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1

3:2:1 Crack Spread  

Gasoline and Diesel Fuel Update (EIA)

:2:1 Crack Spread :2:1 Crack Spread Figure 1 Source: U.S. Energy Information Administration, based on Thomson Reuters. A crack spread measures the difference between the purchase price of crude oil and the selling price of finished products, such as gasoline and distillate fuel, that a refinery produces from the crude oil. Crack spreads are an indicator of the short-term profit margin of oil refineries because they compare the cost of the crude oil inputs to the wholesale, or spot, prices of the outputs (although they do not include other variable costs or any fixed costs). The 3:2:1 crack spread approximates the product yield at a typical U.S. refinery: for every three barrels of crude oil the refinery processes, it makes two barrels of gasoline and one barrel of distillate

2

Spark Spread  

Gasoline and Diesel Fuel Update (EIA)

Spark Spread Spark Spread Figure 1 Source: U.S. Energy Information Administration, based on SNL Energy. The spark spread is a common metric for estimating the profitability of natural gas-fired electric generators. The spark spread is the difference between the price received by a generator for electricity produced and the cost of the natural gas needed to produce that electricity. It is typically calculated using daily spot prices for natural gas and power at various regional trading points. The chart above shows spark spreads during 2012, calculated for four locations around the United States. Spark spreads tend to be fairly volatile, more so than crack spreads in petroleum markets, largely because of the volatility of wholesale electric power prices, which vary widely

3

Cracking knuckles  

NLE Websites -- All DOE Office Websites (Extended Search)

Cracking knuckles Cracking knuckles Name: Renee Knuckles Location: N/A Country: N/A Date: N/A Question: Does cracking your joints especially the knuckles cause arthritis? What are some of the results of doing so? Replies: Cracking knuckles has NEVER been associated with causing arthritis. This concept is as wrong as saying weight lifting makes you short, or playing basketball makes you tall. The "popping" of the knuckles results from forcing joint fluid to very rapidly pass from one side of the joint to the other, where the "sides" are partitioned off by the main bones of the joint. Let me rephrase that: a joint is an area where two or more separate and distinct bones meet. The joint fluid provides a cushioning between the joints so that they don't grate into each other. Cracking your knuckles forces the joint fluid from one part of the joint to another, and the popping sound is just the result of the high pressured rushing of fluid.

4

Steady State Crustal Spreading  

Science Journals Connector (OSTI)

... form at the axis of a mid-ocean ridge and ride down the continuously foundering "conveyor belt" toward the abyssal plains2. As soon, as vulcanism ceases, wave erosion begins ... ascended mantle material spreading from the axis of a ridge, the sinking rate of a parcel of oceanic crust may be only a function of time after extrusion. In that ...

PETER R. VOGT; NED A. OSTENSO

1967-08-19T23:59:59.000Z

5

Elevated temperature crack propagation  

SciTech Connect

This paper is a summary of two NASA contracts on high temperature fatigue crack propagation in metals. The first evaluated the ability of fairly simple nonlinear fracture parameters to correlate crack propagation. Hastelloy-X specimens were tested under isothermal and thermomechanical cycling at temperatures up to 980 degrees C (1800 degrees F). The most successful correlating parameter was the crack tip opening displacement derived from the J-integral. The second evaluated the ability of several path-independent integrals to correlate crack propagation behavior. Inconel 718 specimens were tested under isothermal, thermomechanical, temperature gradient, and creep conditions at temperatures up to 650 degrees C (1200 degrees F). The integrals formulated by Blackburn and by Kishimoto correlated the data reasonably well under all test conditions.

Orange, T.W.

1994-02-01T23:59:59.000Z

6

Hybrid spread spectrum radio system  

DOE Patents (OSTI)

Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

Smith, Stephen F. (London, TN) [London, TN; Dress, William B. (Camas, WA) [Camas, WA

2010-02-09T23:59:59.000Z

7

Crack propagation in Hastelloy X  

SciTech Connect

The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 650/sup 0/C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air.

Weerasooriya, T.; Strizak, J.P.

1980-05-01T23:59:59.000Z

8

Crack Fundamental Element (CFE) for Multi-scale Crack Classification  

Science Journals Connector (OSTI)

With the advance of sensor and information technology, high-resolution 2D image and 3D range data are available to support crack classification. However, crack classification still remains a challenge because sta...

Yuchun Huang; Yichang (James) Tsai

2012-01-01T23:59:59.000Z

9

Reflective Cracking Study: Summary Report  

E-Print Network (OSTI)

Cracking Study: First-level Report on Laboratory ShearStudy: Second-Level Analysis Report. Davis and Berkeley, CA:Cracking Study: First-level Report on HVS Testing on Section

Jones, David; Harvey, John T; Monismith, Carl L.

2008-01-01T23:59:59.000Z

10

Stress corrosion crack growth in porous sandstones.   

E-Print Network (OSTI)

Stress corrosion crack growth occurs when the chemical weakening of strained crack tip bonds facilitates crack propagation. I have examined the effect of chemical processes on the growth of a creack population by carrying out triaxial compression...

Ojala, Ira O

11

Spreading dynamics in complex networks  

Science Journals Connector (OSTI)

Searching for influential spreaders in complex networks is an issue of great significance for applications across various domains, ranging from epidemic control, innovation diffusion, viral marketing, and social movement to idea propagation. In this paper, we first display some of the most important theoretical models that describe spreading processes, and then discuss the problem of locating both the individual and multiple influential spreaders respectively. Recent approaches in these two topics are presented. For the identification of privileged single spreaders, we summarize several widely used centralities, such as degree, betweenness centrality, PageRank, k-shell, etc. We investigate the empirical diffusion data in a large scale online social community—LiveJournal. With this extensive dataset, we find that various measures can convey very distinct information of nodes. Of all the users in the LiveJournal social network, only a small fraction of them are involved in spreading. For the spreading processes in LiveJournal, while degree can locate nodes participating in information diffusion with higher probability, k-shell is more effective in finding nodes with a large influence. Our results should provide useful information for designing efficient spreading strategies in reality.

Sen Pei; Hernán A Makse

2013-01-01T23:59:59.000Z

12

FOREIGN INVESTMENT: Commerce Cracks Down  

Science Journals Connector (OSTI)

FOREIGN INVESTMENT: Commerce Cracks Down ... U.S. companies "will have to learn to live with" some form of mandatory federal controls on direct overseas investments "for at least a few years." ...

1968-09-02T23:59:59.000Z

13

Peridynamic model for fatigue cracking.  

SciTech Connect

The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the %22remaining life%22 of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

Silling, Stewart A.; Abe Askari (Boeing)

2014-10-01T23:59:59.000Z

14

Cracking behavior of cored structures  

SciTech Connect

The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a composition gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Data on stress corrosion cracking and fatigue crack growth in selected FCC alloys are used to illustrate the significance of microsegregation on mechanical properties.

Wahid, A.; Olson, D.L.; Matlock, D.K. (Colorado School of Mines, Golden, CO (United States). Center for Welding and Joining Research); Kelly, T.J. (General Electric Aircraft Engines, Evendale, OH (United States))

1991-01-01T23:59:59.000Z

15

Crack propagation driven by crystal growth  

SciTech Connect

Crystals that grow in confinement may exert a force on their surroundings and thereby drive crack propagation in rocks and other materials. We describe a model of crystal growth in an idealized crack geometry in which the crystal growth and crack propagation are coupled through the stress in the surrounding bulk solid. Subcritical crack propagation takes place during a transient period, which may be very long, during which the crack velocity is limited by the kinetics of crack propagation. When the crack is sufficiently large, the crack velocity becomes limited by the kinetics of crystal growth. The duration of the subcritical regime is determined by two non-dimensional parameters, which relate the kinetics of crack propagation and crystal growth to the supersaturation of the fluid and the elastic properties of the surrounding material.

A. Royne; Paul Meaking; A. Malthe-Sorenssen; B. Jamtveit; D. K. Dysthe

2011-10-01T23:59:59.000Z

16

To Crack or Not to Crack: Strain in High Temperature Superconductors  

E-Print Network (OSTI)

Strain in High Temperature Superconductors Arno GodekeCrack: Strain in High Temperature Superconductors MotivationCrack: Strain in High Temperature Superconductors How do Nb

Godeke, Arno

2008-01-01T23:59:59.000Z

17

Nonlinear structural crack growth monitoring  

DOE Patents (OSTI)

A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

Welch, Donald E. (Oak Ridge, TN); Hively, Lee M. (Philadelphia, TN); Holdaway, Ray F. (Clinton, TN)

2002-01-01T23:59:59.000Z

18

Hybrid spread spectrum radio system  

DOE Patents (OSTI)

Systems and methods are described for hybrid spread spectrum radio systems. A method includes modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control an amplification circuit that provides a gain to the signal. Another method includes: modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control a fast hopping frequency synthesizer; and fast frequency hopping the signal with the fast hopping frequency synthesizer, wherein multiple frequency hops occur within a single data-bit time.

Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)

2010-02-02T23:59:59.000Z

19

Crack propagation in hydrided zircaloy-2  

Science Journals Connector (OSTI)

Transmission electron microscope observations of cracks in thin foils of Zircaloy—2 which contains hydride particles have shown that the fracture process is one of linking up satellite cracks in the hydride ph...

G. Östberg

1968-06-01T23:59:59.000Z

20

A Kinetic model of crack fusion  

Science Journals Connector (OSTI)

......Research Note A Kinetic model of crack fusion Zbigniew Czechowski Institute of Geophysics...presents a kinetic approach to the problem of fusion of cracks. A kinetic equation for the...repetitive episodes of seismicity. crack fusion|kinetic model|seismicity| References......

Zbigniew Czechowski

1991-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Stiffness reduction and stress transfer in composite laminates with transverse matrix cracks  

E-Print Network (OSTI)

-staggered cracking. Laminates with staggered cracks showed a greater reduction in effective modulus at lower crack densities. The crack opening displacements at different crack densities were normalized in a way as to compare with the solution for an isolated crack...

Praveen, Grama Narasimhaprasad

2012-06-07T23:59:59.000Z

22

Gradual Spread of Market-Led Industrialization  

E-Print Network (OSTI)

Gradual Spread of Market-Led Industrialization Jeffrey D. Sachs and Xiaokai Yang CID Working Paper Paper no. 11 Gradual Spread of Market-Led Industrialization Jeffrey D. Sachs and Xiaokai Yang* Abstract the network effects of industrialization, though this function is not perfect. Hence, market led

23

White Etching Cracks | Argonne National Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Etching Cracks Presented by Walter Holweger of Schaeffler at the Wind Turbine Tribology Seminar 2014. NREL Chicago291014Holweger26nosec...

24

Combustion in cracks of PBX 9501  

SciTech Connect

Recent experiments involving the combustion of PBX 9501 explosive under confined conditions reveal the importance of crack and flaws in reaction violence. Experiments on room temperature confined disks of pristine and thermally damaged PBX 9501 reveal that crack ignition depends on hot gases entering existing or pressure induced cracks rather than on energy release at the crack tip. PBX 9501 slot combustion experiments show that the reaction propagation rate in the slot does not depend on the external pressure. We have observed 1500 d s in long slots of highly-confined PBX 9501. We present experiments that examine the combustion of mechanically and thermally damaged samples of PBX 9501.

Berghout, H. L. (Henry L.); Son, S. F. (Steven F.); Bolme, C. A. (Cynthia A.); Hill, L. G. (Larry G.); Asay, B. W. (Blaine W.); Dickson, P. M. (Peter M.); Henson, B. F. (Bryan F.); Smilowitz, L. B. (Laura B.)

2002-01-01T23:59:59.000Z

25

Biomaterials 24 (2003) 52095221 Crack blunting, crack bridging and resistance-curve fracture  

E-Print Network (OSTI)

Biomaterials 24 (2003) 5209­5221 Crack blunting, crack bridging and resistance-curve fracture focused on a description of the fracture toughness properties of dentin in terms of resistance-curve (R-curve) behavior, i.e., fracture resistance increasing with crack extension, particularly in light of the relevant

Ritchie, Robert

26

Damage spreading in the Ising model  

Science Journals Connector (OSTI)

We present two interesting results regarding damage spreading in ferromagnetic Ising models. First, we show that a damage spreading transition can occur in an Ising chain that evolves in contact with a thermal reservoir. Damage heals at low temperature and spreads at high T. The dynamic rules for the system’s evolution for which such a transition is observed are as legitimate as the conventional rules (Glauber, Metropolis, heat bath). Our second result is that such transitions are not always in the directed percolation universality class.

Haye Hinrichsen and Eytan Domany

1997-07-01T23:59:59.000Z

27

Characterization of Fatigue Cracking and Healing of Asphalt Mixtures  

E-Print Network (OSTI)

Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize...

Luo, Xue

2012-07-16T23:59:59.000Z

28

Effect of Desiccation Cracks on Earth Embankments  

E-Print Network (OSTI)

............................................................................. 4 1.4 Methodology ........................................................................................ 6 1.5 Summary .............................................................................................. 8 1.6 Layout... geometry recorded in literature ..... 17 2.5 Desiccation crack behavior during drying-wetting cycles ................... 29 2.6 Flow through a single crack ................................................................. 30 2.7 Flow through a...

Khandelwal, Siddharth

2012-07-11T23:59:59.000Z

29

Fire spread in concealed foamed plastic insulation  

Science Journals Connector (OSTI)

A test program, jointly sponsored by the Society of the Plastics Industry of Canada and the National Research Council, examined the contribution of plastic foams to fire spread in buildings. The conditions und...

Dr. W. Taylor

1983-08-01T23:59:59.000Z

30

High-Resolution Crack Imaging Reveals Degradation Processes in...  

NLE Websites -- All DOE Office Websites (Extended Search)

Crack Imaging Reveals Degradation Processes in Nuclear Reactor Structural Materials. High-Resolution Crack Imaging Reveals Degradation Processes in Nuclear Reactor Structural...

31

Early stages in the development of stress corrosion cracks  

SciTech Connect

Processes in growth of short cracks and stage I of long stress corrosion cracks were identified and evaluated. There is evidence that electrochemical effects can cause short stress corrosion cracks to grow at rates faster or slower than long cracks. Short cracks can grow at faster rates than long cracks for a salt film dissolution growth mechanism or from reduced oxygen inhibition of hydrolytic acidification. An increasing crack growth rate with increasing crack length could result from a process of increasing crack tip concentration of a critical anion, such as Cl{sup {minus}}, with increasing crack length in a system where the crack velocity is dependent on the Cl{sup {minus}} or some other anion concentration. An increasing potential drop between crack tip and mouth would result in an increased anion concentration at the crack tip and hence an increasing crack velocity. Stage I behavior of long cracks is another early development stage in the life of a stress corrosion crack which is poorly understood. This stage can be described by da/dt = AK{sup m} where da/dt is crack velocity, A is a constant, K is stress intensity and m ranges from 2 to 24 for a variety of materials and environments. Only the salt film dissolution model was found to quantitatively describe this stage; however, the model was only tested on one material and its general applicability is unknown.

Jones, R.H.; Simonen, E.P.

1993-12-01T23:59:59.000Z

32

Relationships between HIV spread and evolution examined  

NLE Websites -- All DOE Office Websites (Extended Search)

3 » 3 » November » Relationships between HIV spread and evolution examined Relationships between HIV spread and evolution examined Thomas Leitner of LANL and collaborators are investigating the development of HIV from the point of contraction onwards. November 14, 2013 Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocytes. The image has been colored to highlight important features. Photo credit: C. Goldsmith, Centers for Disease Control and Prevention. Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocytes. The image has been colored to highlight important features. Photo credit: C. Goldsmith, Centers for Disease Control and Prevention. They are examining the relationships between the spread of the virus in a

33

Stress corrosion cracking of power boiler drums  

Science Journals Connector (OSTI)

This paper deals with the study, analysis and technical diagnosis fundamentals concerning damage induced by stress corrosion cracking. The main repair and safe operation methods for power boiler drums are described; this work being based on plant experience.

Alecsandru Pavel; Alexandru Pelle; Alexandru Epure; Cornel Radulescu; Petric? Baciu; Alexandru Bogdan; Mihai Stefanescu

1991-01-01T23:59:59.000Z

34

Parallel interacting edge cracks under pure bending  

E-Print Network (OSTI)

. Once the applicability of the Williams' equations, have been proved or disproved, the power of the singularity represented by the first term of equation 1. 1 and the polynomial expansion can be truncated in order to extract information... of Williams' approach for the case of cracked bodies under pure bending is demonstrated. Four point bending load is applied on specimens with either a vertical or a slant crack giving Mode I or Mixed Mode I ? II respectively. The existence...

Moran, Ivan

1991-01-01T23:59:59.000Z

35

Studies on fruit cracking of tomatoes  

E-Print Network (OSTI)

STUDIES ON FRUIT CRACKING OF TOMATOES A Thesis Sam Don Cotner Submitted to the Graduate College of' ths Texas A&M University in partial fulfillment of the requirements i' or the degree of MASTER OF SCIENCE January~ 1966 Major Subject...: Horticulture STUDlES ON FRUIT CRACKING OF TOMATOES A Thesis Sam Dcn Cotnsr Approved as to style and content by; (Chairman of tes Member (Head o Department) mbsr) January 1966 TABLE OF CONTENTS Chapter I. INTRODUCTION . II. REVIEW OF LITERATURE Page...

Cotner, Sam Don

1966-01-01T23:59:59.000Z

36

Crack-Size Effects on Cyclic and Monotonic Crack Growth in Polycrystalline Alumina: Quantification of the Role of Grain Bridging  

E-Print Network (OSTI)

-prediction methodologies, it is necessary in many materials that the subcritical crack-growth and toughness propertiesCrack-Size Effects on Cyclic and Monotonic Crack Growth in Polycrystalline Alumina: Quantification propagation has been quantitatively examined in a 99.5% pure alumina. Fatigue-crack growth properties for both

Ritchie, Robert

37

Spread of Detonation in High Explosives  

Science Journals Connector (OSTI)

... In a note1 on the spread of detonation in a mass of high explosive from the point of initiation, Weibull demonstrates that, ... initiation, Weibull demonstrates that, in a cylindrical cartridge of compressed T.N.T., detonation is propagated with a uniform and constant speed in all directions from the detonator. ...

DUGALD MITCHELL; STEWART PATERSON

1947-09-27T23:59:59.000Z

38

Environmental performance indicators of organic spreading machines  

E-Print Network (OSTI)

industrial and agronomical databases but the LCA agricultural machinery database is not well adapted-03150 Montoldre, France 2 Chambre d'Agriculture de Bretagne, Station des Cormiers, F-35140 Saint Aubin impacts generated by organic product spreading is obtained from Life Cycle Assessment (LCA). LCA uses

Paris-Sud XI, Université de

39

Modeling of LNG Pool Spreading and Vaporization  

E-Print Network (OSTI)

.............................................................................. 20 CHAPTER III PREVIOUS EXPERIMENTS ON LNG POOL SPREADING .............. 22 3.1. Summary of Experiments on liquefied gases ................................................... 22 CHAPTER IV CURRENT STATE OF THE ART... of liquefied gases into bunds .................................................................... 23 Table 7: Experimental setup for bund experiments.......................................................... 23 Table 8: Spills of liquefied gases onto water...

Basha, Omar 1988-

2012-11-20T23:59:59.000Z

40

Fracture mechanics and subcritical crack growth approach to model time-dependent failure in brittle rock.  

E-Print Network (OSTI)

??Subcritical crack growth (SCG) takes place when a crack is stressed below its short-term strength. This slow fracturing process may lead to an accelerating crack… (more)

Rinne, Mikael

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

E-Print Network 3.0 - axially cracked pressure Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Collection: Engineering 2 MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK Summary: under axial impact with a crack in the central disk....

42

E-Print Network 3.0 - anomolous fatigue crack Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Science ; Engineering 6 Cracking Resistance of Asphalt Rubber Mix Versus Summary: vs. Fracture Mechanics Conventional Fatigue Testing Crack initiation Fracture Mechanics Crack......

43

Interfacial and near interfacial crack growth phenomena in metal bonded alumina  

E-Print Network (OSTI)

studies looking at subcritical crack growth at interfaces,An understanding of subcritical crack growth is important,the amount of subcritical crack growth data that could be

Kruzic, Jamie Joseph

2002-01-01T23:59:59.000Z

44

Prevent the Spread of Zoonotic Diseases  

E-Print Network (OSTI)

Take Precautions when Handling and Caring for Animals During routine care of animals, take the following precautions against spread- ing germs that cause diseases. Wear personal protective clothing and equipment Personal protective clothing, boots..., and equipment can reduce the risk of exposing other animals or people to contagious diseases. Wear boots and a set of protective clothing that you wear only when ? handling and caring for animals. Examples are hat ? coveralls ? long-sleeved shirt (cotton...

Pena, Josefa

2008-11-10T23:59:59.000Z

45

Crack detection using resonant ultrasound spectroscopy  

DOE Patents (OSTI)

Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component. 5 figs.

Migliori, A.; Bell, T.M.; Rhodes, G.W.

1994-10-04T23:59:59.000Z

46

How Do You Spread the Word About Saving Energy? | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Do You Spread the Word About Saving Energy? How Do You Spread the Word About Saving Energy? May 25, 2012 - 2:03pm Addthis Earlier this week, Drew talked about how you can follow...

47

Dynamics of Information Spreading in Online Social Networks  

E-Print Network (OSTI)

Online social networks (OSNs) are changing the way information spreads throughout the Internet. A deep understanding of information spreading in OSNs leads to both social and commercial benefits. In this paper, dynamics of information spreading (e.g., how fast and widely the information spreads against time) in OSNs are characterized, and a general and accurate model based on Interactive Markov Chains (IMCs) and mean-field theory is established. This model shows tight relations between network topology and information spreading in OSNs, e.g., the information spreading ability is positively related to the heterogeneity of degree distributions whereas negatively related to the degree-degree correlations in general. Further, the model is extended to feature the time-varying user behavior and the ever-changing information popularity. By leveraging the mean-field theory, the model is able to characterize the complicated information spreading process (e.g., the dynamic patterns of information spreading) with six pa...

Zhang, Sai; Chen, Xi; Liu, Xue

2014-01-01T23:59:59.000Z

48

Performance degradation of OFDM systems due to Doppler spreading  

E-Print Network (OSTI)

on Jakes’ model for the Doppler effects, and an exponentialand S. Kaiser, “The effects of Doppler spreads in OFDM (A)In particular, the effect of Doppler spreading destroys the

Wang, T J; Proakis, J G; Masry, E; Zeidler, James R

2006-01-01T23:59:59.000Z

49

Alternative Fuels Data Center: EV Charging Stations Spread Through Philly  

Alternative Fuels and Advanced Vehicles Data Center (EERE)

EV Charging Stations EV Charging Stations Spread Through Philly to someone by E-mail Share Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on Facebook Tweet about Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on Twitter Bookmark Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on Google Bookmark Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on Delicious Rank Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on Digg Find More places to share Alternative Fuels Data Center: EV Charging Stations Spread Through Philly on AddThis.com... March 3, 2012 EV Charging Stations Spread Through Philly W atch how Philadelphia fuels electric vehicles with a growing network of

50

Fatigue Enhancement of Undersized, Drilled Crack-Arrest Holes  

E-Print Network (OSTI)

Fatigue cracks occur in steel bridges from repeated loads. If allowed to continue to grow, eventually the fatigue cracks will require either expensive repairs or reduction of traffic loads on the bridge, or they may lead ...

Simmons, Gary Gene

2013-12-31T23:59:59.000Z

51

Dynamical fracture instabilities due to local hyperelasticity at crack tips  

Science Journals Connector (OSTI)

... a crack propagating through a brittle material increases, a dynamical instability leads to an increased roughening of the fracture surface. Cracks moving at low speeds create atomically flat mirror-like ...

Markus J. Buehler; Huajian Gao

2006-01-19T23:59:59.000Z

52

Reflective cracking of shear keys in multi-beam bridges  

E-Print Network (OSTI)

strength to resist cracking from vehicular loads, but uneven temperature changes and shrinkage strains cause high tensile stresses in the shear key regions and lead to reflective cracking. The analyses showed the highest stresses were often times near...

Sharpe, Graeme Peter

2009-06-02T23:59:59.000Z

53

Information Spreading on Almost Torus Networks Antonia Maria Masucci 1  

E-Print Network (OSTI)

in the spread of a viral message and the authors of [6, 7, 8] have identified some conditions for successful

54

Quantitative Spreading Kinetics of a Three Molecular Layer Liquid Patch  

Science Journals Connector (OSTI)

Quantitative Spreading Kinetics of a Three Molecular Layer Liquid Patch ... The late stage kinetics of the spreading of a smectic nanodrop on a solid surface was investigated by direct and real time imaging of a three molecular layer patch using the SEEC microscopy. ... (15) At some stage of the spreading kinetics, the structure reduces to a single bilayer patch lying on the surface monolayer. ...

Olivier Noel; Jean-Luc Buraud; Laurent Berger; Dominique Ausserre?

2010-03-19T23:59:59.000Z

55

Digital radiographic systems detect boiler tube cracks  

SciTech Connect

Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

Walker, S. [EPRI, Charlotte, NC (United States)

2008-06-15T23:59:59.000Z

56

NORTHWESTERN UNIVERSITY Autonomous Crack Comparometer Phase II  

E-Print Network (OSTI)

program between the two universities. Thanks are also given to the staff of the Infrastructure Technology Institute and in particular Dan Marron for all his advice and assistance during the project. I would like that daily and weekly weather related crack displacements are greater than those produced by dynamic events

57

CRACKING OF PIc NUCLEAR CONTAINMENT STRUCTURES  

E-Print Network (OSTI)

CRACKING OF PIc NUCLEAR CONTAINMENT STRUCTURES By Sami H. Rizkalla,l Sidney H. Simmonds': and James structures for some Canadian nuclear reactors consist of a heavy concrete base, a cylindrical wall, a ring the design accident pressure. This would result in the walls and dome of the containment being stressed

58

Feedback algorithm for simulation of multi-segmented cracks  

SciTech Connect

In this paper, a method for obtaining a three dimensional crack model from a radiographic image is discussed. A genetic algorithm aiming at close simulation of crack's shape is presented. Results obtained with genetic algorithm are compared to those achieved in authors' previous work. The described algorithm has been tested on both simulated and real-life cracks.

Chady, T.; Napierala, L. [Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, al. Piastow 17, 70-310 Szczecin (Poland)

2011-06-23T23:59:59.000Z

59

ESTABLISHEMENT OF CRACK INDEXES BY ELECTRICAL APPARENT RESISTIVITY DATA  

E-Print Network (OSTI)

ESTABLISHEMENT OF CRACK INDEXES BY ELECTRICAL APPARENT RESISTIVITY DATA A. Samouelian (1,2), I is indeed well adapted to recognize the electrical resistant signature of crack filled by air during-destructive geophysical methods permits a 3D temporal monitoring of the cracking patterns. Electrical resis- tivity

Boyer, Edmond

60

Fracture toughness and fatigue crack growth characteristics of nanotwinned copper  

E-Print Network (OSTI)

fracture and subcritical fatigue crack growth life. Possible mechanistic origins of these trends and the resistance to stable subcritical crack growth under mono- tonic and cyclic loading, especially at lowerFracture toughness and fatigue crack growth characteristics of nanotwinned copper A. Singh a,1 , L

Suresh, Subra

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Dynamic crack response to a localized shear pulse perturbation in brittle amorphous materials: on crack surface roughening  

Science Journals Connector (OSTI)

Linear Elastic Fracture Mechanics (LEFM) provides a coherent framework to evaluate quantitatively the energy flux released at the tip of a growing crack. However, the way in which the crack chooses its path in re...

D. Bonamy; K. Ravi-Chandar

2005-07-01T23:59:59.000Z

62

Increasing jet entrainment, mixing and spreading  

DOE Patents (OSTI)

A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct. 11 figs.

Farrington, R.B.

1994-08-16T23:59:59.000Z

63

Characterization of cracking restraint at sawcut joints using the German Cracking Frame  

E-Print Network (OSTI)

. Cracks Follow Capillary Channels . . 3. Warping stress coefficients (from Bradbury). , 4. Cracks follow capillary channels. 5. Schematic representation of the slab instrumentation. . . . 6. Weather data on the day the bike trail concrete was laid... the curling stresses caused by temperature differentials through the slab, and are used to find the total stress due to bending, in a slab. The Bradbury curling coefficient (Figure 3) was developed by Bradbury in 1938 based on Westergaard analysis. Bradbury...

Vepakomma, Shilpa

2012-06-07T23:59:59.000Z

64

Evolving crack patterns in thin films with the extended finite element method  

E-Print Network (OSTI)

-exist in the film. To describe subcritical crack growth, we prescribe a kinetic law that relates the crack velocity is susceptible to subcritical cracking, obeying a kinetic law that relates the velocity of each crack to its Elsevier Science Ltd. All rights reserved. Keywords: Crack patterns; Subcritical cracking; Thin films

Suo, Zhigang

65

Fracture Modeling of Crack Propagation in Wood and Wood Composites Including Crack Tip Processes and Fiber Bridging Mechanics  

E-Print Network (OSTI)

1 Fracture Modeling of Crack Propagation in Wood and Wood Composites Including Crack Tip Processes and Fiber Bridging Mechanics J. A. Nairn, N. Matsumoto Wood Science & Engineering, Oregon State University wood and wood composites develop process zones often consisting of fibers bridging the crack surfaces

Nairn, John A.

66

Cleavage crack-tip deformation in single-crystal zinc  

Science Journals Connector (OSTI)

Dislocation distribution ahead of a cleavage crack tip in single crystal Zn is observed by using the etch pit technique. The results show that the distribution has the feature predicted by the DFZ models, and both X1, the distance from the crack tip to the first dislocation and N0, the total number of dislocations ahead of the crack tip, agree with Majumdar and Burns's DFZ theory. The problems of dislocation emission from the crack tip and dislocation shielding effects on the crack tip are also discussed based on the experimental results.

Fu Ran; Q Y Long; T Y Zhang; C W Lung

1989-01-01T23:59:59.000Z

67

Cracking of Composite Modified Alloy 825 Primary Air Port Tubes  

SciTech Connect

Twenty primary air ports fabricated from modified Alloy 825-based composite tubes underwent a metallurgical examination to document the mode and extent of cracking on the external fireside surface of a kraft recovery boiler. Collectively, the crack features found are most consistent with thermal fatigue, but corrosion fatigue cannot be ruled out. Regardless of the true cracking mechanism, temperature cycling is implicated as a critical factor for crack propagation. on the basis of the relative crack lengths observed, membrane welds and tube weld repairs, and their adjacent heat-affected zones, appear to be more susceptible to cracking than the cladding itself. This work suggests that mills should avoid boiler operating conditions that promote large temperature fluctuations, which can cause Alloy 825-based composite tubes to crack.

Kish, Joseph R. [Paprican; Keiser, James R [ORNL; Singbeil, Douglas [Paprican; Willoughby, Adam W [ORNL; Longmire, Hu Foster [ORNL

2007-04-01T23:59:59.000Z

68

Equatorial spread {ital F} effects on an HF path: Doppler spread, spatial coherence, and frequency coherence  

SciTech Connect

In August 1990 we participated in the Equatorial Ionospheric Studies sounding rocket campaign near Kwajalein Atoll in the equatorial Pacific region. The campaign included measurements of plasma density using rocket probes and coherent and incoherent scatter radar. During the campaign we fielded high-frequency ionospheric sounders over a bistatic path between Maloelap Atoll and Bikini Atoll in the Marshall Islands. The distance between the transmitters and receivers was 700 km; the ionospheric-reflection region was at 10.18; {degree}N, 168.40;{degree}E, near the magnetic equator. We made three types of measurements: Doppler spread and spatial coherence for a single-frequency CW path; frequency coherence of multiple CW paths; and Doppler spread and time-delay spread for a 60-kHz bandwidth path. We obtained such data over a period of 2 weeks for approximately 2 hours each evening; during this period spread {ital F} was common. Fifty percent of the evenings showed Doppler spread of greater than 6 Hz at the {minus}10 dB level (relative to the peak signal power) and greater than 15 Hz at the {minus}30 dB level. Forty percent of the evenings showed spatial coherence distance of less than 180 m in the direction normal to the bistatic path; 40{percent} of the evenings showed spatial coherence of less than 75 m in the direction parallel to the path. Seventy-five percent of the evenings showed coherence bandwidths of less than 1.5 kHz. {copyright} 1999 American Geophysical Union

Fitzgerald, T.J.; Argo, P.E.; Carlos, R.C. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)

1999-01-01T23:59:59.000Z

69

Process for magnetic beneficiating petroleum cracking catalyst  

DOE Patents (OSTI)

A process for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded.

Doctor, Richard D. (Lisle, IL)

1993-01-01T23:59:59.000Z

70

Process for magnetic beneficiating petroleum cracking catalyst  

DOE Patents (OSTI)

A process is described for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded. 1 figures.

Doctor, R.D.

1993-10-05T23:59:59.000Z

71

Fluid catalytic cracking of heavy petroleum fractions  

SciTech Connect

A process is claimed for fluid catalytic cracking of residuum and other heavy oils comprising of gas oil, petroleum residue, reduced and whole crudes and shale oil to produce gasoline and other liquid products which are separated in various streams in a fractionator and associated vapor recovery equipment. The heat from combustion of coke on the coked catalyst is removed by reacting sulfur-containing coke deposits with steam and oxygen in a separate stripper-gasifier to produce a low btu gas stream comprising of sulfur compounds, methane, carbon monoxide, hydrogen, and carbon dioxide at a temperature of from about 1100/sup 0/F. To about 2200/sup 0/F. The partially regenerated catalyst then undergoes complete carbon removal in a regeneration vessel. The regenerated catalyst is recycled for re-use in the cracking of heavy petroleum fractions. The liquid products are gasoline, distillates, heavy fuel oil, and light hydrocarbons.

McHenry, K.W.

1981-06-30T23:59:59.000Z

72

Static strength assessment of cracked tubular joints  

SciTech Connect

Results from a number of investigations on the ultimate capacity of cracked tubular joints are available. A comparison of the results with predictions from parametric equations for the static strength capacity of intact joints indicates that the presence of a defect can have a significant influence on the joint capacity. The data, which were obtained from experiments on small-scale and large-scale tests and numerical analyses, are assessed in this paper. A range of tubular joint geometries containing surface and through-thickness cracks are considered. The data are assessed with respect to characteristic static strength predictions and fracture mechanics predictions based on the use of the Failure Assessment Diagram approach. Finally, an outline of current research in this area is presented.

Stacey, A.; Sharp, J.V. [Health and Safety Executive, London (United Kingdom). Offshore Safety Div.; Nichols, N.W. [AEA Technology, Culham (United Kingdom)

1996-12-01T23:59:59.000Z

73

Subcritical crack growth in fibrous materials  

E-Print Network (OSTI)

We present experiments on the slow growth of a single crack in a fax paper sheet submitted to a constant force $F$. We find that statistically averaged crack growth curves can be described by only two parameters : the mean rupture time $\\tau$ and a characteristic growth length $\\zeta$. We propose a model based on a thermally activated rupture process that takes into account the microstructure of cellulose fibers. The model is able to reproduce the shape of the growth curve, the dependence of $\\zeta$ on $F$ as well as the effect of temperature on the rupture time $\\tau$. We find that the length scale at which rupture occurs in this model is consistently close to the diameter of cellulose microfibrils.

Santucci, Stéphane; Deschanel, Stéphanie; Vanel, Loic; Ciliberto, Sergio

2006-01-01T23:59:59.000Z

74

Structures for dense, crack free thin films  

DOE Patents (OSTI)

The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

2011-03-08T23:59:59.000Z

75

Golden Spread Panhandle Wind Ranch | Open Energy Information  

Open Energy Info (EERE)

Spread Panhandle Wind Ranch Spread Panhandle Wind Ranch Jump to: navigation, search Name Golden Spread Panhandle Wind Ranch Facility Golden Spread Panhandle Wind Ranch Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner Golden Spread Electric Cooperative Developer Cielo Energy Purchaser Golden Spread Electric Cooperative Location Wildarado TX Coordinates 35.22770741°, -102.2323751° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":35.22770741,"lon":-102.2323751,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

76

Method and apparatus for generating a natural crack  

DOE Patents (OSTI)

A method and apparatus for generating a measurable natural crack includes forming a primary notch in the surface of a solid material. A nonsustained single pressure pulse is then generated in the vicinity of the primary notch, reuslting in the formation of a shock wave which travels through the material. The shock wave creates a measurable natural crack within the material which extends from the primary notch. The natural crack formed possesses predictable geometry, location and orientation.

Fulton, F.J.; Honodel, C.A.; Holman, W.R.; Weingart, R.C.

1982-05-06T23:59:59.000Z

77

Vibration Diagnosis of Elastic Shafts with A Transverse Crack.  

E-Print Network (OSTI)

??Detection of the shaft crack in a rotating machine is one of the most challenging problems in equipment predictive maintenance. In the available literature, various… (more)

Cai, ZHONGYI

2011-01-01T23:59:59.000Z

78

White-Etching Crack Failure Overview, Tomography Analysis, and...  

NLE Websites -- All DOE Office Websites (Extended Search)

White-Etching Crack Failure Overview, Tomography Analysis, and Test Development Presented by Aaron Greco of Argonne National Laboratory at the Wind Turbine Tribology Seminar 2014....

79

Investigation of White Etching Crack (WEC) Formation Mechanisms...  

NLE Websites -- All DOE Office Websites (Extended Search)

Investigation of White Etching Crack (WEC) Formation Mechanisms Under Non-hydrogen Charged Test Conditions Presented by Alex Richardson, Afton Chemical (representing University of...

80

Hot Rolling Scrap Reduction through Edge Cracking and Surface...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

properties as a routine part of design. OEMs design typically with linear elastic fracture mechanics, isotropic crack direction criteria (maximum tensile stress) In...

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Fuzzy decision support system for spread mooring system selection  

Science Journals Connector (OSTI)

Spread mooring systems are associated with high level uncertainties and risks during tanker loading/unloading operations. In addition, the design of such complex systems consists of many subjective and imprecise parameters. Therefore, in the present ... Keywords: AHP, Decision making, Fuzzy multiple attribute decision making, Fuzzy set theory, Spread mooring system, TOPSIS

Ayhan Mentes; Ismail Hakki Helvacioglu

2012-02-01T23:59:59.000Z

82

Towards Understanding Global Spread of Disease from Everyday Interpersonal Interactions  

E-Print Network (OSTI)

spread of disease. We consider the important task of predicting the prevalence of flu- like illness into the mechanisms of dis- ease spread and significantly improve predictabil- ity of future flu outbreaks. Our media--places em- phasis on predicting which specific individuals will become afflicted with flu

Kautz, Henry

83

Modeling daily flow patterns individuals to characterize disease spread  

SciTech Connect

The effect of an individual's travels throughout a day on the spread of disease is examined using a deterministic SIR model. We determine which spatial and demographic characteristics most contribute to the disease spread and whether the progression of the disease can be slowed by appropriate vaccination of people belonging to a specific location-type.

Smallwood, J. (Jeanine); Hyman, J. M. (James M.); Mirchandani, Pitu B.

2002-11-17T23:59:59.000Z

84

What constrains spread growth in forecasts ini2alized from  

E-Print Network (OSTI)

1 What constrains spread growth in forecasts ini2alized from ensemble Kalman filters? Tom from manner in which ini2al condi2ons are generated, some due to the model (e.g., stochas2c physics as error; part of spread growth from manner in which ini2al condi2ons are generated, some due

Hamill, Tom

85

Wet climate and transportation routes accelerate spread of human plague  

Science Journals Connector (OSTI)

...provides new insights on transmission patterns and possible...behind variability in transmission speed, with implications...plague pandemic|spread route|spread velocity...facilitated spatial transmission of infectious diseases...in circles or along lines away from the central...

2014-01-01T23:59:59.000Z

86

A heavy oil thermal cracking simulation program  

SciTech Connect

Correlations were developed to simulate the thermal cracking reaction of petroleum vacuum distillation residues through pilot plant data analysis. They use charge properties like specific gravity, viscosity, sulphur content and initial boiling point to give the yield and quality of products as a function of conversion, which is measured in terms of wt.% products with normal boiling point below 350{degrees}C. The mixture is represented with 24 lumps, and kinetic parameters for the reaction feed {r_arrow} products were also found as a function of feedstock properties. Finally, a computer program was developed to simulate fired heater operation for visbreaking and delayed coking units. 3 refs., 10 figs., 1 tab.

Maciel, R. [UNICAMP, Campinas (Brazil); Sugaya, M.F. [Petrobrais, Rio de Janeiro (Brazil)

1996-12-31T23:59:59.000Z

87

Crack initiation and crack growth resistance of Ti-48Al-2Cr sheet material  

SciTech Connect

The present paper reports on the fracture toughness tests conducted on Ti-48Al-2Cr sheet material with near-gamma microstructure produced by hot rolling. Compact tension specimens were sectioned from sheet material and tested at room temperature to determine the fracture toughness and crack growth resistance curves. The deformation and fracture behavior were studied on tested specimens.

Dogan, B.; Schwalbe, K.H. [GKSS Research Centre, Geesthacht (Germany)] [GKSS Research Centre, Geesthacht (Germany); Clemens, H. [Plansee AG, Reutte (Austria)] [Plansee AG, Reutte (Austria)

1998-03-03T23:59:59.000Z

88

An evaluation of crack front effect on threshold and crack propagation  

SciTech Connect

That a through-thickness crack may exhibit over the entire fatigue crack propagation (FCP) regime morphological variations such as curvature, deviation and deflection appears to be very common. This effect is hereafter referred to as the crack front effect (CFE). It includes the practical consequence that when CFE occurs, local crack length, and hence the surface and the through-thickness data derived, tend to differ. Apparently, the difference should not be significant a least for thin specimens, for which data acquisition on one face suffices, and therefore, problems resulting from CFE can be neglected in certain cases. The authors became involved in the CFE problem while studying hysteresis effects in the threshold regime, particularly when post-threshold non-propagation was observed on the surface. In brief, the specimens had a section thickness of 4mm, i.e., relatively thin (B/W = 0.066), and according to the ASIM test recommendations the surface data should have been accurate. The major questions which arose were, however, whether surface and through-thickness effects are comparable, and how reliable surface observations are. Pure copper was chosen as the material since it exhibits a mixed mode fracture path, and thus should be inherently prone to yield CFE.

Vaidya, W.V.

1989-01-01T23:59:59.000Z

89

Cincinnati Canvassing Spreads Retrofitting Message | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Cincinnati Canvassing Spreads Retrofitting Message Cincinnati Canvassing Spreads Retrofitting Message Cincinnati Canvassing Spreads Retrofitting Message May 28, 2010 - 3:07pm Addthis A volunteer canvasses the Mt. Washington neighborhood to spread awareness about home energy audits in the area. | Photo Courtesy GCEA A volunteer canvasses the Mt. Washington neighborhood to spread awareness about home energy audits in the area. | Photo Courtesy GCEA Lindsay Gsell What are the key facts? With help from the Greater Cincinnati Energy Alliance (GCEA), this resident was able to get his home energy audited for only $50, saving approximately $300 from the average audit cost. Stuart Schaefer's home sits on a quaint, tree-lined street in Wyoming, Ohio. Although he's always enjoyed the neighborhood and his house in the

90

Corrosion-fatigue crack growth behavior of surface crack on AH36 TMCP steel weld in seawater  

SciTech Connect

Fatigue crack growth behavior in seawater of surface crack on the weld was studied with a structural steel, AH36, manufactured by the thermo-mechanical control process (TMCP). Crack growth rate was measured for the surface cracks located in different regions of weld, such as the heat affected zone, the weld metal and the base metal. Influence of the welding condition was investigated with the variation of heat inputs of 80, 120 and 180 kJ/cm. Electrochemical analysis of each region of the weld was also performed to investigate the corrosion behavior between the weld and the base metal.

Kweon, Y.G.; Jeong, H.D.; Chang, R.W. [Research Inst. of Industrial Science and Technology, Pohang (Korea, Republic of). Welding Research Center

1995-12-31T23:59:59.000Z

91

CIRCUMFERENTIAL MFL IN-LINE INSPECTION FOR CRACKS IN PIPELINES  

SciTech Connect

Circumferential MFL is a new implementation of a widely used technology that has potential to provide improved detection and quantification of axially oriented defects such as cracks, seam weld defects, mechanical damage, and groove corrosion. This implementation works by orienting the magnetic field around the pipe rather that along the axis. By orienting the magnetic field around the pipe (the circumferential direction), the axial defects that were magnetically transparent can disrupt more of the magnetic field and can be more easily detected. Initial implementations of circumferential MFL have found that flux leakage from cracks at the interior of the pipe is small, and the signals from cracks are difficult to detect. The objective of this project is to improve detection of cracks by changing the implementation along with using data from overlapping and complementary inspection techniques. Two technology enhancements were investigated: Combining high- and low-magnetization technology for stress detection; and Combining axial and circumferential MFL methods. Although a method combining high- and low-magnetization technology showed promise for characterizing gouges cause by third party excavation equipment, its commercial development was not successful for two reasons. First, the stress diminishes the crack signal, while the opening of the crack increases the signal. The stress-induced changes in flux leakage around cracks were small and any critical information on the severity of cracks and crack-like defects is difficult to distinguish from changes caused by the crack opening and other inspection variables. Second, it is difficult to magnetize pipe material in the circumferential direction. A relatively low, non-uniform magnetization level produced by the circumferential magnetizer makes detection of changes due to stress extremely difficult. This project also examined combining axial and circumferential MFL to improve crack detection and distinguish cracks for axially oriented volumetric defects. While successful results are presented in this report, circumferential MFL can only detect larger cracks. Even with the field aligned properly, circumferential MFL technology has difficulty detecting cracks on the outside surface that have the potential to grow to failure. Circumferential MFL can be used to detect many corrosion, mechanical damage, and crack defects. However, the detection capabilities and sizing accuracies may not be sufficient for all pipeline threats. Inspection tools that use more sophisticated technologies for detecting and sizing defects may have better performance capabilities, but will likely be expensive to operate. Circumferential MFL will be useful in identifying locations for detailed testing. While performance enhancements may be limited, circumferential MFL inspections will be part of the inspection process for many decades.

J.B. Nestleroth

2003-06-01T23:59:59.000Z

92

E-Print Network 3.0 - applications crack growth Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

that the critical crack-tip opening angle (CTOA) value measured on the specimen... fracture changes a Mode-I type of crack growth to a mixed-mode IIII type of crack growth. It...

93

A nanomechanical investigation of the crack tip process zone of marble  

E-Print Network (OSTI)

This study explores the interaction between crack initiation and nanomechanical properties in the crack tip process zone (zone of microcracking at the tip of a propagating crack) of a brittle geomaterial. Samples of Carrara ...

Brooks, Zenzile (Zenzile Z.)

2010-01-01T23:59:59.000Z

94

Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions  

E-Print Network (OSTI)

S.B. , 1999. Subcritical crack growth in silicon MEMS. J.appearance of subcritical crack growth in the absence ofbe mistaken for subcritical fatigue-crack growth when the

Muhlstein, C.L.; Howe, R.T.; Ritchie, R.O.

2001-01-01T23:59:59.000Z

95

Propagating solitary waves along a rapidly moving crack front  

Science Journals Connector (OSTI)

... Much recent research has focused on crack front coherence and roughening. Simplified models (mode III) of fracture as well as more general models of ... the cumulative effect of numerous asperities would be to cause a crack front to continually roughen. We point out that despite this possibility of increasing roughness, the propagating nature of ...

Eran Sharon; Gil Cohen; Jay Fineberg

2001-03-01T23:59:59.000Z

96

Fracture mechanics analysis of slow crack growth in polyethylene  

E-Print Network (OSTI)

Slow crack growth in polyethylene is often the limiting factor in long-term service of plastic pipe or other structural applications. A new test method and analysis method was developed to study slow crack growth in polyethylene. Two high density...

Self, Robert Alan

1997-01-01T23:59:59.000Z

97

The Influence of Crystallographic Orientation on Crack Tip Displacements of  

E-Print Network (OSTI)

consists of 212 randomly shaped, sized and oriented grains, loaded monotonically in uniaxial tension to a maximum load of 0.9Rp0.2 (240 MPa). The influence that a random grain structure imposes on a Stage I crack will preferably follow the slip plane where the crack tip opening displacement is highest, we show

Cizelj, Leon

98

Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models  

SciTech Connect

The Ford/Andresen slip dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material condition. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L.

1995-02-22T23:59:59.000Z

99

Modeling of pool spreading of LNG on land  

Science Journals Connector (OSTI)

Abstract This paper presents a source term model for estimating the rate of spreading of LNG and other cryogenic mixtures on unconfined land. The model takes into account the composition changes of a boiling mixture, the varying thermodynamic properties due to preferential boiling within the mixture and the effect of the various boiling regimes on conductive heat transfer. A sensitivity analysis is conducted to determine the relative effect of each of these phenomena on pool spread. The model is applied to continuous and instantaneous spills. The model is compared to literature experimental data on cryogenic pool spreading.

Omar Basha; Tomasz Olewski; Luc Véchot; Marcelo Castier; Sam Mannan

2014-01-01T23:59:59.000Z

100

E-Print Network 3.0 - assisted cracking resistance Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

crack... and the time-dependent, environmentally-assisted, crack initiation and subcritical growth in the oxide layer... of exploring these prin- ciples is seen in Figure 5....

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone  

E-Print Network (OSTI)

in the presence of subcritical crack growth. It involvesgrowth (not crack initiation). As a result, stable (subcritical)

Zimmermann, Elizabeth A.

2010-01-01T23:59:59.000Z

102

Insights into Stress Corrosion Cracking Mechanisms from High-Resolution Measurements of Crack-Tip Structures and Compositions  

SciTech Connect

The fundamental basis for mechanistic understanding and modeling of SCC remains in question for many systems. Specific mechanisms controlling SCC can vary with changes in alloy characteristics, applied/residual stress or environmental conditions. The local crack electrochemistry, crack-tip mechanics and material metallurgy are the main factors controlling crack growth. These localized properties are difficult or impossible to measure in active cracks. Nevertheless, it is essential to quantitatively interrogate these crack-tip conditions if mechanistic understanding is to be obtained. A major recent advance has been the ability to investigate SCC cracks and crack tips using high-resolution ATEM techniques. ATEM enables the characterization of SCC cracks including trapped tip solution chemistries, corrosion product/film compositions and structures, and elemental composition gradients and defect microstructures along the crack walls and at the crack tip. A wide variety of methods for imaging and analyses at resolutions down to the atomic level can be used to examine the crack and corrosion film characteristics. Surface films and reaction layers have been examined by cross-sectional TEM techniques, but little work had been conducted on environmentally induced internal cracks until that of Lewis and co-workers [1-3] and the current authors [4-17]. This capability combined with modern ATEM techniques has enabled exciting new insights into corrosion processes occurring at buried interfaces and is being used to identify mechanisms controlling IGSCC in boiling water reactor (BWR) and pressurized water reactor (PWR) components. The objective of this paper is to summarize certain results focused on IGSCC of Fe- base and Ni-base stainless alloys in high-temperature water environments. Representative crack-tip examples will be shown to illustrate specific aspects that are characteristic of SCC in the material/environment combinations. Differences and similarities in crack-tip structures- chemistries will be highlighted comparing Fe-base 316/304SS to Ni-base alloy 600/182 and for tests in oxidizing versus hydrogenated water environments.

Bruemmer, Stephen M.; Thomas, Larry E.

2010-04-05T23:59:59.000Z

103

A Gravitational Spreading Origin For The Socompa Debris Avalanche | Open  

Open Energy Info (EERE)

Gravitational Spreading Origin For The Socompa Debris Avalanche Gravitational Spreading Origin For The Socompa Debris Avalanche Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Gravitational Spreading Origin For The Socompa Debris Avalanche Details Activities (0) Areas (0) Regions (0) Abstract: Socompa Volcano arguably provides the world's best-exposed example of a sector collapse-derived debris avalanche deposit. New observations lead us to re-interpret the origin of the sector collapse. We show that it was triggered by failure of active thrust-anticlines in sediments and ignimbrites underlying the volcano. The thrust-anticlines were a result of gravitational spreading of substrata under the volcano load. About 80% of the resulting avalanche deposit is composed of substrata formerly residing under the volcano and in the anticlines. The collapse

104

Tight Product Balance Pushes Up Product Spread (Spot Product - Crude  

Gasoline and Diesel Fuel Update (EIA)

5 5 Notes: Gasoline inventories indicate how tight the gasoline product market is in any one region. When the gasoline market is tight, it affects the portion of gasoline price is the spread between spot product price and crude oil price. Note that in late 1998-and early 1999 spreads were very small when inventories were quite high. Contrast summers of 1998 or 1999 with summer 2000. Last summer's tight markets, resulting low stocks and transition to Phase 2 RFG added price pressure over and above the already high crude price pressure on gasoline -- particularly in the Midwest. As we ended last winter, gasoline inventories were low, and the spread between spot prices and crude oil were higher than typical as a result. Inventories stayed well below average and the spread during the

105

Golden Spread Electric Cooperative, Inc | Open Energy Information  

Open Energy Info (EERE)

Golden Spread Electric Cooperative, Inc Golden Spread Electric Cooperative, Inc Jump to: navigation, search Name Golden Spread Electric Cooperative, Inc Place Amarillo, Texas Utility Id 7349 Utility Location Yes Ownership C NERC Location SPP NERC ERCOT Yes NERC SPP Yes Operates Generating Plant Yes Activity Generation Yes Activity Transmission Yes Activity Buying Transmission Yes Activity Buying Distribution Yes Activity Wholesale Marketing Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] SGIC[2] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Golden Spread Electric Cooperative, Inc. Smart Grid Project was awarded $19,995,000 Recovery Act Funding with a total project value of $49,987,500.

106

Distillate Supply/Demand Balance Reflected in Spreads  

Gasoline and Diesel Fuel Update (EIA)

4 4 Notes: The price spike that initiated the flood of distillate imports last winter can be easily seen in this chart. The distillate supply/demand balance influences the spread between spot distillate and spot crude oil prices. For example, when stocks are higher than normal, the spread will be lower than usual. This spread is the price incentive that encourages or discourages changes in supply. The January/February 2000 price spike was shorter than the one last winter, largely due to the timing. Since last winter's price spike occurred early in the season, it took some time before prices receded substantially. Currently, the distillate fuel refining spread (the difference between the spot heating oil price and the WTI price) is more "typical". But as was

107

Epidemic spreading in time-varying community networks  

SciTech Connect

The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q{sub c}. The epidemic will survive when q?>?q{sub c} and die when q?spreading in complex networks with community structure.

Ren, Guangming, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [School of Electronic and Information, Guangdong Polytechnic Normal University, Guangzhou 510665 (China) [School of Electronic and Information, Guangdong Polytechnic Normal University, Guangzhou 510665 (China); Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn, E-mail: ren-guang-ming@163.com [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)] [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

2014-06-15T23:59:59.000Z

108

spread their Photo:FeraCrownCopyright2011  

E-Print Network (OSTI)

...don't spread their germs! Photo:Fera©CrownCopyright2011 Plants get ill too... For more information please visit www.scotland.gov.uk/planthealth Photo:ForestryCommission©CrownCopyright2011 © Crown

109

Discontinuities in the History of Sea-floor Spreading  

Science Journals Connector (OSTI)

... following. Let X be the distance, measured parallel to the spreading direction, of a parcel of crust from the axis of the mid-ocean ridge. Then a lapse is ... occasional vulcanism and the effects of sedimentation.

ERIC D. SCHNEIDER; PETER R. VOGT

1968-03-30T23:59:59.000Z

110

Competing spreading processes on multiplex networks: awareness and epidemics  

E-Print Network (OSTI)

Epidemic-like spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [Granell et al. Phys. Rev. Lett. 111, 128701 (2013)] presented the analysis of the interrelation between two processes accounting for the spreading of an epidemics, and the spreading of information awareness to prevent its infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease, revealed the existence of a metacritical point at which the critical onset of the epidemics starts depending on the reaching of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between both competing processes for a wide spectrum of parameters representing the interacti...

Granell, Clara; Arenas, Alex

2014-01-01T23:59:59.000Z

111

Analysis of composite tube cracking in recovery boiler floors  

SciTech Connect

Cracking of co-extruded (generally identified as composite) floor tubes in kraft black liquor recovery boilers was first observed in Scandinavia, but this problem has now been found in many North American boilers. In most cases, cracking in the outer 304L stainless steel has not progressed into the carbon steel, but the potential for such crack propagation is a cause of concern. A multidimensional study has been initiated to characterize the cracking seen in composite floor tubes, to measure the residual stresses resulting from composite tube fabrication, and to predict the stresses in tubes under operating conditions. The characterization studies include review of available reports and documents on composite tube cracking, metallographic examination of a substantial number of cracked tubes, and evaluation of the dislocation structure in cracked tubes. Neutron and X-ray diffraction are being used to determine the residual stresses in composite tubes from two major manufacturers, and finite element analysis is being used to predict the stresses in the tubes during normal operation and under conditions where thermal fluctuations occur.

Keiser, J.R.; Taljat, B.; Wang, X.L.; Maziasz, P.J.; Hubbard, C.R.; Swindeman, R.W. [Oak Ridge National Lab., TN (United States); Singbeil, D.L.; Prescott, R. [Pulp and Paper Research Inst. of Canada, Vancouver, British Columbia (Canada)

1996-08-01T23:59:59.000Z

112

Author's personal copy Effect of fluid salinity on subcritical crack propagation in calcite  

E-Print Network (OSTI)

Author's personal copy Effect of fluid salinity on subcritical crack propagation in calcite Fatma Accepted 22 October 2012 Available online 31 October 2012 Keywords: Subcritical crack growth Calcite Salt Damage The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing

113

A three-dimensional validation of crack curvature in muscovite mica  

SciTech Connect

Experimental and computational efforts focused on characterizing crack tip curvature in muscovite mica. Wedge-driven cracks were propagated under monochromatic light. Micrographs verified the subtle curvature of the crack front near the free surface. A cohesive approach was employed to model mixed-mode fracture in a three-dimensional framework. Finite element calculations captured the crack curvature observed in experiment.

J. C. Hill; J. W. Foulk III; P. A. Klein; E. P. Chen

2001-01-07T23:59:59.000Z

114

EFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS  

E-Print Network (OSTI)

, toughness, creep, and subcritical crack growth [1± 10]. Under quasi-static loading, subcritical crack growthEFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS AT ELEVATED allow for consistent crack-growth monitoring in these materials at high temperatures, and even

Ritchie, Robert

115

Cyclic fatigue-crack propagation in sapphire in air and simulated physiological environments  

E-Print Network (OSTI)

for the first time in sapphire for both modes of subcritical cracking. It was found that growth rates were on the subcritical crack-growth prop- erties of sapphire. In general, crack growth in many polycrystalline ce- ramics loads. This article describes an investigation of subcritical crack growth in sapphire under both mon

Ritchie, Robert

116

Environmentally Assisted Cracking of Ni-Base Alloys [Corrosion and  

NLE Websites -- All DOE Office Websites (Extended Search)

LWRs > Environmentally Assisted LWRs > Environmentally Assisted Cracking of Ni-Base Alloys Capabilities Materials Testing Environmentally Assisted Cracking (EAC) of Reactor Materials Corrosion Performance/Metal Dusting Overview Light Water Reactors Fatigue Testing of Carbon Steels and Low-Alloy Steels Environmentally Assisted Cracking of Ni-Base Alloys Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless Steels Steam Generator Tube Integrity Program Air Oxidation Kinetics for Zr-based Alloys Fossil Energy Fusion Energy Metal Dusting Publications List Irradiated Materials Steam Generator Tube Integrity Other Facilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Corrosion and Mechanics of Materials Light Water Reactors

117

Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless  

NLE Websites -- All DOE Office Websites (Extended Search)

Environmentally Assisted Environmentally Assisted Cracking of Ni-Base Alloys Capabilities Materials Testing Environmentally Assisted Cracking (EAC) of Reactor Materials Corrosion Performance/Metal Dusting Overview Light Water Reactors Fatigue Testing of Carbon Steels and Low-Alloy Steels Environmentally Assisted Cracking of Ni-Base Alloys Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless Steels Steam Generator Tube Integrity Program Air Oxidation Kinetics for Zr-based Alloys Fossil Energy Fusion Energy Metal Dusting Publications List Irradiated Materials Steam Generator Tube Integrity Other Facilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Corrosion and Mechanics of Materials Light Water Reactors Bookmark and Share

118

Thermal cracking in disc brakes Thomas J. Mackin *,1  

E-Print Network (OSTI)

Thermal cracking in disc brakes Thomas J. Mackin *,1 , Steven C. Noe, K.J. Ball, B.C. Bedell, D, or hub, which is connected to the wheel and axle, and an inboard and outboard braking surface

Salvaggio, Carl

119

Energy Recovery System for Fluid Catalytic Cracking Units  

E-Print Network (OSTI)

This paper describes the power and heat recovery processes and equipment for modern fluid catalytic cracking (FCC) units made possible by improvements in catalyst fines removal technology and the availability of erosion resistant high temperature...

Wen, H.; Lou, S. C.

1982-01-01T23:59:59.000Z

120

Automated crack control analysis for concrete pavement construction  

E-Print Network (OSTI)

The focus of this research is on the control of random cracking in concrete paving by using sawcut notch locations in the early stages of construction. This is a major concern in concrete pavement construction. This research also addresses a...

Jang, Se Hoon

2005-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Modeling of crack initiation, propagation and coalescence in rocks  

E-Print Network (OSTI)

Natural or artificial fracturing of rock plays a very important role in geologic processes and for engineered structures in and on rock. Fracturing is associated with crack initiation, propagation and coalescence, which ...

Gonçalves da Silva, Bruno Miguel

2009-01-01T23:59:59.000Z

122

Delayed hydride cracking behavior for ZIRCALOY-2 tubing  

Science Journals Connector (OSTI)

The delayed hydride cracking (DHC) behavior for ZIRCALOY-2 tubing was characterized at temperatures ranging from 93 °C to 288 °C. Testing was performed on the three types of pressure tubes that were used in th...

F. H. Huang; W. J. Mills

1991-09-01T23:59:59.000Z

123

Field Examples of Axial Cracked Bearings in Wind Turbine Gearboxes...  

NLE Websites -- All DOE Office Websites (Extended Search)

Field Examples of Axial Cracked Bearings in Wind Turbine Gearboxes Presented by Paul John Baker of FrontierPro Services at the Wind Turbine Tribology Seminar 2014. 141030 Axial...

124

SAFT Imaging of Transverse Cracks in Austenitic and Dissimilar Welds  

Science Journals Connector (OSTI)

Up to now there is no sufficient technique to detect transverse cracks in austenitic and dissimilar welds which recently are of increasing interest in the integrity surveillance of nuclear power plants as well as...

Christian Höhne; Sanjeevareddy Kolkoori…

2013-03-01T23:59:59.000Z

125

Failure analysis of a cracked diesel engine clutch spring plate  

Science Journals Connector (OSTI)

A diesel engine clutch spring plate used in a truck cracked when testing was being performed. The crack initiated from the middle of the thickness direction of the plate and propagated toward the front and the back of the plate. Fractographic studies indicate that brittle intergranular fracture was the dominant failure mechanism. Many parallel band structures were observed along the radial direction of the plate in the intergranular fracture region; a high density of secondary cracks and fine intergranular particles were found in this banded region. Metallurgical examinations indicated segregation of elongated MnS inclusions and the presence of granular vanadium carbides along the radial direction of the plate, at the location of the crack origin. Segregation of the elongated MnS inclusions leads to a reduction in toughness, and the combined segregation of inclusions and impurity elements at grain boundaries result in weakening of the boundaries. These conditions led to the intergranular brittle fracture of the clutch spring plate.

Zhiwei Yu; Xiaolei Xu

2008-01-01T23:59:59.000Z

126

J-integral values for cracks in conventional fatigue specimens  

SciTech Connect

Comprehensive S-N fatigue data has been developed worldwide using conventional low-cycle fatigue tests. Such tests use smooth unnotched specimens subjected to controlled axial deflection or strain ranges. The tests must be run in the plastic regime in order to achieve the required cycles-to-failure. Recent developments have highlighted the need to understand and interpret the significance of the resulting strain range vs. cycles to failure data in terms of crack initiation and propagation. Since conventional fatigue tests are conducted in the plastic regime, linear elastic fracture mechanics cannot be used to accurately quantify crack growth in such tests. Elastic-plastic J-integral theory, however, has been shown to provide excellent correlations of crack growth in the elastic, elastic-plastic and grossly-plastic regimes for a wide range of geometric and loading conditions. The authors are applying this theory to the low-cycle fatigue specimen crack behavior. As cracks progress in conventional fatigue specimens, bending becomes significant. Since fatigue testing machines are quite stiff relative to the small fatigue specimens, the ends of the specimen are constrained to remain parallel, and this reduces bending in the cracked cross-section. Three-dimensional finite element elastic-plastic analyses are required to include these constraints in the J-integral solutions.

O`Donnell, T.P.; O`Donnell, W.J. [O`Donnell Consulting Engineers, Pittsburgh, PA (United States)

1996-12-01T23:59:59.000Z

127

Research on mechanisms of stress corrosion cracking in Zircaloy  

SciTech Connect

The results of internal gas pressurization tests, primarily at 320/sup 0/C, on cladding tubes from two suppliers, Supplier A and Supplier B, are presented. The two lots show a substantial difference in iodine SCC susceptibility so a test matrix is used to resolve the relative contributions of surface condition, residual stress, and texture. Additional tests with constant deflection split-ring specimens and with unstressed cladding segments are used to understand crack initiation and the early crack growth stages of SCC. The difference in SCC susceptibility is due to crystallographic texture. Other variables such as surface finish, stress relief temperature, and residual stress have little or no effect. Mechanical properties, crack initiation, and crack propagation all depend on texture. Both initiation and propagation features are analyzed by scanning electron microscopy. A mechanism for crack initiation consistent with most observations in this study and with the work of other investigators is proposed. At 320/sup 0/C, lifetime is crack initiation limited while several tests at 390/sup 0/C indicate that lifetime is less initiation limited at higher temperature. 31 figures, 9 tables.

Knorr, D.B.; Pelloux, R.M.

1981-06-01T23:59:59.000Z

128

ffe1098 FFE March 7, 2007 21:55 Crack tip displacements of microstructurally small cracks in 316L steel  

E-Print Network (OSTI)

steel and their dependence on crystallographic orientations of grains I. SIMONOVSKI1 , KARL orientations on a short Stage I surface crack in a 316L stainless steel. The analysis is based on a plane

Cizelj, Leon

129

North Carolina Nonprofit Helps Spread the Word About Weatherization |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

North Carolina Nonprofit Helps Spread the Word About Weatherization North Carolina Nonprofit Helps Spread the Word About Weatherization North Carolina Nonprofit Helps Spread the Word About Weatherization September 3, 2010 - 10:00am Addthis Stephen Graff Former Writer & editor for Energy Empowers, EERE On Tuesday night, about 15 people gathered at the Lewisville Library in Winston-Salem, N.C., to hear three energy experts talk about how to tighten homes to save money on utility bills. Weather stripping, insulation and even planting trees were among the tips discussed. For two hours, people asked questions and took notes, learning as much as they could about how to weatherize their own homes. "Afterwards, the reaction from everyone was, 'wow that is a really great amount of information,'" says Terri LeGrand, executive director of Piedmont

130

Golden Spread Electric Cooperative, Inc. Smart Grid Project | Open Energy  

Open Energy Info (EERE)

Golden Spread Electric Cooperative, Inc. Golden Spread Electric Cooperative, Inc. Country United States Headquarters Location Amarillo, Texas Recovery Act Funding $19,995,000.00 Total Project Value $49,987,500.00 Coverage Area Coverage Map: Golden Spread Electric Cooperative, Inc. Smart Grid Project Coordinates 35.2219971°, -101.8312969° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[]}

131

Georgia Nonprofit Spreads the Word About Energy Efficiency | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Georgia Nonprofit Spreads the Word About Energy Efficiency Georgia Nonprofit Spreads the Word About Energy Efficiency Georgia Nonprofit Spreads the Word About Energy Efficiency January 12, 2010 - 3:25pm Addthis Eric Barendsen Energy Technology Program Specialist, Office of Energy Efficiency and Renewable Energy At a time of strapped budgets, service organizations that find ways to save money through energy efficiency will more easily meet their fundraising goals. CHRIS Kids, an Atlanta-based nonprofit that provides housing to disadvantaged young people, is taking that idea to the next level. By upgrading its buildings with the latest in high-efficiency technologies, the group will reap the rewards of increased energy savings and, at the same time, teach the next generation about energy-efficiency technologies and behaviors.

132

EcoCar Students Spread the Word | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

EcoCar Students Spread the Word EcoCar Students Spread the Word EcoCar Students Spread the Word June 16, 2011 - 11:34am Addthis Shannon Brescher Shea Communications Manager, Clean Cities Program "If you build it, they will come" is a mantra that might be well suited for rural sporting venues, but the organizers behind the EcoCAR competition realize that in the commercial sector, merely producing a finely tuned product often isn't enough to make it successful. That's why along with challenging students to re-engineer a donated vehicle to minimize gas consumption and emissions while maintaining consumer acceptability, they've made outreach and education key components of the competition. Whether they're speaking to policy makers or elementary school students, each of the teams have worked to convey the benefits of advanced technology

133

North Carolina Nonprofit Helps Spread the Word About Weatherization |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Nonprofit Helps Spread the Word About Weatherization Nonprofit Helps Spread the Word About Weatherization North Carolina Nonprofit Helps Spread the Word About Weatherization September 3, 2010 - 10:00am Addthis Stephen Graff Former Writer & editor for Energy Empowers, EERE On Tuesday night, about 15 people gathered at the Lewisville Library in Winston-Salem, N.C., to hear three energy experts talk about how to tighten homes to save money on utility bills. Weather stripping, insulation and even planting trees were among the tips discussed. For two hours, people asked questions and took notes, learning as much as they could about how to weatherize their own homes. "Afterwards, the reaction from everyone was, 'wow that is a really great amount of information,'" says Terri LeGrand, executive director of Piedmont

134

Strengthening, Crack Arrest And Multiple Cracking In Brittle Materials Using Residual Stresses.  

DOE Patents (OSTI)

Embodiments include a method for forming a glass which displays visible cracking prior to failure when subjected to predetermined stress level that is greater than a predetermined minimum stress level and less than a failure stress level. The method includes determining a critical flaw size in the glass and introducing a residual stress profile to the glass so that a plurality of visible cracks are formed prior to failure when the glass is subjected to a stress that is greater than the minimum stress level and lower than the critical stress. One method for forming the residual stress profile includes performing a first ion exchange so that a first plurality of ions of a first element in the glass are exchanged with a second plurality of ions of a second element that have a larger volume than the first ions. A second ion exchange is also performed so that a plurality of the second ions in the glass are exchanged back to ions of the first element.

Green, David J. (State College, PA); Sglavo, Vincenzo M. (Roncegno, IT); Tandon, Rajan (Fremont, CA)

2003-02-11T23:59:59.000Z

135

Radio-frequency identification could help reduce the spread of plant pathogens  

E-Print Network (OSTI)

frequency identification could help reduce the spread ofeconomic losses. It also helps control the Plant Protection

Luvisi, Andrea; Panattoni, Alessandra; Triolo, Enrico

2012-01-01T23:59:59.000Z

136

The spread of awareness and its impact on epidemic outbreaks  

Science Journals Connector (OSTI)

...There is a fatal flu in Guangzhou...syndrome (SARS) outbreak (5), causing people...present a network model for the spread...constrain an epidemic outbreak. This effectiveness...when trying to predict disease progression...disease (32). Our model suggests how...distancing in disease outbreaks to come. 1 Ferguson...

Sebastian Funk; Erez Gilad; Chris Watkins; Vincent A. A. Jansen

2009-01-01T23:59:59.000Z

137

GLASSY STATES OF ADSORBED FLEXIBLE POLYMERS AND SPREAD POLYMER "MONOLAYERS"  

E-Print Network (OSTI)

1269 GLASSY STATES OF ADSORBED FLEXIBLE POLYMERS AND SPREAD POLYMER "MONOLAYERS" K. KREMER* Exxon mechanism for the dynamics of irreversibly adsorbed polymers. We argue that glass-like states can exist near of polymer adsorbed ' ' and the thickness of the adsorbed layer 2-7. While the results of the different

Paris-Sud XI, Université de

138

Short range spread-spectrum radiolocation system and method  

DOE Patents (OSTI)

A short range radiolocation system and associated methods that allow the location of an item, such as equipment, containers, pallets, vehicles, or personnel, within a defined area. A small, battery powered, self-contained tag is provided to an item to be located. The tag includes a spread-spectrum transmitter that transmits a spread-spectrum code and identification information. A plurality of receivers positioned about the area receive signals from a transmitting tag. The position of the tag, and hence the item, is located by triangulation. The system employs three different ranging techniques for providing coarse, intermediate, and fine spatial position resolution. Coarse positioning information is provided by use of direct-sequence code phase transmitted as a spread-spectrum signal. Intermediate positioning information is provided by the use of a difference signal transmitted with the direct-sequence spread-spectrum code. Fine positioning information is provided by use of carrier phase measurements. An algorithm is employed to combine the three data sets to provide accurate location measurements.

Smith, Stephen F. (Loudon, TN)

2003-04-29T23:59:59.000Z

139

Magma to Microbe: Modeling Hydrothermal Processes at Ocean Spreading Centers  

E-Print Network (OSTI)

215 Magma to Microbe: Modeling Hydrothermal Processes at Ocean Spreading Centers Geophysical is very limited. Low-temperature diffuse vent fluids, ubiquitous at hydrothermal systems, provide one microorganisms from diffuse hydrothermal vent fluids and the subseafloor at basalt-hosted mid-ocean ridges

Holden, James F.

140

Original article Impact of spreading olive mill wastewater on soil  

E-Print Network (OSTI)

Original article Impact of spreading olive mill wastewater on soil characteristics: laboratory 2001) Abstract ­ A dynamic of soil pollution with olive mill wastewater (OMW) was investigated process forms an olive mill wastewater (OMW). The amount of this waste depends on the process used for oil

Paris-Sud XI, Université de

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Statistical simulation of small fatigue crack nucleation and coalescence in a lamellar TiAl alloy  

SciTech Connect

This article examines the possibility of fatigue failure as the result of fatigue crack nucleation and coalescence at stress ranges below the fatigue limit and the large crack threshold where fatigue cracks are expected not to grow. By representing the material as a two-dimensional array of beam elements, the nucleation of nonpropagating small cracks at various material locations is modeled via a statistical approach that considers fatigue crack nucleation by accumulation of damage at randomly distributed weak regions. Once nucleated, the fatigue cracks do not propagate but extend only by linking with fatigue cracks subsequently formed in the contiguous elements. Result of the computer simulation suggests that fatigue failure by crack nucleation and coalescence is feasible, but the cycles-to-coalescence is much longer than the cycles-to-initiation for the first crack. Implications of the results in fatigue life assessment based on the Kitagawa diagram are discussed for TiAl alloys.

Chan, K.S. [Southwest Research Inst., San Antonio, TX (United States); Wittowsky, B. [Proctor and Gamble European Service GmbH, Euskirchen (Germany); Pfuff, M. [GKSS Research Center, Geesthacht (Germany)

1999-05-01T23:59:59.000Z

142

Measure the Crack Instead of Construction Vibrations by Charles H. Dowding, Ph.D., P.E.  

E-Print Network (OSTI)

Measure the Crack Instead of Construction Vibrations by Charles H. Dowding, Ph.D., P.E. Figure 1 to address fears of vibration-induced cracking by directly measuring crack response. Relatively inexpensive. HOUSE AND CRACK RESPONSE TO VIBRATIONS Crack measurement concepts are illustrated by the response

143

Hydrogen Crack Growth Resistance of Thermal Power Plant Material Collector  

Science Journals Connector (OSTI)

Abstract The influence of electrolytical hydrogenation on fracture toughness, corrosion crack-growth resistance and fracture micromechanisms of operated 12Cr1MoV steel of thermal power plant superheater collector has been studied. Compact tension specimens were cut from perforated surface of thermal power plant superheater collector dismounted after 178,500 hours of operation. Corrosion crack-growth resistance under tension of previously hydrogenated compact specimens with fatigue cracks was studied. Due to the increased concentration of hydrogen in solution an additional buffer was being created that prevents hydrogen leakage from the specimen through the fracture surface during the experiment. The hydrogenation causes the significant decrease of critical stress intensity factor Kc, during the experiment in 0.1 N NaOH solution as compared with critical stress intensity factor K of non-hydrogenation 12Cr1MoV steel obtained by the 5% secant line method and in comparison with critical stress intensity factor Kc, determined through the J-integral. The areas of ductile crack growth in hydrogenated and non-hydrogenated specimens were found to have similar material fracture micromechanisms with dimples creation of different shape and size. But on the ductile crack growth area in hydrogenated specimens material intergranular fracture mechanisms were found caused by the hydrogen embrittlement which are similar to areas without ridges with the products corrosion traces.

V. Iasnii; P. Maruschak; O. Yasniy; Y. Lapusta

2014-01-01T23:59:59.000Z

144

FITNESS-FOR-SERVICE ASSESSMENT FOR A RADIOACTIVE WASTE TANK THAT CONTAINS STRESS CORROSION CRACKS  

SciTech Connect

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The tanks are examined by ultrasonic (UT) methods for thinning, pitting, and stress corrosion cracking in order to assess fitness-for-service. During an inspection in 2002, ten cracks were identified on one of the tanks. Given the location of the cracks (i.e., adjacent to welds, weld attachments, and weld repairs), fabrication details (e.g., this tank was not stress-relieved), and the service history the degradation mechanism was stress corrosion cracking. Crack instability calculations utilizing API-579 guidance were performed to show that the combination of expected future service condition hydrostatic and weld residual stresses do not drive any of the identified cracks to instability. The cracks were re-inspected in 2007 to determine if crack growth had occurred. During this re-examination, one indication that was initially reported as a 'possible perpendicular crack <25% through wall' in 2002, was clearly shown not to be a crack. Additionally, examination of a new area immediately adjacent to other cracks along a vertical weld revealed three new cracks. It is not known when these new cracks formed as they could very well have been present in 2002 as well. Therefore, a total of twelve cracks were evaluated during the re-examination. Comparison of the crack lengths measured in 2002 and 2007 revealed that crack growth had occurred in four of the nine previously measured cracks. The crack length extension ranged from 0.25 to 1.8 inches. However, in all cases the cracks still remained within the residual stress zone (i.e., within two to three inches of the weld). The impact of the cracks that grew on the future service of Tank 15 was re-assessed. API-579 crack instability calculations were again performed, based on expected future service conditions and trended crack growth rates for the future tank service cycle. The analysis showed that the combined hydrostatic and weld residual stresses do not drive the identified cracks to instability. This tank expected to be decommissioned in the near future. However, if these plans are delayed, it was recommended that a third examination of selected cracks in the tank be performed in 2014.

Wiersma, B; James Elder, J; Rodney Vandekamp, R; Charles Mckeel, C

2009-04-23T23:59:59.000Z

145

Influence of cracking on the diffusion properties of cement-based materials. Part I: Influence of continuous cracks on the steady-state regime  

SciTech Connect

The influence of traversing cracks on the steady-state diffusion properties of concrete was studied. The effect of both anisotropic and isotropic crack networks was first theoretically assessed using an analytical approach. To simplify the transport equations, cracks were assumed to be of uniform size and evenly distributed on a one- or two-dimensional grid. Results of the theoretical analysis were then compared to experimental data. Both series of results indicate that cracking can markedly alter the diffusion properties of the material and favor the penetration (or the leaching) of drifting species. A simple method to predict the effect of cracking on the concrete diffusivity is proposed. Predictions are made on the basis of two parameters: the crack density and the mean crack aperture. This method can provide a first estimate of the diffusion properties of severely damaged concrete elements.

Gerard, B.; Marchand, J.

2000-01-01T23:59:59.000Z

146

Characterization of geothermal reservoir crack patterns using shear-wave  

Open Energy Info (EERE)

geothermal reservoir crack patterns using shear-wave geothermal reservoir crack patterns using shear-wave splitting Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Characterization of geothermal reservoir crack patterns using shear-wave splitting Details Activities (1) Areas (1) Regions (0) Abstract: Microearthquakes recorded by a downhole, three-component seismic network deployed around the Coso, California, geothermal reservoir since 1992 display distinctive shear-wave splitting and clear polarization directions. From the polarizations the authors estimated three predominant subsurface fracture directions, and from the time delays of the split waves they determined tomographically the 3-D fracture density distribution in the reservoir. Author(s): Lou, M.; Rial, J.A. Published: Geophysics, 3/1/1997

147

Shear-wave splitting and reservoir crack characterization: the Coso  

Open Energy Info (EERE)

Shear-wave splitting and reservoir crack characterization: the Coso Shear-wave splitting and reservoir crack characterization: the Coso geothermal field Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Shear-wave splitting and reservoir crack characterization: the Coso geothermal field Details Activities (1) Areas (1) Regions (0) Abstract: This paper aims to improve current understanding of the subsurface fracture system in the Coso geothermal field, located in east-central California. The Coso reservoir is in active economic development, so that knowledge of the subsurface fracture system is of vital importance for an accurate evaluation of its geothermal potential and day-to-day production. To detect the geometry and density of fracture systems we applied the shear-wave splitting technique to a large number of

148

Stress-corrosion cracking in BWR and PWR piping  

SciTech Connect

Intergranular stress-corrosion cracking of weld-sensitized wrought stainless steel piping has been an increasingly ubiquitous and expensive problem in boiling-water reactors over the last decade. In recent months, numerous cracks have been found, even in large-diameter lines. A number of potential remedies have been developed. These are directed at providing more resistant materials, reducing weld-induced stresses, or improving the water chemistry. The potential remedies are discussed, along with the capabilities of ultrasonic testing to find and size the cracks and related safety issues. The problem has been much less severe to date in pressurized-water reactors, reflecting the use of different materials and much lower coolant oxygen levels.

Weeks, R.W.

1983-07-01T23:59:59.000Z

149

Method for fabrication of crack-free ceramic dielectric films  

DOE Patents (OSTI)

The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

2014-02-11T23:59:59.000Z

150

Cracking a Cold Case and Enduring Mystery | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Cracking a Cold Case and Enduring Mystery Cracking a Cold Case and Enduring Mystery Cracking a Cold Case and Enduring Mystery July 1, 2013 - 3:04pm Addthis Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy. The breakwater dates back to roughly 37 B.C. | Photo courtesy of J.P. Oleson. Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy. The breakwater dates back to roughly 37 B.C. | Photo courtesy of J.P. Oleson. Charles Rousseaux Charles Rousseaux Senior Writer, Office of Science What are the key facts? Modern concrete buildings -- most made with Portland cement -- are built to last for a hundred or so years. But Roman concrete has withstood

151

Weld solidification cracking in 304 to 304L stainless steel  

SciTech Connect

A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

2010-01-01T23:59:59.000Z

152

Weld solidification cracking in 304 to 204L stainless steel  

SciTech Connect

A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

2010-09-15T23:59:59.000Z

153

Stress intensity factors for small fatigue cracks in tubular joints  

SciTech Connect

Some simple fracture mechanics models are presented for estimating stress intensity factors for small surface fatigue cracks in welded tubular joints. Model predictions are compared with large-scale experimental results for the cases of in-plane and out-of-plane bending in multi-brace tubular nodes. It is demonstrated that reasonably accurate predictions of the stress intensity factor are possible using a modified flat plate solution if the effects of weld geometry, load shedding and crack shape are adequately accounted for.

Monahan, C.C. [Memorial Univ. of Newfoundland, St. Johns, Newfoundland (Canada). Centre for Cold Ocean Resources Engineering; Dover, W.D. [University College, London (United Kingdom)

1995-12-31T23:59:59.000Z

154

Model of crack propagation in a clay soil  

E-Print Network (OSTI)

of independent variables for maximum R to determine A for crack de th, 2 Number of variables in model (p) R Variables in model 0. 703913 0. 916176 0. 988151 0. 997207 0. 999328 H*CLrH*M~CL H, H*M, H~M*CL H, CL, H*M, H*M*CL H, CL, H"M, H*CL, H...: Agricultural Engineering MODEL OF CRACK PROPAGATION IN A CLAY SOIL A Thesis by PATRICK EDWIDGE CARRIERE Approved as to style and content by: John L. Nieber (Chairman of Committee) Donald L. Reddell (Member) Kirk W, Brown (Member ) Wilbert H...

Carriere, Patrick Edwidge

2012-06-07T23:59:59.000Z

155

Transverse spreading of electrons in high-intensity laser fields  

E-Print Network (OSTI)

We show that for collisions of electrons with a high-intensity laser, discrete photon emissions introduce a transverse beam spread which is distinct from that due to classical (or beam shape) effects. Via numerical simulations, we show that this quantum induced transverse momentum gain of the electron is manifest in collisions with a realistic laser pulse of intensity within reach of current technology, and we propose it as a measurable signature of strong-field quantum electrodynamics.

D. G. Green; C. N. Harvey

2014-03-18T23:59:59.000Z

156

Modeling the spread of bird flu and predicting outbreak diversity  

Science Journals Connector (OSTI)

Avian influenza, commonly known as bird flu, is an epidemic caused by H5N1 virus that primarily affects birds like chickens, wild water birds, etc. On rare occasions, these can infect other species including pigs and humans. In the span of less than a year, the lethal strain of bird flu is spreading very fast across the globe mainly in South East Asia, parts of Central Asia, Africa and Europe. In order to study the patterns of spread of epidemic, we made an investigation of outbreaks of the epidemic in one week, that is from February 13–18, 2006, when the deadly virus surfaced in India. We have designed a statistical transmission model of bird flu taking into account the factors that affect the epidemic transmission such as source of infection, social and natural factors and various control measures are suggested. For modeling the general intensity coefficient f ( r ) , we have implemented the recent ideas given in the article Fitting the Bill, Nature [R. Howlett, Fitting the bill, Nature 439 (2006) 402], which describes the geographical spread of epidemics due to transportation of poultry products. Our aim is to study the spread of avian influenza, both in time and space, to gain a better understanding of transmission mechanism. Our model yields satisfactory results as evidenced by the simulations and may be used for the prediction of future situations of epidemic for longer periods. We utilize real data at these various scales and our model allows one to generalize our predictions and make better suggestions for the control of this epidemic.

Ranjit Kumar Upadhyay; Nitu Kumari; V. Sree Hari Rao

2008-01-01T23:59:59.000Z

157

E-Print Network 3.0 - assisted crack growth Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

cal crack growth by stress... for the first time in sapphire for both modes of subcritical cracking. It was found that growth rates were... growth rates could be closely...

158

Monitoring Cracking of a Smectitic Vertisol using Three-dimensional Electrical Resistivity Tomography  

E-Print Network (OSTI)

Upon desiccation, the matrix of Vertisols and other expansive soils shrinks. Matrix shrinkage results in the formation of cracks that can alter the hydrology of the soil. Despite the importance of cracks, many hydrologic models do not account...

Ackerson, Jason Paul

2013-11-20T23:59:59.000Z

159

Evaluation of cracking in steam generator feedwater piping in pressurized water reactor plants  

SciTech Connect

Cracking in feedwater piping was detected near the inlet to steam generators in 15 pressurized water reactor plants. Sections with cracks from nine plants are examined with the objective of identifying the cracking mechanism and assessing various factors that might contribute to this cracking. Using transmission electron microscopy, fatigue striations are observed on replicas of cleaned crack surfaces. Calculations based on the observed striation spacings gave a cyclic stress value of 150 MPa (22 ksi) for one of the major cracks. The direction of crack propagation was invariably related to the piping surface and not to the piping axis. These two factors are consistent with the proposed concept of thermally induced, cyclic, tensile surface stresses and it is concluded that the overriding factor in the cracking problem was the presence of such undocumented cyclic loads.

Goldberg, A.; Streit, R.D.

1981-05-01T23:59:59.000Z

160

Crack-resistant siloxane molding compounds. [Patent application  

DOE Patents (OSTI)

The crack resistance of phenyl silicone molding resins containing siliceous fillers is improved by incorporating therein about 0.5 to 5.5% by weight of ..beta..-eucryptite, a lithium aluminum silicate having a negative thermal expansion coefficient. These molding resins are particularly suitable for encapsulating electronic devices such as diodes, coils, resistors, and the like.

McFarland, J.W.; Swearngin, C.B.

1980-11-03T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

EARLY-AGE CRACKING REVIEW: MECHANISMS, MATERIAL PROPERTIES,  

E-Print Network (OSTI)

://cementbarriers.org/ and Savannah River National Laboratory website: http://srnl.doe.gov #12;Early-Age Cracking Review: Mechanisms Commission (NRC), the National Institute of Standards and Technology (NIST), the Savannah River National of work performed in part under that contract. This report was prepared in support of the Savannah River

Bentz, Dale P.

162

CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR  

E-Print Network (OSTI)

CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR James R. Rice* ABSTRACT An exact linear elastic-perfectly plastic solution is presented for the problem of a sharp notch coordinates corresponding to given stresses, position of the elastic-plastic boundary, and accompanying

163

Predicting overload-affected fatigue crack growth in steels  

SciTech Connect

The ability of semi-empirical crack closure models to predict the effect of overloads on fatigue crack growth in low-alloy steels has been investigated. With this purpose, the CORPUS model developed for aircraft metals and spectra has been checked first through comparisons between the simulated and observed results for a low-alloy steel. The CORPUS predictions of crack growth under several types of simple load histories containing overloads appeared generally unconservative which prompted the authors to formulate a new model, more suitable for steels. With the latter approach, the assumed evolution of the crack opening stress during the delayed retardation stage has been based on experimental results reported for various steels. For all the load sequences considered, the predictions from the proposed model appeared to be by far more accurate than those from CORPUS. Based on the analysis results, the capability of semi-empirical prediction concepts to cover experimentally observed trends that have been reported for sequences with overloads is discussed. Finally, possibilities of improving the model performance are considered.

Skorupa, M.; Skorupa, A.; Ladecki, B. [Univ. of Mining and Metallurgy, Krakow (Poland). Dept. of Mechanical Engineering and Robotics

1996-12-01T23:59:59.000Z

164

Cracks and Atoms** By Dominic Holland* and Michael Marder  

E-Print Network (OSTI)

Cracks and Atoms** By Dominic Holland* and Michael Marder 1. Introduction Many materials scientists the atomic scale on the mechanical response of materials. On the one hand, there is a reluctance to believe that the invisible atomic scale is important for macroscopic mechanical deformation. Out of sight, out of mind

Texas at Austin. University of

165

Corrosion pitting and environmentally assisted small crack growth  

Science Journals Connector (OSTI)

...of pit geometry and the local pit chemistry. In addition, the pit may have significant microtopographical...these can be found in the work of Burns et al. [29] in relation to...that cracks may initiate near the pit mouth, but the specific location...

2014-01-01T23:59:59.000Z

166

Fatigue crack growth testing of sub-clad defects  

SciTech Connect

Fatigue crack growth tests were performed on four-point bend specimens with cracklike defects intentionally placed in A302B low-alloy pressure vessel steel clad with 308/309L weld-deposited stainless steel. The defects were placed in the base metal under the cladding by machining a cavity from the side opposite the cladding, electric-discharge machining a very sharp flaw, fatigue precracking the flaw, and then filling up the cavity by a weld repair process. The specimens were stress relieved before fatigue testing. The specimens were fatigue cycled at positive load ratios until the defects broke through to the surface. The specimens were then fractured at liquid nitrogen temperatures to reveal the fracture surfaces. Seven different sub-clad flaw specimens were tested in room temperature air and each test provides a record of cycles to defect breakthrough. Changes in defect size and shape as a function of applied load cycles were obtained by beach-marking the crack at various stages of the load history. The results provide a set of embedded defect data which can be used for qualifying fatigue crack growth analysis procedures such as those in Section XI of the ASME boiler and Pressure Vessel Code. A comparison between calculated and measured values shows that the ASME B and PV Section XI fatigue crack growth procedures conservatively predict cycles to defect breakthrough for small sub-clad defects.

Jones, D.P.; Leax, T.R. [Bechtel Bettis, Inc., West Mifflin, PA (United States). Bettis Atomic Power Lab.

1999-08-01T23:59:59.000Z

167

Incipient Crack Detection in Composite Wind Turbine Blades  

SciTech Connect

This paper presents some analysis results for incipient crack detection in a 9-meter CX-100 wind turbine blade that underwent fatigue loading to failure. The blade was manufactured to standard specifications, and it underwent harmonic excitation at its first resonance using a hydraulically-actuated excitation system until reaching catastrophic failure. This work investigates the ability of an ultrasonic guided wave approach to detect incipient damage prior to the surfacing of a visible, catastrophic crack. The blade was instrumented with piezoelectric transducers, which were used in an active, pitchcatch mode with guided waves over a range of excitation frequencies. The performance results in detecting incipient crack formation in the fiberglass skin of the blade is assessed over the range of frequencies in order to determine the point at which the incipient crack became detectable. Higher excitation frequencies provide consistent results for paths along the rotor blade's carbon fiber spar cap, but performance falls off with increasing excitation frequencies for paths off of the spar cap. Lower excitation frequencies provide more consistent performance across all sensor paths.

Taylor, Stuart G. [Los Alamos National Laboratory; Choi, Mijin [Chonbuk National University, Korea; Jeong, Hyomi [Chonbuk National University, Korea; Jang, Jae Kyeong [Chonbuk National University, Korea; Park, Gyuhae [Chonnam National University, Korea; Farinholt, Kevin [Commonwealth Center for Advanced Manufacturing, VA; Farrar, Charles R. [Los Alamos National Laboratory; Ammerman, Curtt N. [Los Alamos National Laboratory; Todd, Michael D. [Los Alamos National Laboratory; Lee, Jung-Ryul [Chonbuk National University, Korea

2012-08-28T23:59:59.000Z

168

A new approach to the subcritical cracking of ceramic Pierre Ladev`eze,a,1  

E-Print Network (OSTI)

A new approach to the subcritical cracking of ceramic fibers Pierre Ladev`eze,a,1 , Martin Geneta a Cachan Cedex, France Abstract A new modeling approach to subcritical crack propagation (i.e. static fa, the result comes down to the widely-used Paris-like subcritical crack propagation law. For the general case

169

Average crack front velocity during subcritical fracture propagation in a heterogeneous medium  

E-Print Network (OSTI)

Average crack front velocity during subcritical fracture propagation in a heterogeneous medium relaxation tests, exploring subcritical to critical regimes. Transparency of the material (PMMA) allows kinetic crack propagation is usually referred to as sub-critical crack growth or sub- critical regime

Paris-Sud XI, Université de

170

On the physics of moisture-induced cracking in metal-glass ,,copper-silica... interfaces  

E-Print Network (OSTI)

September 2007 Environmentally dependent subcritical crack growth, or stress-corrosion cracking, along on the moisture content in gaseous environments. Water and several organic liquids, namely n-butanol, methanol, additionally, subcritical crack growth17 and cyclically induced fracture18 at or near these interfaces when

Ritchie, Robert

171

Stress corrosion cracking under low stress: Continuous or discontinuous Longkui K. Zhu a  

E-Print Network (OSTI)

Stress corrosion cracking under low stress: Continuous or discontinuous cracks? Longkui K. Zhu a , Yu Yan a , Jinxu X. Li a , Lijie J. Qiao a, , Alex A. Volinsky b,a a Corrosion and Protection Center. Stress corrosion C. Anodic dissolution a b s t r a c t Two-dimensional and three-dimensional crack

Volinsky, Alex A.

172

Influence of Impurity Segregation on Temper Embrittlement and on Slow Fatigue Crack  

E-Print Network (OSTI)

of segregated impurity atoms (temper embrittlement) and hydrogen atoms, evolved from crack tip surface reactions with water vapor in the moist air environment (hydrogen embrittlement). The signifi- cance of crack closureInfluence of Impurity Segregation on Temper Embrittlement and on Slow Fatigue Crack Growth

Ritchie, Robert

173

Brittle fracture in a periodic structure with internal potential energy. Spontaneous crack propagation  

Science Journals Connector (OSTI)

...with the crack speed-energy relation is presented...crack-related dynamic Green's function. For anisotropic...crack-related dynamic Green's function Note that...absence of the internal energy was considered in [14] without evaluation of the Green's function (also see...

2014-01-01T23:59:59.000Z

174

MICRO-METER MEASUREMENT OF CRACKS TO COMPARE BLAST AND ENVIRONMENTAL EFFECTS.  

E-Print Network (OSTI)

to development of a new approach to vibration monitoring called autonomous crack measurement (ACM vibration time histories. Measurements reported herein show that weather- induced response of cracksMICRO-METER MEASUREMENT OF CRACKS TO COMPARE BLAST AND ENVIRONMENTAL EFFECTS. Charles H Dowding

175

The Application of Reliability-Based Design Factors In Stress Corrosion Cracking Evaluations  

SciTech Connect

First-order reliability methodology (FORM) is used to develop reliability-based design factors for deterministic analyses of stress corrosion cracking. The basic elements of FORM as applied to structural reliability problems are reviewed and then employed specifically to stress corrosion cracking evaluations. Failure due to stress corrosion cracking is defined as crack initiation followed by crack growth to a critical depth. The stress corrosion cracking process is thus represented in terms of a crack initiation time model and a crack growth rate model, with the crack growth rate integrated from the initiation time to the time at which the crack grows to its critical depth. Both models are described by log-normal statistical distribution functions. A procedure is developed to evaluate design factors that are applied to the mean values of the crack initiation time and the crack growth rate for specified temperature and stress conditions. The design factors, which depend on the standard deviations of the statistical distributions, are related to a target reliability, which is inversely related to an acceptable probability of failure. The design factors are not fixed, but are evaluated on a case-to-case basis for each application. The use of these design factors in a deterministic analysis assures that the target reliability will be attained and the corresponding acceptable probability of failure will not be exceeded. An example problem illustrates use of this procedure.

E. Friedman

2001-12-20T23:59:59.000Z

176

White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel!  

E-Print Network (OSTI)

! 1! White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel! ! W!phenomena!such!as!the!appearance!of!"white(etching!areas"!or!"white(etching! cracks",!crack!particular!kind!of!microstructural!damage!in!the!form!of!regions!of!the! structure,! which! appear! white! in

Cambridge, University of

177

ensl-00138774,version1-27Mar2007 Slow crack growth: models and experiments  

E-Print Network (OSTI)

the subcritical growth of a single crack in thin sheets of paper. A good agreement between the theoreticalensl-00138774,version1-27Mar2007 Slow crack growth: models and experiments S. Santucci, L. Vanel, S'Italie, 69364 Lyon Cedex 07, France March 28, 2007 Abstract The properties of slow crack growth in brittle

Paris-Sud XI, Université de

178

J Am Cerom Soc 73 [4]893-903 (1990) Cyclic Fatigue-Crack Propagation in  

E-Print Network (OSTI)

InternationalScience Center, Thousand Oaks, California 91360 The subcritical growth of fatigue cracks under variable-amplitude cyclic loading, crack-growth rates show transient accelera- tions following low overloads, again analogous to behavior commonly observed in ductile metals. Cyclic crack-growth rates

Ritchie, Robert

179

Biomaterials 28 (2007) 49014911 Stresscorrosion crack growth of SiNaKMgCaPO bioactive  

E-Print Network (OSTI)

Elsevier Ltd. All rights reserved. Keywords: Stress corrosion; Bioactive glass; Subcritical crack growthBiomaterials 28 (2007) 4901­4911 Stress­corrosion crack growth of Si­Na­K­Mg­Ca­P­O bioactive Available online 21 August 2007 Abstract This paper describes research on the stress­corrosion crack growth

Ritchie, Robert

180

Ocean Floor Spreading: Olduvai and Gilsa Events in the Matuyama Epoch  

Science Journals Connector (OSTI)

...3910.1267 David A. Emilia Donald F. Heinrichs Marathon Oil Company, Denver Research Center, Littleton, Colorado...the basic spread-ing hypothesis. DAVID A. EMILIA Marathon Oil Company, Denver Research Center, Littleton, Colorado...

David A. Emilia; Donald F. Heinrichs

1969-12-05T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Fire spread probabilities for experimental beds composed of mixedwood boreal forest fuels  

E-Print Network (OSTI)

that fire spread was largely determined by the heat sink, heat of combustion, and fuel bed depth. We found

Johnson, Edward A.

182

Modeling the Spread of Epidemic Cholera: an Age-Structured Model  

E-Print Network (OSTI)

in crowded conditions and poor sanitation. A common type of model for the spread of an infectious disease

Gobbert, Matthias K.

183

Damage Spreading in the Ising Model Haye Hinrichsen and Eytan Domany  

E-Print Network (OSTI)

Damage Spreading in the Ising Model Haye Hinrichsen and Eytan Domany Department of Physics regarding damage spreading in ferromagnetic Ising models. First, we show that a damage spreading transition can occur in an Ising chain that evolves in contact with a thermal reservoir. Damage heals at low

Domany, Eytan

184

Anisotropic geometrical-spreading correction for wide-azimuth P-wave reflections  

E-Print Network (OSTI)

Anisotropic geometrical-spreading correction for wide-azimuth P-wave reflections Xiaoxia Xu1 spreading in stratified azi- muthally anisotropic media. The P-wave geometrical-spreading factor systems, nonhydrostatic stresses, or dipping trans- versely isotropic layers e.g., shales . The inversion

Tsvankin, Ilya

185

Comparing methods for measuring the rate of spread of invading populations  

E-Print Network (OSTI)

with known theoretical spread rates over a hypothetical region where a set of sampling points are distributed as well as the shape of the invaded area and then compare how different spread rate measurement methods biology, and in particular on the factors influencing spread into new environments (Sharov et al. 1999

Liebhold, Andrew

186

Mobile Conductance and Gossip-based Information Spreading in Mobile Networks  

E-Print Network (OSTI)

Mobile Conductance and Gossip-based Information Spreading in Mobile Networks Huazi Zhang, Zhaoyang framework for information spreading in mobile networks based on a new performance metric, mobile conductance, which allows us to separate the details of mobility models from the study of mobile spreading time. We

Dai, Huaiyu

187

Radiation-Driven Flame Spread Over Thermally-Thick Fuels in Quiescent Microgravity Environments  

E-Print Network (OSTI)

Radiation-Driven Flame Spread Over Thermally-Thick Fuels in Quiescent Microgravity Environments-non-premixed, flame-spread Submitted to Twenty-Ninth International Symposium on Combustion, Sapporo, Japan, July 21 ­ July 26, 2002. #12;Radiation-Driven Flame Spread Over Thermally-Thick Fuels in Quiescent Microgravity

188

Assessing nitrogen losses after sewage sludge spreading: A method based on simulation models and spreader  

E-Print Network (OSTI)

1 Assessing nitrogen losses after sewage sludge spreading: A method based on simulation models performances. We define 45 sewage sludge spreading scenarios covering a wide range of situations in France. Several models are used to (i) assess nitrogen losses due to sewage sludge spreading and (ii) calculate

Paris-Sud XI, Université de

189

Long-term survival of the axial valley morphology at abandoned slow-spreading centers  

E-Print Network (OSTI)

Long-term survival of the axial valley morphology at abandoned slow-spreading centers Andrew M the preservation of prominent axial valleys at extinct spreading centers, where extension has long ceased. In other of mid-ocean ridges suggest that the axial valley topography created at active slow- spreading centers

Freed, Andrew

190

EFFECT OF UNBROKEN LIGAMENTS ON STRESS CORROSION CRACKING BEHAVIOR OF ALLOY 82H WELDS  

SciTech Connect

Previously reported stress corrosion cracking (SCC) rates for Alloy 82H gas-tungsten-arc welds tested in 360 C water showed tremendous variability. The excessive data scatter was attributed to the variations in microstructure, mechanical properties and residual stresses that are common in welds. In the current study, however, re-evaluation of the SCC data revealed that the large data scatter was an anomaly due to erroneous crack growth rates inferred from crack mouth opening displacement (CMOD) measurements. Apparently, CMOD measurements provided reasonably accurate SCC rates for some specimens, but grossly overestimated rates in others. The overprediction was associated with large unbroken ligaments that often form in welds in the wake of advancing crack fronts. When ligaments were particularly large, they prevented crack mouth deflection, so apparent crack incubation times (i.e. period of time before crack advance commences) based on CMOD measurements were unrealistically long. During the final states of testing, ligaments began to separate allowing the crack mouth to open rather quickly. This behavior was interpreted as a rapid crack advance, but it actually reflects the ligament separation rate, not the SCC rate. Revised crack growth rates obtained in this study exhibit substantially less scatter than that previously reported. The effects of crack orientation and fatigue flutter loading on SCC rates in 82H welds are also discussed.

Mills, W.J. and Brown, C.M.

2003-02-20T23:59:59.000Z

191

Characteristics of lead induced stress corrosion cracking of alloy 690 in high temperature  

SciTech Connect

Slow strain rate tests (SSRT) were conducted on alloy 690 in various lead chloride solutions and metal lead added to 100 ppm chloride solution at 288 C. The corrosion potential (rest potential) for the alloy was measured with SSRT tests. The cracking was observed by metallographic examination and electron probe micro analyzer. Also, the corrosion behavior of the alloy was evaluated by anodic polarized measurement at 30 C. Resulting from the tests, cracking was characterized by cracking behavior, crack length and crack growth rate, and lead effects on cracking. The cracking was mainly intergranular in mode, approximately from 60 um to 450 um in crack length, and approximately 10{sup {minus}6} to 10{sup {minus}7} mmS-1 in crack velocity. The cracking was evaluated through the variation the corrosion potential in potential-time and lead behavior during SSRTs. The lead effect in corrosion was evaluated through active to passive transition behavior in anodic polarized curves. The corrosion reactions in the cracking region were confirmed by electron probe microanalysis. Alloy 690 is used for steam generation tubes in pressurized water reactors.

Chung, K.K. [Korea Inst. of Nuclear Safety, Taejon (Korea, Republic of); Lim, J.K. [Chonbuk National Univ., Chonju (Korea, Republic of); Watanabe, Yutaka; Shoji, Tetsuo [Tohoku Univ., Sendai (Japan). Research Inst. for Fracture Technology

1996-10-01T23:59:59.000Z

192

Fatigue and Creep Crack Propagation behaviour of Alloy 617 in the Annealed and Aged Conditions  

SciTech Connect

The crack propagation behaviour of Alloy 617 was studied under various conditions. Elevated temperature fatigue and creep-fatigue crack growth experiments were conducted at 650 and 800 degrees C under constant stress intensity (triangle K) conditions and triangular or trapezoidal waveforms at various frequencies on as-received, aged, and carburized material. Environmental conditions included both laboratory air and characteristic VHTR impure helium. As-received Alloy 617 displayed an increase in the crack growth rate (da/dN) as the frequency was decreased in air which indicated a time-dependent contribution component in fatigue crack propagation. Material aged at 650°C did not display any influence on the fatigue crack growth rates nor the increasing trend of crack growth rate with decreasing frequency even though significant microstructural evolution, including y’ (Ni3Al) after short times, occurred during aging. In contrast, carburized Alloy 617 showed an increase in crack growth rates at all frequencies tested compared to the material in the standard annealed condition. Crack growth studies under quasi-constant K (i.e. creep) conditions were also completed at 650 degrees C and a stress intensity of K = 40 MPa9 (square root)m. The results indicate that crack growth is primarily intergranular and increased creep crack growth rates exist in the impure helium environment when compared to the results in laboratory air. Furthermore, the propagation rates (da/dt) continually increased for the duration of the creep crack growth either due to material aging or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 degrees C on annealed Alloy 617 indicated that crack propagation rates were higher in air than impure helium at the largest frequencies and lowest stress intensities. The rates in helium, however, eventually surpass the rates in air as the frequency is reduced and the stress intensity is decreased which was not observed at 650 degrees C.

Julian K. Benz; Richard N. Wright

2013-10-01T23:59:59.000Z

193

On the application of bees algorithm to the problem of crack detection of beam-type structures  

Science Journals Connector (OSTI)

In this paper, the application of the bees algorithm (BA) to the problem of crack detection in beams is introduced. A numerical as well as an experimental study is designed to predict a single open edge-crack in cantilever beams. The crack is modeled ... Keywords: Bees algorithm, Cantilever beam, Crack detection, Modal testing, Particle swarm optimization

S. Moradi; P. Razi; L. Fatahi

2011-12-01T23:59:59.000Z

194

Method for making dense crack free thin films  

DOE Patents (OSTI)

The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

2007-01-16T23:59:59.000Z

195

Environmentally assisted cracking of light-water reactor materials  

SciTech Connect

Environmentally assisted cracking (EAC) of lightwater reactor (LWR) materials has affected nuclear reactors from the very introduction of the technology. Corrosion problems have afflicted steam generators from the very introduction of pressurized water reactor (PWR) technology. Shippingport, the first commercial PWR operated in the United States, developed leaking cracks in two Type 304 stainless steel (SS) steam generator tubes as early as 1957, after only 150 h of operation. Stress corrosion cracks were observed in the heat-affected zones of welds in austenitic SS piping and associated components in boiling-water reactors (BRWs) as early as 1965. The degradation of steam generator tubing in PWRs and the stress corrosion cracking (SCC) of austenitic SS piping in BWRs have been the most visible and most expensive examples of EAC in LWRs, and the repair and replacement of steam generators and recirculation piping has cost hundreds of millions of dollars. However, other problems associated with the effects of the environment on reactor structures and components am important concerns in operating plants and for extended reactor lifetimes. Cast duplex austenitic-ferritic SSs are used extensively in the nuclear industry to fabricate pump casings and valve bodies for LWRs and primary coolant piping in many PWRs. Embrittlement of the ferrite phase in cast duplex SS may occur after 10 to 20 years at reactor operating temperatures, which could influence the mechanical response and integrity of pressure boundary components during high strain-rate loading (e.g., seismic events). The problem is of most concern in PWRs where slightly higher temperatures are typical and cast SS piping is widely used.

Chopra, O.K.; Chung, H.M.; Kassner, T.F.; Shack, W.J.

1996-02-01T23:59:59.000Z

196

Environmental stress cracking of plastics under dynamic conditions  

E-Print Network (OSTI)

The objective of this study was to find out if dynamic conditions have any effect on the phenomenon of environmental stress cracking (ESC). Dynamic conditions in this study include thermal shock, mechanical shock, and vibrations. Injection blow molded... resistance of blow molded polyethylene containers. The experimental data indicated that each of the dynamic conditions accelerated the ESC. Therefore, the results obtained from the static tests cannot be used to predict the service life of the containers...

Suresh, Mitta

1992-01-01T23:59:59.000Z

197

Direct Observation and Image-Based Simulation of Three-Dimensional Tortuous Crack Evolution inside Opaque Materials  

Science Journals Connector (OSTI)

We present a combined novel methodology to study the three-dimensional complex geometry of a tortuous crack and identify the essential features of the crack and its propagation inside a heterogeneous material. We find that some severe damage events occur unexpectedly below a local mode-I crack within the sample; we realize that the severe plastic zone of the local mode-I crack is shifted down by another unseen crack segment hidden behind, which is responsible for the unusual damage phenomenon observed. We also find that the crack grows fast at some locations but slowly at some other locations along the crack front; we recognize that the crack-tip fields are reduced by neighboring hidden crack segments, which accounts for the retarded propagation of some part of the crack front. The feasibility and power of the proposed methodology highlights the potential of a new way to study fracture mechanisms in real materials.

Lihe Qian; Hiroyuki Toda; Kentaro Uesugi; Masakazu Kobayashi; Toshiro Kobayashi

2008-03-21T23:59:59.000Z

198

Mixed-mode, high-cycle fatigue-crack growth thresholds in I. A comparison of large-and short-crack behavior  

E-Print Network (OSTI)

) in a Ti±6Al±4V turbine blade alloy with a bimodal microstructure. Speci®cally, the eect of combined mode I machined to within $200 lm of the precrack tip. For such short cracks, wherein the magnitude of crack, particularly in association with fretting fatigue in the blade dovetail/disk contact section [3]. For fatigue

Ritchie, Robert

199

To Crack or Not to Crack: Strain in High TemperatureSuperconductors  

SciTech Connect

Round wire Bi 2212 is emerging as a viable successor ofNb3Sn in High Energy Physics and Nuclear Magnetic Resonance, to generatemagnetic fields that surpass the intrinsic limitations of Nb3Sn. Ratherbold claims are made on achievable magnetic fields in applications usingBi 2212, due to the materials' estimated critical magnetic field of 100 Tor higher. High transport currents in high magnetic fields, however, leadto large stress on, and resulting large strain in the superconductor. Theeffect of strain on the critical properties of Bi-2212 is far fromunderstood, and strain is, as with Nb3Sn, often treated as a secondaryparameter in the design of superconducting magnets. Reversibility of thestrain induced change of the critical surface of Nb3Sn, points to anelectronic origin of the observed strain dependence. Record breaking highfield magnets are enabled by virtue of such reversible behavior. Straineffects on the critical surface of Bi-2212, in contrast, are mainlyirreversible and suggest a non-electronic origin of the observed straindependence, which appears to be dominated by the formation of cracks inthe superconductor volumes. A review is presented of available results onthe effects of strain on the critical surface of Bi-2212, Bi-2223 andYBCO. It is shown how a generic behavior emerges for the (axial) straindependence of the critical current density, and how the irreversiblereduction of the critical current density is dominated by strain inducedcrack formation in the superconductor. From this generic model it becomesclear that magnets using high temperature superconductors will be strainlimited far before the intrinsic magnetic field limitations will beapproached, or possibly even before the magnetic field limitation ofNb3Sn can be surpassed. On a positive note, in a very promising recentresult from NIST on the axial strain dependence of the critical currentdensity in extremely well aligned YBCO, reversible behavior was observed.This result emphasizes the need for further conductor development,specifically for round wire Bi-2212, to generate a wire with a similarreversible dependence on strain. Availability of such a wire will enablethe construction of magnets that can indeed generate fields that farsurpass the limitations of Nb3Sn superconductors.

Godeke, Arno

2007-08-22T23:59:59.000Z

200

Effects of stress ratio and fiber orientation on fatigue crack growth behavior in APAL  

SciTech Connect

A new hybrid composite (APAL; Aramid Patched Aluminum Alloy), consisting of 2024-T3 aluminum alloy plate sandwiched between aramid/epoxy prepregs (HK 285/RS 1222), was developed. Fatigue crack growth behavior was examined at stress ratios of R = 0.2, 0.5 using two kinds of APAL with different fiber orientation (0{degree}/90{degree} and {+-} 45{degree} for crack direction). The APAL showed superior fatigue crack growth resistance, which may be attributed to the crack bridging effect imposed by the intact fibers in the crack wave. The magnitude of crack bridging was estimated quantitatively and determined by a new technique on the basis of the compliances of 2024-T3 aluminum alloy and APAL specimens. The crack growth rate of the APAL specimens was reduced significantly as comparison to the monolithic aluminum alloy and was not adequately correlated with the conventional stress intensity factor range ({Delta}K). It was found that the crack growth rate was successfully correlated with the effective stress intensity factor range ( {Delta}K{sub eff} = K{sub br} {minus} K{sub cl}) allowing for the crack closure and the crack bridging. The relation between da/dN and {Delta}K{sub eff} was plotted within a narrow scatter band regardless at loading line of 2024-T3 aluminum alloy, two kinds of the APAL (APAL 0{degree}/90{degree}, APAL {+-} 45{degree}) and two kinds of stress ratios (R = 0.2, 0.5).

Oh, S.W.; Park, W.J. [Dong-A Univ., Pusan (Korea, Republic of). Dept. of Mechanical Engineering; Yoon, H.K.; Lee, K.G. [Dong-Eui Univ., Pusan (Korea, Republic of). Dept. of Mechanical Engineering; Cho, J.M.; Lee, K.B. [Han Kuk Fiber Glass Co. Ltd., Kyungnam (Korea, Republic of)

1993-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Finite element analysis of a crack tip in silicate glass: No evidence for a plastic zone  

Science Journals Connector (OSTI)

Recently, the claim was made that cracks in silicate glasses propagate by the nucleation, growth, and coalescence of cavities at crack tips, which is the same way as in metals but at a much smaller scale. This hypothesis for crack growth is based in part on the measurement of surface displacements near the tip of an emerging crack, which is the point at which a crack front intersects the side surface of the specimen. Surface displacements measured by atomic force microscopy were less than theoretically predicted. The difference between the theoretical and experimental displacements was attributed to a plastic zone surrounding the tip of the moving crack. In this paper, we show that the theoretical analysis used earlier was based on an incorrect assumption about the functional dependence of the displacement with distance from the crack tip. We use a full three-dimensional finite element analysis combined with an asymptotic solution of the crack geometry to obtain a solution to the surface displacement problem. We show that the calculated displacements are fully consistent with those experimentally measured by using an atomic force microscope. No divergence from elastic behavior is observed. Our results support the view that crack propagation in glass is entirely brittle. No evidence for plasticity at the crack tips is obtained.

T. Fett, G. Rizzi, D. Creek, S. Wagner, J. P. Guin, J. M. López-Cepero, and S. M. Wiederhorn

2008-05-15T23:59:59.000Z

202

Acoustic Emission Detection and Prediction of Fatigue Crack Propagation in Composite Patch Repairs Using Neural Networks  

SciTech Connect

An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor features were used to train neural networks for predicting crack length. The results show that AE events are correlated with crack propagation. AE system was able to detect crack propagation even at high noise condition of 10 Hz loading; that crack propagation signals can be differentiated from matrix cracking signals that take place due to fiber breakage in the composite patch. Three back-propagation cascade feed forward networks were trained to predict crack length based on the number of fatigue cycles, AE event number, and both the Fatigue Cycles and AE events, as inputs respectively. Network using both fatigue cycles and AE event number as inputs to predict crack length gave the best results, followed by Network with fatigue cycles as input, while network with just AE events as input had a greater error.

Okafor, A. Chukwujekwu; Singh, Navdeep; Singh, Navrag [Structural Health Monitoring and NDE Laboratory, Department of Mechanical and Aerospace Engineering, University of Missouri-Rolla, 1870 Miner Circle Rolla MO 65409-0050 (United States)

2007-03-21T23:59:59.000Z

203

Stress Corrosion Cracking and Non-Destructive Examination of Dissimilar Metal Welds and Alloy 600  

SciTech Connect

The United States Nuclear Regulatory Commission (USNRC) has conducted research since 1977 in the areas of environmentally assisted cracking and assessment and reliability of non-destructive examination (NDE). Recent occurrences of cracking in Alloy 82/182 welds and Alloy 600 base metal at several domestic and overseas plants have raised several issues relating to both of these areas of NRC research. The occurrences of cracking were identified by the discovery of boric acid deposits resulting from through-wall cracking in the primary system pressure boundary. Analyses indicate that the cracking has occurred due to primary water stress corrosion cracking (PWSCC) in Alloy 82/182 welds. This cracking has occurred in two different locations: in hot leg nozzle-to-safe end welds and in control rod drive mechanism (CRDM) nozzle welds. The cracking associated with safe-end welds is important due to the potential for a large loss of reactor coolant inventory, and the cracking of CRDM nozzle base metal and welds, particularly circumferential cracking of CRDM nozzle base metal, is important due to the potential for a control rod to eject resulting in a loss of coolant accident. The industry response in the U.S. to this cracking is being coordinated through the Electric Power Research Institute's Materials Reliability Project (EPRI-MRP) in a comprehensive, multifaceted effort. Although the industry program is addressing many of the issues raised by these cracking occurrences, confirmatory research is necessary for the staff to evaluate the work conducted by industry groups. Several issues requiring additional consideration regarding the generic implications of these isolated events have been identified. This paper will discuss the recent events of significant cracking in domestic and foreign plants, discuss the limitations of NDE in detecting SCC, identify deficiencies in information available in this area, discuss the USNRC approach to address these issues, and discuss the development of an international cooperative effort. (authors)

Jackson, Deborah A. [U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001 (United States)

2002-07-01T23:59:59.000Z

204

Longitudinal bunch profile and electron beam energy spread  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnets and Power Supplies Up: APS Storage Ring Parameters Previous: Magnets and Power Supplies Up: APS Storage Ring Parameters Previous: Storage Ring Operation Modes Longitudinal bunch profile and electron beam energy spread Longitudinal bunch profile depends mainly on the single bunch charge (or single bunch current). Every APS operating mode has different single bunch current and therefore has different bunch length. The plot below shows measured bunch length dependence on the single bunch current between 1 mA and 18 mA and the fit that uses the formula shown below the plot. The bunch length in this plot is shorter than it was quoted before. Earlier numbers were obtained using a Gaussian fit, present numbers are calculated as true standard deviation. \includegraphics[width=0.8\textwidth]{otherFiles/bunchLength.eps} The following formula obtained by fitting the log of the data above can be

205

Reactive Spreading of a Lead-Free Solder on Alumina  

SciTech Connect

The wetting of Sn3Ag-based alloys on Al{sub 2}O{sub 3} has been studied using the sessile-drop configuration. Small additions of Ti decrease the contact angle of Sn3Ag alloys on alumina from 115 to 23 degrees. Adsorption of Ti-species at the solid-liquid interface prior to reaction is the driving force for the observed decrease in contact angle, and the spreading kinetics is controlled by the kinetics of Ti dissolution into the molten alloy. The addition of Ti increases the transport rates at the solid-liquid interface, resulting in the formation of triple-line ridges that pin the liquid front and promote a wide variability in the final contact angles.

Gremillard, L.; Saiz, E.; Radmilovic, V.R.; Tomsia, A.P.

2005-12-01T23:59:59.000Z

206

Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617  

SciTech Connect

The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or SAGBOE damage process under hold-time fatigue and sustained loading conditions

Longzhou Ma

2012-11-30T23:59:59.000Z

207

Significance of crack opening monitoring for determining the growth behavior of hydrofractures  

SciTech Connect

A method for determining the size of a crack induced by hydraulic fracturing is presented. The procedure is based on the measurement of the crack opening displacement and the fracture mechanics approach. The proposed method has been tested by conducting laboratory small-scale hydraulic fracturing tests on a granite. It is shown from the preliminary tests that the method provides a reasonable prediction of experimentally observed crack sizes.

Hashida, Toshiyuki; Sato, Kazushi; Takahashi, Hideaki

1993-01-28T23:59:59.000Z

208

Evaluation of low-cycle fatigue crack growth and subsequent ductile fracture for cracked pipe experiments using cyclic J-integral  

SciTech Connect

Piping for LWR power plants is required to satisfy the Leak-Before-Break concept for postulated (not actual) defects. With this in mind, numerous research has so far been conducted on the fatigue crack growth under cyclic loading, and on the ductile crack growth under excessive loading. Study on cracked pipe fracture under cyclic loading gains much attention from the viewpoint of the Leak-Before-Break concept for seismic loading that accompanies large-scale yielding. An evaluation method based on cyclic J-integral was newly developed to predict the low-cycle fatigue crack growth and the subsequent ductile fracture for cyclic loading that accompanies large-scale yielding. Cyclic J-integral was introduced to describe the crack growth up to failure. The method was applied to 4-inch diameter circumferentially through-wall-cracked carbon steel base metal pipes and welded pipe joints subjected to cyclic 4-point bending at room temperature and high temperature of approximately 300 C. Fatigue crack growth behavior and failure life were successfully predicted by the proposed approach.

Miura, Naoki; Fujioka, Terutaka; Kashima, Koichi [CRIEPI, Tokyo (Japan); Miyazaki, Katsumasa; Kanno, Satoshi; Hayashi, Makoto; Ishiwata, Masayuki; Gotoh, Nobuho [Hitachi, Ltd., Ibaraki (Japan)

1996-12-01T23:59:59.000Z

209

E-Print Network 3.0 - assisted fatigue crack Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

and Grain-Boundary Adhesion Summary: unless they experience environmentally assisted subcritical growth during cyclic loading.7 Fatigue-crack... (moist air and dry N2). The...

210

Modeling of interaction between corrosion-induced concrete cover crack and steel corrosion rate.  

E-Print Network (OSTI)

??Chloride-induced corrosion of steel reinforcement in concrete may cause severe damage to RC structures. Longitudinal cover cracks may form during the rust expansion process. Currently,… (more)

Cao, Chong

2012-01-01T23:59:59.000Z

211

Low Alloy Steel Susceptibility to Stress Corrosion Cracking in Hydraulic Fracturing Environment.  

E-Print Network (OSTI)

??The pipelines used for hydraulic fracturing (aka. "fracking") are often operating at a pressure above 10000psi and thus are highly susceptible to Stress Corrosion Cracking… (more)

Anyanwu, Ezechukwu John

2014-01-01T23:59:59.000Z

212

Simulation of the ultrasonic array response from real branched cracks using an efficient finite element method  

SciTech Connect

A hybrid model to simulate the ultrasonic array response from stress corrosion cracks is presented. These cracks are branched and difficult to detect so the model is required to enable optimization of an array design. An efficient frequency-domain finite element method is described and selected to simulate the ultrasonic scattering. Experimental validation results are presented, followed by an example of the simulated ultrasonic array response from a real stress corrosion crack whose geometry is obtained from an X-ray Computed Tomography image. A simulation-assisted array design methodology, which includes the model and use of real crack geometries, is proposed.

Felice, Maria V. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom and Rolls-Royce plc., Bristol BS34 7QE (United Kingdom); Velichko, Alexander; Wilcox, Paul D. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Barden, Tim J.; Dunhill, Tony K. [Rolls-Royce plc., Bristol BS34 7QE (United Kingdom)

2014-02-18T23:59:59.000Z

213

Subcritical crack growth, initiation, and arrest in columnar freshwater and sea ice.  

E-Print Network (OSTI)

??A study was conducted to determine if slow stable sub-critical crack growth may occur in ice. The Double Torsion fracture toughness geometry was used to… (more)

Parsons, Bruce L.

1989-01-01T23:59:59.000Z

214

Welding Hot Cracking of Side Shell of Drilling-Well Oil Storage Ship  

Science Journals Connector (OSTI)

...Cracks were found in the weld metal (WM) of weld-section of side shell of drilling-well oil storage ship when performing post weld radiographic...

Zhi-wei Yu; Xiao-lei Xu

2014-11-01T23:59:59.000Z

215

Fracture of Hydrided Zircaloy-4 Sheet under Through-Thickness Crack Growth Conditions  

SciTech Connect

The failure of thin-wall components such as fuel cladding may be caused by crack initiation on the component surface and subsequent crack growth through its thickness. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at 25 deg. C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined pre-crack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (K{sub Q}) is sensitive to the orientation of the hydride platelets, and K{sub Q} {approx_equal} 25 MPavm for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, K{sub Q} is much higher ({approx_equal} 75 MPavm) when the hydride platelets are oriented predominantly in the plane of the sheet (and therefore normal to both the crack plane and the crack growth direction). The implication of these fracture toughness values to the fracture strain behavior of hydrided Zircaloy-4 under through-thickness crack growth conditions is illustrated. (authors)

Raynaud, P.A.; Koss, D.A. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Motta, A.T. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Chan, K.S. [Southwest Research Institute, San Antonio, TX 78238 (United States)

2007-07-01T23:59:59.000Z

216

Status Report on Studies of Recovery Boiler Composite Floor Tube Cracking  

SciTech Connect

Cracking of the stainless steel layer of co-extruded 304L stainless steel/SA210 Gd A 1 carbon steel black liquor recovery boiler floor tubes has been identified as one of the most serious material problems in the pulp and paper industry. A DOE-funded study was initiated in 1995 with the goal of determining the cause of and possible solutions to this cracking problem. These studies have characterized tube cracking as well as the chemical and thermal environment and stress state of floor tubes. Investigations of possible cracking mechanisms indicate that stress corrosion cracking rather than thermal fatigue is a more likely cause of crack initiation. The cracking mechanism appears to require the presence of hydrated sodium sulfide and is most likely active during shut-downs and/or start-ups. Based on these results and operating experience, certain alloys appear to be more resistant than others to cracking in the floor environment, and certain operating practices appear to significantly lessen the likelihood of cracking. This report is the latest in a series of progress reports presented on this project.

Eng, P.; Frederick, L.A.; Hoffmann, C.M.; Keiser, J.R.; Mahmood, J.; Maziasz, P.J.; Prescott, R.; Sarma, G.B.; Singbeil, D.L.; Singh, P.M.; Swindeman, R.W.; Wang, X.-L.

1999-09-12T23:59:59.000Z

217

Innovative Approach to Establish Root Causes for Cracking in Aggressive Reactor Environments  

SciTech Connect

The research focuses on the high-resolution characterization of degradation microstructures and microchemistries in specimens tested under controlled conditions for the environment and for the material where in-service complexities can be minimized. Thermodynamic and kinetic modeling of crack-tip processes is employed to analyze corrosion-induced structures and gain insights into degradation mechanisms. Novel mechanistic ''fingerprinting'' of crack-tip structures is used to isolate causes of environmental cracking in tandem with quantitative measurements of crack growth. Sample preparation methods and advanced analytical techniques are used to characterize corrosion/oxidation reactions and crack-tip structures at near atomic dimensions in order to gain insight into fundamental environmental cracking mechanisms. Reactions at buried interfaces, not accessible by conventional approaches, are being systematically interrogated. Crack-growth experiments in high-temperature water environments are evaluating and isolating the effects of material condition (matrix strength, grain boundary composition and precipitation) on stress corrosion cracking (SCC). The fundamental understanding of crack advance mechanisms will establish the basis to design new corrosion-resistant alloys for current light-water reactors and advanced reactor systems.

Bruemmer, Stephen M.; Thomas, Larry E.; Vetrano, John S.; Simonen, Edward P.

2003-10-31T23:59:59.000Z

218

IGNITION PROCESSES AND FLAME SPREADING IN A GRANULAR SOLID PROPELLANT BED.  

E-Print Network (OSTI)

??Understanding the detailed ignition, flame spreading, and combustion processes inside of a granular solid propellant bed is vital for accurate internal ballistic modeling and development… (more)

Colletti, Alexander

2010-01-01T23:59:59.000Z

219

Dynamic Modeling of Cell Migration and Spreading Behaviors on Fibronectin Coated Planar Substrates and Micropatterned Geometries  

E-Print Network (OSTI)

An integrative cell migration model incorporating focal adhesion (FA) dynamics, cytoskeleton and nucleus remodeling, actin motor activity, and lamellipodia protrusion is developed for predicting cell spreading and migration ...

Kim, Min-Cheol

220

Temperature and environmentally assisted cracking in low alloy steel  

SciTech Connect

Environmental assisted cracking (EAC) can be defined as the propagation of fatigue cracks in water at rates from 3 to over 40 times the growth rates in air. For low alloy steels with sulfur contents > 0.0125% by weight, EAC is normal behavior in the 240 to 290C range. However, literature yields mixed results for low alloy steels with compositions just below this sulfur level; some reports indicate EAC while others do not. Also, several authors have reported an increased tendency toward EAC when the water temperatures were lowered. In the present work, five ASTM A 508 Class 2 forgings with ladle and check analyses that ranged from 0.010 to 0.019 wt% S were tested in high purity deaerated water in the temperature range of 93 to 260C. At 260C these forgings did not exhibit EAC, reinforcing earlier results for two similar forgings. This broad sampling indicates strong resistance to EAC for this class of forging at 260C. On the other hand, EAC occurred consistently in the three of these forgings that were tested below 204C, provided the test conditions (loading frequency, {Delta}K, and R) were high enough to produce a high baseline fatigue crack growth rate (FCGR), where the baseline FCGR is that expected in air. At 149C, EAC occurred at test conditions that combined to yield a baseline FCGR greater than {approx}2E-6 mm/s. At 204, 121, and 93C, this critical crack growth rate appeared to shift to lower baseline values. The EAC that occurred at lower temperatures was a factor of 3 to 12 times higher than baseline air rates, which was not as strong as the effect for higher sulfur steels at 240 to 290C. Also, no plateau in the growth rates occurred as it does with the higher sulfur steels. In another approach, EAC was induced at 93 and at 260C by raising the dissolved oxygen content of the water from <10 to >15 ppb.

Auten, T.A.; Monter, J.V.

1995-04-01T23:59:59.000Z

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221

Physics-Based Stress Corrosion Cracking Component Reliability  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Physics-Based Stress Corrosion Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework Draft Report Supporting Technology Inputs to the Risk- Informed Safety Margin Characterization Pathway of the DOE Light Water Reactor Sustainability Program Stephen D. Unwin Kenneth I. Johnson Robert F. Layton Peter P. Lowry Scott E. Sanborn Mychailo B. Toloczko PNNL-20596 July 2011 Physics-Based SCC Reliability Model in a Cumulative Damage Framework 2 Physics-Based SCC Reliability Model in a Cumulative Damage Framework 3 Table of Contents Executive Summary............................................................................... 4 1. Introduction .......................................................................... 5

222

Fundamentals of wetting and spreading with emphasis on soldering  

SciTech Connect

Soldering is often referred to as a mature technology whose fundamentals were established long ago. Yet a multitude of soldering problems persist, not the least of which are related to the wetting and spreading of solder. The Buff-Goodrich approach to thermodynamics of capillarity is utilized in a review of basic wetting principles. These thermodynamics allow a very compact formulation of capillary phenomena which is used to calculate various meniscus shapes and wetting forces. These shapes and forces lend themselves to experimental techniques, such as the sessile drop and the Wilhelmy plate, for measuring useful surface and interfacial energies. The familiar equations of Young, Wilhelmy, and Neumann are all derived with this approach. The force-energy duality of surface energy is discussed and the force method is developed and used to derive the Herring relations for anisotropic surfaces. The importance of contact angle hysteresis which results from surface roughness and chemical inhomogeneity is presented and Young's equation is modified to reflect these ever present effects. Finally, an analysis of wetting with simultaneous metallurigical reaction is given and used to discuss solder wetting phenomena. 60 refs., 13 figs.

Yost, F.G.

1991-01-01T23:59:59.000Z

223

Prediction of PWSCC in nickel base alloys using crack growth rate models  

SciTech Connect

The Ford/Andresen slip-dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material conditions. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip-dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip-dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L. [Knolls Atomic Power Lab., Schenectady, NY (United States)

1995-12-31T23:59:59.000Z

224

Catalytic cracking of a Gippsland reduced crude on zeolite catalysts  

SciTech Connect

Cracking reactions of a Gippsland reduced crude have been investigated at 520[degrees]C over HY and HZSM-5. Gasolines with similar characteristics can be obtained on both zeolites, although the mechanistic routes to these products are quite distinct. Changes in aromatic product selectivities are consistent with the zeolite pore geometries. Minor quantities of aromatics are formed via hydrogen transfer processes involving product olefins and naphthenes over the faujasite and the cyclization (and to a lesser extent oligomerization) of olefinic species on the pentasil. Dehydrogenation of naphthenic species in the feedstock is also important for aromatic formation. While paraffins are formed via hydrogen transfer processes together with cracking and isomerization of feed paraffins on HY, only the latter route can explain formation of saturated species on HZSM-5. The removal of linear paraffins from the GRC was traced as a function of conversion on HY. It was found that the relative reactivity of the linear paraffins increased monotonically with paraffin chain length. 43 refs., 11 figs., 8 tabs.

Guerzoni, F.N.; Abbot, J. (Univ. of Tasmania (Australia))

1994-06-01T23:59:59.000Z

225

Fatigue and environmentally assisted cracking in light water reactors  

SciTech Connect

Fatigue and stress corrosion cracking (SCC) for low-alloy steel used in piping and in steam generator and reactor pressure vessels have been investigated. Fatigue data were obtained on medium-sulfur-content A533-Gr B and A106-Gr B steels in high-purity (HP) deoxygenated water, in simulated pressurized water reactor water, and in air. Analytical studies focused on the behavior of carbon steels in boiling water reactor (BWR) environments. Crack-growth rates of composite fracture-mechanics specimens of A533-Gr B/Inconel-182/Inconel-600 (plated with nickel) and homogeneous specimens of A533-Gr B steel were determined under small-amplitude cyclic loading in HP water with {approx}300 pbb dissolved oxygen. Radiation-induced segregation and irradiation-assisted SCC of Type 304 SS after accumulation of relatively high fluence also have been investigated. Microchemical and microstructural changes in HP and commercial-purity Type 304 SS specimens from control-blade absorber tubes used in two operating BWRs were studied by Auger electron spectroscopy and scanning electron microscopy, and slow-strain-rate tensile tests were conducted on tubular specimens in air and in simulated BWR water at 289{degrees}C.

Kassner, T.F.; Ruther, W.E.; Chung, H.M.; Hicks, P.D.; Hins, A.G.; Park, J.Y.; Shack, W.J.

1992-03-01T23:59:59.000Z

226

De-alloying and stress-corrosion cracking. Final report  

SciTech Connect

This research program has had two major areas of focus that are related: (1) alloy corrosion and (2) the role of selective dissolution in the stress corrosion cracking of alloy systems. These interrelated issues were examined using model systems such as Ag-Au and Cu-Au by conventional electrochemical techniques, in situ scanning tunneling microscopy (STM), in situ small angle neutron scattering (SANS), ultrahigh speed digital photography of fracture events, and computer simulations. The STM and SANS work were specifically aimed at addressing a roughening transition known to occur in alloy systems undergoing corrosion at electrochemical potentials greater than the so-called critical potential. Analytical models of de-alloying processes including the roughening transition were developed that specifically include curvature effects that are important in alloy corrosion processes. Stress-corrosion experiments were performed on the same model systems using rapid optical and electrochemical techniques on 50 {micro}m--250 {micro}m thick sheets and small diameter wires. The primary goal of this work was to develop a fundamental understanding of the corrosion and electrochemistry of alloys and the stress-corrosion cracking processes these alloys undergo. Computer simulations and analytical work identified surface stress and an important parameter in environmentally assisted fracture. The major results of the research on this program since the summer of 1993 are briefly summarized.

Sieradzki, K.

1998-09-01T23:59:59.000Z

227

Validation of the state-space model of fatigue crack growth in ductile alloys under variable-amplitude load via comparison of the crack-opening stress data  

Science Journals Connector (OSTI)

A state-space model of fatigue crack growth in ductile alloys under variable-amplitude load was presented by Patankar and Ray (Patankar...International Journal of Fracture, 90, 235--249; Patankar and Ray (2000).

Ravindra Patankar; Rong Qu

2005-02-01T23:59:59.000Z

228

DEVELOPMENT AND CONSTRUCTION OF LOW-CRACKING HIGH-PERFORMANCE CONCRETE (LC-HPC) BRIDGE DECKS: FREE SHRINKAGE TESTS, RESTRAINED RING TESTS, CONSTRUCTION EXPERIENCE, AND CRACK SURVEY RESULTS  

E-Print Network (OSTI)

The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained during the construction of 13 LC-HPC bridge ...

Yuan, Jiqiu

2011-12-31T23:59:59.000Z

229

Fibrin but Not Adsorbed Fibrinogen Supports Fibronectin Assembly by Spread Platelets  

E-Print Network (OSTI)

Fibrin but Not Adsorbed Fibrinogen Supports Fibronectin Assembly by Spread Platelets EFFECTS on fibrin matrices than by platelets spread on adsorbed fibrinogen. The difference between platelets adherent to adsorbed mutant fibrinogen lacking the QAGDV sequence ( 5FG) were assembly-competent, as were

Mosher, Deane F.

230

A model of the spread of randomly scanning Internet worms that saturate access links  

Science Journals Connector (OSTI)

We present a simple, deterministic mathematical model for the spread of randomly scanning and bandwidth-saturating Internet worms. Such worms include Slammer and Witty, both of which spread extremely rapidly. Our model, consisting of coupled Kermack-McKendrick ... Keywords: Internet worms, communications/computer networking, epidemiology, modeling

George Kesidis; Ihab Hamadeh; Youngmi Jin; Soranun Jiwasurat; Milan Vojnovi?

2008-04-01T23:59:59.000Z

231

Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using the  

E-Print Network (OSTI)

Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using-- Analysis of detectability of the kurtosis algorithm for pulsed-sinusoidal Radio Frequency Interference (RFI) has already been performed in detail. The detectability for wide- band spread-spectrum RFI

Ruf, Christopher

232

Spread of cattle led to the loss of matrilineal descent in Africa: a coevolutionary analysis  

Science Journals Connector (OSTI)

...2003 research-article Spread of cattle led to the loss of matrilineal descent in Africa...support the hypothesis that acquiring cattle led formerly matrilineal Bantu-speaking cultures...Coevolution|Phylogeny| Spread of cattle led to the loss of matrilineal descent in Africa...

2003-01-01T23:59:59.000Z

233

Temporal variations of the segmentation of slow to intermediate spreading mid-ocean ridges  

E-Print Network (OSTI)

Tectonophysics: Dynamics, convection currents and mantle plumes; KEYWORDS: Mid-ocean ridge, mantle convectionTemporal variations of the segmentation of slow to intermediate spreading mid-ocean ridges 1 missions reveal a set of small-scale lineations on the flanks of slow to intermediate spreading mid- ocean

Boyer, Edmond

234

Measurement of focal spread, beam divergence and vibration in HREM images CB Boothroyd1*  

E-Print Network (OSTI)

Measurement of focal spread, beam divergence and vibration in HREM images CB Boothroyd1* and RE, the measurement of focal spread, beam divergence and specimen vibration is more difficult, as these parameters from the change in the intensity around each ring measured as a function of defocus, and vibration can

Dunin-Borkowski, Rafal E.

235

GIS-Based Epidemiological Modeling of an Emerging Forest Disease: Spread of  

E-Print Network (OSTI)

247 GIS-Based Epidemiological Modeling of an Emerging Forest Disease: Spread of Sudden Oak Death applied in a GIS to real-world wildland landscapes. In this paper, we present and evaluate a GIS model was implemented (1990-2005) in a GIS to simulate disease spread across California at a spatial

Standiford, Richard B.

236

Observations of the longitudinal spread of solar energetic particle events in solar cycle 24  

E-Print Network (OSTI)

Observations of the longitudinal spread of solar energetic particle events in solar cycle 24 C://proceedings.aip.org/about/rights_permissions #12;Observations of the Longitudinal Spread of Solar Energetic Particle Events in Solar Cycle 24 C-based satellites such as ACE, simultaneous multi-point measurements of solar energetic particle (SEP

Jensen, Grant J.

237

Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite  

E-Print Network (OSTI)

when the material is subjected to temperature gradients and is therefore relevant to its thermal shock resistance. The present study focuses on the effects of a periodic array of matrix cracks on thermal displacement are used to determine the contributions to the longitudinal thermal resistance due to each crack

Zok, Frank

238

Interaction between corrosion crack width and steel loss in RC beams corroded under load  

SciTech Connect

This paper presents results and discussions on an experimental study conducted to relate the rate of widening of corrosion cracks with the pattern of corrosion cracks as well as the level of steel corrosion for RC beams (153 x 254 x 3000 mm) that were corroded whilst subjected to varying levels of sustained loads. Steel corrosion was limited to the tensile reinforcement and to a length of 700 mm at the centre of the beams. The rate of widening of corrosion cracks as well as strains on uncracked faces of RC beams was constantly monitored during the corrosion process, along the corrosion region and along other potential cracking faces of beams using a demec gauge. The distribution of the gravimetric mass loss of steel along the corrosion region was measured at the end of the corrosion process. The results obtained showed that: the rate of widening of each corrosion crack is dependent on the overall pattern of the cracks whilst the rate of corrosion is independent of the pattern of corrosion cracks. A mass loss of steel of 1% was found to induce a corrosion crack width of about 0.04 mm.

Malumbela, Goitseone, E-mail: malumbela@mopipi.ub.b [Dpt. of Civil Eng., Univ. of Cape Town, Private Bag X3, Rondebosch, 7700 (South Africa); Alexander, Mark; Moyo, Pilate [Dpt. of Civil Eng., Univ. of Cape Town, Private Bag X3, Rondebosch, 7700 (South Africa)

2010-09-15T23:59:59.000Z

239

Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams  

SciTech Connect

This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied.

Khan, Inamullah; François, Raoul [Université de Toulouse, UPS, INSA, LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, Avenue de Rangueil, F-31077 Toulouse (France)] [Université de Toulouse, UPS, INSA, LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, Avenue de Rangueil, F-31077 Toulouse (France); Castel, Arnaud [Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW (Australia)] [Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW (Australia)

2014-02-15T23:59:59.000Z

240

THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice*  

E-Print Network (OSTI)

THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice* ABSTRACT This paper briefly reviews progres~in the elastic plastic analysisof crack extension. Analytical results for plane strain and plane stress deformation fields are noted, and elastic-plastic fracture instability as well as transitional

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Adsorption and Desorption of Hydrocarbons on a Supported Nickel Cracking Catalyst  

Science Journals Connector (OSTI)

...Hydrocarbons on a Supported Nickel Cracking Catalyst A. K. Galwey A study has been made...a high area supported nickel cracking catalyst. Measurements have been made of (i...adsorbed, after standard preparation of the catalyst, when a known volume of each hydrocarbon...

1963-01-01T23:59:59.000Z

242

Sorption and Diffusion of Simple Paraffins in Silica-Alumina Cracking Catalyst  

Science Journals Connector (OSTI)

...Paraffins in Silica-Alumina Cracking Catalyst R. M. Barrer T. Gabor Sorption and...propane in the silica-alumina cracking catalyst previously employed in similar measurements...behaviour in the micropore structure of the catalyst, for the species studied. The ratio...

1960-01-01T23:59:59.000Z

243

TRANSIENT FATIGUE-CRACK GROWTH BEHAVIOR FOLLOWING VARIABLE-AMPLITUDE LOADING IN A  

E-Print Network (OSTI)

TRANSIENT FATIGUE-CRACK GROWTH BEHAVIOR FOLLOWING VARIABLE-AMPLITUDE LOADING IN A MONOLITHIC-crack growth behavior following variable-amplitude loading sequences has been investigated in a hot-toughened ceramics [13] following various variable-amplitude loading sequences. Transient retardations, involving

Ritchie, Robert

244

Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and  

E-Print Network (OSTI)

Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows

Ritchie, Robert

245

Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D  

E-Print Network (OSTI)

Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D W. Zhou*, T. Z. Long and C. K ductility, and the HAZ was found to be the `weakest link'. Keywords: Magnesium alloy, AZ91D, TIG welding, Hot cracking, Liquation, Fracture Introduction Magnesium alloys have high strength/weight ratio

Zhou, Wei

246

The effects of stress and fluid pressure on the anisotropy of interconnected cracks  

Science Journals Connector (OSTI)

......compressive stress, as it hinders the process of crack closure (Fig. 1a). Crack...decreasing the anisotropy. These two competing processes explain the rise in the anisotropy parameters...effective pressure, in 70th Ann. Int. Mtg SEG, Exp. Abs., pp. 1826-1829....

S. R. Tod

2002-04-01T23:59:59.000Z

247

Brittle fracture in a periodic structure with internal potential energy. Spontaneous crack propagation  

E-Print Network (OSTI)

Spontaneous brittle fracture is studied based on the recently introduced model (Mishuris and Slepyan, Brittle fracture in a periodic structure with internal potential energy. Proc. Roy. Soc. A, in press). A periodic structure is considered, where only the prospective crack-path layer is specified as a discrete set of alternating initially stretched and compressed bonds. A bridged crack destroying initially stretched bonds may propagate under a certain level of the internal energy without external sources. The general analytical solution with the crack speed $-$ energy relation is presented in terms of the crack-related dynamic Green's function. For the anisotropic two-line chain and lattice considered earlier in quasi-statics, the dynamic problem is examined in detail. The crack speed is found to grow unboundedly as the energy approaches its upper limit. It is revealed that the spontaneous fracture can occur in the form of a pure bridged, partially bridged or fully open crack depending on the internal energy level. Generally, the steady-state mode of the crack propagation is found to be realised, whereas an irregular growth, clustering and the crack speed oscillations are detected in a vicinity of the lower bound of the energy.

Mark Ayzenberg-Stepanenko; Gennady Mishuris; Leonid Slepyan

2014-02-12T23:59:59.000Z

248

DEVELOPMENT OF NONLINEAR TIME REVERSED ACOUSTICS (NLTRA) FOR APPLICATIONS TO CRACK DETECTION IN SOLIDS  

E-Print Network (OSTI)

of Nondestructive Evaluation (NDE) exhibit extremely high sensitivity to the presence of cracks. Time Reverse stones and long-distance communication in the ocean. The Nondestructive Evaluation (NDE) applications,4] and detection of cracks in a thin air-filled hollow cylinder [5]. A review of TRA applications to NDE is given

249

Autonomous Crack Displacement Monitoring of a Residence Near a Quarry David E. Kosnik, Northwestern University  

E-Print Network (OSTI)

Autonomous Crack Displacement Monitoring of a Residence Near a Quarry David E. Kosnik, Northwestern remote mon- itoring of cracks in interior and exterior walls of a residence near a limestone quarry for construction and raw materials. For instance, neighbors of road aggregate quarries often perceive

250

Autonomous Remote Crack Displacement Monitoring of a Residence Near a Limestone  

E-Print Network (OSTI)

Autonomous Remote Crack Displacement Monitoring of a Residence Near a Limestone Quarry, Naples a limestone quarry. The object is to quantitatively compare crack re- sponse to blast-induced ground motion for construction and raw materials. For instance, neighbors of road aggregate quarries often perceive

251

Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within the oxide layer  

E-Print Network (OSTI)

Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within with stress-induced surface oxide thicken- ing and moisture-assisted subcritical cracking in the amor- phous

Ritchie, Robert

252

Analysis of Fatigue Crack Growth under Random Load Sequences Derived from Military In-flight Load Data  

Science Journals Connector (OSTI)

The crack growth process of a crack initiating at a hole of a skin-stringer panel in a fighter aircraft subjected to random variable amplitude loading is investigated in this paper. The generation of synthetic...

C. Mattrand; J. -M. Bourinet; D. Théret

2011-01-01T23:59:59.000Z

253

Bilateral propagation of a spontaneous two-dimensional anti-plane shear crack under the influence of cohesion  

Science Journals Connector (OSTI)

......cracks, the calculations of the time- dependent fault motions and the corresponding seismograms as the crack propagates, pro- ceed much as in the cases of uniform extension. The principal differences are that, whereas the coordinates of the edges can be......

A. K. Chatterjee; L. Knopoff

1983-05-01T23:59:59.000Z

254

Spectroscopic studies on the formation of coke on individual Fluid Catalytic Cracking particles: the effect of poisoning metal compounds.  

E-Print Network (OSTI)

??The formation of coke on individual Fluid Catalytic Cracking (FCC) catalyst particles was studied using UV/Vis microspectroscopy and confocal fluorescence microscopy, with n-hexane cracking as… (more)

Goetze, J.G.

2013-01-01T23:59:59.000Z

255

Hydride-phase formation and its influence on fatigue crack propagationbehavior in a Zircaloy-4 alloy  

SciTech Connect

The hydride-phase formation and its influence on the fatigue behavior of a Zircaloy-4 alloy charged with hydrogen gas are investigated. First, the microstructure and fatigue crack propagation rate of the alloy in the as-received condition are studied. Second, the formation and homogeneous distribution of delta zirconium hydride ( -ZrH2) in the bulk, and its effect on the fatigue crack propagation rate are presented. The results show that in the presence of hydrides the zirconium alloy exhibits reduced toughness and enhanced crack growth rates. Finally, the influence of a pre-existing fatigue crack in the specimen and the subsequent hydride formation were investigated. The residual lattice strain profile around the fatigue crack tip was measured using neutron diffraction. The combined effects of residual strains and hydride precipitation on the fatigue behavior are discussed.

Garlea, Elena [University of Tennessee, Knoxville (UTK); Choo, H. [University of Tennessee, Knoxville (UTK); Wang, G Y [University of Tennessee, Knoxville (UTK); Liaw, Peter K [University of Tennessee, Knoxville (UTK); Clausen, B [Los Alamos National Laboratory (LANL); Brown, D. W. [Los Alamos National Laboratory (LANL); Park, Jae-Sung [University of Tennessee, Knoxville (UTK); Rack, P. D. [University of Tennessee, Knoxville (UTK); Kenik, Edward A [ORNL

2010-01-01T23:59:59.000Z

256

Fatigue crack propagation in a quasi one-dimensional elasto-plastic model  

E-Print Network (OSTI)

Fatigue crack advance induced by the application of cyclic quasistatic loads is investigated both numerically and analytically using a lattice spring model. The system has a quasi-one-dimensional geometry, and consists in two symmetrical chains that are pulled apart, thus breaking springs which connect them, and producing the advance of a crack. Quasistatic crack advance occurs as a consequence of the plasticity included in the springs which form the chains, and that implies a history dependent stress-strain curve for each spring. The continuous limit of the model allows a detailed analytical treatment that gives physical insight of the propagation mechanism. This simple model captures key features that cause well known phenomenology in fatigue crack propagation, in particular a Paris-like law of crack advance under cyclic loading, and the overload retardation effect.

Tomás M. Guozden; Eduardo A. Jagla

2012-06-27T23:59:59.000Z

257

Characterization of elevated temperature crack growth in Hastelloy-X using integral parameters  

SciTech Connect

Linear elastic fracture mechanics approaches are not suitable for prediction of fatigue crack growth in the nonlinear regime at elevated temperatures. The objective of this paper is to investigate the ability of the integral parameters by Blackburn (J*), by Kishimoto et al. ({cflx J}), and by Atluri et al. ({Delta}Tp*, {Delta}Tp) to correlate crack growth data of Hastelloy-X at elevated temperatures under nominally elastic and nominally plastic loading. Crack growth is analyzed using a finite element method, and the integral parameters are computed from the results of analysis. The experimental crack growth rates are correlated with these parameters. It is found that J*, {cflx J}, and {Delta}Tp* can correlate crack growth data within an acceptable accuracy.

Kim, K.S. [Pohang Univ. of Science and Technology (Korea, Republic of). Dept. of Mechanical Engineering; Van Stone, R.H. [General Electric Aircraft Engines, Cincinnati, OH (United States)

1995-07-01T23:59:59.000Z

258

PHYSICAL REVIEW E 84, 036104 (2011) Average crack-front velocity during subcritical fracture propagation in a heterogeneous medium  

E-Print Network (OSTI)

PHYSICAL REVIEW E 84, 036104 (2011) Average crack-front velocity during subcritical fracture]. In consequence the slow kinetic crack propagation is usually referred to as subcritical crack growth or the subcritical regime. Statistical physics models suggest that this subcritical regime is governed by a thermally

Schmittbuhl, Jean

259

A continuing investigation into the stress field around two parallet-edge cracks in a finite body  

E-Print Network (OSTI)

,7 ........................................................................................... 5 2.1 Two Parallel Edge Cracks in a Four Point Bending Member.............................. 7 2.2 Westergaard Stress Functions and Resulting Stress Intensity Factors for a Crack with Applied Tractions Along Its Faces... .................................................................... 31 4.2 Mesh Created for Numerical Model (Zoomed in on Crack Interaction Region) ............................................................................................. 32 5.1 Open Mode Stress Intensity Factor Percent...

Gilman, Justin Patrick

2005-02-17T23:59:59.000Z

260

ensl-00156750,version1-22Jun2007 A dynamical law for slow crack growth in polycarbonate films  

E-Print Network (OSTI)

that subcritical crack growth in paper sheets can be successfully described by a thermally activated mechanismensl-00156750,version1-22Jun2007 A dynamical law for slow crack growth in polycarbonate films: 24 juin 2007) We study experimentally the slow growth of a single crack in polycarbonate films

Paris-Sud XI, Université de

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Thin Film Cracking Modulated by Underlayer Creep by J. Liang, R. Huang, J.H. Prvost, and Z. Suo  

E-Print Network (OSTI)

: subcritical decohesion at the crack tip, and creep in the underlayer. In a thin-film microbridge over for the growth rate per temperature cycle of a channel crack in a brittle film, induced by ratcheting plasticThin Film Cracking Modulated by Underlayer Creep by J. Liang, R. Huang, J.H. Prévost, and Z. Suo

Huang, Rui

262

Effect of Surface Morphology on Crack Growth at a Sol-Gel Reinforced Epoxy/Aluminum Interface  

E-Print Network (OSTI)

the measurements of the critical energy-release rate, subcritical crack-growth kinetics, and threshold energyEffect of Surface Morphology on Crack Growth at a Sol-Gel Reinforced Epoxy/Aluminum Interface Jiong. Keywords: ADCB wedge test; Crack growth; Durability; Epoxy=aluminum; Sol-gel coating; Surface pretreatment

Chaudhury, Manoj K.

263

EMAT based inspection of natural gas pipelines for SSC cracks  

NLE Websites -- All DOE Office Websites (Extended Search)

EMAT-Based Inspection of Natural Gas EMAT-Based Inspection of Natural Gas Pipelines for Stress Corrosion Cracks FY2004 Report Venugopal K. Varma, Raymond W. Tucker, Jr., and Austin P. Albright Oak Ridge National Laboratory Oak Ridge, Tennessee 37831 1 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name,

264

Material properties effects on the detonation spreading and propagation of diaminoazoxyfurazan (DAAF)  

SciTech Connect

Recent dynamic testing of Diaminoazoxyfurazan (DAAF) has focused on understanding the material properties affecting the detonation propagation, spreading, behavior and symmetry. Small scale gap testing and wedge testing focus on the sensitivity to shock with the gap test including the effects of particle size and density. Floret testing investigates the detonation spreading as it is affected by particle size, density, and binder content. The polyrho testing illustrates the effects of density and binder content on the detonation velocity. Finally the detonation spreading effect can be most dramatically seen in the Mushroom and Onionskin tests where the variations due to density gradients, pressing methods and geometry can be seen on the wave breakout behavior.

Francois, Elizabeth Green [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory; Novak, Alan M [Los Alamos National Laboratory; Kennedy, James E [HERE LLC

2010-01-01T23:59:59.000Z

265

Concrete cover cracking with reinforcement corrosion of RC beam during chloride-induced corrosion process  

SciTech Connect

This paper deals with the evolution of the corrosion pattern based on two beams corroded by 14 years (beam B1CL1) and 23 years (beam B2CL1) of conservation in a chloride environment. The experimental results indicate that, at the cracking initiation stage and the first stage of cracking propagation, localized corrosion due to chloride ingress is the predominant corrosion pattern and pitting corrosion is the main factor that influences the cracking process. As corrosion cracking increases, general corrosion develops rapidly and gradually becomes predominant in the second stage of cracking propagation. A comparison between existing models and experimental results illustrates that, although Vidal et al.'s model can better predict the reinforcement corrosion of beam B1CL1 under localized corrosion, it cannot predict the corrosion of beam B2CL1 under general corrosion. Also, Rodriguez's model, derived from the general corrosion due to electrically accelerated corrosion experiments, cannot match natural chloride corrosion irrespective of whether corrosion is localized or general. Thus, for natural general corrosion in the second stage of cracking propagation, a new model based on the parameter of average steel cross-section loss is put forward to predict steel corrosion from corrosion cracking.

Zhang Ruijin, E-mail: rjzhang@mail.neu.edu.c [Modern Design and Analysis Research Institute, Northeastern University, Shenyang (China); Castel, Arnaud; Francois, Raoul [LMDC - Laboratoire Materiaux et Durabilite des Constructions, Universite de Toulouse, UPS, INSA, Toulouse (France)

2010-03-15T23:59:59.000Z

266

Response of Surface Cracks in Tubular Members During Global Buckling and Instability  

Science Journals Connector (OSTI)

Abstract Beam-columns in compression are subject to potential buckling. If the axial load is combined with a global bending moment, member instability may occur. One situation where this can occur is for pipelines on the seabed, where thermal strains induce significant compression in the pipeline due to constrained expansion. This may lead to upheaval buckling or snaking. In this condition one should also assess how a weld defect in the buckle zone will evolve. If the crack is located on the compressive side of the cross section, the crack remains closed. If the crack is located on the side where beam bending eventually leads to tension, fracture may develop. This has not been studied sufficiently in the past, and is the topic of the present paper. Here the interesting case of initial compression, with closure of the crack, is followed by a transition to tension and opening of the crack when the transverse displacement increases in the post-buckling regime. Simple cases of tubular beam-columns with surface cracks are investigated for cracks growing in a ductile manner. The simulations are based on shell and linespring finite elements.

Bjřrn Skallerud

2014-01-01T23:59:59.000Z

267

A displacement-based method for predicting plasticity-induced fatigue crack closure  

SciTech Connect

A numerical method for predicting closure and its effects on thermomechanical crack growth has been developed. A finite element model, using linear-elastic fracture mechanics shape functions, is employed to predict crack tip displacements. The effective changes in stress intensity, and therefore crack growth, are obtained from the minimum and maximum crack tip displacement predictions. When a flaw is loaded in Mode 1, a ligament of material ahead of the flaw yields, and a maximum crack tip displacement is computed. Upon unloading, plastically deformed material from prior plastic zones acts to limit the minimum displacements of the crack tip. The material is modeled as elastic-perfectly plastic. The yield strength of the material is varied based on the degree of constraint. The upper limit of constraint is a plane strain condition while the lowest constraint is a plane stress condition. The level of constraint is predicted by relating the stress intensity to the thickness of the component. Temperatures also affect yield strength, along with stiffness, and can cause the plastic zone to expand due to creep. During variable-amplitude loadings, and/or temperature changes, the irregular shape of the wake can be accommodated with this numerical procedure. The method has proven to accurately account for load interaction effects such as delayed retardation, crack arrest, initial accelerations following overloads, and the transient growth and stabilization of closure level with number of overloads.

Pawlik, M.E.; Saff, C.R.

1999-07-01T23:59:59.000Z

268

Analysis of cracking of co-extruded recovery boiler floor tubes  

SciTech Connect

Cracking of the stainless steel layer in co-extruded 304L/SA210 tubing used in black liquor recovery boilers is being found in an ever-increasing number of North American pulp and paper mills. Because of the possibility of a tube failure, this is a significant safety issue, and, because of the extra time required for tube inspection and repair, this can become an economic issue as well. In a project funded by the U.S. Department of Energy and given wide support among paper companies, boiler manufacturers, and tube fabricators, studies are being conducted to determine the cause of the cracking and to identify alternate materials and/or operating procedures to prevent tube cracking. Examination of cracked tubes has permitted characterization of crack features, and transmission electron microscopy is providing information about the thermal history, particularly cyclic thermal exposures, that tubes have experienced. Neutron and x-ray diffraction techniques are being used to determine the residual stresses in as-fabricated tube panels and exposed tubes, and finite element modeling is providing information about the stresses the tubes experience during operation. Laboratory studies are being conducted to determine the susceptibility of the co-extruded 304L/SA210 tubes to stress corrosion cracking, thermal fatigue, and corrosion in molten smelt. This paper presents the current status of these studies. On the basis of all of these studies, recommendations for means to prevent tube cracking will be offered.

Keiser, J.R.; Taljat, B.; Wang, X.L. [and others

1997-08-01T23:59:59.000Z

269

Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels  

SciTech Connect

Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear fuels are critical to understand the burnup, and thus the fuel efficiency.

Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott

2014-01-09T23:59:59.000Z

270

Response Surfaces for optimal weight of cracked composite panels: noise and accuracy  

E-Print Network (OSTI)

Two levels of fidelity are used for minimum weight design of a composite blade-stiffened panel subject to crack propagation constraints. The low fidelity approach makes use of an equivalent strain constraint calculated by a closed form solution for the stress intensity factor. The high fidelity approach uses the stress intensity factor directly as the constraint and computes it from the stress distribution around the crack. A number of panels were optimized by both approaches for different values of applied load, crack length, and blade height, and response surface approximations for optimal weight as function of these configuration variables were constructed. Computational cost, noise and accuracy for the results are compared.

Melih Papila; Raphael T. Haftka

271

Fundamentals of Petroleum Residue Cracking Gasification for Coproduction of Oil and Syngas  

Science Journals Connector (OSTI)

Fundamentals of Petroleum Residue Cracking Gasification for Coproduction of Oil and Syngas ... Thus, the terminology of heavy oil or heavy residue can be also used to indicate all such heavy petroleum oils. ... Notwithstanding, for the RCG process it is ideal to develop the catalyst that has moderate cracking activity for heavy residues or heavy oils but meanwhile good activity for catalyzing the deposited coke gasification so that the gasification can be at reasonably low temperatures to maintain the catalytic activity for cracking heavy fractions. ...

Yuming Zhang; Deping Yu; Wangliang Li; Yin Wang; Shiqiu Gao; Guangwen Xu

2012-10-23T23:59:59.000Z

272

Eddy?Current Inspection of Cracking in Land?Based Gas Turbine Blades  

Science Journals Connector (OSTI)

There has been a growing need in the electric utility industry to assess the remaining life of blades in gas turbines. It is quite important to nondestructively comprehend the depths of surface?breaking cracks in blades. Flexible eddy current array probes have been developed to overcome the major limitations of existing eddy current inspection systems. The use of an array of sensors allows cracks of all lengths to be detected and will ultimately allow real time data imaging to provide rapid inspection and easy interpretation. For this study using eddy current techniques crack detection equipment has been developed and applied to gas turbine Stage 1 blades for field use.

H. Fukutomi; T. Ogata

2004-01-01T23:59:59.000Z

273

The stress field around two parallel edge cracks in a finite body  

E-Print Network (OSTI)

the application of the Schwarz alternating method in conjunction with complex mapping techniques for modelling the stress fields around two arbitrarily oriented cracks in an infinite body (see Fig. 1. 4). M P 0. 83W I. 83W Again 19. Isolated, Single...-Ended Crack Located in a Finite Body. " Zo r A I I 0 I Figure IA. Two Aibitnuily Oiiented Conchs Located in an Infinite Body. t CHAFIXR II FULL-FIELD REPRESENTATION OF THE STRESS FIELD SURROUNDING TWO EDGE CRACKS OVERVIEW OF THE METHODOLOGY USED...

Hardin, Patrick Wayne

2012-06-07T23:59:59.000Z

274

Effects of thickness on plasticity-induced fatigue crack closure: Analysis and experiment  

SciTech Connect

The crack-opening stress was measured using a strain gage technique on 7050 aluminum alloy, under constant amplitude and repeated overload. The behavior of crack-opening stress predicted by Newman's FASTRAN-II is consistent with the experimental results for repeated overload. It is also found that the FASTRAN-II program is capable of predicting crack growth on the 7050-T76 aluminum plate and 7050-T76 aluminum plate and 7050-T7452 aluminum hand forging under complex simulated flight loading which contains a significant number of compression cycles.

Hsu, C.; Chan, K.K.; Yu, J.

1999-07-01T23:59:59.000Z

275

A quantitative determination of the conditions for hot cracking during welding for aluminum alloys  

E-Print Network (OSTI)

Memorial Institute, February 1964. 2. Savage, W. F. and Krantz, B. M. , "An Investigation of Hot Cracking in Hastelloy X, ' ~Weldin Journal, 45(51, 13s-25s (1966) . Borland, J. C. and Younger, R. N. , "Some Aspects of Cracking in Cr-Ni Austenite Steels...-T6 Alu?iinum 25 10 Typical Load-Temperature Data 26 Typical Modulus of Elasticity Verses Temperature Re1atiousI!ip fcr Aluminum Alloys 32 12 As-Received and Ai. r Cooled (T = 1125'P) 6061-T6 Specimens (100X) 37 13 Hot Cracked 6061-T6 Aluminur...

Steenbergen, James Everett

1969-01-01T23:59:59.000Z

276

VR/Urban: Spread.gun Design Process and Challenges in Developing a Shared Encounter for Media Faades  

E-Print Network (OSTI)

VR/Urban: Spread.gun ­ Design Process and Challenges in Developing a Shared Encounter for Media intervention tool called Spread.gun, which was created for the Media Façade Festival 2008 in Berlin. Main social change. In this paper, we discuss our Spread.gun installation as a case study exemplifying

Hornecker, Eva

277

Second Price Component: Spread Impacted by Distillate Supply/Demand Balance  

Gasoline and Diesel Fuel Update (EIA)

8 8 Notes: While crude oil prices will be a major factor impacting distillate prices this winter, another important factor is the U.S. distillate supply/demand balance, as measured by distillate stocks. The distillate supply/demand balance influences the spread between spot distillate and spot crude oil prices. For example, when stocks are higher than normal, the spread will be lower than usual. This spread is the price incentive that encourages or discourages changes in supply. While high stocks in the distillate market are good news for consumers, an excess is bad news for refiners. Distillate spreads during the winter of 1998-99 and throughout most of 1999 were well below average. Distillate stocks were very high during this period, partially as a result of warm weather keeping demand down.

278

Energy Tax Credits: Secretary Chu is Spreading the Word, and You Should,  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Secretary Chu is Spreading the Word, and You Secretary Chu is Spreading the Word, and You Should, Too! Energy Tax Credits: Secretary Chu is Spreading the Word, and You Should, Too! March 29, 2010 - 7:30am Addthis Allison Casey Senior Communicator, NREL As we've mentioned many times on the Energy Savers blog, you can receive up to $1,500 in tax credits for home energy efficiency improvements like adding insulation, installing energy efficient windows, or replacing water heaters. If you're a regular reader, you know that we write about tax credits a lot. Our reasons are simple: we don't want you to forget that these credits are available, and we hope you'll help spread the word by sharing this info with your friends and family. (There are even some handy links at the bottom for you to send this article to your favorite social media

279

SmartPower Spreading Energy Efficiency to Echo-boomers | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

SmartPower Spreading Energy Efficiency to Echo-boomers SmartPower Spreading Energy Efficiency to Echo-boomers SmartPower Spreading Energy Efficiency to Echo-boomers April 9, 2010 - 4:36pm Addthis Paul Lester Communications Specialist, Office of Energy Efficiency and Renewable Energy What are the key facts? Research shows that once young people start unplugging unused electronic devices, they are likely to take more action to reduce their energy use. Saving energy is cool. That's the message SmartPower is spreading online to 80 million echo-boomers, the generation born between 1982 and 1995. "They are the generation that best appreciates the need for mitigation of climate change," says Jonathan Edwards, vice president of SmartPower, a non-profit that has developed creative Web marketing campaigns aimed at

280

SmartPower Spreading Energy Efficiency to Echo-boomers | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

SmartPower Spreading Energy Efficiency to Echo-boomers SmartPower Spreading Energy Efficiency to Echo-boomers SmartPower Spreading Energy Efficiency to Echo-boomers April 9, 2010 - 4:36pm Addthis Paul Lester Communications Specialist, Office of Energy Efficiency and Renewable Energy What are the key facts? Research shows that once young people start unplugging unused electronic devices, they are likely to take more action to reduce their energy use. Saving energy is cool. That's the message SmartPower is spreading online to 80 million echo-boomers, the generation born between 1982 and 1995. "They are the generation that best appreciates the need for mitigation of climate change," says Jonathan Edwards, vice president of SmartPower, a non-profit that has developed creative Web marketing campaigns aimed at

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Predictable waves of sequential forest degradation and biodiversity loss spreading from an African city  

E-Print Network (OSTI)

- tainably reducing carbon storage and biodiversity. biodiversity conservation | carbon emissions | reducing, wood production, and biodiversity conservation. The impacts of individual forms of tropical forestPredictable waves of sequential forest degradation and biodiversity loss spreading from an African

Vermont, University of

282

Beam energy spread in FERMI@elettra gun and linac induced by intrabeam scattering  

E-Print Network (OSTI)

spread in FERMI@elettra gun and linac induced by intrabeamcathode area in the electron guns know in the literature asmost visible within the electron gun where the electron beam

Zholents, Alexander A

2008-01-01T23:59:59.000Z

283

Tradeoffs of Source Coding, Channel Coding and Spreading in Frequency Selective Rayleigh Fading Channels  

Science Journals Connector (OSTI)

This paper investigates the tradeoffs of source coding, channel coding and spreading in CDMA systems. We consider a system consisting of an image source coder, a convolutional channel coder, an interleaver, an...

1]Qinghua Zhao; Pamela Cosman…

2002-01-01T23:59:59.000Z

284

Spreading of Sn-Ag solders on FeNi alloys  

SciTech Connect

The spreading of Sn-3Ag-xBi solders on Fe-42Ni has been studied using a drop transfer setup. Initial spreading velocities as fast as {approx}0.5 m/s have been recorded. The results are consistent with a liquid front moving on a metastable, flat, unreacted substrate and can be described by using a modified molecular-kinetic model for which the rate controlling step is the movement of one atom from the liquid to the surface of the solid substrate. Although the phase diagram predicts the formation of two Fe-Sn intermetallics at the solder/substrate interface in samples heated at temperatures lower than 513 C, after spreading at 250 C only a thin FeSn reaction layer could be observed. Two interfacial layers (FeSn and FeSn2) were found after spreading at 450 C.

Saiz, Eduardo; Hwang, C-W.; Suganuma, Katsuaki; Tomsia, Antoni P.

2003-02-28T23:59:59.000Z

285

Collisional spreading of Enceladus' neutral cloud T.A. Cassidy *, R.E. Johnson  

E-Print Network (OSTI)

Collisional spreading of Enceladus' neutral cloud T.A. Cassidy *, R.E. Johnson Charlottesville exchange momentum, causing deflections whether or not a charge exchange occurs (e.g., Johnson et al., 2006a

Johnson, Robert E.

286

The tectonics and three-dimensional structure of spreading centers--microearthquake studies and tomographic inversions  

E-Print Network (OSTI)

Two-thirds of the Earth's surface has been formed along a global system of spreading centers that are presently manifested in several different structural forms, including the classic rift valley of the Mid-Atlantic Ridge, ...

Toomey, Douglas R

1987-01-01T23:59:59.000Z

287

The spread of violent civil conflict : rare state-driven, and preventable  

E-Print Network (OSTI)

This dissertation advances and tests an explanation for the spread of violent civil conflict from one state to another. The fear of such "substate conflict contagion" is frequently invoked by American policymakers as a ...

Black, Nathan Wolcott

2012-01-01T23:59:59.000Z

288

Energy Tax Credits: Secretary Chu is Spreading the Word, and You Should,  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Energy Tax Credits: Secretary Chu is Spreading the Word, and You Energy Tax Credits: Secretary Chu is Spreading the Word, and You Should, Too! Energy Tax Credits: Secretary Chu is Spreading the Word, and You Should, Too! March 29, 2010 - 7:30am Addthis Allison Casey Senior Communicator, NREL As we've mentioned many times on the Energy Savers blog, you can receive up to $1,500 in tax credits for home energy efficiency improvements like adding insulation, installing energy efficient windows, or replacing water heaters. If you're a regular reader, you know that we write about tax credits a lot. Our reasons are simple: we don't want you to forget that these credits are available, and we hope you'll help spread the word by sharing this info with your friends and family. (There are even some handy links at the bottom for you to send this article to your favorite social media

289

Landau damping effects and evolutions of energy spread in small isochronous ring  

SciTech Connect

This paper presents the Landau damping effects on the microwave instability of a coasting long bunch in an isochronous ring due to finite energy spread and emittance. Our two-dimensional (2D) dispersion relation gives more accurate predictions of the microwave instability growth rates of short-wavelength perturbations than the conventional 1D formula. The long-term evolution of energy spread is also studied by measurements and simulations.

Li, Yingjie [Michigan State University; Wang, Langfa [SLAC; Lin, Fanglei [JLAB

2014-11-01T23:59:59.000Z

290

Direct, physically motivated derivation of triggering probabilities for spreading processes on generalized random networks  

E-Print Network (OSTI)

We derive a general expression for the probability of global spreading starting from a single infected seed for contagion processes acting on generalized, correlated random networks. We employ a simple probabilistic argument that encodes the spreading mechanism in an intuitive, physical fashion. We use our approach to directly and systematically obtain triggering probabilities for contagion processes acting on a series of interrelated random network families.

Dodds, Peter Sheridan; Payne, Joshua L

2011-01-01T23:59:59.000Z

291

Enhanced Spreading of Aqueous Films Containing Ionic Surfactants on Solid Substrates  

Science Journals Connector (OSTI)

The spreading behavior of ionic surfactant aqueous systems on organosulfur monolayers with differing compositions and surface energies has been investigated. ... Wetting often plays a critical role in applications such as coatings, cosmetics, agrochemicals, and lubrication. ... The poor understanding of the relationship between surfactant composition and structure and dynamic wetting prompted us to examine the spreading behavior of aqueous media containing a variety of nonionic surfactants. ...

T. Stoebe; Randal M. Hill; Michael D. Ward; H. Ted Davis

1997-12-24T23:59:59.000Z

292

Evaluation of cracking in feedwater piping adjacent to the steam generators in Nine Pressurized Water Reactor Plants  

SciTech Connect

Cracking in ASTM A106-B and A106-C feedwater piping was detected near the inlet to the steam generators in a number of pressurized water reactor plants. We received sections with cracks from nine of the plants with the objective of identifying the cracking mechanism and assessing various factors that might contribute to this cracking. Variations were observed in piping surface irregularities, corrosion-product, pit, and crack morphology, surface elmental and crystal structure analyses, and steel microstructures and mechanical properties. However, with but two exceptions, namely, arrest bands and major surface irregularities, we were unable to relate the extent of cracking to any of these factors. Tensile and fracture toughness (J/sub Ic/ and tearing modulus) properties were measured over a range of temperatures and strain rates. No unusual properties or microstructures were observed that could be related to the cracking problem. All crack surfaces contained thick oxide deposits and showed evidence of cyclic events in the form of arrest bands. Transmission electron microscopy revealed fatigue striations on replicas of cleaned crack surfaces from one plant and possibly from three others. Calculations based on the observed striation spacings gave a value of ..delta..sigma = 150 MPa (22 ksi) for one of the major cracks. The direction of crack propagation was invariably related to the piping surface and not to the piping axis. These two factors are consistent with the proposed concept of thermally induced, cyclic, tensile surface stresses. Although surface irregularities and corrosion pits were sources for crack initiation and corrosion may have contributed to crack propagation, it is proposed that the overriding factor in the cracking problem is the presence of unforeseen cyclic loads.

Goldberg, A.; Streit, R.D.; Scott, R.G.

1980-06-25T23:59:59.000Z

293

Coolant Sub-Channel and Smeared-Cracking Models in BISON | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Coolant Sub-Channel and Smeared-Cracking Models in BISON Coolant Sub-Channel and Smeared-Cracking Models in BISON Coolant Sub-Channel and Smeared-Cracking Models in BISON January 29, 2013 - 10:45am Addthis Coolant Sub-Channel and Smeared-Cracking Models in BISON A single-pin coolant sub-channel model was implemented in BISON, the pin-scale simulation code. This enables BISON to compute the heat transfer coefficient and coolant temperature as a function of axial position along the fuel pin (rather than requiring this information to be supplied by the user). At present, the model is only applicable to pressurized water reactor coolant conditions, but modifications to include boiling water reactor (BWR) coolant conditions are in progress. A preliminary UO2 thermal and irradiation creep model has been implemented in BISON and is

294

The Co-cracking Experiment and Application Route of Waste Plastics and Heavy Oil  

Science Journals Connector (OSTI)

Abstract The co-cracking experiment of waste plastics and heavy oil was done in the condition of 400 °C and pressure not higher than 2.0 MPa. The experimental results showed that the yield of heavy oil and coke decreased but the light oil and gas yield increased with the increasing amount of waste plastics. The products of heavy oil's solidifying point, flash point, viscosity and density decreased and had a good pour point depression effect. Heavy oil containing heat conduction oil and solvent contributed to heat transfer, melting and transport and had the effect of dissolution and co-cracking. It would have a good prospect when the co-cracking of waste plastics and heavy oil was applied to the combination processes of visbreaking and delayed coking and catalytic cracking and delayed coking.

Shikui Wu; Kaixiong Xu; Lusen Jiang; Li Wang

2014-01-01T23:59:59.000Z

295

Effects of thermal aging on Stress Corrosion Cracking and mechanical properties of stainless steel weld metals  

E-Print Network (OSTI)

Stress Corrosion Cracking (SCC) in and around primary loop piping welds in Boiling Water Reactors has been observed worldwide as plants continue to operate at temperatures and pressures near 2880C (5500F) and 6.9 MPa (1000 ...

Hixon, Jeff

2006-01-01T23:59:59.000Z

296

Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures  

E-Print Network (OSTI)

The addition of hydrated lime to asphalt has shown to be beneficial with an improvement in the Theological properties of the binder, as well as resistance to permanent deformation (rutting) and fatigue cracking of asphalt concrete mixtures...

Izzo, Richard P

1997-01-01T23:59:59.000Z

297

Cracked lifting lug welds on ten-ton UF{sub 6} cylinders  

SciTech Connect

Ten-ton, Type 48X, UF{sub 6} cylinders are used at the Portsmouth Gaseous Diffusion Plant to withdraw enriched uranium hexafluoride from the cascade, transfer enriched uranium hexafluoride to customer cylinders, and feed enriched product to the cascade. To accomplish these activities, the cylinders are lifted by cranes and straddle carriers which engage the cylinder lifting lugs. In August of 1988, weld cracks on two lifting lugs were discovered during preparation to lift a cylinder. The cylinder was rejected and tagged out, and an investigating committee formed to determine the cause of cracking and recommend remedial actions. Further investigation revealed the problem may be general to this class of cylinder in this use cycle. This paper discusses the actions taken at the Portsmouth site to deal with the cracked lifting lug weld problem. The actions include inspection activities, interim corrective actions, metallurgical evaluation of cracked welds, weld repairs, and current monitoring/inspection program.

Dorning, R.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

1991-12-31T23:59:59.000Z

298

Reaction kinetics of olefin saturation in the hydrodesulfurization of fluid catalytic cracked naphtha  

E-Print Network (OSTI)

U.S. governmental agencies are calling for strict environmental regulations on the quality of gasoline. Fluid catalytic cracked naphtha is an important blending component of the gasoline pool. The majority of the sulfur in the gasoline pool comes...

Schumann, Brian Herbert

2012-06-07T23:59:59.000Z

299

High-Temperature Stress Relaxation Cracking and Stress Rupture Observed in a Coke Gasifier Failure  

Science Journals Connector (OSTI)

This article discusses the high-temperature metal degradation mechanisms that occurred in the failure of a nine-story tall coke gasifier, located in a refinery power plant. Cracking of gasifier internals, bulging...

Daniel J. Benac; Douglas B. Olson…

2011-06-01T23:59:59.000Z

300

A preliminary investigation of the effects of environmentally assisted cracking on natural gas transmission pipelines  

E-Print Network (OSTI)

Concepts for the development of a model to predict natural gas transmission pipeline lifetime in a corrosive environment are constructed. Primarily, the effects of environmentally assisted cracking (EAC) are explored. Tensile test specimens from a...

Curbo, Jason Wayne

2005-08-29T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

On the fracture toughness of ferroelectric ceramics with electric field applied parallel to the crack front  

E-Print Network (OSTI)

On the fracture toughness of ferroelectric ceramics with electric field applied parallel crack growth. The effects of electric field on the fracture toughness of both initially unpoled and poled materials are investigated. Results for the predicted fracture toughness, remanent strain

302

Spatial and Temporal Distribution of Desiccation Cracks in Shrink-Swell Soils  

E-Print Network (OSTI)

Soil crack volume estimates, which are important for hydrology models on shrink-swell soils, are currently based on field measurements of vertical shrinkage and an assumption of isotropic shrinkage; however, few studies have validated the resulting...

Neely, Haly Lury

2014-04-17T23:59:59.000Z

303

Improvement of resistance to hydrogen induced cracking in electric resistance welded pipes fabricated with slit coils  

Science Journals Connector (OSTI)

The optimization of electric resistance welding (ERW) conditions was studied to improve the resistance to hydrogen induced cracking (HIC) at ... Furthermore, for a satisfactory level of HIC resistance, the fracti...

Hyun Uk Hong; Jong Bong Lee; Ho Jin Choi

2009-02-01T23:59:59.000Z

304

P wave anisotropy, stress, and crack distribution at Coso geothermal field,  

Open Energy Info (EERE)

wave anisotropy, stress, and crack distribution at Coso geothermal field, wave anisotropy, stress, and crack distribution at Coso geothermal field, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: P wave anisotropy, stress, and crack distribution at Coso geothermal field, California Details Activities (1) Areas (1) Regions (0) Abstract: A new inversion method for P wave anisotropy (Wu and Lees, 1999a) has been applied to high-precision, microseismic traveltime data collected at Coso geothermal region, California. Direction-dependent P wave velocity and thus its perturbation, are represented by a symmetric positive definite matrix A instead of a scalar. The resulting anisotropy distribution is used to estimate variations in crack density, stress distribution and permeability within the producing geothermal field. A circular dome-like

305

Laboratory Evaluation of Hot-Mix Asphalt Concrete Fatigue Cracking Resistance  

E-Print Network (OSTI)

LABORATORY EVALUATION OF HOT-MIX ASPHALT CONCRETE FATIGUE CRACKING RESISTANCE A Thesis by BRANDON PARKER JAMISON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 2010 Major Subject: Civil Engineering LABORATORY EVALUATION OF HOT-MIX ASPHALT CONCRETE FATIGUE CRACKING RESISTANCE A Thesis by BRANDON PARKER JAMISON Submitted to the Office of Graduate...

Jamison, Brandon Parker

2012-02-14T23:59:59.000Z

306

Electrochemical aspects of stress-corrosion cracking in. cap alpha. -brass  

SciTech Connect

This paper considers a number of aspects of the stress-corrosion cracking of brass from the point of view of the localized electrochemical processes occurring at the tip of a propagating crack. The principal system examined is the intergranular SCC of 70-30 brass in near-neutral ammoniacal solutions, for which a detailed mechanism is developed. In addition, the effects of nitrite ions in promoting SCC of both brass and copper are considered.

Burstein, G T; Newman, R C

1981-01-01T23:59:59.000Z

307

Modeling the ASR Induced Strains and Cracking of Reinforced Concrete Beams  

E-Print Network (OSTI)

). ...................................................................................................... 14 Figure 1-4: Crack pattern observed in C-Beam specimen subjected to cracking due to ASR/DEF effects (Mander et al. 2012). .............................................. 16 Figure 1-5: Reinforcing steel strain from strain gauges by Mander et al... steel strains show substantial evidence of dilation due to ASR effects. This is also verified using post-test petrographic analysis. Results show that much of the ASR-induced damage is concentrated in the concrete cover, while the reinforcing cage...

Zhang, Li

2013-05-17T23:59:59.000Z

308

The interaction of two closely spaced cracks - rock models and computer simulations  

E-Print Network (OSTI)

THE INTERACTION OF TWO CLOSELY SPACED CRACKS ROCK MODELS AND COMPUTER SIMULATIONS A Thesis by PENG LIN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1990 Major Subject: Geophysics THE INTERACTION OF TWO CLOSELY SPACED CRACKS ROCK MODELS AND COMPUTER SIMULATIONS A Thesis by PENG LIN Approved as to style and content by: o . ogan ( -Chair Committee) Andreas K. Kronenberg (Co...

Lin, Peng

2012-06-07T23:59:59.000Z

309

Mode I transverse cracking in an epoxy and a graphite fiber reinforced epoxy  

E-Print Network (OSTI)

, Johnson and Radon [6] and Glover, Mucci and Radon [7] used Charpy impact specimens to produce fast, unstable crack growth in unreinforced polymers. Devitt, Schapery and Bradley [8], and Hulsey [9] used split laminates in the form of double cantilever..., Johnson and Radon [6] and Glover, Mucci and Radon [7] used Charpy impact specimens to produce fast, unstable crack growth in unreinforced polymers. Devitt, Schapery and Bradley [8], and Hulsey [9] used split laminates in the form of double cantilever...

Williams, David Robert

2012-06-07T23:59:59.000Z

310

Corrosion-assisted cracking of duplex stainless steels in suction roll applications  

SciTech Connect

Corrosion-assisted cracking of suction rolls is a worldwide pulp and paper industry concern despite the great strides in identifying more resistant materials. The authors have examined various tests to assess their use in predicting the susceptibility of suction roll alloys with known service performance. Under conditions of high mean stress and low pH, near-threshold fatigue crack growth testing discriminates among the several materials in approximately the same ranking as their service performance characteristics would have predicted.

Yeske, R.M.; Revall, M.A.; Thompson, C.M. (Inst. of Paper Science and Technology, Atlanta, GA (United States))

1994-08-01T23:59:59.000Z

311

Methodology for extracting local constants from petroleum cracking flows  

DOE Patents (OSTI)

A methodology provides for the extraction of local chemical kinetic model constants for use in a reacting flow computational fluid dynamics (CFD) computer code with chemical kinetic computations to optimize the operating conditions or design of the system, including retrofit design improvements to existing systems. The coupled CFD and kinetic computer code are used in combination with data obtained from a matrix of experimental tests to extract the kinetic constants. Local fluid dynamic effects are implicitly included in the extracted local kinetic constants for each particular application system to which the methodology is applied. The extracted local kinetic model constants work well over a fairly broad range of operating conditions for specific and complex reaction sets in specific and complex reactor systems. While disclosed in terms of use in a Fluid Catalytic Cracking (FCC) riser, the inventive methodology has application in virtually any reaction set to extract constants for any particular application and reaction set formulation. The methodology includes the step of: (1) selecting the test data sets for various conditions; (2) establishing the general trend of the parametric effect on the measured product yields; (3) calculating product yields for the selected test conditions using coupled computational fluid dynamics and chemical kinetics; (4) adjusting the local kinetic constants to match calculated product yields with experimental data; and (5) validating the determined set of local kinetic constants by comparing the calculated results with experimental data from additional test runs at different operating conditions.

Chang, Shen-Lin (Woodridge, IL); Lottes, Steven A. (Naperville, IL); Zhou, Chenn Q. (Munster, IN)

2000-01-01T23:59:59.000Z

312

Weibull Effective Area for Hertzian Ring Crack Initiation Stress  

SciTech Connect

Spherical or Hertzian indentation is used to characterize and guide the development of engineered ceramics under consideration for diverse applications involving contact, wear, rolling fatigue, and impact. Ring crack initiation can be one important damage mechanism of Hertzian indentation. It is caused by sufficiently-high, surface-located, radial tensile stresses in an annular ring located adjacent to and outside of the Hertzian contact circle. While the maximum radial tensile stress is known to be dependent on the elastic properties of the sphere and target, the diameter of the sphere, the applied compressive force, and the coefficient of friction, the Weibull effective area too will be affected by those parameters. However, the estimations of a maximum radial tensile stress and Weibull effective area are difficult to obtain because the coefficient of friction during Hertzian indentation is complex, likely intractable, and not known a priori. Circumventing this, the Weibull effective area expressions are derived here for the two extremes that bracket all coefficients of friction; namely, (1) the classical, frictionless, Hertzian case where only complete slip occurs, and (2) the case where no slip occurs or where the coefficient of friction is infinite.

Jadaan, Osama M. [University of Wisconsin, Platteville; Wereszczak, Andrew A [ORNL; Johanns, Kurt E [ORNL

2011-01-01T23:59:59.000Z

313

Automated inspection of surface breaking cracks using GMR sensor arrays  

SciTech Connect

We present a prototype for automated magnetic stray field testing of ferromagnetic roller bearings. For this purpose NDE-adapted GMR sensor arrays (giant magneto resistance) are used for the detection of surface breaking cracks. The sensors are miniaturized down to the lower ?m-regime to achieve adequate spatial resolution. In doing so, sensor arrays with up to 48 elements are used to inspect the bearing surface within a few seconds only. In contrast to magnetic particle inspection (MPI), where the global magnetization requires a further inspection step and succeeding demagnetization, the presented prototype only locally magnetize the surface area in the vicinity of the GMR Sensors. For the local magnetization, the applied sub-surface magnetic field was simulated and proofed for detecting flaws with a depth of a few 10 ?m. By multiplexing the sensor array with an adapted read out electronics we quasi simultaneously detect the normal field component of about 100?m above the surface. The detection of artificial notches with a depth of 40 ?m and more could be resolved with a SNR better than 20 dB. The presented testing facility is fast and provides a step towards automated testing of safety relevant steel components.

Pelkner, Matthias; Reimund, Verena; Erthner, Thomas; Panke, Nicolai; Kreutzbruck, Marc [BAM Federal Institute for Material Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

2014-02-18T23:59:59.000Z

314

Effects of hydrogen on electropotential monitoring of stress corrosion crack growth  

SciTech Connect

Electropotential monitoring (EPM) has a crack growth measurement resolution that is an order of magnitude greater than methods that rely on crack mouth opening displacement. However, two phenomena have been identified that compromise the accuracy of the EPM technique. Coolant hydrogen concentrations above those needed to chemically reduce nickel oxide to metallic nickel cause EPM to underestimate the true crack length. The metallic nickel provides an electrical conduction path at contact points across the irregular crack surface thereby lowering the EPM potential. The coolant hydrogen concentration at which this reduction occurs is temperature dependent and correlates with an abrupt decrease in the rate of SCC crack growth. It was also found that EPM can indicate large crack growth when none actually exists. At temperatures > 315 C (600 F) the electrical resistivity of mill annealed Alloy 600 increased by as much as 5% in a period of weeks or months. Each 1% increase in resistivity results in a bias in the EPM indicated cracklength of about 0.2 mm (0.008 inches). Smaller changes in the electrical resistivity of other alloys have been measured which rank as EN52> X-750> 304SS> nickel. It has been shown that these resistivity changes occur during exposure to high temperature water or inert gas. Strategies to minimize the effects of these two phenomena on EPM measurement are discussed.

Thompson, C.D.; Carey, D.M.; Perazzo, N.L.

1997-08-01T23:59:59.000Z

315

Fracture behavior of surface cracked wide plates of high strength steel containing overmatched repair welds  

SciTech Connect

This paper presents the experimental results of tests conducted using surface cracked wide plates containing overmatched repair weld joints. The deformation and fracture characteristics of the repair welded wideplates notched at the original weld deposit, repair weld and HAZ regions are discussed. The aim of this work was to investigate the effects of strength mis-match and notch position on the fracture performance of such complex weldments. Furthermore, the predictions of crack driving force using the Engineering Treatment Model for mis-matched welds (ETM-MM) procedure was compared with the results of the wide plates containing semielliptical surface cracks. For this study, 1/2K weld joints were prepared on 30 nm thick pipeline steel X65 plates by using a SAW process, resulting in 50% overmatching. Repair was performed at the cap side of the original joint up to half depth of plate thickness with a GMA welding process under hyperbaric conditions, leading to 41% yield strength overmatching. In order to assess the fracture behavior of these welds, surface cracked (semielliptic defects) wide plates containing original and repair welds were tested in tension at {minus}10 C. The surface cracked wide plate tests results have confirmed that overmatched repair weld metal can exert a significant effect on the deformation and fracture behavior of the wide plates. Wide plates containing root cracks clearly showed a shielding effect of the overmatched repair weld since it prevented development of through thickness ligament yielding.

Junghans, E.; Kocak, M.; Schwalbe, K.H. [GKSS Research Center, Geesthacht (Germany). Inst. of Materials Research

1996-12-01T23:59:59.000Z

316

Hydrogen-induced cracking along the fusion boundary of dissimilar metal welds  

SciTech Connect

Presented here are the results from a series of experiments in which dissimilar metals welds were made using the gas tungsten arc welding process with pure argon or argon-6% hydrogen shielding gas. The objective was to determine if cracking near the fusion boundary of dissimilar metal welds could be caused by hydrogen absorbed during welding and to characterize the microstructures in which cracking occurred. Welds consisted of ER308 and ER309LSi austenitic stainless steel and ERNiCr-3-nickel-based filler metals deposited on A36 steel base metal. Cracking was observed in welds made with all three filler metals. A ferrofluid color metallography technique revealed that cracking was confined to regions in the weld metal containing martensite. Microhardness indentations indicated that martensitic regions in which cracking occurred had hardness values from 400 to 550 HV. Cracks did not extend into bulk weld metal with hardness less than 350 HV. Martensite formed near the fusion boundary in all three filler metals due to regions of locally increased base metal dilution.

Rowe, M.D.; Nelson, T.W.; Lippold, J.C. [Ohio State Univ., Columbus, OH (United States)

1999-02-01T23:59:59.000Z

317

Evidences for secondary cracking of oil in South Pars field, Persian Gulf, Iran  

Science Journals Connector (OSTI)

Condensates and natural gases in South Pars, world's largest gas field in Persian Gulf were studied for their geochemical characteristics and possibility of secondary cracking as a major gas producing mechanism. Carbon isotopic analysis of gas components proposes thermogenic origin for South Pars gas field. However, ?13C values of Methane and Ethane are slightly depleted in comparison with generated gas from primary thermogenic gas whereas gases from secondary cracking of oils are systematically depleted in 13C in Methane and Ethane compared to gases from primary cracking. Gas composition of Head-Space gas samples were plotted in Ln(C1/C2) vs. Ln(C2/C3) diagram that all the data points indicate a noticeable shift toward trend of secondary cracking, indicating frequency of higher components i.e. C2+. Silurian black shales are recognized as most important source rock for the South Pars field. Biomarker analysis of hydrocarbon liquid samples indicates Pristane to Phytane ratio is > 1 that could confirm mentioned shaly source rock which is deposited in suboxic to oxic marine environment. Considering of ?13C of Silurian shales the “?13C Methane-?13C Source” was calculated and plotted against C1/?C1–5 indicating effect of secondary cracking of oil as producing mechanism for South Pars gas field. Moreover, pyro-bitumen as product of the secondary cracking was found filling secondary porosities in bottom part of the reservoir.

Jafar Aali; Omeid Rahmani

2011-01-01T23:59:59.000Z

318

Overview of the DOE studies of recovery boiler floor tube cracking  

SciTech Connect

Cracking of the stainless steel layer of coextruded 304L/SA210 recovery boiler floor tubes has been observed in an increasing number of black liquor recovery boilers. Because failure of such tubes is a serious safety concern as well as an economic issue, this project was initiated with the objective of identifying alternate materials or process changes that would prevent tube cracking. Tensile stresses are essential for the most likely failure mechanisms, i.e., fatigue or stress corrosion cracking, therefore stresses were measured at room temperature and modeling was used to predict stresses under operating conditions. Laboratory studies have identified conditions under which composite tubes crack due to thermal fatigue and stress corrosion. Floor tube temperature measurements have defined the magnitude and frequency of temperature fluctuations experienced by such tubes, and smelt corrosion studies have measured the degradation rate when molten smelt comes in contact with tubes. Based on these observations, certain materials appear more likely to resist cracking and certain process changes should help avoid conditions that cause composite tube cracking.

Keiser, J.R.; Taljat, B.; Wang, X.L. [and others

1998-03-01T23:59:59.000Z

319

Production of low axial energy spread ion beams with multicusp sources  

SciTech Connect

Multicusp ion sources are capable of producing ions with low axial energy spread which are necessary in applications such as: ion projection lithography (IPL) and focused ion beams for the next generation lithographic tools and nuclear science experiments such as radioactive ion beam production. The axial ion energy spread for multicusp source is approximately 6 eV which is too large for IPL and radioactive ion beam applications. The addition of a magnetic filter which consists of a pair of permanent magnets to the multicusp source reduces the energy spread considerably. The reduction is due to the improvement in the uniformity of the axial plasma potential distribution in the discharge region. Axial ion energy spread of the filament driven ion source has been measured using three different techniques. In all cases, it was found to be less than 2 eV. Energy spread of the radio frequency (RF) driven source has also been explored, and it was found to be less than 3 eV with the proper RF-shielding. A new multicusp source configuration has been designed and constructed to further reduce the energy spread. To achieve a more uniform axial plasma potential distribution, a cylindrical magnetic filter has been designed and constructed for a 2-cm-diameter source. This new source configuration, the co-axial source, is new in its kind. The energy spread in this source has been measured to be a record low of 0.6 eV. Because of the novelty of this device, some plasma parameters inside the source have been studied. Langmuir probe has been used to measure the plasma potential, the electron temperature and the density distribution.

Lee, Y.H.Y. [Univ. of California, Berkeley, CA (United States)

1998-05-01T23:59:59.000Z

320

The effect of aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels  

SciTech Connect

The effect of elevated temperature aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels is discussed in terms of the several parameters which influence such behavior. These parameters include water chemistry, impurities within the steels themselves, as well as factors such as the water flow rate, loading waveform and loading rates. Some of these parameters have similar effects upon both crack initiation and propagation, while others exhibit different effects in the two stages of cracking. In the case of environmentally-assisted crack (EAC) growth, the most important impurities within the steel are metallurgical sulfide inclusions which dissolve upon contact with the water. A ``critical`` concentration of sulfide ions at the crack tip can then induce environmentally-assisted cracking which proceeds at significantly increased crack growth rates over those observed in air. The occurrence, or non-occurrence, of EAC is governed by the mass-transport of sulfide ions to and from the crack-tip region, and the mass-transport is discussed in terms of diffusion, ion migration, and convection induced within the crack enclave. Examples are given of convective mass-transport within the crack enclave resulting from external free stream flow. The initiation of fatigue cracks in elevated temperature aqueous environments, as measured by the S-N fatigue lifetimes, is also strongly influenced by the parameters identified above. The influence of sulfide inclusions does not appear to be as strong on the crack initiation process as it is on crack propagation. The oxygen content of the environment appears to be the dominant factor, although loading frequency (strain rate) and temperature are also important factors.

James, L.A. [Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.; Van Der Sluys, W.A. [Babcock and Wilcox Co., Alliance, OH (United States)

1996-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Measurements of spatial and frequency coherence of an equatorial hf path during spread-F  

SciTech Connect

In August 1990, the authors set up an hf path on the equatorial path between Maloelap Atoll and Bikini Atoll. This path, which had a range of 702 km, reflected in the ionosphere approximately 100 km north of the Altair radar location on Kwajalein. Transmitters at Maloelap broadcasted four cw tones within bandwidth of either 4 kHz, 9 kHz, or 70 kHz to be used to determine frequency coherence and also a phase-coded pseudo random sequence with a bandwidth of 60 kHz (channel probe) to be used to determine time delay spread. A spatial array of antennas was deployed at Bikini to measure spatial and frequency coherence using the cw broadcasts. The system was run in the post-sunset time period over two weeks during which almost every night showed significant degradation due to spread F resulting in rapid fading, decreased spatial and frequency coherence, and increased time delay spread. Doppler spreads of greater than 20 Hz were not uncommon, and the spatial correlation distances and frequency coherence bandwidths became so small (50 meters and 1 kHz respectively) that the experiment had to be readjusted. Measurements taken by the Altair incoherent scatter radar and the CUPRI 50 MHz coherent scatter radar indicate that although the bistatic hf channel is affected by the large scale plume structures, most of the [open quotes]damage[close quotes] is done by the bottomside spread F.

Fitzgerald, T.J.; Argo, P.E.; Carlos, R.C.

1993-01-01T23:59:59.000Z

322

Measurements of spatial and frequency coherence of an equatorial hf path during spread-F  

SciTech Connect

In August 1990, the authors set up an hf path on the equatorial path between Maloelap Atoll and Bikini Atoll. This path, which had a range of 702 km, reflected in the ionosphere approximately 100 km north of the Altair radar location on Kwajalein. Transmitters at Maloelap broadcasted four cw tones within bandwidth of either 4 kHz, 9 kHz, or 70 kHz to be used to determine frequency coherence and also a phase-coded pseudo random sequence with a bandwidth of 60 kHz (channel probe) to be used to determine time delay spread. A spatial array of antennas was deployed at Bikini to measure spatial and frequency coherence using the cw broadcasts. The system was run in the post-sunset time period over two weeks during which almost every night showed significant degradation due to spread F resulting in rapid fading, decreased spatial and frequency coherence, and increased time delay spread. Doppler spreads of greater than 20 Hz were not uncommon, and the spatial correlation distances and frequency coherence bandwidths became so small (50 meters and 1 kHz respectively) that the experiment had to be readjusted. Measurements taken by the Altair incoherent scatter radar and the CUPRI 50 MHz coherent scatter radar indicate that although the bistatic hf channel is affected by the large scale plume structures, most of the {open_quotes}damage{close_quotes} is done by the bottomside spread F.

Fitzgerald, T.J.; Argo, P.E.; Carlos, R.C.

1993-07-01T23:59:59.000Z

323

Acoustic Emission and Guided Ultrasonic Waves for Detection and Continuous Monitoring of Cracks in Light Water Reactor Components  

SciTech Connect

Acoustic emission (AE) and guided ultrasonic waves (GUW) are considered for continuous monitoring and detection of cracks in Light Water Reactor (LWR) components. In this effort, both techniques are applied to the detection and monitoring of fatigue crack growth in a full scale pipe component. AE results indicated crack initiation and rapid growth in the pipe, and significant GUW responses were observed in response to the growth of the fatigue crack. After initiation, the crack growth was detectable with AE for approximately 20,000 cycles. Signals associated with initiation and rapid growth where distinguished based on total rate of activity and differences observed in the centroid frequency of hits. An intermediate stage between initiation and rapid growth was associated with significant energy emissions, though few hits. GUW exhibit a nearly monotonic trend with crack length with an exception of measurements obtained at 41 mm and 46 mm.

Meyer, Ryan M.; Coble, Jamie B.; Ramuhalli, Pradeep; Watson, Bruce E.; Cumblidge, Stephen E.; Doctor, Steven R.; Bond, Leonard J.

2012-06-28T23:59:59.000Z

324

Spread the word about how to help | ENERGY STAR Buildings & Plants  

NLE Websites -- All DOE Office Websites (Extended Search)

Spread the word about how to help Spread the word about how to help Secondary menu About us Press room Contact Us Portfolio Manager Login Facility owners and managers Existing buildings Commercial new construction Industrial energy management Small business Service providers Service and product providers Verify applications for ENERGY STAR certification Design commercial buildings Energy efficiency program administrators Commercial and industrial program sponsors Associations State and local governments Federal agencies Tools and resources Training In this section Learn the benefits Get started Use Portfolio Manager Save energy Stamp out energy waste Find cost-effective investments Engage occupants Provide a seat at the table Share energy goals and progress Identify energy-saving actions Spread the word about how to help

325

Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals  

DOE Patents (OSTI)

A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

2014-05-20T23:59:59.000Z

326

Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals  

DOE Patents (OSTI)

A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

2014-10-14T23:59:59.000Z

327

No Evidence for Significant Age Spreads in Young Massive LMC Clusters  

E-Print Network (OSTI)

Recent discoveries have put the picture of stellar clusters being simple stellar populations into question. In particular, the color-magnitude diagrams of intermediate age (1-2 Gyr) massive clusters in the Large Magellanic Cloud (LMC) show features that could be interpreted as age spreads of 100-500 Myr. If multiple generations of stars are present in these clusters then, as a consequence, young (test this hypothesis. We analyzed the color-magnitude diagrams of these clusters and fitted their star formation history to derive upper limits of potential age spreads. We find that none of the clusters analyzed in this work shows evidence for an extended star formation history that would be consistent with the age spreads proposed for intermediat...

Niederhofer, Florian; Bastian, Nate; Silva-Villa, Esteban

2015-01-01T23:59:59.000Z

328

Use of incomplete energy recovery for the energy compression of large energy spread charged particle beams  

DOE Patents (OSTI)

A method of energy recovery for RF-base linear charged particle accelerators that allows energy recovery without large relative momentum spread of the particle beam involving first accelerating a waveform particle beam having a crest and a centroid with an injection energy E.sub.o with the centroid of the particle beam at a phase offset f.sub.o from the crest of the accelerating waveform to an energy E.sub.full and then recovering the beam energy centroid a phase f.sub.o+Df relative to the crest of the waveform particle beam such that (E.sub.full-E.sub.o)(1+cos(f.sub.o+Df))>dE/2 wherein dE=the full energy spread, dE/2=the full energy half spread and Df=the wave form phase distance.

Douglas, David R. (Newport News, VA); Benson, Stephen V. (Yorktown, VA)

2007-01-23T23:59:59.000Z

329

Investigation of Pool Spreading and Vaporization Behavior in Medium-Scale LNG Tests  

Science Journals Connector (OSTI)

Abstract A failure of a Liquefied Natural Gas (LNG) tanker can occur due to collision or loading/unloading operation resulting in spillage of LNG on water. Upon release, a spreading liquid can form a pool with rapid vaporization leading to the formation of a flammable vapor cloud. Safety analysis for the protection of public and property involves the determination of consequences of such accidental releases. To address this complex pool spreading and vaporization phenomenon of LNG, an investigation is performed based on the experimental tests that were conducted by the Mary Kay O’Connor Process Safety Center (MKOPSC) in 2007. The 2007 tests are a part of medium-scale experiments carried out at the Brayton Fire Training Field (BFTF), College Station. The dataset represents a semi-continuous spill on water, where LNG is released on a confined area of water for a specified duration of time. The pool spreading and vaporization behavior are validated using empirical models, which involved determination of pool spreading parameters and vaporization rates with respect to time. Knowledge of the pool diameter, pool height and spreading rate are found to be important in calculating the vaporization rates of the liquid pool. The paper also presents a method to determine the vaporization mass flux of LNG using water temperature data that is recorded in the experiment. The vaporization rates are observed to be high initially and tend to decrease once the pool stopped spreading. The results of the analysis indicated that a vaporization mass flux that is varying with time is required for accurate determination of the vaporization rate. Based on the data analysis, sources of uncertainties in the experimental data were identified to arise from ice formation and vapor blocking.

Nirupama Gopalaswami; R. Mentzer; M. Sam Mannan

2014-01-01T23:59:59.000Z

330

Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical crack growth, and some implications  

E-Print Network (OSTI)

Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical at the earliest stages of fracture nucleation). Slow, subcritical crack growth in rock is associated

331

Numerical validation of a new criterion of fracture for elastic-plastic materials with a subcritical crack growth.  

E-Print Network (OSTI)

??The objective of this thesis is to study the dependence of the P method on the geometry of the specimen, crack length and applied load.… (more)

LAVORINI, LORENZO

2012-01-01T23:59:59.000Z

332

An Evaluation of Subcritical Crack Growth and Stress-Induced Transformation Toughening of 3Y-TZP.  

E-Print Network (OSTI)

?? The purpose of this study was to evaluate the subcritical crack growth parameters (SCG) through constant stress-rate testing and the critical time to transformation… (more)

Rigby, Brent Lee

2009-01-01T23:59:59.000Z

333

Strain energy density: Distance criterion for the initiation of hydrogen-induced cracking of Alloy X-750  

SciTech Connect

A criterion for initiation of subcritical crack growth at blunt notches and sharp defects was developed and applied to hydrogen- induced cracking of the Ni-base superalloy X-750. Onset of crack growth is shown to occur when a critical strain energy density is attained at a distance from the notch and crack tips characteristic of the microstructure along the prospective crack path. Rising load crack growth initiation data were obtained using homogeneous hydrogen precharged notched and fatigue precracked bend specimens. Notch root radius, grain size and hydrogen concentration were varied. Crack growth initiation loads were dependent on both notch root radius and bulk precharged hydrogen concentration. These data were shown to be correlated using a critical strain energy at-a-distance (SEDAD) criterion. Furthermore, an elastic-plastic analysis of the strain energy distributions showed that the critical strain energy density value is attained at one grain diameter from the notch and fatigue precrack tips. Mechanical and microstructural aspects of crack growth process and relevance to hydrogen-induced cracking are discussed.

Hall, M.M. Jr.; Symons, D.M.; Kearns, J.J.

1991-12-31T23:59:59.000Z

334

Strain energy density-distance criterion for the initiation of stress corrosion cracking of alloy X-750  

SciTech Connect

A strain energy density-distance criterion was previously developed and used to correlate rising-load K{sub c} initiation data for notched and fatigue precracked specimens of hydrogen precharged Alloy X-750. This criterion, which was developed for hydrogen embrittlement (HE) cracking, is used here to correlate static-load stress corrosion cracking (SCC) initiation times obtained for smooth geometry, notched and fatigue precracked specimens. The onset of SCC crack growth is hypothesized to occur when a critical strain, which is due to environment-enhanced creep, is attained within the specimen interior. For notched and precracked specimens, initiation is shown by analysis to occur at a variable distance from notch and crack tips. The initiation site varies from very near the crack tip, for highly loaded sharp cracks, to a site that is one grain diameter from the notch, for lower loaded, blunt notches. The existence of hydrogen gradients, which are due to strain-induced hydrogen trapping in the strain fields of notch and crack tips, is argued to be controlling the site for initiation of cracking. By considering the sources of the hydrogen, these observations are shown to be consistent with those from the previous HE study, in which the characteristic distance for crack initiation was found to be one grain diameter from the notch tip, independent of notch radius, applied stress intensity factor and hydrogen level.

Hall, M.M. Jr.; Symons, D.M.

1996-05-01T23:59:59.000Z

335

Hydrodesulfurization of Fluid Catalytic Cracking Decant Oils for the Production of Low-sulfur Needle Coke Feedstocks.  

E-Print Network (OSTI)

??Needle coke, produced by the delayed coking of fluid catalytic cracking decant oils, is the primary filler used in the production of graphite electrodes. The… (more)

Wincek, Ronald

2013-01-01T23:59:59.000Z

336

Getter sputtering system for high-throughput fabrication of composition spreads  

SciTech Connect

We describe a sputtering system that can deposit composition spreads in an effectively UHV environment but which does not require the high-throughput paradigm to be compromised by a long pump down each time a target is changed. The system deploys four magnetron sputter guns in a cryoshroud (getter sputtering) which allows elements such as Ti and Zr to be deposited with minimal contamination by oxygen or other reactive background gases. The system also relies on custom substrate heaters to give rapid heating and cool down. The effectiveness of the gettering technique is evaluated, and example results obtained for catalytic activity of a pseudoternary composition spread are presented.

Gregoire, John M.; Dover, R. B. van; Jin Jing; Di Salvo, Francis J.; Abruna, Hector D. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States) and Cornell Fuel Cell Institute, Cornell University, Ithaca, New York 14853 (United States); Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States) and Cornell Fuel Cell Institute, Cornell University, Ithaca, New York 14853 (United States); Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States) and Cornell Fuel Cell Institute, Cornell University, Ithaca, New York 14853 (United States)

2007-07-15T23:59:59.000Z

337

On formulating equations for plume spreads for near-surface releases  

Science Journals Connector (OSTI)

Recent concerns about effects of automobile emissions on the health of people living close to roads have motivated an examination of models to estimate dispersion in the surface boundary layer. This examination led to new formulations for horizontal and vertical plume spread described in Venkatram et al. (2013). Concentration estimates based on the proposed plume spread equations compare well with data from both the Prairie Grass experiment (Barad, 1958) as well as the recently conducted Idaho Falls experiment (Finn et al., 2010). This paper describes a simpler approach to deriving the new equations proposed in the earlier paper.

Akula Venkatram; Nico Schulte

2014-01-01T23:59:59.000Z

338

Belgian approach to steam generator tube plugging for primary water stress corrosion cracking  

SciTech Connect

For a number of years, three Belgian nuclear power plants have experienced primary water stress corrosion cracking (PWSCC) in the expansion transition area on a very large number of tubes. One of the plants has part depth rolled tubes and the others have full depth expansion. The report presents a review of the leakage experience associated with (PWSCC) in the Doel 2, Doel 3 and Tihange 2 Nuclear Power Plants and illustrates the type of cracking observed on pulled tubes from Doel 2 and Doel 3. The Belgian units operate with numerous through wall cracks without impairing the safety and the reliability of the plants. This is achieved by a safety approach based on the extensive use of advanced non-destructive examination (NDE) techniques and the development of new plugging limits. These limits are derived from a realistic interpretation of NRC Regulatory Guide 1.121 and are backed up by a substantial experimental program. The report summarizes the establishment of plugging limits for both axial and circumferential cracks in the roll transition area of full depth rolled tubes. The LABORELEC eddy current rotating probe (RPC) technology and associated crack sizing methodology are also described. 8 refs., 2 figs., 1 tab.

Frederick, G. (TRACTEBEL, Brussels (Belgium)); Hernalsteen, P.; Dobbeni, D. (Laboratoire Belge de l'Industrie Electrique (LABORELEC), Linkebeek (Belgium))

1990-03-01T23:59:59.000Z

339

Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz  

SciTech Connect

The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

Yuan Zhang; Jin-hu Wu; Dong-ke Zhang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

2008-03-15T23:59:59.000Z

340

Surfactant-assisted spreading of an oil-in-water emulsion on the surface of a liquid bath  

E-Print Network (OSTI)

This fluid dynamics video shows how an oil-in-water emulsion stabilized by an ionic surfactant spreads on the free surface of a layer of pure water. The spreading shows two intriguing features: a transparent area surrounding the source of oil droplets, and a fast retraction of the layer of oil droplets on itself once the source has emptied. We show that the dynamics of spreading are strongly connected to the interfacial/bulk properties of the surfactant.

Roche, Matthieu; Griffiths, Ian; Saint-Jalmes, Arnaud; Stone, Howard A

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


341

Study on grain boundary character and strain distribution of intergranular cracking in the CGHAZ of T23 steel  

SciTech Connect

Intergranular reheat cracking in the coarse-grained heat-affected zone of T23 steel was produced by strain to fracture tests on a Gleeble 3500 thermal–mechanical simulator. Then the grain boundary character, as well as the strain distribution after reheat crack propagation, was studied by electron backscatter diffraction technique. The results showed that incoherent ?3 boundaries were seldom found on the prior austenite grain boundaries. Therefore, only the type of random high-angle boundaries played a crucial role in the intergranular cracking. Microstructurally cavities and small cracks were preferentially initiated from high-angle grain boundaries. Low-angle grain boundaries and high-angle ones with misorientation angles less than 15° were more resistant to the cracking. More importantly, the fraction of high-angle grain boundaries increased with the plastic strain induced by both temperature gradient and stress in the coarse-grained heat-affected zone, which contributed to the crack initiation and propagation. Furthermore, the strain distributions in the vicinity of cavities and cracks revealed the accommodation processes of plastic deformation during stress relaxation. It also reflected the strength differences between grain interior and grain boundary at different heat-treated temperatures, which had a large influence on the cracking mechanism. - Highlights: • The coincidence site lattice boundaries play little role in the reheat cracking. • Cavity and crack occur at high-angle grain boundaries rather than low-angle ones. • The strain leads low-angle grain boundaries to transform to high-angle ones. • Strain distribution differs for cavity and crack zones at different temperatures.

Jin, Y.J.; Lu, H., E-mail: shweld@sjtu.edu.cn; Yu, C.; Xu, J.J.

2013-10-15T23:59:59.000Z

342

Physics-Based Stress Corrosion Cracking Component Reliability Model cast in  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Physics-Based Stress Corrosion Cracking Component Reliability Model Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework The Risk-Informed Safety Margin Characterization (RISMC) pathway is a set of activities defined under the U.S. Department of Energy Light Water Reactor Sustainability Program. The overarching objective of RISMC is to support plant life-extension decision-making by providing a state-of-knowledge characterization of safety margins in key systems, structures, and components (SSCs). The methodology emerging from the RISMC pathway is not a conventional probabilistic risk assessment (PRA)-based one; rather, it relies on a reactor systems simulation framework in which

343

Physics-Based Stress Corrosion Cracking Component Reliability Model cast in  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Physics-Based Stress Corrosion Cracking Component Reliability Model Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework The Risk-Informed Safety Margin Characterization (RISMC) pathway is a set of activities defined under the U.S. Department of Energy Light Water Reactor Sustainability Program. The overarching objective of RISMC is to support plant life-extension decision-making by providing a state-of-knowledge characterization of safety margins in key systems, structures, and components (SSCs). The methodology emerging from the RISMC pathway is not a conventional probabilistic risk assessment (PRA)-based one; rather, it relies on a reactor systems simulation framework in which

344

Cracking Molecular Structures with Bright Lights - and a Few Good Eggs |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Cracking Molecular Structures with Bright Lights - and a Few Good Cracking Molecular Structures with Bright Lights - and a Few Good Eggs Cracking Molecular Structures with Bright Lights - and a Few Good Eggs June 22, 2012 - 11:04am Addthis This rendering shows a lysozyme structural model against its X-ray diffraction pattern from SLAC’s Linac Coherent Light Source (LCLS), a powerful X-ray laser facility. Researchers have achieved high-resolution images of these simple biomolecules using advanced crystallography at LCLS. | Photo by Anton Barty/DESY This rendering shows a lysozyme structural model against its X-ray diffraction pattern from SLAC's Linac Coherent Light Source (LCLS), a powerful X-ray laser facility. Researchers have achieved high-resolution images of these simple biomolecules using advanced crystallography at LCLS.

345

Supercomputers Crack Sixty-Trillionth Binary Digit of Pi-Squared |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Supercomputers Crack Sixty-Trillionth Binary Digit of Pi-Squared Supercomputers Crack Sixty-Trillionth Binary Digit of Pi-Squared Supercomputers Crack Sixty-Trillionth Binary Digit of Pi-Squared April 28, 2011 - 11:28am Addthis David H. Bailey | Photo Courtesy of Lawrence Berkely National Lab David H. Bailey | Photo Courtesy of Lawrence Berkely National Lab Linda Vu What are the key facts? Australian researchers have found the sixty-trillionth binary digit of Pi-squared. The calculation would have taken a single computer processor unit (CPU) 1,500 years to calculate, but it took just a few months on IBM's "BlueGene/P" supercomputer, which is designed to run continuously at one quadrillion calculations per second. Pi is one of the most mysterious numbers in mathematics and can never be expressed as a finite decimal number -- humanity will never have

346

Method for cracking hydrocarbon compositions using a submerged reactive plasma system  

DOE Patents (OSTI)

A method is described for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap there between. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition. 6 figs.

Kong, P.C.

1997-05-06T23:59:59.000Z

347

Method and apparatus for detecting external cracks from within a metal tube  

DOE Patents (OSTI)

A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.

Caffey, Thurlow W. H. (Albuquerque, NM)

2001-08-07T23:59:59.000Z

348

Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks  

SciTech Connect

Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

Dugan, Sandra; Wagner, Sabine [Materials Testing Institute University of Stuttgart (MPA), Pfaffenwaldring 32, 70569 Stuttgart (Germany)

2014-02-18T23:59:59.000Z

349

Task 3.9 -- Catalytic tar cracking. Semi-annual report, January 1--June 30, 1995  

SciTech Connect

Tar produced in the gasification of coal is deleterious to the operation of downstream equipment including fuel cells, gas turbines, hot-gas stream cleanup filters, and pressure swing adsorption systems. Catalytic cracking of tars to smaller hydrocarbons can be an effective means to remove these tars from gas streams and, in the process, generate useful products, e.g., methane gas, which is crucial to the operation of molten carbonate fuel cells. The objectives of this project are to investigate whether gasification tars can be cracked by synthetic nickel-substituted micamontmorillonite, zeolite, or dolomite material; and whether the tars can be cracked selectively by these catalysts to produce a desired liquid and/or gas stream. Results to date are presented in the cited papers.

Young, B.C.; Timpe, R.C.

1995-12-31T23:59:59.000Z

350

ISO test method to determine sustained-load-cracking resistance of aluminium cylinders  

SciTech Connect

Leak as well as rupture types of failures related to sustained-load-cracking (SLC) have been observed in high-pressure gas cylinders fabricated from certain aluminium alloy. The stable crack growth mechanism observed primarily in the cylinder neck and shoulder area have been identified as the SLC mechanism occurring at room temperature without any environmental effect. The International Organization for standardization (ISO) Sub-Committee 3, Working Group 16 has developed a test method to measure the SLC resistance using fracture mechanics specimens along with an acceptance criterion for aluminium cylinders. The technical rationale for the proposed test method and the physical significance of the acceptance criterion to the cylinder performance in terms of critical stress-crack size relationship is presented. Application of the developed test method for characterizing new aluminium alloy for manufacturing cylinders is demonstrated. SLC characteristics of several aluminium cylinders as well as on-board cylinders for natural gas vehicles assessed by the authors are discussed.

Bhuyan, G.S. [Powertech Labs. Inc., Surrey, British Columbia (Canada); Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States)

1999-08-01T23:59:59.000Z

351

Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site  

SciTech Connect

In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24 inch diameter and 0.25 inch wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.

ANANTATMULA, R.P.

1999-10-20T23:59:59.000Z

352

Modeling of interface cracking in copper–graphite composites by MD and CFE method  

Science Journals Connector (OSTI)

Abstract Molecular dynamics (MD) method was used to study mechanical properties of copper–graphite composite interface. Mode I fracture of the interface of copper–graphite composite was modeled by considering fixed and free boundary conditions, which means slipping constraint conditions for atomic layers in the composite. The stress near crack tip and the energy changes of the system are obtained. Then a cohesive traction–separation law of copper–graphite interface can also be obtained by using the MD simulation. For the purpose of comparisons, a modeling of interfacial fracture of the composite by using a zero-thickness cohesive finite element (CFE) was carried out. It is found that there is a stress concentration but no singularity for the normal stress at the crack tip in interface obtained by using the present MD simulation and CFE method. While in the interface away from the crack tip, the obtained stress is consistent with the solution of classical interfacial fracture mechanics.

Shi-Jun Guo; Qing-Sheng Yang; X.Q. He; K.M. Liew

2014-01-01T23:59:59.000Z

353

A Review of Stress Corrosion Cracking/Fatigue Modeling for Light Water  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

A Review of Stress Corrosion Cracking/Fatigue Modeling for Light A Review of Stress Corrosion Cracking/Fatigue Modeling for Light Water Reactor Cooling System Components A Review of Stress Corrosion Cracking/Fatigue Modeling for Light Water Reactor Cooling System Components In the United States currently there are approximately 104 operating light water reactors. Of these, 69 are pressurized water reactors (PWRs) and 35 are boiling water reactors (BWRs). In 2007, the 104 light-water reactors (LWRs) in the United States generated approximately 100 GWe, equivalent to 20% of total US electricity production. Most of the US reactors were built before 1970 and the initial design lives of most of the reactors are 40 years. It is expected that by 2030, even those reactors that have received 20-year life extension license from the US Nuclear Regulatory Commission

354

Method for cracking hydrocarbon compositions using a submerged reactive plasma system  

DOE Patents (OSTI)

A method for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap therebetween. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition.

Kong, Peter C. (Idaho Falls, ID)

1997-01-01T23:59:59.000Z

355

Neutron diffraction determination of the residual stress redistribution in cracked autofrettaged tubing  

SciTech Connect

Neutron diffraction has been used to measure the residual stress distributions in uncracked and fatigue cracked rings taken from a high strength, low alloy steel autofrettage tube with a bore diameter of 60mm and a wall thickness of 32mm. Stresses were determined to a precision of {plus minus} 10MPa. Three crack sixes were examines. No appreciable stress redistribution was observed until the crack was grown into a region which originally contained tensile residual hoop stress. When this occurred an increase in residual hoop tension was observed ahead of the crick tip. Qualitative agreement was achieved between the measured hoop stress distribution and values predicted using a boundary element method. 9 refs., 12 figs.

Bourke, M.A. (Los Alamos National Lab., NM (USA)); McGillivray, H.J.; Webster, G.A. (Imperial Coll. of Science, Technology and Medicine, London (UK). Dept. of Mechanical Engineering); Webster, P.J. (Salford Univ. (UK). Dept. of Civil Engineering)

1991-01-01T23:59:59.000Z

356

Proceedings of the Sudden Oak Death Fifth Science Symposium Reducing the Spread of Phytophthora ramorum  

E-Print Network (OSTI)

Proceedings of the Sudden Oak Death Fifth Science Symposium 141 Reducing the Spread of Phytophthora on the Rogue River-Siskiyou National Forest was found infected with Phytophthora ramorum. The trail University. Phytophthora ramorum was recovered from at least one of the 11 samples on all occasions except

Standiford, Richard B.

357

Dispersed Repetitive DNA Has Spread to New Genomes Since Polyploid Formation in Cotton  

E-Print Network (OSTI)

Dispersed Repetitive DNA Has Spread to New Genomes Since Polyploid Formation in Cotton Xin recently formed polyploid, cotton (Gossypium barbadense L.; AD genome), 83 non-cross-hybridizing DNA clones tetraploid cotton. In tetraploid cotton, FISH analysis showed that some A-genome dispersed repeats appear

Wendel, Jonathan F.

358

Code-Red: a case study on the spread and victims of an Internet worm  

E-Print Network (OSTI)

Code-Red: a case study on the spread and victims of an Internet worm David Moore, Colleen Shannon infected with the Code- Red (CRv2) worm in less than 14 hours. The cost of this epidemic, including subsequent strains of Code-Red, is es- timated to be in excess of $2.6 billion. Despite the global damage

Somayaji, Anil

359

The Effect of Rumor Spreading in Reputation Systems for Mobile Ad-hoc Networks  

E-Print Network (OSTI)

The Effect of Rumor Spreading in Reputation Systems for Mobile Ad-hoc Networks Sonja Buchegger IBM EPFL-DSC CH-1015 Lausanne, Switzerland jean-yves.leboudec@epfl.ch Abstract: Mobile ad-hoc networks rely- liciously pose a threat to availability in mobile ad- hoc networks. Several approaches have been pro- posed

Paris-Sud XI, Université de

360

40 Cognitive Science class intervals that are equally spread across the data  

E-Print Network (OSTI)

40 Cognitive Science class intervals that are equally spread across the data range. For example and geographic visualization. Englewood Cliffs, NJ: PearsonJPrentice Hall. COGNITIVE SCIENCE Cognitive science. Cognition includes perception, thinking, learning, memory, reasoning and problem solving, and linguistic

Montello, Daniel R.

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Energy Spot Price Models and Spread Options Pricing Samuel Hikspoors and Sebastian Jaimungal a  

E-Print Network (OSTI)

). The world wide energy commodities markets have created a need for a deeper quan- titative understandingEnergy Spot Price Models and Spread Options Pricing Samuel Hikspoors and Sebastian Jaimungal a a Department of Statistics and Mathematical Finance Program, University of Toronto, 100 St. George Street

Jaimungal, Sebastian

362

LONG EXPOSURE POINT SPREAD FUNCTION ESTIMATION FROM SOLAR ADAPTIVE OPTICS LOOP DATA  

E-Print Network (OSTI)

Astronomer, National Solar Observatory, New Mexico, USA Dr. Haimin Wang, Dissertation Co-Advisor DateABSTRACT LONG EXPOSURE POINT SPREAD FUNCTION ESTIMATION FROM SOLAR ADAPTIVE OPTICS LOOP DATA during solar observations due to the lack of point sources in the field-of-view. Moreover, the highly

363

THE VALUATION OF CLEAN SPREAD OPTIONS: LINKING ELECTRICITY, EMISSIONS RENE CARMONA, MICHAEL COULON, AND DANIEL SCHWARZ  

E-Print Network (OSTI)

on CO2 by the regulation should be included in the costs of production to set the price of electricity which can be run when it is profitable to do so (namely when the price of electricity is greater thanTHE VALUATION OF CLEAN SPREAD OPTIONS: LINKING ELECTRICITY, EMISSIONS AND FUELS REN´E CARMONA

Carmona, Rene

364

A spreading episode at the southern end of the San Andreas fault system  

Science Journals Connector (OSTI)

... is between the Cerro Prieto and Imperial faults; the grey region denotes the Cerro Prieto geothermal field, with the arrows giving the expected direction of spreading. The star on the ... levelling data indicate up to 0.25 m of subsidence in the vicinity of the geothermal field10. The gravity measurements show significant positive gravity changes for the period of time ...

Paul G. Silver; J. N. Valette-Silver

1987-04-09T23:59:59.000Z

365

Insights into the Origin, Emergence, and Current Spread of a Successful Russian Clone of Mycobacterium tuberculosis  

Science Journals Connector (OSTI)

...regimen and wide use of the key first-line anti-TB drugs. In contrast, a link...operon), and the virulence-related eis, mce, and esx gene families. Other...emergence and spread in the human population. Supplemental material for this article may be found...

Igor Mokrousov

2013-04-01T23:59:59.000Z

366

Asymmetry in Directional Spreading Function of Random Waves due to Refraction  

E-Print Network (OSTI)

for deep water conditions. Analytic directional spreading functions take the form cos2 - p Pierson et al. Introduction Water waves generated by the wind are multidirectional random waves. The wave energy increases, 1970 , the Joint North Sea Wave Project JONSWAP spectrum Hassel- mann et al. 1973 , and the TEXEL storm

Haller, Merrick

367

DOCUMENTS DE TRAVAIL -WORKING PAPERS The spread of international financial shocks to Asean  

E-Print Network (OSTI)

to Asean countries Céline Gimet Décembre 2009 GATE Groupe d'Analyse et de Théorie �conomique UMR 5824 du;1 The spread of international financial shocks to Asean countries Céline Gimet1 November 2009 ABSTRACT This article focuses on the reaction of Asean economies to international financial shocks. The crises

Paris-Sud XI, Université de

368

A Spreading Activation Framework for Ontology-enhanced Adaptive Information Access  

E-Print Network (OSTI)

A Spreading Activation Framework for Ontology-enhanced Adaptive Information Access Md Maruf Hasan for Ontology-enhanced Adaptive Information Access Md Maruf Hasan, Enrico Motta, John B. Domingue, Simon Keynes, MK7 6AA, United Kingdom {m.m.hasan, e.motta, j.b.domingue, s.buckingham.sham, m.vargas-vera, m

369

Modelling the influence of human behaviour on the spread of infectious diseases: a review  

Science Journals Connector (OSTI)

...Funk 1 Marcel Salathe 2 * Vincent A. A. Jansen 1 * Author for correspondence ( salathe...more recently, with the MMR vaccine (Jansen et al. 2003). By making a rational...Gilad, C. Watkins, and V. A. A. Jansen 2009 The spread of awareness and its impact...

2010-01-01T23:59:59.000Z

370

Lifeasweknowit To understand the human genome, researchers must spread their wings to all branches of life.  

E-Print Network (OSTI)

and a worm to its ENCODE project, which aims to catalogue all the functional parts of the human genome is moving more forcefully into purely human genomics. The biggest new projects recently announcedLifeasweknowit To understand the human genome, researchers must spread their wings to all branches

Pratt, Vaughan

371

Current spread and overheating of high power laser bars B. Laikhtmana)  

E-Print Network (OSTI)

-power lasers, the width of the stripe is much larger than the cladding thick- ness, and the substrate thicknessCurrent spread and overheating of high power laser bars B. Laikhtmana) Power Photonic, 214 Old 11794 Received 27 May 2003; accepted 12 January 2004 The heating of a semiconductor laser bar imbedded

372

The Point Spread Function of the Human Head and its Implications for Transcranial Current  

E-Print Network (OSTI)

The Point Spread Function of the Human Head and its Implications for Transcranial Current distribution in the head resulting from the application of scalp currents. Derivation of forward models has represented a major effort in brain stimulation research, with model complexity ranging from spherical shells

Parra, Lucas C.

373

Modeling the Spread of Methicillin-Resistant Staphylococcus aureus in Nursing Homes for Elderly  

E-Print Network (OSTI)

Modeling the Spread of Methicillin-Resistant Staphylococcus aureus in Nursing Homes for Elderly hospital settings, including nursing homes. It is an important nosocomial pathogen that causes mortality homes is both hospital- and community-like. Transmission occurs via hands of health care workers (HCWs

Ruan, Shigui

374

Evaluation and Tuning of Model Trajectories and Spreading Rates in the Baltic Sea Using  

E-Print Network (OSTI)

Stockholm, Sweden e-mail: joakim@misu.su.se K. Döös e-mail: doos@misu.su.se T. Soomere Wave Engineering. The initial spreading, up to a distance of about d = 100­150 m, is governed by the power law d t0.27 whereas

Döös, Kristofer

375

A state-space solution search method for apparel industry spreading and cutting  

Science Journals Connector (OSTI)

The spreading of fabric onto cutting tables in several layers, and the cutting of this fabric in the most cost-efficient manner to produce a pre-determined number of garments is the apparel manufacturing phase that precedes assembly (sewing) and finishing. The problem consists of determining the lowest cost spreading and cutting schedule for garments of different styles, colors, and sizes, subject to physical constraints of cutting table length and cutting knife height as well as business constraints of required demand for each stock-keeping unit (SKU). The determination of this optimal spreading and cutting schedule for various garment styles is a difficult combinatorial NP-complete optimization problem. This paper proposes the use of an innovative state-space approach using heuristic rules to solve the problem: it is modeled as a least-cost search in a graph where each node represents a different spreading and cutting schedule. Several solution algorithms and heuristics are proposed and tested and an illustrative application to a Brazilian apparel company is presented.

Daniela B. Nascimento; J. Neiva de Figueiredo; S.F. Mayerle; P.R. Nascimento; R.M. Casali

2010-01-01T23:59:59.000Z

376

Progress in the Research Programs to Elucidate Axial Cracking Fuel Failure at High Burnup  

SciTech Connect

A fuel failure with an axial crack starting outside the cladding and penetrating inwards was experienced by high burnup BWR fuel rods in power ramp test. On the other hand, no fuel failure caused by power ramp test has been currently reported on PWR fuel rods at burnups higher than 50 GWd/t. Extensive research programs regarding hydrogen behaviors and mechanical performances on irradiated BWR and PWR fuel claddings have been carried out to clarify the mechanism of the axial cracking and to quantify the conditions to cause fuel failure. Hydrogen solid solubility measurement on irradiated Zircaloy-2 materials showed almost comparable results to those on unirradiated ones. Hydride re-distribution and re-orientation behaviors were tested by heating irradiated BWR claddings with Zr-liner under the conditions of applied radial heat flux (temperature gradient) and circumferential stress. Mechanical performances of BWR claddings were evaluated mainly by the internal pressurizing tests. Internal pressurization tests applying various pressurizing sequences, e.g. stepwise increase in pressure with holding intervals, were also conducted to simulate crack propagation behaviors. Some specimens demonstrated characteristic fracture surfaces similar to those observed on the failed fuel rods after the power ramp. Mechanical performances of irradiated PWR claddings were tested at temperatures of 573 to 723 K. Metallographic examination after tensile tests revealed a large number of incipient cracks within the region of cladding outer rim where a concentrated hydride layer (hydride rim) has been formed during irradiation. Crack propagation test using an expanding mandrel device demonstrated the crack propagation at 573 K but no propagation at 658 K. (authors)

Ogata, Keizo; Aomi, Masaki; Baba, Toshikazu; Kamimura, Katsuichiro [Japan Nuclear Energy Safety Organization, 3-17-1 Toranomon, Minato-ku, Tokyo 105-0001 (Japan); Etoh, Yoshinori [Nippon Nuclear Fuel Development Co., Ltd., 2163 Narita-cho, Oarai-machi, Ibaraki 311-1313 (Japan); Ito, Kunio [Grobal Nuclear Fuel - Japan Co., Ltd., 3-1 Uchikawa 2-chone, Yokosuka 239-0836 (Japan); Kido, Toshiya [Nuclear Development Corporation, 622-12 Funaishikawa, Tokai-mura, Ibaraki 319-1111 (Japan); Teshima, Hideyuki [Mitsubishi Heavy Industries, Ltd. 1-1, Wadasaki-cho 1-chome, Hyogo-ku, Kobe 652-8585 (Japan)

2007-07-01T23:59:59.000Z

377

Crack detection on HC-130H aircraft using low frequency eddy current  

SciTech Connect

An eddy current inspection method was developed at the Federal Aviation Administration`s Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect subsurface fatigue cracks in the wheel well fairing on the US Coast Guard (USCG) HC-130H aircraft caused by fatigue. The inspection procedure locates cracks as small as 10.2 millimeters in length at 2.54 mm below the skin surface at raised fastener sites. The test procedure developed baseline three USCG aircraft. Inspection results on the three aircraft reveals good correlation with results made during subsequent structural disassembly.

Moore, D.G. [Sandia National Labs., Albuquerque, NM (United States); Mihelic, J.E.; Barnes, J.D. [Coast Guard, Elizabeth City, NC (United States). Aircraft Repair and Supply Center

1998-02-01T23:59:59.000Z

378

Characterization of the plastic strain theory for predicting hot cracking during welding in aluminum alloys  

E-Print Network (OSTI)

, W. F. and Krantz, B. M. , "An Investigation of Hot Cracking in Hastelloy X, " ~Weldin Journal, ~45 1 , 13s-25s (1966) . Duvall, D. S. and Qwczarski, W. A. , "Further Heat-Affected-Zone Studies in Heat-Resistant Nickel Alloys, " ~Weldin Journal... (100X). 20 2024-T3 Specimen ? 8. 21 2024-T3 Specimen ? 15 22 10 12 2024-T3 Specimen ? 16 2024-T3 Specimen ? 21 5086 Specimen ? 14. 5086 Specimen ? 16. Typical 5052 Aluminum Microstructure. Crack Susceptibility of Aluminum Alloys 23 24 26...

Walters, Douglas Frederick

1970-01-01T23:59:59.000Z

379

Inuence of foreign-object damage on crack initiation and early crack growth during high-cycle fatigue of Ti6Al4V  

E-Print Network (OSTI)

; Ti±6Al±4V 1. Introduction The high-cycle fatigue (HCF) of aircraft gas-turbine engine components has of small surface fatigue cracks in a Ti±6Al±4V alloy, processed for typical turbine blade applications microcracks in the damaged zone (seen only at the higher impact velocities). Furthermore, the eect of residual

Ritchie, Robert

380

Atomic origin of hysteresis during cyclic loading of Si due to bond rearrangements at the crack surfaces  

E-Print Network (OSTI)

that invokes mechanically induced subcritical cracking to explain the delayed onset of failure. © 2005 American associated with a larger initial flaw, which is assumed to be caused by subcritical crack growth, 5- time during high cycle fatigue if water is present, and 6 a fatigue lifetime that depends only

Carter, Emily A.

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Materials Science and Engineering A231 (1997) 170182 Fatigue crack growth resistance in SiC particulate and whisker  

E-Print Network (OSTI)

Materials Science and Engineering A231 (1997) 170­182 Fatigue crack growth resistance in Si resulted in higher crack growth resistance at low growth rates in the particulate reinforced materials in these materials have indicated that many factors may be important in deter- mining the fatigue resistance of SiC/

Ritchie, Robert

382

An experimental study on the effects of compressive stress on the fatigue crack growth of low-alloy steel  

SciTech Connect

A series of fatigue crack growth rate tests was conducted in order to study effects of negative stress ratio on fatigue crack growth rate of low-alloy steel in air. Four-point bend specimens were used to simulate linear stress distributions typical of pressure vessel applications. This type of testing adds to knowledge on negative stress ratio effects for low-alloy steels obtained in the past from uniform tension-compression tests. Applied bending stress range was varied over twice the yield strength. Load control was used for tests for which the stress range was less than twice the yield strength and deflection control was used for the higher stress range tests. Crack geometries were both short and long fatigue cracks started at notches and tight fatigue cracks for which crack closure could occur over the full crack face. Results are presented in terms of the stress intensity factor ratio R = K{sub MIN}/K{sub MAX}. The negative R-ratio test results were correlated to an equation of the form da/dN = C[{Delta}K/(A-R)]{sup n}, where A, C, and n are curve fitting parameters. It was found that effects of negative R-ratio on fatigue crack growth rates for even the high stress range tests could be bounded by correlating the above equation to only positive R-ratio test results and extending the resulting equation into the negative R-ratio regime.

Jones, D.P.; Hoppe, R.G. [Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.; Hechmer, J.L. [Babcock and Wilcox Co., Barberton, OH (United States); James, B.A. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgy

1993-12-01T23:59:59.000Z

383

Evaluation of LBZ susceptibility of offshore structural steels by CTOD and instrumented pre-crack Charpy impact test  

SciTech Connect

Toughness of simulated HAZ was evaluated by means of CTOD and instrumented pre-crack Charpy tests. While the CTOD transition temperature represents brittle fracture initiation toughness, pre-crack Charpy transition temperature is strongly influenced by brittle fracture arrest toughness. The both transition temperatures are controlled by different microstructural parameters.

Aihara, Shuji; Okamoto, Kentaro [Nippon Steel Corp., Futtsu (Japan)

1994-12-31T23:59:59.000Z

384

Micromechanisms of short fatigue crack growth in an Al-Si piston alloy. T.O. Mbuya1  

E-Print Network (OSTI)

1 Micromechanisms of short fatigue crack growth in an Al-Si piston alloy. T.O. Mbuya1 , and P behaviour of a model cast aluminium piston alloy has been investigated. This has been achieved using. Keywords: Fatigue; Short fatigue cracks; Fatigue micromechanics; Al-Si ; Fatigue ; piston alloys 1

385

Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model and Computations  

E-Print Network (OSTI)

Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model In this paper we present the development of the macroscopic model describing the hydro-mechanical coupling model in the micro-porous domain saturated by a fluid. In the crack/vug domain the Stokes equation

Paris-Sud XI, Université de

386

Fracture toughness and fatigue-crack propagation in a ZrTiNiCuBe bulk metallic glass  

E-Print Network (OSTI)

growth and fracture toughness behavior, representing the conditions governing the subcritical amorphous alloy was also found to be susceptible to fatigue-crack growth under cyclic loading, with growth are thus available on the toughness and cyclic crack growth properties in these alloys. Accord- ingly

Ritchie, Robert

387

Comparative analysis of failure probability for ethylene cracking furnace tube using Monte Carlo and API RBI technology  

Science Journals Connector (OSTI)

Abstract Ethylene cracking furnace tube is one of the most critical components in the petrochemical industry to crack molecules at high temperature. The furnace tube degrades easily during operations which would cause equipment failure and lead to serious consequences, such as fire and explosion. In this work, a quantitative analysis of failure probability for the ethylene cracking furnace tube is performed using the Monte Carlo method and API Risk-Based Inspection (RBI) technology. The results have shown that the operation life of ethylene cracking furnace tube under interaction of creep and carburization is less than that under creep, and the failure probability calculated based on API RBI technology is lower than that using the Monte Carlo method. Moreover, the comparative analysis results prove further that creep and carburization are two main failure modes of the furnace tube rupture. Therefore, it is very necessary to provide reliable data to perform risk assessment and inspections on ethylene cracking furnace tube.

Wenhe Wang; Kaiwu Liang; Changyou Wang; Qingsheng Wang

2014-01-01T23:59:59.000Z

388

A microscopic model for thin lm spreading Douglas B. Abraham 1 , Rodolfo Cuerno 2 , and Esteban Moro 1  

E-Print Network (OSTI)

A microscopic model for thin #12;lm spreading Douglas B. Abraham 1 , Rodolfo Cuerno 2 , and Esteban-temporal uc- tuations of the precursor #12;lm observed in spreading experiments. Matter is transported both;lm about one molecule thick; this can be followed laterally out to an extension of the order of 10 7

Moro, Esteban

389

A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED  

E-Print Network (OSTI)

materials with high fracture toughness and elevated temperature resistance. Ideally, the ceramic side of the FGM provides thermal and corrosion resistance while the metallic side gives the necessary strengthA NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED MATERIALS

Paulino, Glaucio H.

390

Channel cracks in atomic-layer and molecular-layer deposited multilayer thin film coatings  

SciTech Connect

Metal oxide thin film coatings produced by atomic layer deposition have been shown to be an effective permeation barrier. The primary failure mode of such coatings under tensile loads is the propagation of channel cracks that penetrate vertically into the coating films. Recently, multi-layer structures that combine the metal oxide material with relatively soft polymeric layers produced by molecular layer deposition have been proposed to create composite thin films with desired properties, including potentially enhanced resistance to fracture. In this paper, we study the effects of layer geometry and material properties on the critical strain for channel crack propagation in the multi-layer composite films. Using finite element simulations and a thin-film fracture mechanics formalism, we show that if the fracture energy of the polymeric layer is lower than that of the metal oxide layer, the channel crack tends to penetrate through the entire composite film, and dividing the metal oxide and polymeric materials into thinner layers leads to a smaller critical strain. However, if the fracture energy of the polymeric material is high so that cracks only run through the metal oxide layers, more layers can result in a larger critical strain. For intermediate fracture energy of the polymer material, we developed a design map that identifies the optimal structure for given fracture energies and thicknesses of the metal oxide and polymeric layers. These results can facilitate the design of mechanically robust permeation barriers, an important component for the development of flexible electronics.

Long, Rong, E-mail: rlongmech@gmail.com [Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Dunn, Martin L. [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Singapore University of Technology and Design, Singapore 138682 (Singapore)

2014-06-21T23:59:59.000Z

391

A probabilistic model to predict the formation and propagation of crack networks in thermal  

E-Print Network (OSTI)

. In the case of cooling systems in nuclear power plants, observations revealed the presence of thermal crazing loading even if thermal fatigue is multiaxial. However, the first simulations on a uniaxial mechanicalA probabilistic model to predict the formation and propagation of crack networks in thermal fatigue

392

ABSTRACT. The stress-relief cracking (SRC) susceptibility of single-pass welds  

E-Print Network (OSTI)

steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble thermal simulation and pressure vessels for chemical and fossil power plants. Many components in these power plants oper- ate techniques. HCM2S was found to be more susceptible to stress-relief cracking than 2.25Cr-1Mo steel. Simulated

DuPont, John N.

393

Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking  

DOE Patents (OSTI)

A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

Steeves, Arthur F. (Schenectady, NY); Stewart, James C. (Loudonville, NY)

1981-01-01T23:59:59.000Z

394

Ultrasonic ply-by-ply detection of matrix cracks in laminated composites  

E-Print Network (OSTI)

on an unprecedented significance. In this work, an ultrasonic technique for the ply-by-ply detection of matrix cracks in laminated composites is developed. Experimental results are presented for graphite/epoxy laminates with different lay-ups and laminate thicknesses...

Ganpatye, Atul Shridatta

2005-02-17T23:59:59.000Z

395

Keep Customers—and Energy—From Slipping Through the Cracks  

Energy.gov (U.S. Department of Energy (DOE))

The most successful energy efficiency upgrade programs have customers who are willing and able to implement energy efficiency upgrades. This may seem like an obvious statement; however, many upgrade programs are struggling to reach their upgrade goals because they allow initially excited customers to slip through the cracks by not guiding them through the entire upgrade process.

396

Modeling of crack tip high inertia zone in dynamic brittle fracture  

E-Print Network (OSTI)

energy dissipation around the crack tip and is assumed to be a function of external energy per volume input into the system. Finite element analysis is performed on PMMA with constant velocity boundary conditions and mesh discretization based on the work...

Karedla-Ravi, Shankar

2007-09-17T23:59:59.000Z

397

Elastic-Plastic Models for Stable Crack Growtht *James R. Rice  

E-Print Network (OSTI)

Elastic-Plastic Models for Stable Crack Growtht by *James R. Rice Mareh 1973 'PCAbh ~ ~ e c.\\. (n do not fully recover their strain upon unloading. The idealized non-linear elastic (left) and rigid-plastic,. there is ~ strain concentration created at the cut-ahead tip in the rigid-plastic material and the deformation field

398

Crack propagation induced heating in crystalline energetic materials W. Holmes,a)  

E-Print Network (OSTI)

Crack propagation induced heating in crystalline energetic materials W. Holmes,a) R. S. Francis of the heating of molecular vibrations and the possible initiation of chemical reaction from heat dissipated that vibrational temperatures can reach 800 K in 55 ps and exceed 550 K for 1 ns after the initial heating

Fayer, Michael D.

399

Thermal resistance of bridged cracks in fiber-reinforced ceramic John Dryden  

E-Print Network (OSTI)

and elasticity in multiphase materials is emphasized. The results for the constriction resistance are comparedThermal resistance of bridged cracks in fiber-reinforced ceramic composites John Dryden Department of Mechanical and Materials Engineering, The University of Western Ontario, London, Ontario, Canada, N6A 5B9

Zok, Frank

400

Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996  

SciTech Connect

This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

1996-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Sensitivity analysis based crack propagation criterion for compressible and (near) incompressible hyperelastic materials  

Science Journals Connector (OSTI)

Sensitivity analysis of an XFEM crack propagation model is developed for shape and material parameters, where the direct differentiation method is applied to large strain problems with hyperelastic neo-Hookean materials. The presence of level set functions ... Keywords: Finite strains, Fracture, Incompressibility, Sensitivity analysis, XFEM

Primo Šuštari?; Mariana R. R. Seabra; Jose M. A. Cesar De Sa; Toma Rodi?

2014-05-01T23:59:59.000Z

402

A model for turbulent hydraulic fracture and application to crack propagation at glacier beds  

E-Print Network (OSTI)

Click Here for Full Article A model for turbulent hydraulic fracture and application to crack suggest that fluidinduced hydraulic fracture of an ice sheet from its bed sometimes occurs quickly. Citation: Tsai, V. C., and J. R. Rice (2010), A model for turbulent hydraulic fracture and application

403

Fraunhofer-Center fr Silizium-Photovoltaik CSP CRACK INVESTIGATION OF ENCAPSULATED  

E-Print Network (OSTI)

© Fraunhofer-Center für Silizium-Photovoltaik CSP CRACK INVESTIGATION OF ENCAPSULATED SOLAR CELLS UNDER THERMAL AND MECHANICAL STRESSES Martin Sander Fraunhofer Center for Silicon Photovoltaics CSP-5999, martin.sander@csp.fraunhofer.de Workshop "Impact of mechanical and thermal loads on the long term

404

Early Development Of Stress Corrosion Cracks At The Grain Scale: Incomplete Random Tessellation Model  

E-Print Network (OSTI)

Model Leon Cizelj, Marko Kovac "Jozef Stefan" Institute, Reactor Engineering Division, Ljubljana that anisotropy could have extremely important impact on the direction of crack propagation. Further analysis of reliability of affected tubes and to clarifications of main mechanisms governing the IGSCC. The reliability

Cizelj, Leon

405

A micromechanical approach of crack-induced damage in orthotropic media : application to a  

E-Print Network (OSTI)

with experimental data available for a ceramic matrix composite (unidirectional SiC-SiC). Key words: Homogenization; Eshelby tensor; Anisotropy; Damage; Brittle materials; Ceramic Matrix Composites; Micromechanics; Cracks matrix composite Vincent MONCHIET a , Cosmin GRUESCU b , Oana CAZACU c , Djimedo KONDO d, a

Paris-Sud XI, Université de

406

Evaluation of the MMCLIFE 3.0 code in predicting crack growth in titanium aluminide composites  

SciTech Connect

Crack growth and fatigue life predictions made with the MMCLIFE 3.0 code are compared to test data for unidirectional, continuously reinforced SCS-6/Ti-14Al-21Nb (wt pct) composite laminates. The MMCLIFE 3.0 analysis package is a design tool capable of predicting strength and fatigue performance in metal matrix composite (MMC) laminates. The code uses a combination of micromechanic lamina and macromechanic laminate analyses to predict stresses and uses linear elastic fracture mechanics to predict crack growth. The crack growth analysis includes a fiber bridging model to predict the growth of matrix flaws in 0{degree} laminates and is capable of predicting the effects of interfacial shear stress and thermal residual stresses. The code has also been modified to include edge-notch flaws in addition to center-notch flaws. The model was correlated with constant amplitude, isothermal data from crack growth tests conducted on 0- and 90{degree} SCS-6/Ti-14-21 laminates. Spectrum fatigue tests were conducted, which included dwell times and frequency effects. Strengths and areas for improvement for the analysis are discussed.

Harmon, D. [Boeing Co., St. Louis, MO (United States); Larsen, J.M. [Materials and Mfg. Directorate, Wright-Patterson AFB, OH (United States). Air Force Research Lab.; Peralta, A.; Hall, J.A. [Allied Signal Engines, Phoenix, AZ (United States)

1999-02-01T23:59:59.000Z

407

Comparing Methods of Estimating Crack Volume in Shrink-Swell Soils  

E-Print Network (OSTI)

and is located in Snook, TX. The second soil monitored is a Burleson Clay (Fine, smectitic, thermic Udic Haplusterts), which has smectitic mineralogy and is located 1 mile southwest of the Ships site. During two drying events, vertical subsidence and cracking...

Rivera, Leonardo D.

2011-08-04T23:59:59.000Z

408

On fracture criteria for dynamic crack propagation in elastic materials with couple stresses  

E-Print Network (OSTI)

The focus of the article is on fracture criteria for dynamic crack propagation in elastic materials with microstructures. Steady-state propagation of a Mode III semi-infinite crack subject to loading applied on the crack surfaces is considered. The micropolar behavior of the material is described by the theory of couple-stress elasticity developed by Koiter. This constitutive model includes the characteristic lengths in bending and torsion, and thus it is able to account for the underlying microstructures of the material. Both translational and micro-rotational inertial terms are included in the balance equations, and the behavior of the solution near to the crack tip is investigated by means of an asymptotic analysis. The asymptotic fields are used to evaluate the dynamic J-integral for a couple-stress material, and the energy release rate is derived by the corresponding conservation law. The propagation stability is studied according to the energy-based Griffith criterion and the obtained results are compar...

Morini, L; Mishuris, G; Radi, E

2013-01-01T23:59:59.000Z

409

Linking Grain Boundary Structure and Composition to Intergranular Stress Corrosion Cracking of Austenitic Stainless Steels  

SciTech Connect

Grain boundary structure and composition is assessed in austenitic stainless steels along with its influence on intergranular stress corrosion cracking (IGSCC) in high-temperature water. Brief examples are presented illustrating effects of grain boundary character and segregation on behavior in specific light-water-reactor environments. Although grain boundary engineering can produce an increased fraction of special boundaries in austenitic stainless alloys, practical benefits depend on the boundary orientation distribution. It is critical to recognize that only coherent sigma 3s appear to be resistant to SCC and the behavior of other low sigma boundaries is uncertain. Grain boundary composition can have a dominant effect on IGSCC under certain conditions, but altered interfacial chemistry is not required for cracking. In high-potential oxidizing environments, IGSCC susceptibility is a direct function of the boundary Cr concentration. Non-equilibrium thermal segregation of Cr and Mo is often present in millannealed stainless steels and may influence cracking susceptibility. This initial grain boundary composition alters subsequent radiation-induced segregation and delays irradiation-assisted SCC susceptibility to higher doses. Other alloying elements and impurities in 300-series stainless steels have been seen to enrich grain boundaries, but few have any significant impact on IGSCC susceptibility. One exception is Si that strongly segregates during irradiation. recent results suggest that Si may accelerate crack propagation in both low- and high-potential water environments. Critical research is still needed to isolate individual grain boundary characteristics and quantitatively link to IGSCC.

Bruemmer, Stephen M.

2004-08-10T23:59:59.000Z

410

Assessing Hydrogen-Assisted Cracking Fracture Modes in High-Strength  

E-Print Network (OSTI)

theoretical hydro- gen-assisted cracking mechanisms. In- deed, it was found that the microplastic- ity theory of Beachem can best describe how the stress intensity faqor and hydro- gen content affect the modes of inter to reassociate into diatomic hydrogen in pores and micro- voids. The pressure of diatomic hyd~oge~ KEY WORDS

Eagar, Thomas W.

411

Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jrme Fortin a  

E-Print Network (OSTI)

Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jérôme Fortin a , Yves Guéguen-Sur-Cèze Cedex, France a r t i c l e i n f o Article history: Available online xxxx Keywords: Glass Pressure evolution of synthetic glass (SON68) under compressive triaxial stresses (hydrostatic and deviatoric

Fortin, JĂ©rĂ´me

412

Section headings : Cavity and void detection1 SOIL CRACKS DETECTION BY 3D ELECTRICAL RESISTIVITY3  

E-Print Network (OSTI)

on limited size sample. Three-15 dimensional electrical resistivity prospecting enables now to monitor crack dimensional electrical resistivity surveys are commonly gathered by a network of in-line18 survey arrays medium 3D electrical resistivity22 model resolution was sensitive to electrode configuration orientation

Paris-Sud XI, Université de

413

CHARACTERISATION OF AGED HDPE PIPES FROM DRINKING WATER DISTRIBUTION: INVESTIGATION OF CRACK DEPTH BY NOL RING  

E-Print Network (OSTI)

CHARACTERISATION OF AGED HDPE PIPES FROM DRINKING WATER DISTRIBUTION: INVESTIGATION OF CRACK DEPTH are used for the transport of drinking water. However, disinfectants in water seem to have a strong impact for the distribution of drinking water. HDPE pipes are exposed to an internal pressure due to water flow. Furthermore

Paris-Sud XI, Université de

414

Features of hydrotreating catalytic cracking feed and heavy slow coking gas oils  

SciTech Connect

A possible means of more extensive processing of crude oil is the use, in catalytic cracking, of heavy coking gas oils (HCGOs), a feature of which is a higher content of polycyclic aromatic compounds and resins by comparison with straight-run vacuum distillates. The presence of these compounds in catalytic cracking feed causes a reduction in the product yield and increased coke formation. Therefore, one of the problems of hydrotreating feedstock of this kind is the hydrogenation of polycyclic arenes. Processes of extensive desulphurization and denitration occur in parallel, since the sulphur and nitrogen compounds of HCGO are chiefly condensed benzoderivatives of thiophene, pyridine and carbazole, and largely concentrated in heavy aromatic and resinous fractions. The composition of the saturated part of the cracking feed plays a large role in achieving the optimum yields of gaseous and gasoline fractions. Thus an increase in the proportion of cyclanes in the feed raises the gasoline yield. In this way, an investigation of the hydrocarbon conversions during the hydrotreatment of cracking feed is of great importance. The present paper sets out the results for studying the change in the group-structural characteristics of the hydrogenation products of a mixture containing 30% HCGOs according to data of {sup 1}H and {sup 13}C NMR spectroscopy. 7 refs., 7 figs., 1 tab.

Yefremov, N.I.; Kushnarev, D.F.; Frolov, P.A.; Chagovets, A.N.; Kalabin, G.A.

1993-12-31T23:59:59.000Z

415

METALLURGICAL AND MATERIALS TRANSACTIONS A VOLUME 30A, MARCH 1999--633 Fatigue-Crack Propagation Behavior of Ductile/Brittle  

E-Print Network (OSTI)

subcritical crack growth in the reinforcements them- selves, thereby diminishing the bridging zone reinforcement volume fraction (20 pct Nb). It was found that resistance to fatigue-crack growth improved-reinforced composites, such bridging was quite resilient under cyclic loading conditions. The superior crack-growth

Ritchie, Robert

416

Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking  

SciTech Connect

Approximately 68% of the aluminum produced in the United States is first cast into ingots prior to further processing into sheet, plate, extrusions, or foil. The direct chill (DC) semi-continuous casting process has been the mainstay of the aluminum industry for the production of ingots due largely to its robust nature and relative simplicity. Though the basic process of DC casting is in principle straightforward, the interaction of process parameters with heat extraction, microstructural evolution, and development of solidification stresses is too complex to analyze by intuition or practical experience. One issue in DC casting is the formation of stress cracks [1-15]. In particular, the move toward larger ingot cross-sections, the use of higher casting speeds, and an ever-increasing array of mold technologies have increased industry efficiencies but have made it more difficult to predict the occurrence of stress crack defects. The Aluminum Industry Technology Roadmap [16] has recognized the challenges inherent in the DC casting process and the control of stress cracks and selected the development of 'fundamental information on solidification of alloys to predict microstructure, surface properties, and stresses and strains' as a high-priority research need, and the 'lack of understanding of mechanisms of cracking as a function of alloy' and 'insufficient understanding of the aluminum solidification process', which is 'difficult to model', as technology barriers in aluminum casting processes. The goal of this Aluminum Industry of the Future (IOF) project was to assist the aluminum industry in reducing the incidence of stress cracks from the current level of 5% to 2%. Decreasing stress crack incidence is important for improving product quality and consistency as well as for saving resources and energy, since considerable amounts of cast metal could be saved by eliminating ingot cracking, by reducing the scalping thickness of the ingot before rolling, and by eliminating butt sawing. Full-scale industrial implementation of the results of the proposed research would lead to energy savings in excess of 6 trillion Btu by the year 2020. The research undertaken in this project aimed to achieve this objective by a collaboration of industry, university, and national laboratory personnel through Secat, Inc., a consortium of aluminum companies. During the four-year project, the industrial partners and the research team met in 16 quarterly meetings to discuss research results and research direction. The industrial partners provided guidance, facilities, and experience to the research team. The research team went to two industrial plants to measure temperature distributions in commercial 60,000-lb DC casting ingot production. The project focused on the development of a fundamental understanding of ingot cracking and detailed models of thermal conditions, solidification, microstructural evolution, and stress development during the initial transient in DC castings of the aluminum alloys 3004 and 5182. The microstructure of the DC casting ingots was systematically characterized. Carefully designed experiments were carried out at the national laboratory and university facilities as well as at the industrial locations using the industrial production facilities. The advanced computational capabilities of the national laboratories were used for thermodynamic and kinetic simulations of phase transformation, heat transfer and fluid flow, solidification, and stress-strain evolution during DC casting. The achievements of the project are the following: (1) Identified the nature of crack formation during DC casting; (2) Developed a novel method for determining the mechanical properties of an alloy at the nonequilibrium mushy zone of the alloy; (3) Measured heat transfer coefficients (HTCs) between the solidifying ingot and the cooling water jet; (4) Determined the material constitutive model at high temperatures; and (5) Developed computational capabilities for the simulation of cracking formation in DC casting ingot. The models and the database de

Das, S.K.; Ningileri, S.; Long, Z.; Saito, K.; Khraisheh, M.; Hassan, M.H.; Kuwana, K.; Han, Q.; Viswanathan, S.; Sabau, A.S.; Clark, J.; Hyrn, J. (ANL)

2006-08-15T23:59:59.000Z

417

Stress Corrosion Cracking Response of 304 Stainless Steel in ASerated and Dearated Water  

SciTech Connect

Scoping stress corrosion cracking (SCC) tests of 304 stainless steel (SS) were performed in 75 C and 250 C aerated pressurized water (APW) and 250 C deaerated pressurized water (DPW). The 250 C APW environment was used to initiate intergranular stress corrosion cracking (IGSCC) and then the water was deaerated and hydrogenated to see if IGSCC continued in 250 C DPW. Tests were performed with and without 200 ppb SO{sub 4}{sup =}. The 304 SS test materials were evaluated in either the as-received, heavily sensitized (649 C for 1 h), fully sensitized (1099 C for 1 h/water quench/621 C for 17 h) or 20% cold rolled condition. At the beginning of each test sequence, specimens were subjected to continuous cycling with a 500s rise/500s fall or a 5000s rise/500s fall to promote the transition from a transgranular (TG) precrack to an IG crack. After generating a uniform crack under continuous cycling conditions, a trapezoidal waveform with 500s rise/9000s hold/500s fall was used to characterize the SCC behavior. Crack growth rates (CGRs) were monitored continuously with the electric potential drop (EPD) method and were corrected based on physical crack length measurements obtained when specimens were destructively evaluated. Continuous cycling with a 500s or 5000s rise time was found to produce both TG faceting and IGSCC in fully sensitized 304 SS tested in 75 C APW with 7 ppm O{sub 2} and 200 ppb SO{sub 4}{sup =}. However, no measurable crack extension occurred when a 9000 s hold time was introduced. Extensive IGSCC occurred in heavily sensitized and fully sensitized 304 SS in 250 C APW with 1 ppm O{sub 2} and 200 ppb SO{sub 4}{sup =}. IGSCC initiated under continuous cycling conditions with a 500 s rise time, and rapid IGSCC occurred when a 9000 s hold time was introduced. During the trapezoidal waveform test with a 9000 s hold, CGRs ranged from 1 to 3 mils/day for the heavily sensitized material and 5 to 10 mils/day for the fully sensitized material. When the test environment was dearated and hydrogenated to 30 cc H{sub 2}/kg H{sub 2}O, CGRs decreased by an order of magnitude ({approx}0.1 mils/day), and the cracking mode in 250 C DPW was predominantly TG. The only material that exhibited evidence of IGSCC in 250 C DPW was 20% cold rolled 304 SS. IGSCC readily initiated in 250 C APW and continued in 250 C DPW. Metallographic and fractographic examinations showed that the IG cracking was highly branched and discontinuous. Results from the scoping SCC tests have revealed significant information regarding the nature of IG and TG cracking of 304 SS in APW and DPW. The key finding is that cold work appears to be more important than sensitization in producing IGSCC in DPW.

Mills, W. J.

2007-04-30T23:59:59.000Z

418

Revealing latent factors of temporal networks for mesoscale intervention in epidemic spread  

E-Print Network (OSTI)

The customary perspective to reason about epidemic mitigation in temporal networks hinges on the identification of nodes with specific features or network roles. The ensuing individual-based control strategies, however, are difficult to carry out in practice and ignore important correlations between topological and temporal patterns. Here we adopt a mesoscopic perspective and present a principled framework to identify collective features at multiple scales and rank their importance for epidemic spread. We use tensor decomposition techniques to build an additive representation of a temporal network in terms of mesostructures, such as cohesive clusters and temporally-localized mixing patterns. This representation allows to determine the impact of individual mesostructures on epidemic spread and to assess the effect of targeted interventions that remove chosen structures. We illustrate this approach using high-resolution social network data on face-to-face interactions in a school and show that our method afford...

Gauvin, Laetitia; Barrat, Alain; Cattuto, Ciro

2015-01-01T23:59:59.000Z

419

Space charge modeling of dense electron beams with large energy spreads  

Science Journals Connector (OSTI)

Theoretical and numerical studies of the transport in vacuum of multi-nC, multi-MeV electron beams are performed using several methods, including envelope models, a novel semianalytic approach using ellipsoidal shell decomposition, a modified electrostatic particle-in-cell method, and a point-to-point interaction model. The effects of space-charge forces on the longitudinal and transverse bunch properties are evaluated for various bunch lengths, energies, energy spreads, and charges. An evaluation of the various methods for studying space-charge effects in large energy spread, high charge beams is summarized. Examples are given for beam distributions typical of those generated by plasma-based accelerators. It is found that, for the highly correlated beams produced in the self-modulated regime, the high energy portion of the beam can gain significant energy while propagating in vacuum due to space-charge effects.

G. Fubiani; J. Qiang; E. Esarey; W. P. Leemans; G. Dugan

2006-06-22T23:59:59.000Z

420

A Hierarchy of Linear Threshold Models for the Spread of Political Revolutions on Social Networks  

E-Print Network (OSTI)

We study a linear threshold agent-based model (ABM) for the spread of political revolutions on social networks using empirical network data. We propose new techniques for building a hierarchy of simplified ordinary differential equation (ODE) based models that aim to capture essential features of the ABM, including effects of the actual networks, and give insight in the parameter regime transitions of the ABM. We relate the ABM and the hierarchy of models to a population-level compartmental ODE model that we proposed previously for the spread of political revolutions [1], which is shown to be mathematically consistent with the proposed ABM and provides a way to analyze the global behaviour of the ABM. This consistency with the linear threshold ABM also provides further justification a posteriori for the compartmental model of [1]. Extending concepts from epidemiological modelling, we define a basic reproduction number $R_0$ for the linear threshold ABM and apply it to predict ABM behaviour on empirical networ...

Lang, John C

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Performance Demonstration Based Probablity of Detection (POD) Curves for Fatigue Cracks in Piping  

SciTech Connect

This paper evaluates non-destructive examination (NDE) detection capabilities for fatigue cracks in piping. Industry performance demonstration initiative (PDI) data for fatigue crack detection were used to develop a matrix of statistically based probability of detection (POD) curves that consider various NDE performance factors. Seven primary performance factors were identified – Material, Crack Geometry/Type, NDE Examination Access, NDE Procedure, Examiner Qualification, Pipe Diameter, and Pipe Wall Thickness. A database of 16,181 NDE performance observations, with 18 fields associated with each observation, was created and used to develop statistically based POD curves for 42 stainless steel and 14 carbon steel performance cases. Subsequent comparisons of the POD fits for each of the cases showed that excellent NDE performance for fatigue cracks can be expected for ferritic materials. Very little difference was observed between the POD curves for the 14 carbon steel performance cases considered in this study and NDE performance could therefore be represented by a single POD curve. For stainless steel, very good performance can also be expected for circumferential cracks located on the same side of the weld from which the NDE examination is made. POD depended primarily on component thickness. Three POD curves for stainless steel were prepared. Best estimate and the associated 95% confidence bounds for POD versas through-wall depth logistic regression digital data are provided. Probabilistic fracture mechanics (PFM) calculations were performed to compare best estimate leak probabilities obtained from both the new performance-based POD curves and previous PFM models. This work was performed under joint funding by EPRI and the U.S. Department of Energy (DOE), Office of Nuclear Energy Science and Technology’s Nuclear Energy Plant Optimization (NEPO) program.

Gosselin, Stephen R.; Simonen, Fredric A.; Heasler, Patrick G.; Becker, F. L.; Doctor, Steven R.; Carter, R. G.

2005-07-01T23:59:59.000Z

422

Modelling of Infrared emission from Cyg X3 and the UKIRT IRCAM3 point spread function  

E-Print Network (OSTI)

in order to test for any extended emission around the X­ray binary Cyg X­3. We found that the point spread ranging from 12 magnitude (Cyg X­3) to 18th mag for some of the faintest stars. The positions of the stars instrument. 2 #12; 2.1 k­band image The k­band image, figure 2 or the finder chart provided by Fender (Fender

Ogley, Richard

423

How Do You Spread the Word About Saving Energy? | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

How Do You Spread the Word About Saving Energy? How Do You Spread the Word About Saving Energy? How Do You Spread the Word About Saving Energy? May 25, 2012 - 2:03pm Addthis Earlier this week, Drew talked about how you can follow Energy Savers and the Office of Energy Efficiency and Renewable Energy on Facebook. But do you share energy saving tips with your own friends, family, and readers? Do you use social media? Do you share tips about how to save energy? And if you do, how? You have the chance to share your thoughts on a question about energy efficiency or renewable energy for consumers. E-mail your responses to the Energy Saver team at consumer.webmaster@nrel.gov. Addthis Related Articles Navigating the New EnergySaver.gov What Are Your Top Tips for Saving Energy? By taking simple steps to improve your home's energy efficiency, you can save up to 30 percent on your energy bill. | Infographic by Sarah Gerrity.

424

On compensating tune spread induced by space charge in bunched beams  

SciTech Connect

Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.

Litvinenko, V. N.; Wang, G.

2014-05-09T23:59:59.000Z

425

Design, Implementation, and Evaluation of a Hybrid DS/FFH Spread-Spectrum Radio Transceiver  

SciTech Connect

In recent years there has been great interest in using hybrid spread-spectrum (HSS) techniques for commercial applications, particularly in the Smart Grid, in addition to their inherent uses in military communications. This is because HSS can accommodate high data rates with high link integrity, even in the presence of significant multipath effects and interfering signals. A highly useful form of this transmission technique for many types of command, control, and sensing applications is the specific code-related combination of standard direct-sequence modulation with "fast" frequency-hopping, denoted hybrid DS/FFH, wherein multiple frequency hops occur within a single data-bit time. In this paper, we present the efforts carried out at Oak Ridge National Laboratory toward exploring the design, implementation, and evaluation of a hybrid DS/FFH spread-spectrum radio transceiver using a single Field Programmable Gate Array (FPGA). The FPGA allows the various subsystems to quickly communicate with each other and thereby maintain tight synchronization. We also investigate various hopping sequences against robustness to interference and jamming. Experimental results are presented that show the receiver sensitivity, radio data-rate/bit-error evaluations, and jamming and interference rejection capabilities of the implemented hybrid DS/FFH spread-spectrum system under widely varying design parameters.

Olama, Mohammed M [ORNL; Killough, Stephen M [ORNL; Kuruganti, Teja [ORNL; Carroll, Thomas E. [Pacific Northwest National Laboratory (PNNL)

2014-01-01T23:59:59.000Z

426

Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations  

E-Print Network (OSTI)

Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from ten neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such trend. Moreover, it is important to note that an opposite trend is not found from any of the bursts. The concave shape of the fractional ampli...

Chakraborty, Manoneeta

2014-01-01T23:59:59.000Z

427

Micromechanisms of creep-fatigue crack growth in a silicide-matrix composite with SiC particles  

SciTech Connect

An experimental study has been conducted to examine the cyclic fatigue crack growth characteristics in 1,200 C air of a MoSi[sub 2]-50 mol% WSi[sub 2] alloy in the unreinforced condition and with 30 vol% SiC particles. For comparison purposes, crack growth experiments under sustained loads were also carried out in the silicide-matrix composite. Particular attention is devoted to developing an understanding of the micromechanism of subcritical crack growth by recourse to optical and electron microscopy, including transmission electron microscopy of crack-tip damage. The results indicate that enhanced viscous flow of glass films along interfaces and grain boundaries imparts pronounced levels of subcritical crack growth in the composite material; the composite exhibits a higher fatigue fracture threshold and a more extended range of stable fracture than the unreinforced alloy. The effects of glass phase in influencing fatigue crack growth in the silicide-based material are compared to the influence of in situ-formed and preexisting glass films on high-temperature cyclic fatigue crack growth in ceramics and ceramic composites. The paper concludes with a comparison of present results with the high-temperature damage tolerance of a variety of intermetallic alloys and ceramic materials.

Ramamurty, U.; Kim, A.S.; Suresh, S. (Brown Univ., Providence, RI (United States)); Petrovic, J.J. (Los Alamos National Lab., NM (United States))

1993-08-01T23:59:59.000Z

428

Investigation of steel corrosion in cracked concrete: Evaluation of macrocell and microcell rates using Tafel polarization response  

Science Journals Connector (OSTI)

Inhomogeneous corrosion in reinforced concrete is investigated using a beam with a flexural crack intersecting the reinforcement. An Evans diagram representation of the macrocell corrosion system is developed. The relationship between the current density and the potentials relative to the crack obtained from the Tafel polarization responses of active and passive steel in concrete compares favorably with the experimental values. When both microcell and macrocell mechanisms contribute to metal loss at the crack, the Evans diagram representation indicates that an increase in the macrocell current density results in a decreasing contribution from the local microcell at the macrocell anode.

Kolluru V. Subramaniam; Mingdong Bi

2010-01-01T23:59:59.000Z

429

The equilibrium concentration of hydrogen atoms ahead of a mixed mode I-mode III crack tip in single crystal iron  

SciTech Connect

Calculations of the equilibrium hydrogen concentration profiles about a mixed ode I-mode III crack in single crystal iron were performed. Both material anisotropy and the tetragonal nature of the distortion induced in the iron crystal structure by interstitial hydrogen were incorporated. Results show that, unlike the case of a spherical distortion, a strong coupling exists between the strain field of the interstitial hydrogen and the stress field of the crack for orientations of the crack plane that are not coincident with the cube axes of the lattice. As a result, the predicated enhancement of hydrogen in the crack tip region increases with increasing levels of mode III loading for those orientations. The results may help reconcile conflicting observations concerning the potential role of shear stresses in hydrogen embrittlement and preferential cracking of grains ahead of loaded crack tips in sustained load cracking experiments.

Zhang, T.Y.; Hack, J.E. [Yale Univ., New Haven, CT (United States). Dept. of Mechanical Engineering

1999-01-01T23:59:59.000Z

430

A note on the effects of nonuniform spreading velocity of submarine slumps and slides on the near-eld tsunami amplitudes  

E-Print Network (OSTI)

A note on the effects of nonuniform spreading velocity of submarine slumps and slides on the near Accepted 9 February 2002 Abstract The effects of variable speeds of spreading of submarine slides slides and slumps must consider time variations in the spreading velocities, when these velocities

Southern California, University of

431

Modeling the Spread and Outbreak Dynamics of Avian Influenza (H5N1) Virus and Its Possible Control  

Science Journals Connector (OSTI)

Avian Influenza, commonly known as Bird Flu, is an epidemic caused by H5N1 Virus ... The present chapter is aimed at developing mathematical models that predict the spread and outbreak diversity of low pathogenic...

V. Sree Hari Rao; Ranjit Kumar Upadhyay

2013-01-01T23:59:59.000Z

432

Nonvolcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15N on the Mid-  

E-Print Network (OSTI)

mafic crust is constructed by volcanism and shallow magma intrusion (Figure 1a) [e.g., Sinton sections of intermediate- and slow- spreading ridges [Sinton and Detrick, 1992]. Non-

433

Russia's Wild Wild South: Two Tales of Economic Woes, Political Corruption and Spreading Insurgent Violence in Ingushetia and Dagestan  

E-Print Network (OSTI)

The Northern Caucasus has been a troubled region for the Russian Federation for nearly two decades. In the 1990s, two wars took place in Chechnya and violence spread into the neighboring republics of Ingushetia and Dagestan. ...

Grandstaff, John M.

2011-05-14T23:59:59.000Z

434

Annex A -Potential threats in EU Organism(s) Means of spread Control measures Control approaches being used in  

E-Print Network (OSTI)

Annex A - Potential threats in EU Organism(s) Means of spread Control measures Control approaches options Potential threats in EU keep out, knowledge of trade routes, awareness on nurseries, foresters

435

Structure, chemistry, and stress corrosion cracking of grain boundaries in alloys 600 and 690  

SciTech Connect

The microstructure in six commercial batches of alloys 600 and 690 has been investigated using scanning electron microscopy (SEM), analytical transmission electron microscopy (ATEM), atom probe field ion microscopy (APFIM), and secondary ion mass spectroscopy (SIMS). The materials were also tested with respect to their resistance to intergranular stress corrosion cracking (IGSCC) in high-purity water at 365 C. Applied microanalytical techniques allowed direct measurement of carbon concentration in the matrix together with determination of grain boundary microstructure and microchemistry in all material conditions. The distribution of oxygen near a crack in material tested with respect to IGSCC was also investigated. The role of carbon and chromium and intergranular precipitates on IGSCC is discussed.

Stiller, K. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics; Nilsson, J.O. [AB Sandvik Steel, Sandviken (Sweden); Norring, K. [Studsvik Material AB, Nykoeping (Sweden)

1996-02-01T23:59:59.000Z

436

A review of fatigue crack growth rates for offshore steels in air and seawater environments  

SciTech Connect

A literature review of fatigue crack growth rates (FCGR) has been performed for steels in air and seawater environments, either free corroding or with applied cathodic protection potentials of {minus}850 and {minus}1050/{minus}1100 mV Ag/AgCl. In all cases a more precise description of cracking was obtained using a bi-linear growth law rather than the more conventional Paris Law. Recommendations were made for mean and design values of the constants C and m on a piece-wise basis suitable for use in fracture mechanics analyses of structures. An effect of R-ratio was observed, and separate recommendations were made for high and low R-ratios to cater for as-welded, and post weld heat treated joints with low mean stress levels.

King, R.N. [Failure Control Ltd., Cranleigh (United Kingdom); Stacey, A.; Sharp, J.V. [Health and Safety Executive, London (United Kingdom). Offshore Safety Div.

1996-12-01T23:59:59.000Z

437

Fracture criterion for predicting surface cracking of Ti40 alloy in hot forming processes  

Science Journals Connector (OSTI)

Hot compression tests were conducted on Ti40 burn resistant titanium alloy in the temperature range of 900–1 100 °C and strain rate range of 0.01–10 s?1 to investigate its fracture behavior and critical fracture conditions in hot forming. It was observed that the failure of Ti40 alloy is attributed to longitudinal surface cracking due to severe oxidation of element V and the secondary tensile stresses. The critical fracture strain increases with increasing temperature and decreasing strain rate. From these observations and parallel FEM simulations, it was concluded that the critical fracture strain is a function of a single argument Zener-Hollomon parameter, and there is a linear relationship between them. An Oyane criterion successfully predicted the location of crack initiation. The critical fracture values also exhibit a liner relationship with lnZ. Based on these results, a new fracture criterion of Ti40 alloy based on Zener-Hollomon parameter was established.

Xue-min ZHANG; Wei-dong ZENG; Ying SHU; Yi-gang ZHOU; Yong-qing ZHAO; Huan WU; Han-qing YU

2009-01-01T23:59:59.000Z

438

Stress Corrosion Cracking of Ferritic Materials for Fossil Power Generation Applications  

SciTech Connect

Creep strength enhanced ferritic (CSEF) steels Grades 23, 24, 91, and 92 have been widely implemented in the fossil fired industry for over two decades. The stress corrosion cracking (SCC) behavior of these materials with respect to mainstay Cr-Mo steels (such as Grades 11, 12 and 22) has not been properly assessed, particularly in consideration of recent reported issues of SCC in CSEF steels. This report details the results of Jones test exposures of a wide range of materials (Grades 11, 22, 23, 24, and 92), material conditions (as-received, improper heat treatments, normalized, weldments) and environments (salt fog; tube cleaning environments including decreasing, scale removal, and passivation; and high temperature water) to compare the susceptibility to cracking of these steels. In the as-received (normalized and tempered) condition, none of these materials are susceptible to SCC in the environments examined. However, in the hardened condition, certain combinations of environment and alloy reveal substantial SCC susceptibility.

Pawel, Steven J [ORNL] [ORNL; Siefert, John A. [Electric Power Research Institute (EPRI)] [Electric Power Research Institute (EPRI)

2014-01-01T23:59:59.000Z

439

Self-replicating cracks: a collaborative fracture mode in thin films  

E-Print Network (OSTI)

Straight cracks are observed in thin coatings under residual tensile stress, resulting into the classical network pattern observed in china crockery, old paintings or dry mud. Here, we present a novel fracture mechanism where delamination and propagation occur simultaneously, leading to the spontaneous self-replication of an initial template. Surprisingly, this mechanism is active below the standard critical tensile load for channel cracks and selects a robust interaction length scale on the order of 30 times the film thickness. Depending on triggering mechanisms, crescent alleys, spirals or long bands are generated over a wide range of experimental parameters. We describe with a simple physical model the selection of the fracture path and provide a configuration diagram displaying the different failure modes.

Joel Marthelot; Benoit Roman; Jose Bico; Jeremie Teisseire; Davy Dalmas; Francisco Melo

2014-08-20T23:59:59.000Z

440

The probabilistic life time prediction model of oil pipeline due to local corrosion crack  

Science Journals Connector (OSTI)

Abstract A four-stage probabilistic damage model is proposed basis of cross-scale damage processes to deal with the local corrosion crack of oil pipeline. At first, some key parameters for life time prediction were determined; then the probabilistic damage model is formulated and numerically calculated by using Monte Carlo Simulation (MCS). Furthermore, the model is used to deal with an example in order to check its validity. The results show that the life-span of this pipeline is nearly 20.55 years, and the pipe wall thickness, operating pressure difference and corrosion electric current density are the three key parameters to determine the span-life of this pipeline; the longest examination and repair period should be less than 4.71 years for safety when the surface crack length of 10 mm can be detected reliably.

Jun Hu; Yangyang Tian; Haipeng Teng; Lijun Yu; Maosheng Zheng

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rbob-brent crack spread" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Strain-rate effects on deflection/penetration of crack terminating perpendicular to bimaterial interface under dynamic loadings  

Science Journals Connector (OSTI)

Strain-rate effects on the deflection/penetration behaviors of a crack terminating perpendicular to ... . The competition between the deflection and the penetration is found to depend markedly on the loading rate

L. G. Liu; Z. C. Ou; Z. P. Duan; A. G. Pi; F. L. Huang

2011-02-01T23:59:59.000Z

442

High-cycle fatigue of nickel-base superalloy Rene 104 (ME3): Interaction of microstructurally small cracks with  

E-Print Network (OSTI)

. Specifically, we examine the interaction of propagating small ($10­900 lm) sur- face cracks with grain of a size in the range of few to hundreds of micrometers. In gas-turbine components such as blades and disks

Ritchie, Robert

443

Relation between the characteristics of the pitches produced on the basis of heavy gas-oil of catalytic cracking  

SciTech Connect

Mesophase pitches are often used to produce carbon fibers. Results of microanalysis and fiber-forming ability of the pitches are described. The pitches were obtained by the catalytic cracking of heavy gas-oil.

Nikolaeva, L.V.; Bulanova, V.V. [Rossiiskaya Akadeiya, Nauk (Russian Federation)

1995-12-31T23:59:59.000Z

444

Prediction of early-age cracking of UHPC materials and structures : a thremo-chemo-mechanics approach  

E-Print Network (OSTI)

Ultra-High Performance Concrete [UHPC] has remarkable performance in mechanical properties, ductility, economical benefit, etc., but early-age cracking of UHPC can become an issue during the manufacturing process due to ...

Shim, JongMin, 1975-

2005-01-01T23:59:59.000Z

445

A new statistical dispersion model for tracer tests and contaminant spread in porous media  

SciTech Connect

Dispersion of solutes moving in permeable media is an essential control to describe fluid flow in permeable media. Dispersion can be thought of as a spreading of a solute caused by the presence of microscopic inhomogeneities. An accurate model for dispersion is needed for accurate estimation of oil recovery efficiencies and clean up costs of subsurface contaminants. Current approaches utilizing the fickian assumption fall short in describing the real physics of spreading during a solute transport process. Numerous field investigations have shown that dispersivities measured in the field are much larger than those measured in the lab for the same type of porous material. Moreover, field measured dispersivities have been shown to be scale dependent, that is, a tracer test conducted over a longer travel path will yield a larger dispersivity value than a tracer test conducted in the same geologic formation over a shorter travel path. Numerous approaches to address this problem have been developed yet none attempted to go beyond the Fickian dispersion assumption. In this study, a convective dispersivity is introduced. New model assumes that dispersion is dimensionless and mainly determined by pore size distribution. The new model results in a spread that increases linearly with time contrary to conventional model, which predicts a mixing zone length that increases with square root of time. Therefore, new model explains the field test results that indicate increasing dispersivity with distance. The model validations are in perfect agreement with experimental results, which include; Ganapathy et al.`s slug experiment on Antolini sandstone, Handy`s radioactive tracer experiment on Alhambra sandstone, and CT experiment conducted at BDM-OK/NIPER facilities on Tallant sandstone.

Ates, H.; Kasap, E. [Univ. of Tulsa, OK (United States)

1995-12-31T23:59:59.000Z

446

Energy and environmental research emphasizing low-rank coal: Task 3.9 catalytic tar cracking  

SciTech Connect

Tar produced in the gasification of coal is deleterious to the operation of downstream equipment, including fuel cells, gas turbines, hot-gas stream cleanup filters, and pressure-swing absorption systems. Catalytic cracking of tars to smaller hydrocarbons can be an effective means of removing these tars from gas streams and, in the process, generating useful products, such as methane gas, which is crucial to operation of molten carbonate fuel cells. Aerosol tars are not readily removed from gas streams by conventional means and, as a consequence, often end up plugging filters or fouling fuel cells, turbines, or sorbents. Catalytic cracking of these tars to molecular moieties of C{sub 10} or smaller would prevent the problems commonly attributed to the tars. As an example, the moving Bourdon fixed-bed gasifier, by virtue of its efficient countercurrent heat exchange and widespread commercial use, may offer the lowest-cost integrated gasification combined-cycle (IGCC) system if tar generation and wastewater contamination can be minimized. We evaluate the potential of selected catalysts to minimize tar accumulation and maximize char conversion to useful liquid and/or gaseous products. Owing to the potential for production of extremely toxic nickel carbonyl gas, care must be exercised in the use of a NISMM catalyst for cracking tars at high temperatures in reducing atmospheres such as those produced by coal gasification. We observed a fifty percent or more of tar produced during steam gasification of Beulah lignite at temperatures of 400{degrees}-800+{degrees}C when cracked by either dolomite or zeolite maintained at a temperature of 50{degrees}C-100{degrees}C below that of the reactor.

Timpe, R.C.

1995-09-01T23:59:59.000Z

447

Intersecting Epidemics -- Crack Cocaine Use and HIV Infection among Inner-City Young Adults  

Science Journals Connector (OSTI)

...be Hispanic or white (PHispanic African Americans, 8 percent of the smokers and 9 percent of the nonsmokers were Hispanics, 3 percent of the smokers and 5 percent of the nonsmokers were black Hispanics, and... “Crack” cocaine, an addictive, smokable form of cocaine, gained widespread use in many urban neighborhoods in the United States in the mid-1980s, particularly among poor young adults who were members of minority groups1–6. A recent national household ...

Edlin B.R.; Irwin K.L.; Faruque S.

1994-11-24T23:59:59.000Z

448

A Multidomain Model for Ionic Electrodiffusion and Osmosis with an Application to Cortical Spreading Depression  

E-Print Network (OSTI)

Ionic electrodiffusion and osmotic water flow are central processes in many physiological systems. We formulate a system of partial differential equations that governs ion movement and water flow in biological tissue. A salient feature of this model is that it satisfies a free energy identity, ensuring the thermodynamic consistency of the model. A numerical scheme is developed for the model in one spatial dimension and is applied to a model of cortical spreading depression, a propagating breakdown of ionic and cell volume homeostasis in the brain.

Yoichiro Mori

2014-10-30T23:59:59.000Z

449

On the spreading of Weddell Sea deep water in the southwestern Atlantic Ocean  

E-Print Network (OSTI)

poleward heat flux by abyssal boundary currents across the ACC. 35' S ARGENTINE BASIN 45' S * 0 ~ rlL OEI WICH IN 55' S 65' S RGB o ~D 6' pI 1 WEDDELL SEA Attt Btk 70 W 60' W 50' W 40' W 30' W 20 W 10' W 0 Fig 2. Bathymetric chart... Water. Chlorofluorocarbon measurements indicate that WSDW with an age of about a decade can reach the Georgia Basin via the Scotia Sea faster than by spreading equatorward over the South Sandwich Trench. Geostrophic calculations show that about 1. 8...

Locarnini, Ricardo A

2012-06-07T23:59:59.000Z

450

Analysis of steady-state propagating cracks in metals under creep conditions  

SciTech Connect

Asymptotic analysis of the near-tip field of cracks propagating at constant velocities in metals experiencing small-scale creep is presented. The constitutive law incorporates a back-stress, a threshold stress below which creep deformation does not occur. In addition, a more complete description of the time dependent uniaxial creep behavior is employed than in previous studies, as both the transient and secondary stages of the creep deformation are retained. As a result of these developments, a natural length parameter, the size of the creep zone, emerges and the role of transient creep is clarified. The solution of the mode III problem is first presented and the leading term of the asymptotic expansion of the stress potential determined. The concept of an elastic wake zone behind the crack is introduced and its extent is evaluated for a range of creep parameters, Predictions of creep zone, shape, and crack propagation speed are made for commercial ferritic steel, HT-9, typically used in power plant systems. Solutions to the mode I problem, both plane stress and plane strain, are also presented. The character of the asymptotic solution is found to be different in plane strain from the results for mode III and plane stress. While in the latter cases solutions with an elastic wake are found for all practical values of the creep exponent, in plane strain deformation such a wake zone is not present. Creep zone estimates and propagation speed versus load relations are presented for a mode I example.

Orient, G.E. [Rocketdyne, Rockwell International, Canoga Park, CA (United States); Westmann, R.A.; Ghoniem, N.M. [Univ. of California, Los Angeles, CA (United States)

1995-12-31T23:59:59.000Z

451

Integrated two stage coking and steam cracking process and apparatus therefor  

SciTech Connect

The invention relates to an improvement in an integrated, two stage coking and steam cracking process for the production of unsaturated light hydrocarbons. A heavy hydrocarbonaceous oil is first coked in a fluidized bed coking zone. The vaporous conversion product is passed to a dilute phase. High temperature cracking in the presence of steam is carried out on the vaporous coker conversion product by injecting into the vapors a stream of hot coke particles at a sufficient temperature and in sufficient amount to raise the coker vapors to steam cracking temperature and supply the endothermic heat of reaction. Solids are separated from product gas in a gas-solids separation zone such as one or more cyclones and sent to the fluid coking zone and the gas is quenched to stop olefin degradation reactions. According to the improvement, relatively low temperature steam is introduced into contact with the separated solids to superheat the steam and cool the solids. Suitably this is effected in a riser on the cyclone dipleg. The solids, after having given up heat to the steam, pass into the coking zone and the superheated steam passes into the dilute phase and serves as part of the dilution steam therefor. Conservation of fuel and mitigation of coke on reactor walls and equipment are advantages of the process.

Oldweiler, M.E.

1983-10-25T23:59:59.000Z

452

Steady-State Propagation of a Mode II Crack in Couple Stress Elasticity  

E-Print Network (OSTI)

The present work deals with the problem of a semi-infinite crack steadily propagating in an elastic body subject to plane-strain shear loading. It is assumed that the mechanical response of the body is governed by the theory of couple-stress elasticity including also micro-rotational inertial effects. This theory introduces characteristic material lengths in order to describe the pertinent scale effects that emerge from the underlying microstructure and has proved to be very effective for modeling complex microstructured materials. It is assumed that the crack propagates at a constant sub-Rayleigh speed. An exact full field solution is then obtained based on integral transforms and the Wiener-Hopf technique. Numerical results are presented illustrating the dependence of the stress intensity factor and the energy release rate upon the propagation velocity and the characteristic material lengths in couple-stress elasticity. The present analysis confirms and extends previous results within the context of couple-stress elasticity concerning stationary cracks by including inertial and micro-inertial effects.

P. A. Gourgiotis; A. Piccolroaz

2014-05-13T23:59:59.000Z

453

Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an AL-Zn-Mg-(Cu) Alloy  

SciTech Connect

Precipitation hardenable Al-Zn-Mg alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are used to increase HEAC resistance at the expense of strength but overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). Results show that overaging the copper bearing alloys both inhibits hydrogen ingress from oxide covered surfaces and decreases the apparent hydrogen diffusion rates in the metal.

G.A. Young; J.R. Scully

2002-04-09T23:59:59.000Z

454

Gasoline conversion: reactivity towards cracking with equilibrated FCC and ZSM-5 catalysts  

Science Journals Connector (OSTI)

Cracking of a straight-run FCC gasoline using either a steamed ZSM-5 catalyst or a base, FCC equilibrium, catalyst shows that the only significantly reactive components in the gasoline fraction are normal and branched olefins with a carbon number of seven and higher. Overall, the reactivity of gasoline is one to two orders of magnitude smaller than that of a normal FCC feedstock. The ZSM-5 catalyst produces light olefins (LPG-range and some ethene) through cracking of the gasoline-range olefins. The base catalyst produces these light olefins in lower amounts than ZSM-5 does. Further, the base catalyst produces small amounts of paraffins and products that are heavier than the gasoline feedstock. The overall reason for the differences between the two catalysts is a shape-selective mechanism; in the small pores of ZSM-5 only monomolecular cracking reactions take place, while in the larger pores of the FCC base catalyst also a bimolecular reaction mechanism is operative. As a result of the absence of bimolecular reactions, with ZSM-5, the average size of the products and the amount of hydrogen transfer products is smaller than with the base catalyst. On the other hand, because of the relatively small pore size of ZSM-5, the interaction between the catalytic surface of ZSM-5 and the reactants is larger resulting in a higher conversion of linear olefins and a higher production of ethene than with the base catalyst.

M.A. den Hollander; M. Wissink; M. Makkee; J.A. Moulijn

2002-01-01T23:59:59.000Z

455

Microstructural and Microchemical Characterization of Dual Step Aged Alloy X-750 and its Relationship to Environmentally Assisted Cracking  

SciTech Connect

When exposed to deaerated high purity water, Alloy X-750 is susceptible to both high temperature (> 249 C) intergranular stress corrosion cracking (IGSCC) and intergranular low temperature (< 149 C) fracture (LTF). However, the microstructural and microchemical factors that govern environmentally assisted cracking (EAC) susceptibility are poorly understood. The present study seeks to characterize the grain boundary microstructure and microchemistry in order to gain a better mechanistic understanding of stress corrosion crack initiation, crack growth rate, and low temperature fracture. Light microscopy, scanning electron microscopy, transmission electron microscopy, orientation imaging microscopy, scanning Auger microscopy, and thermal desorption spectroscopy were performed on selected heats of Alloy X-750 AH. These data were correlated to EAC tests performed in 338 C deaerated water. Results show that grain boundary MC-type [(Ti,Nb)C] carbides and increased levels of grain boundary phosphorus correlate with an increase in LTF susceptibility but have little effect on the number of initiation sites or the SCC crack growth rate. Thermal desorption data show that multiple hydrogen trapping states exist in Alloy X-750 condition AH. Moreover, it appears that exposure to high temperature (> 249 C), hydrogen deaerated water increases the hydrogen concentration in strong hydrogen trap states and degrades the resistance of the material to low temperature fracture. These findings are consistent with a hydrogen embrittlement based mechanism of LTF where intergranular fracture occurs ahead of a crack tip and is exacerbated by phosphorus segregation to grain boundaries and grain boundary hydrogen trap states.

G.A. Young; N. Lewis; M. Hanson; W. Matuszyk; B. Wiersma; S. Gonzalez

2001-05-08T23:59:59.000Z

456

Different process schemes for converting light straight run and fluid catalytic cracking naphthas in a FCC unit for maximum propylene production  

Science Journals Connector (OSTI)

Light straight run (LSR) and fluid catalytic cracking (FCCN) naphthas were cracked in a transported bed reactor (MicroDowner) and in a fixed bed reactor (MAT) over a commercial Y zeolite based catalyst, over a commercial ZSM-5 zeolite based additive, and over a mixture of both at selected conditions. Based on the mechanisms through which naphtha hydrocarbons are converted, we evaluated the best alternatives for processing these streams to produce light olefins and/or to reduce olefins content in commercial gasoline. The experimental set-up allowed us to simulate the cracking behaviour of the different naphtha streams in a fluid catalytic cracking (FCC) unit by different processing schemes. Results indicate that LSR only cracks at high severity, yielding large amounts of dry gas. Despite its high olefins content, FCCN practically does not crack when it is fed together with gas oil feed. When cracking FCCN alone at typical gas oil cracking conditions, olefins are transformed preferentially into naphtha-range isoparaffins and aromatics, and when cracking FCCN at high severity, olefins are transformed preferentially into propylene and butylenes. Finally, cracking naphtha in the stripper produces some propylene and increases the aromatics in the remaining gasoline.

Avelino Corma; FranciscoV Melo; Laurent Sauvanaud; F.J Ortega

2004-01-01T23:59:59.000Z

457

Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy  

SciTech Connect

It is well established that Al-Zn-Mg-(Cu) aluminum alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are commonly used to increase HEAC resistance at the expense of strength. Overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). When freshly bared coupons of AA 7050 are exposed to 90 C, 90% RH air, hydrogen ingress follows inverse-logarithmic-type kinetics and is equivalent for underaged (HEAC susceptible) and overaged (HEAC resistant) tempers. However, when the native oxide is allowed to form (24 hrs in 25 C, 40% RH lab air) prior to exposure to 90 C, 90% RH air, underaged alloy shows significantly greater hydrogen ingress than the overaged alloy. Humid air is a very aggressive environment producing local ({approx}1{micro}m) hydrogen concentrations in excess of 10,000 wt. ppm at 90 C. In the copper bearing alloy, overaging also effects the apparent diffusivity of hydrogen. As AA 7050 is aged from underaged {yields} peak aged {yields} overaged, the activation energy for hydrogen diffusion increases and the apparent diffusivity for hydrogen decreases, In the low copper alloy, overaging has little effect on hydrogen diffusion. Comparison of the apparent activation energies for hydrogen diffusion and for K independent (stage II) crack growth rate in 90% RH air between 25 and 90 C indicates that hydrogen transport kinetics are responsible for the decreased crack growth rate of overaged AA 7050 relative to the peak aged temper.

G.A. Young; J.R. Scully

2001-09-12T23:59:59.000Z

458

Conceptual design and comparison of aramid and polyester taut leg spread moorings for deepwater applications  

SciTech Connect

As the offshore industry looks beyond water depths of 3,000 ft for future oil and gas production, the industry standard steel catenary spread mooring (CSM) system used on all floating production systems installed to date becomes increasingly inefficient and costly. An alternative to the CSM is the Taut Leg Spread Mooring (TLSM) system with its characteristic short scope legs and vertically loaded anchors. In water depths greater than 3,000 ft, it has been shown that TLSMs comprised of synthetic mooring lines have performance advantages over systems utilizing steel wire rope and demonstrated potential for significant cost reductions. Early studies investigated the use of aramid fiber rope due to its high strength, lower in-water weight and lower axial stiffness as compared to ropes made from steel. Later studies indicated that the material properties of polyester fiber, primarily its lower Young`s modulus, made polyester mooring lines more suitable for use in TLSMs. As the TLSM knowledge base expanded, aramid rope construction evolved. Earlier efforts to match the characteristics of steel wire rope have given way to new generation soft aramid constructions. This paper compares the mooring performance and total installed cost of a soft aramid TLSM to a typical polyester configuration. Both systems were designed for use in the Gulf of Mexico (GOM) with an FPS based on the Aker P45.

Wilde, B.; Kelly, P.; Librino, F.; Whitehill, A.S.

1996-12-31T23:59:59.000Z

459

Low power implementation of audio watermarking using chirp spread spectrum technique  

Science Journals Connector (OSTI)

There are numerous implementations of software-based audio watermarking available, but the implementation of hardware-based audio watermarking helps to achieve real time performance by integrating an audio watermarking chip with an existing audio electronic device. For the secure communication of the secret messages and for the data protection, the watermarking should provide good imperceptibility, good robustness, high capacity (pay load) and high speed. Thus, this paper presents a new VLSI architecture to implement an audio watermarking using chirp spread spectrum technique. It uses a chirp signal as a secret key; the watermark message can be transmitted as a noise signal such that an intruder cannot retrieve the message which is transmitted, and the message can be retrieved at the receiver side only with the help of the secret key. This technique provides high security with a low power and less complexity and it is very difficult to detect and intercept, hence it is used for the application of military and wireless communication to provide a covert communication. To our knowledge, we are the first authors to propose the low power implementation of audio watermarking using spread spectrum technique.

P. Karthigaikumar; K. Baskaran; K. Jaraline Kirubavathy

2011-01-01T23:59:59.000Z

460

Thermonuclear Flame Spreading on Rapidly Spinning Neutron Stars: Indications of the Coriolis Force?  

E-Print Network (OSTI)

Millisecond period brightness oscillations during the intensity rise of thermonuclear X-ray bursts are likely caused by an azimuthally asymmetric, expanding burning region on the stellar surface. The time evolution of the oscillation amplitude during the intensity rise encodes information on how the thermonuclear flames spread across the stellar surface. This process depends on properties of the accreted burning layer, surface fluid motions, and the surface magnetic field structure, and thus can provide insight into these stellar properties. We present two examples of bursts from different sources that show a decrease in oscillation amplitude during the intensity rise. Using theoretical modeling, we demonstrate that the observed amplitude evolution of these bursts is not well described by a uniformly expanding circular burning region. We further show that by including in our model the salient aspects of the Coriolis force (as described by Spitkovsky, Levin, and Ushomirsky) we can qualitatively reproduce the observed evolution curves. Our modeling shows that the evolutionary structure of burst oscillation amplitude is sensitive to the nature of flame spreading, while the actual amplitude values can be very useful to constrain some source parameters.

Sudip Bhattacharyya; Tod E. Strohmayer

2007-08-27T23:59:59.000Z

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461

Photon data shed new light upon the GDR spreading width in heavy nuclei  

E-Print Network (OSTI)

A global study of the electric dipole strength in and below the isovector giant dipole resonance (GDR) is presented for mass numbers A>80. It relies on the recently established remarkably good match between data for the nuclear photo effect to novel photon scattering data covering the region below the neutron emission threshold as well as by average resonance neutron capture (ARC). From the wide energy coverage of these data the correlation of the GDR spreading width with energy can be studied with remarkable accuracy. A clear sensitivity to details of the nuclear shape, i.e. the beta- and gamma-deformations, is demonstrated. Based hereon a new parameterization of the energy dependence of the nuclear electric-dipole strength is proposed which - with only two new parameters - allows to describe the dipole strength in all heavy nuclei with A>80. Although it differs significantly from previous parameterizations it holds for spherical, transitional, triaxial and well deformed nuclei. The GDR spreading width depends in a regular way on the respective resonance energy, but it is independent of the photon energy.

A. R. Junghans; G. Rusev; R. Schwengner; A. Wagner; E. Grosse

2008-10-13T23:59:59.000Z

462

Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material  

SciTech Connect

Stress corrosion cracking is one of the most common corrosion-related causes for premature breach of metal structural components. Stress corrosion cracking is the initiation and propagation of cracks in structural components due to three factors that must be present simultaneously: metallurgical susceptibility, critical environment, and static (or sustained) tensile stresses. This report was prepared according to ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of this report is to provide an evaluation of the potential for stress corrosion cracking of the engineered barrier system components (i.e., the drip shield, waste package outer barrier, and waste package stainless steel inner structural cylinder) under exposure conditions consistent with the repository during the regulatory period of 10,000 years after permanent closure. For the drip shield and waste package outer barrier, the critical environment is conservatively taken as any aqueous environment contacting the metal surfaces. Appendix B of this report describes the development of the SCC-relevant seismic crack density model (SCDM). The consequence of a stress corrosion cracking breach of the drip shield, the waste package outer barrier, or the stainless steel inner structural cylinder material is the initiation and propagation of tight, sometimes branching, cracks that might be induced by the combination of an aggressive environment and various tensile stresses that can develop in the drip shields or the waste packages. The Stainless Steel Type 316 inner structural cylinder of the waste package is excluded from the stress corrosion cracking evaluation because the Total System Performance Assessment for License Application (TSPA-LA) does not take credit for the inner cylinder. This document provides a detailed description of the process-level models that can be applied to assess the performance of Alloy 22 (used for the waste package outer barrier) and Titanium Grade 7 (used for the drip shield) that are subjected to the effects of stress corrosion cracking. The use of laser peening or other residual stress mitigation techniques is considered as a means of mitigating stress corrosion cracking in the waste package final closure lid weld.

G. Gordon

2004-10-13T23:59:59.000Z

463

Application of modeling of the texture dependence of environmentally assisted crack growth of long and short cracks to ZIRCALOY fuel tubing  

SciTech Connect

Argon and iodine stress-rupture tests were performed on five lots of ZIRCALOY-4 tubing with relatively large differences in texture. The addition of iodine relative to argon decreases the failure time. The iodine data exhibited increasing failure times with decreasing stress until a plateau or threshold stress level was reached. The threshold stress was used to evaluate a model developed from fracture mechanics crack propagation data. Modification of this model was necessary in order to account for tubing texture, tubing fracture surface characteristics, test temperature, and the embrittling effect of iodine. The adjusted model predicts that moderate increases in the iodine threshold stress may be obtained with very low tangential texture tubing.

Foster, J.P.; Comstock, R.J. (Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center)

1989-10-01T23:59:59.000Z

464

Thermally activated dislocation creep model for primary water stress corrosion cracking of NiCrFe alloys  

SciTech Connect

There is a growing awareness that awareness that environmentally assisted creep plays an important role in integranular stress corrosion cracking (IGSCC) of NiCrFe alloys in the primary coolant water environment of a pressurized water reactor (PWR). The expected creep mechanism is the thermally activated glide of dislocations. This mode of deformation is favored by the relatively low temperature of PWR operation combined with the large residual stresses that are most often identified as responsible for the SCC failure of plant components. Stress corrosion crack growth rate (CGR) equations that properly reflect the influence of this mechanism of crack tip deformation are required for accurate component life predictions. A phenomenological IGSCC-CGR model, which is based on an apriori assumption that the IGSCC-CGR is controlled by a low temperature dislocation creep mechanism, is developed in this report. Obstacles to dislocation creep include solute atoms such as carbon, which increase the lattice friction force, and forest dislocations, which can be introduced by cold prestrain. Dislocation creep also may be environmentally assisted due to hydrogen absorption at the crack tip. The IGSCC-CGR model developed here is based on an assumption that crack growth occurs by repeated fracture events occurring within an advancing crack-tip creep-fracture zone. Thermal activation parameters for stress corrosion cracking are obtained by fitting the CGR model to IGSCC-CGR data obtained on NiCrFe alloys, Alloy X-750 and Alloy 600. These IGSCC-CGR activation parameters are compared to activation parameters obtained from creep and stress relaxation tests. Recently reported CGR data, which exhibit an activation energy that depends on yield stress and the applied stress intensity factor, are used to benchmark the model. Finally, the effects of matrix carbon concentration, grain boundary carbides and absorbed hydrogen concentration are discussed within context of the model.

Hall, M.M., Jr

1995-12-31T23:59:59.000Z

465

Product Price Spreads Over Crude Oil Vary With Seasons and Supply/Demand  

Gasoline and Diesel Fuel Update (EIA)

6 6 Notes: Of course, petroleum product prices don't move in lockstep to crude oil prices, for a number of reasons. We find it useful to look at variations in the spread between product and crude oil prices, in this case comparing spot market prices for each. The difference between heating oil and crude oil spot prices tends to vary seasonally; that is, it's generally higher in the winter, when demand for distillate fuels is higher due to heating requirements, and lower in the summer. (Gasoline, as we'll see later, generally does the opposite.) However, other factors affecting supply and demand, including the relative severity of winter weather, can greatly distort these "typical" seasonal trends. As seen on this chart, the winters of 1995-96 and 1996-97 featured

466

Nuclear fuel reprocessing and the problems of safeguarding against the spread of nuclear weapons  

SciTech Connect

In 1977, the executive branch reversed its long-standing support for nuclear fuel reprocessing, primarily because of the rick of spreading nuclear weapons. GAO reviewed safeguards technology designed to reduce such risks in Federal reprocessing facilities and found that concerns are warranted. Material in sufficient quantities to construct a nuclear weapon could be diverted and go undetected for a long time. Effective international control and safeguards over the production, storage, and use of separated plutonium are lacking. The United States should increase its efforts to: develop and ensure the use of effective safeguards for reprocessing facilities; and establish, in conjunction with major nuclear fuel users, suppliers, and reprocessors, an international system to control the storage and use of excess plutonium.

Staats, E.B.

1980-03-18T23:59:59.000Z

467

Similarity solutions and applications to turbulent upward flame spread on noncharring materials  

SciTech Connect

The primary achievement in this work has been the discovery that turbulent upward flame spread on noncharring materials (for pyrolysis lengths less than 1.8m) can be directly predicted by using measurable flammability parameters. These parameters are: a characteristic length scale which is proportional to a turbulent combustion and mixing related length scale parameter ({dot q}{double_prime}{sub net}({Delta}H{sub c}/{Delta}H{sub v})){sup 2}, a pyrolysis or ignition time {tau}{sub p}, and a parameter which determines the transient pyrolysis history of a non-charring material: {lambda} = L/c{Delta}T{sub p} = ratio of the latent heat to the sensible heat of the pyrolysis temperature of the material. In the length scale parameter, {dot q}{double_prime}{sub net} is the total net heat flux from the flames to the wall (i.e., total heat flux minus reradiation losses), {Delta}H{sub c} is the heat of combustion and {Delta}H{sub v} is an effective heat of gasification for the material. The pyrolysis or ignition time depends (for thermally thick conditions) on the material thermal inertia, the pyrolysis temperature, and the total heat flux from the flames to the wall, {dot q}{double_prime}{sub fw}. The present discovery was made possible by using both a numerical simulation, developed earlier, and exact similarity solutions, which are developed in this work. The predictions of the analysis have been validated by comparison with upward flame spread experiments on PMMA.

Delichatsios, M.A.; Delichatsios, M.; Chen, Y. [Factory Mutual Research Corporation, Norwood, MA (United States)] [Factory Mutual Research Corporation, Norwood, MA (United States); Hasemi, Y. [Ministry of Construction, Tsukuba (Japan). Building Research Inst.] [Ministry of Construction, Tsukuba (Japan). Building Research Inst.

1995-08-01T23:59:59.000Z

468

Effect of aging of the pillaring reagent on the microstructure and cracking activity of pillared clay  

SciTech Connect

Pillared interlayer clay (PILC) is formed by exchanging large hydroxyaluminum polycations into the interlayer of a smectite clay such as montmorillonite, which is made up of sheet-like silica/alumina layers. Calcination of the exchanged clay gives a well dispersed array of metal oxide clumps (i.e., pillars) bonded top and bottom to the silica/alumina layers of the clay. The permanent separation of the clay layers gives an 8 to 10-fold increase in surface area, from 30 to 250-300 m{sup 2}/g, and a microporous structure similar to but less constrained than that of zeolites. Recently, there has been an increased interest in the use of these clays as cracking catalysts. For example, pillared clays have been shown to be an active cracking catalyst for both single component and gas oil feeds. PILC's also lead to both higher light cycle oil (LCO) and coke yields than conventional cracking catalysts. Commercially available, metal-hydrolyzed hydroxyaluminum solutions containing chlorhydrol, A1{sub 2}(OH){sub 5}C1.2H{sub 2}O, have been used as one source of the polycation solution. The approach of these hydrolyzed polycation solutions to equilibrium is known as aging. During the aging process certain polycationic species disappear from the solution and new species are formed. For this reason, the aging process can have a significant influence on the properties of the pillared clays. The objective of this work was to determine how the physical and catalytic properties of the pillared clay depend on the aging of dilute cholorhydrol solutions.

Harris, J.R. (Phillips Petroleum Company, Bartlesville, OK (USA))

1987-08-01T23:59:59.000Z

469

Pacific Northwest National Laboratory Investigation of the Stress Corrosion Cracking in Nickel-Base Alloys, Volume 2  

SciTech Connect

The objective of this program is to evaluate the primary water stress corrosion cracking (PWSCC) susceptibility of high chromium alloy 690 and its weld metals, establish quantitative measurements of crack-growth rates and determine relationships among cracking susceptibility, environmental conditions and metallurgical characteristics. Stress-corrosion, crack-growth rates have been determined for 12 alloy 690 specimens, 11 alloy 152/52/52M weld metal specimens, 4 alloy 52M/182 overlay specimens and 2 alloy 52M/82 inlay specimens in simulated PWR primary water environments. The alloy 690 test materials included three different heats of extruded control-rod-drive mechanism (CRDM) tubing with variations in the initial material condition and degree of cold work for one heat. Two cold-rolled (CR) alloy 690 plate heats were also obtained and evaluated enabling comparisons to the CR CRDM materials. Weld metal, overlay and inlay specimens were machined from industry mock ups to provide plant-representative materials for testing. Specimens have been tested for one alloy 152 weld, two alloy 52 welds and three alloy 52M welds. The overlay and inlay specimens were prepared to propagate stress-corrosion cracks from the alloy 182 or 82 material into the more resistant alloy 52M. In all cases, crack extension was monitored in situ by direct current potential drop (DCPD) with length resolution of about +1 µm making it possible to measure extremely low growth rates approaching 5x10-10 mm/s. Most SCC tests were performed at 325-360°C with hydrogen concentrations from 11-29 cc/kg; however, environmental conditions were modified during a few experiments to evaluate the influence of temperature, water chemistry or electrochemical potential on propagation rates. In addition, low-temperature (~50°C) cracking behavior was examined for selected alloy 690 and weld metal specimens. Extensive characterizations have been performed on material microstructures and stress-corrosion cracks by optical and electron microscopy techniques and linked to crack-growth test results to help define material and environmental parameters controlling SCC susceptibility.

Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.

2012-03-01T23:59:59.000Z

470

Irradiation-assisted stress corrosion cracking of materials from commercial BWRs: Role of grain-boundary microchemistry  

SciTech Connect

Constant-extension-rate tensile tests and grain-boundary analysis by Auger electron spectroscopy which were conducted on high- and commercial-purity (HP and CP) Type 304 stainless steel (SS) specimens from irradiated boiling-water reactor (BWR) components to determine susceptibility to irradiation-assisted stress corrosion cracking (IASCC) and to identify the mechanisms of intergranular failure. The susceptibility of HP neutron absorber tubes to intergranular stress corrosion cracking (IGSCC) was higher than that of CP absorber tubes or CP control blade sheath. Contrary to previous beliefs, susceptibility to intergranular fracture could not be correlated with radiation-induced segregation of impurities such as Si, P, C, N, or S, but a correlation was obtained with grain-boundary Cr concentration, indicating a role for Cr depletion that promotes IASCC. Detailed analysis of grain-boundary chemistry was conducted on neutron absorber tubes that were fabricated from two similar heats of HP Type 304 SS of virtually identical bulk chemical composition but exhibiting a significant difference in susceptibility to IGSCC for similar fluence. Grain-boundary concentrations of Cr, Ni, Si, P, S, and C in the crack-resistant and susceptible HP heats were virtually identical. However, grain boundaries of the cracking-resistant material contained less N and more B and Li (transmutation product from B) than those of the crack-susceptible material, indicating beneficial effects of low N and high B contents.

Chung, H.M.; Ruther, W.E.; Sanecki, J.E.; Hins, A.G.; Kassner, T.F.

1993-12-01T23:59:59.000Z

471

The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water  

SciTech Connect

Grain boundary chromium carbides improve the resistance of nickel based alloys to primary water stress corrosion cracking (PWSCC). However, in weld heat affected zones (HAZ's), thermal cycles from fusion welding can solutionize beneficial grain boundary carbides, produce locally high residual stresses and strains, and promote PWSCC. The present research investigates the crack growth rate of an A600 HAZ as a function of test temperature. The A600 HAZ was fabricated by building up a gas-tungsten-arc-weld deposit of EN82H filler metal onto a mill-annealed A600 plate. Fracture mechanics based, stress corrosion crack growth rate testing was performed in high purity water between 600 F and 680 F at an initial stress intensity factor of 40 ksi {radical}in and at a constant electrochemical potential. The HAZ samples exhibited significant SCC, entirely within the HAZ at all temperatures tested. While the HAZ samples showed the same temperature dependence for SCC as the base material (HAZ: 29.8 {+-} 11.2{sub 95%} kcal/mol vs A600 Base: 35.3 {+-} 2.58{sub 95%} kcal/mol), the crack growth rates were {approx} 30X faster than the A600 base material tested at the same conditions. The increased crack growth rates of the HAZ is attributed to fewer intergranular chromium rich carbides and to increased plastic strain in the HAZ as compared to the unaffected base material.

George A. Young; Nathan Lewis

2003-04-05T23:59:59.000Z

472

Developing Fatigue Pre-crack Procedure to Evaluate Fracture Toughness of Pipeline Steels Using Spiral Notch Torsion Test  

SciTech Connect

The spiral notch torsion test (SNTT) has been utilized to investigate the crack growth behavior of X52 steel base and welded materials used for hydrogen infrastructures. The X52 steel materials are received from a welded pipe using friction stir welding techniques. Finite element models were established to study the crack growth behavior of steel SNTT steel samples, which were assumed to be isotropic material. A series SNTT models were set up to cover various crack penetration cases, of which the ratios between crack depth to diameter (a/D ratio) ranging from 0.10 to 0.45. The evolution of compliance and energy release rates in the SNTT method have been investigated with different cases, including different geometries and materials. Indices of characteristic compliance and energy release rates have been proposed. Good agreement has been achieved between predictions from different cases in the same trend. These work shed lights on a successful protocol for SNTT application in wide range of structural materials. The further effort needed for compliance function development is to extend the current developed compliance function to the deep crack penetration arena, in the range of 0.55 to 0.85 to effectively determine fracture toughness for extremely tough materials.

Wang, Jy-An John [ORNL; Tan, Ting [ORNL; Jiang, Hao [ORNL; Zhang, Wei [ORNL; Feng, Zhili [ORNL

2012-10-01T23:59:59.000Z

473

The role of hydrogen in the stress corrosion cracking of titanium alloys  

Science Journals Connector (OSTI)

Work with Ti?8A1?1Mo?1V has shown that the susceptibility of this alloy to stress corrosion cracking (SCC) in dilute saline solution is dependent on the hydrogen content of the material. Progressive removal of hydrogen results in increasing Kie and Kisec until at about the 5 ppm level the material shows immunity to SCC. Addition of hydrogen also raises the level of the fracture toughness values of the material when tested in air or saline, but does not confer immunity to SCC. Removal of hydrogen has a similar effect on the fracture toughness properties of Ti?6A1?4V.

S. Orman; G. Picton

1974-01-01T23:59:59.000Z

474

Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate  

SciTech Connect

Eddy current nondestructive evaluation (NDE) is usually carried out by exciting a time harmonic field using an inductive probe. However, a viable alternative is to use transient eddy current NDE in which a current pulse in a driver coil produces a transient .eld in a conductor that decays at a rate dependent on the conductivity and the permeability of the material and the coil configuration. By using transient eddy current, it is possible to estimate the properties of the conductive medium and to locate and size potential .aws from the measured probe response. The fundamental study described in this dissertation seeks to establish a theoretical understanding of the transient eddy current NDE. Compared with the Fourier transform method, the derived analytical formulations are more convenient when the transient eddy current response within a narrow time range is evaluated. The theoretical analysis provides a valuable tool to study the effect of layer thickness, location of defect, crack opening as well as the optimization of probe design. Analytical expressions have been developed to evaluate the transient response due to eddy currents in a conductive plate based on two asymptotic series. One series converges rapidly for a short time regime and the other for a long time regime and both of them agree with the results calculated by fast Fourier transform over all the times considered. The idea of asymptotic expansion is further applied to determine the induced electromotive force (EMF) in a pick-up coil due to eddy currents in a cylindrical rod. Starting from frequency domain representation, a quasi-static time domain dyadic Green's function for an electric source in a conductive plate has been derived. The resulting expression has three parts; a free space term, multiple image terms and partial reflection terms. The dyadic Green's function serves as the kernel of an electric field integral equation which defines the interaction of an ideal crack with the transient eddy currents in a conductive plate. The crack response is found using the reciprocity theorem. Good agreement is observed between the predictions of the magnetic field due to the crack and experimental measurements.

Fangwei Fu

2006-08-09T23:59:59.000Z

475

Effect of Syngas Addition on Lower Alkene Production by the Oxidative Cracking of Hexane  

Science Journals Connector (OSTI)

For the COC of C6 with added syngas, the mechanism of exothermic heterogeneous combustion reactions (e.g., H2?O2 catalytic combustion), followed by endothermic homogeneous pyrolysis reaction of C6, is supposed, in which lower alkenes are produced in the gas-phase cracking of C6, using the heat generated from heterogeneously catalytic combustion reactions. ... Both Sn/SiO2 and PtSn/SiO2 seem to be able to selectively combust hydrogen in a gas mixt. ...

Haiou Zhu; Xuebin Liu; Wenzhao Li; Qingjie Ge; Hengyong Xu

2005-04-21T23:59:59.000Z

476

Influence of nondestructive test procedures on detection of stress-corrosion cracks  

SciTech Connect

A weld T joint from a scrapped carbon-steel digester level tank was used to test the efficacy of the nondestructive liquid-penetrant and magnetic-particle test methods commonly used for field detection of stress-corrosion cracks. The tests were conducted using three methods of surface preparation--wire brushing, light grinding, and sandblasting. Light grinding of the surface greatly increased the sensitivity of both the liquid-penetrant and magnetic-particle test methods. The most successful combination was light surface grinding followed by inspection with a fluorescent liquid.

Reid, J.C. (Industrial Nondestructive Testing Ltd., Burnaby, British Columbia (Canada)); Reid, D.C. (MacMillan Bloedel Ltd., Burnaby, British Columbia (Canada))

1993-08-01T23:59:59.000Z

477

Low cycle fatigue crack initiation life assessment of HY-100 undermatched weld  

SciTech Connect

An evaluation is conducted of several approaches to the prediction of low cycle fatigue crack initiation in HY-100 welds of an undermatched weldment. FEM analyses and experiments using various types of low cycle fatigue specimens were conducted and their results were compared with the results of such theoretical algorithms as Neuber's rule. A two-surface cyclic plasticity algorithm was implanted in a FEM code's user subroutine in order to simulate the material's cyclic stress-strain behavior under cyclic loading conditions; fatigue tests ranging from small, standard smooth specimens to notched cylindrical specimens with notch constraint were conducted for HY-100. 11 refs.

Wang, K.; Shah, R.; Yuan, D.; Kleinosky, M.J.

1993-01-01T23:59:59.000Z

478

Derivation of a crack opening deflection relationship for fibre reinforced concrete panels using a stochastic model: Application for predicting the flexural behaviour of round panels using stress crack opening diagrams  

SciTech Connect

This study is aimed at proposing a simple analytical model to investigate the post-cracking behaviour of FRC panels, using an arbitrary tension softening, stress crack opening diagram, as the input. A new relationship that links the crack opening to the panel deflection is proposed. Due to the stochastic nature of material properties, the random fibre distribution, and other uncertainties that are involved in concrete mix, this relationship is developed from the analysis of beams having the same thickness using the Monte Carlo simulation (MCS) technique. The softening diagrams obtained from direct tensile tests are used as the input for the calculation, in a deterministic way, of the mean load displacement response of round panels. A good agreement is found between the model predictions and the experimental results.

Nour, Ali, E-mail: ali.nour@polymtl.ca [Civil, Geological, and Mining Engineering Department, Ecole Polytechnique of Montreal, P.O. Box 6079, Station Centre-ville, Montreal, Quebec, H3C 3A7 (Canada); Hydro Quebec, Montreal, Quebec, H2L 4P5 (Canada); Massicotte, Bruno; De Montaignac, Renaud; Charron, Jean-Philippe [Civil, Geological, and Mining Engineering Department, Ecole Polytechnique of Montreal, P.O. Box 6079, Station Centre-ville, Montreal, Quebec, H3C 3A7 (Canada)

2011-09-15T23:59:59.000Z

479

Status report: Intergranular stress corrosion cracking of BWR core shrouds and other internal components  

SciTech Connect

On July 25, 1994, the US Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 94-03 to obtain information needed to assess compliance with regulatory requirements regarding the structural integrity of core shrouds in domestic boiling water reactors (BWRs). This report begins with a brief description of the safety significance of intergranular stress corrosion cracking (IGSCC) as it relates to the design and function of BWR core shrouds and other internal components. It then presents a brief history of shroud cracking events both in the US and abroad, followed by an indepth summary of the industry actions to address the issue of IGSCC in BWR core shrouds and other internal components. This report summarizes the staff`s basis for issuing GL 94-03, as well as the staff`s assessment of plant-specific responses to GL 94-03. The staff is continually evaluating the licensee inspection programs and the results from examinations of BWR core shrouds and other internal components. This report is representative of submittals to and evaluations by the staff as of September 30, 1995. An update of this report will be issued at a later date.

NONE

1996-03-01T23:59:59.000Z

480

Effect of material heat treatment on fatigue crack initiation in austenitic stainless steels in LWR environments.  

SciTech Connect

The ASME Boiler and Pressure Vessel Code provides rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify design curves for applicable structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. The existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives of austenitic stainless steels (SSs) can be a factor of 20 lower in water than in air. This report presents experimental data on the effect of heat treatment on fatigue crack initiation in austenitic Type 304 SS in LWR coolant environments. A detailed metallographic examination of fatigue test specimens was performed to characterize the crack morphology and fracture morphology. The key material, loading, and environmental parameters and their effect on the fatigue life of these steels are also described. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic SSs as a function of material, loading, and environmental parameters. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented.

Chopra, O. K.; Alexandreanu, B.; Shack, W. J.; Energy Technology

2005-07-31T23:59:59.000Z

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481

Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.  

SciTech Connect

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of fatigue crack initiation in austenitic stainless steels in LWR coolant environments. The existing fatigue {var_epsilon}-N data have been evaluated to establish the effects of key material, loading, and environmental parameters (such as steel type, strain range, strain rate, temperature, dissolved-oxygen level in water, and flow rate) on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. The influence of reactor environments on the mechanism of fatigue crack initiation in these steels is also discussed.

Chopra, O. K.; Energy Technology

2002-08-01T23:59:59.000Z

482

Matrix fatigue cracking mechanisms of alpha(2) TMC for hypersonic applications  

SciTech Connect

The objective of this work was to understand matrix cracking mechanisms in a unidirectional alpha[sub 2] TMC in possible hypersonic applications. A (0)[sub 8] SCS-6/Ti-24Al-11Nb (at. percent) TMC was first subjected to a variety of simple isothermal and nonisothermal fatigue cycles to evaluate the damage mechanisms in simple conditions. A modified ascent mission cycle test was then performed to evaluate the combined effects of loading modes. This cycle mixes mechanical cycling at 150 and 483 C, sustained loads, and a slow thermal cycle to 815 C. At low cyclic stresses and strains more common in hypersonic applications, environment-assisted surface cracking limited fatigue resistance. This damage mechanism was most acute for out-of-phase nonisothermal cycles having extended cycle periods and the ascent mission cycle. A simple linear fraction damage model was employed to help understand this damage mechanism. Time-dependent environmental damage was found to strongly influence out-of-phase and mission life, with mechanical cycling damage due to the combination of external loading and CTE mismatch stresses playing a smaller role. The mechanical cycling and sustained loads in the mission cycle also had a smaller role.

Gabb, T.P.; Gayda, J.

1994-02-01T23:59:59.000Z

483

Matrix fatigue cracking in {alpha}{sub 2} titanium matrix composites for hypersonic applications  

SciTech Connect

The objective of this work was to understand matrix cracking mechanisms in a unidirectional {alpha}{sub 2} titanium matrix composite (TMC) in possible hypersonic applications. A [0]{sub 8} SCS-6/Ti-24Al-11Nb (atomic %) TMC was first subjected to a variety of simple isothermal and nonisothermal fatigue cycles to evaluate the damage mechanisms in simple conditions. A modified ascent mission cycle test was then performed to evaluate the combined effects of loading modes. This cycle mixes mechanical cycling at 150 and 483 C, sustained loads, and a slow thermal cycle to 815 C. At low cyclic stresses and strains more common in hypersonic applications, environment-assisted surface cracking limited fatigue resistance. This damage mechanism was most acute for out-of-phase nonisothermal cycles having extended cycle periods and the ascent mission cycle. A simple linear fraction damage model was employed to help understand this damage mechanism. Time-dependent environmental damage was found to strongly influence out-of-phase and mission life, with mechanical cycling damage due to the combination of external loading and CTE mismatch stresses playing a smaller role. The mechanical cycling and sustained loads in the mission cycle also had a smaller role.

Gabb, T.P.; Gayda, J. [NASA Lewis Research Center, Cleveland, OH (United States)

1996-12-31T23:59:59.000Z

484

The selective catalytic cracking of Fischer-Tropsch liquids to high value transportation fuels. Final report  

SciTech Connect

Amoco Oil Company, investigated a selective catalytic cracking process (FCC) to convert the Fischer-Tropsch (F-T) gasoline and wax fractions to high value transportation fuels. The primary tasks of this contract were to (1) optimize the catalyst and process conditions of the FCC process for maximum conversion of F-T wax into reactive olefins for later production of C{sub 4}{minus}C{sub 8} ethers, and (2) use the olefin-containing light naphtha obtained from FCC processing of the F-T wax as feedstock for the synthesis of ethers. The catalytic cracking of F-T wax feedstocks gave high conversions with low activity catalysts and low process severities. HZSM-5 and beta zeolite catalysts gave higher yields of propylene, isobutylene, and isoamylenes but a lower gasoline yield than Y zeolite catalysts. Catalyst selection and process optimization will depend on product valuation. For a given catalyst and process condition, Sasol and LaPorte waxes gave similar conversions and product selectivities. The contaminant iron F-T catalyst fines in the LaPorte wax caused higher coke and hydrogen yields.

Schwartz, M.M.; Reagon, W.J.; Nicholas, J.J.; Hughes, R.D.

1994-11-01T23:59:59.000Z

485

Failure Analysis of Cracked FS-85 Tubing and ASTAR-811C End Caps  

SciTech Connect

Failure analyses were performed on cracked FS-85 tubing and ASTAR-811C and caps which had been fabricated as components of biaxial creep specimens meant to support materials testing for the NR Space program. During the failure analyses of cracked FS-85 tubing, it was determined that the failure potentially could be due to two effects: possible copper contamination from the EDM (electro-discharge machined) recast layer and/or an insufficient solution anneal. to prevent similar failures in the future, a more formal analysis should be done after each processing step to ensure the quality of the material before further processing. During machining of the ASTAR-811FC rod to form end caps for biaxial creep specimens, linear defects were observed along the center portion of the end caps. These defects were only found in material that was processed from the top portion of the ingot. The linear defects were attributed to a probable residual ingot pipe that was not removed from the ingot. During the subsequent processing of the ingot to rod, the processing temperatures were not high enough to allow self healing of the ingot's residual pipe defect. To prevent this from occurring in the future, it is necessary to ensure that complete removal of the as-melted ingot pipe is verified by suitable non-destructive evaluation (NDE).

ME Petrichek

2006-02-09T23:59:59.000Z

486

Microwave Enhanced Direct Cracking of Hydrocarbon Feedstock for Energy Efficient Production of Ethylene and Propylene.  

SciTech Connect

This project demonstrated microwave cracking of ethane with good product conversion and ethylene selectivity, with a short residence time ({approx}0.001 sec). The laboratory scale equipment was designed and built, along with concept designs for larger scale implementation. The system was operated below atmospheric pressures, in the range of 15-55 torr, with argon as a carrier gas. The measured products included hydrogen, methane, acetylene, and ethylene. The results followed similar trends to those predicted by the modeling software SPYRO{reg_sign}, with the exception that the microwave appeared to produce slightly lower amounts of ethylene and methane, although enhanced analytical analysis should reduce the difference. Continued testing will be required to verify these results and quantify the energy consumption of microwave vs. conventional. The microwave cracking process is an attractive option due to the possibility of selectively heating the reaction volume rather than the reactor walls, which may allow novel reactor designs that result in more efficient production of ethylene. Supplemental studies are needed to continue the laboratory testing and refine processing parameters.

Shulman, Holly; Fall, Morgana; Wagner, Eric; Bowlin, Ricardo

2012-02-13T23:59:59.000Z

487

What can you do to stop the flu? Cover your cough! Help stop the spread of germs by  

E-Print Network (OSTI)

What can you do to stop the flu? · Cover your cough! Help stop the spread of germs by covering your mouth and nose when you cough or sneeze with a tissue or with your upper sleeve. · Wash your hands surfaces. · Flu symptoms include: - Fever - Extreme tiredness - Headache - Cough - Muscle aches - Runny

Burke, Peter

488

Improved photovoltaic performance of InGaN/GaN solar cells with optimized transparent current spreading layers  

Science Journals Connector (OSTI)

In0.135Ga0.865N/GaN p–i–n solar cells are fabricated and investigated with three types of transparent current spreading layers (TCSLs): Ni/Au layer type (Ni/Au-L), Ni/Au grid type (Ni/Au-G), and ITO layer type (I...

X. M. Cai; Y. Wang; Z. D. Li; X. Q. Lv; J. Y. Zhang; L. Y. Ying…

2013-05-01T23:59:59.000Z

489

Morphology and segmentation of the western Galapagos Spreading Center, 90.598W: Plume-ridge interaction at  

E-Print Network (OSTI)

-ridge interaction at an intermediate spreading ridge John Sinton Department of Geology and Geophysics, University of Hawai`i, Honolulu, Hawai`i 96822, USA (sinton@hawaii.edu) Robert Detrick and J. Pablo Canales Department. Sinton, J., R. Detrick, J. P. Canales, G. Ito, and M. Behn, Morphology and segmentation of the western

Ito, Garrett

490

First Observation of the Point Spread Function of Optical Transition Radiation Pavel Karataev,1,* Alexander Aryshev,2  

E-Print Network (OSTI)

First Observation of the Point Spread Function of Optical Transition Radiation Pavel Karataev,1 Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan 3 John Adams) of optical transition radiation (OTR) performed at KEK-Accelerator Test Facility extraction line. We have

Sheldon, Nathan D.

491

A numerical model of hydrothermal cooling and crustal accretion at a fast spreading mid-ocean ridge  

E-Print Network (OSTI)

: 7360 words, 11 figures. Keywords: Mid-ocean ridge processes; hydrothermal cooling; numerical modelA numerical model of hydrothermal cooling and crustal accretion at a fast spreading mid-ocean ridge present a steady state numerical representation of the sill model that explicitly includes hydrothermal

Toomey, Doug

492

Two-dimensional nonlinear advection?diffusion in a model of surfactant spreading on a thin liquid film  

Science Journals Connector (OSTI)

......Grotberg, 1994; Halpern et al., 1998), notably as a vehicle for drug delivery. + Present address: Department of Biomedical...mathematical model for the transport and spreading of oil slicks. Ecological Model. 22, 325 - 339. O ' B RIEN, S. B. G. M 1993 On......

H. A. R. Williams; O. E. Jensen

2001-01-01T23:59:59.000Z

493

Background Model formulation Patch model SIK model Conclusions War of the Worlds: Modelling the spread of an  

E-Print Network (OSTI)

Background Model formulation Patch model SIK model Conclusions War of the Worlds: Modelling the spread of an invasive species an #12;Background Model formulation Patch model SIK model Conclusions Model formulation Patch model SIK model Conclusions Outline 1 Background 2 Model formulation Equations

Linder, Tamás

494

Effect of cracks on the thermal resistance of aligned fiber composites Department of Mechanical and Materials Engineering, University of Western Ontario, London,  

E-Print Network (OSTI)

Effect of cracks on the thermal resistance of aligned fiber composites J. Dryden Department are bridged by the fibers, and this crack- ing causes an increase in the longitudinal thermal resistance of the matrix and the fiber, respectively. The thermal resistance of a pristine unit cell is R0 L b2 kz . 4

Zok, Frank

495

I Am Crrarn Soc, 1 5 [2] 316-2r (1992) Distribution of Matrix Cracks in a Uniaxial Ceramic Composite  

E-Print Network (OSTI)

Composite Chongdu Cho,*John W. Holmes," and James R. Barber Department of Mechanical Engineering and Applied cracking and debonding in uniaxial composites loaded in tension predict that the matrix stress varies only model of a composite and by direct experimental measurements of crack spacing. In the limit

Barber, James R.