UK PubMed Central (United Kingdom)

Dynamic deformation and recovery responses of red blood cells (RBCs) to a cyclically reversing shear flow generated in a 30-μm clearance, with the peak shear stress of 53, 108,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A new experimental technique to measure material shear strength at high pressures has been developed for use on magneto-hydrodynamic (MHD) drive pulsed power platforms. By applying an external static magnetic field to the sample region, the MHD drive directly induces a shear stress wave in addition to the usual longitudinal stress wave. Strength is probed by passing this shear wave through a sample material where the transmissible shear stress is limited to the sample strength. The magnitude of the transmitted shear wave is measured via a transverse VISAR system from which the sample strength is determined.

International Nuclear Information System (INIS)

A numerical study of a natural convection in a rectangular cavity with the low-Reynolds-number differential stress and flux model is presented. The primary emphasis of the study is placed on the investigation of the accuracy and numerical stability of the low-Reynolds-number differential stress and flux model for a natural convection problem. The turbulence model considered in the study is that developed by Peeters and Henkes (1992) and further refined by Dol and Hanjalic (2001), and this model is applied to the prediction of a natural convection in a rectangular cavity together with the two-layer model, the shear stress transport model and the time-scale bound #upsilon#"2-f model, all with an algebraic heat flux model. The computed results are compared with the experimental data commonly used for the validation of the turbulence models. It is shown that the low-Reynolds-number differential ...

International Nuclear Information System (INIS)

In this study the results of mathematical simulation and experimental research of texture transition in stress assisted shear phase transformations are discussed. The orientation distribution function (ODF) calculation model to the any type crystalline lattice symmetry materials has been suggested. By crystalline lattice symmetry analysis this computer program determines necessary amount of the initial experimental data. The experimental verification supports this model well. The ODF calculation model after shear phase transformation with equal use of all possible variants of orientation relationship or with various degrees of variant selection worked out. In this study the experimental and calculating data of the direct and reversal shear transformations #alpha# <=> #gamma# in Fe-alloys and B2 <=> B19' in Ti-Ni alloys are discussed. The stress assisted ...

CERN Document Server

We prove, using the AdS/CFT correspondence, that the long wavelength dynamics of the shear stress tensor in a strongly coupled N=4 SYM plasma is not described by the relaxation-type, fluid dynamical equations proposed by Israel and Stewart: the coarse grained dynamics will necessarily contain a second-order comoving derivative of the shear stress tensor. We argue that this should be true for any strongly-coupled gauge theory with a gravity dual. If the QGP formed in heavy ion collisions can indeed be described in terms of a (yet unknown) theory of gravity in higher dimensions, the equations of motion used in hydrodynamical simulations of the QGP must necessarily include second order comoving derivatives of the shear stress tensor.

CERN Document Server

A complex network approach on a rough fracture is developed. In this manner, some hidden metric spaces (similarity measurements) between apertures profiles are set up and a general evolutionary network in two directions (in parallel and perpendicular to the shear direction) is constructed. Also, an algorithm (COmplex Networks on Apertures: CONA) is proposed in which evolving of a network is accomplished using preferential detachments and attachments of edges (based on a competition and game manner) while the number of nodes is fixed. Also, evolving of clustering coefficients and number of edges display similar patterns as well as are appeared in shear stress, hydraulic conductivity and dilation changes, which can be engaged to estimate shear strength distribution of asperities.

UK PubMed Central (United Kingdom)

BackgroundDuring normal breathing, the mesothelial surfaces of the lung and chest wall slide relative to one another. Experimentally, the shear stresses induced by...Full Text Available

International Nuclear Information System (INIS)

The use of high pressure waterjets (HPWJ) as oil barriers has been proposed and tested. It has been shown that a series of waterjets directed horizontally above the free water surface provide an effective means of containing or deflecting oil slicks. The waterjets generate a high speed air flow capable of moving the surface layer of the liquid. A numerical model is implemented to study the characteristics of the entrained turbulent air flow using the Spectral Element Method (SEM) and an algebraic turbulent model for the Reynolds stresses. A test of the code is done for turbulent Couette Flow to check the accuracy of the calculated shear stresses against published data. A parametric study is performed to evaluate the HPWJ system performance at various operating and design parameters which include manifold pressure, nozzle flow rate, nozzle characteristics, jet height and surface wave conditions. The total driving ...

Energy Technology Data Exchange (ETDEWEB)

Approximately 95% of the world`s integrated chips are packaged using a hot, high pressure transfer molding process. The stress created by the flow of silica powder loaded epoxy can displace the fine bonding wires and can even distort the metalization patterns under the protective chip passivation layer. In this study the authors developed a technique to measure the mechanical stress over the surface of an integrated circuit during the molding process. A CMOS test chip with 25 diffused resistor stress sensors was applied to a commercial lead frame. Both compression and shear stresses were measured at all 25 locations on the surface of the chip every 50 milliseconds during molding. These measurements have a fine time and stress resolution which should allow comparison with computer simulation of the molding process, thus allowing optimization of both the ...

CERN Document Server

It is shown that the physical interpretation of Elie Cartan three-dimensional space torsion as couple asymmetric stress, has the effect of damping, previously Riemannian unstable Couette planar shear flow, leading to stability of the flow in the Lagrangean sense. Actually, since the flow speed is inversely proportional to torsion, it has the effect of causing a damping in the planar flow atenuating the instability effect. In this sense we may say that Cartan torsion induces shear viscous asymmetric stresses in the fluid, which are able to damp the instability of the flow. The stability of the flow is computed from the sectional curvature in non-Riemannian three-dimensional manifold. Marginal stability is asssumed by making the sectional non-Riemannian curvature zero, which allows us to determine the speeds of flows able to induce this stability. The ideas discussed here show that torsion plays the ...

International Nuclear Information System (INIS)

Momentum transfer through an air-water interface was studied in a horizontal rectangular channel through experimental and numerical analysis. The liquid flow Reynolds numbers, based on hydraulic diameters, were 11500 and 17000. The air flow Reynolds number varied from 0 to 3260. In experiments, velocity distribution was measured by hot-film and hot-wire probes. The effect of the liquid flow Reynolds number and the direction of interfacial shear stress was investigated by performing the cocurrent and countercurrent experiments. The modified k-#epsilon# model was able to reproduce these experimental results qualitatively. The range of applicability of the modified k-#epsilon# model was also discussed. (author).

CERN Document Server

Numerical simulations are used to test the kinetic theory constitutive relations of inertial granular shear flow. These predictions are shown to be accurate in the dilute regime, where only binary collisions are relevant, but underestimate the measured value in the dense regime, where force networks of size $\\xi$ are present. The discrepancy in the dense regime is due to non-collisional forces that we measure directly in our simulations and arise from elastic deformations of the force networks. We model the non-collisional stress by summing over all paths that elastic waves travel through force networks. This results in an analytical theory that successfully predicts the stress tensor over the entire inertial regime without any adjustable parameters.

CERN Document Server

Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive ...

International Nuclear Information System (INIS)

In the case wherein nonlinear seismic response analyses are carried out, the response values vary due to the variations in materials and modeling. In this paper, nonlinear analyses of several random variables are carried out using: i. a conventional method; ii. a two-point estimation method (i. and ii. are simplified methods); and iii. Monte Carlo simulation (detailed method) to examine the variability of the response in the excessive nonlinear range for seismic responses of shear walls. The analyses are performed to a PWR-3 loop type reactor building which is one of the most typical reactor buildings in Japan. The variations are considered in specified compressive strength of concrete, concrete damping factor, shear wave velocity of soil and shapes of shear stress-strain relation curves of shear walls. As the results by the two simplified methods closely matched the Monte Carlo ...

International Nuclear Information System (INIS)

A theoretical analysis of two-dimensional unsteady flow in a porous medium bounded by a horizontal wall is presented as a perturbation on a basic flow. It is assumed that the perturbation is occasioned by a sudden suction at the wall. Even for a highly permeable medium the characteristic Reynolds number in porous media flow is usually small and asymptotic solutions are developed by the Laplace transform technique. It is observed that the perturbed shear stress at the wall decays exponentially with time. (author). 5 refs.

International Nuclear Information System (INIS)

Computer experiments imitating specimen strain on tension with constant deformation rate have been carried out. A formation possibility of atmosphere from defects around gliding dislocations (I) and a work of Frank-Read sources (II) have been accounted for. In result deformation curves until stresses do not exceed a critical shear stress were calculated. Influence of effects (I) and (II) was analyzed. It is determined that both by pass of dislocations over defect ''atmospheres'' and dislocation multiplication can cause a peak in flow stress occurrence on the deformation curves. Reasons and conditions of such peak occurrence have been studied. 12 refs.; 9 figs. (author).

Energy Technology Data Exchange (ETDEWEB)

The microstructural development inside the stress induced martensite (SIM) variants in Ti-Ni-Nb alloy with various degrees of deformation have been revealed by electron microscopic observations. The orientation relationship between the SIM and the parent phase has been found: [1{bar 1}0]{sub M}{parallel}[11{bar 1}]{sub B2}, (001){sub M} 5{degree} away from (101){sub B2}. The lattice invariant shear of the SIM variants at the slightly deformed stage is dominantly (11{bar 1}) Type I twin. Besides the ordinary slip, the adjustment and development of the internal secondary twinning from (11{bar 1}) Type I twin to {l_angle}011{r_angle} Type II/ or (011) Type I twin, (001)compound twin and (111) Type I twin happen concurrently or in combination inside the SIM variants with the further deformation. The corresponding deformation mechanisms include stress induced reorientation of SIM substructural bands by the most favorably ...

Energy Technology Data Exchange (ETDEWEB)

Three dispersants (stearic acid, oleic acid, and poly-(12-hydroxystearic acid)) are compared for their ability to produce low-viscosity suspensions of zirconia in kerosene. Rheological measurements and sediment packing density measurements show that poly(12-hydroxystearic acid) is a better dispersant than stearic acid or oleic acid; this is explained in terms of the longer tail of the poly-(12-hydroxystearic acid) surfactant molecule. The amount of dispersant can be optimized to reduce viscosity and yield point of the suspension, and to eliminate thixotropic hysteresis. The use of a dispersion medium of lower viscosity than the dispersant makes it easy to detect when complete monolayer coverage has been achieved. The loss of pseudoplasticity, brought about by a higher degree of deflocculation, can be recovered by increasing the volume fraction of solids of a suspension and this is beneficial in the plastic forming of ceramics. Rheological measurements showed that these suspensions ...

Science.gov (United States)

Hot-torsion testing was used to establish the cavitation behavior of a typical alpha/beta titanium alloy, Ti-6Al-4V, with a colony microstructure, during simple-shear deformation. For this purpose, sections of deformed specimens were examined by optical metallography, and by scanning and orientation-imaging microscopy (OIM). It was found that cavity nucleation occurred along prior beta boundaries as well as at triple points; in particular, most cavities nucleated along boundaries perpendicular to the axial direction of the specimen. Extensive growth was observed for cavities surrounded by both hard and soft orientations, with the soft colonies accommodating more of the imposed strain. At high degrees of deformation, dynamic globularization of the colony microstructure adjacent to the cavities was also observed. In addition, the metallographic observations revealed that the cavities did not grow in an equiaxed mode, but in an elliptical manner. A tensor describing ...

Energy Technology Data Exchange (ETDEWEB)

The problem of pile groups subjected to lateral loads is of interest particularly in offshore and coastal regions. An understanding of pile-soil interaction is essential in designing such pile foundations. In this paper, a simplified finite element analysis in conjunction with Yegian and Wright approach has been presented to study the behavior of pile groups under lateral loads. The pile is treated as a shear beam and the soil media is assumed to be linear elastic. The results of the analysis are used to estimate: (1) Lateral Group Efficiency and (2) Extent of stress influence around the pile. The results obtained from the theoretical predictions are found to be reasonably in good agreement with the published literature.

Energy Technology Data Exchange (ETDEWEB)

In this book over 250 alloys are organized by AISI number into 10 major sections: Irons, Carbon Steels, Alloy Steels, Low Alloy Constructional Steels, Ultra High Strength Steels, Tool Steels, Maraging Steels, Wrought Stainless Steels, Heat Resistnat Casting Alloys, and Iron Based Rought Superalloys. Each alloy record lists the designation, specifications, UNS number, composition, product forms and a comment on the high-temperature properties and applications. Referenced data is then given for physical properties such as density, specific heat, thermal conductivity, thermal expansion, electrical conductivity, Poisson's ratio, moduli of elasticity and rigidity, etc. Mechanical properties follow, and include tensile properties, shearing and bearing properties, impact properties, creep, stress rupture and stress relaxation and fatigue properties. The last part of the alloy record gives other effects of temperature, ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a method for analyzing the seismic response of a flat bottomed cylindrical liquid storage tank to vertical earthquake excitation. Here, vertical earthquake acceleration is considered to correspond to an increase in the density of a stored liquid. Taking into account the vertical and horizontal earthquake loads, hydrostatic pressure, and considering restrictive moment and shear forces at shell-bottom welded joint, the author has calculated circumferential and longitudinal stresses. These are combined to more accurately approximate the stresses at the base shell course. The calculated result closely conforms to the actual damage, termed ''elephant's foot,'' observed in the fuel storage tanks damaged in the Tangshan earthquake. This result shows that the ''elephant's foot'' phenomenon is not caused by buckling of the ...

International Nuclear Information System (INIS)

Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained-Si (s-Si) p-MOSFETs (metal-oxide-semiconductor field-effect transistors) along (110) and (100) channel directions. In bulk Si, a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field. The combination of (100) direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the (110) direction, opposite to the situation in bulk Si. But the combinational strain experiences a gain loss at high field, which means that uniaxial compressive strain may still be a better choice. The mobility enhancement of SiGe-induced strained p-MOSFETs along the (110) direction under additive uniaxial tension is explained by the competition between biaxial ...

Energy Technology Data Exchange (ETDEWEB)

Crack arrest of fast running cracks is an important issue for the safety of steel structures. Crack arrest design can prevent fatal damage of large structures by restricting the influence of the incidents. Therefore crack arrest design is important especially for very large structure, where accidents may cause huge economical and social losses. Propagating shear fracture, long running ductile crack propagation in pipelines and brittle crack propagation in heavy thick shipbuilding steels have been investigated. For the propagating shear fracture issue, a new HLP simulation model, applicable to various backfill conditions, including underwater backfill, was developed. The proposed backfill model can be applied to the prediction of the crack arrest of propagating shear fracture under various backfill conditions. The new HLP simulation was successful in estimating full-scale burst tests with various backfill depths. The new HLP ...

British Library Electronic Table of Contents (United Kingdom)

The shock stand-off distance of a spherical model flying with transonic speeds is determined through numerical simulations. The model decelerates due to drag forces caused by the pressure and viscous shear stress at the model surface. Two-dimensional axisymmetric numerical codes with numerical grids fixed to the flying spherical model are used in the simulations. Numerically determined shock stand-off distances are compared with experimental data obtained in a previous study as well as with those obtained in our ballistic-range experiments. The numerical results and the experimental data are found to be in good agreement. In addition, the time-dependent shock stand-off distance of a decelerating model is investigated.

CERN Document Server

substrate). Within each group of simulations, three lubricant film thicknesses are studied to examine the effect of varying lubricant thickness. Statistical data are collected from each simulation and presented in this work. Via these data, together with the evolution, of atomic and molecular configurations, a very detailed picture of the properties of this thin film interface is presented. In particular, we conclude that perfluoropolyether lubricant forms distinct molecular layers when confined between two substrates, the rate of heat generation under shearing conditions typical of those in a head-disk interface is insufficient for thermal mechanisms to result directly in lubricant degradation, and mechanical stresses attained in the head-disk interface are unlikely to result in any significant degree of lubricant degradation. This thesis examines the tribology of a head-disk interface in an operating hard disk drive via non-equilibrium ...

British Library Electronic Table of Contents (United Kingdom)

A model is developed to represent mechanical strain, stress-enhanced dissolution, and shear dilation as innately hysteretic and interlinked processes in rough contacting fractures. The model is incorporated into a numerical simulator designed to examine permeability change and thermal exchange in chemically active and deformable fractured reservoirs. A candidate engineered geothermal reservoir system (EGS) is targeted. The mechanistic model is able to distinguish differences between the evolution of fluid transmission characteristics of (1) small scale, closely spaced fractures, and (2) large-scale, more widely spaced fractures. Alternate realizations of fracture frequency and scale, exhibiting identical initial bulk permeability, lead to significantly different conclusions regarding perme...

Energy Technology Data Exchange (ETDEWEB)

Hyaluronic acid (HA) is a significant component of the extracellular matrix (ECM), particular interest being shown herein in synovial fluid. The present study aims to investigate the degrading effects of X-ray radiation on HA at radiotherapy doses. Measurements of viscosity and shear stresses on HA solutions have been made at different shear rates using various types of viscometer for different concentrations in the range 0.01-1% w/v of HA. The HA has been subjected to doses of 6 MV photon radiation ranging from 0 to 20 Gy, the major emphasis being on doses below 5 Gy. It is found that there is a dose-dependent relationship between viscosity and shear rate, viscosity reducing with radiation dose, this being related to polymer scissions via the action of radiation-induced free radicals. The dependency appears to become weaker at higher concentrations, possibly due to the contribution to viscosity from ...

Energy Technology Data Exchange (ETDEWEB)

Copper coatings deposited on Al-6061 substrates by radio frequency magnetron sputtering, to prevent the retention and permeation of energetically implanted tritium in Al-6061, were evaluated by a variety of characterization techniques. The coatings, weighing in the 0.03 to 0.088 kg/m{sup 2} range, were smooth and had a fine grain structure. They contained the intermetallic phases Cu{sub 9}Al{sub 4} and CuAl{sub 2} as well as copper. The fractions of Al and Cu in any coating increased and decreased, respectively, with increasing depth below the surface. Furthermore, the fractions of Al and Cu on the coating surface decreased and increased, respectively, with increasing coating weight. There was no texture or preferred orientation in the Cu phase of the coatings. A significant amount of oxygen was also detected at the original substrate surface. Residual stress measurements revealed that, in both Cu and CuAl{sub 2}, the stresses in the coating ...

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories contracted with Rockwell International Science Center to perform a series of narrowband, pseudo-random cyclic fatigue tests on sections of 6063-T651 aluminum, Darrius-type, vertical axis wind turbine (VAWT) airfoils. We designed and constructed a load member that was mounted within the frame of a rigid 200-kip servohydraulic, closed-loop test system to hold the VAWT section and permit cantilever bending along the shear centerline of the beam. A computer program was developed to synthesize a narrow band, pseudo-random load history with fixed root mean square (RMS) stress levels at a given bandwidth and central frequency. Six specimens each of two different weld configurations at the flange mounting plate were tested at several RMS stress levels with failure defined as visual observation of a 3-inch-long crack in the VAWT. In order to test at as great a frequency as possible, a 20-kip hydraulic ...

Energy Technology Data Exchange (ETDEWEB)

A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

Energy Technology Data Exchange (ETDEWEB)

The characteristics of the local magnetic shear, a quantity associated with high-mode-number ballooning mode stability, are considered in heliotron/torsatron devices that have a large Shafranov shift. The local magnetic shear is shown to vanish even in the stellarator-like region in which the global magnetic shear is positive. The reason for this is that the degree of the local compression of the poloidal magnetic field on the outer side of the torus, which maintains the toroidal force balance, is reduced in the stellarator-like region of global magnetic shear because the global rotational transform in heliotron/torsatron systems is a radially increasing function. This vanishing of the local magnetic shear is a universal property in heliotron/torsatron systems with a large Shafranov shift since it results from toroidal force balance in the stellarator-like global ...

Energy Technology Data Exchange (ETDEWEB)

The two-phase flows involve interfacial interactions which modify significantly the structure of the mean and fluctuating flow fields. The design of the two-fluid models adapted to industrial flows requires the taking into account of the effect of these interactions in the closure relations adopted. The work developed in this thesis concerns the development of first order two-fluid models deduced by reduction of second order closures. The adopted reasoning, based on the principle of decomposition of the Reynolds stress tensor into two statistically independent contributions turbulent and pseudo-turbulent parts, allows to preserve the physical contents of the second order relations closure. Analysis of the turbulence structure in two basic flows: homogeneous bubbly flows uniform and with a constant shear allows to deduce a formulation of the two-phase turbulent viscosity involving the characteristic scales of bubbly turbulence, as well as an ...

CERN Document Server

Heating during frictional sliding is a major component of the energy budget of earthquakes and represents a potential weakening mechanism. It is therefore important to investigate how heat dissipates during sliding on simulated faults. We present results from laboratory friction experiments where a halite (NaCl) slider held under constant load is dragged across a coarse substrate. Surface evolution and frictional resistance are recorded. Heat emission at the sliding surface is monitored using an infra-red camera. We demonstrate a link between plastic deformations of halite and enhanced heating characterized by transient localized heat spots. When sand 'gouge' is added to the interface, heating is more diffuse. Importantly, when strong asperities concentrate deformation, significantly more heat is produced locally. In natural faults such regions could be nucleation patches for melt production and hence potentially initiate weakening during earthquakes at much smaller sliding velocities ...

Energy Technology Data Exchange (ETDEWEB)

Increase usage of magnesium components in the portable electronics industries has propelled considerable research interest on the development of magnesium forging. There have been some studies done in the area of sheet metal forming and forging of axis-symmetrical parts of magnesium alloys but there are very little work done on the plane strain backward extrusion of magnesium alloy. This paper deals with the analysis of plane strain extrusion of magnesium alloy, AZ31, using numerical modeling at different extrusion conditions of temperatures and friction coefficients. A commercially available finite element package, ANSYS/LSDYNA, was used in the finite element analysis. FE simulated results, material deformation, punch force and stress/strain distributions, were compared with actual experimental data. From the numerical analysis, a decrease in forging temperature from 300 C to 250 C will lead to a moderate increase in forming resistance. The forming resistance will ...

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 strain ranges. Slip was localized in Alloy 800 ...

Energy Technology Data Exchange (ETDEWEB)

The effect of transverse magnetic field parameter (Hartmann number, Ha) Reynolds number (Re) and Prandtl number (Pr) on the mixed convection flow past a semi-infinite vertical porous plate in a non-Darcian porous medium with variable viscosity and porosity, viscous dissipation and fluid-solid thermal conductivity ratio in the presence of plate transpiration (lateral mass flux) is investigated theoretically and numerically using Keller`s implicit finite difference scheme. It is shown that the Harmann number acts as a retarding force and increases the momentum boundary layer thickness, analogous to the flow against a positive pressure gradient, simultaneously decreasing local skin friction (shear stress). The heat transfer rate is however enhanced by the magnetic field (for positive values of the Eckert number) since the fluid is heated and temperature gradients become reduced between the fluid and the plate, with important potential applications ...

Energy Technology Data Exchange (ETDEWEB)

The possibility of improving the cold formability of wrought magnesium alloys is considered in light of their good hot forming characteristics. Magnesium alloy AZ31B sheet is selected as a model system. Parameters affecting formability, such as strain hardening rate, strain rate sensitivity, and the degree of anisotropy are examined systematically by conducting tensile tests over a range of temperatures (room temperature to 250 C) and strain rates (1 x 10{sup -5} to 0.1 s{sup -1}). The plastic anisotropy and deformation texture evolution are examined in samples aligned with the sheet rolling and transverse directions. Polycrystal plasticity simulations using a viscoplastic self-consistent (VPSC) formulation are used to model the observed anisotropy and texture evolution. The adjustable parameters in the model are the relative critical resolved shear stresses of the dislocation mechanisms known to operate within magnesium. The experimental ...

International Nuclear Information System (INIS)

As an engineered barrier system in the geological disposal of high-level waste, multibarrier system is considered. Multibarrier system consists of the vitrified waste, the overpack and the buffer. Bentonite is one of the potential material as the buffer because of its low water permeability, self-sealing properties, radionuclides adsorption and retardation properties, thermal conductivity, chemical buffering properties, overpack supporting properties, stress buffering properties, etc. As the construction technology of the buffer, the block installation method and in-situ compaction method, etc, are being investigated. The block installation method is to emplace the buffer blocks manufactured in advance at the ground facility, and construction processes of the block installation method at the underground will be simplified compared with the in-situ compaction method. However, the block joints of buffer might be a mechanical weak portion or might be a preferential ...

Energy Technology Data Exchange (ETDEWEB)

The formation of a quasiequilibrium beam distribution matched to an alternating-gradient quadrupole focusing lattice by means of the adiabatic turn-on of the oscillating focusing field is studied numerically using particle-in-cell simulations. Quiescent beam propagation over several hundred lattice periods is demonstrated for a broad range of beam intensities and vacuum phase advances describing the strength of the oscillating focusing field. Properties of the matched-beam distribution are investigated. In particular, self-similar evolution of the beam density profile is observed over a wide range of system parameters. The numerical simulations are performed using the WARP particle-in-cell code.

International Nuclear Information System (INIS)

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

Medline Plus

... energy. It consists of a stack of piezoelectric ceramics sandwiched under high pressure between two metal cylinders. ...

British Library Electronic Table of Contents (United Kingdom)

A suite of numerical experiments is conducted to extend our previous studies to explore the effects of linear, ambient wind shear on simulated mammatus-like clouds. Increasing values of unidirectional shear result in banded cloud bases, and for the strongest shears roll-type quasi-two-dimensional convection results rather than three-dimensional lobe morphology. Two observed soundings were used, and the sounding with a drier, shallower sub-cloud layer appeared to be most strongly affected by the presence of the ambient shear. The drier sounding also had less snow in the mammatus lobes owing to sublimation. Copyright Copyright 2009 Royal Meteorological Society

British Library Electronic Table of Contents (United Kingdom)

Orthogonal frequency division multiplexing (OFDM) can fully use the frequency band and transmit data at high speeds. The ADSP-TS101 is a high performance digital signal processor (DSP) with good properties that include parallel processing and a high speed. Aimed at the real-time processing requirement of the OFDM algorithm, an underwater acoustic communication system with real-time processing capability is carried out. The system is mainly composed of multiple ADSP-TS101s, a multi-channel synchronous sample module and a field programmable gate array (FPGA) chip. The multiprocessor structure is made up of a cluster/data flow associated multiprocessing parallel processing structure as the operation kernel, and a multi-channel synchronous sample module is designed to realize no phase warp amo...

International Nuclear Information System (INIS)

The Supercritical Water Cooled Reactor(SCWR) operates in a pressure around 25MPa and temperature of 293#approx#510 .deg. C. In order to study the heat transfer behaviors and good comparisons between the various fluids, a heat transfer test loop(SPHINX) using CO_2 has been constructed in KAERI as a part of international research program, I-NERI. At a supercritical pressure, the heat transfer coefficient is much larger than that estimated from the Dittus-Boelter correlation for a relatively large flow rate with moderate wall heat flux conditions. This phenomenon was explained by the rapid variations of the physical properties near the wall with the temperature. On the contrary, the heat transfer becomes worse when the bulk fluid enthalpy is below the pseudo-critical enthalpy under a low flow rate with large heat flux conditions. This phenomenon is called 'deteriorated heat transfer', and which is explained as the modification of the shear stress ...

Energy Technology Data Exchange (ETDEWEB)

Damage and cyclic fatigue failure under alternating loading in transformation-toughened zirconia ceramics is reviewed and compared to corresponding behavior under quasi-static loading (static fatigue). Current understanding of the role of transformation toughening in influencing cyclic fatigue-crack propagation behavior is examined based on studies which altered the extent of the tetragonal-to-monoclinic phase transformation in MG-PSZ through subeutectoid aging. These studies suggest that near-tip computations of the crack-driving force (in terms of the local stress intensity) can be used to predict crack-growth behavior under constant amplitude and variable-amplitude (spectrum) loading, using spatially resolved Raman spectroscopy to measure the extent of the transformation zones. In addition, results are reviewed which rationalize distinctions between the crack-growth behavior of preexisting, long'' (> 2 mm), through-thickness cracks and ...

Science.gov (United States)

... Title : STRESS ANALYSIS OF AN AUTOFRETTAGED LOOSE LINER FOR GUN BARREL CONSTRUCTION PRECOMPRESSED IN THE ...

Energy Technology Data Exchange (ETDEWEB)

The signature of the negative snakes from the soft X-ray cameras is very similar to the more usual snakes except that the localised region of the snake has, compared with its surroundings, decreased rather than increased emission. Circumstances where negative snakes have been seen are reviewed. The negative snake appears as a region of increased resistance and of increased impurity density. The relationship between the shear and the current perturbation is shown, and it seem probable that the magnetic shear is reversed at the point of the negative snake, i.e. that q is decreasing with radius. 6 refs., 6 figs.

International Nuclear Information System (INIS)

A new high strength titanium alloy has been developed primarily intended for fastener applications. While Ti-6Al-4V is used extensively as a fastener alloy in the aerospace industry, its shear strength allowable is limited to 655 MPa (95 ksi). For higher shear strength requirements, various steels or nickel-based alloys are used (up to 860 MPa (125 ksi)), but with the attendant density penalty. This new alloy is intended to provide the 860 MPa shear strength at roughly a 40% weight savings. After screening various alloy systems, the optimum chemistry has been selected as follows: Ti-6.0V-6.2Mo-5.7Fe-3Al. In light of its 125 ksi shear strength goal, the alloy has been designated TIMETAL reg-sign 125.

International Nuclear Information System (INIS)

A new implementation of a shear-force microscope is described that uses a shear-force detection system to perform topographical imaging of large areas (#approx#1x1 mm"2). This implementation finds very interesting application in the study of archeological or artistic samples. Three dc motors are used to move a sample during a scan, allowing the probe tip to follow the surface and to face height differences of several tens of micrometers. This large-area topographical imaging mode exploits new subroutines that were added to the existing homemade software; these subroutines were created in Microsoft VISUAL BASIC 6.0 programming language. With this new feature our shear-force microscope can be used to study topographical details over large areas of archaeological samples in a nondestructive way. We show results detecting worn reliefs over a coin.

Science.gov (United States)

... In: Separated Flows, AGARD CP No. ... on thin wings in two-dimensional incompressible flow. ... fields in the region of separating and reattaching flows. ...

Science.gov (United States)

... Accession Number : ADA539720. Title : A Hybrid Kinetic Model of Asymmetric Thin Current Sheets with Sheared Flows in a Collisionless Plasma. ...

Energy Technology Data Exchange (ETDEWEB)

Testing results obtained from simple shear and direct shear tests were conducted for investigating the frictional properties between steel pile shaft and silty clay in this paper. By using the analyzed results of these tests, a hyperbolic curve fitting method for estimating skin friction of pile shaft was proposed in which was verified by its application on the results of undrained uplift triaxial model pile tests.

Energy Technology Data Exchange (ETDEWEB)

This research involves the development of an analysis which yielded recommendations regarding the plate thickness at which the effects of transverse shear become significant enough to be taken into consideration during vibration testing of composite plates. The specimens designed using this analysis are to be used for the {open_quotes}inverse{close_quotes} problem of determining through-the-thickness elastic constants as well as in-plane elastic constants from modal vibration response data. The effects of transverse shear were studied over the range of practical plate aspect ratios (length to thickness ratios) and mode numbers. Behavior of composite plates ranging from isotropic to highly orthotropic was studied in order to investigate the effects of transverse shear. Orthotropic plates having in-plane dimensions of 254 x 254 mm and thicknesses varying from 10 mm to 80 mm, with free-free edge boundary conditions, were ...

UK PubMed Central (United Kingdom)

Senescence is regarded as a physiological response of cells to stress, including telomere dysfunction, aberrant oncogenic activation, DNA damage, and oxidative stress. This stress response has an antagonistically...Full Text Available

CERN Document Server

In this paper we study half-BPS type IIB supergravity solutions with multiple $AdS_3\\times S^3\\times M_4$ asymptotic regions, where $M_4$ is either $T^4$ or $K_3$. These solutions were first constructed in [1] and have geometries given by the warped product of $AdS_2 \\times S^2 \\times M_4 $ over $\\Sigma$, where $\\Sigma$ is a Riemann surface. We show that the holographic boundary has the structure of a star graph, i.e. $n$ half-lines joined at a point. The attractor mechanism and the relation of the solutions to junctions of self-dual strings in six-dimensional supergravity are discussed. The solutions of [1] are constructed introducing two meromorphic and two harmonic functions defined on $\\Sigma$. We focus our analysis on solutions corresponding to junctions of three different conformal field theories and show that the conditions for having a solution charged only under Ramond-Ramond three-form fields reduce to relations involving the positions of the poles ...

Energy Technology Data Exchange (ETDEWEB)

Scour around offshore structures is well known. It is caused by the strong eddy formation at the base of the structures protruding from the sea bottom. The strong vortices result in an amplified effective shear stress working on the sea bottom surface adjacent to the structure. When the surrounding sea bottom is lowered the scour protection will end up being a cap on a small hill and when the slopes are getting too steep the scour protection will roll or slide down the sides. It will loose its cohesion and therefore its integrity. This will take place irrespective of the type of scour protection material and the type of scour protection. This report describes scour protections, which can deal with this particular problem. Such a scour protection must be able to sustain the following loads: Be able to follow the lowering of the seabed on its way down; Be resistant to edge scour (scour around the perimeter of the scour protection). The ...

Science.gov (United States)

No Abstract Available

Norwegian Open Research Archives (NORA)

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Science.gov (United States)

Sep 16, 2010 ... Taking military operations as an example, there is evidence that stress-related behavioral disorders and mental conditions such as anxiety, ...

Energy Technology Data Exchange (ETDEWEB)

This thesis develops methods for recording and analysis of seismo-acoustic interface waves for determination of shear wave velocity as a function of depth and includes this in standard refraction seismic surveying. It investigates different techniques for estimation of dispersion characteristics of the interface waves and demonstrates that multi sensor spectral estimation techniques improve the dispersion estimates. The dispersion estimate of the fundamental interface wave mode is used as input to an object function for a model based linearized inversion. The inversion scheme provides an estimate of the shear wave velocity as a function of depth. Three field surveys were performed. Data were acquired with a standard bottom deployed refraction seismic hydrophone array containing 24 or 48 receivers, with a receiver spacing of 2.5 m. Explosive charges were used as sources. The recording time was increased from 0.5 to 8 s, compared to standard ...

British Library Electronic Table of Contents (United Kingdom)

An assessment of the joint shear strength of exterior concrete beam-column joints reinforced internally with Glass Fibre Reinforced Polymer (GFRP) reinforcements under monotonically increasing load on beams keeping constant load on columns is carried out in this study. Totally eighteen numbers of specimens are cast and tested for different parametric conditions like beam longitudinal reinforcement ratio, concrete strength, column reinforcement ratio, joint aspect ratio and influence of the joint stirrups at the joint. Also finite element analysis is performed to simulate the behaviour of the beam-column joints under various parametric conditions. Based on this study, a modified design equation is proposed for assessing the joint shear strength of the GFRP reinforced beam-column specimens b...

International Nuclear Information System (INIS)

The performance of different polymers used to flocculate red mud particulate materials in the Bayer process can be evaluated on the basis of their efficiency to achieve adequate settling velocities and turbidity levels. In this study, three commercially available flocculants are evaluated under typical conditions found in the last washer of a Bayer plant. The different shear levels are produced by using a modified Couette flow system. Great differences are noticed in the performance of the polymers when they are compared at different dosages and at different shear rate levels. The data collected also suggests that conventional cylinder settling tests may not be adequate to measure the performance of certain types of polymers. (author)

Energy Technology Data Exchange (ETDEWEB)

We have demonstrated that the SSSE pulverization process can convert multicomponent plastic waste into a powder with very promising properties. A variety of mixed color plastic chips have been pulverized.

Science.gov (United States)

Approximately 1.2 million kg of uranium oxide (yellow cake) has been produced from the area surrounding Gunnison, Colorado. Over 99 percent of this has come form the Cochetopa and Marshall Pass districts. Uranium in both districts and many of the other occurrences is associated closely with fault and shear zones which cut brittle host formations (sandstones and dolomites) of Paleozonic and Mesozoic age. Minor uranium occurrences are in pegmatites and shear zones in Precambrian rocks, Cambrian vein material, and sandstones of Tertiary age. In the paper presented, the uranium occurences are described by districts. In addition, possibilities for additional discoveries are discussed. (JMT)

Energy Technology Data Exchange (ETDEWEB)

Fastening systems for parts that endure high vibration shear loads have traditionally been difficult or expensive to produce. This application describes a fastening system with multiple conical surfaces and eccentric offsets. The novel conical fastener system allows parts to be assembled with reduced tolerance controls at interface features while improving alignment precision. The eccentric conical fastening system is particularly well suited for assemblies with high shear loads in high vibration/shock environments, and/or for systems that have extremely precise pointing requirements.

UK PubMed Central (United Kingdom)

Stress has been reported to be a causative factor for male infertility. Withania somnifera has been documented in Ayurveda and Unani medicine system for its stress-combating properties....Full Text Available

UK PubMed Central (United Kingdom)

Rate of dehydration greatly affects desiccation tolerance of recalcitrant seeds. This effect is presumably related to two different stress vectors: direct mechanical or physical stress because of the...Full Text Available

UK PubMed Central (United Kingdom)

Plant roots exhibit remarkable developmental plasticity in response to local soil conditions. It is shown here that mild salt stress stimulates a stress-induced morphogenic response (SIMR) in Arabidopsis...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundIt is known that diabetes and stress are directly or indirectly related, and that it is important to evaluate stress in patients with diabetes. The relationship between...Full Text Available

UK PubMed Central (United Kingdom)

IntroductionChest pain with ST-segment elevation is a rare clinical problem during dobutamine stress testing. Although beta-agonists treatment prior to dobutamine stress testing...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A plane stress constitutive relation is developed for laminate composites undergoing matrix cracking and therefore displaying significant nonlinear stress-strain behavior. The constitutive relation is similar in some respects to a phenomenological theory of plasticity in that it is fit to data from uniaxial tests. The constitutive equations are specialized to brittle matrix composites (especially CMCs) in the form of cross-piles and quasi-isotropic laminates. Several problems involving stress redistribution at holes and notches due to nonlinear stress-strain behavior are investigated with the aid of the constitutive law.

Science.gov (United States)

... Mirrors (Preprint) Ryan Conk et al. 15 September 2006 ... 4. TITLE AND SUBTITLE Stress Coatings for Large Scale Membrane Mirrors (Preprint) 5a. ...

UK PubMed Central (United Kingdom)

We explored transcriptional responses of the fission yeast Schizosaccharomyces pombe to various environmental stresses. DNA microarrays were used to characterize changes in expression...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Electron cyclotron emission (ECE) can be used to determine the electron temperature profile in magnetized plasmas. The complex structure of the magnetic field configuration in the Large Helical Device (LHD), which has a large shear, complicates the analysis of the ECE spectrum. In a sheared magnetic field the propagation of X and O-mode polarization through the plasma are coupled, causing mode conversion and polarization rotation. Mode scrambling is also caused by wall reflections. In this report, this mode conversion in LHD is numerically analyzed. It was found that at low density mode conversion scrambles the ECE spectra. However, at higher density (n{sub eo} > 1.0{center_dot}10{sup 19} m{sup -3}) the polarization mode is found to rotate with the sheared magnetic field, yielding only a negligible mode conversion. Wall reflections are found to depolarize the ECE spectrum. Notwithstanding the LHD magnetic ...

Energy Technology Data Exchange (ETDEWEB)

The electronic structure and properties of the cubic Laves phase (C15) compounds ZrZn/sub 2/ and ZrV/sub 2/ have been determined using our all-electron full-potential linearized-augmented-plane-wave (FLAPW) method for bulk solids. The computations were performed in two stages: (i) self-consistent warped muffin tin and (ii) self-consistent full potential. Spin-orbit coupling was included after either stage. The effects of the inclusion of the nonspherical terms inside the muffin tins on the eigenvalues is found to be small (of order 1 mRy). However, due to the fact that some of the bands near the Fermi level are flat, this effect leads to a much higher value of the density of states at E/sub F/ in ZnZr/sub 2/. The most important difference between the materials ZrZn/sub 2/ and ZrV/sub 2/ is the position of the d bands derived from the Zr and V atoms. Consequently, these materials have completely different Fermi surfaces. We have investigated the magnetic properties ...

Science.gov (United States)

PMID:747753

Science.gov (United States)

The threshold stress itensities for stress corrosion crack propagation in beta titanium alloy 38-6-44, Ti-3Al-8V-6Cr-4Mo-4Zr, has been determined in salt water and methanolic solutions. The alloy was immune to stress corrosion cracking in aqueous sodium c...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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Science.gov (United States)

Not Available

Science.gov (United States)

Necessary theoretical foundation is given for the treatment of magnetic stresses applied to

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

... THE STRENGTH, TOUGHNESS, AND STRESS-CORROSION CRACKING SUSCEPTIBILITY OF A METASTABLE BETA TITANIUM ALLOY (Ti-11. ...

Science.gov (United States)

Not Available

Science.gov (United States)

... Attributes and limitations of the charac- terization framework are illustrated through comparison with experimental PLZT data. ...

International Nuclear Information System (INIS)

In previous work, on cooling from 300 K to 10 K the elastic moduli for both #alpha#- and #delta#-Pu dropped 30%. This large change may reflect effects of 5f-electron localization. In this work, the elastic moduli at ambient temperature of several Pu-Ga alloys were measured using resonant ultrasound spectroscopy (RUS). The strong temperature dependence of the bulk and shear modulus and the temperature independence of Poisson's ratio was confirmed and the upper temperature limit for #alpha#-Pu was extended to 360 K. Measurements of the time dependence of the shear moduli of Pu and Pu-2.36 at.% Ga were determined with high precision as a function of time and temperature. Using a model for time dependence of point defects, we determined the exponential time constant at ambient temperature for such variations. The low temperature results are consistent with Fluss .

Science.gov (United States)

A method for simplifying finite element models of structures having a beam-like global dynamical behaviour is presented. This method is based on the use of a general uniform beam finite element formulation. It takes into account both transverse shear effects and dynamical coupling between bending and torsion due to the fact that mass centres and shear centres do not always coincide. For that purpose, we develop a condensation method for reducing any shell model into an equivalent beam, as well as a technique for automatically identifying the corresponding set of beam parameters. The method is applied to several illustrate examples that demonstrate its ability to simplify finite element models for many kinds of sophisticated structures having a beam-like predominant behaviour.

Energy Technology Data Exchange (ETDEWEB)

Considerable interest has focused recently on the use of lignocellulosic fibers as a reinforcement for thermoplastic polymers. The combination of these dissimilar materials, however, is characterized by a widespread incompatibility that leads to a weak fiber/polymer interface and poor performance properties for the composite. In an effort to improve compatibility a number of fiber surface modification approaches have been investigated including plasma, ozone, and polymer grafting treatments. Evaluation of adhesion improvements has been complicated by processing variables that are difficult to control. This paper will discuss the use of the-micro-debond test in quantifying the interfacial shear strength (ISS) in wood fiber/polystyrene composites. Wood fibers were modified to different degrees with styrene-maleic anhydride copolymers that varied in their composition. The effect of fiber modification on surface energetics was determined using dynamic contact angle ...

Science.gov (United States)

The purpose of this study is to search for a new method of dispersing spilled heavy oil, which has a detrimental effect on the natural environment and marine ecosystem. A method ejecting a waterjet vertically downward to heavy oil on the water surface was studied, particularly focusing on the effect of the guide nozzle shape. The waterjet comprised heavy oil and minute air bubbles, and passed through the hole of the guide nozzle. Thirteen guide nozzle shapes were tested and compared. The dispersion efficiency of a tapered hole was the best among the 13 nozzles. The flow in the hole of the guide nozzles was recorded by a high-speed video camera. The occurrence of two flows, regular and counter flows, was observed in the taper guide nozzle. It seemed that the counter flows generated the shearing force between the waterjet and the heavy oil layer. It is considered that the shearing force determines the surplus efficiency of disperse.

British Library Electronic Table of Contents (United Kingdom)

VHF wind-profiling radars often measure a decrease of echo power with zenith angle, which can be explained from in situ measurements of horizontal layering or anisotropy of metre-scale temperature structure in the atmosphere. There can also be an azimuthal variation of echo power, which is increased in an azimuth opposite to the vertical shear vector of horizontal wind. This paper checks if the azimuth variation can also be linked to in situ observations of temperature structure, using aircraft flights in the tropopause region near a VHF radar. At heights where VHF radar measures wind shear and aspect sensitivity, there can be an asymmetry in the probability distribution of horizontal gradient of potential temperature, for horizontal scale of e.g. hundreds of metres. The asymmetry is often...

Energy Technology Data Exchange (ETDEWEB)

The macroscopic stress distribution across an annealed Zircaloy-4 gas tungsten arc weld was measured by neutron time-of-flight diffraction at the SMARTS diffractometer at Los Alamos National Laboratory. The stresses after annealing are about 40% lower than those in the same weld prior to heat treatment. The intergranular strains in the reference coupons, which give the macroscopic stress free lattice spacings, are consistent with the difference in cooling the strongly textured plate and the weakly textured weld.

Science.gov (United States)

In this project the influence of residual compression stresses on the stress corrosion cracking behaviour of the turbine disc steel 26 NiCrMoV 14 5 (Rp(sub 0.2) = 850 N/mm(sup 2)) was investigated. The residual compression stresses were produced by shot p...

Energy Technology Data Exchange (ETDEWEB)

Today`s nuclear power plants are marked by increasing needs for non-destructive inspection techniques in preventive maintenance programs. Additionally, it is becoming more important to evaluate residual stress which may be a key parameter for crack propagations in welded pipings. The authors have developed an ultrasonic velocity measurement method which obtains ultrasonic velocity changes by residual stress with a high accuracy. The ultrasonic velocity measurement is composed of three procedures. They are as follows. (1) Highly accurate propagation time measurements; (2) Pipe thickness correction; (3) Residual stress evaluation. The ultrasonic velocity measurements have been applied to the residual stress evaluation of carbon steel welded pipings. Destructive testing using stress strain gauges was done after the ultrasonic non-destructive evaluation of the residual ...

Energy Technology Data Exchange (ETDEWEB)

We describe exact cosmological solutions with rotation and expansion in the low-energy effective string theory. These models are spatially homogeneous (closed Bianchi type IX) and they belong to the family of shear-free metrics which are causal (no closed timelike curves are allowed), admit no parallax effects and do not disturb the isotropy of the background radiation. The dilaton and the axion fields are nontrivial, in general, and we consider both cases with and without the central charge (effective cosmological constant)

Energy Technology Data Exchange (ETDEWEB)

A quantitative description is proposed for the depletion-induced slip thickness and velocity profile of a polymer solution near the wall-fluid interface in simple shear flow. The inhomogeneous polymer density profile at a flat wall is inserted into the equations of motion for the flow of a polymer solution near the flat wall. The theory is in quantitative agreement with simulation results. (letter to the editor)

Energy Technology Data Exchange (ETDEWEB)

Methods of solving Navier-Stokes equations for turbulent channel flow are given. These numerical solutions utilize either Neumann or Dirichlet boundary conditions. Computer codes were written and tested and are discussed. Digital image processing of flow visualization video sequences, taken simultaneously with vorticity probe measurements in a turbulent boundary layer, were carried out. 4 figs. (GHH)

Energy Technology Data Exchange (ETDEWEB)

Lifetimes have been measured for dipole bands in {sup 142}Gd using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (shears mechanism with Principal Axis Cranking) models. The dipole bands DB1 to DB4 can be interpreted as magnetic rotational bands. (orig.)

International Nuclear Information System (INIS)

It is shown that the section of the energy surface corresponding to the longitudinal mode by the principal xy-plane for the A-15 compounds will degenerate into four points at the corners of a square at very low temperatures in the cubic phase. When the quasi-shear mode propagating along the (110) direction becomes soft, simultaneously the longitudinal mode will exhibit unusually high phonon focussing. (author).

Energy Technology Data Exchange (ETDEWEB)

Anomalous features in Gulf Coast Salt domes exhibit deviations from normally pure salt and vary widely in form from one dome to the next, ranging considerably in length and width. They have affected both conventional and solution mining in several ways. Gas outbursts, insolubles, and potash (especially carnallite) have led to the breakage of tubing in a number of caverns, and caused irregular shapes of many caverns through preferential leaching. Such anomalous features essentially have limited the lateral extent of conventional mining at several salt mines, and led to accidents and even the closing of several other mines. Such anomalous features, are often aligned in anomalous zones, and appear to be related to diapiric processes of salt dome development. Evidence indicates that anomalous zones are found between salt spines, where the differential salt intrusion accumulates other materials: Anhydrite bands which are relatively strong, and other, weaker impurities. ...

British Library Electronic Table of Contents (United Kingdom)

This paper studies the electrical characteristics of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) under flat and bending situations after AC/DC stress at different temperatures. Stress temperature was varied from 77K to 400K, and threshold voltage shifts were extracted to analyze degradation mechanisms. It was found that high temperature and mechanical bending played important roles under AC stress, with an enhanced stress effect resulting in a more serious degradation. This study also discusses the dependence between the accumulated sum of bias rising and falling time and the threshold voltage shifts under AC stress.

Energy Technology Data Exchange (ETDEWEB)

The aim of this study is to develop the methodology which enables to identify the mechanical properties of element such as stress intensity factor by using the AE parameters. Considering the multivariate and nonlinear properties of AE parameters such as ringdown count, rise time, energy, event duration and peak amplitude from fatigue cracks of machine element the principal component regression(PCR) and artificial neural network(ANN) models for the estimation of stress intensity factor were developed and validated. The AE parameters were found to be very significant to estimate the stress intensity factor. Since the statistical values including correlation coefficients, standard mr of calibration, standard error of prediction and bias were stable, the PCR and ANN models for stress intensity factor were very robust. The performance of ANN model for unknown data of stress intensity ...

UK PubMed Central (United Kingdom)

Vulnerability to xylem embolism by freeze-thaw cycles and water stress was quantified in ring-porous (Quercus gambelii Nutt.), diffuse-porous (Populus tremuloides Michx.,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The temperature dependence of the dislocation mobility threshold is investigated on the basis of a dislocation model suggested by Frenkel-Kontorova. The critical value is obtained for the stress/temperature, corresponding to the dislocation depinning from its equilibrium position. The universal behaviour of a barrier height at finite stress and temperature is revealed and investigated.

UK PubMed Central (United Kingdom)

Stress strongly inhibits proliferation of granule cell precursors in the dentate gyrus, while voluntary running has the opposite effect. Few studies, however, have examined the possible effects...Full Text Available

UK PubMed Central (United Kingdom)

The RNA-binding protein Hfq is recognized as an important regulatory factor in a variety of cellular processes, including stress resistance and pathogenesis. Hfq has been shown in several bacteria to...Full Text Available

International Nuclear Information System (INIS)

Research highlights: ? Correlations between microstructure and internal stress during Ti anodising are established. ? Large internal compressive stresses are accumulated in the film during anodising upto 12 V. ?A transition from compressive to tensile stress is observed when the cell voltage exceeds 12 V. ? At 40 V, the oxide films consist of two regions with different compositions and microstructures. Crystallisation of amorphous to anatase TiO2 contributes to the compressive stress relaxation. - Abstract: The relationship between the microstructural and internal stress evolution during Ti anodising is discussed. Samples anodised galvanostatically to 12 V and 40 V, corresponding to different stages of the internal stress evolution, were examined by in-plane and cross-section transmission electron microscopy. Electron diffraction patterns have been complemented ...

CERN Document Server

Residual Stresses in Ta, Mo, Al and Pd Thin Films Deposited by E-Beam Evaporation Process on Si and Si/SiO 2 Substrates

UK PubMed Central (United Kingdom)

BackgroundThe aim of this double-blind randomized study is to test the efficacy of a radio electric stimulator device using an auricular reflex therapy protocol for stress-related...Full Text Available

UK PubMed Central (United Kingdom)

The osmoprotectant Pro betaine is the main betaine identified in alfalfa (Medicago sativa). We have investigated the long-term responses of nodulated alfalfa plants to salt stress,...Full Text Available

Wastenet

... Austrian Environment Minister Nikolaus Berlakovich called for such stress tests on Sunday (13 March) to make sure that nuclear power stations were quake-proof following Japan's massive earthquake and tsunami. Austria, a mountainous country rich in geothermal energy, has no NPPs and no plans to develop ...

UK PubMed Central (United Kingdom)

Mitochondrial heat shock protein 70 (mtHSP70) is found to play a primary role in cellular defense against physiological stress like exposure to environmental contaminants and helpful in the maintenance...Full Text Available

International Nuclear Information System (INIS)

The problems of the thermal stress in concrete structures are roughly divided into the initial stress due to setting heat and the stress due to external temperature after hardening. The initial stress exists in every concrete structure, and it is usually neglected in beams and columns, but it must be taken into account in case of the foundation mat structures in nuclear power stations, for example. In this paper, (1) the results of measurement of temperature, strain and stress in each lift at the time of and after placing concrete in the foundation mat of a nuclear power station and the comparison of them with the results of analysis, (2) the results of measurement of the temperature and stress in a foundation mat, which was carried out to rationalize the design method for the raft type foundation mats in thermal power stations, and (3) the results of ...

UK PubMed Central (United Kingdom)

SummaryMycobacterium tuberculosis has 10 universal stress proteins, whose function is unknown. However, proteomic and transcriptomic analyses have shown that a number...Full Text Available

UK PubMed Central (United Kingdom)

Accumulation of molecular damage and increased molecular heterogeneity are hallmarks of cellular aging. Mild stress-induced hormesis can be an effective way for reducing the accumulation of molecular...Full Text Available

UK PubMed Central (United Kingdom)

Neurons in the hippocampal CA1 region are particularly sensitive to oxidative stress (OS), whereas those in CA3 are resistant. To uncover mechanisms for selective CA1 vulnerability to OS, we...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundA strong association between stress resistance and longevity in multicellular organisms has been established as many mutations that extend lifespan also show increased...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundClara cell protein (CC16), the main secretory product of bronchiolar Clara cells, plays an important protective role in the respiratory tract against oxidative stress and...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundTrichloroethylene (TCE) may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radical scavenging enzymes.MethodsTwenty...Full Text Available

UK PubMed Central (United Kingdom)

Small RAC/ROP-family G proteins regulate development and stress responses in plants. Transient overexpression and RNA interference experiments suggested that the barley (Hordeum vulgare)...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Iron undergoes a polymorphic phase transformation from alpha phase (bcc) to the epsilon phase (hcp) when compressed to stresses exceeding 13 CPa. Bccause the epsilon phase is denser than the alpha phase, a single shock wave is unstable and breaks up into an elastic wave, a plastic wave, and a phase transition wave. Examination of this structured wave coupled with various phase transformation models has been used to indirectly examine the transition kinetics. Recently, multimillion atom simulations (molecular dynamics) have been used to examine the shock-induced transition in single crystal iron illustrating an orientation dependence of the transition stress, mechanisms, and kinetics. The objective of the current work was to perform plate impact experiments to examine the shock-response of polycrystalline and single crystal iron with nanosecond resolution for impact stresses spanning the {alpha} - {epsilon} transition. The ...

UK PubMed Central (United Kingdom)

BackgroundBallet Dancers have been shown to have a relatively high incidence of stress fractures of the foot and ankle. It was our objective to examine MR imaging patterns of bone...Full Text Available

UK PubMed Central (United Kingdom)

The aim of the present study was to evaluate the ameliorative potential of quercetin (QC) against paracetamol (PCM)-induced oxidative stress and biochemical alterations in mice blood. A total of 36...Full Text Available

UK PubMed Central (United Kingdom)

Biological membranes are lamellar structures composed of two leaflets capable of supporting different mechanical stresses. Stress differences between leaflets were generated during micromechanical experiments...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

We report a case of stress fracture of the clavicle associated with sternocostoclavicular hyperostosis. A 60-year-old man sustained a stress fracture of the right clavicle with no history of trauma. On radiography, hyperostosis of the anterior chest wall and ankylosis of the sternoclavicular joint were evident in addition to the fracture. Fracture healing was uneventful after 2.5 months. Ankylosis of the sternoclavicular joint may have caused increased stress at the midshaft of the clavicle by daily activity or minor trauma. Such a fracture is a rare complication of sternocostoclavicular hyperostosis. (orig.)

KoreaScience (Korea)

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International Science & Technology Center (ISTC)

Studies of the Superheavy-metal Effect as a Stress-factor on Protein Biosynthesis and Cytoskeleton Integrity in Animal Cells

International Nuclear Information System (INIS)

... Industry, Material Science Research Laboratory, Yokosuka, Kanagawa (Japan)

International Nuclear Information System (INIS)

Results of investigation of stress corrosion cracking of steam turbine materials in nuclear, fossil and geothermal power plants have been analysed. The role of factors that cause damage to rotor discs, mono block and welding rotors of steam turbines has been shown. These are yield stress and steel composition, stress intensity coefficient and crack growth rate, composition and temperature of the condensed steam and water, electrochemical conditions. The conclusion has been made about the state of stress corrosion cracking of the rotors materials, and main investigation trends which are necessary to solve this problem have been listed.

Energy Technology Data Exchange (ETDEWEB)

Stress relaxation was studied at 408 K on AZ31 reinforced by ceramic foam produced by in situ foaming of filler loaded preceramic polymer melt. Reinforcement causes significant enhancement of the resistance against stress relaxation compared to AZ91. It is correlated with hardening by the ceramic skeleton as well as ceramic particles formed in the AZ31-matrix. (orig.)

UK PubMed Central (United Kingdom)

Stress exposure increases the risk of addictive drug use in human and animal models of drug addiction by mechanisms that are not completely understood. Mice subjected to repeated forced swim stress...Full Text Available

Science.gov (United States)

During the erection of the Sandia 34-Meter VAWT Test Bed, the induced gravitational stress state in the turbine blades and their associated deflections were measured. This manuscript details the measurements that were taken on the Test Bed blades during erection and compares them to the stresses and deflections predicted by the NASTRAN finite element code.

International Nuclear Information System (INIS)

The constituent phases and associated deformed microstructure of the quenched Ti-xNb-(0.5-1.5) at.% Si alloy consisting of non-cytotoxicity elements, where x = 24-30 at.%, were investigated to provide pseudoelasticity for biomedical and sensor applications. Optical microscopy revealed that stress-induced martensitic transformation takes place during the deformation in the present alloys. It is confirmed from the X-ray diffraction results of the deformed specimens that the crystal structure of the stress-induced martensite phase is the orthorhombic so-called #alpha#'' structure. Within the alloys having #beta#(bcc) phase studied Nb-poor region appeared to exhibit a dominant behavior for stress-induced martensitic transformation than Nb-rich region. This result suggests that metastable #beta# phase is superior to stable #beta# phase for the occurrence of stress-induced martensitic transformation in the ...

British Library Electronic Table of Contents (United Kingdom)

Harvested plant organs such as heads of broccoli (Brassica oleracea L. var. italica) experience a range of stresses that can lead to premature reduction in quality and eventual senescence. Understanding plant responses to stress may open up novel opportunities to extend postharvest life. One of the first stresses experienced by harvested organs is likely to be water deficit stress since severance of the vascular system halts the normal flux of water into the tissue. For broccoli branchlets with their cut ends held in water, transcriptome analysis based on hybridization of broccoli floret mRNA to a heterologous Arabidopsis microarray revealed that the transcript abundance of 431 genes reliably changed within 48h of harvest. Of these, transcripts of 146 genes increased and 34 genes decreased...

Energy Technology Data Exchange (ETDEWEB)

The accurate measurement of a stress level is one of the most important issues in a stress diagnosis and its measurement could be of great value in clinical medicine. Stress has a potent effect on the spirit and physical condition of an individual. There are various methods available for its measurement. Some of the commonly used techniques for the diagnosis of a stress level include analysis of the body fluids, questionnaire assessments, psychophysiological evaluations and by determining heart rate variability (HRV) of subjects. However, the existing diagnostic methods have several defects like, a low sensitivity, inaccuracy and long of operation time. In this report, we present a diagnostic technology to detect a stress level which is the origin of various diseases. This method can be of great help in providing an early diagnosis through a biosensor and might play a vital role in ...

International Nuclear Information System (INIS)

The combined effects of environment, yield strength and stress state on the cracking susceptibility of beta-extruded Ti-6Al-6V-2Sn have been examined. At a constant yield strength and under plane strain conditions, the stress intensity required for slow crack propagation decreased as the severity of the environment increased, i.e., from laboratory air to 3.5% NaCl. Furthermore, the crack propagation rates were a function of both stress intensity, and environmental severity. Although the fracture toughness and threshold stress intensities for slow crack growth generally decreased with increasing yield strength, aging, which resulted in the precipitation of ordered Ti3Al particles in the primary alpha phase, tended to accentuate the susceptibility of this alloy to sustained load/stress corrosion cracking. Finally, at constant yield strength, the sustained load cracking threshold ...

Energy Technology Data Exchange (ETDEWEB)

The code of ASME Sec. III prescribes the general rules upon the design of a NSSS (nuclear steam supply system). The code provides further flexibility to the design of the nuclear structures by introducing a design by analysis concept. But it still preserves the conservatisms in design works by imposing strict failure mechanism and controlling material properties in use. A designer should prove the integrity of a structure under consideration by comparing the stress intensity, which was driven from the linearization of stress at concerning section, with the prescribed one. The recent development in computing system has enabled the commercial finite element programs to be a prevailing way to structural analysis field. But only few programs provide the procedure for stress linearization through the post-processing stage. Therefore, the simplified method which uses nodal stresses over the concerning section ...

Energy Technology Data Exchange (ETDEWEB)

The X-ray diffraction analysis of (U,Ce)O{sub 2} with the CeO{sub 2} contents ranging from 0 to 20 mol% CeO{sub 2} was performed at room temperature to obtain the variation in the lattice parameter with the CeO{sub 2} content. Ultrasonic pulse echo measurements were also carried out to estimate the change in the mechanical properties of (U,Ce)O{sub 2} with the CeO{sub 2} content. The lattice parameter of (U,Ce)O{sub 2} was found to decrease with increasing CeO{sub 2} content. The variation in the lattice parameter with the CeO{sub 2} content closely followed the Vegard law. The shear and longitudinal velocities in (U,Ce)O{sub 2} were found to decrease with increasing CeO{sub 2} content. The Young`s and shear moduli, and Poisson`s ratio estimated from the wave velocities decreased with the CeO{sub 2} content. No mechanical property showed anomaly in low CeO{sub 2} content region. (orig.).

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Despite their high medical relevance, the principles of lubrication in natural joints are still unclear. It is generally accepted, that the presence of hyaluronic acid (HA), the main component of the synovial liquid, plays an important role for the low friction observed. Furthermore, it is assumed that surface active lipids participate in the lubrication. Using a model system of lipid bilayers deposited on a polyelectrolyte (PE) cushion and in contact with HA solution, we started to investigate the effects of pressure and shear forces, as experienced by natural joints, on the internal structure of the SiO{sub 2}/PE/lipid/HA interface and the bulk HA solution by neutron reflectometry (NR), complemented by in situ ellipsometry and quartz crystal microbalance (QCM-D) measurements. Only on positively charged polyelectrolyte surfaces, the successful build-up of the model system could be demonstrated. By NR, the existence of an irreversibly absorbed, highly hydrated HA ...

Science.gov (United States)

The Bingham plastic constitutive model has been widely used to predict the post-yield behavior of electro- and magneto- rheological fluids (ER and MR fluids). However, if these fluids experience shear thinning or shear thickening, the Bingham plastic model may not be an accurate predictor of behavior, since the post-yield plastic viscosity is assumed to be constant. In a recent study, it was theoretically and experimentally demonstrated that the Herschel-Bulkley fluid model can be successfully employed when evaluating non- Newtonian post-yield behavior of ER and MR fluids. In this paper, the Herschel-Bulkley model is employed to include a detailed analysis of ER and MR fluid dynamics through pipes and parallel plates. Simplified explicit expressions for the exact formulation are also developed. It is shown that the proposed simplified model of the Herschel-Bulkley steady flow equations for pipes and parallel plates can be used as an accurate ...

International Nuclear Information System (INIS)

The process of miniemulsification allows the generation of small, homogeneous, and stable droplets containing monomer or polymer precursors and magnetite which are then transferred by polymer reactions to the final polymer latexes, keeping their particular identity without serious exchange kinetics involved. It is shown that the miniemulsion process can excellently be used for the formulation of polymer-coated magnetic nanoparticles which can further be used for biomedical applications. The use of high shear, appropriate surfactants, and the addition of a hydrophobe in order to suppress the influence of Ostwald ripening are key factors for the formation of the small and stable droplets in miniemulsion and will be discussed. Two different approaches based on miniemulsion processes for the encapsulation of magnetite into polymer particles will be presented in detail.

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Changes in transverse phonon sound velocity were measured during low temperature irradiation of amorphous Pd{sub 80}Si{sub 20} with 3.5 MeV krypton ions. The sound velocity decreases as a function of the ion fluence and shows a tendency to saturate at large fluences at a relative change of {minus}4.7%. The changes in sound velocity were used to determine the changes in shear elastic constant and in Debye temperature both of which were in reasonable agreement with the value reported in the literature.

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Safety-technical factors related to spontaneous ignition and dust explosions of biomasses were investigated. Parametres of dust explosions and effect of inertisation on the maximum pressure (pmax) and the maximum rate of pressure rise (Kstmax) were studied at elevated initial pressure (1-9 bar). The level of inertisation required to prevent dust explosions totally was determined at different initial pressures. The sensitivity of fuels to spontaneous ignition and the effect of pressure on the sensitivity to and temperature of spontaneous ignition were studied on a pressurised dynamic self-ignition equipment. The effect of inertisation on the self-ignition temperature and alternatives of preventing spontaneous ignition by effective inertisation in the pressure ranges of 1 and 25 bar were investigated. As an example of application, results obtained with the laboratory test equipment were extrapolated to bin sizes used in practice. As a factor contributing to spontaneous ignition, the ...

International Nuclear Information System (INIS)

A general theoretical approach for the study of the two-dimensional structure of high-n Toroidal Alfven Eigenmodes (TAE) in finite-#beta#, large aspect ratio (R_o/a much-gt 1) tokamak equilibria is presented. Here, n is the toroidal mode number, #beta# = plasma/magnetic pressure, and a(R_o) is the minor (major) radius of the torus. It is shown how the general pseudo-differential boundary value problem for the radial eigenmode structure can be systematically constructed from the local dispersion relation; which is obtained using the ballooning formalism. The TAE modes are characterized by a broad radial envelope, the width of which is independent on the mode number in the general case of monotonic equilibrium profiles. The results on the two-dimensional eigenmode structure are expected to be applicable to drift-type waves. The ballooning transform is generalized here to handle singular eigenfunctions typical of the continuous shear Alfven spectrum, and, thereby, ...

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Correlation between mechanical stress and hydrogen effects on radiation damage in polycide-gate MOS capacitors was investigated as a function of gate-oxide thickness. The compressive stress magnitude was altered by varying the silicide (TiSi/sub 2/ or WSi/sub 2/) thickness in the polycide-gate electrode, and hydrogen introduction into gate-SiO/sub 2/ film was carried out by diffusion from plasma-deposited silicon-nitride passivation film (SiN-Cap). In a MOS capacitor without passivation film (No-Cap sample), it was found that compressive stress on gate-SiO/sub 2/ reduces both positive charge build-up (..delta..Qot) and interface-trap generation (..delta..Dit). Radiation induced shift, ..delta..Qot exhibits a smaller stress effect as compared with ..delta..Dit. As gate-SiO/sub 2/ thickness decreases, the stress effect on ..delta..Qot increases, while this effect on ..delta..Dit ...

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A set of equations describing a stress-mediated evolution of the nonequilibrium dopant-defect system has been derived and analyzed. Together with coupled diffusion of dopant atoms and point defects, we consider the drift of all mobile species in different charge states, namely vacancies, self-interstitials, and pairs 'dopant atom-point defect', in the field of stress. It has been shown that stresses may affect the diffusion of dopant atoms mainly in two ways: (1) directly, due to the drift of the pairs in the field of stress; (2) indirectly, by the formation of nonuniform defect distribution due to the drift of point defects. On this basis, various features of doping processes, such as phenomena of 'uphill' impurity diffusion near the surface (within the framework of the first or second mechanisms) and the peculiarities of high concentration phosphorus diffusion (due ...

International Nuclear Information System (INIS)

Complete text of publication follows. The stability regime of the incommensurate phase of quartz is influenced by uniaxial stress. Hence, the phase transition can be induced under isothermal conditions by the application of external mechanical forces. Using real-time neutron scattering the time evolution of structural changes is investigated id detail during stress variations. The time dependent behaviour of the satellite reflection is compared with that one of the fundamental Bragg reflection which - via primary extinction - gives information about the perfection of the crystal. On increasing stress the perfection of the lattice is destroyed immediately while the modulated structure is built up with a delay of about 1 s. Decreasing the stress leads to a reverse behaviour. Moreover, there is evidence that under periodical load residual non-relaxed strain fields survive leading to a different temperature ...

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All organisms, from bacteria and yeast to humans, respond to physical and chemical stressors by increasing the synthesis of a small group of cellular stress proteins.'' The authors have developed a simple in vitro system for quickly screening environmentally relevant stressors to detect stress-induced proteins that are good candidates for biomarkers. Polyacrylamide gel electrophoresis was used to detect stressor-induced, concentration-dependent changes in cellular stress protein levels in two fish cell culture systems, whereas simultaneous in vitro neutral red uptake cytotoxicity assays measured the stressors effect on cellular physiology. There was a direct concentration-dependent relationship between sublethal cytotoxic effects and the increases in stress protein levels. Increases of 50 to 200% were detected in stress proteins from desert topminnow, Poeciliopsis ...

International Nuclear Information System (INIS)

The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V_G_S = V_D_S/2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to ...

British Library Electronic Table of Contents (United Kingdom)

Aims: In this study we investigated whether attenuation of endoplasmic reticulum stress (ER stress) could protect HepG2 cells from free fatty acid (FFA)-induced apoptosis. Main methods: Human liver cell line HepG2 cells were exposed to Sodium Palmitate (Pa) or Sodium Oleate (Ol). Apoptosis and ER stress of HepG2 cells were analyzed with flow cytometry, real-time RT-PCR and Western Blotting. An expression plasmid encoding for the ER chaperone immunoglobulin heavy chain-binding protein (Bip) was transfected into HepG2 cells to attenuate ER stress. Small interfering RNA siCHOP was used to knockdown the expression of C/EBP Homologous Protein (CHOP) in HepG2. Key findings: Pa led to cytotoxicity and apoptosis in HepG2 cells in a dose-dependent pattern and also induced ER stress indicated by inc...

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Metallic multilayers offer a fantastic playground to investigate elastic stresses in films of nanometer thickness. We will present and discuss a few examples from our recent work on Au-Ni and Ag-Cu systems where we combined plate bending measurements and electron or X-ray diffraction to investigate stress buildup and interfacial mixing. Comparing these two cases we discuss the results with respect to basic parameters like the misfits in lattice parameters and in elastic moduli, the mixing enthalpies and the surface energies.

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The authors report a two-temperature RF bias stress test on nominal 1.2 W 7.5 GHz GaAs/AlGaAs HBT unit cell amplifiers. MTTF`s of 2020 and 1340 hours were obtained at Tj = 218{degrees}C and 245{degrees}C, respectively, under nominal input bias. An activation energy of 0.42 eV is estimated, consistent with published results for similar devices under DC bias stress.

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The problem of thermal instability of compressible, electrically conducting couple-stress fluids in the presence of a uniform magnetic field is considered. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For stationary convection, the compressibility, couple-stress, and magnetic field postpone the onset of convection. Graphs have been plotted by giving numerical values of the parameters to depict the stability characteristics. The principle of exchange of stabilities is found to be satisfied. The magnetic field introduces oscillatory modes in the system that were non-existent in its absence. The case of overstability is also studied wherein a sufficient condition for the non-existence of overstability is obtained. (orig.)

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The design of High-Voltage, Direct-Current transmission cables insulated with oil-impregnated cellulose paper is constrained by the maximum temperature and the maximum steady-state and transient stresses (voltage gradients) that the cable insulation can reliably withstand over the desired operating lifetime. Because the electrical stresses in the insulation are related in a very complex fashion to temperature, applied voltage and cable geometry, iterative techniques are required to compute the values of these stresses. Digital computers are ideally suited for these iterative techniques. This paper presents the principal equations and logic needed to develop suitable computer programs.

UK PubMed Central (United Kingdom)

BackgroundOxidative stress has been proposed as a mechanism linking the poor placental perfusion characteristic of preeclampsia with the clinical manifestations of...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

The double diffusive convection in a horizontal couple stress fluid saturated anisotropic porous layer, which is heated and salted from below, is studied analytically. The modified Darcy equation that includes the time derivative term is used to model the momentum equation. The critical Rayleigh number, wavenumber for stationary and oscillatory modes, and frequency of oscillations are obtained analytically using linear theory. The effect of anisotropy parameter, solute Rayleigh number, Lewis number, couple stress parameter, and Vadasz number on the stationary, oscillatory, and finite amplitude convection is shown graphically. It is found that the thermal anisotropy parameter, couple stress parameter, and solute Rayleigh number have stabilizing effect on the stationary, oscillatory, and fin...

International Nuclear Information System (INIS)

... Masahiro Tsukada, Takashi Japan Atomic Energy Agency, Tokai, Ibaraki (Japan)

International Nuclear Information System (INIS)

... University, Fracture and Reliability Research Institute, Sendai, Miyagi (Japan)

UK PubMed Central (United Kingdom)

The in vivo photochemical activity of photosystem II was inferred from modulated chlorophyll fluorescence and photoacoustic measurements in intact leaves of several plant species (Lycopersicon...Full Text Available

UK PubMed Central (United Kingdom)

ContextCorticotropin-releasing hormone (CRH), through the hypothalamic pituitary adrenal (HPA) axis and other brain stress systems, is involved in the emotional dysregulation...Full Text Available

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Low residual stress silicon oxynitride thin films are investigated for use as a replacement for silicon dioxide (SiO{sub 2}) as sacrificial layer in surface micromachined microelectrical-mechanical systems (MEMS). It is observed that the level of residual stress in oxynitrides is a function of the nitrogen content in the film. MEMS film stacks are prepared using both SiO{sub 2} and oxynitride sacrificial layers. Wafer bow measurements indicate that wafers processed with oxynitride release layers are significantly flatter. Polycrystalline Si (poly-Si) cantilevers fabricated under the same conditions are observed to be flatter when processed with oxynitride rather than SiO{sub 2} sacrificial layers. These results are attributed to the lower post-processing residual stress of oxynitride compared to SiO{sub 2} and reduced thermal mismatch to poly-Si.

UK PubMed Central (United Kingdom)

Periventricular white matter injury (PWMI), is the leading cause of chronic neurologic injury among survivors of preterm birth. The hallmark of PWMI is hypomyelination and a lack of mature,...Full Text Available

UK PubMed Central (United Kingdom)

Obesity is characterized by the abnormal or excessive deposition of fat in the adipose tissue. Its consequences go far beyond adverse metabolic effects on health, causing an increase in oxidative stress,...Full Text Available

International Nuclear Information System (INIS)

... for mediating the effects of early adverse experiences since they are affected

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A new test methodology is described which allows access to loading rates that lie between split Hopkinson bar and shock-loading techniques. Gas gun experiments combined with velocity interferometry techniques have been used to experimentally determine the intermediate strain-rate loading behavior of Coors AD995 alumina and Cercom silicon-carbide rods. Graded-density materials have been used as impactors; thereby eliminating the tension states generated by the radial stress components during the loading phase. Results of these experiments demonstrate that the time-dependent stress pulse generated during impact allows an efficient transition from the initial uniaxial strain loading to a uniaxial stress state as the stress pulse propagates through the rod. This allows access to intermediate loading rates over 5 x 10{sup 3}/s to a few times 10{sup 4}/s.

UK PubMed Central (United Kingdom)

Tetragonal ferroelectric/ferroelectric \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts}...Full Text Available

UK PubMed Central (United Kingdom)

Chaperones (stress proteins) are essential proteins to help the formation and maintenance of the proper conformation of other proteins and to promote cell survival after a large variety of environmental...Full Text Available

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We conduct the static and dynamic loading fracture experiments on magnesium alloy (AZ31B) under the equitable and inequitable biaxial stress. We process specimens as cross type with cracks. There are different kinds of cracks defined by their crack angles. By using a hydraulic high-speed biaxial experiment machine, we put the equitable and inequitable stresses on the specimen. We analyze results using the caustic method. The experiments reveal a few important results. There is negative correlation between the fracture toughness value and the plate thickness in the magnesium alloy sheet specimen. The fracture toughness value decrease in the case the crack has the angle different from the loading direction. The fracture toughness value decreases significantly under the inequitable biaxial stress. (orig.)

British Library Electronic Table of Contents (United Kingdom)

In this research, the interactive effect of grain and specimen sizes on the flow stress of sheet metal in microforming is investigated via the tensile test of pure copper and numerical modeling. Models based on different assumptions are proposed to analyze the size effect phenomenon. It is found that the flow stress decreases linearly with the decrease of the ratio of specimen to grain sizes. The grain boundary thickness decreases and its volume fraction increases with the decrease of grain size. The variation of grain boundary thickness is not proportional to the variation of grain size. Furthermore, the fraction of grain boundary increases with the strain and the ratio of specimen to grain sizes. Based on the FE simulation, it is found that the simulated flow stress, which is modeled bas...

British Library Electronic Table of Contents (United Kingdom)

This paper is concerned with the study of the Electrorheological RayleighTaylor instability (ERTI) at the interface between a densely packed saturated poorly conducting couple stress porous layer accelerated by a lighter poorly conducting couple stress fluid in a thin shell in the presence of a transverse electric field and laser radiation. A simple theory based on fully developed flow approximations is used to derive the dispersion relation for the growth rate of ERTI. The cutoff and the maximum wave numbers and the corresponding maximum frequencies are obtained. It is shown that the effects of couple stress parameter and the electric field reduce the growth rate considerably compared to a non-conducting fluid in the absence of an electric field. These are favorable to control the surface...

International Nuclear Information System (INIS)

... University, Fracture and Reliability Research Institute, Sendai, Miyagi (Japan)

International Nuclear Information System (INIS)

The effect of uniaxial tensile stress on intergranular corrosion (IGC) of AA2024-T3 was studied using the foil penetration technique. Standard ASTM G49 fixed-displacement jigs were modified to allow the use of sheet samples, which were then attached to an electrochemical cell as in the foil penetration setup. The time for IGC to penetrate samples of varying thickness was monitored. This method provides a new approach to bridge the gap between IGC and intergranular stress corrosion cracking (IGSCC). Samples with various orientations relative to the rolling direction were studied in 1.0 M NaCl at controlled anodic potentials. Potentiodynamic polarization measurements indicated that the two breakdown potentials typically observed for AA2024-T3 were lower for stressed samples than for unstressed samples, and the current at a given potential was higher. The penetration rate depended on potential and was higher for ...

International Nuclear Information System (INIS)

... Industry, Material Science Research Laboratory, Yokosuka, Kanagawa (Japan)

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138 unselected head tomographies of children by computer are reported and analysed. The major aspect stressed by the authors is the excellent precision of this radiological technique.

British Library Electronic Table of Contents (United Kingdom)

The residing fracture system and the prevailing in situ stresses have a significant impact on fluid flow and heat transfer in crystalline rocks. The long term response of fracture systems to changes in effective stresses, in particular the long term geo-mechanical effects of thermal stresses on reservoir characteristics is of particular interest to the geothermal industry.In this paper, a geothermal reservoir model is presented, in which a thermo-poroelastic finite element module is coupled to a fracture geomechanical module. This describes fracture closure as a function of effective stress and the changes in parameters, such as effective permeability, porosity and discrete fracture apertures. The novelty of this approach lies in its dynamic treatment of the characteristic properties of in...

Science.gov (United States)

reaching their ultimate compressive strength. Thus, when applying a lamina stress analysis in conjunction with a failure model, one must ...

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As part of a coordinated program, AECL is developing a set of tools to aid with the prediction and management of steam generator performance. Although stress corrosion cracking (of Alloy 800) has not been detected in any operating steam generator, for life management it is necessary to develop mechanistic models to predict the conditions under which stress corrosion cracking is plausible. Therefore, constant extension rate tests were carried out for Alloy 800 under various steam generator crevice chemistry conditions at applied potentials. These tests were designed to evaluate the stress corrosion cracking susceptibility of Alloy 800 under CANDU( steam generator operating conditions. Based on the experimental results, the recommended electrochemical corrosion potential/pH zone for Alloy 800 determined by electrochemical polarization measurements was verified with the respect of stress corrosion cracking ...

UK PubMed Central (United Kingdom)

Hyperosmotic stress is known to significantly enhance net uptake of inorganic ions into plant cells. Direct evidence for cell turgor recovery via such a mechanism, however, is still lacking. In the...Full Text Available

UK PubMed Central (United Kingdom)

A variety of stress situations may affect the activity and survival of plant-beneficial pseudomonads added to soil to control root diseases. This study focused on the roles of the sigma factor AlgU...Full Text Available

International Nuclear Information System (INIS)

In the past decade, a new technique has been developed for measuring tensile stresses in solids. This ultrasonic technique has been used thus far primarily for measuring fastener tension. The precision of measurement is routinely to 2-3% and, with special care, to approx. 1%. The method is insensitive to the frictional losses which plague tensioning by torque wrench. Though the approach is relatively new, it promises a wide range of applicability.

UK PubMed Central (United Kingdom)

The initiation and progression of several forms of retinal degenerations involve excessive, repetitive, and/or sustained oxidative stress that, in turn, mediate photoreceptor cell damage and...Full Text Available

International Nuclear Information System (INIS)

Investigated are the characteristics of high-temperature plastic deformation the velocity sensitivity of flow stresses, deformation curves, flow stresses, deformation before rupture - as well as the structure of beryllium alloys containing nickel (0.5-4 %), yttrium (0.5-2 %) and aluminium (38 %). The alloys containing nickel (2%) and yttrium (0.5 %) are superplastic, however, deformation before fracture of the alloys is lower than that of the unalloyed beryllium. The singularities of high-temperature plastic flow of the alloys and the causes of deterioration of their plasticity are determined.

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Air Force Prototype Thermal Flash Protective Device (TFPD) Goggles were furnished to USAFSAM by the Life Support System Program Office, Aeronautical Systems Division, for determination and evaluation of their eye-type goggles caused stressed areas. The bonding used in the production model eliminated the stressed areas, resulting in increased closed-state optical density, particularly in the upper nasal area of the lens.

International Nuclear Information System (INIS)

Dynamic recrystallization (DRX) is the main softening mechanism of magnesium alloy AZ31B in hot deformation. Theoretically, in the flow rule the atomic diffusibility and the driving force of dislocation migration are dependent on the temperature, and the dislocation density and the cumulation of grain boundary energy are dependent on the strain rate. The peak stress will appear when the flow driving force and resistance force reach a balance, after which the stress descending will take place due to recrystallization fraction. Since the DRX is a thermally activated process, the recrystallized volume fraction can be regarded as the function of strain through Avrami equation. Based on this idea, the paper proposes a new constitutive model characterizing dynamic recrystallization for magnesium alloy AZ31B. The model is described by a peak stress and a strain softening rate, in which the peak stress depends ...

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By means of a global mode analysis of ideal MHD modes for Mercier-unstable equilibria in a planar axis L=2/M=10 heliotron/torsatron system with an inherently large Shafranov shift, the conjecture from local mode analysis for Mercier-unstable equilibria given in [N. Nakajima, Phys. Plasmas 3, 4556 (1996)] has been confirmed and the properties of pressure-driven modes, namely, ballooning modes and interchange modes, inherent to such three-dimensional systems have been clarified. The change of the local magnetic shear due to the Shafranov shift, which is related to toroidicity, reduces the field line bending stabilizing effects on ballooning modes. According to the degree of the reduction of the local magnetic shear by the Shafranov shift, the Mercier-unstable equilibria are categorized into toroidicity-dominant (strong reduction) and helicity-dominant (weak reduction) Mercier-unstable equilibria. Since the local magnetic curvature due to helicity ...

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For quantitative acquisition of the influence of surface decarburizing phenomena on the failure of construction parts under cyclic stress different surface decarburization stages were generated in the steels 42CrMo4 and 100Cr6. After construction part-specific thermal treatment the generated states of residual stress were then determined and life span-oriented fatigue tests were conducted. The studies showed that already a small decarburization in martensitic material conditions of the steels 42CrMo4 and 100Cr6 led to a reduction of the alternating bending strength. The decrease of alternate strength can be associated with the micro-notch effects caused by the internal oxides formed by surface oxidation and/or the residual tension stress developed during the hardening in sub-surface sample areas. Decarburization degrees of more than 50% cause a noticeable decrease of surface stability, an increase of residual tension ...

International Nuclear Information System (INIS)

During the operation of a tokamak, the first wall elements suffer very high heat fluxes. Heat is removed by internal cooling by means of water, helium or fluid metal. The resulting inhomogeneous temperature field cause internal stresses which, due to the pulsed operation are of cyclic nature. Additional mechanical stresses in the first wall may be caused by disruptions or vertical plasma movements. During theses events high currents are induced in the metallic part of the first wall which by their interaction with the magnetic field of the tokamak lead to mechanical forces. These electromechanical stresses may lie beyond the yield stress of the structural material. From the interaction of thermal and mechanical forces, a complex stress state is achieved which under certain circumstances may lead to premature failure and/or to progressive plastic deformations (ratcheting). In order ...

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