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Note: This page contains sample records for the topic "thermal cracking delayed" from the National Library of EnergyBeta (NLEBeta).
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1

Theory of delayed thermal fluorescence  

Science Journals Connector (OSTI)

A theory of nonradiative thermal activation involved in delayed thermal fluorescence has been developed from the viewpoint of the breakdown of the Born-Oppenheimer adiabatic approximation.

S. H. Lin

1971-01-01T23:59:59.000Z

2

A heavy oil thermal cracking simulation program  

SciTech Connect (OSTI)

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale  

E-Print Network [OSTI]

by the thermal cracking process of the El-Lujjan oil shale showed that the yield of oil was around 12 wt of the boiling point for different distillate fractions. Sulfur in Jordanian oil shale was found to be mainly the dominant phases in these fractions. q 2005 Published by Elsevier Ltd. 1. Introduction Oil shale

Shawabkeh, Reyad A.

11

Thermally activated dislocation creep model for primary water stress corrosion cracking of NiCrFe alloys  

SciTech Connect (OSTI)

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

12

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

13

Thermally activated low temperature creep and primary water stress corrosion cracking of NiCrFe alloys  

SciTech Connect (OSTI)

A phenomenological SCC-CGR model is developed based on an apriori assumption that the SCC-CGR is controlled by low temperature creep (LTC). This mode of low temperature time dependent deformation occurs at stress levels above the athermal flow stress by a dislocation glide mechanism that is thermally activated and may be environmentally assisted. The SCC-CGR model equations developed contain thermal activation parameters descriptive of the dislocation creep mechanism. Thermal activation parameters are obtained by fitting the CGR model to SCC-CGR data obtained on Alloy 600 and Alloy X-750. These SCC-CGR activation parameters are compared to LTC activation parameters obtained from stress relaxation tests. When the high concentration of hydrogen at the tip of an SCC crack is considered, the SCC-CGR activation energies and rate sensitivities are shown to be quantitatively consistent with hydrogen reducing the activation energy and increasing the strain rate sensitivity in LTC stress relaxation tests. Stress dependence of SCC-CGR activation energy consistent with that found for the LTC activation energy. Comparisons between temperature dependence of the SCC-CGR stress sensitivity and LTC stress sensitivity provide a basis for speculation on effects of hydrogen and solute carbon on SCC crack growth rates.

Hall, M.M. Jr.

1993-10-01T23:59:59.000Z

14

The evolution of solid density within a thermal explosion II. Dynamic proton radiography of cracking and solid consumption by burning  

SciTech Connect (OSTI)

We report proton transmission images obtained subsequent to the laser assisted thermal ignition of a sample of PBX 9501 (a plastic bonded formulation of the explosive nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)). We describe the laser assisted thermal ignition technique as a means to synchronize a non-linear thermal ignition event while preserving the subsequent post-ignition behavior. We have obtained dynamic proton transmission images at two spatial magnifications and viewed both the radial and transverse axis of a solid cylindrical sample encased in aluminum. Images have been obtained with 3 to 15 {mu}s temporal resolution and approximately 100 {mu}m spatial resolution at the higher magnification. We observe case expansion from very early in the experiment, until case fragmentation. We observe spatially anisotropic features in the transmission which we attribute to cracking in the solid explosive, in agreement with previous measurements conducted on two dimensional samples with optical viewing. Digital analysis of the images also reveals spatially isotropic features which we attribute to the evolution of the loss of density by burning subsequent to thermal ignition.

Smilowitz, L.; Henson, B. F.; Romero, J. J.; Asay, B. W.; Saunders, A.; Merrill, F. E.; Morris, C. L.; Kwiatkowski, K.; Grim, G.; Mariam, F.; Schwartz, C. L.; Hogan, G.; Nedrow, P.; Murray, M. M.; Thompson, T. N.; Espinoza, C.; Lewis, D.; Bainbridge, J.; McNeil, W.; Rightley, P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); and others

2012-05-15T23:59:59.000Z

15

Yield of delayed neutrons in the thermal-neutron-induced reaction {sup 245}Cm(n, f)  

SciTech Connect (OSTI)

The yield of delayed neutrons, v{sub d}, from thermal-neutron-induced fission of {sup 245}Cm is measured. Experiments aimed at studying the properties of delayed neutrons from the fission of some reactor isotopes and initiated in 1997 were continued at the upgraded Isomer-M facility by a method according to which a periodic irradiation of a sample with a pulsed neutron beam from the IBR-2 reactor was accompanied by recording emitted neutrons in the intervals between the pulses. The accuracy of the resulting total delayed-neutron yield v{sub d} = (0.64 {+-} 0.02)% is two times higher than that in previous measurements. This work was performed at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (JINR, Dubna).

Andrianov, V. R. [Joint Institute for Nuclear Research (Russian Federation); Vyachin, V. N. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Gundorin, N. A. [Joint Institute for Nuclear Research (Russian Federation); Druzhinin, A. A. [All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Zhdanova, K. V.; Lihachev, A. N.; Pikelner, L. B.; Rebrova, N. V.; Salamatin, I. M.; Furman, V. I. [Joint Institute for Nuclear Research (Russian Federation)

2008-10-15T23:59:59.000Z

16

Materials Science and Engineering A 490 (2008) 2635 Mechanisms of cracking and delamination within thick thermal barrier  

E-Print Network [OSTI]

. Introduction The maximum temperature capability of thermal barrier systems used in gas turbines is often that characterizes the susceptibility to delamination of thermal barrier coated (TBC) hot-section aero-turbine and sub-surface delaminations, as well as spalls. Estimates of the residual stress gradients made on cross

Hutchinson, John W.

17

Combustion in cracks of PBX 9501  

SciTech Connect (OSTI)

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

18

Cracking knuckles  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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.

19

Thermal Cracking of Higher Paraffins  

Science Journals Connector (OSTI)

The model was based on the Kossiakoff and Rice theory, that is, including the following five elementary reactions:? initiation, ... ...

H. H. Voge; G. M. Good

1949-02-01T23:59:59.000Z

20

Vehicle barrier with access delay  

DOE Patents [OSTI]

An access delay vehicle barrier for stopping unauthorized entry into secure areas by a vehicle ramming attack includes access delay features for preventing and/or delaying an adversary from defeating or compromising the barrier. A horizontally deployed barrier member can include an exterior steel casing, an interior steel reinforcing member and access delay members disposed within the casing and between the casing and the interior reinforcing member. Access delay members can include wooden structural lumber, concrete and/or polymeric members that in combination with the exterior casing and interior reinforcing member act cooperatively to impair an adversarial attach by thermal, mechanical and/or explosive tools.

Swahlan, David J; Wilke, Jason

2013-09-03T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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

The energy spectrum of delayed neutrons from thermal neutron induced fission of sup 2 sup 3 sup 5 U and its analytical approximation  

E-Print Network [OSTI]

The energy spectrum of the delayed neutrons is the poorest known of all input data required in the calculation of the effective delayed neutron fractions. In addition to delayed neutron spectra based on the aggregate spectrum measurements there are two different approaches for deriving the delayed neutron energy spectra. Both of them are based on the data related to the delayed neutron spectra from individual precursors of delayed neutrons. In present work these two different data sets were compared with the help of an approximation by gamma-function. The choice of this approximation function instead of the Maxwellian or evaporation type of distribution is substantiated.

Doroshenko, A Y; Tarasko, M Z

2001-01-01T23:59:59.000Z

22

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

23

Linking Grain Boundary Structure and Composition to Intergranular Stress Corrosion Cracking of Austenitic Stainless Steels  

SciTech Connect (OSTI)

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

24

Cracking of Composite Modified Alloy 825 Primary Air Port Tubes  

SciTech Connect (OSTI)

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

25

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

SciTech Connect (OSTI)

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

26

Uncertainty evaluation of delayed neutron decay parameters  

E-Print Network [OSTI]

parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical...

Wang, Jinkai

2009-05-15T23:59:59.000Z

27

Elevated temperature crack propagation  

SciTech Connect (OSTI)

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

28

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

SciTech Connect (OSTI)

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

29

Effects from Alkali-Silica Reacton and Delayed Ettringite Formation on Reinforced Concrete Column Lap Splices  

E-Print Network [OSTI]

Reinforced concrete bridge columns can deteriorate prematurely due to the alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF), causing internal expansion and cracking on the surface of the concrete. The performance...

Eck, Mary

2012-07-16T23:59:59.000Z

30

Effects from Alkali-Silica Reacton and Delayed Ettringite Formation on Reinforced Concrete Column Lap Splices.  

E-Print Network [OSTI]

??Reinforced concrete bridge columns can deteriorate prematurely due to the alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF), causing internal expansion and cracking on the… (more)

Eck, Mary

2012-01-01T23:59:59.000Z

31

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

32

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

33

Crack propagation in Hastelloy X  

SciTech Connect (OSTI)

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

34

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

35

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.

36

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

37

Thermally activated delayed fluorescence from {sup 3}n?* to {sup 1}n?* up-conversion and its application to organic light-emitting diodes  

SciTech Connect (OSTI)

Intense n?* fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the n?* transition and the higher energy of the {sup 3}??* state than the {sup 3}n?* one lead to a small energy difference between the lowest singlet (S{sub 1}) and triplet (T{sub 1}) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T{sub 1} ? S{sub 1} pathway in the electroluminescent process.

Li, Jie; Zhang, Qisheng; Nomura, Hiroko [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Miyazaki, Hiroshi [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Functional Materials Laboratory, Nippon Steel and Sumikin Chemical Co., Ltd, 46–80 Nakabaru, Sakinohama, Tobata, Kitakyushu, Fukuoka 804–8503 (Japan); Adachi, Chihaya, E-mail: adachi@cstf.kyushu-u.ac.jp [Department of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)

2014-07-07T23:59:59.000Z

38

Analysis of composite tube cracking in recovery boiler floors  

SciTech Connect (OSTI)

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

39

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

40

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

42

11 - Stresses due to Change of Air Temperature and Superficial Thermal Insulation  

Science Journals Connector (OSTI)

Experience shows that most cracks in mass concrete structures are originally superficial cracks, but some of them may become larger and deeper cracks later on which will reduce the safety and durability of the structure. Thermal insulation is the most efficient measure for preventing superficial cracks of mass concrete structures.

Zhu Bofang

2014-01-01T23:59:59.000Z

43

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

44

Status Report on Studies of Recovery Boiler Composite Floor Tube Cracking  

SciTech Connect (OSTI)

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

45

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

SciTech Connect (OSTI)

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

46

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

47

Discrete Element Model for Simulations of Early-Life Thermal Fracturing Behaviors in Ceramic Nuclear Fuel Pellets  

SciTech Connect (OSTI)

A discrete element Model (DEM) representation of coupled solid mechanics/fracturing and heat conduction processes has been developed and applied to explicitly simulate the random initiations and subsequent propagations of interacting thermal cracks in a ceramic nuclear fuel pellet during initial rise to power and during power cycles. The DEM model clearly predicts realistic early-life crack patterns including both radial cracks and circumferential cracks. Simulation results clearly demonstrate the formation of radial cracks during the initial power rise, and formation of circumferential cracks as the power is ramped down. In these simulations, additional early-life power cycles do not lead to the formation of new thermal cracks. They do, however clearly indicate changes in the apertures of thermal cracks during later power cycles due to thermal expansion and shrinkage. The number of radial cracks increases with increasing power, which is consistent with the experimental observations.

Hai Huang; Ben Spencer; Jason Hales

2014-10-01T23:59:59.000Z

48

Analysis of cracking of co-extruded recovery boiler floor tubes  

SciTech Connect (OSTI)

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

49

Thermal Shock-resistant Cement  

SciTech Connect (OSTI)

We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved cement, causing its volume to expand.

Sugama T.; Pyatina, T.; Gill, S.

2012-02-01T23:59:59.000Z

50

Predicting overload-affected fatigue crack growth in steels  

SciTech Connect (OSTI)

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

51

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

52

Peridynamic model for fatigue cracking.  

SciTech Connect (OSTI)

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

53

Cracking behavior of cored structures  

SciTech Connect (OSTI)

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

54

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

55

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

SciTech Connect (OSTI)

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

56

Degradation of Structural Alloys Under Thermal Insulation  

E-Print Network [OSTI]

Wet thermal insulation may actively degrade steel and stainless steel structures by general corrosion or stress-corrosion cracking. Two different mechanisms of water ingress into insulation are discussed; flooding from external sources...

McIntyre, D. R.

1984-01-01T23:59:59.000Z

57

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

58

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

SciTech Connect (OSTI)

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

59

Crack propagation driven by crystal growth  

SciTech Connect (OSTI)

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

60

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

62

Fundamentals of Delayed Coking Joint Industry Project  

SciTech Connect (OSTI)

Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking.

Michael Volk; Keith Wisecarver

2004-09-26T23:59:59.000Z

63

Fundamentals of Delayed Coking Joint Industry Project  

SciTech Connect (OSTI)

Delayed coking evolved steadily over the early to mid 1900s to enable refiners to convert high boiling, residual petroleum fractions to light products such as gasoline. Pound for pound, coking is the most energy intensive of any operation in a modern refinery. Large amounts of energy are required to heat the thick, poor-quality petroleum residuum to the 900 to 950 degrees F required to crack the heavy hydrocarbon molecules into lighter, more valuable products. One common misconception of delayed coking is that the product coke is a disadvantage. Although coke is a low valued (near zero economic value) byproduct, compared to transportation fuels, there is a significant worldwide trade and demand for coke as it is an economical fuel. Coke production has increased steadily over the last ten years, with further increases forecast for the foreseeable future. Current domestic production is near 111,000 tons per day. A major driving force behind this increase is the steady decline in crude quality available to refiners. Crude slates are expected to grow heavier with higher sulfur contents while environmental restrictions are expected to significantly reduce the demand for high-sulfur residual fuel oil. Light sweet crudes will continue to be available and in even greater demand than they are today. Refiners will be faced with the choice of purchasing light sweet crudes at a premium price, or adding bottom of the barrel upgrading capability, through additional new investments, to reduce the production of high-sulfur residual fuel oil and increase the production of low-sulfur distillate fuels. A second disadvantage is that liquid products from cokers frequently are unstable, i.e., they rapidly form gum and sediments. Because of intermediate investment and operating costs, delayed coking has increased in popularity among refiners worldwide. Based on the 2000 Worldwide Refining Survey published in the Oil and Gas, the delayed coking capacity for 101 refineries around the world is 2,937,439 barrels/calendar day. These cokers produce 154,607 tons of coke per day and delayed coking accounts for 88% of the world capacity. The delayed coking charge capacity in the United States is 1,787,860 b/cd. Despite its wide commercial use, only relatively few contractors and refiners are truly knowledgeable in delayed-coking design, so that this process carries with it a ''black art'' connotation. Until recently, the expected yield from cokers was determined by a simple laboratory test on the feedstock. As a result of Tulsa University's prior related research, a process model was developed that with additional work could be used to optimize existing delayed cokers over a wide range of potential feedstocks and operating conditions. The objectives of this research program are to: utilize the current micro, batch and pilot unit facilities at The University of Tulsa to enhance the understanding of the coking process; conduct additional micro and pilot unit tests with new and in-house resids and recycles to make current optimization models more robust; conduct focused kinetic experiments to enhance the furnace tube model and to enhance liquid production while minimizing sulfur in the products; conduct detailed foaming studies to optimize the process and minimize process upsets; quantify the parameters that affect coke morphology; and to utilize the knowledge gained from the experimental and modeling studies to enhance the computer programs developed in the previous JIP for optimization of the coking process. These refined computer models will then be tested against refinery data provided by the member companies. Novel concepts will also be explored for hydrogen sulfide removal of furnace gases as well as gas injection studies to reduce over-cracking.

Michael Volk; Keith Wisecarver

2003-09-26T23:59:59.000Z

64

Downhole delay assembly for blasting with series delay  

DOE Patents [OSTI]

A downhole delay assembly is provided which can be placed into a blasthole for initiation of explosive in the blasthole. The downhole delay assembly includes at least two detonating time delay devices in series in order to effect a time delay of longer than about 200 milliseconds in a round of explosions. The downhole delay assembly provides a protective housing to prevent detonation of explosive in the blasthole in response to the detonation of the first detonating time delay device. There is further provided a connection between the first and second time delay devices. The connection is responsive to the detonation of the first detonating time delay device and initiates the second detonating time delay device. A plurality of such downhole delay assemblies are placed downhole in unfragmented formation and are initiated simultaneously for providing a round of explosive expansions. The explosive expansions can be used to form an in situ oil shale retort containing a fragmented permeable mass of formation particles.

Ricketts, Thomas E. (Grand Junction, CO)

1982-01-01T23:59:59.000Z

65

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

66

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

67

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.

Bjørn Skallerud

2014-01-01T23:59:59.000Z

68

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

Broader source: Energy.gov (indexed) [DOE]

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

69

Delayed coking of decant oil and coal in a laboratory-scale coking unit  

SciTech Connect (OSTI)

In this paper, we describe the development of a laboratory-scale delayed coker and present results of an investigation on the recovered liquid from the coking of decant oil and decant oil/coal mixtures. Using quantitative gas chromatography/mass spectroscopy (GC/MS) and {sup 1}H and {sup 13}C NMR, a study was made of the chemical composition of the distillate liquids isolated from the overheads collected during the coking and co-coking process. {sup 1}H and {sup 13}C NMR analyses of combined liquids from coking and co-coking did not show any substantial differences. These NMR results of coking and co-coking liquids agree with those of GC/MS. In these studies, it was observed that co-coking with coal resulted in a decrease in the paraffins contents of the liquid. The percentage of cycloparaffins, indenes, naphthalenes, and tetralins did not change significantly. In contrast, alkyl benzenes and polycyclic aromatic hydrocarbons in the distillate were higher in the co-coking experiments which may have resulted from the distillation of thermally cracked coal macromolecules and the contribution of these molecules to the overall liquid composition. 40 refs., 3 figs., 13 tabs.

Oemer Guel; Leslie R. Rudnick; Harold H. Schobert [Pennsylvania State University Park, PA (United States). Energy Institute, C205 Coal Utilization Laboratory

2006-08-15T23:59:59.000Z

70

Spectroscopy of traceroute delays  

Science Journals Connector (OSTI)

We analyze delays of traceroute probes, i.e. packets that elicit ICMP TimeExceeded messages, for a full range of probe sizes up to 9000 bytes as observed on unloaded high-end routers. Our ultimate motivation is to use traceroute RTTs for Internet mapping ...

Andre Broido; Young Hyun; kc claffy

2005-03-01T23:59:59.000Z

71

LHC faces further delay  

Science Journals Connector (OSTI)

... An official announcement expected within days is likely to say that the Large Hadron Collider (LHC) will not begin providing data until November — more than a year after its ... providing data until November — more than a year after its planned start date. The LHC was seriously damaged during power tests in September last year (see 'Eight-month delay ...

Geoff Brumfiel

2009-02-09T23:59:59.000Z

72

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

73

A new mineralogical approach to predict coefficient of thermal expansion of aggregate and concrete  

E-Print Network [OSTI]

the construction allows for accurate prediction of the potential thermal change on crack development and crack width and enhances the overall design process. Siliceous gravel use results in larger crack width than does the limestone and at low temperature... increment between the contacts to the flask volume, the amount of aggregate in the flask, and the thermal characteristics of the aggregate. For measurements made below the freezing point of water, a non-reactive liquid, such as toluene, which does...

Neekhra, Siddharth

2005-02-17T23:59:59.000Z

74

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.

75

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.

76

Standard cosmology delayed  

SciTech Connect (OSTI)

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Choudhury, Debajyoti [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ghoshal, Debashis [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Sen, Anjan Ananda, E-mail: debajyoti.choudhury@gmail.com, E-mail: dghoshal@mail.jnu.ac.in, E-mail: anjan.ctp@jmi.ac.in [Centre for Theoretical Physics, Jamia Millia Islamia, New Delhi 110025 (India)

2012-02-01T23:59:59.000Z

77

Standard Cosmology Delayed  

E-Print Network [OSTI]

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Debajyoti Choudhury; Debashis Ghoshal; Anjan Ananda Sen

2012-02-06T23:59:59.000Z

78

Standard Cosmology Delayed  

E-Print Network [OSTI]

The introduction of a delay in the Friedmann equation of cosmological evolution is shown to result in the very early universe undergoing the necessary accelerated expansion in the usual radiation (or matter) dominated phase. Occurring even without a violation of the strong energy condition, this expansion slows down naturally to go over to the decelerated phase, namely the standard Hubble expansion. This may obviate the need for a scalar field driven inflationary epoch.

Choudhury, Debajyoti; Sen, Anjan Ananda

2011-01-01T23:59:59.000Z

79

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

SciTech Connect (OSTI)

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

80

Modeling delay in genetic networks: From delay birth-death processes to delay stochastic differential equations  

E-Print Network [OSTI]

genetic circuits17­26 ; the infusion of delay dramatically enhances the stability of such circuits27

Ott, William

Note: This page contains sample records for the topic "thermal cracking delayed" 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

White Etching Cracks | Argonne National Laboratory  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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

82

Overview of the DOE studies of recovery boiler floor tube cracking  

SciTech Connect (OSTI)

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

83

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

84

Delayed neutron emission measurements for U-235 and Pu-239  

E-Print Network [OSTI]

The delayed neutron emission rates of U-235 and Pu-239 samples were measured accurately from a thermal fission reaction. A Monte Carlo calculation using the Geant4 code was used to demonstrate the neutron energy independence of the detector used...

Chen, Yong

2009-05-15T23:59:59.000Z

85

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

86

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

87

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

88

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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

89

Early stages in the development of stress corrosion cracks  

SciTech Connect (OSTI)

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

90

Microstructural and Microchemical Characterization of Dual Step Aged Alloy X-750 and its Relationship to Environmentally Assisted Cracking  

SciTech Connect (OSTI)

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

91

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

92

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

93

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

94

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

95

“Petroleum Gas Oil?Ethanol” Blends Used as Feeds: Increased Production of Ethylene and Propylene over Catalytic Steam-Cracking (CSC) Hybrid Catalysts. Different Behavior of Methanol in Blends with Petroleum Gas Oil  

Science Journals Connector (OSTI)

“Petroleum Gas Oil?Ethanol” Blends Used as Feeds: Increased Production of Ethylene and Propylene over Catalytic Steam-Cracking (CSC) Hybrid Catalysts. ... Recently developed hybrid catalysts used in the catalytic steam cracking (CSC, formerly called selective deep catalytic cracking or SDCC(1, 2) and also thermal catalytic cracking or TCC(3, 4)) of hydrocarbon heavy feedstocks (naphthas and gas oils) are very efficient in the production of light olefins, particularly ethylene and propylene with a product propylene-to-ethylene ratio close to 1.0. ...

A. Muntasar; R. Le Van Mao; H. T. Yan

2010-03-22T23:59:59.000Z

96

Gels under stress: the origins of delayed collapse  

E-Print Network [OSTI]

Attractive colloidal particles can form a disordered elastic solid or gel when quenched into a two-phase region, if the volume fraction is sufficiently large. When the interactions are comparable to thermal energies the stress-bearing network within the gel restructures over time as individual particle bonds break and reform. Typically, under gravity such weak gels show a prolonged period of either no or very slow settling, followed by a sudden and rapid collapse - a phenomenon known as delayed collapse. The link between local bond breaking events and the macroscopic process of delayed collapse is not well understood. Here we summarize the main features of delayed collapse and discuss the microscopic processes which cause it. We present a plausible model which connects the kinetics of bond breaking to gel collapse and test the model by exploring the effect of an applied external force on the stability of a gel.

Lisa J. Teece; James M. Hart; Kerry Yen Ni Hsu; Stephen Gilligan; Malcolm A. Faers; Paul Bartlett

2014-03-12T23:59:59.000Z

97

The analysis of cracks in high-pressure piping and their effects on strength and lifetime of construction components at the Ignalina nuclear plant  

SciTech Connect (OSTI)

A number of cracks and damages of other sorts have been identified in the high-pressure parts at the Ignalina Nuclear Plant. They are caused by inadequate production- and repair technologies, as well as by thermal, chemical and mechanical processes of their performance. Several techniques are available as predictions of cracks and other defects of pressurized vessels. The choice of an experimental technique should be based on the level of its agreement with the actual processes.

Aleev, A.; Petkevicius, K.; Senkus, V. [and others

1997-04-01T23:59:59.000Z

98

Characterization of geothermal reservoir crack patterns using...  

Open Energy Info (EERE)

directions. From the polarizations the authors estimated three predominant subsurface fracture directions, and from the time delays of the split waves they determined...

99

Thermal spray coatings on Yankee dryers  

SciTech Connect (OSTI)

Several failure investigations and recent research on thermal spray coatings on Yankee dryer surfaces show at least three modes of environmentally induced degradation. Corrosion may occur with the ingress of certain chemicals into coating pores. Erosion or corrosion is manifested by streaks at local sites of high doctor blade loading. Erosion and cracking occur due to coating parameters, thermal stress, and differential expansion. While most of the results described in this paper are from investigations of molybdenum, stainless steel coatings also are discussed.

Bowers, D.F. (Packer Engineering, Inc., Naperville, IL (United States))

1994-08-01T23:59:59.000Z

100

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 "thermal cracking delayed" 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

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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....

102

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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

103

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

104

Effects of restraint on expansion due to delayed ettringite formation  

Science Journals Connector (OSTI)

Delayed ettringite formation (DEF) is a chemical reaction that causes expansion in civil engineering structures. The safety level of such damaged structures has to be reassessed. To do this, the mechanical conditions acting on DEF expansions have to be analysed and, in particular, the variation of strength with expansion and the effect of restraint on the DEF expansion. This paper highlights several points: DEF expansion is isotropic in stress-free conditions, compressive stresses decrease DEF expansion in the direction subjected to restraint and lead to cracks parallel to the restraint, and expansion measured in the stress-free direction of restrained specimens is not modified. Thus restraint causes a decrease of the volumetric expansion and DEF expansion under restraint is anisotropic. Moreover, the paper examines the correlation between DEF expansion and concrete damage, providing data that can be used for the quantification of the effect of stresses on DEF induced expansion.

Hassina Bouzabata; Stéphane Multon; Alain Sellier; Hacène Houari

2012-01-01T23:59:59.000Z

105

The impact of cement parameters on Delayed Ettringite Formation  

Science Journals Connector (OSTI)

Delayed Ettringite Formation (DEF) in concrete is likely to lead to swelling and cracking in structures which have undergone early age heating to a temperature of over 65 °C. Application of a method that accelerates this process has made it possible to study the impact of cement properties on DEF. For two temperatures reached by the concrete (75 °C or 85 °C), the study considers a domain defined by the sulphate content [2.6–3.6%], the alkali content [0.5–1%] and the Blaine specific area [3330–4635 cm2/g] of the cement. The impact of these parameters and the interactions between them on swelling are discussed. Monitoring of the dynamic elastic modulus of the concretes shows that this property may be reduced by DEF, but that it may increase again once the swelling process has ceased, probably due to the gradual filling of voids by ettringite formed under conditions of limited supersaturation.

A. Pavoine; X. Brunetaud; L. Divet

2012-01-01T23:59:59.000Z

106

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

107

Evaluation of the MMCLIFE 3.0 code in predicting crack growth in titanium aluminide composites  

SciTech Connect (OSTI)

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

108

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

109

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

110

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

111

Digital radiographic systems detect boiler tube cracks  

SciTech Connect (OSTI)

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

112

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

113

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

114

Feedback algorithm for simulation of multi-segmented cracks  

SciTech Connect (OSTI)

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

115

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

116

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

117

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

118

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

119

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

120

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.

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

122

Delayed Neutron and Delayed Photon Characteristics from Photofission of Actinides  

SciTech Connect (OSTI)

Delayed neutron (DN) and delayed photon (DP) emissions from photofission reactions play an important role for applications involving nuclear material detection and characterization. To provide new, accurate, basic nuclear data for evaluations and data libraries, an experimental programme of DN and DP measurements has been undertaken for actinides with bremsstrahlung endpoint energy in the giant resonance region ({approx}15 MeV). In this paper, the experimental setup and the data analysis method will be described. Experimental results for DN and DP characteristics will be presented for {sup 232}Th, {sup 235,238}U, {sup 237}Np, and {sup 239}Pu. Finally, an example of an application to study the contents of nuclear waste packages will be briefly discussed.

Dore, D.; Berthoumieux, E.; Leprince, A.; Ridikas, D. [DSM/IRFUS/PhN, CEA/Saclay, Gif-sur-Yvette, F-91191 (France); Ledoux, X. [CEA/DAM/DIF, Arpajon, F-91297 (France); Agelou, M.; Carrel, F.; Gmar, M. [CEA, LIST, Gif-sur-Yvette, F-91191 (France)

2011-12-13T23:59:59.000Z

123

The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water  

SciTech Connect (OSTI)

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

124

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

125

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

126

Fluid catalytic cracking of heavy petroleum fractions  

SciTech Connect (OSTI)

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

127

Static strength assessment of cracked tubular joints  

SciTech Connect (OSTI)

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

128

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

129

On the Cost/Delay Tradeoff of Wireless Delay Tolerant Geographic Routing Argyrios G. Tasiopoulos  

E-Print Network [OSTI]

On the Cost/Delay Tradeoff of Wireless Delay Tolerant Geographic Routing Argyrios G. Tasiopoulos transport cost of a packet and the delay in its delivery. We study this tradeoff in the context of geographical routing in wireless DTNs. We first specify the optimal cost/delay tradeoff, i.e., the tradeoff

Glinz, Martin

130

Stability criteria for BAM neural networks with leakage delays and probabilistic time-varying delays  

Science Journals Connector (OSTI)

This paper is concerned with the stability criteria for bidirectional associative memory (BAM) neural networks with leakage time delay and probabilistic time-varying delays. By establishing a stochastic variable with Bernoulli distribution, the information ... Keywords: BAM neural networks, Leakage delay, Probabilistic time-varying delays

S. Lakshmanan, Ju H. Park, Tae H. Lee, H. Y. Jung, R. Rakkiyappan

2013-05-01T23:59:59.000Z

131

Hierarchical Petascale Simulation Framework for Stress Corrosion Cracking  

SciTech Connect (OSTI)

Reaction Dynamics in Energetic Materials: Detonation is a prototype of mechanochemistry, in which mechanically and thermally induced chemical reactions far from equilibrium exhibit vastly different behaviors. It is also one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. The CACS group has performed multimillion-atom reactive MD simulations to reveal a novel two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine (RDX) crystal. Rapid production of N2 and H2O within ~10 ps is followed by delayed production of CO molecules within ~ 1 ns. They found that further decomposition towards the final products is inhibited by the formation of large metastable C- and O-rich clusters with fractal geometry. The CACS group has also simulated the oxidation dynamics of close-packed aggregates of aluminum nanoparticles passivated by oxide shells. Their simulation results suggest an unexpectedly active role of the oxide shell as a nanoreactor.

Vashishta, Priya

2014-12-01T23:59:59.000Z

132

Distributed Delays Stabilize Ecological Feedback Systems  

Science Journals Connector (OSTI)

We consider the effect of distributed delays in predator-prey models and ecological food webs. Whereas the occurrence of delays in population dynamics is usually regarded a destabilizing factor leading to the extinction of species, we here demonstrate complementarily that delay distributions yield larger stability regimes than single delays. Food webs with distributed delays closely resemble nondelayed systems in terms of ecological stability measures. Thus, we state that dependence of dynamics on multiple instances in the past is an important, but so far underestimated, factor for stability in dynamical systems.

Christian W. Eurich; Andreas Thiel; Lorenz Fahse

2005-04-22T23:59:59.000Z

133

Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking  

SciTech Connect (OSTI)

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

134

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

135

Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an AL-Zn-Mg-(Cu) Alloy  

SciTech Connect (OSTI)

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

136

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

137

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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....

138

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

139

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

Broader source: Energy.gov (indexed) [DOE]

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

140

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

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

An evaluation of crack front effect on threshold and crack propagation  

SciTech Connect (OSTI)

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

142

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

SciTech Connect (OSTI)

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

143

CIRCUMFERENTIAL MFL IN-LINE INSPECTION FOR CRACKS IN PIPELINES  

SciTech Connect (OSTI)

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

144

Delays, Unstable Particles, and Transport Theory  

E-Print Network [OSTI]

Delays associated with elementary interaction processes are investigated. The case of broad resonances is discussed in the context of reaction simulations.

P. Danielewicz; S. Pratt

1997-02-18T23:59:59.000Z

145

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

146

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

147

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

148

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

149

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

150

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

151

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

SciTech Connect (OSTI)

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

152

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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....

153

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

154

Isochronal synchronization of delay-coupled systems  

E-Print Network [OSTI]

We consider small network models for mutually delay-coupled systems which typically do not exhibit stable isochronally synchronized solutions. We show that for certain coupling architectures which involve delayed self feedback to the nodes, the oscillators become isochronally synchronized. Applications are shown for both incoherent pump coupled lasers and spatio-temporal coupled fiber ring lasers.

Ira B. Schwartz; Leah B. Shaw

2006-09-09T23:59:59.000Z

155

FPGA Interconnect Delay Fault Testing Erik Chmelar  

E-Print Network [OSTI]

A satisfactory FPGA testing method meets several crite- ria. First, the routing resources must be explicitlyFPGA Interconnect Delay Fault Testing Erik Chmelar Center for Reliable Computing Stanford is a scalable manufactur- ing test method for all SRAM-based FPGAs, able to detect multiple interconnect delay

Stanford University

156

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

SciTech Connect (OSTI)

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

157

Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy  

SciTech Connect (OSTI)

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

158

Thermal neutron imaging support with other laboratories BL06-IM-TNI  

SciTech Connect (OSTI)

The goals of this project are: (1) detect and locate a source of thermal neutrons; (2) distinguish a localized source from uniform background; (3) show shape and size of thermalizing material; (4) test thermal neutron imager in active interrogation environment; and (5) distinguish delayed neutrons from prompt neutrons.

Vanier,P.E.

2008-06-17T23:59:59.000Z

159

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

160

A three-dimensional validation of crack curvature in muscovite mica  

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

162

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

163

Environmentally Assisted Cracking of Ni-Base Alloys [Corrosion and  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

164

Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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

165

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

166

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

167

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

168

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

169

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

170

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

171

Effect of Thymectomy on ‘Delayed' Hypersensitive Reactions  

Science Journals Connector (OSTI)

... appeared to delay the onset and slow the tempo of rejection of skin homografts from Sherman strain rats. Grafts were inspected at 10 days and acceptance or rejection assessed by ...

BARRY G. ARNASON; BRANISLAV D. JANKOVI?; BYRON H. WAKSMAN

1962-04-07T23:59:59.000Z

172

Delayed neutron activation analysis for safeguards  

Science Journals Connector (OSTI)

Delayed neutron activation analysis (DNAA) presents a fast, accurate, and reliable method for quantification of fissile material. The method has relatively few sources of error and may be accomplished nondestruct...

D. C. Glasgow

2008-04-01T23:59:59.000Z

173

Hybrid delayed/undelayed LQG compensation  

E-Print Network [OSTI]

Loss Functions 1. Formulation of Sampled-data Equivalent Plant 2. Discretizing the Loss Function HYBRID DELAYED/UNDELAYED FEEDBACK . A. Hybrid (Delayed + Undelayed) Controller Structures B. Continuous-Undelayed Fccdback Structure 1. Defining... the SDE 2. Discretizing the LQG Objective . C. Sampled-Undelsyed Feedback Structure . 1. Defining the SDE 2. Discretization of Loss Function D. Remarks 9 11 17 20 20 23 23 26 29 30 32 35 IV LQG TRADE-OFFS FOR A DOUBLE-IVTEGRATOR PLANT A...

Wattal, Ankush

2012-06-07T23:59:59.000Z

174

J-integral values for cracks in conventional fatigue specimens  

SciTech Connect (OSTI)

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

175

Research on mechanisms of stress corrosion cracking in Zircaloy  

SciTech Connect (OSTI)

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

176

Thermal treatment  

Science Journals Connector (OSTI)

Thermal treatment can be regarded as either a pre-treatment of waste prior to final disposal, or as a means of valorising waste by recovering energy. It includes both the burning of mixed MSW in municipal inciner...

Dr. P. White; Dr. M. Franke; P. Hindle

1995-01-01T23:59:59.000Z

177

Thermal Processes  

Broader source: Energy.gov [DOE]

Some thermal processes use the energy in various resources, such as natural gas, coal, or biomass, to release hydrogen, which is part of their molecular structure. In other processes, heat, in...

178

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

179

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

180

Matrix fatigue cracking mechanisms of alpha(2) TMC for hypersonic applications  

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

Matrix fatigue cracking in {alpha}{sub 2} titanium matrix composites for hypersonic applications  

SciTech Connect (OSTI)

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

182

A framework for delay emulation of large-scale internetworks  

E-Print Network [OSTI]

, and Delay Injector. The Virtual Host Configuration Module enables a machine to act as a set of virtual hosts with arbitrary IP addresses. The Delay Estimator can compute delay values for any two arbitrary IP addresses. The Delay Injector captures packets...

Venkata, Shravan Rangaraju

2012-06-07T23:59:59.000Z

183

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

SciTech Connect (OSTI)

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

184

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

185

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

SciTech Connect (OSTI)

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

186

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

187

Stress-corrosion cracking in BWR and PWR piping  

SciTech Connect (OSTI)

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

188

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

189

Cracking a Cold Case and Enduring Mystery | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

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

190

Weld solidification cracking in 304 to 304L stainless steel  

SciTech Connect (OSTI)

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

191

Weld solidification cracking in 304 to 204L stainless steel  

SciTech Connect (OSTI)

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

192

Stress intensity factors for small fatigue cracks in tubular joints  

SciTech Connect (OSTI)

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

193

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

194

Delay tails in MapReduce scheduling  

Science Journals Connector (OSTI)

MapReduce/Hadoop production clusters exhibit heavy-tailed characteristics for job processing times. These phenomena are resultant of the workload features and the adopted scheduling algorithms. Analytically understanding the delays under different schedulers ... Keywords: MapReduce, coupling scheduler, fair scheduler, first in first out, hadoop, heavy-tails, processor sharing

Jian Tan; Xiaoqiao Meng; Li Zhang

2012-06-01T23:59:59.000Z

195

CAUSALITY, MEMORY ERASING AND DELAYED CHOICE EXPERIMENTS  

E-Print Network [OSTI]

Comment on [R.L. Ingraham, Phys. Rev. A 50, 4502 (1994)]. Ingraham suggested ``a delayed-choice experiment with partial, controllable memory erasing''. It is shown that he cannot be right since his predictions contradict relativistic causality. A subtle quantum effect which was overlooked by Ingraham is explained.

Y. Aharonov; S. Popsecu; L. Vaidman

1995-01-08T23:59:59.000Z

196

Modeling Delivery Delay for Flooding in Mobile  

E-Print Network [OSTI]

Modeling Delivery Delay for Flooding in Mobile Ad Hoc Networks TR-UTEDGE-2009-004 Taesoo Jun for Flooding in Mobile Ad Hoc Networks Taesoo Jun, Nirmalya Roy, and Christine Julien The Center for Excellence. In mobile networks, a major component of many of these routing protocols is some form of flooding, which

Julien, Christine

197

AQUIFER THERMAL ENERGY STORAGE  

E-Print Network [OSTI]

using aquifers for thermal energy storage. Problems outlinedmatical Modeling of Thermal Energy Storage in Aquifers,"ings of Aquifer Thermal Energy Storage Workshop, Lawrence

Tsang, C.-F.

2011-01-01T23:59:59.000Z

198

A sintering model for thermal barrier coatings R.G. Hutchinson a  

E-Print Network [OSTI]

Turbine blades in the high-pressure, high-temperature stages of gas turbines are manufactured from creep model is developed for the progressive sintering of ceramic columns in a thermal barrier coating made. Explicit calculations are reported for the evolution of sintering within an array of mud-cracked columns

Fleck, Norman A.

199

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

200

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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.


201

Leakage Minimization Using Self Sensing and Thermal Alireza Vahdatpour  

E-Print Network [OSTI]

architecture, measuring and modeling techniques, and algorithms for on-line power and energy optimization that can be used for real-time and low overhead measurement of temperature on chip positions where our Measurement, Design Keywords Leakage Energy, Thermal Management, Delay 1. INTRODUCTION There are two principal

Potkonjak, Miodrag

202

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.

203

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

204

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

205

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

206

Fatigue crack growth testing of sub-clad defects  

SciTech Connect (OSTI)

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

207

Incipient Crack Detection in Composite Wind Turbine Blades  

SciTech Connect (OSTI)

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

208

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

209

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

210

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

211

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.

212

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

213

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

214

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

215

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

SciTech Connect (OSTI)

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

216

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

217

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

218

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

219

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

220

Built-In Self Test (BIST) for Realistic Delay Defects  

E-Print Network [OSTI]

Testing of delay defects is necessary in deep submicron (DSM) technologies. High coverage delay tests produced by automatic test pattern generation (ATPG) can be applied during wafer and package tests, but are difficult to apply during the board...

Tamilarasan, Karthik Prabhu

2012-02-14T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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.


221

WATTS TOWERS: THE EFFECTS OF THERMAL CYCLES ON THE FORMATION AND BEHAVIOR OF CRACKS  

E-Print Network [OSTI]

to make lasting repairs to the Watts Towers. 15 REFERENCES [1] LSTC. "LS-DYNA KEYWROD MANUAL." DYNA Support. Livermore Software Technology Corporation, n.d. Web. 5 Apr. 2013.

Spencer, Matthew T

2013-02-06T23:59:59.000Z

222

Estimation of Damage to the Collector of a Water Economizer by Thermal Fatigue Cracks  

Science Journals Connector (OSTI)

We study defects formed on the outer and inner surfaces of the input collector of water economizer of a TPP-312 boiler at the...

R. Ya. Kosarevych; O. Z. Student; Ya. D. Onyshchak; A. D. Markov…

2004-01-01T23:59:59.000Z

223

Coherence delay augmented laser beam homogenizer  

DOE Patents [OSTI]

The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

Rasmussen, P.; Bernhardt, A.

1993-06-29T23:59:59.000Z

224

Coherence delay augmented laser beam homogenizer  

DOE Patents [OSTI]

The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

Rasmussen, Paul (Livermore, CA); Bernhardt, Anthony (Berkeley, CA)

1993-01-01T23:59:59.000Z

225

State Control Design for Linear Systems with Distributed Time Delays  

E-Print Network [OSTI]

State Control Design for Linear Systems with Distributed Time Delays Daniel Gontkovic and Róbert with distributed time delays. Using an extended form of the Lyapunov- Krasovskii functional the controller design involving distributed time delays is a problem of large practical interest where intensive activity are done

Paris-Sud XI, Université de

226

Delay-dependent robust $$H_\\infty $$ control for 2-D discrete nonlinear systems with state delays  

Science Journals Connector (OSTI)

This paper investigates the problem of robust $$H_\\infty $$ control for a class of 2-D (two-dimensional) discrete state delayed systems with sector nonlinearity ... Keywords: $$H_\\infty $$ performance, 2D discrete systems, Exponential stability, State delays

Shipei Huang; Zhengrong Xiang

2014-10-01T23:59:59.000Z

227

Ultrasonic Flaw Detection of Cracks and Machined Flaws as Observed Through Austenitic Stainless Steel Piping Welds  

SciTech Connect (OSTI)

Piping welds in the pressure boundary of light water reactors (LWRs) are subject to a volumetric examination based on Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Due to access limitations and high background radiation levels, the technique used is primarily ultrasonic rather than radiographic. Many of the austenitic welds in safety-related piping systems provide limited access to both sides of the weld, so a far-side examination is necessary. Historically, far-side inspections have performed poorly because of the coarse and elongated grains that make up the microstructures of austenitic weldments. The large grains cause the ultrasound to be scattered, attenuated, and redirected. Additionally, grain boundaries or weld geometry may reflect coherent ultrasonic echoes, making flaw detection and discrimination a more challenging endeavor. Previous studies conducted at the Pacific Northwest National Laboratory (PNNL) on ultrasonic far-side examinations in austenitic piping welds involved the application of conventional transducers, use of low-frequency Synthetic Aperture Focusing Techniques (SAFT), and ultrasonic phased-array (PA) methods on specimens containing implanted thermal fatigue cracks and machined reflectors [1-2]. From these studies, PA inspection provided the best results, detecting nearly all of the flaws from the far side. These results were presented at the Fifth International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components in 2006. This led to an invitation to examine field-removed specimens containing service-induced intergranular stress corrosion cracks (IGSCC) at the Electric Power Research Institute’s (EPRI) Nondestructive Evaluation (NDE) Center, in Charlotte, North Carolina. Results from this activity are presented.

Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.

2009-07-01T23:59:59.000Z

228

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

SciTech Connect (OSTI)

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

229

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

SciTech Connect (OSTI)

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

230

Delay time and Hartman effect in strain engineered graphene  

SciTech Connect (OSTI)

Tunneling times, including group delay and dwell time, are studied for massless Dirac electrons transmitting through a one-dimensional barrier in strain-engineered graphene. The Hartman effect, the independence of group delay on barrier length, is induced by the strain effect, and associated with the transmission gap and the evanescent mode. The influence of barrier height/length and strain modulus/direction on the group delay is also discussed, which provides the flexibility to control the group delay with applications in graphene-based devices. The relationship between group delay and dwell time is finally derived to clarify the nature of the Hartman effect.

Chen, Xi, E-mail: xchen@shu.edu.cn; Deng, Zhi-Yong [Department of Physics, Shanghai University, 200444 Shanghai (China); Ban, Yue, E-mail: yban@shu.edu.cn [Department of Electronic Information Materials, Shanghai University, 200444 Shanghai (China)

2014-05-07T23:59:59.000Z

231

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

SciTech Connect (OSTI)

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

232

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

233

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

234

Environmentally assisted cracking of light-water reactor materials  

SciTech Connect (OSTI)

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

235

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

236

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

237

To Crack or Not to Crack: Strain in High TemperatureSuperconductors  

SciTech Connect (OSTI)

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

238

Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods  

SciTech Connect (OSTI)

Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping.

Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Denslow, Kayte M.; Diaz, Aaron A.; Doctor, Steven R.

2007-03-01T23:59:59.000Z

239

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

SciTech Connect (OSTI)

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

240

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

SciTech Connect (OSTI)

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

242

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

SciTech Connect (OSTI)

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

243

The Thermal Expansion, Elastic and Fracture Properties of Porous Cordierite at Elevated Temperatures  

SciTech Connect (OSTI)

The properties that determine the thermal shock resistance in materials are reported for porous cordierite, a leading candidate material for the fabrication of diesel particulate filters. Fracture toughness and slow crack growth tests were performed on test specimens obtained from the walls of diesel particulate filter monolithic substrates using the double-torsion test method at temperatures between 20 C and 900 C. The thermal expansion and elastic properties were characterized between 20 C and 1000 C. The role of the microstructure of porous cordierite in determining its unusual thermal expansion and elevated temperature Young's modulus and fracture toughness are discussed.

Shyam, Amit [ORNL; Lara-Curzio, Edgar [ORNL; Pandey, Amit [ORNL; Watkins, Thomas R [ORNL; More, Karren [Oak Ridge National Laboratory (ORNL)

2012-01-01T23:59:59.000Z

244

Seasonal thermal energy storage  

SciTech Connect (OSTI)

This report describes the following: (1) the US Department of Energy Seasonal Thermal Energy Storage Program, (2) aquifer thermal energy storage technology, (3) alternative STES technology, (4) foreign studies in seasonal thermal energy storage, and (5) economic assessment.

Allen, R.D.; Kannberg, L.D.; Raymond, J.R.

1984-05-01T23:59:59.000Z

245

Thermal unobtainiums? The perfect thermal conductor and  

E-Print Network [OSTI]

contribute to thermal resistance · Isotopically pure diamond has highest thermal conductivity of any material materials: disordered layered crystals Conclude with some thoughts on promising, high-risk, research even in a computer model. #12;Thermal resistance is created by Umklapp scattering (U

Braun, Paul

246

Thermal Control & System Integration  

Broader source: Energy.gov [DOE]

The thermal control and system integration activity focuses on issues such as the integration of motor and power control technologies and the development of advanced thermal control technologies....

247

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

SciTech Connect (OSTI)

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

248

Mitigation of Delayed Ettringite Formation in Laboratory Specimens .  

E-Print Network [OSTI]

??The objective of this study was to determine if the growth of delayed ettringite formation (DEF) in existing concrete can be reduced or even prevented… (more)

Shaikh, Hafiz

2007-01-01T23:59:59.000Z

249

Characterization of Delayed Ettringite Formation in Maryland Bridges .  

E-Print Network [OSTI]

??The research investigated the significance of Delayed Ettringite Formation (DEF) presences in the Maryland Bridge Inventory. The objective of the research included investigating possible presence… (more)

Ceary, Micah

2007-01-01T23:59:59.000Z

250

Using Numerical Techniques to Accelerate Delayed Ettringnite Formation Test Methods.  

E-Print Network [OSTI]

??Delayed ettringite formation (DEF) in concrete can cause significant damage to structures. Finding the severity of the DEF is beneficial. Currently to measure the potential… (more)

Robertson, John Bret

2010-01-01T23:59:59.000Z

251

Stress-corrosion cracking of steels in ammonia with consideration given to OTEC design: a survey  

SciTech Connect (OSTI)

Carbon steel, alloy steel, and high-strength, quenched and tempered steel, when under applied or residual stress and especially when cold formed and/or welded without subsequent thermal stress relief, are subject to failure by stress-corrosion cracking (SCC) in air-contaminated dry ammonia. Water as well as hydrazine when present in small amounts have been shown to be effective inhibitors in an all steel system. Galvanic corrosion between dissimilar metals and/or accelerated failure by SCC of stressed steel as a result of galvanic coupling may be of concern. Where water has proven effective as an inhibitor of SCC in an all steel system, it may not be adequate in a mixed metal system. With aluminum tubes, the tube sheet will either have to be solid aluminum, aluminum clad steel or some nonconductive coating will be necessary to effectively remove the cathodic alloy from the galvanic circuit. Research is required to determine the severity of the coupling effect between dissimilar alloys in ammonia under OTEC conditions; especially the possibility of accelerated SCC failures of stressed steel where the presence of an inhibitor in the ammonia may not be sufficient to override the galvanic coupling effect.

Teel, R.B.

1980-03-01T23:59:59.000Z

252

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

SciTech Connect (OSTI)

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

253

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

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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...

254

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

255

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

256

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

SciTech Connect (OSTI)

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

257

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

258

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

259

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

SciTech Connect (OSTI)

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

260

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

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

Scattering and; Delay, Scale, and Sum Migration  

SciTech Connect (OSTI)

How do we see? What is the mechanism? Consider standing in an open field on a clear sunny day. In the field are a yellow dog and a blue ball. From a wave-based remote sensing point of view the sun is a source of radiation. It is a broadband electromagnetic source which, for the purposes of this introduction, only the visible spectrum is considered (approximately 390 to 750 nanometers or 400 to 769 TeraHertz). The source emits an incident field into the known background environment which, for this example, is free space. The incident field propagates until it strikes an object or target, either the yellow dog or the blue ball. The interaction of the incident field with an object results in a scattered field. The scattered field arises from a mis-match between the background refractive index, considered to be unity, and the scattering object refractive index ('yellow' for the case of the dog, and 'blue' for the ball). This is also known as an impedance mis-match. The scattering objects are referred to as secondary sources of radiation, that radiation being the scattered field which propagates until it is measured by the two receivers known as 'eyes'. The eyes focus the measured scattered field to form images which are processed by the 'wetware' of the brain for detection, identification, and localization. When time series representations of the measured scattered field are available, the image forming focusing process can be mathematically modeled by delayed, scaled, and summed migration. This concept of optical propagation, scattering, and focusing have one-to-one equivalents in the acoustic realm. This document is intended to present the basic concepts of scalar scattering and migration used in wide band wave-based remote sensing and imaging. The terms beamforming and (delayed, scaled, and summed) migration are used interchangeably but are to be distinguished from the narrow band (frequency domain) beamforming to determine the direction of arrival of a signal, and seismic migration in which wide band time series are shifted but not to form images per se. Section 3 presents a mostly graphically-based motivation and summary of delay, scale, and sum beamforming. The model for incident field propagation in free space is derived in Section 4 under specific assumptions. General object scattering is derived in Section 5 and simplified under the Born approximation in Section 6. The model of this section serves as the basis in the derivation of time-domain migration. The Foldy-Lax, full point scatterer scattering, method is derived in Section 7. With the previous forward models in hand, delay, scale, and sum beamforming is derived in Section 8. Finally, proof-of-principle experiments are present in Section 9.

Lehman, S K

2011-07-06T23:59:59.000Z

262

Delayed Radiation-Induced Vasculitic Leukoencephalopathy  

SciTech Connect (OSTI)

Purpose: Recently, single-fraction, high-dosed focused radiation therapy such as that administered by Gamma Knife radiosurgery has been used increasingly for the treatment of metastatic brain cancer. Radiation therapy to the brain can cause delayed leukoencephalopathy, which carries its own significant morbidity and mortality. While radiosurgery-induced leukoencephalopathy is known to be clinically different from that following fractionated radiation, pathological differences are not well characterized. In this study, we aimed to integrate novel radiographic and histopathologic observations to gain a conceptual understanding of radiosurgery-induced leukoencephalopathy. Methods and Materials: We examined resected tissues of 10 patients treated at Yale New Haven Hospital between January 1, 2009, and June 30, 2010, for brain metastases that had been previously treated with Gamma Knife radiosurgery, who subsequently required surgical management of a symptomatic regrowing lesion. None of the patients showed pathological evidence of tumor recurrence. Clinical and magnetic resonance imaging data for each of the 10 patients were then studied retrospectively. Results: We provide evidence to show that radiosurgery-induced leukoencephalopathy may present as an advancing process that extends beyond the original high-dose radiation field. Neuropathologic examination of the resected tissue revealed traditionally known leukoencephalopathic changes including demyelination, coagulation necrosis, and vascular sclerosis. Unexpectedly, small and medium-sized vessels revealed transmural T-cell infiltration indicative of active vasculitis. Conclusions: We propose that the presence of a vasculitic component in association with radiation-induced leukoencephalopathy may facilitate the progressive nature of the condition. It may also explain the resemblance of delayed leukoencephalopathy with recurring tumor on virtually all imaging modalities used for posttreatment follow-up.

Rauch, Philipp J. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Faculty of Medicine, University of Heidelberg, Heidelberg (Germany); Park, Henry S. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Knisely, Jonathan P.S. [Department of Radiation Medicine, North Shore University Hospital, Manhasset, New York (United States); Chiang, Veronica L. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Vortmeyer, Alexander O., E-mail: alexander.vortmeyer@yale.edu [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States)

2012-05-01T23:59:59.000Z

263

Erasure of Time Delay Signatures in the Output of an Optoelectronic Feedback Laser with Modulated Delays and Chaos Synchronization  

E-Print Network [OSTI]

By studying the autocorrelation function of the optoelectronic feedback semiconductor laser output we establish that the signatures of time delays can be erased in systems incorporating modulated feedback time delays. This property is of importance for the suitability of such laser systems for secure chaos-based communication systems. We also make the first report on chaos synchronization in both unidirectionally and bidirectionally coupled multiple time delay chaotic semiconductor lasers with modulated optoelectronic feedbacks.

E. M. Shahverdiev; K. A. Shore

2009-06-17T23:59:59.000Z

264

Temperature and environmentally assisted cracking in low alloy steel  

SciTech Connect (OSTI)

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

265

Physics-Based Stress Corrosion Cracking Component Reliability  

Broader source: Energy.gov (indexed) [DOE]

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

266

Thermal Management of Solar Cells  

E-Print Network [OSTI]

a better thermal conductance and when ceramic particles areor ceramic fillers that enhances thermal conductivity. Solid

Saadah, Mohammed Ahmed

2013-01-01T23:59:59.000Z

267

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

SciTech Connect (OSTI)

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

268

Adapting a delay-based protocol to heterogeneous environments  

E-Print Network [OSTI]

with different mixes of PERT and SACK protocols. Delay-based protocols, being less aggressive, have problems in fully utilizing a highspeed link while operating alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link. We performed...

Kotla, Kiran

2008-10-10T23:59:59.000Z

269

A structural approach to delay optimization in combinational circuits  

E-Print Network [OSTI]

about the area penalty incurred due to delay optimization. The experiments were performed on a SPARC-20 workstation. 1. Comparison with Delay Optimization Script in SIS 1. 3 We applied LOD to the two-input gate versions of the benchmark circuits...

Munshi, Avinash

1999-01-01T23:59:59.000Z

270

M/M/1 Queueing System with Delayed Controlled Vacation  

E-Print Network [OSTI]

M/M/1 Queueing System with Delayed Controlled Vacation Yonglu Deng , Zhongshan University W. John systems using a time division multiple access (TDMA) scheme (Frey and Takahashi, [7]). Researchers have that of a server's cold switch-on. The case of delayed vacation has also very recently been studied by Frey

Zhao, Yiqiang Q.

271

Utility Maximization for Delay Constrained QoS in Wireless  

E-Print Network [OSTI]

Utility Maximization for Delay Constrained QoS in Wireless I-Hong Hou CSL and Department of CS of utility maxi- mization for clients with delay based QoS requirements in wireless networks. We adopt that the utility of a client is a function of the timely throughput it obtains. We treat the timely throughput

272

Stability and bifurcation of genetic regulatory networks with delays  

Science Journals Connector (OSTI)

A four-dimension genetic regulatory network model with double genes and four delays is considered. The existence of Hopf bifurcation is first considered and then explicit formulas are derived by using the normal form method and center manifold theory ... Keywords: Genetic regulatory networks, Hopf bifurcation, Periodic solution, Time delay

Kai Wang; Lei Wang; Zhidong Teng; Haijun Jiang

2010-10-01T23:59:59.000Z

273

Short communication Dynamics of microbubble oscillators with delay coupling  

E-Print Network [OSTI]

Differential delay equation Perturbation theory Hopf bifurcation a b s t r a c t We investigate the stability of the in-phase mode in a system of two delay-coupled bubble oscillators. The bubble oscillator model to travel from one bubble to another through the liquid medium that surrounds them. Using techniques from

Rand, Richard H.

274

Convex Delay Models for Transistor Sizing Mahesh Ketkar  

E-Print Network [OSTI]

for developing accurate con- vex delay models to be used for transistor sizing. A new rich class of convex]: minimize Area or Power subject to Delay Tspec: (1) There have been many significant attempts to solve. in the development of closed form models for inverters and then mapping other gates to an equivalent inverter [5, 6

Sapatnekar, Sachin

275

Target Tracking Using Delayed Measurements with Implicit Constraints  

E-Print Network [OSTI]

with a negligible delay, since the speed of light is much larger than the speed of the target. This contribution the speed of light is much larger than the speed of the target. One further example relating to sensor speed (Doppler measurement). The delay k can be described as a function of the position (and hence

Gustafsson, Fredrik

276

Catalytic cracking of a Gippsland reduced crude on zeolite catalysts  

SciTech Connect (OSTI)

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

277

Fatigue and environmentally assisted cracking in light water reactors  

SciTech Connect (OSTI)

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

278

De-alloying and stress-corrosion cracking. Final report  

SciTech Connect (OSTI)

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

279

Delays associated with elementary processes in nuclear reaction simulations  

SciTech Connect (OSTI)

Scatterings, particularly those involving resonances, and other elementary processes do not happen instantaneously. In the context of semiclassical nuclear reaction simulations, we consider delays associated with an interaction for incident quantum wave packets. As a consequence, we express delays associated with elementary processes in terms of elements of the scattering matrix and phase shifts for elastic scattering. We show that, within the second order in density, the simulation must account for delays in scattering consistently with the mean field in order to properly model thermodynamic properties such as pressure and free-energy density. Delays associated with nucleon-nucleon and pion-nucleon scattering in free space are analyzed with their nontrivial energy dependence. Finally, an example of {ital s}-channel scattering of massless partons is studied, and scattering schemes in nuclear reaction simulations are investigated in the context of scattering delays. {copyright} {ital 1996 The American Physical Society.}

Danielewicz, P.; Pratt, S. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)] [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); [Grand Accelerateur National dIons Lourds (GANIL), BP 5027, F-14021 Caen Cedex (France)

1996-01-01T23:59:59.000Z

280

Next Generation Strong Lensing Time Delay Estimation with Gaussian Processes  

E-Print Network [OSTI]

Strong gravitational lensing forms multiple, time delayed images of cosmological sources, with the "focal length" of the lens serving as a cosmological distance probe. Robust estimation of the time delay distance can tightly constrain the Hubble constant as well as the matter density and dark energy. Current and next generation surveys will find hundreds to thousands of lensed systems but accurate time delay estimation from noisy, gappy lightcurves is potentially a limiting systematic. Using a large sample of blinded lightcurves from the Strong Lens Time Delay Challenge we develop and demonstrate a Gaussian Process crosscorrelation technique that delivers an average bias within 0.1% depending on the sampling, necessary for subpercent Hubble constant determination. The fits are accurate (80% of them within 1 day) for delays from 5-100 days and robust against cadence variations shorter than 6 days. We study the effects of survey characteristics such as cadence, season, and campaign length, and derive requiremen...

Hojjati, Alireza

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

282

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

283

Periodically Intermittent Stabilization of Delayed Neural Networks Based on Piecewise Lyapunov Functions/Functionals  

Science Journals Connector (OSTI)

This paper is concerned with the stabilization problem of delayed neural networks via a periodically intermittent controller. Two cases of time-varying bounded delays are considered: one is the time-varying delay without any constraints on the delay ... Keywords: Delayed neural networks, Intermittent control, Linear matrix inequalities, Piecewise Lyapunov functions/functionals

Wu-Hua Chen, Jiacheng Zhong, Zhiyong Jiang, Xiaomei Lu

2014-12-01T23:59:59.000Z

284

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

SciTech Connect (OSTI)

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

285

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

SciTech Connect (OSTI)

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

286

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

287

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

288

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

289

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

290

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

291

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

292

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

293

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

294

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

295

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

296

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

297

Experimental analysis of control loops with different delay times in the supply air system of a radiator test rig  

Science Journals Connector (OSTI)

The test rig of low-temperature hot-water radiator is a typical multi-input multi-output (MIMO) thermal system with large time delay. Aiming at the control of the supply air temperature and the temperature of the environmental chamber in the test rig, the paper carries out the fuzzy control experiments and PI control experiments based on adjusting the electric heater in the supply air system, in which there are two control loops with various delay time. The experiments researched two types of fuzzy control methods which are the basic fuzzy control (BFC), and the self-organizing rules fuzzy control (SORFC) with zero initial control rules. For the control loop of supply air temperature with short delay time, PI control performs better with fast convergence speed and small overshoot than the BFC and the SORFC. The convergence speed of the BFC method is lower than other two control methods. For the control loop of chamber temperature with long delay time, the SORFC has a satisfied control performance with less overshoot and stable error than the BFC and PI control.

Yongpan Chen; Jili Zhang; Zhen Lu; Tianyi Zhao; Hui Liu

2011-01-01T23:59:59.000Z

298

Syneresis and delayed detachment in agar plates  

E-Print Network [OSTI]

Biogels made of crosslinked polymers such as proteins or polysaccharides behave as porous soft solids and store large amount of solvent. These gels undergo spontaneous aging, called syneresis that consists in the shrinkage of the gel matrix and the progressive expulsion of the solvent, which eventually leads to the gel detachment from its container. Here we report on the syneresis phenomena in agar plates that consist in Petri dishes filled with a gel mainly composed of agar. Direct observations and speckle pattern correlation analyses allow us to rationalize the delayed detachment of the gel from the sidewall of the Petri dish. The detachment time $t^*$ is mainly controlled by the gel minimum thickness $e_{min}$ along the periphery of the plate: $t^*$ increases as a robust function of $e_{min}$ that neither depends on the age of the gel nor on any previous mass loss. Time-resolved correlation spectroscopy reveals that the speckle decorrelation rate increases a few hours before $t^*$ and that the gel detachment can be anticipated. This work provides quantitative observables to predict the shelf life of agar plates and highlights the key role of the competition between the syneresis and the gel adhesion to the wall in the detachment process.

Thibaut Divoux; Bosi Mao; Patrick Snabre

2014-10-30T23:59:59.000Z

299

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

300

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

302

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

303

HEATS: Thermal Energy Storage  

SciTech Connect (OSTI)

HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

None

2012-01-01T23:59:59.000Z

304

Holographic thermalization patterns  

E-Print Network [OSTI]

We investigate the behaviour of various correlators in N=4 super Yang Mills theory, taking finite coupling corrections into account. In the thermal limit we investigate the flow of the quasinormal modes as a function of the 't Hooft coupling. Then by using a specific model of holographic thermalization we investigate the deviation of the spectral densities from their thermal limit in an out-of-equilibrium situation. The main focus lies on the thermalization pattern with which the various plasma constituents of different energies approach their final thermal distribution as the coupling constant decreases from the infinite coupling limit. All results point towards the weakening of the usual top down thermalization pattern.

Stefan Stricker

2014-03-11T23:59:59.000Z

305

Holographic thermalization patterns  

E-Print Network [OSTI]

We investigate the behaviour of various correlators in N=4 super Yang Mills theory, taking finite coupling corrections into account. In the thermal limit we investigate the flow of the quasinormal modes as a function of the 't Hooft coupling. Then by using a specific model of holographic thermalization we investigate the deviation of the spectral densities from their thermal limit in an out-of-equilibrium situation. The main focus lies on the thermalization pattern with which the various plasma constituents of different energies approach their final thermal distribution as the coupling constant decreases from the infinite coupling limit. All results point towards the weakening of the usual top down thermalization pattern.

Stricker, Stefan

2014-01-01T23:59:59.000Z

306

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

SciTech Connect (OSTI)

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

307

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

308

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

SciTech Connect (OSTI)

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

309

Review of industry efforts to manage pressurized water reactor feedwater nozzle, piping, and feedring cracking and wall thinning  

SciTech Connect (OSTI)

This report presents a review of nuclear industry efforts to manage thermal fatigue, flow-accelerated corrosion, and water hammer damage to pressurized water reactor (PWR) feedwater nozzles, piping, and feedrings. The review includes an evaluation of design modifications, operating procedure changes, augmented inspection and monitoring programs, and mitigation, repair and replacement activities. Four actions were taken: (a) review of field experience to identify trends of operating events, (b) review of technical literature, (c) visits to PWR plants and a PWR vendor, and (d) solicitation of information from 8 other countries. Assessment of field experience is that licensees have apparently taken sufficient action to minimize feedwater nozzle cracking caused by thermal fatigue and wall thinning of J-tubes and feedwater piping. Specific industry actions to minimize the wall-thinning in feedrings and thermal sleeves were not found, but visual inspection and necessary repairs are being performed. Assessment of field experience indicates that licensees have taken sufficient action to minimize steam generator water hammer in both top-feed and preheat steam generators. Industry efforts to minimize multiple check valve failures that have allowed backflow of steam from a steam generator and have played a major role in several steam generator water hammer events were not evaluated. A major finding of this review is that analysis, inspection, monitoring, mitigation, and replacement techniques have been developed for managing thermal fatigue and flow-accelerated corrosion damage to feedwater nozzles, piping, and feedrings. Adequate training and appropriate applications of these techniques would ensure effective management of this damage.

Shah, V.N.; Ware, A.G.; Porter, A.M.

1997-03-01T23:59:59.000Z

310

Femtosecond-tunable measurement of electron thermalization in gold  

Science Journals Connector (OSTI)

Femtosecond electron thermalization in metals was investigated using transient thermomodulation transmissivity and reflectivity. Studies were performed using a tunable multiple-wavelength femtosecond pump-probe technique in optically thin gold films in the low perturbation limit. An IR pump beam is used to heat the electron distribution and changes in electron temperature are measured with a visible probe beam at the d band to Fermi-surface transition. We show that the subpicosecond optical response of gold is dominated by delayed thermalization of the electron gas. This effect is particularly important far off the spectral peak of the reflectivity or transmissivity changes, permitting a direct and sensitive access to the internal thermalization of the electron gas. Using a simple rate-equation model, line-shape analysis of the transient reflectivity and transmissivity indicates a thermalization time of the order of 500 fs. At energies close to the Fermi surface, longer thermalization times ?1–2 ps are observed. These results are in agreement with a more sophisticated model based on calculations of the electron-thermalization dynamics by numerical solutions of the Boltzmann equation. This model quantitatively describes the measured transient optical response during the full thermalization time of electron gas, of the order of 1.5 ps, and gives new insight into electron thermalization in metals.

C.-K. Sun; F. Vallée; L. H. Acioli; E. P. Ippen; J. G. Fujimoto

1994-11-15T23:59:59.000Z

311

Non-thermal Plasma Chemistry Non-thermal Thermal  

E-Print Network [OSTI]

automotive industry optics biomedical technology environmental technology Plasma Technology Quote from: Pla-thermal Plasma Chemical Flow Reactor #12;Werner von Siemens ,, ... construction of an apparatus generation (1857) pollution control volatile organic components, NOx reforming, ... radiation sources excimer

Greifswald, Ernst-Moritz-Arndt-Universität

312

Monitoring Thermal Fatigue Damage In Nuclear Power Plant Materials Using Acoustic Emission  

SciTech Connect (OSTI)

Proactive aging management of nuclear power plant passive components requires technologies to enable monitoring and accurate quantification of material condition at early stages of degradation (i.e., pre-macrocrack). Acoustic emission (AE) is well-suited to continuous monitoring of component degradation and is proposed as a method to monitor degradation during accelerated thermal fatigue tests. A key consideration is the ability to separate degradation responses from external sources such as water spray induced during thermal fatigue testing. Water spray provides a significant background of acoustic signals, which can overwhelm AE signals caused by degradation. Analysis of AE signal frequency and energy is proposed in this work as a means for separating degradation signals from background sources. Encouraging results were obtained by applying both frequency and energy filters to preliminary data. The analysis of signals filtered using frequency and energy provides signatures exhibiting several characteristics that are consistent with degradation accumulation in materials. Future work is planned to enable verification of the efficacy of AE for thermal fatigue crack initiation detection. While the emphasis has been placed on the use of AE for crack initiation detection during accelerated aging tests, this work also has implications with respect to the use of AE as a primary tool for early degradation monitoring in nuclear power plant materials. The development of NDE tools for characterization of aging in materials can also benefit from the use of a technology such as AE which can continuously monitor and detect crack initiation during accelerated aging tests.

Meyer, Ryan M.; Ramuhalli, Pradeep; Watson, Bruce E.; Pitman, Stan G.; Roosendaal, Timothy J.; Bond, Leonard J.

2012-04-26T23:59:59.000Z

313

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

314

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

315

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.

316

Thermal contact resistance  

E-Print Network [OSTI]

This work deals with phenomena of thermal resistance for metallic surfaces in contact. The main concern of the work is to develop reliable and practical methods for prediction of the thermal contact resistance for various ...

Mikic, B. B.

1966-01-01T23:59:59.000Z

317

Solar Thermal Processes  

Science Journals Connector (OSTI)

The use of solar energy for desalination purposes was one of ... The process is based on the use of solar thermal energy to evaporate water, thus separating pure ... brine. In this chapter an overview of solar thermal

M.T. Chaibi; Ali M. El-Nashar

2009-01-01T23:59:59.000Z

318

Thermal Neutron Scattering  

Science Journals Connector (OSTI)

... of its title. It is not for the nuclear physicist, nor even for the neutron physicist, but for the student of solids and liquids. "Thermal ... physicist, but for the student of solids and liquids. "Thermal neutron ...

G. E. BACON

1968-11-09T23:59:59.000Z

319

ALKALI AGGREGATE REACTION AND DELAYED ETTRINGITE FORMATION: COMMON FEATURES AND DIFFERENCES  

E-Print Network [OSTI]

ALKALI AGGREGATE REACTION AND DELAYED ETTRINGITE FORMATION: COMMON FEATURES AND DIFFERENCES Renaud Department, Paris, France Abstract Alkali-Aggregate Reaction (AAR) and Delayed Ettringite Formation (DEF effects 1 INTRODUCTION Alkali Aggregate Reaction (AAR) and Delayed Ettringite Formation (DEF) are internal

Paris-Sud XI, Université de

320

Exact emulation of a priority queue with a switch and delay lines  

E-Print Network [OSTI]

has to be at least one delay line of length 1, so L 1 = 1.which are all in the delay lines numbered 1, 2, . . . ,m. Thus these delay lines are “full”. Suppose that at time t

Sarwate, A D; Anantharam, V

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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

EMAT based inspection of natural gas pipelines for SSC cracks  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (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,

322

Delayed fracture in gels and Wei Hong*ab  

E-Print Network [OSTI]

­14 Instead of instantaneous or continuous crack growth, the gel would hesitate for some time without showing, and consequently facilitates nucleation and subcritical growth of microcracks. Since similar dynamic chain breakage DOI: 10.1039/c2sm25553g Subject to a subcritical load, a swollen polymeric gel may hesitate

Hong, Wei

323

Design of coupling for synchronization in time-delayed systems  

E-Print Network [OSTI]

We report a design of delay coupling for targeting desired synchronization in delay dynamical systems. We target synchronization, antisynchronization, lag-, antilag- synchronization, amplitude death (or oscillation death) and generalized synchronization in mismatched oscillators. A scaling of the size of an attractor is made possible in different synchronization regimes. We realize a type of mixed synchronization where synchronization, antisynchronization coexist in different pairs of state variables of the coupled system. We establish the stability condition of synchronization using the Krasovskii-Lyapunov function theory and the Hurwitz matrix criterion. We present numerical examples using the Mackey-Glass system and a delay R\\"{o}ssler system.

Dibakar Ghosh; Ioan Grosu; Syamal Kumar Dana

2012-07-03T23:59:59.000Z

324

Revival of Classical Vortex Generators Now for Transition Delay  

Science Journals Connector (OSTI)

Classical vortex generators, known for their efficiency in delaying or even inhibiting boundary layer separation, are here shown to be coveted devices for transition to turbulence delay. The present devices are miniature with respect to classical vortex generators but are tremendously powerful in modulating the laminar boundary layer in the direction orthogonal to the base flow and parallel to the surface. The modulation generates an additional term in the perturbation energy equation, which counteracts the wall-normal production term and, hence, stabilizes the flow. Our experimental results show that these devices are really effective in delaying transition, but we also reveal their Achilles’ heel.

Shahab Shahinfar; Sohrab S. Sattarzadeh; Jens H. M. Fransson; Alessandro Talamelli

2012-08-16T23:59:59.000Z

325

Electronic Implementation of the Mackey-Glass Delayed Model  

E-Print Network [OSTI]

The celebrated Mackey-Glass model describes the dynamics of physiological \\textit{delayed} systems in which the actual evolution depends on the values of the variables at some \\textit{previous} times. This kind of systems are usually expressed by delayed differential equations which turn out to be infinite-dimensional. In this contribution, an electronic implementation mimicking the Mackey-Glass model is proposed. New approaches for both the nonlinear function and the delay block are made. Explicit equations for the actual evolution of the implementation are derived. Simulations of the original equation, the circuit equation, and experimental data show great concordance.

Pablo Amil; Cecilia Cabeza; Arturo C. Martí

2014-08-21T23:59:59.000Z

326

Thermal-mechanical fatigue behavior of nickel-base superalloys. Final Report  

SciTech Connect (OSTI)

The main achievements of a 36-month research program are presented. The main objective was to gain more insight into the problem of crack growth under thermal mechanical fatigue (TMF) conditions. This program was conducted at M.I.T. for the period of September 1982 to September 1985. The program was arranged into five technical tasks. Under Task I, the literature of TMF data was reviewed. The goal was to identify the crack propagation conditions in aircraft engines (hot section) and to assess the validity of conventional fracture mechanics parameters to address TMF crack growth. The second task defined the test facilities, test specimen and the testing conditions needed to establish the effectiveness of data correlation parameters identified in Task I. Three materials (Inconel X-750, Hastelloy-X, and B-1900) were chosen for the program. Task II was accomplished in collaboration with Pratt and Whitney Aircraft engineers. Under Task III, a computerized testing system to measure the TMF behavior (LCF and CG behaviors) of various alloys systems was built. The software used to run isothermal and TMF tests was also developed. Built around a conventional servohydraulic machine, the system is capable of push-pull tests under stress or strain and temperature controlled conditions in the temperature range of 25C to 1050C. A crack propagation test program was defined and conducted under Task IV. The test variables included strain range, strain rate (frequency) and temperature. Task V correlated and generalized the Task IV data for isothermal and variable temperature conditions so that several crack propagation parameters could be compared and evaluated. The structural damage (mode of cracking and dislocation substructure) under TMF cycling was identified and contrasted with the isothermal damage to achieve a sound fundamental mechanistic understanding of TMF.

Pelloux, R.M.; Marchand, N.

1986-03-01T23:59:59.000Z

327

Design of a novel conduction heating based stress-thermal cycling apparatus for composite materials and its utilization to characterize composite microcrack damage thresholds  

E-Print Network [OSTI]

???????????..?????????47 viii CHAPTER Page 4.4 Thermal Loading Combined with Bending Conditions?????? 49 4.5 Thermo-Viscoelastic Constitutive....1 Characterization of Crack Formation and Propagation Mechanism?. 93 6.2 Analytical Study of Time Dependent Non-Isothermal Linear Thermo-Viscoelasticity??????????????????...94 6.3 Initial Damage Characterization??????????????.. 101 6.3.1 Cryogenic Temperature...

Ju, Jaehyung

2006-10-30T23:59:59.000Z

328

Thermal neutron detection system  

DOE Patents [OSTI]

According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

Peurrung, Anthony J. (Richland, WA); Stromswold, David C. (West Richland, WA)

2000-01-01T23:59:59.000Z

329

Thermal Performance Benchmarking (Presentation)  

SciTech Connect (OSTI)

This project will benchmark the thermal characteristics of automotive power electronics and electric motor thermal management systems. Recent vehicle systems will be benchmarked to establish baseline metrics, evaluate advantages and disadvantages of different thermal management systems, and identify areas of improvement to advance the state-of-the-art.

Moreno, G.

2014-11-01T23:59:59.000Z

330

Multiwavelength Thermal Emission  

E-Print Network [OSTI]

Multiwavelength Astronomy NASA #12;Thermal Emission #12;Thermal Emission Non-thermal p-p collisions Optical IR Radio/ Microwave sources of emission massive stars, WHIM, Ly many dust, cool objects-ray ~GeV Gamma-ray ~TeV sources of emission AGN, clusters, SNR, binaries, stars AGN (obscured), shocks

California at Santa Cruz, University of

331

Thermal imaging measurement of lateral diffusivity and non-invasive material defect detection  

DOE Patents [OSTI]

A system and method for determining lateral thermal diffusivity of a material sample using a heat pulse; a sample oriented within an orthogonal coordinate system; an infrared camera; and a computer that has a digital frame grabber, and data acquisition and processing software. The mathematical model used within the data processing software is capable of determining the lateral thermal diffusivity of a sample of finite boundaries. The system and method may also be used as a nondestructive method for detecting and locating cracks within the material sample.

Sun, Jiangang (Westmont, IL); Deemer, Chris (Downers Grove, IL)

2003-01-01T23:59:59.000Z

332

Analysis of thermal transfer of reinforced concrete submarine oil tanks  

SciTech Connect (OSTI)

The temperature distributions of reinforced concrete submarine oil tanks (RCSOT) obtained by the flat wall method and the cylinder wall method, are compared with the experimental data of the thermal transfer of the RCSOT. The precision and suitable scope of the different methods are discussed. The principle for selecting analysis method for solving thermal transfer of the RCSOT is given. The analytical and experimental temperature distributions show that the wall of the RCSOT should consist of double layer walls and the empty space between double layer walls should be filled with sand or other heat insulation materials to reduce the temperature difference between the inner and outer surfaces of the wall and to prevent the concrete from cracking.

Song, Y.P.; Zhao, G.F. [Dalian Univ. of Technology (China)

1994-12-31T23:59:59.000Z

333

Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management  

E-Print Network [OSTI]

The last years saw a renewal of interest for hypersonic research in general and regenerative cooling specifically, with a large increase of the number of dedicated facilities and technical studies. In order to quantify the heat transfer in the cooled structures and the composition of the cracked fuel entering the combustor, an accurate model of the thermal decomposition of the fuel is required. This model should be able to predict the fuel chemical composition and physical properties for a broad range of pressures, temperatures and cooling geometries. For this purpose, an experimental and modeling study of the thermal decomposition of generic molecules (long-chain or polycyclic alkanes) that could be good surrogates of real fuels, has been started at the DCPR laboratory located in Nancy (France). This successful effort leads to several versions of a complete kinetic model. These models do not assume any effect from the material that constitutes the cooling channel. A specific experimental study was performed ...

Bouchez, Marc; Visez, Nicolas; Herbinet, Olivier; Fournet, René; Marquaire, Paul-Marie

2009-01-01T23:59:59.000Z

334

Full-field characterization of thermal diffusivity in continuous- fiber ceramic composite materials and components  

SciTech Connect (OSTI)

Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced heat engines. Among the material classes of interest for such applications are silicon carbide (SiC)-fiber-reinforced SiC (SiC{sub (f)}/SiC), SiC-fiber-reinforced silicon nitride (SiC {sub (f)}/Si{sub 3}N{sub 4}), aluminum oxide (Al{sub 2}O{sub 3})-fiber-reinforced Al{sub 2}O{sub 3} (Al{sub 2}O{sub 3}{sub (f)}/Al{sub 2}O{sub 3}), and others. In such composites, the condition of the interfaces (between the fibers and matrix) are critical to the mechanical and thermal behavior of the component (as are conventional mechanical defects such as cracks, porosity, etc.). For example, oxidation of this interface (especially on carbon coated fibers) can seriously degrade both mechanical and thermal properties. Furthermore, thermal shock damage can degrade the matrix through extensive crack generation. A nondestructive evaluation method that could be used to assess interface condition, thermal shock damage, and to detect other ``defects`` would thus be very beneficial, especially if applicable to full-scale components. One method under development uses infrared thermal imaging to provide ``single-shot`` full-field assessment of the distribution of thermal properties in large components by measuring thermal diffusivity. By applying digital image filtering, interpolation, and least-squares-estimation techniques for noise reduction, we can achieve acquisition and analysis times of minutes or less with submillimeter spatial resolution. The system developed at Argonne has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in oxidation resistant coatings in a full array of test specimens. Subscale CFCC components with nonplanar geometries have also been studied for manufacturing-induced variations in thermal properties.

Steckenrider, J.S.; Ellingson, W.A. [Argonne National Lab., IL (United States); Rothermel, S.A. [South Dakota State Univ., Brookings, SD (United States)

1995-05-01T23:59:59.000Z

335

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

SciTech Connect (OSTI)

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

336

MHK Technologies/Tidal Delay | Open Energy Information  

Open Energy Info (EERE)

Delay Delay < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Tidal Delay.png Technology Profile Primary Organization Woodshed Technologies Ltd Technology Resource Click here Current Technology Type Click here Overtopping Technology Readiness Level Click here TRL 1 3 Discovery Concept Def Early Stage Dev Design Engineering Technology Description The Tidal Delay utilizes an existing natural land formation such as a peninsula or isthmus that creates a natural tidal barrier separating moving rising and falling bodies of seawater As the seawater on each side of the natural barrier rises and falls the device captures the energy resulting from the difference in water levels across the barrier using proven hydroelectric technology The device utilizes a standard impulse turbine installed in siphon pipe over under the natural barrier

337

Ionizing Radiation Induces Delayed Hyperrecombination in Mammalian Cells  

Science Journals Connector (OSTI)

...instability is critical to radiation risk assessment and for determining...the many delayed effects of radiation, chromosomal instability is...detrimental effects over a range of doses of ionizing radiation. Furthermore, a rapid and...

Lei Huang; Suzanne Grim; Leslie E. Smith; Perry M. Kim; Jac A. Nickoloff; Olga G. Goloubeva; William F. Morgan

2004-06-01T23:59:59.000Z

338

Delayed neutron energy spectrum measurements of actinide waste isotopes  

E-Print Network [OSTI]

was irradiated using the Texas A&M Nuclear Science Center Reactor (NSCR). Three proton recoil detectors, operating individually, in conjunction with MCNP calculated response functions, were used to measure the delayed neutron energy spectra of each isotope...

Comfort, Christopher M.

2012-06-07T23:59:59.000Z

339

Utilization-based delay guarantee techniques and their applications  

E-Print Network [OSTI]

have become popular for both civilian and mission critical applications. The variable service capacity of a wireless link presents more of a challenge in providing delay-guaranteed services in wireless networks. Finally, we study ways to provide...

Wang, Shengquan

2009-05-15T23:59:59.000Z

340

Implementation of a fiber-optic delay-line memory  

Science Journals Connector (OSTI)

The construction and operation of a 50-MHz 64 × 16 bit fiber-optic bit-serial delay-line memory is described. It consists of LiNbO3 directional coupler switches, fused-fiber...

Soukup, T J; Feuerstein, R J; Heuring, V P

1992-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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.


341

Assessment of Crack Detection in Cast Austenitic Piping Components Using Advanced Ultrasonic Methods.  

SciTech Connect (OSTI)

Studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on developing and evaluating the reliability of nondestructive examination (NDE) approaches for inspecting coarse-grained, cast stainless steel reactor components. The objective of this work is to provide information to the United States Nuclear Regulatory Commission (NRC) on the utility, effec¬tiveness and limitations of ultrasonic testing (UT) inspection techniques as related to the in-service inspec¬tion of primary system piping components in pressurized water reactors (PWRs). Cast stainless steel pipe specimens were examined that contain thermal and mechanical fatigue cracks located close to the weld roots and have inside/outside surface geometrical conditions that simulate several PWR primary piping configurations. In addition, segments of vintage centrifugally cast piping were also examined to understand inherent acoustic noise and scattering due to grain structures and determine consistency of UT responses from different locations. The advanced UT methods were applied from the outside surface of these specimens using automated scanning devices and water coupling. The low-frequency ultrasonic method employed a zone-focused, multi-incident angle inspection protocol (operating at 250-450 kHz) coupled with a synthetic aperture focusing technique (SAFT) for improved signal-to-noise and advanced imaging capabilities. The phased array approach was implemented with a modified instrument operating at 500 kHz and composite volumetric images of the specimens were generated. Re¬sults from laboratory studies for assessing detection, localization and sizing effectiveness are discussed in this paper.

Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.; Doctor, Steven R.

2007-01-01T23:59:59.000Z

342

Coupled Thermal-Hydrological-Mechanical-Chemical Model And Experiments...  

Broader source: Energy.gov (indexed) [DOE]

of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

343

Coupled Thermal-Hydrological-Mechanical-Chemical Model and Experiments...  

Broader source: Energy.gov (indexed) [DOE]

of mechanistic crack growth and grain contact models for chemically induced subcritical crack growth and pressure solution, with porosity-permeability changes * Conduct...

344

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

SciTech Connect (OSTI)

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

345

Thermal Insulation in Solar Thermal Devices  

Science Journals Connector (OSTI)

Thermal Insulation is a device or a practice which is used in a system for minimising heat losses caused due to transfer of heat from hotter to colder regions. It is one of the cheapest methods of energy conse...

B. C. Raychaudhuri

1986-01-01T23:59:59.000Z

346

Device For Trapping Laser Pulses In An Optical Delay Line  

DOE Patents [OSTI]

A device for maintaining a high-energy laser pulse within a recirculating optical delay line for a period time to optimize the interaction of the pulse with an electron beam pulse train comprising closely spaced electron micropulses. The delay line allows a single optical pulse to interact with many of the electron micropulses in a single electron beam macropulse in sequence and for the introduction of additional optical pulses to interact with the micropulses of additional electron beam macropulses. The device comprises a polarization-sensitive beam splitter for admitting an optical pulse to and ejecting it from the delay line according to its polarization state, a Pockels cell to control the polarization of the pulse within the delay line for the purpose of maintaining it within the delay line or ejecting it from the delay line, a pair of focusing mirrors positioned so that a collimated incoming optical pulse is focused by one of them to a focal point where the pulse interacts with the electron beam and then afterwards the pulse is recollimated by the second focusing mirror, and a timing device which synchronizes the introduction of the laser pulse into the optical delay line with the arrival of the electron macropulse at the delay line to ensure the interaction of the laser pulse with a prescribed number of electron micropulses in sequence. In a first embodiment of the invention, the principal optical elements are mounted with their axes collinear. In a second embodiment, all principal optical elements are mounted in the configuration of a ring.

Yu, David U. L. (Rancho Palos Verdes, CA); Bullock, Donald L. (Los Angeles, CA)

1997-12-23T23:59:59.000Z

347

Identifying delayed directional couplings with symbolic transfer entropy  

Science Journals Connector (OSTI)

We propose a straightforward extension of symbolic transfer entropy to enable the investigation of delayed directional relationships between coupled dynamical systems from time series. Analyzing time series from chaotic model systems, we demonstrate the applicability and limitations of our approach. Our findings obtained from applying our method to infer delayed directed interactions in the human epileptic brain underline the importance of our approach for improving the construction of functional network structures from data.

Henning Dickten and Klaus Lehnertz

2014-12-08T23:59:59.000Z

348

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

349

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

350

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

351

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

352

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

SciTech Connect (OSTI)

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

353

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

354

Some factors affecting delayed ettringite formation in heat-cured mortars  

Science Journals Connector (OSTI)

Although more than 10 years of studies on delayed ettringite formation (DEF) have led to consensus in numerous areas of past disagreements, some questions remain experimental work is needed to complete the knowledge of this pathology. Following this objective, this paper studies the influence of pre-existing microcracking, wetting/drying cycles and the type of sulfated addition on DEF in steam cured mortars. The mortar specimens were prepared using an Ordinary Portland Cement and two types of sulfate were added to the mixtures: calcium sulfate (CaSO4) or sodium sulfate (Na2SO4). The results confirm the well-known effect of temperature: no expansion was observed in any of the mixtures cured at room temperature. Moreover, no expansion was observed after 800 days for the reference mortar or for the mortar containing calcium sulfate but all the specimens of heat-cured mortars containing sodium sulfate expanded markedly after about 50 days whatever the supplementary treatments applied (thermal shrinkage or wetting/drying cycles). These results show the significant role played by alkalis in the occurrence of delayed ettringite. The supplementary treatments intended to cause prelimiray microcracking of the specimens did not promote expansion but contributed to a slight acceleration of the reaction. The ultimate values of expansion were similar to those obtained with sound mortars.

Gilles Escadeillas; Jean-Emmanuel Aubert; Maximiliano Segerer; William Prince

2007-01-01T23:59:59.000Z

355

Delayed Light Studies on Photosynthetic Energy Conversion VI. Effects of Phosphorylation Inhibitors on Delayed Light in the Millisecond Time Range  

Science Journals Connector (OSTI)

The delayed light which ARNOLD and STREHLER found in 1951 ... being recognized as a reliable measure of photosynthetic energy storage between loss of excitation from the ... NORRIS 1963) and production of chemica...

R. Wells; W. Bertsch; W. Cohen

1972-01-01T23:59:59.000Z

356

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

357

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

SciTech Connect (OSTI)

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

358

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

359

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

360

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 "thermal cracking delayed" 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

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

362

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

363

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

364

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

365

Thermal neutron imaging in an active interrogation environment  

SciTech Connect (OSTI)

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier,P.E.; Forman, L., and Norman, D.R.

2009-03-10T23:59:59.000Z

366

Thermal Neutron Imaging in an Active Interrogation Environment  

SciTech Connect (OSTI)

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutron-emitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

Vanier, Peter E. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Forman, Leon [Ion Focus Technology, Inc., Miller Place, NY 11764 (United States); Norman, Daren R. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2009-03-10T23:59:59.000Z

367

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

368

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

SciTech Connect (OSTI)

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

369

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

370

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

371

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

372

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

SciTech Connect (OSTI)

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

373

Thermal comfort during surgery  

E-Print Network [OSTI]

THERMAL COMFORT DURING SURGERY A Thesis by DAVID HAROLD MANNING Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1978 Major Subject: Industrial... Engineering THERMAL COMFORT DURING SURGERY A Thesis by DAVID HAROLD MANNING Approved as to style and content by: airman of C it ee Head of Department Member Me er December 1978 ABSTRACT Thermal Comfort During Surgery (December 1978) David Harold...

Manning, David Harold

1978-01-01T23:59:59.000Z

374

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

375

Weibull Effective Area for Hertzian Ring Crack Initiation Stress  

SciTech Connect (OSTI)

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

376

Automated inspection of surface breaking cracks using GMR sensor arrays  

SciTech Connect (OSTI)

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

377

Catalyst deactivation kinetics: An apparent delay in decreasing of catalyst activity, “inflection point” and data interpretation  

Science Journals Connector (OSTI)

Problems of catalyst deactivation kinetics and catalyst stability testing are considered. An apparent delay...

N. M. Ostrovskii

2011-12-01T23:59:59.000Z

378

Effects of hydrogen on electropotential monitoring of stress corrosion crack growth  

SciTech Connect (OSTI)

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

379

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

SciTech Connect (OSTI)

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

380

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

SciTech Connect (OSTI)

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

382

Variable pressure thermal insulating jacket  

DOE Patents [OSTI]

A device for controlled insulation of a thermal device is disclosed. The device includes a thermal jacket with a closed volume able to be evacuated to form an insulating jacket around the thermal source. A getter material is in communication with the closed volume of the thermal jacket. The getter material can absorb and desorb a control gas to control gas pressure in the volume of the thermal jacket to control thermal conductivity in the thermal jacket. 10 figs.

Nelson, P.A.; Malecha, R.F.; Chilenskas, A.A.

1994-09-20T23:59:59.000Z

383

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

SciTech Connect (OSTI)

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

384

NANO REVIEW Open Access Thermal conductivity and thermal boundary  

E-Print Network [OSTI]

NANO REVIEW Open Access Thermal conductivity and thermal boundary resistance of nanostructures and the thermal transport prop- erties is a key point to design materials with preferred thermal properties with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity

Boyer, Edmond

385

Thermal shock and fatigue resistance of tungsten materials under transient heat loading  

Science Journals Connector (OSTI)

Abstract Transient heat loading tests were performed on rolled pure tungsten (PW) and lanthanum oxide doped tungsten (WL10) as well as swaged + rolled potassium doped tungsten (W-K) samples using an electron beam. In thermal shock tests, the cracking threshold was 0.44–0.66, 0.17–0.22 and 0.44–0.66 GW/m2 for PW, WL10 and W-K, respectively. The melting threshold was over 1.1 GW/m2 for PW and W-K while 0.66–0.88 GW/m2 for WL10. In thermal fatigue tests, the obvious roughening threshold was over 1000 cycles for PW and WL10 while 1–100 cycles for W-K. The cracking threshold was 100–1000 cycles for PW, 1–100 cycles for WL10 and over 1000 cycles for W-K alloy. WL10 displayed worse thermal and fatigue resistance while W-K exhibited better properties compared with PW, which was attributed to differences in thermal–mechanical properties of the three tungsten alloys, in addition to the size and number density of La2O3 particles and potassium bubbles.

Xiaoxin Zhang; Qingzhi Yan; Shaoting Lang; Min Xia; Xiang Liu; Changchun Ge

2014-01-01T23:59:59.000Z

386

Delay time calculation for dual-wavelength quantum cascade lasers  

SciTech Connect (OSTI)

In this paper, we calculate the turn-on delay (t{sub th}) and buildup (?t) times of a midinfrared quantum cascade laser operating simultaneously on two laser lines having a common upper level. The approach is based on the four-level rate equations model describing the variation of the electron number in the states and the photon number present within the cavity. We obtain simple analytical formulae for the turn-on delay and buildup times that determine the delay times and numerically apply our results to both the single and bimode states of a quantum cascade laser, in addition the effects of current injection on t{sub th} and ?t are explored.

Hamadou, A., E-mail: abd-hamado@yahoo.fr [Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université de Bordj Bou Arreridj 34000 (Algeria); Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Lamari, S. [Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 (Algeria); Thobel, J.-L. [Institut d'Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR 8520, Université Lille1, Avenue Poincaré, BP 60069, 59652 Villeneuve d'Ascq Cédex (France)

2013-11-28T23:59:59.000Z

387

Multi-rhythmicity in an optoelectronic oscillator with large delay  

E-Print Network [OSTI]

An optoelectronic oscillator exhibiting a large delay in its feedback loop is studied both experimentally and theoretically. We show that multiple square-wave oscillations may coexist for the same values of the parameters (multi-rhythmicity). Depending on the sign of the phase shift, these regimes admit either periods close to an integer fraction of the delay or periods close to an odd integer fraction of twice the delay. These periodic solutions emerge from successive Hopf bifurcation points and stabilize at a finite amplitude following a scenario similar to Eckhaus instability in spatially extended systems. We find quantitative agreements between experiments and numerical simulations. The linear stability of the square-waves is substantiated analytically by determining stable fixed points of a map.

Weicker, Lionel; Rosin, David P; Gauthier, Daniel J

2014-01-01T23:59:59.000Z

388

Thermal Insulation of Houses  

Science Journals Connector (OSTI)

... THE Thermal Insulation (Dwellings) Bill which Mr. G. Nabarro introduced into the House of Commons on ... , sponsored by members of both major political parties, extends the principle of the Thermal Insulation (Industrial Buildings) Act of July 1957 to all new dwelling houses built in the ...

1958-02-22T23:59:59.000Z

389

Mechanical Engineering & Thermal Group  

E-Print Network [OSTI]

Mechanical Engineering & Thermal Group The Mechanical Engineering (ME) & Thermal Group at LASP has, and ground- based mechanical systems. Instrument Design Building on decades of design experience that has evolved with the complexity of instrument design demands, LASP mechanical engineers develop advanced

Mojzsis, Stephen J.

390

Thermal Recovery Methods  

SciTech Connect (OSTI)

Thermal Recovery Methods describes the basic concepts of thermal recovery and explains the injection patterns used to exploit reservoir conditions. Basic reservoir engineering is reviewed with an emphasis on changes in flow characteristics caused by temperature. The authors discuss an energy balance for steam and combustion drive, and they explain in situ reactions. Heat loss, combustion drive, and steam displacement also are examined in detail, as well as cyclic steam injection, downhole ignition, well heating, and low-temperature oxidation. Contents: Thermal processes; Formation and reservoir evaluations; Well patterns and spacing; Flow and process equations; Laboratory simulation of thermal recovery; Heat loss and transmission; Displacement and production; Equipment; Basic data for field selection; Laboratory evaluation of combustion characteristics; Thermal properties of reservoirs and fluids.

White, P.D.; Moss, J.T.

1983-01-01T23:59:59.000Z

391

Tunable thermal link  

DOE Patents [OSTI]

Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

Chang, Chih-Wei; Majumdar, Arunava; Zettl, Alexander K.

2014-07-15T23:59:59.000Z

392

Solar thermal aircraft  

DOE Patents [OSTI]

A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

Bennett, Charles L. (Livermore, CA)

2007-09-18T23:59:59.000Z

393

Efficient Path Delay Test Generation with Boolean Satisfiability  

E-Print Network [OSTI]

Assignments (NAs) of the paths are compacted to improve the compaction ratio. However, dynamic compaction takes significantly more CPU time than static compaction. 1.5 Pseudo Functional Test The voltage level of the power grid in the circuit can... significantly affect the accuracy of delay test. [32][33] The launching of the delay test causes a surge in the current drawn from the power grid. Because of the inductance on the power grid, this current surge will cause a large drop in power supply voltage...

Bian, Kun

2013-12-10T23:59:59.000Z

394

Coherence Resonance in an Autapse Neuron Model with Time Delay  

E-Print Network [OSTI]

We study the noise activated dynamics of a model {\\it autapse} neuron system that consists of a subcritical Hopf oscillator with a time delayed nonlinear feedback. The coherence of the noise driven pulses of the neuron exhibits a novel double peaked structure as a function of the noise amplitude. The two peaks correspond to separate optimal noise levels for excitation of single spikes and multiple spikes (bursts) respectively. The relative magnitudes of these peaks are found to be a sensitive function of time delay. The physical significance of our results and its practical implications in various real life systems are discussed.

Gautam C Sethia; Juergen Kurths; Abhijit Sen

2006-04-10T23:59:59.000Z

395

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

SciTech Connect (OSTI)

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

396

Thermal decomposition of charring materials  

SciTech Connect (OSTI)

Experimental techniques and methods were developed to investigate the transient process of wood pyrolysis under different levels of external radiation, moisture content of the wood sample, and oxygen concentration of the ambient atmosphere. A unique small-scale combustion-wind tunnel was constructed to conduct the pyrolysis experiments and to obtain the time dependent gasification mass flux, surface and in-depth temperatures, and evolved products of pyrolysis (CO, CO{sub 2}, H{sub 2}O, and total hydrocarbons (THC)) for thermally thick samples of Douglas-fir. Experiments were performed both in inert atmosphere (nitrogen), and in air at several different heat fluxes and three different moisture contents of wood. Time dependent empirical chemical composition, char yield, and the heat of combustion of the pyrolysis products were determined. The experimental results indicate that the presence of moisture reduces the pyrolysis mass flux and delays the occurrence of its maxima. Presence of oxygen drastically increases the pyrolysis mass flux but its effect specially at lower temperatures depends on the experimental conditions such as the boundary layer thickness over the wood surface. Char yield, chemical composition of the volatiles, and the heat of combustion were found to vary during the pyrolysis process and with changes in the environmental conditions and wood moisture content. The pyrolysis temperature assumption often used for the simplified modeling of wood pyrolysis was examined in detail by considering two otherwise identical models; one with infinitely fast decomposition kinetics and the other with finite rate chemistry. It was concluded that the pyrolysis temperature is not a material property and different pyrolysis temperatures are needed for every problem.

Nurbakhsh, S.

1989-01-01T23:59:59.000Z

397

High-Temperature Thermal Array for Next Generation Solar Thermal...  

Broader source: Energy.gov (indexed) [DOE]

Thermal Array for Next Generation Solar Thermal Power Production Award Number: DE-EE00025828 Report Date: March 15, 2013 PI: Stephen Obrey * Technical approach is focused on...

398

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

399

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

400

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

SciTech Connect (OSTI)

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

402

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

SciTech Connect (OSTI)

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

403

Instability of coupled systems with delay1 Reinhard Racke  

E-Print Network [OSTI]

Instability of coupled systems with delay1 Reinhard Racke Department of Mathematics and Statistics University of Konstanz 78457 Konstanz, Germany reinhard.racke@uni-konstanz.de Abstract: We consider linear, Quintanilla & Racke [9], or Pr¨u� [29], in particular for connections to Volterra equations. Indeed

Racke, Reinhard

404

Client-Centered Energy and Delay Analysis for TCP Downloads  

E-Print Network [OSTI]

time for energy savings during TCP downloads, in an attempt to reduce the energy*delay product. Effectively saving WNIC energy during a TCP download is difficult because TCP streams tend to be smooth transfer time in exchange for energy savings. In fact, IEEE 802.11b power saving mode (PSM) [2] is designed

Lowenthal, David

405

A CURRENT CONTROLLED VARIABLE DELAY SUPERCONDUCTING TRANSMISSION LINE  

E-Print Network [OSTI]

I I I I 1388 A CURRENT CONTROLLED VARIABLE DELAY SUPERCONDUCTING TRANSMISSION LINE S. M. Anlage, H line. The device makes use of the change in kinetic inductance of a superconducting transmission line, fabrication of transmission lines with such films provides the means for constructing a continuously variable

Anlage, Steven

406

On the modeling of time-varying delays  

E-Print Network [OSTI]

functions were limited to steps, ramps and sinusoids. This limited class of inputs and delays defines the scope of this thesis and the results are to be interpreted as such. The methodology adopted to identify the basic underpinnings of models was system...

Shah, Chirag Laxmikant

2004-09-30T23:59:59.000Z

407

Envelope/phase delays correction in an EER radio architecture  

E-Print Network [OSTI]

Envelope/phase delays correction in an EER radio architecture Jean-François BERCHER and Corinne -- In this paper we consider the sensitivity of a transmitter based on EER radio architecture to time mismatches the interest of this approach. I. INTRODUCTION Envelope Elimination and restoration (EER) was developed by Kahn

Bercher, Jean-François

408

Delay analysis of bursty tasks using workload arrival functions  

E-Print Network [OSTI]

and the integrated methodologies with variable workloads are introduced. However, these methodologies have some limitations when they are applied to task systems instead of traffic. In this thesis, we propose that the end-to-end delay computed by the decomposed...

Kim, Junwhan

2012-06-07T23:59:59.000Z

409

Joint Power-Delay Minimization in Green Wireless Access Networks  

E-Print Network [OSTI]

, adapting power consumption to traffic load [3] or devising intelligent network deployment strategies using an optimization problem that jointly minimizes the power consumption of the network and the sum of data unitJoint Power-Delay Minimization in Green Wireless Access Networks Farah Moety, Samer Lahoud, Kinda

Paris-Sud XI, Université de

410

Technology Mapping Targeting Routing Congestion under Delay Constraints  

E-Print Network [OSTI]

1 Technology Mapping Targeting Routing Congestion under Delay Constraints Rupesh S. Shelar, Member a serious concern in today's VLSI designs. To address the same, we propose a technology mapping algorithm in a 100 nm technology show that the algorithm can improve track overflows by 59%, on an average

Sapatnekar, Sachin

411

A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS  

E-Print Network [OSTI]

A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS #3; MICHAEL G. ZAGER y , HIEN T endocrine-related e#11;ects such as reduced birth weight in rats and humans. In its conjugated form], including soybean-derived foods with high genistein concentrations, such as tofu and soy-derived infant

412

Photonics for time delay in communication Jianyi Yang  

E-Print Network [OSTI]

to 50 ns, or 0.3 mm to 15 m in free space, for most phased array antenna PAA applications. In PAAs result- ing from the propagation from each of the PAA's indi- vidual emitters. In general, the maximum delay time re- quired in a PAA is comparable with the antenna's size. For a large PAA it is generally

Chen, Ray

413

Task Assignment in a Server Farm with Switching Delays and  

E-Print Network [OSTI]

costs Holding costs (per job) Objective to balance between Energy consumption Performance (e.g., latency Energy- and Delay-aware cost structure Switching costs Running costs Holding costs (per job) Objective to balance between Energy consumption Performance (e.g., latency) Heterogeneous servers, job-specific costs

Hyytiä, Esa

414

Packet Audio Playout Delay Adjustment: Performance Bounds and Algorithms \\Lambda  

E-Print Network [OSTI]

Packet Audio Playout Delay Adjustment: Performance Bounds and Algorithms \\Lambda Sue B. Moon, Jim 01003 fsbmoon,kurose,towsleyg@cs.umass.edu Abstract In packet audio applications, packets are buffered, given a trace of packet audio receptions at a receiver, we present efficient algorithms for computing

Massachusetts at Amherst, University of

415

Turbo King: Framework for Large-Scale Internet Delay Measurements  

E-Print Network [OSTI]

servers (which is called cache pollution) and requires large traffic overhead when deployed in large consuming half the bandwidth needed by King and reducing the impact of cache pollution by several orders building an all-to-all delay matrix between approximately 220, 000 BGP prefixes advertised in the Internet

Loguinov, Dmitri

416

Measurement of Gravitational Lens Time Delays with LSST (SULI Paper)  

SciTech Connect (OSTI)

The proposed Large Synoptic Survey Telescope will be the first to explore multiple dark energy probes simultaneously, including baryon acoustic oscillations, weak lensing, and strong gravitational lensing. The large data sample, covering the entire visible sky every few nights, will allow an unprecedented survey of deep supernova sources and their lensed images. The latter have not yet been observed. Notably, LSST will measure the time delays between different strong-lensed images of the same supernova. This will provide a unique probe of dark matter, dark energy, and the expansion rate of the Universe. By simulating LSST observations under realistic conditions, we determined the time delay precision of multiple images from a representative strong-lensed Type Ia supernova. The output of the simulation was a set of light curves according to field and filter, which were subsequently analyzed to determine the experimental time delays. We find that a time delay precision of better then 10% can be achieved under suitable conditions. Firstly, a minimum observed peak-magnitude of 22 is required for the lensed image, corresponding to an intrinsic source magnitude of about 24. The number of such supernova sources expected for LSST is under investigation, but it could amount to several thousand. Secondly, a minimum of about 50 visits per field is required, and, moreover, these visits must be evenly distributed over the duration of the event. The visit frequency should be approximately once per week, or better. Thirdly, the sky brightness should be below 21 magnitude arcsec{sup -2} to allow sufficient sensitivity to distance sources. Under the nominal LSST visiting schedule and field conditions, 15% of all fields satisfy these criteria, and allow time delay measurements of better than 10% precision. This performance can be further improved by fitting the predicted supernova light curves to the observations, rather than using the simple weighted mean as in the present study. Of the well-measured fields, 85% involve observations taken with the r filter, which has a wavelength acceptance that is well-matched to supernova spectra. This filter therefore represents the best choice for strong gravitational lens observations with LSST. Our primary conclusion is that the visiting schedule is the single most important parameter to optimize for time delay measurements, and, once a lensed supernova has been detected, that frequent, regular observations should be scheduled to search with the highest sensitivity for multiple, delayed lensed images.

Kirkby, Lowry Anna; /Oxford U. /SLAC

2006-01-04T23:59:59.000Z

417

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

SciTech Connect (OSTI)

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

418

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

SciTech Connect (OSTI)

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

419

Thermal insulations using vacuum panels  

DOE Patents [OSTI]

Thermal insulation vacuum panels are formed of an inner core of compressed low thermal conductivity powders enclosed by a ceramic/glass envelope evaluated to a low pressure.

Glicksman, Leon R. (Lynnfield, MA); Burke, Melissa S. (Pittsburgh, PA)

1991-07-16T23:59:59.000Z

420

Thermally driven circulation  

E-Print Network [OSTI]

Several problems connected by the theme of thermal forcing are addressed herein. The main topic is the stratification and flow field resulting from imposing a specified heat flux on a fluid that is otherwise confined to a ...

Nelken, Haim

1987-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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

Manipulation of Thermal Phonons  

E-Print Network [OSTI]

to manipulate the behavior of phonons is crucial for both energy applications and the cooling of integrated circuits. A novel class of artificially periodic structured materials — phononic crystals — might make manipulation of thermal phonons possible. In many...

Hsu, Chung-Hao

2013-03-28T23:59:59.000Z

422

Solar Thermal Energy Storage  

Science Journals Connector (OSTI)

Various types of thermal energy storage systems are introduced and their importance and desired characteristics are outlined. Sensible heat storage, which is one of the most commonly used storage systems in pract...

E. Paykoç; S. Kakaç

1987-01-01T23:59:59.000Z

423

Contact thermal lithography  

E-Print Network [OSTI]

Contact thermal lithography is a method for fabricating microscale patterns using heat transfer. In contrast to photolithography, where the minimum achievable feature size is proportional to the wavelength of light used ...

Schmidt, Aaron Jerome, 1979-

2004-01-01T23:59:59.000Z

424

Neutron stars - thermal emitters  

E-Print Network [OSTI]

Confronting theoretical models with observations of thermal radiation emitted by neutron stars is one of the most important ways to understand the properties of both, superdense matter in the interiors of the neutron stars and dense magnetized plasmas in their outer layers. Here we review the theory of thermal emission from the surface layers of strongly magnetized neutron stars, and the main properties of the observational data. In particular, we focus on the nearby sources for which a clear thermal component has been detected, without being contaminated by other emission processes (magnetosphere, accretion, nebulae). We also discuss the applications of the modern theoretical models of the formation of spectra of strongly magnetized neutron stars to the observed thermally emitting objects.

Potekhin, A Y; Pons, J A

2014-01-01T23:59:59.000Z

425

Texas Thermal Comfort Report  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

thermal comfort thermal comfort Too often, the systems in our houses are both physically and intellectually inaccessible. In the SNAP House, HVAC components are integrated into the overall structure, and act as an experiential threshold between public and private spaces. They are located in a central, structural chase that supports the clerestory and gives the systems a functional presence within the interior. Each individual component is contained within a single chase

426

Photovoltaic-thermal collectors  

DOE Patents [OSTI]

A photovoltaic-thermal solar cell including a semiconductor body having antireflective top and bottom surfaces and coated on each said surface with a patterned electrode covering less than 10% of the surface area. A thermal-absorbing surface is spaced apart from the bottom surface of the semiconductor and a heat-exchange fluid is passed between the bottom surface and the heat-absorbing surface.

Cox, III, Charles H. (Carlisle, MA)

1984-04-24T23:59:59.000Z

427

Dynamic modelling for thermal micro-actuators using thermal networks  

E-Print Network [OSTI]

Dynamic modelling for thermal micro-actuators using thermal networks Beatriz L´opez-Wallea,1 and analytical calculations. Key words: Micro-actuators, Thermal modelling, Electrical analogy, Thermal network 1 and MicroMechatronic Systems Department (AS2M), 24 rue Alain Savary, 25000 Besan¸con, France Abstract

Paris-Sud XI, Université de

428

Physics-Based Stress Corrosion Cracking Component Reliability Model cast in  

Broader source: Energy.gov (indexed) [DOE]

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

429

Physics-Based Stress Corrosion Cracking Component Reliability Model cast in  

Broader source: Energy.gov (indexed) [DOE]

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

430

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

Broader source: Energy.gov (indexed) [DOE]

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.

431

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

Broader source: Energy.gov (indexed) [DOE]

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

432

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

433

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

434

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

SciTech Connect (OSTI)

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

435

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

SciTech Connect (OSTI)

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

436

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

SciTech Connect (OSTI)

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

437

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

SciTech Connect (OSTI)

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

438

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

439

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

Broader source: Energy.gov (indexed) [DOE]

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

440

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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

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

SciTech Connect (OSTI)

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

442

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

SciTech Connect (OSTI)

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

443

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

SciTech Connect (OSTI)

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

444

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

445

E-Print Network 3.0 - analysis delays restart Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

of restart delay at 5 mins and the baselineg p g p y y y different groups Large systems on an internet... 300 400 500 600 700 ofJobs j Job Restart Delay specifies a...

446

Video-on-Demand Based on Delayed-Multicast: Algorithmic Support  

Science Journals Connector (OSTI)

...Article Video-on-Demand Based on Delayed-Multicast: Algorithmic Support N. Glinos...examine algorithmic issues related to the delayed multicast technique for video-on-demand delivery. We introduce the minimum total memory (MTM......

N. Glinos; D. B. Hoang; C. Nguyen; A. Symvonis

2004-01-01T23:59:59.000Z

447

A study of microstrip delay lines on high dielectric constant substrates  

E-Print Network [OSTI]

Microstrip delay lines have many possible applications in today's world of high frequency communications and radar systems. High dielectric constant (high-x) substrates allow for the building of miniaturized microstrip delay fines which...

Ashour, Thomas Joseph

2012-06-07T23:59:59.000Z

448

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

449

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

450

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

SciTech Connect (OSTI)

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

451

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

SciTech Connect (OSTI)

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

452

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

453

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

454

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

455

Robust chaos in autonomous time-delay system  

E-Print Network [OSTI]

We consider an autonomous system constructed as modification of the logistic differential equation with delay that generates successive trains of oscillations with phases evolving according to chaotic maps. The system contains two feedback loops characterized by two generally distinct retarding time parameters. In the case of their equality, chaotic dynamics is associated with the Smale-Williams attractor that corresponds to the double-expanding circle map for the phases of the carrier of the oscillatory trains. Alternatively, at appropriately chosen two different delays attractor is close to torus with Anosov dynamics on it as the phases are governed by the Fibonacci map. In both cases the attractors manifest robustness (absence of regularity windows under variation of parameters) and presumably relate to the class of structurally stable hyperbolic attractors.

D. S. Arzhanukhina; S. P. Kuznetsov

2014-04-16T23:59:59.000Z

456

Ignition Delay Times of Kerosene(Jet-A)/Air Mixtures  

E-Print Network [OSTI]

Ignition of Jet-A/air mixtures was studied behind reflected shock waves. Heating of shock tube at temperature of 150 C was used to prepare a homogeneous fuel mixture. Ignition delay times were measured from OH emission at 309 nm and from absorption of He-Ne laser radiation at 3.3922 micrometers. The conditions behind shock waves were calculated by one-dimensional shock wave theory from initial conditions T1, P1, mixture composition and incident shock wave velocity. The ignition delay times were obtained at two fixed pressures 10, 20 atm for lean, stoichiometric and rich mixtures (ER=0.5, 1, 2) at an overall temperature range of 1040-1380 K.

Zhukov, V P; Starikovskii, A Yu

2012-01-01T23:59:59.000Z

457

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

458

Immediate versus Delayed IUD Insertion after Uterine Aspiration  

Science Journals Connector (OSTI)

...continued use of the IUD, removal (and reason for removal), reinsertion after expulsion or removal, and adverse events, including perforation, pelvic infection, and subsequent unintended pregnancy. All analyses were performed in the intention-to-treat population. Additional analyses were restricted to... This trial showed that, as compared with delayed placement, immediate placement of an IUD after uterine aspiration resulted in slightly higher but statistically noninferior rates of expulsion, similar rates of other complications, and higher rates of IUD use at 6 months.

Bednarek P.H.; Creinin M.D.; Reeves M.F.

2011-06-09T23:59:59.000Z

459

Delayed neutrons from the neutron irradiation of ²³?U  

E-Print Network [OSTI]

&M University Nuclear Science Center Reactor (NSCR) to verify 235U delayed neutron emission rates. A custom device was created to accurately measure a sample’s pneumatic flight time and the Nuclear Science Center’s (NSC’s) pneumatic transfer system (PTS... parameter measurements, including two 235U samples, an array of three 3He cylindrical neutron detectors, signal processing circuitry, the PTS, a reactor core sensor and a computerized control system. A. Fissile Material Isotope Products Laboratories...

Heinrich, Aaron David

2008-10-10T23:59:59.000Z

460

Complex network synchronization of chaotic systems with delay coupling  

SciTech Connect (OSTI)

The study of complex networks enables us to understand the collective behavior of the interconnected elements and provides vast real time applications from biology to laser dynamics. In this paper, synchronization of complex network of chaotic systems has been studied. Every identical node in the complex network is assumed to be in Lur’e system form. In particular, delayed coupling has been assumed along with identical sector bounded nonlinear systems which are interconnected over network topology.

Theesar, S. Jeeva Sathya, E-mail: sjstheesar@gmail.com; Ratnavelu, K., E-mail: sjstheesar@gmail.com [Network Science Research Group, Institute of Mathematical Sciences, University of Malaya, 50603, Kuala Lumpur (Malaysia)

2014-03-05T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" 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.


461

Computing turn delay in city road network with GPS collected trajectories  

Science Journals Connector (OSTI)

In this paper, we aim to mine turn delay at different times and turn types in city road network based on personal GPS collected trajectories. We provide a method to effectively solve the problem for computing turn delay. By using this method, we can ... Keywords: community, data mining, gps trajectory, turn delay

Hengcai Zhang; Feng Lu; Liang Zhou; Yingying Duan

2011-09-01T23:59:59.000Z

462

Optimization of the Readout Electronics for Microchannel Plate Delay Line Anodes  

E-Print Network [OSTI]

Optimization of the Readout Electronics for Microchannel Plate Delay Line Anodes John Vallerga and future space missions use microchannel plate (MCP) detectors with delay line anode readouts (e.g. FUSE Telescope). Delay line anodes are used to measure the position of the centroid of the charge clouds

Colorado at Boulder, University of

463

The time-delayed inverted pendulum: Implications for human balance control  

E-Print Network [OSTI]

The time-delayed inverted pendulum: Implications for human balance control John Milton,1 Juan Luis May 2009; published online 29 June 2009 The inverted pendulum is frequently used as a starting point experimental paradigms of time-delayed balance control: 1 mechanical inverted time-delayed pendulum, 2 stick

Milton, John G.

464

Buffer Sizing for Minimum Energy-Delay Product by Using an Approximating Polynomial  

E-Print Network [OSTI]

Buffer Sizing for Minimum Energy-Delay Product by Using an Approximating Polynomial Chang Woo Kang to derive sizing rules for buffered chains, which optimize the overall energy-delay product. Categories result in a poor solution in terms of the energy-delay product. The focus of this work is on multi

Pedram, Massoud

465

Control of Delayed Recycling Systems with an Unstable Pole at Forward Path  

E-Print Network [OSTI]

Control of Delayed Recycling Systems with an Unstable Pole at Forward Path J. F. Marquez Rubio, B. del Muro Cu´ellar and Olivier Sename Abstract-- Unstable time delay system and recycling system pose a challenge problem in their own. When unstable time delay system have recycle the control problem becomes

Paris-Sud XI, Université de

466

Control of Delayed Recycling Systems with Unstable First Order Forward Loop  

E-Print Network [OSTI]

Control of Delayed Recycling Systems with Unstable First Order Forward Loop J. F. M Abstract Unstable time-delay systems and recycling systems are challenging problems for control analysis and design. When an unstable time-delay system has a recycle, its control problem becomes even more difficult

Boyer, Edmond

467

E-companion to: Rahmandad: Effect of Delays on Complexity of Organizational Learning Electronic Companion for  

E-Print Network [OSTI]

E-companion to: Rahmandad: Effect of Delays on Complexity of Organizational Learning 1 Electronic Companion for: Effect of Delays on Complexity of Organizational Learning Hazhir Rahmandad, hazhir@vt.edu 1: Effect of Delays on Complexity of Organizational Learning 2 An example would elaborate the workings

Rahmandad, Hazhir

468

A Low Power Thyristor-Based CMOS Programmable Delay Element Junmou Zhang  

E-Print Network [OSTI]

voltage to control the delay, exhibiting a low power supply noise sensitivity of 9.43% and a temperature. Simulation results show that the proposed delay element has a lower power supply and temperature sensitivity (¢ £ ¥ § © £ £ ) and is sensitive to power supply noise. Furthermore, the delay of an inverter chain is sensitive to temperature

Friedman, Eby G.

469

Femtosecond Time-Delay X-ray Holography  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Time-Delay X-ray Holography Time-Delay X-ray Holography X-ray free-electron lasers (XFELs) will produce photon pulses with a unique and desirable combination of properties. Their short X-ray wavelengths allow penetration into materials and the ability to probe structure at and below the nanometer scale. Their ultra-short duration gives information about this structure at the fundamental time-scales of atoms and molecules. The extreme intensity of the pulses will allow this information to be acquired in a single shot, so that these studies can be carried out on non-repeatable processes or on weakly-scattering objects that will be modified by the pulse. A fourth property of XFEL pulses is their high transverse coherence, which brings the promise of decades of innovation in visible optics to the X-ray regime, such as holography, interferometry, and laser-based imaging. Making an effective use of XFEL pulses, however, will benefit from innovations that are new to both X-ray science and coherent optics. One such innovation is the new method of time-delay X-ray holography [i], recently demonstrated at the FLASH FEL at DESY in Hamburg, to measure the evolution of objects irradiated by intense pulses.

470

Predicting Ignition Delay for Gas Turbine Fuel Flexibility  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Ignition Delay for Ignition Delay for Gas Turbine Fuel Flexibility 15 μm * Low emission combustion systems have been carefully optimized for natural gas * Future fuel diversity (including H2 containing fuels) may generate auto-ignition damage * Existing theories vary in predicting propensity for auto-ignition damage * Theory A vs Theory B shows factor of 100 difference-which is right? * UC Irvine improved and validated design tools for ignition delay allow designers to evaluate the risk for auto-ignition in advanced combustion systems with future fuels * Models are available to engine OEM's to shorten design cycle time and save $$ UC Irvine Scott Samuelsen / Vince McDonell #112 1000/T (1/K) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 τ [O 2 ] 0.5 [F] 0.25 (sec(mol/cm 3 ) 0.75 ) 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5

471

A Comparison of Cosmological Models Using Time Delay Lenses  

E-Print Network [OSTI]

The use of time-delay gravitational lenses to examine the cosmological expansion introduces a new standard ruler with which to test theoretical models. The sample suitable for this kind of work now includes 12 lens systems, which have thus far been used solely for optimizing the parameters of $\\Lambda$CDM. In this paper, we broaden the base of support for this new, important cosmic probe by using these observations to carry out a one-on-one comparison between {\\it competing} models. The currently available sample indicates a likelihood of $\\sim 70-80%$ that the $R_{\\rm h}=ct$ Universe is the correct cosmology versus $\\sim 20-30%$ for the standard model. This possibly interesting result reinforces the need to greatly expand the sample of time-delay lenses, e.g., with the successful implementation of the Dark Energy Survey, the VST ATLAS survey, and the Large Synoptic Survey Telescope. In anticipation of a greatly expanded catalog of time-delay lenses identified with these surveys, we have produced synthetic sa...

Wei, Jun-Jie; Melia, Fulvio

2014-01-01T23:59:59.000Z

472

THERMAL NEUTRON BACKSCATTER IMAGING.  

SciTech Connect (OSTI)

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

2004-10-16T23:59:59.000Z

473

Thermal ignition combustion system  

DOE Patents [OSTI]

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

1988-04-19T23:59:59.000Z

474

Scattering Solar Thermal Concentrators  

Broader source: Energy.gov [DOE]

"This fact sheet describes a scattering solar thermal concentrators project awarded under the DOE's 2012 SunShot Concentrating Solar Power R&D award program. The team, led by the Pennsylvania State University, is working to demonstrate a new, scattering-based approach to concentrating sunlight that aims to improve the overall performance and reliability of the collector field. The research team aims to show that scattering solar thermal collectors are capable of achieving optical performance equal to state-of-the-art parabolic trough systems, but with the added benefits of immunity to wind-load tracking error, more efficient land use, and utilization of stationary receivers."

475

Thermal ignition combustion system  

SciTech Connect (OSTI)

The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

Kamo, Roy (Columbus, IN); Kakwani, Ramesh M. (Columbus, IN); Valdmanis, Edgars (Columbus, IN); Woods, Melvins E. (Columbus, IN)

1988-01-01T23:59:59.000Z

476

Thermal ignition combustion system  

SciTech Connect (OSTI)

A thermal ignition combustion system adapted for use with an internal combustion engine is described comprising: (a) means for providing ignition chamber walls defining an ignition chamber, the chamber walls being made of a material having a thermal conductivity greater than 20 W/m/sup 0/C. and a specific heat greater than 480J/kg/sup 0/C., the ignition chamber being in constant communication with the main combustion chamber; (b) means for maintaining the temperature of the chamber walls above a threshold temperature capable of causing ignition of a fuel; and (c) means for conducting fuel to the ignition chamber.

Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

1988-04-19T23:59:59.000Z

477

Thermal test options  

SciTech Connect (OSTI)

Shipping containers for radioactive materials must be qualified to meet a thermal accident environment specified in regulations, such at Title 10, Code of Federal Regulations, Part 71. Aimed primarily at the shipping container design, this report discusses the thermal testing options available for meeting the regulatory requirements, and states the advantages and disadvantages of each approach. The principal options considered are testing with radiant heat, furnaces, and open pool fires. The report also identifies some of the facilities available and current contacts. Finally, the report makes some recommendations on the appropriate use of these different testing methods.

Koski, J.A.; Keltner, N.R.; Sobolik, K.B.

1993-02-01T23:59:59.000Z

478

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

SciTech Connect (OSTI)

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

479

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

480

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

Note: This page contains sample records for the topic "thermal cracking delayed" 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.


481

Keep Customers—and Energy—From Slipping Through the Cracks  

Broader source: Energy.gov [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.

482

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

483

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

484

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.

485

Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996  

SciTech Connect (OSTI)

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

486

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

487

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

488

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

489

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

490

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

491

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

492

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.

493

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, Jérôme

494

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

495

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

496

Features of hydrotreating catalytic cracking feed and heavy slow coking gas oils  

SciTech Connect (OSTI)

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

497

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

498

A case for Mars: A case for nuclear thermal rockets  

SciTech Connect (OSTI)

It is now possible to make general comparisons of candidate propulsion systems for human exploration of Mars. Preliminary review indicates that the propulsion system most likely to meet all mission requirements is the Nuclear Thermal Rocket (NTR). Advanced cryogenic chemical propulsion systems achieve a maximum specific impulse (Isp) of about 470 seconds. The Nuclear Engine for Rocket Vehicle Application (NERVA) program of the 1960's built engines with Isp's of about 825 seconds. Performance of an NTR depends on achievable materials temperatures, but materials has progressed significantly since the 1960's. Also, some of the current research undertaken to improve chemical rocket performance, such as aerobraking or schemes to minify payload, applies to an NTR as well, although it is not essential. The NTR is reusable, and can be developed into a complete space transportation system. Only 3--4% of the nuclear fuel would be used in a Mars mission, and an engine can be used until about 40% of the fuel is expended. Nuclear thermal rockets can take mankind to the moon, to Mars, and beyond, but development must begin now. There is potential for orderly growth into nuclear concepts far beyond NERVA. Using chemical propulsion for lunar missions and delaying NTR development will only result in higher costs and delayed or cancelled Mars missions.

Neuman, J.E.; Van Haaften, D.H.; Madsen, W.W.

1990-01-01T23:59:59.000Z

499

Stress Corrosion Cracking Response of 304 Stainless Steel in ASerated and Dearated Water  

SciTech Connect (OSTI)

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

500

Predictive wavefront control for Adaptive Optics with arbitrary control loop delays  

SciTech Connect (OSTI)

We present a modification of the closed-loop state space model for AO control which allows delays that are a non-integer multiple of the system frame rate. We derive the new forms of the Predictive Fourier Control Kalman filters for arbitrary delays and show that they are linear combinations of the whole-frame delay terms. This structure of the controller is independent of the delay. System stability margins and residual error variance both transition gracefully between integer-frame delays.

Poyneer, L A; Veran, J

2007-10-30T23:59:59.000Z