ECCS Operability With One or More Subsystem(s) Inoperable

International Nuclear Information System (INIS)

Swantner, Stephen R.; Andrachek, James D.

2002-01-01

Plant Technical Specifications are issued by the US NRC to ensure that safe nuclear power plant operation is maintained within the assumptions for parameters and Structures, Systems, and Components (SSCs) made in the plant safety analysis reports. The Technical Specifications are made up of Limiting Conditions for Operation (LCOs), which are the minimum set of requirements that must be met based on the assumptions of the safety analysis, Actions, which are the remedial or compensatory actions that must be taken if the LCO is not met, and Surveillance Requirements, that demonstrate that the LCO is met. The Technical Specification Actions contain Completion Times (CTs) which are the time within which remedial actions must be taken, in the event that the LCO is not met. The Improved Standard Technical Specifications (ISTS) for Westinghouse plants are contained in NUREG-1431, Revision 2. Condition A of Technical Specification 3.5.2 (ECCS- Operating) in NUREG-1431, Revision 2, allows components to be taken out of service for up to 72 hours, as long as 100% of the ECCS flow equivalent to a single Operable ECCS train exists. Condition A would allow, for example, the A train low head safety injection (LHSI) and the B train high head safety injection (HHSI) pumps to be taken out of service (for 72 hours) as long as it could be demonstrated that the remaining components could provide 100% train equivalent flow capacity. The 'cross-training' allowed by this Condition in the ISTS provides flexibility when performing routine pre-planned preventive maintenance and testing, as well as during emergent corrective maintenance and testing associated with random component inoperabilities. Without this flexibility, a unit would have to initiate a plant shutdown within 1 hour, if component(s) were inoperable in different trains. In order to implement this flexibility, the various combinations of components in opposite trains must be evaluated to determine whether 100% of the ECCS flow

Quick Look Report of the SMART ECC injection performance test I3

Energy Technology Data Exchange (ETDEWEB)

Cho, Seok; Ko, Yong Ju; Cho, Young Il; Kim, Jeong Tak; Choi, Nam Hyun; Park, Choon Kyong; Kwon, Tae Soon; Lee, Sung Jae [KAERI, Daejeon (Korea, Republic of)

2010-12-15

The objective of this report is to describe test results of the Test I3 simulating the 2 inch SBLOCA of the SMART using the SWAT test facility. The Test I3 was performed to produce experimental data for the validation of the TASS/SMR-S thermal hydraulic analysis code, and to investigate the related thermal hydraulic phenomena in the down-comer region during the 2 inch SBLOCA of the safety inject line. The particular phenomena for the observation are ECC bypass and multi-dimensional flow characteristics to verify the effectiveness and performance of the safety injection system. In this report, the corresponding steady state test conditions, including initial and boundary conditions along with major measuring parameters, and related experimental results were described

Experiment data report for Semiscale Mod-1 Test S-05-5 (alternate ECC injection test)

International Nuclear Information System (INIS)

Collins, B.L.; Patton, M.L. Jr.; Sackett, K.E.

1977-04-01

Recorded test data are presented for Test S-05-5 of the Semiscale Mod-1 alternate ECC injection test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-05-5 was conducted from initial conditions of 2263 psia and 537 0 F to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the cold leg broken loop piping. During the test, cooling water was injected into the cold leg of the intact and broken loops to simulate emergency core coolant injection in a PWR. The upper plenum was vented through a reflood bypass line interconnecting the hot and cold legs of the broken loop

Accomplishments of LOCA/ECCS experimental research at Japan Atomic Energy Research Institute

International Nuclear Information System (INIS)

Tasaka, Kanji; Murao, Yoshio; Koizumi, Yasuo

1984-01-01

Japan Atomic Energy Research Institute has investigated loss-of-coolant accident (LOCA)/emergency core cooling system (ECCS) from 1970. Major results of the LOCA/ECCS research are summarized in this report. ROSA-II program was LOCA/ECCS research for a pressurized water reactor (PWR) and ROSA-III program was for a boiling water reactor (BWR). The both test facilities were scaled at approximately 1/400 of the respective reference PWR and BWR. Large scale reflood test is research on reflood phenomena during a large break LOCA of PWR. The test facility is scaled at approximately 1/20 of the reference PWR and the research is still being continued. (author)

Method of controlling ECCS system in reactors

International Nuclear Information System (INIS)

Oohashi, Hideaki; Ikehara, Morihiko.

1982-01-01

Purpose: To eliminate the risk of misoperation and thereby improve the reliability of ECCS system upon accident. Method: ECCS system for nuclear reactor is automatically started by either of signals from a water level detector in a pressure vessel or from a pressure detector in a reactor container. Further, the ECCS system is started or stopped by the manual operation irrespective of the signals, and the signals from the pressure detector are isolated from the ECCS-starting signal by the contacts which actuate interlocked with the stopping operation of the manual operation switch. Then, after stopping the ECCS system by the manual operation, the ECCS system is started by the signals from the water level detector irrespective of the signals from the pressure detector. (Seki, T.)

Uniaxial compression test series on Bullfrog Tuff

International Nuclear Information System (INIS)

Price, R.H.; Jones, A.K.; Nimick, K.G.

1982-04-01

Nineteen uniaxial compressive experiments were performed on samples of the Bullfrog Member of the Crater Flat Tuff, obtained from drillhole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated samples were deformed at a nominal strain rate of 10 -5 sec -1 , atmospheric pressure and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 4.63 to 153. MPa, .0028 to .0058, 2.03 to 28.9 GPa and .08 to .16, respectively

Uniaxial backfill block compaction

International Nuclear Information System (INIS)

Koskinen, V.

2012-05-01

The main parts of the project were: to make a literature survey of the previous uniaxial compaction experiments; do uniaxial compaction tests in laboratory scale; and do industrial scale production tests. Object of the project was to sort out the different factors affecting the quality assurance chain of the backfill block uniaxial production and solve a material sticking to mould problem which appeared during manufacturing the blocks of bentonite and cruched rock mixture. The effect of mineralogical and chemical composition on the long term functionality of the backfill was excluded from the project. However, the used smectite-rich clays have been tested for mineralogical consistency. These tests were done in B and Tech OY according their SOPs. The objective of the Laboratory scale tests was to find right material- and compaction parameters for the industrial scale tests. Direct comparison between the laboratory scale tests and industrial scale tests is not possible because the mould geometry and compaction speed has a big influence for the compaction process. For this reason the selected material parameters were also affected by the previous compaction experiments. The industrial scale tests were done in summer of 2010 in southern Sweden. Blocks were done with uniaxial compaction. A 40 tons of the mixture of bentonite and crushed rock blocks and almost 50 tons of Friedland-clay blocks were compacted. (orig.)

Experiment data report for Semiscale Mod-1 Test S-05-3 (alternate ECC injection test)

International Nuclear Information System (INIS)

Feldman, E.M.; Patton, M.L. Jr.; Sackett, K.E.

1977-03-01

Recorded test data are presented for Test S-05-3 of the Semiscale Mod-1 alternate ECC injection test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-05-3 was conducted from initial conditions of 2263 psia and 545 0 F to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the cold leg broken loop piping. During the test, cooling water was injected into the cold leg sides of the intact and broken loops and into the vessel upper plenum to simulate emergency core coolant injection in a PWR. For Test S-05-3, specifically the effects of upper plenum coolant injection on core thermal and system response were being investigated

Investigation of Characteristics of Impinging Jet for 1/5-Scale ECC injection

Energy Technology Data Exchange (ETDEWEB)

Shin, Byung Soo; Ko, Yung Joo; Bae, Hwang; Kwon, Tae Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-05-15

In ECCS of SMART reactor, safety injection pump discharges cooling water into the core to maintain the water level by filling the amount of loss of coolant under emergency situation such as SBLOCA. Once the ECCS starts to operate, the injected water will be impinged to the upper wall of core support barrel (CBS). And the water will fall along the wall forming liquid film or droplets as shown in Fig. 1(b) due to high Reynolds number. The breakup and film flow will be bypassed by high temperature and pressure steam-water mixture cross flow from RCP discharge into the atmosphere through broken injection nozzle. Then, the flow phenomena in the downcomer is very complex situation with including jet impingement, jet breakup, liquid entrainment, steam condensation, counter-current flow and etc. In this study, the hydraulic features of impinging jet were investigated through visualization for full scale test for simulation of SMART ECC jet and SWAT test of 1/5 simulated test for ECCS of SMART reactor and measurement of the film width. And the scaling method for SWAT test was discussed considering jet break up and other phenomena

Core-power and decay-time limits for disabled automatic-actuation of LOFT ECCS

International Nuclear Information System (INIS)

Hanson, G.H.

1978-01-01

The Emergency Core Cooling System (ECCS) for the LOFT reactor may need to be disabled for modifications or repairs of hardware or instrumentation or for component testing during periods when the reactor system is hot and pressurized, or it may be desirable to enable the ECCS to be disabled without the necessity of cooling down and depressurizing the reactor. LTR 113-47 has shown that the LOFT ECCS can be safely bypassed or disabled when the total core power does not exceed 25 kW. A modified policy involves disabling the automatic actuation of the LOFT ECCS, but still retaining the manual activation capability. Disabling of the automatic actuation can be safely utilized, without subjecting the fuel cladding to unacceptable temperatures, when the LOFT power decays to 70 kW; this power level permits a maximum delay of 20 minutes following a LOCA for the manual actuation of ECCS

Experiments on injection performance of SMART ECC facility using SWAT

Energy Technology Data Exchange (ETDEWEB)

Cho, Young Il; Cho, Seok; Ko, Yung Joo; Min, Kyoung Ho; Shin, Yong Cheol; Kwon, Tae Soon; Yi, Sung Jae; Lee, Won Jae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

SMART (System-integrated Modular Advanced ReacTor), an advanced integrated PWR is now in the under developing stages by KAERI. Such integral PWR excludes large-size piping of the primary system of conventional PWR and incorporates the SGs into RPV, which means no LBLOCA could occur in SMART. Therefore, the SBLOCA is considered as a major DBA (Design Basis Accident) in SMART and it is mainly analyzed by using TASS/SMR computer code. The TASS/SMR code should be validated using experimental data from both Integral Effect Test and Separate Effect Test facilities. To investigate injection performance of the ECC system, on SET facility, named as SWAT (SMART ECC Water Asymmetric Two-phase choking test facility), has been constructed at KAERI. The SWAT simulates the geometric configurations of the SG-side upper downcomer annulus and ECCSs of those of SMART. It is designed based on the modified linear scaling method with a scaling ratio of 1/5, to preserve the geometrical similarity and minimize gravitational distortion. The purpose of the SWAT tests is to investigate the safety injection performance, such as the ECC bypass in the downcomer and the penetration rate in the core during the SBLOCA, and hence to produce experimental data to validate and the prediction capability of safety analysis codes, TASS/SMR

Guideline on in-service testing (IST) of ECCS for nuclear power stations in Japan

International Nuclear Information System (INIS)

Yamashita, N.; Honjin, M.; Yamazaki, M.; Iwami, H.

2001-01-01

In Japan, METI (Ministry of Economy, Trade and Industry) periodic inspections are conducted every 13 months in accordance with the EUIL (Electric Utility Industry Law) for light water reactors. On the other hand, during operation, many kinds of function tests are conducted in accordance with Technical Specifications or utilities voluntary test procedures. However, these maintenance activities during outages are in other respects considered too costly and more than necessary because of its predetermined maintenance interval and its old-fashioned full scope maintenance menu. In these circumstances, the ASME O and M Codes and Standards, which are applied to nuclear power plants in the United States, came to be one of the issues to be considered among Japanese utilities. This is because the ASME O and M Codes and Standards, which are developed to verify the operational readiness of equipment or systems by condition based maintenance or performance testing without overhauls, will be considered to suggest a rational alternative to our existing maintenance activities. Because there had been no standard for function tests other than the METI inspection procedures in Japan, activities started for the development of Japanese Operation and Maintenance Guideline (hereinafter called the Japanese OM Guideline or the Guideline) for function tests and condition monitoring. The Japanese OM Guideline is not proclaimed for regulatory use, but the long-term objective is to provide a substantial basis to change the current maintenance activities including regulatory inspection. The Guideline is composed of five parts, which are general requirements, pumps, valves, snubbers and ECCS systems. This paper gives a summary of the ECCS part of the Japanese OM Guideline, in particular, focusing on the differences between the Guideline and the ASME O and M Standards, and topics or discussion during their establishment. (author)

Core-power and decay-time limits for disabled automatic-actuation of LOFT ECCS

International Nuclear Information System (INIS)

Hanson, G.H.

1978-01-01

The Emergency Core Cooling System (ECCS) for the LOFT reactor may need to be disabled for modifications or repairs of hardware or instrumentation or for component testing during periods when the reactor system is hot and pressurized, or it may be desirable to enable the ECCS to be disabled without the necessity of cooling down and depressurizing the reactor. A policy involves disabling the automatic-actuation of the LOFT ECCS, but still retaining the manual actuation capability. Disabling of the automatic actuation can be safely utilized, without subjecting the fuel cladding to unacceptable temperatures, when the LOFT power decays to 33 kW; this power level permits a maximum delay of 20 minutes following a LOCA for the manual actuation of ECCS. For the operating power of the L2-2 Experiment, the required decay-periods (with operating periods of 40 and 2000 hours) are about 21 and 389 hours, respectively. With operating periods of 40 and 2000 hours at Core-I full power, the required decay-periods are about 42 and 973 hours, respectively. After these decay periods the automatic actuation of the LOFT ECCS can be disabled assuming a maximum delay of 20 minutes following a LOCA for the manual actuation of ECCS. The automatic and manual lineup of the ECCS may be waived if decay power is less than 11 kW

Two-phase flow dynamics in ECC

International Nuclear Information System (INIS)

Albraaten, P.J.

1981-07-01

The present report summarizes the achievements within the project ''Two-phase Systems and ECC''. The results during 1978 - 1980 are accounted for in brief as they have been documented in earlier reports. The results during the first half of 1981 are accounted for in greater detail. They contain a new model for the Basset force and test runs with this model using the test code RISQUE. Furthermore, test runs have been performed with TRAC-PD2 MOD 1. This code was implemented on Edwards Pipe Blowdown experiment (a standard test case) and UC-Berkeley Reflooding experiment (a non-standard test case.) (Auth.)

Emergency response guide-B ECCS guideline evaluation analyses for N reactor

International Nuclear Information System (INIS)

Chapman, J.C.; Callow, R.A.

1989-07-01

INEL conducted two ECCS analyses for Westinghouse Hanford. Both analyses will assist in the evaluation of proposed changes to the N Reactor Emergency Response Guide-B (ERG-B) Emergency Core System (ECCS) guideline. The analyses were a sensitivity study for reduced-ECCS flow rates and a mechanistically determined confinement steam source for a delayed-ECCS LOCA sequence. The reduced-ECCS sensitivity study established the maximum allowable reduction in ECCS flow as a function of time after core refill for a large break loss-of-coolant accident (LOCA) sequence in the N Reactor. The maximum allowable ECCS flow reduction is defined as the maximum flow reduction for which ECCS continues to provide adequate core cooling. The delayed-ECCS analysis established the liquid and steam break flows and enthalpies during the reflood of a hot core following a delayed ECCS injection LOCA sequence. A simulation of a large, hot leg manifold break with a seven-minute ECCS injection delay was used as a representative LOCA sequence. Both analyses were perform using the RELAP5/MOD2.5 transient computer code. 13 refs., 17 figs., 3 tabs

Application of Interfacial Propagation and Kinking Crack Concept to ECC/Concrete Overlay Repair System

Directory of Open Access Journals (Sweden)

Yaw ChiaHwan

2014-01-01

Full Text Available Research on the application of ultraductile engineered cementitious composite (ECC as overlay in the repair of deteriorated concrete structures is performed in this paper. Also, interfacial crack kinking and trapping mechanism experimentally observed in ECC/concrete overlay repair system are described by comparison of toughness and energy release rate. The mechanism involves cycles of extension, kinking, and arrest of interfacial crack into the overlay. Experimental testing of overlay repair system reveals significant improvements in load carrying capacity and ductility over conventional concrete overlay. The commonly observed overlay system failure mode of delamination or spalling is eliminated when ECC is applied. These failure modes are suppressed when ECC is used as an ideal and durable candidate overlay repair material.

A novel method for estimating soil precompression stress from uniaxial confined compression tests

DEFF Research Database (Denmark)

Lamandé, Mathieu; Schjønning, Per; Labouriau, Rodrigo

2017-01-01

. Stress-strain curves were obtained by performing uniaxial, confined compression tests on undisturbed soil cores for three soil types at three soil water potentials. The new method performed better than the Gompertz fitting method in estimating precompression stress. The values of precompression stress...... obtained from the new method were linearly related to the maximum stress experienced by the soil samples prior to the uniaxial, confined compression test at each soil condition with a slope close to 1. Precompression stress determined with the new method was not related to soil type or dry bulk density......The concept of precompression stress is used for estimating soil strength of relevance to fieldtraffic. It represents the maximum stress experienced by the soil. The most recently developed fitting method to estimate precompression stress (Gompertz) is based on the assumption of an S-shape stress...

Shear behavior of reinforced Engineered Cementitious Composites (ECC) beams

DEFF Research Database (Denmark)

Paegle, Ieva; Fischer, Gregor

2010-01-01

This paper describes an experimental investigation of the shear behavior of beams consisting of steel reinforced Engineered Cementitious Composites (ECC). Based on the strain hardening and multiple cracking behavior of ECC, this study investigates the extent to which ECC can improve the shear...... capacity of beams loaded primarily in shear and if ECC can partially or fully replace the conventional transverse steel reinforcement in beams. However, there is a lack of understanding of how the fibers affect the shear carrying capacity and deformation behavior of structural members if used either...

A study on design of the trip computer for ECCS based on dynamic safety system

International Nuclear Information System (INIS)

Kim, Seog Nam

2000-02-01

The Emergency Core Cooling system in current nuclear power plants typically has a considerable number of complex functions and largely cumbersome operator interfaces. Functions for initiation, switch-over between various phases of operation, interlocks, monitoring, and alarming are usually performed by relay and analog comparator logic which is difficult to maintain and test. To improve problems of an analog based ECC (Emergency Core Cooling) System, the trip computer for ECCS based on Dynamic Safety System is implemented. The Dynamic Safety System (DSS) is a computer based reactor protection system that has fail-safe nature and performs a dynamic self-testing. The most important feature of the DSS is the introduction of test signal that send the system into a tripped state. The test signals are interleaved between the plant signals to produce an output which switches between a tripped and health state. The dynamic operation is a key feature of the failsafe design of the system. In this thesis, a possible implementation of the DSS using PLC is presented for a CANDU reactor. ECC System of the CANDU Reactor is selected as the reference system. The function of the DSS is implemented In PLC with the CONCEPT language. CONCEPT was developed by GROUPE SCHNEIDER as a graphic user interface programming tool for the Quantum PLC. A MMI display for ECCS based on DSS is implemented with LOOKOUT as an object driven programming tool. The Validation test has been performed by S/W Input Simulator as per Validation Test Procedure. The result of the test was checked and displayed on the MMI display. From the test results, it is shown that the DSS based ECC System operates correctly in all conditions

Nondestructive testing of the low-level radioactive waste drums for uni-axial compressive strength and free liquid content

International Nuclear Information System (INIS)

Yu Geping; Chang Mingyu; Wang Yeajeng; Chu, David S.L.; Ju Yihzen

1992-01-01

This paper summarizes the nondestructive test to determine the uni-axial compressive strength and free water content of solidified low level radioactive waste. The uni-axial compressive strength is determined by ultrasonic wave propagation speed, and the results are compared with those of compressive tests. Three methods of detecting the surface free water by ultrasonic testing are established, the ultrasonic wave speed, wave form and pulse height are used to determine the existence and amount of the surface free liquid. Possible difficulties are discussed. (author)

A methodology to investigate size scale effects in crystalline plasticity using uniaxial compression testing

International Nuclear Information System (INIS)

Uchic, Michael D.; Dimiduk, Dennis M.

2005-01-01

A methodology for performing uniaxial compression tests on samples having micron-size dimensions is presented. Sample fabrication is accomplished using focused ion beam milling to create cylindrical samples of uniform cross-section that remain attached to the bulk substrate at one end. Once fabricated, samples are tested in uniaxial compression using a nanoindentation device outfitted with a flat tip, and a stress-strain curve is obtained. The methodology can be used to examine the plastic response of samples of different sizes that are from the same bulk material. In this manner, dimensional size effects at the micron scale can be explored for single crystals, using a readily interpretable test that minimizes imposed stretch and bending gradients. The methodology was applied to a single-crystal Ni superalloy and a transition from bulk-like to size-affected behavior was observed for samples 5 μm in diameter and smaller

An overview of the BWR ECCS strainer blockage issues

International Nuclear Information System (INIS)

Serkiz, A.W.; Marshall, M.L. Jr.; Elliott, R.

1996-01-01

This Paper provides a brief overview of actions taken in the mid 1980s to resolve Unresolved Safety Issue (USI) A-43, open-quotes Containment Emergency Sump Performance,close quotes and their relationship to the BWR strainer blockage issue; the importance of insights gained from the Barseback-2 (a Swedish BWR) incident in 1992 and from ECCS strainer testing and inspections at the Perry nuclear power plant in 1992 and 1993; an analysis of an US BWR/4 with a Mark I containment; an international community sharing of knowledge relevant to ECCS strainer blockage, additional experimental programs; and identification of actions needed to resolve the strainer blockage issue and the status of such efforts

Experiment data report for semiscale Mod-1 test S-04-1 (baseline ECC test)

International Nuclear Information System (INIS)

Crapo, H.S.; Collins, B.L.; Sackett, K.E.

1976-09-01

Recorded test data are presented for Test S-04-1 of the Semiscale Mod-1 Baseline ECC Test Series. This test is among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor system. Test S-04-1 was conducted from an initial cold leg fluid temperature of 542 0 F and an initial pressure of 2,263 psia. A simulated double-ended offset shear cold leg break was used to investigate the system response to a depressurization and reflood transient using system volume scaled coolant injection parameters. System flow was set to achieve a core fluid temperature differential of 66 0 F at a full core power of 1.6 MW. The flow resistance of the intact loop was based on core area scaling. An electrically heated core with a flat radial power profile was used in the pressure vessel to simulate the effects of a nuclear core. During system depressurization, core power was reduced from the initial level of 1.6 MW in such a manner as to simulate the surface heat flux response of nuclear fuel rods until such time that departure from nucleate boiling might occur. Blowdown to the pressure suppression system was accompanied by simulated emergency core cooling injection into both the intact and broken loops. Coolant injection was continued until test termination at 200 seconds after initiation of blowdown

Uniaxial compression tests on diesel contaminated frozen silty soil specimens

International Nuclear Information System (INIS)

Chenaf, D.; Stampli, N.; Bathurst, R.; Chapuis, R.P.

1999-01-01

Results of a uniaxial, unconfined compression test on artificial diesel-contaminated and uncontaminated frozen silty soils are discussed. The testing program involved 59 specimens. The results show that for the same fluid content, diesel contamination reduced the strength of the frozen specimens by increasing the unfrozen water content. For example, in specimens containing 50 per cent diesel oil of the fluid content by weight the maximum strength was reduced by 95 per cent compared to the strength of an uncontaminated specimen. Diesel contamination was also shown to contribute to the slippage between soil particles by acting as a lubricant, thus accelerating the loss of compressive strength.13 refs., 18 figs

ECC delivery to lower plenum under downcomer injection part 2. RELAP5 assessment

International Nuclear Information System (INIS)

Bang, Young Seok; Shin, An Dong; Kim, Hho Jung

2000-01-01

In the present study, the capability of the thermal-hydraulic codes, RELAP5/MOD3.2.2 gamma, in predicting the steam-water interaction and the related ECC delivery to lower plenum under downcomer injection condition during refill phase is evaluated using the experimental data of the UPTF Test 21A. The facility is modeled in detail, and the test condition simulated for code calculations. The calculation result is compared with the applicable measurement data and discussed for the pressure response, ECC bypass behavior, lower plenum delivery, global water mass distribution, and local behavior in downcomer

Experiment data report for semiscale Mod-1 test S-04-2 (baseline ECC test)

International Nuclear Information System (INIS)

Crapo, H.S.; Collins, B.L.; Sackett, K.E.

1976-09-01

Recorded test data are presented for Test S-04-2 of the Semiscale Mod-1 Baseline ECC test series. This test is among Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor system. Test S-04-2 was conducted from an initial cold leg fluid temperature of 542 0 F and an initial pressure of 2,263 psia. A simulated double-ended offset shear cold leg break was used to investigate the system response to a depressurization and reflood transient using emergency core coolant injection parameters based on downcomer volume scaling. System flow was set to achieve a core fluid temperature differential of 66 0 F at a full core power of 1.6 MW. The flow resistance of the intact loop was based on core area scaling. An electrically heated core with a flat radial power profile was used in the pressure vessel to simulate the effects of a nuclear core. During system depressurization, core power was reduced from the initial level of 1.6 MW to simulate the surface heat flux response of nuclear fuel rods until such sime that departure from nucleate boiling might occur. Blowdown to the pressure suppression system was accompanied by simulated emergency core coolant injection into both the intact and broken loops. Coolant injection was continued until test termination at 200 seconds after initiation of blowdown. The purpose of the report is to make available the uninterpreted data from Test S-04-2 for future data analysis and test results reporting activities. The data, presented in the form of graphs in engineering units, have been analyzed only to the extent necessary to assure that they are reasonable and consistent

Experimental and numerical study on mechanical properties of aluminum alloy under uniaxial tensile test

Directory of Open Access Journals (Sweden)

O. Daghfas

2017-01-01

Full Text Available The main objective is to model the behavior of 7075 aluminum alloy and built an experimental database to identify the model parameters. The first part of the paper presents an experimental database on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried in three loading directions relative to the rolling direction, knowing that the fatigue of aircraft structures is traditionally managed based on the assumption of uniaxial loads. From experimental database, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to material. In second part, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening law and evolution law. In third part, a comparison with experimental data shows that behavior model can successfully describe the anisotropy of the Lankford coefficient.

Evaluation of ECC bypass data with a nonlinear constrained MLE technique

International Nuclear Information System (INIS)

Bishop, T.A.; Collier, R.P.; Kurth, R.E.

1980-01-01

Recently, Battelle's Columbus Laboratories have been involved in scale-model tests of emergency core cooling (ECC) systems for hypothesized loss-of-coolant accidents in pressurized water reactors (PWR). These tests are intended to increase our understanding of ECC bypass, which can occur when steam flow from the reactor core causes the emergency coolant to bypass the core and flow directly to the break. One objective of these experiments is the development of a correlation which relates the flow rate of water penetrating to the core to the steam flow rate. This correlation is derived from data obtained from a 2/15 scale model PWR at various ECC water injection rates, subcoolings, pressures, and steam flows. The general form of the correlation being studied is a modification of the correlation first proposed by Wallis. The correlation model is inherently nonlinear and implicit in form, and the model variables are all subject to error. Therefore, the usual nonlinear analysis techniques are inappropriate. A nonlinear constrained maximum-likelihood-estimation technique has been used to obtain estimates of the model parameters, and a Battelle-developed code, NLINMLE, has been used to analyze the data. The application of this technique is illustrated by sample calculations of estimates of the model parameters and their associated confidence intervals for selected experimental data sets. 5 figures, 7 tables

Development of Calculation Algorithm for ECCS Kinematic Shock

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Chan; Yoon, Duk-Joo; Ha, Sang-Jun [KHNP-CRI, Daejeon (Korea, Republic of)

2014-10-15

The void fraction of inverted U-pipes in front of SI(Safety Injection) pumps impact on the pipe system of ECCS(Emergency Core Cooling Systems). This phenomena is called as 'Kinematic Shock'. The purpose of this paper is to achieve the more exactly calculation when the kinematic shock is calculated by simplified equation. The behavior of the void packet of the ECCS pipes is illustrated by the simplified (other name is kinematic shock equation).. The kinematic shock is defined as the depth of total length of void clusters in the pipes of ECCS when the void cluster is continually reached along the part of pipes in vertical direction. In this paper, the simplified equation is evaluated by comparing calculation error each other.]. The more exact methods of calculating the depth of the kinematic shock in ECCS is achieved. The error of kinematic shock calculation is strongly depended on the calculation search gap and the order of Taylor's expansion. From this study, to select the suitable search gap and the suitable calculation order, differential root method, secant method, and Taylor's expansion form are compared one another.

Method and device for controlling ECCS

International Nuclear Information System (INIS)

Ikeda, Takashi; Kataoka, Yoshiyuki; Murase, Michio.

1986-01-01

Purpose: To accomplish reactor cooling without exposing fuel assemblies out of the coolant and also without inducing counter-current flow (CCFL) brake likely to be caused by excess injection of water even in case of malfunction of one system in a loss-of-coolant accident. Method: In a BWR type reactor having more than two independent ECCS, the lower plenum water level is measured and when the lower plenum is full of water, the ECCS are kept in a fully closed state, and reversely when the lower plenum is not full of water, more coolant than the lost quantity of water will be injected into the plenum at a higher pressure than a pressure at which fuel rods just begin to be exposed to the steam phase. The subcool energy of the emergency coolant to be injected is determined by the decay heat of the core and the change rate of a container pressure. However, the quantity of the emergency coolant is controlled such that the subcool energy will always become less than the overheating energy in the core range and the lower plenum range, thus improving safety and enabling the removal of a prior-art ECCS. (Kamimura, M.)

Electronic processes in uniaxially stressed p-type germanium

Energy Technology Data Exchange (ETDEWEB)

Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

1996-02-01

Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

Evaluation of mispositioned ECCS valves

International Nuclear Information System (INIS)

Hill, R.A.; O'Brien, J.F.; McIntire, D.C.; Barlow, R.T.

1977-09-01

In October of 1975, Westinghouse submitted NS-CE-787, dated October 17, 1975, to the Nuclear Regulatory Commission (NRC) and entered into discussions with them concerning the spurious movement of certain motor-operated valves (MOV's) in the Emergency Core Cooling System (ECCS) to a position defeating the ECCS function at a time when this function is required. On November 25, 1975, the discussion turned to the possible movement of a manually controlled, motor-operated valve due to a fault in its electrical circuitry and the NRC staff expressed concerns about other possible failure modes that might lead to such a valve movement. The NRC meeting minutes document these concerns. This report is an item-by-item response to the concerns expressed by the NRC staff at that meeting and incorporates the original electrical fault analysis

Energy-dissipating and self-repairing SMA-ECC composite material system

International Nuclear Information System (INIS)

Li, Xiaopeng; Li, Mo; Song, Gangbing

2015-01-01

Structural component ductility and energy dissipation capacity are crucial factors for achieving reinforced concrete structures more resistant to dynamic loading such as earthquakes. Furthermore, limiting post-event residual damage and deformation allows for immediate re-operation or minimal repairs. These desirable characteristics for structural ‘resilience’, however, present significant challenges due to the brittle nature of concrete, its deformation incompatibility with ductile steel, and the plastic yielding of steel reinforcement. Here, we developed a new composite material system that integrates the unique ductile feature of engineered cementitious composites (ECC) with superelastic shape memory alloy (SMA). In contrast to steel reinforced concrete (RC) and SMA reinforced concrete (SMA-RC), the SMA-ECC beams studied in this research exhibited extraordinary energy dissipation capacity, minimal residual deformation, and full self-recovery of damage under cyclic flexural loading. We found that the tensile strain capacity of ECC, tailored up to 5.5% in this study, allows it to work compatibly with superelastic SMA. Furthermore, the distributed microcracking damage mechanism in ECC is critical for sufficient and reliable recovery of damage upon unloading. This research demonstrates the potential of SMA-ECC for improving resilience of concrete structures under extreme hazard events. (paper)

The statitistical evaluation of the uniaxial compressive strength of the Ruskov andesite

Directory of Open Access Journals (Sweden)

Krepelka František

2002-03-01

Full Text Available The selection of a suitable model of the statistical distribution of the uniaxial compressive strength is discussed in the paper. The uniaxial compressive strength was studied on 180 specimens of the Ruskov andesite. The rate of loading was 1MPa.s-1. The experimental specimens had a prismatic form with a square base; the slightness ratio of specimens was 2:1. Three sets of specimens with a different length of the base edge were studied, namely 50, 30 and 10 mm. The result of the measurement were three sets with 60 values of the uniaxial compressive strength. The basic statistical parameters: the sample mean, the sample standard deviation, the variational interval, the minimum and maximum value, the sample obliqueness coefficient and the sharpness coefficient were evaluated for each collection. Two types of the distribution which can be joined with the real physical fundamentals of the desintegration of rocks ( the normal and the Weibull distribution were tested. The two-parametric Weibull distribution was tested. The basic characteristics of both distributions were evaluated for each set and the accordance of the model distribution with an experimental distribution was tested. The ÷2-test was used for testing. The two-parametric Weibull distribution was selected following the comparison of the test results of both model distributions as a suitable distribution model for the characterization of uniaxial compressive strength of the Ruskov andesite. The two-parametric Weibull distribution showed better results of the goodness-of-fit test. The normal distribution was suitable for two sets; one of the sets showed a negative result of the goodness-of-fit testing. At the uniaxial compressive strength of the Ruskov andesite, a scale effect was registered : the mean value of uniaxial compressive strength decreases with increasing the specimen base edge. This is another argument for using the Weibull distribution as a suitable statistical model of the

Failure analysis based on microvoid growth for sheet metal during uniaxial and biaxial tensile tests

International Nuclear Information System (INIS)

Abbassi, Fethi; Mistou, Sebastien; Zghal, Ali

2013-01-01

Highlights: ► Cruciform specimen designed and biaxial tensile test carried out. ► Stereo Correlation Image technique is used for 3D full-filed measurements. ► SEM fractography analysis is used to explain the fracture mechanism. ► Constitutive modeling of the necking phenomenon was developed using GTN model. - Abstract: The aim of the presented investigations is to perform an analysis of fracture and instability during simple and complex load testing by addressing the influence of ductile damage evolution in necking processes. In this context, an improved experimental methodology was developed and successfully used to evaluate localization of deformation during uniaxial and biaxial tensile tests. The biaxial tensile tests are carried out using cruciform specimen loaded using a biaxial testing machine. In this experimental investigation, Stereo-Image Correlation technique has is used to produce the heterogeneous deformations map within the specimen surface. Scanning electron microscope is used to evaluate the fracture mechanism and the micro-voids growth. A finite element model of uniaxial and biaxial tensile tests are developed, where a ductile damage model Gurson–Tvergaard–Needleman (GTN) is used to describe material deformation involving damage evolution. Comparison between the experimental and the simulation results show the accuracy of the finite element model to predict the instability phenomenon. The advanced measurement techniques contribute to understand better the ductile fracture mechanism

Preliminary Evaluation Methodology of ECCS Performance for Design Basis LOCA Redefinition

International Nuclear Information System (INIS)

Kang, Dong Gu; Ahn, Seung Hoon; Seul, Kwang Won

2010-01-01

To improve their existing regulations, the USNRC has made efforts to develop the risk-informed and performance-based regulation (RIPBR) approaches. As a part of these efforts, the rule revision of 10CFR50.46 (ECCS Acceptance Criteria) is underway, considering some options for 4 categories of spectrum of break sizes, ECCS functional reliability, ECCS evaluation model, and ECCS acceptance criteria. Since the potential for safety benefits and unnecessary burden reduction from design basis LOCA redefinition is high relative to other options, the USNRC is proceeding with the rulemaking for design basis LOCA redefinition. An instantaneous break with a flow rate equivalent to a double ended guillotine break (DEGB) of the largest primary piping system in the plant is widely recognized as an extremely unlikely event, while redefinition of design basis LOCA can affect the existing regulatory practices and approaches. In this study, the status of the design basis LOCA redefinition and OECD/NEA SMAP (Safety Margin Action Plan) methodology are introduced. Preliminary evaluation methodology of ECCS performance for LOCA is developed and discussed for design basis LOCA redefinition

The prevalence and risks of early childhood caries (ECC) in Toronto, Canada.

Science.gov (United States)

Al-Jewair, Thikriat S; Leake, James L

2010-10-14

To determine the prevalence and risks of early childhood caries (ECC) among children less than 71 months of age in Toronto, Canada, and to evaluate the association between parental/caregiver depression and ECC. A secondary analysis of data previously collected by the Toronto Public Health as part of the 2003 Toronto Perinatal and Child Health Survey was performed. The 90-item survey was conducted over the telephone to 1,000 families with children from zero years (birth) to six years of age. Parents/caregivers were asked about factors related to the development and health of their children. For this study, only children younger than six years of age (less than 71 months) were included (n=833). The primary outcome of interest was self-reported and measured by the response to the question of whether a physician/dentist had ever told the parent/caregiver his/her child had ECC. The prevalence of ECC was 4.7 percent (37 of 791 children). The child's age, his/her history of dental visits, teeth brushing, the use of fluoridated toothpaste, the parent's/caregiver's depressive tendencies, the language spoken at home, and the household annual income were all significant in the bivariate analysis. Multiple logistic regression identified four factors associated with ECC: the child's age (being three years of age or older), having at least one parent/caregiver with depression, not speaking English at home, and having an annual household income less than $40,000 in Canadian dollars (CAD). While a child's age, home language, and household income are known risks for ECC, the finding that parental/caregiver depression may be related to ECC is new. Multiple risk factors are involved in the development of early childhood caries. Of particular importance are demographic (e.g., child's age), social (e.g., annual household income), and psychosocial factors (e.g., parental/caregiver depression) that are indirectly linked to ECC. More attention needs to be placed on understanding the role

On the identifiability of the Hill-1948 model with one uniaxial tensile test

Science.gov (United States)

Bertin, Morgan; Hild, François; Roux, Stéphane

2017-06-01

A uniaxial experiment is performed on an ultra-thin specimen made of 17-7 precipitation hardened stainless steel. An anti-wrinkling setup allows for the characterization of the mechanical behavior with Integrated Digital Image Correlation (IDIC). The result shows that a single uniaxial experiment investigated via IDIC possesses enough data (and even more) to characterize a complete anisotropic elastoplastic model.

Holistic care patient with Early Childhood Caries (ECC: A case report

Directory of Open Access Journals (Sweden)

Intan Maulani

2016-06-01

Full Text Available Early Childhood Caries (ECC is a specific form of severe dental caries that affects infants and young children. ECC progresses rapidly in those who are at high risk, and often goes untreated. Children experiencing caries as infants or toddlers have a much greater probability of subsequent caries in both primary and permanent dentitions. This case showed management holistic care for children with ECC.A five year old boy patient accompanied with her parents were reported to the Pedodontic Clinic Padjadjaran University Dental Hospital with a chief complaint of decayed upper anterior teeth and pain in the molar teeth. Clinical examinations found dental caries almost all teeth in the maxilla and mandible. Based on panoramic radiograph, treatments that can be done are strip crown glass ionomer restorations, pulp treatments, extractions and fixed space maintainer. Patients diagnosed with severe ECC, patient and parents described on this type of caries. During treatment the patient was given oral hygiene instruction and recommend daily use of tooth mouse. After all treatment were completed, fluoride topical, and fissure sealants, recall check up after three months was scheduled. Holistic care needed in handling children with ECC.

Study of Impact Damage in PVA-ECC Beam under Low-Velocity Impact Loading Using Piezoceramic Transducers and PVDF Thin-Film Transducers.

Science.gov (United States)

Qi, Baoxin; Kong, Qingzhao; Qian, Hui; Patil, Devendra; Lim, Ing; Li, Mo; Liu, Dong; Song, Gangbing

2018-02-24

Compared to conventional concrete, polyvinyl alcohol fiber reinforced engineering cementitious composite (PVA-ECC) offers high-strength, ductility, formability, and excellent fatigue resistance. However, impact-induced structural damage is a major concern and has not been previously characterized in PVA-ECC structures. We investigate the damage of PVA-ECC beams under low-velocity impact loading. A series of ball-drop impact tests were performed at different drop weights and heights to simulate various impact energies. The impact results of PVA-ECC beams were compared with mortar beams. A combination of polyvinylidene fluoride (PVDF) thin-film sensors and piezoceramic-based smart aggregate were used for impact monitoring, which included impact initiation and crack evolution. Short-time Fourier transform (STFT) of the signal received by PVDF thin-film sensors was performed to identify impact events, while active-sensing approach was utilized to detect impact-induced crack evolution by the attenuation of a propagated guided wave. Wavelet packet-based energy analysis was performed to quantify failure development under repeated impact tests.

A LOCA analysis for AHWR caused by ECCS header rupture

International Nuclear Information System (INIS)

Chatterjee, B.; Gawai, Amol; Gupta, S.K.; Kushwaha, H.S.

2000-01-01

Loss of coolant accident (LOCA) analyses for the proposed 750 MWth Advanced Heavy Water Reactor (AHWR), initiated by the rupture of 8 inch NB ECCS header has been carried out. This paper narrates the description of AHWR and associated ECCS, postulated scenario with which the analyses is carried out, results, discussion and conclusion

Experimental investigation of the strength and failure behavior of layered sandstone under uniaxial compression and Brazilian testing

Science.gov (United States)

Yin, Peng-Fei; Yang, Sheng-Qi

2018-05-01

As a typical inherently anisotropic rock, layered sandstones can differ from each other in several aspects, including grain size, type of material, type of cementation, and degree of compaction. An experimental study is essential to obtain and convictive evidence to characterize the mechanical behavior of such rock. In this paper, the mechanical behavior of a layered sandstone from Xuzhou, China, is investigated under uniaxial compression and Brazilian test conditions. The loading tests are conducted on 7 sets of bedding inclinations, which are defined as the angle between the bedding plane and horizontal direction. The uniaxial compression strength (UCS) and elastic modulus values show an undulatory variation when the bedding inclination increases. The overall trend of the UCS and elastic modulus values with bedding inclination is decreasing. The BTS value decreases with respect to the bedding inclination and the overall trend of it is approximating a linear variation. The 3D digital high-speed camera images reveal that the failure and fracture of a specimen are related to the surface deformation. Layered sandstone tested under uniaxial compression does not show a typical failure mode, although shear slip along the bedding plane occurs at high bedding inclinations. Strain gauge readings during the Brazilian tests indicate that the normal stress on the bedding plane transforms from compression to tension as the bedding inclination increases. The stress parallel to the bedding plane in a rock material transforms from tension to compression and agrees well with the fracture patterns; "central fractures" occur at bedding inclinations of 0°-75°, "layer activation" occurs at high bedding inclinations of 75°-90°, and a combination of the two occurs at 75°.

Is 300 Seconds ACT Safe and Efficient during MiECC Procedures?

Science.gov (United States)

Bauer, Adrian; Hausmann, Harald; Schaarschmidt, Jan; Szlapka, Michal; Scharpenberg, Martin; Eberle, Thomas; Hasenkam, J Michael

2017-12-31

 The recommended minimum activated clotting time (ACT) level for cardiopulmonary bypass (CPB) of 480 seconds originated from investigations with bubble oxygenators and uncoated extracorporeal circulation (ECC) systems. Modern minimal invasive ECC (MiECC) systems are completely closed circuits containing a membrane oxygenator and a tip-to-tip surface coating. We hypothesized that surface coating and the "closed-loop" design allow the MiECC to safely run with lower ACT levels and that an ACT level of 300 seconds can be safely applied without thromboembolic complications. The aim of this study was to investigate the potential risks during application of reduced heparin levels in patients undergoing coronary surgery.  In this study, 68 patients undergoing coronary artery bypass grafting with MiECC were randomized to either the study group with an ACT target of 300 seconds or the control group with an ACT of 450 seconds. All other factors of MiECC remained unchanged.  The study group received significantly less heparin and protamine (heparin [international units] median [min-max], Red_AC: 32,800 [23,000-51,500] vs. Full_AC: 50,000 [35,000-65,000] p  ACT in the study group was significantly lower at the start of MiECC (mean ± standard deviation: study group 400 ± 112 vs. control group 633 ± 177; p  ACT levels were: study group 344 ± 60 versus control group 506 ± 80. In both groups, the values of the endogenous thrombin potential (ETP) decreased simultaneously. None of the study participants experienced thromboembolic complications.  Since no evidence of increased thrombin formation (ETP) was found from a laboratory standpoint, we concluded that the use of MiECC with a reduced anticoagulation strategy seems possible. This alternative anticoagulation strategy leads to significant reduction in dosages of both heparin and protamine. We can confidently move forward with investigating this anticoagulation concept. However, to

ECC cusp analysis

Energy Technology Data Exchange (ETDEWEB)

Pregliasco, R.G. (Centro Atomico Bariloche and CONICET, S.C. de Bariloche (Argentina)); Garibotti, C.R. (Centro Atomico Bariloche and CONICET, S.C. de Bariloche (Argentina)); Barrachina, R. (Centro Atomico Bariloche and CONICET, S.C. de Bariloche (Argentina))

1994-03-01

We measured the ionization double differential cross section for the H[sup +][yields]He 100 keV collision at the proximities of the ECC cusp and all around 0 . We propose an angular function expansion and a procedure for data analysis. We demonstrate that, in this way, the difficulties and shortcomings presented in the standard data processing are overcome. In our experimental results we distinguish the presence of characteristic shapes for the ionization depending on whether the module of the electron velocity is greater or smaller than the projectile velocity. (orig.)

Fracture assessment of shallow-flaw cruciform beams tested under uniaxial and biaxial loading conditions

International Nuclear Information System (INIS)

Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

1999-01-01

A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate with the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states. (orig.)

Uniaxial ratcheting behavior of Zircaloy-4 tubes at room temperature

International Nuclear Information System (INIS)

Wen, Mingjian; Li, Hua; Yu, Dunji; Chen, Gang; Chen, Xu

2013-01-01

In this study, a series of uniaxial tensile, strain cycling and uniaxial ratcheting tests were conducted at room temperature on Zircaloy-4 (Zr-4) tubes used as nuclear fuel cladding in Pressurized Water Reactors (PWRs) for the purpose to investigate the uniaxial ratcheting behavior of Zr-4 and the factors which may influence it. The experimental results show that at room temperature this material features cyclic softening remarkably within the strain range of 1.6%, and former cycling under larger strain amplitude cannot retard cyclic softening of later cycling under lower strain amplitude. Uniaxial ratcheting strain accumulates in the direction of mean stress, and the ratcheting stain level is larger under tensile mean stress than that under compressive mean stress. Uniaxial ratcheting strain level increases with the increase of mean stress and stress amplitude, and decreases with the increase of loading rate. The sequence of loading rate appears to have no effects on the final ratcheting strain accumulation. Loading history has great influence on the uniaxial ratcheting behavior. Lower stress level after loading history with higher stress level leads to the shakedown of ratcheting. Higher loading rate after loading history with lower loading rate brings down the ratcheting strain rate. Uniaxial ratcheting behavior is sensitive to compressive pre-strain, and the decay rate of the ratcheting strain rate is slowed down by pre-compression

The JAERI code system for evaluation of BWR ECCS performance

International Nuclear Information System (INIS)

Kohsaka, Atsuo; Akimoto, Masayuki; Asahi, Yoshiro; Abe, Kiyoharu; Muramatsu, Ken; Araya, Fumimasa; Sato, Kazuo

1982-12-01

Development of respective computer code system of BWR and PWR for evaluation of ECCS has been conducted since 1973 considering the differences of the reactor cooling system, core structure and ECCS. The first version of the BWR code system, of which developmental work started earlier than that of the PWR, has been completed. The BWR code system is designed to provide computational tools to analyze all phases of LOCAs and to evaluate the performance of the ECCS including an ''Evaluation Model (EM)'' feature in compliance with the requirements of the current Japanese Evaluation Guideline of ECCS. The BWR code system could be used for licensing purpose, i.e. for ECCS performance evaluation or audit calculations to cross-examine the methods and results of applicants or vendors. The BWR code system presented in this report comprises several computer codes, each of which analyzes a particular phase of a LOCA or a system blowdown depending on a range of LOCAs, i.e. large and small breaks in a variety of locations in the reactor system. The system includes ALARM-B1, HYDY-B1 and THYDE-B1 for analysis of the system blowdown for various break sizes, THYDE-B-REFLOOD for analysis of the reflood phase and SCORCH-B2 for the calculation of the fuel assembl hot plane temperature. When the multiple codes are used to analyze a broad range of LOCA as stated above, it is very important to evaluate the adequacy and consistency between the codes used to cover an entire break spectrum. The system consistency together with the system performance are discussed for a large commercial BWR. (author)

Simultaneous algae-polluted water treatment and electricity generation using a biocathode-coupled electrocoagulation cell (bio-ECC).

Science.gov (United States)

Dong, Yue; Qu, Youpeng; Li, Chao; Han, Xiaoyu; Ambuchi, John J; Liu, Junfeng; Yu, Yanling; Feng, Yujie

2017-10-15

How to utilize electrocoagulation (EC) technology for algae-polluted water treatment in an energy-efficient manner remains a critical challenge for its widespread application. Herein, a novel biocathode-coupled electrocoagulation cell (bio-ECC) with sacrificial iron anode and nitrifying biocathode was developed. Under different solution conductivities (2.33±0.25mScm -1 and 4.94±0.55mScm -1 ), the bio-ECC achieved almost complete removal of algae cells. The maximum power densities of 8.41 and 11.33Wm -3 at corresponding current densities of 48.03Am -3 and 66.26Am -3 were obtained, with the positive energy balance of 4.52 and 7.44Wm -3 . In addition, the bio-ECC exhibited excellent NH 4 + -N removal performance with the nitrogen removal rates of 7.28mgL -1 h -1 and 6.77mgL -1 h -1 in cathode chamber, indicating the superiority of bio-ECC in NH 4 + -N removal. Pyrosequencing revealed that nitrifiers including Nitrospira, Nitrobacter, Nitrosococcus, and Nitrosomonas were enriched in biocathode. The removal mechanisms of algae in anode chamber were also explored by AFM and SEM-EDX tests. These results provide a proof-of-concept study of transferring energy-intensive EC process into an energy-neutral process with high-efficiency algae removal and electricity recovery. Copyright © 2017. Published by Elsevier B.V.

Measurement and analysis of the ECC cusp structure

Energy Technology Data Exchange (ETDEWEB)

Pregliasco, R.G.; Garibotti, C.R.; Barrachina, R.O. (Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche)

1994-03-28

We measured the electron capture to the continuum (ECC) peak in the ionization of He atoms by the collision of 50, 100 and 200 keV H[sup +] and 100 keV amu[sup -1]He[sup 2+]. We exhaustively scanned the double differential cross section between the angles -1.5[sup o] to 10[sup o] and within the velocities (1 [+-] 0.15)[upsilon][sub i] where [upsilon][sub i] is the impact velocity. We propose a new method for analysing the ECC structure which is independent of the spectrometer transmission function modellization and enables a direct comparison with the available theories. Furthermore, we distinguish two regimes for the ionization process, depending on whether the electron velocity is larger or smaller than the projectile velocity. (Author).

Noise-based Stego-ECC

Directory of Open Access Journals (Sweden)

Rahardjo Budi

2014-03-01

Full Text Available A novel method of inserting noise into stream of ciphered text is proposed. The goal of inserting noise is to increase the level of uncertainty, thus making it harder for an attacker to detect data and noise. This form of steganography is implemented using Elliptic Curve Cryptography (ECC. The process of embedding the noise to the message in the encryption process and removing the noise from the message in the decryption process is proposed in this work by modifying ElGamal to allow auto detection of data and noise.

Quorum sensing in the plant pathogen Erwinia carotovora subsp. carotovora: the role of expR(Ecc).

Science.gov (United States)

Andersson, R A; Eriksson, A R; Heikinheimo, R; Mäe, A; Pirhonen, M; Kõiv, V; Hyytiäinen, H; Tuikkala, A; Palva, E T

2000-04-01

The production of the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). OHHL is synthesized by the product of the expI/carI gene. Linked to expI we found a gene encoding a putative transcriptional regulator of the LuxR-family. This gene, expR(Ecc), is transcribed convergently to the expI gene and the two open reading frames are partially overlapping. The ExpR(Ecc) protein showed extensive amino acid sequence similarity to the repressor EsaR from Pantoea stewartii subsp. stewartii (formerly Erwinia stewartii subsp. stewartii) and to the ExpR(Ech) protein of Erwinia chrysanthemi. Inactivation of the E. carotovora subsp. carotovora expR(Ecc) gene caused no decrease in virulence or production of virulence determinants in vitro. In contrast, there was a slight increase in the maceration capacity of the mutant strain. The effects of ExpR(Ecc) were probably mediated by changes in OHHL levels. Inactivation of expR(Ecc) resulted in increased OHHL levels during early logarithmic growth. In addition, overexpression of expR(Ecc) caused a clear decrease in the production of virulence determinants and part of this effect was likely to be caused by OHHL binding to ExpR(Ecc). ExpR(Ecc) did not appear to exhibit transcriptional regulation of expI, but the effect on OHHL was apparently due to other mechanisms.

Application of Engineered Cementitious Composites (ECC) in modular floor panels

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor; Jönsson, Jeppe

2008-01-01

This paper describes the design, manufacturing, and structural behavior of a prefabricated floor panel consisting of a modular assembly of a thin-walled ECC slab and steel truss girders. The features of this composite structure include light weight, the modular manufacturing process...... concept introduced in this paper aims at improvements in the manufacturing process of the panels by casting the ECC slab separately and subsequently joining it with the steel trusses. The focus of this paper is on design and manufacturing of a prototype modular panel and on its structural behavior under...

On the energy shift the ECC cusp. Does the shift really exist?

International Nuclear Information System (INIS)

Sarkadi, L.; Barrachina, R.O.

2004-01-01

The cusplike 'electron capture to the continuum' (ECC) peak appearing in the spectrum of the forward emitted electrons in ion-atom collisions are generally thought to be a divergence. Recently Shah et al., however, claimed that 'the ECC cusp is indeed a cusp, and not a divergence smoothed by the experiment'. These authors measured the ECC cusp for collisions of 10- and 20-keV protons with H 2 and He, and found that the peak was shifted to lower velocity than its expected position. We also carried out CTMC calculations (for the case of 20-keV protons on He) by which we demonstrated that the shift really exists but its value depends on the angular window of the electron detection. (K.A.)

Metallographic examinations of Type 304 stainless steel (heat 9T2796) tested in high-temperature uniaxial and multiaxial experiments

Energy Technology Data Exchange (ETDEWEB)

Swindeman, R.W.; Houck, C.W.

1984-03-01

The results obtained from a number of metallographic examinations of Type 304 stainless steel specimens were compiled. Samples were obtained from uniaxial and multiaxial tests covering a very broad span of temperatures and times. Special emphasis was on the identification of failure modes, cracking patterns, grain distortion, and grain-boundary microstructures. Uniaxial specimens exhibited the following sequence of failure modes with increasing temperature and time: ductile plastic tearing, ductile plastic shear, wedge cracking, and microvoid cracking. Over most of the temperature range examined (482 to 871/sup 0/C), M/sub 23/C/sub 6/ precipitated on grain boundaries at long times. Sigma phase and possibly ferrite were often present in the stressed areas at temperatures as low as 482/sup 0/C (900/sup 0/F). These metallurgical features promoted a severe loss in creep ductility at long times and low temperatures. Most multiaxial tests were performed under conditions that promoted wedge cracking. Stress gradients also favored surface crack initiation rather than bulk damage. Testing times for multiaxial tests were less than 10,000 h; hence, there was insufficient time for the development of embrittling features such as microvoids, sigma, and ferrite. Long-time multiaxial tests to failure are recommended.

ECC2K-130 on NVIDIA GPUs

NARCIS (Netherlands)

Bernstein, D.J.; Chen, H.-C.; Cheng, C.M.; Lange, T.; Niederhagen, R.F.; Schwabe, P.; Yang, B.Y.

2012-01-01

[Updated version of paper at Indocrypt 2010] A major cryptanalytic computation is currently underway on multiple platforms, including standard CPUs, FPGAs, PlayStations and GPUs, to break the Certicom ECC2K-130 challenge. This challenge is to compute an elliptic-curve discrete logarithm on a Koblitz

ECC2K-130 on NVIDIA GPUs

NARCIS (Netherlands)

Bernstein, D.J.; Chen, H.-C.; Cheng, C.M.; Lange, T.; Niederhagen, R.F.; Schwabe, P.; Yang, B.Y.; Gong, G.; Gupta, K.C.

2010-01-01

A major cryptanalytic computation is currently underway on multiple platforms, including standard CPUs, FPGAs, PlayStations and Graphics Processing Units (GPUs), to break the Certicom ECC2K-130 challenge. This challenge is to compute an elliptic-curve discrete logarithm on a Koblitz curve over $\\rm

A study on stress analysis of small punch-creep test and its experimental correlations with uniaxial-creep test

International Nuclear Information System (INIS)

Lee, Song In; Baek, Seoung Se; Kwon, Il Hyun; Yu, Hyo Sun

2002-01-01

A basic research was performed to ensure the usefulness of Small Punch-creep(SP-creep) test for residual life evaluation of heat resistant components effectively. This paper presents analytical results of initial stress and strain distributions in SP specimen caused by constant loading for SP-creep test and its experimental correlations with uniaxial creep(Ten-creep) test on 9CrlMoVNb steel. It was shown that the initial maximum equivalent stress, σ eq · max from FE analysis was correlated with steady-state equivalent creep strain rate, ε qf-ss , rupture time, t r , activation energy, Q and Larson-Miller parameter, LMP during SP-creep deformation. The simple correlation laws, σ SP - σ TEN , P SP -σ TEN and Q SP -Q TEN adopted to established a quantitative correlation between SP-creep and Ten-creep test data. Especially, the activation energy obtained from SP-creep test is linearly related to that from Ten-creep test at 650 deg. C as follows : Q SP-P =1.37 Q TEN , Q SP-σ =1.53 Q TEN

Preparation and evaluation of 68Ga-ECC as a PET renal imaging agent

International Nuclear Information System (INIS)

Mizaei, Alireza; Jaililan, Amir Reza; Mazidi, Mohammad; Aghanejad, Ayuob; Yousefnia, Hassan; Shabani, Gholamli; Ardaneh, Khosro; Geramifar, Patham; Beiki, Davood

2015-01-01

Development of a gallium-68-labeled renal tracer can be a good substitute for Tc-99m, a known SPECT tracer. In this study, effort was made to develop 68 Ga-ethylenecysteamine cysteine ( 68 Ga-ECC). Ga-ECC was prepared using generator-based 68 GaCl3 and ethylenecysteamine cysteine (ECC) at optimized conditions. Stability of the complex was checked in human serum followed by partition coefficient determination of the tracer. The biodistribution of the tracer in rats was studied using tissue counting and PET/CT imaging up to 120 min. Ga-ECC was prepared at optimized conditions in 15 min at 90 °C (radiochemical purity ≈97 ± 0.88 % ITLC, >99 % HPLC, specific activity: 210 ± 5 GBq/mM). 68 Ga-ECC was a water-soluble complex based on partition coefficient data (log P; −1.378) and was stable in the presence of human serum for 2 h at 37 °C. The biodistribution of the tracer demonstrated high kidney excretion of the tracer in 10–20 min. The SUV max ratios of the liver to left kidney were 0.38 and 0.39 for 30 and 90 min, respectively, indicating high kidney uptake. Initial biodistribution results showed significant kidney and urinary excretion of the tracer comparable to that of the homologous 99m Tc compound. The complex could be a possible PET kidney imaging agent with a fast imaging time

Comprehensive Oral Health Care to Reduce the Incidence of Severe Early Childhood Caries (s-ECC) in Urban China.

Science.gov (United States)

Si, Yan; Guo, Yan; Yuan, Chao; Xu, Tao; Zheng, Shu Guo

2016-03-01

To explore the effectiveness of comprehensive oral health care to reduce the caries incidence for children with severe early childhood caries (s-ECC) in an urban area in China. A total of 357 children aged 3 to 4 years old and diagnosed with s-ECC were recruited in this randomised controlled, single-blinded clinical trial for 1 year. Children of two different kindergarten classes were enrolled in this study and randomly divided into a test group (205 children) and a control group (152 children). The test group received comprehensive oral health care, which included: oral health examination, oral health education, topical fluoride application and dental treatment, and the children in the control group only received the oral health examination. The evaluation of the oral health questionnaire for parents was also performed. An evaluation was carried out at the time of recruitment and 1 year later to explore the effectiveness of the comprehensive oral health care model. The differences in decayed teeth (dt), decayed tooth surfaces (ds), filled teeth (ft), filled tooth surfaces (fs) and the ratio of ft /(dt + ft) between the two groups were statistically significant (P comprehensive oral health care program reduces and prevents caries amongst children with s-ECC.

Lightweight ECC based RFID authentication integrated with an ID verifier transfer protocol.

Science.gov (United States)

He, Debiao; Kumar, Neeraj; Chilamkurti, Naveen; Lee, Jong-Hyouk

2014-10-01

The radio frequency identification (RFID) technology has been widely adopted and being deployed as a dominant identification technology in a health care domain such as medical information authentication, patient tracking, blood transfusion medicine, etc. With more and more stringent security and privacy requirements to RFID based authentication schemes, elliptic curve cryptography (ECC) based RFID authentication schemes have been proposed to meet the requirements. However, many recently published ECC based RFID authentication schemes have serious security weaknesses. In this paper, we propose a new ECC based RFID authentication integrated with an ID verifier transfer protocol that overcomes the weaknesses of the existing schemes. A comprehensive security analysis has been conducted to show strong security properties that are provided from the proposed authentication scheme. Moreover, the performance of the proposed authentication scheme is analyzed in terms of computational cost, communicational cost, and storage requirement.

Uniaxial tension test on Rubber at constant true strain rate

Directory of Open Access Journals (Sweden)

Sourne H.L.

2012-08-01

Full Text Available Elastomers are widely used for damping parts in different industrial contexts because of their remarkable dissipation properties. Indeed, they can undergo severe mechanical loading conditions, i.e., high strain rates and large strains. Nevertheless, the mechanical response of these materials can vary from purely rubber-like to glassy depending on the strain rate undergone. Classically, uniaxial tension tests are made in order to find a relation between the stress and the strain in the material at various strain rates. However, even if the strain rate is searched to be constant, it is the nominal strain rate that is considered. Here we develop a test at constant true strain rate, i.e. the strain rate that is experienced by the material. In order to do such a test, the displacement imposed by the machine is an exponential function of time. This test has been performed with a high speed hydraulic machine for strain rates between 0.01/s and 100/s. A specific specimen has been designed, yielding a uniform strain field (and so a uniform stress field. Furthermore, an instrumented aluminum bar has been used to take into account dynamic effects in the measurement of the applied force. A high speed camera enables the determination of strain in the sample using point tracking technique. Using this method, the stress-strain curve of a rubber-like material during a loading-unloading cycle has been determined, up to a stretch ratio λ = 2.5. The influence of the true strain rate both on stiffness and on dissipation of the material is then discussed.

Gonioscopic changes in conventional ECCE vs manual SICS: A comparative study

Directory of Open Access Journals (Sweden)

Surya Joseph, Sundararajan D, Rajvin Samuel Ponraj, Srinivasan M, Veluchamy

2014-04-01

Full Text Available The aim of the study is to observe and compare the Gonioscopic changes in the angle of the anterior chamber of the eye after surgeries namely; Conventional Extra capsular cataract extraction (ECCE with Posterior chamber Intraocular lens (PC IOL implantation, Manual Small incision Cataract Surgery with PCIOL implantation. The clinical study was undertaken after Institutional Ethical committee clearance, securing the inform consent, total number of 100 patients were enrolled in the study. 50 ECCE; 50 SICS consisting of 57 Males and 43 Females aged between 40 – 80yrs who were admitted and operated for Cataract at Meenakshi Medical college Hospital & Research institute. The following parameters are studied: Gonioscopic changes in the angle, namely the PAS formation in the quadrants, pigment dispersion in each of the methods. After this study, we arrive to a conclusion that complications in the angle of anterior chamber occur mostly in Conventional with insignificant change in manual SICS. So manual Small incision Cataract Surgery with PCIOL implantation is preferable over Conventional ECCE with PCIOL implantation.

Investigation of the Failure Mechanism of HTPB/AP/Al Propellant by In-situ Uniaxial Tensile Experimentation in SEM

NARCIS (Netherlands)

Ramshorst, M.C.J. van; Benedetto, G.L. di; Duvalois, W.; Hooijmeijer, P.A.; Heijden, A.E.D.M. van der

2016-01-01

The failure mechanism of a propellant consisting of hydroxyl terminated poly-butadiene filled with ammonium perchlorate and aluminum (HTPB/AP/Al) was determined by performing in-situ uniaxial tensile tests in a scanning electron microscope (SEM). The experimental test plan contained uniaxial tensile

Ion-beam texturing of uniaxially textured Ni films

International Nuclear Information System (INIS)

Park, S.J.; Norton, D.P.; Selvamanickam, Venkat

2005-01-01

The formation of biaxial texture in uniaxially textured Ni thin films via Ar-ion irradiation is reported. The ion-beam irradiation was not simultaneous with deposition. Instead, the ion beam irradiates the uniaxially textured film surface with no impinging deposition flux, which differs from conventional ion-beam-assisted deposition. The uniaxial texture is established via a nonion beam process, with the in-plane texture imposed on the uniaxial film via ion beam bombardment. Within this sequential ion beam texturing method, grain alignment is driven by selective etching and grain overgrowth

LOFT ECC Pitot Tube and Thermocouple Rake Penetration thermal analysis

International Nuclear Information System (INIS)

Tolan, B.J.

1977-01-01

A thermal analysis of the LOFT ECC Pitot Tube and Thermocouple Rake Penetration was performed using COUPLE, a two-dimensional finite element computer code. Four transients which conservatively cover all transients the rake will be exposed to were included in this analysis in order to comply with the ASME Code Section III requirements. The transients conservatively cover hot and cold leg operation, and nuclear and nonnuclear operation. The four transients include the LOCE with ECC injection transient, the single control rod drop transient, the scram transient, and the heatup with 0 to 100% load change transient. Temperature distributions in the rake were obtained for each of the four transients and several plots of node temperatures vs. time are given

A study of ECC water bypass reduction technology for an improvement of core cooling capability

International Nuclear Information System (INIS)

Song, C. G.; Kwon, T. S.; Yun, B. J.

2006-02-01

The research for the reduction of ECC water bypass fraction was mainly performed to develop the flow mechanisms that ECC water can penetrate more effectively into a lower downcomer. Evaluation were carried out for the effect of major parameters on the bypass of ECC water in the downcomer with DVI. The following various physical models were derived for the reduction of the bypass fraction of ECC water: models of changing DVI injection angle, models of rearranging relative angles of DVI nozzles, model of grooved-and-subchannel type core barrel, model of dual core barrel. CFD analysis and MARS design verification were performed for the derived models as a first step performance estimation. Through out air-water verification experiments, quantitative evaluation were performed for each model, and three most efficient models were suggested. Examination were carried out for the requirement of structural modification and the change in structural integrity due to the adoption of one of the schemes

Preparation and evaluation of {sup 68}Ga-ECC as a PET renal imaging agent

Energy Technology Data Exchange (ETDEWEB)

Mizaei, Alireza; Jaililan, Amir Reza; Mazidi, Mohammad; Aghanejad, Ayuob; Yousefnia, Hassan; Shabani, Gholamli; Ardaneh, Khosro [Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Geramifar, Patham; Beiki, Davood [Research Center for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2015-09-15

Development of a gallium-68-labeled renal tracer can be a good substitute for Tc-99m, a known SPECT tracer. In this study, effort was made to develop {sup 68}Ga-ethylenecysteamine cysteine ({sup 68}Ga-ECC). Ga-ECC was prepared using generator-based {sup 68}GaCl3 and ethylenecysteamine cysteine (ECC) at optimized conditions. Stability of the complex was checked in human serum followed by partition coefficient determination of the tracer. The biodistribution of the tracer in rats was studied using tissue counting and PET/CT imaging up to 120 min. Ga-ECC was prepared at optimized conditions in 15 min at 90 °C (radiochemical purity ≈97 ± 0.88 % ITLC, >99 % HPLC, specific activity: 210 ± 5 GBq/mM). {sup 68}Ga-ECC was a water-soluble complex based on partition coefficient data (log P; −1.378) and was stable in the presence of human serum for 2 h at 37 °C. The biodistribution of the tracer demonstrated high kidney excretion of the tracer in 10–20 min. The SUV{sub max} ratios of the liver to left kidney were 0.38 and 0.39 for 30 and 90 min, respectively, indicating high kidney uptake. Initial biodistribution results showed significant kidney and urinary excretion of the tracer comparable to that of the homologous {sup 99m}Tc compound. The complex could be a possible PET kidney imaging agent with a fast imaging time.

Multi-dimensional analysis of the ECC behavior in the UPI plant Kori Unit 1

International Nuclear Information System (INIS)

Bae, Sungwon; Chung, Bub-Dong; Bang, Young Seok

2008-01-01

A multi-dimensional transient analysis during the LBLOCA of the Kori Unit 1 has been performed by using the MARS code. Based on 1-D nodalization of the Kori Unit 1, the reactor vessel nodalizations have been replaced by the multi-dimensional component. The multi-dimensional component for the reactor vessel is designed as 5 radial, 8 peripheral, and 21 vertical grids. It is assumed that the fuel assemblies are homogeneously distributed in inner 3 radial grids. The outer 1 radial grid region is modeled as the core bypass. The outer-model 1 radial grid is used for the downcomer region. The corresponding heat structures and fuels are modified to fit for the multi-dimensional reactor vessel model. The form drag coefficients for the upper plenum and the core have been designated as 0.6 and 9.39, respectively. The form drag coefficients for the radial and peripheral directions are assigned to the same on the assumption of homogeneous distribution of the flow obstacles. After obtaining the 102% power steady operation condition, cold leg LOCA simulation is performed during 400 second period. The multi-dimensional steady run results show no severe differences compared to the traditional 1-D nodalization results. After the ECC injection starts, a liquid pool is maintained at the upper plenum because the ECCS water can not overcome the upward gas flow that comes from the reactor core through the upper tie plate. The depth of ECCS water pool is predicted as about 20% of the total height from the upper tie plate and the center line of the hot leg pipe. At the vicinity region of the active ECCS show higher depth of liquid pool. The accumulated water flow rate passing the upper tie plate is calculated by the transient result. Much downward water flow is obtained at the outer-most region of upper plenum space. The downward flow dominant region is about 32.3% of the total upper tie plate area. The accumulated ECCS bypass ratio is predicted as 27.64% at 300 second. It is calculated

Characterization of a 14Cr ODS steel by means of small punch and uniaxial testing with regard to creep and fatigue at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Bruchhausen, M., E-mail: matthias.bruchhausen@ec.europa.eu [European Commission, Joint Research Centre, Institute for Energy and Transport, P.O. Box 2, 1755 ZG Petten (Netherlands); Turba, K. [European Commission, Joint Research Centre, Institute for Energy and Transport, P.O. Box 2, 1755 ZG Petten (Netherlands); Lund University, Division of Materials Engineering, P.O. Box 118, SE-221 00 Lund (Sweden); Haan, F. de; Hähner, P.; Austin, T. [European Commission, Joint Research Centre, Institute for Energy and Transport, P.O. Box 2, 1755 ZG Petten (Netherlands); Carlan, Y. de [CEA, DEN, Service de Recherches Métallurgiques Appliquées, 91191 Gif-sur-Yvette (France)

2014-01-15

A 14Cr ODS steel was characterized at elevated temperatures with regard to its behavior in small punch and uniaxial creep tests and in low cycle fatigue tests. A comparison of small punch and uniaxial creep tests at 650 °C revealed a strong anisotropy of the material when strained parallel and perpendicular to the extrusion direction with rupture times being several orders of magnitude lower for the perpendicular direction. The stress-rupture and Larson–Miller plots show a very large scatter of the creep data. This scatter is strongly reduced when rupture time is plotted against minimum deflection rate or minimum creep rate (Monkman–Grant plot). Fatigue tests have been carried out at 650 °C and 750 °C. The alloy is cyclically very stable with practically no hardening/softening. Results from the tests at both temperatures can be described by a common power law. An increase in the test temperature has little influence on the fatigue ductility exponent. For a given total strain level, the fatigue life of the alloy is reduced with increasing temperature.

Cold leg condensation tests. Task C. Steam--water interaction tests

International Nuclear Information System (INIS)

Brodrick, J.R.; Loiselle, V.

1974-03-01

A report is presented of tests to determine the condensation efficiency of ECC water injected into a quality fluid mixture flowing through the cold leg. In particular, a specific objective was to determine if the mixture of ECC water and quality fluid reached thermodynamic equilibrium before exiting the cold leg. Further, the stability of the ECC water/quality fluid interaction would be assessed by interpretation of thermocouple records and utilization of a section of cold leg piping with view ports to film the interaction whenever possible. The cold leg condensation tests showed complete condensation of the 5 lbm/sec steam quality mixtures in the cold leg by the ECC water flows of the test matrix. The cold leg exit fluid temperature remained below the saturation temperature and had good agreement with the predicted cold leg outlet temperature, calculated assuming total condensation. (U.S.)

Intricate and Cell Type-Specific Populations of Endogenous Circular DNA (eccDNA) in Caenorhabditis elegans and Homo sapiens.

Science.gov (United States)

Shoura, Massa J; Gabdank, Idan; Hansen, Loren; Merker, Jason; Gotlib, Jason; Levene, Stephen D; Fire, Andrew Z

2017-10-05

Investigations aimed at defining the 3D configuration of eukaryotic chromosomes have consistently encountered an endogenous population of chromosome-derived circular genomic DNA, referred to as extrachromosomal circular DNA (eccDNA). While the production, distribution, and activities of eccDNAs remain understudied, eccDNA formation from specific regions of the linear genome has profound consequences on the regulatory and coding capabilities for these regions. Here, we define eccDNA distributions in Caenorhabditis elegans and in three human cell types, utilizing a set of DNA topology-dependent approaches for enrichment and characterization. The use of parallel biophysical, enzymatic, and informatic approaches provides a comprehensive profiling of eccDNA robust to isolation and analysis methodology. Results in human and nematode systems provide quantitative analysis of the eccDNA loci at both unique and repetitive regions. Our studies converge on and support a consistent picture, in which endogenous genomic DNA circles are present in normal physiological states, and in which the circles come from both coding and noncoding genomic regions. Prominent among the coding regions generating DNA circles are several genes known to produce a diversity of protein isoforms, with mucin proteins and titin as specific examples. Copyright © 2017 Shoura et al.

A Secure-Enhanced Data Aggregation Based on ECC in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Qiang Zhou

2014-04-01

Full Text Available Data aggregation is an important technique for reducing the energy consumption of sensor nodes in wireless sensor networks (WSNs. However, compromised aggregators may forge false values as the aggregated results of their child nodes in order to conduct stealthy attacks or steal other nodes’ privacy. This paper proposes a Secure-Enhanced Data Aggregation based on Elliptic Curve Cryptography (SEDA-ECC. The design of SEDA-ECC is based on the principles of privacy homomorphic encryption (PH and divide-and-conquer. An aggregation tree disjoint method is first adopted to divide the tree into three subtrees of similar sizes, and a PH-based aggregation is performed in each subtree to generate an aggregated subtree result. Then the forged result can be identified by the base station (BS by comparing the aggregated count value. Finally, the aggregated result can be calculated by the BS according to the remaining results that have not been forged. Extensive analysis and simulations show that SEDA-ECC can achieve the highest security level on the aggregated result with appropriate energy consumption compared with other asymmetric schemes.

The Heat Exchanger for Passive Part ECCS of WWER-1000 on Base of the Thermo siphons

International Nuclear Information System (INIS)

Kirov, V.; Chulkin, O.

2008-01-01

One of NPP's systems providing safe operation is the system of emergency core cooling system (ECCS), which primary function in accidents is to flood the nuclear reactor core and to assure the sub critical condition and core cooling. At injection of cold water in reactor thermal stresses and thermal fatigue in the vessel cladding and constructional materials are arise. Low temperature of the water injected in reactor is a reason of occurrence of these undesirable consequences. Some variants of the water heating in accumulators of ECCS are considered. Now at Ukrainian NPPs the electrical heating in accumulators is used. Electrical heaters create the essential additional loading to diesel generators at imposing of two accidents - the large break and losses of power supplies on own needs. It is offered to use a heater in accumulators that working by a principle two-phase thermal siphon which advantages is: small dimensions, small delay and design reliability. In such heat exchanger the heating medium is a direct steam and the heated up medium is water with boric acid from accumulators of ECCS. Under requirements of the service regulations of ECCS accumulators it is necessary to guarantee injected water heating up to 90 ?? in case of a small break and to 150 ?? in case of the large break. Results of calculations for different external diameters of a tube of thermal siphon which have allowed to define the constructive sizes of heat exchanger, providing necessary conditions for required functioning of passive part ECCS are submitted The calculation and analysis of operating modes of the changed circuit of passive part ECCS for various accidents is carried out. The calculated pressure drop indicates that changes do not have essential influence on system work as a whole. Thus, the submitted decision provides the increase of reliability of ECCS at small and large breaks accidents, i.e. in all modes stipulated by the project.(author)

Superconductivity under uniaxial compression in β-(BDA-TTP) salts

International Nuclear Information System (INIS)

Suzuki, T.; Onari, S.; Ito, H.; Tanaka, Y.

2009-01-01

In order to clarify the mechanism of organic superconductor β-(BDA-TTP) salts. We study the superconductivity under uniaxial compression with non-dimerized two-band Hubbard model. We have calculated the uniaxial compression dependence of T c by solving the Eliashberg's equation using the fluctuation exchange (FLEX) approximation. The transfer integral under the uniaxial compression was estimated by the extended Huckel method. We have found that non-monotonic behaviors of T c in experimental results under uniaxial compression are understood taking the spin frustration and spin fluctuation into account.

Superconductivity under uniaxial compression in β-(BDA-TTP) salts

Science.gov (United States)

Suzuki, T.; Onari, S.; Ito, H.; Tanaka, Y.

2009-10-01

In order to clarify the mechanism of organic superconductor β-(BDA-TTP) salts. We study the superconductivity under uniaxial compression with non-dimerized two-band Hubbard model. We have calculated the uniaxial compression dependence of T c by solving the Eliashberg’s equation using the fluctuation exchange (FLEX) approximation. The transfer integral under the uniaxial compression was estimated by the extended Huckel method. We have found that non-monotonic behaviors of T c in experimental results under uniaxial compression are understood taking the spin frustration and spin fluctuation into account.

Superconductivity under uniaxial compression in beta-(BDA-TTP) salts

Energy Technology Data Exchange (ETDEWEB)

Suzuki, T., E-mail: suzuki@rover.nuap.nagoya-u.ac.j [Department of Applied Physics and JST, TRIP, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Onari, S.; Ito, H.; Tanaka, Y. [Department of Applied Physics and JST, TRIP, Nagoya University, Chikusa, Nagoya 464-8603 (Japan)

2009-10-15

In order to clarify the mechanism of organic superconductor beta-(BDA-TTP) salts. We study the superconductivity under uniaxial compression with non-dimerized two-band Hubbard model. We have calculated the uniaxial compression dependence of T{sub c} by solving the Eliashberg's equation using the fluctuation exchange (FLEX) approximation. The transfer integral under the uniaxial compression was estimated by the extended Huckel method. We have found that non-monotonic behaviors of T{sub c} in experimental results under uniaxial compression are understood taking the spin frustration and spin fluctuation into account.

Experiment data of ROSA-III integral test Run 7341

International Nuclear Information System (INIS)

Anoda, Yoshinari; Soda, Kunihisa; Tasaka, Kanji

1983-02-01

This report presents the test data of Run 7341 in the single failure test series of the ROSA-III program to conduct the system effect test concerning the response of a BWR during a LOCA with the ECC injection. The ROSA-III test facility is a volumetrically scaled (1/424) system of the BWR/6 with an electrically heated core and the scaled ECCS. Run 7341 is a double-ended break test at the recirculation pump inlet with the assumption that all ECCS function as designed. The test is initiated with the steam dome pressure of 7.28 MPa, the lower plenum subcooling of 11.0 K, the core inlet flow rate of 15.3 kg/s, and the core heat generation rate of 3.55 MW and proceeded as planned. The whole core is quenched after the ECCS actuation and the maximum fuel cladding temperature is 810 K. The effectiveness of ECC injection has been clarified from the comparison of the test results with those of the other test in the series without ECCS. (author)

BREASTFEEDING AND EARLY CHILDHOOD CARIES (ECC SEVERITY OF CHILDREN UNDER THREE YEARS OLD IN DKI JAKARTA

Directory of Open Access Journals (Sweden)

Risqa Rina Darwita

2008-12-01

Full Text Available The prevalence and severity of caries in children under three years old are constantly increasing. One of the cause is the increase consumption of cariogenic carbohydrate. Breast milk have buffer capacity that eventually able to prevent caries. The aims of this research are to discover the correlation between breastfeeding with the severity of Early Childhood Caries (ECC in children under three years old, to provide information on prevalence and severity of caries in children under three years, and to explain factors influencing the incidence of ECC. This research designed cross sectionally and conducted upon 565 children aged 12-38 months, selected using multistage cluster random sampling. The ECC prevalence of children under three years in DKI Jakarta is 52.7%, with average score of def-t 2.85. Bivariate analysis showed that, variables which correlate with the level of ECC are; the way to deliver (p=0,012, frequency (p=0,002, duration (p=0,002, salivary buffer capacity (p=0.013, habitual consumption of sugary diet (p=0.005, child’s dental hygiene behavior (p=0.002, and mother’s education (p=0.001. Multivariate analysis showed that ECC can be explained by these variables: age, mother’s education, the way to deliver and frequency of breast milk complements/replacement of consumtions, child’s brushing habit, plaque pH, and salivary buffer capacity. Resulting determination coefficient 32.1%. There is no significant correlation between breastfeeding and the level of Early Childhood Caries (ECC. The role of protective qualities of breastfeeding are not shown because of bias in obtaining data influence the incidence of caries.

Feeding practice among 6-36 months old in Tanzania and Uganda: reliability and relationship with early childhood caries, ECC.

Science.gov (United States)

Masumo, Ray; Bardsen, Asgeir; Mashoto, Kijakazi; Åstrøm, Anne Nordrehaug

2013-09-01

To assess the reproducibility of caregivers' responses to dietary recall from birth and 24-h dietary recall with respect to infants' intake of sugared snacks and to assess whether those assessment methods provide comparable results for groups of infants. Re-test reliability and clinical covariates of time to first exposure of sugared snacks and time to termination of breastfeeding were also examined. It was hypothesized that time to first exposure/termination would vary according to socio-demographic profile and ECC. Interviews and clinical oral examinations were carried out in Kampala and Manyara, including 1221 and 816 child-caregiver pairs. Reproducibility was assessed using Cohen's kappa and Intra Class Correlation Coefficient, ICC. Adjusted Cox regression was used to model time to first exposure of sugared snacks and time to termination of breastfeeding. Cohen's kappa for intake of sugar items ranged from 0.40-1.0, with no differences observed between average intakes at test-re-test. Mean sugar score based on 24-h recall increased significantly by increasing quartiles of the sugar score based on recall from birth. Cox regression revealed that the odds ratio, OR, for early exposure to various sugared snacks and the ORs for early termination of breastfeeding were significantly smaller in infants with than without ECC. Fair-to-good reproducibility was established. Infant's sugar consumption emerge as early as 6 months of age. Survival of any breastfeeding and non-exposure to sugared snacks was most prolonged among infants with ECC. This has implications for interventions needed to improve feeding habits of infants and toddlers.

Post-test analysis for the MIDAS DVI tests using MARS

International Nuclear Information System (INIS)

Bae, K. H.; Lee, Y. J.; Kwon, T. S.; Lee, W. J.; Kim, H. C.

2002-01-01

Various DVI tests have been performed at MIDAS test facility which is a scaled facility of APR1400 applying a modified linear scale ratio. The evaluation results for the various void height tests and direct bypass tests using a multi-dimensional best-estimate analysis code MARS, show that; (a) MARS code has an advanced modeling capability of well predicting major multi-dimensional thermal-hydraulic phenomena occurring in the downcomer, (b) MARS code under-predicts the steam condensation rates, which in turn causes to over-predict the ECC bypass rates. However, the trend of decrease in steam condensation rate and increase in ECC bypass rate in accordance with the increase in steam flow rate, and the calculation results of the ECC bypass rates under the EM analysis conditions generally agree with the test data

Comparison of allele frequency for HLA-DR and HLA-DQ between patients with ECC and caries-free children

Directory of Open Access Journals (Sweden)

Bagherian A

2008-03-01

Full Text Available Background: Early childhood caries (ECC is one of the most common diseases of childhood. The etiology of ECC is multifactorial and both genetic and environmental factors play important roles in the pathogenesis of the disease. Genetic variations in the hosts may contribute to changes in the risk for dental caries. Genetic factors such as human leukocyte antigen (HLA have recently been suggested as a predisposing factor. Aim: The aim of this study was to look for an association between HLA-DRB1 and HLA-DQB1 with ECC for developing new strategies for the diagnosis as well as the prevention of the disease. Design: In this study, we extracted the genomic DNAs from whole blood samples of 44 patients with ECC and 35 caries-free children by the salting-out method. We amplified the genomic DNA by PCR-SSP and then HLA-typing was performed for all alleles. Results: The results revealed a significant increase in the frequency of HLA-DRB1FNx0104 in the patient group (P = 0.019. The odds ratio for this allele was detected to be 10. The frequency of HLA-DQB1 alleles was not significantly different between the two groups. Conclusion: The above results suggest that HLA-DRB1FNx0104 is associated with the susceptibility to ECC. Thus HLA-DRB1FNx0104 detection as a molecular marker for early diagnosis of ECC may be recommended.

Experimental study on uniaxial cyclic ratcheting behavior of 304 stainless steel at room temperature

International Nuclear Information System (INIS)

Yang Xianjie; Gao Qing; Cai Lixun; Liu Yujie

2004-01-01

The cyclic tests for 304 stainless steel with solution heat treatment under uni-axial cyclic straining and stressing were carried out systematically. The effects of the cyclic engineering stress amplitude history with constant mean stress, the mean engineering stress history with constant cyclic stress amplitude and the stress amplitude histories with the specific mean stress increment per cycle on the uni-axial ratcheting deformation behavior were investigated. Some significant results are obtained

Adapted ECC ozonesonde for long-duration flights aboard boundary-layer pressurised balloons

Science.gov (United States)

Gheusi, François; Durand, Pierre; Verdier, Nicolas; Dulac, François; Attié, Jean-Luc; Commun, Philippe; Barret, Brice; Basdevant, Claude; Clenet, Antoine; Derrien, Solène; Doerenbecher, Alexis; El Amraoui, Laaziz; Fontaine, Alain; Hache, Emeric; Jambert, Corinne; Jaumouillé, Elodie; Meyerfeld, Yves; Roblou, Laurent; Tocquer, Flore

2016-12-01

Since the 1970s, the French space agency CNES has developed boundary-layer pressurised balloons (BLPBs) with the capability to transport lightweight scientific payloads at isopycnic level and offer a quasi-Lagrangian sampling of the lower atmosphere over very long distances and durations (up to several weeks).Electrochemical concentration cell (ECC) ozonesondes are widely used under small sounding balloons. However, their autonomy is limited to a few hours owing to power consumption and electrolyte evaporation. An adaptation of the ECC sonde has been developed specifically for long-duration BLPB flights. Compared to conventional ECC sondes, the main feature is the possibility of programming periodic measurement sequences (with possible remote control during the flight). To increase the ozonesonde autonomy, the strategy has been adopted of short measurement sequences (2-3 min) regularly spaced in time (e.g. every 15 min). The rest of the time, the sonde pump is turned off. Results of preliminary ground-based tests are first presented. In particular, the sonde was able to provide correct ozone concentrations against a reference UV-absorption ozone analyser every 15 min for 4 days. Then we illustrate results from 16 BLBP flights launched over the western Mediterranean during three summer field campaigns of the ChArMEx project (http://charmex.lsce.ipsl.fr): TRAQA in 2012, and ADRIMED and SAFMED in 2013. BLPB drifting altitudes were in the range 0.25-3.2 km. The longest flight lasted more than 32 h and covered more than 1000 km. Satisfactory data were obtained when compared to independent ozone measurements close in space and time. The quasi-Lagrangian measurements allowed a first look at ozone diurnal evolution in the marine boundary layer as well as in the lower free troposphere. During some flight segments, there was indication of photochemical ozone production in the marine boundary layer or even in the free troposphere, at rates ranging from 1 to 2 ppbv h -1, which

Multi-purpose fatigue sensor. Part 1. Uniaxial and multiaxial fatigue

Directory of Open Access Journals (Sweden)

M.V. Karuskevich

2016-10-01

Full Text Available The paper describes the key principles and results of preliminary experiments aimed at the development of new technique for the fatigue life prediction under conditions of biaxial cyclic tension. The foundations of the method were developed early by the numerous tests with monitoring the process of surface deformation relief formation, which is proved to be an indicator of accumulated fatigue damage under uniaxial fatigue. The employed phenomenon was early applied for the development of a family of uniaxial loading fatigue sensors. The formation of strain induced relief has been recently taken into consideration as a part of damage accumulation criteria under biaxial fatigue as well. The home-made testing machine has been designed to implement combined bending and torsion loading that simulates loads experienced by an aircraft wing skin. The experimental evidences on formation and evolution of the deformation relief revealed under conditions of combined loading, supports the proposed concept of biaxial fatigue sensor

Intercomparison of ozone measurements between Lidar and ECC-sondes

Energy Technology Data Exchange (ETDEWEB)

Grabbe, G.C. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Boesenberg, J. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Dier, H. [Meteorologisches Obs., Lindenberg (Germany); Goersdorf, U. [Meteorologisches Obs., Lindenberg (Germany); Matthias, V. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Peters, G. [Meteorologisches Obs., Lindenberg (Germany); Schaberl, T. [Hamburg Univ. (Germany). Meteorologisches Inst.; Senff, C. [Hamburg Univ. (Germany). Meteorologisches Inst.

1996-02-01

An intercomparison experiment for measurements of ozone vertical profiles in the lower troposphere was performed using a ground-based ozone DIAL (DIfferential Absorption Lidar) and ECC-sondes (Electrochemical Concentration Cell) attached to tethered as well as free flying balloons, which took place in June of 1994. The tethered balloon was used for ozone soundings in the planetary boundary layer up to an altitude of 500 m, while in the free troposphere free flying balloons were used. For the time series of up to 90 min obtained with the tethersondes both averages and standard deviations are compared. The mean difference for all measurements amounted to 3.5 {mu}g/m{sup 3} only, corresponding to 3.5%. For the instantaneous profiles compared to the free flying sondes the differences were only marginally larger, with a mean value of 3.6 {mu}g/m{sup 3} corresponding to 4.1%. With two exceptions all averages for a single profile stayed below 7 {mu}g/m{sup 3}. Larger individual excursions were observed. In some cases, in particular in regions of steep aerosol gradients at layer boundaries, most probably the lidar values cause the deviation, while in other cases the ECC-sonde is suspected to yield erroneous results. For the measured standard deviation those retrieved from DIAL measurements are generally larger than measured by the ECC-sondes, especially in regions of inhomogeneous aerosol distribution. For the measurements reported here, this is attributed to residual errors in the aerosol correction of the DIAL measurements. The general agreement found in this intercomparison is regarded as excellent, DIAL is proven to be a very valuable tool for detailed studies of the ozone distribution in the lower troposphere. (orig.)

Modified ECC ozone sonde for long-duration flights aboard isopicnic drifting balloons

Science.gov (United States)

Gheusi, Francois; Durand, Pierre; Verdier, Nicolas; Dulac, François; Attié, Jean-Luc; Commun, Philippe; Barret, Brice; Basdevant, Claude; Clénet, Antoine; Fontaine, Alain; Jambert, Corinne; Meyerfeld, Yves; Roblou, Laurent; Tocquer, Flore

2015-04-01

Since few years, the French space agency CNES has developed boundary-layer pressurized balloons (BLPB) with the capability to transport scientific payloads at isopicnic level over very long distances and durations (up to several weeks in absence of navigation limits). However, the autonomy of conventional electrochemical concentration cell (ECC) ozone sondes, that are widely used for tropospheric and stratospheric soundings, is limited to few hours due to power consumption and electrolyte evaporation (owing to air bubbling in the cathode solution). In collaboration with the French research community, CNES has developed a new ozone payload suited for long duration flights aboard BLPB. The mechanical elements (Teflon pump and motor) and the electrochemical cell of conventional ECC sondes have been kept but the electronic implementation is entirely new. The main feature is the possibility of programming periodic measurement sequences -- with possible remote control during the flight. To increase the ozone sonde autonomy, a strategy has been adopted of short measurement sequences (typically 2-3 min) regularly spaced in time (e.g. every 15 min, which is usually sufficient for air quality studies). The rest of the time, the sonde is at rest (pump motor off). The response time of an ECC sonde to an ozone concentration step is below one minute. Consequently, the measurement sequence is typically composed of a one-minute spin-up period after the pump has been turned on, followed by a one- to two-minute acquisition period. All time intervals can be adjusted before and during the flight. Results of a preliminary ground-based test in spring 2012 are first presented. The sonde provided correct ozone concentrations against a reference UV analyzer every 15 minutes during 4 days. Then we illustrate results from 16 BLBP flights launched in the low troposphere over the Mediterranean during summer field campaings in 2012 and 2013 (TRAQA and ChArMEx programmes). BLPB drifting

Analysis of electromagnetic scattering by uniaxial anisotropic bispheres.

Science.gov (United States)

Li, Zheng-Jun; Wu, Zhen-Sen; Li, Hai-Ying

2011-02-01

Based on the generalized multiparticle Mie theory and the Fourier transformation approach, electromagnetic (EM) scattering of two interacting homogeneous uniaxial anisotropic spheres with parallel primary optical axes is investigated. By introducing the Fourier transformation, the EM fields in the uniaxial anisotropic spheres are expanded in terms of the spherical vector wave functions. The interactive scattering coefficients and the expansion coefficients of the internal fields are derived through the continuous boundary conditions on which the interaction of the bispheres is considered. Some selected calculations on the effects of the size parameter, the uniaxial anisotropic absorbing dielectric, and the sphere separation distance are described. The backward radar cross section of two uniaxial anisotropic spheres with a complex permittivity tensor changing with the sphere separation distance is numerically studied. The authors are hopeful that the work in this paper will help provide an effective calibration for further research on the scattering characteristic of an aggregate of anisotropic spheres or other shaped anisotropic particles.

Cyclic mechanical behavior of 316L: Uniaxial LCF and strain-controlled ratcheting tests

International Nuclear Information System (INIS)

Facheris, G.; Janssens, K.G.F.

2013-01-01

Highlights: ► Characterization of cyclic plastic deformation behavior of plate and tubular 316L. ► Strain-controlled ratcheting response between room temperature and 200 °C. ► Isotropic cyclic hardening is dependent on the yield criterion used. ► Ratcheting induced hardening mostly affects the kinematic hardening component. ► Ratcheting induced hardening is related to the mean strain and the ratcheting rate. -- Abstract: With the purpose of analyzing the fatigue behavior under loading conditions relevant for the primary cooling circuit of a light water nuclear reactor, a set of uniaxial low cycle fatigue and strain-controlled ratcheting tests (also named ‘cyclic tension tests’) has been performed at room temperature and at 200 °C on specimens manufactured from two different batches of stainless steel grade 316L. The experiments have been repeated varying strain amplitude, cyclic ratcheting rate and ratcheting direction in order to investigate the influence on the cyclic deformation behavior. In strain-controlled ratcheting tests, the stress response is found to be a superposition of two hardening mechanisms: the first one due to the zero mean strain cycling and the second one linked with the monotonic drifting of mean plastic strain. An approach is proposed to distinguish the effect of each mechanism and the influence of the test parameters on the hardening mechanisms is discussed

ECCS evaluation of B and W's 205-FA NSS

International Nuclear Information System (INIS)

Lowe, R.J.; Anderson, G.E. Jr.; Dunn, B.M.

1975-06-01

The effectiveness of the ECCS for B and W's 205-fuel assembly plants is evaluated and shown to meet all the requirements of 10 CFR 50.46. The results of various sensitivity studies, a spectrum of breaks, and an analysis to determine allowable linear heat rates under 10 CFR 50.46 are presented. (14 references) (U.S.)

Simulation of Texture Evolution during Uniaxial Deformation of Commercially Pure Titanium

Science.gov (United States)

Bishoyi, B.; Debta, M. K.; Yadav, S. K.; Sabat, R. K.; Sahoo, S. K.

2018-03-01

The evolution of texture in commercially pure (CP) titanium during uniaxial tension and compression through VPSC (Visco-plastic self-consistent) simulation is reported in the present study. CP-titanium was subjected to both uniaxial tension and compression upto 35% deformation. During uniaxial tension, tensile twin of \\{10\\bar{1}2\\}\\unicode{x003C;}\\bar{1}011\\unicode{x003E;} type and compressive twin of \\{11\\bar{2}2\\}\\unicode{x003C;}11\\bar{2}\\bar{3}\\unicode{x003E;} type were observed in the samples. However, only tensile twin of \\{10\\bar{1}2\\}\\unicode{x003C;}\\bar{1}011\\unicode{x003E;} type and compressive twin of type was observed in the samples during uniaxial compression. Volume fractions of the twins were increased linearly as a function of percentage deformation during uniaxial tension. Whereas, during uniaxial compression the twinning volume fraction was increased up to 20% deformation and then decreased rapidly on further increasing the percentage deformation. During uniaxial tension, the general t-type textures were observed in the samples irrespective of the percentage deformation. The initial non-basal texture was oriented to split basal texture during uniaxial compression of the sample. VPSC formulation was used for simulating the texture development in the material. Different hardening parameters were estimated through correlating the simulated stress-strain curve with the experimental stress-strain data. It was observed that, prismatic slip \\{10\\bar{1}0\\}\\unicode{x003C;}11\\bar{2}0\\unicode{x003E;} operated as the primary deformation mode during uniaxial tension whereas basal slip \\{0001\\}\\unicode{x003C;}11\\bar{2}0\\unicode{x003E;} acquired the leading role during deformation through uniaxial compression. It was also revealed that active deformation modes were fully depending on percentage deformation, loading direction, and orientation of grains.

A PWR reactor downcomer modification for reduction of ECC bypass flow during LOCA

International Nuclear Information System (INIS)

Popov, N.; Bosevski, T.

1986-01-01

The ECC bypass phenomenon in the PWR reactor down-comer, which delays the reactor vessel refilling, after cold leg large break LOCA accident, has been subject of analysis in this paper. In the paper, a particular construction modification of the reactor down-comer has been suggested by inserting vertical ribs, aimed to intensify the reactor ECC refilling following the LOCA accident, and to advance the thermal-hydraulics safety of post-accidental cooling of the PWR reactors. To verify the effectiveness of the suggested down-comer construction modification, some properly selected results, obtained by corresponding verified mathematical model, have been presented in this paper. (author)

Modeling of ECC materials using numerical formulations based on plasticity

DEFF Research Database (Denmark)

Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe

2006-01-01

scale it is shown that the cohesive law for a unidirectional fiber reinforced cementitious composite can be found through superposition of the cohesive law for mortar and the fiber bridging curve. On the meso scale I it is shown that the maximum crack opening observed during crack propagation in ECC...

Experimental study on uniaxial ratcheting deformation and failure behavior of 304 stainless steel

International Nuclear Information System (INIS)

Yang Xianjie; Gao Qing; Cai Lixun; Liu Yujie

2004-01-01

In the paper, the tests of cyclic strain ratcheting and low cycle fatigue for 304 stainless steel under uniaxial cyclic straining were carried out to systematically explore the deformation and failure behavior of the material. The experimental study shows that the cyclic strain ratcheting deformation behavior of the material is different from either the uniaxial monotonic tensile one or the cyclic deformation one under the symmetrical cyclic straining with the same strain amplitude, and the strain ratcheting deformation and failure behaviors depend on both the plastic strain amplitude and the strain increment at the cyclic maximum strain. Some significant results were observed

Disease Management of Early Childhood Caries: ECC Collaborative Project.

Science.gov (United States)

Ng, Man Wai; Ramos-Gomez, Francisco; Lieberman, Martin; Lee, Jessica Y; Scoville, Richard; Hannon, Cindy; Maramaldi, Peter

2014-01-01

Until recently, the standard of care for early childhood caries (ECC) has been primarily surgical and restorative treatment with little emphasis on preventing and managing the disease itself. It is now recognized that surgical treatment alone does not address the underlying etiology of the disease. Despite costly surgeries and reparative treatment, the onset and progression of caries are likely to continue. A successful rebalance of risk and protective factors may prevent, slow down, or even arrest dental caries and its progression. An 18-month risk-based chronic disease management (DM) approach to address ECC in preschool children was implemented as a quality improvement (QI) collaborative by seven teams of oral health care providers across the United States. In the aggregate, fewer DM children experienced new cavitation, pain, and referrals to the operating room (OR) for restorative treatment compared to baseline historical controls. The teams found that QI methods facilitated adoption of the DM approach and resulted in improved care to patients and better outcomes overall. Despite these successes, the wide scale adoption and spread of the DM approach may be limited unless health policy and payment reforms are enacted to compensate providers for implementing DM protocols in their practice.

Minimum containment pressure and its effect on ECCS performance of APR-1400

International Nuclear Information System (INIS)

Kim, In Goo; Bang, Young S.; Kim, Hho Jung

2004-01-01

The containment pressure has a strong effect on the late reheat behavior for a large break LOCA, associated with the DVI issue. The downcomer boiling, which occurs during the post-reflood phase, has a negative effect on core cooling for a LBLOCA. Because the downcomer boiling is enhanced as the containment pressure decreases, how to determine containment pressure is important to the evaluation of ECCS performance. In spite of its importance of containment pressure, there are few studies on the containment pressure and the interaction between RCS and containment thermal hydraulics. To have a better knowledge of the effect of containment pressure on APR-1400 ECCS performance, a parametric study for containment pressure has been carried out. Also, the interaction between RCS and containment behavior has been also investigated

Post-test analysis for the APR1400 LBLOCA DVI performance test using MARS

International Nuclear Information System (INIS)

Bae, Kyoo Hwan; Lee, Y. J.; Kim, H. C.; Bae, Y. Y.; Park, J. K.; Lee, W.

2002-03-01

Post-test analyses using a multi-dimensional best-estimate analysis code, MARS, are performed for the APR1400 LBLOCA DVI (Direct Vessel Injection) performance tests. This report describes the code evaluation results for the test data of various void height tests and direct bypass tests that have been performed at MIDAS test facility. MIDAS is a scaled test facility of APR1400 with the objective of identifying multi-dimensional thermal-hydraulic phenomena in the downcomer during the reflood conditions of a large break LOCA. A modified linear scale ratio was applied in its construction and test conditions. The major thermal-hydraulic parameters such as ECC bypass fraction, steam condensation fraction, and temperature distributions in downcomer are compared and evaluated. The evaluation results of MARS code for the various test cases show that: (a) MARS code has an advanced modeling capability of well predicting major multi-dimensional thermal-hydraulic phenomena occurring in the downcomer, (b) MARS code under-predicts the steam condensation rates, which in turn causes to over-predict the ECC bypass rates. However, the trend of decrease in steam condensation rate and increase in ECC bypass rate in accordance with the increase in steam flow rate, and the calculation results of the ECC bypass rates under the EM analysis conditions generally agree with the test data

Heat induced fracturing of rock in an existing uniaxial stress field

International Nuclear Information System (INIS)

Mathis, J.; Stephansson, O.; Bjarnason, B.; Hakami, H.; Herdocia, A.; Mattila, U.; Singh, U.

1986-01-01

This study was initiated under the premise that it may be possible to determine the state of stress in the earth's crust by heat induced fracturing of the rock surrounding a borehole. The theory involved is superficially simple, involving the superposition of the stress field around a borehole due to the existing virgin stresses and the uniform stress field of thermally loaded rock as induced by a heater. Since the heat stress field is uniform, varying only in magnitude and gradient as a function of heater input, fracturing should be controlled by the non-uniform virgin stress field. To determine if the method was, in fact, feasible, a series of laboratory test were conducted. These tests consisted of physically loading center drilled cubes of rock, 0.3 m on a side, uniaxially from 0 to 25 MPa. The blocks were then thermally loaded with a nominally rated 3.7 kW heater until failure occurred. Results from these laboratory tests were then compared to analytical studies of the problem, i.e., finite element and discrete theoretical analysis. Overall, results were such that the method is likely eliminated as a stress measurement technique. The immediate development of a thermal compressive zone on the borehole wall overlaps the tensile zone created by the uniaxial stress field, forcing the failure is thus controlled largely by the power input of the heater, being retarded by the small compressive stresses genrated by the uniaxial stress field. This small retardation effect is of such low magnitude that the retardation effect is of such low magnitude that the fracture time is relatively insensitive to the local virgin stress field. (authors)

Compendium of ECCS [Emergency Core Cooling Systems] research for realistic LOCA [loss-of-coolant accidents] analysis: Final report

International Nuclear Information System (INIS)

1988-12-01

In the United States, Emergency Core Cooling Systems (ECCS) are required for light water reactors (LWRs) to provide cooling of the reactor core in the event of a break or leak in the reactor piping or an inadvertent opening of a valve. These accidents are called loss-of-coolant accidents (LOCA), and they range from small leaks up to a postulated full break of the largest pipe in the reactor cooling system. Federal government regulations provide that LOCA analysis be performed to show that the ECCS will maintain fuel rod cladding temperatures, cladding oxidation, and hydrogen production within certain limits. The NRC and others have completed a large body of research which investigated fuel rod behavior and LOCA/ECCS performance. It is now possible to make a realistic estimate of the ECCS performance during a LOCA and to quantify the uncertainty of this calculation. The purpose of this report is to summarize this research and to serve as a general reference for the extensive research effort that has been performed. The report: (1) summarizes the understanding of LOCA phenomena in 1974; (2) reviews experimental and analytical programs developed to address the phenomena; (3) describes the best-estimate computer codes developed by the NRC; (4) discusses the salient technical aspects of the physical phenomena and our current understanding of them; (5) discusses probabilistic risk assessment results and perspectives, and (6) evaluates the impact of research results on the ECCS regulations. 736 refs., 412 figs., 66 tabs

Analysis of the Mechanical Behavior, Creep Resistance and Uniaxial Fatigue Strength of Martensitic Steel X46Cr13

Science.gov (United States)

Brnic, Josip; Krscanski, Sanjin; Lanc, Domagoj; Brcic, Marino; Turkalj, Goran; Canadija, Marko; Niu, Jitai

2017-01-01

The article deals with the analysis of the mechanical behavior at different temperatures, uniaxial creep and uniaxial fatigue of martensitic steel X46Cr13 (1.4034, AISI 420). For the purpose of considering the aforementioned mechanical behavior, as well as determining the appropriate resistance to creep and fatigue strength levels, numerous uniaxial tests were carried out. Tests related to mechanical properties performed at different temperatures are presented in the form of engineering stress-strain diagrams. Short-time creep tests performed at different temperatures and different stress levels are presented in the form of creep curves. Fatigue tests carried out at stress ratios R=0.25 and R=−1 are shown in the form of S–N (fatigue) diagrams. The finite fatigue regime for each of the mentioned stress ratios is modeled by an inclined log line, while the infinite fatigue regime is modeled by a horizontal line, which represents the fatigue limit of the material and previously was calculated by the modified staircase method. Finally, the fracture toughness has been calculated based on the Charpy V-notch impact energy. PMID:28772749

Using ECC DRAM to Adaptively Increase Memory Capacity

OpenAIRE

Luo, Yixin; Ghose, Saugata; Li, Tianshi; Govindan, Sriram; Sharma, Bikash; Kelly, Bryan; Boroumand, Amirali; Mutlu, Onur

2017-01-01

Modern DRAM modules are often equipped with hardware error correction capabilities, especially for DRAM deployed in large-scale data centers, as process technology scaling has increased the susceptibility of these devices to errors. To provide fast error detection and correction, error-correcting codes (ECC) are placed on an additional DRAM chip in a DRAM module. This additional chip expands the raw capacity of a DRAM module by 12.5%, but the applications are unable to use any of this extra c...

Preestrita pihtimus : Friedrich Nietzsche ja tema substantsiaalne mina (Ecce homo) / Jaan Undusk

Index Scriptorium Estoniae

Undusk, Jaan, 1958-

1998-01-01

Varem ilmunud raamatu järelsõnana: Nietzsche, Friedrich. Ecce homo : kuidas saadakse selleks, mis ollakse / tlk. Jaan Undusk. Tallinn : Vagabund, 1996. Sisu: Poeetiline, filosoofiline, dionüüsiline kaanon ; Künism contra hulluskahtlus ; Antikristlik pihtimus ; Egoretoorika

Predictive Eco-Cruise Control (ECC) system : model development, modeling and potential benefits.

Science.gov (United States)

2013-02-01

The research develops a reference model of a predictive eco-cruise control (ECC) system that intelligently modulates vehicle speed within a pre-set speed range to minimize vehicle fuel consumption levels using roadway topographic information. The stu...

Parametric study of the potential for BWR ECCS strainer blockage due to LOCA generated debris. Final report

International Nuclear Information System (INIS)

Zigler, G.; Brideau, J.; Rao, D.V.; Shaffer, C.; Souto, F.; Thomas, W.

1995-10-01

This report documents a plant-specific study for a BWR/4 with a Mark I containment that evaluated the potential for LOCA generated debris and the probability of losing long term recirculation capability due ECCS pump suction strainer blockage. The major elements of this study were: (1) acquisition of detailed piping layouts and installed insulation details for a reference BWR; (2) analysis of plant specific piping weld failure probabilities to estimate the LOCA frequency; (3) development of an insulation and other debris generation and drywell transport models for the reference BWR; (4) modeling of debris transport in the suppression pool; (5) development of strainer blockage head loss models for estimating loss of NPSH margin; (6) estimation of core damage frequency attributable to loss of ECCS recirculation capability following a LOCA. Elements 2 through 5 were combined into a computer code, BLOCKAGE 2.3. A point estimate of overall DEGB pipe break frequency (per Rx-year) of 1.59E-04 was calculated for the reference plant, with a corresponding overall ECCS loss of NPSH frequency (per Rx-year) of 1.58E-04. The calculated point estimate of core damage frequency (per Rx-year) due to blockage related accident sequences for the reference BWR ranged from 4.2E-06 to 2.5E-05. The results of this study show that unacceptable strainer blockage and loss of NPSH margin can occur within the first few minutes after ECCS pumps achieve maximum flows when the ECCS strainers are exposed to LOCA generated fibrous debris in the presence of particulates (sludge, paint chips, concrete dust). Generic or unconditional extrapolation of these reference plant calculated results should not be undertaken

Failure Mode and Effects Analysis (FMEA) of the Emergency Core Cooling System (ECCS) for a Westinghouse type 312, three loop pressurized water reactor

International Nuclear Information System (INIS)

Shopsky, W.E.

1977-01-01

The Emergency Core Cooling System (ECCS) is a Safeguards System designed to cool the core in the unlikely event of a Loss-of-Coolant Accident (LOCA) in the primary reactor coolant system as well as to provide additional shutdown capability following a steam break accident. The system is designed for a high reliability of providing emergency coolant and shutdown reactivity to the core for all anticipated occurrences of such accidents. The ECCS by performing its intended function assures that fuel and clad damage is minimized during accident conditions thus reducing release of fission products from the fuel. The ECCS is designed to perform its function despite sustaining a single failure by the judicious use of equipment and flow path redundancy within and outside the containment structure. By the use of an analytic tool, a Failure Mode and Effects Analysis (FMEA), it is shown that the ECCS is in compliance with the Single Failure Criterion established for active failures of fluid systems during short and long term cooling of the reactor core following a LOCA or steam break accident. An analysis was also performed with regards to passive failure of ECCS components during long-term cooling of the core following an accident. The design of the ECCS was verified as being able to tolerate a single passive failure during long-term cooling of the reactor core following an accident. The FMEA conducted qualitatively demonstrates the reliability of the ECCS (concerning active components) to perform its intended safety function

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

Science.gov (United States)

Feng, Xiaowei; Zhang, Nong; Zheng, Xigui; Pan, Dongjiang

2015-01-01

Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE) testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three-dimensional damage source

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions.

Directory of Open Access Journals (Sweden)

Xiaowei Feng

Full Text Available Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three

Development of CANDU ECCS performance evaluation methodology and guides

Energy Technology Data Exchange (ETDEWEB)

Bang, Kwang Hyun; Park, Kyung Soo; Chu, Won Ho [Korea Maritime Univ., Jinhae (Korea, Republic of)

2003-03-15

The objectives of the present work are to carry out technical evaluation and review of CANDU safety analysis methods in order to assist development of performance evaluation methods and review guides for CANDU ECCS. The applicability of PWR ECCS analysis models are examined and it suggests that unique data or models for CANDU are required for the following phenomena: break characteristics and flow, frictional pressure drop, post-CHF heat transfer correlations, core flow distribution during blowdown, containment pressure, and reflux rate. For safety analysis of CANDU, conservative analysis or best estimate analysis can be used. The main advantage of BE analysis is a more realistic prediction of margins to acceptance criteria. The expectation is that margins demonstrated with BE methods would be larger that when a conservative approach is applied. Some outstanding safety analysis issues can be resolved by demonstration that accident consequences are more benign than previously predicted. Success criteria for analysis and review of Large LOCA can be developed by top-down approach. The highest-level success criteria can be extracted from C-6 and from them, the lower level criteria can be developed step-by-step, in a logical fashion. The overall objectives for analysis and review are to verify radiological consequences and frequency are met.

Disease Management of Early Childhood Caries: ECC Collaborative Project

Directory of Open Access Journals (Sweden)

Man Wai Ng

2014-01-01

Full Text Available Until recently, the standard of care for early childhood caries (ECC has been primarily surgical and restorative treatment with little emphasis on preventing and managing the disease itself. It is now recognized that surgical treatment alone does not address the underlying etiology of the disease. Despite costly surgeries and reparative treatment, the onset and progression of caries are likely to continue. A successful rebalance of risk and protective factors may prevent, slow down, or even arrest dental caries and its progression. An 18-month risk-based chronic disease management (DM approach to address ECC in preschool children was implemented as a quality improvement (QI collaborative by seven teams of oral health care providers across the United States. In the aggregate, fewer DM children experienced new cavitation, pain, and referrals to the operating room (OR for restorative treatment compared to baseline historical controls. The teams found that QI methods facilitated adoption of the DM approach and resulted in improved care to patients and better outcomes overall. Despite these successes, the wide scale adoption and spread of the DM approach may be limited unless health policy and payment reforms are enacted to compensate providers for implementing DM protocols in their practice.

A uniaxial cyclic elastoplastic constitutive law with a discrete memory variable

International Nuclear Information System (INIS)

Taheri, S.

1991-01-01

At present, the study on cyclic elastoplastic constitutive laws is focused on nonproportional loading, but for uniaxial loading, some problems still exist. For example, the possibility for a law to describe simultaneously the ratcheting in nonsymmetrical load-controlled test, elastic and plastic shakedown in symmetrical and nonsymmetrical ones. Here a law is presented, which in addition to previous phenomena, describes the cyclic hardening in a pushpull test, the cyclic softening after overloading and also the dependence of cyclic strain-stress curves on the history of loading. These are the usual properties of 316 stainless steel at room temperature. This law uses an internal discrete memory variable: the plastic strain at the last unloading. On the other hand, the choice of all macroscopic variables is justified by a microscopic analysis. This law has been also extended to a three-dimensional case. Regarding the microstructure under cyclic loading, plastic shakedown and ratcheting are discussed. The definition of macroscopic variables taking account of microstructure and uniaxial constitutive law are described. (K.I.)

On the energy shift of the ECC cusp. Does the shift really exist?

International Nuclear Information System (INIS)

Barrachina, R.O.; Sarkadi, L.

2004-01-01

Full text: The cusplike 'electron capture to the continuum' (ECC) peak appearing in the spectrum of the forward emitted electrons in ion-atom collisions is generally thought to be a divergence. The peak is centered at electron velocity that matches that of the projectile. Recently Illescas et al. [1] claimed, however, that 'the cusp is not a divergence smoothed by the experiment, and is slightly shifted from the impact-velocity value'. In a subsequent work Shah et al. [2] measured the ECC cusp for collisions of 10- and 20- keV protons with H2 and He, and found that the peak was indeed shifted to a velocity below its expected position. Their classical trajectory Monte Carlo (CTMC) calculations reproduced the observation well. In the present work we demonstrate by our CTMC calculations (made for the case of 20-keV protons on He) that the intensity, width and position of the ECC cusp do depend on the experimental conditions by which the electrons are detected (first of all, the acceptance angle of the electron spectrometer). We also present experimental data for this collision system. While the latter data are well reproduced by our CTMC calculations, neither the theoretical results, nor the experimental data of the present work support of the findings of Shah et al. [2]. At the same time, analyzing the problem in the framework of the general final-state interaction theory of cusp formation [3], we concluded that 'rigorously' speaking Shah et al. [2] are right when they state that the ECC cusp is not a divergence. The divergence is smeared out by the scattering of the projectile. However, this effect is negligibly small at the lowest energy that was considered in their paper, 10 keV. At this impact energy the projectile motion is smeared within an angular region Δθ th ∼ 0.06 deg, which is much smaller than the acceptance angle of the experiment, Δθ exp ∼ 1.5 deg

The Evaluation of the Effect of Strain Limits on the Physical Properties of Magnetorheological Elastomers Subjected to Uniaxial and Biaxial Cyclic Testing.

OpenAIRE

Gorman, Dave; Murphy, Niall; Ekins, Ray; Jerrams, Stephen

2017-01-01

Magnetorheological Elastomers (MREs) are “smart” materials whose physical properties are altered by the application of magnetic fields. In a previous study by the authors [1], variations in the physical properties of MREs have been evaluated when subjected to a range of magnetic field strengths for both uniaxial and biaxial cyclic tests. By applying the same magnetic field to similar samples, this paper investigates the effect of both the upper strain limit and the strain amplitude on the pro...

Thermo-mechanical fatigue behaviour of the near-{gamma}-titanium aluminide alloy TNB-V5 under uniaxial and multiaxial loading

Energy Technology Data Exchange (ETDEWEB)

Brookes, Stephen Peter

2009-12-19

With increasing environmental awareness and the general need to economise on the use of fossil fuels, there is growing pressure for industry to produce lighter, more efficient, gas turbine engines. One such material that will help to achieve these improvements is the intermetallic gamma titanium aluminide ({gamma}-TiAl) alloy. At only half the density of current nickel-based superalloys its weight saving capability is highly desirable, however, its mechanical properties have not yet been fully explored especially, when it is to be considered for structural components in aeronautical gas turbine engines. Critical components in these engines typically experience large variations in temperatures and multiaxial states of stress under non-isothermal conditions. These stress states are known as tri-axial thermo-mechanical fatigue (TMF). The work presented here investigates the effects these multi-axial stresses, have on a {gamma}-TiAl, (Ti-45Al-5Nb-0.2B-0.2C) alloy under TMF conditions. The uniaxial, torsional and axialtorsional TMF behaviour of this {gamma}-TiAl alloy have been examined at 400 - 800 C with strain amplitudes ranging from 0.15% to 0.7%. The tests were conducted at both thermomechanical in-phase (IP) and out-of-phase (OP). Selected tests additionally contained a 180 seconds hold period. Fatigue lifetimes are strongly influenced by the strain amplitude, a small increase in amplitude reduces the lifetime considerably. The uniaxial IP tests showed significantly longer fatigue lifetimes than of all the tests performed. Torsional loading although have shorter fatigue lifetimes than the uniaxial IP loading they have longer fatigue lifetimes than the uniaxial OP loading. The non-proportional axial-torsional 90 degree OP test is most damaging which resulted in a shorter lifetime than the uniaxial OP test with the same Mises equivalent mechanical strain amplitude. A hold period at maximum temperatures reduced the lifetime for all tests regardless of the temperature

ECCS analysis of B and W's 177-FA lowered-loop NSS

International Nuclear Information System (INIS)

Jones, R.C.; Biller, J.R.; Dunn, B.M.

1975-06-01

The effectiveness for the ECCS for B and W's 177-FA Lowered-Loop NSS is shown to meet the five criteria of 10 CFR 50.46. A spectrum analysis is performed and the worst case is used to establish allowable linear heat rates as a function of elevation in the core. (U.S.)

Triaxial- and uniaxial-compression testing methods developed for extraction of pore water from unsaturated tuff, Yucca Mountain, Nevada

Energy Technology Data Exchange (ETDEWEB)

Mower, T.E.; Higgins, J.D. [Colorado School of Mines, Golden, CO (USA). Dept. of Geology and Geological Engineering; Yang, I.C. [Geological Survey, Denver, CO (USA). Water Resources Div.

1989-12-31

To support the study of hydrologic system in the unsaturated zone at Yucca Mountain, Nevada, two extraction methods were examined to obtain representative, uncontaminated pore-water samples from unsaturated tuff. Results indicate that triaxial compression, which uses a standard cell, can remove pore water from nonwelded tuff that has an initial moisture content greater than 11% by weight; uniaxial compression, which uses a specifically fabricated cell, can extract pore water from nonwelded tuff that has an initial moisture content greater than 8% and from welded tuff that has an initial moisture content greater than 6.5%. For the ambient moisture conditions of Yucca Mountain tuffs, uniaxial compression is the most efficient method of pore-water extraction. 12 refs., 7 figs., 2 tabs.

Influence of alkali-silica reaction and crack orientation on the uniaxial compressive strength of concrete cores from slab bridges

DEFF Research Database (Denmark)

Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren; Hansen, Kurt Kielsgaard

2018-01-01

ASR-damaged flat slab bridges in service. Furthermore, the influence of the ASR-induced crack orientation on the compressive strength and the Young’s modulus is investigated. Uniaxial compression tests, visual observations, and thin section examinations were performed on more than 100 cores drilled...... from the three severely ASR-damaged flat slab bridges. It was found that the orientation of ASR-induced cracks has a significant influence on the uniaxial compressive strength and the stress-strain relationship of the tested cores. The compressive strength in a direction parallel to ASR cracks can...

Comparison of uniaxial and triaxial accelerometry in the assessment of physical activity among adolescents under free-living conditions: the HELENA study

Directory of Open Access Journals (Sweden)

Vanhelst Jérémy

2012-03-01

Full Text Available Abstract Background Different types of devices are available and the choice about which to use depends on various factors: cost, physical characteristics, performance, and the validity and intra- and interinstrument reliability. Given the large number of studies that have used uniaxial or triaxial devices, it is of interest to know whether the different devices give similar information about PA levels and patterns. The aim of this study was to compare physical activity (PA levels and patterns obtained simultaneously by triaxial accelerometry and uniaxial accelerometry in adolescents in free-living conditions. Methods Sixty-two participants, aged 13-16 years, were recruited in this ancillary study, which is a part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA. All participants wore a uniaxial accelerometer (ActiGraph GT1M®, Pensacola, FL and a triaxial accelerometer (RT3®, Stayhealthy, Monrovia, CA simultaneously for 7 days. The patterns were calculated by converting accelerometer data output as a percentage of time spent at sedentary, light, moderate, and vigorous PA per day. Analysis of output data from the two accelerometers were assessed by two different tests: Equivalence Test and Bland & Altman method. Results The concordance correlation coefficient between the data from the triaxial accelerometer and uniaxial accelerometer at each intensity level was superior to 0.95. The ANOVA test showed a significant difference for the first three lower intensities while no significant difference was found for vigorous intensity. The difference between data obtained with the triaxial accelerometer and the uniaxial monitor never exceeded 2.1% and decreased as PA level increased. The Bland & Altman method showed good agreement between data obtained between the both accelerometers (p Conclusions Uniaxial and triaxial accelerometers do not differ in their measurement of PA in population studies, and either could be used in such

Mechanical characterisation of porcine rectus sheath under uniaxial and biaxial tension.

LENUS (Irish Health Repository)

Lyons, Mathew

2014-06-03

Incisional hernia development is a significant complication after laparoscopic abdominal surgery. Intra-abdominal pressure (IAP) is known to initiate the extrusion of intestines through the abdominal wall, but there is limited data on the mechanics of IAP generation and the structural properties of rectus sheath. This paper presents an explanation of the mechanics of IAP development, a study of the uniaxial and biaxial tensile properties of porcine rectus sheath, and a simple computational investigation of the tissue. Analysis using Laplace׳s law showed a circumferential stress in the abdominal wall of approx. 1.1MPa due to an IAP of 11kPa, commonly seen during coughing. Uniaxial and biaxial tensile tests were conducted on samples of porcine rectus sheath to characterise the stress-stretch responses of the tissue. Under uniaxial tension, fibre direction samples failed on average at a stress of 4.5MPa at a stretch of 1.07 while cross-fibre samples failed at a stress of 1.6MPa under a stretch of 1.29. Under equi-biaxial tension, failure occurred at 1.6MPa with the fibre direction stretching to only 1.02 while the cross-fibre direction stretched to 1.13. Uniaxial and biaxial stress-stretch plots are presented allowing detailed modelling of the tissue either in silico or in a surrogate material. An FeBio computational model of the tissue is presented using a combination of an Ogden and an exponential power law model to represent the matrix and fibres respectively. The structural properties of porcine rectus sheath have been characterised and add to the small set of human data in the literature with which it may be possible to develop methods to reduce the incidence of incisional hernia development.

ROSA-III 200% double-ended break integral test RUN 901

International Nuclear Information System (INIS)

Nakamura, Hideo; Tasaka, Kanji; Koizumi, Yasuo; Anoda, Yoshinari; Kumamaru, Hiroshige; Murata, Hideo; Suzuki, Mitsuhiro; Shiba, Masayoshi

1984-02-01

This report presents the experimental data of RUN 901, a 200% double-ended break test at the recirculation pump suction line with the ROSA-III test facility. The ROSA-III test facility is a volumetrically scaled (1/424) system of the BWR/6. The facility has the electrically heated core, the break simulator and the scaled ECCS (Emergency Core Cooling System). The MSIV closure and the ECCS actuation were tripped by the liquid level in the upper downcomer. The channel inlet flows were measured by differential pressure transducers installed at the channel inlet orifices of the fuel assembly No.4. The PCT (Peak Cladding Temperature) was 780 K occured during the blowdown phase in RUN 901. The whole core was quenched after the ECCS actuation and the effectiveness of ECCS has been confirmed. (author)

Elastic properties of uniaxial-fiber reinforced composites - General features

Science.gov (United States)

Datta, Subhendu; Ledbetter, Hassel; Lei, Ming

The salient features of the elastic properties of uniaxial-fiber-reinforced composites are examined by considering the complete set of elastic constants of composites comprising isotropic uniaxial fibers in an isotropic matrix. Such materials exhibit transverse-isotropic symmetry and five independent elastic constants in Voigt notation: C(11), C(33), C(44), C(66), and C(13). These C(ij) constants are calculated over the entire fiber-volume-fraction range 0.0-1.0, using a scattered-plane-wave ensemple-average model. Some practical elastic constants such as the principal Young moduli and the principal Poisson ratios are considered, and the behavior of these constants is discussed. Also presented are the results for the four principal sound velocities used to study uniaxial-fiber-reinforced composites: v(11), v(33), v(12), and v(13).

Characteristics of Crushing Energy and Fractal of Magnetite Ore under Uniaxial Compression

Science.gov (United States)

Gao, F.; Gan, D. Q.; Zhang, Y. B.

2018-03-01

The crushing mechanism of magnetite ore is a critical theoretical problem on the controlling of energy dissipation and machine crushing quality in ore material processing. Uniaxial crushing tests were carried out to research the deformation mechanism and the laws of the energy evolution, based on which the crushing mechanism of magnetite ore was explored. The compaction stage and plasticity and damage stage are two main compression deformation stages, the main transitional forms from inner damage to fracture are plastic deformation and stick-slip. In the process of crushing, plasticity and damage stage is the key link on energy absorption for that the specimen tends to saturate energy state approaching to the peak stress. The characteristics of specimen deformation and energy dissipation can synthetically reply the state of existed defects inner raw magnetite ore and the damage process during loading period. The fast releasing of elastic energy and the work done by the press machine commonly make raw magnetite ore thoroughly broken after peak stress. Magnetite ore fragments have statistical self-similarity and size threshold of fractal characteristics under uniaxial squeezing crushing. The larger ratio of releasable elastic energy and dissipation energy and the faster energy change rate is the better fractal properties and crushing quality magnetite ore has under uniaxial crushing.

Mechanical interaction of Engineered Cementitious Composite (ECC) reinforced with Fiber Reinforced Polymer (FRP) rebar in tensile loading

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor; Jönsson, Jeppe

2010-01-01

This paper introduces a preliminary study of the composite interaction of Engineered Cementitious Composite (ECC), reinforced with Glass Fiber Reinforced Polymer (GFRP) rebar. The main topic of this paper will focus on the interaction of the two materials (ECC and GFRP) during axial loading......, particularly in post cracking phase of the concrete matrix. The experimental program carried out in this study examined composite behavior under monotonic and cyclic loading of the specimens in the elastic and inelastic deformation phases. The stiffness development of the composite during loading was evaluated...

Comparison of allele frequency for HLA-DR and HLA-DQ between patients with ECC and caries-free children

OpenAIRE

Bagherian A; Nematollahi H; Afshari J; Moheghi N

2008-01-01

Background: Early childhood caries (ECC) is one of the most common diseases of childhood. The etiology of ECC is multifactorial and both genetic and environmental factors play important roles in the pathogenesis of the disease. Genetic variations in the hosts may contribute to changes in the risk for dental caries. Genetic factors such as human leukocyte antigen (HLA) have recently been suggested as a predisposing factor. Aim: The aim of this study was to look for an association between HLA-D...

Factors predisposing to early childhood caries (ECC) in children of pre-school age in the city of Zagreb, Croatia.

Science.gov (United States)

Lulić-Dukić, O; Jurić, H; Dukić, W; Glavina, D

2001-06-01

The aim of this study was to investigate factors predisposing to early childhood caries (ECC) in pre-school children in the city of Zagreb, Croatia. The investigation was carried out on the sample of 145 children (77 boys and 68 girls) aged between 2 and 5 years, including clinical examination of dental status and survey on the habits among the parents. The overall prevalence of ECC was 30%: in girls it was 25%, and in boys 48%. The study on the risk factors was designed as a classic case-control study. The mean value of dmfs index among the cases amounted to 8.6, in comparison to 5.2 in the control group (pteeth-brushing habit after first 24 months did (p importance of early introduction of teeth-brushing and giving up the nightly consumption of sweet beverages in prevention of ECC.

Notch effects in uniaxial tension specimens

International Nuclear Information System (INIS)

Delph, T.J.

1979-03-01

Results of a literature survey on the effect of notches on the time-dependent failure of uniaxial tension specimens at elevated temperatures are presented. Particular attention is paid to the failure of notched specimens containing weldments

Evaluation report on SCTF Core-III Test S3-22

International Nuclear Information System (INIS)

Okubo, Tsutomu; Iguchi, Tadashi; Iwamura, Takamichi; Akimoto, Hajime; Ohnuki, Akira; Abe, Yutaka; Murao, Yoshio; Adachi, Hiromichi.

1991-07-01

Two tests (Tests S3-20 and S3-22) were conducted with JAERI's Slab Core Test Facility (SCTF) Core-III in order to investigate water break-through and core cooling behaviors under the intermittent ECC water delivery from the hot legs to one location in the upper plenum and the alternate ECC water delivery to two locations in the upper plenum during reflooding, respectively. This report presents an analysis on Test S3-22 (the alternate case). Subcooled ECC water was injected alternately just above the upper core support plate above Bundles 7 and 8 and Bundles 3 and 4. The total injection rate from both injection ports was the same as that in SCTF Test S3-20 and Test S3-13. Analyzing the test data together with those of Tests S3-13 and S3-20 the following has been found: (1) Alternate break-through occurred immediately corresponding to the alternate ECC water injection except for one period, during which no break-through was observed. However, there observed a difference in break-through behavior that break-through was strong above the low power region, whereas weak above the high power region. (2) Although its break-through behavior was different, nearly the same core cooling as in the continuous or intermittent ECC water delivery case was observed except for the period around quench. (3) Around quench time, degraded core cooling comparing to the continuous or intermittent ECC water delivery case was observed. That is, quench time at the midplane level of the present test was 35 s later than in the continuous case. This is considered to result from decrease in core water inventory caused by water sealing at the cross-over leg. (J.P.N.)

A provably-secure ECC-based authentication scheme for wireless sensor networks.

Science.gov (United States)

Nam, Junghyun; Kim, Moonseong; Paik, Juryon; Lee, Youngsook; Won, Dongho

2014-11-06

A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme) is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number of SUA-WSN schemes have been suggested in recent years, their intended security properties lack formal definitions and proofs in a widely-accepted model. One consequence is that SUA-WSN schemes insecure against various attacks have proliferated. In this paper, we devise a security model for the analysis of SUA-WSN schemes by extending the widely-accepted model of Bellare, Pointcheval and Rogaway (2000). Our model provides formal definitions of authenticated key exchange and user anonymity while capturing side-channel attacks, as well as other common attacks. We also propose a new SUA-WSN scheme based on elliptic curve cryptography (ECC), and prove its security properties in our extended model. To the best of our knowledge, our proposed scheme is the first SUA-WSN scheme that provably achieves both authenticated key exchange and user anonymity. Our scheme is also computationally competitive with other ECC-based (non-provably secure) schemes.

A Provably-Secure ECC-Based Authentication Scheme for Wireless Sensor Networks

Science.gov (United States)

Nam, Junghyun; Kim, Moonseong; Paik, Juryon; Lee, Youngsook; Won, Dongho

2014-01-01

A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme) is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number of SUA-WSN schemes have been suggested in recent years, their intended security properties lack formal definitions and proofs in a widely-accepted model. One consequence is that SUA-WSN schemes insecure against various attacks have proliferated. In this paper, we devise a security model for the analysis of SUA-WSN schemes by extending the widely-accepted model of Bellare, Pointcheval and Rogaway (2000). Our model provides formal definitions of authenticated key exchange and user anonymity while capturing side-channel attacks, as well as other common attacks. We also propose a new SUA-WSN scheme based on elliptic curve cryptography (ECC), and prove its security properties in our extended model. To the best of our knowledge, our proposed scheme is the first SUA-WSN scheme that provably achieves both authenticated key exchange and user anonymity. Our scheme is also computationally competitive with other ECC-based (non-provably secure) schemes. PMID:25384009

A Provably-Secure ECC-Based Authentication Scheme for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Junghyun Nam

2014-11-01

Full Text Available A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number of SUA-WSN schemes have been suggested in recent years, their intended security properties lack formal definitions and proofs in a widely-accepted model. One consequence is that SUA-WSN schemes insecure against various attacks have proliferated. In this paper, we devise a security model for the analysis of SUA-WSN schemes by extending the widely-accepted model of Bellare, Pointcheval and Rogaway (2000. Our model provides formal definitions of authenticated key exchange and user anonymity while capturing side-channel attacks, as well as other common attacks. We also propose a new SUA-WSN scheme based on elliptic curve cryptography (ECC, and prove its security properties in our extended model. To the best of our knowledge, our proposed scheme is the first SUA-WSN scheme that provably achieves both authenticated key exchange and user anonymity. Our scheme is also computationally competitive with other ECC-based (non-provably secure schemes.

Uniaxial ratcheting behavior of sintered nanosilver joint for electronic packaging

International Nuclear Information System (INIS)

Chen, Gang; Yu, Lin; Mei, Yunhui; Li, Xin; Chen, Xu; Lu, Guo-Quan

2014-01-01

Uniaxial ratcheting behavior and the fatigue life of sintered nanosilver joint were investigated at room temperature. All tests were carried out under stress-controlled mode. Force–displacement data were recorded during the entire fatigue lifespan by a non-contact displacement detecting system. Effects of stress amplitude, mean stress, stress rate, and stress ratio on the uniaxial ratcheting behavior of the sintered nanosilver joint were discussed. Stress-life (S–N) curves of the sintered joints were also obtained. The Smith–Watson–Topper (SWT) model, the Gerber model and the modified Goodman model, all of which took effect of mean stress into consideration, were compared for predicting the fatigue life of the sintered joint. Both the ratcheting strain and its rate increased with increasing stress amplitude or mean stress. The increase in stress amplitude and mean stress both reduced the fatigue life of the sintered joint, while the fatigue life prolonged with the increase in stress rate and stress ratio. The modified Goodman model predicted the fatigue life of the sintered joints well

Pressure vessel fracture studies pertaining to a PWR LOCA-ECC thermal shock: experiments TSE-1 and TSE-2

International Nuclear Information System (INIS)

Cheverton, R.D.

1976-09-01

The LOCA-ECC Thermal Shock Program was established to investigate the potential for flaw propagation in pressurized-water reactor (PWR) vessels during injection of emergency core coolant following a loss-of-coolant accident. Studies thus far have included fracture mechanics analyses of typical PWRs, the design and construction of a thermal shock test facility, determination of material properties for test specimens, and two thermal shock experiments with 0.53-m-OD (21-in.) by 0.15-m-wall (6-in.) cylindrical test specimens. The PWR calculations indicated that under some circumstances crack propagation could be expected and that experiments should be conducted for cracks that would have the potential for propagation at least halfway through the wall

Comparison between uniaxially and isostatically compacted bentonite

International Nuclear Information System (INIS)

Kalbantner, P.; Sjoeblom, R.; Boergesson, Lennart

2001-12-01

The purpose of the present report is to provide the Swedish Nuclear Fuel and Waste Management Company (SKB) with the knowledge base needed for their selection of reference method for manufacturing of bentonite blocks. The purpose is also to provide support for the direction of the further development work. Three types of blocks are compared in the present report: uniaxially compacted medium high blocks, isostatically compacted medium high blocks, isostatically compacted high blocks. The analyses is based on three process systems relating to the sequence of excavation of bentonite-transport-powder preparation-compaction-handling and emplacement of bentonite blocks. The need for further knowledge has been identified and documented in conjunction with these analyses. The comparison is primarily made with regard to the criteria safety/risk, quality/ technique and economy. It is carried out through identification of issues of significance and subsequent analysis and evaluation as well as more formally in a simplified AHP (AHP = Analytical Hierarchic Process). The result of the analyses is that the isostatic technique is applicable for the production of high as well as medium size blocks. The pressed blocks are assessed to fulfil the basic requirements with a very large margin. The result of the analyses is also that the uniaxial technique is applicable for the preparation of medium size blocks, which are assessed to fulfil the basic requirements with a large margin. The need for development and process control is assessed to be somewhat higher for the uniaxial technique. One example is the friction against the walls of the die during the compaction, including the significance of this friction for the development of stresses and discontinuities in the block. These results support a selection of the isostatic technique as the reference technique as it provides flexibility in the choice of block height. The uniaxial technique can form a second alternative if medium high

Assessment of some interfacial shear correlations in a model of ECC bypass flow in PWR reactor downcomer

International Nuclear Information System (INIS)

Popov, N.K.; Rohatgi, U.S.

1987-01-01

The bypass/refill process in the PWR reactor downcomer, following a large rupture of a cold leg coolant supply pipe, is a complicated thermo-hydraulic two-phase flow phenomenon. Mathematical modeling of such phenomena is always accompanied with a difficult task of selection of suitable constitutive correlations. In a typically hydrodynamic phenomenon, like ECC refill process of the reactor lower plenum is considered, the phasic interfacial friction is the most influential constitutive correlation. Therefore, assessment of the well-known widely-used interfacial friction constitutive correlations in the model of ECC bypass/refill process, is the subject of this paper

The E.C.C. programme in the field of radioactive wastes

International Nuclear Information System (INIS)

Orlowski, S.

1976-01-01

After a description of the aims of the E.C.C. in the field of radioactive wastes, the contents and the structure of the programme developed for this purpose as well as its time schedule and financing, are presented. The state of work progress and the first results of the actions taken, whose application is marked by an active cooperation of numerous national experts are quoted [fr

Field-Induced Rheology in Uniaxial and Biaxial Fields

International Nuclear Information System (INIS)

MARTIN, JAMES E.

1999-01-01

Steady and oscillatory shear 3-D simulations of electro- and magnetorheology in uniaxial and biaxial fields are presented, and compared to the predictions of the chain model. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. In a biaxial field, an opposite trend is seen, where Brownian motion decreases the stress most significantly at higher Mason numbers. to account for the uniaxial steady shear data they propose a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect. In oscillatory shear, a striped phase again appears in uniaxial field, at strain amplitudes greater than(approx) 0.15, and the presence of a shear slip zone creates strong stress nonlinearities at low strain amplitudes. In a biaxial field, a shear slip zone is not created, and so the stress nonlinearities develop only at expected strain amplitudes. The nonlinear dynamics of these systems is shown to be in good agreement with the Kinetic Chain Model

Nonparaxial propagation of Lorentz-Gauss beams in uniaxial crystal orthogonal to the optical axis.

Science.gov (United States)

Wang, Xun; Liu, Zhirong; Zhao, Daomu

2014-04-01

Analytical expressions for the three components of nonparaxial propagation of a polarized Lorentz-Gauss beam in uniaxial crystal orthogonal to the optical axis are derived and used to investigate its propagation properties in uniaxial crystal. The influences of the initial beam parameters and the parameters of the uniaxial crystal on the evolution of the beam-intensity distribution in the uniaxial crystal are examined in detail. Results show that the statistical properties of a nonparaxial Lorentz-Gauss beam in a uniaxial crystal orthogonal to the optical axis are closely determined by the initial beam's parameters and the parameters of the crystal: the beam waist sizes-w(0), w(0x), and w(0y)-not only affect the size and shape of the beam profile in uniaxial crystal but also determine the nonparaxial effect of a Lorentz-Gauss beam; the beam profile of a Lorentz-Gauss beam in uniaxial crystal is elongated in the x or y direction, which is determined by the ratio of the extraordinary refractive index to the ordinary refractive index; with increasing deviation of the ratio from unity, the extension of the beam profile augments. The results indicate that uniaxial crystal provides an effective and convenient method for modulating the Lorentz-Gauss beams. Our results may be valuable in some fields, such as optical trapping and nonlinear optics, where a light beam with a special profile and polarization is required.

Uniaxial and biaxial tensioning effects on thin membrane materials. [large space structures

Science.gov (United States)

Hinson, W. F.; Goslee, J. W.

1980-01-01

Thin laminated membranes are being considered for various surface applications on future large space structural systems. Some of the thin membranes would be stretched across or between structural members with the requirement that the membrane be maintained within specified limits of smoothness which would be dictated by the particular applications such as antenna reflector requirements. The multiaxial tensile force required to maintain the smoothness in the membrane needs to be determined for use in the structure design. Therefore, several types of thicknesses of thin membrane materials have been subjected to varied levels of uniaxial and biaxial tensile loads. During the biaxial tests, deviations of the material surface smoothness were measured by a noncontacting capacitance probe. Basic materials consisted of composites of vacuum deposited aluminum on Mylar and Kapton ranging in thickness from 0.00025 in (0.000635 cm) to 0.002 in (0.00508 cm). Some of the material was reinforced with Kevlar and Nomex scrim. The uniaxial tests determined the material elongation and tensile forces up to ultimate conditions. Biaxial tests indicated that a relatively smooth material surface could be achieved with tensile force of approximately 1 to 15 Newtons per centimeter, depending upon the material thickness and/or reinforcement.

Modifying the ECC-based grouping-proof RFID system to increase inpatient medication safety.

Science.gov (United States)

Ko, Wen-Tsai; Chiou, Shin-Yan; Lu, Erl-Huei; Chang, Henry Ker-Chang

2014-09-01

RFID technology is increasingly used in applications that require tracking, identification, and authentication. It attaches RFID-readable tags to objects for identification and execution of specific RFID-enabled applications. Recently, research has focused on the use of grouping-proofs for preserving privacy in RFID applications, wherein a proof of two or more tags must be simultaneously scanned. In 2010, a privacy-preserving grouping proof protocol for RFID based on ECC in public-key cryptosystem was proposed but was shown to be vulnerable to tracking attacks. A proposed enhancement protocol was also shown to have defects which prevented proper execution. In 2012, Lin et al. proposed a more efficient RFID ECC-based grouping proof protocol to promote inpatient medication safety. However, we found this protocol is also vulnerable to tracking and impersonation attacks. We then propose a secure privacy-preserving RFID grouping proof protocol for inpatient medication safety and demonstrate its resistance to such attacks.

Experimental Studies on Strength Behaviour of Notched Glass/Epoxy Laminated Composites under Uni-axial and Bi-axial Loading

Science.gov (United States)

Guptha, V. L. Jagannatha; Sharma, Ramesh S.

2017-11-01

The use of FRP composite materials in aerospace, aviation, marine, automotive and civil engineering industry has increased rapidly in recent years due to their high specific strength and stiffness properties. The structural members contrived from such composite materials are generally subjected to complex loading conditions and leads to multi-axial stress conditions at critical surface localities. Presence of notches, much required for joining process of composites, makes it further significant. The current practice of using uni-axial test data alone to validate proposed material models is inadequate leading to evaluation and consideration of bi-axial test data. In order to correlate the bi-axial strengths with the uni-axial strengths of GFRP composite laminates in the presence of a circular notch, bi-axial tests using four servo-hydraulic actuators with four load cells were carried out. To determine the in-plane strength parameters, bi-axial cruciform test specimen model was considered. Three different fibre orientations, namely, 0°, 45°, and 90° are considered with a central circular notch of 10 mm diameter in the present investigation. From the results obtained, it is observed that there is a reduction in strength of 5.36, 2.41 and 13.92% in 0°, 45°, and 90° fibre orientation, respectively, under bi-axial loading condition as compared to that of uni-axial loading in laminated composite.

Uniaxially stressed Ge:Ga and Ge:Be

Energy Technology Data Exchange (ETDEWEB)

Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

1992-12-01

The application of a large uniaxial stress to p-type Ge single crystals changes the character of both the valence band and the energy levels associated with the acceptors. Changes include the splitting of the fourfold degeneracy of the valence band top and the reduction of the ionization energy of shallow acceptors. In order to study the effect of uniaxial stress on transport properties of photoexcited holes, a variable temperature photo-Hall effect system was built in which stressed Ge:Ga and Ge:Be could be characterized. Results indicate that stress increases the lifetime and Hall mobility of photoexcited holes. These observations may help further the understanding of fundamental physical processes that affect the performance of stressed Ge photoconductors including the capture of holes by shallow acceptors.

Enhanced electron-lattice coupling under uniaxial stress in layered double hydroxides intercalated with samarium complexes

International Nuclear Information System (INIS)

Park, Ta-Ryeong

2004-01-01

We have applied uniaxial stress to samarium complexes by intercalating them into the gallery of a layered material and by using a diamond-anvil cell at 28 K. Although uniaxial stress reduces symmetry and removes degeneracy, the overall number of photoluminescence (PL) peaks evidently decreased with the application of uniaxial stress. This contradictory observation is explained by an increased electron-lattice coupling strength under uniaxial stress. This behavior is also confirmed by time-resolved PL data.

Thermal effects on the enhanced ductility in non-monotonic uniaxial tension of DP780 steel sheet

Science.gov (United States)

Majidi, Omid; Barlat, Frederic; Korkolis, Yannis P.; Fu, Jiawei; Lee, Myoung-Gyu

2016-11-01

To understand the material behavior during non-monotonic loading, uniaxial tension tests were conducted in three modes, namely, the monotonic loading, loading with periodic relaxation and periodic loading-unloadingreloading, at different strain rates (0.001/s to 0.01/s). In this study, the temperature gradient developing during each test and its contribution to increasing the apparent ductility of DP780 steel sheets were considered. In order to assess the influence of temperature, isothermal uniaxial tension tests were also performed at three temperatures (298 K, 313 K and 328 K (25 °C, 40 °C and 55 °C)). A digital image correlation system coupled with an infrared thermography was used in the experiments. The results show that the non-monotonic loading modes increased the apparent ductility of the specimens. It was observed that compared with the monotonic loading, the temperature gradient became more uniform when a non-monotonic loading was applied.

ECCE Toolkit: Prototyping Sensor-Based Interaction

Directory of Open Access Journals (Sweden)

Andrea Bellucci

2017-02-01

Full Text Available Building and exploring physical user interfaces requires high technical skills and hours of specialized work. The behavior of multiple devices with heterogeneous input/output channels and connectivity has to be programmed in a context where not only the software interface matters, but also the hardware components are critical (e.g., sensors and actuators. Prototyping physical interaction is hindered by the challenges of: (1 programming interactions among physical sensors/actuators and digital interfaces; (2 implementing functionality for different platforms in different programming languages; and (3 building custom electronic-incorporated objects. We present ECCE (Entities, Components, Couplings and Ecosystems, a toolkit for non-programmers that copes with these issues by abstracting from low-level implementations, thus lowering the complexity of prototyping small-scale, sensor-based physical interfaces to support the design process. A user evaluation provides insights and use cases of the kind of applications that can be developed with the toolkit.

Modeling of uniaxial ratchetting behavior of SA333 carbon manganese steel

International Nuclear Information System (INIS)

Shit, J.; Dhar, S.; Acharyya, S.K.; Goyal, S.

2012-01-01

The paper deals with uniaxial ratcheting phenomenon of cyclic plasticity behavior of the materials SA333 carbon Manganese steel. A mechanistic model for the ratcheting phenomenon has been proposed. It is observed that von Mises yield criterion together with Chaboche’s kinematic hardening rules are not sufficient to model ratcheting phenomenon. Other associated phenomena like plastic strain memory surface, back stress memory points and over all the extra hardening behavior have to be incorporated to get a complete material model for ratcheting. The proposed model assembled all these ideas together with von Mises yield criterion and Chabache’s kinematic hardening rule. Low cycle fatigue tests and uniaxial ratcheting tests have been conducted for the materials. The material constants are identified and derived from experimental results. The ratcheting coefficients have been properly calibrated with these material constants. The material model, as mentioned above, for the ratcheting phenomenon has been implemented in an elastic plastic finite element code. The ratcheting results for different stress controlled ratcheting loads have been computed. The good feature of this model is that it reduces to symmetric low cycle fatigue model when loop closes. - Highlights: ► A common material model to simulate symmetric LCF and ratcheting. ► Extra hardening to take care the shift of plastic strain centre. ► Material parameters from tensile and LCF tests. ► Saturated loop in LCF and ratcheting strain rate is compared with experiment. ► Consideration of loading path, memory path and their directions.

Evaluation report on SCTF Core-III test S3-06

International Nuclear Information System (INIS)

Iwamura, Takamichi; Iguchi, Tadashi; Akimoto, Hajime; Okubo, Tsutomu; Ohnuki, Akira; Adachi, Hiromichi; Murao, Yoshio; Minato, Akihiko; Sakaki, Isao.

1988-10-01

In order to investigate the effect of radial power distribution on the thermal-hydraulic characteristics during the reflood phase of a PWR-LOCA with a combined injection type ECCS, a core cooling separate effect test S3-06 and a combined injection test S3-16-Phase 2 were performed using the Slab Core Test Facility (SCTF) Core-III. The radial power distributions in these two tests simulated a reference distribution for a PWR with a combined injection type ECCS and a steep distribution for a PWR with a cold leg injection type ECCS, respectively. Under the radial power distribution of a PWR with a combined injection type ECCS, the radial power distribution had little effect on the thermal-hydraulic behavior in the two-phase up-flow region due to the approximately flat power distribution in this region (power ratio = 1.04 ∼ 1.08). The overall fluid behavior in the pressure vessel was also little affected by the radial power distribution. On the other hand, under the steep radial power distribution (peak power ratio = 1.36), the degree of heat transfer enhancement in high power bundles in the two-phase up-flow region was dominated by the bundlewise radial power ratio as in the case of a PWR with a cold leg injection type ECCS. (author)

Shear punch tests performed using a new low compliance test fixture

International Nuclear Information System (INIS)

Toloczko, M.B.; Kurtz, R.J.; Hasegawa, A.; Abe, K.

2002-01-01

Based on a recent finite element analysis (FEA) study performed on the shear punch test technique, it was suggested that compliance in a test frame and fixturing which is quite acceptable for uniaxial tensile tests, is much too large for shear punch tests. The FEA study suggested that this relatively large compliance was masking both the true yield point and the shape of the load versus displacement trace obtained in shear punch tests. The knowledge gained from the FEA study was used to design a new shear punch test fixture which more directly measures punch tip displacement. The design of this fixture, the traces obtained from this fixture, and the correlation between uniaxial yield stress and shear yield stress obtained using this fixture are presented here. In general, traces obtained from the new fixture contain much less compliance resulting in a trace shape which is more similar in appearance to a corresponding uniaxial tensile trace. Due to the more direct measurement of displacement, it was possible to measure yield stress at an offset shear strain in a manner analogous to yield stress measurement in a uniaxial tensile test. The correlation between shear yield and uniaxial yield was altered by this new yield measurement technique, but the new correlation was not as greatly improved as was suggested would occur from the FEA study

Factors Predisposing to Early Childhood Caries (ECC) in Children of Pre-School Age in the City of Zagreb, Croatia

OpenAIRE

Lulić-Dukić, O.; Jurić, H.; Dukić, W.; Glavina, D.

2001-01-01

The aim of this study was to investigate factors predisposing to early childhood caries (ECC) in pre-school children in the city of Zagreb, Croatia. The investigation was carried out on the sample of 145 children (77 boys and 68 girls) aged between 2 and 5 years, including clinical examination of dental status and survey on the habits among the parents. The overall prevalence of ECC was 30%: in girls it was 25%, and in boys 48%. The study on the risk factors was designed as a c...

Plain-Woven, 600-Denier Kevlar KM2 Fabric Under Quasistatic, Uniaxial Tension

Science.gov (United States)

2005-03-01

respectively, along the direction of applied tensile loading, and Sfail and Efail denote the values corresponding to material failure. 2.2 Least...uniaxial tension along the fill direction. 7 Table 1. Failure strain and failure stress (strength) from each test. Test Efail Sfail (GPa) W1 0.122633...14539.8 7214.87 d (GPa) –4898.41 –10674.6 –33428.5 –14475.3 e –22.0527 –15.6910 –34.3400 –28.6378 f 465.297 476.711 2137.94 1266.84 Efail 0.132930

Study on Relaxation Damage Properties of High Viscosity Asphalt Sand under Uniaxial Compression

Directory of Open Access Journals (Sweden)

Yazhen Sun

2018-01-01

Full Text Available Laboratory investigations of relaxation damage properties of high viscosity asphalt sand (HVAS by uniaxial compression tests and modified generalized Maxwell model (GMM to simulate viscoelastic characteristics coupling damage were carried out. A series of uniaxial compression relaxation tests were performed on HVAS specimens at different temperatures, loading rates, and constant levels of input strain. The results of the tests show that the peak point of relaxation modulus is highly influenced by the loading rate in the first half of an L-shaped curve, while the relaxation modulus is almost constant in the second half of the curve. It is suggested that for the HVAS relaxation tests, the temperature should be no less than −15°C. The GMM is used to determine the viscoelastic responses, the Weibull distribution function is used to characterize the damage of the HVAS and its evolution, and the modified GMM is a coupling of the two models. In this paper, the modified GMM is implemented through a secondary development with the USDFLD subroutine to analyze the relaxation damage process and improve the linear viscoelastic model in ABAQUS. Results show that the numerical method of coupling damage provides a better approximation of the test curve over almost the whole range. The results also show that the USDFLD subroutine can effectively predict the relaxation damage process of HVAS and can provide a theoretical support for crack control of asphalt pavements.

MICROORGANISMS FOUND IN SECONDARY CATARACT MATERIAL OF ECCE PATIENTS, A STUDY WITH SEM AND TEM

NARCIS (Netherlands)

KALICHARAN, D; JONGEBLOED, WL; LOS, LI; WORST, JGF

1993-01-01

Globular secondary cataract material, removed from 24 patients with ECCE after ophthalmic cleaning of the anterior capsule, were investigated with SEM and TEM. Besides spherical, somewhat oval shaped bodies of various shape and size comparable with those found in cataractous lenses, (an)aerobic

UPTF test 21D counterpart test in the MIDAS test facility

International Nuclear Information System (INIS)

Yoon, B. C.; Ah, D. J.; Joo, I. C.; Kwon, T. S.; Park, W. M.; Song, C. H.

2002-01-01

This paper describes the experimental results of UPTF Test 21D counterpart tests in the downcomer during the late reflood phase of LBLOCA. The experiments have been performed in the MIDAS test facility using superheated steam and water. The test condition was determined,based on the test results of UPTF Test 21D, by applying the 'modified linear scaling method of 1/4.077 length scale. The tests of ECC direct bypass and void height are performed separately to estimate each phenomena quantitatively. The tests were carried out by varying the injection steam flow rate of intact cold legs widely to investigate the effect of steam flow rate on the direct bypass fraction and void height. In the tests, separate effect tests have been performed in cases of DVI-1,DVI- 2 and DVI-1 and 2 injections to see the direct bypass fraction according to the DVI nozzle combination. From the tests, we found that the fraction of direct ECC bypass and the void height observed in the MIDAS test facility reasonably well agree with those of UPTF test 21- D. It confirms that the applied 'modified linear scaling law' reproduces major thermal hydraulics phenomena in the downcomer during the LBLOCA reflood phase

Soft computing methods for estimating the uniaxial compressive strength of intact rock from index tests

Czech Academy of Sciences Publication Activity Database

Mishra, A. Deepak; Srigyan, M.; Basu, A.; Rokade, P. J.

2015-01-01

Roč. 80, December 2015 (2015), s. 418-424 ISSN 1365-1609 Institutional support: RVO:68145535 Keywords : uniaxial compressive strength * rock indices * fuzzy inference system * artificial neural network * adaptive neuro-fuzzy inference system Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 2.010, year: 2015 http://ac.els-cdn.com/S1365160915300708/1-s2.0-S1365160915300708-main.pdf?_tid=318a7cec-8929-11e5-a3b8-00000aacb35f&acdnat=1447324752_2a9d947b573773f88da353a16f850eac

Combined group ECC protection and subgroup parity protection

Science.gov (United States)

Gara, Alan G.; Chen, Dong; Heidelberger, Philip; Ohmacht, Martin

2013-06-18

A method and system are disclosed for providing combined error code protection and subgroup parity protection for a given group of n bits. The method comprises the steps of identifying a number, m, of redundant bits for said error protection; and constructing a matrix P, wherein multiplying said given group of n bits with P produces m redundant error correction code (ECC) protection bits, and two columns of P provide parity protection for subgroups of said given group of n bits. In the preferred embodiment of the invention, the matrix P is constructed by generating permutations of m bit wide vectors with three or more, but an odd number of, elements with value one and the other elements with value zero; and assigning said vectors to rows of the matrix P.

Prosthetic Oral Rehabilitation of a Child With S-ECC: A Case Report with Histopathologic Analysis.

Science.gov (United States)

Tannure, P N; Moraes, G G; Borba, McU; Abrahão, A; Andrade, Mtrc; Fidalgo, Tks

2015-01-01

The aim of this case report is to describe the treatment planning of a young child with severe early childhood caries (S-ECC) as well as the prosthetic rehabilitation technique. A 3-year-old female child was referred to the pediatric dentistry clinic with the chief complaint of tooth pain, difficulty in eating and recurrent hospitalizations caused by dental infections. The mother reported intermittent episodes of fever and recurrent swelling of child's face. The girl presented angular cheilitis and was referred to a dietitian. The treatment plain consisted on a behavior changes in oral hygiene habits, exodontias of all primary teeth and oral rehabilitation with a prosthesis. The extracted teeth with periapical lesions were submitted to histopathologic analysis (hematoxilin and eosin staining) and revealed an inflammatory infiltrate. The aesthetic requirement of children with S-ECC has been a challenge to pediatric dentists. In the present case, the oral rehabilitation provided for the children better aesthetic, nutrition, phonation, and functional conditions.

Refractive indices of K2ZnCl4 crystals in an incommensurate phase under uniaxial stresses

International Nuclear Information System (INIS)

Gaba, V.M.; Kogut, Z.O.; Brezvin, R.S.; Stadnik, V.I.

2010-01-01

The influence of uniaxial mechanical stresses directed along the principal crystallophysical axes on refractiveindex temperature dependences in K 2 ZnCl 4 crystals was studied. It is established that the refractive indices ni are quite sensitive to uniaxial stresses. Significant baric shifts of the paraphase-incommensurate-commensurate phase transition points to different temperature regions were observed, which is due to the effect of the uniaxial stress on the K 2 ZnCl 4 crystal structure. It is found that applying uniaxial pressure increases the value of the temperature hysteresis of the commensurate-incommensurate phase transition. (authors)

ROSA-III 100 % break integral test Run 914

International Nuclear Information System (INIS)

Yonomoto, Taisuke; Tasaka, Kanji; Koizumi, Yasuo; Anoda, Yoshinari; Kumamaru, Hiroshige; Nakamura, Hideo; Suzuki, Mitsuhiro; Murata, Hideo

1987-05-01

This report presents the experimental data of RUN 914 conducted at the ROSA-III test facility. The facility is a volumetrically scaled (1/424) simulator for a BWR/6 with the electrically heated core, the break simulator and the scaled ECCS (emergency core cooling system). RUN 914 was a 100% split break test at the recirculation pump suction line with an assumption of HPCS diesel generator failure and conducted as one of the break area parameter tests. A peak cladding temperature (PCT) of 851 K was reached at 130 s after the break during the reflooding phase. Whole core was completely quenched by ECCS, and the effectiveness of ECCS was confirmed. The primary test results of RUN 914 are compared in this report with those of RUN 926, which was a 200 % double-ended break test. The initiation of core dryout in RUN 914 was almost the same as that in RUN 926. Duration of core dryourt was, however, longer in RUN 914 because of later actuation of ECCSs. PCT in RUN 914 was 67 K higher than that in RUN 926. (author)

Analysis of surface roughening behavior of 6063 aluminum alloy by tensile testing of a trapezoidal uniaxial specimen

Energy Technology Data Exchange (ETDEWEB)

Cai, Yang [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150090 (China); Wang, Xiaosong, E-mail: hitxswang@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150090 (China); National Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Yuan, Shijian [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150090 (China); National Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

2016-08-30

To determine the quantitative relationship between surface roughness and strain, the surface roughening behavior of a 6063 aluminum alloy tube was examined by tensile testing of a trapezoidal uniaxial specimen, that can provide a continuous strain distribution after tensile deformation. The surface roughness was measured using a laser scanning confocal microscope to reflect the degree of roughening. The microstructure and surface morphology were examined using electron back-scattered diffraction and in-situ scanning electron microscopy to determine the grain orientation and surface topography evolution. The surface roughness increased with strain when the strain was less than 0.067 and then decreased slightly, with a maximum surface roughness of 23.73 µm. Inhomogeneous deformation at the grain boundaries and inside the grains was enhanced with increasing strain, resulting in an increase of surface roughness when the strain was below a critical value. As the strain increased, a greater number of slip systems contributed to the further deformation. Thus, the strain became more homogeneous, and accordingly, the surface roughness slightly decreased.

AN ANALYSIS OF STUDENTS’ SPEAKING ABILITY IN ENGLISH CONVERSATION CLUB (ECC PROGRAM AT THE 3rd SEMESTER

Directory of Open Access Journals (Sweden)

M. Fadhly Farhy Abbas

2017-07-01

Full Text Available This research is based on students’ speaking ability who had followed the EnglishConversation Club (ECC program especially for the third semester of English Department. Thepurpose of this study was to analyze the students’ speaking ability at the 3rd semester in the EnglishConversation Club FKIP UNILAK Pekanbaru. The type of the research was mixed method in typeof explanatory design. The number of participant was 53 students. The researcher used twoinstruments, those were test and interview. In analyzing the data, it used in descriptive statistics.The result of the analysis showed that the average score of 3rd semester students’ speaking abilitywas 45.42. It can be concluded that the students’ speaking ability was categorized into failed . Thescore of Standard Deviation was 7.02, Variance was 49.30, and Range was 36 points . It meansthat the students’ speaking ability was homogeneous. According to the Z-Score, it can be seen that49.06% students’ ability was higher than average and 50.94% students ability was below theaverage. In conclusion, the students’ ability in learning speaking English was failed, it had beenaffected by some factors, those were lack of vocabulary, grammar and motivation. It was supportedby the interview, eventhough the students’ perception to English Conversation Club (ECCprogram was positive, but in fact, the students’ frequency to speak English was seldom, they wereless practice speaking English everyday.Keywords : Speaking , English Conversation Club (ECC

Complete genome sequences of Escherichia coli strains 1303 and ECC-1470 isolated from bovine mastitis

NARCIS (Netherlands)

Leimbach, Andreas; Poehlein, Anja; Witten, Anika; Scheutz, Flemming; Schukken, Ynte|info:eu-repo/dai/nl/075051907; Daniel, Rolf; Dobrindt, Ulrich

2016-01-01

Escherichia coli is the leading causative agent of acute bovine mastitis. Here, we report the complete genome sequence of E. coli O70:H32 strain 1303, isolated from an acute case of bovine mastitis, and E. coli Ont:Hnt strain ECC-1470, isolated from a persistent infection.

Switching the uniaxial magnetic anisotropy by ion irradiation induced compensation

Science.gov (United States)

Yuan, Ye; Amarouche, Teyri; Xu, Chi; Rushforth, Andrew; Böttger, Roman; Edmonds, Kevin; Campion, Richard; Gallagher, Bryan; Helm, Manfred; Jürgen von Bardeleben, Hans; Zhou, Shengqiang

2018-04-01

In the present work, the uniaxial magnetic anisotropy of GaMnAsP is modified by helium ion irradiation. According to the micro-magnetic parameters, e.g. resonance fields and anisotropy constants deduced from ferromagnetic resonance measurements, a rotation of the magnetic easy axis from out-of-plane [0 0 1] to in-plane [1 0 0] direction is achieved. From the application point of view, our work presents a novel avenue in modifying the uniaxial magnetic anisotropy in GaMnAsP with the possibility of lateral patterning by using lithography or focused ion beam.

Experiment data of 200% recirculation pump discharge line break integral test run 961 with HPCS failure at ROSA-III and comparison with results of suction line break tests

International Nuclear Information System (INIS)

Suzuki, Mitsuhiro; Tasaka, Kanji; Nakamura, Hideo; Anoda, Yoshinari; Kumamaru, Hiroshige; Murata, Hideo; Yonomoto, Taisuke; Shiba, Masayoshi

1984-03-01

This report presents the experimental data of RUN 961, a 200% double-ended break test at the recirculation pump discharge line in the ROSA-III test facility. The ROSA-III test facility is a volumetrically scaled (1/424) system of the BWR/6. The facility has the electrically heated core, the break simulator and the scaled ECCS (Emergency Core Cooling System). The MSIV (Main Steam Isolation Valve) closure and the ECCS actuation were tripped by the liquid level in the upper downcomer. The PCT (Peak Cladding Temperature) was 894 K, which was 107 K higher than a 200% pump suction line break test (RUN 926) due to the smaller depressurization rate. The effect of break location on transient LOCA phenomena was clarified by comparing the discharge and suction break tests. The whole core was quenched 71 s after LPCI actuation and the effectiveness of ECCS has been confirmed. (author)

Numerical study of hot-leg ECC injection into the upper plenum of a pressurized water reactor

International Nuclear Information System (INIS)

Daly, B.J.; Torrey, M.D.; Rivard, W.C.

1981-01-01

In certain pressurized water reactor (PWR) designs, emergency core coolant (ECC) is injected through the hot legs into the upper plenum. The condensation of steam on this subcooled liquid stream reduces the pressure in the hot legs and upper plenum and thereby affects flow conditions throughout the reactor. In the present study, we examine countercurrent steam-water flow in the hot leg to determine the deceleration of the ECC flow that results from an adverse pressure gradient and from momentum exchange from the steam by interfacial drag and condensation. For the parameters examined in the study, water flow reversal is observed for a pressure drop of 22 to 32 mBar over the 1.5 m hot leg. We have also performed a three-dimensional study of subcooled water injection into air and steam environments of the upper plenum. The ECC water is deflected by an array of cylindrical guide tubes in its passage through the upper plenum. Comparisons of the air-water results with data obtained in a full scale experiment shows reasonable agreement, but indicates that there may be too much resistance to horizontal flow about the columns because of the use of a stair-step representation of the cylindrical guide tube cross section. Calculations of flow past single columns of stair-step, square and circular cross section do indicate excessive water deeentrainment by the noncircular column. This has prompted the use of an arbitrary mesh computational procedure to more accuratey represent the circular cross-section guide tubes. 15 figures

Crystallinity of polyethylene in uni-axial extensional flow

DEFF Research Database (Denmark)

Wingstrand, Sara Lindeblad; van Drongelen, Martin; Mortensen, Kell

Flow history of polymer melts in processing greatly influences the crystallinity and hence the solid properties of the final material. A wide range of polymer processes involve extensional flows e.g. fiber spinning, blow moulding etc. However, due to instrumental difficulties, experimental studies...... on polymer crystallization in controlled uniaxial extension are quite rare compared to studies of crystallization in shear. Inherently uniaxial extensional flows are strong and simple relative to shear flows, in the sense that chain stretch is easily obtained and that the molecules experience no tumbling...... such that crystallization from a stretched state can take place. In this work we explore this feature in the attempt to link the nonlinear extensional rheology to the final morphology. We investigate polyethylenes (PE) of various chain architectures and observe that, even for complex architectures like long chain branched...

Performance-based ECCS cladding acceptance criteria: A new simulation approach

International Nuclear Information System (INIS)

Zoino, A.; Alfonsi, A.; Rabiti, C.; Szilard, R.H.; Giannetti, F.; Caruso, G.

2017-01-01

Highlights: • A new methodology to demonstrate compliance with the new ECCS acceptance criteria is described. • A wide spectrum of fuel rod initial burnup states can be analysed in the design phase. • The coupled suite PHISICS/RELAP5-3D has been used in the analyses. • A demo simulation of the equilibrium cycle, load-following and a LOCA analysis has been performed. - Abstract: The U.S. Nuclear Regulatory Commission is currently proposing rulemaking to revise the Loss Of Coolant Accident (LOCA) and therefore the Emergency Core Cooling System (ECCS) acceptance criteria, to include the effects of higher burnup on cladding performance as well as to address other technical issues. As motivated by the new rule, the need to use advanced cladding designs may be a result. A loss of operational margin may result due to the more restrictive cladding embrittlement criteria. Initial and future compliance with the rule may significantly increase vendor workload and licensee cost, as a spectrum of fuel rod initial burnup states may need to be analyzed to demonstrate compliance. Consequently, there will be an increased focus on licensee decision making related to LOCA analysis to minimize cost and impact, and to manage margin. The study here presented has been part of a big project used to investigate technical issues and approaches for future industrial applications within the Risk-Informed Safety Margin Characterization (RISMC) Pathway. Specifically, the primary aim of this study is to lay out a roadmap to demonstrate the application of the new methodology. The present analysis shows a simplified version of the methodology of an industrial application on the Core Design and the Multi-Cycle Analysis.

Influence of Simulated Acid Rain Corrosion on the Uniaxial Tensile Mechanical Properties of Concrete

Directory of Open Access Journals (Sweden)

Ying-zi Zhang

2012-01-01

Full Text Available An experimental study on the uniaxial tensile property of concrete exposed to the acid rain environment was carried out. Acid rain with pH level of 1.0 was deposed by the mixture of sulfate and nitric acid solution in the laboratory. Dumbbell-shaped concrete specimens were immersed in the simulated acid rain completely. After being exposed to the deposed mixture for a certain period, uniaxial tensile test was performed on the concrete specimens. The results indicate that elastic modulus, tensile strength, and peak strain have a slight increase at the initial corrosion stage, and with the extension of corrosion process, elastic modulus and tensile strength decrease gradually, while the peak strain still increases. It is found that the compressive strength is more sensitive than the tensile strength in aggressive environment. Based on the experimental results, an equation was proposed to describe the ascending branch of the stress-strain curve of the concrete corroded by acid rain.

Effect of Fiber Reinforcement on the Response of Structural Members

DEFF Research Database (Denmark)

Fischer, Gregor; Li, Victor

2007-01-01

This paper describes a series of investigations on the effect of fiber reinforcement on the response of structural members in direct tension and flexure under reversed cyclic loading conditions. The design approach of the fiber reinforced cementitious composite is based on fracture mechanics...... principles, which will be described in the first part of the paper along with an introduction of the relevant material properties of the resulting engineered cementitious composite (ECC). This class of composites is characterized by strain hardening and multiple cracking properties in uniaxial tension...... and an ultimate tensile strain capacity on the order of several percent. Subsequently, the synergistic effects of composite deformation mechanisms in the ECC and structural members subjected to large shear reversals are identified. Beneficial effects observed in the reinforced ECC structural members as compared...

Risk-based assessment of the allowable outage times for the unit 1 leningrad nuclear power plant ECCS components

International Nuclear Information System (INIS)

Koukhar, Sergey; Vinnikov, Bronislav

2009-01-01

Present paper describes a method for risk - informed assessment of the Allowable Outage Times (AOTs). The AOT is the time, when components of a safety system allowed to be out of service during power operation or during shutdown operation off a plant. If the components are not restored during the time, the plant in operation must be shut down or the plant in a given shutdown mode has to go to safer shutdown mode. Application of the method is also provided for the equipment of the Unit 1 Leningrad NPP ECCS components. For solution of the problem it is necessary to carry out two series of computations using a Living PSA model, level 1. In the first series of the computations the core damage frequency (CDFb) for the base configuration of the plant is determined (there is no equipment out of service). Here the symbol 'b' means the base configuration of a plant. In the second series of the computations the core damage frequency (CDFi) for the configuration of the plant with the component (which is out of service) is calculated. That is here CDFi is determined for the failure probability of the component equal to 1.0 (component 'i' is unavailable). Then it is necessary to determine so called Risk Increase Factor (RIF) using the following ratio: RIFi = CDFi / CDFb. At last the AOT is calculated with the help of the ratio: AOTi = Tppr / RIFi, where Tppr is a period of time between two Planned Preventive Repairs (PPRs). 1. Using the risk based approach the AOTs were calculated for a set of the components of the Unit 1 Leningrad NPP ECCS components. 2. The main conclusion from the analysis is that the current deterministic AOTs for the ECCS components are conservative and should be extended. 3. The risk based extension of the AOTs for the ECCS components can prevent the Unit 1 Leningrad NPP to enter into the operating modes with increased risk. (author)

Compressive Properties of PTFE/Al/Ni Composite Under Uniaxial Loading

Science.gov (United States)

Wang, Huai-xi; Li, Yu-chun; Feng, Bin; Huang, Jun-yi; Zhang, Sheng; Fang, Xiang

2017-05-01

To investigate the mechanical properties of pressed and sintered PTFE/Al/Ni (polytetrafluoroethylene/aluminum/nickel) composite, uniaxial quasi-static and dynamic compression experiments were conducted at strain rates from 10-2 to 3 × 103/s. The prepared samples were tested by an electrohydraulic press with 300 kN loading capacity and a split Hopkinson pressure bar (SHPB) device at room temperature. Experimental results show that PTFE/Al/Ni composite exhibits evident strain hardening and strain rate hardening. Additionally, a bilinear relationship between stress and {{log(}}\\dot{ɛ} ) is observed. The experimental data were fit to Johnson-Cook constitutive model, and the results are in well agreement with measured data.

Uniaxial Pressure Effect on the SdH Oscillations in Heavy-Fermion Semimetal CeRu4Sb12

International Nuclear Information System (INIS)

Saha, S. R.; Kobayashi, M.; Sugawara, H.; Namiki, T.; Abe, K.; Aoki, Y.; Sato, H.

2003-01-01

We report the first successful Shubnikov-de Haas (SdH) experiment under uniaxial pressure in the anomalous heavy-fermion semimetal CeRu 4 Sb 12 . The nature of the quantum oscillations in the magnetoresistance is found to be significantly sensitive to uniaxial pressure. The results reveal that the nearly spherical Fermi surface elongates along the direction of the uniaxial pressure. (author)

Audit of ECCS Availability for CANDU Reactors with an extended O/H interval

Energy Technology Data Exchange (ETDEWEB)

Choi, Jong Soo [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2011-10-15

KINS conducts regulatory periodic inspections of the safety and performance of each nuclear installation during the planned outage every 20 months, pursuant to the Atomic Energy Act. For CANDU reactors, planned outage or overhaul (O/H) have been performed every 15 months. KHNP has been making efforts to extend the O/H intervals of CANDU reactors into 20 months since 2001. Low ECCS availability is one of the regulatory pending issues in the related licensing

Determination of deformation and strength characteristics of artificial geomaterial having step-shaped discontinuities under uniaxial compression

Science.gov (United States)

Tsoy, PA

2018-03-01

In order to determine the empirical relationship between the linear dimensions of step-shaped macrocracks in geomaterials as well as deformation and strength characteristics of geomaterials (ultimate strength, modulus of deformation) under uniaxial compression, the artificial flat alabaster specimens with the through discontinuities have been manufactured and subjected to a series of the related physical tests.

ROSA-III 50 % break integral test RUN 916

International Nuclear Information System (INIS)

Yonomoto, Taisuke; Tasaka, Kanji; Koizumi, Yasuo; Anoda, Yoshinari; Kumamaru, Hiroshige; Nakamura, Hideo; Suzuki, Mitsuhiro; Murata, Hideo

1985-08-01

This report presents the experimental data of RUN 916 conducted at the ROSA-III test facility. The facility is a volumetrically scaled (1/424) simulator for a BWR/6 with the electrically heated core, the break simulator and the scaled ECCS(emergency core cooling system). RUN 916 was a 50 % split break test at the recirculation pump suction line with an assumption of HPCS diegel generator failure and conducted as one of the break area parameter tests. A peak cladding temperature (PCT) of 917 K was reached at 190 s after the break during the reflooding phase. Whole core was completely quenched by ECCS, and the effectiveness of ECCS was confermed. The primary test results of RUN 916 are compared in this report with those of RUN 926, which was a 200 % double-ended break test. The initiation of core dryout in RUN 916 was later than that in RUN 926 because of the smaller discharge flow rate. Duration of core dryourt was, however, longer in RUN 916 because of later actuation of ECCSs. PCT in RUN 916 was 133 K higher than that in RUN 926. (author)

Chamber for uniaxial pressure application at low temperatures

International Nuclear Information System (INIS)

Grillo, M.L.N.; Carmo, L.C.S. do; Picon, A.P.

1984-08-01

A chamber for alignment of low temperature ferroelastic domains in crystals by the use of uniaxial stress was built. The system allows the use of EPR and optical techniques, as well as X-ray irradiation at temperatures as low as 77K. (Author) [pt

Hydrostatic and uniaxial pressure effect on Tc of YBa2Cu3Ox

International Nuclear Information System (INIS)

Ludwig, H.A.; Quenzel, R.; Schlachter, S.I.

1996-01-01

The variation of the transition temperature T c of YBa 2 Cu 3 O x with hydrostatic He-gas pressure depends on the oxygen content x. The pressure effect dT c /dp increases from small negative values at x=7 to dT c /dp=7.4 K/GPa at x=6.7. For oxygen contents below x=6.7 dT c /dp drops to 3 K/GPa and remains nearly constant. The charge transfer model cannot explain the drop at x=6.7. Thermal expansion measurements on YBa 2 Cu 3 O x indicated that the uniaxial pressure effects along the three crystal axes are different. To investigate the uniaxial pressure effects inductively an experimental setup was constructed. The T c -change of several YBa 2 Cu 3 O x single crystals with different oxygen contents has been investigated under pressure along the c-axis. To avoid oxygen ordering processes the samples were held below 105 K during the measurements. The results of uniaxial pressure measurements in c-axis direction fit to former uniaxial pressure data and are explained within the charge transfer model. Hydrostatic pressure data of overdoped samples fit to the same curve. However, this is not the case for under doped samples. From this the authors conclude that only a part of the hydrostatic pressure effect can be explained by charge transfer in the underdoped region. The remaining part can be ascribed to uniaxial pressure effects along the a- and b-axis

Thermal fatigue appears to be more damaging than uniaxial isothermal fatigue for the austentic stainless steels, and application of multiaxial fatigue criteria

Energy Technology Data Exchange (ETDEWEB)

Fissolo, Antoine; Gourdin, Cedric [DM2S/SEMT/LISN, Gif sur Yvette (France); Vincent, Ludovic [DMN/SRMA/LCD, Gif sur Yvette (France)

2009-07-01

For nuclear reactor components, uniaxial isothermal fatigue curves are used to estimate the crack initiation under thermal fatigue. However, such approach would be not sufficient in some cases where cracking was observed. To investigate differences between uniaxial and thermal fatigue damage, tests have been carried out at CEA using the thermal fatigue devices SPLASH and FAT3D: a bi-dimensional (2-D) loading status is obtained in SPLASH, whereas a tri-dimensional (3-D) loading status is obtained in FAT3D. All the analysed tests clearly show that crack initiation in thermal fatigue is faster than in uniaxial isothermal fatigue conditions: for identical levels of strain, the number of cycles required to achieve crack initiation is significantly lower. The enhanced damaging effect probably results from a pure mechanical origin: a nearly perfect biaxial state corresponds to an increased hydrostatic stress. Consequently, multiaxial fatigue criteria must be applied. The Zamrik's strain criterion and the energy criterion proposed by Ecole Polytechnique provide the best estimations. In that framework, the proposed new method coupling both RCC-MR strain estimations and Zamrik's criterion appears to be more promising for the designer. (orig.)

Thermal fatigue appears to be more damaging than uniaxial isothermal fatigue for the austentic stainless steels, and application of multiaxial fatigue criteria

International Nuclear Information System (INIS)

Fissolo, Antoine; Gourdin, Cedric; Vincent, Ludovic

2009-01-01

For nuclear reactor components, uniaxial isothermal fatigue curves are used to estimate the crack initiation under thermal fatigue. However, such approach would be not sufficient in some cases where cracking was observed. To investigate differences between uniaxial and thermal fatigue damage, tests have been carried out at CEA using the thermal fatigue devices SPLASH and FAT3D: a bi-dimensional (2-D) loading status is obtained in SPLASH, whereas a tri-dimensional (3-D) loading status is obtained in FAT3D. All the analysed tests clearly show that crack initiation in thermal fatigue is faster than in uniaxial isothermal fatigue conditions: for identical levels of strain, the number of cycles required to achieve crack initiation is significantly lower. The enhanced damaging effect probably results from a pure mechanical origin: a nearly perfect biaxial state corresponds to an increased hydrostatic stress. Consequently, multiaxial fatigue criteria must be applied. The Zamrik's strain criterion and the energy criterion proposed by Ecole Polytechnique provide the best estimations. In that framework, the proposed new method coupling both RCC-MR strain estimations and Zamrik's criterion appears to be more promising for the designer. (orig.)

Strength of SiCf-SiCm composite tube under uniaxial and multiaxial loading

Science.gov (United States)

Shapovalov, Kirill; Jacobsen, George M.; Alva, Luis; Truesdale, Nathaniel; Deck, Christian P.; Huang, Xinyu

2018-03-01

The authors report mechanical strength of nuclear grade silicon carbide fiber reinforced silicon carbide matrix composite (SiCf-SiCm) tubing under several different stress states. The composite tubing was fabricated via a Chemical Vapor Infiltration (CVI) process, and is being evaluated for accident tolerant nuclear fuel cladding. Several experimental techniques were applied including uniaxial tension, elastomer insert burst test, open and closed end hydraulic bladder burst test, and torsion test. These tests provided critical stress and strain values at proportional limit and at ultimate failure points. Full field strain measurements using digital image correlation (DIC) were obtained in order to acquire quantitative information on localized deformation during application of stress. Based on the test results, a failure map was constructed for the SiCf-SiCm composites.

Influence of an uniaxial stress on point defects

International Nuclear Information System (INIS)

Beuneu, B.

1984-03-01

We study two effects of an elastic external uniaxial stress on point defects (created by electron irradiation): 1.- We measure the linear variation of their resistivity rhosub(D) under the elastic strain epsilon in Copper. It gives the specific elastoresistivity (E.R.S.) chisub(D)=delta rhosub(D)/epsilon. With the help of the results of VON STEBUT (fast neutrons) we show that the E.R.S. is characteristic of a defect and of its configuration. 2.- By means of resistivity measurements in molybdenum, we observe a paraelastic phenomenon. It is thermally activated (νsub(0) approximately= 10 12 s -1 and E approximately= 72 meV) and we attribute it to the reorientation of a dumbell interstitial under the uniaxial stress. The resistivity of this dumbbell is higher along its axis than perpendicularly to it. We have completed these results with some configuration energy calculations for the dumbbell and with a simple kinetic model [fr

Giant valley drifts in uniaxially strained monolayer MoS2

KAUST Repository

Zhang, Qingyun

2013-12-30

Using first-principles calculations, we study the electronic structure of monolayer MoS2 under uniaxial strain. We show that the energy valleys drift far off the corners of the Brillouin zone (K points), about 12 times the amount observed in graphene. Therefore, it is essential to take this effect into consideration for a correct identification of the band gap. The system remains a direct band gap semiconductor up to 4% uniaxial strain, while the size of the band gap decreases from 1.73 to 1.54 eV. We also demonstrate that the splitting of the valence bands due to inversion symmetry breaking and spin-orbit coupling is not sensitive to strain.

Effective stress coefficient for uniaxial strain condition

DEFF Research Database (Denmark)

Alam, M.M.; Fabricius, I.L.

2012-01-01

one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective stress...... determined under uniaxial strain condition will be more relevant in reservoir studies. Copyright 2012 ARMA, American Rock Mechanics Association....

Direct Observation of Magnetocrystalline Anisotropy Tuning Magnetization Configurations in Uniaxial Magnetic Nanomaterials

KAUST Repository

Zhu, Shimeng; Fu, Jiecai; Li, Hongli; Zhu, Liu; Hu, Yang; Xia, Weixing; Zhang, Xixiang; Peng, Yong; Zhang, Junli

2018-01-01

Discovering the effect of magnetic anisotropy on the magnetization configurations of magnetic nanomaterials is essential and significant for not only enriching the fundamental knowledge of magnetics but also facilitating the designs of desired magnetic nanostructures for diverse technological applications, such as data storage devices, spintronic devices, and magnetic nanosensors. Herein, we present a direct observation of magnetocrystalline anisotropy tuning magnetization configurations in uniaxial magnetic nanomaterials with hexagonal structure by means of three modeled samples. The magnetic configuration in polycrystalline BaFe12O19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. Both single crystalline BaFe12O19 nanoslice and individual particles of single-particle-chain BaFe12O19 nanowire appear in a single domain state, revealing a dominant role of magnetocrystalline anisotropy in the magnetization configuration of uniaxial magnetic nanomaterials. These observations are further verified by micromagnetic computational simulations.

Direct Observation of Magnetocrystalline Anisotropy Tuning Magnetization Configurations in Uniaxial Magnetic Nanomaterials

KAUST Repository

Zhu, Shimeng

2018-03-20

Discovering the effect of magnetic anisotropy on the magnetization configurations of magnetic nanomaterials is essential and significant for not only enriching the fundamental knowledge of magnetics but also facilitating the designs of desired magnetic nanostructures for diverse technological applications, such as data storage devices, spintronic devices, and magnetic nanosensors. Herein, we present a direct observation of magnetocrystalline anisotropy tuning magnetization configurations in uniaxial magnetic nanomaterials with hexagonal structure by means of three modeled samples. The magnetic configuration in polycrystalline BaFe12O19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. Both single crystalline BaFe12O19 nanoslice and individual particles of single-particle-chain BaFe12O19 nanowire appear in a single domain state, revealing a dominant role of magnetocrystalline anisotropy in the magnetization configuration of uniaxial magnetic nanomaterials. These observations are further verified by micromagnetic computational simulations.

Mechanical and electronic properties of monolayer and bilayer phosphorene under uniaxial and isotropic strains.

Science.gov (United States)

Hu, Ting; Han, Yang; Dong, Jinming

2014-11-14

The mechanical and electronic properties of both the monolayer and bilayer phosphorenes under either isotropic or uniaxial strain have been systematically investigated using first-principles calculations. It is interesting to find that: 1) Under a large enough isotropic tensile strain, the monolayer phosphorene would lose its pucker structure and transform into a flat hexagonal plane, while two inner sublayers of the bilayer phosphorene could be bonded due to its interlayer distance contraction. 2) Under the uniaxial tensile strain along a zigzag direction, the pucker distance of each layer in the bilayer phosphorene can exhibit a specific negative Poisson's ratio. 3) The electronic properties of both the monolayer and bilayer phosphorenes are sensitive to the magnitude and direction of the applied strains. Their band gaps decrease more rapidly under isotropic compressive strain than under uniaxial strain. Also, their direct-indirect band gap transitions happen at the larger isotropic tensile strains compared with that under uniaxial strain. 4) Under the isotropic compressive strain, the bilayer phosphorene exhibits a transition from a direct-gap semiconductor to a metal. In contrast, the monolayer phosphorene initially has the direct-indirect transition and then transitions to a metal. However, under isotropic tensile strain, both the bilayer and monolayer phosphorene show the direct-indirect transition and, finally, the transition to a metal. Our numerical results may open new potential applications of phosphorene in nanoelectronics and nanomechanical devices by external isotropic strain or uniaxial strain along different directions.

An effective uniaxial tensile stress-strain relationship for prestressed concrete

International Nuclear Information System (INIS)

Chitnuyanondh, L.; Rizkalla, S.; Murray, D.W.; MacGregor, J.G.

1979-02-01

This report evaluates the direct tensile strength and an equivalent uniaxial tensile stress-strain relationship for prestressed concrete using data from specimens tested at the University of Alberta which represent segments from the wall of a containment vessel. The stress-strain relationship, when used in conjunction with the BOSOR5 program, enables prediction of the response of prestressed concrete under any biaxial combination of compressive and/or tensile stresses. Comparisons between the experimental and analytical (BOSOR5) load-strain response of the wall segments are also presented. It is concluded that the BOSOR5 program is able to predict satisfactorily the response of the wall segments and multi-layered shell structures. (author)

Safety evaluation report on Westinghouse Electric Company ECCS evaluation model for plants equipped with upper head injection

International Nuclear Information System (INIS)

Lauben, G.N.; Wagner, N.H.; Israel, S.L.; McPherson, G.D.; Hodges, M.W.

1978-04-01

For plants which include an ice condenser containment concept, Westinghouse has planned an additional safety system known as the upper head injection (UHI) system to augment the emergency core cooling system. This system is comprised of additional accumulator tanks and piping arranged to supply cooling water to the top of the core during the blowdown period following a postulated large-break loss-of-coolant accident (LOCA). The objective of UHI is to add to the core cooling provided by the conventional emergency core cooling system (ECCS) and so permit operation at linear heat rates comparable to those permitted in plants utilizing the dry containment concept. In this way, plants which include the UHI system would have greater operating flexibility while still meeting the acceptance criteria as defined in paragraph 50.46 of 10 CFR Part 50. This review is concerned with those changes to the Westinghouse ECCS evaluation model that have been proposed for the UHI-LOCA model

Mechanical Behavior of Red Sandstone under Incremental Uniaxial Cyclical Compressive and Tensile Loading

Directory of Open Access Journals (Sweden)

Baoyun Zhao

2017-01-01

Full Text Available Uniaxial experiments were carried out on red sandstone specimens to investigate their short-term and creep mechanical behavior under incremental cyclic compressive and tensile loading. First, based on the results of short-term uniaxial incremental cyclic compressive and tensile loading experiments, deformation characteristics and energy dissipation were analyzed. The results show that the stress-strain curve of red sandstone has an obvious memory effect in the compressive and tensile loading stages. The strains at peak stresses and residual strains increase with the cycle number. Energy dissipation, defined as the area of the hysteresis loop in the stress-strain curves, increases nearly in a power function with the cycle number. Creep test of the red sandstone was also conducted. Results show that the creep curve under each compressive or tensile stress level can be divided into decay and steady stages, which cannot be described by the conventional Burgers model. Therefore, an improved Burgers creep model of rock material is constructed through viscoplastic mechanics, which agrees very well with the experimental results and can describe the creep behavior of red sandstone better than the Burgers creep model.

Method of injecting cooling water in emergency core cooling system (ECCS) of PWR type reactor

International Nuclear Information System (INIS)

Sobajima, Makoto; Adachi, Michihiro; Tasaka, Kanji; Suzuki, Mitsuhiro.

1979-01-01

Purpose: To provide a cooling water injection method in an ECCS, which can perform effective cooling of the reactor core. Method: In a method of injecting cooling water in an ECCS as a countermeasure against a rupture accident of a pwr type reactor, cooling water in the first pressure storage injection system is injected into the upper plenum of the reactor pressure vessel at a set pressure of from 50 to 90 atg. and a set temperature of from 80 to 200 0 C, cooling water in the second pressure storage injection system is injected into the lower plenum of the reactor pressure vessel at a pressure of from 25 to 60 atg. which is lower than the set pressure and a temperature less than 60 0 C, and further in combination with these procedures, cooling water of less than 60 0 C is injected into a high-temperature side piping, in the high-pressure injection system of upstroke of 100 atg. by means of a pump and the low-pressure injection system of upstroke of 20 atg. also by means of a pump, thereby cooling the reactor core. (Aizawa, K.)

Uniaxial Elongational viscosity of bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

Technique for measurements of plane waves of uniaxial strain

International Nuclear Information System (INIS)

Graham, R.A.

1977-01-01

The measurement of plane waves in uniaxial strain, in which large surface areas are loaded and the measurements are restricted to a central region that is not influenced by lateral boundaries, is discussed. Measuring techniques are covered and instruments are discussed

Oriented Morphology and Anisotropic Transport in Uniaxially Stretched Perfluorosulfonate Ionomer Membranes

Energy Technology Data Exchange (ETDEWEB)

J Park; J Li; G Divoux; L Madsen; R Moore

2011-12-31

Relations between morphology and transport sensitively govern proton conductivity in perfluorsulfonate ionomers (PFSIs) and thus determine useful properties of these technologically important materials. In order to understand such relations, we have conducted a broad systematic study of H{sup +}-form PFSI membranes over a range of uniaxial extensions and water uptakes. On the basis of small-angle X-ray scattering (SAXS) and {sup 2}H NMR spectroscopy, uniaxial deformation induces a strong alignment of ionic domains along the stretching direction. We correlate ionic domain orientation to transport using pulsed-field-gradient {sup 1}H NMR measurements of water diffusion coefficients along the three orthogonal membrane directions. Intriguingly, we observe that uniaxial deformation enhances water transport in one direction (parallel-to-draw direction) while reducing it in the other two directions (two orthogonal directions relative to the stretching direction). We evaluate another important transport parameter, proton conductivity, along two orthogonal in-plane directions. In agreement with water diffusion experiments, orientation of ionic channels increases proton conduction along the stretching direction while decreasing it in the perpendicular direction. These findings provide valuable fodder for optimal application of PFSI membranes as well as for the design of next generation polymer electrolyte membranes.

Quantum Monte Carlo simulation for S=1 Heisenberg model with uniaxial anisotropy

International Nuclear Information System (INIS)

Tsukamoto, Mitsuaki; Batista, Cristian; Kawashima, Naoki

2007-01-01

We perform quantum Monte Carlo simulations for S=1 Heisenberg model with an uniaxial anisotropy. The system exhibits a phase transition as we vary the anisotropy and a long range order appears at a finite temperature when the exchange interaction J is comparable to the uniaxial anisotropy D. We investigate quantum critical phenomena of this model and obtain the line of the phase transition which approaches a power-law with logarithmic corrections at low temperature. We derive the form of logarithmic corrections analytically and compare it to our simulation results

On the in-plane uniaxial anisotropy formation by using Fe–Co–Zr–N films: A theoretical and experimental investigation

Energy Technology Data Exchange (ETDEWEB)

Seemann, K., E-mail: klaus.seemann@kit.edu; Beirle, S.; Leiste, H.

2016-09-01

In the present paper a simple theoretical approach for the in-plane uniaxial anisotropy evolution in thin films is introduced. In order to show, what are the conditions for a uniaxial anisotropy formation during annealing a ferromagnetic film in an external static magnetic field, a Hamiltonian, i.e., mean energy balances were established with introducing their annealing temperature dependence. At this point, a 1-dimesional chain-like arrangement of Fe and Co elements for an “isotropic” and uniaxial anisotropy state for the numerical computation was assumed. It was shown that a critical energy and annealing temperature (temperature threshold) can be attained from which a uniaxial anisotropy arises. Comparatively, calculations according to the Neél theory delivered the activation energy for inducing a uniaxial anisotropy. The experimental verification of the calculations, by using Fe{sub 40}Co{sub 37}Zr{sub 11}N{sub 12} films which were produced by reactive magnetron sputtering, yielded the activation energy of about 250 meV. Annealing temperatures above 473 K (200 °C) enabled marked uniaxial anisotropies. This correlated with the numerical quantum mechanical estimations which yielded a critical annealing temperature of approximately 449 K (176 °C). The calculated critical energy of 243 meV was in a good agreement with the verified experiments if one assumes a short range order of at least 10 ferromagnetic atoms in line (5Fe+5Co) for computation. - Highlights: • Model and theoretical description of the uniaxial anisotropy in ferromagnetic films. • Critical energy and a critical temperature for inducing the uniaxial anisotropy. • Investigation of the activation energy for inducing the uniaxial anisotropy. • Comparison with the model and according to the Neél theory.

Microwave holography in a uniaxial anial anisotropic plasma

International Nuclear Information System (INIS)

Nagai, Keinosuke; Suzuki, Michio

1974-01-01

Properties of a hologram constructed in a uniaxial anisotropic medium, namely in a gyro-plasma were investigated theoretically. We considered the interference patterns of ordinary waves and extraordinary waves from a source such as a hologram. An element of permitivity tensor can be measured by the reconstruction process from this hologram. (auth.)

Exxon Nuclear Company ECCS evaluation of a 2-loop Westinghouse PWR with dry containment using the ENC WREM-II ECCS model. Large break example problem

International Nuclear Information System (INIS)

Krajicek, J.E.

1977-01-01

This document is presented as a demonstration of the ENC WREM-II ECCS model calculational procedure applied to a Westinghouse 2-loop PWR with a dry containment (R. E. Ginna plant, for example). The hypothesized Loss-of-Coolant Accident (LOCA) investigated was a split break with an area equal to twice the pipe cross-sectional area. The break was assumed to occur in one pump discharge pipe (DECLS break). The analyses involved calculations using the ENC WREM-II model. The following codes were used: RELAP4-EM/ENC26A for blowdown and hot channel analyses, RELAP4-EM FLOOD/ENC26A for core reflood analysis, CONTEMPT LT/22 modified for containment backpressure analysis, and TOODEE2/APR77 for heatup analysis

Incorporating Indigenous Knowledge and Practice into ECCE: A Comparison of Programs in The Gambia, Senegal and Mali

Science.gov (United States)

Soudee, Alicia Ranck

2009-01-01

Early Childhood Development (ECD) has emerged as a theme in international and African dialogue on education in recent years. UNESCO's Division of Basic Education Early Childhood promotes an integrated approach to Early Childhood Care and Education (ECCE) policy development and review. The study examines how this is implemented in three West…

Interplay of uniaxial and cubic anisotropy in epitaxial Fe thin films on MgO (001 substrate

Directory of Open Access Journals (Sweden)

Srijani Mallik

2014-09-01

Full Text Available Epitaxial Fe thin films were grown on annealed MgO(001 substrates at oblique incidence by DC magnetron sputtering. Due to the oblique growth configuration, uniaxial anisotropy was found to be superimposed on the expected four-fold cubic anisotropy. A detailed study of in-plane magnetic hysteresis for Fe on MgO thin films has been performed by Magneto Optic Kerr Effect (MOKE magnetometer. Both single step and double step loops have been observed depending on the angle between the applied field and easy axis i.e. along ⟨100⟩ direction. Domain images during magnetization reversal were captured by Kerr microscope. Domain images clearly evidence two successive and separate 90° domain wall (DW nucleation and motion along cubic easy cum uniaxial easy axis and cubic easy cum uniaxial hard axis, respectively. However, along cubic hard axis two 180° domain wall motion dominate the magnetization reversal process. In spite of having four-fold anisotropy it is essential to explain magnetization reversal mechanism in 0°< ϕ < 90° span as uniaxial anisotropy plays a major role in this system. Also it is shown that substrate rotation can suppress the effect of uniaxial anisotropy superimposed on four-fold anisotropy.

Experiment data of ROSA-III integral test RUN 710

International Nuclear Information System (INIS)

Koizumi, Yasuo; Tasaka, Kanji; Adachi, Hiromichi; Anoda, Yoshinari; Soda, Kunihisa

1981-01-01

The report presents data of RUN 710 at ROSA-III test facility. RUN 710 simulates a 200% double-ended break at the inlest side of a recirculation pump of a BWR. All ECCS are activated and electric power to simulated fuel rods in one core channel among four is not supplied in RUN 710. The primary initial conditions are steam dome pressure 7.35 MPa, lower plenum subcooling 10.8 K, core inlet flow rate 31.3 kg/s and core heat generation 2.42 MW. Peak cladding temperature is 609 K at Position 3, 352.5 mm above the mid plane of the core. All heater rods are quenched after ECCS actuation and the effectiveness of ECCS is confirmed. (author)

Volume growth during uniaxial tension of particle-filled elastomers at various temperatures - Experiments and modelling

Science.gov (United States)

Ilseng, Arne; Skallerud, Bjørn H.; Clausen, Arild H.

2017-10-01

A common presumption for elastomeric material behaviour is incompressibility, however, the inclusion of filler particles might give rise to matrix-particle decohesion and subsequent volume growth. In this article, the volumetric deformation accompanying uniaxial tension of particle-filled elastomeric materials at low temperatures is studied. An experimental set-up enabling full-field deformation measurements is outlined and novel data are reported on the significant volume growth accompanying uniaxial tension of two HNBR and one FKM compounds at temperatures of - 18 , 0, and 23 °C. The volumetric deformation was found to increase with reduced temperature for all compounds. To explain the observed dilatation, in situ scanning electron microscopy was used to inspect matrix-particle debonding occurring at the surface of the materials. A new constitutive model, combining the Bergström-Boyce visco-hyperelastic formulation with a Gurson flow potential function is outlined to account for the observed debonding effects in a numerical framework. The proposed model is shown to provide a good correspondence to the experimental data, including the volumetric response, for the tested FKM compound at all temperature levels.

2D magnetization of grain-oriented 3%-Si steel under uniaxial stress

International Nuclear Information System (INIS)

Permiakov, V.; Dupre, L.; Pulnikov, A.; Melkebeek, J.

2005-01-01

Magnetization in electrical steels is strongly affected by mechanical stress. The stress dependence of magnetic properties of non-oriented steels has been studied at one- and two-dimensional magnetization. This paper deals with the stress effect on one- and two-dimensional magnetization in grain-oriented 3%-Si steel. The special magnetic measurements system is applied to combine uniaxial stress and 2D magnetic measurements. The uniaxial stress ranges from 10 MPa compressive stress to 100 MPa tensile stress. A domain theory is a suitable tool for prediction and a physical explanation of stress dependency in grain-oriented steel

Giant valley drifts in uniaxially strained monolayer MoS{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Schwingenschloegl, Udo; Zhang, Qingyun; Cheng, Yingchun; Gan, Li-Yong [PSE Division, KAUST, Thuwal 23955 (Saudi Arabia)

2016-07-01

Using first-principles calculations, we study the electronic structure of monolayer MoS{sub 2} under uniaxial strain. We show that the energy valleys drift far off the corners of the Brillouin zone (K points), about 12 times the amount observed in graphene. Therefore, it is essential to take this effect into consideration for a correct identification of the band gap. The system remains a direct band gap semiconductor up to 4% uniaxial strain, while the size of the band gap decreases from 1.73 to 1.54 eV. We also demonstrate that the splitting of the valence bands due to inversion symmetry breaking and spin-orbit coupling is not sensitive to strain.

Saturation and oscillation of current in semiconductors subjected to uniaxial deformation

International Nuclear Information System (INIS)

Zdebskii, A.P.; Olikh, Yu.A.; Savchuk, A.U.

1985-01-01

The influence of an external uniaxial deformation on the saturation and oscillations of current in photosensitive CdS monocrystals is investigated. The specimens were subjected to uniaxial pressure up to 6 x 10 7 N/m 2 , the pressure being either parallel or perpendicular to the c axis in CdS. With application of external pressure, the shape of current oscillations and their amplitude changed. In the case where the pressure was perpendicular to the direction of current I, the amplitude of oscillations and the saturation depth of the volt-ampere characteristic, VAC, were increased. With pressure being parallel to the current direction, the reverse phenomenon was observed, i.e. the efficiency of the acousto-electronic interaction was reduced

Tensile testing

CERN Document Server

2004-01-01

A complete guide to the uniaxial tensile test, the cornerstone test for determining the mechanical properties of materials: Learn ways to predict material behavior through tensile testing. Learn how to test metals, alloys, composites, ceramics, and plastics to determine strength, ductility and elastic/plastic deformation. A must for laboratory managers, technicians, materials and design engineers, and students involved with uniaxial tensile testing. Tensile Testing , Second Edition begins with an introduction and overview of the test, with clear explanations of how materials properties are determined from test results. Subsequent sections illustrate how knowledge gained through tensile tests, such as tension properties to predict the behavior (including strength, ductility, elastic or plastic deformation, tensile and yield strengths) have resulted in improvements in materals applications. The Second Edition is completely revised and updated. It includes expanded coverage throughout the volume on a variety of ...

Experimental study under uniaxial cyclic behavior at room and high temperature of 316L stainless steel

International Nuclear Information System (INIS)

Kang Guozheng; Gao Qing; Yang Xianjie; Sun Yafang

2001-01-01

An experimental study was carried out of the cyclic properties of 316L stainless steel subjected to uniaxial strain and stress at room and high temperature. The effects of cyclic strain amplitude, temperature and their histories on the cyclic deformation behavior of 316L stainless steel are investigated. And, the influences of stress amplitude, mean stress, temperature and their histories on ratcheting are also analyzed. It is shown that either uniaxial cyclic property under cyclic strain or ratcheting under asymmetric uniaxial cyclic stress depends not only on the current temperature and loading state, but also on the previous temperature and loading history. Some significant results are obtained

Assessment of human effective absorbed dose of 67 Ga-ECC based on biodistribution rat data.

Science.gov (United States)

Shanehsazzadeh, Saeed; Yousefnia, Hassan; Lahooti, Afsaneh; Zolghadri, Samaneh; Jalilian, Amir Reza; Afarideh, Hossien

2015-02-01

In a diagnostic context, determination of absorbed dose is required before the introduction of a new radiopharmaceutical to the market to obtain marketing authorization from the relevant agencies. In this work, the absorbed dose of [67 Ga]-ethylenecysteamine cysteine [(67 Ga)ECC] to human organs was determined by using distribution data for rats. For biodistribution data, the animals were sacrificed by CO2 asphyxiation at selected times after injection (0.5, 2 and 48 h, n = 3 for each time interval), then the tissue (blood, heart, lung, brain, intestine, feces, skin, stomach, kidneys, liver, muscle and bone) were removed. The absorbed dose was determined by Medical Internal Radiation Dose (MIRD) method after calculating cumulated activities in each organ. Our prediction shows that a 185-MBq injection of (67)Ga-ECC into the humans might result in an estimated absorbed dose of 0.029 mGy in the whole body. The highest absorbed doses are observed in the spleen and liver with 33.766 and 16.847 mGy, respectively. The results show that this radiopharmaceutical can be a good SPECT tracer since it can be produced easily and also the absorbed dose in each organ is less than permitted absorbed dose.

Effect of hexane treatment and uniaxial stretching on bending ...

African Journals Online (AJOL)

PVDF) film was studied. The quantity, β31, defined as the bending piezoelectric stress constant, was calculated. After hexane treatment and uniaxial stretching of the PVDF film, the value of β31 was 5.75 mV/m and 8.00 mV/m for draw ratio of ...

Safety verification for the ECCS driven by the electrically 4 trains during LBLOCA reflood phase using ATLAS

International Nuclear Information System (INIS)

Park, Yusun; Park, Hyun-sik; Kang, Kyoung-ho; Choi, Nam-hyun; Min, Kyoung-ho; Choi, Ki-yong

2014-01-01

Highlights: • Safety improvement by adopting 4 train emergency core cooling system was validated experimentally. • General thermal hydraulic behaviors of the system during LBLOCA reflood phase were successfully demonstrated. • Key parameters such as the liquid levels, the PCTs, the quenching time, and the ECC bypass ratios were investigated. • Asymmetric effects of the different combination of safety injection were negligible during the reflood period. - Abstract: The APR1400 is equipped with four safety injection pumps driven by two emergency diesel generators. However, the design has been changed so that the four safety injection pumps are driven by 4 emergency diesel generators during the design certification process from the U.S. NRC. Thus, 4 safety injection pumps (SIPs) are completely independent electrically and mechanically and three safety injection pumps are available in a single failure condition. This design change could have a certain effects on the thermal-hydraulic phenomenon occurring in the downcomer region during the late reflood phase of a large break loss of coolant accident (LBLOCA). Thus, in this study, a verification experiment for the reflood phase of a LBLOCA was performed to evaluate the core cooling performance of the 4 train emergency core cooling system (ECCS) with an assumption of a single failure. And the different combinations of three SIPs positions were tested to investigate the asymmetric effects on the reactor core cooling performance. The overall experimental results revealed the typical thermal–hydraulic trends expected to occur during the reflood phase of a large-break LOCA scenario for the APR1400. Experiment with the injection of three SIPs showed a faster core quenching time and lower bypass ratio than that of the case in which two SIPs were injected. The RPV wall temperature distributions showed the similar trend in spite of the different SIP combinations

Nietzsche como destino da filosofia e da humanidade? interpretação contextual do § 1 do capítulo "por que sou um destino", de ecce homo

Directory of Open Access Journals (Sweden)

Werner Stegmaier

2010-01-01

Full Text Available The following translation is a reduced and revised version of the paper Schicksal Nietzsche? Zu Nietzsches Selbsteinschätzung als Schicksal der Philosophie und der Menschheit (Ecce Homo, Warum ich ein Schicksal bin §1" - originally published in Nietzsche-Studien 37 (2008 - which was specially prepared to be presented in lecture organized by the Grupo de Pesquisa Spinoza & Nietzsche (Spinoza & Nietzsche research group - SpiN, in the Universidade Federal do Rio de Janeiro (Rio de Janeiro's Federal University, on September 14, 2009. In the text, the autor employs his own philological-hermeneutical methodology, which is called contextual interpretation, in the purpose to clarify the concepts of the first aphorism from "Why I am a destiny", from Ecce Homo, in its own context, in the context of Ecce Homo and in the context of the entire work from Nietzsche.

Experimental observations on uniaxial whole-life transformation ratchetting and low-cycle stress fatigue of super-elastic NiTi shape memory alloy micro-tubes

Science.gov (United States)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2015-07-01

In this work, the low-cycle fatigue failure of super-elastic NiTi shape memory alloy micro-tubes with a wall thickness of 150 μm is investigated by uniaxial stress-controlled cyclic tests at human body temperature 310 K. The effects of mean stress, peak stress, and stress amplitude on the uniaxial whole-life transformation ratchetting and fatigue failure of the NiTi alloy are observed. It is concluded that the fatigue life depends significantly on the stress levels, and the extent of martensite transformation and its reverse play an important role in determining the fatigue life. High peak stress or complete martensite transformation shortens the fatigue life.

Experimental observations on uniaxial whole-life transformation ratchetting and low-cycle stress fatigue of super-elastic NiTi shape memory alloy micro-tubes

International Nuclear Information System (INIS)

Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

2015-01-01

In this work, the low-cycle fatigue failure of super-elastic NiTi shape memory alloy micro-tubes with a wall thickness of 150 μm is investigated by uniaxial stress-controlled cyclic tests at human body temperature 310 K. The effects of mean stress, peak stress, and stress amplitude on the uniaxial whole-life transformation ratchetting and fatigue failure of the NiTi alloy are observed. It is concluded that the fatigue life depends significantly on the stress levels, and the extent of martensite transformation and its reverse play an important role in determining the fatigue life. High peak stress or complete martensite transformation shortens the fatigue life. (paper)

Water-hammer in the cold leg during an SBLOCA due to cold ECCS injection

International Nuclear Information System (INIS)

Ortiz, M.G.; Ghan, L.S.

1991-01-01

Water-hammer might occur in the cold leg of pressurized water reactors (PWR) during small break loss-of-coolant accidents (SBLOCA's), when cold emergency core cooling system (ECCS) water is injected into a pipe that may be partially filled with saturated steam. The water may mix with the steam and cause it to condense abruptly. Depending on the flow regime present, slugs of liquid may then be accelerated towards each other or against the piping structure. The possibility of this phenomenon is of concern to us because it may become a dominant phenomenon and change the character of the transient. In performing the code scaling, applicability, and uncertainty study (CSAU) on a SBLOCA scenario, we had to examine the possibility that the transient being analyzed could experience water-hammer and thus depart from the scope of the study. Two criteria for water-hammer initiation were investigated and tested using a RELAP5/MOD3 simulation of the transient. Our results indicated a very low likelihood of occurrence of the phenomenon. 8 refs., 6 figs

Determination of the activation energy of A-center in the uniaxially deformed n-Ge single crystals

Directory of Open Access Journals (Sweden)

S. V. Luniov

2017-08-01

Full Text Available Based on the decisions of electroneutrality equation and experimental results of measurements of the piezo-Hall-effect the dependences of activation energy of the deep level A-center depending on the uniaxial pressure along the crystallographic directions [100], [110] and [111] for n-Ge single crystals, irradiated by the electrons with energy 10 MeV are obtained. Using the method of least squares approximational polynomials for the calculation of these dependences are obtained. It is shown that the activation energy of A-center deep level decreases linearly for the entire range of uniaxial pressure along the crystallographic direction [100]. For the cases of uniaxial deformation along the crystallographic directions [110] and [111] decrease of the activation energy according to the linear law is observed only at high uniaxial pressures, when the A-center deep level interacts with the minima of the germanium conduction band, which proved the lower at the deformation. The various dependences of the activation energy of A-center depending on the orientation of the axis of deformation may be connected with features of its microstructure.

Status of CCTF test program

International Nuclear Information System (INIS)

Murao, Y.; Iguchi, T.; Sugimoto, J.; Akimoto, H.; Okubo, T.; Okabe, K.

1984-01-01

The cylindrical core test facility (CCTF) is one of the facilities of the large scale reflood test program which was initiated in April, 1976. The first series of the CCTF test (CCTF CORE I Test) was completed in April, 1981 and the second series (CCTF Core II Test) has been conducted since April, 1982. In the test, the following has been intended to be examined: (1) The conservativeness of the assumption of the safety analysis with the evaluation model (EM) code. (2) The refill and reflood phenomena for analytical modeling of thermo-hydrodynamics in the core and the system. (3) The validity of the models in the EM code and the application to the best estimate code development. In this paper, presented are the quantative evaluation of the REFLA code and the discussion of some CCTF Core II Test results. The REFLA code consists of REFLA-1D core code developed with the results of small scale tests and a simple system model developed with the results of the CCTF Core I Test. The CCTF Core II Test was perfored for developing more realistic model for the alternative ECCS as well as for the cold leg injection type ECCS

Preparation, structure and properties of uniaxially oriented polyethylene-silver nanocomposites

NARCIS (Netherlands)

Dirix, Y.J.L.; Bastiaansen, C.W.M.; Caseri, W.R.; Smith, P.

1999-01-01

Uniaxially oriented composites of high-density polyethylene and silver nanoparticles were prepared using solution-casting, melt-extrusion and solid-state drawing techniques. The absorption spectrum in the visible wavelength range of the drawn nanocomposites was observed to strongly depend on the

Reflooding phenomena of German PWR estimated from CCTF [Cylindrical Core Test Facility], SCTF [Slab Core Test Facility] and UPTF [Upper Plenum Test Facility] results

International Nuclear Information System (INIS)

Murao, Y.; Iguchi, T.; Sugimoto, J.

1988-09-01

The reflooding behavior in a PWR with a combined injection type ECCS was studied by comparing the test results from Cylindrical Core Test Facility (CCTF), Slab Core Test Facility (SCTF) and Upper Plenum Test Facility (UPTF). Core thermal-hydraulics is discussed mainly based on SCTF test data. In addition, the water accumulation behavior in hot legs and the break-through characteristics at tie plate are discussed

THE EFFICACY OF ANGLE-MATCHED ISOKINETIC KNEE FLEXOR AND EXTENSOR STRENGTH PARAMETERS IN PREDICTING AGILITY TEST PERFORMANCE.

Science.gov (United States)

Greig, Matt; Naylor, James

2017-10-01

Agility is a fundamental performance element in many sports, but poses a high risk of injury. Hierarchical modelling has shown that eccentric hamstring strength is the primary determinant of agility performance. The purpose of this study was to investigate the relationship between knee flexor and extensor strength parameters and a battery of agility tests. Controlled laboratory study. Nineteen recreational intermittent games players completed an agility battery and isokinetic testing of the eccentric knee flexors (eccH) and concentric knee extensors (conQ) at 60, 180 and 300°·s -1 . Peak torque and the angle at which peak torque occurred were calculated for eccH and conQ at each speed. Dynamic control ratios (eccH:conQ) and fast:slow ratios (300:60) were calculated using peak torque values, and again using angle-matched data, for eccH and conQ. The agility test battery differentiated linear vs directional changes and prescriptive vs reactive tasks. Linear regression showed that eccH parameters were generally a better predictor of agility performance than conQ parameters. Stepwise regression showed that only angle-matched strength ratios contributed to the prediction of each agility test. Trdaitionally calculated strength ratios using peak torque values failed to predict performance. Angle-matched strength parameters were able to account for 80% of the variation in T-test performance, 70% of deceleration distance, 55% of 10m sprint performance, and 44% of reactive change of direction speed. Traditionally calculated strength ratios failed to predict agility performance, whereas angle-matched strength ratios had better predictive ability and featured in a predictive stepwise model for each agility task. 2c.

Functional possibilities of nonlinear crystals for frequency conversion: uniaxial crystals

Energy Technology Data Exchange (ETDEWEB)

Andreev, Yu M [Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch of the Russian Academy of Sciences, Tomsk (Russian Federation); Arapov, Yu D; Kasyanov, I V [E.I. Zababakhin All-Russian Scientific-Research Institute of Technical Physics, Russian Federal Nuclear Centre, Snezhinsk, Chelyabinsk region (Russian Federation); Grechin, S G; Nikolaev, P P [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)

2016-01-31

The method and results of the analysis of phase-matching and nonlinear properties for all point groups of symmetry of uniaxial crystals that determine their functional possibilities for solving various problems of nonlinear frequency conversion of laser radiation are presented. (nonlinear optical phenomena)

Magnetic properties of URu2Si2 under uniaxial stress by neutron scattering

International Nuclear Information System (INIS)

Bourdarot, Frederic; Martin, Nicolas; Raymond, Stephane; Regnault, Louis-Pierre; Aoki, Dai; Taufour, Valentin; Flouquet, Jacques

2011-01-01

The aim of this study is to compare the magnetic behavior of URu 2 Si 2 under uniaxial stress along the a axis with the behavior under hydrostatic pressure. Both are very similar, but uniaxial stress presents a critical stress σ x a [0.33(5) GPa] that is smaller than the hydrostatic critical pressure p x (0.5 GPa) where the ground state switches from a HO (hidden-order) to AF (antiferromagnetic) ground state. From these critical values and Larmor neutron diffraction, we conclude that the magnetic properties are governed by the shortest U-U distance in the plane (a lattice parameter). Under stress, the orthorhombic unit cell stays centered. A key point shown by this study is the presence of a threshold for the uniaxial stress along the a axis before the appearance of the large AF moment, which indicates no mixture of the order parameter between the HO ground state and the AF one as under hydrostatic pressure. The two most intense longitudinal magnetic excitations at Q 0 =(1,0,0) and Q 1 =(0.6,0,0) were measured in the HO state: the excitation at Q 0 decreases in energy while the excitation at Q 1 increases in energy with the uniaxial stress along the a axis. The decrease of the energy of the excitation at Q 0 seems to indicate a critical energy-gap value of 1.2(1) meV at σ x a . A similar value was derived from studies under hydrostatic pressure at p x .

Raman study of lead zirconate titanate under uniaxial stress

International Nuclear Information System (INIS)

Tallant, David R.; Simpson, Regina L.; Grazier, J. Mark; Zeuch, David H.; Olson, Walter R.; Tuttle, Bruce A.

2000-01-01

The authors used micro-Raman spectroscopy to monitor the ferroelectric (FE) to antiferroelectric (AFE) phase transition in PZT ceramic bars during the application of uniaxial stress. They designed and constructed a simple loading device, which can apply sufficient uniaxial force to transform reasonably large ceramic bars while being small enough to fit on the mechanical stage of the microscope used for Raman analysis. Raman spectra of individual grains in ceramic PZT bars were obtained as the stress on the bar was increased in increments. At the same time gauges attached to the PZT bar recorded axial and lateral strains induced by the applied stress. The Raman spectra were used to calculate an FE coordinate, which is related to the fraction of FE phase present. The authors present data showing changes in the FE coordinates of individual PZT grains and correlate these changes to stress-strain data, which plot the macroscopic evolution of the FE-to-AFE transformation. Their data indicates that the FE-to-AFE transformation does not occur simultaneously for all PZT grains but that grains react individually to local conditions

Analysis of threshold current of uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers.

Science.gov (United States)

Jiang, Jialin; Sun, Junqiang; Gao, Jianfeng; Zhang, Ruiwen

2017-10-30

We propose and design uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers with the stress along direction. The micro-bridge structure is adapted for introducing uniaxial stress in Ge/SiGe quantum well. To enhance the fabrication tolerance, full-etched circular gratings with high reflectivity bandwidths of ~500 nm are deployed in laser cavities. We compare and analyze the density of state, the number of states between Γ- and L-points, the carrier injection efficiency, and the threshold current density for the uniaxially tensile stressed bulk Ge and Ge/SiGe quantum well lasers. Simulation results show that the threshold current density of the Ge/SiGe quantum well laser is much higher than that of the bulk Ge laser, even combined with high uniaxial tensile stress owing to the larger number of states between Γ- and L- points and extremely low carrier injection efficiency. Electrical transport simulation reveals that the reduced effective mass of the hole and the small conduction band offset cause the low carrier injection efficiency of the Ge/SiGe quantum well laser. Our theoretical results imply that unlike III-V material, uniaxially tensile stressed bulk Ge outperforms a Ge/SiGe quantum well with the same strain level and is a promising approach for Si-compatible light sources.

Uniaxial creep behavior of V-4Cr-4Ti alloy

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.; Purohit, A.

2002-01-01

We are undertaking a systematic study at Argonne National Laboratory to evaluate the uniaxial creep behavior of V-Cr-Ti alloys in a vacuum environment as a function of temperature in the range of 650-800 deg. C and at applied stress levels of 75-380 MPa. Creep strain in the specimens is measured by a linear-variable-differential transducer, which is attached between the fixed and movable pull rods of the creep assembly. Strain is measured at sufficiently frequent intervals during testing to define the creep strain/time curve. A linear least-squares analysis function is used to ensure consistent extraction of minimum creep rate, onset of tertiary creep and creep strain at the onset of tertiary creep. Creep test data, obtained at 650, 700, 725 and 800 deg. C, showed power-law creep behavior. Extensive analysis of the tested specimens is conducted to establish hardness profiles, oxygen content and microstructural characteristics. The data are also quantified by the Larson-Miller approach, and correlations are developed to relate time to rupture, onset of tertiary creep, times for 1% and 2% strain, exposure temperature and applied stress

Study of uniaxial nematic lyomesophases by x-ray diffraction and auxiliary techniques

International Nuclear Information System (INIS)

Bittencourt, D.R.S.

1986-01-01

The uniaxial lyotropic nematic liquid crystals made of amphiphile/water/decanol/salt have been studied. The amphiphiles sodium decyl sulphate and sodium dodecil sulphate have been used. Characterization of samples conditioned in plane and cylindrical cells has been made by orthoscopic polarized optical microscopy (OM) and X.ray diffraction (XD) by observation of orientation under surface and magnetic field effects. It was possible to determine the director orientation of uniaxial discotic (N D ) and cylindrical (N C ) samples under surface and magnetic effects by both OM and XD techniques in independent ways. The homologous amphiphilies sodium octil, decil and dodecil sulfate, in powder form, have been studied by Debye-Scherrer technique. Observed reflexions have been indexed and crystallographic parameters determined. Good agreement between calculated and measured densities has been obtained. A crysostat for temperature variation in the interval- 10 0 /60 0 has been constructed, XD diagrams has been obtained for sodium decil sulfate samples allowing determination of phase transitions of two systems. Scattering curves at room temperatures have been obtained in a small-angle X-ray diffractometer. Analysis of profiles allowed determination of short range positional order and correlation ranges. Interference function between scattering objects have been obtained using structural models for the micelles of the uniaxial nematic phases. (author) [pt

Evolution of the Fermi surface of the strongly correlated f electron system under hydrostatic and uniaxial pressures

CERN Document Server

Aoki, H; Endo, M; Nakayama, M; Takei, H; Kimura, N; Kunii, S; Terashima, T; Uji, S; Matsumoto, T

2002-01-01

We report our recent developments of experimental systems for measuring the de Haas-van Alphen (dHvA) effect under hydrostatic and uniaxial pressures. The dHvA effect of CeB sub 6 has been studied under both hydrostatic and uniaxial pressures and the effects of the pressures on the electronic structure are discussed.

The impact of uniaxial stress on subband structure and mobility of strain Si NMOSFETs

International Nuclear Information System (INIS)

Chang, S.T.; Liao, S.H.; Lin, C.-Y.

2008-01-01

An effect of stress distortion on the conduction band structure was derived by k.p method considering a second order perturbation. From k.p conduction band calculations, stress-induced band edge split and the change of effective mass are quantitatively evaluated. The physical reasons of warped subband structure and abnormal mobility enhancement by uniaxial stress are investigated. Variation rates of experimental electron mobility in the silicon n-channel metal-oxide-semiconductor field-effect-transistors under a [110] uniaxial stress as a function of channel direction is theoretically studied

Mechanical response of human female breast skin under uniaxial stretching.

Science.gov (United States)

Kumaraswamy, N; Khatam, Hamed; Reece, Gregory P; Fingeret, Michelle C; Markey, Mia K; Ravi-Chandar, Krishnaswamy

2017-10-01

Skin is a complex material covering the entire surface of the human body. Studying the mechanical properties of skin to calibrate a constitutive model is of great importance to many applications such as plastic or cosmetic surgery and treatment of skin-based diseases like decubitus ulcers. The main objective of the present study was to identify and calibrate an appropriate material constitutive model for skin and establish certain universal properties that are independent of patient-specific variability. We performed uniaxial tests performed on breast skin specimens freshly harvested during mastectomy. Two different constitutive models - one phenomenological and another microstructurally inspired - were used to interpret the mechanical responses observed in the experiments. Remarkably, we found that the model parameters that characterize dependence on previous maximum stretch (or preconditioning) exhibited specimen-independent universal behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental data report for transient flow calibration facility tests IIIA101, IIIA102, IIIA201, and IIIA202

International Nuclear Information System (INIS)

Wambach, J.L.

1980-01-01

Thermal-hydraulic response data are presented for the transient performance tests of an ECC pitot tube rake (IIIA201, IIIA202) and both an ECC pitot tube rake and modular drag disc-turbine transducer (DTT) rake (IIIA101, IIIA102). The tests were conducted in a system which provided full scale simulation of the pressure vessel and intact loop cold leg piping of the Loss of Fluid Test Facility (LOFT). A load cell system was used to provide a reference mass flow rate measurement

Band Gap Changes Of Single Walled Carbon Nanotubes Under Uniaxial Strain

International Nuclear Information System (INIS)

Dereli, G.

2010-01-01

The study of the band gap variation with mechanical deformation is important in manipulations of Single Walled Carbon Nanotubes (SWCNT). In this study we investigated the electronic band structure and the mechanical properties of (12,0) and (13,0) SWCNTs under the effect of uniaxial strain. Electronic and mechanical properties are studied using a parallel, order N, tight-binding molecular dynamics (O(N) TBMD) simulation code designed by G. Dereli et. al. We showed the effect of uniaxial strain on the variations of band gaps and the total energy per atom of (12,0) and (13,0) SWCNTs. We calculated Young's modulus and the Poisson ratio of these SWCNTs. The research reported here was supported through the Yildiz Technical University Research Found Project No: 24-01-01-04. Simulations are performed in parallel environment at Carbon Nanotube Simulation Laboratory of Yildiz Technical University.

Polarized emission from light-emitting electrochemical cells using uniaxially oriented polymer thin films of poly(9,9-dioctylfluorene-co-bithiophene)

Science.gov (United States)

Miyazaki, Masumi; Sakanoue, Tomo; Takenobu, Taishi

2018-03-01

Uniaxially oriented poly(9,9-dioctylfluorene-co-bithiophene) (F8T2) films were prepared on rubbed polyimide substrates and applied to emitting layers of light-emitting electrochemical cells (LECs). The layered structure of the uniaxially oriented F8T2 film and ionic liquid electrolytes enabled us to demonstrate LEC operations with high anisotropic characteristics both in emission and charge transport. Polarized electroluminescence (EL) from electrochemically induced p-n junctions in the uniaxially oriented F8T2 was obtained. The dichroic ratios of EL were the same as those of photoluminescence, suggesting that the doping process into the oriented F8T2 did not interrupt the polymer ordering. This indicates the usefulness of the layered structure of the polymer/electrolyte for the fabrication of LECs based on highly oriented polymer films. In addition, uniaxially oriented F8T2 was found to show reduced threshold energy in optically pumped amplified spontaneous emission. These demonstrations suggest the advantage of uniaxially oriented polymer-based LECs for potential application in future electrically pumped lasers.

High-temperature mechanical properties of a uniaxially reinforced zircon-silicon carbide composite

International Nuclear Information System (INIS)

Singh, R.N.

1990-01-01

This paper reports that mechanical properties of a monolithic zircon ceramic and zircon-matrix composites uniaxially reinforced with either uncoated or BN-coated silicon carbide monofilaments were measured in flexure between 25 degrees and 1477 degrees C. Monolithic zircon ceramics were weak and exhibited a brittle failure up to abut 1300 degrees C. An increasing amount of the plastic deformation was observed before failure above about 1300 degrees C. In contrast, composites reinforced with either uncoated or BN-coated Sic filaments were stronger and tougher than the monolithic zircon at all test temperatures between 25 degrees and 1477 degrees. The ultimate strength and work-of-fracture of composite samples decreased with increasing temperature. A transgranular matrix fracture was shown by the monolithic and composite samples tested up to about 1200 degrees C, whereas an increasing amount of the intergranular matrix fracture was displayed above 1200 degrees C

Unified Drain Current Model of Armchair Graphene Nanoribbons with Uniaxial Strain and Quantum Effect

Directory of Open Access Journals (Sweden)

EngSiew Kang

2014-01-01

Full Text Available A unified current-voltage I-V model of uniaxial strained armchair graphene nanoribbons (AGNRs incorporating quantum confinement effects is presented in this paper. The I-V model is enhanced by integrating both linear and saturation regions into a unified and precise model of AGNRs. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on the tight-binding approximation. Our results reveal the modification of the energy band gap, carrier density, and drain current upon strain. The effects of quantum confinement were investigated in terms of the quantum capacitance calculated from the broadening density of states. The results show that quantum effect is greatly dependent on the magnitude of applied strain, gate voltage, channel length, and oxide thickness. The discrepancies between the classical calculation and quantum calculation were also measured and it has been found to be as high as 19% drive current loss due to the quantum confinement. Our finding which is in good agreement with the published data provides significant insight into the device performance of uniaxial strained AGNRs in nanoelectronic applications.

The effects of different possible modes of uniaxial strain on the ...

Indian Academy of Sciences (India)

Dimple

2017-06-19

Jun 19, 2017 ... Ab-initio density functional theory; band gap; monolayer MoS2 nanosheet; strain. PACS Nos 31.15. ... drawn a surge in research interests. ..... Bader charge analysis of strain-free and uniaxially strained ML−MoS2 nanosheet.

Magnetic phase transitions and hydrostatic pressure or uniaxial stress experiments

International Nuclear Information System (INIS)

Bloch, D.

1980-01-01

Crystals submitted to high hydrostatic pressure or uniaxial stress have been investigated by means of neutron scattering. The techniques used are described and applications to pressure or stress induced T = 0 magnetic to nonmagnetic transitions (Pr,PrSb) and continuous to discontinuous order-disorder transitions (MnO) are given. (orig.)

The Origin of Uni-axial Negative Thermal Expansion in a Layered Perovskite

Science.gov (United States)

Ablitt, Chris; Craddock, Sarah; Senn, Mark; Mostofi, Arash; Bristowe, Nicholas

Using first-principles calculations within the quasi-harmonic approximation (QHA), we explain the origin of experimentally observed uni-axial negative thermal expansion (NTE) in a layered perovskite: the Ruddlesden-Popper (RP) oxide Ca2MnO4, which has anti-ferromagnetic ordering at low temperatures and is closely related to Ca3Mn2O7, which exhibits hybrid improper ferroelectricity and uni-axial NTE in competing phases. Dynamic tilts of MnO6 octahedra, common in many complex oxides, drive the expansion of the a axis and contraction of the c axis of the tetragonal NTE phase. We find that ferroelastic RP phases with a frozen octahedral rotation are unusually compliant to particular combinations of strains along different axes. The atomic mechanism responsible is characteristic of the perovskite/rock-salt interfaces present in the RP structure. We show that the contribution from this anisotropic elasticity must be taken into account in order to accurately predict NTE over the temperature range observed in experiment. A similar compliance to cooperative strains is found in other systems with uni-axial NTE. The development of this mechanistic understanding of NTE in complex oxides may pave the way for designing tunable multifunctional materials. The authors would like to acknowledge support from the EPSRC and the Centre for Doctoral Training in Theory and Simulation of Materials.

General multimode polarization splitter design in uniaxial media

Science.gov (United States)

Teixeira, Poliane A.; Silva, Daniely G.; Gabrielli, Lucas H.; Spadoti, Danilo H.; Junqueira, Mateus A. F. C.

2018-03-01

Quasiconformal transformation optics is used to design two-dimensional polarization beam splitters. The resulting media present inhomogeneous uniaxial permittivity and nonmagnetic response. The compact devices are theoretically designed and investigated for symmetrical and asymmetrical geometries, with footprint of 64 and 110 μm2, respectively. The polarization splitter performance is evaluated for the fundamental mode and third mode, exhibiting an insertion loss closer to 0 dB and extinction ratio above 40 dB over a broad wavelength range.

Molar mass of poly(ethylene terephthalate) (PET) during ultimate uniaxial drawing

NARCIS (Netherlands)

Göschel, U.; Cools, P.J.C.H.

2000-01-01

The changes of the average molar mass Mw, Mn, Mz, and molar mass distributions during multistep uniaxial drawing of poly(ethylene terephthalate) (PET) to achieve ultimate mechanical properties have been studied in detail by means of size exclusion chromatography (SEC) with triple detection:

Molar-Mass of Poly(Ethylene-Terephthalate) (PET) During Ultimate Uniaxial Drawing

NARCIS (Netherlands)

Göschel, A.G.P.U.; Cools, P.J.C.H.

2000-01-01

The changes of the average molar mass Mw, Mn, Mz, and molar mass distributions during multistep uniaxial drawing of poly(ethylene terephthalate) (PET) to achieve ultimate mechanical properties have been studied in detail by means of size exclusion chromatography (SEC) with triple detection:

Uniaxial pressure-induced half-metallic ferromagnetic phase transition in LaMnO3

Science.gov (United States)

Rivero, Pablo; Meunier, Vincent; Shelton, William

2016-03-01

We use first-principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half-metal phase in LaMnO3. We identify the Q2 Jahn-Teller mode as the primary mechanism that drives the transition, indicating that this mode can be used to tune the lattice, charge, and spin coupling. Applying ≃6 GPa of uniaxial pressure along the [010] direction activates the transition to a half-metallic pseudocubic state. The half-metallicity opens the possibility of producing colossal magnetoresistance in the stoichiometric LaMnO3 compound at significantly lower pressure compared to recently observed investigations using hydrostatic pressure.

Parametric Effects of Debris Source, Environments, and Design Options on the Overall Performance of ECCS Recirculation Sump

International Nuclear Information System (INIS)

Park, Jong Woon; Kim, Chang Hyun

2006-01-01

A primary safety issue regarding long-term recirculation core cooling following a LOCA (Loss of Coolant Accident) is that LOCA-generated debris may be transported to the recirculation sump screen, resulting in adverse blockage on the sump screen and deterioration of available NPSH (Net Positive Suction Head) of ECCS (Emergency Core Cooling System). USNRC identified this as Generic Safety Issue (GSI) 191 and issued the Generic Letter 04-02 to resolve the issue. The GL required that all PWR owners perform an engineering assessment of their containment recirculation sumps to ensure they will not suffer from excessive blockage. The guidance report (GR) for PWR sump performance evaluation has been developed by NEI (Nuclear Energy Institute) and approved by the USNRC. In Korea, Korea Hydro and Nuclear Power Company (KHNP) is performing the assessment of Kori unit 1 and planning for remaining plants in the near future. The objective of the assessment is to derive required plant modifications including insulation, sump screen, etc. To derive the cost-effective modification items, we have to get insight on the parametric effects of plant conditions and design. Therefore, the general effects of debris source, containment environments and debris interceptor on the performance of ECCS recirculation sump with respect to head loss are parametrically investigated

NbSe3: Fermi surface and magnetoresistance under uniaxial stress

International Nuclear Information System (INIS)

Tessema, G.X.; Gamble, B.K.; Kuh, J.; Skove, M.J.; Lacerda, A.H.; Bennett, M.

1999-01-01

The Fermi surface of NbSe 3 below the two CDW transitions is still not very clear. Large magnetoresistance and giant quantum oscillations have been seen at low temperature below the second CDW transition. The SdH oscillations are attributed to one or several small pieces of electron or hole pockets spared by the two CDW transitions at 145 and 59 K. In a previous low field study (μ 0 H<8 T) of the transverse magnetoresistance (H in the (b,c) plane) we have shown that the extremal area of one of these pockets decreases linearly with strain, ε, vanishing at ε = 2.5%. Here we extend our study into the high magnetic field regime (pulsed 60 T) and investigate the effect of uniaxial stress on the magnetoresistance (I//H). Our high field study is consistent with the fermiology study and shows that uniaxial stress leads to the obliteration of a small closed pocket. Above 1% strain the magnetoresistance is linear with H with no sign of saturation. (orig.)

An Investigation of the Uniaxial Compressive Strength of a Cemented Hydraulic Backfill Made of Alluvial Sand

Directory of Open Access Journals (Sweden)

Guangsheng Liu

2017-01-01

Full Text Available Backfill is commonly used in underground mines. The quality control of the backfill is a key step to ensure it meets the designed strength requirement. This is done through sample collection from the underground environment, followed by uniaxial compression tests to obtain the Uniaxial Compressive Strength (UCS in the laboratory. When the cylindrical cemented backfill samples are axially loaded to failure, several failure modes can be observed and mainly classified into diagonal shear failure and axial split failure. To date, the UCS obtained by these two failure modes are considered to be the same with no distinction between them. In this paper, an analysis of the UCS results obtained on a cemented hydraulic backfill made of alluvial sand at a Canadian underground mine over the course of more than three years is presented. The results show that the UCS values obtained by diagonal shear failure are generally higher than those obtained by axial split failure for samples with the same recipe and curing time. This highlights the importance of making a distinction between the UCS values obtained by the two different modes of failure. Their difference in failure mechanism is explained. Further investigations on the sources of the data dispersion tend to indicate that the UCS obtained by laboratory tests following the current practice may not be representative of the in-situ strength distribution in the underground stopes due to segregation in cemented hydraulic backfill.

Evaluation report on SCTF Core-III tests S3-7 and S3-8

International Nuclear Information System (INIS)

Okubo, Tsutomu; Iguchi, Tadashi; Iwamura, Takamichi

1990-03-01

It has been said that the Emergency Core Cooling (ECC) water injected into the hot legs flows into the upper plenum and then falls back to the core (i.e. break-through) during reflood phase in a German type Pressurized Water Reactor (GPWR) with the combined-injection-type ECCS, and that the break-through occurs where the water temperature at the tie plate area is lower and subcooled. Based on this information two tests were conducted with the Slab Core Test Facility (SCTF) Core-III in order to investigate the effects of the water temperature distribution at the tie plate area on the break-through and the core cooling. In these tests, the subcooled ECC water was injected just above the Upper Core Support Plate (UCSP) in order to establish the desired water temperature distribution at the tie plate area. In one test (Test S3-7) the ECC water injection above the UCSP was performed above Bundles 3 and 4, and in the other test (Test S3-8) above Bundles 7 and 8 during initial 60 s a and then was changed to above Bundles 3 and 4. The test data were compared with those of Test S3-SH1, in which the injection was performed above Bundles 7 and 8 and the other test conditions were the same as in Tests S3-7 and S3-8. Analyzing these test data, the following has been found: The break-through occurs where the water temperature at the tie plate area is subcooled and the core cooling is enhanced significantly in the break-through region. The break-through location changes, with some time lag, following the change of the water temperature distribution at the tie plate area. Furthermore, the core cooling in the non-break-through regions is almost the same regardless of the location of the break-through. (author)

Change in behavior of uniaxial compression due to degradation of salt water and freezing and thawing for rock

International Nuclear Information System (INIS)

Yamamoto, Kiyohito; Kobayashi, Akira; Aoyama, Shigeyasu

2007-01-01

To investigate the effect of the degradation on the mechanical behavior, the degraded rock samples were prepared to the uniaxial compression test. The degradation methods are divided into two types. One type is submerged in the 10% saline water (10%NaCl) for 90 days, and another one is freezing and thawing for 240 cycles. The degraded Smaland-granites were preserved in saline water. Kurihashi-granodiorite, Tage-tuff and Funyu-tuff were imposed on freezing and thawing test to make degraded state. The damage parameters were identified from the stress-strain relation obtained from the uniaxial compression tests. The damage parameters are K υ , n υ , K d , n d and B 0 . K υ and n υ are related to expansive strain. K d , n d and B 0 are subject to behavior of Young's modulus. By investigating the change in the damage parameters of the degraded rock, the effect of the degradation was tried to infer. As the results, it was inferred using the damage parameters that the Smaland-granite becomes more expansive material and the damage occurs earlier due to saline water degradation. Moreover, it was considered that the Kurihashi-granodiorite and Tage-tuff become more expansive and the axial strain at the failure decreases by freezing and thawing degradation, however the axial strain of the Funyu-tuff at the failure becomes large. It was found the proposed damage parameters can be good index for volumetric strain behavior after degradation. (author)

Uniaxial stress-driven coupled grain boundary motion in hexagonal close-packed metals: A molecular dynamics study

International Nuclear Information System (INIS)

Zong, Hongxiang; Ding, Xiangdong; Lookman, Turab; Li, Ju; Sun, Jun

2015-01-01

Stress-driven grain boundary (GB) migration has been evident as a dominant mechanism accounting for plastic deformation in crystalline solids. Using molecular dynamics (MD) simulations on a Ti bicrystal model, we show that a uniaxial stress-driven coupling is associated with the recently observed 90° GB reorientation in shock simulations and nanopillar compression measurements. This is not consistent with the theory of shear-induced coupled GB migration. In situ atomic configuration analysis reveals that this GB motion is accompanied by the glide of two sets of parallel dislocation arrays, and the uniaxial stress-driven coupling is explained through a composite action of symmetrically distributed dislocations and deformation twins. In addition, the coupling factor is calculated from MD simulations over a wide range of temperatures. We find that the coupled motion can be thermally damped (i.e., not thermally activated), probably due to the absence of the collective action of interface dislocations. This uniaxial coupled mechanism is believed to apply to other hexagonal close-packed metals

Failure Mechanisms of Brittle Rocks under Uniaxial Compression

Science.gov (United States)

Liu, Taoying; Cao, Ping

2017-09-01

The behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

Study on safety analysis of VVER-1200/V491 in scenario of Loss of Coolant Accidents along with partly failure of ECCS using RELAP5 code

International Nuclear Information System (INIS)

Hoang Minh Giang; Ha Thi Anh Dao; Hoang Tan Hung; Bui Thi Hoa; Nguyen Thi Tu Oanh; Dinh Anh Tuan; Pham Tuan Nam

2017-01-01

The advanced VVER-1200/V491 reactor designed with passive safety systems to deal with design extension conditions is primarily selected as priority candidate for Ninh Thuan 1 nuclear power plant project. So that, in order to enhance competence of nuclear safety and toward participation on review Safety Analysis Report (SAR) of Ninh Thuan nuclear Power project the study on safety analysis of VVER-1200/V491 in scenario of Loss of Coolant Accidents along with partly failure of ECCS is implemented. As requirement of the study, the input deck file of VVER-1200/V491 for RELAP5 and analysis report for some special case of LOCAs along with partly failure of ECCS are issued. (author)

Experiment data report for semiscale Mod-1 test S-01-1B (isothermal blowdown with core resistance simulator)

International Nuclear Information System (INIS)

Crapo, H.S.; Jensen, M.F.; Sackett, K.E.; Zender, S.N.

1975-05-01

Recorded test data are presented for Test S-01-1B of the semiscale Mod-1 isothermal blowdown test series. System hardware is representative of the LOFT design, selected using volumetric scaling methods, and initial conditions duplicate those identified for the LOFT nonnuclear tests. Test S-01-1B is a repeat of Test S-01-1 with the exception that simulated ECC was injected into the cold leg of the intact loop rather than into the inlet annulus of the downcomer. The principal objective of Test S-01-1B was to determine whether a different ECC injection would significantly alter the system response during the period of ECC injection. Test S-01-1B was conducted from an initial temperature of 541 0 F and an initial pressure of 1630 psig. A simulated intermediate size double-ended hot leg break (0.00145 ft 2 break area on each end) was used to investigate the system response to a slow de-pressurization transient. An orificed structure was used in the pressure vessel to simulate the LOFT core simulator. Following the blowdown portion of Test S-01-1B, coolant spray was introduced into the pressure suppression tank to determine the response of the pressure suppression system. (U.S.)

Assessment of compliance with regulatory requirements for a best estimate methodology for evaluation of ECCS

Energy Technology Data Exchange (ETDEWEB)

Lee, Un Chul; Jang, Jin Wook; Lim, Ho Gon; Jeong, Ik [Seoul National Univ., Seoul (Korea, Republic of); Sim, Suk Ku [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2000-03-15

Best estimate methodology for evaluation of ECCS proposed by KEPCO(KREM) os using thermal-hydraulic best-estimate code and the topical report for the methodology is described that it meets the regulatory requirement of USNRC regulatory guide. In this research the assessment of compliance with regulatory guide. In this research the assessment of compliance with regulatory requirements for the methodology is performed. The state of licensing procedure of other countries and best-estimate evaluation methodologies of Europe is also investigated, The applicability of models and propriety of procedure of uncertainty analysis of KREM are appraised and compliance with USNRC regulatory guide is assessed.

Hybrid aerogels and bioactive aerogels under uniaxial compression: an in situ SAXS study

Directory of Open Access Journals (Sweden)

Esquivias, L.

2010-12-01

Full Text Available The complex structure of hybrid organic/inorganic aerogels is composed by an inorganic phase covalently bonded to an organic chain forming a copolymer. Conventional hybrid aerogels were studied as well as bioactive hybrid aerogels, that is, aerogels with a calcium active phase added. In this work, the relationship between mechanical response and nanostructure was studied, using a specifically designed sample-holder for in situ uniaxial compression obtaining at the same time the small-angle X-ray pattern from synchrotron radiation (SAXS. Structural elements can be described as a particulated silica core surrounded by the organic chains. These chains are compressed on the direction parallel to the load, and a relationship between macroscopic uniaxial compression and particle and pore deformations can be established.

La compleja estructura de los aerogeles híbridos orgánico/inorgánicos está compuesta por una fase inorgánica de sílice, unida mediante enlaces covalentes a una red de cadenas orgánicas. Se han estudiado composites híbridos convencionales y bioactivos, esto es, con una fase activa de calcio añadida. En este trabajo se ha investigado la relación entre la respuesta mecánica y la nanoestructura, con ayuda de un portamuestras específicamente diseñado para el estudio in situ de muestras bajo compresión uniaxial, a la vez que se obtiene el espectro de rayos-X a bajo-ángulo de radiación sincrotrón (SAXS. Los elementos estructurales se pueden describir como núcleos particulados de sílice rodeados de las cadenas orgánicas. Estas, se comprimen en la dirección paralela a la carga pudiéndose establecer una relación entre la compresión uniaxial macroscópica y la deformación de las partículas y poros que forman la estructura.

Time Dependent and Steady Uni-axial Elongational Viscosity

DEFF Research Database (Denmark)

Nielsen, Jens K.; Rasmussen, Henrik Koblitz; Hassager, Ole

2005-01-01

Here we present measurements of transient and steady uni-axial elongational viscosity, using the Filament Stretching Rheometer1 or FSR1 (see Fig. 1) of the following melts: Four narrow MMD polystyrene (PS) samples with weight-average molar mass Mw in the range of 50k to 390k. Three different bi......-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements....

Experimental research of the influence of the strength of ore samples on the parameters of an electromagnetic signal during acoustic excitation in the process of uniaxial compression

Science.gov (United States)

Yavorovich, L. V.; Bespal`ko, A. A.; Fedotov, P. I.

2018-01-01

Parameters of electromagnetic responses (EMRe) generated during uniaxial compression of rock samples under excitation by deterministic acoustic pulses are presented and discussed. Such physical modeling in the laboratory allows to reveal the main regularities of electromagnetic signals (EMS) generation in rock massive. The influence of the samples mechanical properties on the parameters of the EMRe excited by an acoustic signal in the process of uniaxial compression is considered. It has been established that sulfides and quartz in the rocks of the Tashtagol iron ore deposit (Western Siberia, Russia) contribute to the conversion of mechanical energy into the energy of the electromagnetic field, which is expressed in an increase in the EMS amplitude. The decrease in the EMS amplitude when the stress-strain state of the sample changes during the uniaxial compression is observed when the amount of conductive magnetite contained in the rock is increased. The obtained results are important for the physical substantiation of testing methods and monitoring of changes in the stress-strain state of the rock massive by the parameters of electromagnetic signals and the characteristics of electromagnetic emission.

Critical behaviour of nanocrystalline gadolinium: evidence for random uniaxial dipolar universality class

International Nuclear Information System (INIS)

Ferdinand, A; Probst, A-C; Birringer, R; Michels, A; Kaul, S N

2014-01-01

We report on how nanocrystal size affects the critical behaviour of the rare-earth metal Gd near the ferromagnetic-to-paramagnetic phase transition. The asymptotic critical behaviour of the coarse-grained polycrystalline sample (with an average crystallite size of L≅100 μm) is that of a (pure) uniaxial dipolar ferromagnet, as is the case with single crystal Gd, albeit the width of the asymptotic critical region (ACR) is reduced. As the grain size approaches ∼30 nm, the ACR is so narrow that it could not be accessed in the present experiments. Inaccessibly narrow ACR for L ∼ 30 nm and continuous increase in the width of the ACR as L decreases from 16 to 9.5 nm basically reflect a crossover to the random uniaxial dipolar fixed point caused by the quenched random exchange disorder prevalent at the internal interfaces (grain boundaries). (paper)

Mechanical properties of stanene under uniaxial and biaxial loading: A molecular dynamics study

Energy Technology Data Exchange (ETDEWEB)

Mojumder, Satyajit [Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Amin, Abdullah Al [Department of Mechanical and Aerospace Engineering, Case western Reverse University, Cleveland, Ohio 44106 (United States); Islam, Md Mahbubul, E-mail: mmi122@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2015-09-28

Stanene, a graphene like two dimensional honeycomb structure of tin has attractive features in electronics application. In this study, we performed molecular dynamics simulations using modified embedded atom method potential to investigate mechanical properties of stanene. We studied the effect of temperature and strain rate on mechanical properties of α-stanene for both uniaxial and biaxial loading conditions. Our study suggests that with the increasing temperature, both the fracture strength and strain of the stanene decrease. Uniaxial loading in zigzag direction shows higher fracture strength and strain compared to the armchair direction, while no noticeable variation in the mechanical properties is observed for biaxial loading. We also found at a higher loading rate, material exhibits higher fracture strength and strain. These results will aid further investigation of stanene as a potential nano-electronics substitute.

Industry Application ECCS / LOCA Integrated Cladding/Emergency Core Cooling System Performance: Demonstration of LOTUS-Baseline Coupled Analysis of the South Texas Plant Model

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hongbin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Szilard, Ronaldo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Epiney, Aaron [Idaho National Lab. (INL), Idaho Falls, ID (United States); Parisi, Carlo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Vaghetto, Rodolfo [Texas A & M Univ., College Station, TX (United States); Vanni, Alessandro [Texas A & M Univ., College Station, TX (United States); Neptune, Kaleb [Texas A & M Univ., College Station, TX (United States)

2017-06-01

Under the auspices of the DOE LWRS Program RISMC Industry Application ECCS/LOCA, INL has engaged staff from both South Texas Project (STP) and the Texas A&M University (TAMU) to produce a generic pressurized water reactor (PWR) model including reactor core, clad/fuel design and systems thermal hydraulics based on the South Texas Project (STP) nuclear power plant, a 4-Loop Westinghouse PWR. A RISMC toolkit, named LOCA Toolkit for the U.S. (LOTUS), has been developed for use in this generic PWR plant model to assess safety margins for the proposed NRC 10 CFR 50.46c rule, Emergency Core Cooling System (ECCS) performance during LOCA. This demonstration includes coupled analysis of core design, fuel design, thermalhydraulics and systems analysis, using advanced risk analysis tools and methods to investigate a wide range of results. Within this context, a multi-physics best estimate plus uncertainty (MPBEPU) methodology framework is proposed.

Ultrasonic detection of cracks in uniaxial glass fibre rods

CSIR Research Space (South Africa)

Loveday, PW

2006-01-01

Full Text Available Conference on Computational and Applied Mechanics SACAM06 Cape Town, 16-18 January 2006 �SACAM ULTRASONIC DETECTION OF CRACKS IN UNIAXIAL GLASS FIBRE RODS Derren Wood and Philip Loveday Sensor Science and Technology, CSIR Materials Science... means of detecting internal and/or surface damage in composites which is safe, quick and relatively cost effective. Various ultrasonic techniques have been applied in the past to detect defects in composite media, the most well known being perhaps...

Evaluation of Concrete Cylinder Tests Using Finite Elements

DEFF Research Database (Denmark)

Saabye Ottosen, Niels

1984-01-01

Nonlinear axisymmetric finite element analyses are performed on the uniaxial compressive test of concrete cylinders. The models include thick steel loading plates, and cylinders with height‐to‐diameter ratios (h/d) ranging from 1‐3 are treated. A simple constitutive model of the concrete is emplo......Nonlinear axisymmetric finite element analyses are performed on the uniaxial compressive test of concrete cylinders. The models include thick steel loading plates, and cylinders with height‐to‐diameter ratios (h/d) ranging from 1‐3 are treated. A simple constitutive model of the concrete...... uniaxial strength the use of geometrically matched loading plates seems to be advantageous. Finally, it is observed that for variations of the element size within limits otherwise required to obtain a realistic analysis, the results are insensitive to the element size....

Mechanical stability of Ni and Ir under hydrostatic and uniaxial loading

Czech Academy of Sciences Publication Activity Database

Řehák, Petr; Černý, Miroslav; Šob, Mojmír

2015-01-01

Roč. 23, č. 5 (2015), art. n. 055010 ISSN 0965-0393 R&D Projects: GA ČR(CZ) GAP108/12/0311 Institutional support: RVO:68081723 Keywords : ab initio calculations * elastic stability * phonon instability * theoretical strength * hydrostatic loading * uniaxial loading Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.859, year: 2015

Strength and stiffness of uniaxially tensioned reinforced concrete panels subjected to membrane shear. Technical report

International Nuclear Information System (INIS)

Hilmy, S.I.; White, R.N.; Gergely, P.

1982-06-01

This report presents experimental and analytical results on internal pressurization effects and seismic shear effects in a concrete containment vessel that is cracked by tension in one direction only. The experimental program, which was restricted to 6 in. thick flat specimens with two-way reinforcement, included establishment of (a) extensional stiffness for uniaxially tensioned specimens stressed to 0.6fy, and (b) shear strength and stiffness of these cracked specimens with tension levels ranging from 0 to 0.9fy; values were about 10 to 15 percent higher than in similar biaxially tensioned specimens. Eleven (11) specimens were tested (6 in monotonic shear and 5 in reversing cyclic shear)

The Landau-de Gennes theory of nematic liquid crystals: Uniaxiality versus Biaxiality

KAUST Repository

Majumdar, Apala

2011-12-01

We study small energy solutions within the Landau-de Gennes theory for nematic liquid crystals, subject to Dirichlet boundary conditions. We consider two-dimensional and three-dimensional domains separately. In the two-dimensional case, we establish the equivalence of the Landau-de Gennes and Ginzburg-Landau theory. In the three-dimensional case, we give a new definition of the defect set based on the normalized energy. In the threedimensional uniaxial case, we demonstrate the equivalence between the defect set and the isotropic set and prove the C 1,α-convergence of uniaxial small energy solutions to a limiting harmonic map, away from the defect set, for some 0 < a < 1, in the vanishing core limit. Generalizations for biaxial small energy solutions are also discussed, which include physically relevant estimates for the solution and its scalar order parameters. This work is motivated by the study of defects in liquid crystalline systems and their applications.

Hierarchically mesoporous silica materials prepared from the uniaxially stretched polypropylene membrane and surfactant templates

International Nuclear Information System (INIS)

Wang Xiaocong; Ma Jin; Liu Jin; Zhou Chen; Zhao, Yan; Yi Shouzhi; Yang Zhenzhong

2006-01-01

Hierarchically mesoporous silica materials with a bimodal distribution were template-prepared from uniaxially stretched polypropylene membrane in the presence of a surfactant via a sol-gel process. Their regularity and morphologies were characterized by transmission electron microscopy (TEM), x-ray diffraction and Brunauer-Emmett-Teller (BET) surface area analysis. The larger channel pores formed by removing the microfibrils of uniaxially stretched polypropylene membrane have a broad pore size distribution, and their size is around 13 nm. In contrast, the smaller mesopores formed by surfactant templates have a narrow distribution; their size is about 3.9 nm. The size of the smaller pores could be tuned from 2 to 6 nm by selecting different surfactants and by changing the concentration of reactants

Self-focusing in uniaxial gyrotropic media. Qualitative and numerical investigation

DEFF Research Database (Denmark)

Karpman, V.I.; Shagalov, A.G.

1992-01-01

We consider the self-focusing in uniaxial gyrotropic media at axially symmetric geometry, i.e., when the wave beam and the gyration vector g are parallel to the principal axis. Dissipation is neglected and the nonlinearity is of the Kerr type. It is shown that when g is directed along the wave no...... beam is formed. The results obtained are beyond the theory based on the nonlinear Schrodinger equation....

A Secure ECC-based RFID Mutual Authentication Protocol to Enhance Patient Medication Safety.

Science.gov (United States)

Jin, Chunhua; Xu, Chunxiang; Zhang, Xiaojun; Li, Fagen

2016-01-01

Patient medication safety is an important issue in patient medication systems. In order to prevent medication errors, integrating Radio Frequency Identification (RFID) technology into automated patient medication systems is required in hospitals. Based on RFID technology, such systems can provide medical evidence for patients' prescriptions and medicine doses, etc. Due to the mutual authentication between the medication server and the tag, RFID authentication scheme is the best choice for automated patient medication systems. In this paper, we present a RFID mutual authentication scheme based on elliptic curve cryptography (ECC) to enhance patient medication safety. Our scheme can achieve security requirements and overcome various attacks existing in other schemes. In addition, our scheme has better performance in terms of computational cost and communication overhead. Therefore, the proposed scheme is well suitable for patient medication systems.

Anomalous dispersion properties of TM waves in subwavelength metallic waveguides loaded by uniaxial metamaterials

Energy Technology Data Exchange (ETDEWEB)

Wang, Guanghui, E-mail: wanggh@scnu.edu.cn; Lei, Yuandong; Zhang, Weifeng

2015-02-20

Dispersion properties of transverse magnetic (TM) waves in a subwavelength metallic waveguide loaded by uniaxial metamaterials are investigated, based on two kinds of uniaxial metamaterials with different orientations of optical axis. The numerical results show that the existence of fundamental TM{sub 0} mode and high-order TM modes in the waveguide system is dependent on the orientation of optical axis. In addition, their anomalous dispersion properties are clarified. When the orientation of optical axis is selected properly, there are two branches of dispersion curves for each high-order mode—one is normal dispersion and another belongs to anomalous dispersion, showing a transition from a backward wave to a forward one with the increase of working frequency. Moreover, the group velocity and energy flow distribution for TM{sub 1} mode are also demonstrated. These properties may have potential applications in optical information storage, integrated optics and nanophotonic devices. - Highlights: • Two kinds of subwavelength uniaxial metamaterial waveguides are constructed. • We demonstrate anomalous dispersion properties of transverse magnetic (TM) guided modes. • There are two branches of dispersion curves for high-order TM modes, showing a transition from a backward wave to a forward one. • Group velocity can approach to zero, having potential application in optical information storage. • Negative group velocity and energy flow distribution for TM modes are shown.

Safety design/analysis and scenario for prevention of CDA with ECCS in lead-bismuth-cooled fast reactor

International Nuclear Information System (INIS)

Minoru, Takahashi; Vaclav, Dostal; Abu Khalid, Rivai; Novitrian; Yumi, Yamada

2007-01-01

Safety design has been developed to show safety feature of Pb-Bi-cooled direct contact boiling water small fast reactor (PBWFR). The core is designed to have negative void reactivity even if the entire core and upper plenum are voided by steam intrusion from above. In-vessel type control rod driving mechanisms are used to prevent control rods from accidental ejection due to high pressure in the reactor vessel. In cases of coolant leakage from reactor vessel and feed water pipes, Pb-Bi coolant level in the reactor vessel is kept at the required level for decay heat removal by means of closed type guard vessel. Dual pipes are adopted to avoid leak of water in the feedwater system. Pump trip in feedwater systems initiates loss of coolant flow (LOF) event, although there is no concern of loss of flow accident due to primary pump trip. Injection of high pressure water slows down the flow-coast-down of feedwater at the LOF event. It has been evaluated that the fuel temperature is kept lower than safety limits at the unprotected loss of flow and heat sink (ATWS). A scenario for prevention of the core disruptive accident (CDA) with the emergency core cooling system (ECCS) is examined. The reactor becomes super-critical when the reactor vessel is filled with water. It is necessary to use water with boric acid for the ECC system, and additional backup rods for sub-critical core in water injection. (authors)

Multiple scattering of a zero-order Bessel beam with arbitrary incidence by an aggregate of uniaxial anisotropic spheres

International Nuclear Information System (INIS)

Li, Z.J.; Wu, Z.S.; Qu, T.; Shang, Q.C.; Bai, L.

2016-01-01

Based on the generalized multiparticle Mie theory, multiple scattering of an aggregate of uniaxial anisotropic spheres illuminated by a zero-order Bessel beam (ZOBB) with arbitrary propagation direction is investigated. The particle size and configuration are arbitrary. The arbitrary incident Bessel beam is expanded in terms of spherical vector wave functions (SVWFs). Utilizing the vector addition theorem of SVWFs, interactive and total scattering coefficients are derived through the continuous boundary conditions on which the interaction of the particles is considered. The accuracy of the theory and codes are verified by comparing results with those obtained for arbitrary plane wave incidence by CST simulation, and for ZOBB incidence by a numerical method. The effects of angle of incidence, pseudo-polarization angle, half-conical angle, beam center position, and permittivity tensor elements on the radar cross sections (RCSs) of several types of collective uniaxial anisotropic spheres, such as a linear chain, a 4×4×4 cube-shaped array, and other periodical structures consisting of massive spheres, are numerically analyzed. Selected results on the properties of typical particles such as TiO 2 , SiO 2 , or other particle lattices are calculated. This investigation could provide an effective test for further research on the scattering characteristics of an aggregate of anisotropic spheres by a high-order Bessel vortex beam. The results have important application in optical tweezers and particle manipulation. - Highlights: • Scattering of Bessel beam by an aggregate of uniaxial anisotropic spheres is studied. • The zero-order Bessel beam propagates and polarizes along arbitrary direction. • The accuracy of expansion coefficients, the scattering theory and codes is verified. • Effects of various parameters on scattering properties are numerically discussed. • Scattering properties of several type of periodical array are numerically analyzed.

Hydrostatic-pressure and uniaxial-strain experiments for controlling the spin-Peierls transition

International Nuclear Information System (INIS)

Mito, Masaki; Deguchi, Hiroyuki; Fujita, Wataru; Kondo, Ryusuke; Kagoshima, Seiichi

2010-01-01

The spin-Peierls (SP) system is considered to be a quantum spin system strongly coupled with the lattice. We have succeeded in controlling SP transition by applying hydrostatic pressure and/or uniaxial strain. The observed phenomenon could be a typical example for understanding the SP transition based on the Hamiltonian. (author)

Self-assembly of heterogeneous supramolecular structures with uniaxial anisotropy.

Science.gov (United States)

Ruiz-Osés, M; Gonzalez-Lakunza, N; Silanes, I; Gourdon, A; Arnau, A; Ortega, J E

2006-12-28

Uniaxial anisotropy in two-dimensional self-assembled supramolecular structures is achieved by the coadsorption of two different linear molecules with complementary amine and imide functionalization. The two-dimensional monolayer is defined by a one-dimensional stack of binary chains, which can be forced to line up along steps in vicinal surfaces. The competing driving forces in the self-organization process are discussed in light of the structures observed during single molecule adsorption and coadsorption on flat and vicinal surfaces and the corresponding theoretical calculations.

Verification of the code ATHLET by post-test analysis of two experiments performed at the CCTF integral test facility

International Nuclear Information System (INIS)

Krepper, E.; Schaefer, F.

2001-03-01

In the framework of the external validation of the thermohydraulic code ATHLET Mod 1.2 Cycle C, which has been developed by the GRS, post test analyses of two experiments were done, which were performed at the japanese test facility CCTF. The test facility CCTF is a 1:25 volume-scaled model of a 1000 MW pressurized water reactor. The tests simulate a double end break in the cold leg of the PWR with ECC injection into the cold leg and with combined ECC injection into the hot and cold legs. The evaluation of the calculated results shows, that the main phenomena can be calculated in a good agreement with the experiment. Especially the behaviour of the quench front and the core cooling are calculated very well. Applying a two-channel representation of the reactor model the radial behaviour of the quench front could be reproduced. Deviations between calculations and experiment can be observed simulating the emergency injection in the beginning of the transient. Very high condensation rates were calculated and the pressure decrease in this phase of the transient is overestimated. Besides that, the pressurization due to evaporation in the refill phase is underestimated by ATHLET. (orig.) [de

Stable evaluation of Green's functions in cylindrically stratified regions with uniaxial anisotropic layers

Science.gov (United States)

Moon, H.; Donderici, B.; Teixeira, F. L.

2016-11-01

We present a robust algorithm for the computation of electromagnetic fields radiated by point sources (Hertzian dipoles) in cylindrically stratified media where each layer may exhibit material properties (permittivity, permeability, and conductivity) with uniaxial anisotropy. Analytical expressions are obtained based on the spectral representation of the tensor Green's function based on cylindrical Bessel and Hankel eigenfunctions, and extended for layered uniaxial media. Due to the poor scaling of these eigenfunctions for extreme arguments and/or orders, direct numerical evaluation of such expressions can produce numerical instability, i.e., underflow, overflow, and/or round-off errors under finite precision arithmetic. To circumvent these problems, we develop a numerically stable formulation through suitable rescaling of various expressions involved in the computational chain, to yield a robust algorithm for all parameter ranges. Numerical results are presented to illustrate the robustness of the formulation including cases of practical interest.

A fiber bundle-plastic chain model for quasi-brittle materials under uniaxial loading

International Nuclear Information System (INIS)

Shan, Zhi; Yu, Zhiwu

2015-01-01

A fiber bundle-plastic chain model for quasi-brittle materials under both uniaxial compression and tension conditions is developed. By introducing a plastic chain model into the fiber bundle model, a bundle-chain model for quasi-brittle materials is proposed with physical considerations. The model achieves a novel and convenient approach to describe the stochastic effective stress-driven plasticity. It is found that the numerical solutions obtained with this model agree with experimental results when subjected to both monotonic and cyclic uniaxial loading. The model generates a numerical solution with higher accuracy than the present models, when compared with the experimental results on certain problems. An example is shown which utilizes this model to describe the stochastic properties of a constitutive model given as standard. Furthermore, the difference between the existing plastic fiber bundle models in the literature and this model is also obtained in this work. (paper)

Comparative study of fracture mechanical test methods for concrete

DEFF Research Database (Denmark)

Østergaard, Lennart; Olesen, John Forbes

2004-01-01

and the interpretation, i.e. the analysis needed to extract the stress-crack opening relationship, the fracture energy etc. Experiments are carried out with each test configuration using mature, high performance concrete. The results show that the UTT is a highly complicated test, which only under very well controlled...... circumstances will yield the true fracture mechanical properties. It is also shown that both the three point bending test and the WST are well-suited substitutes for the uniaxial tension test.......This paper describes and compares three different fracture mechanical test methods; the uniaxial tension test (UTT), the three point bending test (TPBT) and the wedge splitting test (WST). Potentials and problems with the test methods will be described with regard to the experiment...

High pressure measurement of the uniaxial stress of host layers on intercalants and staging transformation of intercalation compounds

CERN Document Server

Park, T R; Kim, H; Min, P

2002-01-01

A layered double-hydroxide intercalation compound was synthesized to measure the uniaxial stress the host layers exert on the intercalants. To measure the uniaxial stress, we employed the photoluminescence (PL) from the intercalated species, the Sm ion complex, as it is sensitive to the deformation of the intercalants. Of the many PL peaks the Sm ion complex produces, the one that is independent of the counter-cation environment was chosen for the measurement since the Sm ion complexes are placed under a different electrostatic environment after intercalation. The peak position of the PL was redshifted linearly with increasing hydrostatic pressure on the intercalated sample. Using this pressure-induced redshifting rate and the PL difference at ambient pressure between the pre-intercalation and the intercalated ions, we found that, in the absence of external pressure, the uniaxial stress exerted on the samarium ion complexes by the host layers was about 13.9 GPa at room temperature. Time-resolved PL data also ...

Structural and electronic properties of armchair graphene nanoribbons under uniaxial strain

Science.gov (United States)

Qu, Li-Hua; Zhang, Jian-Min; Xu, Ke-Wei; Ji, Vincent

2014-02-01

We theoretically investigate the structures, relative stabilities and electronic properties of the armchair graphene nanoribbons (AGNRs) under uniaxial strain via first-principles calculations. The results show that, although each bond length decreases (increases) with increasing compression (tension) strain especially for the axial bonds a1, a4 and a7, the ribbon geometrical width d increases (decreases) with increasing compression (tension) strain due to the rotation of the zigzag bonds a2, a3, a5 and a6. For each nanoribbon, as expected, the lowest average energy corresponds to the unstrained state and the larger contract (elongate) deformation corresponds to the higher average energy. At a certain strain, the average energy increases with decreasing the ribbon width n. The average energy increases quadratically with the absolute value of the uniaxial strain, showing an elastic behavior. The dependence of the band gap on the strain is sensitive to the ribbon width n which can be classified into three distinct families n=3I, 3I+1 and 3I+2, where I is an integer. The ribbon width leads to oscillatory band gaps due to quantum confinement effect.

Effect of uniaxial strain on the tunnel magnetoresistance of T-shaped graphene nanoribbon based spin-valve

Science.gov (United States)

Fouladi, A. Ahmadi

2016-07-01

We theoretically investigated the spin-dependent transport through a T-shaped graphene nanoribbon (TsGNR) based spin-valve consisting of armchair graphene sandwiched between two semi-infinite ferromagnetic armchair graphene nanoribbon leads in the presence of an applied uniaxial strain. Based on a tight-binding model and standard nonequilibrium Green's function technique, it is demonstrated that the tunnel magnetoresistance (TMR) for the system can be increased about 98% by tuning the uniaxial strain. Our results show that the absolute values of TMR around the zero bias voltage for compressive strain are larger than tensile strain. In addition, the TMR of the system can be nicely controlled by GNR width.

Mechanical and microstructural stability of P92 steel under uniaxial tension at high temperature

International Nuclear Information System (INIS)

Giroux, P.F.; Dalle, F.; Sauzay, M.; Malaplate, J.; Fournier, B.; Gourgues-Lorenzon, A.F.

2010-01-01

9-12%Cr creep-resistant ferritic-martensitic steels are candidates for structural components of Generation IV nuclear power plants. However, they are sensitive to softening during low-cycle fatigue, creep and creep-fatigue tests, due to the destabilisation of the tempered martensite microstructure, possibly inducing a decrease in further creep resistance. To better identify the softening mechanisms in P92 steel during uniaxial deformation, tensile tests were carried out at 823 K, showing an extended and stable softening stage on true stress-strain curves after some work-hardening. Three phenomena were studied in order to understand this behaviour: mechanical instability (necking), damage and grain size evolution. Examination of fractured and non-fractured tensile specimens (light optical and electron microscopy, macrohardness) suggested that the physical mechanisms responsible for softening are mainly (sub)grain size evolution and diffuse necking. Models were proposed to predict grain growth and beginning of the mechanical instability during homogeneous deformation.

Determination of Hot-Carrier Distribution Functions in Uniaxially Stressed p-Type Germanium

DEFF Research Database (Denmark)

Christensen, Ove

1973-01-01

This paper gives a description of an experimental determination of distribution functions in k→ space of hot holes in uniaxially compressed germanium. The hot-carrier studies were made at 85°K at fields up to 1000 V/cm and uniaxial stresses up to 11 800 kg/cm2. The field and stress were always in...... probabilities with stress. A model based on the nonparabolicity of the upper p3 / 2 level is proposed for the negative differential conductivity in stressed p-type Ge....... function has been assumed. The parameters of the distribution function are then fitted to the experimental modulation. The calculation of absorption was performed numerically, using a four-band k→·p→ model. This model was checked for consistency by comparing with piezoabsorption measurements performed...... in thermal equilibrium. The average carrier energy calculated from the distribution function shows a fast increase with stress and almost saturates when the strain splitting of the two p3 / 2 levels reaches the optical-phonon energy. This saturation is interpreted in terms of the change in scattering...

Kinetics of interstitial defects in α-Fe: The effect from uniaxial stress

Energy Technology Data Exchange (ETDEWEB)

Kang, Changwoo [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77843 (United States); Wang, Qingyu [College of Nuclear Science and Technology, Harbin Engineering University, Harbin 150001 (China); Shao, Lin, E-mail: lshao@tamu.edu [Department of Nuclear Engineering, Texas A& M University, College Station, TX 77843 (United States)

2017-03-15

Understanding defect kinetics in a stress field is important for multiscale modeling of materials degradation of nuclear materials. By means of molecular dynamics and molecular statics simulations, we calculate formation and migration energies of self-interstitial atoms (SIA) and SIA clusters (up to size of 5 interstitials) in alpha Fe and identify their stable configurations under uniaxial tensile strains. By applying uniaxial stress along [111], <111> oriented single SIA defects become more stable than <110> oriented SIA, which is opposite to stress-free condition. Diffusion of single SIA defects under [111] tensile stress is facilitated along [111] direction and the diffusion becomes one dimensional (1D). For SIA clusters, their diffusion under zero stress has gradual transition from three dimensional (3D) for small clusters to one dimensional (1D) for large clusters. Under the tensile stress along [111], the 3D to 1D transition is accelerated. For large SIA clusters, the stress effect is quickly saturated with less diffusivity enhancement in comparison with small SIA clusters.

Symmetry of Uniaxial Global Landau--de Gennes Minimizers in the Theory of Nematic Liquid Crystals

KAUST Repository

Henao, Duvan; Majumdar, Apala

2012-01-01

We extend the recent radial symmetry results by Pisante [J. Funct. Anal., 260 (2011), pp. 892-905] and Millot and Pisante [J. Eur. Math. Soc. (JEMS), 12 (2010), pp. 1069- 1096] (who show that the equivariant solutions are the only entire solutions of the three-dimensional Ginzburg-Landau equations in superconductivity theory) to the Landau-de Gennes framework in the theory of nematic liquid crystals. In the low temperature limit, we obtain a characterization of global Landau-de Gennes minimizers, in the restricted class of uniaxial tensors, in terms of the well-known radial-hedgehog solution. We use this characterization to prove that global Landau-de Gennes minimizers cannot be purely uniaxial for sufficiently low temperatures. Copyright © by SIAM.

Mechanical behavior and dynamic failure of high-strength ultrafine grained tungsten under uniaxial compression

International Nuclear Information System (INIS)

Wei, Q.; Jiao, T.; Ramesh, K.T.; Ma, E.; Kecskes, L.J.; Magness, L.; Dowding, R.; Kazykhanov, V.U.; Valiev, R.Z.

2006-01-01

We have systematically investigated the quasi-static and dynamic mechanical behavior (especially dynamic failure) of ultra-fine grained (UFG) tungsten (W) under uniaxial compression. The starting material is of commercial purity and large grain size. We utilized severe plastic deformation to achieve the ultrafine microstructure characterized by grains and subgrains with sizes of ∼500 nm, as identified by transmission electron microscopy. Results of quasi-static compression show that the UFG W behaves in an elastic-nearly perfect plastic manner (i.e., vanishing strain hardening), with its flow stress approaching 2 GPa, close to twice that of conventional coarse grain W. Post-mortem examinations of the quasi-statically loaded samples show no evidence of cracking, in sharp contrast to the behavior of conventional W (where axial cracking is usually observed). Under uniaxial dynamic compression (strain rate ∼10 3 s -1 ), the true stress-true strain curves of the UFG W exhibit significant flow softening, and the peak stress is ∼3 GPa. Furthermore, the strain rate sensitivity of the UFG W is reduced to half the value of the conventional W. Both in situ high-speed photography and post-mortem examinations reveal shear localization and as a consequence, cracking of the UFG W under dynamic uniaxial compression. These observations are consistent with recent observations on other body-centered cubic metals with nanocrystalline or ultrafine microstructures. The experimental results are discussed using existing models for adiabatic shear localization in metals

Determination of area reduction rate by continuous ball indentation test

International Nuclear Information System (INIS)

Zou, Bin; Guan, Kai Shu; Wu, Sheng Bao

2016-01-01

Rate of area reduction is an important mechanical property to appraise the plasticity of metals, which is always obtained from the uniaxial tensile test. A methodology is proposed to determine the area reduction rate by continuous ball indentation test technique. The continuum damage accumulation theory has been adopted in this work to identify the failure point in the indentation. The corresponding indentation depth of this point can be obtained and used to estimate the area reduction rate. The local strain limit criterion proposed in the ASME VIII-2 2007 alternative rules is also adopted in this research to convert the multiaxial strain of indentation test to uniaxial strain of tensile test. The pile-up and sink-in phenomenon which can affect the result significantly is also discussed in this paper. This method can be useful in engineering practice to evaluate the material degradation under severe working condition due to the non-destructive nature of ball indentation test. In order to validate the method, continuous ball indentation test is performed on ferritic steel 16MnR and ASTM (A193B16), then the results are compared with that got from the traditional uniaxial tensile test.

Effect of uniaxial stress on the electrochemical properties of graphene with point defects

Science.gov (United States)

Szroeder, Paweł; Sagalianov, Igor Yu.; Radchenko, Taras M.; Tatarenko, Valentyn A.; Prylutskyy, Yuriy I.; Strupiński, Włodzimierz

2018-06-01

We report a calculational study of electron states and the resulting electrochemical properties of uniaxially strained graphene with point defects. For this study the reduction of ferricyanide to ferrocyanide serves as a benchmark electrochemical reaction. We find that the heterogeneous electron transfer activity of the perfect graphene electrode rises under uniaxial strain. However, evolution of the cathodic reaction rate depends on the direction of strain. For moderate lattice deformations, the zigzag strain improves electrochemical performance better than the armchair strain. Standard rate constant increases by 50% at the zigzag strain of 10%. Vacancies, covalently bonded moieties, charged adatoms and substitutional impurities in the zigzag strained graphene induce changes in the shape of the curve of the cathodic reaction rate. However, this changes do not translate into the electrocatalytic activity. Vacancies and covalently bonded moieties at concentration of 0.1% do not affect the electrochemical performance. Charged adatoms and substitutional impurities give a slight increase in the standard rate constant by, respectively, 2.2% and 3.4%.

Experiment data report for Semiscale Mod-1 Test S-05-4 (alternate ECC injection test)

International Nuclear Information System (INIS)

Collins, B.L.; Feldman, E.M.

1977-03-01

Recorded test data are presented for Test S-05-4 of the Semiscale Mod-1 alternate emergency core coolant injection test series. These tests are among several Semiscale Mod-1 experiments conducted to investigate the thermal and hydraulic phenomena accompanying a hypothesized loss-of-coolant accident in a pressurized water reactor (PWR) system. Test S-05-4 was conducted from initial conditions of 2266 psia and 543 0 F to investigate the response of the Semiscale Mod-1 system to a depressurization and reflood transient following a simulated double-ended offset shear of the cold leg broken loop piping. During the test, cooling water was injected into the cold leg of each loop and into the vessel upper plenum to simulate emergency core coolant injection in a PWR. The upper plenum coolant injection was scaled according to the heat stored in the metal mass of the upper plenum

Investigation of the use of uniaxial comb-shaped Galfenol patches for a guided wave-based magnetostrictive phased array sensor

Science.gov (United States)

Yoo, Byungseok; Pines, Darryll J.

2018-05-01

This paper investigates the use of uniaxial comb-shaped Fe-Ga alloy (Galfenol) patches in the development of a Magnetostrictive Phased Array Sensor (MPAS) for the Guided Wave (GW) damage inspection technique. The MPAS consists of six highly-textured Galfenol patches with a preferred orientation and a Hexagonal Magnetic Circuit Device (HMCD). The Galfenol patches individually aligned to distinct azimuthal directions were permanently attached to a thin aluminum plate specimen. The detachable HMCD encloses a biasing magnet and six sensing coils with unique directional sensing preferences, equivalent to the specific orientation of the discrete Galfenol patches. The preliminary experimental tests validated that the GW sensing performance and directional sensitivity of the Galfenol-based sensor were significantly improved by the magnetic shape anisotropy effect on the fabrication of uniaxial comb fingers to a Galfenol disc patch. We employed a series of uniaxial comb-shaped Galfenol patches to form an MPAS with a hexagonal sensor configuration, uniformly arranged within a diameter of 1". The Galfenol MPAS was utilized to identify structural damage simulated by loosening joint bolts used to fasten the plate specimen to a frame structure. We compared the damage detection results of the MPAS with those of a PZT Phased Array Sensor (PPAS) collocated to the back surface of the plate. The directional filtering characteristic of the Galfenol MPAS led to acquiring less complicated GW signals than the PPAS using omnidirectional PZT discs. However, due to the detection limit of the standard hexagonal patterned array, the two array sensors apparently identified only the loosened bolts located along one of the preferred orientations of the array configuration. The use of the fixed number of the Galfenol patches for the MPAS construction constrained the capability of sensing point multiplication of the HMCD by altering its rotational orientation, resulting in such damage detection

Propagation of high-order circularly polarized Bessel beams and vortex generation in uniaxial crystals

CSIR Research Space (South Africa)

Belyi, VN

2011-05-01

Full Text Available The authors investigate the generation and transformation of Bessel beams through linear and nonlinear optical crystals. They outline the generation of high-order vortices due to propagation of Bessel beams along the optical axis of uniaxial...

Characteristics of Xanthosoma sagittifolium roots during cooking, using physicochemical analysis, uniaxial compression, multispectral imaging and low field NMR spectroscopy

DEFF Research Database (Denmark)

Boakye, Abena Achiaa; Gudjónsdóttir, María; Skytte, Jacob Lercke

2017-01-01

and white varieties of cocoyam roots were thus analysed by low field nuclear magnetic resonance relaxometry, multispectral imaging, uniaxial compression testing, and relevant physicochemical analysis in the current study. Both varieties had similar dry matter content, as well as physical and mechanical...... of that spectral region for rapid analysis of dry matter and water content of the roots. The small, but significant differences in the structural and gelatinization characteristics of the two varieties indicated that they may not be equally suited for further processing, e.g. to flours or starches. Processors thus...

Measuring the complex permittivity tensor of uniaxial biological materials with coplanar waveguide transmission line

Science.gov (United States)

A simple and accurate technique is described for measuring the uniaxial permittivity tensor of biological materials with a coplanar waveguide transmission-line configuration. Permittivity tensor results are presented for several chicken and beef fresh meat samples at 2.45 GHz....

Laboratory Testing of Silica Sol Grout in Coal Measure Mudstones

Directory of Open Access Journals (Sweden)

Dongjiang Pan

2016-11-01

Full Text Available The effectiveness of silica sol grout on mudstones is reported in this paper. Using X-ray diffraction (XRD, the study investigates how the silica sol grout modifies mudstone mineralogy. Micropore sizes and mechanical properties of the mudstone before and after grouting with four different materials were determined with a surface area/porosity analyser and by uniaxial compression. Tests show that, after grouting, up to 50% of the mesopore volumes can be filled with grout, the dominant pore diameter decreases from 100 nm to 10 nm, and the sealing capacity is increased. Uniaxial compression tests of silica sol grouted samples shows that their elastic modulus is 21%–38% and their uniaxial compressive strength is 16%–54% of the non-grouted samples. Peak strain, however, is greater by 150%–270%. After grouting, the sample failure mode changes from brittle to ductile. This paper provides an experimental test of anti-seepage and strengthening properties of silica sol.

Optical conoscopy of distorted uniaxial liquid crystals: computer simulation and experiment

OpenAIRE

Yu.A.Nastishin; O.B.Dovgyi; O.G.Vlokh

2001-01-01

We propose an algorithm to compute the conoscopic pattern for distorted uniaxial liquid crystal cells. The computed conoscopic figures for several cells (homeotropic, planar, twist, hybrid, hybrid under an external field) are compared to the corresponding experimental conoscopic patterns. We demonstrate that conoscopy can be used for the characterization of the distorted nematic cells with the director deformations which can not be detected and unambigously characterized by direct microscopy ...

Theoretical study of Cherenkov radiation emission in anisotropic uniaxial crystals

Energy Technology Data Exchange (ETDEWEB)

Delbart, A; Derre, J

1996-04-01

A theoretical review of the Cherenkov radiation emission in uniaxial crystals is presented. The formalism of C. Muzicar in terms of energetic properties of the emitted waves are corrected. This formalism is used to simulate the Cherenkov radiation emission in a strongly birefringent sodium nitrate crystal (NaNO{sub 3}) and to investigate the consequences of the slight anisotropy of sapphire (Al{sub 2}O{sub 3}) on the design of the Optical Trigger. (author). 12 refs. Submitted to Physical Review, D (US).

Pressure vessel fracture studies pertaining to a PWR LOCA-ECC thermal shock: experiments TSE-3 and TSE-4 and update of TSE-1 and TSE-2 analysis

International Nuclear Information System (INIS)

Cheverton, R.D.; Bolt, S.E.

1977-01-01

The LOCA-ECC Thermal Shock Program was established to investigate the potential for flaw propagation in pressurized-water reactor (PWR) vessels during injection of emergency core coolant following a loss-of-coolant accident. Studies thus far have included fracture mechanics analyses of typical PWRs, the design and construction of a thermal shock test facility, determination of material properties for test specimens, and four thermal shock experiments with 0.53-m-OD (21-in.) by 0.15-m-wall (6-in.) cylindrical test specimens. In the first experiment, initiation was not expected and did not occur, although there was a small amount of subcritical crack growth. In the second experiment, initiation of a semicircular flaw took place as expected; the final length along the surface was about four times the initial length, but there was no radial growth. The third and fourth experiments were similar, and the long axial flaw initiated in good agreement with predictions

Thermal expansion, modulus of elasticity, shrinkage, creep and residual strength of concrete for PCRVs at uniaxial stress state and elevated temperatures

International Nuclear Information System (INIS)

Aschl, H.; Stoeckl, S.

1981-01-01

At the Institut fuer Massivbau of the Technical University of Munich testing machines were built, which allow to test sealed and unsealed cylinders with uniaxial stress state at elevated temperatures till 523 K (250 0 C). With this equipment tests were carried out at predried, unsealed and sealed specimens to study - thermal expansion coefficient - modulus of elasticity - shrinkage and - creep of concrete at elevated temperatures of 353 K (80 0 C) and 393 K (120 0 C) and at a normal temperature of 293 K (20 0 C). In addition the residual strength of all specimens was measured. In the worst case (unsealed, i.e. drying specimens) some showed a maximum decrease in strength up to 60%. (orig.) [de

On the limits of uniaxial magnetic anisotropy tuning by a ripple surface pattern

Energy Technology Data Exchange (ETDEWEB)

Arranz, Miguel A. [Facultad de Ciencias Químicas, Universidad de Castilla-La Mancha, Avda. Camilo J. Cela 10, 13071 Ciudad Real (Spain); Colino, Jose M., E-mail: josemiguel.colino@uclm.es [Instituto de Nanociencia, Nanotecnología y Materiales Moleculares, Universidad de Castilla-La Mancha, Campus de la Fábrica de Armas, 45071 Toledo (Spain); Palomares, Francisco J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, c/ Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain)

2014-05-14

Ion beam patterning of a nanoscale ripple surface has emerged as a versatile method of imprinting uniaxial magnetic anisotropy (UMA) on a desired in-plane direction in magnetic films. In the case of ripple patterned thick films, dipolar interactions around the top and/or bottom interfaces are generally assumed to drive this effect following Schlömann's calculations for demagnetizing fields of an ideally sinusoidal surface [E. Schlömann, J. Appl. Phys. 41, 1617 (1970)]. We have explored the validity of his predictions and the limits of ion beam sputtering to induce UMA in a ferromagnetic system where other relevant sources of magnetic anisotropy are neglected: ripple films not displaying any evidence of volume uniaxial anisotropy and where magnetocrystalline contributions average out in a fine grain polycrystal structure. To this purpose, the surface of 100 nm cobalt films grown on flat substrates has been irradiated at fixed ion energy, fixed ion fluency but different ion densities to make the ripple pattern at the top surface with wavelength Λ and selected, large amplitudes (ω) up to 20 nm so that stray dipolar fields are enhanced, while the residual film thickness t = 35–50 nm is sufficiently large to preserve the continuous morphology in most cases. The film-substrate interface has been studied with X-ray photoemission spectroscopy depth profiles and is found that there is a graded silicon-rich cobalt silicide, presumably formed during the film growth. This graded interface is of uncertain small thickness but the range of compositions clearly makes it a magnetically dead layer. On the other hand, the ripple surface rules both the magnetic coercivity and the uniaxial anisotropy as these are found to correlate with the pattern dimensions. Remarkably, the saturation fields in the hard axis of uniaxial continuous films are measured up to values as high as 0.80 kG and obey a linear dependence on the parameter ω{sup 2}/Λ/t in quantitative

Uniaxial Strain Induced Critical Current Degradation of Ag-Sheathed Bi-2212 Round Wire

NARCIS (Netherlands)

Dai, Chao; Qin, Jinggang; Liu, Bo; Liu, Peihang; Wu, Yu; Nijhuis, Arend; Zhou, Chao; Li, Chenshan; Hao, Qingbin; Liu, Sheng

2018-01-01

The critical current degradation of Bi-2212 Ag-sheathed round wire subjected to uniaxial strain was studied at 4.2 K in 14 T background field. The strains applied on the sample are both tension and compression. The additional tensile strain caused by the difference in thermal expansion between the

Warm temperature (170-280°C) uniaxial compresion of SiC reinforced MMCs

CSIR Research Space (South Africa)

Gxowa, Zizo

2017-10-01

Full Text Available and constant strain of 0.3. Engineering stress-strain curves showed that the best deformation was achieved when sintered MMC compacts were uniaxially compressed at 280°C and strain rate of 5s-1 using a soaking time of 20min.The best deformation was achieved...

Ultimate uniaxial compressive strength of stiffened panel with opening under lateral pressure

Directory of Open Access Journals (Sweden)

Chang-Li Yu

2015-03-01

Full Text Available This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

Correlated electron capture in the impact parameter and final projectile charge-state dependence of ECC cusp production in 0.53 MeV u-1 F8+ + Ne

International Nuclear Information System (INIS)

Skutlartz, A.; Hagmann, S.; Schmidt-Boecking, H.

1988-01-01

The impact parameter dependence of ECC cusp electron production in collisions of fast, highly charged ions with atoms is investigated by measuring the scattered projectiles in coincidence with cusp electrons emitted at 0 0 with respect to the beam axis. The absolute probabilities for ECC cusp production show a maximum at b ≅ 0.10 au, decrease strongly for smaller impact parameters and more gently toward larger impact parameters. In addition the final charge state of the scattered projectile is also determined simultaneously for each collision event. The probabilities, as a function of the projectile final charge state, are large for the case where at least one or more electrons are simultaneously captured into bound states of the projectile, but are surprisingly small for collisions in which a projectile did not capture an electron into a bound state. (author)

Uniaxial experimental study of the acoustic emission and deformation behavior of composite rock based on 3D digital image correlation (DIC)

Science.gov (United States)

Cheng, Jian-Long; Yang, Sheng-Qi; Chen, Kui; Ma, Dan; Li, Feng-Yuan; Wang, Li-Ming

2017-12-01

In this paper, uniaxial compression tests were carried out on a series of composite rock specimens with different dip angles, which were made from two types of rock-like material with different strength. The acoustic emission technique was used to monitor the acoustic signal characteristics of composite rock specimens during the entire loading process. At the same time, an optical non-contact 3D digital image correlation technique was used to study the evolution of axial strain field and the maximal strain field before and after the peak strength at different stress levels during the loading process. The effect of bedding plane inclination on the deformation and strength during uniaxial loading was analyzed. The methods of solving the elastic constants of hard and weak rock were described. The damage evolution process, deformation and failure mechanism, and failure mode during uniaxial loading were fully determined. The experimental results show that the θ = 0{°}-45{°} specimens had obvious plastic deformation during loading, and the brittleness of the θ = 60{°}-90{°} specimens gradually increased during the loading process. When the anisotropic angle θ increased from 0{°} to 90{°}, the peak strength, peak strain, and apparent elastic modulus all decreased initially and then increased. The failure mode of the composite rock specimen during uniaxial loading can be divided into three categories: tensile fracture across the discontinuities (θ = 0{°}-30{°}), sliding failure along the discontinuities (θ = 45{°}-75{°}), and tensile-split along the discontinuities (θ = 90{°}). The axial strain of the weak and hard rock layers in the composite rock specimen during the loading process was significantly different from that of the θ = 0{°}-45{°} specimens and was almost the same as that of the θ = 60{°}-90{°} specimens. As for the strain localization highlighted in the maximum principal strain field, the θ = 0{°}-30{°} specimens appeared in the rock

Post-test analysis of ROSA-III experiment Run 702

International Nuclear Information System (INIS)

Koizumi, Yasuo; Kikuchi, Osamu; Soda, Kunihisa

1980-01-01

The purpose of the ROSA-III experiment with a scaled BWR test facility is to examine primary coolant thermal-hydraulic behavior and performance of ECCS during a posturated loss-of-coolant accident of BWR. The results provide information for verification and improvement of reactor safety analysis codes. Run 702 assumed a 200% split break at the recirculation pump suction line under an average core power without ECCS activation. Post - test analysis of the Run 702 experiment was made with computer code RELAP4J. Agreement of the calculated system pressure and the experiment one was good. However, the calculated heater surface temperatures were higher than the measured ones. Also, the axial temperature distribution was different in tendency from the experimental one. From these results, the necessity was indicated of improving the analytical model of void distribution in the core and the nodalization in the pressure vassel, in order to make the analysis more realistic. And also, the need of characteristic test was indicated for ROSA-III test facility components, such as jet pump and piping form loss coefficient; likewise, flow rate measurements must be increased and refined. (author)

Domain shape instabilities and dendrite domain growth in uniaxial ferroelectrics

Science.gov (United States)

Shur, Vladimir Ya.; Akhmatkhanov, Andrey R.

2018-01-01

The effects of domain wall shape instabilities and the formation of nanodomains in front of moving walls obtained in various uniaxial ferroelectrics are discussed. Special attention is paid to the formation of self-assembled nanoscale and dendrite domain structures under highly non-equilibrium switching conditions. All obtained results are considered in the framework of the unified kinetic approach to domain structure evolution based on the analogy with first-order phase transformation. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

Disk-bend ductility tests for irradiated materials

International Nuclear Information System (INIS)

Klueh, R.L.; Braski, D.N.

1984-01-01

We modified the HEDL disk-bend test machine and are using it to qualitatively screen alloys that are susceptible to embrittlement caused by irradiation. Tests designed to understand the disk-bend test in relation to a uniaxial test are discussed. Selected results of tests of neutron-irradiated material are also presented

Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

International Nuclear Information System (INIS)

Larsson, C.; Clausen, B.; Holden, T.M.; Bourke, M.A.M.

2004-01-01

Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement

Measurements and predictions of strain pole figures for uniaxially compressed stainless steel

Energy Technology Data Exchange (ETDEWEB)

Larsson, C. [Division of Engineering Materials, Department of Mechanical Engineering, Linkoeping University, 58183 Linkoeping (Sweden)]. E-mail: clarsson@cfl.rr.com; Clausen, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Holden, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2004-09-15

Strain pole figures representative of residual intergranular strains were determined from an -2.98% uniaxially compressed austenitic stainless steel sample. The measurements were made using neutron diffraction on the recently commissioned Spectrometer for Materials Research at Temperature and Stress (SMARTS) at Los Alamos National Laboratory, USA. The measurements were compared with predictions from an elasto-plastic self-consistent model and found to be in good agreement.

A creep life assessment method for boiler pipes using small punch creep test

International Nuclear Information System (INIS)

Izaki, Toru; Kobayashi, Toshimi; Kusumoto, Junichi; Kanaya, Akihiro

2009-01-01

The small punch creep (SPC) test is considered as a highly useful method for creep life assessment for high temperature plant components. SPC uses miniature-sized specimens and does not cause any serious sampling damages, and its assessment accuracy is at a high level. However, in applying the SPC test to the residual creep life assessment of the boiler in service, there are some issues to be studied. In order to apply SPC test to the residual creep life assessment of the 2.25Cr-1Mo steel boiler pipe, the relationship between uniaxial creep stress and the SPC test load has been studied. The virgin material, pre-crept, weldment and service aged samples of 2.25Cr-1Mo steel were tested. It was confirmed that the relationship between uniaxial creep stress and the SPC test load at the same rupture time can be described as a single straight line independent of test conditions and materials. Therefore a life assessment is possible by using SPC test in place of uniaxial creep tests. The creep life assessment using SPC was applied to actual thermal power plant components which are in service.

Routine testing on protective and safety systems and components

International Nuclear Information System (INIS)

Rysy, W.

1977-01-01

1) In-process inspection, tests during commissioning. 2) Tests during reactor operation. 2.1) Reactor protection system, for example: continuous auto-testing by a dynamic system, check of the output signals; 2.2) safety features: selected examples: functional tests on the ECCS, trial operation of the emergency diesels. 3) Tests during refuelling phase. 3.1) Containment: Leakage rate tests, leak testing; 3.2) coolant system: selected examples: inservice inspections of the pressure vessel, eddy current testing of the steam generator, functional tests of safety valves. (orig./HP) [de

QNS study of uniaxial molecular reorientation in solid t-cyanobutane

International Nuclear Information System (INIS)

Urban, S.; Nawrocik, W.

1977-01-01

The results of a quasielastic neutron scattering (QNS) investigation on a t-cyanobutane, (CH 3 ) 3 CCN, sample jn three solid phases are presented. It was found there is a fast uniaxial reorientation of the t-cyanobutane molecules in phase 1, characterized by correlation times of the order of several picoseconds and an activation barrier ΔE= (0.5 +- 0.2) kcal/mole. The lack of quasielastic broadening in the neutron spectra of lower-temperature phases implies that molecular rotation then is much slower or completely hindered. (author)

FPGA implementation of PCI to CAMAC interface for Embedded CAMAC Controller (ECC)

International Nuclear Information System (INIS)

Jha, K.; Behere, Anita; Ghodgaonkar, M.D.

2005-01-01

CAMAC controllers are used for control systems and nuclear physics experiments. Control applications need more number of physically distributed crates with regular scanning of all the parameters, the control being with a centralized computer. On the other hand, nuclear physics experiments need a high throughput with a large number of parameters in one or more crates. The nature of events is random hence buffering of data in LIST mode acquisition is needed. For a large number of parameters, this translates to high transfer rate. Hence it is essential that the CAMAC readout time is minimized and also the data transfer speed is improved to achieve maximum effective throughput. The ECC is designed to achieve these objectives using an embedded controller with PC architecture having PCI bus as interface for add on logic. The PCI Add-on to CAMAC interface protocol has been implemented in an AL TERA FPGA and all the functionality coded in VHDL. This paper discusses the design aspects of the FPGA implementation of the PCI to CAMAC interface. (author)

Electric-regulated enhanced in-plane uniaxial anisotropy in FeGa/PMN-PT composite using oblique pulsed laser deposition

Science.gov (United States)

Zhang, Yi; Huang, Chaojuan; Turghun, Mutellip; Duan, Zhihua; Wang, Feifei; Shi, Wangzhou

2018-04-01

The FeGa film with in-plane uniaxial magnetic anisotropy was fabricated onto different oriented single-crystal lead magnesium niobate-lead titanate using oblique pulsed laser deposition. An enhanced in-plane uniaxial magnetic anisotropy field of FeGa film can be adjusted from 18 Oe to 275 Oe by tuning the oblique angle and polarizing voltage. The competitive relationship of shape anisotropy and strain anisotropy has been discussed, which was induced by oblique angle and polarizing voltage, respectively. The (100)-oriented and (110)-oriented PMN-PT show completely different characters on voltage-dependent magnetic properties, which could be attributed to various anisotropy directions depended on different strain directions.

Structural Benchmark Testing for Stirling Convertor Heater Heads

Science.gov (United States)

Krause, David L.; Kalluri, Sreeramesh; Bowman, Randy R.

2007-01-01

The National Aeronautics and Space Administration (NASA) has identified high efficiency Stirling technology for potential use on long duration Space Science missions such as Mars rovers, deep space missions, and lunar applications. For the long life times required, a structurally significant design limit for the Stirling convertor heater head is creep deformation induced even under relatively low stress levels at high material temperatures. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and much creep data is available for the proposed Inconel-718 (IN-718) and MarM-247 nickel-based superalloy materials of construction. However, very little experimental creep information is available that directly applies to the atypical thin walls, the specific microstructures, and the low stress levels. In addition, the geometry and loading conditions apply multiaxial stress states on the heater head components, far from the conditions of uniaxial testing. For these reasons, experimental benchmark testing is underway to aid in accurately assessing the durability of Stirling heater heads. The investigation supplements uniaxial creep testing with pneumatic testing of heater head test articles at elevated temperatures and with stress levels ranging from one to seven times design stresses. This paper presents experimental methods, results, post-test microstructural analyses, and conclusions for both accelerated and non-accelerated tests. The Stirling projects use the results to calibrate deterministic and probabilistic analytical creep models of the heater heads to predict their life times.

Uniaxial stress influence on electrical conductivity of thin epitaxial lanthanum-strontium manganite films

Energy Technology Data Exchange (ETDEWEB)

Stankevič, V., E-mail: wstan@pfi.lt [Center for Physical Sciences and Technology, Semiconductor Physics Institute, A.Gostauto 11, Vilnius (Lithuania); Vilnius Gediminas Technical University, Sauletekio 11, Vilnius (Lithuania); Šimkevičius, Č.; Balevičius, S.; Žurauskienė, N. [Center for Physical Sciences and Technology, Semiconductor Physics Institute, A.Gostauto 11, Vilnius (Lithuania); Vilnius Gediminas Technical University, Sauletekio 11, Vilnius (Lithuania); Cimmperman, P. [Center for Physical Sciences and Technology, Semiconductor Physics Institute, A.Gostauto 11, Vilnius (Lithuania); Abrutis, A. [Vilnius University, Dept. of General and Inorganic Chemistry, Naugarduko 24, Vilnius (Lithuania); Plaušinaitienė, V. [Center for Physical Sciences and Technology, Semiconductor Physics Institute, A.Gostauto 11, Vilnius (Lithuania); Vilnius University, Dept. of General and Inorganic Chemistry, Naugarduko 24, Vilnius (Lithuania)

2013-07-01

This is a study of the influence of external uniaxial mechanical strains on the transport properties of thin epitaxial La{sub 0.83}Sr{sub 0.17}MnO{sub 3} (LSMO) films. Our measurements were carried out using standard isosceles triangle-shaped cantilever. Films which were tensed in-plane or compressed or were subjected to both tension and compression strains were grown onto SrTiO{sub 3} (STO), LaAlO{sub 3} (LAO) and (001) NdGaO{sub 3} (NGO) substrates, respectively. It was found that for thin films (less than 100 nm), the uniaxial compression of such films which were initially tensed in-plane (grown onto STO substrates) produces a decrease of their resistance, whereas the compression of initially compressed films (on LAO substrates) produces an increase of the films' resistance. The same results were obtained for LSMO films grown onto (001) NGO substrates when they were compressed along the [010] and [100] directions, respectively. For thicker films (more than 100 nm), the resistance behavior after uniaxial compression was found to be identical to that produced by hydrostatic compression, namely, the resistance decreases irrespective of the substrate. These experiments also reveal an increase of resistance and a shift of metal–insulator transition temperature T{sub m} to lower temperatures corresponding to a decrease of the film thickness. The occurrence of this effect is also independent of the kind of substrate used. Thus it was concluded that the influence of film thickness on its resistance as well as on the behavior of such films while under external uniaxial compression cannot be explained fully by only the presence of residual stress in these films. A possible reason is that the inhomogeneous distribution of the mechanical stresses in the films can lead to the appearance of two conductivity phases, each having a different mechanism. The results which were obtained when these films were subjected to hydrostatic compression were also explained by this

Deformation response of gellan gum based bone scaffold subjected to uniaxial quasi-static loading

Czech Academy of Sciences Publication Activity Database

Kytýř, Daniel; Krčmářová, Nela; Šleichrt, Jan; Fíla, Tomáš; Koudelka_ml., Petr; Gantar, A.; Novak, S.

2017-01-01

Roč. 57, č. 1 (2017), s. 14-21 ISSN 1210-2709 EU Projects: European Commission(XE) ATCZ38 Institutional support: RVO:68378297 Keywords : gellan gum scaffold * reinforcement * uni-axial loading Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering https://ojs.cvut.cz/ojs/index.php/ap/article/view/3885

Viscosity overshoot in the start-up of uniaxial elongation of low density polyethylene melts

DEFF Research Database (Denmark)

Rasmussen, Henrik K.; Nielsen, Jens Kromann; Bach, Anders

2005-01-01

The transient uniaxial elongational viscosity of BASF Lupolen 1840D and 3020D melts has been measured on a filament stretch rheometer up to Hencky strains of 6-7. The elongational viscosity of both melts was measured at 130 degrees C within a broad range of elongational rates. At high elongation ...

Stable evaluation of Green's functions in cylindrically stratified regions with uniaxial anisotropic layers

Energy Technology Data Exchange (ETDEWEB)

Moon, H., E-mail: haksu.moon@gmail.com [ElectroScience Laboratory, The Ohio State University, Columbus, OH 43212 (United States); Donderici, B., E-mail: burkay.donderici@halliburton.com [Sensor Physics & Technology, Halliburton Energy Services, Houston, TX 77032 (United States); Teixeira, F.L., E-mail: teixeira@ece.osu.edu [ElectroScience Laboratory, The Ohio State University, Columbus, OH 43212 (United States)

2016-11-15

We present a robust algorithm for the computation of electromagnetic fields radiated by point sources (Hertzian dipoles) in cylindrically stratified media where each layer may exhibit material properties (permittivity, permeability, and conductivity) with uniaxial anisotropy. Analytical expressions are obtained based on the spectral representation of the tensor Green's function based on cylindrical Bessel and Hankel eigenfunctions, and extended for layered uniaxial media. Due to the poor scaling of these eigenfunctions for extreme arguments and/or orders, direct numerical evaluation of such expressions can produce numerical instability, i.e., underflow, overflow, and/or round-off errors under finite precision arithmetic. To circumvent these problems, we develop a numerically stable formulation through suitable rescaling of various expressions involved in the computational chain, to yield a robust algorithm for all parameter ranges. Numerical results are presented to illustrate the robustness of the formulation including cases of practical interest.

Investigation of the Geometry of Metal Tube Walls after Necking in Uniaxial Tension

Directory of Open Access Journals (Sweden)

Chong Li

2017-03-01

Full Text Available Abstract: In order to characterize the deformation and true stress–strain relation of metal tubes, the geometry of tube walls after necking in uniaxial tension need to be determined. The paper investigated the necking process of metal tube. A large number of tensile tests and finite element analysis of 1Cr18Ni9Ti tubes with different sizes were conducted. It was found that the geometry of outer tube wall in the necking region can be described using a logistic regression model. The final geometry of the tube is determined by original tube diameter and wall thickness. The offset of tube walls are affected by two competing factors: volume constancy and necking. The offset distances of outer and inner walls are mainly affected by original wall thickness. The length of the necking zone is more influenced by original tube diameter. Tube elongation at fracture increases slightly as tube diameter gets larger, while the wall thickness has almost no impact on the elongation.

Uniaxial creep as a control on mercury intrusion capillary pressure in consolidating rock salt

Energy Technology Data Exchange (ETDEWEB)

Dewers, Thomas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Heath, Jason E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Leigh, Christi D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-09-01

The nature of geologic disposal of nuclear waste in salt formations requires validated and verified two - phase flow models of transport of brine and gas through intact, damaged, and consolidating crushed salt. Such models exist in oth er realms of subsurface engineering for other lithologic classes (oil and gas, carbon sequestration etc. for clastics and carbonates) but have never been experimentally validated and parameterized for salt repository scenarios or performance assessment. Mo dels for waste release scenarios in salt back - fill require phenomenological expressions for capillary pressure and relative permeability that are expected to change with degree of consolidation, and require experimental measurement to parameterize and vali date. This report describes a preliminary assessment of the influence of consolidation (i.e. volume strain or porosity) on capillary entry pressure in two phase systems using mercury injection capillary pressure (MICP). This is to both determine the potent ial usefulness of the mercury intrusion porosimetry method, but also to enable a better experimental design for these tests. Salt consolidation experiments are performed using novel titanium oedometers, or uniaxial compression cells often used in soil mech anics, using sieved run - of - mine salt from the Waste Isolation Pilot Plant (WIPP) as starting material. Twelve tests are performed with various starting amounts of brine pore saturation, with axial stresses up to 6.2 MPa (%7E900 psi) and temperatures to 90 o C. This corresponds to UFD Work Package 15SN08180211 milestone "FY:15 Transport Properties of Run - of - Mine Salt Backfill - Unconsolidated to Consolidated". Samples exposed to uniaxial compression undergo time - dependent consolidation, or creep, to various deg rees. Creep volume strain - time relations obey simple log - time behavior through the range of porosities (%7E50 to 2% as measured); creep strain rate increases with temperature and applied stress as

Effect of uniaxial strain on adatom diffusion across {l_brace}1 1 1{r_brace}-faceted step

Energy Technology Data Exchange (ETDEWEB)

Yang Jianyu, E-mail: wuliyangjianyu@yahoo.com.cn [Department of Maths and Physics, Hunan Institute of Engineering, Donghu Street, Xiangtan 411104 (China); Hu Wangyu, E-mail: Wangyuhu2001@yahoo.com.cn [Department of Applied Physics, Hunan University, Changsha 410082 (China); Tang Jianfeng [Department of Applied Physics, Hunan Agricultural University, Changsha 410128 (China)

2011-02-01

Diffusion of Pt adatom across the strained {l_brace}1 1 1{r_brace}-faceted step is studied by embedded atom method along with nudged elastic band method. For adatom on the flat (1 1 1) surface, the anisotropic diffusion behavior is found as the uniaxial strain is imposed. For the strained {l_brace}1 1 1{r_brace}-faceted step, our results show that the maximum energy barrier for adatom crossing step edge remains approximately constant as the strain varied from -1.0% to 1.0%, and there is a rise as the larger uniaxial strain is applied. The calculated energy barrier for adatom diffusion along the step edge increases with increasing tensile strain, and the slope of the straight line is small.

Large scale reflood test with cylindrical core test facility (CCTF). Core I. FY 1979 tests

International Nuclear Information System (INIS)

Murao, Yoshio; Akimoto, Hajime; Okubo, Tsutomu; Sudoh, Takashi; Hirano, Kenmei

1982-03-01

This report presents the results of analysis of the data obtained in the CCTF Core I test series (19 tests) in FY. 1979 as an interim report. The Analysis of the test results showed that: (1) The present safety evaluation model on the reflood phenomena during LOCA conservatively represents the phenomena observed in the tests except for the downcomer thermohydrodynamic behavior. (2) The downcomer liquid level rose slowly and it took long time for the water to reach a terminal level or the spill-over level. It was presume that such a results was due to an overly conservative selection of the ECC flow rate. This presumption will be checked against a future test result for an increased flow rate. The loop-seal-water filling test was unsuccessful due to a premature power shutdown by the core protection circuit. The test will be conducted again. The tests to be performed in the future are summerized. Tests for investigation of the refill phenomena were also proposed. (author)

Mechanical properties of uniaxial natural fabric Grewia tilifolia reinforced epoxy based composites: Effects of chemical treatment

CSIR Research Space (South Africa)

Jayaramudu, J

2014-07-01

Full Text Available The effects of chemical treatment on the mechanical, morphological, and chemical resistance properties of uniaxial natural fabrics, Grewia tilifolia/epoxy composites, were studied. In order to enhance the interfacial bonding between the epoxy matrix...

Gigantic uniaxial pressure effect in single crystals of iron-based superconductors

International Nuclear Information System (INIS)

Nakashima, Y.; Yui, H.; Sasagawa, T.

2010-01-01

In order to elucidate the anisotropic pressure effect on superconductivity in an iron-based superconductor, magnetization measurements have been performed in Ba(Fe 0.92 Co 0.08 ) 2 As 2 single crystals under uniaxial pressures applied along the c-axis. Gigantic T c suppression, dT c /dP //c = -15 K/GPa, was observed when the anisotropic deformation with the a-expansion and c-compression was induced by the c-pressure, which should be compared with dT c /dP c .

Dynamic hysteresis of a uniaxial superparamagnet: Semi-adiabatic approximation

International Nuclear Information System (INIS)

Poperechny, I.S.; Raikher, Yu.L.; Stepanov, V.I.

2014-01-01

The semi-adiabatic theory of magnetic response of a uniaxial single-domain ferromagnetic particle is presented. The approach is developed in the context of the kinetic theory and allows for any orientation of the external field. Within this approximation, the dynamic magnetic hysteresis loops in an ac field are calculated. It is demonstrated that they very closely resemble those obtained by the full kinetic theory. The behavior of the effective coercive force is analyzed in detail, and for it a simple formula is proposed. This relation accounts not only for the temperature behavior of the coercive force, as the previous ones do, but also yields the dependence on the frequency and amplitude of the applied field

Uniaxially aligned ceramic nanofibers obtained by chemical mechanical processing

Energy Technology Data Exchange (ETDEWEB)

Tararam, R. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil); Foschini, C.R. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Bauru, Dept. de Eng. Mecanica, Av. Eng. Luiz Edmundo C. Coube 14-01, CEP 17033-360 Bauru, SP (Brazil); Destro, F.B. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Longo, E.; Varela, J.A. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil)

2014-08-01

For this study, we investigated a simple method to generate well aligned nanofibers over large areas using an organic polymer stretched over the substrate surface With this method, ZnO and CuO 3D parallel nanowire arrays were successfully prepared by calcinations of the polymer fibers. X-ray diffraction (XRD) analysis revealed that the copper oxide has a monoclinic structure while the zinc oxide has a hexagonal structure. Scanning electron microscopy (SEM) analysis showed ceramic nanofibers with an average diameter of 120 nm which were composed of small nanoparticles which are 10 nm in diameter. The ability to obtain uniaxially aligned nanofibers reveals a range of interesting properties with potential applications for sensors, catalysts and energy technologies.

Anisotropic Material Behavior of Uni-axially Compacted Graphite Matrix for HTGR Fuel Compact Fabrication

Energy Technology Data Exchange (ETDEWEB)

Lee, Young-Woo; Yeo, Seunghwan; Yoon, Ji-Hae; Cho, Moon Sung [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In developing the fuel compact fabrication technology, and fuel graphite material to meet the required material properties, it is essential to investigate the relationship among the process parameters of the matrix graphite powder preparation, the fabrication parameters of fuel element green compact and the heat treatments conditions and the material properties of fuel element. It was observed, during this development, that the pressing technique employed for the compaction fabrication prior to the two successive heat treatments (carbonization and final high temperature heat treatment) was of extreme importance in determining the material properties of the final compact product. In this work, the material behavior of the uni-axially pressed graphite matrix during the carbonization and final heat treatment are evaluated and summarized along the different directions, viz., perpendicular and parallel directions to pressing direction. In this work, the dimensional variations and variations in thermal expansion, thermal conductivity and Vickers hardness of the graphite matrix compact samples in the axial and radial directions prepared by uni-axial pressing are evaluated, and compared with those of samples prepared by cold isostatic pressing with the available data. From this work, the followings are observed. 1) Dimensional changes of matrix graphite green compacts during carbonization show that the difference in radial and axial variations shows a large anisotropic behavior in shrinkage. The radial variation is very small while the axial variation is large. During carbonization, the stresses caused by the force would be released in to the axial direction together with the phenolic resin vapor. 2) Dimensional variation of compact samples in perpendicular and parallel directions during carbonization shows a large difference in behavior when compact sample is prepared by uni-axial pressing. However, when compact sample is prepared by cold isostatic pressing, there is

Anisotropic Material Behavior of Uni-axially Compacted Graphite Matrix for HTGR Fuel Compact Fabrication

International Nuclear Information System (INIS)

Lee, Young-Woo; Yeo, Seunghwan; Yoon, Ji-Hae; Cho, Moon Sung

2016-01-01

In developing the fuel compact fabrication technology, and fuel graphite material to meet the required material properties, it is essential to investigate the relationship among the process parameters of the matrix graphite powder preparation, the fabrication parameters of fuel element green compact and the heat treatments conditions and the material properties of fuel element. It was observed, during this development, that the pressing technique employed for the compaction fabrication prior to the two successive heat treatments (carbonization and final high temperature heat treatment) was of extreme importance in determining the material properties of the final compact product. In this work, the material behavior of the uni-axially pressed graphite matrix during the carbonization and final heat treatment are evaluated and summarized along the different directions, viz., perpendicular and parallel directions to pressing direction. In this work, the dimensional variations and variations in thermal expansion, thermal conductivity and Vickers hardness of the graphite matrix compact samples in the axial and radial directions prepared by uni-axial pressing are evaluated, and compared with those of samples prepared by cold isostatic pressing with the available data. From this work, the followings are observed. 1) Dimensional changes of matrix graphite green compacts during carbonization show that the difference in radial and axial variations shows a large anisotropic behavior in shrinkage. The radial variation is very small while the axial variation is large. During carbonization, the stresses caused by the force would be released in to the axial direction together with the phenolic resin vapor. 2) Dimensional variation of compact samples in perpendicular and parallel directions during carbonization shows a large difference in behavior when compact sample is prepared by uni-axial pressing. However, when compact sample is prepared by cold isostatic pressing, there is

Design aspects of the Alpha Repository: III. Uniaxial quasi-static and creep properties of the site rock. Technical memorandum report RSI-0029

International Nuclear Information System (INIS)

Hansen, F.D.; Gnirk, P.F.

1975-01-01

Candidate mining horizons for the Alpha Repository have been tentatively selected at depths of 1,900, 2,100, and 2,700 ft in the massive salt formations underlying Eddy and Lea counties in New Mexico. The rock salt in the mining horizon at 1,900 ft exhibits average tensile and uniaxial compressive strengths of 200 and 2,445 psi, while the rock salt in the 2,700 ft horizon is 20 to 35 percent stronger. The elastic constants were essentially identical for the two horizons, with an average Young's modulus of 1.94 x 10 6 psi and a Poisson's ratio of 0.33 to 0.34. The anhydrite exhibits tensile and uniaxial compressive strengths of 830 and 13,085 psi, and its Poisson's ratio is 0.35, essentially the same as for rock salt, but its Young's modulus is 10.2 x 10 6 psi, five times greater than that of rock salt. In general, rock salt exhibits a type of bilinear stress-strain curve, with a discontinuity in slope occurring at about 750 psi. Rock salt appears to fail by crushing, rather than in an abrupt ''brittle fracture'' fashion. Anhydrite exhibits a linear stress-strain relationship, with abrupt and distinct failure at the level required for rupture. Uniaxial creep tests were performed on specimens from the 1,900 ft and 2,700 ft horizons using stress levels of 750 and 1,500 psi from 30 to over 200 hours. Results indicate that, for a constant stress level, strain is a function of time to the power of 0.20 to 0.24 and strain appears to be a nonlinear function of the deviatoric stress. Neither steady-state nor tertiary creep was observed

The role of ultrasonic velocity and Schmidt hammer hardness - The simple and economical non-destructive test for the evaluation of mechanical properties of weathered granite

Science.gov (United States)

Jobli, Ahmad Fadzil; Hampden, Ahmad Zaidi; Tawie, Rudy

2017-08-01

One of the most significant techniques for evaluation of rock strength is by using the simple and economical non-destructive test (NDT). Previous literatures confirm that there were good correlations between NDTs to the strength properties of granite rocks. The present work deals with the use of Ultrasonic Pulse Velocity and Schmidt Hammer Hardness test to predict the mechanical properties of weathered granite. Cylindrical specimens with the length to diameter ratio of two were prepared for this study and were characterized based on different weathering states. Each of the rock specimens was tested under non-destructive test and then followed by uniaxial compression test to assess the mechanical properties. It was found that good correlations established between the NDTs and the uniaxial compressive strength. The correlation between uniaxial compressive strength and rebound hardness number was demonstrated by exponential form; UCS = 6.31e0.057N, while linear correlations was obtained between the uniaxial compressive strength and the ultrasonic pulse velocity; UCS = 0.023Vp - 21.43. It was also noticed that the increase of uniaxial compression strength was parallel to the increase of elastic modulus and can be presented by a linear equation; UCS = 1.039Et50 + 4.252. Based on the reported results, it is clear that the mechanical properties or weathered granite can be estimated by means of non-destructive test.

Effect of uniaxially pressing ordinary Portland cement pastes containing metal hydroxides on porosity, density, and leaching

International Nuclear Information System (INIS)

Cheeseman, C.R.; Asavapisit, S.; Knight, J.

1998-01-01

Synthetic metal hydroxide wastes containing Zn and Pb have been mixed with partially hydrated cement and uniaxially pressed. The effect on porosity, pore size distribution, and bulk and skeletal densities has been characterized using mercury intrusion porosimetry. Ca(OH) 2 formation has been determined using differential thermal analysis and metal leaching has been assessed in a series of static leach tests completed on monolithic samples. Pressed solidified materials have increased density, reduced porosity, and reduced Ca(OH) 2 . They exhibit increased resistance to acid attack in terms of sample weight loss during leaching due to reduced release of alkalis. Leaching of Zn and Pb is primarily determined by pH. A peak observed in Zn leaching from pressed samples is due to the effect of changing leachate pH on the dominant Zn species present

Test-Retest Reliability of Isokinetic Knee Strength Measurements in Children Aged 8 to 10 Years.

Science.gov (United States)

Fagher, Kristina; Fritzson, Annelie; Drake, Anna Maria

Isokinetic dynamometry is a useful tool to objectively assess muscle strength of children and adults in athletic and rehabilitative settings. This study examined test-retest reliability of isokinetic knee strength measurements in children aged 8 to 10 years and defined limits for the minimum difference (MD) in strength that indicates a clinically important change. Isokinetic knee strength measurements (using the Biodex System 4) in children will provide reliable results. Descriptive laboratory study. In 22 healthy children, 5 maximal concentric (CON) knee extensor (KE) and knee flexor (KF) contractions at 2 angular velocities (60 deg/s and 180 deg/s) and 5 maximal eccentric (ECC) KE/KF contractions at 60 deg/s were assessed 7 days apart. The intraclass correlation coefficient (ICC 2.1 ) was used to examine relative reliability, and the MD was calculated on the basis of standard error of measurement. ICCs for CON KE/KF peak torque measurements were fair to excellent (range, 0.49-0.81). The MD% values for CON KE and KF ranged from 31% to 37% at 60 deg/s and from 34% to 39% at 180 deg/s. ICCs in the ECC mode were good (range, 0.60-0.70), but associated MD% values were high (>50%). There was no systematic error for CON KE/KF and ECC KE strength measurements at 60 deg/s, but systematic error was found for all other measurements. The dynamometer provides a reliable analysis of isokinetic CON knee strength measurements at 60 deg/s in children aged 8 to 10 years. Measurements at 180 deg/s and in the ECC mode were not reliable, indicating a need for more familiarization prior to testing. The MD values may help clinicians to determine whether a change in knee strength is due to error or intervention.

Large break LOCA analysis for retrofitted ECCS at MAPS using modified computer code ATMIKA

International Nuclear Information System (INIS)

Singhal, Mukesh; Khan, T.A.; Yadav, S.K.; Pramod, P.; Rammohan, H.P.; Bajaj, S.S.

2002-01-01

Full text: Computer code ATMIKA which has been used for thermal hydraulic analysis is based on unequal velocity equal temperature (UVET) model. Thermal hydraulic transient was predicted using three conservation equations and drift flux model. The modified drift flux model is now able to predict counter current flow and the relative velocity in vertical channel more accurately. Apart from this, stratification model is also introduced to predict the fuel behaviour under stratified condition. Many more improvements were carried out with respect to solution of conservation equation, heat transfer package and frictional pressure drop model. All these modifications have been well validated with published data on RD-12/RD-14 experiments. This paper describes the code modifications and also deals with the application of the code for the large break LOCA analysis for retrofitted emergency core cooling system (ECCS) being implemented at Madras Atomic Power Station (MAPS). This paper also brings out the effect of accumulator on stratification and fuel behaviour

Ultrashort optical waveguide excitations in uniaxial silica fibers: elastic collision scenarios.

Science.gov (United States)

Kuetche, Victor K; Youssoufa, Saliou; Kofane, Timoleon C

2014-12-01

In this work, we investigate the dynamics of an uniaxial silica fiber under the viewpoint of propagation of ultimately ultrashort optical waveguide channels. As a result, we unveil the existence of three typical kinds of ultrabroadband excitations whose profiles strongly depend upon their angular momenta. Looking forward to surveying their scattering features, we unearth some underlying head-on scenarios of elastic collisions. Accordingly, we address some useful and straightforward applications in nonlinear optics through secured data transmission systems, as well as laser physics and soliton theory with optical soliton dynamics.

Conduction band structure and electron mobility in uniaxially strained Si via externally applied strain in nanomembranes

Energy Technology Data Exchange (ETDEWEB)

Chen Feng [Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Euaruksakul, Chanan; Himpsel, F J; Lagally, Max G [University of Wisconsin-Madison, Madison, WI 53706 (United States); Liu Zheng; Liu Feng, E-mail: lagally@engr.wisc.edu [University of Utah, Salt Lake City, UT 84112 (United States)

2011-08-17

Strain changes the band structure of semiconductors. We use x-ray absorption spectroscopy to study the change in the density of conduction band (CB) states when silicon is uniaxially strained along the [1 0 0] and [1 1 0] directions. High stress can be applied to silicon nanomembranes, because their thinness allows high levels of strain without fracture. Strain-induced changes in both the sixfold degenerate {Delta} valleys and the eightfold degenerate L valleys are determined quantitatively. The uniaxial deformation potentials of both {Delta} and L valleys are directly extracted using a strain tensor appropriate to the boundary conditions, i.e., confinement in the plane in the direction orthogonal to the straining direction, which correspond to those of strained CMOS in commercial applications. The experimentally determined deformation potentials match the theoretical predictions well. We predict electron mobility enhancement created by strain-induced CB modifications.

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

Directory of Open Access Journals (Sweden)

Baoyun Zhao

2018-01-01

Full Text Available In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

Facile fabrication of uniaxial nanopatterns on shape memory polymer substrates using a complete bottom-up approach

Science.gov (United States)

Chen, Zhongbi; Krishnaswamy, Sridhar

2014-03-01

In earlier work, we have demonstrated an assisted self-assembly fabrication method for unidirectional submicron patterns using pre-programmed shape memory polymers (SMP) as the substrate in an organic/inorganic bilayer structure. In this paper, we propose a complete bottom-up method for fabrication of uniaxial wrinkles whose wavelength is below 300 nm. The method starts with using the aforementioned self-assembled bi-layer wrinkled surface as the template to make a replica of surface wrinkles on a PDMS layer which is spin-coated on a pre-programmed SMP substrate. When the shape recovery of the substrate is triggered by heating it to its transition temperature, the substrate has been programmed in such a way that it shrinks uniaxially to return to its permanent shape. Consequently, the wrinkle wavelength on PDMS reduces accordingly. A subsequent contact molding process is carried out on the PDMS layer spin-coated on another pre-programmed SMP substrate, but using the wrinkled PDMS surface obtained in the previous step as the master. By activating the shape recovery of the substrate, the wrinkle wavelength is further reduced a second time in a similar fashion. Our experiments showed that the starting wavelength of 640 nm decreased to 290 nm after two cycles of recursive molding. We discuss the advantages and limitations of our recursive molding approach compared to the prevalent top-down fabrication methods represented by lithography. The present study is expected to o er a simple and cost-e ective fabrication method of nano-scale uniaxial wrinkle patterns with the potential for large-scale mass-production.

Alternative methods for ray tracing in uniaxial media. Application to negative refraction

Science.gov (United States)

Bellver-Cebreros, Consuelo; Rodriguez-Danta, Marcelo

2007-03-01

In previous papers [C. Bellver-Cebreros, M. Rodriguez-Danta, Eikonal equation, alternative expression of Fresnel's equation and Mohr's construction in optical anisotropic media, Opt. Commun. 189 (2001) 193; C. Bellver-Cebreros, M. Rodriguez-Danta, Internal conical refraction in biaxial media and graphical plane constructions deduced from Mohr's method, Opt. Commun. 212 (2002) 199; C. Bellver-Cebreros, M. Rodriguez-Danta, Refraccion conica externa en medios biaxicos a partir de la construccion de Mohr, Opt. Pura AppliE 36 (2003) 33], the authors have developed a method based on the local properties of dielectric permittivity tensor and on Mohr's plane graphical construction in order to study the behaviour of locally plane light waves in anisotropic media. In this paper, this alternative methodology is compared with the traditional one, by emphasizing the simplicity of the former when studying ray propagation through uniaxial media (comparison is possible since, in this case, traditional construction becomes also plane). An original and simple graphical method is proposed in order to determine the direction of propagation given by the wave vector from the knowledge of the extraordinary ray direction (given by Poynting vector). Some properties of light rays in these media not described in the literature are obtained. Finally, two applications are considered: a description of optical birefringence under normal incidence and the study of negative refraction in uniaxial media.

Validity of hip-mounted uniaxial accelerometry with heart-rate monitoring vs. triaxial accelerometry in the assessment of free-living energy expenditure in young children: the IDEFICS Validation Study.

Science.gov (United States)

Ojiambo, Robert; Konstabel, Kenn; Veidebaum, Toomas; Reilly, John; Verbestel, Vera; Huybrechts, Inge; Sioen, Isabelle; Casajús, José A; Moreno, Luis A; Vicente-Rodriguez, German; Bammann, Karin; Tubic, Bojan M; Marild, Staffan; Westerterp, Klaas; Pitsiladis, Yannis P

2012-11-01

One of the aims of Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) validation study is to validate field measures of physical activity (PA) and energy expenditure (EE) in young children. This study compared the validity of uniaxial accelerometry with heart-rate (HR) monitoring vs. triaxial accelerometry against doubly labeled water (DLW) criterion method for assessment of free-living EE in young children. Forty-nine European children (25 female, 24 male) aged 4-10 yr (mean age: 6.9 ± 1.5 yr) were assessed by uniaxial ActiTrainer with HR, uniaxial 3DNX, and triaxial 3DNX accelerometry. Total energy expenditure (TEE) was estimated using DLW over a 1-wk period. The longitudinal axis of both devices and triaxial 3DNX counts per minute (CPM) were significantly (P hip-mounted uniaxial and triaxial accelerometers for assessing PA and EE is similar.

The application of miniature disc testing for the assessment of creep damage in CrMoV rotor steel

Energy Technology Data Exchange (ETDEWEB)

Parker, J D; Stratford, G C [University of Wales, Swansea (United Kingdom); Shaw, N; Spink, G [National Power plc (United Kingdom); Metcalfe, H [Siemens Power Generation (United Kingdom)

1999-12-31

A range of critical experiments has been performed studying the creep and fracture behaviour of a typical CrMoV rotor steel. Initially, uniaxial tests were carried out to provide material with a predetermined level of creep damage. Then, miniature disc tests were undertaken under accelerated conditions in a similar manner to procedures used for post-exposure uniaxial testing of service components. Data analysis demonstrates that the miniature tests accurately reflect the damage present so that this approach can be used to support run/repair/replace decisions. (orig.) 8 refs.

The application of miniature disc testing for the assessment of creep damage in CrMoV rotor steel

Energy Technology Data Exchange (ETDEWEB)

Parker, J.D.; Stratford, G.C. [University of Wales, Swansea (United Kingdom); Shaw, N.; Spink, G. [National Power plc (United Kingdom); Metcalfe, H. [Siemens Power Generation (United Kingdom)

1998-12-31

A range of critical experiments has been performed studying the creep and fracture behaviour of a typical CrMoV rotor steel. Initially, uniaxial tests were carried out to provide material with a predetermined level of creep damage. Then, miniature disc tests were undertaken under accelerated conditions in a similar manner to procedures used for post-exposure uniaxial testing of service components. Data analysis demonstrates that the miniature tests accurately reflect the damage present so that this approach can be used to support run/repair/replace decisions. (orig.) 8 refs.

Analytical description of changes in the magnetic states of chromium-nickel steel under uniaxial elastic deformation

Science.gov (United States)

Gorkunov, E. S.; Yakushenko, E. I.; Zadvorkin, S. M.; Mushnikov, A. N.

2017-12-01

Dependences of magnetization and magnetic permeability of the 15KhN4D structural steel on the value of uniaxial stresses and magnetic field strength are obtained. A polynomial approximation fairly accurately describing the observed changes is proposed on the basis of experimental data.

Dynamic Uniaxial Compression of HSLA-65 Steel at Elevated Temperatures

Science.gov (United States)

Dike, Shweta; Wang, Tianxue; Zuanetti, Bryan; Prakash, Vikas

2017-12-01

In the present study, the dynamic response of a high-strength, low alloy Grade 65 (HSLA-65) steel, used by the United States Navy for ship hull construction, is investigated under dynamic uniaxial compression at temperatures ranging from room temperature to 1000 °C using a novel elevated temperature split-Hopkinson pressure bar. These experiments are designed to probe the dynamic response of HSLA-65 steel in its single α-ferrite phase, mixed α + γ-austenite phase, and the single γ-austenite phase, as a function of temperature. The investigation is conducted at two different average strain rates—1450 and 2100/s. The experimental results indicate that at test temperatures in the range from room temperature to lower than 600 °C, i.e. prior to the development of the mixed α + γ phase, a net softening in flow strength is observed at all levels of plastic strain with increase in test temperatures. As the test temperatures are increased, the rate of this strain softening with temperature is observed to decrease, and at 600 °C the trend reverses itself resulting in an increase in flow stress at all strains tested. This increase in flow stress is understood be due to dynamic strain aging, where solute atoms play a distinctive role in hindering dislocation motion. At 800 °C, a (sharp) drop in the flow stress, equivalent to one-half of its value at room temperature, is observed. As the test temperature are increased to 900 and 1000 °C, further drop in flow stress are observed at all plastic strain levels. In addition, strain hardening in flow stress is observed at all test temperatures up to 600 °C; beyond 800 °C the rate of strain hardening is observed to decrease, with strain softening becoming dominant at temperatures of 900 °C and higher. Moreover, comparing the high strain rate stress versus strain data gathered on HSLA 65 in the current investigation with those available in the literature at quasi-static strain rates, strain-rate hardening can be

2D Electron Gas with 100% Spin-Polarization in the (LaMnO3)2/(SrTiO3)2 Superlattice under Uniaxial Strain

KAUST Repository

Cossu, Fabrizio

2014-07-28

By first-principles calculations we investigate the structural, electronic, and magnetic properties of the (LaMnO3)2/(SrTiO3)2 superlattice. We find that a monoclinic C2h symmetry is energetically favorable and that the spins order ferromagnetically. Under both compressive and tensile uniaxial strain the electronic structure of the superlattice shows a half-metallic character. In particular, a fully spin-polarized two-dimensional electron gas, which traces back to the Ti 3dxy orbitals, is achieved under compressive uniaxial strain. The (LaMnO3)2/(SrTiO3)2 superlattice is analysed with respect to its structure, magnetism, and electronic properties. Our results demonstrate that uniaxial strain in an experimentally accessible range, both tensile and compressive, can be used to induce half-metallicity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estimated net value and uncertainty for automating ECCS switchover at PWRs

International Nuclear Information System (INIS)

Walsh, B.; Brideau, J.; Comes, L.; Darby, J.; Guttmann, H.; Sciacca, F.; Souto, F.; Thomas, W.; Zigler, G.

1996-02-01

Question for resolution of Generic Safety Issue No. 24 is whether or not PWRs that currently rely on a manual system for ECCS switchover to recirculation should be required to install an automatic system. Risk estimates are obtained by reevaluating the contributions to core damage frequencies (CDFs) associated with failures of manual and semiautomatic switchover at a representative PWR. This study considers each separate instruction of the corresponding emergency operating procedures (EOPs), the mechanism for each control, and the relation of each control to its neighbors. Important contributions to CDF include human errors that result in completely coupled failure of both trains and failure to enter the required EOP. It is found that changeover to a semiautomatic system is not justified on the basis of cost-benefit analysis: going from a manual to a semiautomatic system reduces the CDF by 1.7 x 10 -5 per reactor-year, but the probability that the net cost of the modification being less than $1, 000 per person-rem is about 20% without license renewal. Scoping analyses, using optimist assumptions, were performed for a changeover to a semiautomatic system with automatic actuation and to a fully automatic system; in these cases the probability of a net cost being less than $1,000/person-rem is about 50% without license renewal and over 95% with license renewal

Fabrication and morphology of uniaxially aligned perylenediimide nanowires

Science.gov (United States)

Machida, Shinjiro; Tanikatsu, Makoto; Itaya, Akira; Ikeda, Noriaki

2017-06-01

Uniaxial alignment of crystalline nanowires consisting of N,N‧-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) was achieved on poly(tetrafluoroethylene) (PTFE) layers prepared by friction transfer method on a glass substrate. The nanowires were formed by spin-coating a trifluoroacetic acid (TFA) solution of PTCDI-C8 on the PTFE layers and were further grown under TFA vapor atmosphere. The morphology of the PTCDI-C8 nanowires were characterized using atomic force microscope (AFM) and fluorescence optical microscope with changing the dye concentration in the spin coating solution, annealing time in the TFA vapor, and substrate materials. The nanowires prepared on the PTFE layer on a silica-coated silicon or a mica substrate did not grow so well as those on the glass substrate. This result suggests that the surface roughness would affect the PTFE layer and the growth of the PTCDI nanowires.

Sensitivity analysis of MIDAS tests using SPACE code. Effect of nodalization

International Nuclear Information System (INIS)

Eom, Shin; Oh, Seung-Jong; Diab, Aya

2018-01-01

The nodalization sensitivity analysis for the ECCS (Emergency Core Cooling System) bypass phe�nomena was performed using the SPACE (Safety and Performance Analysis CodE) thermal hydraulic analysis computer code. The results of MIDAS (Multi-�dimensional Investigation in Downcomer Annulus Simulation) test were used. The MIDAS test was conducted by the KAERI (Korea Atomic Energy Research Institute) for the performance evaluation of the ECC (Emergency Core Cooling) bypass phenomenon in the DVI (Direct Vessel Injection) system. The main aim of this study is to examine the sensitivity of the SPACE code results to the number of thermal hydraulic channels used to model the annulus region in the MIDAS experiment. The numerical model involves three nodalization cases (4, 6, and 12 channels) and the result show that the effect of nodalization on the bypass fraction for the high steam flow rate MIDAS tests is minimal. For computational efficiency, a 4 channel representation is recommended for the SPACE code nodalization. For the low steam flow rate tests, the SPACE code over-�predicts the bypass fraction irrespective of the nodalization finesse. The over-�prediction at low steam flow may be attributed to the difficulty to accurately represent the flow regime in the vicinity of the broken cold leg.

Sensitivity analysis of MIDAS tests using SPACE code. Effect of nodalization

Energy Technology Data Exchange (ETDEWEB)

Eom, Shin; Oh, Seung-Jong; Diab, Aya [KEPCO International Nuclear Graduate School (KINGS), Ulsan (Korea, Republic of). Dept. of NPP Engineering

2018-02-15

The nodalization sensitivity analysis for the ECCS (Emergency Core Cooling System) bypass phe�nomena was performed using the SPACE (Safety and Performance Analysis CodE) thermal hydraulic analysis computer code. The results of MIDAS (Multi-�dimensional Investigation in Downcomer Annulus Simulation) test were used. The MIDAS test was conducted by the KAERI (Korea Atomic Energy Research Institute) for the performance evaluation of the ECC (Emergency Core Cooling) bypass phenomenon in the DVI (Direct Vessel Injection) system. The main aim of this study is to examine the sensitivity of the SPACE code results to the number of thermal hydraulic channels used to model the annulus region in the MIDAS experiment. The numerical model involves three nodalization cases (4, 6, and 12 channels) and the result show that the effect of nodalization on the bypass fraction for the high steam flow rate MIDAS tests is minimal. For computational efficiency, a 4 channel representation is recommended for the SPACE code nodalization. For the low steam flow rate tests, the SPACE code over-�predicts the bypass fraction irrespective of the nodalization finesse. The over-�prediction at low steam flow may be attributed to the difficulty to accurately represent the flow regime in the vicinity of the broken cold leg.

Accelerated Life Structural Benchmark Testing for a Stirling Convertor Heater Head

Science.gov (United States)

Krause, David L.; Kantzos, Pete T.

2006-01-01

For proposed long-duration NASA Space Science missions, the Department of Energy, Lockheed Martin, Infinia Corporation, and NASA Glenn Research Center are developing a high-efficiency, 110 W Stirling Radioisotope Generator (SRG110). A structurally significant limit state for the SRG110 heater head component is creep deformation induced at high material temperature and low stress level. Conventional investigations of creep behavior adequately rely on experimental results from uniaxial creep specimens, and a wealth of creep data is available for the Inconel 718 material of construction. However, the specified atypical thin heater head material is fine-grained with a heat treatment that limits precipitate growth, and little creep property data for this microstructure is available in the literature. In addition, the geometry and loading conditions apply a multiaxial stress state on the component, far from the conditions of uniaxial testing. For these reasons, an extensive experimental investigation is ongoing to aid in accurately assessing the durability of the SRG110 heater head. This investigation supplements uniaxial creep testing with pneumatic testing of heater head-like pressure vessels at design temperature with stress levels ranging from approximately the design stress to several times that. This paper presents experimental results, post-test microstructural analyses, and conclusions for four higher-stress, accelerated life tests. Analysts are using these results to calibrate deterministic and probabilistic analytical creep models of the SRG110 heater head.

ROSA-II test data report, 13

International Nuclear Information System (INIS)

1978-07-01

Results of the ROSA-II test simulating a loss-of-coolant accident (LOCA) in a PWR are presented, including test conditions and interpretations of phenomena observed in test runs 502, 505, 506 and 507. Development tests were performed to find a more effective ECCS injection method than the existing one based on cold leg injection. A combined injection of hot water into upper plenum in early stage of blowdown and subsequent cold water into lower plenum is the most effective method for a cold leg break. A hot leg injection of a low pressure injection system is effective for direct core cooling and early reflooding. The generalization for actual reactors will require analyses with a reliable code. (auth.)

Systematic evaluation program review of NRC Safety Topic VI-7.3 associated with the electrical, instrumentation and control portions of the ECCS actuation system for the Dresden II Nuclear Power Plant

International Nuclear Information System (INIS)

St Leger-Barter, G.

1980-11-01

This report documents the technical evaluation and review of NRC Safety Topic VI-7.A.3, associated with the electrical, instrumentation, and control portions of the classification of the ECCS actuation system for the Dresden II nuclear power plant, using current licensing criteria

Surface Wave Velocity-Stress Relationship in Uniaxially Loaded Concrete

DEFF Research Database (Denmark)

Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

2012-01-01

The sonic surface wave (or Rayleigh wave) velocity measured on prismatic concrete specimens under uniaxial compression was found to be highly stress-dependent. At low stress levels, the acoustoelastic effect and the closure of existing microcracks results in a gradual increase in surface wave...... velocities. At higher stress levels, concrete suffers irrecoverable damage: the existing microcracks widen and coalesce and new microcracks form. This progressive damage process leads first to the flattening and eventually the drop in the velocity-stress curves. Measurements on specimens undergoing several...... loading cycles revealed that the velocities show a stress-memory effect in good agreement with the Kaiser effect. Comparing the velocities measured during loading and unloading, the effects of stress and damage on the measured velocities could be differentiated. Moreover, the stress dependency of surface...

Pressure-induced α->ω transition in titanium metal: a systematic study of the effects of uniaxial stress

International Nuclear Information System (INIS)

Errandonea, Daniel; Meng, Y.; Somayazulu, M.; Haeusermann, D.

2005-01-01

The effects of uniaxial stress on the pressure-induced α->ω transition in pure titanium (Ti) are investigated by means of angle dispersive X-ray diffraction in a diamond-anvil cell. Experiments under four different pressure environments reveal that: (1) the onset of the transition depends on the pressure medium used, going from 4.9GPa (no pressure medium) to 10.5GPa (argon pressure medium); (2) the α and ω phases coexist over a rather large pressure range, which depends on the pressure medium employed; (3) the hysteresis and quenchability of the ω phase is affected by differences in the sample pressure environment; and (4) a short-term laser heating of Ti lowers the α->ω transition pressure. Possible transition mechanisms are discussed in the light of the present results, which clearly demonstrate the influence of uniaxial stress in the α->ω transition

Laboratory testing of gneissic rocks in Olkiluoto borehole OL-KR24

International Nuclear Information System (INIS)

Eloranta, P.

2006-10-01

The stress-strain behaviour of anisotropic gneissic rocks from Olkiluoto, Finland, was studied for a total of 25 rock mechanics tests. Samples were selected from borehole OLKR24 at a depth level of 417-442 m. Tests included 15 uniaxial compression tests, 10 indirect tensile strength tests and 6 triaxial compression tests. Strain gauges were installed in five samples to evaluate the anisotropic properties, and acoustic emission sensors were installed in ten samples to estimate the stress damage levels. The specimen preparation and tests were carried out at the Laboratory of Rock Engineering, Helsinki University of Technology, Finland. Specimens were tested under laboratory-air-dry conditions and were photographed before and after the tests. The values obtained for the uniaxial compressive strength were in the range 56.5 - 165.9 MPa and for the indirect tensile strength 7.7 - 12.1 MPa. The anisotropic ratio of Young's modulus, E/E', was of the order of 1.1. (orig.)

Large scale reflood test

International Nuclear Information System (INIS)

Hirano, Kemmei; Murao, Yoshio

1980-01-01

The large-scale reflood test with a view to ensuring the safety of light water reactors was started in fiscal 1976 based on the special account act for power source development promotion measures by the entrustment from the Science and Technology Agency. Thereafter, to establish the safety of PWRs in loss-of-coolant accidents by joint international efforts, the Japan-West Germany-U.S. research cooperation program was started in April, 1980. Thereupon, the large-scale reflood test is now included in this program. It consists of two tests using a cylindrical core testing apparatus for examining the overall system effect and a plate core testing apparatus for testing individual effects. Each apparatus is composed of the mock-ups of pressure vessel, primary loop, containment vessel and ECCS. The testing method, the test results and the research cooperation program are described. (J.P.N.)

Uniaxial cyclic strain enhances adipose-derived stem cell fusion with skeletal myocytes

Energy Technology Data Exchange (ETDEWEB)

Andersen, Jens Isak; Juhl, Morten; Nielsen, Thøger; Emmersen, Jeppe; Fink, Trine; Zachar, Vladimir; Pennisi, Cristian Pablo, E-mail: cpennisi@hst.aau.dk

2014-07-25

Highlights: • Uniaxial cyclic tensile strain (CTS) applied to ASCs alone or in coculture with myogenic precursors. • CTS promoted the formation of a highly ordered array of parallel ASCs. • Without biochemical supplements, CTS did not support advanced myogenic differentiation of ASCs. • Mechanical stimulation of cocultures boosted fusion of ASCs with skeletal myoblasts. - Abstract: Although adult muscle tissue possesses an exceptional capacity for regeneration, in the case of large defects, the restoration to original state is not possible. A well-known source for the de novo regeneration is the adipose-derived stem cells (ASCs), which can be readily isolated and have been shown to have a broad differentiation and regenerative potential. In this work, we employed uniaxial cyclic tensile strain (CTS), to mechanically stimulate human ASCs to participate in the formation skeletal myotubes in an in vitro model of myogenesis. The application of CTS for 48 h resulted in the formation of a highly ordered array of parallel ASCs, but failed to support skeletal muscle terminal differentiation. When the same stimulation paradigm was applied to cocultures with mouse skeletal muscle myoblasts, the percentage of ASCs contributing to the formation of myotubes significantly exceeded the levels reported in the literature hitherto. In perspective, the mechanical strain may be used to increase the efficiency of incorporation of ASCs in the skeletal muscles, which could be found useful in diverse traumatic or pathologic scenarios.

Exxon Nuclear WREM-based NJP-BWR ECCS evaluation model and example application to the Oyster Creek Plant

International Nuclear Information System (INIS)

Krysinski, T.L.; Bjornard, T.A.; Steves, L.H.

1975-01-01

A proposed integrated ECCS model for non-jet pump boiling water reactors is presented, using the RELAP4-EM/BLOWDOWN and RELAP4-EM/SMALL BREAK portions of the Exxon Nuclear WREM-based Generic PWR Evaluation Model coupled with the ENC NJP-BWR Fuel Heatup Model. The results of the application of the proposed model to Oyster Creek are summarized. The results of the break size sensitivity study using the proposed model for the Oyster Creek Plant are presented. The application of the above results yielded the MAPLHGR curves. Included are a description of the proposed non-jet pump boiling water reaction evaluation model, justification of its conformance with TOCFR50, Appendix K, the adopted Oyster Creek plant model, and results of the analysis and sensitivity studies. (auth)

A robust ECC based mutual authentication protocol with anonymity for session initiation protocol.

Science.gov (United States)

Mehmood, Zahid; Chen, Gongliang; Li, Jianhua; Li, Linsen; Alzahrani, Bander

2017-01-01

Over the past few years, Session Initiation Protocol (SIP) is found as a substantial application-layer protocol for the multimedia services. It is extensively used for managing, altering, terminating and distributing the multimedia sessions. Authentication plays a pivotal role in SIP environment. Currently, Lu et al. presented an authentication protocol for SIP and profess that newly proposed protocol is protected against all the familiar attacks. However, the detailed analysis describes that the Lu et al.'s protocol is exposed against server masquerading attack and user's masquerading attack. Moreover, it also fails to protect the user's identity as well as it possesses incorrect login and authentication phase. In order to establish a suitable and efficient protocol, having ability to overcome all these discrepancies, a robust ECC-based novel mutual authentication mechanism with anonymity for SIP is presented in this manuscript. The improved protocol contains an explicit parameter for user to cope the issues of security and correctness and is found to be more secure and relatively effective to protect the user's privacy, user's masquerading and server masquerading as it is verified through the comprehensive formal and informal security analysis.

A robust ECC based mutual authentication protocol with anonymity for session initiation protocol.

Directory of Open Access Journals (Sweden)

Zahid Mehmood

Full Text Available Over the past few years, Session Initiation Protocol (SIP is found as a substantial application-layer protocol for the multimedia services. It is extensively used for managing, altering, terminating and distributing the multimedia sessions. Authentication plays a pivotal role in SIP environment. Currently, Lu et al. presented an authentication protocol for SIP and profess that newly proposed protocol is protected against all the familiar attacks. However, the detailed analysis describes that the Lu et al.'s protocol is exposed against server masquerading attack and user's masquerading attack. Moreover, it also fails to protect the user's identity as well as it possesses incorrect login and authentication phase. In order to establish a suitable and efficient protocol, having ability to overcome all these discrepancies, a robust ECC-based novel mutual authentication mechanism with anonymity for SIP is presented in this manuscript. The improved protocol contains an explicit parameter for user to cope the issues of security and correctness and is found to be more secure and relatively effective to protect the user's privacy, user's masquerading and server masquerading as it is verified through the comprehensive formal and informal security analysis.

Quasi-static and ratcheting properties of trabecular bone under uniaxial and cyclic compression.

Science.gov (United States)

Gao, Li-Lan; Wei, Chao-Lei; Zhang, Chun-Qiu; Gao, Hong; Yang, Nan; Dong, Li-Min

2017-08-01

The quasi-static and ratcheting properties of trabecular bone were investigated by experiments and theoretical predictions. The creep tests with different stress levels were completed and it is found that both the creep strain and creep compliance increase rapidly at first and then increase slowly as the creep time goes by. With increase of compressive stress the creep strain increases and the creep compliance decreases. The uniaxial compressive tests show that the applied stress rate makes remarkable influence on the compressive behaviors of trabecular bone. The Young's modulus of trabecular bone increases with increase of stress rate. The stress-strain hysteresis loops of trabecular bone under cyclic load change from sparse to dense with increase of number of cycles, which agrees with the change trend of ratcheting strain. The ratcheting strain rate rapidly decreases at first, and then exhibits a relatively stable and small value after 50cycles. Both the ratcheting strain and ratcheting strain rate increase with increase of stress amplitude or with decrease of stress rate. The creep model and the nonlinear viscoelastic constitutive model of trabecular bone were proposed and used to predict its creep property and rate-dependent compressive property. The results show that there are good agreements between the experimental data and predictions. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of micro fatigue crack growth under equi-biaxial stress by membranous pressure fatigue test

International Nuclear Information System (INIS)

Iida, Satoshi; Abe, Shigeki; Nakamura, Takao; Kamaya, Masayuki

2014-01-01

For preventing nuclear power plant (NPP) accidents, NPPs are required to ensure system safety in long term safe operation under aging degradation. Now, fatigue accumulation is one of major ageing phenomena and are evaluated to ensure safety by design fatigue curve that are based on the results of uniaxial fatigue tests. On the other hand, thermal stress that occurs in piping of actual components is not uniaxial but equi-biaxial. For accurate evaluation, it is required to conform real circumstance. In this study, membranous pressure fatigue test was conducted to simulated equi-biaxial stress. Crack initiation and crack growth were examined by replica investigation. Calculation result of equivalent stress intensity factor shows crack growth under equi-biaxial stress is faster than under uniaxial stress. It is concluded that equi-biaxial fatigue behavior should be considered in the evaluation of fatigue crack initiation and crack growth. (author)

Shock Response of Commercial Purity Polycrystalline Magnesium Under Uniaxial Strain at Elevated Temperatures

Science.gov (United States)

Wang, Tianxue; Zuanetti, Bryan; Prakash, Vikas

2017-12-01

In the present paper, results of plate impact experiments designed to investigate the onset of incipient plasticity in commercial purity polycrystalline magnesium (99.9%) under weak uniaxial strain compression and elevated temperatures up to melt are presented. The dynamic stress at yield and post yield of magnesium, as inferred from the measured normal component of the particle velocity histories at the free (rear) surface of the target plate, are observed to decrease progressively with increasing test temperatures in the range from 23 to 500 °C. At (higher) test temperatures in the range 500-610 °C, the rate of decrease of dynamic stress with temperature at yield and post-yield in the sample is observed to weaken. At still higher test temperatures (617 and 630 °C), a dramatic increase in dynamic yield as well as flow stress is observed indicating a change in dominant mechanism of plastic deformation as the sample approaches the melt point of magnesium at strain rates of 105/s. In addition to these measurements at the wavefront, the plateau region of the free surface particle velocity profiles indicates that the longitudinal (plastic) impedance of the magnesium samples decreases continuously as the sample temperatures are increased from room to 610 °C, and then reverses trend (indicating increasing material longitudinal impedance/strength) as the sample temperatures are increased to 617 and 630 °C. Electron back scattered diffraction analysis of the as-received and annealed pre-test magnesium samples reveal grain coarsening as well as grain re-orientation to a different texture during the heating process of the samples.

Pre-test analysis of a LBLOCA using the design data of the ATLAS facility, a reduced-height integral effect test loop for PWRs

International Nuclear Information System (INIS)

Hyun-Sik Park; Ki-Yong Choi; Dong-Jin Euh; Tae-Soon Kwon; Won-Pil Baek

2005-01-01

Full text of publication follows: The simulation capability of the KAERI integral effect test facility, ATLAS (Advanced Thermalhydraulic Test Loop for Accident Simulation), has been assessed for a large-break loss-of-coolant accident (LBLOCA) transient. The ATLAS facility is a 1/2 height-scaled, 1/144 area-scaled (1/288 in volume scale), and full-pressure test loop based on the design features of the APR1400, an evolutionary pressurized water reactor that has been developed by Korean industry. The APR1400 has four mechanically separated hydraulic trains for the emergency core cooling system (ECCS) with direct vessel injection (DVI). The APR1400 design features have brought about several new safety issues related to the LBLOCA including the steam-water interaction, ECC bypass, and boiling in the reactor vessel downcomer. The ATLAS facility will be used to investigate the multiple responses between the systems or between the components during various anticipated transients. The ATLAS facility has been designed according to a scaling method that is mainly based on the model suggested by Ishii and Kataoka. The ATLAS facility is being evaluated against the prototype plant APR1400 with the same control logics and accident scenarios using the best-estimated code, MARS. This paper briefly introduces the basic design features of the ATLAS facility and presents the results of pre-test analysis for a postulated LBLOCA of a cold leg. The LBLOCA analyses has been conducted to assess the validity of the applied scaling law and the similarity between the ATLAS facility and the APR1400. As the core simulator of the ATLAS facility has the 10% capability of the scaled full power, the blowdown phase can not be simulated, and the starting point of the accident scenario is around the end of blowdown. So it is an important problem to find the correct initial conditions. For the analyzed LBLOCA scenario, the ATLAS facility showed very similar thermal-hydraulic characteristics to the APR

Anomalous elastic response of silicon to uniaxial shock compression on nanosecond time scales.

Science.gov (United States)

Loveridge-Smith, A; Allen, A; Belak, J; Boehly, T; Hauer, A; Holian, B; Kalantar, D; Kyrala, G; Lee, R W; Lomdahl, P; Meyers, M A; Paisley, D; Pollaine, S; Remington, B; Swift, D C; Weber, S; Wark, J S

2001-03-12

We have used x-ray diffraction with subnanosecond temporal resolution to measure the lattice parameters of orthogonal planes in shock compressed single crystals of silicon (Si) and copper (Cu). Despite uniaxial compression along the (400) direction of Si reducing the lattice spacing by nearly 11%, no observable changes occur in planes with normals orthogonal to the shock propagation direction. In contrast, shocked Cu shows prompt hydrostaticlike compression. These results are consistent with simple estimates of plastic strain rates based on dislocation velocity data.

Isogyres - Manifestation of Spin-orbit interaction in uniaxial crystal: A closed-fringe Fourier analysis of conoscopic interference

Science.gov (United States)

Samlan, C. T.; Naik, Dinesh N.; Viswanathan, Nirmal K.

2016-09-01

Discovered in 1813, the conoscopic interference pattern observed due to light propagating through a crystal, kept between crossed polarizers, shows isochromates and isogyres, respectively containing information about the dynamic and geometric phase acquired by the beam. We propose and demonstrate a closed-fringe Fourier analysis method to disentangle the isogyres from the isochromates, leading us to the azimuthally varying geometric phase and its manifestation as isogyres. This azimuthally varying geometric phase is shown to be the underlying mechanism for the spin-to-orbital angular momentum conversion observed in a diverging optical field propagating through a z-cut uniaxial crystal. We extend the formalism to study the optical activity mediated uniaxial-to-biaxial transformation due to a weak transverse electric field applied across the crystal. Closely associated with the phase and polarization singularities of the optical field, the formalism enables us to understand crystal optics in a new way, paving the way to anticipate several emerging phenomena.

Development of porous ceramics by lycopodium using uniaxial pressing and sintering

Directory of Open Access Journals (Sweden)

Rita Serzane

2010-12-01

Full Text Available In this work microporous hydroxyapatite (HAp ceramics were fabricated using lycopodium as a porosifier. The samples were produced by uniaxial pressing and then heating at high temperatures, 1100°C and 1200°C, to burn-out porogens and sintering. The obtained samples had porosity over the variable range of 12 to 45% with different pore size ranging from 0.2 to 25 µm. Chemical and physical characterization was determined by scanning electron microscopy (SEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and bending strength measurements. The bending strength of the prepared samples was in the range of 1.97–21.81 MPa.

Mechanical properties of graphene nanoribbons under uniaxial tensile strain

Science.gov (United States)

Yoneyama, Kazufumi; Yamanaka, Ayaka; Okada, Susumu

2018-03-01

Based on the density functional theory with the generalized gradient approximation, we investigated the mechanical properties of graphene nanoribbons in terms of their edge shape under a uniaxial tensile strain. The nanoribbons with armchair and zigzag edges retain their structure under a large tensile strain, while the nanoribbons with chiral edges are fragile against the tensile strain compared with those with armchair and zigzag edges. The fracture started at the cove region, which corresponds to the border between the zigzag and armchair edges for the nanoribbons with chiral edges. For the nanoribbons with armchair edges, the fracture started at one of the cove regions at the edges. In contrast, the fracture started at the inner region of the nanoribbons with zigzag edges. The bond elongation under the tensile strain depends on the mutual arrangement of covalent bonds with respect to the strain direction.

Light propagation in two-dimensional photonic crystals based on uniaxial polar materials: results on polaritonic spectrum

Science.gov (United States)

Gómez-Urrea, H. A.; Duque, C. A.; Pérez-Quintana, I. V.; Mora-Ramos, M. E.

2017-03-01

The dispersion relations of two-dimensional photonic crystals made of uniaxial polaritonic cylinders arranged in triangular lattice are calculated. The particular case of the transverse magnetic polarization is taken into account. Three different uniaxial materials showing transverse phonon-polariton excitations are considered: aluminum nitride, gallium nitride, and indium nitride. The study is carried out by means of the finite-difference time-domain technique for the solution of Maxwell equations, together with the method of the auxiliary differential equation. It is shown that changing the filling fraction can result in the modification of both the photonic and polaritonic bandgaps in the optical dispersion relations. Wider gaps appear for smaller filling fraction values, whereas a larger number of photonic bandgaps will occur within the frequency range considered when a larger filling fraction is used. The effect of including the distinct wurtzite III-V nitride semiconductors as core materials in the cylinders embedded in the air on the photonic properties is discussed as well, highlighting the effect of the dielectric anisotropy on the properties of the polaritonic part of the photonic spectrum.

Uniaxial ferromagnetism of local uranium moments in hexagonal UBeGe

Science.gov (United States)

Gumeniuk, Roman; Yaresko, Alexander N.; Schnelle, Walter; Nicklas, Michael; Kvashnina, Kristina O.; Hennig, Christoph; Grin, Yuri; Leithe-Jasper, Andreas

2018-05-01

The new intermetallic uranium beryllium germanide UBeGe and its thorium analogon ThBeGe crystallize with the hexagonal ZrBeSi type of structure. Studies of magnetic, thermal, and transport properties were performed on polycrystalline samples between 1.8 and 750K. UBeGe is a uniaxial ferromagnet and there are indications for two magnetic transitions at TC(1 )≈160 K and TC(2 )≈150 K . The high paramagnetic effective moment μeff≈3.1 μB , x-ray absorption near-edge spectroscopy (XANES, 17-300 K), as well as theoretical DFT calculations indicate localized U 5 f2 states in UBeGe. ThBeGe is a diamagnetic metallic material with low density of states at the Fermi level.

Experimental observation of a multi-dimensional mixing behavior of steam-water flow in the MIDAS test facility

International Nuclear Information System (INIS)

Kweon, T. S.; Yun, B. J.; Ah, D. J.; Ju, I. C.; Song, C. H.; Park, J. K.

2001-01-01

Multi-dimensional thermal-hydraulic hehavior, such as ECC (Emergency Core Cooling) bypass, ECC penetration, steam-water condensation and accumulated water level, in an annular downcomer of a PWR (Pressurized Water Reactor) reactor vessel with a DVI(Direct Vessel Injection) injection mode is presented based on the experimental observations in the MIDAS (Multi-dimensional Investigation in Downcomer Annulus Simulation) steam-water facility. From the steady-state tests to similate a late reflood phase of LBLOCA (Large Break Loss-of-Coolant Accidents), major thermal-hydraulic phenomena in the downcomer are quantified under a wide range of test conditions. Especially, isothermal lines show well multi-dimensional phenomena of phase interaction between steam and water in the annulus downcomer. Overall test results show that multi-dimensional thermal-hydraulic behaviors occur in the downcomer annulus region as expected. The MIDAS test facility is a steam-water separate effect test facility, which is 1/4.93 linearly scaled-down of a 1400 MWe PWR type of nuclear reactor, with focusing on understanding multi-dimensional thermal-hydraulic phenomena in annulus downcomer with various types of safety injection location during refill or reflood phase of a LBLOCA in PWR

EM Scattering by a Conducting Sphere Coated with a Uniaxial Layer under Arbitrary Illumination Angle in a Fixed Laboratory Frame

Directory of Open Access Journals (Sweden)

C.M.Tse

2011-12-01

Full Text Available Under a fixed laboratory frame, the electromagnetic theory of the scattering of a plane wave of arbitrary polarizations incidence from arbitrary angles by a uniaxial anisotropic medium was obtained for the first time, and could be solved analytically from an eigensystem determined by a uniaxial anisotropic medium. By applying the boundary conditions at respective interfaces of the coated spherical structure, the unknown expansion coefficients can be obtained from the incident field and the electromagnetic fields in the anisotropic medium, and from the scattered field. Not only did the numerical results demonstrate the validity of our proposed theory but this paper shall also provide discussions in relation to some general cases (under arbitrary incident angles of bistatic radar cross section.

Synthesis and characterization of uniaxial ferrogels with Ni nanorods as magnetic phase

International Nuclear Information System (INIS)

Bender, P.; Guenther, A.; Tschoepe, A.; Birringer, R.

2011-01-01

In the present study, the rotation of magnetic nanorods in a soft hydrogel matrix induced by a homogeneous magnetic field is investigated. Magnetic nanorods of ∼151.2nm length and ∼17.7nm diameter are synthesized via current-pulsed electrodeposition of nickel into porous aluminum oxide-templates. The nanorods are processed towards a stable colloidal dispersion by dissolution of the alumina template in aqueous NaOH to which PVP (polyvinyl-pyrrolidone) is added as surfactant. These suspensions are used to prepare gelatine-based ferrogels of different shear modulus with either isotropic or uniaxial orientation-distribution of the nanorods. While magnetization measurements of rigid ferrogels mainly reflect the magnetic properties of the nickel nanorods, the magnetization behavior of soft ferrogels is significantly influenced by a field-induced rotation of the nickel nanorods in the low compliant matrix. A particular analysis of magnetization measurements on uniaxial ferrogels enables to quantify the rotation angle of the nanorods with respect to their initial orientation under the influence of a transversal homogeneous magnetic field. The analysis of the field-dependent rotation also allows to estimate the local shear modulus of the matrix which is demonstrated by an investigation of room temperature ageing process of the ferrogel. - Highlights: → We present the synthesis of ferrogels containing ferromagnetic Ni nanorods. → The torque in the homogeneous magnetic field leads to a rotation of the nanorods. → The rotation angle increases with decreasing shear modulus of the gel matrix. → The local shear modulus can be estimated by analyzing magnetization measurements.

TESTING OF ENHANCED CHEMICAL CLEANING OF SRS ACTUAL WASTE TANK 5F AND TANK 12H SLUDGES

Energy Technology Data Exchange (ETDEWEB)

Martino, C.; King, W.

2011-08-22

Forty three of the High Level Waste (HLW) tanks at the Savannah River Site (SRS) have internal structures that hinder removal of the last approximately five thousand gallons of waste sludge solely by mechanical means. Chemical cleaning can be utilized to dissolve the sludge heel with oxalic acid (OA) and pump the material to a separate waste tank in preparation for final disposition. This dissolved sludge material is pH adjusted downstream of the dissolution process, precipitating the sludge components along with sodium oxalate solids. The large quantities of sodium oxalate and other metal oxalates formed impact downstream processes by requiring additional washing during sludge batch preparation and increase the amount of material that must be processed in the tank farm evaporator systems and the Saltstone Processing Facility. Enhanced Chemical Cleaning (ECC) was identified as a potential method for greatly reducing the impact of oxalate additions to the SRS Tank Farms without adding additional components to the waste that would extend processing or increase waste form volumes. In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate an alternative to the baseline 8 wt. % OA chemical cleaning technology for tank sludge heel removal. The baseline OA technology results in the addition of significant volumes of oxalate salts to the SRS tank farm and there is insufficient space to accommodate the neutralized streams resulting from the treatment of the multiple remaining waste tanks requiring closure. ECC is a promising alternative to bulk OA cleaning, which utilizes a more dilute OA (nominally 2 wt. % at a pH of around 2) and an oxalate destruction technology. The technology is being adapted by AREVA from their decontamination technology for Nuclear Power Plant secondary side scale removal. This report contains results from the SRNL small scale testing of the ECC process

Verification of LOCA/ECCS analysis codes ALARM-B2 and THYDE-B1 by comparison with RELAP4/MOD6/U4/J3

International Nuclear Information System (INIS)

Shimizu, Takashi

1982-08-01

For a verification study of ALARM-B2 code and THYDE-B1 code which are the component of the JAERI code system for evaluation of BWR ECCS performance, calculations for typical small and large break LOCA in BWR were done, and compared with those by RELAP4/MOD6/U4/J3 code. This report describes the influences of differences between the analytical models incorporated in the individual code and the problems identified by this verification study. (author)

Twist phase-induced characteristics changes of a radially polarized Gaussian Schell-Model beam in a uniaxial crystal orthogonal to the optical axis

Science.gov (United States)

Cao, Pengfei; Fu, Wenyu

2017-10-01

Based on the extended Huygens-Fresnel integral formula and unified theory of coherence and polarization, we obtained the cross-spectral density matrix elements for a radially polarized partially coherent twist (RPPCT) beam in a uniaxial crystal. Moreover, compared with free space, we explore numerically the evolution properties of a RPPCT beam in a uniaxial crystal. The calculation results show that the evolution properties of a RPPCT beam in crystals are substantially different from its properties in free space. These properties in crystals are mainly determined by the twist factor and the ratio of extraordinary index to ordinary refractive index. In a uniaxial crystal, the distribution of the intensity of a RPPCT beam all exhibits non-circular symmetry, and these distributions change with twist factor and the ratio of extraordinary index to ordinary refractive index. The twist factor affects their rotation orientation angles, and the ratio of extraordinary index to ordinary refractive index impacts their twisted levels. This novel characteristics can be used for free-space optical communications, particle manipulation and nonlinear optics, where partially coherent beam with controlled profile and twist factor are required.

Constitutive modeling for uniaxial time-dependent ratcheting of SS304 stainless steel

International Nuclear Information System (INIS)

Kan Qianhua; Kang Guozheng; Zhang Juan

2007-01-01

Based on the experimental results of uniaxial time-dependent ratcheting behavior of SS304 stainless steel at room temperature and 973K, a new time-dependent constitutive model was proposed. The model describes the time-dependent ratcheting by adding a static/thermal recovery into the Abdel-Karim-Ohno non-linear kinematic hardening rule. The capability of the model to describe the time-dependent ratcheting was discussed by comparing the simulations with the corresponding experimental results. It is shown that the revised unified viscoplastic model can simulate the time-dependent ratcheting reasonably both at room and high temperatures. (authors)

Electric field-induced valley degeneracy lifting in uniaxial strained graphene: evidence from magnetophonon resonance

OpenAIRE

Assili, Mohamed; Haddad, Sonia; Kang, Woun

2015-01-01

A double peak structure in the magneto-phonon resonance (MPR) spectrum of uniaxial strained graphene, under crossed electric and magnetic fields, is predicted. We focus on the $\\Gamma$ point optical phonon modes coupled to the inter-Landau level transitions $0 \\leftrightarrows \\pm 1$ where MPR is expected to be more pronounced at high magnetic field. We derive the frequency shifts and the broadenings of the longitudinal (LO) and transverse (TO) optical phonon modes taking into account the eff...

Modeling the electrical resistance of gold film conductors on uniaxially stretched elastomeric substrates

Science.gov (United States)

Cao, Wenzhe; Görrn, Patrick; Wagner, Sigurd

2011-05-01

The electrical resistance of gold film conductors on polydimethyl siloxane substrates at stages of uniaxial stretching is measured and modeled. The surface area of a gold conductor is assumed constant during stretching so that the exposed substrate takes up all strain. Sheet resistances are calculated from frames of scanning electron micrographs by numerically solving for the electrical potentials of all pixels in a frame. These sheet resistances agree sufficiently well with values measured on the same conductors to give credence to the model of a stretchable network of gold links defined by microcracks.

Phonon dispersion evolution in uniaxially strained aluminum crystal

Science.gov (United States)

Parthasarathy, Ranganathan; Misra, Anil; Aryal, Sitaram; Ouyang, Lizhi

2018-04-01

The influence of loading upon the phonon dispersion of crystalline materials could be highly nonlinear with certain particular trends that depend upon the loading path. In this paper, we have calculated the influence of [100] uniaxial strain on the phonon dispersion and group velocities in fcc aluminum using second moments of position obtained from molecular dynamics (MD) simulation at 300 K. In contrast to nonlinear monotonic variation of both longitudinal and transverse phonon frequencies along the Δ , Λ and Σ lines of the first Brillouin zone under tension, transverse phonon branches along the Λ line show inflection at specific wavevectors when the compressive strain exceeds 5%. Further, the longitudinal group velocities along the high-symmetry Δ line vary non-monotonically with strain, reaching a minimum at 5% compressive strain. Throughout the strain range studied, the equilibrium positions of atoms displace in an affine manner preserving certain static structural symmetry. We attribute the anomalies in the phonon dispersion to the non-affine evolution of second moments of atomic position, and the associated plateauing of force constants under the applied strain path.

Experimental and numerical study of the failure process and energy mechanisms of rock-like materials containing cross un-persistent joints under uniaxial compression.

Directory of Open Access Journals (Sweden)

Rihong Cao

Full Text Available Joints and fissures in natural rocks have a significant influence on the stability of the rock mass, and it is often necessary to evaluate strength failure and crack evolution behavior. In this paper, based on experimental tests and numerical simulation (PFC2D, the macro-mechanical behavior and energy mechanism of jointed rock-like specimens with cross non-persistent joints under uniaxial loading were investigated. The focus was to study the effect of joint dip angle α and intersection angle γ on the characteristic stress, the coalescence modes and the energy release of jointed rock-like specimens. For specimens with γ = 30° and 45°, the UCS (uniaxial compression strength, CIS (crack initiation stress and CDiS (critical dilatancy stress increase as α increases from 0° to 75°. When γ = 60° and 75°, the UCS, CIS and CDiS increase as α increases from 0° to 60° and decrease when α is over 60°. Both the inclination angle α and intersection angle γ have great influence on the failure pattern of pre-cracked specimens. With different α and γ, specimens exhibit 4 kinds of failure patterns. Both the experimental and numerical results show that the energy of a specimen has similar trends with characteristic stress as α increases.

Biaxial Testing of 2195 Aluminum Lithium Alloy Using Cruciform Specimens

Science.gov (United States)

Johnston, W. M.; Pollock, W. D.; Dawicke, D. S.; Wagner, John A. (Technical Monitor)

2002-01-01

A cruciform biaxial test specimen was used to test the effect of biaxial load on the yield of aluminum-lithium alloy 2195. Fifteen cruciform specimens were tested from 2 thicknesses of 2195-T8 plate, 0.45 in. and 1.75 in. These results were compared to the results from uniaxial tensile tests of the same alloy, and cruciform biaxial tests of aluminum alloy 2219-T87.

High Temperature Uniaxial Compression and Stress-Relaxation Behavior of India-Specific RAFM Steel

Science.gov (United States)

Shah, Naimish S.; Sunil, Saurav; Sarkar, Apu

2018-05-01

India-specific reduced activity ferritic martensitic steel (INRAFM), a modified 9Cr-1Mo grade, has been developed by India as its own structural material for fabrication of the Indian Test Blanket Module (TBM) to be installed in the International Thermonuclear Energy Reactor (ITER). The extensive study on mechanical and physical properties of this material has been currently going on for appraisal of this material before being put to use in the ITER. High temperature compression, stress-relaxation, and strain-rate change behavior of the INRAFM steel have been investigated. The optical microscopic and scanning electron microscopic characterizations were carried out to observe the microstructural changes that occur during uniaxial compressive deformation test. Comparable true plastic stress values at 300 °C and 500 °C and a high drop in true plastic stress at 600 °C were observed during the compression test. Stress-relaxation behaviors were investigated at 500 °C, 550 °C, and 600 °C at a strain rate of 10-3 s-1. The creep properties of the steel at different temperatures were predicted from the stress-relaxation test. The Norton's stress exponent (n) was found to decrease with the increasing temperature. Using Bird-Mukherjee-Dorn relationship, the temperature-compensated normalized strain rate vs stress was plotted. The stress exponent (n) value of 10.05 was obtained from the normalized plot. The increasing nature of the strain rate sensitivity (m) with the test temperature was found from strain-rate change test. The low plastic stability with m 0.06 was observed at 600 °C. The activation volume (V *) values were obtained in the range of 100 to 300 b3. By comparing the experimental values with the literature, the rate-controlling mechanisms at the thermally activated region of high temperature were found to be the nonconservative movement of jogged screw dislocations and thermal breaking of attractive junctions.

Shock-induced transformations in crystalline RDX: a uniaxial constant-stress Hugoniostat molecular dynamics simulation study.

Science.gov (United States)

Bedrov, Dmitry; Hooper, Justin B; Smith, Grant D; Sewell, Thomas D

2009-07-21

Molecular dynamics (MD) simulations of uniaxial shock compression along the [100] and [001] directions in the alpha polymorph of hexahydro-1,3,5-trinitro-1,3,5-triazine (alpha-RDX) have been conducted over a wide range of shock pressures using the uniaxial constant stress Hugoniostat method [Ravelo et al., Phys. Rev. B 70, 014103 (2004)]. We demonstrate that the Hugoniostat method is suitable for studying shock compression in atomic-scale models of energetic materials without the necessity to consider the extremely large simulation cells required for an explicit shock wave simulation. Specifically, direct comparison of results obtained using the Hugoniostat approach to those reported by Thompson and co-workers [Phys. Rev. B 78, 014107 (2008)] based on large-scale MD simulations of shocks using the shock front absorbing boundary condition (SFABC) approach indicates that Hugoniostat simulations of systems containing several thousand molecules reproduced the salient features observed in the SFABC simulations involving roughly a quarter-million molecules, namely, nucleation and growth of nanoscale shear bands for shocks propagating along the [100] direction and the polymorphic alpha-gamma phase transition for shocks directed along the [001] direction. The Hugoniostat simulations yielded predictions of the Hugoniot elastic limit for the [100] shock direction consistent with SFABC simulation results.

Long-wavelength optical phonon behavior in uniaxial strained graphene: Role of electron-phonon interaction

OpenAIRE

Assili, Mohamed; Haddad, Sonia

2014-01-01

We derive the frequency shifts and the broadening of $\\Gamma$ point longitudinal optical (LO) and transverse optical (TO) phonon modes, due to electron-phonon interaction, in graphene under uniaxial strain as a function of the electron density and the disorder amount. We show that, in the absence of a shear strain component, such interaction gives rise to a lifting of the degeneracy of the LO and TO modes which contributes to the splitting of the G Raman band. The anisotropy of the electronic...

Study on Energy Absorption Capacity of Steel-Polyester Hybrid Fiber Reinforced Concrete Under Uni-axial Compression

Science.gov (United States)

Chella Gifta, C.; Prabavathy, S.

2018-05-01

This work presents the energy absorption capacity of hybrid fiber reinforced concrete made with hooked end steel fibers (0.5 and 0.75%) and straight polyester fibers (0.5, 0.8, 1.0 and 2.0%). Compressive toughness (energy absorption capacity) under uni-axial compression was evaluated on 100 × 200 mm size cylindrical specimens with varying steel and polyester fiber content. Efficiency of the hybrid fiber reinforcement is studied with respect to fiber type, size and volume fractions in this investigation. The vertical displacement under uni-axial compression was measured under the applied loads and the load-deformation curves were plotted. From these curves the toughness values were calculated and the results were compared with steel and polyester as individual fibers. The hybridization of 0.5% steel + 0.5% polyester performed well in post peak region due to the addition of polyester fibers with steel fibers and the energy absorption value was 23% greater than 0.5% steel FRC. Peak stress values were also higher in hybrid series than single fiber and based on the results it is concluded that hybrid fiber reinforcement improves the toughness characteristics of concrete without affecting workability.

Assessment of strength characteristics of Al2024 ECAP metal using small punch testing

International Nuclear Information System (INIS)

Ma, Young Wha; Choi, Jeong Woo; Yoon, Kee Bong; Kim, Seon Hwa

2006-01-01

When subjected to severe shear deformation by ECAP, microstructure of Al2024 becomes extremely refined. To measure the strength of that, Small Punch(SP) testing method was adopted as a substitute for the conventional uniaxial tensile testing because the size of material processed by ECAP were limited to ψ12 mm in transverse direction. SP tests were performed with specimens in longitudinal and transverse directions of Al2024 ECAP metal. For comparing the strength values with those assessed by SP tests, uniaxial tensile tests were also conducted with specimens in longitudinal direction. Failure surfaces of the tested SP specimens showed that failure mode was shear deformation and Al2024 ECAP metal has an anisotropy in strength. Thus, conventional equations proposed for assessing the strength characteristics were improper to assess those of Al2024 ECAP metal. In this paper a way of assessing the strength of Al2024 ECAP metal was proposed and was proven to be effective

Multicriteria decision-making analysis based methodology for predicting carbonate rocks' uniaxial compressive strength

Directory of Open Access Journals (Sweden)

Ersoy Hakan

2012-10-01

Full Text Available

ABSTRACT

Uniaxial compressive strength (UCS deals with materials' to ability to withstand axially-directed pushing forces and especially considered to be rock materials' most important mechanical properties. However, the UCS test is an expensive, very time-consuming test to perform in the laboratory and requires high-quality core samples having regular geometry. Empirical equations were thus proposed for predicting UCS as a function of rocks' index properties. Analytical hierarchy process and multiple regression analysis based methodology were used (as opposed to traditional linear regression methods on data-sets obtained from carbonate rocks in NE Turkey. Limestone samples ranging from Devonian to late Cretaceous ages were chosen; travertine-onyx samples were selected from morphological environments considering their surface environmental conditions Test results from experiments carried out on about 250 carbonate rock samples were used in deriving the model. While the hierarchy model focused on determining the most important index properties affecting on UCS, regression analysis established meaningful relationships between UCS and index properties; 0. 85 and 0. 83 positive coefficient correlations between the variables were determined by regression analysis. The methodology provided an appropriate alternative to quantitative estimation of UCS and avoided the need for tedious and time consuming laboratory testing

RESUMEN

La resistencia a la compresión uniaxial (RCU trata con la capacidad de los materiales para soportar fuerzas empujantes dirigidas axialmente y, especialmente, es considerada ser uno de las más importantes propiedades mecánicas de

An Experimental and Numerical Study on Cracking Behavior of Brittle Sandstone Containing Two Non-coplanar Fissures Under Uniaxial Compression

Science.gov (United States)

Yang, Sheng-Qi; Tian, Wen-Ling; Huang, Yan-Hua; Ranjith, P. G.; Ju, Yang

2016-04-01

To understand the fracture mechanism in all kinds of rock engineering, it is important to investigate the fracture evolution behavior of pre-fissured rock. In this research, we conducted uniaxial compression experiments to evaluate the influence of ligament angle on the strength, deformability, and fracture coalescence behavior of rectangular prismatic specimens (80 × 160 × 30 mm) of brittle sandstone containing two non-coplanar fissures. The experimental results show that the peak strength of sandstone containing two non-coplanar fissures depends on the ligament angle, but the elastic modulus is not closely related to the ligament angle. With the increase of ligament angle, the peak strength decreased at a ligament angle of 60°, before increasing up to our maximum ligament angle of 120°. Crack initiation, propagation, and coalescence were all observed and characterized from the inner and outer tips of pre-existing non-coplanar fissures using photographic monitoring. Based on the results, the sequence of crack evolution in sandstone containing two non-coplanar fissures was analyzed in detail. In order to fully understand the crack evolution mechanism of brittle sandstone, numerical simulations using PFC2D were performed for specimens containing two non-coplanar fissures under uniaxial compression. The results are in good agreement with the experimental results. By analyzing the stress field, the crack evolution mechanism in brittle sandstone containing two non-coplanar fissures under uniaxial compression is revealed. These experimental and numerical results are expected to improve the understanding of the unstable fracture mechanism of fissured rock engineering structures.

Ab initio study of Co and Ni under uniaxial and biaxial loading and in epitaxial overlayers

Czech Academy of Sciences Publication Activity Database

Zelený, Martin; Legut, Dominik; Šob, Mojmír

2008-01-01

Roč. 78, č. 22 (2008), 224105/1-224105/11 ISSN 1098-0121 R&D Projects: GA ČR GD106/05/H008; GA AV ČR IAA1041302; GA MŠk OC 147 Institutional research plan: CEZ:AV0Z20410507 Keywords : ab initio calculations * epitaxial overlayers * uniaxial and biaxial loading Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008

ATHLET calculations of the pressurizer surge line break (PH-SLB test) at the PMK-2 test facility

International Nuclear Information System (INIS)

Krepper, E.; Schaefer, F.

2000-01-01

At the Hungarian integral test facility PMK-2 a pressurizer surge line break experiment (PH-SLB test) was carried out with the PHARE 4.2.6b project. The primary objective of the test was to provide experimental data for a surge line break transient at VVER-440 reactors with reduced injection from the emergency core cooling systems (ECC). At the Institute of Safety Research calculations of the experiment were performed with the thermohydraulic computer code ATHLET, which was developed by GRS (Gesellschaft fuer Anlagen- und Reaktorsicherheit) mbH. In the context of the PHARE 4.2.6b project the Institute of Safety Research has also supplied the void fraction measurement system for the PMK-2 test facility and was involved in the evaluation of the experimental results. (orig.)

Effects of hydrostatic pressure and uniaxial strain on spin-Peierls transition in an organic radical magnet, BBDTA·InCl4

International Nuclear Information System (INIS)

Mito, Masaki; Kawagoe, Seiichiro; Deguchi, Hiroyuki; Takagi, Seichi; Fujita, Wataru; Awaga, Kunio; Kondo, Ryusuke; Kagoshima, Seiichi

2009-01-01

We investigated the effects of hydrostatic pressure and uniaxial strain on the spin-Peierls (SP) transition of an organic radical magnet, benzo[1,2-d:4,5-d']bis[1,3,2]dithiazole(BBDTA)·InCl 4 . It has a one-dimensional coordination polymer structure along its c-axis and its SP transition occurs at 108 K. The SP transition temperature T SP decreased to 99 K at a hydrostatic pressure of 10 kbar, while it increased to 132 K at a uniaxial strain along the c-axis of 8 kbar. The pressure dependences of T SP under these two conditions were discussed by evaluating two parameters, namely, the intrachain interaction 2J/k B and the effective spin-lattice coupling parameter η, that are related to T SP by the equation T SP =1.6ηJ/k B . Under ambient pressure, the a- and c-axes of this material shortened monotonically with decreasing temperature, while the b-axis elongated below T SP . In this study, we found the correlation between η and the change in the lattice constant b. 2J/k B increased with increasing hydrostatic pressure and uniaxial strain, suggesting that the contraction along the c-axis does not depend on the manner of pressurization. From the evaluation of η, the observed variation in T SP is explained by the difference between the changes in b under the two pressurization conditions. (author)

Synthesis of full Poincaré beams by means of uniaxial crystals

Science.gov (United States)

Piquero, G.; Monroy, L.; Santarsiero, M.; Alonzo, M.; de Sande, J. C. G.

2018-06-01

A simple optical system is proposed to generate full-Poincaré beams (FPBs), i.e. beams presenting all possible states of (total) polarization across their transverse section. The method consists in focusing a uniformly polarized laser beam onto a uniaxial crystal having its optic axis parallel to the propagation axis of the impinging beam. A simple approximated model is used to obtain the analytical expression of the beam polarization at the output of the crystal. The output beam is then proved to be a FPB. By changing the polarization state of the input field, full-Poincaré beams are still obtained, but presenting different distributions of the polarization state across the beam section. Experimental results are reported, showing an excellent agreement with the theoretical predictions.

Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

KAUST Repository

Hou, Zhipeng; Ren, Weijun; Ding, Bei; Xu, Guizhou; Wang, Yue; Yang, Bing; Zhang, Qiang; Zhang, Ying; Liu, Enke; Xu, Feng; Wang, Wenhong; Wu, Guangheng; Zhang, Xixiang; Shen, Baogen; Zhang, Zhidong

2017-01-01

to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial

Standard test method for creep-fatigue testing

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This test method covers the determination of mechanical properties pertaining to creep-fatigue deformation or crack formation in nominally homogeneous materials, or both by the use of test specimens subjected to uniaxial forces under isothermal conditions. It concerns fatigue testing at strain rates or with cycles involving sufficiently long hold times to be responsible for the cyclic deformation response and cycles to crack formation to be affected by creep (and oxidation). It is intended as a test method for fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. The cyclic conditions responsible for creep-fatigue deformation and cracking vary with material and with temperature for a given material. 1.2 The use of this test method is limited to specimens and does not cover testing of full-scale components, structures, or consumer products. 1.3 This test method is primarily ...

Uniaxial strain orientation dependence of superconducting transition temperature (Tc) and critical superconducting pressure (Pc) in β-(BDA-TTP)2I3.

Science.gov (United States)

Kikuchi, Koichi; Isono, Takayuki; Kojima, Masayuki; Yoshimoto, Haruo; Kodama, Takeshi; Fujita, Wataru; Yokogawa, Keiichi; Yoshino, Harukazu; Murata, Keizo; Kaihatsu, Takayuki; Akutsu, Hiroki; Yamada, Jun-ichi

2011-12-14

Dependence of the superconducting transition temperature (T(c)) and critial superconducting pressure (P(c)) of the pressure-induced superconductor β-(BDA-TTP)(2)I(3) [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] on the orientation of uniaxial strain has been investigated. On the basis of the overlap between the upper and lower bands in the energy dispersion curve, the pressure orientation is thought to change the half-filled band to the quarter-filled one. The observed variations in T(c) and P(c) are explained by considering the degree of application of the pressure and the degree of contribution of the effective electronic correlation at uniaxial strains with different orientations parallel to the conducting donor layer. © 2011 American Chemical Society

Post-test analysis of ROSA-III experiment RUNs 705 and 706

International Nuclear Information System (INIS)

Koizumi, Yasuo; Soda, Kunihisa; Kikuchi, Osamu; Tasaka, Kanji; Shiba, Masayoshi

1980-07-01

The purpose of ROSA-III experiment with a scaled BWR Test facility is to examine primary coolant thermal-hydraulic behavior and performance of ECCS during a postulated loss-of-coolant accident of BWR. The results provide the information for verification and improvement of reactor safety analysis codes. RUNs 705 and 706 assumed a 200% double-ended break at the recirculation pump suction. RUN 705 was an isothermal blowdown test without initial power and initial core flow. In RUN 706 for an average core power and no ECCS, the main steam line and feed water line were isolated immediately on the break. Post-test analysis of RUNs 705 and 706 was made with computer code RELAP4J. The agreement in system pressure between calculation and experiment was satisfactory. However, the calculated heater rod surface temperature were significantly higher than the experimental ones. The calculated axial temperature profile was different in tendency from the experimental one. The calculated mixture level behavior in the core was different from the liquid void distribution observed in experiment. The rapid rise of fuel rod surface temperature was caused by the reduction of heat transfer coefficient attributed to the increase of quality. The need was indicated for improvement of analytical model of void distribution in the core, and also to performe a characteristic test of recirculation line under reverse flow and to examine the core inlet flow rate experimentally and analytically. (author)

Terahertz absorption and emission upon the photoionization of acceptors in uniaxially stressed silicon

Energy Technology Data Exchange (ETDEWEB)

Zhukavin, R. Kh., E-mail: zhur@ipmras.ru; Kovalevsky, K. A.; Orlov, M. L.; Tsyplenkov, V. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Hübers, H.-W. [DLR Institute of Optical Sensor Systems (Germany); Dessmann, N. [Humboldt University of Berlin, Institute of Physics (Germany); Kozlov, D. V.; Shastin, V. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2016-11-15

Experimental data on the spontaneous emission and absorption modulation in boron-doped silicon under CO{sub 2} laser excitation depending on the uniaxial stress applied along the [001] and [011] crystallographic directions are presented. Room-temperature radiation is used as the probe radiation. Low stress (less than 0.5 kbar) is shown to reduce losses in the terahertz region by 20%. The main contribution to absorption modulation at zero and low stress is made by A{sup +} centers. Intersubband free hole transitions additionally contribute to terahertz absorption at higher stress. These contributions can be minimized by compensation.

Multi-cracking in uniaxial and biaxial fatigue of 304L stainless steel

International Nuclear Information System (INIS)

Rupil, J.

2012-01-01

When a mechanical part is subjected to a repeated mechanical stress, it may be damaged after a number of cycles by several cracks initiation and propagation of a main crack. This is the phenomenon of fatigue damage. The thesis deals specifically with possible damage to some components of nuclear plants due to thermal fatigue. Unlike conventional mechanical fatigue damage where a main crack breaks the part, the thermal fatigue damage usually results in the appearance of a surface crack network. Two aspects are discussed in the thesis. The first is the experimental study of fatigue multiple cracking stage also called multi-cracking. Two mechanical test campaigns with multi-cracking detection by digital image correlation were conducted. These campaigns involve uniaxial and equi-biaxial mechanical loads in tension/compression without mean stress. This work allows to monitor and to observe the evolution of different networks of cracks through mechanical solicitations. The second is the numerical simulation of the phenomenon of fatigue damage. Several types of model are used (stochastic, probabilistic, cohesive finite elements). The experimental results have led to identify a multiple crack initiation law in fatigue which is faced with the numerical results. This comparison shows the relevance of the use of an analytical probabilistic model to find statistical results on the density of cracks that can be initiated with thermal and mechanical fatigue loadings. (author) [fr

Uniaxial strain effects on transport properties of a supramolecular organic conductor theta-(DIETS) sub 2 [Au(CN) sub 4

CERN Document Server

Tajima, N; Kato, R; Nishio, Y; Kajita, K

2003-01-01

Pressure-controlled switching between an insulating state and a superconducting state has been successfully realized on a supramolecular organic conductor theta-(DIETS) sub 2 [Au(CN) sub 4] [DIETS = diiodo(ethylenedithio)diselenadithiafulvalene]. Strong contact between iodine on the donor (DIETS) molecule and nitrogen on the anion [Au(CN) sub 4] genetates characteristic uniaxial strain effects on transport properties. Under the ambient pressure, the present system undergoes a semiconductor-insulator transition at 226 K. The effect of strains parallel to the conduction plane (ab-plane) is very small. Even under uniaxial strains up to 20 kbar along the a- and b-axis directions, the transition is not suppressed. Surprisingly, however, the c-axis strain induces a superconducting state with T sub c of 8.6 K at 10 kbar. Band parameter calculation and the conductivity anisotropy ratio suggest that an increase in the bandwidth W associated with a c-axis strain transforms the system to the metallic and superconducting...

Development of selective medium for IMP-type carbapenemase-producing Enterobacteriaceae in stool specimens.

Science.gov (United States)

Yamamoto, Norihisa; Kawahara, Ryuji; Akeda, Yukihiro; Shanmugakani, Rathina Kumar; Yoshida, Hisao; Hagiya, Hideharu; Hara, Naohiro; Nishi, Isao; Yukawa, Satomi; Asada, Rumiko; Sasaki, Yumi; Maeda, Kazuhiro; Sakamoto, Noriko; Hamada, Shigeyuki; Tomono, Kazunori

2017-03-24

Identification of carbapenemase-producing Enterobacteriaceae (CPE) in faecal specimens is challenging. This fact is particularly critical because low-level carbapenem-resistant organisms such as IMP-producing CPE are most prevalent in Japan. We developed a modified selective medium more suitable for IMP-type CPE. Fifteen reference CPE strains producing different types of β-lactamases were used to evaluate the commercially available CHROMagar KPC and chromID CARBA as well as the newly prepared MC-ECC medium (CHROMagar ECC supplemented with meropenem, cloxacillin, and ZnSO 4 ) and M-ECC medium (CHROMagar ECC supplemented with meropenem and ZnSO 4 ). A total of 1035 clinical samples were then examined to detect CPE using chromID CARBA and M-ECC medium. All tested strains producing NDM-, KPC-, and OXA-48-carbapenemases were successfully cultured in the media employed. Although most of the IMP-positive strains did not grow in CHROMagar KPC, chromID CARBA, or MC-ECC, all tested strains grew on M-ECC. When faecal samples were applied to the media, M-ECC medium allowed the best growth of IMP-type CPE with a significantly higher sensitivity (99.3%) than that of chromID CARBA (13.9%). M-ECC medium was determined as the most favourable selective medium for the detection of IMP-type CPE as well as other types of CPE.

Uniaxial in-plane magnetization of iron nanolayers grown within an amorphous matrix

Energy Technology Data Exchange (ETDEWEB)

Ghafari, M., E-mail: mohammad.ghafari@kit.edu; Hahn, H. [Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing 210094 (China); Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Mattheis, R. [Leibniz Institute for Photonic Technology IPHT, Jena (Germany); McCord, J. [Institute for Materials Science, Kiel University Kiel, Kaiserstraße 2, 24143 Kiel (Germany); Brand, R. A. [Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Macedo, W. A. A. [Laboratório de Física Aplicada, Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), 31270-901 Belo Horizonte, MG (Brazil)

2014-08-18

Conversion electron Mössbauer spectroscopy is used to determine the magnetic ground state at zero magnetic field of four-monolayer thick amorphous iron layers as part of a CoFeB-Fe multilayer stack. By comparing the intensities of the magnetic hyperfine field, an easy in-plane axis of the amorphous embedded Fe layer is verified, which is collinear to the uniaxial anisotropy axis of the neighboring amorphous CoFeB. Despite the soft magnetic character of the Fe layers, external fields up to 4 T perpendicular to the film plane are insufficient to completely align the embedded Fe moments parallel to the magnetic field due to a local disorder of the magnetic moments of the Fe atoms.

Band structure of Si/Ge core-shell nanowires along the [110] direction modulated by external uniaxial strain

International Nuclear Information System (INIS)

Peng Xihong; Tang Fu; Logan, Paul

2011-01-01

Strain modulated electronic properties of Si/Ge core-shell nanowires along the [110] direction were reported, on the basis of first principles density-functional theory calculations. In particular, the energy dispersion relationship of the conduction/valence band was explored in detail. At the Γ point, the energy levels of both bands are significantly altered by applied uniaxial strain, which results in an evident change of the band gap. In contrast, for the K vectors far away from Γ, the variation of the conduction/valence band with strain is much reduced. In addition, with a sufficient tensile strain (∼1%), the valence band edge shifts away from Γ, which indicates that the band gap of the Si/Ge core-shell nanowires experiences a transition from direct to indirect. Our studies further showed that effective masses of charge carriers can also be tuned using the external uniaxial strain. The effective mass of the hole increases dramatically with tensile strain, while strain shows a minimal effect on tuning the effective mass of the electron. Finally, the relation between strain and the conduction/valence band edge is discussed thoroughly in terms of site-projected wavefunction characters.

Room temperature lasing unraveled by a strong resonance between gain and parasitic absorption in uniaxially strained germanium

Science.gov (United States)

Gupta, Shashank; Nam, Donguk; Vuckovic, Jelena; Saraswat, Krishna

2018-04-01

A complementary metal-oxide semiconductor compatible on-chip light source is the holy grail of silicon photonics and has the potential to alleviate the key scaling issues arising due to electrical interconnects. Despite several theoretical predictions, a sustainable, room temperature laser from a group-IV material is yet to be demonstrated. In this work, we show that a particular loss mechanism, inter-valence-band absorption (IVBA), has been inadequately modeled until now and capturing its effect accurately as a function of strain is crucial to understanding light emission processes from uniaxially strained germanium (Ge). We present a detailed model of light emission in Ge that accurately models IVBA in the presence of strain and other factors such as polarization, doping, and carrier injection, thereby revising the road map toward a room temperature Ge laser. Strikingly, a special resonance between gain and loss mechanisms at 4%-5% 〈100 〉 uniaxial strain is found resulting in a high net gain of more than 400 cm-1 at room temperature. It is shown that achieving this resonance should be the goal of experimental work rather than pursuing a direct band gap Ge.

Uni-axial Elongational Viscosity of Linear and Branched polymer melts

DEFF Research Database (Denmark)

Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

2005-01-01

About 40 years ago interest in the measurement of elongational viscosity of polymer melts started to grow. Here we present measurements of transient (and steady) uni-axial elongational viscosity, using the FSR, of the following melts: Four narrow MMD polystyrene (PS) samples with weight......-average molar mass Mw in the range of 50k to 390k. Three different bi-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements.The measurements on the bi-disperse PS...... melts have demonstrated that both the transient and steady elongational viscosity is quite sensitive to polydispersity. Bi-disperse PS resembles the behaviour of mono-disperse melts only at elongational rates larger then the inverse of maximal time constant of the smallest molecule. As observed in Boger...

Uniaxial Compressive Strengths of Rocks Drilled at Gale Crater, Mars

Science.gov (United States)

Peters, G. H.; Carey, E. M.; Anderson, R. C.; Abbey, W. J.; Kinnett, R.; Watkins, J. A.; Schemel, M.; Lashore, M. O.; Chasek, M. D.; Green, W.; Beegle, L. W.; Vasavada, A. R.

2018-01-01

Measuring the physical properties of geological materials is important for understanding geologic history. Yet there has never been an instrument with the purpose of measuring mechanical properties of rocks sent to another planet. The Mars Science Laboratory (MSL) rover employs the Powder Acquisition Drill System (PADS), which provides direct mechanical interaction with Martian outcrops. While the objective of the drill system is not to make scientific measurements, the drill's performance is directly influenced by the mechanical properties of the rocks it drills into. We have developed a methodology that uses the drill to indicate the uniaxial compressive strengths of rocks through comparison with performance of an identically assembled drill system in terrestrial samples of comparable sedimentary class. During this investigation, we utilize engineering data collected on Mars to calculate the percussive energy needed to maintain a prescribed rate of penetration and correlate that to rock strength.

Stress relaxation of entangled polystyrene solution after constant-rate, uniaxial elongation

DEFF Research Database (Denmark)

Matsumiya, Yumi; Masubuchi, Yuichi; Watanabe, Hiroshi

For an entangled solution of linear polystyrene (PS 545k; M = 545k) in dibutyl phthalate (DBP), the stress relaxation after constant-rate uniaxial elongation was examined with an extensional viscosity fixture mounted on ARES (TA Instruments). The PS concentration, c = 52 wt%, was chosen in a way...... that the entanglement density M/Me of the solution coincided with that of PS 290k melt (M = 290k). After the elongation at the Rouse-based Weissenberg number Wi(R) ~ 3 up to the Hencky strain of 3, the short time stress relaxation of the solution was accelerated by a factor of ~4, which was less significant compared...... and the lack of monotonic thinning observed for the semidilute solutions. Results for less concentrated solutions will be also presented on site....

Forming limit diagram of aluminum AA6063 tubes at high temperatures by bulge tests

International Nuclear Information System (INIS)

Hashemi, Seyed Jalal; Naeini, Hassan Moslemi; Liaghat, Gholamhossein; Tafti, Rooholla Azizi; Rahmani, Farzad

2014-01-01

A free bulge test and ductile fracture criteria were used to obtain the forming limit diagrams (FLD) of aluminum alloy AA6063 tubes at high temperatures. Ductile fracture criteria were calibrated using the results of uniaxial tension tests at various elevated temperatures and different strain rates through adjusting the Zener-Holloman parameter. High temperature free bulge test of tubes was simulated in finite element software Abaqus, and tube bursting was predicted using ductile fracture criteria under different loading paths. FLDs which were obtained from finite element simulation were compared to experimental results to select the most accurate criterion for prediction of forming limit diagram. According to the results, all studied ductile fracture criteria predict similarly when forming condition is close to the uniaxial tension, while Ayada criterion predicts the FLD at 473 K and 573 K very well.

Forming limit diagram of aluminum AA6063 tubes at high temperatures by bulge tests

Energy Technology Data Exchange (ETDEWEB)

Hashemi, Seyed Jalal; Naeini, Hassan Moslemi; Liaghat, Gholamhossein [Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Tafti, Rooholla Azizi [Yazd University, Yazd (Iran, Islamic Republic of); Rahmani, Farzad [Kar Higher Education Institute, Qazvin (Iran, Islamic Republic of)

2014-11-15

A free bulge test and ductile fracture criteria were used to obtain the forming limit diagrams (FLD) of aluminum alloy AA6063 tubes at high temperatures. Ductile fracture criteria were calibrated using the results of uniaxial tension tests at various elevated temperatures and different strain rates through adjusting the Zener-Holloman parameter. High temperature free bulge test of tubes was simulated in finite element software Abaqus, and tube bursting was predicted using ductile fracture criteria under different loading paths. FLDs which were obtained from finite element simulation were compared to experimental results to select the most accurate criterion for prediction of forming limit diagram. According to the results, all studied ductile fracture criteria predict similarly when forming condition is close to the uniaxial tension, while Ayada criterion predicts the FLD at 473 K and 573 K very well.

Influence of water-soaking time on the acoustic emission characteristics and spatial fractal dimensions of coal under uniaxial compression

Directory of Open Access Journals (Sweden)

Jia Zheqiang

2017-01-01

Full Text Available The water-soaking time affects the physical and mechanical properties of coals, and the temporal and spatial evolution of acoustic emissions reflects the fracture damage process of rock. This study conducted uniaxial compression acoustic emissions tests of coal samples with different water-soaking times to investigate the influence of water-soaking time on the acoustic emissions characteristics and spatial fractal dimensions during the deformation and failure process of coals. The results demonstrate that the acoustic emissions characteristics decrease with increases in the water-soaking time. The acoustic emissions spatial fractal dimension changes from a single dimensionality reduction model to a fluctuation dimensionality reduction model, and the stress level of the initial descending point of the fractal dimension increases. With increases in the water-soaking time, the destruction of coal transitions from continuous intense failure throughout the process to a lower release of energy concentrated near the peak strength.

Textile properties of synthetic prolapse mesh in response to uniaxial loading

Science.gov (United States)

Barone, William R.; Moalli, Pamela A.; Abramowitch, Steven D.

2016-01-01

BACKGROUND Although synthetic mesh is associated with superior anatomic outcomes for the repair of pelvic organ prolapse, the benefits of mesh have been questioned because of the relatively high complication rates. To date, the mechanisms that result in such complications are poorly understood, yet the textile characteristics of mesh products are believed to play an important role. Interestingly, the pore diameter of synthetic mesh has been shown to impact the host response after hernia repair greatly, and such findings have served as design criteria for prolapse meshes, with larger pores viewed as more favorable. Although pore size and porosity are well-characterized before implantation, the changes in these textile properties after implantation are unclear; the application of mechanical forces has the potential to greatly alter pore geometries in vivo. Understanding the impact of mechanical loading on the textile properties of mesh is essential for the development of more effective devices for prolapse repair. OBJECTIVE The objective of this study was to determine the effect of tensile loading and pore orientation on mesh porosity and pore dimensions. STUDY DESIGN In this study, the porosity and pore diameter of 4 currently available prolapse meshes were examined in response to uniaxial tensile loads of 0.1, 5, and 10 N while mimicking clinical loading conditions. The textile properties were compared with those observed for the unloaded mesh. Meshes included Gynemesh PS (Ethicon, Somerville, NJ), UltraPro (Artisyn; Ethicon), Restorelle (Coloplast, Minneapolis, MN), and Alyte Y-mesh (Bard, Covington, GA). In addition to the various pore geometries, 3 orientations of Restorelle (0-, 5-, 45-degree offset) and 2 orientations of UltraPro (0-, 90-degree offset) were examined. RESULTS In response to uniaxial loading, both porosity and pore diameter dramatically decreased for most mesh products. The application of 5 N led to reductions in porosity for nearly all groups

UPTF/TEST10B/RUN081, Steam/Water Flow Phenomena Reflood PWR Cold Leg Break LOCA

International Nuclear Information System (INIS)

1998-01-01

1 - Description of test facility: The Upper Plenum Test Facility (UPTF) is a geometrical full-scale simulation of the primary system of the four-loop 1300 MWe Siemens/KWU pressurized water reactor (PWR) at Grafenrheinfeld. The test vessel, upper plenum and its internals, downcomer, primary loops, pressurizer and surge line are replicas of the reference plant. The core, coolant pumps, steam generators and containment of a PWR are replaced by simulators which simulate the boundary and initial conditions during end-of-blowdown, refill and reflood phase following a loss-of-coolant accident (LOCA) with a hot or cold leg break. The break size and location can be simulated in the broken loop. The emergency core coolant (ECC) injection systems at the UPTF are designed to simulate the various ECC injection modes, such as hot leg, upper plenum, cold leg, downcomer or combined hot and cold leg injection of different ECC systems of German and US/Japan PWRs. Moreover, eight vent valves are mounted in the core barrel above the hot leg nozzle elevation for simulation of ABB and B and W PWRs. The UPTF primary system is divided into the investigation and simulation areas. The investigation areas, which are the exact replicas of a GPWR, consist of the upper plenum with internals, hot legs, cold legs and downcomer. The realistic thermal-hydraulic behavior in the investigation areas is assured by appropriate initial and boundary conditions of the area interface. The boundary conditions are realized by above mentioned simulators, the setup and the operation of which are based on small-scale data and mathematical models. The simulation areas include core simulator, steam generator simulators, pump simulators and containment simulator. The steam production and entrainment in a real core during a LOCA are simulated by steam and water injection through the core simulator. 2 - Description of test: Investigation of steam/water flow phenomena at the upper tie plate and in the upper plenum and

Effect of combined external uniaxial stress and dc bias on the dielectric property of BaTiO3-based dielectrics in multilayer ceramic capacitor: thermodynamics and experiments

International Nuclear Information System (INIS)

Yang Gang; Yue Zhenxing; Sun Tieyu; Gou Huanlin; Li Longtu

2008-01-01

The dielectric properties of (Nb, Y)-doped BaTiO 3 in a multilayer ceramic capacitor (MLCC) under combined external uniaxial compressive stress and dc bias field were investigated at room temperature by using a modified Ginsburg-Landau-Devonshire thermodynamic theory and the dielectric measurement. It is found that although dc bias decreases the dielectric properties dominantly, the influence of the external uniaixial compressive stress should not be neglected. When applied along a direction perpendicular to the internal electrode layer in the MLCC, the external uniaixal compressive stress will strengthen the negative effect of dc bias. In contrast, the external uniaxial compressive stress along a direction parallel to the internal electrode layer in the MLCC will increase the dielectric permittivity under dc bias field, i.e. improve the ε-V response of the MLCC. Furthermore, although there is a difference between the calculated permittivity and the measured permittivity, the effects of the combined external uniaxial compressive stress and dc bias field on the dielectric permittivity described through two approaches are in good agreement

Comparison of Candida species isolated from children with and without early childhood caries: A descriptive cross-sectional study

Directory of Open Access Journals (Sweden)

M S Beena

2017-01-01

Full Text Available Background: Early childhood caries (ECC is characterized by the presence of one or more decayed, missing (due to caries, or filled teeth surfaces in any primary tooth, in a child below 6 years of age. Although ECC is primarily associated with high levels of maternal Streptococcus mutans, there has been an increased interest in finding the relationship between oral fungal flora and dental caries. Objective: The aim of the study is to identify and characterize the Candida species and to compare the candidal isolates in children with ECC and without ECC. Materials and Methods: The study was conducted on children below 6 years of age, who were categorized into ECC and non-ECC groups of fifty children each. Samples were collected using sterile cotton swabs and were inoculated on Sabouraud's Dextrose Agar and incubated at 37°C for 24 h. Candidal colonies were isolated, species identified and virulence factors tested for both ECC and non-ECC groups. Results: The candidal carriage among the ECC children was found to be 84%, which was significantly higher than the non-ECC group of 24%. Candida albicans and non-albicans Candida (NAC were isolated in both ECC and non-ECC groups. Phospholipase production was significantly high in ECC group whereas hemolysin production and germ tube formation showed no significant difference between the two groups. Conclusion: A significant correlation was found between the presence of Candida and ECC. NAC also plays an important role in the development of ECC. The virulence factors such as phospholipase may be responsible for the pathogenicity of Candida in the development of ECC.

Uniaxial Compressive Strength and Fracture Mode of Lake Ice at Moderate Strain Rates Based on a Digital Speckle Correlation Method for Deformation Measurement

Directory of Open Access Journals (Sweden)

Jijian Lian

2017-05-01

Full Text Available Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range of 0.4–10 s−1 at −5 °C and −10 °C. The digital speckle correlation method (DSCM is used for deformation measurement through constructing artificial speckle on ice sample surface in advance, and two dynamic load cells are employed to measure the dynamic load for monitoring the equilibrium of two ends’ forces under high-speed loading. The relationships between uniaxial compressive strength and strain-rate, temperature, loading direction, and air porosity are investigated, and the fracture mode of ice at moderate rates is also discussed. The experimental results show that there exists a significant difference between true strain-rate and nominal strain-rate derived from actuator displacement under dynamic loading conditions. Over the employed strain-rate range, the dynamic uniaxial compressive strength of lake ice shows positive strain-rate sensitivity and decreases with increasing temperature. Ice obtains greater strength values when it is with lower air porosity and loaded vertically. The fracture mode of ice seems to be a combination of splitting failure and crushing failure.

Performance enhancement in uniaxially tensile stressed GeSn n-channel fin tunneling field-effect transistor: Impact of stress direction

Science.gov (United States)

Wang, Hongjuan; Han, Genquan; Jiang, Xiangwei; Liu, Yan; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

2017-04-01

In this work, the boosting effect on the performance of GeSn n-channel fin tunneling FET (nFinTFET) enabled by uniaxial tensile stress is investigated theoretically. As the fin rotates within the (001) plane, the uniaxial tensile stress is always along its direction. The electrical characteristics of tensile-stressed GeSn nFinTFETs with point and line tunneling modes are computed utilizing the technology computer aided design (TCAD) simulator in which the dynamic nonlocal band-to-band tunneling (BTBT) algorithm is employed. In comparison with the relaxed devices, tensile-stressed GeSn nFinTFETs achieve a substantial enhancement in band-to-band tunneling generation rate (G BTBT) and on-state current I ON owing to the reduced bandgap E G induced by the tensile stress. Performance improvement of GeSn nFinTFETs induced by tensile stress demonstrates a strong dependence on channel direction and tunneling modes. Under the same magnitude of stress, line-nFinTFETs obtain a more pronounced I ON enhancement over the transistors with point tunneling mode.

Electroluminescence in quantum well heterostructures p-Al{sub x}Ga{sub 1-x}As/GaAs{sub 1-y}P{sub y}/n-Al{sub x}Ga{sub 1-x}As under uniaxial stress

Energy Technology Data Exchange (ETDEWEB)

Berman, Irina V. [Physics Department, San Jose State University, CA (United States); Bogdanov, Evgeniy V.; Minina, Natalia Ya.; Shirokov, Stanislav S.; Yunovich, Alexander E. [Physics Department, Lomonosov Moscow State University (Russian Federation); Kissel, Heiko [R and D Department, DILAS Diodenlaser GmbH, (Germany)

2009-03-15

We present new results on the influence of uniaxial stress up to P=4 kbar on the electroluminescence spectra and current-voltage characteristics of p-Al{sub x}Ga{sub 1-x}As/GaAs{sub 1-y}P{sub y}/n-Al{sub x}Ga{sub 1-x}As double heterostructures usually used in TM emitting 808 nm high-power diode lasers. With increasing stress, the emission spectra demonstrate a blue shift of up to 25 meV at a pressure of P=4 kbar, while the electroluminescence intensity increases under compression. The different behavior of the current-voltage characteristics under uniaxial stress along[110] and[1 anti 10] directions is mainly determined by the arising piezoelectric field. The results are also discussed in terms of changes in the band structure under uniaxial compression. The construction of the cryostat for optical measurements under uniaxial stress at liquid nitrogen temperature is described in the paper. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Utilization of Local Ingredients for the Production of High-Early-Strength Engineered Cementitious Composites

Directory of Open Access Journals (Sweden)

Hanwen Deng

2018-01-01

Full Text Available The rapid repair and retrofitting of existing transportation infrastructure requires dimensional stability and ductile repair material that can obtain sufficiently high strength in a few hours to accommodate the large loading and deformation at an early age. Engineering cementitious composites (ECCs is a class representative of the new generation of high-performance fiber-reinforced cement-based composites (HPFRCC with medium fiber content. The unique properties of tremendous ductility and tight multiple crack behavior indicate that ECC can be used as an effective retrofit material. The wide application of this material in China will require the use of all local ingredients. In this study, based on Chinese domestic ingredients, including matrix materials and all fibers, high-early-strength ECC (HES-ECC was designed under the guidance of strain-hardening criterion of ECC. The matrix properties and fiber/matrix interfacial micromechanics properties were obtained from three-point-bending test and single-fiber pullout test. The mechanical properties of HES-ECC were achieved by direct tensile test. The experimental results show that HES-ECC was successfully developed by using all Chinese materials. When using the domestic PVA fiber at 2%, the strength requirement can be achieved but only a low ductility. When using the domestic PE fiber at 0.8%, the strength and deformation requirement both can be obtained. The HES-ECC developed in this study exhibited compressive strength of more than 25 MPa within 6 hours, and an ultimate tensile strength of 5-6 MPa and tensile strain capacity of 3-4% after 60 days. Moreover, the cost of using domestic fiber can be largely reduced compared with using imported fiber, up to 70%; it is beneficial to the promotion of these high-early-strength ECCs in the Chinese market.

Study on infrasonic characteristics of coal samples in failure process under uniaxial loading

Directory of Open Access Journals (Sweden)

Bing Jia

Full Text Available To study the precursory failure infrasonic characteristics of coal samples, coal rock stress loading system and infrasonic wave acquisition system were adopted, and infrasonic tests in uniaxial loading process were made for the coal samples in the studied area. Wavelet filtering, fast Fourier transform, and relative infrasonic energy methods were used to analyze the characteristics of the infrasonic waves in the loading process, including time domain characteristics, and relative energy. The analysis results demonstrated that the frequencies of the infrasonic signals in the loading process mainly distribute within 5–10 Hz, which are significantly different from noise signals. The changes of the infrasonic signals show clear periodic characters in time domain. Meanwhile, the relative energy changes of the infrasonic wave also show periodic characters, which are divided into two stages by the yield limit of coal samples, and are clear and easy to be recognized, so that they can be used as the precursory characteristics for recognizing coal sample failures. Moreover, the infrasonic waves generated by coal samples have low frequency and low attenuation, which can be collected without coupling and transmitted in long distance. This study provides an important support for the further in-situ prediction of coal rock failures. Keywords: Infrasound, Relative energy, Time-frequency analysis, Failure prediction, Identification feature

Dislocation based controlling of kinematic hardening contribution to simulate primary and secondary stages of uniaxial ratcheting

Science.gov (United States)

Bhattacharjee, S.; Dhar, S.; Acharyya, S. K.

2017-07-01

The primary and secondary stages of the uniaxial ratcheting curve for the C-Mn steel SA333 have been investigated. Stress controlled uniaxial ratcheting experiments were conducted with different mean stresses and stress amplitudes to obtain curves showing the evolution of ratcheting strain with number of cycles. In stage-I of the ratcheting curve, a large accumulation of ratcheting strain occurs, but at a decreasing rate. In contrast, in stage-II a smaller accumulation of ratcheting strain is found and the ratcheting rate becomes almost constant. Transmission electron microscope observations reveal that no specific dislocation structures are developed during the early stages of ratcheting. Rather, compared with the case of low cycle fatigue, it is observed that sub-cell formation is delayed in the case of ratcheting. The increase in dislocation density as a result of the ratcheting strain is obtained using the Orowan equation. The ratcheting strain is obtained from the shift of the plastic strain memory surface. The dislocation rearrangement is incorporated in a functional form of dislocation density, which is used to calibrate the parameters of a kinematic hardening law. The observations are formulated in a material model, plugged into the ABAQUS finite element (FE) platform as a user material subroutine. Finally the FE-simulated ratcheting curves are compared with the experimental curves.

Cracking and Failure in Rock Specimen Containing Combined Flaw and Hole under Uniaxial Compression

Directory of Open Access Journals (Sweden)

Xiang Fan

2018-01-01

Full Text Available Flaw is a key factor influencing failure behavior of a fractured specimen. In the present study, rectangular-flawed specimens were prepared using sandstone to investigate the effect of flaw on failure behavior of rock. Open flaw and cylindrical hole were simultaneously precut within rock specimens using high-pressure water jet cutting technology. Five series of specimens including intact, single-hole-alone, two-hole-alone, single-hole and two-flaw, and two-hole and single-flaw blocks were prepared. Uniaxial compressive tests using a rigid servo control instrument were carried out to investigate the fracture processes of these flawed specimens. It is observed that during loading, internal stress always intensively distributed at both sidewalls of open hole, especially at midpoint of sidewalls, so rock crumb flaking was firstly observed among all sandstone specimens containing single hole or two holes. Cracking around open hole is associated with the flaw inclination angle which was observed in Series III and V. Crack easily initiated at the tips of flaw with inclination angles of 0°, 30°, and 60° but hard for 90° in Series III and V. Rock burst was the major failure mode among most tested specimens, which generally induced new cracks and finally created crater shape. Additionally, due to extrusion between blocks, new shear or tensile cracks were generated and the rock specimen surface spalled. Eventually, four typical failure processes including rock crumb flaking, crack initiation and propagation, rock burst, and second rupture, were summarized.

Effect of Strength Coefficient of Bainite on Micromechanical Deformation and Failure Behaviors of Hot-Rolled 590FB Steel during Uniaxial Tension

Energy Technology Data Exchange (ETDEWEB)

Kim, Eun-Young; Choi, Shi-Hoon [Sunchon National University, Suncheon (Korea, Republic of); Kim, Sung Il [POSCO Technical Research Laboratories, Gwangyang (Korea, Republic of)

2016-11-15

The effect of the strength coefficient (K{sub B}) of bainite on micromechanical deformation and failure behaviors of a hot-rolled 590MPa steel (590FB) during uniaxial tension was simulated using the elasto-plastic finite element method (FEM). The spatial distribution of the constituent phases was obtained using a phase identification technique based on optical microstructure. Empirical equations which depend on chemical composition were used to determine the stress-strain relationship of the constituent phases of the 590FB steel. The stress-strain partitioning and failure behavior were analyzed by increasing the K{sub B} of bainite. The elasto-plastic FEM results revealed that effective strain in the ferrite-bainite boundaries, and maximum principal stress in fibrous bainite, were enhanced as the K{sub B} increased. The elasto-plastic FEM results also demonstrated that the K{sub B} significantly affects the micromechanical deformation and failure behaviors of the hot-rolled 590FB steel during uniaxial tension.

Application of Geostatistical Modelling to Study the Exploration Adequacy of Uniaxial Compressive Strength of Intact Rock alongthe Behesht-Abad Tunnel Route

Directory of Open Access Journals (Sweden)

Mohammad Doustmohammadi

2014-12-01

Full Text Available Uniaxial compressive strength (UCS is one of the most significant factors on the stability of underground excavation projects. Most of the time, this factor can be obtained by exploratory boreholes evaluation. Due to the large distance between exploratory boreholes in the majority of geotechnical projects, the application of geostatistical methods has increased as an estimator of rock mass properties. The present paper ties the estimation of UCS values of intact rock to the distance between boreholes of the Behesht-Abad tunnel in central Iran, using SGEMS geostatistical program. Variography showed that UCS estimation of intact rock using geostatistical methods is reasonable. The model establishment and validation was done after assessment that the model was trustworthy. Cross validation proved the high accuracy (98% and reliability of the model to estimate uniaxial compressive strength. The UCS values were then estimated along the tunnel axis. Moreover, using geostatistical estimation led to better identification of the pros and cons of geotechnical explorations in each location of tunnel route.

In situ synchrotron X-ray diffraction of ferroelastic La0.8Ca0.2CoO3 ceramics during uniaxial compression

International Nuclear Information System (INIS)

Vullum, Per Erik; Mastin, Johann; Wright, Jonathan; Einarsrud, Mari-Ann; Holmestad, Randi; Grande, Tor

2006-01-01

Uniaxial compression of rhombohedral La 0.8 Ca 0.2 CoO 3 ceramics has been studied in situ using synchrotron X-ray diffraction. The intensities of Bragg reflections parallel and perpendicular to the stress field were simultaneously detected as a function of the stress. Reorientation of ferroelastic domains due to the uniaxial stress was demonstrated. With increasing stress the volume fraction of domains with the hexagonal c-axis parallel to the stress axis increased at the expense of domains with the c-axis perpendicular to the stress axis. The strain in the polycrystalline materials evolved unevenly with increasing stress due to crystallographic anisotropy. In energetically favourable domains with the c-axis parallel to the stress axis, the rhombohedral distortion from cubic symmetry increased, while the crystal structure became closer to cubic in domains with the c-axis perpendicular to the stress. Successive compression/decompression cycles to higher maximum stress resulted in a higher volume fraction of reoriented domains both at maximum stress and after decompression

Final report on in-reactor uniaxial tensile deformation of pure iron and Fe-Cr alloy

International Nuclear Information System (INIS)

Singh, B.N.; Xiaoxu Huang; Taehtinen, S.; Moilamen, P.; Jacquet, P.; Dekeyser, J.

2007-11-01

Traditionally, the effect of irradiation on mechanical properties of metals and alloys is determined using post-irradiation tests carried out on pre-irradiated specimens and in the absence of irradiation environment. The results of these tests may not be representative of deformation behaviour of materials used in the structural components of a fission or fusion reactor where the materials will be exposed concurrently to displacement damage and external and/or internal stresses. In an effort to evaluate and understand the dynamic response of materials under these conditions, we have recently performed a series of uniaxial tensile tests on Fe-Cr and pure iron specimens in the BR-2 reactor at Mol (Belgium). The present report first provides a brief description of the test facilities and the procedure used for performing the in-reactor tests. The results on the mechanical response of materials during these tests are presented in the form of stress-displacement dose and the conventional stress-strain curves. For comparison, the results of post-irradiation tests and tests carried out on unirradiated specimens are also presented. Results of microstructural investigations on the unirradiated and deformed, irradiated and undeformed, post-irradiation deformed and the in-reactor deformed specimens are also described. During the in-reactor tests the specimens of both Fe-Cr alloy and pure iron deform in a homogeneous manner and do not exhibit the phenomenon of yield drop. An increase in the pre-yield dose increases the yield stress but not the level of maximum flow stress during the in-reactor deformation of Fe-Cr alloy. Neither the in-reactor nor the post-irradiation deformed specimens of Fe-Cr alloy and pure iron showed any evidence of cleared channel formation. Both in Fe-Cr and pure iron, the in-reactor deformation leads to accumulation of dislocations in a homogeneous fashion and only to a modest density. No dislocation cells are formed during the in-reactor or post

Development and Testing of a Smartphone Application Prototype for Oral Health Promotion.

Science.gov (United States)

Nolen, Sara L; Giblin-Scanlon, Lori J; Boyd, Linda D; Rainchuso, Lori

2018-04-01

Purpose: The purpose of this study was to develop and test a smartphone application (app) prototype, ToothSense, as an oral health promotion tool for the prevention of Early Childhood Caries (ECC) based on the Theory of Planned Behavior (TPB). Methods: A quantitative and qualitative design process based on the TPB was used for the app development in the first phase of the study. A behavioral intervention technologic model was used to document the app features design, accounting for Doshi's intervention strategies for the TPB. Beta-testing of the app was hosted via an online software program. Testers were presented with a series of tasks and prompts followed by a 5-point Likert-scale questionnaire that quantitatively measured perceptions of the app's interactive design based on Jakob Nielsen's principles and behavioral strategies. A Net Promotor Score was calculated to determine the tester's likelihood to recommend the app prototype. Audio and video aspects of the app were qualitatively measured using a template approach. Results: Beta testers agreed the app met the majority of the five usability statements. The Net Promotor Score indicated a likelihood to recommend the app prototype. Thematic analyses revealed the following themes: interface design, navigation, terminology, information, and oral health promotion. Conclusion: Beta testing results from this study provided health promotion project design information for the prevention of ECC using the TPB and highlighted the importance and usability of smartphone app for oral health promotion. Copyright © 2018 The American Dental Hygienists’ Association.

Uniaxial low cycle fatigue behavior for pre-corroded 16MND5 bainitic steel in simulated pressurized water reactor environment

Science.gov (United States)

Chen, Xu; Ren, Bin; Yu, Dunji; Xu, Bin; Zhang, Zhe; Chen, Gang

2018-06-01

The effects of uniaxial tension properties and low cycle fatigue behavior of 16MND5 bainitic steel cylinder pre-corroded in simulated pressurized water reactor (PWR) were investigated by fatigue at room temperature in air and immersion test system, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS). The experimental results indicated that the corrosion fatigue lives of 16MND5 specimen were significantly affected by the strain amplitude and simulated PWR environments. The compositions of corrosion products were complexly formed in simulated PWR environments. The porous corrosion surface of pre-corroded materials tended to generate pits as a result of promoting contact area to the fresh metal, which promoted crack initiation. For original materials, the fatigue cracks initiated at inclusions imbedded in the micro-cracks. Moreover, the simulated PWR environments degraded the mechanical properties and low cycle fatigue behavior of 16MND5 specimens remarkably. Pre-corrosion of 16MND5 specimen mainly affected the plastic term of the Coffin-Manson equation.

Development of evaluation technique of high temperature creep characteristics by small punch-creep test method (I)

International Nuclear Information System (INIS)

Baek, Seung Se; Na, Sung Hun; Yu, Hyo Sun; Na, Eui Gyun

2001-01-01

In this study, a Small Punch Creep(SP-Creep) test using miniaturized specimen(10 x 10 x 0.5mm) is described to develop the new creep test method for high temperature structural materials. The SP-Creep test is applied to 2.25Cr-1Mo(STBA24) steel which is widely used as boiler tube material. The test temperatures applied for the creep deformation of miniaturized specimens are between 550∼600 .deg. C. The SP-Creep curves depend definitely on applied load and creep temperature, and show the three stages of creep behavior like in conventional uniaxial tensile creep curves. The load exponent of miniaturized specimen decrease with increasing test temperature, and its behavior is similar to stress exponent behavior of uniaxial creep test. The creep activation energy obtained from the relationship between SP-Creep rate and test temperature decreases as the applied load increases. A predicting equation of SP-Creep rate for 2.25Cr-1Mo steel is suggested, and a good agreement between experimental and calculated data has been found

Testing Bonds Between Brittle And Ductile Films

Science.gov (United States)

Wheeler, Donald R.; Ohsaki, Hiroyuki

1989-01-01

Simple uniaxial strain test devised to measure intrinsic shear strength. Brittle film deposited on ductile stubstrate film, and combination stretched until brittle film cracks, then separates from substrate. Dimensions of cracked segments related in known way to tensile strength of brittle film and shear strength of bond between two films. Despite approximations and limitations of technique, tests show it yields semiquantitative measures of bond strengths, independent of mechanical properties of substrates, with results reproducible with plus or minus 6 percent.

Phase transitions in random uniaxial systems with dipolar interactions

International Nuclear Information System (INIS)

Schuster, H.G.

1977-01-01

The critical behaviour of random uniaxial ferromagnetic (ferroelectric) systems with both short range and long range dipolar interactions is investigated, using the field theoretic renormalization method of Brezin et al. for the free energy above and below transition point Tsub(c). The randomness is due to externally introduced fluctuations in the short range interactions (quenched case) or (and) magneto-elastic coupling to the lattice (annealed case). Strong deviations in the critical behaviour with respect to the pure systems are found. In the quenched case, e.g., the specific heat C and the coefficient f 2 (of M 3 in the equation of state, where M is the magnetization) change from C proportional to abs ln abs t abs abssup(1/3), f 2 proportional to abs ln abs t abs abs sup(1/3), f 2 proportional to abs ln abs t abs abs -1 in the pure system to C = A+- + C+-exp[-4√ 3 106 abs ln abs t abs abs], f 2 proportional to abs ln abs t abs abs sup(-1/2) (where t = (T-Tsub(c)) / Tsub(c) is the reduced temperature and A+-, C+- are constants) in the random situation. (orig.) [de

Uniaxial alignment of triisopropylsilylethynyl pentacene via zone-casting technique.

Science.gov (United States)

Su, Yajun; Gao, Xiang; Liu, Jiangang; Xing, Rubo; Han, Yanchun

2013-09-14

Uniaxially aligned triisopropylsilylethynyl pentacene (TIPS-pentacene) crystals over a large area were fabricated using zone-casting technique. The array of TIPS-pentacene displayed a high orientation degree with a dichroic ratio (DR) of 0.80. The crystals were arranged with c axis perpendicular to the substrate and the long axis of the ribbon corresponded to the a axis of TIPS-pentacene. The properties of the solutions and the processing parameters were shown to influence the formation of the oriented TIPS-pentacene crystalline array. Solvent with a low boiling point (such as chloroform) favoured the orientation of the ribbon-like crystals. The concentration of the solution should be appropriate, ensuring the crystallization velocity of TIPS-pentacene matching with the receding of the meniscus. Besides, we proved that the casting speed should be large enough to induce a sufficient concentration gradient. The orientation mechanism of TIPS-pentacene was attributed to a synergy of the ordered nuclei and a match between the crystallization velocity and the casting speed. Field effect transistors (FETs) based on the oriented TIPS-pentacene crystalline array showed a mobility of 0.67 cm(2) V(-1) s(-1).

UPTF-TRAM experiments for SBLOCA: Evaluation of condensation processes in TRAM tests A6 and A7

Energy Technology Data Exchange (ETDEWEB)

Sonneburg, H.G.; Tuunanen, J.; Palazov, V.V. [Gesellschaft fuer Anlagen-und Reaktorsicherheit (GRS), Muenchen (Germany)

1995-09-01

The investigation of thermal-hydraulic phenomena related to reactor transients with accident management measures is the goal of the TRansient and accident Management (TRAM) experimental programme being carried out at the Upper Plenum Test Facility (UPTF) at Mannheim (Germany). These experimental investigations and test analyses are funded by the German Federal Minister for Research and Technology (BMFT). The UPTF simulates these phenomena in a 1:1 such relative to the dimension of a PWR. Condensation of steam during Emergency Core Cooling (ECC) water injection from accumulators into the primary system is one of the phenomena studied within the accumulators into the primary system is one of the phenomena studied within the TRAM programme. This phenomenon partly controls the efficiency of accumulator injection if the high pressure safety systems fail. Beside this, the condensation within the nitrogen inside the accumulator for a certain period controls the pressure development inside the accumulator. Thus, both condensation phenomena determine the ECC flow rate delivered to the primary system. Concerning the condensation inside the primary system, this is also of safety relevance in the case of Pressurized Thermal Shock (PTS) during cold leg injection.

Atomic force microscopy and mechanical testing of bovine pericardium irradiated to radiotherapy doses

International Nuclear Information System (INIS)

Daar, Eman; Kaabar, W.; Woods, E.; Lei, C.; Nisbet, A.; Bradley, D.A.

2014-01-01

Within the context of radiotherapy our work investigates the feasibility of identifying changes in structural and biomechanical properties of pericardium resulting from exposure to penetrating photon irradiation. Collagen fibres extracted from bovine pericardium were chosen as a model of pericardium extracellular matrix as these form the main fibrous component of the medium. Tests of mechanical properties, controlled by the various structural elements of the tissues, were performed on frontal pericardium, including uni-axial tests and atomic force microscopy (AFM). While the irradiated collagen fibres showed no significant change in D-band spacing up to doses of 80 Gy, the fibre width was found to increase by 34±9% at 80 Gy when compared with that for un-irradiated samples. - Highlights: • Methods for identifying changes in tissue biophysical properties following photon irradiation. • Tests made using collagen fibres extracted from bovine pericardium. • Sensitivity of uni-axial tests and atomic force microscopy (AFM) investigated. • Radiotherapy doses investigated up to 80 Gy, delivered by 6 MV photons

Characterization of mechanical behavior of a porcine pulmonary artery strip using a randomized uniaxial stretch and stretch-rate protocol

Directory of Open Access Journals (Sweden)

Criscione John C

2008-01-01

Full Text Available Abstract Background Much of the experimental work in soft tissue mechanics has been focused on fitting approximate relations for specific tissue types from aggregate data on multiple samples of the tissue. Such relations are needed for modeling applications and have reasonable predictability – especially given the natural variance in specimens. There is, however, much theoretical and experimental work to be done in determining constitutive behaviors for particular specimens and tissues. In so doing, it may be possible to exploit the natural variation in tissue ultrastructure – so to relate ultrastructure composition to tissue behavior. Thus, this study focuses on an experimental method for determining constitutive behaviors and illustrates the method with analysis of a porcine pulmonary artery strip. The method characterizes the elastic part of the response (implicitly in terms of stretch and the inelastic part in terms of short term stretch history (i.e., stretch-rate Ht2, longer term stretch history Ht1, and time since the start of testing T. Methods A uniaxial testing protocol with a random stretch and random stretch-rate was developed. The average stress at a particular stretch was chosen as the hyperelastic stress response, and deviation from the mean at this particular stretch is chosen as the inelastic deviation. Multivariable Linear Regression Analysis (MLRA was utilized to verify if Ht2, Ht1, and T are important factors for characterizing the inelastic deviation. For acquiring Ht2 and Ht1, an integral function type of stretch history was employed with time constants chosen from the relaxation spectrum of an identical size strip from the same tissue with the same orientation. Finally, statistical models that characterize the inelasticity were developed at various, nominal values of stretch, and their predictive capability was examined. Results Inelastic deviation from hyperelasticity was high (31% for low stretch and declined

Extrachromosomal circles of satellite repeats and 5S ribosomal DNA in human cells

Directory of Open Access Journals (Sweden)

Cohen Sarit

2010-03-01

Full Text Available Abstract Background Extrachomosomal circular DNA (eccDNA is ubiquitous in eukaryotic organisms and was detected in every organism tested, including in humans. A two-dimensional gel electrophoresis facilitates the detection of eccDNA in preparations of genomic DNA. Using this technique we have previously demonstrated that most of eccDNA consists of exact multiples of chromosomal tandemly repeated DNA, including both coding genes and satellite DNA. Results Here we report the occurrence of eccDNA in every tested human cell line. It has heterogeneous mass ranging from less than 2 kb to over 20 kb. We describe eccDNA homologous to human alpha satellite and the SstI mega satellite. Moreover, we show, for the first time, circular multimers of the human 5S ribosomal DNA (rDNA, similar to previous findings in Drosophila and plants. We further demonstrate structures that correspond to intermediates of rolling circle replication, which emerge from the circular multimers of 5S rDNA and SstI satellite. Conclusions These findings, and previous reports, support the general notion that every chromosomal tandem repeat is prone to generate eccDNA in eukryoric organisms including humans. They suggest the possible involvement of eccDNA in the length variability observed in arrays of tandem repeats. The implications of eccDNA on genome biology may include mechanisms of centromere evolution, concerted evolution and homogenization of tandem repeats and genomic plasticity.

Ice-sheet flow conditions deduced from mechanical tests of ice core

DEFF Research Database (Denmark)

Miyamoto, Atsushi; Narita, Hideki; Hondoh, Takeo

1999-01-01

Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate....... It was revealed that cloudy bands affect ice-deformation processes, but the details remain unclear. Udgivelsesdato: June......Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate......-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow...

The phonon-polariton spectrum of one-dimensional Rudin-Shapiro photonic superlattices with uniaxial polar materials

Science.gov (United States)

Gómez-Urrea, H. A.; Duque, C. A.; Mora-Ramos, M. E.

2015-11-01

The properties of the optical-phonon-associated polaritonic modes that appear under oblique light incidence in 1D superlattices made of photonic materials are studied. The investigated systems result from the periodic repetition of quasiregular Rudin-Shapiro (RS) multilayer units. It is assume that the structure consists of both passive non-dispersive layers of constant refraction index and active layers of uniaxial polar materials. In particular, we consider III-V wurtzite nitrides. The optical axis of these polaritonic materials is taken along the growth direction. Maxwell equations are solved using the transfer matrix technique for all admissible values of the incidence angle.

Creep in rock salt with temperature. Testing methods and results

International Nuclear Information System (INIS)

Charpentier, J.P.; Berest, P.

1985-01-01

The growing interest shown in the delayed behaviour of rocks at elevated temperature has led the Solid Mechanics Laboratory to develop specific equipment designed for creep tests. The design and dimensioning of these units offer the possibility of investigating a wide range of materials. The article describes the test facilities used (uni-axial and tri-axial creep units) and presents the experimental results obtained on samples of Bresse salt [fr

Influence of social environment on caries prevalence in early childhood

Directory of Open Access Journals (Sweden)

Tušek Ivan

2011-01-01

Full Text Available Introduction. Early childhood caries (ECC is a special form of caries that affects decideous teeth with rapid progression and numerous complications. Objective. The aim of the study was to define the prevalence of ECC in children of the South Bačka area, the importance of social environment for the prevalence and severity of ECC, and define the model for its prevention. Methods. The survey was the cross-sectional analytical study in the 10% sample of children, aged 13-64 months, different sex, social status and human environment. Severity and prevalence of ECC were assessed by dental check-ups. The epidemiological data were obtained by the interview of parents. The tests of significant statistical differences were performed by the analysis variance and χ2 (p<0.05 test, as well as interdependence of ECC and single characteristics that could be a predictor of the disease by the logistic regression. Results. The prevalence of ECC was 30.5%. The highest disease frequency was found in children of male sex (35.1%, out of kindergardens (54.2%, in the third and the next born child in the family (46.9% and in part-time employed mothers (47.2% who had only elementary education (59.3% and were poorly informed about oral health. The highest prevalence (47.1% of ECC was found in children whose parents had the lowest income per month. Type 1 of ECC was the most presented one (75.0%. Conclusion. The higher prevalence and more severe ECC were found in the third and the next born male child from rural environment.

Graphene Foam: Uniaxial Tension Behavior and Fracture Mode Based on a Mesoscopic Model.

Science.gov (United States)

Pan, Douxing; Wang, Chao; Wang, Tzu-Chiang; Yao, Yugui

2017-09-26

Because of the combined advantages of both porous materials and two-dimensional (2D) graphene sheets, superior mechanical properties of three-dimensional (3D) graphene foams have received much attention from material scientists and energy engineers. Here, a 2D mesoscopic graphene model (Modell. Simul. Mater. Sci. Eng. 2011, 19, 054003), was expanded into a 3D bonded graphene foam system by utilizing physical cross-links and van der Waals forces acting among different mesoscopic graphene flakes by considering the debonding behavior, to evaluate the uniaxial tension behavior and fracture mode based on in situ SEM tensile testing (Carbon 2015, 85, 299). We reasonably reproduced a multipeak stress-strain relationship including its obvious yielding plateau and a ductile fracture mode near 45° plane from the tensile direction including the corresponding fracture morphology. Then, a power scaling law of tensile elastic modulus with mass density and an anisotropic strain-dependent Poisson's ratio were both deduced. The mesoscopic physical mechanism of tensile deformation was clearly revealed through the local stress state and evolution of mesostructure. The fracture feature of bonded graphene foam and its thermodynamic state were directly navigated to the tearing pattern of mesoscopic graphene flakes. This study provides an effective way to understand the mesoscopic physical nature of 3D graphene foams, and hence it may contribute to the multiscale computations of micro/meso/macromechanical performances and optimal design of advanced graphene-foam-based materials.

Engineering the quantum anomalous Hall effect in graphene with uniaxial strains

Energy Technology Data Exchange (ETDEWEB)

Diniz, G. S., E-mail: ginetom@gmail.com; Guassi, M. R. [Institute of Physics, University of Brasília, 70919-970 Brasília-DF (Brazil); Qu, F. [Institute of Physics, University of Brasília, 70919-970 Brasília-DF (Brazil); Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

2013-12-28

We theoretically investigate the manipulation of the quantum anomalous Hall effect (QAHE) in graphene by means of the uniaxial strain. The values of Chern number and Hall conductance demonstrate that the strained graphene in presence of Rashba spin-orbit coupling and exchange field, for vanishing intrinsic spin-orbit coupling, possesses non-trivial topological phase, which is robust against the direction and modulus of the strain. Besides, we also find that the interplay between Rashba and intrinsic spin-orbit couplings results in a topological phase transition in the strained graphene. Remarkably, as the strain strength is increased beyond approximately 7%, the critical parameters of the exchange field for triggering the quantum anomalous Hall phase transition show distinct behaviors—decrease (increase) for strains along zigzag (armchair) direction. Our findings open up a new platform for manipulation of the QAHE by an experimentally accessible strain deformation of the graphene structure, with promising application on novel quantum electronic devices with high efficiency.

Engineering the quantum anomalous Hall effect in graphene with uniaxial strains

International Nuclear Information System (INIS)

Diniz, G. S.; Guassi, M. R.; Qu, F.

2013-01-01

We theoretically investigate the manipulation of the quantum anomalous Hall effect (QAHE) in graphene by means of the uniaxial strain. The values of Chern number and Hall conductance demonstrate that the strained graphene in presence of Rashba spin-orbit coupling and exchange field, for vanishing intrinsic spin-orbit coupling, possesses non-trivial topological phase, which is robust against the direction and modulus of the strain. Besides, we also find that the interplay between Rashba and intrinsic spin-orbit couplings results in a topological phase transition in the strained graphene. Remarkably, as the strain strength is increased beyond approximately 7%, the critical parameters of the exchange field for triggering the quantum anomalous Hall phase transition show distinct behaviors—decrease (increase) for strains along zigzag (armchair) direction. Our findings open up a new platform for manipulation of the QAHE by an experimentally accessible strain deformation of the graphene structure, with promising application on novel quantum electronic devices with high efficiency

Optical gain tuning within IR region in type-II In0.5Ga0.5As0.8P0.2/GaAs0.5Sb0.5 nano-scale heterostructure under external uniaxial strain

Science.gov (United States)

Singh, A. K.; Rathi, Amit; Riyaj, Md.; Bhardwaj, Garima; Alvi, P. A.

2017-11-01

Quaternary and ternary alloy semiconductors offer an extra degree of flexibility in terms of bandgap tuning. Modifications in the wave functions and alterations in optical transitions in quaternary and ternary QW (quantum well) heterostructures due to external uniaxial strain provide valuable insights on the characteristics of the heterostructure. This paper reports the optical gain in strained InGaAsP/GaAsSb type-II QW heterostructure (well width = 20 Å) under external uniaxial strain at room temperature (300 K). The entire heterostructure is supposed to be grown on InP substrate pseudomorphically. Band structure, wave functions, energy dispersion and momentum matrix elements of the heterostructure have been computed. 6 × 6 diagonalised k → ·p → Hamiltonian matrix of the system is evaluated and Luttinger-Kohn model has been applied for the band structure and wavefunction calculations. TE mode optical gain spectrum in the QW-heterostructure under uniaxial strain along [110] is calculated. Optical gain of the heterostructure as a function of 2D carrier density and temperature variation is investigated. The variation of the peak optical gain as a function of As and Sb fractions in InGaAsP as a barrier and GaAsSb as a well respectively is exhibited. For a charge carrier injection of 5 ×1012 /cm2 , the TE optical gain is 3952 cm-1 at room temperature under no external uniaxial strain. Significant increase in TE mode optical gain is observed under high external uniaxial strain (1, 5 and 10 GPa) along [110] within IR (Infrared region) region.

Evaluation report on CCTF core-I reflood test C1-5 (Run 14)

International Nuclear Information System (INIS)

Murao, Yoshio; Akimoto, Hajime; Sudoh, Takashi; Okubo, Tsutomu

1983-02-01

A study of a cylindrical core test facility (CCTF) test was performed for modeling the system behavior during the reflood phase of a PWR-LOCA and the following conclusions were obtained: 1) With the exception of some points, the observed phenomena are similar to a model derived from an evaluation model for a PWR safety evaluation. 2) The different points are the water accumulation in the upper plenum, the ECC bypass in the downcomer, the reduction of the effective downcomer head and the pressure drop at the broken cold leg nozzle and in the interconnected pipes. (author)

Target Soil Impact Verification: Experimental Testing and Kayenta Constitutive Modeling.

Energy Technology Data Exchange (ETDEWEB)

Broome, Scott Thomas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Flint, Gregory Mark [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Dewers, Thomas [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Newell, Pania [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-11-01

This report details experimental testing and constitutive modeling of sandy soil deformation under quasi - static conditions. This is driven by the need to understand constitutive response of soil to target/component behavior upon impact . An experimental and constitutive modeling program was followed to determine elastic - plastic properties and a compressional failure envelope of dry soil . One hydrostatic, one unconfined compressive stress (UCS), nine axisymmetric compression (ACS) , and one uniaxial strain (US) test were conducted at room temperature . Elastic moduli, assuming isotropy, are determined from unload/reload loops and final unloading for all tests pre - failure and increase monotonically with mean stress. Very little modulus degradation was discernable from elastic results even when exposed to mean stresses above 200 MPa . The failure envelope and initial yield surface were determined from peak stresses and observed onset of plastic yielding from all test results. Soil elasto - plastic behavior is described using the Brannon et al. (2009) Kayenta constitutive model. As a validation exercise, the ACS - parameterized Kayenta model is used to predict response of the soil material under uniaxial strain loading. The resulting parameterized and validated Kayenta model is of high quality and suitable for modeling sandy soil deformation under a range of conditions, including that for impact prediction.

Influence of Fissure Number on the Mechanical Properties of Layer-Crack Rock Models under Uniaxial Compression

Directory of Open Access Journals (Sweden)

Yun-liang Tan

2018-01-01

Full Text Available Many case studies have revealed that rock bursts generally occur in the high stress concentration area where layer-crack structures often exist, especially for brittle coal or rock masses. Understanding the mechanical properties of layer-crack rock models is beneficial for rational design and stability analysis of rock engineering project and rock burst prevention. This study experimentally investigated the influence of fissure number on the mechanical properties of layer-crack rock models through uniaxial compression tests. The digital speckle correlation method (DSCM and acoustic emission (AE techniques were applied to record and analyze the information of deformation and failure processes. Test results show the following: the bearing capacity of layer-crack specimen decreases compared with intact specimen, but their failure modes are similar, which are the splitting failure accompanied with local shear failure; the nonuniform deformation phenomenon begins to appear at the elastic deformation stage for layer-crack specimens; the AE behavior of intact specimens consists of three stages, that is, active stage, quiet stage, and major active stage, but for layer-crack specimens, it is characteristic by three peaks without quiet stage. In addition, as the fissure number of layer-crack specimens increases, the bearing capacity of specimens decreases, the appearing time of nonuniform deformation phenomenon in the specimen surface decreases, the AE events are denser and denser in each peak stage, and the risk of dynamic instability of layer-crack structure increases. At last, the failure mechanism of layer-crack structure and the related mitigation advices were discussed based on the test results. In general, the novelty is that this paper focuses on the failure mechanism of layer-crack structure directly.

Evaluation report on CCTF Core-II reflood test second shakedown test, C2-SH2 (Run 54)

International Nuclear Information System (INIS)

Iguchi, Tadashi; Sugimoto, Jun; Akimoto, Hajime; Okubo, Tsutomu; Murao, Yoshio

1985-03-01

A low power test (the initial averaged linear power density = 1.18 kW/m) and the base case test (1.4 kW/m) were performed with the Cylindrical Core Test Facility (CCTF) at Japan Atomic Energy Research Institute, in order to study the effect of the power on the reflood phenomena. The former linear power density corresponds nearly to the scaled linear power density based on the current safety evaluation criterio. During the early period of the reflood ( 200s) the heat transfer coefficient became higher and resultantly the quench front advanced faster in the low power test. The core flooding rate was nearly identical between both tests, independently of the different power. The insensitiveness of the power to the core flooding rate was also observed in FLECHT-SET performed in the USA. A significatn large differential pressure oscillation at ECC ports was experienced in the low power test, and it may be important for the long term core cooling although it has not been taken note on the previous studies. (author)

Magnetisation switching in a ferromagnetic Heisenberg nanoparticle with uniaxial anisotropy: a Monte Carlo investigation

International Nuclear Information System (INIS)

Ledue, D.; Berche, P.E.; Patte, R.

2004-01-01

We investigate the thermal-activated magnetisation reversal in a single ferromagnetic nanoparticle with uniaxial anisotropy using Monte Carlo simulations. The aim of this work is to reproduce the reversal magnetisation by uniform rotation at very low temperature in the high-energy barrier hypothesis, that is to realize the Neel-Brown model. For this purpose we have considered a simple cubic nanoparticle where each site is occupied by a classical Heisenberg spin. The Hamiltonian is the sum of an exchange interaction term, a single-ion anisotropy term and a Zeeman interaction term. Our numerical data of the thermal variation of the switching field are compared to an approximated expression and previous experimental results on Co nanoparticles

Message-passing-interface-based parallel FDTD investigation on the EM scattering from a 1-D rough sea surface using uniaxial perfectly matched layer absorbing boundary.

Science.gov (United States)

Li, J; Guo, L-X; Zeng, H; Han, X-B

2009-06-01

A message-passing-interface (MPI)-based parallel finite-difference time-domain (FDTD) algorithm for the electromagnetic scattering from a 1-D randomly rough sea surface is presented. The uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different processors is illustrated for one sea surface realization, and the computation time of the parallel FDTD algorithm is dramatically reduced compared to a single-process implementation. Finally, some numerical results are shown, including the backscattering characteristics of sea surface for different polarization and the bistatic scattering from a sea surface with large incident angle and large wind speed.

Specimen aspect ratio and progressive field strain development of sandstone under uniaxial compression by three-dimensional digital image correlation

Directory of Open Access Journals (Sweden)

H. Munoz

2017-08-01

Full Text Available The complete stress–strain characteristics of sandstone specimens were investigated in a series of quasi-static monotonic uniaxial compression tests. Strain patterns development during pre- and post-peak behaviours in specimens with different aspect ratios was also examined. Peak stress, post-peak portion of stress–strain, brittleness, characteristics of progressive localisation and field strain patterns development were affected at different extents by specimen aspect ratio. Strain patterns of the rocks were obtained by applying three-dimensional (3D digital image correlation (DIC technique. Unlike conventional strain measurement using strain gauges attached to specimen, 3D DIC allowed not only measuring large strains, but more importantly, mapping the development of field strain throughout the compression test, i.e. in pre- and post-peak regimes. Field strain development in the surface of rock specimen suggests that strain starts localising progressively and develops at a lower rate in pre-peak regime. However, in post-peak regime, strains increase at different rates as local deformations take place at different extents in the vicinity and outside the localised zone. The extent of localised strains together with the rate of strain localisation is associated with the increase in rate of strength degradation. Strain localisation and local inelastic unloading outside the localised zone both feature post-peak regime.

Investigation of mean spin orientation in the amorphous systems Fe/sub 81/B/sub 19/ under uniaxial extension conditions

Energy Technology Data Exchange (ETDEWEB)

Korsunskij, I L; Lomonosov, V V; Pazhin, Yu F; Sazonov, S B; Samarin, P F; Sedykh, V D; Serebryakov, A V; Suetin, V A

1986-06-01

The spin orientation averaged over the volume of an amorphous Fe/sub 81/B/sub 19/ band arising on uniaxial cyclic loading of the sample is investigated by NGR spectroscopy. It is found that in the unloaded state of the sample the hyperfine field at the Fe nucleus fluctuates depending on the prehistory of the loading procedure. A qualitative model is proposed which describes the behaviour of the averaged spin orientation.

Strengthening masonry infill panels using engineered cementitious composites

DEFF Research Database (Denmark)

Dehghani, Ayoub; Fischer, Gregor; Nateghi Alahi, Fariborz

2015-01-01

for ECC in order to assess its distinctive mechanical properties such as tensile stress–strain behavior and multiple cracking. To investigate the influence of a thin layer of ECC on plain masonry in terms of changes in stiffness, strength, and deformability, small scale tests have been conducted...... and strength properties, including the post-peak softening behavior in view of seismic applications. The obtained resultsindicate that the proposed ECC-strengthening technique can effectively increase the shear capacity of masonry panels, improve their deformability, enhance their energy absorption capacity......, and prevent the brittle failure mode. Furthermore, the superior deformability of ECC is clearly reflected by cracks development in the ECC layer, which was monitored by a high resolution camera and was analyzed using Digital Image Correlation (DIC) technique....

Standard test method for creep-fatigue crack growth testing

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This test method covers the determination of creep-fatigue crack growth properties of nominally homogeneous materials by use of pre-cracked compact type, C(T), test specimens subjected to uniaxial cyclic forces. It concerns fatigue cycling with sufficiently long loading/unloading rates or hold-times, or both, to cause creep deformation at the crack tip and the creep deformation be responsible for enhanced crack growth per loading cycle. It is intended as a guide for creep-fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. Therefore, this method requires testing of at least two specimens that yield overlapping crack growth rate data. The cyclic conditions responsible for creep-fatigue deformation and enhanced crack growth vary with material and with temperature for a given material. The effects of environment such as time-dependent oxidation in enhancing the crack growth ra...

Effect of Layering on Cracking Initiation and Propagation under Uniaxial Compression

Science.gov (United States)

Modiriasari, A.; Jiang, L.; Yoon, H.; Bobet, A.; Pyrak-Nolte, L. J.

2017-12-01

Rock anisotropy can arise from textural and structural causes both of which contribute to anisotropic strength and moduli. Rock variability makes it difficult to determine which properties dominate failure. Here, laboratory experiments were performed on 3D printed samples to examine the effect of layering on crack formation. Samples with two pre-existing coplanar flaws were fabricated using an additive 3D printing process (Projet CJP 360). Layers of gypsum (0.2 mm thick) were printed in either a horizontal (H) or a vertical (V) orientation to create prismatic samples (152.4 mm x 76.2 mm x 25.1 mm) with two 12.7 mm long coplanar flaws (19.05 mm apart) oriented at 450 with the load. Cracks were induced under uniaxial loading conditions. Digital image correlation (DIC) and acoustic emission (AE) (18 AE sensors with a frequency range of 100-450 kHz) were used to monitor crack evolution. DIC imaging of the V specimen during uniaxial compression showed that smooth cracks were initiated and propagated from the tips of the flaws parallel to the layering. Unlike the strongly bonded samples, no cracks were formed between the pre-existing flaws. The failure mechanism between the flaws was controlled by the weak bonding between the layers, and not by the coalescence of the new cracks. However, for the H specimen, failure was caused by crack coalescence between the two flaws. The new cracks exhibited a step-like roughness that was influenced by the layering in the sample. AE events were only detected when a synchronized mode was used. 3D printed samples can be effectively used to study the effect of anisotropic layering on crack initiation and propagation in a repeatable and controlled manner. Acknowledgements: Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security

Experimental investigation on the fracture behaviour of black shale by acoustic emission monitoring and CT image analysis during uniaxial compression

Science.gov (United States)

Wang, Y.; Li, C. H.; Hu, Y. Z.

2018-04-01

Plenty of mechanical experiments have been done to investigate the deformation and failure characteristics of shale; however, the anisotropic failure mechanism has not been well studied. Here, laboratory Uniaxial Compressive Strength tests on cylindrical shale samples obtained by drilling at different inclinations to bedding plane were performed. The failure behaviours of the shale samples were studied by real-time acoustic emission (AE) monitoring and post-test X-ray computer tomography (CT) analysis. The experimental results suggest that the pronounced bedding planes of shale have a great influence on the mechanical properties and AE patterns. The AE counts and AE cumulative energy release curves clearly demonstrate different morphology, and the `U'-shaped curve relationship between the AE counts, AE cumulative energy release and bedding inclination was first documented. The post-test CT image analysis shows the crack patterns via 2-D image reconstructions, an index of stimulated fracture density is defined to represent the anisotropic failure mode of shale. What is more, the most striking finding is that the AE monitoring results are in good agreement with the CT analysis. The structural difference in the shale sample is the controlling factor resulting in the anisotropy of AE patterns. The pronounced bedding structure in the shale formation results in an anisotropy of elasticity, strength and AE information from which the changes in strength dominate the entire failure pattern of the shale samples.

Preparation of refractory cermet structures for lithium compatibility testing

Science.gov (United States)

Heestand, R. L.; Jones, R. A.; Wright, T. R.; Kizer, D. E.

1973-01-01

High-purity nitride and carbide cermets were synthesized for compatability testing in liquid lithium. A process was developed for the preparation of high-purity hafnium nitride powder, which was subsequently blended with tungsten powder or tantalum nitride and tungsten powders and fabricated into 3 in diameter billets by uniaxial hot pressing. Specimens were then cut from the billets for compatability testing. Similar processing techniques were applied to produce hafnium carbide and zirconium carbide cermets for use in the testing program. All billets produced were characterized with respect to chemistry, structure, density, and strength properties.

Correction between B and H, and the analysis of the magnetization into uniaxial superconductor in the limit at large values of B

International Nuclear Information System (INIS)

Oliveira, I.G. de.

1994-04-01

Using the London theory, a correction is obtained between the direction of the magnetic induction B and the applied magnetic field H in superconductors with uniaxial anisotropy when the Ginsburg-Landau constant is not so large. One analysis of the magnetization as function of angle α is made. (author). 5 refs, 2 figs

Correction between B and H, and the analysis of the magnetization into uniaxial superconductor in the limit at large values of B

Energy Technology Data Exchange (ETDEWEB)

Oliveira, I.G. de

1994-04-01

Using the London theory, a correction is obtained between the direction of the magnetic induction B and the applied magnetic field H in superconductors with uniaxial anisotropy when the Ginsburg-Landau constant is not so large. One analysis of the magnetization as function of angle {alpha} is made. (author). 5 refs, 2 figs.

Paraxial propagation dynamics of the radially polarized Airy beams in uniaxial crystals orthogonal to the optical axis.

Science.gov (United States)

Xie, Jintao; Zhang, Jianbin; Zheng, Xitao; Ye, Junran; Deng, Dongmei

2018-04-30

We study the paraxial propagation of the radially polarized Airy beams (RPAiBs) in uniaxial crystals orthogonal to the optical axis analytically and numerically. The propagation trajectory, the intensity and the radiation forces of the RPAiBs are investigated and the properties are elucidated by numerical examples in this paper. Results show that the RPAiBs evolve into the beams produced by the x-direction electric field (RPAiXBs) and the y-direction electric field (PRAiYBs) which are totally different in uniaxial crystals. During the propagation, the intensity of the RPAiXBs transfers from the side lobe in the x-direction to the main lobe and finally returns to the side lobe in the x-direction again, but that of the RPAiYBs transfers from the side lobe in the y-direction to the main lobe and flows to the side lobe in the x-direction at last. The effect of the intensity focusing for the RPAiXBs can be modulated by the ratio of the extraordinary index (ne) to the ordinary index (no) in anisotropic medium, which contributes to the intensity focusing of the RPAiBs in a short distance a lot. We can adjust the intensity distribution especially the focusing position, the propagation trajectory and the radiation forces distributions of the RPAiXBs through choosing an appropriate value of the ratio of ne to no to meet the actual usage accordingly.

Uniaxial compression on the superconductivity of {beta}-BDA-TTP salts

Energy Technology Data Exchange (ETDEWEB)

Ito, Hiroshi; Ishihara, Tetsuo; Tanaka, Hisaaki; Kuroda, Shin-ichi [Department of Applied Physics, Nagoya University, Chikusa, Nagoya, 464-8603 (Japan); Yamada, Jun-ichi [Department of Material Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Hyogo 678-1297 (Japan)], E-mail: ito@nuap.nagoya-u.ac.jp

2008-10-15

The {beta}-type BDA-TTP superconductors attract attention due to the high transition temperature Tc at ambient pressure for organic superconductors. In order to get insight into the superconductivity in terms of the dimerized anisotropic triangular lattice model, Tc of {beta}-(BDA-TTP){sub 2}X [X = SbF{sub 6}, X = AsF{sub 6}] is studied under uniaxial compression by resistivity measurements. Under compression parallel to the donor stack, Tc increases gradually up to 3 (X = SbF{sub 6}), 5 (X = AsF{sub 6}) kbar, and decreases under further piston pressure. Under compression perpendicular to the donor stack, Tc decreases gradually up to 2.5 (X = SbF{sub 6}), 4 (X = AsF{sub 6}) kbar and then decreases rapidly under further pressure. Only for X = AsF{sub 6}, a Tc minimum at 3 kbar is found for both direction. These trends in Tc are understood as an interplay between the enhancement of antiferromagnetic spin fluctuation and frustration on the triangular lattice. By the interplane compression, Tc increased by 0.5 K up to 2 kbar for both salts, demonstrating the importance of the interlayer interaction.

Uniaxial compression on the superconductivity of β-BDA-TTP salts

International Nuclear Information System (INIS)

Ito, Hiroshi; Ishihara, Tetsuo; Tanaka, Hisaaki; Kuroda, Shin-ichi; Yamada, Jun-ichi

2008-01-01

The β-type BDA-TTP superconductors attract attention due to the high transition temperature Tc at ambient pressure for organic superconductors. In order to get insight into the superconductivity in terms of the dimerized anisotropic triangular lattice model, Tc of β-(BDA-TTP) 2 X [X = SbF 6 , X = AsF 6 ] is studied under uniaxial compression by resistivity measurements. Under compression parallel to the donor stack, Tc increases gradually up to 3 (X = SbF 6 ), 5 (X = AsF 6 ) kbar, and decreases under further piston pressure. Under compression perpendicular to the donor stack, Tc decreases gradually up to 2.5 (X = SbF 6 ), 4 (X = AsF 6 ) kbar and then decreases rapidly under further pressure. Only for X = AsF 6 , a Tc minimum at 3 kbar is found for both direction. These trends in Tc are understood as an interplay between the enhancement of antiferromagnetic spin fluctuation and frustration on the triangular lattice. By the interplane compression, Tc increased by 0.5 K up to 2 kbar for both salts, demonstrating the importance of the interlayer interaction.

Uniaxial compression on the superconductivity of β-BDA-TTP salts

Science.gov (United States)

Ito, Hiroshi; Ishihara, Tetsuo; Tanaka, Hisaaki; Kuroda, Shin-ichi; Yamada, Jun-ichi

2008-10-01

The β-type BDA-TTP superconductors attract attention due to the high transition temperature Tc at ambient pressure for organic superconductors. In order to get insight into the superconductivity in terms of the dimerized anisotropic triangular lattice model, Tc of β-(BDA-TTP)2X [X = SbF6, X = AsF6] is studied under uniaxial compression by resistivity measurements. Under compression parallel to the donor stack, Tc increases gradually up to 3 (X = SbF6), 5 (X = AsF6) kbar, and decreases under further piston pressure. Under compression perpendicular to the donor stack, Tc decreases gradually up to 2.5 (X = SbF6), 4 (X = AsF6) kbar and then decreases rapidly under further pressure. Only for X = AsF6, a Tc minimum at 3 kbar is found for both direction. These trends in Tc are understood as an interplay between the enhancement of antiferromagnetic spin fluctuation and frustration on the triangular lattice. By the interplane compression, Tc increased by 0.5 K up to 2 kbar for both salts, demonstrating the importance of the interlayer interaction.

Acoustic Emission Characteristics of Red Sandstone Specimens Under Uniaxial Cyclic Loading and Unloading Compression

Science.gov (United States)

Meng, Qingbin; Zhang, Mingwei; Han, Lijun; Pu, Hai; Chen, Yanlong

2018-04-01

To explore the acoustic emission (AE) characteristics of rock materials during the deformation and failure process under periodic loads, a uniaxial cyclic loading and unloading compression experiment was conducted based on an MTS 815 rock mechanics test system and an AE21C acoustic emissions test system. The relationships among stress, strain, AE activity, accumulated AE activity and duration for 180 rock specimens under 36 loading and unloading rates were established. The cyclic AE evolutionary laws with rock stress-strain variation at loading and unloading stages were analyzed. The Kaiser and Felicity effects of rock AE activity were disclosed, and the impact of the significant increase in the scale of AE events on the Felicity effect was discussed. It was observed that the AE characteristics are closely related to the stress-strain properties of rock materials and that they are affected by the developmental state and degree of internal microcracks. AE events occur in either the loading or unloading stages if the strain is greater than zero. Evolutionary laws of AE activity agree with changes in rock strain. Strain deformation is accompanied by AE activity, and the density and intensity of AE events directly reflect the damage degree of the rock mass. The Kaiser effect exists in the linear elastic stage of rock material, and the Felicity effect is effective in the plastic yield and post-peak failure stages, which are divided by the elastic yield strength. This study suggests that the stress level needed to determine a significant increase in AE activity was 70% of the i + 1 peak stress. The Felicity ratio of rock specimens decreases with the growth of loading-unloading cycles. The cycle magnitude and variation of the Felicity effect, in which loading and unloading rates play a weak role, are almost consistent.

Standard practice for verification of testing frame and specimen alignment under tensile and compressive axial force application

CERN Document Server

American Society for Testing and Materials. Philadelphia

2005-01-01

1.1 Included in this practice are methods covering the determination of the amount of bending that occurs during the application of tensile and compressive forces to notched and unnotched test specimens in the elastic range and to plastic strains less than 0.002. These methods are particularly applicable to the force application rates normally used for tension testing, creep testing, and uniaxial fatigue testing.

Standard practice for verification of testing frame and specimen alignment under tensile and compressive axial force application

CERN Document Server

American Society for Testing and Materials. Philadelphia

2014-01-01

1.1 Included in this practice are methods covering the determination of the amount of bending that occurs during the application of tensile and compressive forces to notched and unnotched test specimens in the elastic range and to plastic strains less than 0.002. These methods are particularly applicable to the force application rates normally used for tension testing, creep testing, and uniaxial fatigue testing.

Miniaturization of specimens for mechanical testing

International Nuclear Information System (INIS)

Harling, O.K.; Kohse, G.

1987-01-01

The development of mechanical property tests based on bending of a 3 mm diameter by (typically) 0.25 mm thick disk is described. Slow strain rate testing of such a disk is used to obtain tensile properties. Finite element computer modelling is used to extract yield stress values with accuracies of at least +- 10% of uniaxial tensile test values for a variety of materials. Analytical estimates of ductility from disk bend test values are possible for low-ductility materials. Work directed toward finite element calculations for ductility and ultimate tensile strength is also discussed. Preliminary data indicating the feasibility of high strain rate testing for estimation of ductile-to-brittle transition temperatures, and an example of the successful application of miniature bend testing in obtaining relative fatigue information are also presented. (author)

Resource Utilization Associated with Extracardiac Co-morbid Conditions Following Congenital Heart Surgery in Infancy.

Science.gov (United States)

Tuomela, Krista E; Gordon, John B; Cassidy, Laura D; Johaningsmeir, Sarah; Ghanayem, Nancy S

2017-06-01

Congenital heart disease (CHD) is often associated with chronic extracardiac co-morbid conditions (ECC). The presence of ECC has been associated with greater resource utilization during the operative period; however, the impact beyond hospital discharge has not been described. This study sought to understand the scope of chronic ECC in infants with CHD as well as to describe the impact of ECC on resource utilization after discharge from the index cardiac procedure. IRB approved this retrospective study of infants Whitney Rank Sum Test with p < 0.05 considered significant. ECC occurred in 55% (481/876) of infants. Median STAT score was higher in the group with ECC (3 vs. 2, p < 0.001). Resource utilization after discharge from the index procedure as defined by median hospital charges (78 vs. 10 K, p < 0.001 and unplanned hospital days 4 vs. 0, p < 0.001) was higher in those with ECC, and increased with the greater number of ECC, even after accounting for surgical complexity. STAT score and the presence of multiple ECC were associated with higher resource utilization following the index cardiac surgical procedure. These data may be helpful in deciding which children might benefit from a cardiac complex care program that partners families and providers to improve health and decrease healthcare costs.

Electrical resistivity of CeNiSn under uniaxial and hydrostatic pressures

Science.gov (United States)

Echizen, Y.; Umeo, K.; Igaue, T.; Takabatake, T.

2002-05-01

We present measurements of the electrical resistivity ρ(T) on high-quality single-crystalline CeNiSn under both hydrostatic pressure up to 1 GPa and uniaxial pressure up to 0.25 GPa. At ambient pressure, ρ(T) along the orthorhombic a-axis (b-axis) shows two maxima at TL = 12 K (14 K) and TH = 74 K (40 K), respectively, which arise from the Kondo scattering of conduction electrons by the crystal-field ground state and excited states. With increasing hydrostatic pressure, both TL and TH increase linearly, and for P≥0.8 GPa, the anisotropy in ρ(T) for I∥a and I∥b almost vanishes as a result of increased hybridization between the 4f electrons and the conduction electrons. Under P∥a, both TL and TH in ρ(I∥b) increase similarly to under hydrostatic pressure. Under P∥c, however, the depression of TL in ρ(I∥a) and ρ(I∥b) suggests that the c-f hybridization in the crystal-field ground state is weakened in the a-b plane of CeNiSn.

Experimental and theoretical study of transport properties in uniaxially pressed (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+d}elta ceramic samples

Energy Technology Data Exchange (ETDEWEB)

Garcia-Fornaris, I. [Departamento de Ciencias Basicas, Universidad de Granma, Apdo. 21, P.O. Box 85100, Bayamo (Cuba); Mune, P. [Departamento de Fisica, Universidad de Oriente, Patricio Lumumba s/n, P.O. Box 90500, Santiago de Cuba (Cuba); Suzuki, P.A. [Escola de Engenharia de Lorena, Universidade de Sao Paulo, 12602-810 Lorena, SP (Brazil); Alberteris-Campos, M. [Departamento de Engenharia Mecanica, Escola Politecnica, Universidade de Sao Paulo, 05508-900 Sao Paulo, SP (Brazil); Jardim, R.F. [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970 S. Paulo, SP (Brazil); Govea-Alcaide, E., E-mail: malvareza@udg.co.c [Departamento de Fisica, Universidad de Oriente, Patricio Lumumba s/n, P.O. Box 90500, Santiago de Cuba (Cuba); Departamento de Engenharia Mecanica, Escola Politecnica, Universidade de Sao Paulo, 05508-900 Sao Paulo, SP (Brazil)

2010-02-15

Experimental and theoretical studies on the magnetic field dependence of the electrical resistance R(B{sub a}) and the transport noise (TN) in polycrystalline high-T{sub c} superconductors subjected to different uniaxial compacting pressures were conducted. X-ray diffraction rocking curves were performed in different surfaces of the samples in order to investigated the degree of texture. The results indicated an improvement of the degree of texture with increasing the uniaxial compacting pressure. In theoretical simulations of the data, the polycrystalline superconductors were described as a series-parallel array of Josephson devices. The intergranular magnetic field is described within the framework of the intragranular flux-trapping model and the distribution of the grain-boundary angles is assumed to follow the Rayleigh statistical function. The proposed model describes well the experimental magnetoresistance R(B{sub a}) data. We have found that the behavior of the R(B{sub a}) curves changes appreciably when different uniaxially compacting pressures are applied to the sample and such a changes are reproduced by the model when different grain-boundary angles distributions are used. In addition, changes in the R(B{sub a}) dependence have their counterparts in the experimental transport noise signals.

Twenty-third water reactor safety information meeting. Volume 3, structural and seismic engineering, primary systems integrity, equipment operability and aging, ECCS strainer blockage research and regulatory issues

Energy Technology Data Exchange (ETDEWEB)

Monteleone, S. [comp.] [Brookhaven National Lab., Upton, NY (United States)

1996-03-01

This three-volume report contains papers presented at the Twenty- Third Water Reactor Safety Information Meeting held at the Bethesda Marriott Hotel, Bethesda, Maryland, October 23-25, 1995. The papers are printed in the order of their presentation in each session and describe progress and results of programs in nuclear safety research conducted in this country and abroad. Foreign participation in the meeting included papers presented by researchers from France, Italy, Japan, Norway, Russia, Sweden, and Switzerland. This document, Volume 3, presents topics in Structural & Seismic Engineering, Primary Systems Integrity, Equipment Operability and Aging, and ECCS Strainer Blockage Research & Regulatory Issues. Individual papers have been cataloged separately.

Twenty-third water reactor safety information meeting. Volume 3, structural and seismic engineering, primary systems integrity, equipment operability and aging, ECCS strainer blockage research and regulatory issues

International Nuclear Information System (INIS)

Monteleone, S.

1996-03-01

This three-volume report contains papers presented at the Twenty- Third Water Reactor Safety Information Meeting held at the Bethesda Marriott Hotel, Bethesda, Maryland, October 23-25, 1995. The papers are printed in the order of their presentation in each session and describe progress and results of programs in nuclear safety research conducted in this country and abroad. Foreign participation in the meeting included papers presented by researchers from France, Italy, Japan, Norway, Russia, Sweden, and Switzerland. This document, Volume 3, presents topics in Structural ampersand Seismic Engineering, Primary Systems Integrity, Equipment Operability and Aging, and ECCS Strainer Blockage Research ampersand Regulatory Issues. Individual papers have been cataloged separately

Numerical calculation of electromagnetic properties including chirality parameters for uniaxial bianisotropic media

International Nuclear Information System (INIS)

Amirkhizi, Alireza V; Nemat-Nasser, Sia

2008-01-01

Through the use of conductive straight wires or coils the electromagnetic properties of a composite material can be modified. The asymmetric geometry of the coils creates an overall chiral response. The polarization vectors rotate as an electromagnetic wave travels through such a medium. To calculate the chirality of a medium prior to its manufacturing, we developed a method to extract all four electromagnetic material parameter tensors for a general uniaxial bianisotropic composite based on the numerical simulation of the electromagnetic fields. Our method uses appropriate line and surface field averages in a single unit cell of the periodic structure of the composite material. These overall field quantities have physical meaning only when the microscopic variation of the electromagnetic fields in the scale of the unit cell is not important, that is when the wavelength of interest is significantly larger than the maximum linear dimension of the unit cell. The overall constitutive relations of the periodic structure can then be obtained from the relations among the average quantities

Viscosity overshoot followed by steady state measured in uni-axial elongation of LDPE. Ole Hassager, Henrik Koblitz Rasmussen, Anders Bach and Jens Kromann Nielsen

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Hassager, Ole; Bach, Anders

2004-01-01

The transient (e.g. start up of) elongational viscosity of three low-density polyethylene (LDPE) melts (BASF Lupolen 1810H, 1840D and 3020D) was measured using a filament stretching rheometer (FSR) capable of measuring at elevated temperatures. The transient uni-axial elongational viscosity showe...

Spherical nanoindentation of proton irradiated 304 stainless steel: A comparison of small scale mechanical test techniques for measuring irradiation hardening

Science.gov (United States)

Weaver, Jordan S.; Pathak, Siddhartha; Reichardt, Ashley; Vo, Hi T.; Maloy, Stuart A.; Hosemann, Peter; Mara, Nathan A.

2017-09-01

Experimentally quantifying the mechanical effects of radiation damage in reactor materials is necessary for the development and qualification of new materials for improved performance and safety. This can be achieved in a high-throughput fashion through a combination of ion beam irradiation and small scale mechanical testing in contrast to the high cost and laborious nature of bulk testing of reactor irradiated samples. The current work focuses on using spherical nanoindentation stress-strain curves on unirradiated and proton irradiated (10 dpa at 360 °C) 304 stainless steel to quantify the mechanical effects of radiation damage. Spherical nanoindentation stress-strain measurements show a radiation-induced increase in indentation yield strength from 1.36 GPa to 2.72 GPa and a radiation-induced increase in indentation work hardening rate of 10 GPa-30 GPa. These measurements are critically compared against Berkovich nanohardness, micropillar compression, and micro-tension measurements on the same material and similar grain orientations. The ratio of irradiated to unirradiated yield strength increases by a similar factor of 2 when measured via spherical nanoindentation or Berkovich nanohardness testing. A comparison of spherical indentation stress-strain curves to uniaxial (micropillar and micro-tension) stress-strain curves was achieved using a simple scaling relationship which shows good agreement for the unirradiated condition and poor agreement in post-yield behavior for the irradiated condition. The disagreement between spherical nanoindentation and uniaxial stress-strain curves is likely due to the plastic instability that occurs during uniaxial tests but is absent during spherical nanoindentation tests.

Risk-Informed Margin Management (RIMM) Industry Applications IA1 - Integrated Cladding ECCS/LOCA Performance Analysis - Problem Statement

Energy Technology Data Exchange (ETDEWEB)

Szilard, Ronaldo Henriques [Idaho National Lab. (INL), Idaho Falls, ID (United States); Youngblood, Robert [Idaho National Lab. (INL), Idaho Falls, ID (United States); Frepoli, Cesare [Idaho National Lab. (INL), Idaho Falls, ID (United States); Yurko, Joseph P. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Swindlehurst, Gregg [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Hongbin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bayless, Paul D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis L. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-04-01

The U. S. NRC is currently proposing rulemaking designated as “10 CFR 50.46c” to revise the LOCA/ECCS acceptance criteria to include the effects of higher burnup on cladding performance as well as to address some other issues. The NRC is also currently resolving the public comments with the final rule expected to be issued in the summer of 2016. The impact of the final 50.46c rule on the industry will involve updating of fuel vendor LOCA evaluation models, NRC review and approval, and licensee submittal of new LOCA evaluations or reanalyses and associated technical specification revisions for NRC review and approval. The rule implementation process, both industry and NRC activities, is expected to take 5-10 years following the rule effective date. The need to use advanced cladding designs is expected. A loss of operational margin will result due to the more restrictive cladding embrittlement criteria. Initial and future compliance with the rule may significantly increase vendor workload and licensee cost as a spectrum of fuel rod initial burnup states may need to be analyzed to demonstrate compliance. Consequently there will be an increased focus on licensee decision making related to LOCA analysis to minimize cost and impact, and to manage margin.

Examination and modeling of void growth kinetics in modern high strength dual phase steels during uniaxial tensile deformation

Energy Technology Data Exchange (ETDEWEB)

Saeidi, N., E-mail: navidsae@gmail.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ashrafizadeh, F.; Niroumand, B. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Forouzan, M.R.; Mohseni mofidi, S. [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Barlat, F. [Materials Mechanics Laboratory (MML), Graduate Institute of Ferrous Technology (GIFT), Pohang University of Science and Technology - POSTECH, San 31 Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784 (Korea, Republic of)

2016-04-01

Ductile fracture mechanisms during uniaxial tensile testing of two different modern high strength dual phase steels, i.e. DP780 and DP980, were studied. Detailed microstructural characterization of the strained and sectioned samples was performed by scanning electron microscopy as well as EBSD examination. The results revealed that interface decohesion, especially at martensite particles located at ferrite grain boundaries, was the most probable mechanism for void nucleation. It was also revealed that the creation of cellular substructure can reduce stored strain energy and thereby, higher true fracture strain was obtained in DP980 than DP780 steel. Prediction of void growth behavior based on some previously proposed models showed unreliable results. Therefore, a modified model based on Rice-Tracey family models was proposed which showed a very lower prediction error compared with other models. - Highlights: • Damage mechanism in two modern high strength dual phase steels was studied. • Creation of cellular substructures can reduce the stored strain energy within the ferrite grains. • The experimental values were examined by Agrawal as well as RT family models. • A modified model was proposed for prediction of void growth behavior of DP steels.

Numerical analysis on the crack propagation and failure characteristics of rocks with double fissures under the uniaxial compression

Directory of Open Access Journals (Sweden)

Leyong Chen

2015-12-01

Full Text Available The fissures and rock bridges with different dips had different contributions to crack's initiation, propagation, convergence and penetration. In this paper, based on the rock fracture theory, the crack's propagation and evolution process on rock specimen with double fissures under uniaxial compression was simulated. As a result, the crack propagation and evolution law of rocks with different fissure dips (α = 0°, 15°, 30°, 45°, 60°, 75°, 90°; β = 45° and different rock bridge dips (β = 0°, 30°, 45°, 60°, 90°; α = 45° was obtained by numerical tests. Meanwhile, the fissure and rock bridge dips influence on the macro mechanical properties of rock was analyzed. Besides, the paper investigated the influences of different fissure dips and different rock bridge dips on the bridge transfixion. The study is of great significance to reveal the impact of different dips on the mechanical mechanism of multiple-fissures rock under specific conditions, and it also has important theoretical significance for the research on multiple-fissure rock.

Influence of ambient moisture on the compaction behavior of microcrystalline cellulose powder undergoing uni-axial compression and roller-compaction: a comparative study using near-infrared spectroscopy.

Science.gov (United States)

Gupta, Abhay; Peck, Garnet E; Miller, Ronald W; Morris, Kenneth R

2005-10-01

This study evaluates the effect of variation in the ambient moisture on the compaction behavior of microcrystalline cellulose (MCC) powder. The study was conducted by comparing the physico-mechanical properties of, and the near infrared (NIR) spectra collected on, compacts prepared by roller compaction with those collected on simulated ribbons, that is, compacts prepared under uni-axial compression. Relative density, moisture content, tensile strength (TS), and Young modulus were used as key sample attributes for comparison. Samples prepared at constant roller compactor settings and feed mass showed constant density and a decrease in TS with increasing moisture content. Compacts prepared under uni-axial compression at constant pressure and compact mass showed the opposite effect, that is, density increased while TS remained almost constant with increasing moisture content. This suggests difference in the influence of moisture on the material under roller compaction, in which the roll gap (i.e., thickness and therefore density) remains almost constant, vs. under uni-axial compression, in which the thickness is free to change in response to the applied pressure. Key sample attributes were also related to the NIR spectra using multivariate data analysis by the partial least squares projection to latent structures (PLS). Good agreement was observed between the measured and the NIR-PLS predicted values for all key attributes for both, the roller compacted samples as well as the simulated ribbons. Copyright (c) 2005 Wiley-Liss, Inc. and the American Pharmacists Association

The right circular polarized waves in the three-dimensional anisotropic dispersive photonic crystals consisting of the magnetized plasma and uniaxial material as the Faraday effects considered

International Nuclear Information System (INIS)

Zhang, Hai-Feng; Liu, Shao-Bin; Tang, Yi-Jun; Zhen, Jian-Ping

2014-01-01

In this paper, the properties of the right circular polarized (RCP) waves in the three-dimensional (3D) dispersive photonic crystals (PCs) consisting of the magnetized plasma and uniaxial material with face-centered-cubic (fcc) lattices are theoretically investigated by the plane wave expansion method, which the homogeneous anisotropic dielectric spheres (the uniaxial material) immersed in the magnetized plasma background, as the Faraday effects of magnetized plasma are considered (the incidence electromagnetic wave vector is parallel to the external magnetic field at any time). The equations for calculating the anisotropic photonic band gaps (PBGs) for the RCP waves in the first irreducible Brillouin zone are theoretically deduced. The anisotropic PBGs and a flatbands region can be obtained. The effects of the ordinary-refractive index, extraordinary-refractive index, anisotropic dielectric filling factor, plasma frequency, and plasma cyclotron frequency (the external magnetic field) on the properties of first two anisotropic PBGs for the RCP waves are investigated in detail, respectively. The numerical results show that the anisotropy can open partial band gaps in fcc lattices at U and W points, and the complete PBGs for the RCP waves can be achieved compared to the conventional 3D dispersive PCs composed of the magnetized plasma and isotropic material. It is also shown that the first two anisotropic PBGs can be tuned by those parameters as mentioned above. Those PBGs can be enlarged by introducing the uniaxial material into such 3D PCs as the Faraday effects are considered

Measurement of tensile and fracture toughness properties using small punch test

International Nuclear Information System (INIS)

Chatterjee, S.; Shah Priti Kotak

2005-05-01

Small punch test wu carried out at room temperature on five different steels using 10 mm by 10 mm specimens of 0.4 mm thickness in a univesal testing machine. The tensile and fracture toughness properties of the five steels obtained from small punch test were compared with those obtained from the standard test method. The results (except in one steel) show that the tensile properties obtained from small punch test are in close proximity to those obtained ftom uni-axial tension test. The results also show that fracture toughness (Jic) properties obtained ftom small punch test are within ±20% of the corresponding values obtained using standard test procedures. (author)

[Influence of social environment on caries prevalence in early childhood].

Science.gov (United States)

Tusek, Ivan; Carević, Momir; Tusek, Jasmina

2011-01-01

Early childhood caries (ECC) is a special form of caries that affects decideous teeth with rapid progression and numerous complications. The aim of the study was to define the prevalence of ECC in children of the South Backa area, the importance of social environment for the prevalence and severity of ECC, and define the model for its prevention. The survey was the cross-sectional analytical study in the 10% sample of children, aged 13-64 months, different sex, social status and human environment. Severity and prevalence of ECC were assessed by dental check-ups. The epidemiological data were obtained by the interview of parents. The tests of significant statistical differences were performed by the analysis variance and chi2 (p family (46.9%) and in part-time employed mothers (47.2%) who had only elementary education (59.3%) and were poorly informed about oral health. The highest prevalence (47.1%) of ECC was found in children whose parents had the lowest income per month. Type 1 of ECC was the most presented one (75.0%). The higher prevalence and more severe ECC were found in the third and the next born male child from rural environment.

Redesigning axial-axial (biaxial) cruciform specimens for very high cycle fatigue ultrasonic testing machines.

Science.gov (United States)

Montalvão, Diogo; Wren, Andrew

2017-11-01

The necessity to increase performances in terms of lifetime and security in mechanical components or structures is the motivation for intense research in fatigue. Applications range from aeronautics to medical devices. With the development of new materials, there is no longer a fatigue limit in the classical sense, where it was accepted that the fatigue limit is the stress level such that there is no fracture up to 1E7 cycles. The recent development of ultrasonic testing machines where frequencies can go as high as 20 kHz or over enabled tests to be extended to ranges larger than 1E9 in just a few days. This area of studies is now known as Very High Cycle Fatigue (VHCF). On the other hand, most of the existing test equipment in the market for both classical and VHCF are uniaxial test machines. However, critical components used in Engineering applications are usually subjected to complex multi-axial loading conditions. In this paper, it is presented the methodology to redesigning existing cruciform test specimens that can be used to create an in-plane biaxial state of stress when used in 'uniaxial' VHCF ultrasonic testing machines (in this case, the term 'uniaxial' is used not because of the state of stress created at the centre of the specimen, but because of the direction at which the load is applied). The methodology is explained in such a way that it can be expanded to other existing designs, namely cruciform designs, that are not yet used in VHCF. Also, although the approach is presented in simple and logical terms, it may not be that obvious for those who have a more focused approach on fatigue rather than on modal analysis. It is expected that by contributing to bridging the gap between the sciences of modal analysis and fatigue, this research will help and encourage others exploiting new capabilities in VHCF.

Experimental study on infrared radiation temperature field of concrete under uniaxial compression

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Lou, Quan; He, Xueqiu

2018-05-01

Infrared thermography, as a nondestructive, non-contact and real-time monitoring method, has great significance in assessing the stability of concrete structure and monitoring its failure. It is necessary to conduct in depth study on the mechanism and application of infrared radiation (IR) of concrete failure under loading. In this paper, the concrete specimens with size of 100 × 100 × 100 mm were adopted to carry out the uniaxial compressions for the IR tests. The distribution of IR temperatures (IRTs), surface topography of IRT field and the reconstructed IR images were studied. The results show that the IRT distribution follows the Gaussian distribution, and the R2 of Gaussian fitting changes along with the loading time. The abnormities of R2 and AE counts display the opposite variation trends. The surface topography of IRT field is similar to the hyperbolic paraboloid, which is related to the stress distribution in the sample. The R2 of hyperbolic paraboloid fitting presents an upward trend prior to the fracture which enables to change the IRT field significantly. This R2 has a sharp drop in response to this large destruction. The normalization images of IRT field, including the row and column normalization images, were proposed as auxiliary means to analyze the IRT field. The row and column normalization images respectively show the transverse and longitudinal distribution of the IRT field, and they have clear responses to the destruction occurring on the sample surface. In this paper, the new methods and quantitative index were proposed for the analysis of IRT field, which have some theoretical and instructive significance for the analysis of the characteristics of IRT field, as well as the monitoring of instability and failure for concrete structure.

Early childhood caries in preschool children of Kosovo - a serious public health problem

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Meqa Kastriot

2010-12-01

Full Text Available Abstract Background Even though it has been widely studied, early childhood caries (ECC remains a serious public health problem, especially in countries where there is no national program of oral health assessment and no genuine primary oral health care, such as in Kosovo. The purpose of this study was to assess the prevalence of ECC and analyze caries risk factors. Methods The subjects were 1,008 preschool children, selected by stratified random cluster sampling, in the municipality of Prishtina, capital of Kosovo. Data were collected through clinical examination and interviews. Dmft data were recorded according to WHO criteria. Bacterial examination (CRT bacteria test and plaque test of Greene-Vermillion were used. Results The mean dmft of preschool children was found to be 5.8. The prevalence of ECC was 17.36%, with a mean dmft of 11 ± 3.6. Streptococcus mutans prevalence in ECC children was 98%. A significant correlation between dmft and S mutans counts (≥105 CFU/mL saliva was demonstrated. A correlation was also found between daily sweets consumption and dmft in children with ECC (P P Conclusion The prevalence of ECC was high among preschool children in the municipality of Kosovo. We recommend increasing parents' knowledge of proper feeding habits and oral health practices, and increasing preschool children's accessibility to dental services.

Comparison of concentric and eccentric bench press repetitions to failure.

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Kelly, Stephen B; Brown, Lee E; Hooker, Steven P; Swan, Pamela D; Buman, Matthew P; Alvar, Brent A; Black, Laurie E

2015-04-01

Eccentric muscle actions (ECC) are characterized by muscle lengthening, despite actin-myosin crossbridge formation. Muscles acting eccentrically are capable of producing higher levels of force compared with muscles acting concentrically. The purpose of this study was to determine whether ECC bench press yields greater strength than concentric (CON) as determined by 1 repetition maximum (1RM). Additionally, a comparison was made examining differences in the number of repetitions to failure at different relative intensities of 1RM. Thirty healthy men (age = 24.63 ± 5.6 years) were tested for 1RM in CON and ECC bench press and the number of repetitions completed at 60, 70, 80, and 90% 1RM. For CON repetitions, the weight was mechanically lowered to the chest, and the participant pressed it up until the elbows were fully extended. The ECC bench press consisted of lowering a barbell from a fully extended elbow position to the chest in a continuous controlled manner for 3 seconds as determined by electronic metronome. Paired t-tests showed that ECC 1RM (115.99 ± 31.08 kg) was significantly (p ≤ 0.05) greater than CON 1RM (93.56 ± 26.56 kg), and the number of repetitions completed at 90% 1RM was significantly (p ≤ 0.05) greater in ECC (7.67 ± 3.24) as compared with CON (4.57 ± 2.21). There were no significant differences in number of completed repetitions during CON and ECC bench press at 60, 70, and 80% 1RM. These data indicate that ECC actions yield increased force capabilities (∼120%) as compared with CON in the bench press and may be less prone to fatigue, especially at higher intensities. These differences suggest a need to develop unique strategies for training eccentrically.

Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

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Mohan, Nisha

Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the hardening-softening-hardening material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed hardening material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of

Predicted VO2max and effectiveness of external chest compression by Chinese nurses.

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Ho, Leo S T; Jones, Alice Y M; Rainer, Timothy H

2017-08-01

The aims of this study were to assess the influence of sex and body position on external chest compression (ECC) to a manikin by Chinese nurses and to determine the relationship between rescuer's predicted VO2max and ECC depth. A total of 40 nurses performed ECC on a manikin for 5 min in the standing (S) and bed-mount kneeling (K) position, then completed a Chester step-test, in 3 separate days. The rate and depth of compressions and oxygen consumption during ECC were measured. Mean compression rate recorded was above 100/min in both positions throughout ECC. Mean compression depth for male participants was more than 38 mm for 5 min in the K-position but only 3 min in the S-position. Female participants achieved this compression depth for less than 90 s in the K-position but not at all in the S-position. Irrespective of sex, the K-position appears to facilitate effective ECC. The relationship between aerobic fitness of female nurses and their ability to perform effective cardiopulmonary resuscitation warrants further investigation.

Prediction of long time creep rupture properties of welded joints using the results of short duration creep crack incubation tests