Energy Technology Data Exchange (ETDEWEB)

This book contains over 20 selections. Some of the titles are: Continuum damage mechanics studies on the dynamic fracture of concrete; Dynamic compressive strength of cementitious materials; Rate-sensitivity of mode I and mode II fracture concrete; and An impact damage model of concrete.

Energy Technology Data Exchange (ETDEWEB)

This work contains 27 chapters which cover recent advances in fracture mechanics applied to cement-based composites: concrete, reinforced concrete, and fiber reinforced concrete. The book, based on a NATO Advanced Study Institute, is a comprehensive survey of treating nonlinearity associated with crack growth in brittle materials such as cement composites, rocks and ice. The book is divided into 8 major themes: advances in nonlinear fracture mechanics; fracture processes; numerical modelling of fracture; experimental methods of determining fracture parameters; damage and continuum modelling; strain-rate and dynamic effects of crack propagation; stress-corrosion, time and temperature effects on fracture; and implications for concrete structures.

Science.gov (United States)

Al2O3-based ceramic is one of the most widely used materials for tools employed in hardened steel turning applications due to its high hardness, wear resistance, heat resistance and chemical stability. The objective of this work is to predict the lives of Al2O3-(W, Ti)C ceramic tools in intermittent turning of hardened AISI 1045 steel by means of damage evolution model taking into account the mechanical loading and thermal effect in the cutting process. A damage evolution model analyzing the RVE with uniformly distributed interacting cracks is constructed based on micromechanics. The calculated results of the proposed damage evolution model are compared with the lives of two kinds of Al2O3-(W, Ti)C ceramic tools obtained through experiments. It is found that the proposed model can be used to predict the lives of the ceramic cutting tools in intermittent turning ...

Energy Technology Data Exchange (ETDEWEB)

This experiment is carried out in the series of the investigation on the damage mechanism of carbon steel. In this paper, the damage situation is considered by structure observations. The test were carried out in 600degC-1200degC temperature range, in blowing an argon gas. The reagents are Na{sub 2}O, Na{sub 2}O{sub 2} and NaOH. From structure observations, the holes are observed on the surface of iron-base material in some test conditions. This result is indicated that the selective reaction occurs. The selective reaction is more obvious as the time exposed to the high temperature is longer. It is considered that the selective reaction occurs after the chemical reaction between iron-base material and sodium compound. The areas, in which Mn-concentration is higher, are observed in products on the surface of specimen. (author)

Energy Technology Data Exchange (ETDEWEB)

Threshold pump intensity values leading to irreversible damage to colored laser elements based on elastic polymers were measured. The damage to colored elastomers is connected with absorbing microinclusions but is independent of molecular absorption. It is shown that damage to the elastomers has a pronounced threshold character in contrast to the microdamage accumulation effect in glassy polymers. The damage threshold for elastomers is 1.5 times higher, which is connected with the absence of microstresses (characteristics for organic glasses) in the specimens. 13 references.

International Nuclear Information System (INIS)

The sensitivity of the primary circuit material was examined at the Mochovce and Dukovany NPPs. No significant sensitivity of the base material or the weld metal to the initiation of corrosion cracking was observed. Thermal aging was found to accelerate significantly the corrosion fatigue kinetics in the material of the heat affected zone. The threshold values of the double amplitudes of the stress intensity factor were below 8 MPa/m"2 for the materials examined, with a cycle asymmetry coefficient of 0.65. The tests revealed no appreciable sensitivity to general corrosion, pitting, or intergranular corrosion. (J.B.). 7 tabs., 26 figs., 11 refs.

KoreaScience (Korea)

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UK PubMed Central (United Kingdom)

Despite a complex cascade of cellular events to reconstruct the damaged extracellular matrix, ligament healing results in a mechanically inferior scarred ligament. During normal healing, granulation...Full Text Available

Science.gov (United States)

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Energy Technology Data Exchange (ETDEWEB)

An investigation was made of the accumulation of laser damage to transparent polymers irradiated with nanosecond pulses from neodymium and ruby lasers. The damage was investigated by the method of scattering and luminescence in the visible and near ultraviolet parts of the spectrum. It was established that there were two stages in laser damage by repeated irradiation with pulses of intensity below the single-shot damage threshold. An absorbing defect evolved during the first stage in such a way as to create a thermal instability in the surrounding matrix. During the second stage this thermal instability caused spatial growth of laser damage because of propagation of an ionization-inducing absorption wave with a front traveling at the rate governed by the electron component of the thermal conductivity.

Energy Technology Data Exchange (ETDEWEB)

The Boiler and Pressure Vessel Code (BPVC) of the American Society of Mechanical Engineers (ASME) has introduced a risk based approach into Section XI that covers Rules for Inservice Inspection of Nuclear Power Plant Components. The risk based approach requires application of the probabilistic risk assessments (PRA). Because no industry consensus standard existed for PRAs, ASME has developed a standard to evaluate the quality level of an available PRA needed to support a given risk based application. The paper describes the PRA standard, Section XI application of PRAs, and plans for broader applications of PRAs to other ASME nuclear codes and standards. The paper addresses several specific topics of interest to Section XI. Important consideration are special methods (surrogate components) used to overcome the lack of PRA treatments of passive components in PRAs. The approach allows calculations of ...

Energy Technology Data Exchange (ETDEWEB)

A novel acidizing process is used to increase the permeability of carbonate rock cores in the laboratory and to remove drilling fluid damage from cores and wafers. Field results show the benefits of the technology as applied both to injector and producer wells.

International Nuclear Information System (INIS)

The major degradation mechanisms acting during the aging of selected WWER-440/213 primary circuit facilities were assessed critically. The analysis gave evidence that such mechanisms include radiation and fatigue damage of the reactor pressure vessel (effect of the neutron flow, cyclic fatigue promoted by the corrosive medium, effect of thermal aging), corrosion-mechanical and thermo-mechanical (fatigue) damage of the steam generator (stress corrosion cracking, erosion corrosion, thermal aging, wear), thermal and dynamic aging of the pressurizer, and corrosion-mechanical damage of the primary circuit piping (thermal aging, corrosion). (J.B.). 5 tabs., 1 fig., 62 refs.

International Nuclear Information System (INIS)

The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and organs are commented. Referring to delayed ...

Energy Technology Data Exchange (ETDEWEB)

Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent ...

Energy Technology Data Exchange (ETDEWEB)

The dominant fracture parameters used in fracture mechanics analyses of pipelines are related to the asymptotic crack-tip stress and strain fields at the crack tip. This paper reviewed new developments in constraint-sensitive fracture mechanics for the assessment of pipeline girth weld integrity. Constraint theories and experimental studies were evaluated. Constraint models included brittle fracture models and ductile fracture models. Constraint models for brittle fracture are based on weakest link statistics and Weibull distribution. Specifically designed experimental tests are often necessary to derive the damage parameters of ductile fracture models. Experimental test data must then be calibrated with finite element analyses (FEA) to ensure that the correct damage parameters are chosen. The effects of specimen geometry and loading condition are characterized by the T stress, ...

Energy Technology Data Exchange (ETDEWEB)

Aerospace gas turbine disks operate in an environment of relatively high stresses caused by centrifugal forces and elevated temperatures. These severe conditions necessitate the need for materials with high temperature strength and good low cycle fatigue resistance. One class of alloys used for this task is the nickel base superalloys, out of which, IN 718 is the most widely used in the aerospace industry. The properties of IN 718 are attributed to the combined effects of the chemistry, heat treatment, and microstructure. The chemistry is tailored not only for solid solution strengthening but also for precipitation hardening developed during heat treatment, which combined with a fine grained microstructure lead to excellent mechanical properties such as low cycle fatigue resistance and elevated temperature strength. The properties of a gas turbine disk are sensitive to the microstructure, in particular the grain size, which is dependent on the ...

Energy Technology Data Exchange (ETDEWEB)

A unified physically based ion implantation damage model has been developed which successfully predicts both the impurity profiles and the damage profiles for a wide range of implant conditions for arsenic, phosphorus, BF{sub 2}, and boron implants into single-crystal silicon. In addition, the amorphous layer thicknesses predicted by this new damage model are also in excellent agreement with experimental measurements. This damage model is based on the physics of point defects in silicon, and explicitly simulates the defect production, diffusion, and their interactions which include interstitial-vacancy recombination, clustering of same type of defects, defect-impurity complex formation, emission of mobile defects from clusters, and surface effects for the first time. New computationally efficient algorithms have been developed to overcome the barrier of the ...

International Nuclear Information System (INIS)

This paper dealt with the identification of possible damaging mechanism of the collector of the WWER 440 steam generator, cracking of primary collectors, corrosion damage of the protective coat of the primary collector circumferential weld, cracking of breathing space in the region of blinding effect by corrosion and strain, leaking of disassembling joint of the primary collector lid and with the integrity of heat exchanging tubes.

Science.gov (United States)

This paper focuses on a factorial-based design strategy. The approach provides an efficient and statistically reliable means for assessing the influence of multivariable effects. It is applied to the detection and evaluation of damage in impacted composite sandwich panels. The experimental results obtained from this test strategy are utilized to form an empirical response function. The resulting polynomial relates damage area to residual compression strength at values of independent variables for which testing did not occur. The response function also identifies nonlinear interaction effects of key variabes that cannot be easily ascertained by traditional single-variable test strategies. Independent variables evaluated include core thickness, number of face sheet plys and impact energy. The methodology presented allows the designer to predict with more confidence the damage tolerance of a composite ...

International Nuclear Information System (INIS)

Reference is made to Cheng and Leblond (Amer. J. Anat.; 141:537 (1974)) who used tritiated thymidine to kill cells synthesising DNA in the crypts of the small intestine. Amongst their findings was that very low doses caused measurable cell killing and that the killing was not random throughout the crypt but occurred selectively at the crypt base where stem cells are presumably located. It is here reported that the presence of hypersensitive cells at the base of the crypts can be demonstrated after whole-body X- or gamma-irradiation, and the time sequence for the production and loss of the killed cells is described together with their dose-response relationship. The studies were conducted on mice. The data were expressed as surviving rather than killed cells, and it was established that the crypt are amongst the most sensitive of mammalian cells. The mechanism by which these sensitive cells are killed is not known, but DNA ...

UK PubMed Central (United Kingdom)

Intravascular coagulation, thrombosis, and fibrin deposition often produce tissue damage in allogeneic inflammatory reactions such as allograft rejection. The mechanisms which initiate blood clotting...Full Text Available

UK PubMed Central (United Kingdom)

Cocaine is a worldwide used drug and its abuse is associated with physical, psychiatric and social problems. The mechanism by which cocaine causes neurological damage is very complex and involves several...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The overall objective of this project has been to develop immunochemical methods to quantitate unique DNA base damages in order to facilitate studies on radiation-induced damage production and repair. Specifically, we have been using antibodies raised to damaged bases to quantitate unique lesions in model systems in order to evaluate their potential biological consequences. Our approach has been to synthesize modified nucleotides or nucleosides, conjugate them to protein carriers, and use the conjugates as immunogens in rabbits or to prepare monoclonal antibodies. We have been studying damages that are stable radiolysis products found in X-irradiated DNA and thus of potential biological consequence. Our aim is to build an in vitro and in vivo data base on the interactions between model DNA lesions and such cellular enzymes as DNA polymerases ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes a risk based approach and inspection planning as part of the Pipeline Integrity Management (PIM) system for the 95.5 km long 18'' GASVOL gas pipeline in the South eastern region of Brazil transporting circa 5 000 000 m3 dry gas per day. Pipeline systems can be subject to several degradation mechanisms and inspection and monitoring are used to ensure system integrity. Modern pipeline regulations and codes are normally based on a core safety or risk philosophy. The detailed design requirements presented in design codes are practical interpretations established so as to fulfill these core objectives. A given pipeline, designed, constructed and installed according to a pipeline code is therefore the realization of a structure, which, along its whole length, meets the applicable safety objectives of that code. The main objective of Pipeline Integrity Management (PIM) is to control and ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

The plastic displacements around Knoop indentations made in hard titanium/aluminum multilayered films on soft aluminum alloy substrates have been studied. Indentations were cross-sectioned and imaged using the focused-ion-beam (FIB) milling and high-resolution scanning electron microscopy (SEM), respectively. The FIB milling method has the advantage of removing material in a localized region without producing mechanical damage to the specimen. The micrographs of the cross-sectioned indentations indicate that most of the plastic deformation around the indentation is dominated by the soft aluminum substrate. There is a very small change in the multilayered film thickness around the indentation{emdash}less than 10{percent}. The plastic deformation of the thin film resembles a membrane being deflected by a localized pressure gradient across the membrane. Stress-induced voids are also observed in the multilayered film, especially in the area around ...

Energy Technology Data Exchange (ETDEWEB)

The cost incurred every year in West Germany due to air pollution is investigated. Damage to buildings, materials, and vegetation are evaluated as well as the cost of additional cleaning work and changes of location with the objective of getting a picture of the economic value of air pollution abatement. The findings are based on data of immission damage in high-exposure areas. Damage is assessed in consideration of the frequency of repair measures in industrial and country atmosphere. Further research will be necessary in view of the many problems concerning methods and availability of basic statistical data. The sequential cost estimated for a few selected cases of damage show that economic losses due to air pollution amount to several thousand million DM. Air pollution abatement measures thus do not only improve our quality of life but also help to save considerable cost to our ...

Energy Technology Data Exchange (ETDEWEB)

In the power station West Block 2 at Voerde (Federal Republic of Germany), cracks in the final stage of the shaft were determined at the ND1 rotor of the 350 MW condensation tube was determined. A purely mechanical preparation of the crack was not possible due to the depth of the crack. A substitute rotor was not available. A repair solution was developed covering a welding of a new shaft section to the existing rotor. The authors of the contribution under consideration report on the damage, cause of the damage, repair solution and the process of repair.

Science.gov (United States)

A summary of research conducted during the first year is presented. The research objectives were sought by conducting two tasks: (1) investigation of probabilistic design techniques for reliability-based design of composite sandwich panels, and (2) examin...

Energy Technology Data Exchange (ETDEWEB)

Life management system is based on the valid nowadays in Estonian power plants regulation documentation. The system allows to estimate stress distribution in components, find computational assessment of cumulated creep damage, determine when and where it is necessary to cut off the particular number of microsamples or take replicas. Finally, the real metal condition may be assessed on the basis of metallographic specimen research and reasonable 3-R decision - run, repair, replacement - made on further component use. (orig.) 6 refs.

Energy Technology Data Exchange (ETDEWEB)

In the flood surveys, it is fundamental to set up the relations of stage-damage. And this makes it possible to evaluate the flood regulation effects of the multipurpose dam and/or levee construction for optimum formulation. Unfortunately in the previous basin studies excluding the Han river basin survey, the conventional approaches on this matter have not been performed due to its time-consuming complexity. In this study we attempted a new method based on the disaster status, and constructed six stage-damage curves along the reaches of the Kum river basin, based upon the flood events records for recent 12 years (1981-92). (author). 12 refs., 3 tabs., 13 figs.

Energy Technology Data Exchange (ETDEWEB)

Blades of modern steam turbines are designed for high efficiency and operational safety. Modern computer programs enable optimisation of design but factors like manufacturing, assembly, operation and downtimes still play an important role. Damage statistics show that blade damage still quite frequent. Selected cases from the Allianz damage assessment centre show some of the more frequent damage mechanisms. Damage is often caused when several factors come together. Prevention of follow-up damage requires early identification of beginning damage.(orig.) [German] Die Auslegung der Beschaufelung moderner Dampfturbinen hat die Vorgabe, einen hohen Wirkungsgrad bei gleichzeitig hoher Betriebssicherheit zu erreichen. Mit den heute zur Verfuegung stehenden Rechenprogrammen ist eine entsprechende Optimierung realisierbar. Fuer ...

International Nuclear Information System (INIS)

On-power refuelling is an integral feature of PHWR units. The most notable aspect of refuelling system of 540 MWe PHWR (TAPP-3 and 4) is that the FM Head is based on rack and pinion mechanism for B-ram and C-ram of Ram assembly. Latch ram used during plug operations, is assembled in between B-ram and C-ram and is moved by a ballscrew driven by oil hydraulic motors. This unique design has been employed for the first time in a PHWR unit. In comparison, B-ram is ballscrew driven and C-ram is moved by heavy water hydraulic force in FM Heads of 220 MWe PHWR units. Over the years, a number of design improvements have been carried out in the 220 MWe Fuelling Machines to meet the challenge of increasing demands of higher refuelling rates. However, in 540 MWe unit, the average refuelling rate for an equilibrium core is nearly twice that of 220 MWe units. Apart from other assemblies in FM Head, the performance of Ram assembly plays a key role in meeting ...

International Nuclear Information System (INIS)

By 1970 the first edition of the ASME Code Section XI, Inservice Inspection of Nuclear Reactor Coolant Systems was published. From its inception, the Section XI inservice inspection scope was based on a fundamental risk-based selection process. In other words the inservice inspection scope included components where the consequences of a pressure boundary failure were high. Once the consequence significant system boundaries were established, inspections would then be performed at locations believed to be most susceptible service induced failure. Current Section XI requirements require that inspection locations be selected on the basis of peak stress and fatigue usage values contained in the Design Reports. These original stress calculations were designed to qualify a design and assure that the plant would provide reliable service throughout its design life. For the most part, the fatigue usage values in these reports do not provide an accurate ...

UK PubMed Central (United Kingdom)

Mechanism-based inhibition of cytochrome P450 (CYP) 3A4 is characterized by NADPH-, time-, and concentration-dependent enzyme inactivation, occurring when some drugs are converted by CYPs to reactive...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This short survey focuses on the main radiation-induced base lesions that have been identified within cellular DNA. For this purpose, sensitive assays that are aimed at measuring a few modifications per 10{sup 7} normal bases were set-up. In that respect high performance liquid chromatography - tandem mass spectrometry (CLHP-MS/MS) was found to be able to single out the formation of 9 oxidized nucleosides and two modified nucleo-bases out of the 70 oxidative base lesions that have been identified in model systems. As a striking result, it was found that in the DNA of {gamma}-irradiated human monocytes, the formamide-pyrimidine derivative of guanine is produced in a higher yield than the ubiquitous 8-oxo-7,8-dihydro-guanine damage, both arising from the same radical precursor. However, relatively high doses of ionizing radiation (> 20 Gy) have to be applied in order to detect ...

British Library Electronic Table of Contents (United Kingdom)

Phreatic groundwater pumping is affecting water availability for crops in areas with a shallow water table. This can reduce crop growth and so affect farm income. There is a need for a generic and transparent method to assess the agricultural damage caused by water table drawdown. This paper proposes such a method that consists of 'damage tables' relating agricultural production losses to the groundwater regime for different soil/crop combinations found in Northern Belgium. The damage tables are constructed based on numerous simulations with the agrohydrological model SWAP, in which the bottom boundary conditions are gradually changed to reflect different groundwater regimes. The credibility of the resulting metamodel is assessed in three ways: using (1) field data, (2) an existing local e...

International Nuclear Information System (INIS)

The analysis for priority rankings of the recommendations to reduce the total core damage frequency (CDF) of Wolsong nuclear power plant units 2/3/4 was performed in this paper. In order to derive the recommendations, the sensitivity analysis of CDF on which major contributors effect was performed based on the accident quantification results during Level 1 probabilistic safety assessments (PSA). Priorities were ranked in the way that compares the CDF reduction rate with the efforts required to implement those recommendations using risk matrix.

Energy Technology Data Exchange (ETDEWEB)

GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion ...

Energy Technology Data Exchange (ETDEWEB)

The objectives of the research in the field of epidemiology , performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study. For radiobiology, the main objectives are: (1) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phase of its development, (2) to assess the genetic risks of maternal exposure to ionizing radiation, (3) to elucidate the mechanisms by which damage to the brain and mental retardation are caused in man after prenatal irradiation. The main achievements in these domains for 1997 are presented.

International Nuclear Information System (INIS)

It is shown that low-frequency elastic vibrations of near-surface planar defects cause high-frequency ultrasonic radiation in surrounding air. The frequency conversion mechanism is concerned with contact nonlinearity of the defect vibrations and provides efficient generation of air-coupled higher-order ultraharmonics, ultrasubharmonics, and combination frequencies. The nonlinear air-coupled ultrasonic emission is applied for location and high-resolution imaging of damage-induced defects in a variety of solid materials.

CERN Document Server

The CLIC (Compact Linear Collider) high-gradient RF structure testing program has been carried out in order to gain insight into the physical processes involved in RF breakdown, determine the mechanisms that limit gradient and produce damage so that technical concepts can be developed which allow higher accelerating gradients. Two main paths towards higher gradients have emerged from this program, and the performances of two new structures which incorporate them are presented.

UK PubMed Central (United Kingdom)

Oxidized DNA bases, particularly 7,8-dihydro-8-oxoguanine (8-oxoG), are endogenously generated in cells, being a cause of carcinogenic mutations and possibly interfering with gene expression. We found...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Current advanced CMOS source/drain engineering involves the use of amorphizing implants with 3D geometry. Upon annealing, the induced transient enhanced diffusion (TED) can only be accurately predicted if the amorphized region is correctly modeled, as well as the formation and evolution of extended defects, particularly 3 1 1's and dislocation loops. In addition to the extended defects, already modeled in the atomistic kinetic Monte-Carlo simulator DADOS, we have developed a physically based modeling approach for the implant-induced damage build-up, amorphization and recrystallization, suitable to handle device-size process simulation. It is based on amorphous pockets (3D, irregular shape agglomerates of an arbitrary number of interstitials and vacancies, plus trapped impurities) with a size-dependent activation energy for recombination. The model is able to reproduce experimental aspects like the crystal-amorphous ...

Energy Technology Data Exchange (ETDEWEB)

A series of cyclic strain controlled tests have been carried out at 600/sup 0/C on three high temperature austenitic iron-based alloys, AISI type 316 stainless steel, Alloy 800 H and Sandvik 253 MA. The tests were carried out under constant total strain control using a constant strain rate of 0.005 s/sup -1/. By considering the changes in modulus throughout the life of each specimen it was found that damage evolution could be successfully predicted as a function of plastic strain range despite the fact that each alloy had been chosen because of a different stress response at 600/sup 0/C. Although each alloy accumulated fatigue damage in a similar manner the longer lives of Sandvik 253 MA and Alloy 800 H at a given total strain range were due to a smaller plastic strain component and a reduced stage I crack propagation rate. In the 253 MA alloy, slip was predominantly planar with some cells occasionally forming at high ...

Energy Technology Data Exchange (ETDEWEB)

Slow, unexpected displacements have been experienced in most pressurized water reactor (PWR) surge lines. Sometimes, these displacement lead to gap closure at the pipe whip restraints. These movements occur because of thermal stratification. This movement has the potential to increase stresses to valves, which may exceed the material yield stress. To understand this phenomenon, Framatome, Commissariat a l'Energie Atomique, and Electricite de France have undertaken large programs for the study of (1) thermal-hydraulic tests with a half-scale Plexiglas surge line, (2) thermal-hydraulic computations of permanent states and transients with a two-dimensional model, and (3) mechanical analysis of displacements and computation of fatigue damage due to stratification. This paper deals with the last subject. Avoiding stratification in piping by process modifications is difficult because of the high flow rate needed. Alternative solutions for ...

Energy Technology Data Exchange (ETDEWEB)

The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.

International Nuclear Information System (INIS)

A Y-Mg-Si-Al-O-N glass was submitted to swift heavy-ion bombardment at GANIL (Caen, France) and the influence of irradiation on the mechanical properties was studied. The mechanical properties of the glass were characterized both before and after irradiation. Changes in hardness, elastic modulus and fracture toughness of the near-surface irradiated layer were determined using indentation techniques. SRIM calculations allowed to estimate the ions penetration range and the energy deposition relative to electronic and nuclear interactions, which can be correlated to the experimental damaged depth. Meyer's hardness and Young's modulus decrease by about 30 %, while fracture toughness is increased by more than 40 %. (authors)

Energy Technology Data Exchange (ETDEWEB)

AISI 316L stainless steel was welded by the electron beam (EB) and laser techniques. Microstructural characteristics, hardness profile, creep rupture properties and creep damage of the welds were investigated. Fully austenitic microstructure was obtained in the two welds. The solidification structure of the welds consisted of the cellular and equiaxed dendrites. The creep rupture lives of the two welds were almost the same, and they were reduced by a factor of about two compared to the base metal. Moreover, the rupture elongation of the welds was lower than that of the base metal. Creep damage was observed in the ``parting`` region of the welds and in the heat-affected zone (HAZ), respectively. Final creep fracture occurred in the ``parting`` region of the welds. (orig.).

British Library Electronic Table of Contents (United Kingdom)

North American design codes are now committed to the development of load and resistance factor design (LRFD) for reinforced soil structures including internal stability limit states. Reliability-based analysis is required to carry out these calibrations. A framework for LRFD calibration has been proposed by the writers that requires bias statistics for load and resistance terms for each limit state function. In this paper the formulation of the limit state for reinforcement tensile rupture is developed and the component strength-reduction bias statistics identified. The paper describes how to compute bias statistics from project-specific installation damage trials for use in reliability-based design for the reinforcement rupture limit state or using data from multiple sources for LRFD cali...

International Nuclear Information System (INIS)

Using a new approach to quaternion mechanics based on De Broglie waves, it is shown that such a theory describes tachyons and that the quantum theory of tachyons should be a quaternionic one. (U.K.).

Energy Technology Data Exchange (ETDEWEB)

The paper evaluates standardization of regulations on safety of electrical equipment for underground coal mines in the USSR. Factors increasing hazards of electrical failures of equipment in underground coal mines are analyzed: reduced lighting, increased humidity and dusts, damage caused by falling rocks or damage during haulage in underground workings, installation of electrical equipment in places easily accessible to untrained personnel. Standards on safety of electrical equipment for underground coal mining valid in the USSR are reviewed: the PIRNEh regulations on production of electrical equipment for coal mines developed by the VNIIVEh Institute, and the GOST national standards. International cooperation within the COMECON on safety of mining electrical equipment (the Interelectro Committee of the COMECON) is described. Certification of electrical equipment for coal mines is discussed on the example of electrical insulation types used in ...

International Nuclear Information System (INIS)

Short communication.

Science.gov (United States)

In this paper we propose a method for construction of feed-forward neural classifiers based on regularization and adaptive architectures. Using a penalized maximum likelihood scheme, we derive a modified form of the entropic error measure and an algebraic estimate of the test error. In conjunction with optimal brain damage pruning, a test error estimate is used to select the network architecture. The scheme is evaluated on four classification problems. PMID:12662736

International Nuclear Information System (INIS)

This report briefly describes the studies on the mechanism of in vivo DNA repairing by the author in Research Reactor Institute, Kyoto Univ. for the past 30 years. First, the ability of UV radiation to induce transformation was investigated with viral DNA. The formation of thymine-thymine dimer was found harmful to organisms and such dimers were removable by UV-radiation at a low frequency. The mutability was determined in three different E.coli strains with mutator gene, mutT, mutS or mutL. The ability to excise 8-oxoguanin developed in primer DNA was deficient in mutT and miss-pairing left after DNA replication could not be recovered in mutL and mutS strains. Further, DNA repairing mechanism was investigated in other microorganisms; single-strand cleavage caused by exposure to BNCB radiation (boron-neutron-captured beam) could not be repaired in E. coli. Whereas for Deinococcus radiodurans, of which survival rate was not decreased by ...

Energy Technology Data Exchange (ETDEWEB)

The purpose is to define sustainable economic development in the context of nonrenewable resources and to examine the changing nature of reclamation over time. Sustainable development is development that ensures the present utilization of resources and the environment does not damage prospects for their use by future generations. Polls show that the public is demanding higher environmental standards. One mechanism for achieving sustainable economic development for the nonrenewable resource sector is through reclamation. The Alberta government`s approach to reclamation is reviewed to show how reclamation and sustainable government are linked together. The history of reclamation legislation in Alberta is summarized. 10 refs.

International Nuclear Information System (INIS)

The post (neutron) -irradiation high-temperature tensile and creep-rupture properties, deformation and fracture characteristics of austenitic alloys, particularly solution annealed Type 316 steel, are surveyed and correlated with the damage structures developed as a function of irradiation temperature (and dose). The mechanisms proposed to explain the irradiation-induced changes in properties and behaviour are summarised. The factors responsible for the observed differences in the post-irradiation and 'in-reactor' creep-rupture properties and behaviour of an austenitic steel are discussed in terms of the helium gas and stress driven growth of small intergranular bubbles and the atom plating associated with their growth and coalescence. (author).

International Nuclear Information System (INIS)

Nanoindentation was performed on a Mo-alloy single crystal to investigate effects of focused ion beam (FIB) milling on mechanical behavior. On a non-FIB-milled surface, pop-ins were observed on all load-displacement curves corresponding to a transition from elastic to plastic deformation. Similar pop-ins were not detected on surfaces subjected to FIB milling. This difference indicates that FIB milling introduces damage that obviates the need for dislocation nucleation during subsequent deformation. A second effect of FIB milling is that it increased the surface hardness. Together, these effects could be the source of the size effects reported in the literature on micropillar tests.

International Nuclear Information System (INIS)

An integrated approach to the modelling of hydrogen assisted failure in 316L steel is presented. The approach includes experimental, fractographic, numerical and theoretical analysis of the phenomenon. The physical adequacy of the mechanical models of hydrogen embrittlement (notch extension model and notch cracking model) is discussed by comparing the virtual damage depth (theoretical) predicted by the models with the embrittled zone (microphysical) measured in the fractographic analysis by scanning electron microscopy. In addition, a numerical modelling of hydrogen diffusion is performed, concluding that bulk diffusion is not important in hydrogen embrittlement of 316L steel, so that hydrogen transport accelerated by the microdamage itself should be taken into account. (orig.)

Science.gov (United States)

The Seismic Risk Explorer, an extension for ArcGIS Desktop developed by cedim AG, is a tool for computing the seismic risk, i.e. damage on residential buildings and thereby caused monetary losses for earthquake scenarios. It is based on the research results of the CEDIM (Center for Disaster Management and Risk Reduction Technology) research center, located at the Karlsruhe Institute of Technology (KIT) and the GeoForschungsZentrum (GFZ) in Potsdam. With this software tool seismic scenarios can be simulated for a given magnitude, depths and location. The seismic intensity, the resulting mean damage ratio for residential buildings and the seismic risk, expressed as the monetary loss caused by an earthquake can be computed downscaled to communities, postcode areas or even single buildings. Interested end-users are especially insurance companies, but also public authorities which may use the tool for risk management issues.

International Nuclear Information System (INIS)

Staircase current-voltage (I-V) characteristics, observed at 77 K in narrow 2DEG channels irradiated by a single line scan of a focused ion beam (FIB), is reported in detail. These staircases are interpreted as evidence of single electron tunneling through a naturally occurring specific Coulomb island in the random potential fluctuations created by FIB damage. Clear comparison is made between the I-V's taken from wide channels and those from narrow channels. Based on orthodox calculations of the I-V characteristics, it is shown that highly asymmetric tunnel junctions are needed to explain our data. This is consistent with the random nature of the potential landscape in the FIB damaged region. (author).

British Library Electronic Table of Contents (United Kingdom)

Identifying gear damage categories, especially for early faults and combined faults, is a challenging task in gear fault diagnosis. This paper proposes a new multidimensional hybrid intelligent diagnosis method to identify different categories and levels of gear damage automatically. In this method, Hilbert transform, wavelet packet transform (WPT) and empirical mode decomposition (EMD) are performed on gear vibration signals to extract additional fault characteristic information. Then, multidimensional feature sets including time-domain, frequency-domain and time-frequency-domain features are generated to reveal gear health conditions. Multiple classifiers based on several classification algorithms and input features are combined with genetic algorithm (GA). Because of the use of multidim...

International Nuclear Information System (INIS)

The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could be demonstrated after ...

British Library Electronic Table of Contents (United Kingdom)

Modifications of the structure and mechanical properties in LiF crystals irradiated with MeV-energy Au ions have been studied using nanoindentation, atomic force microscopy and optical spectroscopy. The nanostructuring of crystals under a high-fluence irradiation (above 1013 ions/cm2)?was?observed. Nanoindentation tests show a strong ion-induced increase of hardness (up?to 150?200%), which is related to the high volume concentration of complex color centers, defect aggregates, dislocation loops and grain boundaries acting as strong barriers for dislocations. From the?depth profiling of the hardness and energy loss it follows that both nuclear and electronic stopping mechanisms of MeV Au ions contribute to the creation of damage and hardening. Whereas the electronic stopping is dominating i...

Energy Technology Data Exchange (ETDEWEB)

A strong effort is currently being devoted to the investigation of defects and diffusion phenomena in silicon. This effort is not only driven by the stringent technological requirements for the processing of integrated circuits of increased complexity and miniaturization, but also by the lack of fundamental understanding of many of the critical parameters and mechanisms involved. Experimental and theoretical investigations are needed to identify the properties of the defects, the mechanisms of impurity diffusion and the strength of impurity-defect, defect-defect, and impurity-impurity interactions. This volume provides a unique and interdisciplinary forum for the discussion of experimental, theoretical and applied aspects of defects and diffusion phenomena in silicon. Topics include: defect properties and diffusion phenomena in silicon; experimental and theoretical assessments of defect properties; transient-enhanced diffusion and dopant ...

Energy Technology Data Exchange (ETDEWEB)

{gamma} Ti-Al have a higher temperature potential than commercial titanium alloys and a 50 percent lower density than nickel base superalloys. Application temperatures in aircraft turbines are 750 C and above. The authors investigated the high-temperature performance of {gamma} TiAl, i.e. isothermal high-temperature fatigue and the type and importance of damage. LCF experiments were made in the temperature range of brittle/ductile transition in air and vacuum. Damage mechanisms were characterized by microstructural investigations. [German] Unter den modernen Hochtemperaturwerkstoffen kommt den Legierungen auf Basis von {gamma}-TiAl eine zunehmend wichtige Bedeutung zu, da diese Werkstoffe ein hoeheres Temperaturpotential als alle kommerziellen Titanlegierungen haben und eine im Vergleich zu den Nickelbasis-Superlegierungen um ca. 50% geringere Dichte aufweisen. TiAl-Werkstoffe, die z.B. fuer Schaufeln ...

Energy Technology Data Exchange (ETDEWEB)

One of the main factors that require special attention in a pipeline construction is the cold bending process, once depending on the region that the line will be installed the number of bends may achieve 75%, as it was observed in some areas during Campinas-Rio pipeline construction. A study was carried out to evaluate the X80 cold bending operational parameters in order to make viable the use of high strength pipes in the construction of onshore pipelines. For this analysis three pipes of 34 inches x 0.750 inches had been cold bended, the operation was carried out using a hydraulic equipment with punches applications along the pipe, recording the correspondent angles related to the elastic and plastic deformations in order to assess the material spring-back. After the bending process, samples of the weld, extrados and intrados were subjected to mechanical and metallographic tests, as well as performed dimensional inspection of the pipes. It was possible to obtain ...

International Nuclear Information System (INIS)

Geological carbon dioxide capture and storage (CCS) is currently seriously considered for addressing, in the near term, the problem of climate change. CCS technology is available today and is expected to become an increasingly affordable CO2 abatement alternative. Whereas the rapidly growing scientific literature on CCS as well as experimental and commercial practice demonstrate the technological and economic feasibility of implementing this clean fossil fuel option on a large scale, relatively little attention has been paid so far to the risks and environmental externalities of geological storage of CO2. This paper assesses the effects of including CCS damage costs in a long-term energy scenario analysis for Europe. An external cost sensitivity analysis is performed with a bottom-up energy technology model that accounts not only for CCS technologies but also for their external costs. Our main conclusion is that in a business-as-usual scenario (i.e. without climate ...

International Nuclear Information System (INIS)

This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of ?9%Cr-steels irradiated in the range of 50-600 deg. C up to 50 dpa and with a He-content up to 5000 appm. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high ...

International Nuclear Information System (INIS)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5x10"1"2 to 1x10"1"4/cm"2 evolves into a distribution of #left brace#311#right brace# interstitial agglomerates during the initial annealing stages at 670 endash 815 degree C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the ...

KoreaScience (Korea)

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Science.gov (United States)

According to the California Earthquake Authority, only about 12% of current California residences are covered by any form of earthquake insurance, down from about 30% in 1996 following the 1994, M6.7 Northridge earthquake. Part of the reason for this decreasing rate of insurance uptake is the high deductible, either 10% or 15% of the value of the structure, and the relatively high cost of the premiums, as much as thousands of dollars per year. The earthquake insurance industry is composed of the CEA, a public-private partnership; modeling companies that produce damage and loss models similar to the FEMA HAZUS model; and financial companies such as the insurance, reinsurance, and investment banking companies in New York, London, the Cayman Islands, Zurich, Dubai, Singapore, and elsewhere. In setting earthquake insurance rates, financial companies rely on models like HAZUS, that calculate on risk and exposure. In California, the process begins with an official ...

Energy Technology Data Exchange (ETDEWEB)

The current Risk-informed Regulation (RIR) framework employs both a Level 1 Core Damage Frequency (CDF) and a Level 2 Large Early Release Frequency (LERF) as two surrogate measures for the plant risk. For their use in making regulatory decisions for the plant risk, it has been required to maintain an appropriate level of quality for the plant risk models. The first step for this purpose is to evaluate the quality of the PSA model in a qualitative or quantitative manner. Recently, a similar type of quality evaluation has been made for the KSNP Level 1 PSA model based on an ASME PRA Standard for the RIR application, but not for the corresponding LERF model. The main objective of this paper is to provide the ASME PRA Standard-based evaluation result for the existing KSNP Level 2 LERF model and the insights obtained from the evaluation process.

Energy Technology Data Exchange (ETDEWEB)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during initial annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, the authors have used B doping marker layers in Si to probe the injection of interstitials from near-surface, non-amorphizing Si implants during annealing. The in-diffusion of interstitials is limited by trapping at impurities and has an activation energy of {approximately}3.5 eV. Substitutional C is the dominant trapping center with a binding energy of 2--2.5 eV. The high interstitial supersaturation adjacent to the implant damage drives substitutional B into metastable clusters at concentrations below the B solid solubility limit. Transmission electron microscopy shows that the interstitials driving TED are emitted from {l_brace}311{r_brace} defect clusters in the damage region at a rate which also exhibits an ...

Energy Technology Data Exchange (ETDEWEB)

Multilayer mirrors for the extreme ultraviolet (EUV) are keyelements for numerous applications of coherent EUV sources such as newtabletop lasers and free-electron lasers. However the field ofapplications is limited by the radiation and thermal stability of themultilayers. Taking into account the growing power of EUV sources thestability of the optics becomes crucial. To overcome this problem it isnecessary to study the degradation of multilayers and try to increasetheir temporal and thermal stability. In this paper we report the resultsof detailed study of structural changes in Sc/Simultilayers when exposedto intense EUV laser pulses. Various types of surface damage such asmelting, boiling, shockwave creation and ablation were observed asirradiation fluencies increase. Cross-sectional TEM study revealed thatthe layer structure was completely destroyed in the upper part ofmultilayer, but still survived below. The layers adjacent tothe substrateremained intact even ...

Energy Technology Data Exchange (ETDEWEB)

Swift heavy ion-solid interaction leads in volume to track creation and on the surface to the ejection of particles into the vacuum. To learn more about initial mechanisms of track formation, we are focused on the sputtering of uranium dioxide by fast heavy ions. This present study is exclusively devoted to the influence of the electronic stopping power on the emission of neutral particles and especially on their angular distribution. These measurements are completed by those of the ions emitted from UO{sub 2} targets bombarded with swift heavy ions. The whole experimental results give access to: i) the nature of the sputtered particles; ii) the charge state of the emitted particles; iii) the direction of ejection of the sputtered particles ; iv) the sputtering yields deduced from the angular distributions. These results are compared to the prediction of the sputtering models proposed in the literature and it seems that the supersonic gas flow model is well suited ...

Energy Technology Data Exchange (ETDEWEB)

Chicken embryos were x-irradiated in ovo with 5-30 cGy (=priming dose) at the 13th-15th day of development. After 3-48 h, brain- and liver-cell suspensions were x-irradiated in vitro with (challenge) doses of 4-32 Gy. Significantly less radiation damage was observed when the radiation response was measured by scheduled DNA synthesis, nucleoid sedimentation and viscosity of alkaline cell lysates 12-36 h after the priming exposure. In vivo, pre-irradiation with 10 cGy enhanced regeneration as evidenced by the DNA content of chicken embryo brain and liver 24 h following a challenge dose of 4 Gy. From nucleoid sedimentation analyses in brain and liver cells immediately after irradiation with 16 Gy and after a 30-min repair period in the presence of aphidicolin, dideoxythymidine and 3-aminobenzamide or in the absence of these DNA repair inhibitors, it is concluded that a reduction of the initial radiation damage is the dominant ...

CERN Document Server

We present a detailed analysis of the self-organization phenomenon in which the stylized facts originate from finite size effects with respect to the number of agents considered and disappear in the limit of an infinite population. By introducing the possibility that agents can enter or leave the market depending on the behavior of the price, it is possible to show that the system self-organizes in a regime with a finite number of agents which corresponds to the stylized facts. The mechanism to enter or leave the market is based on the idea that a too stable market is unappealing for traders while the presence of price movements attracts agents to enter and speculate on the market. We show that this mechanism is also compatible with the idea that agents are scared by a noisy and risky market at shorter time scales. We also show that the mechanism for self-organization is robust with respect to ...

Science.gov (United States)

The knowledge of wound ballistics and of wounding mechanisms is mandatory for the radiologist to interpret the CT findings of gunshot wounds. The severity of a bullet wound depends on the characteristics of the tissue it goes through, i.e., tissue elasticity, density, thickness of the wounded body part, the type of tissue, its specific gravity, internal cohesiveness and anatomical relationships, as well as on missile characteristics, i.e., mass, shape, fragmentation and deformation. Bullet velocity is certainly a major factor in wounding, but it is only one factor. Two major wounding mechanisms exist the crushing of the bullet-struck tissue (forming the permanent cavity) and radial stretching (forming a temporary cavity). Bullet "yaw" is defined as the angle between the long axis of the bullet and its flight path. The yaw is directly proportional to tissue crushing and stretching: the wider the yaw, the most severe tissue crushing and ...

Energy Technology Data Exchange (ETDEWEB)

Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of nine n-alkanes larger than n-heptane, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on our previous mechanisms for the primary reference fuels n-heptane and iso-octane, using the reaction class mechanism construction first developed for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane ...

Science.gov (United States)

III--V based devices such as field effect transistors, heterojunction bipolar transistors, and lasers often have surface leakage and thermal degradation problems due to surface states which pin the Fermi level to the midgap. Sulfur based passivation processes are known to improve device performance by altering surface-state densities. We have developed a voltage-controlled anodic sulfur passivation scheme using Na[sub 2]S dissolved in ethylene glycol. Our process has repeatedly produced a [similar to]25% improvement in peak output power near the catastrophic damage limit in visible ([lambda]=670 nm) AlGaInP edge-emitting lasers. The threshold current density before and after passivation, and the [ital I]--[ital V] characteristics before and after catastrophic failure, were essentially unchanged indicating that passivation raises the threshold for facet damage.

Energy Technology Data Exchange (ETDEWEB)

Effect of alcohol solvent in mixing process on process on the microstructure and sintering behavior of ceramic-based composites was inestigated in detail. The mixture of fine ceramic powders was prepared through the conventional ball-milling method with various alcohol media. The particle distributions of fine ceramic powders were strongly dependent on the kind of alcohol employed during ball-milling. Ceramic-based composites were fabricated by hot-pressing the mixture of fine ceramic powders. Their microstructures and some mechanical properties of the ceramic-based composites were evaluated. It was found that the viscosity of alcohol, surface tension and contat angle greatly affect the sinterbility and some of the mechanical properties of ceramic-based somposites. (author)

International Nuclear Information System (INIS)

This paper discusses the mechanisms of gas breakdown at low values of pressure and inter-electrode gap, i.e. in the vicinity of the Paschen minimum. In this area of pressure and inter-electrode gap values, breakdown occurs either through gas or vacuum mechanisms, and also the so called anomalous Paschen effect appears. Electrical breakdown of electropositive, electronegative and noble gases has been investigated theoretically, experimentally and numerically. Based on the results obtained, regions in which particular breakdown mechanisms appear have been demarcated. Special attention has been devoted to the anomalous Paschen effect as well as to the avalanche vacuum breakdown mechanism.

International Nuclear Information System (INIS)

In this work, the effects of the focus ion beam (FIB) milling process on the optical properties of semiconductor nanostructures were investigated. With this aim, a sensitive materials system based on InGaAs/GaAs quantum dots with well known and excellent optical properties was selected for the FIB treatment. The FIB technique was used to locally remove a metallic mask deposited on top of the quantum dot sample. The photoluminescence (PL) signal, collected from the circular openings, was used to infer the possible damage effects of the ion beam on the properties of the dots.

British Library Electronic Table of Contents (United Kingdom)

Major similarities between robustness assessment and seismic design exist, and significant information can be brought from seismic design to robustness design. As will be discussed, although some methods and limitations considered in seismic design can improve robustness, the capacity of the structure to sustain limited damage without disproportionate effects is significantly more complex. In fact, seismic design can either improve or reduce the resistance of structures to unforeseeable events, depending on the structural type, triggering event, structural material, among others. Based on a case study, the influence of redundancy and ductility on the seismic behavior and robustness of a long-span timber structure is assessed.

International Nuclear Information System (INIS)

An analysis system for the long-term mechanical behavior of barrier materials (MACBECE: Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials) was developed in order to improve the reliability of the evaluation of the hydraulic field which is one of the important environmental conditions in the safety assessment of the TRU waste disposal. MACBECE is the system that calculates the deformation of barrier materials using their chemical property changes as inputs, and subsequently calculates their hydraulic conductivity taking both their chemical property changes and deformation into consideration. By using MACBECE, the long-term deformation and the transition of hydraulic field for the round-type disposal cavities were evaluated, assuming some sets of chemical evolution data as input. Based on the analysis result, it is considered ...

Energy Technology Data Exchange (ETDEWEB)

The loosening equipment consists of a base machine and four-link suspension mechanism which is a cross frame with loosening gear connected to the base machine by universal hinges. In order to improve the reliability of the machine, the drive of transverse shifting in the cross frame is made of symmetrically arranged, shock-absorbing, hydraulic cylinders which are connected by additional universal hinges to the base machine and the lower pull rods. The design of the loosening machine guarantees its reliable operation on soil with significant quantity of hard inclusions.

International Nuclear Information System (INIS)

In order to prevent corrosion failures of machines and structures, it is desirable to know in advance when the corrosion damage will take place, and appropriate measures are needed to mitigate the damage. The corrosion predictions are needed both at development as well as operational stage of machines and structures. There are several forms of corrosion process through which varying degrees of damage can occur. Under certain conditions these corrosion processes at alone and in other set of conditions, several of these processes may occur simultaneously. For a certain type of machine elements and structures, such as gears, bearing, tubes, pipelines, containers, storage tanks etc., are particularly prone to pitting corrosion which is an insidious form of corrosion. The corrosion predictions are usually based on experimental results obtained from test coupons and/or field experiences of similar machines or ...

International Nuclear Information System (INIS)

The potential application of radioisotopes are not discussed in this review of trypanosome pathogenesis in cattle. Initially, structural changes in the lymphoid system are characterized by marked proliferation and germinal centre formation, whereas in long-standing infections the lymphoid organs become depleted. These changes appear associated with immunodepression. Anaemia dominates the clinical disease syndrome in bovine trypanosomiasis. It develops with the onset of parasitaemia and is largely haemolytic, resulting from increased red blood cell destruction by phagocytosis. Several factors may be involved in this process including haemolysins produced by the trypanosome, immunological mechanisms, fever, disseminated intravascular coagulation and an expanded and active mononuclear phagocytic system. During this phase of the disease, cattle respond well to chemotherapy. However, in later phases of the disease, when trypanosomes cannot be detected, the anaemia ...

Energy Technology Data Exchange (ETDEWEB)

Nickel base superalloys for turbine construction are exposed to maximum thermal and mechanical stresses. owing to a change of materials by one of the project partners, the project only comprised analyses of the alloy CMSX-6. Isothermal tensile and fatigue tests provided basic data on the alloy. Thermomechanical fatigue tests showed that material life and microstructural changes are clearly, and to an extreme extent, dependent on the type of combination of the two stress factors `temperature interval` and `total strain amplitude`, while the damage to the material tends to be a function of the maximum stresses for a given stress path. On the one hand, these results make it possible to obtain information real stresses from the structures of real blades. On the other hand, constructional measures can be taken in order to better adapt the stresses to which alloys are exposed to their characteristic potential. (orig./AKF) ...

Energy Technology Data Exchange (ETDEWEB)

Under the direction of the NASA-Glenn Research Center, the Edison Welding Institute (EWI) in Columbus, OH performed a series of non-fusion joining experiments to determine the feasibility of joining refractory metals or refractory metal alloys to Ni-based superalloys. Results, as reported by EWI, can be found in the project report for EWI Project 48819GTH (Attachment A, at the end of this document), dated October 10, 2005. The three joining methods used in this investigation were inertia welding, magnetic pulse welding, and electro-spark deposition joining. Five materials were used in these experiments: Mo-47Re, T-111, Hastelloy X, Mar M-247 (coarse-grained, 0.5 mm to several millimeter average grain size), and Mar M-247 (fine-grained, approximately 50 {micro}m average grain size). Several iterative trials of each material combination with each joining method were performed to determine the best practice joining method. Mo-47Re was found to be joined easily to ...

Energy Technology Data Exchange (ETDEWEB)

The author explains current developments in high voltage cable technology and subsequently describes problems inherent in its application, from the users viewpoint, in municipal electricity supply. The planning of a high voltage cable network and the selection of a specific type of cable are not only dependent on the typical properties of various cables but to a major degree also on the feasible laying technique, the power transmitted, the costs, the stellation treatment of the high voltage network, the acceptance requirement, the inductive influence from telecommunication cable, thermal influences from the environment, eventual safeguards from mechanical and chemical damage to the network, frequency of failure and surveillance and breakdown location. In conclusion, the author portrays potential developments in the fields of high and maximum voltage cable from the perspectives of today.

International Nuclear Information System (INIS)

The possible corrosion damage is discussed of the CrNi and CrNiMo types steels used as structural materials in WWER type nuclear power plants. It includes point and slot corrosion, corrosion cracking and corrosion fatigue as well as corrosion denting. Also discussed are test procedures that simulate operating conditions and are used for assessing the properties of metallurgical products (sheets and tubes) used in nuclear power engineering. Briefly described is a system for testing the said products in an aqueous medium while keeping the test parameters in a narrow range for a long time. Under the defined temperature, pressure and corrosion medium composition, the test specimens in this system can mechanically be loaded, both statically and dynamically or a temperature gradient can be produced at the tube-tube plate joint. (Z.M.). 1 fig., 1 tab., 10 refs.

International Nuclear Information System (INIS)

Penetrating liver wounds are related to many causes and rank second after blunt abdominal and liver trauma. In this report are examined the clinical and radiological findings of personal series of patients with penetrating trauma, especially by firearms and stab and cut wounds. It will also tried to define the diagnostic workup of these traumas, which is especially based on CT signs of liver damage and associated changes and which is of basic importance for following treatment, both surgical or conservative. In the last seven years it was retrospectively reviewed 31 cases of penetrating liver trauma. The patients were 19 men and 12 women, ranging in age 18 to 73 (mean 42), with penetrating liver injuries from firearms (16 patients) and stab (9 cases) wounds; 6 patients had injuries from different cases. Abdominal CT was carried out in emergency with the CT Angiography (CTA) technique in all patients. In the patients with suspected chest and ...

UK PubMed Central (United Kingdom)

There has been great interest in understanding the methods by which collagen-based load-bearing tissue is constructed, grown and maintained in vertebrate animals. To date, the responsibility for this...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This course is based upon lectures in physics given by Professor Feynman at the California institute of technology during 1961 and 1962. This volume is dedicated to quantum physics, semiconductors, symmetry and advanced principles of physics.

Energy Technology Data Exchange (ETDEWEB)

A dust extraction system removes the contaminated air at source by means of a hood. The extraction system for dust is essentially a ducted air system that prevents excessive employee exposure to dust in the working zone. The four major mechanisms that remove the contaminants in an extraction system are: - capture of contaminants by hoods - transport of contaminated air in duct network - separation of dust in the collector - exhaust of clean air through stack. The current methods of design are based on empirical relations, multi-variable tables, graphs and nomographs that have been derived from the principle of fluid mechanics and particle dynamics. However, the empirical formulae, tables and graphs are used in different geographical locations of the world having different environmental conditions and geo-characteristics of dust particles. Therefore, it is required to establish a rational design method that will be ...

Energy Technology Data Exchange (ETDEWEB)

Scheme of theoretical method of molecular configuration definition for small organic molecules in solution has been presented. The method bases on measurements of nuclear Overhauser effects for proton-proton interactions and molecular mechanics calculations. 3 refs, 1 fig.

International Nuclear Information System (INIS)

We exploit theoretically a class of rectangular cylindrical devices for noise shielding by using acoustic metamaterials. The function of noise shielding is justified by both the far-field and near-field full-wave simulations based on the finite element method. The enlargement of equivalent acoustic scattering cross sections is revealed to be the physical mechanism for this function. This work makes it possible to design a window with both noise shielding and air flow. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

British Library Electronic Table of Contents (United Kingdom)

Based on the Morlet wavelet transformation and Wigner-Ville distribution (WVD), we present a wind turbine fault diagnosis method in this paper. Wind turbine can be damaged by moisture absorption, fatigue, wind gusts or lightening strikes. Due to this reason, there is an increasing need to monitor the health of these structures. Vibration analysis is the best-known technology applied in wind turbine condition monitoring, in which the time-frequency analysis techniques such as Wigner-Ville distribution (WVD) are widely used. Theoretically WVD has an infinite resolution in time-frequency domain. For early wind turbine fault signals, however, there are two main difficulties in WVD analysis. One is strong noise signals in the background and the other is cross terms in WVD itself. In this paper,...

International Nuclear Information System (INIS)

In defining criteria for good protection against ionizing radiation, it is important to assess quantitatively the likely risk of any radiation exposure. The 'somatic' risks to the individual result mainly from induction of cancer in the organs irradiated, and these risks can now be estimated on the basis of numerous detailed epidemiological surveys of exposed human populations. Estimates of the risk of hereditary effects, from genetic changes induced in germ cells, are based largely on the frequency with which such effects are induced in other species. In both cases the risk at very low dose can be inferred using knowledge of the way in which radiation damage is caused in tissues. Coherent systems of radiation protection are based on a restriction of doses to the whole body and to individual organs, such that the induction of cancer and genetic harm is infrequent, and the threshold dose for causing other, 'non-stochastic', ...

International Nuclear Information System (INIS)

The authors summarize the significant dose-related effects on brain development which have emerged largely within the last six years of study of prenatally exposed A-bomb survivors. The results are described primarily in terms of the DS86 estimates and differences between these and the older T65DR dose estimates are discussed. The severe mental retardation sample was based on 1598 individuals taken from the PE-86 sample, and the intelligence test scores considered from the same sample involved 1673 children. The authors also discuss some of the recent neurobiological developments that appear relevant to an understanding of the biological bases of dose-related events observed, and suggest future research that may contribute either to further delineation of exposure consequences or to the explanation of the cellular and molecular origins of observed effects. (UK).

Energy Technology Data Exchange (ETDEWEB)

In general, macroscopic material failure is a manifestation of irreversible changes at the microscopic level. Many tissues, which may appear to be macroscopically homogeneous, are, at a fundamental microscopic level, a composite material. For example, cornea is composed of a hyaluronic acid matrix in which layers of collagen fibers are overlaid in a crossing pattern. The points where the collagen fibers intersect are potential nucleation sites for microscopic defects, which under the action of tensile stress, nucleate, grow and coalesce to form macroscopic failure planes, or spall planes. Using a model based on microstructural evolution, this paper examines the failure process during photoablation. Specifically, the paper describes a physically motivated, micromechanical model based on the nucleation and growth of spherical voids. This model is then used to simulate photoablation of cornea. Potential for using this model to predict the stress ...

Energy Technology Data Exchange (ETDEWEB)

Policy makers are turning to market-based mechanisms to engender innovative ways of reducing polluting air emissions. As with any emerging market, environmental policies must be carefully crafted so that the institutions and incentives needed to form working markets are developed. Attention must be paid to creating avenues for communities and other 'non-moneyed' or unorganised interests to be involved in the new market processes. This paper proposes a strategy to create sustainable, community-based methods to reduce polluting air emissions within the context of market-based incentive programs. By enabling communities to effectively participate in environmental solutions, they will truly be able to 'think globally, act locally'. (author)

International Nuclear Information System (INIS)

This paper presents the objective, scope, and status of the U.S. Department of Energy's Materials and Structures Program to develop a data base on mechanical properties of structural materials for out-of-core structures and components for LMFBRs. Information on the development of a reference data base on materials for the reactor system, reactor enclosure system, primary heat transport system, intermediate heat transport system, and steam generator system is included. In addition, the development of the data and analyses to account for the effects of temperature and stress, as well as water/steam, sodium, and radiation environments, is described. Plans for the development of alternative materials for future out-of-core applications are presented. (author).

Science.gov (United States)

Candoxin (PDB #1JGK), a three-finger neurotoxin from Bungarus candidus venom, inhibits post-synaptic neuromuscular and neuronal alpha7nACh-receptors, and induces delayed cell-death throughout the glial population. When applied to cultured human glial cell lines, candoxin (CDX) induced cell death in a concentration (EC(50) approximately 1muM) and time dependent manner. Results of TUNEL-histochemistry further confirm CDX-induced brain (hippocampus, frontal cortex, and temporal regions) damage when administered intracerebroventricularly (i.c.v) in adult mice. In this study, we explored differential gene expression profiles following exposure of human glial (Hs 683) cell lines to CDX at various time intervals using Affymetrix-GeneChips. By means of MAS and GeneSpring analyses, 105 genes whose expression was significantly (P<0.01) altered by at least 3-fold were selected. Results of the genome analysis reveal that the potential role of CDX at molecular level involves ...

Energy Technology Data Exchange (ETDEWEB)

The process of implementing a damage detection strategy for aerospace, civil and mechanical engineering infrastructure is referred to as structural health monitoring (SHM). Here damage is defined as changes to the material and/or geometric properties of these systems, including changes to the boundary conditions and system connectivity, which adversely affect the system's current or future performance. Our approach is to address the SHM problem in the context of a statistical pattern recognition paradigm (Farrar, Nix and Doebling, 2001). In this paradigm, the process can be broken down into four parts: (1) Operational Evaluation, (2) Data Acquisition, (3) Feature Extraction, and (4) Statistical Model Development for Feature Discrimination. When one attempts to apply this paradigm to data from 'real-world' structures, it quickly becomes apparent that data cleansing, normalization, fusion and ...

International Nuclear Information System (INIS)

Textured silicon nitride (Si_3N_4) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si_3N_4, with emphasis on the anisotropic and abnormal grain growth of #beta#-Si_3N_4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for #beta#-Si_3N_4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental ...

International Nuclear Information System (INIS)

Thermal diffusivity was measured with a laser flash method up to 2000 K for UO_2 pellets irradiated in a commercial reactor. Measurements were done on micro samples of disks (2 mm diameter) or regular prisms (1.5 or 2 mm square cross sections). Thermal diffusivity degraded on extending burnup in agreement with reported values for UO_2 irradiated in test reactors, and it showed hysteresis during the laser flash experiments. Thermal diffusivity began to recover above 750 K and almost completely recovered above 1400 K, which corresponded with the reported radiation damage recovery. The obtained data were in agreement with predictions applying the thermal conductivity expression for irradiated UO_2 proposed by Amaya and Hirai. The sample experiencing power ramp showed higher thermal diffusivity than that of the base irradiated sample and had no obvious hysteresis. This suggested that the radiation damage which degraded thermal ...

International Nuclear Information System (INIS)

The work scope of 'Biological Research for the Radiation Protection' had contained the research about ornithine decarboxylase and its controlling proteins, thioredoxin, peroxiredoxin, S-adenosymethionine decarboxylase, and glutamate decarboxylase 67KD effect on the cell death triggered ionizing radiation and H_2O_2(toxic agents). In this study, to elucidate the role of these proteins in the ionizing radiation (or H_2O_2)-induced apoptotic cell death, we utilized sensesed (or antisensed) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation and H_2O_2(or paraquat). We also investigated whether genisteine(or thiamine) may enhance the cytotoxic efficacy of tumor cells caused by ionizing radiation (may enhance the preventing effect radiation or paraquat-induced damage) because such compounds are able to potentiate the cell-killing or cell ...

Energy Technology Data Exchange (ETDEWEB)

A fractographic and numerical approach is presented to analyze hydrogen-plasticity interactions in pearlitic steel and to elucidate the main hydrogen transport mechanism in this material under triaxial stress states produced by notches. Fractographic analysis showed that the microdamage produced by the hydrogen was clearly detectable by scanning electron microscopy (SEM), through a specific microscopic topography associated with hydrogen effects (tearing topography surface or TTS). Numerical computations obtained by using an elastic-plastic finite element program gave the progressive spreading of the plastic zone, closely associated with the movement of dislocations. In the majority of cases, the plastic zone (PZ) clearly exceeds the hydrogen affected region (TTS) and has no relation with it. In some tests, however, the hydrogen-induced micro-damage surpasses the only region in which there is dislocation movement, and in this case the net ...

International Nuclear Information System (INIS)

Acetylcholine and other neurotransmitters play unique trophic roles in brain development. Accordingly, drugs and environmental toxicants that promote or interfere with neurotransmitter function evoke neurodevelopmental abnormalities by disrupting the timing or intensity of neurotrophic actions. The current review discusses three exposure scenarios involving acetylcholine systems: nicotine from maternal smoking during pregnancy, exposure to environmental tobacco smoke (ETS), and exposure to the organophosphate insecticide, chlorpyrifos (CPF). All three have long-term, adverse effects on specific processes involved in brain cell replication and differentiation, synaptic development and function, and ultimately behavioral performance. Many of these effects can be traced to the sequence of cellular events surrounding the trophic role of acetylcholine acting on its specific cellular receptors and associated signaling cascades. However, for chlorpyrifos, additional noncholinergic ...

Energy Technology Data Exchange (ETDEWEB)

Urban type R D (research and development) facilities have research institute functions which are not desirable to coexist in a city as compared with suburban R D facilities. Therefore careful consideration must be given to environmental protection. KSP is the first large scale urban type R D facility in Japan. The planning and construction have been made with the theme of realization of flexibility in architecture and mechanical planning as well as realization of environmental integrity. To achieve the target so-called technical slit is built at the center of the building to provide a void space for securing natural ventilation. It is effective for provision of internal mechanical spaces without spoiling urban View air exhaust from laboratories natural ventilation for underground parking lots and decrease of damage by strong wind on the ground level. Standards are established and organization is formed for environmental ...

British Library Electronic Table of Contents (United Kingdom)

We present modeling, simulation, and characterization for the dynamic response of clamped-clamped microbeams under mechanical shock. A Galerkin-based reduced-order model is utilized and its results are verified by comparing to finite-element results. The results indicate that the response of a microbeam to mechanical shock is inherently non-linear because of the dominating effect of mid-plane stretching. The effect of the shock pulse shape is investigated. It is concluded that the shape of the shock pulse can result in significant dynamic amplification in the response of the microbeam even in cases where the shock load is considered quasi-static.The combined effect of the electrostatic force and mechanical shock is investigated. The results show that this combined effect can lead to early ...

Energy Technology Data Exchange (ETDEWEB)

Polyethylene (UHMWPE) wear in current knee prosthesis causes prosthesis loosening after no more than 15 years. In this work, a steady state one-dimensional lubrication model with non- Newtonian fluid, porous elastic layer on tibial component, ultra-filtration mechanism of fluid and some features of the surface roughness is studied through a numerical technique based on the Finite Element Method. The results show that the UHMWPE stiffness makes difficult the lubrication mechanism of the artificial joint and promotes abrasive and fatigue wear. Nevertheless, the use of compliant porous materials on the tibial component could reduce friction and wear. Moreover, the ultra-filtration mechanism promotes efficiency on the joint.

Environmental Research Database

ObjectivesFirst comprehensive evaluation of the mechanical properties of an epoxy adhesive in different environments using a nano-indenter. ~%~~%~Use AFM/SEM and finite element modelling to generate knowledge of the precise mechanism of indentation in the epoxy adhesive. ~%~~%~Develop an improved data reduction algorithm for generating meaningful mechanical property data from indentation tests for adhesive materials.~%~ ~%~Validate the nano-indentation method of generating mechanical property data against [continued...]DescriptionThis project aims to address the problem of insufficient data on adhesive materials for effective modelling of joint behaviour in different environments. The methodology to be used is based on depth sensing indentation tests at different loads and rates and in different environments. Post-indentation deformation and ...

Energy Technology Data Exchange (ETDEWEB)

Spice extracts under the form of essential oils were tested for their efficiency to increase the relative radiosensitivity of Listeria monocytogenes and Escherichia coli O157H7 in culture media. The two pathogens were treated by gamma-irradiation alone or in combination with oregano essential oil to evaluate their mechanism of action. The membrane murein composition, and the intracellular and extracellular concentration of ATP was determined. The bacterial strains were treated with two irradiation doses: 1.2 kGy to induce cell damage and 3.5 kGy to cause cell death for L. monocytogenes. A dose of 0.4 kGy to induce cell damages, 1.1 kGy to obtain viable but nonculturable (VBNC) state and 1.3 kGy to obtain a lethal dose was also applied on E. coli O157H7. Oregano essential oil was used at 0.020% and 0.025% (w/v), which is the minimum inhibitory concentration (MIC) for L. monocytogenes. For E. coli O157H7, a concentration of ...

UK PubMed Central (United Kingdom)

DNA damage is a threat to genomic integrity in all living organisms. Plants and green algae are particularly susceptible to DNA damage especially that caused by UV light, due to their light dependency...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

It is demonstrated that normal pitting can occur during oxidizing conditions in the repository. It is also concluded that a new theory for pitting corrosion has to be developed, as the present theory is not in accordance with all practical and experimental observations. A special variant of pitting, based on the growth of sulfide whiskers, is suggested to occur during reducing conditions. However, such a mechanism needs to be demonstrated experimentally. A simple calculational model of canister corrosion was developed based on the results of this study. 69 refs, 3 figs.

Science.gov (United States)

Analyzing the risk of a safeguards system, in particular the security of a computer network based on the notion of fuzzy sets and linguistic variables, addresses concerns such as complexity and inherent imprecision in estimating the possibility of loss or compromise. Automated risk analysis allows the risk to be determined for an entire system based on estimates for lowest level components and the component weight. In addition, for each component (asset) we select the most effective combination of protection mechanisms against a given set of threats.

Energy Technology Data Exchange (ETDEWEB)

This presentation discussed common mechanisms for procuring wind energy in Canada. Mechanisms included renewable portfolio standards (RPSs); offsets; tax subsidies; financial subsidies; command and control mechanisms; and request for proposals (RFPs). A layered approach is required to avoid reliance on any single mechanism. RPSs require a certain minimum percentage of energy to come from renewable sources and aim to encourage the local development of renewable energy. RPSs are market-friendly and often result in the creation of tradable renewable energy credits (RECs) used for compliance purposes. RPSs work in parallel with cap and trade, baseline, and credit and carbon tax systems. RFPs target the lowest price offering, a practice which has often resulted in lower rates of return, high attrition, and a failure to attribute market prices to green attributes. It was concluded that RPSs work with a ...

Science.gov (United States)

Wade. Jackson. - Army. VTD at NASA. Langley. ABSTRACT. Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich ...

UK PubMed Central (United Kingdom)

PurposeCataracts are often considered to be an unavoidable consequence of aging. Oxidative damage is a major cause or consequence of cortical and nuclear cataracts, the most common...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

This paper presents a probabilistic approach for structural robustness assessment for a timber structure built a few years ago. The robustness analysis is based on a structural reliability based framework for robustness and a simplified mechanical system modelling of a timber truss system. A complex timber structure with a large number of failure modes is modelled with only a few dominant failure modes. First, a component based robustness analysis is performed based on the reliability indices of the remaining elements after the removal of selected critical elements. The robustness is expressed and evaluated by a robustness index. Next, the robustness is assessed using system reliability indices where the probabilistic failure model is modelled by a series system of parallel systems.

International Nuclear Information System (INIS)

The scope of the project includes four activities such as construction of DB, development of data base management tool, development of severe accident analysis code system and FP studies. In the construction of DB, level-1,2 PSA results and plant damage states event trees were mainly used to select the following target initiators based on frequencies: LLOCA, MLOCA, SLOCA, station black out, LOOP, LOFW and SGTR. These scenarios occupy more than 95% of the total frequencies of the core damage sequences at KSNP. In the development of data base management tool, SARD 2.0 was developed under the PC microsoft windows environment using the visual basic 6.0 language. In the development of severe accident analysis code system, MIDAS 1.0 was developed with new features of FORTRAN-90 which makes it possible to allocate the storage dynamically and to use the user-defined data type, leading to an ...

International Nuclear Information System (INIS)

Corrosion of steam generator heat transfer tubes (SGHTT) is one of the important problems which affect safety operation of nuclear power plants (NPP), and the hazard of pitting corrosion of heat transfer tubes is the most serious. With an acoustic emission device, the signals during a corrosion test on SGHTT were collected and analyzed, and the corrosion points in the tubes were located accurately. The results show that pitting corrosion of heat transfer tubes has passed through three periods in its development: expansion phase, stationary phase and rapid developing phase. The corrosion damage of HTT can be found earlier with acoustic emission than any other non-destructive testing methods. Acoustic emission can be used for on-line and real-time monitoring of the safety and operation of the steam generator and has therefore a great significance. (orig.)

International Nuclear Information System (INIS)

Recent research findings of epidemiologist Alice Stewart suggest that nuclear workers may be at risk of contracting cancer even though their measured occupational doses fall within current safety standards. It is argued that these standards are inappropriate as they are based on extrapolations of studies on survivors of the Hiroshima and Nagasaki explosions. These individuals received single doses of radiation, whereas today's nuclear industry personnel are exposed to low-level ionizing radiation over the length of their working lives. Stewart's team linked low dose occupational exposure to ionizing radiation with an increased risk of cancer in respiratory, digestive and blood-forming tissues. The nuclear industry and United States government agencies hotly contest these assertion with their potentially damaging political and economic consequences. (UK).

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: The Nuclear Power Plants (NPPs) are always designed for the highest level of safety against postulated accidents which may be initiated due to internal or external causes. One of the external/internal causes, which may lead to accident in the reactor and its associated systems, is fire in certain vital areas of the plant. Conventionally, the fire containment approach and/or the fire confinement approach is used in designing the fire protection systems of NPPs. Indian NPPs (PHWRs) follow the combined approach to ensure plant safety and all newly designed plants are required to comply with the provisions of Atomic Energy Regulatory Board (AERB) fire safety Guide. In respect of older plants, the reassessment of adequacy of fire safety provisions in the light of current advances has becomes essential so as to decide upon the steps for retrofitting. Keeping this in mind the deterministic fire hazard analysis was carried out for the Madras Atomic Power ...

Energy Technology Data Exchange (ETDEWEB)

Man's wastes are polluting the oceans from various sources and delivered by various routes. The result has been the loss of habitat and the irreversible altering of marine ecosystems. Development in the coastal zones and offshore activities that disrupt biologically sensitive areas have led to international negotiations to regulate these impacts and develop a law of the sea. Basic to international cooperation, however, is the need to develop answers to questions about the ecological consequences of development programs and the carrying capacity of the oceans. Current information does not demonstrate long-term global impacts, making it difficult to detect and predict incremental changes and causal relationships. Society needs to determine how much environmental damage it will accept and then to develop appropriate technology, such as biomonitoring. Society also needs to reexamine its positions on technology-based regulatory controls to ...

Energy Technology Data Exchange (ETDEWEB)

The objective of the Coastal Habitat Injury Assessment study was to document and quantify injury to biota of the shallow subtidal, intertidal, and supratidal zones throughout the shoreline affected by oil or cleanup activity associated with the Exxon Valdez oil spill. The results of these studies were to be used to support the Trustee`s Type B Natural Resource Damage Assessment under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). A probability based stratified random sample of shoreline segments was selected with probability proportional to size from each of 15 strata (5 habitat types crossed with 3 levels of potential oil impact) based on those data available in July, 1989. Three study regions were used: Prince William Sound, Cook Inlet/Kenai Peninsula, and Kodiak/Alaska Peninsula. A Geographic Information System was utilized to combine oiling and habitat data and to select the ...

CERN Document Server

We address four main areas in which graduate quantum mechanics education in the U.S. can be improved: course content; textbook; teaching methods; and assessment tools. We report on a three year longitudinal study at the Colorado School of Mines using innovations in all four of these areas. In particular, we have modified the content of the course to reflect progress in the field in the last 50 years, use modern textbooks that include such content, incorporate a variety of teaching techniques based on physics education research, and used a variety of assessment tools to study the effectiveness of these reforms. We present a new assessment tool, the Graduate Quantum Mechanics Conceptual Survey, and further testing of a previously developed assessment tool, the Quantum Mechanics Conceptual Survey (QMCS). We find that graduate students respond well to research-based techniques that have ...

International Nuclear Information System (INIS)

The existence of characteristic longitudinal optical and transverse optical phonons of cubic ZnO in ZnO nano-tetrapods is determined by Raman spectroscopy and first-principles calculations. Stacking sequence change at the boundary of the core and legs is also identified by high-resolution transmission electron microscopy. Based on this experimental and theoretical evidence, we demonstrate that the lattice structure of ZnO nano-tetrapods is hierarchical with a zinc blende core connecting to four wurtzite legs. Furthermore, we establish the atomic configuration and propose a formation mechanism induced by Laplace pressure in the initial growth stage of ZnO nano-tetrapods.

Energy Technology Data Exchange (ETDEWEB)

A micro-mechanistic understanding of bone fracture that encompasses how cracks interact with the underlying microstructure and defines their local failure mode is lacking, despite extensive research on the response of bone to a variety of factors like aging, loading, and/or disease. Micro-mechanical models for fracture incorporating such local failure criteria have been widely developed for metallic and ceramic materials systems; however, few such deliberations have been undertaken for the fracture of bone. In fact, although the fracture event in mineralized tissues such as bone is commonly believed to be locally strain controlled, until recently there has been little experimental evidence to support this widely held belief. In the present study, a series of in vitro experiments involving a double-notch bend test geometry are performed in order to shed further light on the nature of the local cracking events that precede catastrophic fracture in bone and to define ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

The author furnishes a review of incidents of major damage to high-output steam turbines. At the same time, he thereby underlines the call for an improvement in the exchange of experience on such damage and its causes at international level. Only the careful observance of past damage experience - including that of foreign manufacturers and operators - complete and modern monitoring equipment and the painstaking evaluation of all data furnished by such equipment can keep the risk of new technical development within economically tolerable limits. (orig.).

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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International Nuclear Information System (INIS)

Scanning thermal microscopy (SThM) was used to map thermal conductivity images in an ultrafine-grained copper surface layer produced by surface mechanical attrition treatment (SMAT). It is found that the deformed surface layer shows different thermal conductivities that strongly depend on the grain size of the microstructure: the thermal conductivity of the nanostructured surface layer decreases obviously when compared with that of the coarse-grained matrix of the sample. The role of the grain boundaries in thermal conduction is analyzed in correlation with the heat conduction mechanism in pure metal. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that SThM can be used as a tool for the thermal property and ...

British Library Electronic Table of Contents (United Kingdom)

The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerody namic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. T...

CERN Document Server

The fast rotating wire scanners installed in the PS and the PS booster are used for the precise transversal profile measurements in horizontal and vertical planes. The scanners may show large position measurement errors if no special treatment is applied to the acquired data. The aim of the calibration is to obtain a correction algorithm for the systematic position measurement error due to mechanical and electronic offsets. A new calibration system has been developed and introduced at CERN for the scanners implementing position feedback control. The calibration method is based on a substitution of a particle beam by a laser one where the laser beam position is well known. According to the previous experience the following crucial requirements to the system have been taking into consideration: heavy and mechanically stable design of the calibration bench to reduce mechanical oscillations of scanner ...

Energy Technology Data Exchange (ETDEWEB)

In view of the importance of the material Alloy 800 in high-temperature reactor plants (HTR), a material data bank was established which is used for statistical evaluation of mechanical and physical material behaviour. Based on investigations on the interconnection between the mechanical properties at high temperatures and the metallurgical parameters, different types of Alloy 800 were specified in compliance with the component requirements. In addition, aspects of corrosion and toughness behaviour were taken into consideration. The specifications and strength characteristics for the different variants of Alloy 800 were incorporated into draft DIN standards after discussion and approval in expert committees. Further important characteristics of the mechanical and physical material behaviour were summarized in HTR material data sheets so as to furnish an improved basis for the design and stress analyses ...

International Nuclear Information System (INIS)

We outline basic principles of a canonical formalism for the Nambu mechanics - a generalization of Hamiltonian mechanics proposed by Yoichiro Nambu in 1973. It is based on the notion of a Nambu bracket, which generalizes the Poisson bracket - a 'binary'' operation on classical observables on the phase space - to the 'multiple' operation of higher order n#>=#3. Nambu dynamics is described by the phase flow given by Nambu-Hamilton equations of motion - a system of ODE's which involves n-1 'Hamiltonians'. We introduce the fundamental identity for the Nambu bracket - a generalization of the Jacobi identity - as a consistency condition for the dynamics. We show that Nambu bracket structure defines a hierarchy of infinite families of 'subordinated' structures of lower order, including Poisson bracket structure, which satisfy certain matching conditions. The notion of Nambu bracket enables us to define Nambu-Poisson manifolds - ...

International Nuclear Information System (INIS)

A probabilistic precursor study provides a complement to the 'root cause' analysis approach by focusing on how an event might have developed adversely, and implies the mapping of an operational event on a probabilistic risk model of the plant in order to obtain a quantitative assessment of the safety significance of the event. In order to benefit from state-of-the-art PSA features but also to assure repeatability of the analysis, a comprehensive set of PSAEA guidelines was developed. This PSAEA procedure was established in 1996-1998 by Enconet Consulting in the framework of an international project on behalf of - and involving - the nuclear regulatory bodies from 6 countries: AECB (Canada), AVN (Belgium), CSN (Spain), HSK (Switzerland), NII (United Kingdom) and SKI (Sweden). The PSAEA procedure defines preliminary requirements for the PSA model and code, and identifies input requirements such as information on plant status, event sequence chronology and causes. The procedure then ...

International Nuclear Information System (INIS)

Although low-energy ion radiation has been proven to have a wide range of biological effects and led to fruitful achievements as a new mutagenic source for genetic modification, there still exist some disputes about its mutagenic mechanisms because of its short-penetrating property. In present research, Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by irradiations of alpha particle (3.3MeV) and Low-energy-Argon ion (30 KeV). A pronounced effects of alpha particle irradiation to Arabidopsis thaliana seedlings and Argon ion irradiation to seeds on the somatic homologous recombination frequency (sHRF) were reported. The sHRFs increased 1.88-fold and 2.42-fold, respectively, which indicated that the short-penetrating radiation could effectively induce the plant genomic instability in either dry seeds or seedlings with active metabolism. The local alpha particle irradiation of root was performed. ...

British Library Electronic Table of Contents (United Kingdom)

ABSTRACT Introduction. Significant progress has been made in the understanding of physiological and pharmacological mechanisms of human sexual functioning through preclinical research in animal models. Aim. To provide an evidence-based documentation of the experimental models evaluating male and female sexual function for useful clinical translation. Methods. Consensus discussion over the past 18 months leading to summarized views of seven experts from six countries. Main Outcome Measure. Report was based on the critical analysis of scientific information available in literature and subcommittee presentations, discussions, and exchanges of ideas and feedback. Results. Fundamental research in animal models has led to considerable understanding of the physiological mechanisms underlying desi...

Energy Technology Data Exchange (ETDEWEB)

We have investigated tailoring damage effects of explosive devices by addition of unconventional materials, specifically combustible metals. Initial small-scale as well as full-scale testing has been performed. The explosives functioned to disperse and ignite these materials. Incendiary, enhanced-blast, and fragment-damage effect have been identified. These types of effects can be used to extend the damage done to hardened facilities. In other cases it is desirable to disable the target with minimal collateral damage. Use of unconventional materials allows the capability to tailor the damage and effects of explosive devices for these and other applications. Current work includes testing of an incendiary warhead for a penetrator.

International Nuclear Information System (INIS)

A statistical evaluation of rotor blade damage in axial steam turbines affords an insight into the extent of the repair costs incurred and reveals the types of defects and shortcomings which cause such damage. The great amount of rotor blade damage discovered during control inspections will surprise even many turbine experts. The statistical evaluation is followed by a review of the more frequent causes of damage and their characteristic features, illustrated on the basis of practical examples. This contribution is intended as an aid to both the manufacturers and operators of steam turbines in preventing the oft almost classic types of faults which constantly recur. (orig.).

Science.gov (United States)

A new approach of gear fault diagnosis based on continuous wavelet transform is presented. Continuous wavelet transform can provide a finer scale resolution than orthogonal wavelet transform. It is more suitable for extracting mechanical fault information. In this paper, the concept of time-averaged wavelet spectrum (TAWS) based on Morlet continuous wavelet transform is proposed. Two fault diagnosis methods named spectrum comparison method (SCM) and feature energy method (FEM) based on TAWS are established. The results of the application to gearbox gear fault diagnosis show that TAWS can effectively extract gear fault information. The feature energy of the TAWS features the gear fault advancement very well and is conically proportional to the gear fault advancement.

Energy Technology Data Exchange (ETDEWEB)

During rolling contact fatigue of the inner rings of ball bearings three stages of material response can be distinguished, in terms of the volume that is plastically deformed upon overrolling. After a first stage of material strengthening during which a decrease occurs for the volume that is deformed plastically, an effectively stationary, second stage is entered which is eventually succeeded by a third stage exhibiting a pronounced increase of the volume that is deformed plastically upon overrolling, which leads to failure. It is suggested that carbon diffusion induced by local temperature peaks occurring at the moment of overrolling is the key mechanism leading to fatigue damage. The amount of decomposed retained austenite is a useful, practical parameter to assess fatigue life. It is shown that published ideas about the role of certain components of residual stress in enhancing fatigue life are not correct and that the so-called ...

Energy Technology Data Exchange (ETDEWEB)

Ice jamming, known to cause high water levels at even moderate river flows, is described as both the main and least understood source of ice-related bridge damages. This paper describes a joint study by the New Brunswick Department of Transportation, the Department of the Environment, local governments, and the National Water Research Institute, designed to address problems associated with the interaction of ice jams and bridges. The study consists of collecting information at each of four sites in New Brunswick including: historical data on ice jam locations, causes, and water levels; channel bathymetry, width and slope within each study centred at the respective bridge; and documentation of ice conditions throughout the ice season, including measurement of ice cover thickness, observation of breakup mechanisms, times, causes, characteristics and possible impacts of ice jam release. Data analysis will include determination of high stages due ...

International Nuclear Information System (INIS)

Total-dose irradiation seriously damages MOS devices and their circuit performance. Threshold voltage shifts, transconductance degradation and increase in off-state leakage current are generally observed for irradiated devices. These instabilities are essentially due to positive and/or negative charge trapping in SiO_2 and interface trap generation at the SiO_2/Si interface. Radiation hardening of CMOS VLSIs is to eliminate these trapping effects, and for this purpose, special considerations for fabrication processes and layout design are necessary. In this paper, basic mechanisms for radiation-induced charge trapping and related effects on MOS devices are reviewed. Also discussed are radiation-hardening technologies from both fabrication-process and layout-design viewpoints. Using these technologies, 1 #mu#m radiation-hard CMOS gate arrays have been successfully developed. Experimental data taken for 2k-gate test chips indicate that radiation ...

Science.gov (United States)

Therapeutic hypothermia is a promising method for controlling intracranial pressure (ICP) in severely brain-injured patients. However, clinical data regarding the effect of brain hypothermia on overall outcome of these patients is limited. This may be because there are specific pitfalls associated with the clinical management of induced hypothermia in patients with severe traumatic brain injury (TBI). These pitfalls may be avoided by preventing specific risk factors when cooling is induced and with rewarming. However, these risk factors have not been well systematically discussed in the literature. In this paper, three categories of clinical issues regarding the management of brain hypothermia are discussed: (1) stress-induced secondary brain injury mechanisms; (2) technical aspects of intensive care unit (ICU) cooling management; and (3) rewarming rates and methods. For patients with a Glasgow Coma Scale (GCS) score of less than 8, management of stress-induced ...

Energy Technology Data Exchange (ETDEWEB)

Cell death in general can be a physiological process of cell number regulation in tissue, or it can be the result of exo or endogenous injuries, such a low-dose of radiation. Chicken B cell population in the bursa of Fabricius are very susceptible to PCD. Our present studies concern the development of radiation damage of chicken defence mechanisms. In 6 experiments pathogen free chicken were irradiated by gamma rays with the total doses of 0.25, 0.5, 1.0, 2.0 and 4.0 Gy. The induction of apoptosis was checked by Flow-cyto-meter 12 h after irradiation in bursa cell suspension. There is some increase in the number of induced apoptotic cells 12 h after irradiation at the dose 0.5-.4.0 Gy. There were no significant changes in the proportion of proliferating lymphocytes (G2 M), but cellularity decreased significantly at dose 2.0 and 4.0 Gy/12 h after irradiation. (author)

Science.gov (United States)

Ballistics involves the study of the scientific properties of projectiles, their behavior and their terminal effects on biological tissues and other materials. Wound ballistics deals with the analysis of injuries caused by projectiles and the behavior of projectiles within human or other biological tissues. The nineteenth century witnessed the development of both of these areas with Kocher's hydrodynamic theory and the understanding of the significance of bullet deformation in causing tissue injury. The degree of traumatic disruption of tissues and organs was also related to direct energy transfer from projectiles. While subsequent research has concentrated on elucidating further mechanisms of injury, the exact cause of remote tissue damage from high energy projectiles is still the subject of ongoing research. Much of the contemporary literature regarding wound ballistics concentrates on the forensic aspects and their application for legal ...

Energy Technology Data Exchange (ETDEWEB)

High concentrations of self-interstitials are trapped by dopant atoms during ion implantation into Si. For group V dopants, these complexes are sufficiently stable to survive solid-phase-epitaxial (SPE) growth but break up on subsequent thermal processing and cause a transient-enhanced diffusion. Dopant diffusion coefficients are enhanced by up to five orders of magnitude over tracer values and are characterized by an activation energy of approximately one half of the tracer values. In the case of group III dopants, any complexes formed during implantation do not survive SPE growth but a second source of self-interstitials becomes significant and leads to similar transient effects. This is the damaged layer underlying the original amorphous/crystalline interface. These observations provide direct evidence for long-range self-interstitial migration in Si, and we believe these are the first observations of the interstitialcy diffusion mechanism ...

Energy Technology Data Exchange (ETDEWEB)

A simulation model for boron diffusion which takes into account the aggregation of the excess interstitials in clusters, and subsequently, the dissolution of these defects, is proposed. The interstitial supersaturation and generation rate are determined according to the classical theory of nucleation and growth of particles, in analogy with the precipitation of a new phase in heavily doped silicon. The clusters are considered as precipitates formed by interstitial Si atoms. The B diffusion is modelled on the basis of the dopant-interstitial pair diffusion mechanism. The clusters dissolution during annealing maintains nearly constant, for a long period, the interstitial supersaturation and the related enhancement of the boron diffusion. This gives a good account of the diffusion results over a large range of experimental conditions. Furthermore, this approach describes most of the behavior of the transient enhanced diffusion (TED), like the temperature dependence of ...

Energy Technology Data Exchange (ETDEWEB)

Experiments were performed to investigate the involvement of the cell membrane in the excision DNA repair process in Escherichia coli. Two membrane-binding drugs, procaine and phenethyl alcohol (PEA), inhibited liquid-holding recovery (LBR) in u.v.-irradiated E. coli wild-type and recA strains. In uvrB and polA strains where, after u.v.-irradiation, LHR was absent the two drugs had no effect. Both drugs markedly reduced the removal of u.v.-induced thymine dimers in the DNA of wild-type cells (H/r30). Analysis by alkaline sucrose gradients revealed that PEA inhibited the incision step in excision repair. In contrast, procaine had no effect on incision but apparently inhibited the late steps in excision repair. PEA dissociated DNA from the cell membrane, whereas procaine did not. The results suggest that the two drugs PEA and procaine inhibit LHR and the excision repair process operating on u.v.-induced damage in E. coli by at least two different ...

Energy Technology Data Exchange (ETDEWEB)

Recently, the capabilities of the CORMLT code, which was designed to predict heatup, degradation, and meltdown of core and Reactor Pressure VEssel (RPV) internals during postulated severe accidents, were enhanced to enable tracking of individual fission product species during core meltdown. In addition, a mechanistic treatment of the release and flow of molten materials was developed to replace the engineering models developed earlier. In the present paper, the improved models are described and predictions of melt progression for a postullated accident sequence (TMLB') are discussed. A key issue in the new modeling is the mechanical behavior of fuel pellet stacks during run-off of molten cladding. One view is that capillary forces result in ''welding'' of porous fuel, thereby promoting free-standing pellet stacks; another is that rubblization and slumping of fuel take place. Results are reported for the first view point ...

Energy Technology Data Exchange (ETDEWEB)

Wind power is an increasingly significant renewable energy resource, producing no environmentally damaging CO2 emissions. The efficient production of electricity by wind turbines relies on aerodynamics. Aerodynamics of Wind Turbines provides the fundamental solutions to efficient wind turbine design. Following a historical introduction, Part 1 of Aerodynamics of Wind Turbines is concerned with basic rotor aerodynamics, while Part 2 deals with structural aspects of the wind turbine and calculation of the loads on it. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. Aerodynamics of Wind Turbines is an essential reference for both engineering students and others ...

International Nuclear Information System (INIS)

In the feasibility study on commercialized FBR systems, the application of 12Cr steel, with its physical properties and high-temperature strength properties, as structural material is considered in order to greatly reduce construction costs by compacted instruments and structures. In this report, creep, fatigue and the creep-fatigue properties of Mod.9Cr-1Mo steel forging (thickness 550mm) weld, representing conventional steels, were evaluated in order to obtain the needed basic data for the evaluation of the high-temperature strength of 12Cr steel weld. The results obtained are as follows: (1) Metal suitable for HAZ was made by applying thermal treatment to simulate the thermal hysteresis during welding to clearly define creep and fatigue properties in a HAZ softened zone. (2) Creep strength of the weld metal and the welded joint was equal to that of the base metal. However, the welded joint ruptured in the HAZ softened zone and its ductility decreased after about ...

Energy Technology Data Exchange (ETDEWEB)

Current projections of the response of the biosphere to global climatic change indicate as much as 50% to 90% spatial displacement of extratropical biomes. The mechanism of spatial shift could be dominated by either (1) competitive displacement of northern biomes by southern biomes, or (2) drought-induced dieback of areas susceptible to change. The current suite of global biosphere models cannot distinguish between these two processes, thus determining the need for a mechanistically based biome model. The model is in an early stage of development and will require several enhancements, including explicit simulation of potential evapotranspiration, extension to boreal and tropical biomes, a shift from steady-state to transient dynamics, and validation on other continents.

British Library Electronic Table of Contents (United Kingdom)

The present paper considers the evaluation of timber structures with the focus on robustness due to connection ductility. The robustness analysis is based on the structural reliability framework applied to a simplified mechanical system. The structural timber system is depicted as a parallel system. An evaluation method of the ductile behaviour is introduced. For different ductile behaviours, the system reliability is estimated based on Monte Carlo simulation. A correlation between the strength of the structural elements is introduced. The results indicate that the reliability of a structural timber system can be significantly increased due to the ductile behavior.

Energy Technology Data Exchange (ETDEWEB)

A method for cleaning timing optimization in a parallel steam generator system is described. The method is based on the minimization of a suitable objective function, and takes into account the load allocation on steam generators. In order to establish appropriate fouling growth models the mechanism of the particle deposition and removal on heat transfer surfaces is analyzed. The objective function is related to the short time management costs which are based on depreciation of steam generators, fuel costs and the costs of cleaning interventions. The optimization problem is described; a direct one level method is compared with a two level method. Some applications and their results are reported and discussed. (author)

Energy Technology Data Exchange (ETDEWEB)

Under the auspices of the Mine Environment Neutral Drainage (MEND) Program, several waste rock piles were monitored and characterized. Acid rock drainage (ARD) became a mechanism better understood based on the data acquired during these projects. Numerical simulation was used to better comprehend the quantitative issues associated with the characterization of three specific sites for the purpose of this study. The sites selected were the south waste rock pile of the Doyon Mine in Quebec, the Northdale of the mining district of Ronnenberg in Germany, and the waste rock pile of the Sugar Shack South of the Questa mine in New Mexico. The observed and simulated conditions were very distinct from one mine to another, even if the same mechanisms were involved. The dominant oxygen and heat transfer mechanisms displayed the most varied behavior between the sites. ARD control or site rehabilitation decisions ...

British Library Electronic Table of Contents (United Kingdom)

The work is devoted to a microscopic analysis of the reactive capacity of chitin. An algorithm for modeling the deacetylation reaction in a monomeric unit of chitin is described. The reaction coordinate and the potential energy surface topography are determined taking into account the electron-vibrational interaction and low-symmetry perturbations within Jahn-Teller theory. Based on this algorithm, the topological modeling of the deacetylation process is performed for the first time and a mechanism of the biological activity of chitosan is proposed.

Energy Technology Data Exchange (ETDEWEB)

This report describes the test of a dynamic phase compensation unit for a wind turbine with directly connected induction generators. The compensation unit is based on thyristor switched capacitors, where conventional wind turbine compensations use mechanical contactors to switch the capacitors. The influence on power quality analysed, and influence on component lifetime is discussed. Besides, simulation models in Matlab/Simulink are presented, including a flicker meter model. (au)

Energy Technology Data Exchange (ETDEWEB)

Thermal absorption with its combined thermal and mechanical loads in a solar receiver does depend significantly on the distribution of incident solar radiation. For a cavity receiver with paraboloid collectar a method is derived which enables the calculation of solar radiation distribution on the areas inside the receiver. The theoretical bases are presented first, and a subsequent example shows the influence of the most important geometric parameters on the distribution of solar radiation.

Energy Technology Data Exchange (ETDEWEB)

We study by means of Quantum Monte Carlo simulations based on the Worm Algorithm the low temperature (down to T = 0.05 K) properties of parahydrogen clusters comprising up to 40 molecules. Three different intermolecular interactions are employed: the Silvera-Goldman, the Buck and the Lennard-Jones potential. Despite important discrepancies observed in the numerical estimates of energy and superfluid fraction, the mechanism by which clusters melt at low T is independent of the particular choice of the potential, whose only effect is to alter the temperature scale.

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This paper reviews the effects of neutron irradiation on thermal and mechanical properties and bulk tritium retention of armour materials (beryllium, tungsten and carbon). For each material, the main properties affected by neutron irradiation are described and the specific tests of neutron irradiated armour materials under thermal shock and disruption conditions are summarized. Based on current knowledge, the expected thermal and structural performance of neutron irradiated armour materials in the ITER plasma facing components are analysed.

Energy Technology Data Exchange (ETDEWEB)

The use of filters of activated-charcoal particles in drinking-water purification plants assists in the elimination of organic micropollutant substances. The authors report on a study which sought to investigate the mechanism of organic matter; they describe the experimental programme, which used different size ranges of mineral-based activated charcoal, present the experimental findings and discuss the results. 16 references.

Energy Technology Data Exchange (ETDEWEB)

This bibliography contains citations concerning theoretical aspects and industrial applications of activated charcoal. Topics include absorption capacity and mechanism studies, kinetic and thermodynamic aspects, and properties descriptions and evaluations. Applications include utilzation in water analyses and waste treatment, air pollution control and measurement, and in nuclear facilities. (This updated bibliography contains 160 citations, 14 of which are new entries to the previous edition.)

UK PubMed Central (United Kingdom)

Environmental and occupational exposures to heavy metals such as methylmercury (MeHg) and cadmium (Cd) pose significant health risks to humans, including neurotoxicity. The underlying mechanisms of...Full Text Available

DEFF Research Database (Denmark)

It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H reaction ...

International Nuclear Information System (INIS)

The PERMCAT process chosen for the final clean-up stage of the Tokamak Exhaust Processing system of the ITER tritium plant combines in a single component a catalytic reactor and a permeator using Pd/Ag membranes. This study covers the mechanical behaviour of a Pd/Ag membrane under different operating conditions. The consequences of hydrogen uptake by the membrane during nominal operation but also during off-normal events are presented. Depending on the operating conditions, expansions around 2% and significant deformations are observed. Different mechanical designs of PERMCAT reactors are then discussed. The first generation comprises finger-type membranes and two new mechanical designs use either additional edge welded bellows or a special corrugated Pd/Ag membrane. These upgraded designs improve the robustness and simplify the geometry of the component. The experimental validation of these new units has been carried out ...

Science.gov (United States)

In this paper a new procedure, addressed as Interpolation Damage Detecting Method (IDDM), is investigated as a possible mean for early detection and location of light damage in a structure struck by an earthquake. Damage is defined in terms of the accuracy of a spline function in interpolating the operational mode shapes (ODS) of the structure. At a certain location a decrease (statistically meaningful) of accuracy, with respect to a reference configuration, points out a localized variation of the operational shapes thus revealing the existence of damage. In this paper, the proposed method is applied to a numerical model of a multistory frame, simulating a damaged condition through a reduction of the story stiffness. Several damage scenarios have been considered and the results indicate the effectiveness of the method to assess and localize ...

Energy Technology Data Exchange (ETDEWEB)

Onshore pipelines have traditionally been designed with a deterministic stress based methodology. The changing operating environment has however imposed many challenges to the pipeline industry, including heightened public awareness of risk, more challenging natural hazards and increased economic competitiveness. To meet the societal expectation of pipeline safety and enhance the competitiveness of the pipeline industry, significant efforts have been spent for the development of reliability-based design and assessment (RBDA) methodology. This paper will briefly review the technology development in the RBDA area and the focus will be on the progresses in the past years in standard development within the American Society of Mechanical Engineers (ASME) and the Canadian Standard Association (CSA) organizations. (author)

British Library Electronic Table of Contents (United Kingdom)

In this paper, a hybrid time-frequency method (HTM) based on the improved Morlet wavelet and auto terms window (ATW) is presented. The Morlet wavelet, for its shape is similar to the mechanical shock signals, is added two parameters which decide the shape of the mother wavelet. The added parameters and the appropriate scale parameter for continuous wavelet transformation (CWT) are calculated using the cross validation method (CVM) and the minimum Shannon entropy method. The useless noise in the original signal can be filtered by the CWT filter de-noising process. An ATW based on the Smoothed Pseudo Wigner-Ville Distribution (SPWVD) spectrum is designed as a window function to suppress the cross terms in Wigner-Ville Distribution (WVD). The gear fault diagnosis experiment results show that ...

Energy Technology Data Exchange (ETDEWEB)

Recent efforts to identify methods of modeling pitting corrosion damage of high-level radioactive-waste containers are described. The need to develop models that can provide information useful to higher level system performance assessment models is emphasized, and examples of how this could be accomplished are described. Work to date has focused upon physically-based phenomenological stochastic models of pit initiation and growth. These models may provide a way to distill information from mechanistic theories in a way that provides the necessary information to the less detailed performance assessment models. Monte Carlo implementations of the stochastic theory have resulted in simulations that are, at least qualitatively, consistent with a wide variety of experimental data. The effects of environment on pitting corrosion have been included in the model using a set of simple phenomenological equations relating the parameters of the stochastic ...

Energy Technology Data Exchange (ETDEWEB)

The feasibility of using desferrioxamine (DF), an iron chelator, as a therapeutic agent against paraquat (PQ/sup + +/) toxicity in male Sprague-Dawley rats was explored, based on the rationale of limiting toxic hydroxyl radical production from hydrogen peroxide by removing redox-active iron. Body weights, mortality, and lung histopathology were followed for periods up to 14 days after intraperitoneal injection of PQ/sup + +/ (20 or 25 mg/kg body weight) with or without concurrent daily subcutaneous injections of DF (300 mg/day). Animals receiving PQ/sup + +/ showed the expected typical patterns of mortality and of lung histopathology, namely: marked edema, subpleural hemorrhage, acute inflammation, perivascular mononuclear cell infiltrates, sloughing of alveolar and bronchiolar lining cells, and diffuse interstitial fibrosis. Desferrioxamine alone was non-toxic. Surprisingly, results when both PQ/sup + +/ and DF were administered indicated a failure of DF to ...