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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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they are not comprehensive nor are they the most current set.
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1

U.S. Refinery Thermal Cracking, Visbreaking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

2

Guam Refinery Thermal Cracking/Visbreaking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

Guam Refinery Thermal Cracking/Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

3

Guam Refinery Thermal Cracking/Other (including Gas Oil ...  

U.S. Energy Information Administration (EIA)

Guam Refinery Thermal Cracking/Other (including Gas Oil) Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

4

U.S. Refinery Thermal Cracking, Fluid Coking Downstream Charge ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Fluid Coking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

5

Puerto Rico Refinery Thermal Cracking/Visbreaking Downstream ...  

U.S. Energy Information Administration (EIA)

Puerto Rico Refinery Thermal Cracking/Visbreaking Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

6

U.S. Refinery Thermal Cracking, Other (including Gas Oil ...  

U.S. Energy Information Administration (EIA)

U.S. Refinery Thermal Cracking, Other (including Gas Oil) Downstream Charge Capacity as of January 1 (Barrels per Stream Day)

7

Thermal stress cracking and enhancement of heat extraction from fractured geothermal reservoirs  

DOE Green Energy (OSTI)

The effects of thermal stress cracking, upon heat extraction were studied. Very fundamental approximate analyses were performed to elucidate the mechanics of thermal stress cracking, and the main results are summarized.

Murphy, H.D.

1978-01-01T23:59:59.000Z

8

Thermal Cracking of Large-Diameter 706 Ingots  

Science Conference Proceedings (OSTI)

responsible for the cracking. The most plausible scenario is that residual stresses generated by ... Analysis of Heat Up for Homogenization. Finite Element Model.

9

Effect of Thermal-Mechanical Treatment on the Fatigue Crack ...  

Science Conference Proceedings (OSTI)

that fatigue crack propagation (FCP) resistance without holding time has no significant difference between three alloys with 718Plus being the best and 718 the...

10

Thermal stress cracking and the enhancement of heat extraction from fractured geothermal reservoirs  

DOE Green Energy (OSTI)

Given sufficient time, the extraction of heat from geothermal reservoirs formed by the hydraulic fracturing of competent rock will eventually result in the formation of thermal stress cracks in the reservoir. These cracks penetrate the rock in a manner such that the penetration-to-spacing ratio is approximately one. The penetration depends upon the extent of cooling and the square root of time. Initially then, the cracks are closely spaced and penetrate but little, so that a crazing pattern is apparent; but with increasing time some of these cracks, now more widely spaced, grow deeper. Eventually these larger cracks attain a critical aperture such that significant rates of water flow can be established within them and thus the newly created heat transfer area becomes useful for heat extraction. At the same time that cracks are forming within the main reservoir, thermal cracking also occurs in the wellbores that communicate with the reservoir. These cracks eventually convey water to and from the reservoir, thus leading to a decrease in the flow impedances that are often concentrated in the wellbore regions.

Murphy, H.D.

1978-04-01T23:59:59.000Z

11

Enhanced heat extraction from hot-dry-rock geothermal reservoirs due to interacting secondary thermal cracks. Final report  

DOE Green Energy (OSTI)

How the fluid circulating through the main hydraulic fracture and the thermally-induced secondary, growing, interacting cracks affects the time-varying temperature, deformations, stresses, thermal crack geometry, water flow rates through the main and thermal cracks, reservoir coolant outlet temperature, and reservoir thermal power of the cracked geothermal reservoir is investigated. First, a simplified version of the proposed hot-dry-rock reservoir is considered. A closed-form solution of the rock temperature without thermal crack was found and substituted into SAP-IV computer code to calculate the stresses. These stresses being superposed with earth stresses and fluid pressure were used in conjunction with the fracture mechanics criterion to determine the initiation of secondary thermal crack. After the initiation of secondary thermal crack, the rock temperature was then calculated by a two-dimensional heat conduction program AYER. The detailed procedures for carrying out these steps are listed. Solutions developed are applied to studying the time-varying temperature field, thermal stresses and crack geometry produced, and additional heat power generated in the reservoir. Conclusions were discussed and summarized. (MHR)

Hsu, Y.C.

1979-04-01T23:59:59.000Z

12

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.

13

Engineering methods for predicting productivity and longevity of hot-dry-rock geothermal reservoir in the presence of thermal cracks. Technical completion report  

DOE Green Energy (OSTI)

Additional heat extraction from geothermal energy reservioirs depends on the feasibility to extend the main, hydraulic fracture through secondary thermal cracks of the adjacent hot rock. When the main, hydraulic fracture is cooled sufficiently, these secondary thermal cracks are produced normal to the main fracture surface. As such, both the heat transfer surface area and heat energy available to the fluid circulating through the main, hydraulic fracture system increase. Methods for predicting the productivity and longevity of a geothermal reservoir were developed. A question is whether a significant long-term enhancement of the heat extraction process is achieved due to these secondary thermal cracks. In short, the objectives of this investigation are to study how the main, hydraulic fracture can be extended through these secondary thermal cracks of the rock, and to develop methods for predicting the productivity and longevity of a geothermal reservoir.

Hsu, Y.C.; Lu, Y.M.; Ju, F.D.; Dhingra, K.C.; Lu, Y.M.; Ju, F.D.; Dhingra, K.C.

1978-01-01T23:59:59.000Z

14

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

15

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

Science Conference Proceedings (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

16

Materials Reliability Program: Computer-Based NDE Training for Thermal Fatigue Cracking (MRP-36, Revision 2)  

Science Conference Proceedings (OSTI)

This product comes packaged together and contains both #1022875, Materials Reliability Program: NDE Technology for Detection of Thermal Fatigue Damage in Piping, (MRP-23, Revision 1) and Product #1024915, Computer-Based NDE Training for Thermal ...

2012-11-20T23:59:59.000Z

17

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

Science Conference Proceedings (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

18

Acoustic emission from thermal-gradient cracks in UO$sub 2$  

SciTech Connect

A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO$sub 2$ pellets. In the apparatus used for the present tests, two acoustic- emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic- emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO$sub 2$ pellets subjected to direct- electrical heating. 8 references. (auth)

Kennedy, C.R.; Kupperman, D.S.; Wrona, B.J.

1975-01-01T23:59:59.000Z

19

Vacuum Distillation  

U.S. Energy Information Administration (EIA) Indexed Site

Day) Process: Vacuum Distillation Thermal Cracking Thermal Cracking: Coking Thermal Cracking: Delayed Coking Thermal Cracking: Fluid Coking Thermal Cracking: Visbreaking Thermal...

20

Quench Cracking Characterization of Superalloys Using Fracture ...  

Science Conference Proceedings (OSTI)

When the on-cooling thermal stress. (load) accumulated to a certain point, quench cracking happened abruptly. Based on the precrack length, the thermal stress...

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

Electrochemical Interpretation of a Stress Corrosion Cracking of Thermally Treated Ni base Alloys in a Lead Contaminated Water  

SciTech Connect

Since the PbSCC(Lead stress corrosion cracking) of alloy 600 tubing materials was reported by Copson and Dean in 1965, the effect of lead on a corrosion film and cracking morphology have been continually debated. An electrochemical interaction of lead with the alloying elements of SG tubings was studied and the corrosion products were analyzed. It was found that lead enhanced the anodic dissolution of alloy 600 and alloy 690 in the electrochemical test. The lead preferentially dissolved the Cr from the corrosion film of alloy 600 and alloy 690 in alkaline water. The lead ion seemed to penetrate into the TG crack tip and react with the corrosion film. A selective Cr depletion was observed to weaken the stability of the passive film on the alloys. Whereas passivity of Ni became stable in lead containing solution, Cr and Fe passivity became unstable.

Hwang, Seong Sik; Lim, Yun Soo; Kim, Hong Pyo; Kim, Joung Soo; Thomas, Larry E.

2007-08-20T23:59:59.000Z

22

PICEP: Pipe Crack Evaluation Program  

Science Conference Proceedings (OSTI)

We describe a computer program that calculates the crack-opening area, the critical (stable) crack length and the two-phase flow rate through cracks in ductile stainless steel pipes and steam generator tubes. The program is useful in performing leak-before-break calculations in order to demonstrate detectable leak rates prior to a through-wall flaw reaching critical size. Necessary input to the code includes a definition of material properties, loads, thermal-hydraulic conditions, pipe geometry, and crack orientation. User information is provided in the report.

Norris, D.; Okamoto, A.; Chexal, B.; Griesbach, T.

1984-08-01T23:59:59.000Z

23

Shale oil cracking. 1. Kinetics  

DOE Green Energy (OSTI)

Experiments were conducted to determine kinetics for thermal cracking of shale oil vapor over shale. Cracking temperatures of 504 to 610/sup 0/C and residence times of 2 to 11 seconds were used. A first-order Arrhenius rate expression and stoichiometry were obtained. Also observed were changes in the oil quality. Cracking decreased the H/C ratio, increased the nitrogen content, and decreased the pour point of the oil. Gas-phase oil cracking is contrasted to liquid-phase oil coking as a loss mechanism in oil-shale retorting.

Burnham, A.K.; Taylor, J.R.

1979-10-01T23:59:59.000Z

24

A thermal active restrained shrinkage ring test to study the early age concrete behaviour of massive structures  

Science Conference Proceedings (OSTI)

In massive concrete structures, cracking may occur during hardening, especially if autogenous and thermal strains are restrained. The concrete permeability due to this cracking may rise significantly and thus increase leakage (in tank, nuclear containment...) and reduce the durability. The restrained shrinkage ring test is used to study the early age concrete behaviour (delayed strains evolution and cracking). This test shows, at 20 {sup o}C and without drying, for a concrete mix which is representative of a French nuclear power plant containment vessel (w/c ratio equal to 0.57), that the amplitude of autogenous shrinkage (about 40 {mu}m/m for the studied concrete mix) is not high enough to cause cracking. Indeed, in this configuration, thermal shrinkage is not significant, whereas this is a major concern for massive structures. Therefore, an active test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the classical restrained shrinkage ring test. It allows to take into account both autogenous and thermal shrinkages. Its principle is to create the thermal strain effects by increasing the temperature of the brass ring (by a fluid circulation) in order to expand it. With this test, the early age cracking due to restrained shrinkage, the influence of reinforcement and construction joints have been experimentally studied. It shows that, as expected, reinforcement leads to an increase of the number of cracks but a decrease of crack widths. Moreover, cracking occurs preferentially at the construction joint.

Briffaut, M. [LMT/ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Institut de radioprotection et de surete nucleaire, Fontenay-aux-Roses (France); Benboudjema, F. [LMT/ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Torrenti, J.M., E-mail: jean-michel.torrenti@lcpc.f [Universite Paris Est, Laboratoire central des ponts et chaussees, Paris (France); Nahas, G. [LMT/ENS Cachan/CNRS UMR8535/UPMC/PRES UniverSud Paris, Cachan (France); Institut de radioprotection et de surete nucleaire, Fontenay-aux-Roses (France)

2011-01-15T23:59:59.000Z

25

Cracking knuckles  

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

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

26

Hydrogen Assisted Cracking  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking (EAC): Laboratory Research and Field Experiences: Hydrogen Assisted Cracking Program Organizers: Suresh Divi, TIMET

27

Thermal Cracking - Energy Information Administration  

U.S. Energy Information Administration (EIA)

-No Data Reported; --= Not Applicable; NA = Not Available; W = Withheld to avoid disclosure of individual company data. Notes: See Definitions ...

28

Creep Crack Growth  

Science Conference Proceedings (OSTI)

Table 3   Creep crack growth constants b and m for various ferritic steels...and Banerji, ??Creep Crack Growth Behavior

29

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

30

PICEP: Pipe Crack Evaluation Program (Revision 1): Special report  

Science Conference Proceedings (OSTI)

This report describes software for calculating single- or two-phase flow through cracks in pipes and steam generator tubes. Options are available for calculating the crack-opening area and the critical (stable) crack length. The program is useful in performing leak-before-break analysis to demonstrate detectable leak rates prior to crack growth instability. Input to the code includes material properties, loads, thermal-hydraulic conditions, pipe geometry, and crack type and orientation. Theory and user information are provided in this report. 16 refs., 7 figs.

Norris, D.M.; Chexal, B.

1987-12-01T23:59:59.000Z

31

Environmentally Assisted Cracking: Nuclear  

Science Conference Proceedings (OSTI)

About this Symposium. Meeting, Materials Science & Technology 2014. Symposium, Environmentally Assisted Cracking: Nuclear. Sponsorship. Organizer(s)...

32

Cracks Cleave Crystals  

E-Print Network (OSTI)

The problem of finding what direction cracks should move is not completely solved. A commonly accepted way to predict crack directions is by computing the density of elastic potential energy stored well away from the crack tip, and finding a direction of crack motion to maximize the consumption of this energy. I provide here a specific case where this rule fails. The example is of a crack in a crystal. It fractures along a crystal plane, rather than in the direction normally predicted to release the most energy. Thus, a correct equation of motion for brittle cracks must take into account both energy flows that are described in conventional continuum theories and details of the environment near the tip that are not.

Michael Marder

2004-03-05T23:59:59.000Z

33

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

Science Conference Proceedings (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 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

34

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

SciTech Connect

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

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

2009-04-23T23:59:59.000Z

35

Environmentally assisted cracking in light water reactors.  

DOE Green Energy (OSTI)

This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from January to December 2002. Topics that have been investigated include: (a) environmental effects on fatigue crack initiation in carbon and low-alloy steels and austenitic stainless steels (SSs), (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs in BWRs, (c) evaluation of causes and mechanisms of irradiation-assisted cracking of austenitic SS in PWRs, and (d) cracking in Ni-alloys and welds. A critical review of the ASME Code fatigue design margins and an assessment of the conservation in the current choice of design margins are presented. The existing fatigue {var_epsilon}-N data have been evaluated to define the effects of key material, loading, and environmental parameters on the fatigue lives of carbon and low-alloy steels and austenitic SSs. Experimental data are presented on the effects of surface roughness on fatigue crack initiation in these materials in air and LWR environments. Crack growth tests were performed in BWR environments on SSs irradiated to 0.9 and 2.0 x 10{sup 21} n x cm{sup -2}. The crack growth rates (CGRs) of the irradiated steels are a factor of {approx}5 higher than the disposition curve proposed in NUREG-0313 for thermally sensitized materials. The CGRs decreased by an order of magnitude in low-dissolved oxygen (DO) environments. Slow-strain-rate tensile (SSRT) tests were conducted in high-purity 289 C water on steels irradiated to {approx}3 dpa. The bulk S content correlated well with the susceptibility to intergranular SCC in 289 C water. The IASCC susceptibility of SSs that contain >0.003 wt. % S increased drastically. bend tests in inert environments at 23 C were conducted on broken pieces of SSRT specimens and on unirradiated specimens of the same materials after hydrogen charging. The results of the tests and a review of other data in the literature indicate that IASCC in 289 C water is dominated by a crack-tip grain-boundary process that involves S. An initial IASCC model has been proposed. A crack growth test was completed on mill annealed Alloy 600 in high-purity water at 289 C and 320 C under various environmental and loading conditions. The results from this test are compared with data obtained earlier on several other heats of Alloy 600.

Chopra, O. K.; Chung, H. M.; Clark, R. W.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.; Strain, R. V.

2007-11-06T23:59:59.000Z

36

LPG storage vessel cracking experience  

SciTech Connect

In order to evaluate liquefied petroleum gas (LPG) handling and storage hazards, Caltex Petroleum Corp. (Dallas) surveyed several installations for storage vessel cracking problems. Cracking was found in approximately one-third of the storage vessels. In most cases, the cracking appeared to be due to original fabrication problems and could be removed without compromising the pressure containment. Several in-service cracking problems found were due to exposure to wet hydrogen sulfide. Various procedures were tried in order to minimize the in-service cracking potential. One sphere was condemned because of extensive subsurface cracking. This article's recommendations concern minimizing cracking on new and existing LPG storage vessels.

Cantwell, J.E. (Caltex Petroleum Corp., P.O. Box 619500, Dallas, TX (US))

1988-10-01T23:59:59.000Z

37

LPG storage vessel cracking experience  

SciTech Connect

As part of an overall company program to evaluate LPG handling and storage hazards the authors surveyed several installations for storage vessel cracking problems. Cracking was found in approximately one third of the storage vessels. In most cases the cracking appeared due to original fabrication problems and could be removed without compromising the pressure containment. Several in-service cracking problems due to exposure to wet hydrogen sulfide were found. Various procedures were tried in order to minimize the in-service cracking potential. One sphere was condemned because of extensive subsurface cracking. Recommendations are made to minimize cracking on new and existing LPG storage vessels.

Cantwell, J.E.

1988-01-01T23:59:59.000Z

38

The Impact of Delaying the Delay Announcements  

Science Conference Proceedings (OSTI)

Many service providers use delay announcements to inform customers of anticipated delays. However, this information is usually not provided immediately but after a short period of time (spent either waiting or occupied by the system). The focus of this ... Keywords: Noncooperative game, access control, admission control, queues, real-time information, strategic consumer, tandem queues

Gad Allon; Achal Bassamboo

2011-09-01T23:59:59.000Z

39

Prediction of Reflection Cracking in Hot Mix Asphalt Overlays  

E-Print Network (OSTI)

Reflection cracking is one of the main distresses in hot-mix asphalt (HMA) overlays. It has been a serious concern since early in the 20th century. Since then, several models have been developed to predict the extent and severity of reflection cracking in HMA overlays. However, only limited research has been performed to evaluate and calibrate these models. In this dissertation, mechanistic-based models are calibrated to field data of over 400 overlay test sections to produce a design process for predicting reflection cracks. Three cracking mechanisms: bending, shearing traffic stresses, and thermal stress are taken into account to evaluate the rate of growth of the three increasing levels of distress severity: low, medium, and high. The cumulative damage done by all three cracking mechanisms is used to predict the number of days for the reflection crack to reach the surface of the overlay. The result of this calculation is calibrated to the observed field data (severity and extent) which has been fitted with an S-shaped curve. In the mechanistic computations, material properties and fracture-related stress intensity factors are generated using efficient Artificial Neural Network (ANN) algorithms. In the bending and shearing traffic stress models, the traffic was represented by axle load spectra. In the thermal stress model, a recently developed temperature model was used to predict the temperature at the crack tips. This process was developed to analyze various overlay structures. HMA overlays over either asphalt pavement or jointed concrete pavement in all four major climatic zones are discussed in this dissertation. The results of this calculated mechanistic approach showed its ability to efficiently reproduce field observations of the growth, extent, and severity of reflection cracking. The most important contribution to crack growth was found to be thermal stress. The computer running time for a twenty-year prediction of a typical overlay was between one and four minutes.

Tsai, Fang-Ling

2010-12-01T23:59:59.000Z

40

Thermal Cracking Visbreaking Downstream Charge Capacity  

U.S. Energy Information Administration (EIA)

-No Data Reported; --= Not Applicable; NA = Not Available; W = Withheld to avoid disclosure of individual company data. Notes: See Definitions ...

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

Corrosion Fatigue Crack Growth and Stress-Corrosion Cracking in ...  

Science Conference Proceedings (OSTI)

Abstract Scope, The high stress ratio (R=0.85) corrosion fatigue crack growth kinetics and stress-corrosion cracking resistance of sensitized (70-175 C up to...

42

Blunt-crack band propagation in finite-element analysis for concrete structures. [LMFBR  

SciTech Connect

The knowledge of concrete fracture is needed in nuclear reactor safety. The question of safety arises from the potential of concrete to crack under thermal loading. It has been postulated that structural concrete could be exposed to very high temperature, which may result from hot reactor coolant or even core debris coming in direct contact with the concrete. The utilization of the blunt crack approach for simulating concrete cracking in a general-purpose code is explored. The difficulties encountered in establishing the proper direction of crack propagation in an arbitrary discretization are described. Crack propagation is considered within the context of two types of solution techniques: (1) implicit solution of the static crack advance, and (2) explicit time integration using a dynamic relaxation technique to simulate the static crack advance. Also, in both solution techniques an elastic model is used to characterize the concrete.

Pfeiffer, P.A.; Bazant, Z.P.; Marchertas, A.H.

1983-01-01T23:59:59.000Z

43

Catalytic cracking process  

Science Conference Proceedings (OSTI)

Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

Lokhandwala, Kaaeid A. (Union City, CA); Baker, Richard W. (Palo Alto, CA)

2001-01-01T23:59:59.000Z

44

Analysis of Cracked Pipe Weldments  

Science Conference Proceedings (OSTI)

EPRI estimation formulas for predicting loads necessary for crack initiation and instability can facilitate leak-before-break analysis of cracked nuclear piping. Finite-element calculations carried out in this study verified the accuracy of these formulas for analyzing through-the-wall cracks in bimetallic weldments.

1987-02-01T23:59:59.000Z

45

VARIABLE TIME DELAY MEANS  

DOE Patents (OSTI)

An electrically variable time delay line is described which may be readily controlled simuitaneously with variable impedance matching means coupied thereto such that reflections are prevented. Broadly, the delay line includes a signal winding about a magnetic core whose permeability is electrically variable. Inasmuch as the inductance of the line varies directly with the permeability, the time delay and characteristic impedance of the line both vary as the square root of the permeability. Consequently, impedance matching means may be varied similariy and simultaneously w:th the electrically variable permeability to match the line impedance over the entire range of time delay whereby reflections are prevented.

Clemensen, R.E.

1959-11-01T23:59:59.000Z

46

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

47

Digital time delay  

DOE Patents (OSTI)

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay provides a first output signal at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits latch the high resolution data to form a first synchronizing data set. A selected time interval has been preset to internal counters and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses count down the counters to generate an internal pulse delayed by an internal which is functionally related to the preset time interval. A second LCD corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD to generate a second set of synchronizing data which is complementary with the first set of synchronizing data for presentation to logic circuits. The logic circuits further delay the internal output signal with the internal pulses. The final delayed output signal thereafter enables the output pulse generator to produce the desired output pulse at the preset time delay interval following input of the trigger pulse.

Martin, A.D.

1986-05-09T23:59:59.000Z

48

Analysis of Crack Growth Data  

Science Conference Proceedings (OSTI)

Table 3   Methods for calculating crack growth rates...the derivative at the midpoint of a data set. These methods use

49

Environmentally Assisted Cracking of Materials  

Science Conference Proceedings (OSTI)

Development of Alternating Current Potential Drop (ACPD) method for the detection of Primary Water Stress Corrosion Cracking initiation in Stainless Steels and...

50

Environmentally Assisted Cracking of Materials  

Science Conference Proceedings (OSTI)

In-Situ Repairs of Oil Industry Pipelines, Tanks and Vessels by Welding Using Metal Arc Welding Under Oil (MAW-UO) Interpretation of Crack Initiation and...

51

Hydrogen sulfide stress corrosion cracking in materials for geothermal power  

DOE Green Energy (OSTI)

Studies to evaluate the performance of alloys used in geothermal power systems are reported. Alloys which are commercially available and those which have modified metallurgical structures and/or composition modifications were tested to determine the corrosive effects of the H/sub 2/S and thermal environments in geothermal fluids. Hydrogen embrittlement and sulfide stress corrosion cracking were tested. Test results showing the effects of alloy composition, tempering temperatures, fluid temperature and salt content, and ageing on sulfide stress cracking are tabulated. (LCL)

Hehemann, R.F.; Troiano, A.R.; Abu-Khater, B.; Ferrigno, S.

1976-01-01T23:59:59.000Z

52

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

53

Effect of Thermomechanical Processing on Fatigue Crack ...  

Science Conference Proceedings (OSTI)

gechanical driving force such as crack opening distance (COD) . However, at hold time loading, the crack growth rate is drastically decreased with an increase of...

54

Thermal Shock-resistant Cement  

SciTech Connect

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 cements 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

55

Fundamentals of Delayed Coking Joint Industry Project  

SciTech Connect

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

56

Fundamentals of Delayed Coking Joint Industry Project  

SciTech Connect

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

57

Stress corrosion cracking of austenitic stainless steel core internal welds.  

SciTech Connect

Microstructural analyses by several advanced metallographic techniques were conducted on austenitic stainless steel mockup and core shroud welds that had cracked in boiling water reactors. Contrary to previous beliefs, heat-affected zones of the cracked Type 304L, as well as 304 SS core shroud welds and mockup shielded-metal-arc welds, were free of grain-boundary carbides, which shows that core shroud failure cannot be explained by classical intergranular stress corrosion cracking. Neither martensite nor delta-ferrite films were present on the grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the core shroud welds were significantly contaminated by oxygen and fluorine, which migrate to grain boundaries. Significant oxygen contamination seems to promote fluorine contamination and suppress thermal sensitization. Results of slow-strain-rate tensile tests also indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of core shroud welds.

Chung, H. M.; Park, J.-H.; Ruther, W. E.; Sanecki, J. E.; Strain, R. V.; Zaluzec, N. J.

1999-04-14T23:59:59.000Z

58

Intergranular Stress Corrosion Cracking (IGSCC) Mechanism of ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2012. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title...

59

Weldability Tests for Evaluating Cracking Susceptibility  

Science Conference Proceedings (OSTI)

Table 2   Weldability tests used to evaluate susceptibility to cracking...used to evaluate susceptibility to cracking Test Fields of use Controllable variables Type of data Specialized equipment Relative cost Lehigh restraint test Weld metal hot and cold cracking, root cracking,

60

Congestion delays at hub airports  

E-Print Network (OSTI)

A deterministic model was developed to study the effects of inefficient scheduling on flight delays at hub airports. The model bases the delay calculation on published schedule data and on user-defined airport capacities. ...

St. George, Martin J.

1986-01-01T23:59:59.000Z

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

Origin of undesirable cracks during layer transfer  

E-Print Network (OSTI)

We investigate the origin of undesirable transverse cracks often observed in thin films obtained by the layer transfer technique. During this process, two crystals bonded to each other containing a weak plan produced by ion implantation are heated to let a thin layer of one of the material on the other. The level of stress imposed on the film during the heating phase due to the mismatch of thermal expansion coefficients of the substrate and the film is shown to be the relevant parameter of the problem. In particular, it is shown that if the film is submitted to a tensile stress, the microcracks produced by ion implantation are not stable and deviate from their straight trajectory making the layer transfer process impossible. However, if the compressive stress exceeds a threshold value, after layer transfer, the film can buckle and delaminate, leading to transverse cracks induced by bending. As a result, we show that the imposed stress \\sigma_m - or equivalently the heating temperature - must be within the ran...

Ponson, Laurent; Atwater, Harry; Ravichandran, Guruswami; Bhattacharya, Kaushik

2008-01-01T23:59:59.000Z

62

Stable crack growth estimates based on effective crack length and crack-opening displacements  

SciTech Connect

A method was developed for estimating the amount of stable crack growth that has occurred in a fracture toughness specimen that were loaded into the plastic range and for which only a monotonically increasing load-displacement curve was measured. The method was applied to data from several pressure vessel steels. The resulting J vs ..delta..a values compare favorably with a resistance curve obtained by the multiple specimen heat-tinting technique for A533, Grade B, Class 1 steel. The method for estimating stable crack growth uses several existing concepts heretofore mainly used separately. These concepts include an approximate expression for J for the compact specimen proposed by Andrews, the effective crack length concept of McCabe and Landes, the UK representation of the crack profile as a pair of straight lines intersecting at a hinge point, and Well's expression, J = m sigma/sub y/delta, for relating the crack-opening displacement to the value of J. The value of the constraint factor, m, at the advancing crack tip is estimated by means of a relation between ductility and fracture toughness. When calculated with respect to the COD at the original fatigue crack tip, the constraint factor, m/sub o/, is found to have a value consistently close to 2.0 for compact and precracked Charpy specimens. The method of estimation requires no auxiliary load-deflection measurements or calculations, and so permits single specimen estimates of stable crack growth to be made without the necessity of making high precision unloading compliance measurements.

Merkle, J.G.; Hudson, C.E.

1979-01-01T23:59:59.000Z

63

Aspects of Stress Corrosion Cracking Relevant to Irradiation-Assisted Stress Corrosion Cracking (IASCC)  

Science Conference Proceedings (OSTI)

This report provides a comprehensive survey of crack initiation issues in irradiation-assisted stress corrosion cracking (IASCC). It considers microcracking on smooth specimens and the transition from microcracking to stable crack propagation.

2002-05-02T23:59:59.000Z

64

Programmable Differential Delay Circuit With Fine Delay Adjustment  

DOE Patents (OSTI)

Circuitry that provides additional delay to early arriving signals such that all data signals arrive at a receiving latch with same path delay. The delay of a forwarded clock reference is also controlled such that the capturing clock edge will be optimally positioned near quadrature (depending on latch setup/hold requirements). The circuitry continuously adapts to data and clock path delay changes and digital filtering of phase measurements reduce errors brought on by jittering data edges. The circuitry utilizes only the minimum amount of delay necessary to achieve objective thereby limiting any unintended jitter. Particularly, this programmable differential delay circuit with fine delay adjustment is designed to allow the skew between ASICS to be minimized. This includes skew between data bits, between data bits and clocks as well as minimizing the overall skew in a channel between ASICS.

DeRyckere, John F. (Eau Claire, WI); Jenkins, Philip Nord (Eau Claire, WI); Cornett, Frank Nolan (Chippewa Falls, WI)

2002-07-09T23:59:59.000Z

65

Uncertainty evaluation of delayed neutron decay parameters  

E-Print Network (OSTI)

In a nuclear reactor, delayed neutrons play a critical role in sustaining a controllable chain reaction. Delayed neutrons relative yields and decay constants are very important for modeling reactivity control and have been studied for decades. Researchers have tried different experimental and numerical methods to assess these delayed neutron parameters. The reported parameter values vary widely, much more than the small statistical errors reported with these parameters. Interestingly, the reported 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 methods used to extract the delayed neutron parameter from the measured data, including Matrix Inverse, Levenberg-Marquardt, and Quasi-Newton methods, were studied extensively using simulated delayed neutron data. This simulated data was Poisson distributed around Keepins theoretical data. The extraction methods produced totally different results for the same data set, and some of the above numerical methods could not even find solutions for some data sets. Further investigation found that ill-conditioned matrices in the objective function were the reason for the inconsistent results. To find a reasonable solution with small variation, a regularization parameter was introduced using a numerical method called Ridge Regression. The results from the Ridge Regression method, in terms of goodness of fit to the data, were good and often better than the other methods. Due to the introduction of a regularization number in the algorithm, the fitted result contains a small additional bias, but this method can guarantee convergence no matter how large the coefficient matrix condition number. Both saturation and pulse modes were simulated to focus on different groups. Some of the factors that affect the solution stability were investigated including initial count rate, sample flight time, initial guess values. Finally, because comparing reported delayed neutron parameters among different experiments is useless to determine if their data actually differs, methods are proposed that can be used to compare the delayed neutron data sets.

Wang, Jinkai

2008-12-01T23:59:59.000Z

66

Predicting the Behavior of Small Fatigue Cracks - Programmaster.org  

Science Conference Proceedings (OSTI)

are effective at providing crack propagation resistance in many materials and composites, these mechanisms result in a crack size dependence (i.e., small crack...

67

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

68

Intergranular Cracking of Brass Sprinkler Heads  

Science Conference Proceedings (OSTI)

Symposium, Charles R. Morin Memorial Symposium on Failure Analysis and Prevention. Presentation Title, Intergranular Cracking of Brass Sprinkler Heads.

69

Delayed cure bismaleimide resins  

DOE Patents (OSTI)

Polybismaleimides prepared by delayed curing of bis-imides having the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, Cl or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the --(CH.sub.2).sub.n -- group, optionally, is substituted by 1-3 methyl groups or by fluorine.

Adams, Johnnie E. (Grandview, MO); Jamieson, Donald R. (Merriam, KS)

1984-08-07T23:59:59.000Z

70

Assessment of Cracks in Stress Concentration Regions with Localized Plastic Zones  

SciTech Connect

Marty brittle fracture evaluation procedures include plasticity corrections to elastically computed stress intensity factors. These corrections, which are based on the existence of a plastic zone in the vicinity of the crack tip, can overestimate the plasticity effect for a crack embedded in a stress concentration region in which the elastically computed stress exceeds the yield strength of the material in a localized zone. The interactions between the crack, which acts to relieve the high stresses driving the crack, plasticity effects in the stress concentration region, and the nature and source of the loading are examined by formulating explicit flaw finite element models for a crack emanating from the root of a notch located in a panel subject to an applied tensile stress. The results of these calculations provide conditions under which a crack-tip plasticity correction based on the Irwin plastic zone size overestimates the plasticity effect. A failure assessment diagram (FAD) curve is used to characterize the effect of plasticity on the crack driving force and to define a less restrictive plasticity correction for cracks at notch roots when load-controlled boundary conditions are imposed. The explicit flaw finite element results also demonstrate that stress intensity factors associated with load-controlled boundary conditions, such as those inherent in the ASME Boiler and Pressure Vessel Code as well as in most handbooks of stress intensity factors, can be much higher than those associated with displacement-controlled conditions, such as those that produce residual or thermal stresses. Under certain conditions, the inclusion of plasticity effects for cracks loaded by displacement-controlled boundary conditions reduces the crack driving force thus justifying the elimination of a plasticity correction for such loadings. The results of this study form the basis for removing unnecessary conservatism from flaw evaluation procedures that utilize plasticity corrections.

Friedman, E.

1998-11-25T23:59:59.000Z

71

Stress Corrosion Cracking of Brass: A Comparative Study on ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

72

On the Fatigue Crack Propagation Behavior of Superalloys at ...  

Science Conference Proceedings (OSTI)

ON THE FATIGUE CRACK PROPAGATION BEHAVIOR. OF SUPERALLOYS AT ... the FCP resistance of superalloys ... lead to poor crack propagation behavior.

73

Environmental Effects on Fatigue Crack Growth Rates in Sour ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

74

Environmental Cracking Resistance of High Nickel Alloys (CRAs  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

75

On Modeling Hydrogen-Induced Intergranular Cracking under ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

76

Corrosion and Cracking of Carbon Steel in Fuel Grade Ethanol  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

77

Evaluation of the Susceptibility to Hydrogen Assisted Cracking in ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

78

PRECISION TIME-DELAY CIRCUIT  

DOE Patents (OSTI)

A tine-delay circuit which produces a delay time in d. The circuit a capacitor, an te back resistance, connected serially with the anode of the diode going to ground. At the start of the time delay a negative stepfunction is applied to the series circuit and initiates a half-cycle transient oscillatory voltage terminated by a transient oscillatory voltage of substantially higher frequency. The output of the delay circuit is taken at the junction of the inductor and diode where a sudden voltage rise appears after the initiation of the higher frequency transient oscillations.

Creveling, R.

1959-03-17T23:59:59.000Z

79

Fundamentals of Delayed Coking Joint Industry Project  

SciTech Connect

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. The following deliverables are scheduled from the two projects of the three-year JIP: (1) A novel method for enhancing liquid yields from delayed cokers and data that provide insight as to the optimum temperature to remove hydrogen sulfide from furnace gases. (2) An understanding of what causes foaming in c

Michael Volk Jr; Keith Wisecarver

2005-10-01T23:59:59.000Z

80

Modeling of solar receiver for cracking of liquid petroleum gas  

SciTech Connect

The paper presents the model of an industrial solar receiver/reactor for thermal cracking of liquid petroleum gas (LPG) at the typical temperature range of 800--850 C. The concentrated solar radiation enters the receiver located on the ground and provided with a compound parabolic concentrator (CPC) at the ceiling. This is achieved with a reflecting solar tower. The radiative model uses the classical concept of equivalent gray plane to represent a panel of 40 cracking tubes placed in parallel of a refractory wall of the receiver. The radiative flux distribution on each wall is calculated and the chemistry in each reactor tube is evaluated until convergence is achieved. The design of an industrial size receiver, its behavior, and performance have been evaluated using this model. The computer program based on this model was run for a variety of flow conditions, feed compositions, and pressures.

Segal, A.; Epstein, M. [Weizmann Inst. of Science, Rehovot (Israel). Solar Research Facilities Unit

1997-02-01T23:59:59.000Z

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.


81

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

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

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

82

CRACK GROWTH RESPONSE OF ALLOY 690 IN SIMULATED PWR PRIMARY WATER  

SciTech Connect

The stress corrosion crack growth response of three extruded alloy 690 CRDM tube heats was investigated in several thermomechanical conditions. Extremely low propagation rates (< 1 x 10{sup -9} mm/s) were observed under constant stress intensity factor (K) loading at 325-350 C in the as-received, thermally treated (TT) materials despite using a variety of transitioning techniques. Post-test observation of the crack-growth surfaces revealed only isolated intergranular (IG) cracking. One-dimensional cold rolling to 17% reduction and testing in the S-L orientation did not promote enhanced stress corrosion rates. However, somewhat higher propagation rates were observed in a 30% cold-rolled alloy 690TT specimen tested in the T-L orientation. Cracking of the cold-rolled material was promoted on grain boundaries oriented parallel to the rolling plane with the % IG increasing with the amount of cold rolling.

Toloczko, Mychailo B.; Bruemmer, Stephen M.

2009-12-01T23:59:59.000Z

83

Prediction of crack propagation paths in the unit cell of SOFC stacks  

DOE Green Energy (OSTI)

Planar Solid Oxide Fuel Cells (SOFC) stacks are multi-material layered systems with different thermo-mechanical properties. Due to their severe thermal loading, these layers have to meet high demands to preserve their mechanical integrity without initiation and propagation of fracture. Here, we focus on a typical unit cell of the stack which consists of positive electrode-electrolyte-negative electrode (PEN). Based on the mechanical properties of each layer and their interfaces, an energy criterion as a function of crack length is used for the prediction of possible crack extensions in the PEN. This criterion is a pure local criterion, independent of applied loads and geometry of the specimen. An analysis of the competition between crack deflections in the interfaces and crack penetration in layers is presented.

Joulaee, N.; Makradi, A.; Ahzi, Said; Khaleel, Mohammad A.; Koeppel, Brian J.

2009-08-01T23:59:59.000Z

84

High resolution digital delay timer  

DOE Patents (OSTI)

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

Martin, Albert D. (Los Alamos, NM)

1988-01-01T23:59:59.000Z

85

Reduction of Delayed Fracture Susceptibility through Increased Si ...  

Science Conference Proceedings (OSTI)

Environmentally Assisted Cracking of Carbon Steel in High Temperature Geothermal Well Evaluation of the Susceptibility to Hydrogen Assisted Cracking in...

86

The influence of cracks in rotating shafts  

E-Print Network (OSTI)

In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

Jean-Jacques Sinou; A. W. Lees

2008-01-19T23:59:59.000Z

87

Revisiting TCP congestion control using delay gradients  

Science Conference Proceedings (OSTI)

Traditional loss-based TCP congestion control (CC) tends to induce high queuing delays and perform badly across paths containing links that exhibit packet losses unrelated to congestion. Delay-based TCP CC algorithms infer congestion from delay measurements ...

David A. Hayes; Grenville Armitage

2011-05-01T23:59:59.000Z

88

Communication link with constant delay  

DOE Patents (OSTI)

This is a technique that enables the transmission of data on a transmission and reception of data. A programmable delay element is fixed in the transmission line and programmed to add or subtract an appropriate amount of delay to compensate for changes and thereby maintain the overall delay at a predetermined value. The electrical transmission system is coupled via an optical coupler to a fiber optic line. The destination of the fiber optic line is equipped with a means for reflecting a portion of the transmitted information so as to provide an indication of a round trip delay at the transmitting end. By using continuous time compensation, the communication does not distort information as a phase compensated system would do, and also allows higher accuracy for synchronization between transmitter and receiver.

Miller, S.A.

1991-01-01T23:59:59.000Z

89

Improved Mapping of Tropospheric Delays  

Science Conference Proceedings (OSTI)

The authors compare several methods to map the a priori tropospheric delay of global positioning system (GPS) signals from the zenith direction to lower elevations. This is commonly achieved with so-called mapping functions. Dry mapping functions ...

Christian Rocken; Sergey Sokolovskiy; James M. Johnson; Doug Hunt

2001-07-01T23:59:59.000Z

90

Stress Corrosion Cracking - Programmaster.org  

Science Conference Proceedings (OSTI)

Oct 28, 2013 ... Atomic Ordering in Alloy 690 and Its Effect on Long-term Structural Stability and Stress Corrosion Cracking Susceptibility: Michael Kaufman1;...

91

Creep Crack Growth Behaviour of Alloy 718  

Science Conference Proceedings (OSTI)

its creep crack growth is controlled by stress intensity factor regardless of load level .... energy. Since vacancies diffuse from a low strain energy position to a high...

92

Evaluation of Stress-Corrosion Cracking  

Science Conference Proceedings (OSTI)

Table 3   Stress-corrosion cracking of selected material systems...chlorides, seawater Oil/gas production and transmission, oil refining,

93

Crystallographic Orientation Dependence of Fatigue Crack ...  

Science Conference Proceedings (OSTI)

In the present study, fatigue crack propagation behavior of rolled AZ31B magnesium ... Alloy Design for Enhancing the Fracture Resistance of Heat Treated High...

94

Sulfide Stress Cracking in Steels - A Review  

Science Conference Proceedings (OSTI)

Symposium, Corrosion and Corrosion Protection of Materials in the Oil and Gas Industry. Presentation Title, Sulfide Stress Cracking in Steels - A Review.

95

Environmentally Assisted Cracking Susceptibility Assessment of AP ...  

Science Conference Proceedings (OSTI)

Presentation Title, Environmentally Assisted Cracking Susceptibility Assessment of AP 1000 Reactor Coolant Pump Flywheel Retainer Ring A289 18Cr-18Mn...

96

Status Review of Initiation of Environmentally Assisted Cracking and Short Crack Growth  

Science Conference Proceedings (OSTI)

This report reviews current knowledge of environmentally assisted cracking EAC initiation and short crack growth by stress corrosion cracking, strain-induced corrosion cracking, and, to a lesser extent, corrosion fatigue in nickel base alloys, austenitic stainless steels, and carbon and low-alloy steels exposed to typical pressurized water reactor PWR and boiling water reactor BWR aqueous environments. The document identifies key gaps in knowledge and recommends areas where additional experimental work i...

2005-12-06T23:59:59.000Z

97

Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal  

E-Print Network (OSTI)

Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal L Keywords: A. Stainless steel B. SEM C. Stress corrosion a b s t r a c t Single crystal 321 stainless steel, and the river-markings exhibited microshear facets along the {1 1 1} plane. Interaction between the main crack

Volinsky, Alex A.

98

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; Malcolm A. Faers; Paul Bartlett

2013-09-30T23:59:59.000Z

99

Development of a Low Thermal Expansion, Crack Growth Resistant ...  

Science Conference Proceedings (OSTI)

significant commercial usage in industries as diverse as gas turbine engine static ... Manufacturing and fabricating simplicity, and compatibility of heat treatments...

100

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

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

Characterization of Environment-Dependent Fatigue Crack Growth ...  

Science Conference Proceedings (OSTI)

at high frequency levels to fully environment-dependent at very low frequency ... environment-dependent crack growth process, crack increment per cycle is...

102

Computational Weld Mechanics of Hot Crack Nucleation in Nickel ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Computational weld mechanics (CWM) is used to estimate the likelihood of hot crack nucleation in a welded joint. A hot crack nucleates when...

103

The Effect of Microstructure on the Fatigue Crack Growth Resistance ...  

Science Conference Proceedings (OSTI)

GROWTH RESISTANCE OF NICKEL BASE SUF'RRALLOYS. Randy Bowman ... damage are most resistant to crack growth. ... crack propagation. (FCP) was...

104

High cycle fatigue and fatigue crack propagation behavior of ...  

Science Conference Proceedings (OSTI)

And fatigue crack propagation rates of modified A7075 showed slightly lower. Those superior fatigue strength and resistance of fatigue crack propagation of...

105

Characterization of Elevated Temperature Fatigue Crack Growth Rates  

Science Conference Proceedings (OSTI)

temperature fatigue and the crack growth rates may be adequately correlated with the ... During creep crack growth the use of rate dependent elastic/plastic frac-.

106

Delay Dependent Exponential Stability for Fuzzy Recurrent Neural Networks with Interval Time-Varying Delay  

Science Conference Proceedings (OSTI)

In this paper, the problem of delay-dependent exponential stability for fuzzy recurrent neural networks with interval time-varying delay is investigated. The delay interval has been decomposed into multiple non equidistant subintervals, on these interval ... Keywords: Delay decomposition, Fuzzy recurrent neural networks, Interval time-varying delay, Maximum admissible upper bound (MAUB), Maximum exponential convergent rate (MECR)

R. Chandran; P. Balasubramaniam

2013-04-01T23:59:59.000Z

107

Stress corrosion cracking of type 304L stainless steel core shroud welds.  

SciTech Connect

Microstructural analyses by advanced metallographic techniques were conducted on mockup welds and a cracked BWR core shroud weld fabricated from Type 304L stainless steel. heat-affected zones of the shroud weld and mockup shielded-metal-arc welds were free of grain-boundary carbide, martensite, delta ferrite, or Cr depletion near grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the welds were significantly contaminated by fluorine and oxygen which migrate to grain boundaries. Significant oxygen contamination promotes fluorine contamination and suppresses classical thermal sensitization, even in Type 304 steels. Results of slow-strain-rate tensile tests indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of Type 304L stainless steel core shroud welds.

Chung, H. M.; Park, J.-H.; Sanecki, J. E.; Zaluzec, N. J.; Yu, M. S.; Yang, T. T.

1999-10-26T23:59:59.000Z

108

Understanding crack versus cavitation in pressure-sensitive adhesives: the role of kinetics  

E-Print Network (OSTI)

We perform traction experiments on viscous liquids highly confined between parallel plates, a geometry known as the probe-tack test in the adhesion community. Direct observation during the experiment coupled to force measurement shows the existence of several mechanisms for releasing the stress. Bubble nucleation and instantaneous growth had been observed in a previous work. Upon increasing further the traction velocity or the viscosity, the bubble growth is progressively delayed. At high velocities, cracks at the interface between the plate and the liquid appear before the bubbles have grown to their full size. Bubbles and cracks are thus observed concomitantly. At even higher velocities, cracks develop fully so early that the bubbles are not even visible. We present a theoretical model that describes these regimes, using a Maxwell fluid as a model for the actual fluid, a highly viscous silicon oil. We present the resulting phase diagramme for the different force peak regimes. The predictions are compatible with the data. Our results show that in addition to cavitation, interfacial cracks are encountered in a probe-tack traction test with viscoelastic, \\emph{liquid} materials and not solely with viscoelastic solids like adhesives.

Jrmie Teisseire; F. Nallet; P. Fabre; Cyprien Gay

2006-09-18T23:59:59.000Z

109

Subcritical Crack Growth Processes in SiC/SiC Ceramic Matrix Composites  

Science Conference Proceedings (OSTI)

Ceramic matrix composites have the potential to operate at high-temperatures and are, therefore being considered for a variety of advanced energy technologies such as combustor liners in land based gas turbo/generators, heat exchangers and advanced fission and fusion reactors. Ceramic matrix composites exhibit a range of crack growth mechanisms driven by a range of environmental and nuclear conditions. The crack growth mechanisms include: 1) fiber relaxation by thermal (FR) and irradiation (FIR) processes, 2) fiber stress-rupture (SR), 3) interface removal (IR) by oxidation, and 4) oxidation embrittlement (OE) resulting from glass formation including effects of glass viscosity. Analysis of these crack growth processes has been accomplished with a combination experimental/modeling effort. Dynamic, high-temperature, in situ crack growth measurements have been made in variable Ar + O2 environments while a PNNL developed model has been used to extrapolate this data and to add radiation effects. In addition to the modeling effort, a map showing these mechanisms as a function of environmental parameters was developed. This mechanism map is an effective tool for identifying operating regimes and predicting behavior. The process used to develop the crack growth mechanism map was to: 1) hypothesize and experimentally verify the operative mechanisms, 2) develop an analytical model for each mechanism, and 3) define the operating regime and boundary conditions for each mechanism. A map for SiC/SiC composites has been developed for chemical and nuclear environments as a function of temperature and time.

Jones, Russell H.; Henager, Charles H.

2005-07-01T23:59:59.000Z

110

The Effects of Test Temperature, Temper, and Alloyed Copper on the Hydrogen-Controlled Crack Growth Rate of an Al-Zn-Mg-(Cu) Alloy  

DOE Green Energy (OSTI)

The hydrogen embrittlement controlled stage II crack growth rate of AA 7050 (6.09 wt.% Zn, 2.14 wt% Mg, 2.19 wt.% Cu) was investigated as a function of temper and alloyed copper level in a humid air environment at various temperatures. Three tempers representing the underaged, peak aged, and overaged conditions were tested in 90% relative humidity (RH) air at temperatures between 25 and 90 C. At all test temperatures, an increased degree of aging (from underaged to overaged) produced slower stage II crack growth rates. The stage II crack growth rate of each alloy and temper displayed Arrhenius-type temperature dependence with activation energies between 58 and 99 kJ/mol. For both the normal copper and low copper alloys, the fracture path was predominantly intergranular at all test temperatures (25-90 C) in each temper investigated. Comparison of the stage II crack growth rates for normal (2.19 wt.%) and low (0.06 wt.%) copper alloys in the peak aged and overaged tempers showed the beneficial effect of copper additions on stage II crack growth rate in humid air. In the 2.19 wt.% copper alloy, the significant decrease ({approx} 10 times at 25 C) in stage II crack growth rate upon overaging is attributed to an increase in the apparent activation energy for crack growth. IN the 0.06 wt.% copper alloy, overaging did not increase the activation energy for crack growth but did lower the pre-exponential factor, {nu}{sub 0}, resulting in a modest ({approx} 2.5 times at 25 C) decrease in crack growth rate. These results indicate that alloyed copper and thermal aging affect the kinetic factors that govern stage II crack growth rate. Overaged, copper bearing alloys are not intrinsically immune to hydrogen environment assisted cracking but are more resistant due to an increased apparent activation energy for stage II crack growth.

G.A. Young, Jr.; J.R. Scully

2000-09-17T23:59:59.000Z

111

Numerical modeling of crack reorientation and link-up  

Science Conference Proceedings (OSTI)

The FRANC3D/BES software system has been used to simulate the reorientation and link-up of hydraulic fractures in three-dimensional (3D) problems. The adopted technique only needs to discretize the body surface and the crack surface. The crack propagation ... Keywords: FRANC3D/BES, crack propagation, multiple cracks

C. Y. Dong; C. J. de Pater

2002-11-01T23:59:59.000Z

112

Optimal control of fluid catalytic cracking processes  

Science Conference Proceedings (OSTI)

An investigation was made of the applicability of optimal control theory to the design of control systems for non-linear, multivariable chemical processes. A hypothetical fluid catalytic cracking process was selected as a typical representative of such ...

L. A. Gould; L. B. Evans; H. Kurihara

1970-09-01T23:59:59.000Z

113

An investigation of penetrant techniques for detection of machining-induced surface-breaking cracks on monolithic ceramics  

Science Conference Proceedings (OSTI)

The purpose of this effort was to evaluate penetrant methods for their ability to detect surface-breaking cracks in monolithic ceramic materials with an emphasis on detection of cracks generated by machining. There are two basic penetrant types, visible and fluorescent. The visible penetrant method is usually augmented by powder developers and cracks detected can be seen in visible light. Cracks detected by fluorescent penetrant are visible only under ultraviolet light used with or without a developer. The developer is basically a powder that wicks up penetrant from a crack to make it more observable. Although fluorescent penetrants were recommended in the literature survey conducted early in this effort, visible penetrants and two non-standard techniques, a capillary gaseous diffusion method under development at the institute of Chemical Physics in Moscow, and the {open_quotes}statiflux{close_quotes} method which involves use of electrically charged particles, were also investigated. SiAlON ring specimens (1 in. diameter, 3/4 in. wide) which had been subjected to different thermal-shock cycles were used for these tests. The capillary gaseous diffusion method is based on ammonia; the detector is a specially impregnated paper much like litmus paper. As expected, visible dye penetrants offered no detection sensitivity for tight, surface-breaking cracks in ceramics. Although the non-standard statiflux method showed promise on high-crack-density specimens, it was ineffective on limited-crack-density specimens. The fluorescent penetrant method was superior for surface-breaking crack detection, but successful application of this procedure depends greatly on the skill of the user. Two presently available high-sensitivity fluorescent penetrants were then evaluated for detection of microcracks on Si{sub 3}N{sub 4} and SiC from different suppliers. Although 50X optical magnification may be sufficient for many applications, 200X magnification provides excellent delectability.

Forster, G.A.; Ellingson, W.A.

1996-02-01T23:59:59.000Z

114

Thermal spray coatings on Yankee dryers  

SciTech Connect

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

115

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 in the counting station. A set of highly purified actinide samples (U-235 and Pu-239) was irradiated in these experiments by using the Texas A&M University Nuclear Science Center Reactor. A fast pneumatic transfer system, an integrated computer control system, and a graphite-moderated counting system were constructed to perform all these experiments. The calculated values for the five-group U-235 delayed neutron parameters and the six-group Pu-239 delayed neutron parameters were compared with the values recommended by Keepin et al. (1957) and Waldo et al. (1981). These new values differ slightly from literature values. The graphite-moderated counting station and the computerized pneumatic system are now operational for further delayed neutron measurement.

Chen, Yong

2006-12-01T23:59:59.000Z

116

Delay-Insensitivity and Semi-Modularity  

Science Conference Proceedings (OSTI)

The study of asynchronous circuit behaviors in the presence of component and wire delays has received a great deal of attention. In this paper, we consider asynchronous circuits whose components can be any non-deterministic sequential machines of ... Keywords: asynchronous, bisimulation, delay-dense, delay-insensitive, isochronic, module, network, semi-modular, speedindependent

J. A. Brzozowski; H. Zhang

2000-03-01T23:59:59.000Z

117

Effect of Hot Cracks on EAC Crack Initiation and Growth in Nickel ...  

Science Conference Proceedings (OSTI)

No crack initiation/extension from hot cracks occured in any weld metals, which is ... Applicability of Lean Grade of Duplex Stainless Steels in Nuclear Power Plants .... Wear of Zircaloy-4 Grid Straps Due to Fretting and Periodic Impact with RV...

118

TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW  

SciTech Connect

Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

Langton, C.

2012-05-11T23:59:59.000Z

119

Linking Grain Boundary Microstructure to Stress Corrosion Cracking of Cold Rolled Alloy 690 in PWR Primary Water  

SciTech Connect

Grain boundary microstructures and microchemistries are examined in cold-rolled alloy 690 tubing and plate materials and comparisons are made to intergranular stress corrosion cracking (IGSCC) behavior in PWR primary water. Chromium carbide precipitation is found to be a key aspect for materials in both the mill annealed and thermally treated conditions. Cold rolling to high levels of reduction was discovered to produce small IG voids and cracked carbides in alloys with a high density of grain boundary carbides. The degree of permanent grain boundary damage from cold rolling was found to depend directly on the initial IG carbide distribution. For the same degree of cold rolling, alloys with few IG precipitates exhibited much less permanent damage. Although this difference in grain boundary damage appears to correlate with measured SCC growth rates, crack tip examinations reveal that cracked carbides appeared to blunt propagation of IGSCC cracks in many cases. Preliminary results suggest that the localized grain boundary strains and stresses produced during cold rolling promote IGSCC susceptibility and not the cracked carbides and voids.

Bruemmer, Stephen M.; Olszta, Matthew J.; Toloczko, Mychailo B.; Thomas, Larry E.

2012-10-01T23:59:59.000Z

120

STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS  

SciTech Connect

Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

2009-05-01T23:59:59.000Z

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.


121

Adsorbent-treated cat cracked gasoline in motor fuels  

SciTech Connect

A methof is described for supressing carburetor deposit formation of motor fuels containing untreated cat cracked gasoline by blending adsorbent-treated cat cracked gasoline into the motor fuel. Up to about 50 percent by weight of the total composition is adsorbent treated cat cracked gasoline, but preferably from about 5 to about 25 percent by weight of the total composition is adsorbent treated cat cracked gasoline. In a preferred embodiment a standard reference fuel capable of providing a predetermined level of carburetor deposit formation is provided by the addition of either adsorbent-treated cat cracked gasoline, untreated cat cracked gasoline, or aromatic amines to a base fuel.

Thomas, S.P.

1980-09-30T23:59:59.000Z

122

Crack detection using resonant ultrasound spectroscopy  

DOE Patents (OSTI)

This invention is comprised of a method and apparatus 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.

Migliori, A.; Bell, T.M.

1992-12-31T23:59:59.000Z

123

Optimal integer delay budgeting on directed acyclic graphs  

Science Conference Proceedings (OSTI)

Delay budget is an excess delay each component of a design can tolerate under a given timing constraint. Delay budgeting has been widely exploited to improve the design quality. We present an optimal integer delay budgeting algorithm. Due to numerical ...

E. Bozorgzadeh; S. Ghiasi; A. Takahashi; M. Sarrafzadeh

2003-06-01T23:59:59.000Z

124

Variable-delay feedback control of unstable steady states in retarded time-delayed systems  

E-Print Network (OSTI)

We study the stability of unstable steady states in scalar retarded time-delayed systems subjected to a variable-delay feedback control. The important aspect of such a control problem is that time-delayed systems are already infinite-dimensional before the delayed feedback control is turned on. When the frequency of the modulation is large compared to the system's dynamics, the analytic approach consists of relating the stability properties of the resulting variable-delay system with those of an analogous distributed delay system. Otherwise, the stability domains are obtained by a numerical integration of the linearized variable-delay system. The analysis shows that the control domains are significantly larger than those in the usual time-delayed feedback control, and that the complexity of the domain structure depends on the form and the frequency of the delay modulation.

Aleksandar Gjurchinovski; Viktor Urumov

2010-07-06T23:59:59.000Z

125

Thermal Sprays and Ceramic Coatings Assessments: Laboratory and Field Evaluations of Ceramic and Thermal Sprays Coatings  

Science Conference Proceedings (OSTI)

This report includes assessments of Ceramic and Thermal Spray coatings both by laboratory evaluation and analysis of field samples. The field samples are presented as case studies describing the condition of the material solution applied. Several thermal sprays and ceramic coatings were tested and analyzed for their ability to mitigate fireside corrosion, reduce slagging and it's propensity to have circumferential cracking occur due to cyclic temperature variations. In addition, the case studies provide ...

2010-12-31T23:59:59.000Z

126

A Flaw Tolerance Approach to Address Reactor Vessel Head Penetration Cracking Issue  

SciTech Connect

Nickel-based alloys and the associated welds are susceptible to Primary Water Stress Corrosion Cracking. In Pressurized Water Reactor nuclear power plants, the reactor vessel closure head upper penetration nozzles used for the Control Rod Drive Mechanisms and other instrumentation systems are made of such nickel-based alloys. Cracking and leakage have been observed in the upper head penetration nozzles in nuclear power plants worldwide. Such cracking and the resulting leakage is a degradation of the reactor vessel pressure boundary. Regulatory requirements have been issued by the Nuclear Regulatory Commission regarding periodic inspection of the susceptible areas to enable detection of indications and provide reasonable assurance of continued structural integrity for reactor vessel closure head. A flaw tolerance approach has been used in the disposition of detected indications to minimize outage delays, by performing up-front fracture mechanics evaluations for the common types of indications detected in the susceptible areas. Details of the flaw tolerance approach are presented in this paper. (authors)

Ng, C. K.; Jirawongkraisorn, S.; Swamy, S. [Westinghouse Electric Company, LLC, Nuclear Services Division, P. O. Box 158, Madison, PA 15663 (United States)

2006-07-01T23:59:59.000Z

127

Stress corrosion cracking behavior of Alloy 600 in high temperature water  

Science Conference Proceedings (OSTI)

SCC susceptibility of Alloy 600 in deaerated water at 360 C (statically loaded U-bend specimens) is dependent on microstructure and whether the material was cold-worked and annealed (CWA) or hot-worked and annealed (HWA). All cracking was intergranular, and materials lacking grain boundary carbides were most susceptible to SCC initiation. CWA tubing materials are more susceptible to SCC initiation than HWA ring-rolled forging materials with similar microstructures (optical metallography). In CWA tubing materials, one crack dominated and grew to a visible size. HWA materials with a low hot-working finishing temperature (980 C) and a high-temperature final anneal (>1040 C), with grain boundaries that are fully decorated, developed only microcracks in all specimens. These materials did not develop large, visually detectable cracks, even after more than 300 weeks exposure. A low-temperature thermal treatment (610 C for 7h), which reduces or eliminates SCC in Alloy 600, did not eliminate microcrack formation in high temperature processed HWA materials. Conventional metallographic and analytical electron microscopy (AEM) were done on selected materials to identify the factors responsible for the observed differences in cracking behavior. Major difference between high-temperature HWA and low-temperature HWA and CWA materials was that the high temperature processing and final annealing produced predominantly ``semi-continuous`` dendritic M{sub 7}C{sub 3} carbides along grain boundaries with a minimal amount of intragranular carbides. Lower temperature processing produced intragranular M7C3 carbides, with less intergranular carbides.

Webb, G.L.; Burke, M.G.

1995-07-01T23:59:59.000Z

128

Accelerated Fatigue Crack Growth Behavior of PWA 1480 Single ...  

Science Conference Proceedings (OSTI)

3 456. 610. 1520 30. AK . AKrss. MPa v'?! Fig. 10 Fatigue crack growth rate as a function of AKrss and AK. Prediction of the Microscopic Crack Behavior: An...

129

Reading of cracked optical discs using iterative learning control  

Science Conference Proceedings (OSTI)

Optical discs, including Compact Discs (CDs), Digital Versatile Discs (DVDs), and Blu-ray Discs (BDs), can get cracked during storage and usage. Such cracks commonly lead to discontinuities in the data track, potentially preventing reading of the data ...

Maarten Steinbuch; Koos Van Berkel; George Leenknegt; Tom Oomen; Jeroen Van De Wijdeven

2009-06-01T23:59:59.000Z

130

Stress Corrosion Cracking of Steel In Concentrated Nitrate ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2011. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Stress...

131

Interaction between Local Strains and Stress Corrosion Cracks ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Environmentally Assisted Cracking (EAC): Laboratory Research and Field...

132

Stress Corrosion Cracking Observation in API G-105 Grade Drill ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2011. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Stress...

133

Environmentally Assisted Cracking of Stainless Steels and Nickel ...  

Science Conference Proceedings (OSTI)

Oct 10, 2012 ... Intergranular Stress Corrosion Cracking (IGSCC) Mechanism of Structural Component Materials in Pressurized Water Reactors : Young Suk...

134

stress corrosion cracking of iron and nickel based alloys  

Science Conference Proceedings (OSTI)

This Table of Contents is from Chemistry and Electrochemistry of Corrosion and Stress Corrosion Cracking published by TMS.

135

Girth Weld Cracking at Ethanol Terminal Facilities - Programmaster ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Failure Analysis and Prevention. Presentation Title, Girth Weld Cracking at...

136

Latent Cracking of Tantalum - Titanium Welds Due to Hydrogen ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, Materials Science & Technology 2012. Symposium, Environmentally Assisted Cracking of Materials. Presentation Title, Latent...

137

Molecular Dynamics of Fatigue Crack Growth in Nanocrystalline ...  

Science Conference Proceedings (OSTI)

Experimental techniques are prohibitive due to limitations of nano samples and advanced microscopic manipulators. In this study, crack propagation under...

138

THERMAL RECOVERY  

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

THERMAL RECOVERY Thermal recovery comprises the techniques of steamflooding, cyclic steam stimulation, and in situ combustion. In steamflooding, high-temperature steam is injected...

139

Materials Reliability Program: Input for Pressurized Thermal Shock Rulemaking (MRP-248)  

Science Conference Proceedings (OSTI)

The Pressurized Thermal Shock (PTS) rule addresses the risk of a nuclear power plant reactor vessel failing due to propagation of a crack through the vessel wall. If a plant has an emergency cool-down event that superimposes a large thermal transient stress on a large pressure stress in the presence of a pre-existing flaw, it is possible that a crack could initiate and propagate through the vessel wall. The resistance of a vessel to crack initiation and propagation declines as the vessel ages. As a resul...

2008-12-23T23:59:59.000Z

140

Honeywords: making password-cracking detectable  

Science Conference Proceedings (OSTI)

We propose a simple method for improving the security of hashed passwords: the maintenance of additional ``honeywords'' (false passwords) associated with each user's account. An adversary who steals a file of hashed passwords and inverts the hash function ... Keywords: authentication, chaffing, honeywords, login, password cracking, password hashes, passwords

Ari Juels, Ronald L. Rivest

2013-11-01T23:59:59.000Z

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.


141

Fuzzy modeling of fluidized catalytic cracking unit  

Science Conference Proceedings (OSTI)

The paper deals with the fuzzy system identification of reactor-regenerator-stripper-fractionator's (RRSF) section of a fluidized catalytic cracking unit (FCCU). The fuzzy system identification based on the data collected from an operating refinery of ... Keywords: Dynamic fuzzy model, FCCU models, Fuzzy clustering, Fuzzy inference systems, Fuzzy models, Hybrid learning, Mountain clustering, Supervised learning, Unsupervised learning

Mohammad Fazle Azeem; Nesar Ahmad; M. Hanmandlu

2007-01-01T23:59:59.000Z

142

Cracked rotor vibrations by multifractal analysis  

E-Print Network (OSTI)

Multifractal analysis has been used to diagnoze cracked and healthy rotors. Is has been shown that the complexity and regularity criteria of the dynamical systems defined by the multiple scaling of the time series can indicate the damages of the rotating shaft.

Grzegorz Litak; Jerzy T. Sawicki

2008-04-15T23:59:59.000Z

143

Strip edge cracking simulation in cold rolling  

SciTech Connect

This research work focuses on a specific defect which occurs during cold rolling of steel strips: edge-serration. Investigations on the industrial processes have led to the conclusion that this defect is the result of the edge-trimming and cold rolling sequences. The aim of this research work is to analyze the effect of the cutting process and the cold rolling on cracks occurrence, especially on strip edges.This study is performed using an experimental testing stand called Upsetting Rolling Test (URT). It allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near trimmed industrial strip edges are deformed using the URT stand. Two sets of specimens with different stress states, obtained by annealing, are submitted to two reduction passes with extreme forward slips.Scanning electron microscopy observations added to 3D optical surface profiler topographies show that on one hand, forward slip has a major effect on cracks opening. On the other hand, cracks opening decreases according to high roll strip speed gradient. Concerning the heat-treated specimens, no crack appeared after all reduction passes, showing a large influence of the cutting process and consequently of the local stress state in the vicinity of the burnish and fracture regions.

Hubert, C.; Dubar, L.; Dubar, M.; Dubois, A. [Univ Lille Nord de France, F-59000 Lille (France); UVHC, TEMPO EA 4542, F-59313 Valenciennes (France)

2011-01-17T23:59:59.000Z

144

Segmentation of cracks in shale rock  

Science Conference Proceedings (OSTI)

In this paper the use of morphological connected filters are studied for segmenting sheet- and thread-like cracks in images of shale rock. A volume formed from a stack of 2-D X-ray images is processed using 3-D attributes. The shape-preserving property ...

Erik R. Urbach; Marina Pervukhina; Leanne Bischof

2011-07-01T23:59:59.000Z

145

Digital radiographic systems detect boiler tube cracks  

SciTech Connect

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

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

2008-06-15T23:59:59.000Z

146

Stress corrosion cracking and crack tip characterization of Alloy X-750 in light water reactor environments  

E-Print Network (OSTI)

Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

Gibbs, Jonathan Paul

2011-01-01T23:59:59.000Z

147

The influence of crack-imbalance orientation and orbital evolution for an extended cracked Jeffcott rotor  

E-Print Network (OSTI)

Vibration peaks occurring at rational fractions of the fundamental rotating critical speed, here named Local Resonances, facilitate cracked shaft detection during machine shut-down. A modified Jeffcott-rotor on journal bearings accounting for gravity effects and oscillating around nontrivial equilibrium points is employed. Modal parameter selection allows this linear model to represent first mode characteristics of real machines. Orbit evolution and vibration patterns are analyzed, yielding useful results. Crack detection results indicate that, instead of 1x and 2x components, analysis of the remaining local resonances should have priority; this is due to crack-residual imbalance interaction and to 2x multiple induced origins. Therefore, local resonances and orbital evolution around 1/2, 1/3 and 1/4 of the critical speed are emphasized for various crack-imbalance orientations.

Julio Gomez-Mancilla; Jean-Jacques Sinou; V. R. Nosov; Fabrice Thouverez; A. Zambrano

2008-01-19T23:59:59.000Z

148

Stress Corrosion Cracking and Crack Tip Characterization of Alloy X-750 in Light Water Reactor Environments  

E-Print Network (OSTI)

Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

Gibbs, Jonathan Paul

149

Time dependent estimates of delays and delay costs at major airports  

E-Print Network (OSTI)

Two queuing models appropriate for estimating time dependent delays and delay costs at major airports are reviewed. The models use the demand and capacity profiles at any given airport as well as the number of runways there ...

Hengsbach, Gerd

1975-01-01T23:59:59.000Z

150

Characterization of geothermal reservoir crack patterns using...  

Open Energy Info (EERE)

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,...

151

Analysis on delay-dependent stability for neural networks with time-varying delays  

Science Conference Proceedings (OSTI)

This paper considers the problem of delay-dependent stability criteria for neural networks with time-varying delays. First, by constructing a newly augmented Lyapunov-Krasovskii functional, a less conservative stability criterion is established in terms ... Keywords: Lyapunov method, Neural networks, Stability, Time-varying delays

O. M. Kwon; Ju H. Park; S. M. Lee; E. J. Cha

2013-03-01T23:59:59.000Z

152

TCP with delayed ack for wireless networks  

Science Conference Proceedings (OSTI)

This paper studies the TCP performance with delayed ack in wireless networks (including ad hoc and WLANs) which use IEEE 802.11 MAC protocol as the underlying medium access control. Our analysis and simulations show that TCP throughput does not always ... Keywords: Adaptive delayed ack, Congestion control, Friendliness, TCP, Wireless medium access/contention

Jiwei Chen; Mario Gerla; Yeng Zhong Lee; M. Y. Sanadidi

2008-09-01T23:59:59.000Z

153

Novel delay-dependent asymptotic stability criteria for neural networks with time-varying delays  

Science Conference Proceedings (OSTI)

The problem of delay-dependent asymptotic stability criteria for neural networks (NNs) with time-varying delays is investigated. An improved linear matrix inequality based on delay-dependent stability test is introduced to ensure a large upper bound ... Keywords: 34K20, 34K25, 37C20, 37C25, 37C75, 37N35, 37N40, 93C10, 93C83, 93D05, 93D20, Delay-dependent, Linear matrix inequality (LMI), Neural networks (NNs), Time-varying delay

Junkang Tian; Dongsheng Xu; Jian Zu

2009-06-01T23:59:59.000Z

154

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

155

SCREENING TESTS FOR IMPROVED METHANE CRACKING MATERIALS  

DOE Green Energy (OSTI)

Bench scale (1 to 6 gram) methane cracking tests have been performed on a variety of pure elements, some alloys, and SAES{reg_sign} commercial getters St 101, St 198, St 707, St 737, and St 909 to determine methane cracking performance (MCP) of 5% methane in a helium carrier at 700 C, 101.3 kPa (760 torr) with a 10 sccm feed. The MCP was almost absent from some materials tested while others showed varying degrees of MCP. Re, Cr, V, Gd, and Mo powders had good MCP, but limited capacities. Nickel supported on kieselguhr (Ni/k), a Zr-Ni alloy, and the SAES{reg_sign} getters had good MCP in a helium carrier. The MCP of these same materials was suppressed in a hydrogen carrier stream and the MCP of the Zr-based materials was reduced by nitride formation when tested with a nitrogen carrier gas.

Klein, J; Jeffrey Holder, J

2007-07-16T23:59:59.000Z

156

Circumferential cracking of steam generator tubes  

SciTech Connect

On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, {open_quote}Circumferential Cracking of Steam Generator Tubes.{close_quote} GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff`s assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness.

Karwoski, K.J.

1997-04-01T23:59:59.000Z

157

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

158

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

159

Service Provider Competition: Delay Cost Structure, Segmentation, and Cost Advantage  

Science Conference Proceedings (OSTI)

We model competition between two providers who serve delay-sensitive customers. We compare a generalized delay cost structure, where a customer's delay cost depends on her service valuation, with the traditional additive delay cost structure, where the ... Keywords: delay cost structure, service competition, value-based market segmentation

Maxim Afanasyev; Haim Mendelson

2010-04-01T23:59:59.000Z

160

Hydrogen Induced Cracking of Drip Shield  

DOE Green Energy (OSTI)

One potential failure mechanism for titanium and its alloys under repository conditions is via the absorption of atomic hydrogen in the metal crystal lattice. The resulting decreased ductility and fracture toughness may lead to brittle mechanical fracture called hydrogen-induced cracking (HIC) or hydrogen embrittlement. For the current design of the engineered barrier without backfill, HIC may be a problem since the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction. The purpose of this scientific analysis and modeling activity is to evaluate whether the drip shield will fail by HIC or not under repository conditions within 10,000 years of emplacement. This Analysis and Model Report (AMR) addresses features, events, and processes related to hydrogen induced cracking of the drip shield. REV 00 of this AMR served as a feed to ''Waste Package Degradation Process Model Report'' and was developed in accordance with the activity section ''Hydrogen Induced Cracking of Drip Shield'' of the development plan entitled ''Analysis and Model Reports to Support Waste Package PMR'' (CRWMS M&O 1999a). This AMR, prepared according to ''Technical Work Plan for: Waste Package Materials Data Analyses and Modeling'' (BSC 2002), is to feed the License Application.

G. De

2003-02-24T23:59:59.000Z

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

Methane cracking over a bituminous coal char  

Science Conference Proceedings (OSTI)

Methane cracking over a bed of Chinese bituminous coal char was studied using a fixed-bed reactor at atmospheric pressure and temperatures between 1073 and 1223 K. Methane conversion over the fresh char increased with increasing temperature to 90% at 1223 K. Hydrogen was the only gas-phase product that was detected during the experimentation. The char was shown to exert a significant catalytic effect on methane cracking by comparing results from experiments with the raw char and demineralised char as well as from blank experiments using quartz. It was further shown that the ash was not the source of the catalytic effect of the char. However, both methane conversion and hydrogen yield decreased with increasing reaction time, irrespective of other experimental conditions, indicating that the char rapidly became deactivated following the exposure to methane. It was speculated that the deposition of carbon from methane cracking was responsible for this deactivation, which is supported by scanning electron microscopy (SEM) image analysis. It was demonstrated that the catalytic activity of the deactivated char can be partially recovered by burning off the carbon deposits with an oxidizing gas mixture containing 0.46% oxygen. 10 refs., 11 figs., 1 tab.

Zhi-qiang Sun; Jin-hu Wu; Mohammad Haghighi; John Bromly; Esther Ng; Hui Ling Wee; Yang Wang; Dong-ke Zhang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

2007-06-15T23:59:59.000Z

162

Crack tip plasticity in single crystal UO2: Atomistic simulations  

SciTech Connect

The fracture behavior of single crystal uranium dioxide is studied using molecular dynamics simulations at room temperature. Initially, an elliptical notch is created on either {111} or {110} planes, and tensile loading is applied normal to the crack planes. For cracks on both planes, shielding of crack tips by plastic deformation is observed, and crack extension occurs for crack on {111} planes only. Two plastic processes, dislocation emission and phase transformation are identified at crack tips. The dislocations have a Burgers vector of ?110?/2, and glide on {100} planes. Two metastable phases, the so-called Rutile and Scrutinyite phases, are identified during the phase transformation, and their relative stability is confirmed by separate density- functional-theory calculations. Examination of stress concentration near crack tips reveals that dislocation emission is not an effective shielding mechanism. The formation of new phases may effectively shield the crack provided all phase interfaces formed near the crack tips are coherent, as in the case of cracks residing on {110} planes.

Yongfeng Zhang; Paul C. Millett; Michael Tonks; Bulent Biner; Xiang-Yang Liu; David A. Andersson

2012-11-01T23:59:59.000Z

163

Final report on PCRV thermal cylinder axial tendon failures  

SciTech Connect

The post-test examination of the failed tendons from the PCRV thermal cylinder experiment has been concluded. Failures in the wires are attributed to stress-corrosion cracking. The cause of tendon failures has not been unequivocably established, but they may have been due to nitrates in the duct. The wires employed in the manufacture of the tendons will crack in less than 72 hr in a 0.2 M solution of ammonium nitrate at 70$sup 0$C. The quality of the wires is poor, and surface cracks were detected. These could have acted as concentrating sites for both stress and the deleterious contaminants. It is believed that the factors that led to the failures in the thermal cylinder experiment were unique. An improper formulation of the epoxy resin did not provide the tendon anchor plate seal that was desired; indeed, the improper formulation is responsible for the high level of nitrogen in the ducts of the failed tendons. (auth)

Canonico, D.A.; Griess, J.C.; Robinson, G.C.

1976-01-01T23:59:59.000Z

164

Role of crack tip shielding in the initiation and growth of long and small fatigue cracks in composite microstructures  

Science Conference Proceedings (OSTI)

The role of crack tip shielding in retarding the initiation and growth of fatigue cracks has been examined in metallic composite microstructures (consisting of hard and soft phases), with the objective of achieving maximum resistance to fatigue. Specifically, duplex ferritic-martensitic structures have been developed in AISI 1008 and 1015 mild steels to promote shielding without loss in strength. The shielding is developed primarily from crack deflection and resultant crack closure, such that unusually high long crack propagation resistance is obtained. It is found that the fatigue threshold ..delta..K/sub TH/ in AISI 1008 can be increased by more than 100 pct to over 20 MPa ..sqrt..m, without sacrifice in strength, representing the highest ambient temperature threshold reported for a metallic alloy to date. Similar but smaller increases are found in AISI 1015. The effect of the dual-phase microstructures on crack initiation and small crack (10 to 1000 ..mu..m) growth, however, is markedly different, characteristic of behavior influenced by the mutual competition of intrinsic and extrinsic (shielding) ''toughening'' mechanisms. Accordingly, the composite microstructures which appear to show the highest resistance to the growth of long cracks, show the lowest resistance to crack initiation and small crack growth. In general, dual-phase steels are found to display remarkable fatigue properties, with fatigue limits as high as 58 pct of the tensile strengths and fatigue thresholds in the range of 13 to 20 MPa..sqrt..m.

Shang, J.K.; Tzou, J.L.; Ritchie, R.O. (Materials and Chemical Sciences Div., Lawrence Berkeley Lab., and Dept. of Materials Science and Mineral Engineering, Univ. of California, Berkeley, CA (US))

1987-09-01T23:59:59.000Z

165

Thermal fatigue evaluation of solder alloys. Final report  

SciTech Connect

An evaluation was made of the relative thermal fatigue resistance of 29 solder alloys. A number of these alloys were found to be less susceptible to thermal fatigue cracking in encapsulated printed wiring board applications than the commonly used tin-lead eutectic (63Sn-37Pb). Three alloys, 95Sn-5Ag, 96.5Sn-3.5Ag, and 95Sn-5Sb offered the greatest resistance to thermal fatigue. The selection of the encapsulation materials was confirmed to be a significant factor in thermal fatigue of solder joints, regardless of the solder alloy used.

Jarboe, D.M.

1980-02-01T23:59:59.000Z

166

Department of Energy and USEC Announce Decision to Delay USEC...  

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

USEC Announce Decision to Delay USEC Loan Guarantee Application Final Review Department of Energy and USEC Announce Decision to Delay USEC Loan Guarantee Application Final Review...

167

Department of Energy and USEC Announce Decision to Delay USEC...  

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

Department of Energy and USEC Announce Decision to Delay USEC Loan Guarantee Application Final Review Department of Energy and USEC Announce Decision to Delay USEC Loan Guarantee...

168

Hydrogen induced crack growth in Grade-12 titanium  

DOE Green Energy (OSTI)

Internal hydrogen induced crack growth rates were measured in Grade-12 titanium which is a candidate material for high-level nuclear waste containers. As-received and hydrogen charged samples (5 ppM to 330 ppM hydrogen) were used for slow crack growth measurements at constant loads using a Krak Gauge. The testing temperature ranged from room temperature to 148/sup 0/C. The crack growth kinetics under low to moderate loads are linear, but this linear rate is interrupted by discrete fast crack jump segments with parabolic or cubic type kinetics. These fast jump segments are thought to be associated with the passage of the crack front through the alpha-beta interface phase or with the initial loading sequence. By measuring striation spacings on the fracture surface, most crack growth rates observed are found to be in stage II. The striations are considered to be associated with hydride fracture. The crack path is either transgranular in the alpha phase or interfacial in the alpha phase adjacent to the beta phase. For transgranular growth, crack growth rates are constant and slower than those for interfacial growth which is associated with fast crack growth through a high hydrogen concentration region. Most stage II crack growth rates depend slightly on the stress intensity suggesting the contribution of plastic tearing process to stage II kinetics. The activation energies for crack growth are much lower than the activation energy of hydrogen diffusion through the alpha phase, implying that hydrogen is transported along dislocations, grain boundaries or interfaces. When the temperature is increased, the crack velocity first reaches a maximum and then decreases at higher temperatures. These temperature effects come from lower hydrogen concentration trapped at dislocations or from slower hydride nucleation kinetics, both at higher temperatures.

Ahn, T.M.; Lee, K.S.

1984-01-01T23:59:59.000Z

169

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

DOE Green Energy (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

170

Relationships Between Stress Corrosion Cracking Tests and Utility ...  

Science Conference Proceedings (OSTI)

Aug 1, 1999 ... Several utility steam generator and stress corrosion cracking ... Superheated steam and neutral solution environments are found to be...

171

Influence of Different Cooling Structure on Surface Crack of HSLA ...  

Science Conference Proceedings (OSTI)

Presentation Title, Influence of Different Cooling Structure on Surface Crack of .... of Si3N4-SiC Heat Absorption Ceramic Material Used for Tower Type Solar...

172

Basic Aspects of Superalloy Design for Crack Growth Resistance  

Science Conference Proceedings (OSTI)

theories for fatigue and creep crack growth resistance that are particularly ... devices as the nuclear reactors and in such strategic and expensive vehicles.

173

Fatigue Property-Microstructure Relationships and Crack Growth  

Science Conference Proceedings (OSTI)

Feb 28, 2011 ... Effect of Microstructure on Fatigue Behavior of Two Pipeline Steels: .... to a transition crack length (LEFM applicable) is approximated using...

174

In-vitro Evaluation of Stress Corrosion Cracking of Biomedical ...  

Science Conference Proceedings (OSTI)

In this study, the susceptibility to stress corrosion cracking of biodegradable and aluminium-free magnesium alloys, WZ21 and WE43, was investigated using...

175

Corrosion Inhibition of Stress Corrosion Cracking and Localized ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Stress corrosion cracking of 7050 aluminum alloys in the turbo expander industry can cause expensive catastrophic failures, especially for turbo

176

Strain Rate Sensitivity of Alloy 718 Stress Corrosion Cracking  

Science Conference Proceedings (OSTI)

Stress corrosion cracking (SCC) tests were conducted in 36O'C pressurized- water-reactor. (PWR) primary water using. Alloy 718 heat-treated to produce.

177

Stress Corrosion Cracking of Aluminium-Free Magnesium Alloys in ...  

Science Conference Proceedings (OSTI)

Presentation Title, Stress Corrosion Cracking of Aluminium-Free Magnesium Alloys in a Simulated Human Body Fluid. Author(s), Lokesh Choudhary, R. K. Singh...

178

Environmentally Assisted Cracking of Alloy 7050-T7451 Exposed to ...  

Science Conference Proceedings (OSTI)

Under cyclic loading notched specimens failed by transgranular stress corrosion cracking. Striations were observed on the cleavage-like facets. The number of...

179

Stress Corrosion Crack Initiation of Alloy 690 in Subcritical and ...  

Science Conference Proceedings (OSTI)

Abstract Scope, The objective of this study is to investigate the structure and chemistry of corrosion and stress corrosion crack initiation in Alloy 690. To avoid

180

grain boundary oxidation and stress corrosion cracking in nickel ...  

Science Conference Proceedings (OSTI)

Accelerated stress corrosion cracking tests and exposures were conducted on alloy 600, Ni-9Fe, and Ni-9Fe-5Cr (LCr) in constant extension rate mode in...

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

Model for the Superimposed Effects of Stress-Corrosion Cracking ...  

Science Conference Proceedings (OSTI)

Symposium, Fatigue and Corrosion Damage in Metallic Materials: Fundamentals, ... and a stress-corrosion cracking mode acting at high stress intensity in NaCl.

182

Stress Corrosion Cracking Threshold of Ti 6-4 Extrusions  

Science Conference Proceedings (OSTI)

Ti 6Al-4V extrusions with standard chemistry and extra low interstitial are evaluated for their stress corrosion cracking resistance. Also examined is the affect of...

183

A Study on the Stress Corrosion Cracking Mechanism of Carbon ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Carbon steel is susceptible to stress corrosion cracking (SCC) in fuel grade ethanol (FGE). The research results obtained thus far have found...

184

Stress Corrosion Cracking Initiation of Austenitic Alloys in ...  

Science Conference Proceedings (OSTI)

Presentation Title, Stress Corrosion Cracking Initiation of Austenitic Alloys in Supercritical Water. Author(s), Guoping Cao, Vahid Firouzdor, Todd Allen. On-

185

Galvanic Corrosion and Stress Corrosion Cracking of Steel and ...  

Science Conference Proceedings (OSTI)

No aluminum bolt AW 7075 failed in magnesium due to stress corrosion cracking (SCC). Even aluminum bolts in T6 condition can be used for automotive...

186

Orientation Effects and Influence of Delta Phase on Fatigue Crack ...  

Science Conference Proceedings (OSTI)

including a hold time at maximum load lead to increased crack propagation rates when compared ... 720C ;' 8 hours .! controlled cooling rate at 50C per hour.

187

Stress Corrosion Cracking of Stabilized Austenitic Stainless Steels ...  

Science Conference Proceedings (OSTI)

Aug 1, 1999 ... Stress Corrosion Cracking of Stabilized Austenitic Stainless Steels in Various Types of Nuclear Power Plants by M.O. Speidel and R.

188

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

Open Energy Info (EERE)

P wave anisotropy, stress, and crack distribution at Coso geothermal field, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: P wave...

189

Failure Analysis of a Cracked Thermite Welded Rail Section  

Science Conference Proceedings (OSTI)

Brittle fracture followed the fatigue crack propagation causing complete separation of the rail. Although the excess material was thought to reinforce the rails it...

190

High-Temperature Stress Relaxation Cracking and Stress Rupture ...  

Science Conference Proceedings (OSTI)

An incident occurred that resulted in the cracking of gasifier internals, bulging and stress rupture of the shell and the escape of hot syngas, causing a fire.

191

Corrosion Fatigue and Crack Propagation of Different Austenitic ...  

Science Conference Proceedings (OSTI)

A FIB Study of the Resistance of Grain Boundaries to Short Fatigue Crack Propagation in Three-Dimensions in High Strength Al Alloys A Non-Linear Damage...

192

Effect of Interstitial Content on High Temperature Fatigue Crack ...  

Science Conference Proceedings (OSTI)

instance; resulted in fatigue crack propagation (FCP)' programs like ESDADTA(2) and ENSIP(3). Fatigue resistance of nickel base superalloys is affected by...

193

Fatigue and Fatigue Crack Propagation Behaviors of High ...  

Science Conference Proceedings (OSTI)

The S-N fatigue and fatigue crack propagation (FCP) behaviors of high ... The mechanisms associated with the improved fatigue resistance for the high...

194

Intergranular Liquid Formation, Distribution, and Cracking in the ...  

Science Conference Proceedings (OSTI)

zone adjacent to the fusion zone. These intergranular cracks form when liquid ...... 718, and A286 in Light Water Reactor. Environments",. J. Mater. Eng., 2, pp.

195

Stress corrosion cracking of zirconium in nitric acid  

Science Conference Proceedings (OSTI)

The susceptibility of zirconium and its common alloys to stress corrosion cracking (SCC) in nitric acid was investigated by slow strain-rate and constant deflection techniques. Cracking occurred at 25/sup 0/C over a wide range of acid concentrations and electrochemical potentials. The crack velocity increased slightly with increasing temperature. The failure mode was transgranular and the morphology was similar to SCC failures of zirconium alloys in other environments. The fracture was very orientation-dependent suggesting that it occurs on a single crystallographic plane in the material. The results of the study are not consistent with a hydrogen mechanism for cracking.

Beavers, J.A.; Griess, J.C.; Boyd, W.K.

1980-01-01T23:59:59.000Z

196

One-Dimensional Cold Rolling Effects on Stress Corrosion Crack ...  

Science Conference Proceedings (OSTI)

A Microstructural Investigation on the Effect of Cold Work on Environmentally .... Stress Corrosion Cracking Behavior near the Fusion Boundary of Dissimilar...

197

Solidification Cracking Study of High Chromium Nickel-Base Filler ...  

Science Conference Proceedings (OSTI)

... and rank the relative cracking susceptibility of these filler metal specifications. ... Surface Processing of Ag /TiO2 Nanowire Membranes for Solar Photovoltaic...

198

Research and Evaluation of Low Temperature Crack Propagation of ...  

Science Conference Proceedings (OSTI)

NRC/EPRI Welding Residual Stress Validation Program (Phase III) On the Microstructure of Alloy 600 SCC Cracks Observed by TEM on PWR SG Pulled Tubes...

199

DPQ Event Cracked Bushing Leads to Transformer Bank Failure  

Science Conference Proceedings (OSTI)

As part of EPRI's distribution power quality (DPQ) project this power quality (PQ) case study investigates cracked bushing recorded by PQ monitors that led to tranformer bank failure.

2003-12-31T23:59:59.000Z

200

Ranking the Susceptibility to Hydrogen-assisted Cracking in Super ...  

Science Conference Proceedings (OSTI)

Thus, SDSS welds are exposed to hydrogen charging to under CP. There have been reported hydrogen assisted cracking (HAC) failures in SDSS welds during...

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

Hydrogen Induced Cracking Susceptibility of Titanium Alloys in ...  

Science Conference Proceedings (OSTI)

May 16, 2007 ... This report evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain...

202

Ductile Crack Investigation in Multicomponent Materials  

Science Conference Proceedings (OSTI)

At this stage of the research Authors proposed two scale numerical model. ... Optimization of Thermal Cycle for Rails with Respect to the Wear Resistance.

203

Short-Crack Response of Alloy 182 Weld Metal Undergoing Stress Corrosion Cracking in High-Temperature PWR Primary Water  

Science Conference Proceedings (OSTI)

Mechanistic investigations of environmentally assisted cracking (EAC), to date, have focused more on propagation relative to initiation. At the same time, components spend most of their life in the initiation and "short-crack" growth regimes. Prior exploratory work conducted at General Electric Global Research Center (GE GRC) showed that stainless steels, Alloy 600, and Alloy 182 weld metal exhibit lower average growth rates when the cracks are very short or small (1050 m). In those tests, the transition...

2008-10-31T23:59:59.000Z

204

Composite tube cracking in kraft recovery boilers: A state-of-the-art review  

Science Conference Proceedings (OSTI)

Beginning in the mid-1960s, increasing energy costs in Finland and Sweden made energy recovery more critical to the cost-effective operation of a kraft pulp mill. Boiler designers responded to this need by raising the steam operating pressure, but almost immediately the wall tubes in these new boilers began to corrode rapidly. Test panels installed in the walls of the most severely corroding boiler identified austenitic stainless steel as sufficiently resistant to the new corrosive conditions, and discussions with Sandvik AB, a Swedish tube manufacturer, led to the suggestion that coextruded tubes be used for water wall service in kraft recovery boilers. Replacement of carbon steel by coextruded tubes has solved most of the corrosion problems experienced by carbon steel wall tubes, however, these tubes have not been problem-free. Beginning in early 1995, a multidisciplinary research program funded by the US Department of Energy was established to investigate the cause of cracking in coextruded tubes and to develop improved materials for use in water walls and floors of kraft recovery boilers. One portion of that program, a state-of-the-art review of public- and private-domain documents related to coextruded tube cracking in kraft recovery boilers is reported here. Sources of information that were consulted for this review include the following: tube manufacturers, boiler manufacturers, public-domain literature, companies operating kraft recovery boilers, consultants and failure analysis laboratories, and failure analyses conducted specifically for this project. Much of the information contained in this report involves cracking problems experienced in recovery boiler floors and those aspects of spout and air-port-opening cracking not readily attributable to thermal fatigue. 61 refs.

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

1997-07-01T23:59:59.000Z

205

Thermal fatigue behavior of US and Russian grades of beryllium  

Science Conference Proceedings (OSTI)

A novel technique has been used to test the relative low cycle thermal fatigue resistance of different grades of US and Russian beryllium which is proposed as plasma facing armor for fusion reactor first wall, limiter, and divertor components. The 30 KW electron beam test system at Sandia National Laboratories was used to sweep the beam spot along one direction at 1 Hz. This produces a localized temperature ``spike`` of 750{degrees}C for each pass of the beam. Large thermal stress in excess of the yield strength are generated due to very high spot heat flux, 250 MW/m{sup 2}. Cyclic plastic strains on the order of 0.6% produced visible cracking on the heated surface in less than 3000 cycles. An in-vacuo fiber optic borescope was used to visually inspect the beryllium surfaces for crack initiation. Grades of US beryllium tested included: S-65C, S-65H, S-200F, S-300F-H, Sr-200, I-400, extruded high purity. HIP`d sperical powder, porous beryllium (94% and 98% dense), Be/30% BeO, Be/60% BeO, and TiBe{sub 12}. Russian grades included: TGP-56, TShGT, DShG-200, and TShG-56. Both the number of cycles to crack initiation, and the depth of crack propagation, were measured. The most fatigue resistant grades were S-65C, DShG-200, TShGT, and TShG-56. Rolled sheet Be(SR-200) showed excellent crack propagation resistance in the plane of rolling, despite early formation of delamination cracks. Only one sample showed no evidence of surface melting, Extruded (T). Metallographic and chemical analyses are provided. Good agreement was found between the measured depth of cracks and a 2-D elastic-plastic finite element stress analysis.

Watson, R.D.; Youchison, D.L. [Sandia National Labs., Albuquerque, NM (United States); Dombrowski, D.E. [Brush Wellman, Inc., Cleveland, OH (United States); Guiniatouline, R.N. [Efremov Institute, St. Petersburg (USSR); Kupriynov, I.B. [Russian Inst. of Inorganic Materials, Moscow (USSR)

1996-02-01T23:59:59.000Z

206

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

207

Delayed switching applied to memristor neural networks  

Science Conference Proceedings (OSTI)

Magnetic flux and electric charge are linked in a memristor. We reported recently that a memristor has a peculiar effect in which the switching takes place with a time delay because a memristor possesses a certain inertia. This effect was named the ''delayed switching effect.'' In this work, we elaborate on the importance of delayed switching in a brain-like computer using memristor neural networks. The effect is used to control the switching of a memristor synapse between two neurons that fire together (the Hebbian rule). A theoretical formula is found, and the design is verified by a simulation. We have also built an experimental setup consisting of electronic memristive synapses and electronic neurons.

Wang, Frank Z.; Yang Xiao; Lim Guan [Future Computing Group, School of Computing, University of Kent, Canterbury (United Kingdom); Helian Na [School of Computer Science, University of Hertfordshire, Hatfield (United Kingdom); Wu Sining [Xyratex, Havant (United Kingdom); Guo Yike [Department of Computing, Imperial College, London (United Kingdom); Rashid, Md Mamunur [CERN, Geneva (Switzerland)

2012-04-01T23:59:59.000Z

208

Evaluation of Circumferential Cracking on Supercritical Boiler Waterwalls  

Science Conference Proceedings (OSTI)

Circumferential cracking of the fireside surfaces of supercritical waterwalls remains a problem for many coal-fired boilers. Two parallel test programs at Pennsylvania Power and Light's (PPL) Brunner Island Unit 3 attempted to correlate operating conditions with the development and propagation of circumferential cracks.

2008-03-31T23:59:59.000Z

209

Micro-crack Damage Evolution of Fracturing Rock Chaotic Characteristics  

Science Conference Proceedings (OSTI)

Chaotic theory and bifurcation of modern nonlinear science were used to study the evolution of micro-cracks under the hydraulic fracturing of the rock mass characteristics, the tensor damage variable which described the chao evolution of micro-cracks ... Keywords: chaos theory, bifurcation theory, damage evolution

Zhaowan Chun; Wang Tingting

2010-06-01T23:59:59.000Z

210

WATER PERMEABILITY OF CRACKED CEMENTITIOUS MICHAEL LEPECH & VICTOR C. LI  

E-Print Network (OSTI)

with inherently tight crack widths, typically less than 80 micron, even when strained up to 5% in uniaxial tension to undergo large deformations while maintaining load capacity. Of interest to this study are the tight crack mixture. Mixing proportions of both materials are shown in Table 1. The sand used in ECC had an average

Lepech, Michael D.

211

Fatigue-crack propagation behavior of Inconel 718  

DOE Green Energy (OSTI)

The techniques of linear-elastic fracture mechanics were used to characterize the effect of several variables (temperature, environment, cyclic frequency, stress ratio, and heat-treatment variations) upon the fatigue-crack growth behavior of Inconel 718 base metal and weldments. Relevant crack growth data on this alloy from other laboratories is also presented. (33 fig, 39 references) (auth)

James, L.A.

1975-09-01T23:59:59.000Z

212

Improvements for group delay fringe tracking  

E-Print Network (OSTI)

Group delay fringe tracking using spectrally-dispersed fringes is suitable for stabilising the optical path difference in ground-based astronomical optical interferometers in low light situations. We discuss the performance of group delay tracking algorithms when the effects of atmospheric dispersion, high-frequency atmospheric temporal phase variations, non-ideal path modulation, non-ideal spectral sampling, and the detection artifacts introduced by electron-multiplying CCDs (EMCCDs) are taken into account, and we present ways in which the tracking capability can be optimised in the presence of these effects.

A. G. Basden; D. F. Buscher

2004-11-30T23:59:59.000Z

213

Fatigue Crack Closure and Corrosion Fatigue in Al 7075 Alloy Using ...  

Science Conference Proceedings (OSTI)

Traditional methods to quantify crack closure load, such as load-displacement curves, are not very accurate. In this study, the degree of crack closure through...

214

A Study on Fatigue-Crack-Deformation Behavior Following a Single ...  

Science Conference Proceedings (OSTI)

Apr 27, 2009 ... Width. Using this method, the respective crackopening load (COL) at various crack-growth stages can be determined ?om the curve of the...

215

Induction Heating Stress Improvement Effectiveness on Crack Growth in Operating Plants (BWRVIP-61)  

Science Conference Proceedings (OSTI)

New reports of intergranular stress corrosion cracking prompted this review of factors that could influence the performance of the pipe cracking remedy known as induction heating stress improvement.

1999-01-27T23:59:59.000Z

216

Assessment of Crack in Corrosion Defects in Natural Gas Transmission Pipelines.  

E-Print Network (OSTI)

??Pipelines are one of the safest forms of transportation for oil and gas. However, pipelines may experience some defects, such as cracks, corrosion and cracks (more)

Hosseini, Seyed Aliakbar

2010-01-01T23:59:59.000Z

217

Fast and Delayed Fracture at Various Length Scales in Ceramic ...  

Science Conference Proceedings (OSTI)

Ceramic Matrix Composites for Nuclear and Fusion Energy Crack Propagation in SiC Bicrystals ... Graphene Reinforced Glass and Ceramic Matrix Composites.

218

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

SciTech Connect

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

Bruemmer, Stephen M.; Thomas, Larry E.

2010-04-05T23:59:59.000Z

219

Cracking in liquid petroleum gas Horton spheres  

Science Conference Proceedings (OSTI)

A gas processing plant on the western coast of India produces sweet gas after processing sour natural gas. Liquid petroleum gas (LPG) is recovered from the sweet gas. The LPG, containing a H{sub 2}S concentration of 10 ppm to 20 ppm, is stored in Horton spheres, each 17 m in diameter with a capacity of {minus}27 C to 55 C. Horton spheres for containing liquid petroleum gas (LPG) were fabricated on-site using prestressed plates of high-strength carbon steel (CS) SA 537 Class-1 with post-weld heat treatment. High-residual tensile stresses and hydrogen absorption from H{sub 2}S present in LPG could be the cause of cracking at weld and heat-affected zone interfaces at high hardness locations. Recommendations are given for inspection and use of lower-strength CS and improved welding procedures.

Trivedi, D.K. Gupta, S.C. [Oil and Natural Gas Corp., Surat (India). Hazari Gas Processing Complex

1997-07-01T23:59:59.000Z

220

Can we delay a greenhouse warming  

SciTech Connect

The author comments on the EPA report dated September 1983 Can We Delay A Greenhouse Warming. He takes exception to the widely-held interpretation that the answer is not much. The contribution of other greenhouse gases such as methane and nitrous oxide to the EPA scenarios is pointed out, and the lack of understanding of their role is emphasised. (ACR)

Perry, A.M.

1983-01-01T23:59:59.000Z

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.


221

On reducing energy management delays in disks  

Science Conference Proceedings (OSTI)

Enterprise computing systems consume a large amount of energy, the cost of which contributes significantly to the operating budget. Consequently, dynamic energy management techniques are prevalent. Unfortunately, dynamic energy management for disks impose ... Keywords: Disk energy management, Peer memory sharing, Spin-up delay reduction

Krish K.R., Guanying Wang, Puranjoy Bhattacharjee, Ali R. Butt, Chris Gniady

2013-06-01T23:59:59.000Z

222

Materials Reliability Program: Thermal Fatigue Monitoring Guidelines (MRP-32, Revision 1)  

Science Conference Proceedings (OSTI)

This report provides thermal fatigue monitoring guidelines for attached piping systems in which there might be high potential for thermal fatigue cracking. The Materials Reliability Program (MRP) has published guidance under the Nuclear Energy Institute (NEI) 03-08 materials initiative for addressing potential thermal fatigue cycling in non-isolable reactor coolant system branch lines. This guidance calls for monitoring, inspection, and/or fatigue analysis of susceptible lines.

2011-06-16T23:59:59.000Z

223

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

DOE Green Energy (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

224

THE NON-CONSTANT CTOD/CTOA IN CRACK PROPAGATION  

SciTech Connect

Unlike the common belief that crack propagation behavior can be predicted successfully by employing fracture criteria based on a constant crack tip opening displacement or angle (CTOD/CTOA), this paper shows that the initially non-constant portion of the CTOD/CTOA plays an essential role in predicting the fracture load for a growing crack. Three- and two-dimensional finite element analyses indicate that a severe underestimate of the experimental load vs. crack extension curve would occur if a constant CTOD/CTOA criterion is used. However, the use of a simplified, bilinear CTOD/CTOA criterion including its non-constant portion will closely duplicate the test data. Furthermore, as a result of using the experimental data from J-integral test with various crack length to specimen width ratios (a/W), it is demonstrated that the CTOD/CTOA is crack tip constraint dependent. The initially higher values of the CTOD/CTOA are in fact a natural consequence of crack growth process which is refl ected by the J-resistance curve and its slope (tearing modulus).

LAM, POH-SANG

2004-07-19T23:59:59.000Z

225

Analysis of Alloy 600 and X-750 stress corrosion cracks  

Science Conference Proceedings (OSTI)

A few months ago, KAPL evidence supported the view that Primary or Pure Water Stress Corrosion Cracking (PWSCC) of Alloy 600 results from a hydrogen mechanism. Figure 1 shows an Analytical Electron Microscope (AEM) analysis of a stress corrosion crack (SCC) crack in an A600 split tube U-bend specimen exposed to primary water at 338{degree}C (640{degrees}F) for 462 days. The features which appear to confirm a hydrogen mechanism are: (1) A very narrow (< 200 {angstrom}) crack with a sharp tip, nearly free of deposits. (2) No evidence of severe plastic deformation in the region immediately ahead of the crack tip. (3) A line of small voids preceding the main crack tip, of which the largest is about 5 x 10{sup {minus}6} cm in length. Shen and Shewmon proposed that PWSCC of Alloy 600 occurs due to small microvoids ahead of a main crack tip. The hypothesis is that such voids result from pockets of methane gas formed by the reaction of atomic hydrogen with carbon in the base metal. The voids are about 10 x 10{sup {minus}6} cm diameter, approximately a factor of 2 larger than the largest voids.

Thompson, C.D.; Lewis, N.; Krasodomski, H.

1993-06-01T23:59:59.000Z

226

Improved load ratio method for predicting crack length  

SciTech Connect

The elastic compliance from unloading/reloading sequences in a load-displacement record estimates well crack length in elastic-plastic fracture toughness tests of compact tension [C(T)] and bending type specimens. The need for partial unloading of the specimen makes it difficult to run the test under static loading and impossible under either dynamic loading or very high temperatures. Furthermore, fracture toughness testing in which crack length is determined from elastic compliance requires high precision testing equipment and highly skilled technicians. As a result, such tests are confined usually to research laboratories and seldom used under production settings. To eliminate these problems, an improved load ratio method of predicting crack length is proposed that utilizes only the recorded load versus load-line displacement curve (or load versus crack-mouth-opening displacement curve) without unloading/reloading sequences. As a result, the instrumentation is much simpler than in the elastic compliance or potential drop methods. If only a monotonic load-displacement record is to be measured the fracture toughness test becomes almost as simple to perform as a tension test. The method described here improves in three ways the ``original load ratio method`` proposed by Hu et al. First, a blunting term is added to the crack length before maximum load. Second, a strain hardening correction is included after maximum load. And, third, the initial crack length and the physical (final) crack length measured at the end of the test serve to anchor the predicted crack lengths, forcing agreement between predicted and measured values. The method predicts crack extension with excellent accuracy in specimens fabricated from A302, A508, and A533B piping and pressure vessel steels, A588 and A572 structural steels, and HY-80 ship steel.

Chen, X.; Albrecht, P. [Univ. of Maryland, College Park, MD (United States). Inst. for Systems Research; Wright, W. [Federal Highway Administration, McLean, VA (United States). Turner-Fairbank Highway Research Center; Joyce, J.A. [Naval Academy, Annapolis, MD (United States). Mechanical Engineering Dept.

1995-04-01T23:59:59.000Z

227

Hydrogen-Induced Cracking of the Drip Shield  

DOE Green Energy (OSTI)

Hydrogen-induced cracking is characterized by the decreased ductility and fracture toughness of a material due to the absorption of atomic hydrogen in the metal crystal lattice. Corrosion is the source of hydrogen generation. For the current design of the engineered barrier without backfill, hydrogen-induced cracking may be a concern because the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction. The purpose of this report is to analyze whether the drip shield will fail by hydrogen-induced cracking under repository conditions within 10,000 years after emplacement. Hydrogen-induced cracking is a scenario of premature failure of the drip shield. This report develops a realistic model to assess the form of hydrogen-induced cracking degradation of the drip shield under the hydrogen-induced cracking. The scope of this work covers the evaluation of hydrogen absorbed due to general corrosion and galvanic coupling to less noble metals (e.g., Stainless Steel Type 316 and carbon steels) under the repository conditions during the 10,000-year regulatory period after emplacement and whether the absorbed hydrogen content will exceed the critical hydrogen concentration value, above which the hydrogen-induced cracking is assumed to occur. This report also provides the basis for excluding the features, events, and processes (FEPs) related to hydrogen-induced cracking of the drip shield with particular emphasis on FEP 2.1.03.04.OB, hydride cracking of drip shields (DTN: M00407SEPFEPLA.000 [DIRS 170760]). This report is prepared according to ''Technical Work Plan (TWP) for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 169944]).

F. Hua

2004-09-07T23:59:59.000Z

228

Examination of cracked turbine discs from nuclear power plants  

SciTech Connect

Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station (BWR), and on two failed turbine discs from the Yankee-Rowe Nuclear Power Station (PWR). The Yankee-Rowe discs were subjected to SEM/EDAX, uniaxial tension tests, hardness testing, notch sensitivity tests, and environmental notched tensile tests. The results of this investigation support the model whereby the cracks initiated at startup of the turbine, probably from H/sub 2/S produced by hydrolysis of MoS/sub 2/, and grew at a rate consistent with published data for propagation of cracks in pure steam.

Czajkowski, C.J.; Weeks, J.R.

1983-03-01T23:59:59.000Z

229

Shale oil cracking. 2. Effect on oil composition  

DOE Green Energy (OSTI)

Results from spectroscopic investigations are presented that demonstrate the effect of oil cracking on shale oil composition. Techniques used include infrared spectroscopy, capillary column gas chromatography/mass spectroscopy and /sup 13/C nuclear magnetic resonance. We show that cracking causes an increase in aromatic and alkene content of the oil. We compare our results for oils prepared in the laboratory with oils prepared in the TOSCO-II semi-works and in modified and true-in-situ combustion retorts. We demonstrate that the napthalene/2-methyl-naphthalene ratio is a good indicator of cracking conditions in an oil shale retort.

Burnham, A.K.; Sanborn, R.H.; Crawford, R.W.; Newton, J.C.; Happe, J.A.

1980-08-01T23:59:59.000Z

230

Evaluation of Cracks in ABB HK Arc Chutes  

Science Conference Proceedings (OSTI)

The nuclear power industry has a number of medium voltage (5 Kv-15 Kv) ABB HK air-magnetic circuit breakers with cracks in various places on the ceramic liner plate and cold-molded asbestos portions of the arc chutes. These cracks may or may not be cosmetic. This "jump gap crack" issue has been discussed in several ABB circuit breaker users group meetings. Five utilities (Brunswick, Seabrook, TVA, Duke, and Vogtle) have previously expressed interest in this issue. The present ABB Quality Assurance Proced...

2005-05-03T23:59:59.000Z

231

Strategies for planar crack propagation based on the concept of material forces  

Science Conference Proceedings (OSTI)

This paper presents a computational framework for the simulation of planar crack growth (including kinking) driven by "material forces". An evolution law for the crack tip position is formulated, which is shown to give rise to different propagation strategies ... Keywords: Configurational forces, Crack curving, Crack propagation

Jim Brouzoulis; Fredrik Larsson; Kenneth Runesson

2011-03-01T23:59:59.000Z

232

Coherence delay augmented laser beam homogenizer  

SciTech Connect

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

233

Irradiation-Induced Stress Corrosion Cracking of Austenitic Stainless  

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

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

234

Environmentally Assisted Cracking of Ni-Base Alloys [Corrosion and  

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

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

235

Crack coalescence in rock-like material under cycling loading  

E-Print Network (OSTI)

A total of 170 tests (68 tests for monotonic loading, 102 tests for cyclic loading) have been performed to investigate crack initiation, propagation and coalescence. The specimens have two pre-existing flaws which are ...

Ko, Tae Young, 1973-

2005-01-01T23:59:59.000Z

236

Evaluation of Stress Corrosion Cracking Susceptibility of Drill Pipe ...  

Science Conference Proceedings (OSTI)

G-105 and S-135 grades of drill pipe steels have been used to study the effect of temperature and solution chemistry on the stress corrosion cracking behavior of...

237

SLAC National Accelerator Laboratory - SLAC Research Cracks Puzzle...  

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

Press Release Archive SLAC Research Cracks Puzzle of Enzyme Critical to Food Supply November 17, 2011 Menlo Park, Calif. - If we could make plant food from nitrogen the way nature...

238

3D Characterization and Modeling of Fatigue Cracks  

Science Conference Proceedings (OSTI)

The HEDM and CT are performed with high energy x-rays at the Advanced Photon Source (APS). One set of LSHR specimens has small cracks on the order of...

239

Cracked shaft detection and diagnostics: A literature review  

E-Print Network (OSTI)

ABSTRACTCracks in shafts have long been identified as factors limiting the safe and reliable operation of turbomachines. They can sometimes result in catastrophic failure of equipment (rotor bursts) and, more often, in costly process upsets, repairs and premature scrapping and replacement of equipment. Cracked shafts still pose a significant and real threat to equipment in spite of the great advances made in the areas of metallurgy, manufacturing and design. In the past two decades, much research and many resources have gone into developing various on-line and off-line diagnostic techniques to effectively detect cracks before they cause serious damage. Because of the enormous amount of ongoing research in this area (more than 500 technical papers have been published in English alone in the past 30 years), there is a real need to periodically condense and summarize the information. This paper reviews literature on cracked shaft detection and diagnostics published after 1990.

Giridhar Sabnavis; R. Gordon Kirk; Mary Kasarda; Dane Quinn; Giridhar Sabnavis; R. Gordon Kirk; Mary Kasarda; Dane Quinn

2004-01-01T23:59:59.000Z

240

Effect of Oxygen Potential on Crack Growth in Alloy 617  

Science Conference Proceedings (OSTI)

Static crack growth rate increases from 4 x 10-9 m/sec to 4 x 10-8 m/sec when the oxygen concentration decreases from .001 to .0000001 atm. Proceedings...

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

Process to minimize cracking of pyrolytic carbon coatings  

DOE Patents (OSTI)

Carbon-coated microspheroids useful as fuels in nuclear reactors are produced with a low percentage of cracked coatings and are imparted increased strength and mechanical stability characteristics by annealing immediately after the carbon coating processes.

Lackey, Jr., Walter J. (Oak Ridge, TN); Sease, John D. (Knoxville, TN)

1978-01-01T23:59:59.000Z

242

Temperature dependence of the intrinsic small fatigue crack growth behavior in Ni-base superalloys based on measurement of crack closure  

Science Conference Proceedings (OSTI)

The effect of temperature on the small fatigue crack growth behavior of a single crystal and directionally solidified Ni-base superalloys was investigated at temperatures between 873 to 1,123 K by measuring the crack closure. The results were also compared with those of the physically long crack. It was found that the propagation resistance and the fatigue threshold of the long cracks increased with temperature in all the materials. The long crack growth rates at three temperatures were approximately represented by an unique curve, after taking account of crack closure level and elastic modulus. In contrast, the small crack growth resistance decreased with temperature even when the crack closure phenomenon was taken into consideration. Furthermore, the small fatigue cracks exhibited considerably higher growth rates than the long cracks at a given effective stress intensity factor range and also grew under effective stress intensity factor ranges below the long crack threshold. The factors responsible for the lack of similitude in propagation rates between small and long cracks were also discussed, based on these observations and the chemical analysis near the crack tip using the electron probe microanalyzer.

Okazaki, M.; Yamada, H. [Nagaoka Univ. of Technology (Japan). Dept. of Mechanical Engineering; Nohmi, S. [Kawasaki Heavy Industries Co. Ltd., Akashi (Japan)

1996-04-01T23:59:59.000Z

243

High-level test synthesis for delay fault testability  

Science Conference Proceedings (OSTI)

A high-level test synthesis (HLTS) method targeted for delay fault testability is presented. The proposed method, when combined with hierarchical test pattern generation for embedded modules, guarantees 100% delay test coverage for detectable faults ...

Sying-Jyan Wang; Tung-Hua Yeh

2007-04-01T23:59:59.000Z

244

Nucleation and growth of cracks in vitreous-bonded aluminum oxide at elevated temperatures  

Science Conference Proceedings (OSTI)

The nucleation and growth of cracks was studied at elevated temperatures on a grade of vitreous-bonded aluminium oxide that contained approx. =8 vol% glass at the grain boundaries. Cracks were observed to nucleate within the vitreous phase, close to the tensile surface of the flexural test specimens used in these experiments. Crack nucleation occurred at a strain of approx. =0.08% to 0.12% which corresponded to a crack nucleation time of approx. =35% of the time to failure by creep rupture. Once nucleated, cracks propagated along grain boundaries, as long as the stress for crack propagation was maintained. The crack velocity for cracks that were nucleated by the creep process was found to be linearly proportional to the apparent stress intensity factor, whereas for cracks that were nucleated by indentation, the crack velocity was proportional to the fourth power of the apparent stress intensity factor.

Jakus, K.; Wiederhorn, S.M.; Hockey, B.J.

1986-10-01T23:59:59.000Z

245

Reliability Centered Lifetime Prediction of Environmentally Assisted Cracking  

Science Conference Proceedings (OSTI)

This report describes the results of joint research sponsored by EPRI in cooperation with Tohoku University and a number of Japanese organizations to address the issue of environmentally assisted cracking (EAC) in boiling water reactors (BWRs) and pressurized water reactors (PWRs). The term EAC includes intergranular stress corrosion cracking and corrosion fatigue. The goal of this project was to develop a fundamental understanding of processes controlling EAC of stainless steels and nickel-base alloys i...

2003-09-02T23:59:59.000Z

246

Crack reconstruction using a level-set strategy  

Science Conference Proceedings (OSTI)

We present a level-set based technique to recover key characteristics of a defect or crack (e.g. location, length and shape) in a two-dimensional material from boundary electrical measurements. The key feature of this work is to extend the usual level-set ... Keywords: 02.30.Zz, 41.20.Cv, 42.30.Wb, Crack reconstruction, Electrical impedance tomography, Level-sets

Diego lvarez; Oliver Dorn; Natalia Irishina; Miguel Moscoso

2009-09-01T23:59:59.000Z

247

Bayesian Inference Underlies the Contraction Bias in Delayed Comparison Tasks  

E-Print Network (OSTI)

Delayed comparison tasks are widely used in the study of working memory and perception in psychology and neuroscience.

Ashourian, Paymon

248

Forward correction and fountain codes in delay-tolerant networks  

Science Conference Proceedings (OSTI)

Delay-tolerant ad hoc networks leverage the mobility of relay nodes to compensate for lack of permanent connectivity and thus enable communication between nodes that are out of range of each other. To decrease delivery delay, the information to be delivered ... Keywords: delay-tolerant networks (DTNs), forward correction, fountain codes, mobile ad hoc networks

Eitan Altman; Francesco De Pellegrini

2011-02-01T23:59:59.000Z

249

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, and migration from condensation of atmospheric moisture. The general corrosion rate of steels under insulation is predictable (within a broad scatter band) on the basis of temperature and oxygen content. This relationship is presented graphically based on plant case histories. Rainwater, washwater and the insulation itself are compared as potential sources of chloride to promote external SCC of stainless steels. Preventative measures will be discussed.

McIntyre, D. R.

1984-01-01T23:59:59.000Z

250

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

251

Multiple use of waste catalysts with and without regeneration for waste polymer cracking  

SciTech Connect

Waste plastics contain a substantial number of valuable chemicals. The wastes from post-consumer as well as from industrial production can be recycled to valuable chemical feedstock, which can be used in refineries and/or petrochemical industries. This chemical recycling process is an ideal approach in recycling the waste for a better environment. Polymer cracking using a laboratory fluidised bed reactor concentrated on the used highly contaminated catalyst, E-Cat 2. Even though E-Cat 2 had low activity due to fewer acid sites, the products yielded were similar with amorphous ASA and were far better than thermal cracking. The high levels of heavy metals, namely nickel and vanadium, deposited during their lifetime as an FCC catalyst, did not greatly affect on the catalyst activity. It was also shown that E-Cat 2 could be used with and without regeneration. Although there was more deactivation when there was no regeneration step, the yield of gases (C{sub 2}-C{sub 7}) remained fairly constant. For the first time, these results indicate that 'waste' FCC catalyst (E-Cat) is a good candidate for future feedstock recycling of polymer waste. The major benefits of using E-Cat are a low market price, the ability to tolerate reuse and regeneration capacity.

Salmiaton, A., E-mail: mie@eng.upm.edu.my [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia (UPM), 43400 UPM Serdang, Selangor (Malaysia); Garforth, A.A. [School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD (United Kingdom)

2011-06-15T23:59:59.000Z

252

Thermal Properties  

Science Conference Proceedings (OSTI)

Table 12   Thermal conductivities of polymers and other materials...40,000 2.8 Aluminum 24,000 1.7 Steel 5000 0.35 Granite 350 0.02 Crown glass (75 wt% silica) 90 0.006 Source: Ref 4...

253

Phase-flip and amplitude death in time delay systems with delayed feedback  

E-Print Network (OSTI)

We consider a network of delay dynamical systems connected in a ring via unidirectional positive feedback with the delay in coupling being modulated in time. For the specific case of Mackey-Glass systems on the ring topology, we capture the phenomena of amplitude death, synchronization and phase-flip bifurcation in our model as the relevant parameters are tuned. Using linear stability analysis we predict the region of amplitude death in the parameter space and study the nature of transitions between the different states. For a large number of systems in the same dynamical configuration, we observe splay states, mixed splay states and phase locked clusters.

Chiranjit Mitra; G. Ambika; Soumitro Banerjee

2013-12-11T23:59:59.000Z

254

Effects of delaying the operation of a nuclear power plant  

Science Conference Proceedings (OSTI)

This report documents a study of an actual 24-month nuclear power plant licensing delay. A representative utility was chosen for examination. The research was oriented toward determination of the licensing delay's impact on the utility's operating results, ratepayers, and security issues. The methodology utilized to estimate those impacts involved the recursive interaction of a generation costing program to estimate replacement fuel costs and a financial regulatory model to concomitantly determine the impact on the utility, its ratepayers and security issues. The latter model was executed under six alternate scenarios: (1) no delay in the plant's operation; (2) a 24-month delay; (3) a 24-month delay but further assuming all replacement power was generated by coal-fired plants; (4) a 24-month delay assuming all replacement power from oil-fired plants; (5) no delay but assuming the capital cost of the plant was twice as large; and (6) a 24-month delay with the capital cost of the plant twice as large. Three primary conclusions were made. First, under all scenarios, a 24-month delay in operation of the plant has an adverse impact on the utility's internal generation of funds. Second, although electricity rates are not appreciably affected by the delay, the direction of electricity price changes is contingent on the source of fuel used for replacement power. Finally, a 24-month delay has an adverse impact on the indicators used to evaluate the financial soundness of the utility in all cases under consideration.

Hill, L.J.; Rainey, J.A.; Tepel, R.C.; Van Dyke, J.W.

1983-12-01T23:59:59.000Z

255

BWRVIP-196: BWR Vessel and Internals Project, Assessment of Mixing Tee Thermal Fatigue Susceptibility in BWR Plants  

Science Conference Proceedings (OSTI)

In 1998, a French pressurized water reactor (PWR) plant experienced leakage due to thermal fatigue from piping immediately downstream of a residual heat removal (RHR) heat exchanger. EPRI report 1013305, Materials Reliability Program: Assessment of RHR Mixing Tee Thermal Fatigue in PWR Plants (MRP-192), December 2006, was prepared so that owners of PWR plants could determine if their RHR piping systems might be susceptible to similar thermal fatigue cracking and if additional inspection should be recomme...

2008-09-23T23:59:59.000Z

256

Uptake swelling and thermal expansion of CFRP tendons  

E-Print Network (OSTI)

research. Changes in the concrete cover do not have much of an influence on the maximum hoop stress generated. However, this should be treated with caution since the analysis in Figure 11 only considers elastic behaviour up to first cracking. The concrete... composites. Journal of Composite Materials, 1978, 12, No. 2, 153168. 15. TOMPKINS S. S. Thermal expansion of selected graphite- reinforced polyimide-, epoxy- and glass-matrix composites. International Journal of Thermophysics, 1987, 8, No. 1, 119132. 16...

Scott, P.; Lees, Janet M.

2009-08-01T23:59:59.000Z

257

Coherence delay augmented laser beam homogenizer  

DOE Patents (OSTI)

It is an object of the present invention to provide an apparatus that can reduce the apparent coherence length of a laser beam so the beam can be used with an inexpensive homogenizer to produce an output beam with a uniform spatial intensity across its entire cross section. It is a further object of the invention to provide an improved homogenizer with a variable aperture size that is simple and easily made. It is still an additional object of the invention to provide an improved liquid filled homogenizer utilizing total internal reflection for improved efficiency. These, and other objects of the invention are realized by using a ``coherence delay line,`` according to the present invention, in series between a laser and a homogenizer. The coherence delay line is an optical ``line`` that comprises two mirrors, one partially reflecting, and one totally reflecting, arranged so that light incident from the laser first strikes the partially reflecting mirror. A portion of the beam passes through, and a portion is reflected back to the totally reflecting mirror.

Rasmussen, P.; Bernhardt, A.

1991-12-31T23:59:59.000Z

258

Crack Surface Roughness in Three-Dimensional Random Fuse Networks  

SciTech Connect

Using large system sizes with extensive statistical sampling, we analyze the scaling properties of crack roughness and damage profiles in the three-dimensional random fuse model. The analysis of damage profiles indicates that damage accumulates in a diffusive manner up to the peak load, and localization sets in abruptly at the peak load starting from a uniform damage landscape. The global crack width scales as $W \\sim L^{0.5}$ and is consistent with the scaling of localization length $\\xi \\sim L^{0.5}$ used in the data collapse of damage profiles in the post-peak regime. This consistency between the global crack roughness exponent and the post-peak damage profile localization length supports the idea that the post-peak damage profile is predominantly due to the localization produced by the catastrophic failure, which at the same time results in the formation of the final crack. Finally, the crack width distributions can be collapsed for different system sizes and follow a log-normal distribution.

Nukala, Phani K [ORNL; Zapperi, Stefano [University of La Sapienza, Rome; Simunovic, Srdjan [ORNL

2006-01-01T23:59:59.000Z

259

AQUIFER THERMAL ENERGY STORAGE  

E-Print Network (OSTI)

aquifers for thermal energy storage. Problems outlined aboveModeling of Thermal Energy Storage in Aquifers," Proceed-ings of Aquifer Thermal Energy Storage Workshop, Lawrence

Tsang, C.-F.

2011-01-01T23:59:59.000Z

260

AQUIFER THERMAL ENERGY STORAGE  

E-Print Network (OSTI)

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

Tsang, C.-F.

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.


261

Angle of crack propagation for a vertical hydraulic fracture  

DOE Green Energy (OSTI)

Using the strain-energy-density-factor (S) theory, the positive fracture angle +theta/sub o/ (the initial fracture angle of crack propagation) of a near-vertical crack is predicted by using the opening- and sliding-mode stress-intensity factors in the presence of the overburden pressure, the least in situ horizontal principal stress, and the borehole fluid pressure. The crack spreads in the positive theta/sub o/ direction (counter-clockwise) in the plane for which S is a minimum, S/sub min/. It was verified that S/sub min/ is greater than or equal to S/sub c/. The quantity S/sub c/ is defined as the critical value of S, and remains essentially constant. Of interest is the numerical example for calculating fracture angle and the critical uniform borehole fluid pressure required to initiate fracture at such an angle for the present LASL Dry Hot Rock Geothermal Energy Program. (auth)

Sarda, J.P.; Hsu, Y.C.

1975-12-01T23:59:59.000Z

262

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

263

Cracking Condition of Cohesionless Porous Materials in Drying Processes  

E-Print Network (OSTI)

The invasion of air into porous systems in drying processes is often localized in soft materials, such as colloidal suspensions and granular pastes, and it typically develops in the form of cracks before ordinary drying begins. To investigate such processes, we construct an invasion percolation model on a deformable lattice for cohesionless elastic systems, and with this model we derive the condition under which cracking occurs. A Griffith-like condition characterized by a dimensionless parameter is proposed, and its validity is checked numerically. This condition indicates that the ease with which cracking occurs increases as the particles composing the material become smaller, as the rigidity of the system increases, and as the degree of heterogeneity characterizing the drying processes decreases.

So Kitsunezaki

2013-01-15T23:59:59.000Z

264

Stress corrosion cracking of candidate waste container materials  

SciTech Connect

Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca Mountain site in Nevada. These materials are Type 304L stainless steel (SS), Type 316L SS, Incology 825, P-deoxidized Cu, Cu-30%Ni, and Cu-7% Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks, and to assess the relative resistance of these materials to stress corrosion cracking (SCC). A series of slow-strain-rate tests (SSRTs) in simulated Well J-13 water which is representative of the groundwater present at the Yucca Mountain site has been completed, and crack-growth-rate (CGR) tests are also being conducted under the same environmental conditions. 13 refs., 60 figs., 22 tabs.

Maiya, P.S.; Soppet, W.K.; Park, J.Y.; Kassner, T.F.; Shack, W.J.; Diercks, D.R.

1990-11-01T23:59:59.000Z

265

Cracking a Cold Case and Enduring Mystery | Department of Energy  

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

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

266

Dynamic crack initiation toughness : experiments and peridynamic modeling.  

SciTech Connect

This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.

Foster, John T.

2009-10-01T23:59:59.000Z

267

Weld solidification cracking in 304 to 204L stainless steel  

Science Conference Proceedings (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

268

Weld solidification cracking in 304 to 304L stainless steel  

Science Conference Proceedings (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

269

Materials Reliability Program: Lessons Learned from PWR Thermal Fatigue Management Training (MRP-83)  

Science Conference Proceedings (OSTI)

In January 2001, The EPRI Materials Reliability Program (MRP) issued an Interim Guideline (MRP-24) for the management of thermal fatigue in non-isolable piping attached to reactor coolant piping in pressurized water reactor (PWR) plants (EPRI report 1000701). To assist utility personnel in understanding the potential for thermal fatigue in this piping, the MRP also conducted plant-specific workshops at plant sites. These workshops offered training on fatigue and fatigue cracking in non-isolable piping, a...

2002-12-05T23:59:59.000Z

270

Thermal Modeling, Characterization and Management of On-chip Networks  

E-Print Network (OSTI)

Due to the wire delay constraints in deep submicron technology and increasing demand for on-chip bandwidth, networks are becoming the pervasive interconnect fabric to connect processing elements on chip. With ever-increasing power density and cooling costs, the thermal impact of onchip networks needs to be urgently addressed.

Li Shang; Li-shiuan Peh; Amit Kumar; Niraj K. Jha

2004-01-01T23:59:59.000Z

271

Scattering and; Delay, Scale, and Sum Migration  

SciTech Connect

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

272

Delayed Radiation-Induced Vasculitic Leukoencephalopathy  

SciTech Connect

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

273

Microsecond delays on non-real time operating systems  

SciTech Connect

We have developed microsecond timing and profiling software that runs on standard Windows and Linux based operating systems. This software is orders of magnitudes better than most of the standard native functions in wide use. Our software libraries calibrate RDTSC in microseconds or seconds to provide two different types of delays: a ''Guaranteed Minimum'' and a precision ''Long Delay'', which releases to the kernel. Both return profiling information of the actual delay.

Angstadt, R.; Estrada, J.; Diehl, H.T.; Flaugher, B.; Johnson, M.; /Fermilab

2007-05-01T23:59:59.000Z

274

Predicting Ignition Delay for Gas Turbine Fuel Flexibility  

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

Predicting Ignition Delay for Gas Turbine Fuel Flexibility 15 m * Low emission combustion systems have been carefully optimized for natural gas * Future fuel diversity (including...

275

Delayed Start or Cancellation of Business Hours | Argonne National...  

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

Twitter Delayed Start or Cancellation of Business Hours Winter Road Closings Winter Weather FAQs Westgate Alternate Routes Reporting IllegalUnethical Activity Working Remotely...

276

Crack Growth in Solid Oxide Fuel Cell Materials: From Discrete to Continuum Damage Modeling  

Science Conference Proceedings (OSTI)

This paper addresses the cracking problem of glass and ceramic materials used in solid oxide fuel cells (SOFCs). Analyses of an internal crack and of an interface crack between dissimilar materials were conducted using a modified boundary layer modeling approach. In this approach, fracture is allowed to occur in a small process window situated at an initial crack tip. Elastic displacement crack-tip fields are prescribed as remote boundary conditions. Crack propagation was first modeled discretely. Next, a continuum damage mechanics (CDM) model for brittle materials was developed to capture damage and crack growth in the process window. In particular, the damage model was applied to a glass-ceramic material that had been developed in-house for sealing purposes. Discrete and continuum damage solutions were then compared. Finally, the CDM model was used to determine the crack propagation direction as a function of a mode mixity measure.

Nguyen, Ba Nghiep; Koeppel, Brian J.; Ahzi, Said; Khaleel, Mohammad A.; Singh, Prabhakar

2006-04-01T23:59:59.000Z

277

Dielectric magnifying of plasma blocks by nonlinear force acceleration with delayed electron heating  

Science Conference Proceedings (OSTI)

Specific studies were performed in order to increase the thickness of laser generated directed space charge quasineutral plasma blocks with anomalously high ion current densities above 10{sup 11} A/cm{sup 2}. This may lead to an alternative scheme of laser driven fusion with the irradiation of petawatt-picosecond laser pulses. Initial electron densities were used with Rayleigh profiles, because these are unique for inhomogeneous plasmas for undistorted acceleration at very low reflectivity until thermal absorption processes disturb these ideal conditions. Numerical hydrodynamic results based on a genuine two-fluid code are presented to optimize the block generation for possible fast ignition and details show the delay of thermal exchange between the ion and electron plasma fluid.

Sadighi-Bonabi, Rasoul [Department of Physics, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of); Yazdani, Elnaz [Department of Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of) and Laser and Optics Research School P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Cang Yu [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Hora, Heinrich [Department of Theoretical Physics, University of New South Wales, Sydney 2052 (Australia)

2010-11-15T23:59:59.000Z

278

Laboratory And Field Investigations To Address Erosion, Volume Change And Desiccation Cracking Of Compost Amended Expansive Subsoils.  

E-Print Network (OSTI)

??Puppala, Anand Desiccations cracks are formed during drying process of fine grained cohesive soils in summer and these cracks often appear on unpaved subgrades due (more)

Intharasombat, Napat

2007-01-01T23:59:59.000Z

279

Status Report on Studies of Recovery Boiler Composite Floor Tube Cracking  

DOE Green Energy (OSTI)

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

280

Influence of p-method finite element parameters on predictions of crack front geometry  

Science Conference Proceedings (OSTI)

The effect of various p-method finite element model parameters on the prediction of planar crack front geometry in three dimensional structures is evaluated. An automatic crack growth method was developed using the commercial software StressCheck coupled ... Keywords: ?, Corner crack, Crack front, Finite element, Mesh, Stress intensity factor, a, b, b/a, c, ctrat, ipr, m, mrat, p-method, trans

Diane Wowk, Kyle Gamble, Ross Underhill

2013-10-01T23:59:59.000Z

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

Effect of Specimen Size on the Crack Growth Rate Behavior of Irradiated Type 304 Stainless Steel  

Science Conference Proceedings (OSTI)

BackgroundCracks in actual plant components are mainly under plane strain. In order to generate relevant crack growth rate data in the laboratory, specimens where most of the crack front is under plane strain should be used. Since the ASTM E399 size criterion for linear elastic plane-strain fracture toughness is probably conservative, it seems appropriate to also apply it to SCC tests. However, in stress corrosion crack growth rate (CGR) tests on austenitic stainless ...

2012-12-21T23:59:59.000Z

282

Delayed neutron measurements for Th-232, Np-237, Pu-239, Pu-241 and depleted uranium  

E-Print Network (OSTI)

The neutron emission rates from five very pure actinide samples (Th-232, Np-237, Pu-239, Pu-241 and depleted uranium) were measured following equilibrium irradiation in fast and thermal neutron fluxes. The relative abundances (alphas) for the first four groups were calculated from the delayed neutron emission (counts vs. time) data using Keepin's 6-group decay constants (lambdas) for Th-232, Pu-239 and depleted uranium (both fast and thermal neutron induced fissions). The relative abundances (alphas) for the first five groups were calculated for the fast neutron induced fission of Np-237 using the 7-group lambdas obtained by Charlton (1997). The relative abundances for the first five groups were also calculated using the 7-group lambdas proposed by Loaiza and Haskin (2000), the 8-group lambdas proposed by Campbell and Spriggs (1998) and the 8-group lambdas proposed by Piksaikin (2000) for all of the samples (fast neutron induced fission only for Th-232 and Np-237, fast and thermal neutron induced fission for the remainder). Fission product yield and delayed neutron emission probability data from the ENDF-349 and JEF 2.2 nuclear data libraries were also used to simulate neutron emission data from the samples. The calculated neutron yield curves were used to obtain group relative abundances for each of the five actinide samples (fast neutron induced fission only for Th-232 and Np-237, fast and thermal neutron induced fission for the remainder) based on each set of proposed lambdas. The relative abundances obtained from the experiments and calculations are compared and the differences are noted and discussed.

Stone, Joseph C.

2001-01-01T23:59:59.000Z

283

Low cycle thermal fatigue testing of beryllium grades for ITER plasma facing components  

Science Conference Proceedings (OSTI)

A novel technique has been used to test the relative low cycle thermal fatigue resistance of different grades of US and Russian beryllium, which is proposed as plasma facing armor for fusion reactor first wall, limiter, and divertor components. The 30 kW electron beam test system at Sandia National Laboratories was used to sweep the beam spot along one direction at 1 Hz. This produces a localized temperature ``spike`` of 750{degree}C for each pass of the beam. Large thermal stresses in excess of the yield strength are generated due to very high spot heat flux, 250 MW/m{sup 2}. Cyclic plastic strains on the order of 0.6% produced visible cracking on the heated surface in less than 3000 cycles. An in-vacuo fiber optic borescope was used to visually inspect the beryllium surfaces for crack initiation. Grades of US beryllium tested included: S-65C, S- 65H, S-200F, S-200F-H, SR-200, I-400, extruded high purity, HIP`d spherical powder, porous beryllium (94% and 98% dense), Be/30% BeO, Be/60% BeO, and TiBe{sub 12}. Russian grades included: TGP-56, TShGT, DShG-200, and TShG-56. Both the number of cycles to crack initiation, and the depth of crack propagation, were measured. The most fatigue resistant grades were S-65C, DShG-200, TShGT, and TShG-56. Rolled sheet Be (SR-200) showed excellent crack propagation resistance in the plane of rolling, despite early formation of delamination cracks. Only one sample showed no evidence of surface melting, Extruded (T). Metallographic and chemical analyses are provided. Good agreement was found between the measured depth of cracks and a 2-D elastic-plastic finite element stress analysis.

Watson, R.D.; Youchison, D.L. [Sandia National Labs., Livermore, CA (United States); Dombrowski, D.E. [Brush Wellman, Inc., Cleveland, OH (United States); Guiniatouline, R.N. [Efremov Institute, (Russia); Kupriynov, I.B. [Russian Institute of Inorganic Materials (Russia)

1996-02-01T23:59:59.000Z

284

A computational study of the time dependent crack growth process  

SciTech Connect

Universal studies of creep crack growth for (1) constant load and (2) variable load cases are presented. Results of the constant load cases is compared to experiment. The behavior of displacements and integral creep for fracture parameters are discussed for both load cases. The need for using a constitutive law which can handle cyclic creep is discussed.

Brust, F.W.; Krishnaswamy, P.

1992-01-01T23:59:59.000Z

285

Ductile Fracture Handbook, Volume 1: Circumferential Throughwall Cracks  

Science Conference Proceedings (OSTI)

Over the past 10 years, the focus of fracture research related to nuclear power plants has shifted from brittle fractures to fractures of steels used for piping and vessels. This handbook developed by EPRI and Novetech Corporation is the first single-source document containing formulas for evaluating throughwall cracks in these tough ductile steels.

1989-07-01T23:59:59.000Z

286

Method of making crack-free zirconium hydride  

DOE Patents (OSTI)

Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

Sullivan, Richard W. (Denver, CO)

1980-01-01T23:59:59.000Z

287

Fatigue crack growth estimation by relevance vector machine  

Science Conference Proceedings (OSTI)

The investigation of damage propagation mechanisms on a selected safety-critical component or structure requires the quantification of its remaining useful life (RUL) to verify until when it can continue performing the required function. In this work, ... Keywords: Bayesian techniques, Fatigue crack growth, Prognostics, Relevance vector machine, Residual useful life, Support vector machine

Enrico Zio; Francesco Di Maio

2012-09-01T23:59:59.000Z

288

Solvent control of crack dynamics in a reversible hydrogel  

E-Print Network (OSTI)

The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the cutting/slicing and eating characteristics of food gels. It is also critical for their utilization in tissue engineering, for which mechanical protection of encapsulated components is needed. Its dependence on loading rate and, recently, on the density and strength of cross-links has been investigated. But no attention was paid so far to solvent nor to environment effects. Here we report a systematic study of crack dynamics in gels of gelatin in water/glycerol mixtures. We show on this model system that: (i) increasing solvent viscosity slows down cracks; (ii) soaking with solvent increases markedly gel fragility; (iii) tuning the viscosity of the (miscible) environmental liquid affects crack propagation via diffusive invasion of the crack tip vicinity. The results point toward the fact that fracture occurs by viscoplastic chain pull-out. This mechanism, as well as the related phenomenology, should be common to all reversibly cross-linked (physical) gels.

Tristan Baumberger; Christiane Caroli; David Martina

2006-05-16T23:59:59.000Z

289

Catalytic cracking. (Latest citations from the Compendex database). Published Search  

Science Conference Proceedings (OSTI)

The bibliography contains citations concerning applications of catalytic cracking processes in fluidized bed systems, moving beds, refineries, vacuum distillations, and reformers. Design aspects, modeling, control systems, and operating procedures are also discussed. (Contains a minimum of 149 citations and includes a subject term index and title list.)

Not Available

1993-07-01T23:59:59.000Z

290

Incipient Crack Detection in Composite Wind Turbine Blades  

DOE Green Energy (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

291

Early Development Of Stress Corrosion Cracks At The Grain Scale: Incomplete Random Tessellation Model  

E-Print Network (OSTI)

Early Development Of Stress Corrosion Cracks At The Grain Scale: Incomplete Random Tessellation is needed to quantify those effects more accurately. 1 INTRODUCTION Intergranular stress corrosion cracking to the dependence of microscopic stress fields at crack tips on the random orientation of neighboring grains

Cizelj, Leon

292

Age-based preventive maintenance for passive components submitted to stress corrosion cracking  

Science Conference Proceedings (OSTI)

This paper deals with an age-based preventive maintenance for critical systems or structures subject to a gradual degradation phenomenon such as stress corrosion cracking. We analyze a system subjected to different cracks. A crack can be only detected ... Keywords: Age-based maintenance, Counting processes, Gamma process, Non-homogeneous Poisson process, SCC models

I. T. Castro; Anne Barros; Antoine Grall

2011-07-01T23:59:59.000Z

293

Permeability and elastic properties of cracked glass under pressure A. OugierSimonin,1  

E-Print Network (OSTI)

on slow crack growth and stress corrosion processes [Wiederhorn, 1966; Anderson and Grew, 1977; Atkinson for independent controls of the confining pressure, the axial stress, and pore pressure. We produced cracks, to our knowledge, none con- sidered crack evolution under compressive stress. Some of this work explored

Fortin, Jérôme

294

How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks  

SciTech Connect

Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (<600 mu m) cracks propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

2008-05-10T23:59:59.000Z

295

Uplift Pressures in Cracks in Concrete Gravity Dams--An Experimental Study: Volume 8  

Science Conference Proceedings (OSTI)

Uplift pressure distribution in cracks in concrete dams is affected by a combination of several factors, such as crack properties, drain dimensions, and the type of flow in the crack. This study shows that most uplift pressure distributions can be controlled using a vertical drain system with diameters from two to four inches and spacing of about ten feet.

1992-12-20T23:59:59.000Z

296

Estimating Beijing's travel delays at intersections with floating car data  

Science Conference Proceedings (OSTI)

In this paper, we presented a technical framework to calculate the turn delays on road network with floating car data (FCD). Firstly the original FCD collected with GPS equipped taxies was cleaned and matched to a street map with a distributed system ... Keywords: float car data, intersection delay, principal curves, trajectory

Xiliang Liu; Feng Lu; Hengcai Zhang; Peiyuan Qiu

2012-11-01T23:59:59.000Z

297

Delay and resource analysis in MANETs in presence of throwboxes  

Science Conference Proceedings (OSTI)

This paper addresses the delay analysis and resource consumption in mobile ad hoc networks (MANETs) equipped with throwboxes. Throwboxes are stationary, wireless devices that act as relays, and that are deployed to increase the connectivity between mobile ... Keywords: Delay analysis, MANET, Markov models, Mobility model, Throwbox

Mouhamad Ibrahim; Ahmad Al Hanbali; Philippe Nain

2007-10-01T23:59:59.000Z

298

Thermal conductivity of thermal-battery insulations  

DOE Green Energy (OSTI)

The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.

Guidotti, R.A.; Moss, M.

1995-08-01T23:59:59.000Z

299

Broadband optical delay with large dynamic range using atomic dispersion  

E-Print Network (OSTI)

We report on a tunable all-optical delay line for pulses with optical frequency within the Rb $D_2$ absorption line. Pulses of 10 ns duration are delayed in a 10 cm hot vapour cell by up to 40 ns where the transmission reduces to approximately 10%. Using an optical frequency between absorption components from different isotopes allows the delay to be increased or decreased by optical pumping with a second laser, producing rapid tuning over a range more than 40% of the initial delay. We investigate the frequency and intensity ranges in which this delay line can be realised. Our observations are in good agreement with a numerical model of the system.

Vanner, M R; Sidorov, A I; Hannaford, P; Akulshin, A M

2007-01-01T23:59:59.000Z

300

Metastability evaluation method by propagation delay distribution measurement  

Science Conference Proceedings (OSTI)

This paper suggests an experimental method for determining metastability properties based on deliberately inducing metastability in edge-triggered flip-flops. It offers the opportunity to analyze the impact of input signals time relationship on the output ... Keywords: MTBF, PLD, VLSI, analytical representation, asynchronous circuits, asynchronous logic, automatic data acquisition, complex architecture microsystems, custom CMOS, data acquisition, delays, edge-triggered flip-flops, failure analysis, fault diagnosis, fault events, flip-flop normal propagation delay, flip-flops, graphical representation, input signals time relationship, integrated circuit reliability, integrated propagation delay density distribution function, latch devices, logic design, logic testing, metastability, output signal timing characteristics, propagation delay density distribution function, propagation delay distribution measurement, reliability analysis, resolution time constant, statistical measurement

B. M. Rogina; B. Vojnovic

1995-11-01T23:59:59.000Z

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

Dynamic Thermal Management for High-Performance Storage Systems  

Science Conference Proceedings (OSTI)

Thermal-aware design of disk drives is important because high temperatures can cause reliability problems. Dynamic Thermal Management (DTM) techniques have been proposed to operate the disk at the average case temperature, rather than at the worse case by modulating the activities to avoid thermal emergencies. The thermal emergencies can be caused by unexpected events, such as fan-breaks, increased inlet air temperature, etc. One of the DTM techniques is a delay-based approach that adjusts the disk seek activities, cooling down the disk drives. Even if such a DTM approach could overcome thermal emergencies without stopping disk activity, it suffers from long delays when servicing the requests. Thus, in this chapter, we investigate the possibility of using a multispeed disk-drive (called dynamic rotations per minute (DRPM)) that dynamically modulates the rotational speed of the platter for implementing the DTM technique. Using a detailed performance and thermal simulator of a storage system, we evaluate two possible DTM policies (- time-based and watermark-based) with a DRPM disk-drive and observe that dynamic RPM modulation is effective in avoiding thermal emergencies. However, we find that the time taken to transition between different rotational speeds of the disk is critical for the effectiveness of the DRPM based DTM techniques.

Kim, Youngjae [ORNL; Gurumurthi, Dr Sudhanva [University of Virginia; Sivasubramaniam, Anand [Pennsylvania State University

2012-01-01T23:59:59.000Z

302

How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks  

Science Conference Proceedings (OSTI)

Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

2008-05-10T23:59:59.000Z

303

Stress corrosion cracking of candidate waste container materials; Final report  

Science Conference Proceedings (OSTI)

Six alloys have been selected as candidate container materials for the storage of high-level nuclear waste at the proposed Yucca mountain site in Nevada. These materials are Type 304L stainless steel (SS). Type 316L SS, Incoloy 825, phosphorus-deoxidized Cu, Cu-30%Ni, and Cu-7%Al. The present program has been initiated to determine whether any of these materials can survive for 300 years in the site environment without developing through-wall stress corrosion cracks. and to assess the relative resistance of these materials to stress corrosion cracking (SCC)- A series of slow-strain-rate tests (SSRTs) and fracture-mechanics crack-growth-rate (CGR) tests was performed at 93{degree}C and 1 atm of pressure in simulated J-13 well water. This water is representative, prior to the widespread availability of unsaturated-zone water, of the groundwater present at the Yucca Mountain site. Slow-strain-rate tests were conducted on 6.35-mm-diameter cylindrical specimens at strain rates of 10-{sup {minus}7} and 10{sup {minus}8} s{sup {minus}1} under crevice and noncrevice conditions. All tests were interrupted after nominal elongation strain of 1--4%. Scanning electron microscopy revealed some crack initiation in virtually all the materials, as well as weldments made from these materials. A stress- or strain-ratio cracking index ranks these materials, in order of increasing resistance to SCC, as follows: Type 304 SS < Type 316L SS < Incoloy 825 < Cu-30%Ni < Cu and Cu-7%Al. Fracture-mechanics CGR tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L stainless steel (SS) and Incoloy 825. Crack-growth rates were measured under various load conditions: load ratios M of 0.5--1.0, frequencies of 10{sup {minus}3}-1 Hz, rise nines of 1--1000s, and peak stress intensities of 25--40 MPa{center_dot}m {sup l/2}.

Park, J.Y.; Maiya, P.S.; Soppet, W.K.; Diercks, D.R.; Shack, W.J.; Kassner, T.F. [Argonne National Lab., IL (United States)

1992-06-01T23:59:59.000Z

304

The nature of fire-cracked rock: new insights from ethnoarchaeological and laboratory experiments  

E-Print Network (OSTI)

Fire-cracked rock (FCR) is the archaeological by-product of the systemic use of hot rocks for cooking and heating purposes. As a record of various cooking and heating facilities, FCR has substantial potential for addressing research questions on past settlement and subsistence systems. To be able to address these questions requires reliable methods that can identify or infer how a given FCR was used. A series of ethnoarchaeological replication experiments are conducted in order to improve the understanding of the geothennodynamics of FCR production. FCR from two experimental data sets are cut to expose flat surfaces that are inspected for thermal-weathering characteristics under low-power magnification. Analytical results indicate that rock structure and the length of heat application have the most control over thermal weathering. The five most important rock structure characteristics are (1) strength of the bond between grains/crystals, (2) degree of porosity, (3) grain/crystal mineralogy, (4) presence of discontinuities, and (5) grain size; thin section analysis can identify these characteristics for any rock sample. The length of heat application varies dependent on the type of cooking or heating facility, for instance, a typical earth oven remains hot for a longer duration than a typical stone-boil facility; multiple uses of a rock in a facility also increases the sum total of heat application. In broad terms, experimental tests indicate igneous rock types withstand thermal weathering better than metamorphic or sedimentary rock types. Ethnoarchaeological results are applied to six archaeological FCR features, and provide new insights on the use-history of five of the features. Microscopic observations of archaeological FCR also all for the re-evaluation of the current model which explains the occurrence of various FCR shape types within features.

Jackson, Michael A

1998-01-01T23:59:59.000Z

305

Coarsening of the Sn-Pb Solder Microstructure in Constitutive Model-Based Predictions of Solder Joint Thermal Mechanical Fatigue  

SciTech Connect

Thermal mechanical fatigue (TMF) is an important damage mechanism for solder joints exposed to cyclic temperature environments. Predicting the service reliability of solder joints exposed to such conditions requires two knowledge bases: first, the extent of fatigue damage incurred by the solder microstructure leading up to fatigue crack initiation, must be quantified in both time and space domains. Secondly, fatigue crack initiation and growth must be predicted since this metric determines, explicitly, the loss of solder joint functionality as it pertains to its mechanical fastening as well as electrical continuity roles. This paper will describe recent progress in a research effort to establish a microstructurally-based, constitutive model that predicts TMF deformation to 63Sn-37Pb solder in electronic solder joints up to the crack initiation step. The model is implemented using a finite element setting; therefore, the effects of both global and local thermal expansion mismatch conditions in the joint that would arise from temperature cycling.

Vianco, P.T.; Burchett, S.N.; Neilsen, M.K.; Rejent, J.A.; Frear, D.R.

1999-04-12T23:59:59.000Z

306

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

Science Conference Proceedings (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 650C 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

307

Integrating Broad-Band High-Fidelity Acoustic Emission Sensors and Array Processing to Study Drying Shrinkage Cracking in Concrete  

E-Print Network (OSTI)

, cracks can create stress concentrations which can cause further cracking at loads which are well under energy released from the formation of a crack is converted into stress waves which in turn produce Shrinkage Cracking in Concrete Gregory C. McLaskeya,1 , Steven D. Glasera , Christian U. Grosseb

Glaser, Steven D.

308

Modeling biological systems with delays in Bio-PEPA  

E-Print Network (OSTI)

Delays in biological systems may be used to model events for which the underlying dynamics cannot be precisely observed, or to provide abstraction of some behavior of the system resulting more compact models. In this paper we enrich the stochastic process algebra Bio-PEPA, with the possibility of assigning delays to actions, yielding a new non-Markovian process algebra: Bio-PEPAd. This is a conservative extension meaning that the original syntax of Bio-PEPA is retained and the delay specification which can now be associated with actions may be added to existing Bio-PEPA models. The semantics of the firing of the actions with delays is the delay-as-duration approach, earlier presented in papers on the stochastic simulation of biological systems with delays. These semantics of the algebra are given in the Starting-Terminating style, meaning that the state and the completion of an action are observed as two separate events, as required by delays. Furthermore we outline how to perform stochastic simulation of Bio...

Caravagna, Giulio; 10.4204/EPTCS.40.7

2010-01-01T23:59:59.000Z

309

Delayed feedback control of fractional-order chaotic systems  

E-Print Network (OSTI)

We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the parameter ranges for successful stabilization of unstable equilibria in the plane parametrizad by the feedback gain and the time delay. An insight into the control mechanism is gained by analyzing the characteristic equation of the controlled system, showing that the control scheme fails to control unstable equilibria having an odd number of positive real eigenvalues. We demonstrate that the method can also stabilize unstable periodic orbits for a suitable choice of the feedback gain, providing that the time delay is chosen to coincide with the period of the target orbit. In addition, it is shown numerically that delayed feedback control with a sinusoidally modulated time delay significantly enlarges the stability region of the steady states in comparison to the classical time-delayed feedback scheme with a constant delay.

Aleksandar Gjurchinovski; Trifce Sandev; Viktor Urumov

2010-05-17T23:59:59.000Z

310

Development of a statistically based access delay timeline methodology.  

SciTech Connect

The charter for adversarial delay is to hinder access to critical resources through the use of physical systems increasing an adversary's task time. The traditional method for characterizing access delay has been a simple model focused on accumulating times required to complete each task with little regard to uncertainty, complexity, or decreased efficiency associated with multiple sequential tasks or stress. The delay associated with any given barrier or path is further discounted to worst-case, and often unrealistic, times based on a high-level adversary, resulting in a highly conservative calculation of total delay. This leads to delay systems that require significant funding and personnel resources in order to defend against the assumed threat, which for many sites and applications becomes cost prohibitive. A new methodology has been developed that considers the uncertainties inherent in the problem to develop a realistic timeline distribution for a given adversary path. This new methodology incorporates advanced Bayesian statistical theory and methodologies, taking into account small sample size, expert judgment, human factors and threat uncertainty. The result is an algorithm that can calculate a probability distribution function of delay times directly related to system risk. Through further analysis, the access delay analyst or end user can use the results in making informed decisions while weighing benefits against risks, ultimately resulting in greater system effectiveness with lower cost.

Rivera, W. Gary; Robinson, David Gerald; Wyss, Gregory Dane; Hendrickson, Stacey M. Langfitt

2013-02-01T23:59:59.000Z

311

Seasonal thermal energy storage  

DOE Green Energy (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

312

"Cracking-the-whip" effect stretches driven polymers  

E-Print Network (OSTI)

Cracking the whip accelerates the tail of a chain to hit the air loudly and clearly. We proved that the similar acceleration effect causes coil deformation of driven chain-like polymers. We first preformed Monte Carlo simulations of a single driven polymer coil to demonstrate its deformation in company with faster or slower deviations of velocities. We then performed parallel Brownian Dynamics simulations to demonstrate that the coil deformation can be caused by the so-called "cracking-the-whip" effect due to non-synchronous biased Brownian motions of monomers inherited in Monte Carlo simulations. Since such non-synchronous motions represent random perturbations in the environmentally dependent potential energy landscape or mobility, reflecting heterogeneous dynamics of polymers in the liquid phase, our observations bring new insights into the non-linear dynamics of driven chain-like polymers.

Juan Li; Wenbing Hu

2013-10-31T23:59:59.000Z

313

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

Science Conference Proceedings (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

314

Impact of delayed neutron precursor mobility in fissile solution systems  

Science Conference Proceedings (OSTI)

A research version of the Monte Carlo software package MCNP6 is modified to incorporate advection and diffusion of delayed neutron precursors, resulting in the emission of delayed neutrons at locations different from the original fission sites. Results of two test problems, a pipe carrying flowing fissile solution and a sphere of fissile solution with precursor diffusion, show that the fission product mobility tends to perturb the fundamental mode, has a negative reactivity effect, and, perhaps most importantly, causes a decrease in the effective delayed neutron fraction. (authors)

Kiedrowski, B. C. [X-Computational Physics Div., Los Alamos National Laboratory, MS A143, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2012-07-01T23:59:59.000Z

315

Environmentally assisted cracking of light-water reactor materials  

SciTech Connect

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

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

1996-02-01T23:59:59.000Z

316

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

317

Gas Turbine Rotor Life: General Electric FA Disc Cracking  

Science Conference Proceedings (OSTI)

This report covers the integrated results of the investigation into the occurrence of cooling slot and other rim cracking found in GE 7FA and 9FA gas turbine first and second stage rotor discs. Sections of the report address dimensional characterization, rim temperature measurement, metallurgical results, analytical methods, evaluation of mitigation approaches, and damage tolerance. Structural stress analysis assessed the effectiveness of the blend-polish-peen slot modification and a redesigned ...

2010-12-08T23:59:59.000Z

318

Stress relief cracking in creep resisting low alloy ferritic steels.  

E-Print Network (OSTI)

The Problem of Stress Relief Cracking in Low Alloy Steels During the welding of a ferritic steel, the HAZ adjacent to the weld transforms to austenite, the grains close to the fusion zone attaining particularly high tempel'ature and undergoing considerable... growth. At the same time, carbides tend to dissolve, dissolution being more complete in the coarse 14 grained region because it attains a higher temperature. The HAZ is cooled rapidly by the cold parent metal and, as a result, re- precipitation...

Tait, Robert Andrew

1976-10-26T23:59:59.000Z

319

Evaluation of Fundamental Linkage Among Stress Corrosion Cracking (SCC) Phenomena  

Science Conference Proceedings (OSTI)

Many in-core components of stainless steels in light water reactors (LWRs) are susceptible to a degradation process known as irradiation assisted stress corrosion cracking (IASCC). This report describes the results of environmental testing on irradiated Type 304 stainless steel in boiling water reactor (BWR) and pressurized water reactor (PWR) environments to assess their susceptibility to IASCC. The work was sponsored by the Cooperative IASCC Research (CIR I) Program, an international research effort ma...

2002-10-23T23:59:59.000Z

320

Computer Simulation of Intergranular Stress Corrosion Cracking via Hydrogen Embrittlement  

DOE Green Energy (OSTI)

Computer simulation has been applied to the investigation of intergranular stress corrosion cracking in Ni-based alloys based on a hydrogen embrittlement mechanism. The simulation employs computational modules that address (a) transport and reactions of aqueous species giving rise to hydrogen generation at the liquid-metal interface, (b) solid state transport of hydrogen via intergranular and transgranular diffusion pathways, and (c) fracture due to the embrittlement of metallic bonds by hydrogen. A key focus of the computational model development has been the role of materials microstructure (precipitate particles and grain boundaries) on hydrogen transport and embrittlement. Simulation results reveal that intergranular fracture is enhanced as grain boundaries are weakened and that microstructures with grains elongated perpendicular to the stress axis are more susceptible to cracking. The presence of intergranular precipitates may be expected to either enhance or impede cracking depending on the relative distribution of hydrogen between the grain boundaries and the precipitate-matrix interfaces. Calculations of hydrogen outgassing and in gassing demonstrate a strong effect of charging method on the fracture behavior.

Smith, R.W.

2000-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal cracking delayed" from the National Library of EnergyBeta (NLEBeta).
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321

SAES ST 909 PILOT SCALE METHANE CRACKING TESTS  

DOE Green Energy (OSTI)

Pilot scale (500 gram) SAES St 909 methane cracking tests were conducted to determine material performance for tritium process applications. Tests that ran up to 1400 hours have been performed at 700 C, 202.7 kPa (1520 torr) with a 30 sccm feed of methane, with various impurities, in a 20 vol% hydrogen, balance helium, stream. A 2.5 vol% methane feed was reduced below 30 ppm for 631 hours. A feed of 1.1 vol% methane plus 1.4 vol% carbon dioxide was reduced below 30 ppm for 513 hours. The amount of carbon dioxide gettered by St 909 can be equated to an equivalent amount of methane gettered to estimate a reduced bed life for methane cracking. The effect of 0.4 vol % and 2.1 vol% nitrogen in the feed reduced the time to exceed 30 ppm methane to 362 and 45 hours, respectively, but the nitrogen equivalence to reduced methane gettering capacity was found to be dependent on the nitrogen feed composition. Decreased hydrogen concentrations increased methane getter rates while a drop of 30 C in one bed zone increased methane emissions by over a factor of 30. The impact of gettered nitrogen can be somewhat minimized if the nitrogen feed to the bed has been stopped and sufficient time given to recover the methane cracking rate.

Klein, J; Henry Sessions, H

2007-07-02T23:59:59.000Z

322

Comparing Methods of Estimating Crack Volume in Shrink-Swell Soils  

E-Print Network (OSTI)

Predicting soil crack formation and closure in high shrink-swell soils is crucial for modeling water movement and solute transport. However, soil cracking, as it occurs in natural conditions, is not well understood. The objectives of this research are to 1) compare shrinking and swelling of two Vertisols with different mineralogy and 2) compare two methods for estimating soil crack volume. The first soil monitored, Ships Clay (Very-fine, mixed, thermic Chromic Hapluderts) has mixed mineralogy 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 were measured on both soils. Vertical subsidence was measured at three locations in each soil with rods fixed at four depths. Rod movement was converted to soil crack volume by assuming equi-dimensional shrinkage. A second method for estimating crack volume used direct measurements of cracks in the field. This second method was time consuming and the accuracy is unknown. A neutron moisture meter access tube was installed to measure soil moisture at each subsidence location. A total of 20 levling and moisture measurements were completed and 10 hand measurements of cracking were made. At the completion of the study, full characterization of each measurement location was performed, including COLE measurements. These COLE measurements were used as a third method of estimating crack volume in relation to soil moisture. Total crack volume will be compared at both sites to show the differences in the drying and cracking patterns. Crack volume as a function of moisture will be used to show how soil cracking and moisture relate. The two methods of estimating crack volume will be compared to see where possible cracking was measured with subsidence but not seen visually. The results showed the leveling-predicted crack volume was ten times that of the hand measured crack volume but followed the same temporal trend. The leveling-predicted crack volume is the most accurate of the three methods. COLE was also shown to be a good predictor a soils shrink-swell potential.

Rivera, Leonardo D.

2011-08-04T23:59:59.000Z

323

Adaptive control of time delay systems and applications to automotive control problems  

E-Print Network (OSTI)

This thesis is about the adaptive control of time delay systems with applications to automotive control problems. The stabilization of systems involving time delays is a difficult problem since the existence of a delay may ...

Yildiz, Yildiray

2009-01-01T23:59:59.000Z

324

The Effects of Simulated Inertia and Force Prediction on Delayed Telepresence  

Science Conference Proceedings (OSTI)

This paper presents two methods aimed at alleviating the negative effects of network delays on teleoperation. The problem of telepresence across delayed networks is well known. A delay in feedback information such as visual and haptic data can make the ...

Stella Clarke; Gerhard Schillhuber; Michael F. Zaeh; Heinz Ulbrich

2007-10-01T23:59:59.000Z

325

Fatigue Crack Propagation from Notched Specimens of 304 SS in elevated Temperature Aqueous Environment  

DOE Green Energy (OSTI)

Fatigue crack propagation (FCP) rates for 304 stainless steel (304SS) were determined in 24 degree C and 288 degree C air and 288 degree C water using double-edged notch (DEN) specimens of 304 stainless steel (304 SS). Test performed at matched loading conditions in air and water at 288 degree C with 20-6- cc h[sub]2/kg h[sub]2O provided a direct comparison of the relative crack growth rates in air and water over a wide range of crack growth rates. The DEN crack extension ranged from short cracks (0.03-0.25 mm) to long cracks up to 4.06 mm, which are consistent with conventional deep crack tests. Crack growth rates of 304 SS in water were about 12 times the air rate. This 12X environmental enhancement persisted to crack extensions up to 4.06 mm, far outside the range associated with short crack effects. The large environmental degradation for 304 SS crack growth is consistent with the strong reduction of fatigue life in high hydrogen water. Further, very similar environmental effects w ere reported in fatigue crack growth tests in hydrogen water chemistry (HWC). Most literature data in high hydrogen water show only a mild environmental effect for 304 SS, of order 2.5 times air or less, but the tests were predominantly performed at high cyclic stress intensity or equivalently, high air rates. The environmental effect in low oxygen environments at low stress intensity depends strongly on both the stress ratio, R, and the load rise time, T[sub]r, as recently reported for austenitic stainless steel in BWR water. Fractography was performed for both tests in air and water. At 288 degree C in water, the fracture surfaces were crisply faceted with a crystallographic appearance, and showed striations under high magnification. The cleavage-like facets on the fracture surfaces suggest that hydrogen embrittlement is the primary cause of accelerated cracking.

Wire, G. L.; Mills, W. J.

2002-08-01T23:59:59.000Z

326

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

327

Electron-capture delayed fission properties of 244Es  

Science Conference Proceedings (OSTI)

Electron-capture delayed fission was observed in {sup 244}Es produced via the {sup 237}Np({sup 12}C,5n){sup 244}Es reaction at 81 MeV (on target) with a production cross section of 0.31{+-}0.12 {micro}b. The mass-yield distribution of the fission fragments is highly asymmetric. The average preneutron-emission total kinetic energy of the fragments was measured to be 186{+-}19 MeV. Based on the ratio of the number of fission events to the measured number of {alpha} decays from the electron-capture daughter {sup 244}Cf (100% {alpha} branch), the probability of delayed fission was determined to be (1.2{+-}0.4) x 10{sup -4}. This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron-capture.

Shaughnessy, Dawn A.; Gregorich, Kenneth E.; Adams, Jeb L.; Lane, Michael R.; Laue, Carola A.; Lee, Diana M.; McGrath, Christopher A.; Ninov, Victor; Patin, Joshua B.; Strellis, Dan A.; Sylwester, Eric R.; Wilk, Philip A.; Hoffman, Darleane C.

2001-03-16T23:59:59.000Z

328

Real Time Models of the Asynchronous Circuits: The Delay Theory  

E-Print Network (OSTI)

The chapter from the book introduces the delay theory, whose purpose is the modeling of the asynchronous circuits from digital electrical engineering with ordinary and differential pseudo-boolean equations.

Serban E. Vlad

2004-12-17T23:59:59.000Z

329

Opportunities for Process Monitoring Techniques at Delayed Access Facilities  

Science Conference Proceedings (OSTI)

Except for specific cases where the International Atomic Energy Agency (IAEA) maintains a continuous presence at a facility (such as the Japanese Rokkasho Reprocessing Plant), there is always a period of time or delay between the moment a State is notified or aware of an upcoming inspection, and the time the inspector actually enters the material balance area or facility. Termed by the authors as delayed access, this period of time between inspection notice and inspector entrance to a facility poses a concern. Delayed access also has the potential to reduce the effectiveness of measures applied as part of the Safeguards Approach for a facility (such as short-notice inspections). This report investigates the feasibility of using process monitoring to address safeguards challenges posed by delayed access at a subset of facility types.

Curtis, Michael M.; Gitau, Ernest TN; Johnson, Shirley J.; Schanfein, Mark; Toomey, Christopher

2013-09-20T23:59:59.000Z

330

Evaluating passenger delays in the US domestic air transportation system  

E-Print Network (OSTI)

A fundamental component of any National Airspace System (NAS) performance evaluation is the cost impact of air traffic delays, and more generally capacity limitations, on the traveling passengers. In previous research it ...

Umang, Nitish

2010-01-01T23:59:59.000Z

331

Statistical modelling of delays in a rail freight transportation network  

Science Conference Proceedings (OSTI)

This study analyzes the transportation network of a major rail freight operator in order to obtain a model of delay propagation of trains connecting intermodal terminals. Operational management of a rail freight operator needs to take into account deviations ...

Jnos Barta; Andrea Emilio Rizzoli; Matteo Salani; Luca Maria Gambardella

2012-12-01T23:59:59.000Z

332

Delayed-fission properties of neutron-deficient americium nuclei  

Science Conference Proceedings (OSTI)

Characteristics of the delayed-fission decay mode in light americium nuclei have been investigated. Measurements on the unknown isotopes {sup 230}Am and {sup 236}Am were attempted, and upper limits on the delayed-fission branches of these nuclei were determined. Evidence of the existence of {sup 236}Am was observed in radiochemical separations. Total kinetic energy and mass-yield distributions of the electron-capture delayed-fission mode were measured for {sup 232}Am (t{sub 1/2} = 1.31 {plus minus} 0.04 min) and for {sup 234}Am (t{sub 1/2} = 2.32 {plus minus} 0.08 min), and delayed-fission probabilities of 6.9 {times} 10{sup {minus}4} and 6.6 {times} 10{sup {minus}5}, respectively, were determined. The total kinetic energy and the asymmetric mass-yield distributions are typical of fission of mid-range actinides. No discernible influence of the anomalous triple-peaked mass division characteristic of the thorium-radium region was detected. Measurements of the time correlation between the electron-capture x-rays and the subsequent fission conform that the observed fissions arise from the electron-capture delayed-fission mechanism. Delayed fission has provided a unique opportunity to extend the range of low-energy fission studies to previously inaccessible regions. 71 refs., 44 figs., 13 tabs.

Hall, H.L. (California Univ., Berkeley, CA (USA). Dept. of Chemistry)

1989-10-23T23:59:59.000Z

333

On Interference Networks with Feedback and Delayed CSI  

E-Print Network (OSTI)

The degrees of freedom (DoF) region of the two-user MIMO interference channel (IC) is completely characterized in the presence of noiseless channel output feedback from each receiver to its respective transmitter and with the assumption of delayed channel state information (CSI) at the transmitters. It is shown that having output feedback and delayed CSI at the transmitters can strictly enlarge the DoF region when compared to the case in which only delayed CSI is available at the transmitters. The proposed coding schemes that achieve the corresponding DoF region with feedback and delayed CSI utilize both resources, i.e., feedback and delayed CSI in a non-trivial manner. Furthermore, cases are identified in which output feedback and delayed CSI alone are sufficient to achieve the DoF region achievable with perfect, instantaneous CSI. Also, the DoF region of the scalar 2x2x2 two-hop interference network is characterized. It is shown that the total DoF for this network collapses from 2 (with perfect, instantaneo...

Tandon, Ravi; Poor, H Vincent; Shamai, Shlomo

2011-01-01T23:59:59.000Z

334

Structural Assessment of D-Regions Affected by Alkali-Silica Reaction/Delayed Ettringite Formation  

E-Print Network (OSTI)

A combined experimental and analytical program was conducted to investigate the effects of Alkali-Silica Reaction (ASR) and Delayed Ettringite Formation (DEF) on D-regions in reinforced concrete (RC) bridge bents. Four large-scale RC specimens, which represent cantilever and straddle bents in Texas bridges in each specimen, were constructed. The first specimen represented the unexposed control specimen, while the other three were conditioned in the field with supplemental watering to promote ASR/DEF and served as the exposed specimens. The control and two exposed specimens with various levels of ASR/DEF, after eight months and two years of field conditioning, were load tested to failure. The last specimen remains in field with additional exposure to promote ASR/DEF and will be load tested in future studies. The width and length of preload-induced cracks and developing cracks that initiated in the exposed specimens and grew over time, indicating concrete expansion due to ASR/DEF mechanisms, were measured. Petrographic analysis results of concrete cores extracted from the exposed specimens after their load testing confirmed the formation of ASR gel and minimum accumulation of ettringite. The structural testing results showed that the failure mechanism in all three tested specimens was due to a brittle shear failure in the beam-column joint. However, slightly greater stiffness, strength, and ductility were observed in the exposed specimens as a result of the activation of the reinforcing steel in the specimens due to the expansion of the concrete primarily from ASR, which effectively prestressed and confined the core concrete. Sectional analysis and Strut-and-Tie Modeling (STM) of the experimental specimens were applied. Three-dimensional nonlinear Finite Element Analyses (FEA) were also conducted to numerically simulate the overall structural performance, internal response, and out-of-plane behavior of the experimental specimens. The effects of varying constitutive relations of the concrete in tension on models of the specimens were compared with the measured experimental response. A method to mimic ASR/DEF effects on exposed specimens was proposed and incorporated into the FEA approach. As a result, forces that prestress and confine the core concrete were effectively applied through the reinforcing steel prior to subsequent structural loading. The three-dimensional FEA approach was able to simulate the out-of-plane behavior of the beam-column joint and the proposed method yielded comparable results with the measured overall and internal behavior of specimens.

Liu, Shih-Hsiang 1979-

2012-12-01T23:59:59.000Z

335

Materials Reliability Program: Evaluation of Potential for Low Temperature Crack Propagation in Reactor Pressure Vessel Outlet Nozzl e Dissimilar Metal Butt Welds by Stress and Fracture Mechanics Analyses (MRP-247)  

Science Conference Proceedings (OSTI)

Low Temperature Crack Propagation is a form of hydrogen embrittlement that can cause, under specific environmental conditions in laboratory tests, severe degradation of the fracture resistance of nickel-base alloys X-750 and 690, and weld metals 82/182 and 52/152. While no operating plant has exhibited evidence of LTCP, the hydrogen levels and temperature conditions necessary for LTCP to occur are present during some PWR shutdowns. This report evaluates the potential for the thermal stresses generated du...

2008-12-22T23:59:59.000Z

336

On the micromechanisms of fatigue-crack propagation in aluminum- lithium alloys: Sheet vs. plate material  

Science Conference Proceedings (OSTI)

Micromechanisms influencing the propagation of long (>10 mm) fatigue cracks in aluminum-lithium alloys are examined by specifically comparing crack-growth kinetics in a peak-aged Al-Li-Cu-Zr alloy 2090, processed as 1.6-mm thin (T83) sheet and 12.7-mm thick (T81) plate. It is found that in general crack-growth rates are significantly faster in the sheet material at equivalent stress-intensity levels, due to differences in the role of crack-tip shielding, resulting from crack deflection and consequent crack closure from wedging of fracture-surface asperities. Microstructurally, such differences are related to variations in the degree of recrystallization, grain structure and deformation texture in the two wrought-product forms. 14 refs., 4 figs.

Rao Venkateswara, K.T.; Ritchie, R.O. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Bucci, R.J. (Aluminum Co. of America, Alcoa Center, PA (United States). Alcoa Labs.)

1989-12-01T23:59:59.000Z

337

Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results  

SciTech Connect

The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243{degrees}C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling.

Li, Y.Y.

1997-01-01T23:59:59.000Z

338

LARGE NUMBERS OF UNDETECTED CRACKS IN THE WORLDS PWRS  

E-Print Network (OSTI)

Documents of the Davis-Besse incident reveal a strong possibility that there are large numbers of undetected cracks in the worlds pressurized water reactors, particularly in the US. This suspicion has been confirmed by the discovery of an additional crack at Davis-Besse itself. (568.5402) NIRS/WISE Amsterdam The cracks are nothing new: they were first discovered in Bugey-3,

unknown authors

2002-01-01T23:59:59.000Z

339

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

Science Conference Proceedings (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

340

PowerPoint Presentation  

National Nuclear Security Administration (NNSA)

y x Main crack surface Dislocation loops Crack initiation point Crack branching (BLJ + thermal motion) Crack embryo 3D view of surface particles Developed crack Crack development...

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

Elevated-Temperature Creep-Fatigue Crack-Growth Behavior of ...  

Science Conference Proceedings (OSTI)

the nickel-base HAYNES R-41, HAYNES 230 and HASTELLOY. X superalloys at temperatures ... The crack-growth tests for R-41 alloy were conducted using a.

342

An introduction to crack spreads - Today in Energy - U.S ...  

U.S. Energy Information Administration (EIA)

Crack spreads are differences between wholesale petroleum product prices and crude oil prices. These spreads are often used to estimate refining margi ...

343

A model of crack based on dislocations in smectic A liquid crystals  

E-Print Network (OSTI)

A plastic crack model for smectic A liquid crystals under longitudinal shear is suggested. The solution of screw dislocation in smectic A is the key in which the correct result is just obtained by overcoming a longstanding puzzle [19]. We further use the dislocation pile-up principle and the singular integral equation method, construct the solution of the crack in the phase. From the solution we can determine the size of the plastic zone at the crack tip and the crack tip opening (tearing) displacement, which are parameters being relevant to the local stability/instability of materials. The results may be useful in developing soft-matter mechanics.

Tian You Fan

2012-10-30T23:59:59.000Z

344

Cyclic Deformation and Fatigue Cracking Mechanisms of F.C.C. ...  

Science Conference Proceedings (OSTI)

Fatigue Crack Tip Mechanics Following a Tensile Overload Fatigue Weak-Link Density and Strength Distribution in High Strength Al Wrought and Cast Alloys.

345

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

Science Conference Proceedings (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

346

Manufacturing of Crack-Free Hastelloy-X Components by Selective ...  

Science Conference Proceedings (OSTI)

Lubricants in Deposition and Machining of Wire and Arc Additive Manufactured Structures Manufacturing of Crack-Free Hastelloy-X Components by Selective...

347

Stress Corrosion Cracking Behavior of Cast Stainless Steels  

SciTech Connect

Casting of austenitic stainless steels offers the possibility of directly producing large and/or relatively complex structures, such as the first wall shield modules or the diverter cassette for the ITER fusion reactor. Casting offers major cost savings when compared to fabrication via welding of quarter modules machined from large forgings. However, the strength properties of such cast components are typically considered inferior to those of conventionally forged and annealed components. To improve and validate cast stainless steel as a substitute for wrought stainless steel, a development and testing program was initiated, utilizing nitrogen and manganese additions to promote improved performance. This paper focuses on the response of the first set of developmental alloys to neutron-irradiation and susceptibility to stress corrosion cracking. These cast materials may also have applications for different components in light water reactors. Results showed that all steels exhibited irradiation-induced hardening and a corresponding drop in ductility, as expected, although there is still considerable ductility in the irradiated samples. The cast steels all exhibited reduced hardening in comparison to a wrought reference steels, which may be related to a larger grain size. Higher nitrogen contents did not negatively influence irradiation performance. Regarding stress corrosion cracking susceptibility, the large difference in grain size limits the comparison between wrought and cast materials, and inclusions in a reference and archive cast alloy tests complicate analysis of these samples. Results suggest that the irradiated archive heat was more susceptible to cracking than the modified alloys, which may be related to the more complex microstructure. Further, the results suggest that the modified cast steel is at least as SCC resistant as wrought 316LN. The beneficial effect of nitrogen on the mechanical properties of the alloys remains after irradiation and is not detrimental to SCC resistance.

Teysseyre, Sebastien [University of Michigan; Busby, Jeremy T [ORNL; Was, Gary [University of Michigan

2009-01-01T23:59:59.000Z

348

Temperature and environmentally assisted cracking in low alloy steel  

Science Conference Proceedings (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 15 ppb.

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

1995-04-01T23:59:59.000Z

349

Physics-Based Stress Corrosion Cracking Component Reliability  

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

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

350

HEATS: Thermal Energy Storage  

SciTech Connect

HEATS Project: The 15 projects that make up ARPA-Es 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

351

TSPA Final Report - February 11, 1999  

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

Stress corrosion cracking; * Chemically facilitated stress corrosion cracking due to fuel pellet and cladding interactions (Sidky, 1998); * Delayed hydride cracking; *...

352

Routing Algorithms for Delay-insensitive and Delay-sensitive Applications in Underwater Sensor Networks  

E-Print Network (OSTI)

Underwater sensor networks consist of sensors and vehicles deployed to perform collaborative monitoring tasks over a given region. Underwater sensor networks will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, tactical surveillance, and mine reconnaissance. Underwater acoustic networking is the enabling technology for these applications. In this paper, an architecture for three-dimensional underwater sensor networks is considered, and a model characterizing the acoustic channel utilization efficiency is introduced, which allows investigating some fundamental characteristics of the underwater environment. In particular, the model allows setting the optimal packet size for underwater communications given monitored volume, density of the sensor network, and application requirements. Moreover, the problem of data gathering is investigated at the network layer by considering the cross-layer interactions between the routing functions and the characteristics of the underwater acoustic channel. Two distributed routing algorithms are introduced for delay-insensitive and delaysensitive applications. The proposed solutions allow each node to select its next hop, with the objective of minimizing the energy consumption taking the varying condition of the underwater channel and the different application requirements into account. The proposed routing solutions are shown to achieve the performance targets by means of simulation.

Dario Pompili; Tommaso Melodia; Ian F. Akyildiz

2006-01-01T23:59:59.000Z

353

Continuous-time nonlinear model predictive control of time-delayed Wiener-type systems  

Science Conference Proceedings (OSTI)

This paper deals with a novel method of continuous-time model predictive control for nonlinear time-delayed systems. The problems regarding time delays are solved by incorporating delayed and undelayed model outputs in the control-law derivation. Nonlinear-mapping ... Keywords: Wiener-type model, continuous system, nonlinear predictive control, time-delayed system

Simon Oblak; Igor krjanc

2006-02-01T23:59:59.000Z

354

Pulsed Photofission Delayed Gamma Ray Detection for Nuclear Material Identification  

SciTech Connect

Innovative systems with increased sensitivity and resolution are in great demand to detect diversion and to prevent misuse in support of nuclear materials management for the U.S. fuel cycle. Nuclear fission is the most important multiplicative process involved in non-destructive active interrogation. This process produces the most easily recognizable signature for nuclear materials. High-energy gamma rays can also excite a nucleus and cause fission through a process known as photofission. After photofission reactions, delayed signals are easily distinguishable from the interrogating radiation. Linac-based, advanced inspection techniques utilizing the fission signals after photofission have been extensively studied for homeland security applications. Previous research also showed that a unique delayed gamma ray energy spectrum exists for each fissionable isotope. Isotopic composition measurement methods based on delayed gamma ray spectroscopy will be the primary focus of this work.

John Kavouras; Xianfei Wen; Daren R. Norman; Dante R. Nakazawa; Haori Yang

2012-11-01T23:59:59.000Z

355

Time delays across saddles as a test of modified gravity  

E-Print Network (OSTI)

Modified gravity theories can produce strong signals in the vicinity of the saddles of the total gravitational potential. In a sub-class of these models this translates into diverging time-delays for echoes crossing the saddles. Such models arise from the possibility that gravity might be infrared divergent or confined, and if suitably designed they are very difficult to rule out. We show that Lunar Laser Ranging during an eclipse could probe the time-delay effect within meters of the saddle, thereby proving or excluding these models. Very Large Baseline Interferometry, instead, could target delays across the Jupiter-Sun saddle. Such experiments would shed light on the infrared behaviour of gravity and examine the puzzling possibility that there might be well-hidden regions of strong gravity and even singularities inside the solar system.

Joao Magueijo; Ali Mozaffari

2012-12-15T23:59:59.000Z

356

Residual stresses and stress corrosion cracking in pipe fittings  

Science Conference Proceedings (OSTI)

Residual stresses can play a key role in the SCC performance of susceptible materials in PWR primary water applications. Residual stresses are stresses stored within the metal that develop during deformation and persist in the absence of external forces or temperature gradients. Sources of residual stresses in pipe fittings include fabrication processes, installation and welding. There are a number of methods to characterize the magnitude and orientation of residual stresses. These include numerical analysis, chemical cracking tests, and measurement (e.g., X-ray diffraction, neutron diffraction, strain gage/hole drilling, strain gage/trepanning, strain gage/section and layer removal, and acoustics). This paper presents 400 C steam SCC test results demonstrating that residual stresses in as-fabricated Alloy 600 pipe fittings are sufficient to induce SCC. Residual stresses present in as-fabricated pipe fittings are characterized by chemical cracking tests (stainless steel fittings tested in boiling magnesium chloride solution) and by the sectioning and layer removal (SLR) technique.

Parrington, R.J.; Scott, J.J.; Torres, F.

1994-06-01T23:59:59.000Z

357

Delayed neutron measurements from fast fission of actinide waste isotopes  

E-Print Network (OSTI)

A study was performed to determine the delayed neutron emission properties from fast fission of several actinide waste isotopes. The specific isotopes evaluated were U-235, Np-237, and Am-243. A calculational technique based on the microscopic method was used to predict initial guesses for the delayed neutron parameters (group decay constants and yields). Based on these calculations, an alternate "seven-group" structure, in contrast to the traditional "six-group" structure used previously, was suggested which would yield a superior fit to the measured data. A series of measurements were performed to test the hypothesis suggested by this alternate group structure. Using a set of highly purified actinide samples (provided by Oak Ridge National Laboratory), the delayed neutron emission decay constants and yields for six groups of the "seven-group" structure were measured for U-235, Np-237, and Am-243. These experiments were performed using the Texas A&M University Nuclear Science Center Reactor, a quick pneumatic transfer system, an integrated computer control and counting system, and a specially designed in-core irradiation device. The values for the total delayed neutron yield (per 100 fissions) from fast-neutron induced fission of U-235, Np237, and Am-243 were determined to be 1.67 ?0.08, 1.14 ?0.07, 0.86 ?0.05, respectively. The newly measured values were compared with other values recommended by Keepin et al., Waldo et al., Saleh et al., and Brady and England. Good agreement was found in all cases. The "seven-group" structure was shown to yield a superior fit to the measured data, as well as, provide a more direct correlation between delayed neutron groups and their associated delayed neutron precursors.

Charlton, William S.

1997-01-01T23:59:59.000Z

358

V.: Security considerations in space and delay tolerant networks  

E-Print Network (OSTI)

This paper reviews the Internet-inspired security work on delay tolerant networking, in particular, as it might apply to space missions, and identifies some challenges arising, for both the Internet security community and for space missions. These challenges include the development of key management schemes suited for space missions as well as a characterization of the actual security requirements applying. A specific goal of this paper is therefore to elicit feedback from space mission IT specialists in order to guide the development of security mechanisms for delay tolerant networking. 1.

Stephen Farrell; Vinny Cahill

2006-01-01T23:59:59.000Z

359

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

360

Thermal and Electrical Transport in Oxide Heterostructures  

E-Print Network (OSTI)

of thermal conductivity . . . . . . . . . . . . . . . .4.4 Thermal transport in2.3.2 Thermal transport . . . . . . . . . . . . . . . .

Ravichandran, Jayakanth

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.


361

Thermal Spray Coatings  

Science Conference Proceedings (OSTI)

Table 35   Thermal spray coatings used for hardfacing applications...piston ring (internal combustion);

362

Plasma-Thermal Synthesis  

INLs Plasma-Thermal Synthesis process improves the conversion process for natural gas into liquid hydrocarbon fuels.

363

Ocean Thermal Energy Conversion  

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

A process called ocean thermal energy conversion (OTEC) uses the heat energy stored in the Earth's oceans to generate electricity.

364

Nanocomposite Thermal Spray Coatings.  

Science Conference Proceedings (OSTI)

Long-Term Surface Restoration Effect Introduced by Advanced Lubricant Additive Nanocomposite Thermal Spray Coatings. New Hardfacing Overlay Claddings...

365

Thermal Management of Solar Cells  

E-Print Network (OSTI)

phonon transmission and interface thermal conductance acrossF. Miao, et al. , "Superior Thermal Conductivity of Single-Advanced Materials for Thermal Management of Electronic

Saadah, Mohammed Ahmed

2013-01-01T23:59:59.000Z

366

Influence of Radiolysis and Hydrogen Embrittlement on the In-Service Cracking of PWR Internal Structures  

Science Conference Proceedings (OSTI)

Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steel components exposed to a high neutron flux in light water reactors is becoming an increasing concern for nuclear power plant owners. This study investigates the interaction between hydrogen in the metal and the water environment that may exacerbate the cracking process in PWRs.

1999-11-10T23:59:59.000Z

367

On saturation-strip model of a permeable crack in a piezoelectric ceramic  

E-Print Network (OSTI)

, h0, in the analysis of electrical and mechanical fields in the vicinity of a permeable crack tip under both mechanical as well electrical loads. Both local and global energy release rates. This permeable saturation crack model reveals that there exists a possible leaky mode for electrical field, which

Li, Shaofan

368

Apparatus and method for prevention of cracking in welded brittle alloys  

DOE Patents (OSTI)

An apparatus and method for reducing cracking in a heated material as the material cools. The apparatus includes a variable frequency electric signal generator that is coupled to a transducer. The transducer produces a variable frequency acoustic signal in response to the variable frequency electric signal, which is applied to the heated material to reduce cracking as the material cools.

Kronberg, James W. (Aiken, SC); Younkins, Robert M. (New Ellenton, SC)

2000-01-01T23:59:59.000Z

369

Delamination of a sensitized commercial AlMg alloy during fatigue crack growth  

E-Print Network (OSTI)

as sensitization to corrosion and stress corrosion cracking [1,3,4,8], with exposure to tem- peratures between 50,9­12]. The presence and growth of b-phase have been shown to severely degrade the corrosion resistance and stressDelamination of a sensitized commercial Al­Mg alloy during fatigue crack growth J.K. Brosi and J

Rollins, Andrew M.

370

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

E-Print Network (OSTI)

the free energy, and thus the energy barrier, via numerous competing mech- anisms like stress corrosion speed of crack growth with increasing G; a weak stress- sensitive regime II follows where transportAverage crack front velocity during subcritical fracture propagation in a heterogeneous medium

Ampuero, Jean Paul

371

Prediction of Environmental Crack Growth in Nuclear Power Plant Components: Volumes 1-3  

Science Conference Proceedings (OSTI)

In-service assessment of crack growth rates plays a crucial role in decisions involving component integrity and life. The research presented in this three-volume report examines many important aspects of the crack tip damage processes in aqueous environments, providing an improved scientific basis for life prediction technology development.

1993-11-04T23:59:59.000Z

372

Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2  

Science Conference Proceedings (OSTI)

Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 degrees C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared ...

Smith Stephen W.; Piascik Robert S.

2001-03-01T23:59:59.000Z

373

Behavior of Stress Corrosion Cracking for Type 316L Stainless Steel ...  

Science Conference Proceedings (OSTI)

Crack Growth Rates of Irradiated Commercial Stainless Steels in BWR and PWR ... Detailed Root Cause Analysis of SG Tube ODSCC Indications within the Tube Sheets of NPP Biblis Unit A .... Radiation Damage in Fe-C-Met Model Alloys ... Stress Corrosion Cracking Behavior near the Fusion Boundary of Dissimilar Weld

374

Brief paper: Delay-dependent robust H? filtering for uncertain discrete-time singular systems with interval time-varying delay  

Science Conference Proceedings (OSTI)

This paper focuses on the delay-dependent robust H"~ filtering for uncertain discrete-time singular systems with interval time-varying delay. The uncertainty considered is a convex compact set of polytopic type. The purpose is the design of a linear ... Keywords: Discrete-time singular systems, Interval time-varying delay, Linear matrix inequality, Robust H? filter

Jong Hae Kim

2010-03-01T23:59:59.000Z

375

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

376

Micromechanisms of monotonic and cyclic subcritical crack growth in advanced high-melting-point low-ductility intermetallics. Annual report No. 1, 15 Apr 90-14 Apr 91  

Science Conference Proceedings (OSTI)

The next generation of high-performance jet engines will require markedly stiffer materials, operating at higher stress levels and capable of withstanding temperatures of up to 1650 C. Prime candidates for such applications include ordered intermetallics, ceramics and composites based on metal, intermetallic and ceramic or carbon matrices, all of which are currently of limited use due to their low ductility and fracture properties. Moreover, there is a lack of fundamental understanding on the micromechanisms influencing crack growth in these materials, particularly intermetallics. Accordingly, the present study is aimed at exploring the potential of intermetallic alloys and their composites as advanced structural materials by identifying the critical factors influencing the crack-propagation resistance under monotonic and cyclic loads. Attention is focused on the Nb{sub 3}Al and TiAl intermetallic systems. In both cases, the principal mechanism of toughening is to impede crack advance from crack bridging by ductile second phase particles. Reactive sintering and vacuum hot pressing techniques are successful is processing Nb{sub 3}Al intermetallics and duplex Nb/Nb{sub 3}Al microstructure with a stringy niobium phase can be achieved through thermal treatments. Characterization of mechanical properties will commence in the second year.

Rao, K.T.; Murugesh, L.; DeJonghe, L.C.

1991-05-01T23:59:59.000Z

377

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

378

Vickers microindentation toughness of a sintered SiC in the median-crack regime  

SciTech Connect

The Vickers microindentation method for the determination of the fracture toughness of ceramics was investigated in the median crack regime for a sintered alpha SiC. The results are compared with fracture toughness measurements by conventional fracture mechanics technique and also with the reported indentation toughness for the low-load Palmqvist crack regime. Indentation toughnesses in the median crack regime vary widely depending on the choice of the specific equation which is applied. The indentation toughnesses are also load (crack length) dependent. A decreasing R-curve trend results, in contradiction to the flat R-curve that has been observed with conventional fracture mechanics techniques. It is concluded that the Vickers microindentation method is not a reliable technique for the determination of the fracture toughness of ceramics in the median crack regime.

Ghosh, Asish; Kobayashi, A.S. (Washington Univ., Seattle, WA (United States). Coll. of Engineering); Li, Zhuang (Argonne National Lab., IL (United States)); Henager, C.H. Jr. (Pacific Northwest Lab., Richland, WA (United States)); Bradt, R.C. (Nevada Univ., Reno, NV (United States). Mackay School of Mines)

1991-01-01T23:59:59.000Z

379

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

Science Conference Proceedings (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

380

BWRVIP-99-A: BWR Vessel and Internals Project, Crack Growth Rates in Irradiated Stainless Steels in BWR Internal Components  

Science Conference Proceedings (OSTI)

The BWR Vessel and Internals Project (BWRVIP) has developed methodologies to evaluate crack growth in internal components of stainless steel and nickel-base alloys in the BWR vessel. One BWRVIP reportBWRVIP-14developed an approach to evaluate crack growth by intergranular stress corrosion cracking in austenitic stainless steel core shrouds exposed to a limited amount of neutron irradiation. Subsequently another reportBWRVIP-99was prepared to provide a crack growth methodology applicable to irradiated...

2008-11-24T23:59:59.000Z

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

Tracking Down the ENSO Delayed Oscillator with an Adjoint OGCM  

Science Conference Proceedings (OSTI)

According to the delayed-oscillator picture of ENSO, a positive SST anomaly in the eastern tropical Pacific will cause westerly wind anomalies closer to the date line to first give a positive feedback, and later, via planetary wave reflection at ...

Geert Jan van Oldenborgh; Gerrit Burgers; Stephan Venzke; Christian Eckert; Ralf Giering

1999-07-01T23:59:59.000Z

382

GPS Meteorology: Mapping Zenith Wet Delays onto Precipitable Water  

Science Conference Proceedings (OSTI)

Emerging networks of Global Positioning System (GPS) receivers can be used in the remote sensing of atmospheric water vapor. The time-varying zenith wet delay observed at each GPS receiver in a network can be transformed into an estimate of the ...

Michael Bevis; Steven Businger; Steven Chiswell; Thomas A. Herring; Richard A. Anthes; Christian Rocken; Randolph H. Ware

1994-03-01T23:59:59.000Z

383

Delay of intrusion detection in wireless sensor networks  

Science Conference Proceedings (OSTI)

In this paper we consider sensor networks for intrusion detection, such that node deployment, node failures and node behavior result in coverage gaps and a fraction of disconnected nodes in an otherwise dense and well-connected network. We focus on the ... Keywords: delay, intrusion detection, percolation, sensor networks

Olivier Dousse; Christina Tavoularis; Patrick Thiran

2006-05-01T23:59:59.000Z

384

Why Can Wind Delay the Shedding of Loop Current Eddies?  

Science Conference Proceedings (OSTI)

It is first shown that wind in the Gulf of Mexico can delay the shedding of Loop Current eddies. A time-dependent, three-dimensional numerical experiment forced by a spatially and temporally constant westward wind stress within the Gulf is ...

Y.-L. Chang; L.-Y. Oey

2010-11-01T23:59:59.000Z

385

Transportation Center Seminar "Flight Delays, Capacity Investment and Welfare under  

E-Print Network (OSTI)

Transportation Center Seminar "Flight Delays, Capacity Investment and Welfare under Air Transport University of Illinois at Chicago (UIC) Thurs. April 4, 2013 4:00 ­ 5:00 pm Location: Transportation Center in the air transportation system. The Federal Aviation Administration (FAA) and local airport agencies have

Bustamante, Fabián E.

386

Energy efficient searching in delay-tolerant wireless sensor networks  

Science Conference Proceedings (OSTI)

In this paper, we consider the problem of information discovery in densely deployed and delay-tolerant Wireless Sensor Network (WSN), where the initiator of search is unaware of the location of target information. We propose Increasing Ray Search (IRS), ... Keywords: energy efficiency, query, search, wireless sensor networks

Kiran Rachuri; A. Antony Franklin; C. Siva Ram Murthy

2008-05-01T23:59:59.000Z

387

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

388

Building Energy Software Tools Directory: Thermal Comfort  

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

Thermal Comfort Thermal Comfort logo. Provides a user-friendly interface for calculating thermal comfort parameters and making thermal comfort predictions using several thermal...

389

Extent of surface regions near corner points of notched cracked bodies subjected to mode-I loading  

Science Conference Proceedings (OSTI)

In the present paper, the extent of surface regions in cracked bodies subjected to mode-I loading was examined, which is important for a proper definition of finite element meshes. Different specimen geometries with and without lateral notches, representative ... Keywords: Crack shape evolution, Extent of surface region, Fatigue crack growth, Finite element method, Stress triaxiality

R. Branco; F. V. Antunes; L. C. H. Ricardo; J. D. Costa

2012-03-01T23:59:59.000Z

390

Applying neural networks, genetic algorithms and fuzzy logic for the identification of cracks in shafts by using coupled response measurements  

Science Conference Proceedings (OSTI)

This paper considers the dynamic behavior of a shaft with two transverse cracks characterized by three measures: position, depth and relative angle. Both cracks are considered to lie along arbitrary angular positions with respect to the longitudinal ... Keywords: Coupling, Crack identification, Genetic algorithms, Neural networks, Shaft

K. M. Saridakis; A. C. Chasalevris; C. A. Papadopoulos; A. J. Dentsoras

2008-06-01T23:59:59.000Z

391

EMAT based inspection of natural gas pipelines for SSC cracks  

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

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

392

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

2012-09-16T23:59:59.000Z

393

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

Tsoy, L A; Komarov, A G; Tsoy, A N

2012-01-01T23:59:59.000Z

394

CRACK GROWTH ANALYSIS OF SOLID OXIDE FUEL CELL ELECTROLYTES  

DOE Green Energy (OSTI)

Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis, and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells. Rings cut from the tubes were characterized for microstructure, phase stability, mechanical strength (Weibull modulus) and fracture mechanisms. The strength at operating condition of SOFCs (1000 C) decreased to 95 MPa as compared to room temperature strength of 230 MPa. However, the Weibull modulus remains relatively unchanged. Slow crack growth (SCG) parameter, n = 17 evaluated at room temperature in air was representative of well studied brittle materials. Based on the results, further work was planned to evaluate the strength degradation, modulus and failure in more representative environment of the SOFCs.

S. Bandopadhyay; N. Nagabhushana

2003-10-01T23:59:59.000Z

395

RESEARCH DESIGN TO EVALUATE Zr-2.5Nb AND Zr-2.5Nb-0.5Cu ALLOYS FOR DELAYED FAILURE HYDROGEN EMBRITTLEMENT. Final Report, October 15, 1962-October 14, 1963  

DOE Green Energy (OSTI)

In a previous program, the existence of moderate delayed failure of Zr-- 2.5Nb with 500 ppm absorbed hydrogen was established. The present investigation is to determine static fatigue susceptibility of this alloy under various conditions of hydrogen content, heat treatment, and metallurgical condition and includes study of the ternary modification Zr-- 2.5Nb -0.5Cu. Notched and unnotched specimens were evaluated under static loading conditions, primarily at room temperature and with 500 ppm absorbed hydrogen, and the time to failure and fracture characteristics were determined. The metallurgical history which resulted in significant delayed failure susceptibility consisted of water quenching followed by an aging treatment which gave a matrix of entirely transformed beta. If an alphatransformed beta microstructure was produced, static fatigue was markedly attenuated. The results can be accounted for by consideration of whether a crack nucleus cand propagate through the matrix or be stopped by local plastic yielding. The propagation of cracks is therefore determined by matrix strength and ductility, which appear to be strong factors in determining hydrogen embrittlement. (auth)

Weinstein, D.; Holtz, F.C.

1963-11-14T23:59:59.000Z

396

Effect of PCC Joint Skew on Reflective Cracking in HMA Overlays  

E-Print Network (OSTI)

Reflective cracking is a relatively premature distress that occurs in HMA materials overlaying cracked and jointed underlying pavements. The high concentration of stresses and strains in the vicinity of the discontinuity of the old pavement causes the cracks to reflect into the newly placed HMA overlay. While it is a common practice to use skewed transverse joints in rigid pavements to improve the latter's performance, the impact of such a practice on the cracking of a potential HMA overlay has not been examined so far. In this context, this study investigates the effect of using skewed transverse joints in rigid pavements on reflective cracking development in the HMA overlay. Advanced three-dimensional Finite Element models including viscoelastic material properties for the HMA overlay, 3D beam modeling of dowel bars, non-uniform tire-pavement contact stresses, friction interfaces, and infinite boundary elements were constructed for both normal and skewed transverse joints using ABAQUS v-6.11. The potential for reflective cracking was monitored through the fracture mechanics J-integral parameter. Results obtained show, among other things, that the practice of skewing transverse joints increases the potential for reflective cracking development in the asphalt concrete overlay.

Ziad G. Ghauch

2011-10-14T23:59:59.000Z

397

Crack Formation in the Presence of an Electric Field in Droplets of Laponite Gel  

E-Print Network (OSTI)

When a colloidal gel dries through evaporation, cracks are usually formed, which often reveal underlying processes at work during desiccation. Desiccating colloid droplets of few hundred $\\mu l$ size show interesting effects of pattern formation and cracking which makes this an active subject of current research. Since aqueous gels of clay are known to be strongly affected by an electric field, one may expect crack patterns to exhibit a field effect. In the present study we allow droplets of laponite gel to dry under a radial electric field. This gives rise to highly reproducible patterns of cracks, which depend on the strength, direction and time of exposure to the electric field. For a continuously applied DC voltage, cracks always appear on dissipation of a certain constant amount of energy. If the field is switched off before cracks appear, the observed results are shown to obey a number of empirical scaling relations, which enable us to predict the time of appearance and the number of cracks under specified conditions.

Tajkera Khatun; Tapati Dutta; Sujata Tarafdar

2013-08-14T23:59:59.000Z

398

Crack growth rates of nickel alloy welds in a PWR environment.  

Science Conference Proceedings (OSTI)

In light water reactors (LWRs), vessel internal components made of nickel-base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals. A program is being conducted at Argonne National Laboratory to evaluate the resistance of Ni alloys and their welds to environmentally assisted cracking in simulated LWR coolant environments. This report presents crack growth rate (CGR) results for Alloy 182 shielded-metal-arc weld metal in a simulated pressurized water reactor (PWR) environment at 320 C. Crack growth tests were conducted on 1-T compact tension specimens with different weld orientations from both double-J and deep-groove welds. The results indicate little or no environmental enhancement of fatigue CGRs of Alloy 182 weld metal in the PWR environment. The CGRs of Alloy 182 in the PWR environment are a factor of {approx}5 higher than those of Alloy 600 in air under the same loading conditions. The stress corrosion cracking for the Alloy 182 weld is close to the average behavior of Alloy 600 in the PWR environment. The weld orientation was found to have a profound effect on the magnitude of crack growth: cracking was found to propagate faster along the dendrites than across them. The existing CGR data for Ni-alloy weld metals have been compiled and evaluated to establish the effects of key material, loading, and environmental parameters on CGRs in PWR environments. The results from the present study are compared with the existing CGR data for Ni-alloy welds to determine the relative susceptibility of the specific Ni-alloy weld to environmentally enhanced cracking.

Alexandreanu, B.; Chopra, O. K.; Shack, W. J.; Energy Technology

2006-05-31T23:59:59.000Z

399

Catalytic thermal barrier coatings  

Science Conference Proceedings (OSTI)

A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

Kulkarni, Anand A. (Orlando, FL); Campbell, Christian X. (Orlando, FL); Subramanian, Ramesh (Oviedo, FL)

2009-06-02T23:59:59.000Z

400

Thermally Conductive Graphite Foam  

oriented graphite planes, similar to high performance carbon fibers, which have been estimated to exhibit a thermal conductivity greater than 1700 ...

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

Thermal Barrier Coatings  

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

Thermal Barrier Coatings Opportunity The Department of Energy's National Energy Technology Laboratory (NETL) is seeking licensing partners interested in implementing United States...

402

Amplitude death phenomena in delay--coupled Hamiltonian systems  

E-Print Network (OSTI)

Hamiltonian systems, when coupled {\\it via} time--delayed interactions, do not remain conservative. In the uncoupled system, the motion can typically be periodic, quasiperiodic or chaotic. This changes drastically when delay coupling is introduced since now attractors can be created in the phase space. In particular for sufficiently strong coupling there can be amplitude death (AD), namely the stabilization of point attractors and the cessation of oscillatory motion. The approach to the state of AD or oscillation death is also accompanied by a phase--flip in the transient dynamics. A discussion and analysis of the phenomenology is made through an application to the specific cases of harmonic as well as anharmoniccoupled oscillators, in particular the H\\'enon-Heiles system.

Garima Saxena; Awadhesh Prasad; Ram Ramaswamy

2013-05-07T23:59:59.000Z

403

Chloromethyl chlorosulfate as a voltage delay inhibitor in lithium cells  

DOE Patents (OSTI)

Chloromethyl chlorosulfate (CMCS) is used as a passive film growth inhibitor in electrochemical cells to minimize voltage delay and low-voltage discharge. Film growth on lithium anodes is significantly diminished when CMCS is added to SOCl{sub 2} and SO{sub 2}Cl{sub 2} electrolytes of lithium batteries. The CMCS also has the effect of extending the shelf-life of Li/SOCl{sub 2} and Li/SO{sub 2}Cl{sub 2} batteries.

Delnick, F.M.

1991-04-05T23:59:59.000Z

404

Chloromethyl chlorosulfate as a voltage delay inhibitor in lithium cells  

DOE Patents (OSTI)

Chloromethyl chlorosulfate (CMCS) is used as a passive film growth inhibitor in electrochemical cells to minimize voltage delay and low-voltage discharge. Film growth on lithium anodes is significantly diminished when CMCS is added to SOCl.sub.2 and SO.sub.2 Cl.sub.2 electrolytes of lithium batteries. The CMCS also has the effect of extending the shelf-life of Li/SOCl.sub.2 and Li/SO.sub.2 Cl.sub.2 batteries.

Delnick, Frank M. (Albuquerque, NM)

1993-01-01T23:59:59.000Z

405

Chloromethyl chlorosulfate as a voltage delay inhibitor in lithium cells  

DOE Patents (OSTI)

Chloromethyl chlorosulfate (CMCS) is used as a passive film growth inhibitor in electrochemical cells to minimize voltage delay and low-voltage discharge. Film growth on lithium anodes is significantly diminished when CMCS is added to SOCl[sub 2] and SO[sub 2]Cl[sub 2] electrolytes of lithium batteries. The CMCS also has the effect of extending the shelf-life of Li/SOCl[sub 2] and Li/SO[sub 2]Cl[sub 2] batteries.

Delnick, F.M.

1993-04-13T23:59:59.000Z

406

The density of surface states as the total time delay  

E-Print Network (OSTI)

For a scattering problem of tight-binding Bloch electrons by a weak random surface potential, a generalized Levinson theorem is put forward showing the equality of the total density of surface states and the density of the total time delay. The proof uses explicit formulas for the wave operators in the new rescaled energy and interaction (REI) representation, as well as an index theorem for adequate associated operator algebras.

Hermann Schulz-Baldes

2013-05-09T23:59:59.000Z

407

Statistical delay budget partitioning in wireless mesh networks  

Science Conference Proceedings (OSTI)

Wireless Mesh Networks (WMNs) are currently attracting strong attention due to their great potential in supporting multimedia applications with real-time transport with last-mile Internet access. Multimedia end-to-end transmission requires Quality of ... Keywords: Delay budget partitioning, End-to-end QoS, IEEE 802.11s, IEEE 802.16j, Radio resource management, Wireless mesh networks

Najah A. Abu-Ali; Hossam S. Hassanein

2008-05-01T23:59:59.000Z

408

Femtosecond Time-Delay X-ray Holography  

NLE Websites -- All DOE Office Websites (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.

409

Predicting Ignition Delay for Gas Turbine Fuel Flexibility  

NLE Websites -- All DOE Office Websites (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

410

Controlled Nonlinear Stochastic Delay Equations: Part I: Modeling and Approximations  

SciTech Connect

This two-part paper deals with 'foundational' issues that have not been previously considered in the modeling and numerical optimization of nonlinear stochastic delay systems. There are new classes of models, such as those with nonlinear functions of several controls (such as products), each with is own delay, controlled random Poisson measure driving terms, admissions control with delayed retrials, and others. There are two basic and interconnected themes for these models. The first, dealt with in this part, concerns the definition of admissible control. The classical definition of an admissible control as a nonanticipative relaxed control is inadequate for these models and needs to be extended. This is needed for the convergence proofs of numerical approximations for optimal controls as well as to have a well-defined model. It is shown that the new classes of admissible controls do not enlarge the range of the value functions, is closed (together with the associated paths) under weak convergence, and is approximatable by ordinary controls. The second theme, dealt with in Part II, concerns transportation equation representations, and their role in the development of numerical algorithms with much reduced memory and computational requirements.

Kushner, Harold J., E-mail: hjk@dam.brown.edu [Brown University, Applied Math (United States)

2012-08-15T23:59:59.000Z

411

Variable pressure thermal insulating jacket  

DOE Patents (OSTI)

A device for controlled insulation of a thermal device. 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 communcation 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.

Nelson, Paul A. (Wheaton, IL); Malecha, Richard F. (Naperville, IL); Chilenskas, Albert A. (Chicago, IL)

1994-01-01T23:59:59.000Z

412

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

413

Getting There: Exploring the Role of Expectations and Preproduction Delays in Processes of Organizational Founding  

Science Conference Proceedings (OSTI)

Because of preproduction delays, environmental conditions at founding cannot explain organization-building decisions taken earlier. As a consequence, environmental conditions at founding cannot explain organizational founding. Future levels of resource ... Keywords: computer simulation, delays, feedback models, organizational founding, preproduction

Alessandro Lomi; Erik R. Larsen; Filippo Carlo Wezel

2010-01-01T23:59:59.000Z

414

Scheduling algorithms for throughput maximization in time-varying networks with reconfiguration delays  

E-Print Network (OSTI)

We consider the control of possibly time-varying wireless networks under reconfiguration delays. Reconfiguration delay is the time it takes to switch network resources from one subset of nodes to another and it is a ...

Celik, Guner Dincer

2012-01-01T23:59:59.000Z

415

VTrack: Accurate, energy-aware road traffic delay estimation using mobile phones  

E-Print Network (OSTI)

Traffic delays and congestion are a major source of inefficiency, wasted fuel, and commuter frustration. Measuring and localizing these delays, and routing users around them, is an important step towards reducing the time ...

Thiagarajan, Arvind

416

A Soft X-ray Split and Delay System for LCLS | Stanford Synchrotron...  

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

Room 108A Brendan Murphy, LCLS In this talk I will describe the development and commissioning of the x-ray split and delay (XRSD) system at LCLS. The XRSD is a two-mirror delay...

417

A Study of Delays in Making Tide Gauge Data Available to Tsunami Warning Centers  

Science Conference Proceedings (OSTI)

This short note provides conclusions of a study of the various factors that determine the delay between tsunami arrival at a tide gauge station and data being made available at tsunami warning centers. The various delays involved include those ...

S. J. Holgate; P. L. Woodworth; P. R. Foden; J. Pugh

2008-03-01T23:59:59.000Z

418

Accuracy and Variability of GPS Tropospheric Delay Measurements of Water Vapor in the Western Mediterranean  

Science Conference Proceedings (OSTI)

As a preliminary step for assessing the impact of global positioning system (GPS) refractive delay data in numerical weather prediction (NWP) models, the GPS zenith tropospheric delays (ZTDs) are analyzed from 51 permanent GPS sites in the ...

Jennifer Haase; Maorong Ge; Henrik Vedel; Eric Calais

2003-11-01T23:59:59.000Z

419

Significance of joint features derived from the modified group delay function in speech processing  

Science Conference Proceedings (OSTI)

This paper investigates the significance of combining cepstral features derived from the modified group delay function and from the short-time spectral magnitude like the MFCC. The conventional group delay function fails to capture the resonant structure ...

Rajesh M. Hegde; Hema A. Murthy; V. R. R. Gadde

2007-01-01T23:59:59.000Z

420

Studies on the disbonding initiation of interfacial cracks.  

SciTech Connect

With the continuing trend of decreasing feature sizes in flip-chip assemblies, the reliability tolerance to interfacial flaws is also decreasing. Small-scale disbonds will become more of a concern, pointing to the need for a better understanding of the initiation stage of interfacial delamination. With most accepted adhesion metric methodologies tailored to predict failure under the prior existence of a disbond, the study of the initiation phenomenon is open to development and standardization of new testing procedures. Traditional fracture mechanics approaches are not suitable, as the mathematics assume failure to originate at a disbond or crack tip. Disbond initiation is believed to first occur at free edges and corners, which act as high stress concentration sites and exhibit singular stresses similar to a crack tip, though less severe in intensity. As such, a 'fracture mechanics-like' approach may be employed which defines a material parameter--a critical stress intensity factor (K{sub c})--that can be used to predict when initiation of a disbond at an interface will occur. The factors affecting the adhesion of underfill/polyimide interfaces relevant to flip-chip assemblies were investigated in this study. The study consisted of two distinct parts: a comparison of the initiation and propagation phenomena and a comparison of the relationship between sub-critical and critical initiation of interfacial failure. The initiation of underfill interfacial failure was studied by characterizing failure at a free-edge with a critical stress intensity factor. In comparison with the interfacial fracture toughness testing, it was shown that a good correlation exists between the initiation and propagation of interfacial failures. Such a correlation justifies the continuing use of fracture mechanics to predict the reliability of flip-chip packages. The second aspect of the research involved fatigue testing of tensile butt joint specimens to determine lifetimes at sub-critical load levels. The results display an interfacial strength ranking similar to that observed during monotonic testing. The fatigue results indicate that monotonic fracture mechanics testing may be an adequate screening tool to help predict cyclic underfill failure; however lifetime data is required to predict reliability.

McAdams, Brian J. (Lehigh University, Bethlehem, PA); Pearson, Raymond A. (Lehigh University, Bethlehem, PA)

2005-08-01T23:59:59.000Z

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

Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity  

E-Print Network (OSTI)

The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

Andrea Piccolroaz; Gennady Mishuris

2011-10-17T23:59:59.000Z

422

Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity  

E-Print Network (OSTI)

The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

Piccolroaz, Andrea

2011-01-01T23:59:59.000Z

423

An Overview of Stress Cracking of Pipeline Steels in Near-neutral ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Stress cracking of pipeline steels in near-neutral pH has remained a virile integrity risk for oil and gas pipelines. Although it was termed as stress...

424

Influence of Cerium on Stress Corrosion Cracking in AZ91D  

Science Conference Proceedings (OSTI)

This paper considers the effect of cerium additions on the stress corrosion cracking in the Mg-Al-Zn alloy AZ91D. The two dominant phases in the AZ91D...

425

Stress intensity magnification factors for fully circumferential cracks in valve bodies (thick cylinders)  

SciTech Connect

The stress intensity solutions presented herein were obtained using an energy method in conjunction with a two-dimensional finite element program in order to explicitly account for curvature effect for fully circumferential cracks. The magnification factors for a specific crack depth were calculated by successively loading the crack surface by a uniform, linear, quadratic, and a cubic loading distribution. The magnification factors can be used to calculate the stress intensity factors by superposition method. The functions for each load condition in terms of radius to thickness ratio (R/t) and a fractional distance in terms of crack depth to thickness ratio (a/t) were developed. The validity of these functions is R/t = 1.5 to 10.0 and for 0.0125 {le} a/t {le} 0.8125. The functions agree to within 1% of the finite elements solutions for most magnification factors.

Toor, P.M.

1998-11-01T23:59:59.000Z

426

Remarks on the energy release rate for an antiplane moving crack in couple stress elasticity  

E-Print Network (OSTI)

This paper is concerned with the steady-state propagation of an antiplane semi-infinite crack in couple stress elastic materials. A distributed loading applied at the crack faces and moving with the same velocity of the crack tip is considered, and the influence of the loading profile variations and microstructural effects on the dynamic energy release rate is investigated. The behaviour of both energy release rate and maximum total shear stress when the crack tip speed approaches the critical speed (either that of the shear waves or that of the Rayleigh waves) is studied. The limit case corresponding to vanishing characteristic scale lengths is addressed both numerically and analytically by means of a comparison with classical elasticity results.

L. Morini; A. Piccolroaz; G. Mishuris

2013-11-21T23:59:59.000Z

427

Interpretation of warm prestress-induced fracture toughness based on crack-tip constraint  

SciTech Connect

This study explores the possibility of using J-Q-related crack-tip constraint concepts to provide a basis for both the interpretation of warm prestress (WPS)-induced fracture toughness and their transferability to structural applications. A finite-element boundary-layer formulation based on small-scale yielding (SSY), remote mode I K-dominant assumptions is adopted. Effects of WPS-induced crack-tip constraint are quantified in terms of deviation in either the opening-mode or the mean stress component of the WPS crack-tip fields relative to the reference K-dominant SSY state associated with monotonic-loading conditions. Over the range of WPS load-paths considered the WPS-induced crack-tip constraint closely resembles a spatially varying hydrostatic stress field. Interpretation and transferability of WPS fracture toughness under SSY conditions are specified in terms of the unload and reload ratio.

Shum, D.K.M.

1993-06-01T23:59:59.000Z

428

SLAC National Accelerator Laboratory - BaBar Data Hint at Cracks...  

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

Press Release Archive BaBar Data Hint at Cracks in the Standard Model June 18, 2012 Menlo Park, Calif. - Recently analyzed data from the BaBar experiment may suggest possible flaws...

429

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

430

Preliminary Simulations for Geometric Optimization of a High-Energy Delayed Gamma Spectrometer for Direct Assay of Pu in Spent Nuclear Fuel  

Science Conference Proceedings (OSTI)

High-energy, beta-delayed gamma-ray spectroscopy is under investigation as part of the Next Generation Safeguard Initiative effort to develop non-destructive assay instruments for plutonium mass quantification in spent nuclear fuel assemblies. Results obtained to date indicate that individual isotope-specific signatures contained in the delayed gamma-ray spectra can potentially be used to quantify the total fissile content and individual weight fractions of fissile and fertile nuclides present in spent fuel. Adequate assay precision for inventory analysis can be obtained using a neutron generator of sufficient strength and currently available detection technology. In an attempt to optimize the geometric configuration and material composition for a delayed gamma measurement on spent fuel, the current study applies MCNPX, a Monte Carlo radiation transport code, in order to obtain the best signal-to-noise ratio. Results are presented for optimizing the neutron spectrum tailoring material, geometries to maximize thermal or fast fissions from a given neutron source, and detector location to allow an acceptable delayed gamma-ray signal while achieving a reasonable detector lifetime while operating in a high-energy neutron field. This work is supported in part by the Next Generation Safeguards Initiative, Office of Nuclear Safeguards and Security, National Nuclear Security Administration.

Kulisek, Jonathan A.; Campbell, Luke W.; Rodriguez, Douglas C.

2012-06-07T23:59:59.000Z

431

Thermal protection apparatus  

DOE Patents (OSTI)

An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

Bennett, Gloria A. (Los Alamos, NM); Elder, Michael G. (Los Alamos, NM); Kemme, Joseph E. (Albuquerque, NM)

1985-01-01T23:59:59.000Z

432

Thermal protection apparatus  

DOE Patents (OSTI)

The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

Bennett, G.A.; Elder, M.G.; Kemme, J.E.

1984-03-20T23:59:59.000Z

433

Thermal masses in leptogenesis  

E-Print Network (OSTI)

We investigate the validity of using thermal masses in the kinematics of final states in the decay rate of heavy neutrinos in leptogenesis calculations. We find that using thermal masses this way is a reasonable approximation, but corrections arise through quantum statistical distribution functions and leptonic quasiparticles.

Kiessig, Clemens P

2009-01-01T23:59:59.000Z

434

Opportunistic media access control and routing for delay-tolerant mobile ad hoc networks  

Science Conference Proceedings (OSTI)

In delay-tolerant mobile ad hoc networks, motion of network nodes, network sparsity and sporadic density can cause a lack of guaranteed connectivity. These networks experience significant link delay and their routing protocols must take a store-and-forward ... Keywords: Cross-layer adaptation design, Delay-tolerant network, Mobile ad hoc network, Opportunistic routing, Vehicular ad hoc network

Liang Dong

2012-11-01T23:59:59.000Z

435

Short Survey: Intelligent switching expert system for delayed coking unit based on iterative learning strategy  

Science Conference Proceedings (OSTI)

Delayed coking is the most effective process to decarbonize and demetallize heavy petroleum residues. However, it relies much on the field engineers' experiences and expertise in practice for operating the controllers effectively and compatibly in delayed ... Keywords: Delayed coking, Expert system, Intelligent control, Iterative learning

Xiaodong Yu; Yujie Wei; Dexian Huang; Yongheng Jiang; Bo Liu; Yihui Jin

2011-07-01T23:59:59.000Z

436

Adaptive posicast controller for time-delay systems with relative degree n*?2  

Science Conference Proceedings (OSTI)

In this paper, we present an Adaptive Posicast Controller that deals with parametric uncertainties in linear systems with delays. It is assumed that the plant has no right half plane zeros and the delay is known. The adaptive controller is based on the ... Keywords: Adaptive control, Model matching, Time-delay systems

Yildiray Yildiz; Anuradha Annaswamy; Ilya V. Kolmanovsky; Diana Yanakiev

2010-02-01T23:59:59.000Z

437

Sliding mode for detection and accommodation of computation time delay fault  

Science Conference Proceedings (OSTI)

Computation time delay in digital control systems reduces its robustness as well as degrades its performance. In this paper, the computation time delay is assumed to be constant and smaller than the sampling time and is treated as a fault to be detected, ... Keywords: Computation time delay, Discrete-time sliding mode control, Fault detection, Sliding mode observer

Jos Paulo F. Garcia; Lizete Maria C. F. Garcia; Gisele C. Apolinrio; Fernando B. Rodrigues

2009-10-01T23:59:59.000Z

438

Coping with buffer delay change due to power and ground noise  

Science Conference Proceedings (OSTI)

Variation of power and ground levels affect VLSI circuit performance. Trends in device technology and in packaging have necessitated a revision in conventional delay models. In particular, simple scalable models are needed to predict delays in the presence ... Keywords: common mode noise, differential mode noise, incremental delay change, power and ground noise

Lauren Hui Chen; Malgorzata Marek-Sadowska; Forrest Brewer

2002-06-01T23:59:59.000Z

439

Finite-time robust stochastic stability of uncertain stochastic delayed reaction-diffusion genetic regulatory networks  

Science Conference Proceedings (OSTI)

This paper is concerned with the problem of finite-time stability analysis for uncertain stochastic delayed reaction-diffusion genetic regulatory networks. The parameter uncertainties are assumed to be norm-bounded, and the time delays are assumed to ... Keywords: Finite-time stochastic stability, Genetic regulatory networks, Reaction-diffusion, Stochastic noise, Time delays

Jianping Zhou; Shengyuan Xu; Hao Shen

2011-10-01T23:59:59.000Z

440

Energy-Delay Tradeoffs in Combinational Logic using Gate Sizing and Supply Voltage Optimization  

E-Print Network (OSTI)

Energy-Delay Tradeoffs in Combinational Logic using Gate Sizing and Supply Voltage Optimization savings to the energy profile of a circuit. These savings are obtained by using gate sizing and supply of energy to delay is derived from a linear delay model extended to multiple supplies. The optimizations

Nikolic, Borivoje

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

Verification and Implementation of Delay-Insensitive Processes in Restrictive Environments  

Science Conference Proceedings (OSTI)

A delay-insensitive module communicates with its environment through wires of unbounded delay. To avoid transmission interference, the absorption of a signal transition must be acknowledged before another one is propagated along the same wire. The environment ... Keywords: Asynchronous circuits, Closed systems, Delay-insensitivity, Process algebra, Restrictive environments, Verification

Hemangee K. Kapoor; Mark B. Josephs; Dennis P. Furey

2006-04-01T23:59:59.000Z

442

Thermal treatment wall  

DOE Patents (OSTI)

A thermal treatment wall emplaced to perform in-situ destruction of contaminants in groundwater. Thermal destruction of specific contaminants occurs by hydrous pyrolysis/oxidation at temperatures achievable by existing thermal remediation techniques (electrical heating or steam injection) in the presence of oxygen or soil mineral oxidants, such as MnO.sub.2. The thermal treatment wall can be installed in a variety of configurations depending on the specific objectives, and can be used for groundwater cleanup, wherein in-situ destruction of contaminants is carried out rather than extracting contaminated fluids to the surface, where they are to be cleaned. In addition, the thermal treatment wall can be used for both plume interdiction and near-wellhead in-situ groundwater treatment. Thus, this technique can be utilized for a variety of groundwater contamination problems.

Aines, Roger D. (Livermore, CA); Newmark, Robin L. (Livermore, CA); Knauss, Kevin G. (Livermore, CA)

2000-01-01T23:59:59.000Z

443

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

444

Root Causes of Circumferential Cracking in Waterwalls of Supercritical Units: State-of-Knowledge  

Science Conference Proceedings (OSTI)

Circumferential cracking on the waterwalls has again become a significant problem for many supercritical units, especially with the implementation of low-NOx systems. Damage typically consists of multiple, parallel cracks perpendicular to the longitudinal axis of the tube and to the direction of maximum tensile stress. There can be numerous potential causes, and the choice of the appropriate control strategy will depend on identifying the underlying cause(s) for a particular outbreak of damage. This repo...

2008-02-08T23:59:59.000Z

445

Stress Corrosion Cracking Initiation Model for Stainless Steel and Nickel Alloys  

Science Conference Proceedings (OSTI)

This report provides a quantitative framework or model of general applicability in an engineering evaluation of stress corrosion cracking (SCC) initiation, including initial short crack growth, which accounts for the varied effects of cold work (CW) on SCC susceptibility. The microstructural impact of CW is accounted for through the materials strength and strain-hardening response. CW generally acts as an accelerant in SCC. Both the surface-layer-limited cold work and the through-thickness condition nee...

2009-11-20T23:59:59.000Z

446

Program on Technology Innovation: A Mechanistic Basis for Irradiation Assisted Stress Corrosion Cracking  

Science Conference Proceedings (OSTI)

Irradiation-assisted stress corrosion cracking (IASCC) refers to intergranular stress corrosion cracking that is accelerated under the action of irradiation in light water reactor core components. It is referred to as assisted because irradiation enhances, or accelerates, the IGSCC process over the non-irradiated state. IASCC has been a problem in the nuclear industry for the last 40 years and continues to occur due to a lack of understanding of its underlying mechanism. It is the single most important...

2009-09-08T23:59:59.000Z

447

Repair and Replacement Applications Center: Stress Corrosion Cracking in Closed Cooling Water Systems  

Science Conference Proceedings (OSTI)

The results of a recent EPRI project "Stress Corrosion Cracking in PWR and BWR Closed Cooling Water Systems," (EPRI Report 1009721, October 2004) indicated that approximately 10 of 143 light water reactor (LWR) plants surveyed had through-wall leaks in carbon steel piping in their closed cooling water (CCW) systems. The root cause of this leakage was intergranular stress corrosion cracking. Since there has not been extensive non-destructive testing in these systems, it is likely that the incidence rate o...

2006-09-28T23:59:59.000Z

448

Development of an LP Rotor Rim-Attachment Cracking Life Assessment Code (LPRimLife)  

Science Conference Proceedings (OSTI)

Most of the domestic turbine fleet has reached the 50,000-hour range of service operation. Unfortunately, above this level of operational hours, a number of turbines have begun to experience low-pressure (LP) rim-attachment cracking. A computer code developed by EPRI, LPRimLife, provides utilities with a methodology for assessing the remaining life of LP rim attachments with known or suspected cracking.

1999-12-07T23:59:59.000Z

449

Understanding the Interaction Between Localized Deformation in Materials and Environmentally Assisted Cracking  

Science Conference Proceedings (OSTI)

This report sets out to develop an understanding of the interaction between localized mechanical deformation in reactor structural materials (such as nickel-base alloys, austenitic stainless steels, or carbon and low-alloy steels) and their susceptibility to degradation by environmentally assisted cracking (EAC) after long-term exposure to light water reactor coolant. The main emphasis is on stress corrosion cracking (SCC), with and without the influence of irradiation, in the pressurized water reactor (...

2005-12-19T23:59:59.000Z

450

Stress Corrosion Cracking Resistance of Weld Metals 182, 72, and 308L  

Science Conference Proceedings (OSTI)

Intergranular stress corrosion cracking (IGSCC) has occurred in alloy 182 weld metal in operating BWRs. This study compares the propagation behavior of IGSCC for nickel-base weld metal, alloy 182, with two other weld metals: type 308L stainless steel and a high-chromium nickel-base BWR candidate, alloy 72. Results indicate that weld metal 72 is more stress corrosion crack (SCC) resistant than either weld metals 182 or type 308L.

1992-08-01T23:59:59.000Z

451

Development of a Thin Film Sensor for Detecting Initiation of Stress Corrosion Cracks in Stainless Steels  

Science Conference Proceedings (OSTI)

The study of initiation of intergranular stress corrosion cracking (IGSCC) has been hindered by lack of techniques to detect small cracks ranging in depth from sub-micron to several microns. The present investigation's main objective is to develop a thin film sample suitable for detecting and studying initiation of IGSCC in sensitized austenitic stainless steel. Two approaches are being investigated to produce thin films of stainless steel: pulse laser deposition (PLD) of ultrathin films (20-150 nm) usin...

2002-12-11T23:59:59.000Z

452

Program on Technology Innovation: Development of Thin-Film Sensors to Detect Stress Corrosion Crack Initiation  

Science Conference Proceedings (OSTI)

A great amount of effort has been expended measuring stress corrosion crack (SCC) growth rates and investigating the mechanisms of SCC propagation. By contrast, relatively little effort has been devoted to studies of SCC initiation. The small amount of work on SCC initiation is due, in part, to the difficulty in investigating this phase of cracking. The main objective of the present investigation is to develop a thin-film sensor suitable for detecting and studying the initiation of intergranular stress c...

2005-12-02T23:59:59.000Z

453

Assessment of Nondestructive Evaluation Methods and Analytical Procedures for Thick-Section Component Cracking  

Science Conference Proceedings (OSTI)

A significant concern for owners and operators, damage in the form of cracking in thick-section components (valves, casings, headers, and so on) in fossil fuelfired boilers continues to be observed. With increased cyclic duty and the fast startups associated with combined-cycle plants, such damage will remain a prevalent industry problem. Specifically, the concerns for continued operation of cracked thick-section components arise from the uncertainties associated with the nondestructive ...

2013-08-21T23:59:59.000Z

454

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

455

Effects of hydrogen on electropotential monitoring of stress corrosion crack growth  

DOE Green Energy (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

456

Predicting runaway reaction in a solid explosive containing a single crack  

Science Conference Proceedings (OSTI)

Mechanically damaged high explosive (HE) undergoing defiagration has recently been shown capable of generating combustion pressures and flame speeds dramatically in excess of those observed in undamaged HE. Flame penetration of HE cracks large enough to support the reaction zone serves to increase the burning surface area and the rate of gas production. Cracks confine the product gas, elevating the local pressure and reducing the reaction zone thickness such that the flame can enter smaller-width cracks. As the reaction zone decreases sufficiently to enter the smallest cracks, the flame surface area will grow appreciably, rapidly pressurizing the cracks. This runaway of pressure and burning area, termed combustion bootstrapping, can dramatically accelerate the combustion mode and in the most extreme cases may result in deflagration-to-detonation transition [3, 4]. The current study is intended to help predict the conditions required for the onset of reaction runaway in a narrow slot in HE. We review experiments [5] where flames were observed to propagate though a narrow slot (intended to simulate a well-formed crack) in high explosive at velocities up to 10 km/s, reaching pressures in excess of 1 kbar. Pressurization of the slot due to gas-dynamic choking is then used to predict the onset of runaway reaction. This model agrees with experimental pressure measurements of observed reaction runaway in slots.

Jackson, Scott I [Los Alamos National Laboratory; Hill, Larry G [Los Alamos National Laboratory

2009-01-01T23:59:59.000Z

457

Fatigue-crack propagation in aluminum-lithium alloys processed by power and ingot metallurgy  

Science Conference Proceedings (OSTI)

Fatigue-crack propagation behavior in powder-metallurgy (P/M) aluminum-lithium alloys, namely, mechanically-alloyed (MA) Al-4.0Mg-1.5Li-1.1C-0.80{sub 2} (Inco 905-XL) and rapid-solidification-processed (RSP) Al-2.6Li-1.0Cu-0.5Mg-0.5Zr (Allied 644-B) extrusions, has been studied, and results compared with data on an equivalent ingot-metallurgy (I/M) Al-Li alloy, 2090-T81 plate. Fatigue-crack growth resistance of the RSP Al-Li alloy is found to be comparable to the I/M Al-Li alloy; in contrast, crack velocities in MA 905-XL extrusions are nearly three orders of magnitude faster. Growth-rate response in both P/M Al-Li alloys, however, is high anisotropic. Results are interpreted in terms of the microstructural influence of strengthening mechanism, slip mode, grain morphology and texture on the development of crack-tip shielding from crack-path deflection and crack closure. 14 refs., 7 figs., 2 tabs.

Venkateswara Rao, K.T.; Ritchie, R.O. (Lawrence Berkeley Lab., CA (United States)); Kim, N.J. (Pohang Inst. of Science and Technology (Korea, Republic of)); Pizzo, P.P. (San Jose State Univ., CA (United States))

1990-04-01T23:59:59.000Z

458

Thermally-related safety issues associated with thermal batteries.  

DOE Green Energy (OSTI)

Thermal batteries can experience thermal runaway under certain usage conditions. This can lead to safety issues for personnel and cause damage to associated test equipment if the battery thermally self destructs. This report discusses a number of thermal and design related issues that can lead to catastrophic destruction of thermal batteries under certain conditions. Contributing factors are identified and mitigating actions are presented to minimize or prevent undesirable thermal runaway.

Guidotti, Ronald Armand

2006-06-01T23:59:59.000Z

459

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

Science Conference Proceedings (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

460

Damage Evolution in Thermal Barrier Coatings with Thermal Cycling  

Science Conference Proceedings (OSTI)

Abstract Scope, Thermal barrier coatings typically fail on cooling after prolonged thermal cycling by the growth of sub-critical interface separations. Observations...

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

Efficient thermal management for multiprocessor systems  

E-Print Network (OSTI)

2.2.4 Thermal Modeling . . . . . . . .63 Table 4.3: Thermal Hot Spots . . . . . . . . . . . . . .Performance-Efficient Thermal Management . . . . . . . . . .

Co?kun, Ay?e K?v?lc?m

2009-01-01T23:59:59.000Z

462

A numerical study of bench blast row delay timing and its influence on percent-cast  

SciTech Connect

The computer program, DMC (Distinct Motion Code), which was developed for simulating the rock motion associated with blasting, has been used to study the influence of row delay timing on rock motion. The numerical simulations correspond with field observations in that very short delays (< 50ms) and very long delays (> 300ms) produce a lower percent-cast than a medium delay (100 to 200 ms). The DMC predicted relationship between row delay timing and percent-cast is more complex than expected with a dip in the curve where the optimum timing might be expected. More study is required to gain a full understanding of this phenomenon.

Preece, D.S.

1993-11-01T23:59:59.000Z

463

MacroscoMacroscopic Cracking Determination in LaBS Glasspic Cracking Determination in LaBS Glass  

SciTech Connect

The DOE/EM plans to conduct the Plutonium Vitrification Project at the Savannah River Site (SRS). An important part of this project is to reduce the attractiveness of the plutonium by fabricating a plutonium glass form and immobilizing the Pu form within the high level waste (HLW) glass prepared in the Defense Waste Processing Facility (DWPF). This requires that a project schedule that is consistent with EM plans for DWPF and cleanup of the SRS be developed. Critical inputs to key decisions in the vitrification project schedule are near-term data that will increase confidence that the lanthanide borosilicate (LaBS) glass product is suitable for disposal in the Yucca Mountain Repository. A workshop was held on April 28, 2005 at Bechtel SAIC Company (BSC) facility in Las Vegas, NV to define the near term data needs. Dissolution rate data and the fate of plutonium oxide and the neutron absorbers during the dissolution process were defined as key data needs. A suite of short-term tests were defined at the workshop to obtain the needed data. The objectives of these short-term tests are to obtain data that can be used to show that the dissolution rate of a LaBS glass is acceptable and to show that the extent of Pu separation from neutron absorbers, as the glass degrades and dissolves, is not likely to lead to criticality concerns. An additional data need was identified regarding the degree of macroscopic cracking and/or voiding that occurs during processing of the Pu glass waste form and subsequent pouring of HLW glass in the DWPF. A final need to evaluate new frit formulations that may increase the durability of the plutonium glass and/or decrease the degree to which neutron absorbers separate from the plutonium during dissolution was identified. This task plan covers the need to evaluate the degree of macroscopic cracking and/or voiding that occurs during processing of the Vitrified Plutonium Waste Form (i.e. the can-in-canister configuration containing the vitrified Pu product). Separate task plans were developed for Pu glass performance testing of the current baseline LaBS glass composition and development of alternative frit formulations. Recent results from Pressurized Unsaturated Flow (PUF) testing showed the potential separation of Pu from Gd during the glass dissolution process [3]. Post-test analysis of the LaBS glass from a 6-year PUF test showed a region where Pu had apparently accumulated in a Pu-bearing disk-like phase that had become separated from neutron absorber (Gd). It should be noted that this testing was conducted on the early LaBS Frit A glass composition that was devoid of HfO{sub 2} as a neutron absorber. PUF testing is currently being initiated using the LaBS Frit B composition that contains HfO{sub 2}. The potential for fissile material and neutron absorber separation is a criticality risk for the repository. The surface area that is available for leaching (i.e. due to the degree of cracking or voiding within the Pu glass cylinder) is a factor in modeling the amount of fissile material and neutron absorber released during the dissolution process. A mathematical expression for surface area is used in the Total Systems Performance Assessment (TSPA) performed by BSC personnel. Specifically, the surface area available for leaching is being used in current external criticality assessments. The planned processing steps for producing a VPWF assembly involves processing Pu feed and LaBS frit to produce a can of Pu LaBS glass, packaging this can into a second can (i.e. bagless transfer) for removal from the glovebox processing environment, placing a series of bagless transfer cans into a DWPF canister, and pouring HLW glass into the DWPF canister to encapsulate bagless transfer cans. The objective of this task is to quantify the degree of cracking and/or voiding that will occur during the processing of the VPWF.

Marra, James

2005-08-01T23:59:59.000Z

464

Design and economics for low pressure delayed coking  

Science Conference Proceedings (OSTI)

The current refining trend is to run heavier crudes with a growing emphasis on bottom of the barrel resid upgrading. In general, a reduction in light crude availability and a corresponding increase in the price differential between light and heavy crudes makes the processing of heavier crudes highly attractive. US Department of Energy data indicate that between 1985 and 1989 the average API gravity of crude being processed in the US dropped from 32.46 to 32.14 degrees while the average sulfur content increased 0.15 wt%. As crudes get heavier and the demand for light, clean fuels increases, expanded resid upgrading capacity is rapidly becoming a necessity for most refiners. The coking process has existed since the early 1900's, and delayed coking is still favored as a relatively low cost resid upgrading option. Consistent with the objective of maximizing resid conversion, recent trends in delayed coking include maximizing liquid yields and reducing the production of petroleum coke by operating coke drums at lower pressures. Typically, the incremental liquid gained at lower pressures is worth significantly more than coke and can be further upgraded to lighter products. In addition, the driving force to minimize coke make has been accelerated by the worsening quality of crude oils. As vacuum resid feedstocks become heavier, contaminants in coke such as sulfur and metals are increased, making the coke less marketable. In the case of an existing coker which is capacity limited by coke make, a reduction in coke yield can be quite valuable. This paper discusses the design features and presents the economics associated with building a low pressure delayed coker with a 15 psig coke drum operating pressure versus a more conventional 25 psig design.

Bansal, B.B.; Moretta, J.C.; Gentry, A.R. (M.W. Kellogg Co., Houston, TX (United States))

1993-01-01T23:59:59.000Z

465

Cooling thermal storage  

Science Conference Proceedings (OSTI)

This article gives some overall guidelines for successful operation of cooling thermal storage installations. Electric utilities use rates and other incentives to encourage thermal storage, which not only reduces their system peaks but also transfers a portion of their load from expensive daytime inefficient peaking plants to less expensive nighttime base load high efficiency coal and nuclear plants. There are hundreds of thermal storage installations around the country. Some of these are very successful; others have failed to achieve all of their predicted benefits because application considerations were not properly addressed.

Gatley, D.P.

1987-04-01T23:59:59.000Z

466

Solar Thermal Conversion  

DOE Green Energy (OSTI)

The thermal conversion process of solar energy is based on well-known phenomena of heat transfer (Kreith 1976). In all thermal conversion processes, solar radiation is absorbed at the surface of a receiver, which contains or is in contact with flow passages through which a working fluid passes. As the receiver heats up, heat is transferred to the working fluid which may be air, water, oil, or a molten salt. The upper temperature that can be achieved in solar thermal conversion depends on the insolation, the degree to which the sunlight is concentrated, and the measures taken to reduce heat losses from the working fluid.

Kreith, F.; Meyer, R. T.

1982-11-01T23:59:59.000Z

467

Herding, Contrarianism and Delay in Financial Market Trading  

E-Print Network (OSTI)

-orders depending on the passage of time, and they do not employ information that could (theoretically) trigger herding or contrarianism. Ivanov, Levin, and Peck (2008) implement Levin and Peck (2008), which is a model of fixed capital (green-field), non... tells the final subject that there are no more informative actions to come, and so no further reason to delay. 16 pressing the pass-button would count as one of the actions that they were allowed. It was stressed to the subjects that their virtual...

Park, A; Sgroi, Daniel

468

Multilayer thermal barrier coating systems  

DOE Patents (OSTI)

The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

2000-01-01T23:59:59.000Z

469

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

470

Ocean Thermal | Open Energy Information  

Open Energy Info (EERE)

Community Login | Sign Up Search Page Edit History Facebook icon Twitter icon Ocean Thermal Jump to: navigation, search TODO: Add description List of Ocean Thermal Incentives...

471

Comparison of Thermal Insulation Materials.  

E-Print Network (OSTI)

??This thesis is about comparing of different thermal insulation materials of different manufactures. In our days there are a lot of different thermal insulation materials (more)

Chaykovskiy, German

2010-01-01T23:59:59.000Z

472

Integrability vs Quantum Thermalization  

E-Print Network (OSTI)

Non-integrability is often taken as a prerequisite for quantum thermalization. Still, a generally accepted definition of quantum integrability is lacking. With the basis in the driven Rabi model we discuss this careless usage of the term "integrability" in connection to quantum thermalization. The model would be classified as non-integrable according to the most commonly used definitions, for example, the only preserved quantity is the total energy. Despite this fact, a thorough analysis conjectures that the system will not thermalize. Thus, our findings suggest first of all (i) that care should be paid when linking non-integrability with thermalization, and secondly (ii) that the standardly used definitions for quantum integrability are unsatisfactory.

Jonas Larson

2013-04-12T23:59:59.000Z

473

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

474

Properties of Thermal Glueballs  

E-Print Network (OSTI)

We study the properties of the 0++ glueball at finite temperature using SU(3) quenched lattice QCD. We find a significant thermal effects near T_c. We perform the \\chi^2 fit analyses adopting two Ansaetze for the spectral function, i.e., the conventional narrow-peak Ansatz and an advanced Breit-Wigner Ansatz. The latter is an extension of the former, taking account of the appearance of the thermal width at T>0. We also perform the MEM analysis. These analyses indicate that the thermal effect on the glueball is a significant thermal-width broadening \\Gamma(T_c) \\sim 300 MeV together with a modest reduction in the peak center \\Delta\\omega_0(T_c) \\sim 100 MeV.

Noriyoshi Ishii; Hideo Suganuma

2003-12-27T23:59:59.000Z

475

Thermal springs of Wyoming  

SciTech Connect

This bulletin attempts, first, to provide a comprehensive inventory of the thermal springs of Wyoming; second, to explore the geologic and hydrologic factors producing these springs; and, third, to analyze the springs collectively as an indicator of the geothermal resources of the state. A general discussion of the state's geology and the mechanisms of thermal spring production, along with a brief comparison of Wyoming's springs with worldwide thermal features are included. A discussion of geothermal energy resources, a guide for visitors, and an analysis of the flora of Wyoming's springs follow the spring inventory. The listing and analysis of Wyoming's thermal springs are arranged alphabetically by county. Tabulated data are given on elevation, ownership, access, water temperature, and flow rate. Each spring system is described and its history, general characteristics and uses, geology, hydrology, and chemistry are discussed. (MHR)

Breckenridge, R.M.; Hinckley, B.S.

1978-01-01T23:59:59.000Z

476

Thermal springs of Wyoming  

DOE Green Energy (OSTI)

This bulletin attempts, first, to provide a comprehensive inventory of the thermal springs of Wyoming; second, to explore the geologic and hydrologic factors producing these springs; and, third, to analyze the springs collectively as an indicator of the geothermal resources of the state. A general discussion of the state's geology and the mechanisms of thermal spring production, along with a brief comparison of Wyoming's springs with worldwide thermal features are included. A discussion of geothermal energy resources, a guide for visitors, and an analysis of the flora of Wyoming's springs follow the spring inventory. The listing and analysis of Wyoming's thermal springs are arranged alphabetically by county. Tabulated data are given on elevation, ownership, access, water temperature, and flow rate. Each spring system is described and its history, general characteristics and uses, geology, hydrology, and chemistry are discussed. (MHR)

Breckenridge, R.M.; Hinckley, B.S.

1978-01-01T23:59:59.000Z

477

Solar Thermal Manufacturing Activities  

Reports and Publications (EIA)

This report, Solar Thermal Collector Manufacturing Activities, providesan overview and tables with historical data spanning 2000-2009. These tables willcorrespond to similar tables to be presented in the Renewable Energy Annual 2009 andare numbered accordingly.

Michele Simmons

2010-12-01T23:59:59.000Z

478

Texas Thermal Comfort Report  

NLE Websites -- All DOE Office Websites (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

479

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

480

Thermal Energy Storage  

Science Conference Proceedings (OSTI)

This Technology Brief provides an update on the current state of cool thermal energy storage systems (TES) for end-use applications. Because of its ability to shape energy use, TES is strategic technology that allows end-users to reduce their energy costs while simultaneously providing benefits for electric utilities through persistent peak demand reduction and peak shifting. In addition to discussing the concepts of thermal energy storage, the Brief discusses the current state of TES technologies and dr...

2008-12-16T23:59:59.000Z

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

Thermal evolution of rotating strange stars in color superconductivity phase  

E-Print Network (OSTI)

Under the combination effect of the recommencement heating due to spin-down of strange stars and the heat perseveration due to weak conduct heat of the crust, the Cooper pair breaking and formation(PBF) in color superconduction quark matter arises. We investigated the cooling of the strange stars with a crust in color superconductivity phase including both decomfinement heating and PBF process. We find that deconfinement heating can delay the thermal evolution of strange stars and the PBF process suppresses the early temperature rise of the stars. The cooling strange stars behave within the brightness constraint of young compact objects when the color superconductivity gap is small enough.

X. P. Zheng; X. Zhou; Y. W. Yu

2006-07-04T23:59:59.000Z

482

Optimal Forwarding in Delay Tolerant Networks with Multiple Destinations  

E-Print Network (OSTI)

We study the trade-off between delivery delay and energy consumption in a delay tolerant network in which a message (or a file) has to be delivered to each of several destinations by epidemic relaying. In addition to the destinations, there are several other nodes in the network that can assist in relaying the message. We first assume that, at every instant, all the nodes know the number of relays carrying the packet and the number of destinations that have received the packet. We formulate the problem as a controlled continuous time Markov chain and derive the optimal closed loop control (i.e., forwarding policy). However, in practice, the intermittent connectivity in the network implies that the nodes may not have the required perfect knowledge of the system state. To address this issue, we obtain an ODE (i.e., a deterministic fluid) approximation for the optimally controlled Markov chain. This fluid approximation also yields an asymptotically optimal open loop policy. Finally, we evaluate the performance o...

Singh, Chandramani; Kumar, Anurag; Sundaresan, Rajesh

2011-01-01T23:59:59.000Z

483

On X-Channels with Feedback and Delayed CSI  

E-Print Network (OSTI)

The sum degrees of freedom (DoF) of the two-user MIMO X-channel is characterized in the presence of output feedback and delayed channel state information (CSI). The number of antennas at each transmitters is assumed to be M and the number of antennas at each of the receivers is assumed to be N. It is shown that the sum DoF of the two-user MIMO X-channel is the same as the sum DoF of a two-user MIMO broadcast channel with 2M transmit antennas, and N antennas at each receiver. Hence, for this symmetric antenna configuration, there is no performance loss in the sum degrees of freedom due to the distributed nature of the transmitters. This result highlights the usefulness of feedback and delayed CSI for the MIMO X-channel. The K-user X-channel with single antenna at each transmitter and each receiver is also studied. In this network, each transmitter has a message intended for each receiver. For this network, it is shown that the sum DoF with partial output feedback alone is at least 2K/(K+1). This lower bound is...