WorldWideScience

Sample records for local surface stress

  1. The influence of rail surface irregularities on contact forces and local stresses

    Science.gov (United States)

    Andersson, Robin; Torstensson, Peter T.; Kabo, Elena; Larsson, Fredrik

    2015-01-01

    The effect of initial rail surface irregularities on promoting further surface degradation is investigated. The study concerns rolling contact fatigue formation, in particular in the form of the so-called squats. The impact of surface irregularities in the form of dimples is quantified by peak magnitudes of dynamic contact stresses and contact forces. To this end simulations of two-dimensional (later extended to three-dimensional) vertical dynamic vehicle-track interaction are employed. The most influencing parameters are identified. It is shown that even very shallow dimples might have a large impact on local contact stresses. Peak magnitudes of contact forces and stresses due to the influence of rail dimples are shown to exceed those due to rail corrugation.

  2. Local stresses, dyke arrest and surface deformation in volcanic edificesand rift zones

    Directory of Open Access Journals (Sweden)

    L. S. Brenner

    2004-06-01

    Full Text Available Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes that are opened by magmatic overpressure. While (inferred dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear strength while the same strength is not exceeded at the (arrested dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses, layers with relatively high dyke-normal compressive stresses (stress barriers, and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward

  3. Effect of processing conditions on residual stress distributions by bead-on-plate welding after surface machining

    International Nuclear Information System (INIS)

    Ihara, Ryohei; Mochizuki, Masahito

    2014-01-01

    Residual stress is important factor for stress corrosion cracking (SCC) that has been observed near the welded zone in nuclear power plants. Especially, surface residual stress is significant for SCC initiation. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and residual stress distribution due to surface machining is varied by the subsequent butt welding. In previous paper, authors reported that residual stress distribution generated by bead on plate welding after surface machining has a local maximum residual stress near the weld metal. The local maximum residual stress shows approximately 900 MPa that exceeds the stress threshold for SCC initiation. Therefore, for the safety improvement of nuclear power plants, a study on the local maximum residual stress is important. In this study, the effect of surface machining and welding conditions on residual stress distribution generated by welding after surface machining was investigated. Surface machining using lathe machine and bead on plate welding with tungsten inert gas (TIG) arc under various conditions were conducted for plate specimens made of SUS316L. Then, residual stress distributions were measured by X-ray diffraction method (XRD). As a result, residual stress distributions have the local maximum residual stress near the weld metal in all specimens. The values of the local maximum residual stresses are almost the same. The location of the local maximum residual stress is varied by welding condition. It could be consider that the local maximum residual stress is generated by same generation mechanism as welding residual stress in surface machined layer that has high yield stress. (author)

  4. Surface effects on static bending of nanowires based on non-local elasticity theory

    Directory of Open Access Journals (Sweden)

    Quan Wu

    2015-10-01

    Full Text Available The surface elasticity and non-local elasticity effects on the elastic behavior of statically bent nanowires are investigated in the present investigation. Explicit solutions are presented to evaluate the surface stress and non-local elasticity effects with various boundary conditions. Compared with the classical Euler beam, a nanowire with surface stress and/or non-local elasticity can be either stiffer or less stiff, depending on the boundary conditions. The concept of surface non-local elasticity was proposed and its physical interpretation discussed to explain the combined effect of surface elasticity and non-local elasticity. The effect of the nanowire size on its elastic bending behavior was investigated. The results obtained herein are helpful to characterize mechanical properties of nanowires and aid nanowire-based devices design.

  5. Local microstructure and flow stress in deformed metals

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Hansen, Niels; Nielsen, Chris Valentin

    2017-01-01

    The microstructure and flow stress of metals are related through many well-known strength-structure relationships based on structural parameters, where grain size and dislocation density are examples. In heterogeneous structures, the local stress and strain are important as they will affect...... the bulk properties. A microstructural method is presented which allows the local stress in a deformed metal to be estimated based on microstructural parameters determined by an EBSD analysis. These parameters are the average spacing of deformation introduced boundaries and the fraction of high angle...... boundaries. The method is demonstrated for two heterogeneous structures: (i) a gradient (sub)surface structure in steel deformed by shot peening; (ii) a heterogeneous structure introduced by friction between a tool and a workpiece of aluminum. Flow stress data are calculated based on the microstructural...

  6. Welding-induced local maximum residual stress in heat affected zone of low-carbon austenitic stainless steel with machined surface layer and its influential factors

    International Nuclear Information System (INIS)

    Okano, Shigetaka; Ihara, Ryohei; Kanamaru, Daisuke; Mochizuki, Masahito

    2015-01-01

    In this study, the effects of work-hardening and pre-existing stress in the machined surface layer of low-carbon austenitic stainless steel on the welding-induced residual stress were experimentally investigated through the use of weld specimens with three different surface layers; as-cutout, mechanically-polished and electrolytically-polished. The high tensile and compressive stresses exist in the work-hardened surface layer of the as-cutout and mechanically-polished specimens, respectively. Meanwhile, no stress and work-hardened surface layer exist in the electrolytically-polished specimen. TIG bead-on-plate welding under the same welding heat input conditions was performed to introduce the residual stress into these specimens. Using these welded specimens, the distributions of welding-induced residual stress were measured by the X-ray diffraction method. Similarly, the distributions of hardness in welds were estimated by the Vickers hardness test. And then, these distributions were compared with one another. Based on the results, the residual stress in the weld metal (WM) is completely unaffected by the machined surface layer because the work-hardened surface layer disappears through the processes of melting and solidification during welding. The local maximum longitudinal tensile residual stress in the heat affected zone (HAZ) depends on the work-hardening but not on the existing stress, regardless of whether tensile or compressive, in the machined surface layer before welding. At the base metal far from WM and HAZ, the residual stress is formed by the addition of the welding-induced residual stress to the pre-existing stress in the machined surface layer before welding. The features of the welding-induced residual stress in low-carbon austenitic stainless steel with the machined surface layer and their influential factors were thus clarified. (author)

  7. Relationship between ultrasonic Rayleigh waves and surface residual stress

    International Nuclear Information System (INIS)

    Adler, L.; Cook, K.V.; Dewey, B.R.; King, R.T.

    1977-01-01

    Local variations of Rayleigh (surface) circumferential ultrasonic wave velocity near a pipe-girth weld in large-diameter thin-wall type 316H stainless steel pipe were measured. The weldment was similar to those anticipated for the Liquid Metal Fast Breeder Reactor (LMFBR) piping systems. The residual stress distribution was estimated independently from shell theory for an elastic, infinite, thin shell with circumferential line loading. An upper bound on the magnitude of the residual stresses was estimated assuming the deformation of the shell was entirely elastic. The pattern of surface wave velocity variations matches the theoretical residual stress pattern closely. It is suggested that the monitoring of surface wave velocity variations might be used for characterizing residual stress patterns near critical welds in piping, aiding in design calculations, and for in-service monitoring of the state of stress of weldments

  8. Induced surface stress at crystal surfaces

    International Nuclear Information System (INIS)

    Dahmen, K.

    2002-05-01

    Changes of the surfaces stress Δτ (s) can be studied by observing the bending of thin crystalline plates. With this cantilever method one can gain the induced change of surface stress Δτ (s) from the bending of plates with the help of elasticity theory. For elastic isotropic substrates the relevant relations are known. Here the relations are generalized to elastic anisotropic crystals with a C 2v - Symmetry. The equilibrium shapes of crystalline plates oriented along the (100)-, (110)-, or (111)-direction which are clamped along one edge are calculated with a numeric method under the load of a homogeneous but pure isotropic or anisotropic surface stress. The results can be displayed with the dimensionality, so that the effect of clamping can be described in a systematic way. With these tabulated values one can evaluate cantilever experiments exactly. These results are generalized to cantilever methods for determining magnetoelastic constants. It is shown which magnetoelastic constants are measured in domains of thin films with ordered structures. The eigenshape and the eigenfrequency of plates constraint through a clamping at one side are calculated. These results give a deeper understanding of the elastic anisotropy. The induced surface stress of oxygen on the (110)-surface of molybdenum is measured along the principle directions Δτ [001] and Δτ [ anti 110] . The anisotropy of the surface stress is found for the p(2 x 2)-reconstruction. Lithium induces a tensile surface stress on the Molybdenum (110)-surface up to a coverage of Θ = 0, 3 monolayer. For a higher coverage the induced stress drops and reaches a level of less than -1, 2 N/m at one monolayer. It is shown, that cobalt induces a linear increasing stress with respect to the coverage on the (100)-surface of copper with a value of 2, 4GPa. The copper (100)-surface is bombarded with accelerated ions in the range between 800-2200 eV. The resulting induced compressive stress (Δτ (s) < 0) of the order

  9. Effects of surface roughness on plastic strain localization in polycrystalline aggregates

    Directory of Open Access Journals (Sweden)

    Guilhem Yoann

    2014-06-01

    Full Text Available The surface state of mechanical components differs according to applied loadings. Industrial processes may produce specific features at the surface, such as roughness, local hardening, residual stresses or recrystallization. Under fatigue loading, all these parameters will affect the component lifetime, but in different manner. A better understanding of each surface state parameter, separately first and then all combined, will provide a better prediction of fatigue life. The study focuses on the effect of surface roughness. Crystal plasticity finite element computations have been carried out on three-dimensional polycrystalline aggregates with different roughness levels. Local mechanical fields have been analyzed both at the surface and inside the bulk to highlight the competition between crystallography and roughness to impose localization patterns. As soon as surface roughness is strong enough, classical localization bands driven by grains orientation are replaced by localizations patterns driven by the local roughness topology. Nevertheless, this effect tends to decrease gradually under the surface, and it becomes usually negligible after the first layer of grains. The discussion allows us to characterize the influence of the surface state on the local mechanical fields.

  10. Relevance of plastic limit loads to reference stress approach for surface cracked cylinder problems

    International Nuclear Information System (INIS)

    Kim, Yun-Jae; Shim, Do-Jun

    2005-01-01

    To investigate the relevance of the definition of the reference stress to estimate J and C* for surface crack problems, this paper compares finite element (FE) J and C* results for surface cracked pipes with those estimated according to the reference stress approach using various definitions of the reference stress. Pipes with part circumferential inner surface cracks and finite internal axial cracks are considered, subject to internal pressure and global bending. The crack depth and aspect ratio are systematically varied. The reference stress is defined in four different ways using (i) a local limit load (ii), a global limit load, (iii) a global limit load determined from the FE limit analysis, and (iv) the optimised reference load. It is found that the reference stress based on a local limit load gives overall excessively conservative estimates of J and C*. Use of a global limit load clearly reduces the conservatism, compared to that of a local limit load, although it can sometimes provide non-conservative estimates of J and C*. The use of the FE global limit load gives overall non-conservative estimates of J and C*. The reference stress based on the optimised reference load gives overall accurate estimates of J and C*, compared to other definitions of the reference stress. Based on the present findings, general guidance on the choice of the reference stress for surface crack problems is given

  11. Pattern Driven Stress Localization

    Science.gov (United States)

    Croll, Andrew; Crosby, Alfred

    2010-03-01

    The self-assembly of patterns from isotropic initial states is a major driver of modern soft-matter research. This avenue of study is directed by the desire to understand the complex physics of the varied structures found in Nature, and by technological interest in functional materials that may be derived through biomimicry. In this work we show how a simple striped phase can respond with significant complexity to an appropriately chosen perturbation. In particular, we show how a buckled elastic plate transitions into a state of stress localization using a simple, self-assembled variation in surface topography. The collection of topographic boundaries act in concert to change the state from isotropic sinusoidal wrinkles, to sharp folds or creases separated by relatively flat regions. By varying the size of the imposed topographic pattern or the wavelength of the wrinkles, we construct a state diagram of the system. The localized state has implications for both biological systems, and for the control of non-linear pattern formation.

  12. Proposal of reference stress for a surface flaw on a cylindrical component from a review-with-comparison of the local metal loss assessment rule between API 579-1 and the p-M diagram method

    International Nuclear Information System (INIS)

    Oyamada, Kenji; Konosu, Shinji; Ohno, Takashi

    2011-01-01

    The Remaining Strength Factor (RSF) approach in Part 5 of API 579-1/ASME FFS-1 is an assessment method for a cylindrical component with a local metal loss based on surface correction factors. Also, reference stress solutions that are applied in the Failure Assessment Diagram (FAD) method for a cylindrical component with a crack-like flaw are provided in Annex D using surface correction factors. In the recently-developed p-M diagram method, the reference stress solution for local metal loss evaluation in a cylindrical component is derived using bulging factors, which are similar but not identical to the surface correction factors used in API 579-1/ASME FFS-1. This paper describes the results of a comparative study among the RSF approach, reference stress solutions for the FAD method, and the p-M diagram method, in terms of plastic collapse evaluation of a cylindrical component. These results were compared with the FEA and experimental results to confirm how these estimated stresses could be validated. This study also involves recommended reference stress solutions for a cylindrical component with a crack-like flaw or a local metal loss, which should be adopted as fitness-for-service rules, and a discussion on the influence of the design margin of the construction code on allowable flaw depth. - Highlights: → We compared local metal loss assessment rule between API 579-1 and the p-M method. → Experiments and FEA verified the p-M estimate stress state around a flaw accurate. → API 579-1 for local metal loss may underestimate stress state for certain conditions. → Existing reference stresses for crack-like flaws may underestimate stress state too. → We propose the reference stress for a surface flaw subjected to pressure and moment.

  13. Finite Element Simulation of Shot Peening: Prediction of Residual Stresses and Surface Roughness

    Science.gov (United States)

    Gariépy, Alexandre; Perron, Claude; Bocher, Philippe; Lévesque, Martin

    Shot peening is a surface treatment that consists of bombarding a ductile surface with numerous small and hard particles. Each impact creates localized plastic strains that permanently stretch the surface. Since the underlying material constrains this stretching, compressive residual stresses are generated near the surface. This process is commonly used in the automotive and aerospace industries to improve fatigue life. Finite element analyses can be used to predict residual stress profiles and surface roughness created by shot peening. This study investigates further the parameters and capabilities of a random impact model by evaluating the representative volume element and the calculated stress distribution. Using an isotropic-kinematic hardening constitutive law to describe the behaviour of AA2024-T351 aluminium alloy, promising results were achieved in terms of residual stresses.

  14. Effect of surface treatments on stress corrosion cracking susceptibility of nickel base alloys

    International Nuclear Information System (INIS)

    Iwanami, Masaru; Kaneda, Junya; Tamako, Hiroaki; Hato, Hisamitsu; Takamoto, Shinichi

    2009-01-01

    Effect of surface treatment on SCC susceptibility of Ni base alloys was investigated. Cracks were observed in all grinding specimens in a creviced bent beam (CBB) test. On the other hand, no cracks occurred in shot peening (SP), water jet peening (WJP) specimens. It was indicated that these surface treatments effectively reduced the SCC susceptibility of nickel-base alloys. As a result of a residual stress test, the surface of specimens with grinding had high tensile residual stress. However, SP and WJP improved surface residual stress to compressive stress. The depth of the compressive effect of WJP was almost the same as that of SP. However, the surface hardness of WJP specimens differed from that of SP and it was found that WJP had less impact on surface hardening. This difference was consistent with their surface microstructures. The surface of SP specimens had clearly the deformation region, but the surface of WJP specimens was localized. (author)

  15. Experimental study of stress-induced localized transformation plastic zones in tetragonal zirconia polycrystalline ceramics

    International Nuclear Information System (INIS)

    Sun, Q.; Zhao, Z.; Chen, W.; Qing, X.; Xu, X.; Dai, F.

    1994-01-01

    Stress-induced martensitic transformation plastic zones in ceria-stabilized tetragonal zirconia polycrystalline ceramics (Ce-TZP), under loading conditions of uniaxial tension, compression, and three-point bending, are studied by experiments. The transformed monoclinic phase volume fraction distribution and the corresponding plastic strain distribution and the surface morphology (surface uplift) are measured by means of moire interferometry, Raman microprobe spectroscopy, and the surface measurement system. The experimental results from the above three kinds of specimens and methods consistently show that the stress-induced transformation at room temperature of the above specimen is not uniform within the transformation zone and that the plastic deformation is concentrated in some narrow band; i.e., macroscopic plastic flow localization proceeds during the initial stage of plastic deformation. Flow localization phenomena are all observed in uniaxial tension, compression, and three-point bending specimens. Some implications of the flow localization to the constitutive modeling and toughening of transforming thermoelastic polycrystalline ceramics are explored

  16. Effect of reference loads on fracture mechanics analysis of surface cracked pipe based on reference stress method

    International Nuclear Information System (INIS)

    Shim, Do Jun; Son, Beom Goo; Kim, Young Jin; Kim, Yun Jae

    2004-01-01

    To investigate relevance of the definition of the reference stress to estimate J and C * for surface crack problems, this paper compares FE J and C * results for surface cracked pipes with those estimated according to the reference stress approach using various definitions of the reference stress. Pipes with part circumferential inner surface crack and finite internal axial crack are considered, subject to internal pressure and global bending. The crack depth and aspect ratio are systematically varied. The reference stress is defined in four different ways using (I) the local limit load, (II) the global limit load, (III) the global limit load determined from the FE limit analysis, and (IV) the optimised reference load. It is found that the reference stress based on the local limit load gives overall excessively conservative estimates of J and C * . Use of the global limit load clearly reduces the conservatism, compared to that of the local limit load, although it can provide sometimes non-conservative estimates of J and C * . The use of the FE global limit load gives overall non-conservative estimates of J and C * . The reference stress based on the optimised reference load gives overall accurate estimates of J and C * , compared to other definitions of the reference stress. Based on the present finding, general guidance on the choice of the reference stress for surface crack problems is given

  17. Modeling of surface stress effects on bending behavior of nanowires: Incremental deformation theory

    International Nuclear Information System (INIS)

    Song, F.; Huang, G.L.

    2009-01-01

    The surface stress effects on bending behavior of nanowires have recently attracted a lot of attention. In this letter, the incremental deformation theory is first applied to study the surface stress effects upon the bending behavior of the nanowires. Different from other linear continuum approaches, the local geometrical nonlinearity of the Lagrangian strain is considered, therefore, the contribution of the surface stresses is naturally derived by applying the Hamilton's principle, and influence of the surface stresses along all surfaces of the nanowires is captured. It is first shown that the surface stresses along all surfaces have contribution not only on the effective Young's modulus of the nanowires but also on the loading term in the governing equation. The predictions of the effective Young's modulus and the resonance shift of the nanowires from the current method are compared with those from the experimental measurement and other existing approaches. The difference with other models is discussed. Finally, based on the current theory, the resonant shift predictions by using both the modified Euler-Bernoulli beam and the modified Timoshenko beam theories of the nanowires are investigated and compared. It is noticed that the higher vibration modes are less sensitive to the surface stresses than the lower vibration modes.

  18. Surface green function matching for a three-dimensional non-local continuum

    International Nuclear Information System (INIS)

    Idiodi, J.O.A.

    1985-07-01

    With a view toward helping to bridge the gap, from the continuum side, between discrete and continuum models of crystalline, elastic solids, explicit results are presented for non-local stress tensors that describe exactly some lattice dynamical models that have been widely used in the literature for cubic lattices. The Surface Green Function Matching (SGFM) method, which has been used successfully for a variety of surface problems, is then extended, within a continuum approach, to a non-local continuum that models a three-dimensional discrete lattice. The practical use of the method is demonstrated by performing a fairly complete analytical study of the vibrational surface modes of the SCC semi-infinite medium. Some results are presented for the [100] direction of the (001) surface of the SCC lattice. (author)

  19. Local stress calculation in simulations of multicomponent systems

    International Nuclear Information System (INIS)

    Branicio, Paulo S.; Srolovitz, David J.

    2009-01-01

    The virial and Hardy methods provide accurate local stresses for single component materials such as monatomic metals. In contrast to the elemental material case, both methods provide poor estimates of the local stress for multicomponent materials. Using binary materials such as CaO, SiC and AlN and homogeneous strain, we demonstrate that there are several sources for the slow convergence of the virial and Hardy local stresses to the bulk values. Different approaches such as enforced stoichiometry, atomic localization functions and the atomic voronoi volume are used to improve the convergence and increase the spatial resolution of the local stress. The virial method with enforced stoichiometry and atomic voronoi volumes is the most accurate, giving exact stress values by the first atomic shell. In the general case, not assuming stoichiometry, the virial method with localization functions converge to 93% of the bulk value by the third atomic shell. This work may be particularly useful for the real-time description of stresses in simulations of shock waves and deformation dynamics.

  20. Intrinsic Compressive Stress in Polycrystalline Films is Localized at Edges of the Grain Boundaries

    Science.gov (United States)

    Vasco, Enrique; Polop, Celia

    2017-12-01

    The intrinsic compression that arises in polycrystalline thin films under high atomic mobility conditions has been attributed to the insertion or trapping of adatoms inside grain boundaries. This compression is a consequence of the stress field resulting from imperfections in the solid and causes the thermomechanical fatigue that is estimated to be responsible for 90% of mechanical failures in current devices. We directly measure the local distribution of residual intrinsic stress in polycrystalline thin films on nanometer scales, using a pioneering method based on atomic force microscopy. Our results demonstrate that, at odds with expectations, compression is not generated inside grain boundaries but at the edges of gaps where the boundaries intercept the surface. We describe a model wherein this compressive stress is caused by Mullins-type surface diffusion towards the boundaries, generating a kinetic surface profile different from the mechanical equilibrium profile by the Laplace-Young equation. Where the curvatures of both profiles differ, an intrinsic stress is generated in the form of Laplace pressure. The Srolovitz-type surface diffusion that results from the stress counters the Mullins-type diffusion and stabilizes the kinetic surface profile, giving rise to a steady compression regime. The proposed mechanism of competition between surface diffusions would explain the flux and time dependency of compressive stress in polycrystalline thin films.

  1. The Relationship Between Surface Curvature and Abdominal Aortic Aneurysm Wall Stress.

    Science.gov (United States)

    de Galarreta, Sergio Ruiz; Cazón, Aitor; Antón, Raúl; Finol, Ender A

    2017-08-01

    The maximum diameter (MD) criterion is the most important factor when predicting risk of rupture of abdominal aortic aneurysms (AAAs). An elevated wall stress has also been linked to a high risk of aneurysm rupture, yet is an uncommon clinical practice to compute AAA wall stress. The purpose of this study is to assess whether other characteristics of the AAA geometry are statistically correlated with wall stress. Using in-house segmentation and meshing algorithms, 30 patient-specific AAA models were generated for finite element analysis (FEA). These models were subsequently used to estimate wall stress and maximum diameter and to evaluate the spatial distributions of wall thickness, cross-sectional diameter, mean curvature, and Gaussian curvature. Data analysis consisted of statistical correlations of the aforementioned geometry metrics with wall stress for the 30 AAA inner and outer wall surfaces. In addition, a linear regression analysis was performed with all the AAA wall surfaces to quantify the relationship of the geometric indices with wall stress. These analyses indicated that while all the geometry metrics have statistically significant correlations with wall stress, the local mean curvature (LMC) exhibits the highest average Pearson's correlation coefficient for both inner and outer wall surfaces. The linear regression analysis revealed coefficients of determination for the outer and inner wall surfaces of 0.712 and 0.516, respectively, with LMC having the largest effect on the linear regression equation with wall stress. This work underscores the importance of evaluating AAA mean wall curvature as a potential surrogate for wall stress.

  2. Localized surface plate modes via flexural Mie resonances

    KAUST Repository

    Farhat, M.

    2017-05-11

    Surface-plasmon polaritons are naturally generated upon excitation of metals with high-frequency electromagnetic waves. However, the concept of spoof plasmons has made it possible to generate plasmoniclike effects in microwave electrodynamics, magnetics, and even acoustics. Similarly, in this paper, the concept of localized surface plate modes (SPMs) is introduced. It is demonstrated that SPMs can be generated on a two-dimensional (clamped or stress-free) cylindrical surface with subwavelength corrugations, which resides on a thin elastic plate, under excitation by an incident flexural plane wave. Numerical characterization of this corrugated rigid structure shows that it is elastically equivalent to a cylindrical scatterer with dispersive but uniformly negative flexural rigidity. This, indeed, suggests that plasmoniclike elastic materials can be engineered with potential applications in various areas including earthquake sensing and elastic imaging and cloaking.

  3. Localized surface plate modes via flexural Mie resonances

    KAUST Repository

    Farhat, M.; Chen, P. -Y.; Guenneau, S.; Salama, Khaled N.; Bagci, Hakan

    2017-01-01

    Surface-plasmon polaritons are naturally generated upon excitation of metals with high-frequency electromagnetic waves. However, the concept of spoof plasmons has made it possible to generate plasmoniclike effects in microwave electrodynamics, magnetics, and even acoustics. Similarly, in this paper, the concept of localized surface plate modes (SPMs) is introduced. It is demonstrated that SPMs can be generated on a two-dimensional (clamped or stress-free) cylindrical surface with subwavelength corrugations, which resides on a thin elastic plate, under excitation by an incident flexural plane wave. Numerical characterization of this corrugated rigid structure shows that it is elastically equivalent to a cylindrical scatterer with dispersive but uniformly negative flexural rigidity. This, indeed, suggests that plasmoniclike elastic materials can be engineered with potential applications in various areas including earthquake sensing and elastic imaging and cloaking.

  4. Determination of the plastic deformation and residual stress tensor distribution using surface and bulk intrinsic magnetic properties

    International Nuclear Information System (INIS)

    Hristoforou, E.; Svec, P. Sr.

    2015-01-01

    We have developed an unique method to provide the stress calibration curve in steels: performing flaw-less welding in the under examination steel, we obtained to determine the level of the local plastic deformation and the residual stress tensors. These properties where measured using both the X-ray and the neutron diffraction techniques, concerning their surface and bulk stresses type II (intra-grain stresses) respectively, as well as the stress tensor type III by using the electron diffraction technique. Measuring the distribution of these residual stresses along the length of a welded sample or structure, resulted in determining the local stresses from the compressive to tensile yield point. Local measurement of the intrinsic surface and bulk magnetic property tensors allowed for the un-hysteretic correlation. The dependence of these local magnetic tensors with the above mentioned local stress tensors, resulting in a unique and almost un-hysteretic stress calibration curve of each grade of steel. This calibration integrated the steel's mechanical and thermal history, as well as the phase transformations and the presence of precipitations occurring during the welding process.Additionally to that, preliminary results in different grade of steels reveal the existence of a universal law concerning the dependence of magnetic and magnetostrictive properties of steels on their plastic deformation and residual stress state, as they have been accumulated due to their mechanical and thermal fatigue and history. This universality is based on the unique dependence of the intrinsic magnetic properties of steels normalized with a certain magnetoelastic factor, upon the plastic deformation or residual stress state, which, in terms, is normalized with their yield point of stress. (authors)

  5. Surface stress-based biosensors.

    Science.gov (United States)

    Sang, Shengbo; Zhao, Yuan; Zhang, Wendong; Li, Pengwei; Hu, Jie; Li, Gang

    2014-01-15

    Surface stress-based biosensors, as one kind of label-free biosensors, have attracted lots of attention in the process of information gathering and measurement for the biological, chemical and medical application with the development of technology and society. This kind of biosensors offers many advantages such as short response time (less than milliseconds) and a typical sensitivity at nanogram, picoliter, femtojoule and attomolar level. Furthermore, it simplifies sample preparation and testing procedures. In this work, progress made towards the use of surface stress-based biosensors for achieving better performance is critically reviewed, including our recent achievement, the optimally circular membrane-based biosensors and biosensor array. The further scientific and technological challenges in this field are also summarized. Critical remark and future steps towards the ultimate surface stress-based biosensors are addressed. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Numerical simulation of the double pits stress concentration in a curved casing inner surface

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2016-12-01

    Full Text Available Sour or sweet oil fields development is common in recent years. Casing and tubing are usually subjected to pitting corrosion because of exposure to the strong corrosion species, such as CO2, H2S, and saline water. When the corrosion pits formed in the casing inner surface, localized stress concentration will occur and the casing strength will be degraded. Thus, it is essential to evaluate the degree of stress concentration factor accurately. This article performed a numerical simulation on double pits stress concentration factor in a curved inner surface using the finite element software ABAQUS. The results show that the stress concentration factor of double pits mainly depends on the ratio of two pits distance to the pit radius (L/R. It should not be only assessed by the absolute distance between the two pits. When the two pits are close and tangent, the maximum stress concentration factor will appear on the inner tangential edges. Stress concentration increased by double pits in a curved casing inner surface is more serious than that in a flat surface. A correction factor of 1.9 was recommended in the curved inner surface double pits stress concentration factor predict model.

  7. Investigation of the effect of sealed surfaces on local climate in urban areas

    Science.gov (United States)

    Weihs, Philipp; Hasel, Stefan; Mursch-Radlgruber, Erich; Gützer, Christian; Krispel, Stefan; Peyerl, Martin; Trimmel, Heidi

    2015-04-01

    Local climate is driven by the interaction between energy balance and energy transported by advected air. Short-wave and long-wave radiation are major components in this interaction. Some few studies (e.g. Santamouris et al.) showed that adjusting the grade of reflection of surfaces is an efficient way to influence temperature. The present study investigates the influence of high albedo concrete surfaces on local climate. The first step of the study consisted of experimental investigations: routine measurements of the short and longwave radiation balance, of the ground and of the air temperature and humidity at different heights above 6 different types of sealed surfaces were performed. During this measurement campaign the above mentioned components were measured over a duration of 4 months above two conventional asphalt surfaces, one conventional concrete and three newly developed concrete surfaces with increased reflectances. Measured albedo values amounted to 0.12±0.02 for the asphalt surfaces and to maximum values of 0.56 for high albedo concrete. The maximum difference in surface temperature between the asphalt surfaces and the high albedo concrete surfaces amounted to 15°C. In addition the emission constants of the different sealed surfaces were also determined and were compared to values from literature.. In a second step the urban energy balance model Envi_Met was used to simulate the surface temperature of the six surfaces. The simulated surface temperatures were compared to the measured surface temperatures and statements as to uncertainties of the model simulations were made In a third step, Envi_Met was used to simulate the local climate of an urban district in Vienna. The surface and air temperature and the SW, LW fluxes were calculated for different types of sealed surfaces. By performing calculations of thermal stress indices (UTCI, PMV), statements as to the influence of the type of sealed surface on thermal stress on humans was made.

  8. The surface-forming energy release rate versus the local energy release rate

    OpenAIRE

    Xiao, Si; Wang, He-ling; Landis, Chad M; Hwang, Keh-Chih; Liu, Bin

    2016-01-01

    This paper identifies two ways to extract the energy (or power) flowing into a crack tip during propagation based on the power balance of areas enclosed by a stationary contour and a comoving contour. It is very interesting to find a contradiction that two corresponding energy release rates (ERRs), a surface-forming ERR and a local ERR, are different when stress singularity exists at a crack tip. Besides a rigorous mathematical interpretation, we deduce that the stress singularity leads to an...

  9. THE STRESS STATE OF THE RADIALLY INHOMOGENEOUS HEMISPHERICAL SHELL UNDER LOCALLY DISTRIBUTED VERTICAL LOAD

    Directory of Open Access Journals (Sweden)

    Andreev Vladimir Igorevich

    2018-01-01

    Full Text Available Subject: one of the promising trends in the development of structural mechanics is the development of methods for solving problems in the theory of elasticity for bodies with continuous inhomogeneity of any deformation characteristics: these methods make it possible to use the strength of the material most fully. In this paper, we consider the two-dimensional problem for the case when a vertical, locally distributed load acts on the hemisphere and the inhomogeneity is caused by the influence of the temperature field. Research objectives: derive governing system of equations in spherical coordinates for determination of the stress state of the radially inhomogeneous hemispherical shell under locally distributed vertical load. Materials and methods: as a mechanical model, we chose a thick-walled reinforced concrete shell (hemisphere with inner and outer radii a and b, respectively, b > a. The shell’s parameters are a = 3.3 m, b = 4.5 m, Poisson’s ratio ν = 0.16; the load parameters are f = 10MPa - vertical localized load distributed over the outer face, θ0 = 30°, temperature on the internal surface of the shell Ta = 500 °C, temperature on the external surface of the shell Tb = 0 °C. The resulting boundary-value problem (a system of differential equations with variable coefficients is solved using the Maple software package. Results: maximal compressive stresses σr with allowance for material inhomogeneity are reduced by 10 % compared with the case when the inhomogeneity is ignored. But it is not so important compared with a 3-fold decrease in the tensile stress σθ on the inner surface and a 2-fold reduction in the tensile stress σθ on the outer surface of the hemisphere as concretes generally have a tensile strength substantially smaller than the compressive strength. Conclusions: the method presented in this article makes it possible to reduce the deformation characteristics of the material, i.e. it leads to a reduction in stresses

  10. STRESSES IN CEMENT-CONCRETE PAVEMENT SURFACING CAUSED BY THERMAL SHOCK

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2016-01-01

    Full Text Available It is necessary to mention specially so-called thermal shock among various impacts on highway surface. Ice layer is formed on a concrete surface during the winter period of pavement surfacing operation. Sodium chloride which lowers temperature of water-ice transition temperature and causes ice thawing at negative temperature is usually used to remove ice from the pavement surface. Consequently, temperature in the concrete laying immediately under a thawing ice layer is coming down with a run that leads to significant stresses. Such phenomenon is known as a thermal shock with a meaning of local significant change in temperature. This process is under investigation, it has practical importance for an estimation of strength and longevity of a cement-concrete pavement surfacing and consequently it is considered as rather topical issue. The purpose of investigations is to develop a mathematical model and determination of shock blow permissible gradients for a cementconcrete road covering. Finite difference method has been used in order to determine stressed and deformed condition of the cement-concrete pavement surfacing of highways. A computer program has been compiled and it permits to carry out calculation of a road covering at various laws of temperature distribution in its depth. Regularities in distribution of deformation and stresses in the cement-concrete pavement surfacing of highways at thermal shock have been obtained in the paper. A permissible parameter of temperature distribution in pavement surfacing thickness has been determined in the paper. A strength criterion based on the process of micro-crack formation and development in concrete has been used for making calculations. It has been established that the thermal shock causes significant temperature gradients on the cement-concrete surfacing that lead to rather large normal stresses in the concrete surface layer. The possibility of micro-crack formation in a road covering is

  11. Local yield stress statistics in model amorphous solids

    Science.gov (United States)

    Barbot, Armand; Lerbinger, Matthias; Hernandez-Garcia, Anier; García-García, Reinaldo; Falk, Michael L.; Vandembroucq, Damien; Patinet, Sylvain

    2018-03-01

    We develop and extend a method presented by Patinet, Vandembroucq, and Falk [Phys. Rev. Lett. 117, 045501 (2016), 10.1103/PhysRevLett.117.045501] to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols. This technique allows us to sample the plastic rearrangements in a nonperturbative manner for different loading directions on a well-controlled length scale. Plastic activity upon shearing correlates strongly with the locations of low yield stresses in the quenched states. This correlation is higher in more structurally relaxed systems. The distribution of local yield stresses is also shown to strongly depend on the quench protocol: the more relaxed the glass, the higher the local plastic thresholds. Analysis of the magnitude of local plastic relaxations reveals that stress drops follow exponential distributions, justifying the hypothesis of an average characteristic amplitude often conjectured in mesoscopic or continuum models. The amplitude of the local plastic rearrangements increases on average with the yield stress, regardless of the system preparation. The local yield stress varies with the shear orientation tested and strongly correlates with the plastic rearrangement locations when the system is sheared correspondingly. It is thus argued that plastic rearrangements are the consequence of shear transformation zones encoded in the glass structure that possess weak slip planes along different orientations. Finally, we justify the length scale employed in this work and extract the yield threshold statistics as a function of the size of the probing zones. This method makes it possible to derive physically grounded models of plasticity for amorphous materials by directly revealing the relevant details of the shear transformation zones that mediate this process.

  12. Evaluation of local stress for stress corrosion crack initiation by three-dimensional polycrystal model

    International Nuclear Information System (INIS)

    Kamaya, Masayuki; Kitamura, Takayuki

    2006-01-01

    In order to understand the initiation behavior of microstructurally small cracks in a stress corrosion cracking condition, it is important to know the tensile normal stress acting on the grain boundary (normal G.B. stress). The local stress in a polycrystalline body is greatly influenced by deformation constraint which is caused by anisotropic and/or inhomogeneous property of each grain. In present study, the local normal G.B. stress on bi- and tri-crystal bodies and a three-dimensional polycrystalline body consisting of 100 grains were evaluated by the finite element method under a remote uniform tensile stress condition. The polycrystalline body was generated by using a Monte Carlo procedure and random orientations were assigned to each grain. It was revealed that the local normal G.B. stress on the polycrystalline body is inhomogeneous under uniform applied stress. The stress tends to be large near the triple points due to the deformation constraint caused by adjacent grains, even though the grain boundary inclination to the load axis has large influence. It was also shown that particular high stress was not observed at corners of the polycrystalline body. (author)

  13. High Compressive Stresses Near the Surface of the Sierra Nevada, California

    Science.gov (United States)

    Martel, S. J.; Logan, J. M.; Stock, G. M.

    2012-12-01

    Observations and stress measurements in granitic rocks of the Sierra Nevada, California reveal strong compressive stresses parallel to the surface of the range at shallow depths. New overcoring measurements show high compressive stresses at three locations along an east-west transect through Yosemite National Park. At the westernmost site (west end of Tenaya Lake), the mean compressive stress is 1.9. At the middle site (north shore of Tenaya Lake) the mean compressive stress is 6.8 MPa. At the easternmost site (south side of Lembert Dome) the mean compressive stress is 3.0 MPa. The trend of the most compressive stress at these sites is within ~30° of the strike of the local topographic surface. Previously published hydraulic fracturing measurements by others elsewhere in the Sierra Nevada indicate surface-parallel compressive stresses of several MPa within several tens of meters of the surface, with the stress magnitudes generally diminishing to the west. Both the new and the previously published compressive stress magnitudes are consistent with the presence of sheeting joints (i.e., "exfoliation joints") in the Sierra Nevada, which require lateral compressive stresses of several MPa to form. These fractures are widespread: they are distributed in granitic rocks from the north end of the range to its southern tip and across the width of the range. Uplift along the normal faults of the eastern escarpment, recently measured by others at ~1-2 mm/yr, probably contributes to these stresses substantially. Geodetic surveys reveal that normal faulting flexes a range concave upwards in response to fault slip, and this flexure is predicted by elastic dislocation models. The topographic relief of the eastern escarpment of the Sierra Nevada is 2-4 km, and since alluvial fill generally buries the bedrock east of the faults, the offset of granitic rocks is at least that much. Compressive stresses of several MPa are predicted by elastic dislocation models of the range front

  14. Inspection of freeform surfaces considering uncertainties in measurement, localization and surface reconstruction

    International Nuclear Information System (INIS)

    Mehrad, Vahid; Xue, Deyi; Gu, Peihua

    2013-01-01

    Inspection of a manufactured freeform surface can be conducted by building its surface model and comparing this manufactured surface model with the ideal design surface model and its tolerance requirement. The manufactured freeform surface model is usually achieved by obtaining measurement points on the manufactured surface, transforming these measurement points from the measurement coordinate system to the design coordinate system through localization, and reconstructing the surface model using the localized measurement points. In this research, a method was developed to estimate the locations and their variances of any selected points on the reconstructed freeform surface considering different sources of uncertainties in measurement, localization and surface reconstruction processes. In this method, first locations and variances of the localized measurement points are calculated considering uncertainties of the measurement points and uncertainties introduced in the localization processes. Then locations and variances of points on the reconstructed freeform surface are obtained considering uncertainties of the localized measurement points and uncertainties introduced in the freeform surface reconstruction process. Two case studies were developed to demonstrate how these three different uncertainty sources influence the quality of the reconstructed freeform curve and freeform surface in inspection. (paper)

  15. Evolving local climate adaptation strategies: incorporating influences of socio–economic stress

    OpenAIRE

    Hjerpe, Mattias; Glaas, Erik

    2012-01-01

    Socio-economic and climatic stresses affect local communities’ vulnerability toflooding. Better incorporation of socio-economic stress in local vulnerability assessments isimportant when planning for climate adaptation. This is rarely done due to insufficientunderstanding of their interaction, in both theory and practice. The omission leads to criticalweaknesses in local adaptation strategies. This study analyses how socio-economic stressinteract with climatic stress and shape local vulnerabi...

  16. Reynolds stress of localized toroidal modes

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Mahajan, S.M.

    1995-02-01

    An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant

  17. Reynolds stress of localized toroidal modes

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Mahajan, S.M.

    1995-01-01

    An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant. (author). 15 refs

  18. Prevention of brittle fracture of steel structures by controlling the local stress and strain fields

    Directory of Open Access Journals (Sweden)

    Moyseychik Evgeniy Alekseevich

    Full Text Available In the article the author offers a classification of the methods to increase the cold resistance of steel structural shapes with a focus on the regulation of local fields of internal stresses and strains to prevent brittle fracture of steel structures. The need of a computer thermography is highlighted not only for visualization of temperature fields on the surface, but also to control the fields of residual stresses and strains in a controlled element.

  19. Localizing softness and stress along loops in 3D topological metamaterials

    Science.gov (United States)

    Baardink, Guido; Souslov, Anton; Paulose, Jayson; Vitelli, Vincenzo

    2018-01-01

    Topological states can be used to control the mechanical properties of a material along an edge or around a localized defect. The rigidity of elastic networks is characterized by a topological invariant called the polarization; materials with a well-defined uniform polarization display a dramatic range of edge softness depending on the orientation of the polarization relative to the terminating surface. However, in all 3D mechanical metamaterials proposed to date, the topological modes are mixed with bulk soft modes, which organize themselves in Weyl loops. Here, we report the design of a 3D topological metamaterial without Weyl lines and with a uniform polarization that leads to an asymmetry between the number of soft modes on opposing surfaces. We then use this construction to localize topological soft modes in interior regions of the material by including defect lines—dislocation loops—that are unique to three dimensions. We derive a general formula that relates the difference in the number of soft modes and states of self-stress localized along the dislocation loop to the handedness of the vector triad formed by the lattice polarization, Burgers vector, and dislocation-line direction. Our findings suggest a strategy for preprogramming failure and softness localized along lines in 3D, while avoiding extended soft Weyl modes.

  20. On the Stress Transfer of Nanoscale Interlayer with Surface Effects

    Directory of Open Access Journals (Sweden)

    Quan Yuan

    2018-01-01

    Full Text Available An improved shear-lag model is proposed to investigate the mechanism through which the surface effect influences the stress transfer of multilayered structures. The surface effect of the interlayer is characterized in terms of interfacial stress and surface elasticity by using Gurtin–Murdoch elasticity theory. Our calculation result shows that the surface effect influences the efficiency of stress transfer. The surface effect is enhanced with decreasing interlayer thickness and elastic modulus. Nonuniform and large residual surface stress distribution amplifies the influence of the surface effect on stress concentration.

  1. Study on residual stress across the pipes' thickness using outer surface rapid heating. Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

    International Nuclear Information System (INIS)

    Ohta, Takahiro; Terasaki, Toshio

    2009-01-01

    The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression plastic strain generates near the outer surface and the tensile plastic strain generates near the inner surface of pipes. The compression stress occurs near the inner surface of pipes by the plastic deformation. In this paper, the theoretical equation which calculates residual stress distribution from the inherent strain distribution in the thickness of pipes is derived. And, the relation between the distribution of temperature and the residual stress in the thickness is examined for various pipes size. (1) By rapidly heating from the outer surface, the residual stress near the inner surface of the pipe is improved to the compression stress. (2) Pipes size hardly affects the distribution of the residual stress in the stainless steel pipes for piping (JISG3459). (3) The temperature rising area from the outside is smaller, the area of the compression residual stress near the inner surface becomes wider. (author)

  2. Surface energy and surface stress on vicinals by revisiting the Shuttleworth relation

    Science.gov (United States)

    Hecquet, Pascal

    2018-04-01

    In 1998 [Surf. Sci. 412/413, 639 (1998)], we showed that the step stress on vicinals varies as 1/L, L being the distance between steps, while the inter-step interaction energy primarily follows the law as 1/L2 from the well-known Marchenko-Parshin model. In this paper, we give a better understanding of the interaction term of the step stress. The step stress is calculated with respect to the nominal surface stress. Consequently, we calculate the diagonal surface stresses in both the vicinal system (x, y, z) where z is normal to the vicinal and the projected system (x, b, c) where b is normal to the nominal terrace. Moreover, we calculate the surface stresses by using two methods: the first called the 'Zero' method, from the surface pressure forces and the second called the 'One' method, by homogeneously deforming the vicinal in the parallel direction, x or y, and by calculating the surface energy excess proportional to the deformation. By using the 'One' method on the vicinal Cu(0 1 M), we find that the step deformations, due to the applied deformation, vary as 1/L by the same factor for the tensor directions bb and cb, and by twice the same factor for the parallel direction yy. Due to the vanishing of the surface stress normal to the vicinal, the variation of the step stress in the direction yy is better described by using only the step deformation in the same direction. We revisit the Shuttleworth formula, for while the variation of the step stress in the direction xx is the same between the two methods, the variation in the direction yy is higher by 76% for the 'Zero' method with respect to the 'One' method. In addition to the step energy, we confirm that the variation of the step stress must be taken into account for the understanding of the equilibrium of vicinals when they are not deformed.

  3. Localization of SERBP1 in stress granules and nucleoli.

    Science.gov (United States)

    Lee, Yu-Jen; Wei, Hung-Ming; Chen, Ling-Yun; Li, Chuan

    2014-01-01

    SERPINE1 mRNA-binding protein 1 (SERBP1) is an arginine-methylated RNA-binding protein whose modification affects protein interaction and intracellular localization. In the present study, we show that, under normal growth conditions without stress, SERBP1 interacts with arginine-methylated and stress granule-associated proteins such as heterogeneous nuclear ribonucleoprotein A1, fragile X mental retardation protein and fragile X mental retardation syndrome-related protein 1 in an RNA-dependent manner. We also show that, after arsenite treatment, a proportion of full-length SERBP1 protein co-localizes with the typical stress granule marker T-cell intracellular antigen-1 in the cytoplasmic stress granules. Truncated SERBP1 with an N-terminal, central RG or C-terminal deletion, or single-domain segments comprising the N-terminal, central or C-terminal region, were recruited to stress granules upon arsenite treatment but with reduced efficiency. In addition, upon arsenite treatment, the localization of SERBP1 changed from a diffuse cytoplasmic localization to nuclear-dominant (concentrated in the nucleolus) A similar distribution was observed when cells were treated with the methylation inhibitor adenosine periodate, and was also detected for N- or C-terminal domain deletions and all three single-domain fragments even without stress induction. We further demonstrate that adenosine periodate treatment delays the association/dissociation of SERBP1 with stress granules. Hypomethylation retains SERBP1 in the nucleus/nucleolus regardless of arsenite treatment. Our study indicates that arginine methylation is correlated with recruitment of SERBP to stress granules and nucleoli and its retention therein. To our knowledge, this is the first report of an RNA-binding protein that is shifted simultaneously to cytoplasmic stress granules and nucleoli, two ribonucleoprotein-enriched subcellular compartments, upon stress. © 2013 FEBS.

  4. A local leaky-box model for the local stellar surface density-gas surface density-gas phase metallicity relation

    Science.gov (United States)

    Zhu, Guangtun Ben; Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Yan, Renbin; Brinkmann, Jonathan

    2017-07-01

    We revisit the relation between the stellar surface density, the gas surface density and the gas-phase metallicity of typical disc galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g. by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star-formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disc galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

  5. A wafer mapping technique for residual stress in surface micromachined films

    International Nuclear Information System (INIS)

    Schiavone, G; Murray, J; Smith, S; Walton, A J; Desmulliez, M P Y; Mount, A R

    2016-01-01

    The design of MEMS devices employing movable structures is crucially dependant on the mechanical behaviour of the deposited materials. It is therefore important to be able to fully characterize the micromachined films and predict with confidence the mechanical properties of patterned structures. This paper presents a characterization technique that enables the residual stress in MEMS films to be mapped at the wafer level by using microstructures released by surface micromachining. These dedicated MEMS test structures and the associated measurement techniques are used to extract localized information on the strain and Young’s modulus of the film under investigation. The residual stress is then determined by numerically coupling this data with a finite element analysis of the structure. This paper illustrates the measurement routine and demonstrates it with a case study using electrochemically deposited alloys of nickel and iron, particularly prone to develop high levels of residual stress. The results show that the technique enables wafer mapping of film non-uniformities and identifies wafer-to-wafer differences. A comparison between the results obtained from the mapping technique and conventional wafer bow measurements highlights the benefits of using a procedure tailored to films that are non-uniform, patterned and surface-micromachined, as opposed to simple standard stress extraction methods. The presented technique reveals detailed information that is generally unexplored when using conventional stress extraction methods such as wafer bow measurements. (paper)

  6. Single lump breast surface stress assessment study

    Science.gov (United States)

    Vairavan, R.; Ong, N. R.; Sauli, Z.; Kirtsaeng, S.; Sakuntasathien, S.; Paitong, P.; Alcain, J. B.; Lai, S. L.; Retnasamy, V.

    2017-09-01

    Breast cancer is one of the commonest cancers diagnosed among women around the world. Simulation approach has been utilized to study, characterize and improvise detection methods for breast cancer. However, minimal simulation work has been done to evaluate the surface stress of the breast with lumps. Thus, in this work, simulation analysis was utilized to evaluate and assess the breast surface stress due to the presence of a lump within the internal structure of the breast. The simulation was conducted using the Elmer software. Simulation results have confirmed that the presence of a lump within the breast causes stress on the skin surface of the breast.

  7. Influence of plastic slip localization on grain boundary stress fields and microcrack nucleation

    International Nuclear Information System (INIS)

    Sauzay, Maxime; Vor, Kokleang

    2013-01-01

    Slip localization is widely observed in metallic polycrystals after tensile deformation, cyclic deformation (persistent slip bands) or pre-irradiation followed by tensile deformation (channels). Such strong deformation localized in thin slip bands induces local stress concentrations in the quasi-elastic matrix around, at the intersections between slip bands and grain boundaries where microcracks are often observed. Since the work of Stroh, such stress fields have been modeled using the dislocation pile-up theory which leads to stress singularities similar to the LEFM ones. The Griffith criterion has then been widely applied, leading usually to strong underestimations of the macroscopic stress for microcrack nucleation. In fact, slip band thickness is finite: 50-1000 nm depending on material, temperature and loading conditions. Then, many slip planes are plastically activated through the thickness. Stress fields have probably been overestimated using the pile-up theory which assumes that all dislocations are located on the same atomic plane. To evaluate more realistic stress fields, crystalline finite element (FE) computations are carried out using microstructure inputs (slip band aspect ratio and spacing). Slip bands (low critical resolved shear stress) are embedded in an elastic matrix. The following results are obtained concerning grain boundary normal stress fields: - strong influence of slip band thickness close to the slip band corner, which is not accounted for by the pile-up theory. But far away, the thickness has a negligible effect and the predicted stress fields are close to the one predicted by the pile-up theory, - analytical formulae are deduced from the numerous FE computation results which allows the prediction of surface/bulk slips as well as grain boundary stress fields. Slip band plasticity parameters, slip band length and thickness, Schmid factor and remote stress are taken into account. The dependence with respect to the various parameters can

  8. Minimizing stress in large-area surface micromachined perforated membranes with slits

    International Nuclear Information System (INIS)

    Ghaderi, M; Ayerden, N P; De Graaf, G; Wolffenbuttel, R F

    2015-01-01

    This paper presents the effectiveness of both design and fabrication techniques for avoiding the rupturing or excessive bending of perforated membranes after release in surface micromachining. Special lateral designs of arrays of slits in the membrane were investigated for a maximum yield at a given level of residual stress. Process parameters were investigated and optimized for minimum residual stress in multilayer thin-film membranes. A 2 µm thick sacrificial TEOS layer and a structural membrane that is composed of silicon nitride and polysilicon layers in the stack is the basis of this study. The effect of sharp corners on the local stress in membranes was investigated, and structures are proposed that reduce these effects, maximizing the yield at a given level of residual stress. The effects of perforation and slits were studied both theoretically and using finite element analysis. While the overall effect of perforation is negligible in typical MEMS structures, an optimum design for the slits reduces the von Mises stress considerably as compared to sharp corners. The fabrication process was also investigated and optimized for the minimum residual stress of both the layers within the stack and the complete layer stack. The main emphasis of this work is on placing a stress-compensating layer on the wafer backside and simultaneously removing it during the surface micromachining, as this has been found to be the most effective method to reduce the overall stress in a stack of layers after sacrificial etching. Implementation of a stress compensating layer reduced the total residual stress from 200 MPa compressive into almost 60 MPa, tensile. Even though a particular structure was studied here, the employed methods are expected to be applicable to similar MEMS design problems. (paper)

  9. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  10. Topology Optimization of Continuum Structures with Local Stress Constraints

    DEFF Research Database (Denmark)

    Duysinx, Pierre; Bendsøe, Martin P

    1998-01-01

    We introduce an extension of current technologies for topology optimization of continuum structures which allows for treating local stress criteria. We first consider relevant stress criteria for porous composite materials, initially by studying the stress states of the so-called rank 2 layered m...

  11. Oxidative stress parameters in localized scleroderma patients.

    Science.gov (United States)

    Kilinc, F; Sener, S; Akbaş, A; Metin, A; Kirbaş, S; Neselioglu, S; Erel, O

    2016-11-01

    Localized scleroderma (LS) (morphea) is a chronic, inflammatory skin disease with unknown cause that progresses with sclerosis in the skin and/or subcutaneous tissues. Its pathogenesis is not completely understood. Oxidative stress is suggested to have a role in the pathogenesis of localized scleroderma. We have aimed to determine the relationship of morphea lesions with oxidative stress. The total oxidant capacity (TOC), total antioxidant capacity (TAC), paroxonase (PON) and arylesterase (ARES) activity parameters of PON 1 enzyme levels in the serum were investigated in 13 LS patients (generalized and plaque type) and 13 healthy controls. TOC values of the patient group were found higher than the TOC values of the control group (p < 0.01). ARES values of the patient group was found to be higher than the control group (p < 0.0001). OSI was significantly higher in the patient group when compared to the control (p < 0.005). Oxidative stress seems to be effective in the pathogenesis. ARES levels have increased in morphea patients regarding to the oxidative stress and its reduction. Further controlled studies are required in wider series.

  12. Surface Wave Velocity-Stress Relationship in Uniaxially Loaded Concrete

    DEFF Research Database (Denmark)

    Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

    2012-01-01

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

  13. Evaluation of Tire/Surfacing/Base Contact Stresses and Texture Depth

    Directory of Open Access Journals (Sweden)

    W.J.vdM. Steyn

    2015-03-01

    Full Text Available Tire rolling resistance has a major impact on vehicle fuel consumption. Rolling resistance is the loss of energy due to the interaction between the tire and the pavement surface. This interaction is a complicated combination of stresses and strains which depend on both tire and pavement related factors. These include vehicle speed, vehicle weight, tire material and type, road camber, tire inflation pressure, pavement surfacing texture etc. In this paper the relationship between pavement surface texture depth and tire/surfacing contact stress and area is investigated. Texture depth and tire/surfacing contact stress were measured for a range of tire inflation pressures on five different pavement surfaces. In the analysis the relationship between texture and the generated contact stresses as well as the contact stress between the surfacing and base layer are presented and discussed, and the anticipated effect of these relationships on the rolling resistance of vehicles on the surfacings, and subsequent vehicle fuel economy discussed.

  14. Surface stress mediated image force and torque on an edge dislocation

    Science.gov (United States)

    Raghavendra, R. M.; Divya, Iyer, Ganesh; Kumar, Arun; Subramaniam, Anandh

    2018-07-01

    The proximity of interfaces gives prominence to image forces experienced by dislocations. The presence of surface stress alters the traction-free boundary conditions existing on free-surfaces and hence is expected to alter the magnitude of the image force. In the current work, using a combined simulation of surface stress and an edge dislocation in a semi-infinite body, we evaluate the configurational effects on the system. We demonstrate that if the extra half-plane of the edge dislocation is parallel to the surface, the image force (glide) is not altered due to surface stress; however, the dislocation experiences a torque. The surface stress breaks the 'climb image force' symmetry, thus leading to non-equivalence between positive and negative climb. We discover an equilibrium position for the edge dislocation in the positive 'climb geometry', arising due to a competition between the interaction of the dislocation stress fields with the surface stress and the image dislocation. Torque in the climb configuration is not affected by surface stress (remains zero). Surface stress is computed using a recently developed two-scale model based on Shuttleworth's idea and image forces using a finite element model developed earlier. The effect of surface stress on the image force and torque experienced by the dislocation monopole is analysed using illustrative 3D models.

  15. Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'

    International Nuclear Information System (INIS)

    Gutman, E M

    2010-01-01

    In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity. (comment)

  16. Stress Transmission in Granular Packings: Localization and Cooperative Response

    Science.gov (United States)

    Ramola, Kabir

    We develop a framework for stress transmission in two dimensional granular media that respects vector force balance at the microscopic level. For a packing of grains interacting via pairwise contact forces, we introduce local gauge degrees of freedom that determine the response of the system to external perturbations. This allows us to construct unique force-balanced solutions that determine the change in contact forces as a response to external stress. By mapping this response to diffusion in the underlying contact network, we show that this naturally leads to spatial localization of forces. We present numerical evidence for stress localization using exact diagonalization studies of network Laplacians associated with soft disk packings. We use this formalism to characterize the deviation from elastic behaviour as the amount of disorder in the underlying network is varied. We discuss generalizations to systems with large friction between grains and other networks that display topological disorder. This work has been supported by NSF-DMR 1409093 and the W. M. Keck Foundation.

  17. A Family of Invariant Stress Surfaces

    DEFF Research Database (Denmark)

    Krenk, S.

    A family of invariant stress surfaces with a cubic dependence on the deviatoric stress components is expressed as a linear combination of the second and third deviatori stress invariants. A simple geometric derivation demonstrates the convexity of the contours in the deviatoric plane. An explicit...... representation of the deviatoric contours in terms of a size and a shape parameter is given. The shape parameter effects a continuous transition from a triangle to a circle in the deviatoric plane. An explicit format in terms of the triaxial compresson and tension generators is derived, and the plane stress...

  18. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadimehr, M., E-mail: mmohammadimehr@kashanu.ac.ir [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Mohammadi-Dehabadi, A.A. [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Department of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Maraghi, Z. Khoddami [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of)

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  19. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    International Nuclear Information System (INIS)

    Mohammadimehr, M.; Mohammadi-Dehabadi, A.A.; Maraghi, Z. Khoddami

    2017-01-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  20. Development of Generalized Correlation Equation for the Local Wall Shear Stress

    International Nuclear Information System (INIS)

    Jeon, Yu Mi; Park, Ju Hwan

    2010-06-01

    The pressure drop characteristics for a fuel channel are essential for the design and reliable operation of a nuclear reactor. Over several decades, analytical methods have been developed to predict the friction factor in the fuel bundle flows. In order to enhance the accuracy of prediction for the pressure drop in a rod bundle, the influences of a channel wall and the local shear stress distribution should be considered. Therefore, the correlation equation for a local wall shear stress distribution should be developed in order to secure an analytical solution for the friction factor of a rod bundle. For a side subchannel, which has the influence of the channel wall, the local wall shear stress distribution is dependent on the ratio of wall to diameter (W/D) as well as the ratio of pitch to diameter (P/D). In the case that W/D has the same value with P/D, the local shear stress distribution can be simply correlated with the function of angular position for each value of P/D. While in the case where W/D has a different value than P/D, the correlation equation should be developed for each case of P/D and W/D. Therefore, in the present study, the generalized correlation equation of the local wall shear stress distribution was developed for a side subchannel in the case where W/D has a different value than P/D. Consequently, the generalized correlation equation of a local wall shear stress distribution can be represented by the equivalent pitch to diameter ratio, P'/D for the case that P/D and W/D had a different value

  1. Prediction of residual stress distributions due to surface machining and welding and crack growth simulation under residual stress distribution

    International Nuclear Information System (INIS)

    Ihara, Ryohei; Katsuyama, JInya; Onizawa, Kunio; Hashimoto, Tadafumi; Mikami, Yoshiki; Mochizuki, Masahito

    2011-01-01

    Research highlights: → Residual stress distributions due to welding and machining are evaluated by XRD and FEM. → Residual stress due to machining shows higher tensile stress than welding near the surface. → Crack growth analysis is performed using calculated residual stress. → Crack growth result is affected machining rather than welding. → Machining is an important factor for crack growth. - Abstract: In nuclear power plants, stress corrosion cracking (SCC) has been observed near the weld zone of the core shroud and primary loop recirculation (PLR) pipes made of low-carbon austenitic stainless steel Type 316L. The joining process of pipes usually includes surface machining and welding. Both processes induce residual stresses, and residual stresses are thus important factors in the occurrence and propagation of SCC. In this study, the finite element method (FEM) was used to estimate residual stress distributions generated by butt welding and surface machining. The thermoelastic-plastic analysis was performed for the welding simulation, and the thermo-mechanical coupled analysis based on the Johnson-Cook material model was performed for the surface machining simulation. In addition, a crack growth analysis based on the stress intensity factor (SIF) calculation was performed using the calculated residual stress distributions that are generated by welding and surface machining. The surface machining analysis showed that tensile residual stress due to surface machining only exists approximately 0.2 mm from the machined surface, and the surface residual stress increases with cutting speed. The crack growth analysis showed that the crack depth is affected by both surface machining and welding, and the crack length is more affected by surface machining than by welding.

  2. X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

    International Nuclear Information System (INIS)

    Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

    2017-01-01

    The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the

  3. Interaction between diffusion and chemical stresses

    International Nuclear Information System (INIS)

    Yang Fuqian

    2005-01-01

    The present work studies the interaction between chemical stresses and diffusion. A new relation between hydrostatic stress and concentration of solute atoms is established. For a solid free of action of body force, the Laplacian of the hydrostatic stress is proportional to the Laplacian of the concentration of solute atoms, that is, deviation of the hydrostatic stress from its local average is proportional to deviation of the local concentration of solute atoms. A general relationship among surface concentration of solute atoms, normal stress and surface deformation of a solid is then derived, in which the normal stress is dependent on the mean curvature of the undeformed surface and tangential components of the surface displacement. A closed-form solution of the steady state concentration of solute atoms in a thin plate is obtained. It turns out that linear distribution of solute atoms in the plate is non-existent due to the interaction between chemical stresses and diffusion

  4. Do mesoscale faults in a young fold belt indicate regional or local stress?

    Science.gov (United States)

    Kokado, Akihiro; Yamaji, Atsushi; Sato, Katsushi

    2017-04-01

    The result of paleostress analyses of mesoscale faults is usually thought of as evidence of a regional stress. On the other hand, the recent advancement of the trishear modeling has enabled us to predict the deformation field around fault-propagation folds without the difficulty of assuming paleo mechanical properties of rocks and sediments. We combined the analysis of observed mesoscale faults and the trishear modeling to understand the significance of regional and local stresses for the formation of mesoscale faults. To this end, we conducted the 2D trishear inverse modeling with a curved thrust fault to predict the subsurface structure and strain field of an anticline, which has a more or less horizontal axis and shows a map-scale plane strain perpendicular to the axis, in the active fold belt of Niigata region, central Japan. The anticline is thought to have been formed by fault-propagation folding under WNW-ESE regional compression. Based on the attitudes of strata and the positions of key tephra beds in Lower Pleistocene soft sediments cropping out at the surface, we obtained (1) a fault-propagation fold with the fault tip at a depth of ca. 4 km as the optimal subsurface structure, and (2) the temporal variation of deformation field during the folding. We assumed that mesoscale faults were activated along the direction of maximum shear strain on the faults to test whether the fault-slip data collected at the surface were consistent with the deformation in some stage(s) of folding. The Wallace-Bott hypothesis was used to estimate the consistence of faults with the regional stress. As a result, the folding and the regional stress explained 27 and 33 of 45 observed faults, respectively, with the 11 faults being consistent with the both. Both the folding and regional one were inconsistent with the remaining 17 faults, which could be explained by transfer faulting and/or the gravitational spreading of the growing anticline. The lesson we learnt from this work was

  5. Local stress modification during in situ transmission electron microscopy straining experiments

    Czech Academy of Sciences Publication Activity Database

    Zárubová, Niva; Gemperle, Antonín; Gemperlová, Juliana

    2007-01-01

    Roč. 462, - (2007), s. 407-411 ISSN 0921-5093 R&D Projects: GA ČR GA202/04/2016 Institutional research plan: CEZ:AV0Z10100520 Keywords : in situ TEM straining, Local stress in a strained foil * local stress in a strained foil Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.457, year: 2007

  6. Development of generalized correlation equation for the local wall shear stress

    International Nuclear Information System (INIS)

    Jeon, Yu Mi; Bae, Jun Ho; Park, Joo Hwan

    2010-01-01

    The pressure drop characteristics for a fuel channel are essential for the design and reliable operation of a nuclear reactor. Over several decades, analytical methods have been developed to predict the friction factor in the fuel bundle flows. In order to enhance the accuracy of prediction for the pressure drop in a rod bundle, the influences of a channel wall and the local shear stress distribution should be considered. Hence, the correlation equation for a local shear stress distribution should be developed in order to secure an analytical solution for the friction factor of a rod bundle. For a side subchannel, which has the influence of the channel wall, the local shear stress distribution is dependent on the ratio of wall to diameter (W/D) as well as the ratio of pitch to diameter (P/D). In the case that W/D has the same value with P/D, the local shear stress distribution can be simply correlated with the function of angular position for each value of P/D. While, in the case that W/D has the different value with P/D, the correlation equation should be developed for each case of P/D and W/D. Hence, in the present study, the generalized correlation equation of a local shear stress distribution is developed for a side subchannel in the case that W/D has the different value with P/D

  7. Cantilever-based sensing: the origin of surface stress and optimization strategies

    International Nuclear Information System (INIS)

    Godin, Michel; Tabard-Cossa, Vincent; Miyahara, Yoichi; Grutter, Peter; Monga, Tanya; Bruce Lennox, R; Williams, P J; Beaulieu, L Y

    2010-01-01

    Many interactions drive the adsorption of molecules on surfaces, all of which can result in a measurable change in surface stress. This article compares the contributions of various possible interactions to the overall induced surface stress for cantilever-based sensing applications. The surface stress resulting from adsorption-induced changes in the electronic density of the underlying surface is up to 2-4 orders of magnitude larger than that resulting from intermolecular electrostatic or Lennard-Jones interactions. We reveal that the surface stress associated with the formation of high quality alkanethiol self-assembled monolayers on gold surfaces is independent of the molecular chain length, supporting our theoretical findings. This provides a foundation for the development of new strategies for increasing the sensitivity of cantilever-based sensors for various applications.

  8. Local structural ordering in surface-confined liquid crystals

    Science.gov (United States)

    Śliwa, I.; Jeżewski, W.; Zakharov, A. V.

    2017-06-01

    The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. Extending the McMillan mean field theory to include finite systems, it has been shown that confining surfaces can induce complex orientational and translational ordering of molecules. Typically, local smectic A, nematic, and isotropic phases have been shown to coexist in certain temperature ranges, provided that confining cells are sufficiently thick, albeit finite. Due to the nonlocality of surface interactions, the spatial arrangement of these local phases can display, in general, an unexpected complexity along the surface normal direction. In particular, molecules located in the vicinity of surfaces can still be organized in smectic layers, even though nematic and/or isotropic order can simultaneously appear in the interior of cells. The resulting surface freezing of smectic layers has been confirmed to occur even for rather weak surface interactions. The surface interactions cannot, however, prevent smectic layers from melting relatively close to system boundaries, even when molecules are still arranged in layers within the central region of the system. The internal interfaces, separating individual liquid-crystal phases, are demonstrated here to form fronts of local finite-size transitions that move across cells under temperature changes. Although the complex molecular ordering in surface confined liquid-crystal systems can essentially be controlled by temperature variations, specific thermal properties of these systems, especially the nature of the local transitions, are argued to be strongly conditioned to the degree of molecular packing.

  9. Local grid refinement for free-surface flow simulations

    NARCIS (Netherlands)

    van der Plas, Peter

    2017-01-01

    The principal goal of the current study is to explore and investigate the potential of local grid refinement for increasing the numerical efficiency of free-surface flow simulations in a practical context. In this thesis we propose a method for local grid refinement in the free-surface flow model

  10. Importance of Force Decomposition for Local Stress Calculations in Biomembrane Molecular Simulations.

    Science.gov (United States)

    Vanegas, Juan M; Torres-Sánchez, Alejandro; Arroyo, Marino

    2014-02-11

    Local stress fields are routinely computed from molecular dynamics trajectories to understand the structure and mechanical properties of lipid bilayers. These calculations can be systematically understood with the Irving-Kirkwood-Noll theory. In identifying the stress tensor, a crucial step is the decomposition of the forces on the particles into pairwise contributions. However, such a decomposition is not unique in general, leading to an ambiguity in the definition of the stress tensor, particularly for multibody potentials. Furthermore, a theoretical treatment of constraints in local stress calculations has been lacking. Here, we present a new implementation of local stress calculations that systematically treats constraints and considers a privileged decomposition, the central force decomposition, that leads to a symmetric stress tensor by construction. We focus on biomembranes, although the methodology presented here is widely applicable. Our results show that some unphysical behavior obtained with previous implementations (e.g. nonconstant normal stress profiles along an isotropic bilayer in equilibrium) is a consequence of an improper treatment of constraints. Furthermore, other valid force decompositions produce significantly different stress profiles, particularly in the presence of dihedral potentials. Our methodology reveals the striking effect of unsaturations on the bilayer mechanics, missed by previous stress calculation implementations.

  11. Simulations of surface stress effects in nanoscale single crystals

    Science.gov (United States)

    Zadin, V.; Veske, M.; Vigonski, S.; Jansson, V.; Muszinsky, J.; Parviainen, S.; Aabloo, A.; Djurabekova, F.

    2018-04-01

    Onset of vacuum arcing near a metal surface is often associated with nanoscale asperities, which may dynamically appear due to different processes ongoing in the surface and subsurface layers in the presence of high electric fields. Thermally activated processes, as well as plastic deformation caused by tensile stress due to an applied electric field, are usually not accessible by atomistic simulations because of the long time needed for these processes to occur. On the other hand, finite element methods, able to describe the process of plastic deformations in materials at realistic stresses, do not include surface properties. The latter are particularly important for the problems where the surface plays crucial role in the studied process, as for instance, in the case of plastic deformations at a nanovoid. In the current study by means of molecular dynamics (MD) and finite element simulations we analyse the stress distribution in single crystal copper containing a nanovoid buried deep under the surface. We have developed a methodology to incorporate the surface effects into the solid mechanics framework by utilizing elastic properties of crystals, pre-calculated using MD simulations. The method leads to computationally efficient stress calculations and can be easily implemented in commercially available finite element software, making it an attractive analysis tool.

  12. Phase-Field Relaxation of Topology Optimization with Local Stress Constraints

    DEFF Research Database (Denmark)

    Stainko, Roman; Burger, Martin

    2006-01-01

    inequality constraints. We discretize the problem by finite elements and solve the arising finite-dimensional programming problems by a primal-dual interior point method. Numerical experiments for problems with local stress constraints based on different criteria indicate the success and robustness......We introduce a new relaxation scheme for structural topology optimization problems with local stress constraints based on a phase-field method. In the basic formulation we have a PDE-constrained optimization problem, where the finite element and design analysis are solved simultaneously...

  13. Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

    Science.gov (United States)

    Ikkatai, Yuko; Watanabe, Shigeru

    2015-08-05

    Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

  14. Intrinsic stress evolution during amorphous oxide film growth on Al surfaces

    International Nuclear Information System (INIS)

    Flötotto, D.; Wang, Z. M.; Jeurgens, L. P. H.; Mittemeijer, E. J.

    2014-01-01

    The intrinsic stress evolution during formation of ultrathin amorphous oxide films on Al(111) and Al(100) surfaces by thermal oxidation at room temperature was investigated in real-time by in-situ substrate curvature measurements and detailed atomic-scale microstructural analyses. During thickening of the oxide a considerable amount of growth stresses is generated in, remarkably even amorphous, ultrathin Al 2 O 3 films. The surface orientation-dependent stress evolutions during O adsorption on the bare Al surfaces and during subsequent oxide-film growth can be interpreted as a result of (i) adsorption-induced surface stress changes and (ii) competing processes of free volume generation and structural relaxation, respectively

  15. On machine surface to the unit event causing residual stress

    International Nuclear Information System (INIS)

    Arunachalama, R.M.; Mannanb, M.A.; Spowageca, A.

    2005-01-01

    Integrity and reduce overall costs. Within the framework of surface integrity investigations, special emphasis is given to the measurement of residual stresses because they contribute directly to premature failure of components. Since the highest residual stresses are to be found in surface layers, these deserve special attention when dealing with dynamically, heavily loaded machine parts such as gas turbine components used in aero engines. Of the many techniques available for the measurement of residual stresses, the most highly developed and widely used non-destructive method is based on X-ray diffraction (XRD). However, it is not possible to use this technique for inspection of all the components, since it is time consuming, complicated as well as expensive. In this paper, a method is being proposed that augments the XRD method but at the same time capable of inspecting all the components. A non-destructive, visual inspection technique has been developed that can correlate the characteristic features on the surface to the unit event causing the residual stress and the type of residual stress generated on the machined surface. Pictures of the machined surfaces have been taken using a digital video microscope at a magnification of 500 and the surface feature correlated to the unit event causing the residual stress. Sharp and well defined long grooves indicate that the plastic deformation is dominated by a mechanical unit event while appearance of streaks and small areas of smeared material indicate that the plastic deformation is dominated by a thermal unit event. These trends have been confirmed by measuring the residual stresses using XRD. The proposed technique is an attempt at establishing a simple methodology that would be useful to industries manufacturing aerospace and other components that require good surface integrity. (Author)

  16. The effects of the local fracture stress and carbides on the cleavage fracture characteristics of Mn-Mo-Ni low alloy steels in the transition region

    International Nuclear Information System (INIS)

    Yang, Won Jon; Huh, Moo Young; Roh, Sung Joo; Lee, Bong Sang; Oh, Yong Jun; Hong, Jun Hwa

    2000-01-01

    In the ductile-brittle transition temperature region of SA508 C1.3 Mn-Mo-Ni low alloy steels, the relationship of the local fracture stress and carbides influencing the cleavage fracture behavior was investigated. Based on the ASTM E1921-97 standard method, the reference transition temperatures were determined by three point bending fracture toughness tests. A local fracture stress σ f * , was determined from a theoretical stress distribution in front of crack tip using the cleavage initiation distance measured in each fractured specimen surface. The local fracture stress values showed a strong relationship with toughness characteristics of the materials and those were larger in the materials of smaller carbide size. Quantitative analysis of carbides showed that carbides larger than a certain size are mainly responsible for the cleavage fracture in the ductile-brittle transition temperature region. (author)

  17. Stress fields around a crack lying parallel to a free surface

    International Nuclear Information System (INIS)

    Higashida, Yutaka; Kamada, K.

    1980-12-01

    A method of stress analysis for a two dimentional crack, which is subjected to internal gas pressure, and situated parallel to a free surface of a material, is presented. It is based on the concept of continuously distributed edge dislocations of two kinds, i.e. one with Burgers vector normal to the free surface and the other with parallel to it. Stress fields of individual dislocations are chosen so as to satisfy stress free boundary conditions at the free surface, by taking account of image dislocations. Distributions of the both kinds of dislocations in the crack are derived so as to give the internal gas pressure and, at the same time, to satisfy shear stress free boundary condition on the crack surface. Stress fields σsub(xx), σsub(yy) and σsub(xy) in the sub-surface layer are then determined from them. They have square root singularities at the crack-tip. (author)

  18. Use of local and global limit load solutions for plates with surface cracks under tension

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Y. [British Energy Generation Ltd, Barnett Way, Bamwood, Gloucester GL4 3RS (United Kingdom)], E-mail: yuebao.lei@british-energy.com

    2007-09-15

    Some available experimental results for the ductile failure of plates with surface cracks under tension are reviewed. The response of crack driving force, J, and the ligament strain near the local and global limit loads are investigated by performing elastic-perfectly plastic finite element (FE) analysis of a plate with a semi-elliptical crack under tension. The results show that a ligament may survive until the global collapse load is reached when the average ligament strain at the global collapse load, which depends on the uniaxial strain corresponding to the flow stress of the material and the crack geometry, is less than the true fracture strain of the material obtained from uniaxial tension tests. The FE analysis shows that ligament yielding corresponding to the local limit load has little effect on J and the average ligament strain, whereas approach to global collapse corresponds to a sharp increase in both J and the average ligament strain. The prediction of the FE value of J using the reference stress method shows that the global limit load is more relevant to J-estimation than the local one.

  19. Use of local and global limit load solutions for plates with surface cracks under tension

    International Nuclear Information System (INIS)

    Lei, Y.

    2007-01-01

    Some available experimental results for the ductile failure of plates with surface cracks under tension are reviewed. The response of crack driving force, J, and the ligament strain near the local and global limit loads are investigated by performing elastic-perfectly plastic finite element (FE) analysis of a plate with a semi-elliptical crack under tension. The results show that a ligament may survive until the global collapse load is reached when the average ligament strain at the global collapse load, which depends on the uniaxial strain corresponding to the flow stress of the material and the crack geometry, is less than the true fracture strain of the material obtained from uniaxial tension tests. The FE analysis shows that ligament yielding corresponding to the local limit load has little effect on J and the average ligament strain, whereas approach to global collapse corresponds to a sharp increase in both J and the average ligament strain. The prediction of the FE value of J using the reference stress method shows that the global limit load is more relevant to J-estimation than the local one

  20. Non destructive evaluation of residual stresses in welding and hard-surfacing processes

    International Nuclear Information System (INIS)

    Suarez, J.C.; Fernandez, L.M.; Cruz, C.; Aragon, B.; Merino, F.

    1995-01-01

    In this paper transversal and longitudinal stress profiles in welding and hard-surfacing by welding processes are presented. The stresses were measured by RMS of Barkhausen signal. In this work it is shown that in each case the level of stresses is strongly dependent on the number of weld beads of surfacing layers deposited. The subsequent deposition of new weld beads or surfacing layers produces a stress-relieving effect

  1. Determination of near surface in-situ stresses

    International Nuclear Information System (INIS)

    Garritty, P.; Irvin, R.

    1983-06-01

    One of the major unknowns affecting aspects of underground construction and the geohydrology of rock masses is the magnitude and direction of the geostatic principal stresses in the earth's crust. This is particularly the case in near surface rocks where there are indications that high horizontal stresses may exist. The techniques, experiences and results of a preliminary rock stress measurement programme conducted at shallow depth in the Carnmenellis Granite, Cornwall, using C.S.I.R.O. triaxial hollow inclusion cells are described. (author)

  2. Comment on 'Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies'

    Energy Technology Data Exchange (ETDEWEB)

    Gutman, E M, E-mail: gutman@bgu.ac.i [Department of Materials Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105 (Israel)

    2010-10-27

    In a recent publication by Olives (2010 J. Phys.: Condens. Matter 22 085005) he studied 'the thermodynamics and mechanics of the surface of a deformable body, following and refining the general approach of Gibbs' and believed that 'a new definition of the surface stress is given'. However, using the usual way of deriving the equations of Gibbs-Duhem type the author, nevertheless, has fallen into a mathematical discrepancy because he has tried to unite in one equation different thermodynamic systems and 'a new definition of the surface stress' has appeared known in the usual theory of elasticity. (comment)

  3. Local Stress States and Microstructural Damage Response Associated with Deformation Twins in Hexagonal Close Packed Metals

    Directory of Open Access Journals (Sweden)

    Indranil Basu

    2017-12-01

    Full Text Available The current work implements a correlative microscopy method utilizing electron back scatter diffraction, focused ion beam and digital image correlation to accurately determine spatially resolved stress profiles in the vicinity of grain/twin boundaries and tensile deformation twin tips in commercially pure titanium. Measured local stress gradients were in good agreement with local misorientation values. The role of dislocation-boundary interactions on the buildup of local stress gradients is elucidated. Stress gradients across the twin-parent interface were compressive in nature with a maximum stress magnitude at the twin boundary. Stress profiles near certain grain boundaries initially display a local stress minimum, followed by a typically observed “one over square root of distance” variation, as was first postulated by Eshelby, Frank and Nabarro. The observed trends allude to local stress relaxation mechanisms very close to the grain boundaries. Stress states in front of twin tips showed tensile stress gradients, whereas the stress state inside the twin underwent a sign reversal. The findings highlight the important role of deformation twins and their corresponding interaction with grain boundaries on damage nucleation in metals.

  4. Localization in small fcc-particles with surface irregularities and disorder

    International Nuclear Information System (INIS)

    Bucher, J.P.; Bloomfield, L.A.

    1991-01-01

    A numerical eigenvector analysis is used to investigate Anderson localization in small fcc-particles of N = 309 and N = 147 atoms. Special attention is given to the way size and surface roughness of the particles influence the localization behavior. States begin to localize in a non-exponential regime several lattice spacings from the center of localization and finally converge to a fully exponentially-localized regime for strong disorder. For smooth surface particles, it is found that the states localize first at the band bottom and a mobility edge can clearly be defined for increasing disorder. This doesn't seem to be the case for the rougher particles, where the band middle and the band bottom show similar behavior towards localization. Although particles with surface irregularities show an onset of localization for smaller values of the disorder than smooth particles, the localization length is greater. (orig.)

  5. The role of local stress perturbation on the simultaneous opening of orthogonal fractures

    Science.gov (United States)

    Boersma, Quinten; Hardebol, Nico; Barnhoorn, Auke; Bertotti, Giovanni; Drury, Martyn

    2016-04-01

    Orthogonal fracture networks (ladder-like networks) are arrangements that are commonly observed in outcrop studies. They form a particularly dense and well connected network which can play an important role in the effective permeability of tight hydrocarbon or geothermal reservoirs. One issue is the extent to which both the long systematic and smaller cross fractures can be simultaneously critically stressed under a given stress condition. Fractures in an orthogonal network form by opening mode-I displacements in which the main component is separation of the two fracture walls. This opening is driven by effective tensile stresses as the smallest principle stress acting perpendicular to the fracture wall, which accords with linear elastic fracture mechanics. What has been well recognized in previous field and modelling studies is how both the systematic fractures and perpendicular cross fractures require the minimum principle stress to act perpendicular to the fracture wall. Thus, these networks either require a rotation of the regional stress field or local perturbations in stress field. Using a mechanical finite element modelling software, a geological case of layer perpendicular systematic mode I opening fractures is generated. New in our study is that we not only address tensile stresses at the boundary, but also address models using pore fluid pressure. The local stress in between systematic fractures is then assessed in order to derive the probability and orientation of micro crack propagation using the theory of sub critical crack growth and Griffith's theory. Under effective tensile conditions, the results indicate that in between critically spaced systematic fractures, local effective tensile stresses flip. Therefore the orientation of the least principle stress will rotate 90°, hence an orthogonal fracture is more likely to form. Our new findings for models with pore fluid pressures instead of boundary tension show that the magnitude of effective tension

  6. Turbulent oscillating channel flow subjected to a free-surface stress.

    NARCIS (Netherlands)

    Kramer, W.; Clercx, H.J.H.; Armenio, V.

    2010-01-01

    The channel flow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean flow develops. The Reynolds number

  7. Stress analysis of local blisters coupling Raman spectroscopy and X-ray diffraction. Correlation between experimental results and continuous damage modelling for buckling in an iron oxide/phosphated iron system

    Energy Technology Data Exchange (ETDEWEB)

    Panicaud, B., E-mail: benoit.panicaud@utt.fr [Universite de Technologie de Troyes (UTT), CNRS UMR 6279, 12 rue Marie Curie, 10010 Troyes (France); Grosseau-Poussard, J.L. [LEMMA, Pole Sciences et Technologie, Universite de La Rochelle, Av. M. Crepeau, 17042 La Rochelle Cedex (France)

    2010-12-01

    In this present work, local stress development in the iron oxide layers growing on phosphated {alpha}-Fe at 400 deg. C in ambient air is investigated by Raman spectroscopy. Coupled with X-ray diffraction it enables to obtain directly local stresses' maps in the oxide layers. Use of Raman spectroscopy allows obtaining better accuracy on mechanical behaviour at local scale. This characterisation technique is very useful to study systems developing mechanical heterogeneities on surface, especially in case of buckling phenomenon. Investigations on particular local blisters have been done to measure some characteristic lengths at local scale. From local measurements, we are able to evaluate general effect of buckling from simplified scale transition. So, a macroscopic approach has been performed to calculate global stress evolution of the oxide layer, based on continuous damage mechanics. Consequently, it leads to good comparison between modelling and experimental values (global stresses versus oxidation time) in {alpha}-Fe{sub 2}O{sub 3} oxide.

  8. Stress-induced roughening instabilities along surfaces of piezoelectric materials

    International Nuclear Information System (INIS)

    Chien, N.Y.; Gao, H.

    1993-01-01

    The possibility of using electric field to stabilize surfaces of piezoelectric solids against stress-induced morphological roughening is explored in this paper. Two types of idealized boundary conditions are considered: (1) a traction free and electrically insulating surface and (2) a traction free and electrically conducting surface. A perturbation solution for the energy variation associated with surface roughening suggests that the electric field can be used to suppress the roughening instability to various degrees. A completely stable state is possible in the insulating case, and kinetically more stable states can be attained in the conducting case. The stabilization has importance in reducing concentration of stress and electric fields due to microscopic surface roughness which might trigger failure processes involving dislocation, cracks and dielectric breakdown

  9. Stimulated resonant scattering at stressed fused silica surface

    International Nuclear Information System (INIS)

    Bouchut, Philippe; Reymermier, Maryse

    2015-01-01

    The radiative emission in CO 2 laser heated stressed fused silica is radically modified when gold microspheres are on the surface. At high heating rates, the emission dynamics changes from thermoluminescence to stimulated resonant scattering with an emission rate that is increased tenfold and the near infrared (NIR) spectrum is red-shifted. We show that the dynamic tensile stress that rises in heated silica is coupled with a fluctuating electromagnetic field that enables electromagnetic friction between moving OH emitters from silica bulk and NIR resonant scatterers at the silica surface. (paper)

  10. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

  11. Vortex configuration in the presence of local magnetic field and locally applied stress

    Energy Technology Data Exchange (ETDEWEB)

    Wissberg, Shai; Kremen, Anna; Shperber, Yishai; Kalisky, Beena, E-mail: beena@biu.ac.il

    2017-02-15

    Highlights: • We discuss different ways to determine vortex configuration using a scanning SQUID. • We determined the vortex configuration by approaching the sample during cooling. • We observed an accumulation of vortices when contact was made with the sample. • We show how we can manipulate local vortex configuration using contact. - Abstract: Vortex configuration is determined by the repulsive interaction, which becomes dominant with increasing vortex density, by the pinning potential, and by other considerations such as the local magnetic fields, currents flowing in the sample, or as we showed recently, by local stress applied on the sample. In this work we describe different ways to control vortex configuration using scanning SQUID microscopy.

  12. Vortex configuration in the presence of local magnetic field and locally applied stress

    International Nuclear Information System (INIS)

    Wissberg, Shai; Kremen, Anna; Shperber, Yishai; Kalisky, Beena

    2017-01-01

    Highlights: • We discuss different ways to determine vortex configuration using a scanning SQUID. • We determined the vortex configuration by approaching the sample during cooling. • We observed an accumulation of vortices when contact was made with the sample. • We show how we can manipulate local vortex configuration using contact. - Abstract: Vortex configuration is determined by the repulsive interaction, which becomes dominant with increasing vortex density, by the pinning potential, and by other considerations such as the local magnetic fields, currents flowing in the sample, or as we showed recently, by local stress applied on the sample. In this work we describe different ways to control vortex configuration using scanning SQUID microscopy.

  13. Residual stresses estimation in tubes after rapid heating of surface

    International Nuclear Information System (INIS)

    Serikov, S.V.

    1992-01-01

    Results are presented on estimation of residual stresses in tubes of steel types ShKh15, EhP836 and 12KIMF after heating by burning pyrotechnic substance inside tubes. External tube surface was heated up to 400-450 deg C under such treatment. Axial stresses distribution over tube wall thickness was determined for initial state, after routine heat treatment and after heating with the use of fireworks. Inner surface heating was shown to essentially decrease axial stresses in tubes

  14. Study on the essential variables for pipe outer surface irradiated laser stress improvement process (L-SIP). Development of pipe outer surface irradiated laser stress improvement process (L-SIP)

    International Nuclear Information System (INIS)

    Ohta, Takahiro; Kamo, Kazuhiko; Muroya, Itaru; Asada, Seiji; Nakamura, Yasuo

    2009-01-01

    The new process called L-SIP (outer surface irradiated Laser Stress Improvement Process) is developed to improve the tensile residual stress of the inner surface near the butt welded joints of pipes in the compression stress. The temperature gradient occurs in the thickness of pipes in heating the outer surface rapidly by laser beam. By the thermal expansion difference between the inner surface and the outer surface, the compression stress occurs near the inner surface of pipes. In this paper, the essential variables for L-SIP is studied by experimental and FEM analysis. The range of the essential variables for L-SIP, which are defined by thermo-elastic FEM analysis, are Tmax=550 - 650degC, L Q /√rh ≥ 3, W Q /√rh ≥ 1.7, and, 0.04 ≤ F 0 ≤ 0.10 where Tmax is maximum temperature on the monitor point of the outer surface, F 0 is k x τ 0 /h 2 , k is thermal diffusivity coefficient, τ 0 is the temperature rise time from 100degC to maximum temperature on the monitor point of the outer surface, W Q is τ 0 x v, υ is moving velocity, L Q is the uniform temperature length in the axial direction, h is thickness of the pipe, and r is average radius of the pipe. It is showed by thermo-elastic-plastic FEM analysis that the residual stresses near the inner surface of pipes are improved in 4 different size pipes under the same essential variables. L-SIP is actually applied to welding joints of 4B x Sch160 and 2B x Sch80 SUS304 type stainless steel pipes within the defined range of the essential variables. The measured welding residual stresses on the inner surface near the welding joints are tensile. The residual stresses on the inner surface change to compression in all joints by L-SIP. (author)

  15. Effect of surface stress and irregularity of the interface on the ...

    Indian Academy of Sciences (India)

    Surface stress; irregularity of the interface; magneto-elastic crustal ... stress plays a vital role in the propagation of waves due to the fact that the surface of a ...... Mumbai, for his computational help towards the numerical calculations and graphs.

  16. Local equivalence, surface-code states, and matroids

    International Nuclear Information System (INIS)

    Sarvepalli, Pradeep; Raussendorf, Robert

    2010-01-01

    Recently, Ji et al. disproved the local-unitary-local Clifford (LU-LC) conjecture and showed that the local unitary (LU) and local Clifford (LC) equivalence classes of the stabilizer states are not always the same. Despite the fact that this settles the LU-LC conjecture, a sufficient condition for stabilizer states that violate the LU-LC conjecture is not known. In this paper, we investigate further the properties of stabilizer states with respect to local equivalence. Our first result shows that there exist infinitely many stabilizer states that violate the LU-LC conjecture. In particular, we show that for all numbers of qubits n≥28, there exist distance-two stabilizer states which are counterexamples to the LU-LC conjecture. We prove that, for all odd n≥195, there exist stabilizer states with distance greater than two that are LU equivalent but not LC equivalent. Two important classes of stabilizer states that are of great interest in quantum computation are the cluster states and stabilizer states of the surface codes. We show that, under some minimal restrictions, both these classes of states preclude any counterexamples. In this context, we also show that the associated surface codes do not have any encoded non-Clifford transversal gates. We characterize the Calderbank-Shor-Steane (CSS) surface-code states in terms of a class of minor closed binary matroids. In addition to making a connection to an important open problem in binary matroid theory, this characterization does in some cases provide an efficient test for CSS states that are not counterexamples.

  17. FIB-based measurement of local residual stresses on microsystems

    Science.gov (United States)

    Vogel, Dietmar; Sabate, Neus; Gollhardt, Astrid; Keller, Juergen; Auersperg, Juergen; Michel, Bernd

    2006-03-01

    The paper comprises research results obtained for stress determination on micro and nanotechnology components. It meets the concern of controlling stresses introduced to sensors, MEMS and electronics devices during different micromachining processes. The method bases on deformation measurement options made available inside focused ion beam equipment. Removing locally material by ion beam milling existing stresses / residual stresses lead to deformation fields around the milled feature. Digital image correlation techniques are used to extract deformation values from micrographs captured before and after milling. In the paper, two main milling features have been analyzed - through hole and through slit milling. Analytical solutions for stress release fields of in-plane stresses have been derived and compared to respective experimental findings. Their good agreement allows to settle a method for determination of residual stress values, which is demonstrated for thin membranes manufactured by silicon micro technology. Some emphasis is made on the elimination of main error sources for stress determination, like rigid body object displacements and rotations due to drifts of experimental conditions under FIB imaging. In order to illustrate potential application areas of the method residual stress suppression by ion implantation is evaluated by the method and reported here.

  18. Effects of microstructure and local mechanical fields on intergranular stress corrosion cracking of a friction stir welded aluminum–copper–lithium 2050 nugget

    International Nuclear Information System (INIS)

    Dhondt, Matthieu; Aubert, Isabelle; Saintier, Nicolas; Olive, Jean Marc

    2014-01-01

    Highlights: • Applied stress changes the corrosion mode from pitting to intergranular cracking. • Residual stresses are sufficient to induce intergranular stress corrosion cracking. • Effect of crystallographic texture on the development of IGSCC evidenced by EBSD. • Cubic elasticity drives the local orientation of the intergranular cracking. • Tomography observations show the 3D nature of the corrosion development. - Abstract: The effects of the microstructure and mechanical fields on intergranular stress corrosion cracking (IGSCC) of the nugget zone of heat treated welds obtained by friction stir welding in the AA2050 aluminum alloy have been investigated at different scales. At low strain rate, in 1.0 NaCl aqueous solution, IGSCC develops in the microstructure, whereas only pitting corrosion is observed without any mechanical stress. Based on surface observations, EBSD analysis and X-ray tomography, the key role of sub-millimetric textured bands (induced by the welding process) on the IGSCC is demonstrated. Analyses at a more local scale show the grain boundary (low angle boundary, special coincident site lattice boundary or high angle boundary) do not have a significant effect on crack initiation. Crystal plasticity finite element calculations show that the threshold normal stress at grain boundaries for IGSCC development is about 80% of the macroscopic stress. It is also highlighted by crystal plasticity calculations that there is a drastic effect of the local stress field on the shape of cracks. Finally, it is shown that plasticity induced residual stresses are sufficient for the formation of IGSCC

  19. Efficient computer program EPAS-J1 for calculating stress intensity factors of three-dimensional surface cracks

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Watanabe, Takayuki; Yagawa, Genki.

    1982-03-01

    A finite element computer program EPAS-J1 was developed to calculate the stress intensity factors of three-dimensional cracks. In the program, the stress intensity factor is determined by the virtual crack extension method together with the distorted elements allocated along the crack front. This program also includes the connection elements based on the Lagrange multiplier concept to connect such different kinds of elements as the solid and shell elements, or the shell and beam elements. For the structure including three-dimensional surface cracks, the solid elements are employed only at the neighborhood of a surface crack, while the remainder of the structure is modeled by the shell or beam elements due to the reason that the crack singularity is very local. Computer storage and computational time can be highly reduced with the application of the above modeling technique for the calculation of the stress intensity factors of the three-dimensional surface cracks, because the three-dimensional solid elements are required only around the crack front. Several numerical analyses were performed by the EPAS-J1 program. At first, the accuracies of the connection element and the virtual crack extension method were confirmed using the simple structures. Compared with other techniques of connecting different kinds of elements such as the tying method or the method using anisotropic plate element, the present connection element is found to provide better results than the others. It is also found that the virtual crack extension method provides the accurate stress intensity factor. Furthermore, the results are also presented for the stress intensity factor analyses of cylinders with longitudinal or circumferential surface cracks using the combination of the various kinds of elements together with the connection elements. (author)

  20. Influence of Thread Root Radius on Maximum Local Stresses at Large Diameter Bolts under Axial Loading

    Directory of Open Access Journals (Sweden)

    Cojocaru Vasile

    2014-06-01

    Full Text Available In the thread root area of the threaded bolts submitted to axial loading occur local stresses, higher that nominal stresses calculated for the bolts. These local stresses can generate failure and can reduce the fatigue life of the parts. The paper is focused on the study of the influence of the thread root radius on the maximum local stresses. A large diameter trapezoidal bolt was subjected to a static analysis (axial loading using finite element simulation.

  1. Theoretical analysis of surface stress for a microcantilever with varying widths

    International Nuclear Information System (INIS)

    Li Xianfang; Peng Xulong

    2008-01-01

    A theoretical model of surface stress is developed in this paper for a microcantilever with varying widths, and a method for calculating the surface stress via static deflection, slope angle or radius at curvature of the cantilever beam is presented. This model assumes that surface stresses are uniformly distributed on one surface of the cantilever beam. Based on this stressor model and using the small deformation Euler-Bernoulli beam theory, a fourth-order ordinary differential governing equation with varying coefficients or an equivalent second-order integro-differential equation is derived. A simple approach is then proposed to determine the solution of the resulting equation, and a closed-form approximate solution with high accuracy can be obtained. For rectangular and V-shaped microfabricated cantilevers, the dependences of transverse deflection, slope and curvature of the beam on the surface stresses are given explicitly. The obtained results indicate that the zeroth order approximation of the stressor model reduces to the end force model with a linear curvature for a rectangular cantilever. For larger surface stresses, the curvature exhibits a non-linear behaviour. The predictions through the stressor model give higher accuracy than those from the end moment and end force models and satisfactorily agree with experimental data. The derived closed-form solution can serve as a theoretical benchmark for verifying numerically obtained results for microcantilevers as atomic force microscopy and micromechanical sensors

  2. Effect of Applied Stress and Temperature on Residual Stresses Induced by Peening Surface Treatments in Alloy 600

    Science.gov (United States)

    Telang, A.; Gnäupel-Herold, T.; Gill, A.; Vasudevan, V. K.

    2018-04-01

    In this study, the effects of applied tensile stress and temperature on laser shock peening (LSP) and cavitation shotless peening (CSP)-induced compressive residual stresses were investigated using neutron and x-ray diffraction. Residual stresses on the surface, measured in situ, were lower than the applied stress in LSP- and CSP-treated Alloy 600 samples (2 mm thick). The residual stress averaged over the volume was similar to the applied stress. Compressive residual stresses on the surface and balancing tensile stresses in the interior relax differently due to hardening induced by LSP. Ex situ residual stress measurements, using XRD, show that residual stresses relaxed as the applied stress exceeded the yield strength of the LSP- and CSP-treated Alloy 600. Compressive residual stresses induced by CSP and LSP decreased by 15-25% in magnitude, respectively, on exposure to 250-450 °C for more than 500 h with 10-11% of relaxation occurring in the first few hours. Further, 80% of the compressive residual stresses induced by LSP and CSP treatments in Alloy 600 were retained even after long-term aging at 350 °C for 2400 h.

  3. Are Geotehrmal Reservoirs Stressed Out?

    Science.gov (United States)

    Davatzes, N. C.; Laboso, R. C.; Layland-Bachmann, C. E.; Feigl, K. L.; Foxall, W.; Tabrez, A. R.; Mellors, R. J.; Templeton, D. C.; Akerley, J.

    2017-12-01

    Crustal permeability can be strongly influenced by developing connected networks of open fractures. However, the detailed evolution of a fracture network, its extent, and the persistence of fracture porosity are difficult to analyze. Even in fault-hosted geothermal systems, where heat is brought to the surface from depth along a fault, hydrothermal flow is heterogeneously distributed. This is presumably due to variations in fracture density, connectivity, and attitude, as well as variations in fracture permeability caused by sealing of fractures by precipitated cements or compaction. At the Brady Geothermal field in Nevada, we test the relationship between the modeled local stress state perturbed by dislocations representing fault slip or volume changes in the geothermal reservoir inferred from surface deformation measured by InSAR and the location of successful geothermal wells, hydrothermal activity, and seismicity. We postulate that permeability is favored in volumes that experience positive Coulomb stress changes and reduced compression, which together promote high densities of dilatant fractures. Conversely, permeability can be inhibited in locations where Coulomb stress is reduced, compression promotes compaction, or where the faults are poorly oriented in the stress field and consequently slip infrequently. Over geologic time scales spanning the development of the fault system, these local stress states are strongly influenced by the geometry of the fault network relative to the remote stress driving slip. At shorter time scales, changes in fluid pressure within the fracture network constituting the reservoir cause elastic dilations and contractions. We integrate: (1) direct observations of stress state and fractures in boreholes and the mapped geometry of the fault network; (2) evidence of permeability from surface hydrothermal features, production/injection wells and surface deformations related to pumping history; and (3) seismicity to test the

  4. The measurement of in-situ stress in near surface environments

    International Nuclear Information System (INIS)

    Garritty, P.; Irvin, R.A.

    1984-04-01

    One of the major unknowns affecting aspects of underground construction and the geohydrology of rock masses is the magnitude and direction of the geostatic principal stresses in the earth's crust. This is particularly the case in near surface rocks where there are indications that high horizontal stresses may exist. The measurement of stress in near surface environments is particularly difficult. The techniques, experience and results of a geostatic stress measurement programme using four commercially available devices at shallow depth in the Carnmenellis Granite are critically discussed and compared. This report also brings together some of the conclusions of two previous reports in the series, Garritty (1983) and Garritty and Irvin (1983), and emphasises the fundamental relationship between the state of stress in the earth's crust and the geohydrology of rock masses. (author)

  5. Computation of stress on the surface of a soft homogeneous arbitrarily shaped particle.

    Science.gov (United States)

    Yang, Minglin; Ren, Kuan Fang; Wu, Yueqian; Sheng, Xinqing

    2014-04-01

    Prediction of the stress on the surface of an arbitrarily shaped particle of soft material is essential in the study of elastic properties of the particles with optical force. It is also necessary in the manipulation and sorting of small particles with optical tweezers, since a regular-shaped particle, such as a sphere, may be deformed under the nonuniform optical stress on its surface. The stress profile on a spherical or small spheroidal soft particle trapped by shaped beams has been studied, however little work on computing the surface stress of an irregular-shaped particle has been reported. We apply in this paper the surface integral equation with multilevel fast multipole algorithm to compute the surface stress on soft homogeneous arbitrarily shaped particles. The comparison of the computed stress profile with that predicted by the generalized Lorenz-Mie theory for a water droplet of diameter equal to 51 wavelengths in a focused Gaussian beam show that the precision of our method is very good. Then stress profiles on spheroids with different aspect ratios are computed. The particles are illuminated by a Gaussian beam of different waist radius at different incidences. Physical analysis on the mechanism of optical stress is given with help of our recently developed vectorial complex ray model. It is found that the maximum of the stress profile on the surface of prolate spheroids is not only determined by the reflected and refracted rays (orders p=0,1) but also the rays undergoing one or two internal reflections where they focus. Computational study of stress on surface of a biconcave cell-like particle, which is a typical application in life science, is also undertaken.

  6. Localized Failure Promoted by Heterogeneous Stresses in Tectonic Mélanges

    Science.gov (United States)

    Phillips, N. J.; Rowe, C. D.; Ujiie, K.

    2017-12-01

    Within the shallow (PLC) toolbox developed at the University of Maine, which uses Asymptotic Expansion Homogenization (AEH) over a finite element mesh to determine the instantaneous stress distributions in a multiphase system. We model the shale matrix mélange to be deforming through a modified flow law for viscous creep based on coupled frictional sliding and pressure solution, where at a strain rate of 10-12 s-1 the flow stress is 10 MPa under the temperature (190 ºC) and pressure ( 100 MPa) conditions during deformation, and describe the behaviour of the basaltic blocks using experimentally-derived power law flow laws. The results show that at the strain rates calculated based on plate-rate motion, differential stresses high enough to cause comminution of the basalts ( 300 MPa) correspond strongly to areas around the blocks with basalt derived cataclasites. Within the basalt derived cataclasites, thin zones of ultracataclasite record localized slip. We hypothesize that the heterogeneous stress distributions within subduction mélanges: 1) fractures the strong basalt thereby facilitating weakening through fluid-rock interactions, and 2) promotes localized slip (and occasionally seismicity) within these zones of altered basalt along the margins of strong intact basalt.

  7. The Alignment of the Mean Wind and Stress Vectors in the Unstable Surface Layer

    Science.gov (United States)

    Bernardes, M.; Dias, N. L.

    2010-01-01

    A significant non-alignment between the mean horizontal wind vector and the stress vector was observed for turbulence measurements both above the water surface of a large lake, and over a land surface (soybean crop). Possible causes for this discrepancy such as flow distortion, averaging times and the procedure used for extracting the turbulent fluctuations (low-pass filtering and filter widths etc.), were dismissed after a detailed analysis. Minimum averaging times always less than 30 min were established by calculating ogives, and error bounds for the turbulent stresses were derived with three different approaches, based on integral time scales (first-crossing and lag-window estimates) and on a bootstrap technique. It was found that the mean absolute value of the angle between the mean wind and stress vectors is highly related to atmospheric stability, with the non-alignment increasing distinctively with increasing instability. Given a coordinate rotation that aligns the mean wind with the x direction, this behaviour can be explained by the growth of the relative error of the u- w component with instability. As a result, under more unstable conditions the u- w and the v- w components become of the same order of magnitude, and the local stress vector gives the impression of being non-aligned with the mean wind vector. The relative error of the v- w component is large enough to make it undistinguishable from zero throughout the range of stabilities. Therefore, the standard assumptions of Monin-Obukhov similarity theory hold: it is fair to assume that the v- w stress component is actually zero, and that the non-alignment is a purely statistical effect. An analysis of the dimensionless budgets of the u- w and the v- w components confirms this interpretation, with both shear and buoyant production of u- w decreasing with increasing instability. In the v- w budget, shear production is zero by definition, while buoyancy displays very low-intensity fluctuations around

  8. Mobility of Yield-Stress Fluids on Lubricant-Impregnated Surface

    Science.gov (United States)

    Rapoport, Leonid; Solomon, Brian; Varanasi, Kripa; Varanasi Research Group Team

    2017-11-01

    Assuring the flow of yield-stress fluids is an essential problem for various industries such as consumer products, health care, and energy. Elimination of wall-induced pinning forces can potentially save power and cleaning costs as well as enable the flow of yield-stress fluids in channels previously considered too narrow. Lubricant-Impregnated Surfaces (LIS) have been demonstrated to change the dynamic behavior of yield-stress fluids and enable them to move as bulk without shearing at all. However, despite the wide applicability of this technology and its general appeal, the fundamental principles governing the performance of yield stress fluids on LIS have not yet been fully explained. In this work, we explore the mobility of yield stress fluids on a wide range of LIS, and explain the connection between macroscale behavior and the microscale properties of the LIS. Specifically, we show a striking difference in mobility between an LIS that contains a lubricant which fully spreads on the rough micro-features of the surface, and an LIS that contains a lubricant which only imbibes these features but does spread over them

  9. Mathematical model to determine the surface stress acting on the tooth of gear

    Directory of Open Access Journals (Sweden)

    Hinojosa-Torres J.

    2010-01-01

    Full Text Available Surface stress on the surface contact of gear tooth calculated by the Buckingham equation constitutes the basis for The American Gear Manufacturers Association (AGMA pitting resistance formula, which is based on a normal stress that does not cause failure since the yielding in contact problems is caused by shear stresses. An alternative expression based on the maximum-shear-stress is proposed in this paper. The new expression is obtained by using the maximum-shear-stress distribution and the Tresca failure criteria in order to know the maximum-shear-stress value and its location beneath the contact surface. Remarkable differences between the results using the proposed equation and those when the AGMA equation is applied are found.

  10. Surface temperature and evapotranspiration: application of local scale methods to regional scales using satellite data

    International Nuclear Information System (INIS)

    Seguin, B.; Courault, D.; Guerif, M.

    1994-01-01

    Remotely sensed surface temperatures have proven useful for monitoring evapotranspiration (ET) rates and crop water use because of their direct relationship with sensible and latent energy exchange processes. Procedures for using the thermal infrared (IR) obtained with hand-held radiometers deployed at ground level are now well established and even routine for many agricultural research and management purposes. The availability of IR from meteorological satellites at scales from 1 km (NOAA-AVHRR) to 5 km (METEOSAT) permits extension of local, ground-based approaches to larger scale crop monitoring programs. Regional observations of surface minus air temperature (i.e., the stress degree day) and remote estimates of daily ET were derived from satellite data over sites in France, the Sahel, and North Africa and summarized here. Results confirm that similar approaches can be applied at local and regional scales despite differences in pixel size and heterogeneity. This article analyzes methods for obtaining these data and outlines the potential utility of satellite data for operational use at the regional scale. (author)

  11. The Effect of Applied Tensile Stress on Localized Corrosion in Sensitized AA5083

    Science.gov (United States)

    2015-09-01

    corrosion, but if exposed to elevated temperature for prolonged periods of time the alloy becomes sensitized. Since the β phase is more anodic than the...degree of localized corrosion for sensitized AA5083 under an applied tensile stress. AA5083 is an aluminum -magnesium alloy that experiences severe...direction. 14. SUBJECT TERMS Aluminum alloy , AA5083, IGSCC, intergranular stress corrosion cracking, localized corrosion, sensitized aluminum 15

  12. Experimental determination and theoretical analysis of local residual stress at grain scale

    NARCIS (Netherlands)

    Basu, Indranil; Ocelík, Václav; De Hosson, Jeff Th M.

    2017-01-01

    Grain/phase boundaries contribute significantly to build up of residual stresses, owing to varied plastic/thermal response of different grain orientations or phases during thermomechanical treatment. Hence, accurate quantification of such local scale stress gradients in commercial components is

  13. The local quantum-mechanical stress tensor in Thomas-Fermi approximation and gradient expansion method

    International Nuclear Information System (INIS)

    Kaschner, R.; Graefenstein, J.; Ziesche, P.

    1988-12-01

    From the local momentum balance using density functional theory an expression for the local quantum-mechanical stress tensor (or stress field) σ(r) of non-relativistic Coulomb systems is found out within the Thomas-Fermi approximation and its generalizations including gradient expansion method. As an illustration the stress field σ(r) is calculated for the jellium model of the interface K-Cs, containing especially the adhesive force between the two half-space jellia. (author). 23 refs, 1 fig

  14. Stress errors in a case of developmental surface dyslexia in Filipino.

    Science.gov (United States)

    Dulay, Katrina May; Hanley, J Richard

    2015-01-01

    This paper reports the case of a dyslexic boy (L.A.) whose impaired reading of Filipino is consistent with developmental surface dyslexia. Filipino has a transparent alphabetic orthography with stress typically falling on the penultimate syllable of multisyllabic words. However, exceptions to the typical stress pattern are not marked in the Filipino orthography. L.A. read words with typical stress patterns as accurately as controls, but made many more stress errors than controls when reading Filipino words with atypical stress. He regularized the pronunciation of many of these words by incorrectly placing the stress on the penultimate syllable. Since he also read nonwords as accurately and quickly as controls and performed well on tests of phonological awareness, L.A. appears to present a clear case of developmental surface dyslexia in a transparent orthography.

  15. Localized deformation as a key precursor to initiation of intergranular stress corrosion cracking of austenitic stainless steels employed in nuclear power plants

    International Nuclear Information System (INIS)

    Karlsen, Wade; Diego, Gonzalo; Devrient, Bastian

    2010-01-01

    Cold-work has been associated with the occurrence of intergranular cracking of stainless steels employed in light water reactors. This study examined the deformation behavior of AISI 304, AISI 347 and a higher stacking fault energy model alloy subjected to bulk cold-work and (for 347) surface deformation. Deformation microstructures of the materials were examined and correlated with their particular mechanical response under different conditions of temperature, strain rate and degree of prior cold-work. Select slow-strain rate tensile tests in autoclaves enabled the role of local strain heterogeneity in crack initiation in pressurized water reactor environments to be considered. The high stacking fault energy material exhibited uniform strain hardening, even at sub-zero temperatures, while the commercial stainless steels showed significant heterogeneity in their strain response. Surface treatments introduced local cold-work, which had a clear effect on the surface roughness and hardness, and on near-surface residual stress profiles. Autoclave tests led to transgranular surface cracking for a circumferentially ground surface, and intergranular crack initiation for a polished surface.

  16. Effects on Machining on Surface Residual Stress of SA 508 and Austenitic Stainless Steel

    International Nuclear Information System (INIS)

    Lee, Kyoung Soo; Lee, Seong Ho; Park, Chi Yong; Yang, Jun Seok; Lee, Jeong Geun; Park, Jai Hak

    2011-01-01

    Primary water stress corrosion cracking has occurred in dissimilar weld areas in nuclear power plants. Residual stress is a driving force in the crack. Residual stress may be generated by weld or surface machining. Residual stress due to surface machining depends on the machining method, e.g., milling, grinding, or EDM. The stress is usually distributed on or near the surface of the material. We present the measured residual stress for machining on SA 508 and austenitic stainless steels such as TP304 and F316. The residual stress can be tensile or compressive depending on the machining method. The depth and the magnitude of the residual stress depend on the material and the machining method

  17. Absence of surface stress change during pentacene thin film growth on the Si(111)-(7 x 7) surface: a buried reconstruction interface

    International Nuclear Information System (INIS)

    Kury, P; Horn von Hoegen, M; Heringdorf, F-J Meyer zu; Roos, K R

    2008-01-01

    We use high-resolution surface stress measurements to monitor the surface stress during the growth of pentacene (C 22 H 14 ) on the (7x7) reconstructed silicon (111) surface. No significant change in the surface stress is observed during the pentacene growth. Compared to the changes in the surface stress observed for Si and Ge deposition on the Si(111)-(7x7) surface, the insignificant change in the surface stress observed for the pentacene growth suggests that the pentacene molecules of the first adsorbate layer, although forming strong covalent bonds with the Si adatoms, do not alter the structure of the (7x7) reconstruction. The (7x7) reconstruction remains intact and, with subsequent deposition of pentacene, eventually becomes buried under the growing film. This failure of the pentacene to affect the structure of the reconstruction may represent a fundamental difference between the growth of organic thin films and that of inorganic thin films on semiconductor surfaces

  18. Practical Considerations for Thermal Stresses Induced by Surface Heating

    International Nuclear Information System (INIS)

    Blanchard, James P.

    2003-01-01

    Rapid surface heating can induce large stresses in solids. A relatively simple model, assuming full constraint in two dimensions and no constraint in the third dimension, can adequately model stresses in a wide variety of situations. This paper derives this simple model, and supports it with criteria for its validity. Phenomena that are considered include non-zero penetration depths for the heat deposition, spatial non-uniformity in the surface heating, and elastic waves. Models for each of these cases, using simplified geometries, are used to develop quantitative limits for their applicability

  19. Near-surface residual stresses and microstructural changes after turning of a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Schlauer, Christian

    2003-07-01

    Nickel-based superalloys are precipitation hardened alloys with complex compositions. They are used in aircraft engines and land-based gas turbines in load bearing structural components that are exposed to high temperatures. Failure mechanisms in this environment are high and low cycle fatigue, creep, and corrosion. During manufacturing, residual stresses are often introduced into the material due to inhomogeneous plastic deformations, both intentionally and unintentionally. One such manufacturing process is metal cutting, which introduces residual stresses in the surface layer. The stress state in the near-surface zone of components is of special interest as the surface often experiences peak loads and cracks have their starting point there. In this thesis, near-surface residual stress distributions and microstructural changes are studied in the nickel-based superalloy Inconel 718 for two different turning operations, face grooving and facing. Process variables are in both cases cutting speed and feed that have been varied between (10 and 1200) m/min and (0.01 and 0.5) mm, respectively. The first turning technique face grooving, which gives cutting conditions similar to orthogonal cutting, showed a clear dependency of the residual stresses on the cutting speed. The tensile stress at the surface, the maximum compressive stress below the surface, and the thickness of the affected layer increase with increasing cutting speed. The tensile stresses are constrained to a thin surface layer and compressive residual stresses below the surface dominate the depth profile of the residual stresses. Only at low cutting speed, residual stresses were largely avoided. The second turning technique facing confirmed the dependency of the residual stresses on the cutting speed and revealed a similar dependency on the feed. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic

  20. Local versus regional active stress field in 5900m San Gregorio Magno 1 well (southern Apennines, Italy).

    Science.gov (United States)

    Pierdominici, S.; Montone, P.; Mariucci, M. T.

    2009-04-01

    The aim of this work is to characterize the local stress field in a peculiar sector of the southern Apennines by analyzing borehole breakouts, fractures and logging data along the San Gregorio Magno 1 deep well, and to compare the achieved stress field with the regional one. The study area is characterized by diffuse low-Magnitude seismicity, although in historical times it has been repeatedly struck by moderate to large earthquakes. We have analyzed in detail the 5900m San Gregorio Magno 1 well drilled in 1996-97 by ENI S.p.A. and located very close (1.3 km away) to the Irpinia Fault. This fault was responsible of the strongest earthquake happened in this area, the 23rd November 1980 M6.9 earthquake that produced the first unequivocal historical surface faulting ever documented in Italy. The mainshock enucleated on a fault 38 km-long with a strike of 308° and 60-70° northeast-dipping, consistent with a NE-SW T-axis and a normal faulting tectonic regime. Borehole breakouts, active faults and focal mechanism solutions have allowed to define the present-day stress along and around the San Gregorio Magno 1 well and other analysis (logging data) to discriminate the presence of fracture zones and/or faults at depth. We have considered data from 1200m to the bottom of San Gregorio Magno 1 well. Our analysis of stress-induced wellbore breakouts shows an inhomogeneous direction of minimum horizontal stress (N359+-31°) orientation along the well. This direction is moderately consistent with the Shmin-trend determined from breakouts in other wells in this region and also with the regional active stress field inferred from active faults and earthquake focal plane solutions (N44 Shmin oriented). For this reason we have computed for each breakout zone the difference between the local trend and the regional one; comparing these breakout rotations with the spikes or changing trend of logs we have identified possible fractures or faults at different depths. We have correlated

  1. From coherent to incoherent mismatched interfaces: A generalized continuum formulation of surface stresses

    Science.gov (United States)

    Dingreville, Rémi; Hallil, Abdelmalek; Berbenni, Stéphane

    2014-12-01

    The equilibrium of coherent and incoherent mismatched interfaces is reformulated in the context of continuum mechanics based on the Gibbs dividing surface concept. Two surface stresses are introduced: a coherent surface stress and an incoherent surface stress, as well as a transverse excess strain. The coherent surface stress and the transverse excess strain represent the thermodynamic driving forces of stretching the interface while the incoherent surface stress represents the driving force of stretching one crystal while holding the other fixed and thereby altering the structure of the interface. These three quantities fully characterize the elastic behavior of coherent and incoherent interfaces as a function of the in-plane strain, the transverse stress and the mismatch strain. The isotropic case is developed in detail and particular attention is paid to the case of interfacial thermo-elasticity. This exercise provides an insight on the physical significance of the interfacial elastic constants introduced in the formulation and illustrates the obvious coupling between the interface structure and its associated thermodynamics quantities. Finally, an example based on atomistic simulations of Cu/Cu2O interfaces is given to demonstrate the relevance of the generalized interfacial formulation and to emphasize the dependence of the interfacial thermodynamic quantities on the incoherency strain with an actual material system.

  2. Determination of global and local residual stresses in SOFC by X-ray diffraction

    International Nuclear Information System (INIS)

    Villanova, Julie; Sicardy, Olivier; Fortunier, Roland; Micha, Jean-Sebastien; Bleuet, Pierre

    2010-01-01

    Solid Oxide Fuel Cell (SOFC) is a high-performance electrochemical device for energy conversion. A single cell is composed of five layers made of different ceramic materials: anode support, anode functional layer, electrolyte, cathode functional layer and cathode. The mechanical integrity of the cell is a major issue during its lifetime, especially for the electrolyte layer. Damage of the cells is mainly due to the high operating temperature, the 'redox' behaviour of the anode and the brittleness of the involved materials. Since residual stresses are known to play a significant role in the damage evolution, it is important to determine them. For this purpose, residual stresses in an anode-supported planar SOFC were measured by X-ray diffraction. Firstly, macroscopic stresses in each phase of each layer were studied using the sin 2 ψ method on a laboratory X-ray goniometer at room temperature. This technique enables the calculation of residual stress of the material from the measurement of the crystal lattice deformation. The electrolyte has been found under bi-axial compressive stress of -920 MPa. Secondly, X-ray measurements controlling depth penetration were made in the electrolyte using grazing incidence method. The results show that the stress is not homogenous in the layer. The first five micrometers of the electrolyte have been found less constrained (-750 MPa) than the complete layer, suggesting a gradient of deformation in the electrolyte from the interface with the Anode Functional Layer to the free surface. Finally, local stress measurements were made on the electrolyte layer by X-ray synchrotron radiation that allows high accuracy measurement on the (sub-) micrometer scale. Polychromatic and monochromatic beams are used to determine the complete strain tensor from grain to grain in the electrolyte. First results confirm the macroscopic stress trend of the electrolyte. These X-ray techniques at different scales will contribute to a better understanding

  3. Local pH at the surface of hen egg white lysozyme

    Science.gov (United States)

    Otosu, Takuhiro; Kobayashi, Kaito; Yamaguchi, Shoichi

    2018-02-01

    The microenvironment at the surface of hen-egg-white lysozyme (HEWL) was examined by analyzing the change in pKa of fluorescein isothiocyanate (FITC) upon binding to the N-terminus of HEWL. The result showed that the local pH at the HEWL surface is higher than the bulk pH. Furthermore, the data showed that the difference between the local and bulk pH becomes larger with decreasing pH, suggesting HEWL repels more protons at lower pH. Because the local pH affects the protonation states of functional amino-acids at the protein surface, the results provide the fundamental insight into the microenvironment at the protein surface.

  4. Surface residual stress evaluation in double-electrode butt welded steel plates

    International Nuclear Information System (INIS)

    Estefen, S.F.; Gurova, T.; Castello, X.; Leontiev, A.

    2010-01-01

    Surface residual stress evaluation for double-electrode welding was studied. The stresses were monitored after each operational step: positioning, implementing of constraints, welding and constraints removal. The measurements were performed at the deposited metal, heat affected zone, base metal close to the weld joint and along the plate using the X-ray diffraction method. It was observed differences in the stress evaluations for double-electrode welding which resulted in lower bending distortions and higher values of surface residual stresses, compared with single-electrode welding. This behavior is associated with the stress distribution just after the welding processes in both heat affected zone and base metal close to the fillet for double-electrode welding. The main results from the laboratorial tests indicated lower values of the bending distortions for double-electrode welding compared with the single-electrode. In relation to the residual stress, the double-electrode welding generated, in general, higher stress values in both longitudinal and transversal directions.

  5. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Science.gov (United States)

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-05-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin-Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  6. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    International Nuclear Information System (INIS)

    Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad; Rafii-Tabar, Hashem

    2014-01-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin–Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  7. Nonlocal continuum-based modeling of breathing mode of nanowires including surface stress and surface inertia effects

    Energy Technology Data Exchange (ETDEWEB)

    Ghavanloo, Esmaeal, E-mail: ghavanloo@shirazu.ac.ir [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Fazelzadeh, S. Ahmad [School of Mechanical Engineering, Shiraz University, Shiraz 71963-16548 (Iran, Islamic Republic of); Rafii-Tabar, Hashem [Department of Medical Physics and Biomedical Engineering, Research Center for Medical Nanotechnology and Tissue Engineering, Shahid Beheshti University of Medical Sciences, Evin, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)

    2014-05-01

    Nonlocal and surface effects significantly influence the mechanical response of nanomaterials and nanostructures. In this work, the breathing mode of a circular nanowire is studied on the basis of the nonlocal continuum model. Both the surface elastic properties and surface inertia effect are included. Nanowires can be modeled as long cylindrical solid objects. The classical model is reformulated using the nonlocal differential constitutive relations of Eringen and Gurtin–Murdoch surface continuum elasticity formalism. A new frequency equation for the breathing mode of nanowires, including small scale effect, surface stress and surface inertia is presented by employing the Bessel functions. Numerical results are computed, and are compared to confirm the validity and accuracy of the proposed method. Furthermore, the model is used to elucidate the effect of nonlocal parameter, the surface stress, the surface inertia and the nanowire orientation on the breathing mode of several types of nanowires with size ranging from 0.5 to 4 nm. Our results reveal that the combined surface and small scale effects are significant for nanowires with diameter smaller than 4 nm.

  8. Effect of interface/surface stress on the elastic wave band structure of two-dimensional phononic crystals

    International Nuclear Information System (INIS)

    Liu, Wei; Chen, Jiwei; Liu, Yongquan; Su, Xianyue

    2012-01-01

    In the present Letter, the multiple scattering theory (MST) for calculating the elastic wave band structure of two-dimensional phononic crystals (PCs) is extended to include the interface/surface stress effect at the nanoscale. The interface/surface elasticity theory is employed to describe the nonclassical boundary conditions at the interface/surface and the elastic Mie scattering matrix embodying the interface/surface stress effect is derived. Using this extended MST, the authors investigate the interface/surface stress effect on the elastic wave band structure of two-dimensional PCs, which is demonstrated to be significant when the characteristic size reduces to nanometers. -- Highlights: ► Multiple scattering theory including the interface/surface stress effect. ► Interface/surface elasticity theory to describe the nonclassical boundary conditions. ► Elastic Mie scattering matrix embodying the interface/surface stress effect. ► Interface/surface stress effect would be significant at the nanoscale.

  9. SCC of 2304 Duplex Stainless Steel-Microstructure, Residual Stress and Surface Grinding Effects.

    Science.gov (United States)

    Zhou, Nian; Peng, Ru Lin; Schönning, Mikael; Pettersson, Rachel

    2017-02-23

    The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

  10. SCC of 2304 Duplex Stainless Steel—Microstructure, Residual Stress and Surface Grinding Effects

    Directory of Open Access Journals (Sweden)

    Nian Zhou

    2017-02-01

    Full Text Available The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

  11. SCC of 2304 Duplex Stainless Steel—Microstructure, Residual Stress and Surface Grinding Effects

    Science.gov (United States)

    Zhou, Nian; Peng, Ru Lin; Schönning, Mikael; Pettersson, Rachel

    2017-01-01

    The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental. PMID:28772582

  12. A Study on Effect of Local Wall Thinning in Carbon Steel Elbow Pipe on Elastic Stress Concentration

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Seo, Jae Seok

    2009-01-01

    Feeder pipes that connect the inlet and outlet headers to the reactor core in CANDU nuclear power plants are considered as safety Class 1 piping items. Therefore, fatigue of feeder pipes should be assessed at design stage in order to verify structural integrity during design lifetime. In accordance with the fatigue assessment result, cumulative usage factors of some feeder pipes have significant values. The feeder pipes made of SA-106 Grade B or C carbon steel have some elbows and bends. An active degradation mechanism for the carbon steel outlet feeder piping is local wall thinning due to flow-accelerated corrosion. Inspection results from plants and metallurgical examinations of removed feeders indicated the presence of localized thinning in the vicinity of the welds in the lower portion of outlet feeders, such as Grayloc hub-to-bend weld, Grayloc hub-to-elbow weld, elbow-to-elbow, and elbow-to-pipe weld. This local wall thinning can cause increase of peak stress due to stress concentration by notch effect. The increase of peak stress results in increase of cumulative usage factor. However, present fatigue assessment doesn't consider the stress concentration due to local wall-thinning. Therefore, it is necessary to assess the effect of local wall thinning on stress concentration. This study investigates the effect of local wall thinning geometry on stress concentration by performing finite element elastic stress analysis

  13. Cantilever surface stress sensors with single-crystalline silicon piezoresistors

    DEFF Research Database (Denmark)

    Rasmussen, Peter Andreas; Hansen, Ole; Boisen, Anja

    2005-01-01

    We present a cantilever with piezoresistive readout optimized for measuring the static deflection due to isotropic surface stress on the surface of the cantilever [Sens. Actuators B 79(2-3), 115 (2001)]. To our knowledge nobody has addressed the difference in physical regimes, and its influence o...

  14. A strategy for accommodating residual stresses in the assessment of repair weldments based upon measurement of near surface stresses

    International Nuclear Information System (INIS)

    Mcdonald, E.J.; Hallam, K.R.; Flewitt, P.E.J.

    2005-01-01

    On many occasions repairs are undertaken to ferritic steel weldments on plant either during construction or to remove service induced defects. These repaired weldments are subsequently put into service with or without a post-weld heat treatment. In either case, but particularly for the latter, there is a need to accommodate the associated residual stresses in structural integrity assessments such as those based upon the R6 failure avoidance procedure. Although in some circumstances the residual macro-stresses developed within weldments of components and structures can be calculated this is not so readily achieved in the case of residual stresses introduced by repair welds. There is a range of physical and mechanical techniques available to undertake the measurement of macro-residual stresses. Of these X-ray diffraction has the advantage that it is essentially non-destructive and offers the potential for evaluating stresses, which exist in the near surface layer. Although for many structural integrity assessments both the magnitude and distribution of residual stresses have to be accommodated it is not practical to make destructive measurements on weld repaired components and structures to establish the through section distribution of stresses. An approach is to derive a description of the appropriate macro-stresses by a combination of measurement and calculation on trial ferritic steel repair weldments. Surface measurements on the plant can then be made to establish the relationship between the repaired component or structure and the trial weld and thereby improve confidence in predicted stresses and their distribution from the near-surface measured values. Hence X-ray diffraction measurements at the near-surface of the plant weldment can be used to underwrite the quality of the repair by confirming the magnitude and distribution of residual stresses used for the integrity assessment to demonstrate continued safe operation

  15. Geometrical Considerations for Piezoresistive Microcantilever Response to Surface Stress during Chemical Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Loui, A; Goericke, F; Ratto, T; Lee, J; Hart, B; King, W

    2008-04-25

    We have designed, fabricated, and tested five piezoresistive cantilever configurations to investigate the effect of shape and piezoresistor placement on the sensitivity of microcantilevers under either point loading and surface stress loading. The experimental study reveals that: (1) high aspect ratio cantilevers that are much longer than they are wide are optimal for point-loading applications such as microscopy and force measurements; (2) low aspect ratio cantilevers that are short and wide are optimal for surface stress loading scenarios such as those that occur in biological and chemical sensor applications. The sensitivity data for both point loads and surface stress are consistent with previously developed finite-element models.

  16. Localization of optical excitations on random surfaces: SNOM studies

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Localization of optical excitations on nanostructured metal surfaces and fractal colloid silver aggregates are studied by using a scanning near-field optical microscope (SNOM). The SNOM images obtained in both configurations exhibit spatially localized (within 150 to 250 nm) light intensity...

  17. Modelling of surface stresses and fracturing during dyke emplacement: Application to the 2009 episode at Harrat Lunayyir, Saudi Arabia

    Science.gov (United States)

    Al Shehri, Azizah; Gudmundsson, Agust

    2018-05-01

    Correct interpretation of surface stresses and deformation or displacement during volcanotectonic episodes is of fundamental importance for hazard assessment and dyke-path forecasting. Here we present new general numerical models on the local stresses induced by arrested dykes. In the models, the crustal segments hosting the dyke vary greatly in mechanical properties, from uniform or non-layered (elastic half-spaces) to highly anisotropic (layers with strong contrast in Young's modulus). The shallow parts of active volcanoes and volcanic zones are normally highly anisotropic and some with open contacts. The numerical results show that, for a given surface deformation, non-layered (half-space) models underestimate the dyke overpressure/thickness needed and overestimate the likely depth to the tip of the dyke. Also, as the mechanical contrast between the layers increases, so does the stress dissipation and associated reduction in surface stresses (and associated fracturing). In the absence of open contacts, the distance between the two dyke-induced tensile and shear stress peaks (and fractures, if any) at the surface is roughly twice the depth to the tip of the dyke. The width of a graben, if it forms, should therefore be roughly twice the depth to the tip of the associated arrested dyke. When applied to the 2009 episode at Harrat Lunayyir, the main results are as follows. The entire 3-7 km wide fracture zone/graben formed during the episode is far too wide to have been generated by induced stresses of a single, arrested dyke. The eastern part of the zone/graben may have been generated by the inferred, arrested dyke, but the western zone primarily by regional extensional loading. The dyke tip was arrested at only a few hundred metres below the surface, the estimated thickness of the uppermost part of the dyke being between about 6 and 12 m. For the inferred dyke length (strike dimension) of about 14 km, this yields a dyke length/thickness ratio between 2400 and 1200

  18. Efficiency of local surface plasmon polariton excitation on ridges

    DEFF Research Database (Denmark)

    Radko, I.P.; Bozhevolnyi, S.I.; Brucoli, G.

    2008-01-01

    The issue of efficient local coupling of light into surface plasmon polariton (SPP) modes is an important concern in miniaturization of plasmonic components. Here we present experimental and numerical investigations of efficiency of local SPP excitation on gold ridges of rectangular profile...... positioned on a gold film. The excitation is accomplished by illuminating the metal surface normally with a focused laser beam. Wavelength dependence and dependence of the efficiency on geometrical parameters of ridges are examined. Using leakage radiation microscopy, the efficiency of ˜20% is demonstrated...

  19. Ab initio study of symmetrical tilt grain boundaries in bcc Fe: structural units, magnetic moments, interfacial bonding, local energy and local stress

    International Nuclear Information System (INIS)

    Bhattacharya, Somesh Kr; Tanaka, Shingo; Kohyama, Masanori; Shiihara, Yoshinori

    2013-01-01

    We present first-principle calculations on symmetric tilt grain boundaries (GBs) in bcc Fe. Using density functional theory (DFT), we studied the structural, electronic and magnetic properties of Σ3(111) and Σ11(332) GBs formed by rotation around the [110] axis. The optimized structures, GB energies and GB excess free volumes are consistent with previous DFT and classical simulation studies. The GB configurations can be interpreted by the structural unit model as given by Nakashima and Takeuchi (2000 ISIJ 86 357). Both the GBs are composed of similar structural units of three- and five-membered rings with different densities at the interface according to the rotation angle. The interface atoms with larger atomic volumes reveal higher magnetic moments than the bulk value, while the interface atoms with shorter bond lengths have reduced magnetic moments in each GB. The charge density and local density of states reveal that the interface bonds with short bond lengths have more covalent nature, where minority-spin electrons play a dominant role as the typical nature of ferromagnetic Fe. In order to understand the structural stability of these GBs, we calculated the local energy and local stress for each atomic region using the scheme of Shiihara et al (2010 Phys. Rev. B 81 075441). In each GB, the interface atoms with larger atomic volumes and enhanced magnetic moments reveal larger local energy increase and tensile stress. The interface atoms constituting more covalent-like bonds with reduced magnetic moments have lower local energy increase, contributing to the stabilization, while compressive stress is generated at these atoms. The relative stability between the two GBs can be understood by the local energies at the structural units. The local energy and local stress analysis is a powerful tool to investigate the structural properties of GBs based on the behavior of valence electrons. (paper)

  20. Residual stress improved by water jet peening using cavitation for small-diameter pipe inner surfaces

    International Nuclear Information System (INIS)

    Yasuo, Nakamura; Toshizo, Ohya; Koji, Okimura

    2001-01-01

    As one of degradation conditions on components used in water, the overlapping effect of environment, material and stress might cause stress corrosion cracking (SCC). Especially, for the tensile residual stress produced by welding, it is particularly effective to reduce the tensile residual stress on the material surface to prevent SCC. In this paper, the residual stress improvement method using cavitation impact generated by a water jet, called Water Jet Peening (WJP), has been developed as the maintenance technology for the inner surfaces of small-diameter Ni-Cr-Fe alloy (Alloy 600) pipes. As the results, by WJP for the inner surface of Alloy 600 pipe (inner diameter; approximately 10-15 mm), we confirmed that the compressive stress generated within the range from the surface to the inner part about 0.5 mm deep and took a maximum value about 350 MPa on the surface. (author)

  1. High-resolution biosensor based on localized surface plasmons

    Czech Academy of Sciences Publication Activity Database

    Piliarik, Marek; Šípová, Hana; Kvasnička, Pavel; Galler, N.; Krenn, J. R.; Homola, Jiří

    2012-01-01

    Roč. 20, č. 1 (2012), s. 672-680 ISSN 1094-4087 R&D Projects: GA AV ČR KAN200670701; GA MŠk OC09058 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical biosenzor * surface plasmon resonance * localized surface plasmon Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.546, year: 2012

  2. AN INVESTIGATION OF LOCAL EFFECTS ON SURFACE WARMING WITH GEOGRAPHICALLY WEIGHTED REGRESSION (GWR

    Directory of Open Access Journals (Sweden)

    Y. Xue

    2012-07-01

    Full Text Available Urban warming is sensitive to the nature (thermal properties, including albedo, water content, heat capacity and thermal conductivity and the placement (surface geometry or urban topography of urban surface. In the literature the spatial dependence and heterogeneity of urban thermal landscape is widely observed based on thermal infrared remote sensing within the urban environment. Urban surface warming is conceived as a big contribution to urban warming, the study of urban surface warming possesses significant meaning for probing into the problem of urban warming.The urban thermal landscape study takes advantage of the continuous surface derived from thermal infrared remote sensing at the landscape scale, the detailed variation of local surface temperature can be measured and analyzed through the systematic investigation. At the same time urban environmental factors can be quantified with remote sensing and GIS techniques. This enables a systematic investigation of urban thermal landscape with a link to be established between local environmental setting and surface temperature variation. The goal of this research is utilizing Geographically Weighted Regression (GWR to analyze the spatial relationship between urban form and surface temperature variation in order to clarify the local effects on surface warming, moreover to reveal the possible dynamics in the local influences of environmental indicators on the variation of local surface temperature across space and time. In this research, GWR analysis proved that the spatial variation in relationships between environmental setting and surface temperature was significant with Monte Carlo significance test and distinctive in day-night change. Comparatively, GWR facilitated the site specific investigation based on local statistical technique. The inference based on GWR model provided enriched information regarding the spatial variation of local environment effect on surface temperature variation which

  3. The correlation of local deformation and stress-assisted local phase transformations in MMC foams

    Energy Technology Data Exchange (ETDEWEB)

    Berek, H., E-mail: harry.berek@ikgb.tu-freiberg.de [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Ballaschk, U.; Aneziris, C.G. [TU Bergakademie Freiberg, Agricolastraße 17, D-09599 Freiberg (Germany); Losch, K.; Schladitz, K. [Fraunhofer ITWM, Fraunhoferplatz 1, D-67663 Kaiserslautern (Germany)

    2015-09-15

    Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated.

  4. The correlation of local deformation and stress-assisted local phase transformations in MMC foams

    International Nuclear Information System (INIS)

    Berek, H.; Ballaschk, U.; Aneziris, C.G.; Losch, K.; Schladitz, K.

    2015-01-01

    Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they can trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated

  5. Exposure to Forced Swim Stress Alters Local Circuit Activity and Plasticity in the Dentate Gyrus of the Hippocampus

    Directory of Open Access Journals (Sweden)

    Mouna Maroun

    2008-02-01

    Full Text Available Studies have shown that, depending on its severity and context, stress can affect neural plasticity. Most related studies focused on synaptic plasticity and long-term potentiation (LTP of principle cells. However, evidence suggests that following high-frequency stimulation, which induces LTP in principal cells, modifications also take place at the level of complex interactions with interneurons within the dentate gyrus, that is, at the local circuit level. So far, the possible effects of stress on local circuit activity and plasticity were not studied. Therefore, we set out to examine the possible alterations in local circuit activity and plasticity following exposure to stress. Local circuit activity and plasticity were measured by using frequency dependant inhibition (FDI and commissural modulation protocols following exposure to a 15 minute-forced swim trial. Exposure to stress did not alter FDI. The application of theta-burst stimulation (TBS reduced FDI in both control and stressed rats, but this type of plasticity was greater in stressed rats. Commissural-induced inhibition was significantly higher in stressed rats both before and after applying theta-burst stimulation. These findings indicate that the exposure to acute stress affects aspects of local circuit activity and plasticity in the dentate gyrus. It is possible that these alterations underlie some of the behavioral consequences of the stress experience.

  6. Exposure to Forced Swim Stress Alters Local Circuit Activity and Plasticity in the Dentate Gyrus of the Hippocampus

    Science.gov (United States)

    Yarom, Orli; Maroun, Mouna; Richter-Levin, Gal

    2008-01-01

    Studies have shown that, depending on its severity and context, stress can affect neural plasticity. Most related studies focused on synaptic plasticity and long-term potentiation (LTP) of principle cells. However, evidence suggests that following high-frequency stimulation, which induces LTP in principal cells, modifications also take place at the level of complex interactions with interneurons within the dentate gyrus, that is, at the local circuit level. So far, the possible effects of stress on local circuit activity and plasticity were not studied. Therefore, we set out to examine the possible alterations in local circuit activity and plasticity following exposure to stress. Local circuit activity and plasticity were measured by using frequency dependant inhibition (FDI) and commissural modulation protocols following exposure to a 15 minute-forced swim trial. Exposure to stress did not alter FDI. The application of theta-burst stimulation (TBS) reduced FDI in both control and stressed rats, but this type of plasticity was greater in stressed rats. Commissural-induced inhibition was significantly higher in stressed rats both before and after applying theta-burst stimulation. These findings indicate that the exposure to acute stress affects aspects of local circuit activity and plasticity in the dentate gyrus. It is possible that these alterations underlie some of the behavioral consequences of the stress experience. PMID:18301720

  7. Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

    Science.gov (United States)

    Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

    2009-05-01

    Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

  8. Patterning pentacene surfaces by local oxidation nanolithography

    International Nuclear Information System (INIS)

    Losilla, N.S.; Martinez, J.; Bystrenova, E.; Greco, P.; Biscarini, F.; Garcia, R.

    2010-01-01

    Sequential and parallel local oxidation nanolithographies have been applied to pattern pentacene samples by creating a variety of nanostructures. The sequential local oxidation process is performed with an atomic force microscope and requires the application of a sequence of voltage pulses of 36 V for 1 ms. The parallel local oxidation process is performed by using a conductive and patterned stamp. Then, a voltage pulse is applied between the stamp and the pentacene surface. Patterns formed by arrays of parallel lines covering 1 mm 2 regions and with a periodicity of less than 1 μm have been generated in a few seconds. We also show that the patterns can be used as templates for the deposition of antibodies.

  9. Stress localization in BCC polycrystals and its implications on the probability of brittle fracture

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Ludovic [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France); Gelebart, Lionel, E-mail: lionel.gelebart@cea.fr [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France); Dakhlaoui, Rim; Marini, Bernard [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France)

    2011-07-15

    Highlights: {yields} Intergranular stress distributions in a bainitic steel. {yields} Comparison of local mean stress field with neutron diffraction results. {yields} Application of the local stress distribution in a brittle fracture model. - Abstract: The evaluation of the reliability of pressure vessels in nuclear plants relies on the evaluation of failure probability models. Micromechanical approaches are of great interest to refine their description, to better understand the underlying mechanisms leading to failure, and finally to improve the prediction of these models. The main purpose of this paper is to introduce the stress heterogeneities arising within the polycrystal in a probabilistic modeling of brittle fracture. Stress heterogeneities are evaluated from Finite-Element simulations performed on a large number of Statistical Volume Elements. Results are validated both on the measured averaged behavior and on the averaged stresses measured by neutron diffraction in five specific orientations. A probabilistic model for brittle fracture is then presented accounting for the carbide distribution and the stress distribution evaluated previously inside an elementary volume V{sub 0}. Results are compared to a 'Beremin type' approach, assuming a homogeneous stress state inside V{sub 0}.

  10. Stress intensity factor analyses of surface cracks in three-dimensional structures

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Shibata, Katsuyuki; Watanabe, Takayuki; Tagata, Kazunori.

    1983-11-01

    The stress intensity factor analyses of surface cracks in various three-dimensional structures were performed using the finite element computer program EPAS-J1. The results obtained by EPAS-J1 were compared with other finite element solutions or results obtained by the simplified estimation methods. Among the simplified estimation methods, the equations proposed by Newman and Raju give the distributions of the stress intensity factor along a crack front, which were compared with the result obtained by EPAS-J1. It was confirmed by comparing the results that EPAS-J1 gives reasonable stress intensity factors of surface cracks in three-dimensional structures. (author)

  11. Local-Scale Simulations of Nucleate Boiling on Micrometer-Featured Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sitaraman, Hariswaran [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dede, Ercan M. [Toyota Research Institute of North America; Joshi, Shailesh N. [Toyota Research Institute of North America; Zhou, Feng [Toyota Research Institute of North America

    2017-07-12

    A high-fidelity computational fluid dynamics (CFD)-based model for bubble nucleation of the refrigerant HFE7100 on micrometer-featured surfaces is presented in this work. The single-fluid incompressible Navier-Stokes equations, along with energy transport and natural convection effects are solved on a featured surface resolved grid. An a priori cavity detection method is employed to convert raw profilometer data of a surface into well-defined cavities. The cavity information and surface morphology are represented in the CFD model by geometric mesh deformations. Surface morphology is observed to initiate buoyancy-driven convection in the liquid phase, which in turn results in faster nucleation of cavities. Simulations pertaining to a generic rough surface show a trend where smaller size cavities nucleate with higher wall superheat. This local-scale model will serve as a self-consistent connection to larger device scale continuum models where local feature representation is not possible.

  12. A micromachined surface stress sensor with electronic readout

    NARCIS (Netherlands)

    Carlen, Edwin; Weinberg, M.S.; Zapata, A.M.; Borenstein, J.T.

    2008-01-01

    A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high frequency carrier signal, and the output signal is synchronously demodulated and

  13. Application of laser interferometry for assessment of surface residual stress by determination of stress-free state

    International Nuclear Information System (INIS)

    Kim, Dong Won; Kwon, Dong Il; Lee, Nak Kyu; Choi, Tae Hoon; Na, Kyoung Hoan

    2003-01-01

    The total relaxed stress in annealing and the thermal strain/stress were obtained from the identification of the residual stress-free state using Electronic Speckle Pattern Interferometry (ESPI). The residual stress fields in case of both single and film/substrate systems were modeled using the thermo-elastic theory and the relationship between relaxed stresses and displacements. We mapped the surface residual stress fields on the indented bulk Cu and the 0.5 μm Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -1.7 GPa to 700 MPa and -800 GPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the X-Ray Diffractometer (XRD) for the verification of above residual stress results by ESPI

  14. Residual stresses relaxation in surface-hardened half-space under creep conditions

    Directory of Open Access Journals (Sweden)

    Vladimir P. Radchenko

    2015-09-01

    Full Text Available We developed the method for solving the problem of residual stresses relaxation in surface-hardened layer of half-space under creep conditions. At the first stage we made the reconstruction of stress-strain state in half-space after plastic surface hardening procedure based on partial information about distribution for one residual stress tensor component experimentally detected. At the second stage using a numerical method we solve the problem of relaxation of self-balanced residual stresses under creep conditions. To solve this problem we introduce the following Cartesian system: x0y plane is aligned with hardened surface of half-space and 0z axis is directed to the depth of hardened layer. We also introduce the hypotheses of plane sections parallel to x0z and y0z planes. Detailed analysis of the problem has been done. Comparison of the calculated data with the corresponding test data was made for plane specimens (rectangular parallelepipeds made of EP742 alloy during T=650°C after the ultrasonic hardening with four hardening modes. We use half-space to model these specimens because penetration's depth of residual stresses is less than specimen general size in two digit exponent. There is enough correspondence of experimental and calculated data. It is shown that there is a decay (in modulus of pressing residual stresses under creep in 1.4–1.6 times.

  15. Surface growth kinematics via local curve evolution

    KAUST Repository

    Moulton, Derek E.

    2012-11-18

    A mathematical framework is developed to model the kinematics of surface growth for objects that can be generated by evolving a curve in space, such as seashells and horns. Growth is dictated by a growth velocity vector field defined at every point on a generating curve. A local orthonormal basis is attached to each point of the generating curve and the velocity field is given in terms of the local coordinate directions, leading to a fully local and elegant mathematical structure. Several examples of increasing complexity are provided, and we demonstrate how biologically relevant structures such as logarithmic shells and horns emerge as analytical solutions of the kinematics equations with a small number of parameters that can be linked to the underlying growth process. Direct access to cell tracks and local orientation enables for connections to be made to the underlying growth process. © 2012 Springer-Verlag Berlin Heidelberg.

  16. Localized deformation of zirconium-liner tube

    International Nuclear Information System (INIS)

    Nagase, Fumihisa; Uchida, Masaaki

    1988-03-01

    Zirconium-liner tube has come to be used in BWR. Zirconium liner mitigates the localized stress produced by the pellet-cladding interaction (PCI). In this study, simulating the ridging, stresses were applied to the inner surfaces of zirconium-liner tubes and Zircaloy-2 tubes, and, to investigate the mechanism and the extent of the effect, the behavior of zirconium liner was examined. As the result of examination, stress was concentrated especially at the edge of the deformed region, where zirconium liner was highly deformed. Even after high stress was applied, the deformation of Zircaloy part was small, since almost the concentrated stress was mitigated by the deformation of zirconium liner. In addition, stress and strain distributions in the cross section of specimen were calculated with a computer code FEMAXI-III. The results also showed that zirconium liner mitigated the localized stress in Zircaloy, although the affected zone was restricted to the region near the boundary between zirconium liner and Zircaloy. (author)

  17. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  18. Cellular stress stimulates nuclear localization signal (NLS) independent nuclear transport of MRJ

    Science.gov (United States)

    Andrews, Joel F.; Sykora, Landon J.; Barik-Letostak, Tiasha; Menezes, Mitchell E.; Mitra, Aparna; Barik, Sailen; Shevde, Lalita A.; Samant, Rajeev S.

    2012-01-01

    HSP40 family member MRJ (DNAJB6) has been in the spot light for its relevance to Huntington’s, Parkinson’s diseases, limb-girdle muscular dystrophy, placental development, neural stem cells, cell cycle and malignancies such as breast cancer and melanoma. This gene has two spliced variants coding for 2 distinct proteins with significant homology. However, MRJ(L) (large variant) is predominantly localized to the nucleus whereas MRJ(S) (small variant) is predominantly cytoplasmic. Interestingly MRJ(S) translocates to the nucleus in response to heat shock. The classical heat shock proteins respond to crises (stress) by increasing the number of molecules, usually by transcriptional up-regulation. Our studies imply that a quick increase in the molar concentration of MRJ in the nuclear compartment is a novel method by which MRJ responds to stress. We found that MRJ(S) shows NLS (nuclear localization signal) independent nuclear localization in response to heat shock and hypoxia. The specificity of this response is realized due to lack of such response by MRJ(S) when challenged by other stressors, such as some cytokines or UV light. Deletion analysis has allowed us to narrow down on a 20 amino acid stretch at the C-terminal region of MRJ(S) as a potential stress sensing region. Functional studies indicated that constitutive nuclear localization of MRJ(S) promoted attributes of malignancy such as proliferation and invasiveness overall indicating distinct phenotypic characteristics of nuclear MRJ(S). PMID:22504047

  19. Cellular stress stimulates nuclear localization signal (NLS) independent nuclear transport of MRJ

    International Nuclear Information System (INIS)

    Andrews, Joel F.; Sykora, Landon J.; Barik Letostak, Tiasha; Menezes, Mitchell E.; Mitra, Aparna; Barik, Sailen; Shevde, Lalita A.; Samant, Rajeev S.

    2012-01-01

    HSP40 family member MRJ (DNAJB6) has been in the spot light for its relevance to Huntington's, Parkinson's diseases, limb-girdle muscular dystrophy, placental development, neural stem cells, cell cycle and malignancies such as breast cancer and melanoma. This gene has two spliced variants coding for 2 distinct proteins with significant homology. However, MRJ(L) (large variant) is predominantly localized to the nucleus whereas MRJ(S) (small variant) is predominantly cytoplasmic. Interestingly MRJ(S) translocates to the nucleus in response to heat shock. The classical heat shock proteins respond to crises (stress) by increasing the number of molecules, usually by transcriptional up-regulation. Our studies imply that a quick increase in the molar concentration of MRJ in the nuclear compartment is a novel method by which MRJ responds to stress. We found that MRJ(S) shows NLS (nuclear localization signal) independent nuclear localization in response to heat shock and hypoxia. The specificity of this response is realized due to lack of such response by MRJ(S) when challenged by other stressors, such as some cytokines or UV light. Deletion analysis has allowed us to narrow down on a 20 amino acid stretch at the C-terminal region of MRJ(S) as a potential stress sensing region. Functional studies indicated that constitutive nuclear localization of MRJ(S) promoted attributes of malignancy such as proliferation and invasiveness overall indicating distinct phenotypic characteristics of nuclear MRJ(S).

  20. Cellular stress stimulates nuclear localization signal (NLS) independent nuclear transport of MRJ

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Joel F.; Sykora, Landon J.; Barik Letostak, Tiasha; Menezes, Mitchell E.; Mitra, Aparna [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States); Barik, Sailen [Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Science, Cleveland State University, Cleveland, OH (United States); Shevde, Lalita A. [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States); Samant, Rajeev S., E-mail: rsamant@usouthal.edu [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States)

    2012-06-10

    HSP40 family member MRJ (DNAJB6) has been in the spot light for its relevance to Huntington's, Parkinson's diseases, limb-girdle muscular dystrophy, placental development, neural stem cells, cell cycle and malignancies such as breast cancer and melanoma. This gene has two spliced variants coding for 2 distinct proteins with significant homology. However, MRJ(L) (large variant) is predominantly localized to the nucleus whereas MRJ(S) (small variant) is predominantly cytoplasmic. Interestingly MRJ(S) translocates to the nucleus in response to heat shock. The classical heat shock proteins respond to crises (stress) by increasing the number of molecules, usually by transcriptional up-regulation. Our studies imply that a quick increase in the molar concentration of MRJ in the nuclear compartment is a novel method by which MRJ responds to stress. We found that MRJ(S) shows NLS (nuclear localization signal) independent nuclear localization in response to heat shock and hypoxia. The specificity of this response is realized due to lack of such response by MRJ(S) when challenged by other stressors, such as some cytokines or UV light. Deletion analysis has allowed us to narrow down on a 20 amino acid stretch at the C-terminal region of MRJ(S) as a potential stress sensing region. Functional studies indicated that constitutive nuclear localization of MRJ(S) promoted attributes of malignancy such as proliferation and invasiveness overall indicating distinct phenotypic characteristics of nuclear MRJ(S).

  1. Cellular stress stimulates nuclear localization signal (NLS) independent nuclear transport of MRJ

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Joel F.; Sykora, Landon J.; Barik Letostak, Tiasha; Menezes, Mitchell E.; Mitra, Aparna [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States); Barik, Sailen [Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Science, Cleveland State University, Cleveland, OH (United States); Shevde, Lalita A. [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States); Samant, Rajeev S., E-mail: rsamant@usouthal.edu [Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL (United States)

    2012-06-10

    HSP40 family member MRJ (DNAJB6) has been in the spot light for its relevance to Huntington's, Parkinson's diseases, limb-girdle muscular dystrophy, placental development, neural stem cells, cell cycle and malignancies such as breast cancer and melanoma. This gene has two spliced variants coding for 2 distinct proteins with significant homology. However, MRJ(L) (large variant) is predominantly localized to the nucleus whereas MRJ(S) (small variant) is predominantly cytoplasmic. Interestingly MRJ(S) translocates to the nucleus in response to heat shock. The classical heat shock proteins respond to crises (stress) by increasing the number of molecules, usually by transcriptional up-regulation. Our studies imply that a quick increase in the molar concentration of MRJ in the nuclear compartment is a novel method by which MRJ responds to stress. We found that MRJ(S) shows NLS (nuclear localization signal) independent nuclear localization in response to heat shock and hypoxia. The specificity of this response is realized due to lack of such response by MRJ(S) when challenged by other stressors, such as some cytokines or UV light. Deletion analysis has allowed us to narrow down on a 20 amino acid stretch at the C-terminal region of MRJ(S) as a potential stress sensing region. Functional studies indicated that constitutive nuclear localization of MRJ(S) promoted attributes of malignancy such as proliferation and invasiveness overall indicating distinct phenotypic characteristics of nuclear MRJ(S).

  2. A phenomenological model for iodine stress corrosion cracking of zircaloy

    International Nuclear Information System (INIS)

    Miller, A.K.; Tasooji, A.

    1981-01-01

    To predict the response of Zircaloy tubing in iodine environments under conditions where either crack initiation or crack propagation predominates, a unified model of the SCC process has been developed based on the local conditions (the local stress, local strain, and local iodine concentration) within a small volume of material at the cladding inner surface or the crack tip. The methodology used permits computation of these values from simple equations. A nonuniform distribution of local stress and strain results once a crack has initiated. The local stress can be increased due to plastic constraint and triaxiality at the crack tip. Iodine penetration is assumed to be a surface diffusion-controlled process. Experimental data are used to derive criteria for intergranular failure, transgranular failure, and ductile rupture in terms of the local conditions. The same failure criteria are used for both crack initiation and crack propagation. Irradiation effects are included in the model by changing the value of constants in the equation governing iodine penetration and by changing the values used to represent the mechanical properties of the Zircaloy. (orig./HP)

  3. Surface displacements and pillar stresses associated with nuclear waste disposal in salt

    International Nuclear Information System (INIS)

    Hardy, M.P.; St John, C.M.

    1977-01-01

    A numerical model for regional analysis of stresses and displacement, resulting from heat generating waste placement in underground salt excavations, is presented. The model, which is an extension of that described by McClain and Starfield (1971), is based upon the displacement discontinuity method of stress analysis. It incorporates an empirical characterization of creep behavior of material on the excavation horizon and accounts for thermally induced stresses and displacements. The versatility of this approach is illustrated by the results of three relatively short simulations of test scale disposal facilities at shallow and greater depths. In addition, a three-dimensional code was used to evaluate the surface displacement history for a full-scale repository. This latter code, a thermoelastic analysis, gives an upper bound for the surface movements. It is concluded that the pillar stresses are the result of a complex non-linear interaction of many variables, and the maximum pillar stress can reach several multiples of the tributory-area pillar stress

  4. Global gradients of coral exposure to environmental stresses and implications for local management.

    Directory of Open Access Journals (Sweden)

    Joseph Maina

    Full Text Available BACKGROUND: The decline of coral reefs globally underscores the need for a spatial assessment of their exposure to multiple environmental stressors to estimate vulnerability and evaluate potential counter-measures. METHODOLOGY/PRINCIPAL FINDINGS: This study combined global spatial gradients of coral exposure to radiation stress factors (temperature, UV light and doldrums, stress-reinforcing factors (sedimentation and eutrophication, and stress-reducing factors (temperature variability and tidal amplitude to produce a global map of coral exposure and identify areas where exposure depends on factors that can be locally managed. A systems analytical approach was used to define interactions between radiation stress variables, stress reinforcing variables and stress reducing variables. Fuzzy logic and spatial ordinations were employed to quantify coral exposure to these stressors. Globally, corals are exposed to radiation and reinforcing stress, albeit with high spatial variability within regions. Based on ordination of exposure grades, regions group into two clusters. The first cluster was composed of severely exposed regions with high radiation and low reducing stress scores (South East Asia, Micronesia, Eastern Pacific and the central Indian Ocean or alternatively high reinforcing stress scores (the Middle East and the Western Australia. The second cluster was composed of moderately to highly exposed regions with moderate to high scores in both radiation and reducing factors (Caribbean, Great Barrier Reef (GBR, Central Pacific, Polynesia and the western Indian Ocean where the GBR was strongly associated with reinforcing stress. CONCLUSIONS/SIGNIFICANCE: Despite radiation stress being the most dominant stressor, the exposure of coral reefs could be reduced by locally managing chronic human impacts that act to reinforce radiation stress. Future research and management efforts should focus on incorporating the factors that mitigate the effect of

  5. Thermal Stress of Surface of Mold Cavities and Parting Line of Silicone Molds

    Directory of Open Access Journals (Sweden)

    Bajčičák Martin

    2014-06-01

    Full Text Available The paper is focused on the study of thermal stress of surface of mold cavities and parting line of silicone molds after pouring. The silicone mold White SD - THT was thermally stressed by pouring of ZnAl4Cu3 zinc alloy with pouring cycle 20, 30 and 40 seconds. The most thermally stressed part of surface at each pouring cycle is gating system and mold cavities. It could be further concluded that linear increase of the pouring cycle time leads to the exponential increasing of the maximum temperature of mold surface after its cooling. The elongated pouring cycle increases the temperature accumulated on the surface of cavities and the ability of silicone mold to conduct the heat on its surface decreases, because the low thermal conductivity of silicone molds enables the conduction of larger amount of heat into ambient environment.

  6. Implied and Local Volatility Surfaces for South African Index and Foreign Exchange Options

    Directory of Open Access Journals (Sweden)

    Antonie Kotzé

    2015-01-01

    Full Text Available Certain exotic options cannot be valued using closed-form solutions or even by numerical methods assuming constant volatility. Many exotics are priced in a local volatility framework. Pricing under local volatility has become a field of extensive research in finance, and various models are proposed in order to overcome the shortcomings of the Black-Scholes model that assumes a constant volatility. The Johannesburg Stock Exchange (JSE lists exotic options on its Can-Do platform. Most exotic options listed on the JSE’s derivative exchanges are valued by local volatility models. These models needs a local volatility surface. Dupire derived a mapping from implied volatilities to local volatilities. The JSE uses this mapping in generating the relevant local volatility surfaces and further uses Monte Carlo and Finite Difference methods when pricing exotic options. In this document we discuss various practical issues that influence the successful construction of implied and local volatility surfaces such that pricing engines can be implemented successfully. We focus on arbitrage-free conditions and the choice of calibrating functionals. We illustrate our methodologies by studying the implied and local volatility surfaces of South African equity index and foreign exchange options.

  7. Surface stress-induced change in overall elastic behavior and self-bending of ultrathin cantilever plates

    NARCIS (Netherlands)

    Sadeghian, H.; Goosen, J.F.L.; Bossche, A.; Van Keulen, F.

    2009-01-01

    In this letter, the dominant role of surface stress and surface elasticity on the overall elastic behavior of ultrathin cantilever plates is studied. A general framework based on two-dimensional plane-stress analysis is presented. Because of either surface reconstruction or molecular adsorption,

  8. Damage approach: A new method for topology optimization with local stress constraints

    DEFF Research Database (Denmark)

    Verbart, Alexander; Langelaar, Matthijs; van Keulen, Fred

    2016-01-01

    In this paper, we propose a new method for topology optimization with local stress constraints. In this method, material in which a stress constraint is violated is considered as damaged. Since damaged material will contribute less to the overall performance of the structure, the optimizer...... will promote a design with a minimal amount of damaged material. We tested the method on several benchmark problems, and the results show that the method is a viable alternative for conventional stress-based approaches based on constraint relaxation followed by constraint aggregation....

  9. Binding Ligand Prediction for Proteins Using Partial Matching of Local Surface Patches

    Directory of Open Access Journals (Sweden)

    Lee Sael

    2010-12-01

    Full Text Available Functional elucidation of uncharacterized protein structures is an important task in bioinformatics. We report our new approach for structure-based function prediction which captures local surface features of ligand binding pockets. Function of proteins, specifically, binding ligands of proteins, can be predicted by finding similar local surface regions of known proteins. To enable partial comparison of binding sites in proteins, a weighted bipartite matching algorithm is used to match pairs of surface patches. The surface patches are encoded with the 3D Zernike descriptors. Unlike the existing methods which compare global characteristics of the protein fold or the global pocket shape, the local surface patch method can find functional similarity between non-homologous proteins and binding pockets for flexible ligand molecules. The proposed method improves prediction results over global pocket shape-based method which was previously developed by our group.

  10. Binding ligand prediction for proteins using partial matching of local surface patches.

    Science.gov (United States)

    Sael, Lee; Kihara, Daisuke

    2010-01-01

    Functional elucidation of uncharacterized protein structures is an important task in bioinformatics. We report our new approach for structure-based function prediction which captures local surface features of ligand binding pockets. Function of proteins, specifically, binding ligands of proteins, can be predicted by finding similar local surface regions of known proteins. To enable partial comparison of binding sites in proteins, a weighted bipartite matching algorithm is used to match pairs of surface patches. The surface patches are encoded with the 3D Zernike descriptors. Unlike the existing methods which compare global characteristics of the protein fold or the global pocket shape, the local surface patch method can find functional similarity between non-homologous proteins and binding pockets for flexible ligand molecules. The proposed method improves prediction results over global pocket shape-based method which was previously developed by our group.

  11. Allowing for surface preparation in stress corrosion cracking modelling

    International Nuclear Information System (INIS)

    Berge, P.; Buisine, D.; Gelpi, A.

    1997-01-01

    When a 600 alloy component is significantly deformed during installation, by welding, rolling, bending, its stress corrosion cracking in Pressurized Water Nuclear Reactor's primary coolant, is significantly changed by the initial surface treatment. Therefore, the crack initiated time may be reduced by several orders of magnitude for certain surfaces preparations. Allowing for cold working of the surface, for which modelling is proposed, depends less on the degree of cold work then on the depths of the hardened layers. Honing hardens the metal over depths of about one micron for vessel head penetrations, for example, and has little influence on subsequent behaviour after the part deforms. On the other hand, coarser turning treatment produces cold worked layers which can reach several tens of microns and can very significantly reduce the initiation time compared to fine honing. So evaluation after depths of hardening is vital on test pieces for interpreting laboratory results as well as on service components for estimating their service life. Suppression by mechanical or chemical treatment of these layers, after deformation, seems to be the most appropriate solution for reducing over-stressing connected with surface treatment carried out before deformation. (author)

  12. Prediction method of long-term reliability in improving residual stresses by means of surface finishing

    International Nuclear Information System (INIS)

    Sera, Takehiko; Hirano, Shinro; Chigusa, Naoki; Okano, Shigetaka; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi

    2012-01-01

    Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by accelerated test. However, the effectiveness of stress improvement by surface treatment is limited to thin layers and the effect of complicated residual stress distribution in the weld metal beneath the surface is not strictly taken into account for long-term stability. This paper, therefore, describes the accelerated tests, which confirmed that the long-term stability of the layer subjected to buffing treatment was equal to that subjected to WJP. The long-term reliability of very thin stress improved layer was also confirmed through a trial evaluation by thermal elastic-plastic creep analysis, even if the effect of complicated residual stress distribution in the weld metal was excessively taken into account. Considering the above findings, an approach is proposed for constructing the prediction method of the long-term reliability of stress improvement by surface finishing. (author)

  13. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Roudbari, M.A. [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of)

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler–Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  14. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    International Nuclear Information System (INIS)

    Ghorbanpour Arani, A.; Roudbari, M.A.

    2014-01-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler–Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics

  15. Theoretical study of the localization of excess electrons at the surface of ice

    International Nuclear Information System (INIS)

    Hermann, A; Schwerdtfeger, P; Schmidt, W G

    2008-01-01

    The localization of excess electrons at the basal plane surface of hexagonal ice Ih is investigated theoretically, combining density functional theory (DFT) with a partial self-interaction correction (SIC) scheme, to account for spurious self-interaction effects that artificially delocalize the excess electrons. Starting from energetically favored surface geometries, we find strong localization of excess electrons at surface dangling bonds, in particular for surface adsorbed water monomers and dimers

  16. Surface roughness effects on plasma near a divertor plate and local impact angle

    Directory of Open Access Journals (Sweden)

    Wanpeng Hu

    2017-08-01

    Full Text Available The impact of rough surface topography on the electric potential and electric field is generally neglected due to the small scale of surface roughness compared to the width of the plasma sheath. However, the distributions of the electric potential and field on rough surfaces are expected to influence the characteristics of edge plasma and the local impact angle. The distributions of plasma sheath and local impact angle on rough surfaces are investigated by a two dimension-in-space and three dimension-in-velocity (2d3v Particle-In-Cell (PIC code. The influences of the plasma temperature andsurface morphology on the plasma sheath, local impact angle and resulting physical sputtering yield on rough surfaces are investigated.

  17. Local-Scale Simulations of Nucleate Boiling on Micrometer Featured Surfaces: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sitaraman, Hariswaran [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dede, Ercan M. [Toyota Research Institute of North America; Joshi, Shailesh N. [Toyota Research Institute of North America; Zhou, Feng [Toyota Research Institute of North America

    2017-08-03

    A high-fidelity computational fluid dynamics (CFD)-based model for bubble nucleation of the refrigerant HFE7100 on micrometer-featured surfaces is presented in this work. The single-fluid incompressible Navier-Stokes equations, along with energy transport and natural convection effects are solved on a featured surface resolved grid. An a priori cavity detection method is employed to convert raw profilometer data of a surface into well-defined cavities. The cavity information and surface morphology are represented in the CFD model by geometric mesh deformations. Surface morphology is observed to initiate buoyancy-driven convection in the liquid phase, which in turn results in faster nucleation of cavities. Simulations pertaining to a generic rough surface show a trend where smaller size cavities nucleate with higher wall superheat. This local-scale model will serve as a self-consistent connection to larger device scale continuum models where local feature representation is not possible.

  18. Calculation of Local Stress and Fatigue Resistance due to Thermal Stratification on Pressurized Surge Line Pipe

    Science.gov (United States)

    Bandriyana, B.; Utaja

    2010-06-01

    Thermal stratification introduces thermal shock effect which results in local stress and fatique problems that must be considered in the design of nuclear power plant components. Local stress and fatique calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343° C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.

  19. Local inertial oscillations in the surface ocean generated by time-varying winds

    Science.gov (United States)

    Chen, Shengli; Polton, Jeff A.; Hu, Jianyu; Xing, Jiuxing

    2015-12-01

    A new relationship is presented to give a review study on the evolution of inertial oscillations in the surface ocean locally generated by time-varying wind stress. The inertial oscillation is expressed as the superposition of a previous oscillation and a newly generated oscillation, which depends upon the time-varying wind stress. This relationship is employed to investigate some idealized wind change events. For a wind series varying temporally with different rates, the induced inertial oscillation is dominated by the wind with the greatest variation. The resonant wind, which rotates anti-cyclonically at the local inertial frequency with time, produces maximal amplitude of inertial oscillations, which grows monotonically. For the wind rotating at non-inertial frequencies, the responses vary periodically, with wind injecting inertial energy when it is in phase with the currents, but removing inertial energy when it is out of phase. The wind rotating anti-cyclonically with time is much more favorable to generate inertial oscillations than the cyclonic rotating wind. The wind with a frequency closer to the inertial frequency generates stronger inertial oscillations. For a diurnal wind, the induced inertial oscillation is dependent on latitude and is most significant at 30 °. This relationship is also applied to examine idealized moving cyclones. The inertial oscillation is much stronger on the right-hand side of the cyclone path than on the left-hand side (in the northern hemisphere). This is due to the wind being anti-cyclonic with time on the right-hand side, but cyclonic on the other side. The inertial oscillation varies with the cyclone translation speed. The optimal translation speed generating the greatest inertial oscillations is 2 m/s at the latitude of 10 ° and gradually increases to 6 m/s at the latitude of 30 °.

  20. On the quantum mechanical theory of stress and force

    International Nuclear Information System (INIS)

    Nielsen, O.H.; Martin, R.M.

    1985-01-01

    The stress theorem presented previously by the present authors is derived in detail and is related to the virial and force theorems. Stress fields are considered in two alternative forms, which both give the same macroscopic stress and forces on nuclei when integrated over appropriate surfaces. A crucial concept is interactions that ''cross'' surfaces. Explicit forms of the stress field within the local-density approximation are given, together with a generalization of the approximate Liberman form for pressure. Reciprocal-space expressions and ab-initio calculations are considered in detail in an accompanying paper. (orig.)

  1. Alleviating acid soil stress in cowpea with a local population of ...

    African Journals Online (AJOL)

    Alleviating acid soil stress in cowpea with a local population of arbuscular ... Roots of the cowpea lines were all heavily colonized by the fungi and their leaf P was ... Total dry weight of inoculated cowpea was not affected by soil acidity while it ...

  2. A high-order boundary integral method for surface diffusions on elastically stressed axisymmetric rods

    OpenAIRE

    Li, Xiaofan; Nie, Qing

    2009-01-01

    Many applications in materials involve surface diffusion of elastically stressed solids. Study of singularity formation and long-time behavior of such solid surfaces requires accurate simulations in both space and time. Here we present a high-order boundary integral method for an elastically stressed solid with axi-symmetry due to surface diffusions. In this method, the boundary integrals for isotropic elasticity in axi-symmetric geometry are approximated through modified alternating quadratu...

  3. Towards quantifying horizontal stresses of free-polling pneumatic rubber tyres on road surfaces

    CSIR Research Space (South Africa)

    De Beer, Morris

    2008-07-01

    Full Text Available out in which the horizontal stresses on a relatively rough-textured (RT) test surface were compared with those on a relatively smooth (S) test surface, representing nominal positive textured road surfaces and nominal smooth (zero texture) road surfaces...

  4. State-of-stress in magmatic rift zones: Predicting the role of surface and subsurface topography

    Science.gov (United States)

    Oliva, S. J. C.; Ebinger, C.; Rivalta, E.; Williams, C. A.

    2017-12-01

    Continental rift zones are segmented along their length by large fault systems that form in response to extensional stresses. Volcanoes and crustal magma chambers cause fundamental changes to the density structure, load the plates, and alter the state-of-stress within the crust, which then dictates fracture orientation. In this study, we develop geodynamic models scaled to a structure, petrologic and thermodynamic studies constrain material densities, and seismicity and structural analyses constrain active and time-averaged kinematics. This area is an ideal test area because a 60º stress rotation is observed in time-averaged fault and magma intrusion, and in local seismicity, and because this was the site of a large volume dike intrusion and seismic sequence in 2007. We use physics-based 2D and 3D models (analytical and finite elements) constrained by data from active rift zones to quantify the effects of loading on state-of-stress. By modeling varying geometric arrangements, and density contrasts of topographic and subsurface loads, and with reasonable regional extensional forces, the resulting state-of-stress reveals the favored orientation for new intrusions. Although our models are generalized, they allow us to evaluate whether a magmatic system (surface and subsurface) can explain the observed stress rotation, and enable new intrusions, new faults, or fault reactivation with orientations oblique to the main border faults. Our results will improve our understanding of the different factors at play in these extensional regimes, as well as contribute to a better assessment of the hazards in the area.

  5. Probing Earth's State of Stress

    Science.gov (United States)

    Delorey, A. A.; Maceira, M.; Johnson, P. A.; Coblentz, D. D.

    2016-12-01

    The state of stress in the Earth's crust is a fundamental physical property that controls both engineered and natural systems. Engineered environments including those for hydrocarbon, geothermal energy, and mineral extraction, as well those for storage of wastewater, carbon dioxide, and nuclear fuel are as important as ever to our economy and environment. Yet, it is at spatial scales relevant to these activities where stress is least understood. Additionally, in engineered environments the rate of change in the stress field can be much higher than that of natural systems. In order to use subsurface resources more safely and effectively, we need to understand stress at the relevant temporal and spatial scales. We will present our latest results characterizing the state of stress in the Earth at scales relevant to engineered environments. Two important components of the state of stress are the orientation and magnitude of the stress tensor, and a measure of how close faults are to failure. The stress tensor at any point in a reservoir or repository has contributions from both far-field tectonic stress and local density heterogeneity. We jointly invert seismic (body and surface waves) and gravity data for a self-consistent model of elastic moduli and density and use the model to calculate the contribution of local heterogeneity to the total stress field. We then combine local and plate-scale contributions, using local indicators for calibration and ground-truth. In addition, we will present results from an analysis of the quantity and pattern of microseismicity as an indicator of critically stressed faults. Faults are triggered by transient stresses only when critically stressed (near failure). We show that tidal stresses can trigger earthquakes in both tectonic and reservoir environments and can reveal both stress and poroelastic conditions.

  6. Correlation of 0.67um scatter with local stress in Ge impacted with the modified Cambridge liquid jet device

    Science.gov (United States)

    Wilson, Michael; Price, D.; Strohecker, Steve

    1994-09-01

    Germanium witness samples were impacted with the NAWCADWAR modified Cambridge liquid jet device introducing varying levels of damage about the center of each sample. Surface damage statistics were collected, scatter measurements were made at 0.67 micrometers and the samples were failed in tension using a bi-axial flexure test setup. The level and character of the damage was correlated with the reflected scatter measurements as a function of local stress and flaw size distribution. Bi-axial flexure data was analyzed to predict fracture stress and the probability of failure of the germanium samples. The mechanical data were then correlated with the scatter data in order to correlate the BRDF with the material failure. The BRDF measurements were taken in several different orientations in order to study the differences in scatter character for the in-plane and out-of-plane conditions.

  7. X-ray fractography by using synchrotron radiation source. Residual stress distribution just beneath fatigue fracture surface

    International Nuclear Information System (INIS)

    Akita, Koichi; Yoshioka, Yasuo; Suzuki, Hiroshi; Sasaki, Toshihiko

    2000-01-01

    The residual stress distributions just beneath the fatigue fracture surface were measured using synchrotron radiation with three different wavelengths, i.e., three different penetration depths. The residual stress distributions were estimated from three kinds of diffraction data by the following process. First, a temporary residual stress distribution in the depth direction is assumed. Theoretical 2θ-sin 2 ψ diagrams for each wavelength, where each has a different penetration depth, are calculated by the cosψ method developed by one of the authors. The sum total of the differences between the theoretical and experimental values of the diffraction angle in 2θ-sin 2 ψ diagrams is calculated. This total value is minimized by changing the assumed stress distribution by the quasi-Newton optimization method. Finally, optimized 2θ-sin 2 ψ diagrams for each penetration depth and detailed stress distribution are determined. The true surface residual stress is obtained from this stress distribution. No effect of load ratio R (= P min /P max ) on the residual stresses of the fatigue fracture surfaces in low-carbon steels was observed when the sin 2 ψ method was used for stress measurement. However, the residual stresses became higher with increasing R when these were measured by the proposed method. On the basis of this, the stress intensity factor range, ΔK, can be estimated from the residual stress on the fatigue fracture surface. (author)

  8. Sectoral contributions to surface water stress in the coterminous United States

    International Nuclear Information System (INIS)

    Averyt, K; Meldrum, J; Caldwell, P; Sun, G; McNulty, S; Huber-Lee, A; Madden, N

    2013-01-01

    Here, we assess current stress in the freshwater system based on the best available data in order to understand possible risks and vulnerabilities to regional water resources and the sectors dependent on freshwater. We present watershed-scale measures of surface water supply stress for the coterminous United States (US) using the water supply stress index (WaSSI) model which considers regional trends in both water supply and demand. A snapshot of contemporary annual water demand is compared against different water supply regimes, including current average supplies, current extreme-year supplies, and projected future average surface water flows under a changing climate. In addition, we investigate the contributions of different water demand sectors to current water stress. On average, water supplies are stressed, meaning that demands for water outstrip natural supplies in over 9% of the 2103 watersheds examined. These watersheds rely on reservoir storage, conveyance systems, and groundwater to meet current water demands. Overall, agriculture is the major demand-side driver of water stress in the US, whereas municipal stress is isolated to southern California. Water stress introduced by cooling water demands for power plants is punctuated across the US, indicating that a single power plant has the potential to stress water supplies at the watershed scale. On the supply side, watersheds in the western US are particularly sensitive to low flow events and projected long-term shifts in flow driven by climate change. The WaSSI results imply that not only are water resources in the southwest in particular at risk, but that there are also potential vulnerabilities to specific sectors, even in the ‘water-rich’ southeast. (letter)

  9. Electromagnetic Detection of Stress Gradients at the Surfaces of Metals

    International Nuclear Information System (INIS)

    Schmidt, William F.; Zinke, Otto H.

    2004-01-01

    A general, integral expression is developed which relates measurements of the variations of the imaginary component of complex- reluctance with frequency to stress profiles near the surfaces of metals. The technique should yield either applied or residual stress profiles produced, for example, by heat-treating, metal-working, fatigue, or peening. It may even be applicable to carburizing. The technique of measurement cancels out the effects of any pre-treatment residual-stress profile (subject to the assumption of superposition). The general, integral expression is induced from the results of measurements on a steel bar which is subjected to both tensile tests and bending tests

  10. INTERFACE DEVICE FOR NONDESTRUCTIVE TESTING OF RESIDUAL SURFACE STRESSES

    Directory of Open Access Journals (Sweden)

    Gennady A. Perepelkin

    2016-01-01

    Full Text Available The paper considers the organization of connection of a personal computer with a device for nondestructive testing of residual surface stresses. The device works is based on the phenomenon of diffraction of ionizing radiation from the crystal lattice near the surface of the crystallites. Proposed software interface to the organization for each type of user: the device developers, administrators, users. Some aspects of the organization of communication microcontroller to a PC via USB-port

  11. LSAH: a fast and efficient local surface feature for point cloud registration

    Science.gov (United States)

    Lu, Rongrong; Zhu, Feng; Wu, Qingxiao; Kong, Yanzi

    2018-04-01

    Point cloud registration is a fundamental task in high level three dimensional applications. Noise, uneven point density and varying point cloud resolutions are the three main challenges for point cloud registration. In this paper, we design a robust and compact local surface descriptor called Local Surface Angles Histogram (LSAH) and propose an effectively coarse to fine algorithm for point cloud registration. The LSAH descriptor is formed by concatenating five normalized sub-histograms into one histogram. The five sub-histograms are created by accumulating a different type of angle from a local surface patch respectively. The experimental results show that our LSAH is more robust to uneven point density and point cloud resolutions than four state-of-the-art local descriptors in terms of feature matching. Moreover, we tested our LSAH based coarse to fine algorithm for point cloud registration. The experimental results demonstrate that our algorithm is robust and efficient as well.

  12. Analysis of stress intensity factors for surface cracks in pre/post penetration

    International Nuclear Information System (INIS)

    Miyoshi, Toshiro; Yoshida, Yuichiro

    1988-01-01

    It is important to evaluate the penetration of surface cracks in a Leak-Before-Break analysis. Because the stress intensity factors for surface cracks in pre/post penetration had not yet been analyzed, the authors carried three-dimensional boundary element analyses in order to obtain them. First, the authors developed the technique of nodal breakdown appropriate for cracks with short ligament length in a two-dimensional boundary element analysis. Next, analyses of stress intensity factor for surface cracks in pre/post penetration were carried out using the technique of nodal breakdown for cracks with short ligament length and the three-dimensional boundary element code BEM 3 D which was designed for a supercomputer. (author)

  13. Effect of surface stress state on dissolution property of Alloy 690 in simulated primary water condition

    International Nuclear Information System (INIS)

    Kim, Kyung Mo; Shim, Hee-Sang; Lee, Eun Hee; Seo, Myung Ji; Han, Jung Ho; Hur, Do Haeng

    2014-01-01

    The dissolution control of nickel is important to reduce the radioactive dose rate and deterioration of fuel performance in the operation of nuclear power plants (PWR). The corrosion properties are affected by the metal surface residual stress introduced in manufacture process such as work hardening. This work studied the effect of surface modification on the release rate of Alloy 690, nickel-base alloy for a steam generator tube, in the test condition of simulated primary water chemistry in PWRs. The surface stress modification was applied by the electro-polishing and shot peening method. Shot peening process was applied using ceramic beads with different intensities through the variation of air pressure. The corrosion release tests performed at 330degC with LiOH 2 ppm and H 3 BO 4 1200 ppm, DH(dissolved hydrogen) 35 cc/kg (STP) and about 20 ppb of DO(dissolved oxygen) condition. The corrosion release rate was evaluated by a gravimetric analysis method and the surface analysed by SEM and optical microscope. The surface residual stress was measured by an X-ray diffractometer, and the distribution of stress state was evaluated by a micro-hardness tester. The metal ion release rate of alloy 690 was evaluated from the influence of the stress state on the metal surface. The oxide property and structure was affected by the residual stress in the oxide layer. (author)

  14. Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins.

    Science.gov (United States)

    Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Price, Richard B T; Sullivan, Braden; Moeginger, Bernhard

    2015-02-01

    An inhomogeneous irradiance distribution from a light-curing unit (LCU) can locally cause inhomogeneous curing with locally inadequately cured and/or over-cured areas causing e.g. monomer elution or internal shrinkage stresses, and thus reduce the lifetime of dental resin based composite (RBC) restorations. The aim of the study is to determine both the irradiance distribution of two light curing units (LCUs) and its influence on the local mechanical properties of a RBC. Specimens of Arabesk TOP OA2 were irradiated for 5, 20, and 80s using a Bluephase® 20i LCU in the Low mode (666mW/cm(2)), in the Turbo mode (2222mW/cm(2)) and a Celalux® 2 (1264mW/cm(2)). The degree of conversion (DC) was determined with an ATR-FTIR. The Knoop micro-hardness (average of five specimens) was measured on the specimen surface after 24h of dark and dry storage at room temperature. The irradiance distribution affected the hardness distribution across the surface of the specimens. The hardness distribution corresponded well to the inhomogeneous irradiance distributions of the LCU. The highest reaction rates occurred after approximately 2s light exposure. A DC of 40% was reached after 3.6 or 5.7s, depending on the LCU. The inhomogeneous hardness distribution was still evident after 80s of light exposure. The irradiance distribution from a LCU is reflected in the hardness distribution across the surface. Irradiance level of the LCU and light exposure time do not affect the pattern of the hardness distribution--only the hardness level. In areas of low irradiation this may result in inadequate resin polymerization, poor physical properties, and hence premature failure of the restorations as they are usually much smaller than the investigated specimens. It has to be stressed that inhomogeneous does not necessarily mean poor if in all areas of the restoration enough light intensity is introduced to achieve a high degree of cure. Copyright © 2014 Academy of Dental Materials. Published by

  15. Transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations

    International Nuclear Information System (INIS)

    Sugano, Y.

    1980-01-01

    The transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations on two edges are studied by means of the Airy stress function. The purposes of this paper are to present a method of determing the transient thermal stresses in an orthographic rectangular plate with four edges of distinct thermal boundary condition of the third kind which exactly satisfy the traction-free conditions of shear stress over all boundaries including four corners of the plate, and to consider the effects of the anisotropies of material properties and the convective heat transfer on the upper and lower surfaces on the thermal stress distribution. (orig.)

  16. Feasibility of local stress relieving close to main shell of a large vessel

    International Nuclear Information System (INIS)

    Hancinsky, O.A.

    1978-01-01

    This work determines the feasibility of local stress relieving for a circumferential pipe-to-nozzle field weld positioned close to the main shell of a large pressure vessel. This is applicable to nuclear as well as conventional vessels. ANSYS computer program is utilized to perform thermal and thermal stress analysis and ASME Pressure Vessels Code is adhered to. Conclusions and recommendations are made with a view on their applicability in practice

  17. Electronically controllable spoof localized surface plasmons

    Science.gov (United States)

    Zhou, Yong Jin; Zhang, Chao; Yang, Liu; Xun Xiao, Qian

    2017-10-01

    Electronically controllable multipolar spoof localized surface plasmons (LSPs) are experimentally demonstrated in the microwave frequencies. It has been shown that half integer order LSPs modes exist on the corrugated ring loaded with a slit, which actually arise from the Fabry-Perot-like resonances. By mounting active components across the slit in the corrugated rings, electronic switchability and tunability of spoof LSPs modes have been accomplished. Both simulated and measured results demonstrate efficient dynamic control of the spoof LSPs. These elements may form the basis of highly integrated programmable plasmonic circuits in microwave and terahertz regimes.

  18. Localized Donaldson-Thomas theory of surfaces

    DEFF Research Database (Denmark)

    Gholampour, Amin; Sheshmani, Artan; Yau, Shing-Tung

    2017-01-01

    Let S be a projective simply connected complex surface and  be a line bundle on S. We study the moduli space of stable compactly supported 2-dimensional sheaves on the total spaces of . The moduli space admits a ℂ∗-action induced by scaling the fibers of . We identify certain components of the......  is the canonical bundle of S, the Vafa-Witten invariants defined recently by Tanaka-Thomas, can be extracted from these localized DT invariants. VW invariants are expected to have modular properties as predicted by S-duality....

  19. Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations.

    Science.gov (United States)

    Peretz-Soroka, Hagit; Pevzner, Alexander; Davidi, Guy; Naddaka, Vladimir; Kwiat, Moria; Huppert, Dan; Patolsky, Fernando

    2015-07-08

    Significant research efforts have been dedicated to the integration of biological species with electronic elements to yield smart bioelectronic devices. The integration of DNA, proteins, and whole living cells and tissues with electronic devices has been developed into numerous intriguing applications. In particular, the quantitative detection of biological species and monitoring of biological processes are both critical to numerous areas of medical and life sciences. Nevertheless, most current approaches merely focus on the "monitoring" of chemical processes taking place on the sensing surfaces, and little efforts have been invested in the conception of sensitive devices that can simultaneously "control" and "monitor" chemical and biological reactions by the application of on-surface reversible stimuli. Here, we demonstrate the light-controlled fine modulation of surface pH by the use of photoactive molecularly modified nanomaterials. Through the use of nanowire-based FET devices, we showed the capability of modulating the on-surface pH, by intensity-controlled light stimulus. This allowed us simultaneously and locally to control and monitor pH-sensitive biological reactions on the nanodevices surfaces, such as the local activation and inhibition of proteolytic enzymatic processes, as well as dissociation of antigen-antibody binding interactions. The demonstrated capability of locally modulating the on-surface effective pH, by a light stimuli, may be further applied in the local control of on-surface DNA hybridization/dehybridization processes, activation or inhibition of living cells processes, local switching of cellular function, local photoactivation of neuronal networks with single cell resolution and so forth.

  20. A study of x-ray microbeam stress measurement for local area

    International Nuclear Information System (INIS)

    Natsume, Yoshitaka; Miyakawa, Susumu

    1987-01-01

    A new type X-ray microbeam equipment which is capable of three-dimensional oscillation at an X-ray radiation position was used to measure the residual stress of pure iron powder and bending plate specimens as well as that in the vicinity of fatigue crack tip of 1/2 CT specimen. The results obtained are summerized as follows. (1) Diffraction profiles of pure iron powder with diameter 0.02 ∼ 0.03 μm particle size obtained by the present microbeam technique in the beam area of 80 μm in diamether and measuring time more than 800 sec showed Kα 1 and Kα 2 peaks clearly, so that these profiles are good enough for stress measurement. (2) The measured stress of pure iron powder with diameter 10 ∼ 25 μm particle size in the beam area of 80 μm in diameter was not equal to 0 MPa. The measured stress varied greatly and was independent of measuring time. (3) The measured stress of pure iron powder with diameter 0.02 ∼ 0.03 μm particle size in the beam area of 80 μm in diameter was almost 1 MPa, which shows the good accuracy of this X-ray micro-beam equipment. (4) The relation between the X-ray measured stress and the mechanically applied stress showed good agreement. (5) The distribution of residual stress at the vicinity of fatigue crack tip showed that the residual stress at the fatigue crack tip was compression and the residual stress in front of crack tip was tension. This tensile residual stress in front of crack tip existed in the area from 0.02 mm to 2 mm. (6) The above results show that the present equipment is advantageous in the investigation of local stress, shortening the measuring time without sacrificing the accuracy. (author)

  1. Comparison of residual stress measurement in thin films using surface micromachining method

    International Nuclear Information System (INIS)

    He, Q.; Luo, Z.X.; Chen, X.Y.

    2008-01-01

    Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long-short beam strain sensor

  2. Localized surface phonon polariton resonances in polar gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Kaijun, E-mail: kfeng@nd.edu; Islam, S. M.; Verma, Jai; Hoffman, Anthony J. [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Streyer, William; Wasserman, Daniel [Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States); Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14850 (United States)

    2015-08-24

    We demonstrate the excitation of localized surface phonon polaritons in an array of sub-diffraction pucks fabricated in an epitaxial layer of gallium nitride (GaN) on a silicon carbide (SiC) substrate. The array is characterized via polarization- and angle-dependent reflection spectroscopy in the mid-infrared, and coupling to several localized modes is observed in the GaN Reststrahlen band (13.4–18.0 μm). The same structure is simulated using finite element methods and the charge density of the modes are studied; transverse dipole modes are identified for the transverse electric and magnetic polarizations and a quadrupole mode is identified for the transverse magnetic polarization. The measured mid-infrared spectrum agrees well with numerically simulated spectra. This work could enable optoelectronic structures and devices that support surface modes at mid- and far-infrared wavelengths.

  3. Horizontal rotation of the local stress field in response to magmatic activity: Evidence from case studies and modeling

    Science.gov (United States)

    Roman, D. C.

    2003-12-01

    A complete understanding of the initiation, evolution, and termination of volcanic eruptions requires reliable monitoring techniques to detect changes in the conduit system during periods of activity, as well as corresponding knowledge of conduit structure and of magma physical properties. Case studies of stress field orientation prior to, during, and after magmatic activity can be used to relate changes in stress field orientation to the state of the magmatic conduit system. These relationships may be tested through modeling of induced stresses. Here I present evidence from case studies and modeling that horizontal rotation of the axis of maximum compressive stress at an active volcano indicates pressurization of a magmatic conduit, and that this rotation, when observed, may also be indicative of the physical properties of the ascending magma. Changes in the local stress field orientation during the 1992 eruption sequence at Crater Peak (Mt. Spurr), Alaska were analyzed by calculating and inverting subsets of over 150 fault-plane solutions. Local stress tensors for four time periods, corresponding approximately to changes in activity at the volcano, were calculated based on the misfit of individual fault-plane solutions to a regional stress tensor. Results indicate that for nine months prior to the eruption, local maximum compressive stress was oriented perpendicular to regional maximum compressive stress. A similar horizontal rotation was observed beginning in November of 1992, coincident with an episode of elevated earthquake and tremor activity indicating intrusion of magma into the conduit. During periods of quiescence the local stress field was similar to the regional stress field. Similar horizontal rotations have been observed at Mt. Ruapehu, New Zealand (Miller and Savage 2001, Gerst 2003), Usu Volcano, Japan (Fukuyama et al. 2001), Unzen Volcano, Japan (Umakoshi et al. 2001), and Mt. St. Helens Volcano, USA (Moran 1994) in conjunction with eruptive

  4. Variation of air--water gas transfer with wind stress and surface viscoelasticity

    OpenAIRE

    Frew, Nelson M.; Bock, Erik J.; McGillis, Wade R.; Karachintsev, Andrey V.; Hara, Tetsu; Münsterer, Thomas; Jähne, Bernd

    1995-01-01

    Previous parameterizations of gas transfer velocity have attempted to cast this quantity as a function of wind speed or wind-stress. This study demonstrates that the presence of a surface film is effective at reducing the gas transfer velocity at constant wind-stress. Gas exchange experiments were performed at WHOI and UH using annular wind-wave tanks of different scales. Systematic variations of wind-stress and surfactant concentration (Triton-X-100) were explored to determ...

  5. A one-layer satellite surface energy balance for estimating evapotranspiration rates and crop water stress indexes.

    Science.gov (United States)

    Barbagallo, Salvatore; Consoli, Simona; Russo, Alfonso

    2009-01-01

    Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (r(ah)) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (r(s)) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach "K(c) reflectance-based", which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations.

  6. Modeling and Parameter Optimization for Surface Roughness and Residual Stress in Dry Turning Process

    Directory of Open Access Journals (Sweden)

    M. H. El-Axir

    2017-10-01

    Full Text Available The influence of some turning variables and tool overhang on surface roughness parameters and residual stress induced due to machining 6061-T6 aluminum alloy is investigated in this paper. Four input parameters (cutting speed, feed rate, depth of cut and tool overhang are considered. Tests are carried out by precision turning operation on a lathe. Design of experiment techniques, i.e. response surface methodology (RSM and Taguchi's technique have been used to accomplish the objective of the experimental study. Surface roughness parameters are measured using a portable surface roughness device while residual stresses are measured employing deflection-etching technique using electrochemical analysis. The results obtained reveal that feed and rotational speed play significant role in determining the average surface roughness. Furthermore, the depth of cut and tool overhang are less significant parameters, whereas tool overhang interacts with feed rate. The best result of surface roughness was obtained using low or medium values of overhang with low speed and /or feed rate. Minimum maximum tensile residual stress can be obtained with a combination of tool overhang of 37 mm with very low depth of cut, low rotational speed and feed rate of 0.188 mm/rev.

  7. Stress intensity evaluation for surface crack with use of boundary element method and influence function method and the surface crack extension analysis

    International Nuclear Information System (INIS)

    Yuuki, R.; Ejima, K.

    1991-01-01

    In this study, three-dimensional boundary element elastostatic analysis is carried out on various surface crack problems. The present BEM uses a Mindlin's solution as well as a Kelvin's solution as a fundamental solution. So we can obtain accurate solutions for a surface crack just before or after a penetration. The obtained solutions for various shapes of surface cracks are stored as the data base, based on the influence function method. We develop the surface crack extension analysis system using the stress intensity factor data base and also the fatigue crack growth law. Our system seems to be useful especially for the analysis of the surface crack just before or after the penetration and also under the residual stresses

  8. Effect of Surface Roughness on MHD Couple Stress Squeeze-Film Characteristics between a Sphere and a Porous Plane Surface

    Directory of Open Access Journals (Sweden)

    M. Rajashekar

    2012-01-01

    Full Text Available The combined effects of couple stress and surface roughness on the MHD squeeze-film lubrication between a sphere and a porous plane surface are analyzed, based upon the thin-film magnetohydrodynamic (MHD theory. Using Stoke’s theory to account for the couple stresses due to the microstructure additives and the Christensen’s stochastic method developed for hydrodynamic lubrication of rough surfaces derives the stochastic MHD Reynolds-type equation. The expressions for the mean MHD squeeze-film pressure, mean load-carrying capacity, and mean squeeze-film time are obtained. The results indicate that the couple stress fluid in the film region enhances the mean MHD squeeze-film pressure, load-carrying capacity, and squeeze-film time. The effect of roughness parameter is to increase (decrease the load-carrying capacity and lengthen the response time for azimuthal (radial roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and increase the squeeze-film time as compared to the solid case.

  9. Influence of localized plasticity on Stress Corrosion Cracking of austenitic stainless steel. Application to IASCC of internals reactor core vessels

    International Nuclear Information System (INIS)

    Cisse, Sarata

    2012-01-01

    The surface conditions of the 316L screw connecting vessel internals of the primary circuit of PWR (pressurized water reactor) corresponds to a grinding condition. These screws are affected by the IASCC (Irradiation Assisted Stress Corrosion Cracking). Initiation of cracking depends on the surface condition but also on the external oxidation and interactions of oxide layer with the deformation bands. The first objective of this study is to point the influence of surface condition on the growth kinetic of oxide layer, and the surface reactivity of 304, 316 stainless steel grade exposed to PWR primary water at 340 C. The second objective is to determine influence of strain localization on the SCC of austenitic stainless steels in PWR primary water. Indeed, the microstructure of irradiated 304, 316 grades correspond to a localized deformation in deformation bands free of radiation defects. In order to reproduce that microstructure without conducting irradiations, low cycle fatigue tests at controlled stain amplitude are implemented for the model material of the study (A286 austenitic stainless steel hardened by the precipitation of phase γ'Ni3(Ti, Al)). During the mechanical cycling (after the first hardening cycles), the precipitates are dissolved in slip bands leading to the localization of the deformation. Once the right experimental conditions in low cycle fatigue obtained (for localized microstructure), interactions oxidation / deformation bands are studied by oxidizing pre deformed samples containing deformation bands and non deformed samples. The tensile tests at a slow strain rate of 8 x 10 -8 /s are also carried out on pre deformed samples and undeformed samples. The results showed that surface treatment induces microstructural modifications of the metal just under the oxide layer, leading to slower growth kinetics of the oxide layer. However, surface treatment accelerates development of oxides penetrations in metal under the oxide layer. As example, for

  10. Si segregation at Fe grain boundaries analyzed by ab initio local energy and local stress

    International Nuclear Information System (INIS)

    Bhattacharya, Somesh Kr; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori

    2014-01-01

    Using density-functional theory calculations combined with recent local-energy and local-stress schemes, we studied the effects of Si segregation on the structural, mechanical and magnetic properties of the Σ3(1 1 1) and Σ11(3 3 2) Fe GBs formed by rotation around the [1 1 0] axis. The segregation mechanism was analyzed by the local-energy decomposition of the segregation energy, where the segregation energy is expressed as a sum of the following four terms: the local-energy change of Si atoms from the isolated state in bulk Fe to the GB segregated state, the stabilization of replaced Fe atoms from the GB to the bulk, the local-energy change of neighboring Fe atoms from the pure GB to the segregated GB and the local-energy change of neighboring Fe atoms from the system of an isolated Si atom in the bulk Fe to the pure bulk Fe. The segregation energy and value of each term greatly depends on the segregation site and Si concentration. The segregation at interface Fe sites with higher local energies in the original GB configurations naturally leads to higher segregation-energy gains, while interface sites with lower local energies can lead to larger energy gains if stronger Si–Fe interactions occur locally in the final segregated configurations. The high Si concentration reduces the segregation-energy gain per Si atom due to the local-energy increases of Si atoms neighboring to each other or through the reduction in the number of stabilized Fe atoms per Si atom as observed in a Si dimer in bulk Fe. In the Si-segregated GBs, Si–Fe bonds enhance local Young’s moduli and tend to suppress the interface weakening, while the GB adhesion is slightly reduced. And Fe atoms contacting Si atoms have reduced magnetic moments, due to Si–Fe sp-d hybridization interactions. (paper)

  11. Spectroscopic link between adsorption site occupation and local surface chemical reactivity

    DEFF Research Database (Denmark)

    Baraldi, A.; Lizzit, S.; Comelli, G.

    2004-01-01

    rules, from which adsorption sites are directly determined. Theoretical calculations rationalize the results for transition metal surfaces in terms of the energy shift of the d-band center of mass and this proves that adsorbate-induced SCL shifts provide a spectroscopic measure of local surface...

  12. Mechanical stress-controlled tunable active frequency-selective surface

    Science.gov (United States)

    Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

    2017-01-01

    This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

  13. Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress

    KAUST Repository

    Paterson, C.; Wilson, S. K.; Duffy, B. R.

    2014-01-01

    large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a

  14. Comparisons of predicted steady-state levels in rooms with extended- and local-reaction bounding surfaces

    Science.gov (United States)

    Hodgson, Murray; Wareing, Andrew

    2008-01-01

    A combined beam-tracing and transfer-matrix model for predicting steady-state sound-pressure levels in rooms with multilayer bounding surfaces was used to compare the effect of extended- and local-reaction surfaces, and the accuracy of the local-reaction approximation. Three rooms—an office, a corridor and a workshop—with one or more multilayer test surfaces were considered. The test surfaces were a single-glass panel, a double-drywall panel, a carpeted floor, a suspended-acoustical ceiling, a double-steel panel, and glass fibre on a hard backing. Each test surface was modeled as of extended or of local reaction. Sound-pressure levels were predicted and compared to determine the significance of the surface-reaction assumption. The main conclusions were that the difference between modeling a room surface as of extended or of local reaction is not significant when the surface is a single plate or a single layer of material (solid or porous) with a hard backing. The difference is significant when the surface consists of multilayers of solid or porous material and includes a layer of fluid with a large thickness relative to the other layers. The results are partially explained by considering the surface-reflection coefficients at the first-reflection angles.

  15. BnNHL18A shows a localization change by stress-inducing chemical treatments

    International Nuclear Information System (INIS)

    Lee, Suk-Bae; Ham, Byung-Kook; Park, Jeong Mee; Kim, Young Jin; Paek, Kyung-Hee

    2006-01-01

    The two genes, named BnNHL18A and BnNHL18B, showing sequence homology with Arabidopsis NDR1/HIN1-like (NHL) genes, were isolated from cDNA library prepared with oilseed rape (Brassica napus) seedlings treated with NaCl. The transcript level of BnNHL18A was increased by sodium chloride, ethephon, hydrogen peroxide, methyl jasmonate, or salicylic acid treatment. The coding regions of BnNHL18A and BnNHL18B contain a sarcolipin (SLN)-like sequence. Analysis of the localization of smGFP fusion proteins showed that BnNHL18A is mainly localized to endoplasmic reticulum (ER). This result suggests that the SLN-like sequence plays a role in retaining proteins in ER membrane in plants. In response to NaCl, hydrogen peroxide, ethephon, and salicylic acid treatments, the protein localization of BnNHL18A was changed. Our findings suggest a common function of BnNHL18A in biotic and abiotic stresses, and demonstrate the presence of the shared mechanism of protein translocalization between the responses to plant pathogen and to osmotic stress

  16. Predicting Posttraumatic Stress Symptom Prevalence and Local Distribution after an Earthquake with Scarce Data.

    Science.gov (United States)

    Dussaillant, Francisca; Apablaza, Mauricio

    2017-08-01

    After a major earthquake, the assignment of scarce mental health emergency personnel to different geographic areas is crucial to the effective management of the crisis. The scarce information that is available in the aftermath of a disaster may be valuable in helping predict where are the populations that are in most need. The objectives of this study were to derive algorithms to predict posttraumatic stress (PTS) symptom prevalence and local distribution after an earthquake and to test whether there are algorithms that require few input data and are still reasonably predictive. A rich database of PTS symptoms, informed after Chile's 2010 earthquake and tsunami, was used. Several model specifications for the mean and centiles of the distribution of PTS symptoms, together with posttraumatic stress disorder (PTSD) prevalence, were estimated via linear and quantile regressions. The models varied in the set of covariates included. Adjusted R2 for the most liberal specifications (in terms of numbers of covariates included) ranged from 0.62 to 0.74, depending on the outcome. When only including peak ground acceleration (PGA), poverty rate, and household damage in linear and quadratic form, predictive capacity was still good (adjusted R2 from 0.59 to 0.67 were obtained). Information about local poverty, household damage, and PGA can be used as an aid to predict PTS symptom prevalence and local distribution after an earthquake. This can be of help to improve the assignment of mental health personnel to the affected localities. Dussaillant F , Apablaza M . Predicting posttraumatic stress symptom prevalence and local distribution after an earthquake with scarce data. Prehosp Disaster Med. 2017;32(4):357-367.

  17. Adaptive local surface refinement based on LR NURBS and its application to contact

    Science.gov (United States)

    Zimmermann, Christopher; Sauer, Roger A.

    2017-12-01

    A novel adaptive local surface refinement technique based on Locally Refined Non-Uniform Rational B-Splines (LR NURBS) is presented. LR NURBS can model complex geometries exactly and are the rational extension of LR B-splines. The local representation of the parameter space overcomes the drawback of non-existent local refinement in standard NURBS-based isogeometric analysis. For a convenient embedding into general finite element codes, the Bézier extraction operator for LR NURBS is formulated. An automatic remeshing technique is presented that allows adaptive local refinement and coarsening of LR NURBS. In this work, LR NURBS are applied to contact computations of 3D solids and membranes. For solids, LR NURBS-enriched finite elements are used to discretize the contact surfaces with LR NURBS finite elements, while the rest of the body is discretized by linear Lagrange finite elements. For membranes, the entire surface is discretized by LR NURBS. Various numerical examples are shown, and they demonstrate the benefit of using LR NURBS: Compared to uniform refinement, LR NURBS can achieve high accuracy at lower computational cost.

  18. Estimating local atmosphere-surface fluxes using eddy covariance and numerical Ogive optimization

    DEFF Research Database (Denmark)

    Sievers, Jakob; Papakyriakou, Tim; Larsen, Søren

    2014-01-01

    Estimating representative surface-fluxes using eddy covariance leads invariably to questions concerning inclusion or exclusion of low-frequency flux contributions. For studies where fluxes are linked to local physical parameters and up-scaled through numerical modeling efforts, low-frequency cont......Estimating representative surface-fluxes using eddy covariance leads invariably to questions concerning inclusion or exclusion of low-frequency flux contributions. For studies where fluxes are linked to local physical parameters and up-scaled through numerical modeling efforts, low...

  19. Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

    Science.gov (United States)

    Mankari, Kamal; Acharyya, Swati Ghosh

    2017-12-01

    We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

  20. Effect of Local Strain Distribution of Cold-Rolled Alloy 690 on Primary Water Stress Corrosion Crack Growth Behavior

    Directory of Open Access Journals (Sweden)

    Kim S.-W.

    2017-06-01

    Full Text Available This work aims to study the stress corrosion crack growth behavior of cold-rolled Alloy 690 in the primary water of a pressurized water reactor. Compared with Alloy 600, which shows typical intergranular cracking along high angle grain boundaries, the cold-rolled Alloy 690, with its heterogeneous microstructure, revealed an abnormal crack growth behavior in mixed mode, that is, in transgranular cracking near a banded region, and in intergranular cracking in a matrix region. From local strain distribution analysis based on local mis-orientation, measured along the crack path using the electron back scattered diffraction method, it was suggested that the abnormal behavior was attributable to a heterogeneity of local strain distribution. In the cold-rolled Alloy 690, the stress corrosion crack grew through a highly strained area formed by a prior cold-rolling process in a direction perpendicular to the maximum principal stress applied during a subsequent stress corrosion cracking test.

  1. Modelling of composition and stress profiles in low temperature surface engineered stainless steel

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard; Hattel, Jesper Henri; Somers, Marcel A. J.

    2015-01-01

    temperature, time and gas composition is a prerequisite for targeted process optimization. A realistic model to simulate the developing case has to take the following influences on composition and stress into account: - a concentration dependent diffusion coefficient - trapping of nitrogen by chromium atoms...... stresses are introduced in the developing case, arising from the volume expansion that accompanies the dissolution of high interstitial contents in expanded austenite. Modelling of the composition and stress profiles developing during low temperature surface engineering from the processing parameters...... - the effect of residual stress on diffusive flux - the effect of residual stress on solubility of interstitials - plastic accommodation of residual stress. The effect of all these contributions on composition and stress profiles will be addressed....

  2. Consideration of microstructure evolution and residual stress measurement near severe worked surface using high energy x-ray

    International Nuclear Information System (INIS)

    Hashimoto, Tadafumi; Mochizuki, Masahito; Shobu, Takahisa

    2012-01-01

    It is necessary to establish a measurement method that can evaluate accurate stress on the surface. However, the microstructure evolution takes place near the surface due to severe plastic deformation, since structural members have been superpositioned a lot of working processes to complete. As well known, a plane stress can't be assumed on the severe worked surface. Therefore we have been proposed the measurement method that can be measured the in-depth distribution of residual stress components by using high energy X-ray from a synchrotron radiation source. There is the combination of the constant penetration depth method and tri-axial stress analysis. Measurements were performed by diffraction planes for the orientation parameter Γ=0.25 of which elastic constants are nearly equal to the mechanical one. The stress components obtained must be converted to the stress components in real space by using optimization technique, since it corresponds to the weighted average stress components associated with the attenuation of X-ray in materials. The predicted stress components distribution agrees very well with the corrected one which was measured by the conventional removal method. To verify the availability of the proposed method, thermal aging variation of residual stress components on the severe worked surface under elevated temperature was investigated using specimen superpositioned working processes (i.e., welding, machining, peening). It is clarified that the residual stress components increase with thermal aging, using the diffraction planes in hard elastic constants to the bulk. This result suggests that the thermal stability of residual stress has the dependence of the diffraction plane. (author)

  3. Stress distribution in mechanically surface treated Ti-2.5Cu determined by combining energy-dispersive synchrotron and neutron diffraction

    International Nuclear Information System (INIS)

    Maawad, E.; Brokmeier, H.-G.; Hofmann, M.; Genzel, Ch.; Wagner, L.

    2010-01-01

    Mechanical surface treatments such as shot peening (SP) or ball-burnishing (BB) induce plastic deformation close to the surface resulting in work-hardening and compressive residual stresses. It enhances the fatigue performance by retarding or even suppressing micro-crack growth from the surface into the interior. SP and BB were carried out on a solution heat treated (SHT) Ti-2.5Cu. The investigations of compressive and balancing tensile residual stresses need a combination of energy-dispersive synchrotron (ED) and neutron diffraction. Essential for the stress distribution is the stress state before surface treatments which was determined by neutron diffraction. Results show that the maximum compressive stress and its depth play an important role to improve the fatigue performance.

  4. Growth of contact area between rough surfaces under normal stress

    Science.gov (United States)

    Stesky, R. M.; Hannan, S. S.

    1987-05-01

    The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

  5. Analysis of fracture patterns and local stress field variations in fractured reservoirs

    Science.gov (United States)

    Deckert, Hagen; Drews, Michael; Fremgen, Dominik; Wellmann, J. Florian

    2010-05-01

    independently estimated regional stress tensor is put as a boundary condition into the BE Model. The computed BE model allows to recognize local 3D stress tensor perturbations caused by the larger faults that act as mechanical inhomogeneities. The geometry of the fracture network from field work together with the local stress tensors derived from the 3D BE models allows examining normal and shear stresses on single fractures in different domains of the investigated area. This in turn is used to evaluate, which of the fractures might preferably act as fluid conduits by describing the dilation potential of single fractures. The combination of an improved understanding of the fracture network along with local stress tensors variations from mechanical models will provide a sound evaluation of fluid pathways in fractured reservoirs. In future applications the accurate investigation of large discontinuity pattern in outcrops might be used for a better mathematical definition of fracture networks which could be implemented into numerical simulations of fluid flow.

  6. Midlife stress alters memory and mood-related behaviors in old age: Role of locally activated glucocorticoids.

    Science.gov (United States)

    Wheelan, Nicola; Kenyon, Christopher J; Harris, Anjanette P; Cairns, Carolynn; Al Dujaili, Emad; Seckl, Jonathan R; Yau, Joyce L W

    2018-03-01

    Chronic exposure to stress during midlife associates with subsequent age-related cognitive decline and may increase the vulnerability to develop psychiatric conditions. Increased hypothalamic-pituitary-adrenal (HPA) axis activity has been implicated in pathogenesis though any causative role for glucocorticoids is unestablished. This study investigated the contribution of local glucocorticoid regeneration by the intracellular enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), in persisting midlife stress-induced behavioral effects in mice. Middle-aged (10 months old) 11β-HSD1-deficient mice and wild-type congenic controls were randomly assigned to 28 days of chronic unpredictable stress or left undisturbed (non-stressed). All mice underwent behavioral testing at the end of the stress/non-stress period and again 6-7 months later. Chronic stress impaired spatial memory in middle-aged wild-type mice. The effects, involving a wide spectrum of behavioral modalities, persisted for 6-7 months after cessation of stress into early senescence. Enduring effects after midlife stress included impaired spatial memory, enhanced contextual fear memory, impaired fear extinction, heightened anxiety, depressive-like behavior, as well as reduced hippocampal glucocorticoid receptor mRNA expression. In contrast, 11β-HSD1 deficient mice resisted both immediate and enduring effects of chronic stress, despite similar stress-induced increases in systemic glucocorticoid activity during midlife stress. In conclusion, chronic stress in midlife exerts persisting effects leading to cognitive and affective dysfunction in old age via mechanisms that depend, at least in part, on brain glucocorticoids generated locally by 11β-HSD1. This finding supports selective 11β-HSD1 inhibition as a novel therapeutic target to ameliorate the long-term consequences of stress-related psychiatric disorders in midlife. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Atomically flat surface of (0 0 1) textured FePt thin films by residual stress control

    Energy Technology Data Exchange (ETDEWEB)

    Liu, S.H. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Hsiao, S.N., E-mail: pmami.hsiao@gmail.com [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chou, C.L.; Chen, S.K. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Lee, H.Y. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Department of Applied Science, National Hsinchu University of Education, Hsinchu 300, Taiwan (China)

    2015-11-01

    Highlights: • We demonstrate crystallographic structure, (0 0 1) texture, surface roughness, and residual stress in the single-layered FePt thin films annealed at various heating rates (10–110 K/s). • Texture coefficient of (0 0 1)-plane of the samples increases with increasing heating rate from 10 to 40 K/s, which is correlated with perpendicular magnetic anisotropy and in-plane tensile stress. • Dewetting phenomenon due to stress relaxation leads to the broadening of [0 0 1] easy axis and degradation of perpendicular magnetic anisotropy. • A strong dependence of surface roughness on in-plane residual stress was revealed. • When the samples are RTA at 40 K/s, the enhanced perpendicular magnetic anisotropy and atomically surface roughness are achieved. - Abstract: Single-layered Fe{sub 52}Pt{sub 48} films with thickness of 10 nm were sputter-deposited on glass substrates. Rapid thermal annealing with different heating rates (10–110 K/s) was applied to transform as-deposited fcc phase into L1{sub 0} phase and meanwhile to align [0 0 1]-axis of L1{sub 0} crystal along plane normal direction. Based on X-ray diffractometry using synchrotron radiation source, the texture coefficient of (0 0 1)-plane increases with increasing heating rate from 10 to 40 K/s, which is correlated with perpendicular magnetic anisotropy and in-plane tensile stress analyzed by asymmetric sin{sup 2} ψ method. Furthermore, it was revealed by atomic force microscopy that the dewetting process occurred as heating rate was raised up to 80 K/s and higher. The change in the microstructure due to stress relaxation leads to the degradation of (0 0 1) orientation and magnetic properties. Surface roughness is closely related to the in-plane tensile stress. Enhanced perpendicular magnetic anisotropy and atomically flat surface were achieved for the samples annealed at 40 K/s, which may be suitable for further practical applications. This work also suggests a feasible way for surface

  8. Effect of the local morphology in the field emission properties of conducting polymer surfaces

    International Nuclear Information System (INIS)

    De Assis, T A; Borondo, F; Benito, R M; Losada, J C; Andrade, R F S; Miranda, J G V; De Souza, Nara C; De Castilho, C M C; De B Mota, F

    2013-01-01

    In this work, we present systematic theoretical evidence of a relationship between the point local roughness exponent (PLRE) (which quantifies the heterogeneity of an irregular surface) and the cold field emission properties (indicated by the local current density and the macroscopic current density) of real polyaniline (PANI) surfaces, considered nowadays as very good candidates in the design of field emission devices. The latter are obtained from atomic force microscopy data. The electric field and potential are calculated in a region bounded by the rough PANI surface and a distant plane, both boundaries held at distinct potential values. We numerically solve Laplace’s equation subject to appropriate Dirichlet’s condition. Our results show that local roughness reveals the presence of specific sharp emitting spots with a smooth geometry, which are the main ones responsible (but not the only) for the emission efficiency of such surfaces for larger deposition times. Moreover, we have found, with a proper choice of a scale interval encompassing the experimentally measurable average grain length, a highly structured dependence of local current density on PLRE, considering different ticks of PANI surfaces. (paper)

  9. Surface-enhanced localized surface plasmon resonance biosensing of avian influenza DNA hybridization using subwavelength metallic nanoarrays

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Shin Ae; Jang, Sung Min; Kim, Sung June [School of Electrical Engineering and Computer Science, Seoul National University, Seoul 151-742 (Korea, Republic of); Byun, Kyung Min [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Kim, Kyujung; Kim, Donghyun [Program of Nanomedical Science and Technology, Yonsei University, Seoul 120-749 (Korea, Republic of); Ma, Kyungjae; Oh, Youngjin [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Sung Guk [College of Veterinary Medicine, Cornell University, Ithaca, New York 14853 (United States); Shuler, Michael L, E-mail: kmbyun@khu.ac.kr [Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2010-09-03

    We demonstrated enhanced localized surface plasmon resonance (SPR) biosensing based on subwavelength gold nanoarrays built on a thin gold film. Arrays of nanogratings (1D) and nanoholes (2D) with a period of 200 nm were fabricated by electron-beam lithography and used for the detection of avian influenza DNA hybridization. Experimental results showed that both nanoarrays provided significant sensitivity improvement and, especially, 1D nanogratings exhibited higher SPR signal amplification compared with 2D nanohole arrays. The sensitivity enhancement is associated with changes in surface-limited reaction area and strong interactions between bound molecules and localized plasmon fields. Our approach is expected to improve both the sensitivity and sensing resolution and can be applicable to label-free detection of DNA without amplification by polymerase chain reaction.

  10. A high-order boundary integral method for surface diffusions on elastically stressed axisymmetric rods.

    Science.gov (United States)

    Li, Xiaofan; Nie, Qing

    2009-07-01

    Many applications in materials involve surface diffusion of elastically stressed solids. Study of singularity formation and long-time behavior of such solid surfaces requires accurate simulations in both space and time. Here we present a high-order boundary integral method for an elastically stressed solid with axi-symmetry due to surface diffusions. In this method, the boundary integrals for isotropic elasticity in axi-symmetric geometry are approximated through modified alternating quadratures along with an extrapolation technique, leading to an arbitrarily high-order quadrature; in addition, a high-order (temporal) integration factor method, based on explicit representation of the mean curvature, is used to reduce the stability constraint on time-step. To apply this method to a periodic (in axial direction) and axi-symmetric elastically stressed cylinder, we also present a fast and accurate summation method for the periodic Green's functions of isotropic elasticity. Using the high-order boundary integral method, we demonstrate that in absence of elasticity the cylinder surface pinches in finite time at the axis of the symmetry and the universal cone angle of the pinching is found to be consistent with the previous studies based on a self-similar assumption. In the presence of elastic stress, we show that a finite time, geometrical singularity occurs well before the cylindrical solid collapses onto the axis of symmetry, and the angle of the corner singularity on the cylinder surface is also estimated.

  11. Synthesis methods of gold nanoparticles for Localized Surface Plasmon Resonance (LSPR sensor applications

    Directory of Open Access Journals (Sweden)

    Samsuri Nurul Diyanah

    2017-01-01

    Full Text Available Gold nanoparticles (GNPs have been known as an excellent characteristic for Local Surface Plasmon Resonance (LSPR sensors due to their sensitive spectral response to the local environment of the nanoparticle surface and ease of monitoring the light signal due to their strong scattering or absorption. Prior the technologies, GNPs based LSPR has been commercialized and have become a central tool for characterizing and quantifying in various field. In this review, we presented a brief introduction on the history of surface plasmon, the theory behind the surface plasmon resonance (SPR and the principles of LSPR. We also reported on the synthetization as well of the properties of the GNPs and the applications in current LSPR sensors.

  12. 3D Interest Point Detection using Local Surface Characteristics with Application in Action Recognition

    DEFF Research Database (Denmark)

    Holte, Michael Boelstoft

    2014-01-01

    . The proposed Difference-of-Normals (DoN) 3D IP detector operates on the surface mesh, and evaluates the surface structure (curvature) locally (per vertex) in the mesh data. We present an exam- ple of application in action recognition from a sequence of 3-dimensional geometrical data, where local 3D motion de...

  13. Surface localization of the nuclear receptor CAR in influenza A virus-infected cells

    International Nuclear Information System (INIS)

    Takahashi, Tadanobu; Moriyama, Yusuke; Ikari, Akira; Sugatani, Junko; Suzuki, Takashi; Miwa, Masao

    2008-01-01

    Constitutive active/androstane receptor CAR is a member of the nuclear receptors which regulate transcription of xenobiotic metabolism enzymes. CAR is usually localized in the cytosol and nucleus. Here, we found that CAR was localized at the cell surface of influenza A virus (IAV)-infected cells. Additionally, we demonstrated that expression of a viral envelope glycoprotein, either hemagglutinin (HA) or neuraminidase (NA), but not viral nucleoprotein (NP), was responsible for this localization. This report is the first demonstration of CAR at the surface of tissue culture cells, and suggests that CAR may exert the IAV infection mechanism

  14. Prediction of macroscopic and local stress-strain behaviors of perforated plates under primary and secondary creep conditions

    International Nuclear Information System (INIS)

    Igari, Toshihide; Tokiyoshi, Takumi; Mizokami, Yorikata

    2000-01-01

    Prediction methods of macroscopic and local creep behaviors of perforated plates are examined in order to apply these methods to the structural design of perforated structures such as heat exchangers used in elevated temperatures. Both primary and secondary creeps are considered for predicting macroscopic and local creep behaviors of perorated plates which are made of actual structural materials. Both uniaxial and multiaxial loading of perforated plates are taken into consideration. The concept of effective stress is applied to the prediction of macroscopic creep behaviors of perforated plates, and the predicted results are compared with the numerical results by FEM for the unit section of perorated plated under creep, in order to confirm the propriety of the proposed method. Based on the idea that stress exponents in creep equations govern the stress distribution of perforated plates, a modified Neuber's rule is used for predicting local stress and strain concentrations. The propriety of this prediction method is shown through a comparison of the prediction with the numerical results by FEM for the unit section of perforated plates under creep, and experimental results by the Moire method. (author)

  15. Interaction of stress and phase transformations during thermochemical surface engineering

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard

    and diffusion kinetics to simulate the evolution of composition-depth and stress-depth profiles resulting from nitriding of austenitic stainless steel. The model takes into account a composition-dependent diffusion coefficient of nitrogen in expanded austenite, short range ordering (trapping) of nitrogen atoms......Low temperature nitriding of austenitic stainless steel causes a surface zone of expanded austenite, which improves the wear resistance of the stainless steel while preserving the stainless behavior. During nitriding huge residual stresses are introduced in the treated zone, arising from the volume...... expansion that accompanies the dissolution of high nitrogen contents in expanded austenite. An intriguing phenomenon during low-temperature nitriding, is that the residual stresses evoked by dissolution of nitrogen in the solid state, affect the thermodynamics and the diffusion kinetics of nitrogen...

  16. A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

    Science.gov (United States)

    Mathew, Ribu; Ravi Sankar, A.

    2018-06-01

    In the last decade, microelectromechanical systems (MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications, especially in the field of chemical and biological sensing. Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times, numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail. In addition to the design-, fabrication-, and performance-related factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.[Figure not available: see fulltext.

  17. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng

    2017-03-28

    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  18. Numerical investigation on the variation of welding stresses after material removal from a thick titanium alloy plate joined by electron beam welding

    International Nuclear Information System (INIS)

    Liu, Chuan; Zhang, Jianxun; Wu, Bing; Gong, Shuili

    2012-01-01

    Highlights: → After less materials removal from the top, stresses on the bottom remain unchanged. → The transverse stress within the weld decreases significantly with material removal. → Local material removal does not influence the longitudinal stress significantly. -- Abstract: The stress modification after material removal from a 50 mm thick titanium alloy plate jointed by electron beam welding (EBW) was investigated through the finite element method (FEM). The welding experiment and milling process were carried out to experimentally determine the stresses induced by EBW and their modification after local material removal. The modification of as-welded stresses due to the local material removal method and the whole layer removal method was discussed with the finite element analysis. Investigated results showed that with less materials removal from the top, the stresses on the bottom surface remain almost unchanged; after material removal from the top and bottom part, the transverse stress on the newly-formed surface decreases significantly as compared to the as-welded stresses at the same locations; however, the stress modification only occurs at the material removal region in the case of local region removal method; the longitudinal stress decreases with the whole layer removal method while remains almost unchanged with the local region removal method.

  19. Surface plasmon quantum cascade lasers as terahertz local oscillators

    NARCIS (Netherlands)

    Hajenius, M.; Khosropanah, P.; Hovenier, J. N.; Gao, J. R.; Klapwijk, T. M.; Barbieri, S.; Dhillon, S.; Filloux, P.; Sirtori, C.; Ritchie, D. A.; Beere, H. E.

    2008-01-01

    We characterize a heterodyne receiver based on a surface-plasmon waveguide quantum cascade laser (QCL) emitting at 2.84 THz as a local oscillator, and an NbN hot electron bolometer as a mixer. We find that the envelope of the far-field pattern of the QCL is diffraction-limited and superimposed onto

  20. Localized Surface Plasmons in Vibrating Graphene Nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Li, Bo-Hong; Stassen, Erik

    2016-01-01

    in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined...... by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters...

  1. Alpha-fetoprotein detection by using a localized surface plasmon coupled fluorescence fiber-optic biosensor

    Science.gov (United States)

    Chang, Ying-Feng; Chen, Ran-Chou; Li, Ying-Chang; Yu, Chih-Jen; Hsieh, Bao-Yu; Chou, Chien

    2007-11-01

    Alpha-fetoprotein (AFP) detection by using a localized surface plasmon coupled fluorescence (LSPCF) fiber-optic biosensor is setup and experimentally demonstrated. It is based on gold nanoparticle (GNP) and coupled with localized surface plasmon wave on the surface of GNP. In this experiment, the fluorophores are labeled on anti-AFP which are bound to protein A conjugated GNP. Thus, LSPCF is excited with high efficiency in the near field of localized surface plasmon wave. Therefore, not only the sensitivity of LSPCF biosensor is enhanced but also the specific selectivity of AFP is improved. Experimentally, the ability of real time measurement in the range of AFP concentration from 0.1ng/ml to 100ng/ml was detected. To compare with conventional methods such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA), the LSPCF fiber-optic biosensor performs higher or comparable detection sensitivity, respectively.

  2. Standard practice for estimating the approximate residual circumferential stress in straight thin-walled tubing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 A qualitative estimate of the residual circumferential stress in thin-walled tubing may be calculated from the change in outside diameter that occurs upon splitting a length of the tubing. This practice assumes a linear stress distribution through the tube wall thickness and will not provide an estimate of local stress distributions such as surface stresses. (Very high local residual stress gradients are common at the surface of metal tubing due to cold drawing, peening, grinding, etc.) The Hatfield and Thirkell formula, as later modified by Sachs and Espey, provides a simple method for calculating the approximate circumferential stress from the change in diameter of straight, thin-walled, metal tubing. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  3. Poliovirus infection induces the co-localization of cellular protein SRp20 with TIA-1, a cytoplasmic stress granule protein.

    Science.gov (United States)

    Fitzgerald, Kerry D; Semler, Bert L

    2013-09-01

    Different types of environmental stress cause mammalian cells to form cytoplasmic foci, termed stress granules, which contain mRNPs that are translationally silenced. These foci are transient and dynamic, and contain components of the cellular translation machinery as well as certain mRNAs and RNA binding proteins. Stress granules are known to be induced by conditions such as hypoxia, nutrient deprivation, and oxidative stress, and a number of cellular factors have been identified that are commonly associated with these foci. More recently it was discovered that poliovirus infection also induces the formation of stress granules, although these cytoplasmic foci appear to be somewhat compositionally unique. Work described here examined the punctate pattern of SRp20 (a host cell mRNA splicing protein) localization in the cytoplasm of poliovirus-infected cells, demonstrating the partial co-localization of SRp20 with the stress granule marker protein TIA-1. We determined that SRp20 does not co-localize with TIA-1, however, under conditions of oxidative stress, indicating that the close association of these two proteins during poliovirus infection is not representative of a general response to cellular stress. We confirmed that the expression of a dominant negative version of TIA-1 (TIA-1-PRD) results in the dissociation of stress granules. Finally, we demonstrated that expression of wild type TIA-1 or dominant negative TIA-1-PRD in cells during poliovirus infection does not dramatically affect viral translation. Taken together, these studies provide a new example of the unique cytoplasmic foci that form during poliovirus infection. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Poliovirus infection induces the co-localization of cellular protein SRp20 with TIA-1, a cytoplasmic stress granule protein

    Science.gov (United States)

    Fitzgerald, Kerry D.; Semler, Bert L.

    2013-01-01

    Different types of environmental stress cause mammalian cells to form cytoplasmic foci, termed stress granules, which contain mRNPs that are translationally silenced. These foci are transient and dynamic, and contain components of the cellular translation machinery as well as certain mRNAs and RNA binding proteins. Stress granules are known to be induced by conditions such as hypoxia, nutrient deprivation, and oxidative stress, and a number of cellular factors have been identified that are commonly associated with these foci. More recently it was discovered that poliovirus infection also induces the formation of stress granules, although these cytoplasmic foci appear to be somewhat compositionally unique. Work described here examined the punctate pattern of SRp20 (a host cell mRNA splicing protein) localization in the cytoplasm of poliovirus-infected cells, demonstrating the partial co-localization of SRp20 with the stress granule marker protein TIA-1. We determined that SRp20 does not co-localize with TIA-1, however, under conditions of oxidative stress, indicating that the close association of these two proteins during poliovirus infection is not representative of a general response to cellular stress. We confirmed that the expression of a dominant negative version of TIA-1 (TIA-1-PRD) results in the dissociation of stress granules. Finally, we demonstrated that expression of wild type TIA-1 or dominant negative TIA-1-PRD in cells during poliovirus infection does not dramatically affect viral translation. Taken together, these studies provide a new example of the unique cytoplasmic foci that form during poliovirus infection. PMID:23830997

  5. The role of surface preparation in corrosion protection of copper with nanometer-thick ALD alumina coatings

    Energy Technology Data Exchange (ETDEWEB)

    Mirhashemihaghighi, Shadi; Światowska, Jolanta [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Maurice, Vincent, E-mail: vincent.maurice@chimie-paristech.fr [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Seyeux, Antoine; Klein, Lorena H. [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Salmi, Emma; Ritala, Mikko [Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Marcus, Philippe [PSL Research University, CNRS – Chimie ParisTech, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France)

    2016-11-30

    Highlights: • 10–50 nm thick alumina coatings were grown on copper by atomic layer deposition. • Surface smoothening by substrate annealing was studied as pre-deposition treatment. • Corrosion protection is promoted by pre-treatment for 10 nm but not for thicker films. • Local adhesion failure is assigned to the stresses accumulated in the thicker films. • Surface smoothening decreases the interfacial strength bearing the film stresses. - Abstract: Surface smoothening by substrate annealing was studied as a pre-treatment for improving the corrosion protection provided to copper by 10, 20 and 50 nm thick alumina coatings deposited by atomic layer deposition. The interplay between substrate surface state and deposited film thickness for controlling the corrosion protection provided by ultrathin barrier films is demonstrated. Pre-annealing at 750 °C heals out the dispersed surface heterogeneities left by electropolishing and reduces the surface roughness to less than 2 nm independently of the deposited film thickness. For 10 nm coatings, substrate surface smoothening promotes the corrosion resistance. However, for 20 and 50 nm coatings, it is detrimental to the corrosion protection due to local detachment of the deposited films. The weaker adherence of the thicker coatings is assigned to the stresses accumulated in the films with increasing deposited thickness. Healing out the local heterogeneities on the substrate surface diminishes the interfacial strength that is bearing the stresses of the deposited films, thereby increasing adhesion failure for the thicker films. Pitting corrosion occurs at the local sites of adhesion failure. Intergranular corrosion occurs at the initially well coated substrate grain boundaries because of the growth of a more defective and permeable coating at grain boundaries.

  6. Local and systemic oxidative stress and glucocorticoid receptor levels in chronic obstructive pulmonary disease patients

    Science.gov (United States)

    Zeng, Mian; Li, Yue; Jiang, Yujie; Lu, Guifang; Huang, Xiaomei; Guan, Kaipan

    2013-01-01

    BACKGROUND: Previous studies have indicated that oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). OBJECTIVES: To study local and systemic oxidative stress status in COPD patients, and to clarify the relationship between local and systemic oxidative stress. METHODS: Lipid peroxide malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD) and GSH peroxidase (GSH-PX) levels in induced sputum and plasma, as well as glucocorticoid receptor (GR) levels in peripheral blood leukocytes were examined in 43 acute exacerbation of COPD patients (group A), 35 patients with stable COPD (group B) and 28 healthy controls (14 smokers [group C]; 14 nonsmokers [group D]). RESULTS: MDA levels in induced sputum and plasma decreased progressively in groups A to D, with significant differences between any two groups (P<0.001). GSH, SOD and GSH-PX levels in both induced sputum and plasma increased progressively in groups A to D, with significant differences between any two groups (P<0.001). GR levels in peripheral blood leukocytes decreased progressively in groups D to A (all comparisons P<0.001). Pearson analysis revealed strong correlations between MDA, GSH, SOD and GSH-PX levels in plasma and induced sputum. The activity of SOD in plasma and sputum were both positively correlated with GR levels (partial correlation coefficients 0.522 and 0.574, respectively [P<0.001]). CONCLUSIONS: Oxidative stress levels were elevated in COPD patients. There was a correlation between local and systemic oxidative status in COPD, and between decreased SOD activity and decreased GR levels in COPD patients. PMID:23457673

  7. Fatigue Life Prediction of High Modulus Asphalt Concrete Based on the Local Stress-Strain Method

    Directory of Open Access Journals (Sweden)

    Mulian Zheng

    2017-03-01

    Full Text Available Previously published studies have proposed fatigue life prediction models for dense graded asphalt pavement based on flexural fatigue test. This study focused on the fatigue life prediction of High Modulus Asphalt Concrete (HMAC pavement using the local strain-stress method and direct tension fatigue test. First, the direct tension fatigue test at various strain levels was conducted on HMAC prism samples cut from plate specimens. Afterwards, their true stress-strain loop curves were obtained and modified to develop the strain-fatigue life equation. Then the nominal strain of HMAC course determined using finite element method was converted into local strain using the Neuber method. Finally, based on the established fatigue equation and converted local strain, a method to predict the pavement fatigue crack initiation life was proposed and the fatigue life of a typical HMAC overlay pavement which runs a risk of bottom-up cracking was predicted and validated. Results show that the proposed method was able to produce satisfactory crack initiation life.

  8. Local mesh refinement for incompressible fluid flow with free surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Terasaka, H.; Kajiwara, H.; Ogura, K. [Tokyo Electric Power Company (Japan)] [and others

    1995-09-01

    A new local mesh refinement (LMR) technique has been developed and applied to incompressible fluid flows with free surface boundaries. The LMR method embeds patches of fine grid in arbitrary regions of interest. Hence, more accurate solutions can be obtained with a lower number of computational cells. This method is very suitable for the simulation of free surface movements because free surface flow problems generally require a finer computational grid to obtain adequate results. By using this technique, one can place finer grids only near the surfaces, and therefore greatly reduce the total number of cells and computational costs. This paper introduces LMR3D, a three-dimensional incompressible flow analysis code. Numerical examples calculated with the code demonstrate well the advantages of the LMR method.

  9. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng; Wang, Zhihong; Whittaker, John; Lopez-royo, Francisco; Yang, Yang; Zayats, Anatoly

    2017-01-01

    that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold

  10. Transient thermal stresses in an orthotropic rectangular plate with convective heat transfer at upper and lower surfaces

    International Nuclear Information System (INIS)

    Sugano, Yoshihiro; Nakanishi, Takanori; Ito, Masahiko; Saito, Koichi.

    1982-01-01

    Recently, anisotropic materials have been used widely for reactor core elements and fast flying objects, therefore, the problem of thermal stress in anisotropic bodies has been studied actively. In this study, the unsteady plane thermal stress in an orthotropic rectangular thin plate heated by the temperature of ambient medium was analyzed, taking the heat transfer on both surfaces into account. The influence that the anisotropy of material constants and the heat transfer on both surfaces exert on the temperature and thermal stress of the plate was examined. Moreover, in order to investigate into the effect of the aspect ratio of the plate on the temperature and thermal stress, the unsteady distributions of temperature and thermal stress in an orthotropic semi-infinite band, of which the end surfaces are heated by ambient medium, were analyzed. The numerical calculation was carried out, and the results are shown. Before, it was difficult to satisfy the boundary condition related to shearing stress, accordingly, the analysis has not been performed, but in this study, it was shown that the analysis is possible. (Kako, I.)

  11. Two-step method to evaluate equibiaxial residual stress of metal surface based on micro-indentation tests

    International Nuclear Information System (INIS)

    Nishikawa, Masaaki; Soyama, Hitoshi

    2011-01-01

    Highlights: → The sensitivity to residual stress was improved by selecting the depth parameter. → Residual stress could be obtained while determining the effect of unknown parameters. → The estimated residual stress agreed well with those of X-ray diffraction. -- Abstract: The present study proposed a method to evaluate the equibiaxial compressive residual stress of a metal surface by means of a depth-sensing indentation method using a spherical indenter. Inverse analysis using the elastic-plastic finite-element model for an indentation test was established to evaluate residual stress from the indentation load-depth curve. The proposed inverse analysis utilizes two indentation test results for a reference specimen whose residual stress is already known and for a target specimen whose residual stress is unknown, in order to exclude the effect of other unknown mechanical properties, such as Young's modulus and yield stress. Residual stress estimated by using the indentation method is almost identical to that measured by X-ray diffraction for indentation loads of 0.49-0.98 N. Therefore, it can be concluded that the proposed method can effectively evaluate residual stress on metal surface.

  12. Surface shear stress dependence of gas transfer velocity parameterizations using DNS

    Science.gov (United States)

    Fredriksson, S. T.; Arneborg, L.; Nilsson, H.; Handler, R. A.

    2016-10-01

    Air-water gas-exchange is studied in direct numerical simulations (DNS) of free-surface flows driven by natural convection and weak winds. The wind is modeled as a constant surface-shear-stress and the gas-transfer is modeled via a passive scalar. The simulations are characterized via a Richardson number Ri=Bν/u*4 where B, ν, and u* are the buoyancy flux, kinematic viscosity, and friction velocity respectively. The simulations comprise 0Ric or kg=AShearu*Sc-n, Risurface-characteristics.

  13. Investigation of surface residual stress profile on martensitic stainless steel weldment with X-ray diffraction

    Directory of Open Access Journals (Sweden)

    I.I. Ahmed

    2018-04-01

    Full Text Available The development of residual stresses during fabrication is inevitable and often neglected with dire consequences during the service life of the fabricated components. In this work, the surface residual stress profile following the martensitic stainless steel (MSS pipe welding was investigated with X-ray diffraction technique. The results revealed the presence of residual stresses equilibrated across the weldment zones. Tensile residual stress observed in weld metal was balanced by compressive residual stresses in the parent material on the opposing sides of weld metal. Keywords: Residual stress, Weld, Stainless steel, X-ray, HAZ

  14. Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

    International Nuclear Information System (INIS)

    Magnier-Monin, L.

    2007-12-01

    This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)

  15. Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress, Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

    Science.gov (United States)

    Ye, Chang; Telang, Abhishek; Gill, Amrinder; Wen, Xingshuo; Mannava, Seetha R.; Qian, Dong; Vasudevan, Vijay K.

    2018-03-01

    In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile stress generated during welding and imparts beneficial compressive residual stresses. In addition, UNSM can effectively refine the grains and increase hardness in the near-surface region. Corrosion tests in boiling MgCl2 solution demonstrate that UNSM can significantly improve the corrosion resistance due to the compressive residual stresses and changes in the near-surface microstructure.

  16. An analytical method on the surface residual stress for the cutting tool orientation

    Science.gov (United States)

    Li, Yueen; Zhao, Jun; Wang, Wei

    2010-03-01

    The residual stress is measured by choosing 8 kinds orientations on cutting the H13 dies steel on the HSM in the experiment of this paper. The measured data shows on that the residual stress exists periodicity for the different rake angle (β) and side rake angle (θ) parameters, further study find that the cutting tool orientations have closed relationship with the residual stresses, and for the original of the machined residual stress on the surface from the cutting force and the axial force, it can be gained the simply model of tool-workpiece force, using the model it can be deduced the residual stress model, which is feasible to calculate the size of residual stress. And for almost all the measured residual stresses are compressed stress, the compressed stress size and the direction could be confirmed by the input data for the H13 on HSM. As the result, the residual stress model is the key for optimization of rake angle (β) and side rake angle (θ) in theory, using the theory the more cutting mechanism can be expressed.

  17. Surface mechanical property and residual stress of peened nickel-aluminum bronze determined by in-situ X-ray diffraction

    Science.gov (United States)

    Wang, Chengxi; Jiang, Chuanhai; Zhao, Yuantao; Chen, Ming; Ji, Vincent

    2017-10-01

    As one of the most important surface strengthening method, shot peening is widely used to improve the fatigue and stress corrosion crack resistance of components by introducing the refined microstructure and compressive residual stress in the surface layer. However, the mechanical properties of this thin layer are different from the base metal and are difficult to be characterized by conventional techniques. In this work, a micro uniaxial tensile tester equipped with in-situ X-ray stress analyzer was employed to make it achievable on a nickel-aluminum bronze with shot peening treatment. According to the equivalent stress-strain relationship based on Von Mises stress criterion, the Young's modulus and yield strength of the peened layer were calculated. The results showed that the Young's modulus was the same as the bulk material, and the yield strength corresponding to the permanent plastic strain of 0.2% was increased by 21% after SP. But the fractographic analysis showed that the fracture feature of the surface layer was likely to transform from the dimple to the cleavage, indicating the improved strength might be attained at the expense of ductility. The monotonic and cyclic loading were also performed via the same combined set-up. In addition, the specific relaxation behavior of compressive residual stress was quantified by linear logarithm relationship between residual stress and cycle numbers. It was found that the compressive residual stress mainly relaxed in the first few cycles, and then reached steady state with further cycles. The relaxation rate and the stable value were chiefly depended on the stress amplitude and number of cycles. The retained residual stress kept in compressive under all given applied stress levels, suggesting that the shot peening could introduce a more stable surface layer of compressive residual stress other than the elevated strength of nickel-aluminum bronze alloy.

  18. On the residual stress modeling of shot-peened AISI 4340 steel: finite element and response surface methods

    Science.gov (United States)

    Asgari, Ali; Dehestani, Pouya; Poruraminaie, Iman

    2018-02-01

    Shot peening is a well-known process in applying the residual stress on the surface of industrial parts. The induced residual stress improves fatigue life. In this study, the effects of shot peening parameters such as shot diameter, shot speed, friction coefficient, and the number of impacts on the applied residual stress will be evaluated. To assess these parameters effect, firstly the shot peening process has been simulated by finite element method. Then, effects of the process parameters on the residual stress have been evaluated by response surface method as a statistical approach. Finally, a strong model is presented to predict the maximum residual stress induced by shot peening process in AISI 4340 steel. Also, the optimum parameters for the maximum residual stress are achieved. The results indicate that effect of shot diameter on the induced residual stress is increased by increasing the shot speed. Also, enhancing the friction coefficient magnitude always cannot lead to increase in the residual stress.

  19. Water stress indices for the sugarcane crop on different irrigated surfaces

    Directory of Open Access Journals (Sweden)

    Rodrigo G. Brunini

    Full Text Available ABSTRACT Sugarcane (Saccharum officinarum L. is a crop of vital importance to Brazil, in the production of sugar and ethanol, power generation and raw materials for various purposes. Strategic information such as topography and canopy temperature can provide management technologies accessible to farmers. The objective of this study was to determine water stress indices for sugarcane in irrigated areas, with different exposures and slopes. The daily water stress index of the plants and the water potential in the soil were evaluated and the production system was analyzed. The experiment was carried out in an “Experimental Watershed”, using six surfaces, two horizontal and the other ones with 20 and 40% North and South exposure slopes. Water stress level was determined by measuring the temperatures of the vegetation cover and the ambient air. Watering was carried out using a drip irrigation system. The results showed that water stress index of sugarcane varies according to exposure and slope of the terrain, while areas whose water stress index was above 5.0 oC had lower yield values.

  20. The residual stress distribution in welded pipe inner surface of stainless steel from the nuclear power plant in Ringhals

    International Nuclear Information System (INIS)

    Larsson, L.E.

    1984-06-01

    The axial residual stress distribution on the inner surface of welded pipes of stainless steel SS 2333 (AISI 304) have been measured using the X-ray diffraction technique. Four halves of two pipes with the outer diameter of 114 mm and wall thickness of 10 mm were investigated. The result on the pipe inner surface shows compressive stresses in the weld metal and tensile stresses within a region between 8-23 mm with a maximum of 180MPa at a distance of 17 mm from the weld centerline. The maximum axial and circumferential residual stresses on the pipe outer surface are of the magnitude of 100 MPa. By cutting the pipes into two halves these stresses are relaxed by about 35 MPa. (author)

  1. The effect of deformation twinning on stress localization in a three dimensional TWIP steel microstructure

    International Nuclear Information System (INIS)

    Tari, Vahid; Kadiri, Haitham El; Oppedal, Andrew L; King, Roger L; Rollett, Anthony D; Beladi, Hossein

    2015-01-01

    We present an investigation of the effect of deformation twinning on the visco-plastic response and stress localization in a low stacking fault energy twinning-induced plasticity (TWIP) steel under uniaxial tension loading. The three-dimensional full field response was simulated using the fast Fourier transform method. The initial microstructure was obtained from a three dimensional serial section using electron backscatter diffraction. Twin volume fraction evolution upon strain was measured so the hardening parameters of the simple Voce model could be identified to fit both the stress-strain behavior and twinning activity. General trends of texture evolution were acceptably predicted including the typical sharpening and balance between the 〈1 1 1〉 fiber and the 〈1 0 0〉 fiber. Twinning was found to nucleate preferentially at grain boundaries although the predominant twin reorientation scheme did not allow spatial propagation to be captured. Hot spots in stress correlated with the boundaries of twinned voxel domains, which either impeded or enhanced twinning based on which deformation modes were active locally. (paper)

  2. On to what extent stresses resulting from the earth's surface trigger earthquakes

    Science.gov (United States)

    Klose, C. D.

    2009-12-01

    The debate on static versus dynamic earthquake triggering mainly concentrates on endogenous crustal forces, including fault-fault interactions or seismic wave transients of remote earthquakes. Incomprehensibly, earthquake triggering due to surface processes, however, still receives little scientific attention. This presentation continues a discussion on the hypothesis of how “tiny” stresses stemming from the earth's surface can trigger major earthquakes, such as for example, China's M7.9 Wenchuan earthquake of May 2008. This seismic event is thought to be triggered by up to 1.1 billion metric tons of water (~130m) that accumulated in the Minjiang River Valley at the eastern margin of the Longmen Shan. Specifically, the water level rose by ~80m (static), with additional seasonal water level changes of ~50m (dynamic). Two and a half years prior to mainshock, static and dynamic Coulomb failure stresses were induced on the nearby Beichuan thrust fault system at <17km depth. Triggering stresses were equivalent to levels of daily tides and perturbed a fault area measuring 416+/-96km^2. The mainshock ruptured after 2.5 years when only the static stressing regime was predominant and the transient stressing (seasonal water level) was infinitesimal small. The short triggering delay of about 2 years suggests that the Beichuan fault might have been near the end of its seismic cycle, which may also confirm what previous geological findings have indicated. This presentation shows on to what extend the static and 1-year periodic triggering stress perturbations a) accounted for equivalent tectonic loading, given a 4-10kyr earthquake cycle and b) altered the background seismicity beneath the valley, i.e., daily event rate and earthquake size distribution.

  3. Transient thermal stresses in a transversely isotropic finite hollow circular cylinder due to arbitrary surface heat generations

    International Nuclear Information System (INIS)

    Sugano, Yoshihiro; Nakanishi, Takanori.

    1980-01-01

    The materials macroscopically regarded as anisotropic materials such as fiber-reinforced composite materials have become to be used for the structural elements at elevated temperature, and the studies on the problem of thermal stress in anisotropic bodies are carried out actively. The unsteady thermal stress in anisotropic finite circular cylinders has not been analyzed so far. In this study, the problem of unsteady thermal stress in an anisotropic finite circular cylinder having arbitrary surface heat generation in axial direction on the internal and external surfaces, and emitting heat from both ends and the internal and external surfaces, was analyzed. For the analysis of temperature distribution, generalized finite Fourier transformation and finite Hankel transformation were used, and thermal stress and thermal displacement were analyzed by the use of the stress function of Singh. By adopting the function used for the transformation nucleus in generalized finite Fourier transformation as the stress function, the analysis was made without separating symmetric and opposite symmetric problems. Numerical calculation was carried out on the basis of the analytical results, and the effects of the anisotropy in thermal conductivity, Young's modulus and linear expansion on unsteady temperature distribution, thermal stress and thermal displacement were quantitatively examined. (Kako, I.)

  4. Design parameters for measurements of local catalytic activity on surfaces

    DEFF Research Database (Denmark)

    Johansson, Martin; Johannessen, Tue; Jørgensen, Jan Hoffmann

    2006-01-01

    Computational fluid dynamics in combination with experiments is used to characterize a gas sampling device for measurements of the local catalytic activity on surfaces. The device basically consists of a quartz capillary mounted concentrically inside an aluminum tube. Reactant gas is blown toward......, the limits of the range in reaction rate, which can be Studied are estimated. (c) 2005 Elsevier B.V. All rights reserved.......Computational fluid dynamics in combination with experiments is used to characterize a gas sampling device for measurements of the local catalytic activity on surfaces. The device basically consists of a quartz capillary mounted concentrically inside an aluminum tube. Reactant gas is blown toward...... limit for the lateral resolution of the measurement, and that a flow rate of the order of 240 (ml/min)(n) is sufficient to achieve this resolution. The sensitivity is reasonable also with high flow rates, due to the presence of a pocket of stagnant gas under the tip of the capillary. Furthermore...

  5. Residual-stresses in austenitic stainless-steel primary coolant pipes and welds of pressurized-water reactors

    International Nuclear Information System (INIS)

    Faure, F.; Leggatt, R.H.

    1996-01-01

    Surface and through thickness residual stress measurements were performed on an aged cast austenitic-ferritic stainless steel pipe and on an orbital TIG weld representative of those of primary coolant pipes in pressurized water reactors. An abrasive-jet hole drilling method and a block removal and layering method were used. Surface stresses and through thickness stress profiles are strongly dependent upon heat treatments, machining and welding operations. In the aged cast stainless steel pipe, stresses ranged between -250 and +175 MPa. On and near the orbital TIG weld, the outside surface of the weld was in tension both in the axial and hoop directions, with maximum values reaching 420 MPa in the weld. On the inside surface, the hoop stresses were compressive, reaching -300 MPa. However, the stresses in the axial direction at the root of the weld were tensile within 4 mm depth from the inside surface, locally reaching 280 MPa. (author)

  6. Coral seas in fifty years: Need for local policies

    Science.gov (United States)

    Longley, P.; Cheng, N. S.; Fontaine, R. M.; Horton, K.; Bhattacharya, A.

    2017-12-01

    Arising stressors from both global and local sources threaten coral reefs, with studies indicating that local and global sources might reduce coral resilience. Local sources include sediment stress and nutrient stress from fishing; global sources include increasing sea surface temperature and ocean acidification. Through an in-depth review and re-analysis of published work, conducted under the scope of a course in the spring of 2017 semester and follow up research over the summer of 2017 and fall of 2017, students in Environmental Studies Course, ENVS 4100: Coral reefs, at the University of Colorado Boulder have developed a framework to initiate a discussion of global and local policies focused on protection of coral reefs. The research aims to assess current threats and suggest mitigation efforts. The paper uses secondary research to analyze impact of ocean acidification on aragonite saturation levels, current thermal stress, nutrient stress, and sediment factors that influence the health of coral and its surrounding ecosystem over the Common Era. Case studies in this paper include the Caribbean and Red Sea coral reefs, due to the variation of the atmosphere, temperature, and human activity in these regions. This paper intends to offer sufficient evidence that will lead to appropriate policy decisions that pertain to reef conservation.

  7. Simulation of surface crack initiation induced by slip localization and point defects kinetics

    International Nuclear Information System (INIS)

    Sauzay, Maxime; Liu, Jia; Rachdi, Fatima

    2014-01-01

    Crack initiation along surface persistent slip bands (PSBs) has been widely observed and modelled. Nevertheless, from our knowledge, no physically-based fracture modelling has been proposed and validated with respect to the numerous recent experimental data showing the strong relationship between extrusion and microcrack initiation. The whole FE modelling accounts for: - localized plastic slip in PSBs; - production and annihilation of vacancies induced by cyclic slip. If temperature is high enough, point defects may diffuse in the surrounding matrix due to large concentration gradients, allowing continuous extrusion growth in agreement with Polak's model. At each cycle, the additional atoms diffusing from the matrix are taken into account by imposing an incremental free dilatation; - brittle fracture at the interfaces between PSBs and their surrounding matrix which is simulated using cohesive zone modelling. Any inverse fitting of parameter is avoided. Only experimental single crystal data are used such as hysteresis loops and resistivity values. Two fracture parameters are required: the {111} surface energy which depends on environment and the cleavage stress which is predicted by the universal binding energy relationship. The predicted extrusion growth curves agree rather well with the experimental data published for copper and the 316L steel. A linear dependence with respect to PSB length, thickness and slip plane angle is predicted in agreement with recent AFM measurement results. Crack initiation simulations predict fairly well the effects of PSB length and environment for copper single and poly-crystals. (authors)

  8. Effect of the plate surface characteristics and gap height on yield stresses of a magnetorheological fluid

    International Nuclear Information System (INIS)

    Jonkkari, I; Syrjala, S; Kostamo, E; Kostamo, J; Pietola, M

    2012-01-01

    Effects of the plate material, surface roughness and measuring gap height on static and dynamic yield stresses of a magnetorheological (MR) fluid were investigated with a commercial plate–plate magnetorheometer. Magnetic and non-magnetic plates with smooth (Ra ∼ 0.3 μm) and rough (Ra ∼ 10 μm) surface finishes were used. It was shown by Hall probe measurements and finite element simulations that the use of magnetic plates or higher gap heights increases the level of magnetic flux density and changes the shape of the radial flux density profile. The yield stress increase caused by these factors was determined and subtracted from the measured values in order to examine only the effect of the wall characteristics or the gap height. Roughening of the surfaces offered a significant increase in the yield stresses for non-magnetic plates. With magnetic plates the yield stresses were higher to start with, but roughening did not increase them further. A significant part of the difference in measured stresses between rough non-magnetic and magnetic plates was caused by changes in magnetic flux density rather than by better contact of the particles to the plate surfaces. In a similar manner, an increase in gap height from 0.25 to 1.00 mm can lead to over 20% increase in measured stresses due to changes in the flux density profile. When these changes were compensated the dynamic yield stresses generally remained independent of the gap height, even in the cases where it was obvious that the wall slip was present. This suggests that with MR fluids the wall slip cannot be reliably detected by comparison of flow curves measured at different gap heights. (paper)

  9. An interactive local flattening operator to support digital investigations on artwork surfaces.

    Science.gov (United States)

    Pietroni, Nico; Massimiliano, Corsini; Cignoni, Paolo; Scopigno, Roberto

    2011-12-01

    Analyzing either high-frequency shape detail or any other 2D fields (scalar or vector) embedded over a 3D geometry is a complex task, since detaching the detail from the overall shape can be tricky. An alternative approach is to move to the 2D space, resolving shape reasoning to easier image processing techniques. In this paper we propose a novel framework for the analysis of 2D information distributed over 3D geometry, based on a locally smooth parametrization technique that allows us to treat local 3D data in terms of image content. The proposed approach has been implemented as a sketch-based system that allows to design with a few gestures a set of (possibly overlapping) parameterizations of rectangular portions of the surface. We demonstrate that, due to the locality of the parametrization, the distortion is under an acceptable threshold, while discontinuities can be avoided since the parametrized geometry is always homeomorphic to a disk. We show the effectiveness of the proposed technique to solve specific Cultural Heritage (CH) tasks: the analysis of chisel marks over the surface of a unfinished sculpture and the local comparison of multiple photographs mapped over the surface of an artwork. For this very difficult task, we believe that our framework and the corresponding tool are the first steps toward a computer-based shape reasoning system, able to support CH scholars with a medium they are more used to. © 2011 IEEE

  10. The microfluidic probe: operation and use for localized surface processing.

    Science.gov (United States)

    Perrault, Cecile M; Qasaimeh, Mohammad A; Juncker, David

    2009-06-04

    Microfluidic devices allow assays to be performed using minute amounts of sample and have recently been used to control the microenvironment of cells. Microfluidics is commonly associated with closed microchannels which limit their use to samples that can be introduced, and cultured in the case of cells, within a confined volume. On the other hand, micropipetting system have been used to locally perfuse cells and surfaces, notably using push-pull setups where one pipette acts as source and the other one as sink, but the confinement of the flow is difficult in three dimensions. Furthermore, pipettes are fragile and difficult to position and hence are used in static configuration only. The microfluidic probe (MFP) circumvents the constraints imposed by the construction of closed microfluidic channels and instead of enclosing the sample into the microfluidic system, the microfluidic flow can be directly delivered onto the sample, and scanned across the sample, using the MFP. . The injection and aspiration openings are located within a few tens of micrometers of one another so that a microjet injected into the gap is confined by the hydrodynamic forces of the surrounding liquid and entirely aspirated back into the other opening. The microjet can be flushed across the substrate surface and provides a precise tool for localized deposition/delivery of reagents which can be used over large areas by scanning the probe across the surface. In this video we present the microfluidic probe (MFP). We explain in detail how to assemble the MFP, mount it atop an inverted microscope, and align it relative to the substrate surface, and finally show how to use it to process a substrate surface immersed in a buffer.

  11. Localization and expression of MreB in Vibrio parahaemolyticus under different stresses.

    Science.gov (United States)

    Chiu, Shen-Wen; Chen, Shau-Yan; Wong, Hin-chung

    2008-11-01

    MreB, the homolog of eukaryotic actin, may play a vital role when prokaryotes cope with stress by altering their spatial organization, including their morphology, subcellular architecture, and localization of macromolecules. This study investigates the behavior of MreB in Vibrio parahaemolyticus under various stresses. The behavior of MreB was probed using a yellow fluorescent protein-MreB conjugate in merodiploid strain SC9. Under normal growth conditions, MreB formed helical filaments in exponential-phase cells. The shape of starved or stationary-phase cells changed from rods to small spheroids. The cells differentiated into the viable but nonculturable (VBNC) state with small spherical cells via a "swelling-waning" process. In all cases, drastic remodeling of the MreB cytoskeleton was observed. MreB helices typically were loosened and fragmented into short filaments, arcs, and spots in bacteria under these stresses. The disintegrated MreB exhibited a strong tendency to attach to the cytoplasmic membrane. The expression of mreB generally declined in bacteria in the stationary phase and under starvation but was upregulated during the initial periods of cold shock and VBNC state differentiation and decreased afterwards. Our findings demonstrated the behavior of MreB in the morphological changes of V. parahaemolyticus under intrinsic or extrinsic stresses and may have important implications for studying the cellular stress response and aging.

  12. Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models

    Energy Technology Data Exchange (ETDEWEB)

    Saji, N.H.; Goswami, B.N. [Indian Inst. of Sci., Bangalore (India). Centre for Atmos. and Oceanic Sci.

    1997-08-01

    The mean state of the tropical atmosphere is important as the nature of the coupling between the ocean and the atmosphere depends nonlinearly on the basic state of the coupled system. The simulation of the annual cycle of the tropical surface wind stress by 17 atmospheric general circulation models (AGCMs) is examined and intercompared. The models considered were part of the atmospheric model intercomparison project (AMIP) and were integrated with observed sea surface temperature (SST) for the decade 1979-1988. Several measures have been devised to intercompare the performance of the 17 models on global tropical as well as regional scales. Within the limits of observational uncertainties, the models under examination simulate realistic tropical area-averaged zonal and meridional annual mean stresses. This is a noteworthy improvement over older generation low resolution models which were noted for their simulation of surface stresses considerably weaker than the observations. The models also simulate realistic magnitudes of the spatial distribution of the annual mean surface stress field and are seen to reproduce realistically its observed spatial pattern. Similar features are observed in the simulations of the annual variance field. The models perform well over almost all the tropical regions apart from a few. Of these, the simulations over Somali are interesting. Over this region, the models are seen to underestimate the annual mean zonal and meridional stresses. There is also wide variance between the different models in simulating these quantities. 44 refs.

  13. Photodynamic Therapy Oxidative Stress as a Molecular Switch Controlling Therapeutic Gene Expression for the Treatment of Locally Recurrent Breast Carcinoma

    National Research Council Canada - National Science Library

    Gomer, Charles

    2002-01-01

    ... a procedure offering local tumoricidal activity. We have demonstrated that PDT-mediated oxidative stress is a strong transcriptional inducer of stress proteins belonging to the heat shock protein (hsp...

  14. Non-Amontons-Coulomb local friction law of randomly rough contact interfaces with rubber

    OpenAIRE

    Nguyen, D. T.; Wandersman, E.; Prevost, A.; Chenadec, Y. Le; Fretigny, C.; Chateauminois, A.

    2017-01-01

    We report on measurements of the local friction law at a multi-contact interface formed between a smooth rubber and statistically rough glass lenses, under steady state friction. Using contact imaging, surface displacements are measured, and inverted to extract both distributions of frictional shear stress and contact pressure with a spatial resolution of about 10~$\\mu$m. For a glass surface whose topography is self-affine with a Gaussian height asperity distribution, the local frictional she...

  15. Stress relieving procedure and facility by shot-peening the inside surface of NPP steam generators tubes

    International Nuclear Information System (INIS)

    Banica, I.; Maioru, H.

    1994-01-01

    Residual stress relieving of the transition zones between the deformed part and the non deformed part of the heat exchanger tubes expanded in tube sheets of the NPP equipment, is a technological problem attacked on international level as well as on national level through the continuing programme initiated by ICEMENERG. The most recent statistical data point out that over 75% of tube failures are taking place in the tube-to-tubesheet connection zone, a great number of them being produced in this area by intergranular attack and stress corrosion cracking. The increased occurrence of these incidents is explained first by the existence of residual stresses inside tube surfaces, induced by expanding the tubes. Relieving these residual stresses is the purpose of the outlined procedure and it is achieved by overlapping effects (compression stresses added over tensile stresses). In this paper aspects of the procedure are presented and also a facility is described for stress relieving by introducing compressive stresses from uniform and generalized collisions of the inside surface with micro balls of great kinetic energy carried by a pressurized gas. The stress relieving facility can be acted by remote control, the whole process being completely automatic. The procedure aims to the operation maintenance of the NPP steam generators. (Author)

  16. The surface chemistry of metal-oxygen interactions

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Baroni, Stefano

    1997-01-01

    We report on a computational study of the clean and oxygen-covered Rh(110) surface, based on density-functional theory within the local-density approximation. We have used plane-wave basis sets and Vanderbilt ultra-soft pseudopotentials. For the clean surface, we present results for the equilibrium...... structure, surface energy and surface stress of the unreconstructed and (1 x 2) reconstructed structures. For the oxygen-covered surface we have performed a geometry optimization at 0.5, 1, and 2 monolayer oxygen coverages, and we present results for the equilibrium configurations, workfunctions and oxygen...

  17. Residual stress relaxation due to fretting fatigue in shot peened surfaces of Ti-6Al-4V

    International Nuclear Information System (INIS)

    Martinez, S.A.; Blodgett, M.P.; Mall, S.; Sathish, S.; Namjoshi, S.

    2003-01-01

    Fretting fatigue occurs at locations where the materials are sliding against each other under load. In order to enhance the fatigue life under fretting conditions the surface of the component is shot peened. In general, the shot peening process produces a compressive stress on the surface of the material, thereby increasing the resistance of the material to crack initiation. This paper presents the relaxation of residual stress caused during fretting fatigue. X-ray diffraction has been utilized as the method to measure residual stress in fretting fatigued samples of Ti-6Al-4V

  18. Physical exercise prevents stress-induced activation of granule neurons and enhances local inhibitory mechanisms in the dentate gyrus.

    Science.gov (United States)

    Schoenfeld, Timothy J; Rada, Pedro; Pieruzzini, Pedro R; Hsueh, Brian; Gould, Elizabeth

    2013-05-01

    Physical exercise is known to reduce anxiety. The ventral hippocampus has been linked to anxiety regulation but the effects of running on this subregion of the hippocampus have been incompletely explored. Here, we investigated the effects of cold water stress on the hippocampus of sedentary and runner mice and found that while stress increases expression of the protein products of the immediate early genes c-fos and arc in new and mature granule neurons in sedentary mice, it has no such effect in runners. We further showed that running enhances local inhibitory mechanisms in the hippocampus, including increases in stress-induced activation of hippocampal interneurons, expression of vesicular GABA transporter (vGAT), and extracellular GABA release during cold water swim stress. Finally, blocking GABAA receptors in the ventral hippocampus, but not the dorsal hippocampus, with the antagonist bicuculline, reverses the anxiolytic effect of running. Together, these results suggest that running improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus.

  19. Nanoscopic morphological changes in yeast cell surfaces caused by oxidative stress: an atomic force microscopic study.

    Science.gov (United States)

    Canetta, Elisabetta; Walker, Graeme M; Adya, Ashok K

    2009-06-01

    Nanoscopic changes in the cell surface morphology of the yeasts Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354), due to their exposure to varying concentrations of hydrogen peroxide (oxidative stress), were investigated using an atomic force microscope (AFM). Increasing hydrogen peroxide concentration led to a decrease in cell viabilities and mean cell volumes, and an increase in the surface roughness of the yeasts. In addition, AFM studies revealed that oxidative stress caused cell compression in both S. cerevisiae and Schiz. pombe cells and an increase in the number of aged yeasts. These results confirmed the importance and usefulness of AFM in investigating the morphology of stressed microbial cells at the nanoscale. The results also provided novel information on the relative oxidative stress tolerance of S. cerevisiae and Schiz. pombe.

  20. An Improved Local Gradient Method for Sea Surface Wind Direction Retrieval from SAR Imagery

    Directory of Open Access Journals (Sweden)

    Lizhang Zhou

    2017-06-01

    Full Text Available Sea surface wind affects the fluxes of energy, mass and momentum between the atmosphere and ocean, and therefore regional and global weather and climate. With various satellite microwave sensors, sea surface wind can be measured with large spatial coverage in almost all-weather conditions, day or night. Like any other remote sensing measurements, sea surface wind measurement is also indirect. Therefore, it is important to develop appropriate wind speed and direction retrieval models for different types of microwave instruments. In this paper, a new sea surface wind direction retrieval method from synthetic aperture radar (SAR imagery is developed. In the method, local gradients are computed in frequency domain by combining the operation of smoothing and computing local gradients in one step to simplify the process and avoid the difference approximation. This improved local gradients (ILG method is compared with the traditional two-dimensional fast Fourier transform (2D FFT method and local gradients (LG method, using interpolating wind directions from the European Centre for Medium-Range Weather Forecast (ECMWF reanalysis data and the Cross-Calibrated Multi-Platform (CCMP wind vector product. The sensitivities to the salt-and-pepper noise, the additive noise and the multiplicative noise are analyzed. The ILG method shows a better performance of retrieval wind directions than the other two methods.

  1. Gold Nanoparticles with Externally Controlled, Reversible Shifts of Local Surface Plasmon Resonance Bands

    Science.gov (United States)

    Yavuz, Mustafa S.; Jensen, Gary C.; Penaloza, David P.; Seery, Thomas A. P.; Pendergraph, Samuel A.; Rusling, James F.; Sotzing, Gregory A.

    2010-01-01

    We have achieved reversible tunability of local surface plasmon resonance in conjugated polymer functionalized gold nanoparticles. This property was facilitated by the preparation of 3,4-ethylenedioxythiophene (EDOT) containing polynorbornene brushes on gold nanoparticles via surface-initiated ring-opening metathesis polymerization. Reversible tuning of the surface plasmon band was achieved by electrochemically switching the EDOT polymer between its reduced and oxidized states. PMID:19839619

  2. Stress field of a near-surface basal screw dislocation in elastically anisotropic hexagonal crystals

    Directory of Open Access Journals (Sweden)

    Valeri S. Harutyunyan

    2017-11-01

    Full Text Available In this study, we derive and analyze the analytical expressions for stress components of the dislocation elastic field induced by a near-surface basal screw dislocation in a semi-infinite elastically anisotropic material with hexagonal crystal lattice. The variation of above stress components depending on “free surface–dislocation” distance (i.e., free surface effect is studied by means of plotting the stress distribution maps for elastically anisotropic crystals of GaN and TiB2 that exhibit different degrees of elastic anisotropy. The dependence both of the image force on a screw dislocation and the force of interaction between two neighboring basal screw dislocations on the “free surface–dislocation” distance is analyzed as well. The influence of elastic anisotropy on the latter force is numerically analyzed for GaN and TiB2 and also for crystals of such highly elastically-anisotropic materials as Ti, Zn, Cd, and graphite. The comparatively stronger effect of the elastic anisotropy on dislocation-induced stress distribution quantified for TiB2 is attributed to the higher degree of elastic anisotropy of this compound in comparison to that of the GaN. For GaN and TiB2, the dislocation stress distribution maps are highly influenced by the free surface effect at “free surface–dislocation” distances roughly smaller than ≈15 and ≈50 nm, respectively. It is found that, for above indicated materials, the relative decrease of the force of interaction between near-surface screw dislocations due to free surface effect is in the order Ti > GaN > TiB2 > Zn > Cd > Graphite that results from increase of the specific shear anisotropy parameter in the reverse order Ti < GaN < TiB2 < Zn < Cd < Graphite. The results obtained in this study are also applicable to the case when a screw dislocation is situated in the “thin film–substrate” system at a (0001 basal interface between the film and substrate provided that the elastic constants

  3. Humeral stress remodelling locations differ in Thoroughbred racehorses training and racing on dirt compared to synthetic racetrack surfaces.

    Science.gov (United States)

    Dimock, A N; Hoffman, K D; Puchalski, S M; Stover, S M

    2013-03-01

    Veterinarians have observed a putative change in the location of humeral stress remodelling in Thoroughbred racehorses with change from dirt to synthetic racetrack surfaces. To determine whether the location and severity of humeral stress remodelling differs between Thoroughbred racehorses exercising on dirt and synthetic racetrack surfaces, the potential significance of different locations of stress remodelling, and the potential usefulness of scintigraphy for prevention of complete humeral fracture. Scintigraphic images of humeri from 841 Thoroughbred racehorses at 3 racetracks during 2 years before and after conversion from dirt to synthetic surfaces were evaluated for location and severity of lesions. The effects of surface on lesion distributions were examined using Chi-square or Fisher's exact tests. Archived fractured humeri were examined to determine the location and severity of stress remodelling associated with complete fracture. Databases were queried to determine whether racehorses with scintigraphic lesions suffered humeral fracture and whether racehorses with a complete humeral fracture had had a scintigraphic examination. Horses at synthetic racetracks had a greater proportion of distal humeral lesions, whereas horses at dirt racetracks had a greater proportion of caudoproximal lesions (Pdirt surfaces, and, by inference, for horses examined using scintigraphy. © 2012 EVJ Ltd.

  4. Expanded heat treatment to form residual compressive hoop stress on inner surface of zirconium alloy tubing

    International Nuclear Information System (INIS)

    Megata, Masao

    1997-01-01

    A specific heat treatment process that introduces hoop stress has been developed. This technique can produce zirconium alloy tubing with a residual compressive hoop stress near the inner surface by taking advantage of the mechanical anisotropy in hexagonal close-packed zirconium crystal. Since a crystal having its basal pole parallel to the tangential direction of the tubing is easier to exhibit plastic elongation under the hoop stress than that having its basal pole parallel to the radial direction, the plastic and elastic elongation can coexist under a certain set of temperature and hoop stress conditions. The mechanical anisotropy plays a role to extend the coexistent stress range. Thus, residual compressive hoop stress is formed at the inner surface where more plastic elongation occurs during the heat treatment. This process is referred to as expanded heat treatment. Since this is a fundamental crystallographic principle, it has various applications. The application to improve PCI/SCC (pellet cladding interaction/stress corrosion cracking) properties of water reactor fuel cladding is promising. Excellent results were obtained with laboratory-scale heat treatment and an out-reactor iodine SCC test. These results included an extension of the time to SCC failure. (author)

  5. A countermeasure for external stress corrosion cracking in piping components by means of residual stress improvement on the outer surface

    International Nuclear Information System (INIS)

    Tanaka, Yasuhiro; Umemoto, Tadahiro

    1988-01-01

    Many techniques have been proposed as countermeasures for the External Stress Corrosion Cracking (ESCC) on austenitic stainless steel piping caused by sea salt particles. However, not one seems perfect. The method proposed here is an expansion of IHSI (Induction Heating Stress Improvement) which has been successfully implemented in many nuclear power plants as a remedy for Intergranular Stress Corrossion Cracking. The proposed method named EIHSI (External IHSI) can make the residual stress compressive on the outer surface of the piping components. In order to confirm the effectiveness of EIHSI, one series of tests were conducted on a weld joint between the pipe flange and the straight pipe. The measured residual stresses and also the results of the cracking test revealed that EIHSI is a superior method to suppress the ESCC. The outline of EIHSI and the verification tests are presented in this paper. (author)

  6. Surface association and the MreB cytoskeleton regulate pilus production, localization and function in Pseudomonas aeruginosa.

    Science.gov (United States)

    Cowles, Kimberly N; Gitai, Zemer

    2010-06-01

    Spatial organization of bacterial proteins influences many cellular processes, including division, chromosome segregation and motility. Virulence-associated proteins also localize to specific destinations within bacterial cells. However, the functions and mechanisms of virulence factor localization remain largely unknown. In this work, we demonstrate that polar assembly of the Pseudomonas aeruginosa PAO1 type IV pilus is regulated by surface association in a manner that affects gene transcription, protein levels and protein localization. We also uncover one mechanism for this regulation that acts through the actin homologue MreB. Inactivation of MreB leads to mislocalization of the pilus retraction ATPase PilT, mislocalization of the pili themselves and a reduction in motility. Furthermore, the role of MreB in polar localization of PilT is modulated by surface association, corroborating our results that environmental factors influence the regulation of pilus production. Specifically, MreB mediates both the initiation and maintenance of PilT localization when cells are grown in suspension but only affects the initiation of localization when cells are grown on a surface. Together, these results suggest that the bacterial cytoskeleton provides a mechanism for the polar localization of P. aeruginosa pili and demonstrate that protein localization may represent an important aspect of virulence factor regulation in bacterial pathogens.

  7. Laminar shear stress modulates endothelial luminal surface stiffness in a tissue-specific manner.

    Science.gov (United States)

    Merna, Nick; Wong, Andrew K; Barahona, Victor; Llanos, Pierre; Kunar, Balvir; Palikuqi, Brisa; Ginsberg, Michael; Rafii, Shahin; Rabbany, Sina Y

    2018-04-17

    Endothelial cells form vascular beds in all organs and are exposed to a range of mechanical forces that regulate cellular phenotype. We sought to determine the role of endothelial luminal surface stiffness in tissue-specific mechanotransduction of laminar shear stress in microvascular mouse cells and the role of arachidonic acid in mediating this response. Microvascular mouse endothelial cells were subjected to laminar shear stress at 4 dynes/cm 2 for 12 hours in parallel plate flow chambers that enabled real-time optical microscopy and atomic force microscopy measurements of cell stiffness. Lung endothelial cells aligned parallel to flow, while cardiac endothelial cells did not. This rapid alignment was accompanied by increased cell stiffness. The addition of arachidonic acid to cardiac endothelial cells increased alignment and stiffness in response to shear stress. Inhibition of arachidonic acid in lung endothelial cells and embryonic stem cell-derived endothelial cells prevented cellular alignment and decreased cell stiffness. Our findings suggest that increased endothelial luminal surface stiffness in microvascular cells may facilitate mechanotransduction and alignment in response to laminar shear stress. Furthermore, the arachidonic acid pathway may mediate this tissue-specific process. An improved understanding of this response will aid in the treatment of organ-specific vascular disease. © 2018 John Wiley & Sons Ltd.

  8. Mechanical stress regulates insulin sensitivity through integrin-dependent control of insulin receptor localization.

    Science.gov (United States)

    Kim, Jung; Bilder, David; Neufeld, Thomas P

    2018-01-15

    Insulin resistance, the failure to activate insulin signaling in the presence of ligand, leads to metabolic diseases, including type 2 diabetes. Physical activity and mechanical stress have been shown to protect against insulin resistance, but the molecular mechanisms remain unclear. Here, we address this relationship in the Drosophila larval fat body, an insulin-sensitive organ analogous to vertebrate adipose tissue and livers. We found that insulin signaling in Drosophila fat body cells is abolished in the absence of physical activity and mechanical stress even when excess insulin is present. Physical movement is required for insulin sensitivity in both intact larvae and fat bodies cultured ex vivo. Interestingly, the insulin receptor and other downstream components are recruited to the plasma membrane in response to mechanical stress, and this membrane localization is rapidly lost upon disruption of larval or tissue movement. Sensing of mechanical stimuli is mediated in part by integrins, whose activation is necessary and sufficient for mechanical stress-dependent insulin signaling. Insulin resistance develops naturally during the transition from the active larval stage to the immotile pupal stage, suggesting that regulation of insulin sensitivity by mechanical stress may help coordinate developmental programming with metabolism. © 2018 Kim et al.; Published by Cold Spring Harbor Laboratory Press.

  9. Effect of residual stress and hardening on grain boundary sliding in welds of low-carbon stainless steels with surface machining

    International Nuclear Information System (INIS)

    Mori, Hiroaki; Mochizuki, Masahito; Nishimoto, Kazutoshi; Katsuyama, Jinya

    2007-01-01

    To clarify the effects of residual stress and hardening on intergranular stress corrosion cracking (IGSCC) behavior in welds of low-carbon austenitic stainless steels with surface machining, residual stress and hardness were evaluated by 3-dimentional thermo elastic-plastic analysis and grain boundary sliding behavior was examined using a constant strain rate tensile test. It was revealed that grain boundary sliding occurred in the material at 561K by the tensile test with the numerically simulated tensile residual stress due to welding and surface machining. In addition, it was clarified that the grain boundary energy is raised by the grain boundary sliding. On the basis of these results, it was concluded that the cause of IGSCC in the welds of low-carbon austenitic stainless steel with surface hardening is the increase in grain boundary energy due to grain boundary sliding accelerated by residual stress of multi pass welding and surface hardening. (author)

  10. Effect of residual stress and hardening on grain boundary sliding in welds of low-carbon stainless steels with surface machining

    International Nuclear Information System (INIS)

    Mori, Hiroaki; Mochizuki, Masahito; Nishimoto, Kazutoshi; Katsuyama, Jinya

    2008-01-01

    To clarify the effects of residual stress and hardening on intergranular stress corrosion cracking (IGSCC) behavior in welds of low-carbon austenitic stainless steels with surface machining, residual stress and hardness were evaluated by 3-dimentional thermo elastic-plastic analysis and grain boundary sliding behavior was examined using a constant strain rate tensile test. It was revealed that grain boundary sliding occurred in the material at 561K by the tensile test with the numerically simulated tensile residual stress due to multi-pass welding and surface machining. In addition, it was clarified that the grain boundary energy is raised by the grain boundary sliding. On the basis of these results, it was concluded that the cause of IGSCC in the welds of low-carbon austenitic stainless steel with surface hardening is the increase in grain boundary energy due to grain boundary sliding induced by residual stress of multi pass welding and surface hardening. (author)

  11. ANGUSTIFOLIA, a Plant Homolog of CtBP/BARS Localizes to Stress Granules and Regulates Their Formation

    Directory of Open Access Journals (Sweden)

    Hemal Bhasin

    2017-06-01

    Full Text Available The ANGUSTIFOLIA (AN gene in Arabidopsis is important for a plethora of morphological phenotypes. Recently, AN was also reported to be involved in responses to biotic and abiotic stresses. It encodes a homolog of the animal C-terminal binding proteins (CtBPs. In contrast to animal CtBPs, AN does not appear to function as a transcriptional co-repressor and instead functions outside nucleus where it might be involved in Golgi-associated membrane trafficking. In this study, we report a novel and unexplored role of AN as a component of stress granules (SGs. Interaction studies identified several RNA binding proteins that are associated with AN. AN co-localizes with several messenger ribonucleoprotein granule markers to SGs in a stress dependent manner. an mutants exhibit an altered SG formation. We provide evidence that the NAD(H binding domain of AN is relevant in this context as proteins carrying mutations in this domain localize to a much higher degree to SGs and strongly reduce AN dimerization and its interaction with one interactor but not the others. Finally, we show that AN is a negative regulator of salt and osmotic stress responses in Arabidopsis suggesting a functional relevance in SGs.

  12. Stress Analysis in Polymeric Coating Layer Deposited on Rigid Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Soon Lee [Korea University of Technology and Education, School of Mechatronics Engineering, Chonan (Korea, Republic of)

    2015-08-15

    This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.

  13. Detecting local ligand-binding site similarity in nonhomologous proteins by surface patch comparison.

    Science.gov (United States)

    Sael, Lee; Kihara, Daisuke

    2012-04-01

    Functional elucidation of proteins is one of the essential tasks in biology. Function of a protein, specifically, small ligand molecules that bind to a protein, can be predicted by finding similar local surface regions in binding sites of known proteins. Here, we developed an alignment free local surface comparison method for predicting a ligand molecule which binds to a query protein. The algorithm, named Patch-Surfer, represents a binding pocket as a combination of segmented surface patches, each of which is characterized by its geometrical shape, the electrostatic potential, the hydrophobicity, and the concaveness. Representing a pocket by a set of patches is effective to absorb difference of global pocket shape while capturing local similarity of pockets. The shape and the physicochemical properties of surface patches are represented using the 3D Zernike descriptor, which is a series expansion of mathematical 3D function. Two pockets are compared using a modified weighted bipartite matching algorithm, which matches similar patches from the two pockets. Patch-Surfer was benchmarked on three datasets, which consist in total of 390 proteins that bind to one of 21 ligands. Patch-Surfer showed superior performance to existing methods including a global pocket comparison method, Pocket-Surfer, which we have previously introduced. Particularly, as intended, the accuracy showed large improvement for flexible ligand molecules, which bind to pockets in different conformations. Copyright © 2011 Wiley Periodicals, Inc.

  14. A 1-D Analytical Model for the Thermally Induced Stresses in the Mould Surface During Die Casting

    DEFF Research Database (Denmark)

    Hattel, Jesper; Hansen, Preben

    1994-01-01

    This paper presents an anlytically based method for predicting the normal stresses in a die mold surface exposed to a thermal load. A example of application of the method is the high-pressure di casting process where the surface stresses in critical cases lead to cracks. Expressions for the normal...... stresses as afunction of the thermal and mechanical properties have been developed for a casting both without and with a coating. Finally, the resulting relationships are derived and evaluated, with particular emphasis on the effect of the heat transfer coefficient between the casting and the mold....

  15. On the modelling of semi-insulating GaAs including surface tension and bulk stresses

    Energy Technology Data Exchange (ETDEWEB)

    Dreyer, W.; Duderstadt, F.

    2004-07-01

    Necessary heat treatment of single crystal semi-insulating Gallium Arsenide (GaAs), which is deployed in micro- and opto- electronic devices, generate undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid/solid interface and deviatoric stresses in the solid. The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law which gives an appropriate stress/strain relation for many solids in the small strain regime. We establish criteria, which allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law. The main objectives of this study are: (i) We develop a thermo-mechanical model that describes diffusion and interface motion, which both are strongly influenced by surface tension effects and deviatoric stresses. (ii) We give an overview and outlook on problems that can be posed and solved within the framework of the model. (iii) We calculate non-standard phase diagrams, i.e. those that take into account surface tension and non-deviatoric stresses, for GaAs above 786 C, and we compare the results with classical phase diagrams without these phenomena. (orig.)

  16. Local Tensor Radiation Conditions For Elastic Waves

    DEFF Research Database (Denmark)

    Krenk, S.; Kirkegaard, Poul Henning

    2001-01-01

    A local boundary condition is formulated, representing radiation of elastic waves from an arbitrary point source. The boundary condition takes the form of a tensor relation between the stress at a point on an arbitrarily oriented section and the velocity and displacement vectors at the point....... The tensor relation generalizes the traditional normal incidence impedance condition by accounting for the angle between wave propagation and the surface normal and by including a generalized stiffness term due to spreading of the waves. The effectiveness of the local tensor radiation condition...

  17. Bending stresses in Facetted Glass Shells

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik

    2008-01-01

    A shell structure of glass combines a highly effective structural principle with a material of optimal permeability to light. A facetted shell structure has a piecewise plane geometry, and together the facets form an approximation to a curved surface. A distributed load on a plane-based facetted...... structure will locally cause bending moments in the loaded facets. The bending stresses are dependent on the stiffness of the joints. Approximate solutions are developed to estimate the magnitude of the bending stresses. A FE-model of a facetted glass shell structure is used to validate the expressions...

  18. Changes in surface morphology and microcrack initiation in polymers under simultaneous exposure to stress and fast atom bombardment

    International Nuclear Information System (INIS)

    Michael, R.S.; Frank, S.; Stulik, D.; Dickinson, J.T.

    1987-01-01

    The authors present studies of the changes in surface morphology due to simultaneous exposure of polymers to stress and fast atom bombardment. The polymers examined were Teflon, Kapton, Nylon, and Kevlar-49. The incident particles were 6 keV xenon atoms. The authors show that in the presence of mechanical stress these polymers show topographical changes at particle doses considerably lower than similar changes produced on unstressed material. Applied stress also promotes the formation of surface microcracks which could greatly reduce mechanical strength of the material

  19. Localized Surface Plasmon-Enhanced Electroluminescence in OLEDs by Self-Assembly Ag Nanoparticle Film

    Science.gov (United States)

    He, Xiaoxiao; Wang, Wenjun; Li, Shuhong; Wang, Qingru; Zheng, Wanquan; Shi, Qiang; Liu, Yunlong

    2015-12-01

    We fabricated Ag nanoparticle (NP) film in organic light emission diodes (OLEDs), and a 23 times increase in electroluminescence (EL) at 518 nm was probed by time-resolved EL measurement. The luminance and relative external quantum efficiency (REQE) were increased by 5.4 and 3.7 times, respectively. There comes a new energy transport way that localized surface plasmons (LSPs) would absorb energy that corresponds to the electron-hole pair before recombination, promoting the formation of electron-hole pair and exciting local surface plasmon resonance (LSPR). The extended lifetime of Alq3 indicates the existence of strong interaction between LSPR and exciton, which decreases the nonradiative decay rate of OLEDs.

  20. Fatigue life prediction method for contact wire using maximum local stress

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Seok; Haochuang, Li; Seok, Chang Sung; Koo, Jae Mean [Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Ki Won; Kwon, Sam Young; Cho, Yong Hyeon [Korea Railroad Research Institute, Uiwang (Korea, Republic of)

    2015-01-15

    Railway contact wires supplying electricity to trains are exposed to repeated mechanical strain and stress caused by their own weight and discontinuous contact with a pantograph during train operation. Since the speed of railway transportation has increased continuously, railway industries have recently reported a number of contact wire failures caused by mechanical fatigue fractures instead of normal wear, which has been a more common failure mechanism. To secure the safety and durability of contact wires in environments with increased train speeds, a bending fatigue test on contact wire has been performed. The test equipment is too complicated to evaluate the fatigue characteristics of contact wire. Thus, the axial tension fatigue test was performed for a standard specimen, and the bending fatigue life for the contact wire structure was then predicted using the maximum local stress occurring at the top of the contact wire. Lastly, the tested bending fatigue life of the structure was compared with the fatigue life predicted by the axial tension fatigue test for verification.

  1. Fatigue life prediction method for contact wire using maximum local stress

    International Nuclear Information System (INIS)

    Kim, Yong Seok; Haochuang, Li; Seok, Chang Sung; Koo, Jae Mean; Lee, Ki Won; Kwon, Sam Young; Cho, Yong Hyeon

    2015-01-01

    Railway contact wires supplying electricity to trains are exposed to repeated mechanical strain and stress caused by their own weight and discontinuous contact with a pantograph during train operation. Since the speed of railway transportation has increased continuously, railway industries have recently reported a number of contact wire failures caused by mechanical fatigue fractures instead of normal wear, which has been a more common failure mechanism. To secure the safety and durability of contact wires in environments with increased train speeds, a bending fatigue test on contact wire has been performed. The test equipment is too complicated to evaluate the fatigue characteristics of contact wire. Thus, the axial tension fatigue test was performed for a standard specimen, and the bending fatigue life for the contact wire structure was then predicted using the maximum local stress occurring at the top of the contact wire. Lastly, the tested bending fatigue life of the structure was compared with the fatigue life predicted by the axial tension fatigue test for verification.

  2. Increased Adhesion of Listeria monocytogenes Strains to Abiotic Surfaces under Cold Stress

    Directory of Open Access Journals (Sweden)

    Bo-Hyung Lee

    2017-11-01

    Full Text Available Food contamination by Listeria monocytogenes remains a major concern for some food processing chains, particularly for ready-to-eat foods, including processed foods. Bacterial adhesion on both biotic and abiotic surfaces is a source of contamination by pathogens that have become more tolerant or even persistent in food processing environments, including in the presence of adverse conditions such as cold and dehydration. The most distinct challenge that bacteria confront upon entry into food processing environments is the sudden downshift in temperature, and the resulting phenotypic effects are of interest. Crystal violet staining and the BioFilm Ring Test® were applied to assess the adhesion and biofilm formation of 22 listerial strains from different serogroups and origins under cold-stressed and cold-adapted conditions. The physicochemical properties of the bacterial surface were studied using the microbial adhesion to solvent technique. Scanning electron microscopy was performed to visualize cell morphology and biofilm structure. The results showed that adhesion to stainless-steel and polystyrene was increased by cold stress, whereas cold-adapted cells remained primarily in planktonic form. Bacterial cell surfaces exhibited electron-donating properties regardless of incubation temperature and became more hydrophilic as temperature decreased from 37 to 4°C. Moreover, the adhesion of cells grown at 4°C correlated with affinity for ethyl acetate, indicating the role of cell surface properties in adhesion.

  3. The role of local strains from prior cold work on stress corrosion cracking of α-brass in Mattsson's solution

    International Nuclear Information System (INIS)

    Ulaganathan, Jaganathan; Newman, Roger C.

    2014-01-01

    The dynamic strain rate ahead of a crack tip formed during stress corrosion cracking (SCC) under a static load is assumed to arise from the crack propagation. The strain surrounding the crack tip would be redistributed as the crack grows, thereby having the effect of dynamic strain. Recently, several studies have shown cold work to cause accelerated crack growth rates during SCC, and the slip-dissolution mechanism has been widely applied to account for this via a supposedly increased crack-tip strain rate in cold worked material. While these interpretations consider cold work as a homogeneous effect, dislocations are generated inhomogeneously within the microstructure during cold work. The presence of grain boundaries results in dislocation pile-ups that cause local strain concentrations. The local strains generated from cold working α-brass by tensile elongation were characterized using electron backscatter diffraction (EBSD). The role of these local strains in SCC was studied by measuring the strain distributions from the same regions of the sample before cold work, after cold work, and after SCC. Though, the cracks did not always initiate or propagate along boundaries with pre-existing local strains from the applied cold work, the local strains surrounding the cracked boundaries had contributions from both the crack propagation and the prior cold work. - Highlights: • Plastic strain localization has a complex relationship with SCC susceptibility. • Surface relief created by cold work creates its own granular strain localization. • Cold work promotes crack growth but several other factors are involved

  4. Copper plasmonics and catalysis: role of electron-phonon interactions in dephasing localized surface plasmons

    Science.gov (United States)

    Sun, Qi-C.; Ding, Yuchen; Goodman, Samuel M.; H. Funke, Hans; Nagpal, Prashant

    2014-10-01

    Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain boundary scattering on the decay of localized surface plasmon waves. Using our quantitative analysis and different temperature dependent measurements, we show that electron-phonon interactions dominate over other scattering mechanisms in dephasing plasmon waves. While interband transitions in copper metal contributes substantially to plasmon losses, tuning surface plasmon modes to infrared frequencies leads to a five-fold enhancement in the quality factor. These findings demonstrate that conformal ALD coatings can improve the chemical stability for copper nanoparticles, even at high temperatures (>300 °C) in ambient atmosphere, and nanoscaled copper is a good alternative material for many potential applications in nanophotonics, plasmonics, catalysis and nanoscale electronics.Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain

  5. Study of the local structure of binary surfaces by electron diffraction (XPS, LEED)

    OpenAIRE

    Gereová, Katarína

    2006-01-01

    Study of local structure of binary surface with usage of ultra-thin film of cerium deposited on a Pd (111) single-crystal surface is presented. X-ray photoelectron spectroscopy and diffraction (XPS, XPD), angle resolved UV photoemission spectroscopy (ARUPS) and low energy electron diffraction (LEED) was used for our investigations. LEED and X-ray excited photoemission intensities results represent a surface-geometrical structure. As well, mapping of ultra-violet photoelectron intensities as a...

  6. Strengthening of the RAFMS RUSFER-EK181 through nano structuring surface layers

    Energy Technology Data Exchange (ETDEWEB)

    Panin, A.; Melnikova, E.A. [Tomsk State Univ., lnstitute of Strength Physics and Materials Science, SB, RAS (Russian Federation); Chernov, V.M. [Bochvar Institute of Inorganic Materials, Moscow (Russian Federation); Leontieva-Smirnova, M.V. [A.A. Bochvar Research Institute of Inorganic Materials, Moscow (Russian Federation)

    2007-07-01

    Full text of publication follows: Surface nano-structuring increases yield point and strength of the reduced activation ferritic-martensitic steel (RAFMS ) RUSREF - EK181. Ultrasonic impact treatment was used to produce a nano-structure within the surface layers of the specimens. Using scanning tunnelling microscope reveals a new mechanism of mesoscale-level plastic deformation of nano-structured surface layers of the RAFMS RUSREF - EK181 as doubled spirals of localised-plastic deformation meso-bands. A linear dependence of their sizes on thickness of strengthened layer was obtained. The effect of localised deformation meso-bands on macro-mechanical properties of a material was demonstrated. A certain combination of thermal and mechanical treatment as well as optimum proportion of nano-structured surface layer thickness to thickness of a whole specimen are necessary to achieve maximum strength values. Tests performed at high temperatures in the range from 20 to 700 deg. C shows efficiency of the surface hardening of the RAFMS RUSREF - EK181. The effect of nano-structured surface layer on the character of plastic deformation and mechanical properties of the RAFMS RUSREF - EK181 was considered in the framework of a multilevel model in which loss of shear stability and generation of structural defects occur self-consistently at various scale levels such as nano-, micro-, meso-, and macro-Chessboard like distribution of stresses and misfit deformations was theoretical and experimentally shown to appear at the 'nano-structured surface layer - bulk of material' interface. Zones of compressive normal stresses alternates with zones of tensile normal stresses as on a chessboard. Plastic shear can generate only within local zones of tensile normal stresses. Critical meso-volume of non-equilibrium states required for local structure-phase transformation can be formed within these zones. Whereas within the zones of compressive normal stresses acting from both

  7. Effects of city expansion on heat stress under climate change conditions.

    Directory of Open Access Journals (Sweden)

    Daniel Argüeso

    Full Text Available We examine the joint contribution of urban expansion and climate change on heat stress over the Sydney region. A Regional Climate Model was used to downscale present (1990-2009 and future (2040-2059 simulations from a Global Climate Model. The effects of urban surfaces on local temperature and vapor pressure were included. The role of urban expansion in modulating the climate change signal at local scales was investigated using a human heat-stress index combining temperature and vapor pressure. Urban expansion and climate change leads to increased risk of heat-stress conditions in the Sydney region, with substantially more frequent adverse conditions in urban areas. Impacts are particularly obvious in extreme values; daytime heat-stress impacts are more noticeable in the higher percentiles than in the mean values and the impact at night is more obvious in the lower percentiles than in the mean. Urban expansion enhances heat-stress increases due to climate change at night, but partly compensates its effects during the day. These differences are due to a stronger contribution from vapor pressure deficit during the day and from temperature increases during the night induced by urban surfaces. Our results highlight the inappropriateness of assessing human comfort determined using temperature changes alone and point to the likelihood that impacts of climate change assessed using models that lack urban surfaces probably underestimate future changes in terms of human comfort.

  8. Spin inelastic electron tunneling spectroscopy on local spin adsorbed on surface.

    Science.gov (United States)

    Fransson, J

    2009-06-01

    The recent experimental conductance measurements taken on magnetic impurities on metallic surfaces, using scanning tunneling microscopy technique and suggesting occurrence of inelastic scattering processes, are theoretically addressed. We argue that the observed conductance signatures are caused by transitions between the spin states that have opened due to, for example, exchange coupling between the local spins and the tunneling electrons, and are directly interpretable in terms of inelastic transitions energies. Feasible measurements using spin-polarized scanning tunneling microscopy that would enable new information about the excitation spectrum of the local spins are discussed.

  9. Surface/state correspondence and bulk local operators in pp-wave holography

    Directory of Open Access Journals (Sweden)

    Nakwoo Kim

    2015-12-01

    Full Text Available We apply the surface/state correspondence proposal of Miyaji et al. to IIB pp-waves and propose that the bulk local operators should be instantonic D-branes. In line with ordinary AdS/CFT correspondence, the bulk local operators in pp-waves also create a hole, or a boundary, in the dual gauge theory as pointed out by H. Verlinde, and by Y. Nakayama and H. Ooguri. We also present simple calculations which illustrate how to extract the spacetime metric of pp-waves from instantonic D-branes in boundary state formalism.

  10. Local properties of countercurrent stratified steam-water flow

    International Nuclear Information System (INIS)

    Kim, H.J.

    1985-10-01

    A study of steam condensation in countercurrent stratified flow of steam and subcooled water has been carried out in a rectangular channel/flat plate geometry over a wide range of inclination angles (4 0 -87 0 ) at several aspect ratios. Variables were inlet water and steam flow rates, and inlet water temperature. Local condensation rates and pressure gradients were measured, and local condensation heat transfer coefficients and interfacial shear stress were calculated. Contact probe traverses of the surface waves were made, which allowed a statistical analysis of the wave properties. The local condensation Nusselt number was correlated in terms of local water and steam Reynolds or Froude numbers, as well as the liquid Prandtl number. A turbulence-centered model developed by Theofanous, et al. principally for gas absorption in several geometries, was modified. A correlation for the interfacial shear stress and the pressure gradient agreed with measured values. Mean water layer thicknesses were calculated. Interfacial wave parameters, such as the mean water layer thickness, liquid fraction probability distribution, wave amplitude and wave frequency, are analyzed

  11. Oxidative stress does not influence local sweat rate during high-intensity exercise.

    Science.gov (United States)

    Meade, Robert D; Fujii, Naoto; Poirier, Martin P; Boulay, Pierre; Sigal, Ronald J; Kenny, Glen P

    2018-02-01

    What is the central question of this study? We evaluated whether oxidative stress attenuates the contribution of nitric oxide to sweating during high-intensity exercise. What is the main finding and its importance? In contrast to our previous report of an oxidative stress-mediated reduction in nitric oxide-dependent cutaneous vasodilatation in this cohort during intense exercise, we demonstrated no influence of local ascorbate administration on the sweating response during moderate- (∼51% peak oxygen uptake) or high-intensity exercise (∼72% peak oxygen uptake). These new findings provide important mechanistic insight into how exercise-induced oxidative stress impacts sudomotor activity. Nitric oxide (NO)-dependent sweating is diminished during high- but not moderate-intensity exercise. We evaluated whether this impairment stems from increased oxidative stress during high-intensity exercise. On two separate days, 11 young (24 ± 4 years) men cycled in the heat (35°C) at a moderate [500 W; 52 ± 6% peak oxygen uptake (V̇O2 peak )] or high (700 W; 71 ± 5% V̇O2 peak ) rate of metabolic heat production. Each session included two 30 min exercise bouts separated by a 20 min recovery period. Local sweat rate was monitored at four forearm skin sites continuously perfused via intradermal microdialysis with the following: (i) lactated Ringer solution (Control); (ii) 10 mm ascorbate (Ascorbate; non-selective antioxidant); (iii) 10 mm N G -nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor); or (iv) 10 mm ascorbate plus 10 mm l-NAME (Ascorbate + l-NAME). During moderate exercise, sweat rate was attenuated at the l-NAME and Ascorbate + l-NAME sites (both ∼1.0 mg min -1  cm -2 ; all P < 0.05) but not at the Ascorbate site (∼1.1 mg min -1  cm -2 ; both P ≥ 0.28) in comparison to the Control site (∼1.1 mg min -1  cm -2 ). However, no differences were observed between treatment sites (∼1.4 mg min -1  cm -2 ; P = 0

  12. The Effect of the Free Surface on the Singular Stress Field at the Fatigue Crack Front

    Directory of Open Access Journals (Sweden)

    Oplt Tomáš

    2017-11-01

    Full Text Available Description of stress singularity in the vicinity of a free surface is presented. Its presence causes the retardation of the fatigue crack growth in that region and fatigue crack is being curved. Numerical model is used to study dependence of the stress singularity exponent on Poisson’s ratio. Estimated values are compared to those already published. Experimentally measured angles of fatigue crack on SENB specimens confirm the relation between Poisson’s ratio and the angle between crack front and free surface.

  13. Eddy current spectroscopy for near-surface residual stress profiling in surface treated nonmagnetic engine alloys

    Science.gov (United States)

    Abu-Nabah, Bassam A.

    Recent research results indicated that eddy current conductivity measurements can be exploited for nondestructive evaluation of near-surface residual stresses in surface-treated nickel-base superalloy components. Most of the previous experimental studies were conducted on highly peened (Almen 10-16A) specimens that exhibit harmful cold work in excess of 30% plastic strain. Such high level of cold work causes thermo-mechanical relaxation at relatively modest operational temperatures; therefore the obtained results were not directly relevant to engine manufacturers and end users. The main reason for choosing peening intensities in excess of recommended normal levels was that in low-conductivity engine alloys the eddy current penetration depth could not be forced below 0.2 mm without expanding the measurements above 10 MHz which is beyond the operational range of most commercial eddy current instruments. As for shot-peened components, it was initially felt that the residual stress effect was more difficult to separate from cold work, texture, and inhomogeneity effects in titanium alloys than in nickel-base superalloys. In addition, titanium alloys have almost 50% lower electric conductivity than nickel-base superalloys; therefore require proportionally higher inspection frequencies, which was not feasible until our recent breakthrough in instrument development. Our work has been focused on six main aspects of this continuing research, namely, (i) the development of an iterative inversion technique to better retrieve the depth-dependent conductivity profile from the measured frequency-dependent apparent eddy current conductivity (AECC), (ii) the extension of the frequency range up to 80 MHz to better capture the peak compressive residual stress in nickel-base superalloys using a new eddy current conductivity measuring system, which offers better reproducibility, accuracy and measurement speed than the previously used conventional systems, (iii) the lift-off effect on

  14. Sex-specific local life-history adaptation in surface- and cave-dwelling Atlantic mollies (Poecilia mexicana).

    Science.gov (United States)

    Riesch, Rüdiger; Reznick, David N; Plath, Martin; Schlupp, Ingo

    2016-03-10

    Cavefishes have long been used as model organisms showcasing adaptive diversification, but does adaptation to caves also facilitate the evolution of reproductive isolation from surface ancestors? We raised offspring of wild-caught surface- and cave-dwelling ecotypes of the neotropical fish Poecilia mexicana to sexual maturity in a 12-month common garden experiment. Fish were raised under one of two food regimes (high vs. low), and this was crossed with differences in lighting conditions (permanent darkness vs. 12:12 h light:dark cycle) in a 2 × 2 factorial design, allowing us to elucidate potential patterns of local adaptation in life histories. Our results reveal a pattern of sex-specific local life-history adaptation: Surface molly females had the highest fitness in the treatment best resembling their habitat of origin (high food and a light:dark cycle), and suffered from almost complete reproductive failure in darkness, while cave molly females were not similarly affected in any treatment. Males of both ecotypes, on the other hand, showed only weak evidence for local adaptation. Nonetheless, local life-history adaptation in females likely contributes to ecological diversification in this system and other cave animals, further supporting the role of local adaptation due to strong divergent selection as a major force in ecological speciation.

  15. Rayleigh oscillations localized near free surface of a fcc crystal

    International Nuclear Information System (INIS)

    Kosevich, A.M.; Matsokin, D.V.; Savotchenko, S.E.

    1997-01-01

    The waves, which are localized near the free (001) surface of a fcc crystal and propagate in the [110] direction, are described using the model of central interaction of the nearest neighbors. The frequencies of these waves come into the gaps within the frequency spectrum of bulk harmonic oscillations with a fixed wave vector k component along the surface. The long-wave limit and the case of wave vectors close to the Brillouin band boundary are studied analytically. These limit dependences are in agreement with other authors results which were obtained by numerical methods. Analytical calculations in the limit intervals of k are supplemented by numerical calculations for any values of the wave vector. It is essential that these waves have a displacement component which is perpendicular to the crystal surface and can, therefore, be studied by methods of He atoms inelastic scattering

  16. The effect of ammonium partial pressure on residual stresses in surface layer of SW7M HSS steel after vacuum nitriding 'NITROVAC'79'

    International Nuclear Information System (INIS)

    Gawronski, Z.

    1997-01-01

    The effect of the nitriding atmosphere on the residual stresses in the surface layer of the SW7M HSS steel has been investigated in the work. It has been proved that the pressure influences the distribution of those stresses to a great extent. At lower pressures (20 hPa and 40 hPa) at which only one zone is being created - the one of internal nitriding, without that of ε type nitrides on the surface - the highest residual stresses are operating on the HSS steel surface itself or eventually in the subsurface region very close to the surface. In the difference, in case of higher pressure (120 hPa and 240 hPa), the highest stresses are operating at great depth 8-12 μm from the steel surface - depending on the thickness of the ε type nitride layer created on the steel surface at those pressure. All the relevant stresses are compressive one. (author). 6 refs, 4 figs, 1 tab

  17. A Simple Approach for Local Contact Angle Determination on a Heterogeneous Surface

    KAUST Repository

    Wu, Jinbo; Zhang, Mengying; Wang, Xiang; Li, Shunbo; Wen, Weijia

    2011-01-01

    We report a simple approach for measuring the local contact angle of liquids on a heterogeneous surface consisting of intersected hydrophobic and hydrophilic patch arrays, specifically by employing confocal microscopy and the addition of a very low

  18. Osmotic stress changes the expression and subcellular localization of the Batten disease protein CLN3.

    Directory of Open Access Journals (Sweden)

    Amanda Getty

    Full Text Available Juvenile CLN3 disease (formerly known as juvenile neuronal ceroid lipofuscinosis is a fatal childhood neurodegenerative disorder caused by mutations in the CLN3 gene. CLN3 encodes a putative lysosomal transmembrane protein with unknown function. Previous cell culture studies using CLN3-overexpressing vectors and/or anti-CLN3 antibodies with questionable specificity have also localized CLN3 in cellular structures other than lysosomes. Osmoregulation of the mouse Cln3 mRNA level in kidney cells was recently reported. To clarify the subcellular localization of the CLN3 protein and to investigate if human CLN3 expression and localization is affected by osmotic changes we generated a stably transfected BHK (baby hamster kidney cell line that expresses a moderate level of myc-tagged human CLN3 under the control of the human ubiquitin C promoter. Hyperosmolarity (800 mOsm, achieved by either NaCl/urea or sucrose, dramatically increased the mRNA and protein levels of CLN3 as determined by quantitative real-time PCR and Western blotting. Under isotonic conditions (300 mOsm, human CLN3 was found in a punctate vesicular pattern surrounding the nucleus with prominent Golgi and lysosomal localizations. CLN3-positive early endosomes, late endosomes and cholesterol/sphingolipid-enriched plasma membrane microdomain caveolae were also observed. Increasing the osmolarity of the culture medium to 800 mOsm extended CLN3 distribution away from the perinuclear region and enhanced the lysosomal localization of CLN3. Our results reveal that CLN3 has multiple subcellular localizations within the cell, which, together with its expression, prominently change following osmotic stress. These data suggest that CLN3 is involved in the response and adaptation to cellular stress.

  19. Role of SiC substrate surface on local tarnishing of deposited silver mirror stacks

    Science.gov (United States)

    Limam, Emna; Maurice, Vincent; Seyeux, Antoine; Zanna, Sandrine; Klein, Lorena H.; Chauveau, Grégory; Grèzes-Besset, Catherine; Savin De Larclause, Isabelle; Marcus, Philippe

    2018-04-01

    The role of the SiC substrate surface on the resistance to the local initiation of tarnishing of thin-layered silver stacks for demanding space mirror applications was studied by combined surface and interface analysis on model stack samples deposited by cathodic magnetron sputtering and submitted to accelerated aging in gaseous H2S. It is shown that suppressing the surface pores resulting from the bulk SiC material production process by surface pretreatment eliminates the high aspect ratio surface sites that are imperfectly protected by the SiO2 overcoat after the deposition of silver. The formation of channels connecting the silver layer to its environment through the failing protection layer at the surface pores and locally enabling H2S entry and Ag2S growth as columns until emergence at the stack surface is suppressed, which markedly delays tarnishing initiation and thereby preserves the optical performance. The results revealed that residual tarnishing initiation proceeds by a mechanism essentially identical in nature but involving different pathways short circuiting the protection layer and enabling H2S ingress until the silver layer. These permeation pathways are suggested to be of microstructural origin and could correspond to the incompletely coalesced intergranular boundaries of the SiO2 layer.

  20. Standard test method for determining residual stresses by the hole-drilling strain-gage method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 Residual Stress Determination: 1.1.1 This test method specifies a hole-drilling procedure for determining residual stress profiles near the surface of an isotropic linearly elastic material. The test method is applicable to residual stress profile determinations where in-plane stress gradients are small. The stresses may remain approximately constant with depth (“uniform” stresses) or they may vary significantly with depth (“non-uniform” stresses). The measured workpiece may be “thin” with thickness much less than the diameter of the drilled hole or “thick” with thickness much greater than the diameter of the drilled hole. Only uniform stress measurements are specified for thin workpieces, while both uniform and non-uniform stress measurements are specified for thick workpieces. 1.2 Stress Measurement Range: 1.2.1 The hole-drilling method can identify in-plane residual stresses near the measured surface of the workpiece material. The method gives localized measurements that indicate the...

  1. The impact of surface chemistry on the performance of localized solar-driven evaporation system.

    Science.gov (United States)

    Yu, Shengtao; Zhang, Yao; Duan, Haoze; Liu, Yanming; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-09-04

    This report investigates the influence of surface chemistry (or wettability) on the evaporation performance of free-standing double-layered thin film on the surface of water. Such newly developed evaporation system is composed of top plasmonic light-to-heat conversion layer and bottom porous supporting layer. Under solar light illumination, the induced plasmonic heat will be localized within the film. By modulating the wettability of such evaporation system through the control of surface chemistry, the evaporation rates are differentiated between hydrophilized and hydrophobized anodic aluminum oxide membrane-based double layered thin films. Additionally, this work demonstrated that the evaporation rate mainly depends on the wettability of bottom supporting layer rather than that of top light-to-heat conversion layer. The findings in this study not only elucidate the role of surface chemistry of each layer of such double-layered evaporation system, but also provide additional design guidelines for such localized evaporation system in applications including desalination, distillation and power generation.

  2. Local electrical properties of thermally grown oxide films formed on duplex stainless steel surfaces

    Science.gov (United States)

    Guo, L. Q.; Yang, B. J.; He, J. Y.; Qiao, L. J.

    2018-06-01

    The local electrical properties of thermally grown oxide films formed on ferrite and austenite surfaces of duplex stainless steel at different temperatures were investigated by Current sensing atomic force microscopy, X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). The current maps and XPS/AES analyses show that the oxide films covering austenite and ferrite surfaces formed at different temperatures exhibit different local electrical characteristics, thickness and composition. The dependence of electrical conductivity of oxide films covering austenite and ferrite surface on the formation temperature is attributed to the film thickness and semiconducting structures, which is intrinsically related to thermodynamics and kinetics process of film grown at different temperature. This is well elucidated by corresponding semiconductor band structures of oxide films formed on austenite and ferrite phases at different temperature.

  3. Surface preparation for XRD residual stress measurements; Preparacao de superficie para medicao de tensoes residuais em soldagem por DRX

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Andrii; Oliveira, Bruno Jose de; Scotti, Americo, E-mail: asmwelder@gmail.com, E-mail: brunojoliveira7@gmail.com, E-mail: ascotti@mecanica.ufu.br [Universidade Federal de Uberlandia (UFU), MG (Brazil)

    2016-10-15

    A characteristic feature of the X Ray Diffraction (XRD) method for stress determination is that measurements occur at a thin surface layer. Steel sheets come with surfaces modified by lamination, cleaning (sandblasting, grinding) and even corrosion, which induce residual stresses or roughness inherent to the material. Therefore, surface preparation prior to the residual stress measurement is essential, although no standard procedure seems to be available. A general recommendation is to remove a thin layer so that only residual stresses related to the welding process will be measured. In this study, the use of portable electrolytic equipment was evaluated for mechanized surface material removal. Chemical compositions of electrolytic solutions and the influence of current on the removed material, removal time and temperature during the process were studied. As a result, a suitable chemical solution for electro etching of low carbon steel was developed and a set of “soft” parameters that allowed the removal of about 300 um in a reasonable time was found. Higher currents reduce the removal time, yet increasing the consumption of the solution and plate temperature (which could adversely alter the microstructure or generate thermal stresses). Furthermore, the influence of these parameters on the operability of the process was demonstrated. (author)

  4. Modelling of Filling, Microstructure Formation, Local Mechanical Properties and Stress – Strain Development in High-Pressure Die Cast Aluminium Castings

    DEFF Research Database (Denmark)

    Kotas, Petr; Hattel, Jesper Henri; Thorborg, Jesper

    2009-01-01

    .e. whether the casting is based on cast iron- or aluminium-alloys. The distribution of local properties in a casting might vary substantially which makes it complex to optimize the casting with good accuracy. Often, mechanical simulations of the load situation are based on the assumption that the cast...... in an aluminium alloy is considered including simulation of the entire casting process with emphasis on microstructure formation related to mechanical properties such as elastic modulus, yield stress, ultimate strength and elongation as well as residual stresses. Subsequently, the casting is subjected to service...... loads and the results of this analysis are discussed in relation to the predicted local properties as well as the residual stresses originating from the casting simulation....

  5. A high figure of merit localized surface plasmon sensor based on a gold nanograting on the top of a gold planar film

    International Nuclear Information System (INIS)

    Zhang Zu-Yin; Wang Li-Na; Hu Hai-Feng; Li Kang-Wen; Ma Xun-Peng; Song Guo-Feng

    2013-01-01

    We investigate the sensitivity and figure of merit (FOM) of a localized surface plasmon (LSP) sensor with gold nanograting on the top of planar metallic film. The sensitivity of the localized surface plasmon sensor is 317 nm/RIU, and the FOM is predicted to be above 8, which is very high for a localized surface plasmon sensor. By employing the rigorous coupled-wave analysis (RCWA) method, we analyze the distribution of the magnetic field and find that the sensing property of our proposed system is attributed to the interactions between the localized surface plasmon around the gold nanostrips and the surface plasmon polarition on the surface of the gold planar metallic film. These findings are important for developing high FOM localized surface plasmon sensors. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

    NARCIS (Netherlands)

    Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker; Ahlstrøm, Andreas P.; Abermann, Jakob; Andersen, Morten L.; Andersen, Signe B.; Bjørk, Anders A.; Box, Jason E.; Braithwaite, Roger J.; Bøggild, Carl E.; Citterio, Michele; Clement, Poul; Colgan, William; Fausto, Robert S.; Gleie, Karin; Gubler, Stefanie; Hasholt, Bent; Hynek, Bernhard; Knudsen, Niels T.; Larsen, Signe H.; Mernild, Sebastian H.; Oerlemans, Johannes; Oerter, Hans; Olesen, Ole B.; Smeets, C. J P Paul; Steffen, Konrad; Stober, Manfred; Sugiyama, Shin; Van As, Dirk; Van Den Broeke, Michiel R.; Van De Wal, Roderik S W

    2016-01-01

    Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in

  7. Band gaps and localization of surface water waves over large-scale sand waves with random fluctuations

    Science.gov (United States)

    Zhang, Yu; Li, Yan; Shao, Hao; Zhong, Yaozhao; Zhang, Sai; Zhao, Zongxi

    2012-06-01

    Band structure and wave localization are investigated for sea surface water waves over large-scale sand wave topography. Sand wave height, sand wave width, water depth, and water width between adjacent sand waves have significant impact on band gaps. Random fluctuations of sand wave height, sand wave width, and water depth induce water wave localization. However, random water width produces a perfect transmission tunnel of water waves at a certain frequency so that localization does not occur no matter how large a disorder level is applied. Together with theoretical results, the field experimental observations in the Taiwan Bank suggest band gap and wave localization as the physical mechanism of sea surface water wave propagating over natural large-scale sand waves.

  8. Origin of bending in uncoated microcantilever - Surface topography?

    International Nuclear Information System (INIS)

    Lakshmoji, K.; Prabakar, K.; Tripura Sundari, S.; Jayapandian, J.; Tyagi, A. K.; Sundar, C. S.

    2014-01-01

    We provide direct experimental evidence to show that difference in surface topography on opposite sides of an uncoated microcantilever induces bending, upon exposure to water molecules. Examination on opposite sides of the microcantilever by atomic force microscopy reveals the presence of localized surface features on one side, which renders the induced stress non-uniform. Further, the root mean square inclination angle characterizing the surface topography shows a difference of 73° between the opposite sides. The absence of deflection in another uncoated microcantilever having similar surface topography confirms that in former microcantilever bending is indeed induced by differences in surface topography

  9. Development of the simplified local stress analysis methodology for the nuclear class 2 and 3 piping welded to the seal plate

    International Nuclear Information System (INIS)

    Lee, Dae Hee; Park, Jun Soo; Jeong, Seung Ha; Kim, Jong Min; Eom, Se Yoon

    1996-06-01

    Lugs, brackets, stiffeners and other attachments may be welded, bolted and studded to the outside or inside of piping and the local stresses arise because of the radial thermal expansion of the piping, the dilatation of the piping due to its internal pressure, the circumferential contraction of the pipe as a results of an axial tensile force, etc., constrained by those. So the evaluation of the local stress for the piping constrained by the attachment in accordance with the ASME Section III, NB-3651.3, NC-3645 and ND-3645 are required for the Class 1, 2, and 3 piping. In this report, the formula for the local stress analysis for the piping welded to the seal plate was developed and the results from the theoretical analysis were compared with the results from the theoretical analysis were compared with the results analyzed by the ANSYS. The results from the theoretical analysis agree well to the results analyzed by the ANSYS with a conservatism. The conservatism in the theoretical analysis can be considered as a safety factor in the design stage. So, the formula developed in this report can be used very effectively for the design of the seal plate and the local stress analysis of the nuclear class 2 and 3 piping welded to the seal plate. 2 tabs., 7 figs., 5 refs. (Author) .new

  10. Detecting Local Ligand-Binding Site Similarity in Non-Homologous Proteins by Surface Patch Comparison

    Science.gov (United States)

    Sael, Lee; Kihara, Daisuke

    2012-01-01

    Functional elucidation of proteins is one of the essential tasks in biology. Function of a protein, specifically, small ligand molecules that bind to a protein, can be predicted by finding similar local surface regions in binding sites of known proteins. Here, we developed an alignment free local surface comparison method for predicting a ligand molecule which binds to a query protein. The algorithm, named Patch-Surfer, represents a binding pocket as a combination of segmented surface patches, each of which is characterized by its geometrical shape, the electrostatic potential, the hydrophobicity, and the concaveness. Representing a pocket by a set of patches is effective to absorb difference of global pocket shape while capturing local similarity of pockets. The shape and the physicochemical properties of surface patches are represented using the 3D Zernike descriptor, which is a series expansion of mathematical 3D function. Two pockets are compared using a modified weighted bipartite matching algorithm, which matches similar patches from the two pockets. Patch-Surfer was benchmarked on three datasets, which consist in total of 390 proteins that bind to one of 21 ligands. Patch-Surfer showed superior performance to existing methods including a global pocket comparison method, Pocket-Surfer, which we have previously introduced. Particularly, as intended, the accuracy showed large improvement for flexible ligand molecules, which bind to pockets in different conformations. PMID:22275074

  11. Greenland surface mass-balance observations from the ice-sheet ablation area and local glaciers

    DEFF Research Database (Denmark)

    Machguth, Horst; Thomsen, Henrik H.; Weidick, Anker

    2016-01-01

    Glacier surface mass-balance measurements on Greenland started more than a century ago, but no compilation exists of the observations from the ablation area of the ice sheet and local glaciers. Such data could be used in the evaluation of modelled surface mass balance, or to document changes in g...

  12. Effect of geometric construction on residual stress distribution in designing a nuclear rotor joined by multipass narrow gap welding

    International Nuclear Information System (INIS)

    Tan, Long; Zhang, Linjie; Zhang, Jianxun; Zhuang, Dong

    2014-01-01

    Highlights: • The internal stress of the pipe is measured using local material removal method. • Bottom protrusion at weld seam can release the stress and mitigate stress evolution. The through-wall axial stress is bending type under the effect of the rotor discs. • The impact of geometric construction on the stress evolution begins after pass 15. - Abstract: The purpose of this study is to investigate the effect of geometric construction on the distribution of residual stresses before and after heat treatment in designing a nuclear welded rotor. The local material removal method was used to measure internal residual stress of the experimental pipe after post weld heat treatment. Three finite element models were employed as follows: a model of experimental pipe, a model with a bottom protrusion existed at the weld region, and a model of two rotor discs butt-welded with a bottom protrusion at the weld region. Investigated results showed that the bottom protrusion existed at the weld region can decrease the residual stress and mitigate the stress evolution significantly on the inner surface. Under the binding effect of the rotor discs, the axial stress of inner surface region is compressive stress; the through-wall axial stress at the weld center line can be deemed to a bending type; both the hoop stress and axial stress at the weld center line on the inner surface are compressive. The impact of geometric construction on the stress evolution at the root bead begins after pass 15 deposited

  13. Impact of In Situ Stress Distribution Characteristics on Jointed Surrounding Rock Mass Stability of an Underground Cavern near a Hillslope Surface

    Directory of Open Access Journals (Sweden)

    Bangxiang Li

    2017-01-01

    Full Text Available In this paper, a series of numerical simulations are performed to analyze the in situ stress distribution characteristics of the rock mass near different slope angles hillslope surfaces, which are subjected to the vertical gravity stress and different horizontal lateral stresses and the influence which the in situ stress distribution characteristics of 45° hillslope to the integral stability of surrounding rock mass when an underground cavern is excavated considering three different horizontal distances from the underground cavern to the slope surface. It can be concluded from the numerical results that different slope angles and horizontal lateral stresses have a strong impact on the in situ stress distribution and the integral surrounding rock mass stability of the underground cavern when the horizontal distance from the underground cavern to the slope surface is approximately 100 m to 200 m. The relevant results would provide some important constructive suggestions to the engineering site selection and optimization of large-scale underground caverns in hydropower stations.

  14. The application of white radiation to residual stress analysis in the intermediate zone between surface and volume

    CERN Document Server

    Genzel, C; Wallis, B; Reimers, W

    2001-01-01

    Mechanical surface processing is known to give rise to complex residual stress fields in the near surface region of polycrystalline materials. Consequently, their analysis by means of non-destructive X-ray and neutron diffraction methods has become an important topic in materials science. However, there remains a gap with respect to the accessible near surface zone, which concerns a range between about 10 mu m and 1 mm, where the conventional X-ray methods are no longer and the neutron methods are not yet sensitive. In order to achieve the necessary penetration depth tau to perform residual stress analysis (RSA) in this region, advantageous use can be made of energy dispersive X-ray diffraction of synchrotron radiation (15-60 keV) in the reflection mode. Besides an example concerning the adaptation of methods applied so far in the angle dispersive RSA to the energy dispersive case, the concept of a new materials science beamline at BESSY II for residual stress and texture analysis is presented.

  15. The application of white radiation to residual stress analysis in the intermediate zone between surface and volume

    International Nuclear Information System (INIS)

    Genzel, Ch.; Stock, C.; Wallis, B.; Reimers, W.

    2001-01-01

    Mechanical surface processing is known to give rise to complex residual stress fields in the near surface region of polycrystalline materials. Consequently, their analysis by means of non-destructive X-ray and neutron diffraction methods has become an important topic in materials science. However, there remains a gap with respect to the accessible near surface zone, which concerns a range between about 10 μm and 1 mm, where the conventional X-ray methods are no longer and the neutron methods are not yet sensitive. In order to achieve the necessary penetration depth τ to perform residual stress analysis (RSA) in this region, advantageous use can be made of energy dispersive X-ray diffraction of synchrotron radiation (15-60 keV) in the reflection mode. Besides an example concerning the adaptation of methods applied so far in the angle dispersive RSA to the energy dispersive case, the concept of a new materials science beamline at BESSY II for residual stress and texture analysis is presented

  16. Complementary structure for designer localized surface plasmons

    Science.gov (United States)

    Gao, Zhen; Gao, Fei; Zhang, Youming; Zhang, Baile

    2015-11-01

    Magnetic localized surface plasmons (LSPs) supported on metallic structures corrugated by very long and curved grooves have been recently proposed and demonstrated on an extremely thin metallic spiral structure (MSS) in the microwave regime. However, the mode profile for the magnetic LSPs was demonstrated by measuring only the electric field, not the magnetic field. Here, based on Babinet's principle, we propose a Babinet-inverted, or complementary MSS whose electric/magnetic mode profiles match the magnetic/electric mode profiles of MSS. This complementarity of mode profiles allows mapping the magnetic field distribution of magnetic LSP mode profile on MSS by measuring the electric field distribution of the corresponding mode on complementary MSS. Experiment at microwave frequencies also demonstrate the use of complementary MSS in sensing refractive-index change in the environment.

  17. Observation of weak superconductivity in electrons localized on a film surface

    International Nuclear Information System (INIS)

    Fogel', N.Y.; Kolin'ko, A.E.

    1984-01-01

    We have observed anomalous abrupt resistance changes in thick vanadium films [d>>xi(T)]. We have also observed a number of anomalies in the H--T phase diagrams for these films; these anomalies are most clearly seen when the field is parallel to, or at low angles of incidence with respect to, the film surface. We explain our results by assuming that there are two different electron systems present in the film. One of them is composed of electrons localized near a natural planar defect, the film surface. This subsystem is characterized by extremely small values of the critical current

  18. Local emission spectroscopy of surface micrograins in A{sup III}B{sup V} semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhukov, N. D., E-mail: ndzhukov@rambler.ru; Gluhovskoy, E. G.; Mosiyash, D. S. [Saratov State University (Russian Federation)

    2016-07-15

    The density-of-states spectra and the parameters of levels of electron states in locally chosen surface micrograins of indium antimonide and arsenide and gallium arsenide are studied with a tunneling electron microscope in the field-emission mode of measurements. By correlating the current–voltage characteristics with the formula for the probability of emission via levels, the activation energies of the levels (ψ) and the lifetimes of electrons at the levels (τ) are determined. Two types of levels for electron localization are identified. These are levels in the micrograin bulk (ψ ≈ 0.75, 1.15, and 1.59 eV for n-InSb, n-InAs, and n-GaAs, respectively; τ ~ 10{sup –8}–10{sup –7} s) and in the surface region of an i-InSb micrograin (ψ ~ 0.73, 1.33, 1.85, 2.15, 5.1 eV; τ ≈ 5 × 10{sup –8}–3 × 10{sup –7} s). A physical model involving the Coulomb-interaction-induced localization of light electrons and their size quantization determined by the electron effective mass, energy, and concentration and by the surface curvature of the micrograin is proposed.

  19. Control of Eolian soil erosion from waste site surface barriers

    International Nuclear Information System (INIS)

    Ligotke, M.W.

    1994-11-01

    Physical models were tested in a wind tunnel to determine optimum surface-ravel admixtures for protecting silt-loam soil from erosion by, wind and saltating, sand stresses. The tests were performed to support the development of a natural-material surface barrier for and waste sites. Plans call for a 2-m deep silt-loam soil reservoir to retain infiltrating water from rainfall and snowmelt. The objective of the study was to develop a gravel admixture that would produce an erosion-resistant surface layer during, periods of extended dry climatic stress. Thus, tests were performed using simulated surfaces representing dry, unvegetated conditions present just after construction, after a wildfire, or during an extended drought. Surfaces were prepared using silt-loam soil mixed with various grades of sand and Travel. Wind-induced surface shear stresses were controlled over the test surfaces, as were saltating, sand mass flow rates and intensities. Tests were performed at wind speeds that approximated and exceeded local 100-year peak gust intensities. Surface armors produced by pea gravel admixtures were shown to provide the best protection from wind and saltating sand stresses. Compared with unprotected silt-loam surfaces, armored surfaces reduced erosion rates by more than 96%. Based in part on wind tunnel results, a pea gravel admixture of 15% will be added to the top 1 in of soil in a prototype barrier under construction in 1994. Field tests are planned at the prototype site to provide data for comparison with wind tunnel results

  20. An energy conservation approach to adsorbate-induced surface stress and the extraction of binding energy using nanomechanics

    Science.gov (United States)

    Pinnaduwage, Lal A.; Boiadjiev, Vassil I.; Hawk, John E.; Gehl, Anthony C.; Fernando, Gayanath W.; Rohana Wijewardhana, L. C.

    2008-03-01

    Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.

  1. An energy conservation approach to adsorbate-induced surface stress and the extraction of binding energy using nanomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Pinnaduwage, Lal A; Boiadjiev, Vassil I; Hawk, John E; Gehl, Anthony C [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6122 (United States); Fernando, Gayanath W [Physics Department, University of Connecticut, Storrs, CT 06269 (United States); Wijewardhana, L C Rohana [Physics Department, University of Cincinnati, Cincinnati, OH 45221 (United States)

    2008-03-12

    Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.

  2. Size effects and strain localization in atomic-scale cleavage modeling

    International Nuclear Information System (INIS)

    Elsner, B A M; Müller, S

    2015-01-01

    In this work, we study the adhesion and decohesion of Cu(1 0 0) surfaces using density functional theory (DFT) calculations. An upper stress to surface decohesion is obtained via the universal binding energy relation (UBER), but the model is limited to rigid separation of bulk-terminated surfaces. When structural relaxations are included, an unphysical size effect arises if decohesion is considered to occur as soon as the strain energy equals the energy of the newly formed surfaces. We employ the nudged elastic band (NEB) method to show that this size effect is opposed by a size-dependency of the energy barriers involved in the transition. Further, we find that the transition occurs via a localization of bond strain in the vicinity of the cleavage plane, which resembles the strain localization at the tip of a sharp crack that is predicted by linear elastic fracture mechanics. (paper)

  3. Analytic examination of mechanism for compressive residual stress introduction with low plastic strain using peening

    International Nuclear Information System (INIS)

    Ishibashi, Ryo; Hato, Hisamitsu; Miyazaki, Katsumasa; Yoshikubo, Fujio

    2016-01-01

    Our goal for this study was to understand the cause of the differences in surface properties between surfaces processed using water jet peening (WJP) and shot peening (SP) and to examine the compressive residual stress introduction process with low plastic strain using SP. The dynamic behaviors of stress and strain in surfaces during these processes were analyzed through elasto-plastic calculations using a finite-element method program, and the calculated results were compared with measured results obtained through experiments. Media impacting a surface results in a difference in the hardness and microstructure of the processed surface. During SP, a shot deforms the surface locally with stress concentration in the early stages of the impact, while shock waves deform the surface evenly throughout the wave passage across the surface during WJP. A shot with a larger diameter creates a larger impact area on the surface during shot impact. Thus, SP with a large-diameter shot suppresses the stress concentration under the same kinetic energy condition. As the shot diameter increases, the equivalent plastic strain decreases. On the other hand, the shot is subject to size restriction since the calculated results indicate the compressive residual stress at the surface decreased and occasionally became almost zero as the shot diameter increased. Thus, compressive residual stress introduction with low plastic strain by using SP is considered achievable by using shots with a large diameter and choosing the appropriate peening conditions. (author)

  4. Overexpression of a Plasma Membrane-Localized SbSRP-Like Protein Enhances Salinity and Osmotic Stress Tolerance in Transgenic Tobacco

    Directory of Open Access Journals (Sweden)

    Avinash Mishra

    2017-04-01

    Full Text Available An obligate halophyte, Salicornia brachiata grows in salt marshes and is considered to be a potential resource of salt- and drought-responsive genes. It is important to develop an understanding of the mechanisms behind enhanced salt tolerance. To increase this understanding, a novel SbSRP gene was cloned, characterized, over-expressed, and functionally validated in the model plant Nicotiana tabacum. The genome of the halophyte S. brachiata contains two homologs of an intronless SbSRP gene of 1,262 bp in length that encodes for a stress-related protein. An in vivo localization study confirmed that SbSRP is localized on the plasma membrane. Transgenic tobacco plants (T1 that constitutively over-express the SbSRP gene showed improved salinity and osmotic stress tolerance. In comparison to Wild Type (WT and Vector Control (VC plants, transgenic lines showed elevated relative water and chlorophyll content, lower malondialdehyde content, lower electrolyte leakage and higher accumulation of proline, free amino acids, sugars, polyphenols, and starch under abiotic stress treatments. Furthermore, a lower build-up of H2O2 content and superoxide-radicals was found in transgenic lines compared to WT and VC plants under stress conditions. Transcript expression of Nt-APX (ascorbate peroxidase, Nt-CAT (catalase, Nt-SOD (superoxide dismutase, Nt-DREB (dehydration responsive element binding factor, and Nt-AP2 (apetala2 genes was higher in transgenic lines under stress compared to WT and VC plants. The results suggested that overexpression of membrane-localized SbSRP mitigates salt and osmotic stress in the transgenic tobacco plant. It was hypothesized that SbSRP can be a transporter protein to transmit the environmental stimuli downward through the plasma membrane. However, a detailed study is required to ascertain its exact role in the abiotic stress tolerance mechanism. Overall, SbSRP is a potential candidate to be used for engineering salt and osmotic

  5. Preliminary results of endorectal surface coil magnetic resonance imaging for local staging of prostate cancer

    NARCIS (Netherlands)

    Jager, G. J.; Barentsz, J. O.; de la Rosette, J. J.; Rosenbusch, G.

    1994-01-01

    To evaluate the effectiveness of endorectal surface coil (ERC) magnetic resonance imaging (MRI) in the local staging of adenocarcinoma of the prostate (ACP). A total of 23 patients who were considered candidates for radical prostatectomy because of clinically localized ACP were examined by ERC-MRI.

  6. Formation of Sheeting Joints as a Result of Compression Parallel to Convex Surfaces, With Examples from Yosemite National Park, California

    Science.gov (United States)

    Martel, S. J.

    2008-12-01

    The formation of sheeting joints has been an outstanding problem in geology. New observations and analyses indicate that sheeting joints develop in response to a near-surface tension induced by compressive stresses parallel to a convex slope (hypothesis 1) rather than by removal of overburden by erosion, as conventionally assumed (hypothesis 2). Opening mode displacements across the joints together with the absence of mineral precipitates within the joints mean that sheeting joints open in response to a near-surface tension normal to the surface rather than a pressurized fluid. Consideration of a plot of this tensile stress as a function of depth normal to the surface reveals that a true tension must arise in the shallow subsurface if the rate of that tensile stress change with depth is positive at the surface. Static equilibrium requires this rate (derivative) to equal P22 k2 + P33 k3 - ρ g cosβ, where k2 and k3 are the principal curvatures of the surface, P22 and P33 are the respective surface- parallel normal stresses along the principal curvatures, ρ is the material density, g is gravitational acceleration, and β is the slope. This derivative will be positive and sheeting joints can open if at least one principal curvature is sufficiently convex (negative) and the surface-parallel stresses are sufficiently compressive (negative). At several sites with sheeting joints (e.g., Yosemite National Park in California), the measured topographic curvatures and the measured surface-parallel stresses of about -10 MPa combine to meet this condition. In apparent violation of hypothesis 1, sheeting joints occur locally at the bottom of Tenaya Canyon, one of the deepest glaciated, U-shaped (concave) canyons in the park. The canyon-bottom sheeting joints only occur, however, where the canyon is convex downstream, a direction that nearly coincides with direction of the most compressive stress measured in the vicinity. The most compressive stress acting along the convex

  7. Measuring Shear Stress with a Microfluidic Sensor to improve Aerodynamic Efficiency, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Skin friction drag is directly proportional to the local shear stress of a surface and can be the largest factor in an aerodynamic body's total parasitic drag. The...

  8. Reduction method for residual stress of welded joint using random vibration

    International Nuclear Information System (INIS)

    Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro

    2005-01-01

    Welded joints are used for construction of many structures. Residual stress is induced near the bead caused by locally given heat. Tensile residual stress on the surface may reduce fatigue strength. In this paper, a new method for reduction of residual stress using vibration during welding is proposed. As vibrational load, random vibration, white noise and filtered white noise are used. Two thin plates are butt-welded. Residual stress is measured with a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. It is concluded that tensile residual stress near the bead is reduced by using random vibration during welding

  9. Fatigue life extension techniques for weldments via mechanical surface post treatment

    International Nuclear Information System (INIS)

    Han, Seung Ho; Han, Jeong Woo; Cho, In Ho

    2008-01-01

    In many welded structures, fatigue failures are often occurred at welded joints in which stress concentrations due to the joint geometry are relatively high. Although employing good detail design practices by upgrading the welded detail class enables to improve the fatigue performance, in many cases, the modification of the detail may not be practicable. As an alternative, fatigue life extension techniques, that reduce the severity of the stress concentration at the weld toe region, remove imperfections, and introduce local compressive welding residual stress, can be applied. These techniques are also used as remedial measures to extend the fatigue life of critical welds that have failed prematurely and have been repaired. This paper introduces peening techniques via a pneumatic hammer peening and ultrasonic impact which make it possible to give the weld not only a favorable shape reducing the local stress concentration, but also a beneficial compressive residual stress into material surface

  10. Numerical evaluation of state boundary surface through rotation of principal stress axes in sand

    International Nuclear Information System (INIS)

    Sadrnejad, S. A.

    2001-01-01

    In applying shear stress to saturated soil with arbitrary stress paths, the prediction of the exact value of strains is difficult because of mainly its stress path dependent nature. Rotation of the principal stress axes during shearing of the soil is a feature of stress paths associated with many field loading situations. A proper understanding of the effects of principal stress rotation on soil behavior can be provided if the anisotropy existing prior to stress rotation and induced anisotropy due to plastic flow in soil are clearly understood and modeled. A multi laminate based model for soil is developed and used to compute and present the influence of rotation of principal stress axes on the plastic behavior of soil. This is fulfilled by distributing the effects of boundary condition changes into several predefined sampling orientations at one point and summing the micro-results up as the macro-result. The validity of the presented model examined by comparing numerical and test results showing the mentioned aspect. In this paper, the state boundary surface is numerically obtained by a multi laminate based model capable of predicting the behavior of sand under the influences of rotation of the direction of principal stress axes and induced anisotropy. the predicted numerical results are tally in agreement with experiments

  11. Variability of bed mobility in natural, gravel-bed channels and adjustments to sediment load at local and reach scales

    Science.gov (United States)

    Thomas E. Lisle; Jonathan M. Nelson; John Pitlick; Mary Ann Madej; Brent L. Barkett

    2000-01-01

    Abstract - Local variations in boundary shear stress acting on bed-surface particles control patterns of bed load transport and channel evolution during varying stream discharges. At the reach scale a channel adjusts to imposed water and sediment supply through mutual interactions among channel form, local grain size, and local flow dynamics that govern bed mobility...

  12. Localized 31PNMR spectroscopy with ISIS and surface coils

    International Nuclear Information System (INIS)

    Heindel, W.; Schreier, G.; Steinbrich, W.; Glathe, S.; Huttmann, P.

    1990-01-01

    A new method for image-guided localized phosphorus NMR spectroscopy of superficial tissues has been investigated using a 1.5 Tesla whole-body-MR-system. We used a surface coil combined with adiabatic excitation pulses and a modified ISIS sequence. This approach is related to imaging sequences and thus permits a flexible and accurate determination of the volume of interest from 'conventional' proton images. The scope and advantages of the method are demonstrated by phantom studies. Clinical applications to the liver, renal transplants, and the mediastinum are described. (orig.) [de

  13. Effect of wave-function localization on the time delay in photoemission from surfaces

    International Nuclear Information System (INIS)

    Zhang, C.-H.; Thumm, U.

    2011-01-01

    We investigate streaking time delays in the photoemission from a solid model surface as a function of the degree of localization of the initial-state wave functions. We consider a one-dimensional slab with lattice constant a latt of attractive Gaussian-shaped core potentials of width σ. The parameter σ/a latt thus controls the overlap between adjacent core potentials and localization of the electronic eigenfunctions on the lattice points. Small values of σ/a latt latt > or approx 0.4. By numerically solving the time-dependent Schroedinger equation, we calculate photoemission spectra from which we deduce a characteristic bimodal shape of the band-averaged photoemission time delay: as the slab eigenfunctions become increasingly delocalized, the time delay quickly decreases near σ/a latt =0.3 from relatively large values below σ/a latt ∼0.2 to much smaller delays above σ/a latt ∼0.4. This change in wave-function localization facilitates the interpretation of a recently measured apparent relative time delay between the photoemission from core and conduction-band levels of a tungsten surface.

  14. Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

    Energy Technology Data Exchange (ETDEWEB)

    Wanzenboeck, H.D.; Hochleitner, G.; Mika, J.; Shawrav, M.M.; Gavagnin, M.; Bertagnolli, E. [Vienna University of Technology, Institute for Solid State Electronics, Vienna (Austria)

    2014-12-15

    During the last decades, focused electron beam induced deposition (FEBID) has become a successful approach for direct-write fabrication of nanodevices. Such a deposition technique relies on the precursor supply to the sample surface which is typically accomplished by a gas injection system using a tube-shaped injector nozzle. This precursor injection strategy implies a position-dependent concentration gradient on the surface, which affects the geometry and chemistry of the final nanodeposit. Although simulations already proposed the local distribution of nozzle-borne gas molecules impinging on the surface, this isolated step in the FEBID process has never been experimentally measured yet. This work experimentally investigates the local distribution of impinging gas molecules on the sample plane, isolating the direct impingement component from surface diffusion or precursor depletion by deposition. The experimental setup used in this work maps and quantifies the local impinging rate of argon gas over the sample plane. This setup simulates the identical conditions for a precursor molecule during FEBID. Argon gas was locally collected with a sniffer tube, which is directly connected to a residual gas analyzer for quantification. The measured distribution of impinging gas molecules showed a strong position dependence. Indeed, a 300-μm shift of the deposition area to a position further away from the impingement center spot resulted in a 50 % decrease in the precursor impinging rate on the surface area. With the same parameters, the precursor distribution was also simulated by a Monte Carlo software by Friedli and Utke and showed a good correlation between the empirical and the simulated precursor distribution. The results hereby presented underline the importance of controlling the local precursor flux conditions in order to obtain reproducible and comparable deposition results in FEBID. (orig.)

  15. Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

    International Nuclear Information System (INIS)

    Wanzenboeck, H.D.; Hochleitner, G.; Mika, J.; Shawrav, M.M.; Gavagnin, M.; Bertagnolli, E.

    2014-01-01

    During the last decades, focused electron beam induced deposition (FEBID) has become a successful approach for direct-write fabrication of nanodevices. Such a deposition technique relies on the precursor supply to the sample surface which is typically accomplished by a gas injection system using a tube-shaped injector nozzle. This precursor injection strategy implies a position-dependent concentration gradient on the surface, which affects the geometry and chemistry of the final nanodeposit. Although simulations already proposed the local distribution of nozzle-borne gas molecules impinging on the surface, this isolated step in the FEBID process has never been experimentally measured yet. This work experimentally investigates the local distribution of impinging gas molecules on the sample plane, isolating the direct impingement component from surface diffusion or precursor depletion by deposition. The experimental setup used in this work maps and quantifies the local impinging rate of argon gas over the sample plane. This setup simulates the identical conditions for a precursor molecule during FEBID. Argon gas was locally collected with a sniffer tube, which is directly connected to a residual gas analyzer for quantification. The measured distribution of impinging gas molecules showed a strong position dependence. Indeed, a 300-μm shift of the deposition area to a position further away from the impingement center spot resulted in a 50 % decrease in the precursor impinging rate on the surface area. With the same parameters, the precursor distribution was also simulated by a Monte Carlo software by Friedli and Utke and showed a good correlation between the empirical and the simulated precursor distribution. The results hereby presented underline the importance of controlling the local precursor flux conditions in order to obtain reproducible and comparable deposition results in FEBID. (orig.)

  16. Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

    Science.gov (United States)

    Wanzenboeck, H. D.; Hochleitner, G.; Mika, J.; Shawrav, M. M.; Gavagnin, M.; Bertagnolli, E.

    2014-12-01

    During the last decades, focused electron beam induced deposition (FEBID) has become a successful approach for direct-write fabrication of nanodevices. Such a deposition technique relies on the precursor supply to the sample surface which is typically accomplished by a gas injection system using a tube-shaped injector nozzle. This precursor injection strategy implies a position-dependent concentration gradient on the surface, which affects the geometry and chemistry of the final nanodeposit. Although simulations already proposed the local distribution of nozzle-borne gas molecules impinging on the surface, this isolated step in the FEBID process has never been experimentally measured yet. This work experimentally investigates the local distribution of impinging gas molecules on the sample plane, isolating the direct impingement component from surface diffusion or precursor depletion by deposition. The experimental setup used in this work maps and quantifies the local impinging rate of argon gas over the sample plane. This setup simulates the identical conditions for a precursor molecule during FEBID. Argon gas was locally collected with a sniffer tube, which is directly connected to a residual gas analyzer for quantification. The measured distribution of impinging gas molecules showed a strong position dependence. Indeed, a 300-µm shift of the deposition area to a position further away from the impingement center spot resulted in a 50 % decrease in the precursor impinging rate on the surface area. With the same parameters, the precursor distribution was also simulated by a Monte Carlo software by Friedli and Utke and showed a good correlation between the empirical and the simulated precursor distribution. The results hereby presented underline the importance of controlling the local precursor flux conditions in order to obtain reproducible and comparable deposition results in FEBID.

  17. Infrared thermography based studies on the effect of age on localized cold stress induced thermoregulation in human

    Science.gov (United States)

    Lahiri, B. B.; Bagavathiappan, S.; Nishanthi, K.; Mohanalakshmi, K.; Veni, L.; Saumya; Yacin, S. M.; Philip, John

    2016-05-01

    Thermoregulatory control of blood flow plays an important role in maintaining the human body temperature and it provides physiological resistance against extreme environmental thermal stresses. To understand the role of age on thermal signals from veins and the thermoregulatory mechanism, the dynamic variation of the vein temperature on the hands of 17 human subjects, under a localized cold stress, was studied using infrared thermography. It was observed that the vein temperature of the stimulated hand initially decreased with time up to a time interval (called 'inversion time'), which was attributed to the localized cutaneous vasoconstriction. Beyond inversion time, a rise in the vein temperature of the stimulated hand was observed. A shift in the inversion time to higher values was observed for the older subjects, which was attributed to the reduced efficiency and responsiveness of the cutaneous vasoconstriction mechanism in these subjects. Our studies indicated that the inversion time increased linearly with subject age with strong positive Pearson's correlation coefficient of 0.94. It was also observed that the contralateral symmetry in vasoconstriction was much lower in older subjects than the younger subjects. The absolute difference between the left and right inversion time varied between 11-118 s and 5-28 s for the older and younger subjects, respectively. Our study clearly demonstrated that infrared thermography is one of the most effective experimental tool for studying dynamic variation in vein pixel temperature under localized thermal stresses.

  18. Localized surface plasmon polariton resonance in holographically structured Al-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    George, David; Lowell, David; Mao, Michelle; Hassan, Safaa; Philipose, Usha [Department of Physics and Center for Advanced Research and Technology, University of North Texas, Denton, Texas 76203 (United States); Li, Li; Jiang, Yan; Cui, Jingbiao [Department of Physics and Materials Science, University of Memphis, Memphis, Tennessee 38152 (United States); Ding, Jun; Zhang, Hualiang [Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, Massachusetts 01854 (United States); Lin, Yuankun [Department of Physics and Center for Advanced Research and Technology, University of North Texas, Denton, Texas 76203 (United States); Department of Electrical Engineering, University of North Texas, Denton, Texas 76203 (United States)

    2016-07-28

    In this paper, we studied the localized surface plasmon polariton (SPP) resonance in hole arrays in transparent conducting aluminum-doped zinc oxide (AZO). CMOS-compatible fabrication process was demonstrated for the AZO devices. The localized SPP resonance was observed and confirmed by electromagnetic simulations. Using a standing wave model, the observed SPP was dominated by the standing-wave resonance along (1,1) direction in square lattices. This research lays the groundwork for a fabrication technique that can contribute to the core technology of future integrated photonics through its extension into tunable conductive materials.

  19. Effect of clear bands on intergranular stresses and IASCC early damage - 04002

    International Nuclear Information System (INIS)

    Sauzay, M.; Ould Moussa, M.; Diawara, B.; Lebreau, F.

    2016-01-01

    Slip localization is a common feature in post-irradiated metallic poly-crystals undergoing tensile straining. This effect takes place for instance in the form of thin slip bands called channels or clear bands, formed after the local vanishing of irradiation defects induced interactions with gliding dislocations. Channel impingement towards grain boundaries (GBs) should induce local stress concentrations along GBs, in the quasi-elastic surrounding matrix. It has been shown extensively that this trigger GB crack initiation. Grain boundary fracture is simulated using a double criterion based on both critical normal stress and fracture energy as deduced from atomistic computations of GB fracture. The critical stress is deduced from the fracture energy using the universal-binding-energy relationship (UBER). In the case of brittle fracture, the fracture energy is defined as the two fresh free surface energy values minus the GB energy. In relationship with the more complex topic of irradiation induced stress corrosion cracking (IASCC) occurring in-service conditions, the influence of irradiation dose, strain rate and irradiation creep is discussed. Due to the complex loading history highlighted by structural finite element analysis, strain peaks may induce the formation of clear bands or twin bands. The study of the effect of irradiation creep on the relaxation of the induced GB stress fields shows clearly that the relaxation requires many months due to the linear irradiation creep law. Such durations allows GB oxidation mechanisms to occur leading to a weakening of the GB fracture parameters in the vicinity of the free surfaces. This short paper is followed by the slides of the presentation

  20. Mitigation of inside surface residual stress of type 304 stainless steel pipe welds by inside water cooling method

    International Nuclear Information System (INIS)

    Sasaki, R.

    1980-01-01

    The weld residual stress distributions, macro- and microstructures of heat affected zone and IGSCC susceptibility of Type 304 stainless steel pipe welds by natural and inside water cooling methods have been investigated. The residual stresses of pipe welds by the natural cooling method are high tensile on both the inside and the outside surface. While the residual stresses on the inside surface of pipe welds by the inside water cooling method are compressive in both axial and circumferential directions for each pipe size from 2 to 24 inch diameter. The sensitized zones of welds by the inside water cooling method are closer to the fusion line, much narrower and milder than those by the natural cooling method. According to the constant extension rate test results for specimens taken from the inside surface of pipe welds, the inside water cooled welds are more resistant to IGSCC than naturally cooled ones

  1. Study on mechanism of intergranular stress corrosion cracking and analysis of residual stress and work hardening in welds of low-carbon austenitic stainless steel with hard surface machining

    International Nuclear Information System (INIS)

    Mori, Hiroaki; Mochizuki, Masahito; Nishimoto, Kazutoshi; Toyoda, Masao; Katsuyama, Jinya

    2007-01-01

    In order to make clear the effects of residual stress and hardening on intergranular stress corrosion cracking (IGSCC) behavior in the welds of Type 316L low-carbon austenitic stainless steel with surface hardening, the residual stress and hardness in the butt-joint of pipes as a typical example of the actual structure were estimated and the grain boundary sliding was analyzed from the viewpoint of micro-deformation. On the basis of these results, the mechanism of IGSCC was discussed by the integrated knowledge between metallurgy and mechanics. The relationship between plastic strain and hardness in hard-machined surface near welds was clarified from the experimented relationship and the analysis method by the thermal elastic-plastic analysis. The distributions of hardness and residual stress with the actual surface machining could be simulated. It was made clear that grain boundary sliding occurred in the steel at 561K by a constant strain rate tensile test. From the comparison of grain boundary sliding behavior between solution treated specimen and cold-rolled one, it was found that the grain boundary sliding in cold-rolled one occurs in smaller strain conditions than that in as received one, and the amount of grain boundary sliding in cold-rolled one increases remarkably with increases in rolling reduction. In addition, it was clarified that the grain boundary energy is raised by the grain boundary sliding. On the basis of these results, it was concluded that the cause of IGSCC in the welds of Type 316L low-carbon austenitic stainless steel with surface hardening is the increase in grain boundary energy due to grain boundary sliding induced by residual stress of multi pass welding and surface hardening. (author)

  2. Numerical analysis of the effect of surface roughness on mechanical fields in polycrystalline aggregates

    Science.gov (United States)

    Guilhem, Yoann; Basseville, Stéphanie; Curtit, François; Stéphan, Jean-Michel; Cailletaud, Georges

    2018-06-01

    This paper is dedicated to the study of the influence of surface roughness on local stress and strain fields in polycrystalline aggregates. Finite element computations are performed with a crystal plasticity model on a 316L stainless steel polycrystalline material element with different roughness states on its free surface. The subsequent analysis of the plastic strain localization patterns shows that surface roughness strongly affects the plastic strain localization induced by crystallography. Nevertheless, this effect mainly takes place at the surface and vanishes under the first layer of grains, which implies the existence of a critical perturbed depth. A statistical analysis based on the plastic strain distribution obtained for different roughness levels provides a simple rule to define the size of the affected zone depending on the rough surface parameters.

  3. Behavior of surface residual stress in explosion hardened high manganese austenitic cast steel due to repeated impact loads

    International Nuclear Information System (INIS)

    Oda, Akira; Miyagawa, Hideaki

    1985-01-01

    Explosion hardened high manganese austenitic cast steel is being tried for rail crossing recently. From the previous studies, it became clear that high tensile residual stress was generated in the hardened surface layer by explosion and microcracks were observed. In this study, therefore, the behavior of surface residual stress in explosion hardened steel due to repeated impact loads was examined and compared with those of the original and shot peened steels. The results obtained are summarized as follows: (1) In the initial stage of the repetition of impact, high tensile surface residual stress in explosion hardened steel decreased rapidly with the repetition of impact, while those of the original and shot peened steels increased rapidly. This difference was attributed to the difference in depth of the work hardened layer in three testing materials. (2) Beyond 20 impacts the residual stress of three test specimens decreased gradually, and at more than 2000 impacts the compressive stress of about 500 MPa was produced regardless of the histories of working of testing materials. (3) The linear law in the second stage of residual stress fading was applicable to this case, and the range of the linear relationship was related to the depth of the work hardened layer of testing material. (4) From the changes in half-value breadth and peak intensity of diffraction X-ray, it was supposed that a peculiar microscopic strain exists in explosion hardened steel. (author)

  4. On the initiation of sustained slip-weakening ruptures by localized stresses

    KAUST Repository

    Galis, Martin

    2014-12-10

    Numerical simulations of dynamic earthquake rupture require an artificial initiation procedure, if they are not integrated in long-term earthquake cycle simulations. A widely applied procedure involves an \\'overstressed asperity\\', a localized region stressed beyond the static frictional strength. The physical properties of the asperity (size, shape and overstress) may significantly impact rupture propagation. In particular, to induce a sustained rupture the asperity size needs to exceed a critical value. Although criteria for estimating the critical nucleation size under linear slip-weakening friction have been proposed for 2-D and 3-D problems based on simplifying assumptions, they do not provide general rules for designing 3-D numerical simulations. We conduct a parametric study to estimate parameters of the asperity that minimize numerical artefacts (e.g. changes of rupture shape and speed, artificial supershear transition, higher slip-rate amplitudes). We examine the critical size of square, circular and elliptical asperities as a function of asperity overstress and background (off-asperity) stress. For a given overstress, we find that asperity area controls rupture initiation while asperity shape is of lesser importance. The critical area obtained from our numerical results contrasts with published theoretical estimates when background stress is low. Therefore, we derive two new theoretical estimates of the critical size under low background stress while also accounting for overstress. Our numerical results suggest that setting the asperity overstress and area close to their critical values eliminates strong numerical artefacts even when the overstress is large. We also find that properly chosen asperity size or overstress may significantly shorten the duration of the initiation. Overall, our results provide guidelines for determining the size of the asperity and overstress to minimize the effects of the forced initiation on the subsequent spontaneous

  5. Distribution of local magnetic field of vortex lattice near anisotropic superconductor surface in inclined external fields

    International Nuclear Information System (INIS)

    Efremova, S.A.; Tsarevskij, S.L.

    1997-01-01

    Magnetic field distribution in a unit cell of the Abrikosov vortex lattice near the surface of monoaxial anisotropic type-ii superconductors in inclined external magnetic field has been found in the framework of London model for the cases when the symmetry axis is perpendicular and parallel to the superconductor surface interface. Distribution of local magnetic field as a function of the distance from the superconductor interface surface and external field inclination angle has been obtained. Using high-Tc superconductor Y-Ba-Cu-O by way of examples, it has been shown that the study of local magnetic field distribution function, depending on external magnetic field inclination angle towards the superconductor symmetry axis and towards the superconductor surface, can provide important data on anisotropic properties of the superconductor [ru

  6. Electrocardiographic markers of ischemia during mental stress testing in postinfarction patients. Role of body surface mapping

    International Nuclear Information System (INIS)

    Bosimini, E.; Galli, M.; Guagliumi, G.; Giubbini, R.; Tavazzi, L.

    1991-01-01

    In patients with coronary artery disease, radionuclide investigations have documented a high incidence of mental stress-induced myocardial ischemia in the absence of significant electrocardiographic changes and/or angina. To investigate the causes of the low electrocardiographic sensitivity, we recorded body surface maps during mental arithmetic in 22 normal volunteers and 37 postinfarction patients with residual exercise ischemia. Myocardial perfusion was studied with thallium-201 or technetium-99 (SESTAMIBI) planar scans. In 14 patients, body surface maps were also recorded during atrial pacing at the heart rate values achieved during mental stress. While taking the body surface maps, the area from J point to 80 msec after this point (ST-80) was analyzed by integral maps, difference maps, and departure maps. The body surface mapping criteria for ischemia were a new negative area on the integral maps, a negative potential of more than 2 SD from mean normal values on the difference maps, and a negative departure index of more than 2. Scintigraphy showed asymptomatic myocardial hypoperfusion in 33 patients. Eight patients had significant ST segment depression. The ST-80 integral and difference maps identified 17 ischemic patients. Twenty-four patients presented abnormal departure maps. One patient presented ST depression and abnormal body surface maps without reversible tracer defect. In 14 of 14 patients, atrial pacing did not reproduce the body surface map abnormalities. The analyses of the other electrocardiographic variables showed that in patients with mental stress-induced perfusion defects, only changes of T apex-T offset (aT-eT) interval in Frank leads and changes of maximum negative potential value of aT-eT integral maps significantly differed from those of normal subjects

  7. X-ray measurement of residual stress on bolt threads

    International Nuclear Information System (INIS)

    Hagiwara, Masaya; Nakahara, Kanefumi; Yoshimoto, Isamu.

    1989-01-01

    This study deals with X-ray measurement of residual stress at the local area around the thread root of a bolt. Residual stress in the 0.5 mm x 5 mm area was measured using a method of stepped scanning and parabolic approximation. The conditions of measurement had been determined and evaluated through the preliminary measurement of compressive stress acting on the cylindrical surface. Furthermore, the fatigue strength estimated by applying the residual stress data to the previously presented hypothesis was compared with the experimental results. The main conclusions obtained were as follows: (1) The residual stress in a relatively small area on the cylindrical surface with large curvature can be measured by X-ray using a method of stepped scanning and parabolic approximation; (2) The compressive residual stress measured at the thread root was larger for the bolt manufactured by thread rolling after heat treatment than for one manufactured by thread rolling before heat treatment; (3) The distribution of residual stress along the axial direction from the thread root to the portion under crest did not represent remarkable change in its value; (4) The residual stress of a bolt was somewhat decreased by fatigue loading on the condition of low mean stress; (5) The fatigue strength estimated using residual stress data showed the tendency of experimental results well. (author)

  8. Stress field models from Maxwell stress functions: southern California

    Science.gov (United States)

    Bird, Peter

    2017-08-01

    shallow stress maxima and discontinuous horizontal compression at the Moho, which the new model can only approximate. The new model also lacks the spatial resolution to portray the localized stress states that may occur near the central surfaces of weak faults; instead, the model portrays the regional or background stress field which provides boundary conditions for weak faults. Peak shear stresses in one registered model and one alternate model are 120 and 150 MPa, respectively, while peak vertically integrated shear stresses are 2.9 × 1012 and 4.1 × 1012 N m-1. Channeling of deviatoric stress along the strong Great Valley and the western slope of the Peninsular Ranges is evident. In the neotectonics of southern California, it appears that deviatoric stress and long-term strain rate have a negative correlation, because regions of low heat flow are strong and act as stress guides, while undergoing very little internal deformation. In contrast, active faults lie preferentially in areas with higher heat flow, and their low strength keeps deviatoric stresses locally modest.

  9. Rupture preparation process controlled by surface roughness on meter-scale laboratory fault

    Science.gov (United States)

    Yamashita, Futoshi; Fukuyama, Eiichi; Xu, Shiqing; Mizoguchi, Kazuo; Kawakata, Hironori; Takizawa, Shigeru

    2018-05-01

    We investigate the effect of fault surface roughness on rupture preparation characteristics using meter-scale metagabbro specimens. We repeatedly conducted the experiments with the same pair of rock specimens to make the fault surface rough. We obtained three experimental results under the same experimental conditions (6.7 MPa of normal stress and 0.01 mm/s of loading rate) but at different roughness conditions (smooth, moderately roughened, and heavily roughened). During each experiment, we observed many stick-slip events preceded by precursory slow slip. We investigated when and where slow slip initiated by using the strain gauge data processed by the Kalman filter algorithm. The observed rupture preparation processes on the smooth fault (i.e. the first experiment among the three) showed high repeatability of the spatiotemporal distributions of slow slip initiation. Local stress measurements revealed that slow slip initiated around the region where the ratio of shear to normal stress (τ/σ) was the highest as expected from finite element method (FEM) modeling. However, the exact location of slow slip initiation was where τ/σ became locally minimum, probably due to the frictional heterogeneity. In the experiment on the moderately roughened fault, some irregular events were observed, though the basic characteristics of other regular events were similar to those on the smooth fault. Local stress data revealed that the spatiotemporal characteristics of slow slip initiation and the resulting τ/σ drop for irregular events were different from those for regular ones even under similar stress conditions. On the heavily roughened fault, the location of slow slip initiation was not consistent with τ/σ anymore because of the highly heterogeneous static friction on the fault, which also decreased the repeatability of spatiotemporal distributions of slow slip initiation. These results suggest that fault surface roughness strongly controls the rupture preparation process

  10. Numerical Simulations of the Effects of a Tidal Turbine Array on Near-Bed Velocity and Local Bed Shear Stress

    Directory of Open Access Journals (Sweden)

    Philip A. Gillibrand

    2016-10-01

    Full Text Available We apply a three-dimensional hydrodynamic model to consider the potential effects of energy extraction by an array of tidal turbines on the ambient near-bed velocity field and local bed shear stress in a coastal channel with strong tidal currents. Local bed shear stress plays a key role in local sediment dynamics. The model solves the Reynold-averaged Navier-Stokes (RANS equations on an unstructured mesh using mixed finite element and finite volume techniques. Tidal turbines are represented through an additional form drag in the momentum balance equation, with the thrust imparted and power generated by the turbines being velocity dependent with appropriate cut-in and cut-out velocities. Arrays of 1, 4 and 57 tidal turbines, each of 1.5 MW capacity, were simulated. Effects due to a single turbine and an array of four turbines were negligible. The main effect of the array of 57 turbines was to cause a shift in position of the jet through the tidal channel, as the flow was diverted around the tidal array. The net effect of this shift was to increase near-bed velocities and bed shear stress along the northern perimeter of the array by up to 0.8 m·s−1 and 5 Pa respectively. Within the array and directly downstream, near-bed velocities and bed shear stress were reduced by similar amounts. Changes of this magnitude have the potential to modify the known sand and shell banks in the region. Continued monitoring of the sediment distributions in the region will provide a valuable dataset on the impacts of tidal energy extraction on local sediment dynamics. Finally, the mean power generated per turbine is shown to decrease as the turbine array increased in size.

  11. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.

    1997-08-01

    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  12. On topological approach to local theory of surfaces in Calabi-Yau threefolds

    DEFF Research Database (Denmark)

    Gukov, Sergei; Liu, Chiu-Chu Melissa; Sheshmani, Artan

    2017-01-01

    We study the web of dualities relating various enumerative invariants, notably Gromov-Witten invariants and invariants that arise in topological gauge theory. In particular, we study Donaldson-Thomas gauge theory and its reductions to D=4 and D=2 which are relevant to the local theory of surfaces...

  13. The influence of surface stress on dislocation emission from sharp and blunt cracks in f.c.c. metals

    DEFF Research Database (Denmark)

    Schiøtz, Jakob

    2000-01-01

    We use computer simulations to study the behaviour of atomically sharp and blunted cracks in various fee metals. The simulations use effective medium potentials which contain many-body interactions. We find that when using potentials representing platinum and gold a sharp crack is stable with res......We use computer simulations to study the behaviour of atomically sharp and blunted cracks in various fee metals. The simulations use effective medium potentials which contain many-body interactions. We find that when using potentials representing platinum and gold a sharp crack is stable...... with respect to the emission of a dislocation from the crack tip, whereas for all other metals studied the sharp crack is unstable. This result cannot be explained by existing criteria for the intrinsic ductile/brittle behaviour of crack tips, but is probably caused by surface stresses. When the crack...... is no longer atomically sharp dislocation emission becomes easier in all the studied metals. The effect is relatively strong; the critical stress intensity factor for emission to occur is reduced by up to 20%. This behaviour appears to be caused by the surface stress near the crack tip. The surface stress...

  14. Tuning the localized surface plasmon resonance of silver nanoplatelet colloids

    International Nuclear Information System (INIS)

    Singh, Asha; Jayabalan, J; Chari, Rama; Srivastava, Himanshu; Oak, S M

    2010-01-01

    The effect of femtosecond laser irradiation on silver nanoplatelet colloids is described. It is shown that irradiation with a femtosecond laser of appropriate fluence can be used to tune the localized surface plasmon resonances of triangular silver nanoplatelets by a few tens of nanometres. This peak shift is shown to be caused by the structural modifications of the particle tips. We have also shown that post-preparation addition of poly-vinyl pyrrolidone to the nanocolloid arrests the peak shift.

  15. Tuning the localized surface plasmon resonance of silver nanoplatelet colloids

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Asha; Jayabalan, J; Chari, Rama [Laser Physics Applications Division, Raja Ramanna Centre for Advanced Technology, Indore (India); Srivastava, Himanshu [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore (India); Oak, S M, E-mail: jjaya@rrcat.gov.i [Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore (India)

    2010-08-25

    The effect of femtosecond laser irradiation on silver nanoplatelet colloids is described. It is shown that irradiation with a femtosecond laser of appropriate fluence can be used to tune the localized surface plasmon resonances of triangular silver nanoplatelets by a few tens of nanometres. This peak shift is shown to be caused by the structural modifications of the particle tips. We have also shown that post-preparation addition of poly-vinyl pyrrolidone to the nanocolloid arrests the peak shift.

  16. Critical shear stress on the surface of a cuttings bed; Tensao critica de cisalhamento na superficie de um leito de cascalhos

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Luciana Mancor [Universidade Estadual Norte Fluminense (UENF), Macae, RJ (Brazil). Lab. de Engenharia de Petroleo]. E-mail: luciana@lenep.uenf.br; Campos, Wellington [PETROBRAS, S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas]. E-mail: campos@cenpes.petrobras.com.br; Braga, Luiz Carvalho [Centro Federal de Educacao Tecnologica (CEFET), Macae, RJ (Brazil). Unidade de Ensino Descentralizada]. E-mail: luiz@lenep.uenf.br

    2000-07-01

    The cuttings transport during the drilling of highly inclined and horizontal wells is hindered by the creation of a cuttings bed in the annulus. In this work, it is shown that the equilibrium height of this bed can be determined from the shear stress on its surface. This fact enables the formulation of a methodology for evaluating the equilibrium height of the cuttings bed through the introduction of a new concept, that of critical shear stress. This is the shear stress that acts on the bed surface at the imminence of movement of the particles on the bed surface. The use of the methodology requires the determination of the acting shear stress and of the required critical shear stress. The acting shear stress is calculated by means of a computer program that solve the motion differential equations in the annular space; covering the cases of the laminar and turbulent flow regimes. The actuating shear stress is a function of flow rate and of the annular geometry in the presence of a cuttings bed; it is also a function of the physical properties of the fluid. On the other hand, the required critical shear stress is a function of the particles diameters and physical properties of the fluid and particles. A mechanistic model for the critical shear stress is also presented. (author)

  17. Removal factor determination of some local smear papers for surface contamination smear test

    International Nuclear Information System (INIS)

    Suratman; Indriyotomo, D.; Aminjoyo, S.

    1996-01-01

    Removal factor determination of some local smear papers has been done, using dry smear test method. The aim of this research is to find removal values of local smear papers on some surfaces, to replace import smear papers. Smear test was done on the various surfaces i.e.: porcelain, formica, glass, stainless steel, steel and PVC, with the local smear papers I.e.: Padalarang, Diagonal, Concorde, Marga, Hard Cloth, and import smear paper. The artificial contaminant which used were I-131 and P-32. The removal factor values of Padalarang paper for surfaces: porcelain, formica, glass stainless steel, steel and PVC were: 24.5%, 20.0%, 27.0%, 6.8%, 4.9%, and 13.6% respectively. The removal factor values of Diagonal paper were:18.4%, 15.9%, 5.7%, 3.5%, and 9.1% respectively. The removal factor values of concord paper were: 18.5%, 20.3%, 23.1%, 6.6%, 3.8%, and 9.0% respectively. The removal factor values of Marga paper were: 16.7%, 13.5%, 21.1%, 4.2%, 4.1% and 8.1% respectively. The removal factor values of Hard Cloth were: 18.6%, 12.6%, 20.5%, 8.2%, and 10.1% respectively. The removal factor values of import smear paper were: 17.8%, 15.0%, 18.8%, 9.1%, 4.8%, and 14.4% respectively . Substitution alternative of import smear paper is Padalarang. (author)

  18. Investigation of AA2024-T3 surfaces modified by cerium compounds: A localized approach

    International Nuclear Information System (INIS)

    Paussa, L.; Andreatta, F.; De Felicis, D.; Bemporad, E.; Fedrizzi, L.

    2014-01-01

    Highlights: •The precipitation of cerium compounds occurs on the entire AA2024-T3 surface. •The matrix is less involved in the cerium precipitation. •Cerium intensely precipitates on Mg-rich IM particles. •The electrochemical behavior of Mg-rich IM particles influences the mechanism of cerium precipitation. -- Abstract: The precipitation of cerium compounds on polished AA2024-T3 surfaces was investigated following an electrochemical and microstructural localized approach. It was found that cerium precipitation occurs on the entire surface covering intermetallic particles and the matrix as well. The matrix is the region where the precipitation of cerium is less favoured. The highest amount of cerium was observed on magnesium-rich intermetallic particles. The localized analyses suggest that precipitation of cerium on magnesium-rich intermetallic particles could happen following two mechanisms: the former based on a potential reversal of the intermetallic particles and the latter due to a partial magnesium dissolution

  19. Rupture prediction for induction bends under opening mode bending with emphasis on strain localization

    International Nuclear Information System (INIS)

    Mitsuya, Masaki; Sakanoue, Takashi

    2015-01-01

    This study focuses on the opening mode of induction bends; this mode represents the deformation outside a bend. Bending experiments on induction bends are shown and the manner of failure of these bends was investigated. Ruptures occur at the intrados of the bends, which undergo tensile stress, and accompany the local reduction of wall thickness, i.e., necking that indicates strain localization. By implementing finite element analysis (FEA), it was shown that the rupture is dominated not by the fracture criterion of material but by the initiation of strain localization that is a deformation characteristic of the material. These ruptures are due to the rapid increase of local strain after the initiation of strain localization and suddenly reach the fracture criterion. For the evaluation of the deformability of the bends, a method based on FEA that can predict the displacement at the rupture is proposed. We show that the yield surface shape and the true stress–strain relationship after uniform elongation have to be defined on the basis of the actual properties of the bend material. The von Mises yield criterion, which is commonly used in cases of elastic–plastic FEA, could not predict the rupture and overestimated the deformability. In contrast, a yield surface obtained by performing tensile tests on a biaxial specimen could predict the rupture. The prediction of the rupture was accomplished by an inverse calibration method that determined the true stress-strain relationship after uniform elongation. As an alternative to the inverse calibration, a simple extrapolation method of the true stress-strain relationship after uniform elongation which can predict the rupture is proposed. - Highlights: • A method based on FEA that can predict the displacement at the rupture is proposed. • The yield surface shape and the true stress–strain have to be defined precisely. • The von Mises yield criterion overestimated the deformability. • The ruptures are due to the

  20. Changes in phase composition and stress state of surface layers of VK20 hard alloy after ion bombardment

    International Nuclear Information System (INIS)

    Platonov, G.L.; Leonov, E.Yu.; Anikin, V.N.; Anikeev, A.I.

    1988-01-01

    Titanium ion bombardment of the surface of the hard VK20 alloy is studied for its effect on variations in the phase and chemical composition of its surface layers. It is stated that ion treatment results in the appearance of the η-phase of Co 6 W 6 C composition in the surface layer of the VK20 alloy, in the increase of distortions and decrease of coherent scattering blocks of the hard alloy carbide phase. Such a bombardment is found to provoke a transition of the plane-stressed state of the hard alloy surface into the volume-stressed state. It is established that ion treatment does not cause an allotropic transition of the cobalt phase α-modification, formed during grinding of the hard alloy, into the β-modification

  1. Characterization of local hydrophobicity on sapphire (0001) surfaces in aqueous environment by colloidal probe atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp

    2017-02-28

    Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.

  2. Experimental and Theoretical Analysis of Headlight Surface Temperature in an Infrared Heated Stress Relieving Oven

    Directory of Open Access Journals (Sweden)

    Mustafa MUTLU

    2016-04-01

    Full Text Available In this study, the IR heated stress relieve oven was experimentally and theoretically examined. In experimental measurements, temperature was measured on headlight surface, placed in IR oven at various conveyor speeds and various distances between IR lamps and headlight surface. In theoretical study, a mathematical model was developed for the headlights surface temperature by using heat transfer theory. The results obtained by the mathematical model and the measurement showed very good agreement with a 6.5 % average error. It is shown that mathematical models can be used to estimate the surface temperatures when the oven is operated under different conditions.

  3. Experimental residual stress evaluation of hydraulic expansion transitions in Alloy 690 steam generator tubing

    International Nuclear Information System (INIS)

    McGregor, R.; Doherty, P.; Hornbach, D.; Abdelsalam, U.

    1995-01-01

    Nuclear Steam Generator (SG) service reliability and longevity have been seriously affected worldwide by corrosion at the tube-to-tubesheet joint expansion. Current SG designs for new facilities and replacement projects enhance corrosion resistance through the use of advanced tubing materials and improved joint design and fabrication techniques. Here, transition zones of hydraulic expansions have undergone detailed experimental evaluation to define residual stress and cold-work distribution on and below the secondary-side surface. Using X-ray diffraction techniques, with supporting finite element analysis, variations are compared in tubing metallurgical condition, tube/pitch geometry, expansion pressure, and tube-to-hole clearance. Initial measurements to characterize the unexpanded tube reveal compressive stresses associated with a thin work-hardened layer on the outer surface of the tube. The gradient of cold-work was measured as 3% to 0% within .001 inch of the surface. The levels and character of residual stresses following hydraulic expansion are primarily dependent on this work-hardened surface layer and initial stress state that is unique to each tube fabrication process. Tensile stresses following expansion are less than 25% of the local yield stress and are found on the transition in a narrow circumferential band at the immediate tube surface (< .0002 inch/0.005 mm depth). The measurements otherwise indicate a predominance of compressive stresses on and below the secondary-side surface of the transition zone. Excellent resistance to SWSCC initiation is offered by the low levels of tensile stress and cold-work. Propagation of any possible cracking would be deterred by the compressive stress field that surrounds this small volume of tensile material

  4. Study on the Surface Integrity of a Thin-Walled Aluminum Alloy Structure after a Bilateral Slid Rolling Process

    Directory of Open Access Journals (Sweden)

    Laixiao Lu

    2016-04-01

    Full Text Available For studying the influence of a bilateral slid rolling process (BSRP on the surface integrity of a thin-walled aluminum alloy structure, and revealing the generation mechanism of residual stresses, a self-designed BSRP appliance was used to conduct rolling experiments. With the aid of a surface optical profiler, an X-ray stress analyzer, and a scanning electron microscope (SEM, the differences in surface integrity before and after BSRP were explored. The internal changing mechanism of physical as well as mechanical properties was probed. The results show that surface roughness (Ra is reduced by 23.7%, microhardness is increased by 21.6%, and the depth of the hardening layer is about 100 μm. Serious plastic deformation was observed within the subsurface of the rolled region. The residual stress distributions along the depth of the rolling surface and milling surface were tested respectively. Residual stresses with deep and high amplitudes were generated via the BSRP. Based on the analysis of the microstructure, the generation mechanism of the residual stresses was probed. The residual stress of the rolling area consisted of two sections: microscopic stresses caused by local plastic deformation and macroscopic stresses caused by overall non-uniform deformation.

  5. Effect of surface stress states on the corrosion behavior of alloy 690

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Mo; Shim, Hee Sang; Seo, Myung Ji; Hur, Do Haeng [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The test environment simulated the primary water chemistry in PWRs. Dissolved oxygen (DO), dissolved hydrogen (DH), pH and conductivity were monitored at room temperature using sensors manufactured by Orbisphere and Mettler Toledo. The temperature and pressure were maintained at 330 .deg. C and 150 bars during the corrosion test. The condition of the test solution was lithium (LiOH) 2 ppm and boron (H3BO4) 1,200 ppm, DH 35 cc/kg (STP) and less than 5 ppb DO. The flow rate of the loop system was 3.8 L/hour. Corrosion tests were conducted for 500 hours. The corrosion release rate was evaluated by a gravimetric analysis method using a two-step alkaline permanganate-ammonium citrate (AP/AC) descaling process. Compressive residual stress is induced by shot peening treatment but its value reveals some different trend between the shot peening intensity on the surface of Alloy 690 TT. A higher shot peening intensity causes a reduction in the corrosion rate and it is considered that the compressive residual stress beneath the surface layer suppresses the metal ion transfer in an alloy matrix.

  6. Investigations into the Surface Strain/Stress State in a Single-Crystal Superalloy via XRD Characterization

    Directory of Open Access Journals (Sweden)

    Haodong Duan

    2018-05-01

    Full Text Available The present study was aimed at determining the surface strain/stress state in an Ni-based single-crystal (SC superalloy that was subjected to two different cooling rates from solid solution temperature through using the X-ray diffraction (XRD method. The normal stresses σ 11 s and σ 22 s were determined, then the Von Mises stresses ( σ V M s were derived from them. Field emission gun scanning electron microscope (FEG-SEM and transmission electron microscope (TEM micrographs were taken to illustrate the strain/stress state change. The precipitation of the secondary γ′ phases in the γ phase and the formation of the dislocation in the interphase upon a slower cooling rate caused the γ phase lattice distortion to increase, so a larger σ V M s of the γ phase was realized in comparison to the faster cooling sample. For both of the two cooling modes, we found that the σ V M s of the γ′ phase increased due to the growth of the γ′ phase during the aging process. Also, the aging process led to pronouncedly anisotropic lattice mismatches in the {331} and {004} planes. In addition, the surface strain/stress states of a cylinder sample and a tetragonal sample were also studied using a faster cooling rate, and σ 11 s and σ 22 s were analyzed to explain the influence of the shape factor on the stress anisotropy in the [001] and [ 1 1 ¯ 0 ] orientations. The strain in the [001] orientation of the γ phase is more sensitive to the shape change.

  7. Increased in vivo release of neuropeptide S in the amygdala of freely moving rats after local depolarisation and emotional stress.

    Science.gov (United States)

    Ebner, Karl; Rjabokon, Alesja; Pape, Hans-Christian; Singewald, Nicolas

    2011-10-01

    Intracerebral microdialysis in conjunction with a highly sensitive radioimmunoassay was used to study the in vivo release of neuropeptide S (NPS) within the amygdala of freely moving rats. NPS was consistently detected in basolateral amygdala dialysates and the release considerably enhanced in response to local depolarisation as well as exposure to forced swim stress. Thus, our data demonstrate for the first time emotional stress-induced release of NPS in the amygdala supporting a functional role of endogenous NPS in stress/anxiety-related phenomena.

  8. Local stress analysis in devices by FIB

    NARCIS (Netherlands)

    Kregting, R.; Gielen, A.W.J.; Driel, W. van; Alkemade, P.; Miro, H.; Kamminga, J.-D.

    2010-01-01

    Intrinsic stresses in bondpads may lead to early failure of IC's. In order to determine the intrinsic stresses in semiconductor structures, a new procedure is set up. This procedure is a combined experimental/numerical approach which consists of the following steps: First, a conductive gold layer

  9. Understanding of surface pit formation mechanism of GaN grown in MOCVD based on local thermodynamic equilibrium assumption

    International Nuclear Information System (INIS)

    Gao Zhi-Yuan; Xue Xiao-Wei; Li Jiang-Jiang; Wang Xun; Xing Yan-Hui; Cui Bi-Feng; Zou De-Shu

    2016-01-01

    Frank’s theory describes that a screw dislocation will produce a pit on the surface, and has been evidenced in many material systems including GaN. However, the size of the pit calculated from the theory deviates significantly from experimental result. Through a careful observation of the variations of surface pits and local surface morphology with growing temperature and V/III ratio for c -plane GaN, we believe that Frank’s model is valid only in a small local surface area where thermodynamic equilibrium state can be assumed to stay the same. If the kinetic process is too vigorous or too slow to reach a balance, the local equilibrium range will be too small for the center and edge of the screw dislocation spiral to be kept in the same equilibrium state. When the curvature at the center of the dislocation core reaches the critical value 1/ r 0 , at the edge of the spiral, the accelerating rate of the curvature may not fall to zero, so the pit cannot reach a stationary shape and will keep enlarging under the control of minimization of surface energy to result in a large-sized surface pit. (paper)

  10. Influence of residual stress on the adhesion and surface morphology of PECVD-coated polypropylene

    Science.gov (United States)

    Jaritz, Montgomery; Hopmann, Christian; Behm, Henrik; Kirchheim, Dennis; Wilski, Stefan; Grochla, Dario; Banko, Lars; Ludwig, Alfred; Böke, Marc; Winter, Jörg; Bahre, Hendrik; Dahlmann, Rainer

    2017-11-01

    The properties of plasma-enhanced chemical vapour deposition (PECVD) coatings on polymer materials depend to some extent on the surface and material properties of the substrate. Here, isotactic polypropylene (PP) substrates are coated with silicon oxide (SiO x ) films. Plasmas for the deposition of SiO x are energetic and oxidative due to the high amount of oxygen in the gas mixture. Residual stress measurements using single Si cantilever stress sensors showed that these coatings contain high compressive stress. To investigate the influence of the plasma and the coatings, residual stress, silicon organic (SiOCH) coatings with different thicknesses between the PP and the SiO x coating are used as a means to protect the substrate from the oxidative SiO x coating process. Pull-off tests are performed to analyse differences in the adhesion of these coating systems. It could be shown that the adhesion of the PECVD coatings on PP depends on the coatings’ residual stress. In a PP/SiOCH/SiO x -multilayer system the residual stress can be significantly reduced by increasing the thickness of the SiOCH coating, resulting in enhanced adhesion.

  11. Mixed convection-radiation interaction in boundary-layer flow over horizontal surfaces

    Science.gov (United States)

    Ibrahim, F. S.; Hady, F. M.

    1990-06-01

    The effect of buoyancy forces and thermal radiation on the steady laminar plane flow over an isothermal horizontal flat plate is investigated within the framework of first-order boundary-layer theory, taking into account the hydrostatic pressure variation normal to the plate. The fluid considered is a gray, absorbing-emitting but nonscattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both a hot surface facing upward and a cold surface facing downward are considered in the analysis. Numerical results for the local Nusselt number, the local wall shear stress, the local surface heat flux, as well as the velocity and temperature distributions are presented for gases with a Prandtl number of 0.7 for various values of the radiation-conduction parameter, the buoyancy parameter, and the temperature ratio parameter.

  12. Remote detection of stress corrosion cracking: Surface composition and crack detection

    Science.gov (United States)

    Lissenden, Cliff J.; Jovanovic, Igor; Motta, Arthur T.; Xiao, Xuan; Le Berre, Samuel; Fobar, David; Cho, Hwanjeong; Choi, Sungho

    2018-04-01

    Chloride induced stress corrosion cracking (SCC) of austenitic stainless steel is a potential issue in long term dry storage of spent nuclear fuel canisters. In order for SCC to occur there must be a corrosive environment, a susceptible material, and a driving force. Because it is likely that the material in the heat affected zone (HAZ) of welded stainless steel structures has been sensitized as a result of chromium depletion at the grain boundaries and a thermal residual stress driving force is likely present if solution annealing is not performed, two issues are critical. Is the environment corrosive, i.e., are chlorides present in solution on the surface? And then, are there cracks that could propagate? Remote detection of chlorides on the surface can be accomplished by laser induced breakdown spectroscopy (LIBS), while cracks can be detected by shear horizontal guided waves generated by electromagnetic acoustic transducers (EMATs). Both are noncontact methods that are amenable to robotic delivery systems and harsh environments. The sensitivity to chlorine on stainless steel of a LIBS system that employs optical fiber for pulse delivery is demonstrated. Likewise, the ability of the EMAT system to detect cracks of a prescribed size and orientation is shown. These results show the potential for remote detection of Cl and cracks in dry storage spent fuel canisters.

  13. Localization of burn mark under an abnormal topography on MOSFET chip surface using liquid crystal and emission microscopy tools.

    Science.gov (United States)

    Lau, C K; Sim, K S; Tso, C P

    2011-01-01

    This article focuses on the localization of burn mark in MOSFET and the scanning electron microscope (SEM) inspection on the defect location. When a suspect abnormal topography is shown on the die surface, further methods to pin-point the defect location is necessary. Fault localization analysis becomes important because an abnormal spot on the chip surface may and may not have a defect underneath it. The chip surface topography can change due to the catastrophic damage occurred at layers under the chip surface, but it could also be due to inconsistency during metal deposition in the wafer fabrication process. Two localization techniques, liquid crystal thermography and emission microscopy, were performed to confirm that the abnormal topography spot is the actual defect location. The tiny burn mark was surfaced by performing a surface decoration at the defect location using hot hydrochloric acid. SEM imaging, which has the high magnification and three-dimensional capabilities, was used to capture the images of the burn mark. Copyright © 2011 Wiley Periodicals, Inc.

  14. Stress corrosion cracking of Zircaloys. Final report

    International Nuclear Information System (INIS)

    Cubicciotti, D.; Jones, R.L.; Syrett, B.C.

    1980-03-01

    The overall aim has been to develop an improved understanding of the stress corrosion cracking (SCC) mechanism considered to be responsible for pellet-cladding interaction (PCI) failures of nuclear fuel rods. The objective of the present phase of the project was to investigate the potential for improving the resistance of Zircaloy to iodine-induced SCC by modifying the manufacturing techniques used in the commercial production of fuel cladding. Several aspects of iodine SCC behavior of potential relevance to cladding performance were experimentally investigated. It was found that the SCC susceptibility of Zircaloy tubing is sensitive to crystallographic texture, surface condition, and residual stress distribution and that current specifications for Zircaloy tubing provide no assurance of an optimum resistance to SCC. Additional evidence was found that iodine-induced cracks initiate at local chemical inhomogeneities in the Zircaloy surface, but laser melting to produce a homogenized surface layer did not improve the SCC resistance. Several results were obtained that should be considered in models of PCI failure. The ratio of axial to hoop stress and the temperature were both shown to affect the SCC resistance whereas the difference in composition between Zircaloy-2 and Zircaloy-4 had no detectable effect. Damage accumulation during iodine SCC was found to be nonlinear: generally, a given life fraction at low stress was more damaging than the same life fraction at higher stress. Studies of the thermochemistry of the zirconium-iodine system (performed under US Department of Energy sponsorship) revealed many errors in the literature and provided important new insights into the mechanism of iodine SCC of Zircaloys

  15. Local and global Casimir energies for a semitransparent cylindrical shell

    International Nuclear Information System (INIS)

    Cavero-Pelaez, Ines; Milton, Kimball A; Kirsten, Klaus

    2007-01-01

    The local Casimir energy density and the global Casimir energy for a massless scalar field associated with a λδ-function potential in a (3 + 1)-dimensional circular cylindrical geometry are considered. The global energy is examined for both weak and strong coupling, the latter being the well-studied Dirichlet cylinder case. For weak coupling, through O(λ 2 ), the total energy is shown to vanish by both analytic and numerical arguments, based both on Green's-function and zeta-function techniques. Divergences occurring in the calculation are shown to be absorbable by renormalization of physical parameters of the model. The global energy may be obtained by integrating the local energy density only when the latter is supplemented by an energy term residing precisely on the surface of the cylinder. The latter is identified as the integrated local energy density of the cylindrical shell when the latter is physically expanded to have finite thickness. Inside and outside the δ-function shell, the local energy density diverges as the surface of the shell is approached; the divergence is weakest when the conformal stress tensor is used to define the energy density. A real global divergence first occurs in O(λ 3 ), as anticipated, but the proof is supplied here for the first time; this divergence is entirely associated with the surface energy and does not reflect divergences in the local energy density as the surface is approached

  16. Non--Local Approach to the Analysis of the Stress Distribution in Granular Systems.

    Science.gov (United States)

    Scott, J. E.; Kenkre, V. M.; Hurd, A. J.

    1998-03-01

    A continuum mechanical theory of the stress distribution in granular materials is presented, where the transformation of the vertical spatial coordinate into a formal time variable converts the study of the static stress distribution into a generally non--Markoffian, i.e., memory-possessing (non-local) propagation analysis. Previous treatments (J. -P). Bouchaud, M. E. Cates, and P. Claudin, J. Phys. I France 5, 639 (1995). (C. -h). Liu, S. R. Nagel, D. A. Schecter, S. N. Coppersmith, S. Majumdar, O. Narayan, and T. A. Witten, Science 269, 513 (1995). are shown to be particular cases of our theory corresponding to, respectively, wave-like and dif fusive limits of the general evolution. Calculations are presented for the example of ceramic or metal powder compaction in dies, with emphasis on the understanding of previously unexplained features as seen in experimental data found in the literature o ver the past 50 years. Specific proposals for new experimental investigations are presented.

  17. Analysis of stress fractures associated with lameness in Thoroughbred flat racehorses training on different track surfaces undergoing nuclear scintigraphic examination.

    Science.gov (United States)

    MacKinnon, M C; Bonder, D; Boston, R C; Ross, M W

    2015-05-01

    There is limited information regarding the impact of training track surface on the occurrence of stress fractures. To evaluate the impact of training track surface on the proportion of long bone and pelvic stress fractures associated with lameness in Thoroughbred horses in flat race training undergoing nuclear scintigraphic examination. Retrospective study. Scintigraphic examinations of Thoroughbred flat racehorses were evaluated from 2 hospitals (hospital A [Toronto Equine Hospital], 2003-2009, and hospital B [George D. Widener Hospital for Large Animals, School of Veterinary Medicine, University of Pennsylvania], 1994-2006). Horses admitted to hospital A trained at a single track, at which the main training surface changed from dirt to synthetic on 27 August 2006. Two distinct populations existed at hospital B: horses that trained on dirt (numerous trainers) and those that trained on turf (single trainer). All scintigraphic images were evaluated by a blinded reviewer. Fisher's exact test and logistic regression were used when appropriate, and significance was set at Pfractures detected in scintigraphic examinations from horses training on a synthetic surface (31.7%) in comparison to scintigraphic examinations from horses training on a dirt surface (23.0%) at an earlier point in time (P = 0.03). There was a greater proportion of hindlimb/pelvic and tibial stress fractures diagnosed in horses from the synthetic surface-trained group than from the dirt-trained group at hospital A (Pfractures diagnosed, but other factors, such as training philosophy, appear to be important. Future prospective investigations to fully elucidate the relationship between training track surface and the proportion of stress fractures and other nonfatal musculoskeletal injuries are warranted. © 2014 EVJ Ltd.

  18. Correlation between residual stress and plastic strain amplitude during low cycle fatigue of mechanically surface treated austenitic stainless steel AISI 304 and ferritic-pearlitic steel SAE 1045

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, I. [Institute of Materials Engineering, University of Kassel, 34125 Kassel, Hessen (Germany)], E-mail: Ivan.Nikitin@infineon.com; Besel, M. [Institute of Materials Engineering, University of Kassel, 34125 Kassel, Hessen (Germany)

    2008-09-15

    Mechanical surface treatments such as deep rolling are known to affect the near-surface microstructure and induce, e.g. residual stresses and/or increase the surface hardness. It is well known that, e.g. compressive residual stress states usually increase the lifetime under fatigue loading. The stress relaxation behaviour and the stability of the residual stress during fatigue loading depend on the mechanical surface treatment method. In this paper three different surface treatments are used and their effects on the low cycle fatigue behaviour of austenitic stainless steel (AISI 304) and ferritic-pearlitic steel (SAE 1045) are investigated. X-ray diffraction is applied for the non-destructive evaluation of the stress state and the microstructure. It is found that consecutive deep rolling and annealing as well as high temperature deep rolling produce more stable near-surface stress states than conventional deep rolling at room temperature. The plastic strain amplitudes during fatigue loading are measured and it is shown that they correlate well with the induced residual stress and its relaxation, respectively. Furthermore, Coffin-Manson plots are presented which clearly show the correlation between the plastic strain amplitude and the fatigue lifetime.

  19. Computation of principal stresses and stress intensity of a nozzle on a spherical pressure vessel

    International Nuclear Information System (INIS)

    Sun, B.C.; Lyow, B.L.; Koplik, B.

    1993-01-01

    This paper presents a Stress Computation Table that systematically computes the local stresses at various locations of the sphere-nozzle intersection. The six components of external loading are: radial load, two overturning moments, two horizontal shear forces, and a torsional moment. The radial and overturning moments induce local membrane and bending stresses in both the circumferential and meridional directions of the sphere around the nozzle. The shear forces and torsional moment produce local shear stresses. In addition, the shear forces induce local membrane and bending stresses around the nozzle. The local stress factors from each external loading component are taken from recent publications by Lyow, Sun and Koplik who have studied this subject through the use of the finite element method. These factors are a function of the nozzle-sphere geometrical parameters, beta, β, (nozzle radius/sphere radius) and gamma, γ, (sphere radius/thickness), with the beta value ranging from 0.1 to 0.5, and the gamma value ranging from 10 to 100. The Stress Table summarizes all the normal and shear stresses at eight different locations around the nozzle, and finally the principal stresses and stress intensity are computed. The stress factor plots from previous publications are replotted in this paper to provide a handy reference as well as consistency. A numerical sample employing a FORTRAN program is also given. (author)

  20. A novel binary shape context for 3D local surface description

    Science.gov (United States)

    Dong, Zhen; Yang, Bisheng; Liu, Yuan; Liang, Fuxun; Li, Bijun; Zang, Yufu

    2017-08-01

    3D local surface description is now at the core of many computer vision technologies, such as 3D object recognition, intelligent driving, and 3D model reconstruction. However, most of the existing 3D feature descriptors still suffer from low descriptiveness, weak robustness, and inefficiency in both time and memory. To overcome these challenges, this paper presents a robust and descriptive 3D Binary Shape Context (BSC) descriptor with high efficiency in both time and memory. First, a novel BSC descriptor is generated for 3D local surface description, and the performance of the BSC descriptor under different settings of its parameters is analyzed. Next, the descriptiveness, robustness, and efficiency in both time and memory of the BSC descriptor are evaluated and compared to those of several state-of-the-art 3D feature descriptors. Finally, the performance of the BSC descriptor for 3D object recognition is also evaluated on a number of popular benchmark datasets, and an urban-scene dataset is collected by a terrestrial laser scanner system. Comprehensive experiments demonstrate that the proposed BSC descriptor obtained high descriptiveness, strong robustness, and high efficiency in both time and memory and achieved high recognition rates of 94.8%, 94.1% and 82.1% on the considered UWA, Queen, and WHU datasets, respectively.

  1. Localized microjetting in the collapse of surface macrocavities

    Science.gov (United States)

    Olney, K. L.; Chiu, P.-H.; Benson, D. J.; Higgins, A.; Serge, M.; Nesterenko, V. F.

    2015-02-01

    This paper focuses on the multiscale mechanism of collapse of hemicylindrical annular surface macrocavities in steel caused by high-strain, high-strain rate plastic flow of copper. Experiments and simulations revealed that a two-stage process is responsible for the observed microjetting phenomena: the formation of lateral copper microjets from the localized shear flow in copper at the interface during the filling of the cavity, and their subsequent collision at the apex of the macrocavity generating two additional horizontal microjets. The lengths of these microjets were an order of magnitude smaller than the cavity size but linearly scaled with the cavity radius. This process of microjet development is sensitive to the cavity geometry and is unlike the previously observed jetting phenomena in cavitation, impact crater collapse, or shock-induced cavity collapse.

  2. NbSe3: Fermi surface and magnetoresistance under uniaxial stress

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  3. Localized surface plasmon enhanced cellular imaging using random metallic structures

    Science.gov (United States)

    Son, Taehwang; Lee, Wonju; Kim, Donghyun

    2017-02-01

    We have studied fluorescence cellular imaging with randomly distributed localized near-field induced by silver nano-islands. For the fabrication of nano-islands, a 10-nm silver thin film evaporated on a BK7 glass substrate with an adhesion layer of 2-nm thick chromium. Micrometer sized silver square pattern was defined using e-beam lithography and then the film was annealed at 200°C. Raw images were restored using electric field distribution produced on the surface of random nano-islands. Nano-islands were modeled from SEM images. 488-nm p-polarized light source was set to be incident at 60°. Simulation results show that localized electric fields were created among nano-islands and that their average size was found to be 135 nm. The feasibility was tested using conventional total internal reflection fluorescence microscopy while the angle of incidence was adjusted to maximize field enhancement. Mouse microphage cells were cultured on nano-islands, and actin filaments were selectively stained with FITC-conjugated phalloidin. Acquired images were deconvolved based on linear imaging theory, in which molecular distribution was sampled by randomly distributed localized near-field and blurred by point spread function of far-field optics. The optimum fluorophore distribution was probabilistically estimated by repetitively matching a raw image. The deconvolved images are estimated to have a resolution in the range of 100-150 nm largely determined by the size of localized near-fields. We also discuss and compare the results with images acquired with periodic nano-aperture arrays in various optical configurations to excite localized plasmonic fields and to produce super-resolved molecular images.

  4. Surface layer investigation of duplex stainless steel S32205 after stress peening utilizing X-ray diffraction

    International Nuclear Information System (INIS)

    Feng, Qiang; Jiang, Chuanhai; Xu, Zhou

    2013-01-01

    Highlights: ► The stress shot peening is superior to the conventional shot peening. ► Residual stresses along the loaded direction are bigger than transverse direction. ► Higher prestress leads to smaller domain size, high density of dislocation. ► Compared to ferrite, austenite has much higher hardness and work hardening. ► Ferrite has higher recover of elastic deformation than austenite after unloading. - Abstract: Residual stresses and micro-hardness of duplex stainless steel S32205 after stress peening are measured and domain sizes and microstrain are calculated. The results show that stress peening can significantly improve the compressive residual stresses and micro-hardness in both austenite and ferrite, and the former is affected by both the prestress and the measurement directions. Microstructure investigation reveals that material deformation is enhanced after stress peening, and smaller domain sizes and higher microstrain are introduced. The compressive residual stress enhancement by stress peening in ferrite is more than that in austenite under the same stress peening, which is due to the more elastic deformation recover in ferrite. Therefore, the difference of residual stresses between ferrite and austenite can be narrowed down by conducting appropriate stress peening. Based on these investigations, it is concluded that stress peening is superior to conventional shot peening treatment to improve the surface properties of duplex stainless steel

  5. Stress regulated members of the plant organic cation transporter family are localized to the vacuolar membrane

    Directory of Open Access Journals (Sweden)

    Koch Wolfgang

    2008-07-01

    Full Text Available Abstract Background In Arabidopsis six genes group into the gene family of the organic cation transporters (OCTs. In animals the members of the OCT-family are mostly characterized as polyspecific transporters involved in the homeostasis of solutes, the transport of monoamine neurotransmitters and the transport of choline and carnitine. In plants little is known about function, localisation and regulation of this gene family. Only one protein has been characterized as a carnitine transporter at the plasma membrane so far. Findings We localized the five uncharacterized members of the Arabidopsis OCT family, designated OCT2-OCT6, via GFP fusions and protoplast transformation to the tonoplast. Expression analysis with RNA Gel Blots showed a distinct, organ-specific expression pattern of the individual genes. With reporter gene fusion of four members we analyzed the tissue specific distribution of OCT2, 3, 4, and 6. In experiments with salt, drought and cold stress, we could show that AtOCT4, 5 and 6 are up-regulated during drought stress, AtOCT3 and 5 during cold stress and AtOCT 5 and 6 during salt stress treatments. Conclusion Localisation of the proteins at the tonoplast and regulation of the gene expression under stress conditions suggests a specific role for the transporters in plant adaptation to environmental stress.

  6. Nanobiosensors Based on Localized Surface Plasmon Resonance for Biomarker Detection

    Directory of Open Access Journals (Sweden)

    Yoochan Hong

    2012-01-01

    Full Text Available Localized surface plasmon resonance (LSPR is induced by incident light when it interacts with noble metal nanoparticles that have smaller sizes than the wavelength of the incident light. Recently, LSPR-based nanobiosensors were developed as tools for highly sensitive, label-free, and flexible sensing techniques for the detection of biomolecular interactions. In this paper, we describe the basic principles of LSPR-based nanobiosensing techniques and LSPR sensor system for biomolecule sensing. We also discuss the challenges using LSPR nanobiosensors for detection of biomolecules as a biomarker.

  7. Ability of multiaxial fatigue criteria accounting for stress gradient effect for surface defective material

    Directory of Open Access Journals (Sweden)

    Niamchaona Wichian

    2018-01-01

    Full Text Available New high strength steels are widely used nowadays in many industrial areas as in automotive industry. These steels are more resistant and provide higher fatigue limits than latter ones but they are also more sensible to small defects. Natural defects that outcome from metallurgy (as shrinkage, inclusion, void are not considered in this study. We focus on small manufacturing defects such as cutting edge defects generated by punching or other surface defects due to stamping. These defects are harmful on the material fatigue behaviour due to high stress concentration at defects root. They also generate stress gradient that is beneficial from the fatigue strength point of view. This study focusses on the stress gradient (it does not account for the size effect from cylindrical defect on specimen edge. Practically a normal stress gradient is added in multiaxial fatigue criteria formulation. Both critical plane approach and integral approach are involved in the present study. This gradient is calculated from stress states at defects root by using FEM. Criteria fatigue function at N cycles is used to assess the material fatigue strength. Obviously multiaxial fatigue criteria accounting for stress gradient give more precise fatigue functions than criteria that do not consider the gradient influence.

  8. Application of Volta potential mapping to determine metal surface defects

    International Nuclear Information System (INIS)

    Nazarov, A.; Thierry, D.

    2007-01-01

    As a rule, stress or fatigue cracks originate from various surface imperfections, such as pits, inclusions or locations showing a residual stress. It would be very helpful for material selection to be able to predict the likelihood of environment-assisted cracking or pitting corrosion. By using Scanning Kelvin Probe (the vibrating capacitor with a spatial resolution of 80 μm) the profiling of metal electron work function (Volta potential) in air is applied to the metal surfaces showing residual stress, MnS inclusions and wearing. The Volta potential is influenced by the energy of electrons at the Fermi level and drops generally across the metal/oxide/air interfaces. Inclusions (e.g. MnS) impair continuity of the passive film that locally decreases Volta potential. The stress applied gives rise to dislocations, microcracks and vacancies in the metal and the surface oxide. The defects decrease Volta and corrosion potentials; reduce the overvoltage for processes of passivity breakdown and anodic metal dissolution. These 'anodic' defects can be visualized in potential mapping that can help us to predict locations with higher risk of pitting corrosion or cracking

  9. Impact of highway construction on land surface energy balance and local climate derived from LANDSAT satellite data.

    Science.gov (United States)

    Nedbal, Václav; Brom, Jakub

    2018-08-15

    Extensive construction of highways has a major impact on the landscape and its structure. They can also influence local climate and heat fluxes in the surrounding area. After the removal of vegetation due to highway construction, the amount of solar radiation energy used for plant evapotranspiration (latent heat flux) decreases, bringing about an increase in landscape surface temperature, changing the local climate and increasing surface run-off. In this study, we evaluated the impact of the D8 highway construction (Central Bohemia, Czech Republic) on the distribution of solar radiation energy into the various heat fluxes (latent, sensible and ground heat flux) and related surface functional parameters (surface temperature and surface wetness). The aim was to describe the severity of the impact and the distance from the actual highway in which it can be observed. LANDSAT multispectral satellite images and field meteorological measurements were used to calculate surface functional parameters and heat balance before and during the highway construction. Construction of a four-lane highway can influence the heat balance of the landscape surface as far as 90m in the perpendicular direction from the highway axis, i.e. up to 75m perpendicular from its edge. During a summer day, the decrease in evapotranspired water can reach up to 43.7m 3 per highway kilometre. This means a reduced cooling effect, expressed as the decrease in latent heat flux, by an average of 29.7MWh per day per highway kilometre and its surroundings. The loss of the cooling ability of the land surface by evaporation can lead to a rise in surface temperature by as much as 7°C. Thus, the results indicate the impact of extensive line constructions on the local climate. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Blended 6-Hourly Sea Surface Wind Vectors and Wind Stress on a Global 0.25 Degree Grid (1987-2011)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Blended Global Sea Surface Winds products contain ocean surface wind vectors and wind stress on a global 0.25 degree grid, in multiple time resolutions of...

  11. Deriving the suction stress of unsaturated soils from water retention curve, based on wetted surface area in pores

    Science.gov (United States)

    Greco, Roberto; Gargano, Rudy

    2016-04-01

    The evaluation of suction stress in unsaturated soils has important implications in several practical applications. Suction stress affects soil aggregate stability and soil erosion. Furthermore, the equilibrium of shallow unsaturated soil deposits along steep slopes is often possible only thanks to the contribution of suction to soil effective stress. Experimental evidence, as well as theoretical arguments, shows that suction stress is a nonlinear function of matric suction. The relationship expressing the dependence of suction stress on soil matric suction is usually indicated as Soil Stress Characteristic Curve (SSCC). In this study, a novel equation for the evaluation of the suction stress of an unsaturated soil is proposed, assuming that the exchange of stress between soil water and solid particles occurs only through the part of the surface of the solid particles which is in direct contact with water. The proposed equation, based only upon geometric considerations related to soil pore-size distribution, allows to easily derive the SSCC from the water retention curve (SWRC), with the assignment of two additional parameters. The first parameter, representing the projection of the external surface area of the soil over a generic plane surface, can be reasonably estimated from the residual water content of the soil. The second parameter, indicated as H0, is the water potential, below which adsorption significantly contributes to water retention. For the experimental verification of the proposed approach such a parameter is considered as a fitting parameter. The proposed equation is applied to the interpretation of suction stress experimental data, taken from the literature, spanning over a wide range of soil textures. The obtained results show that in all cases the proposed relationships closely reproduces the experimental data, performing better than other currently used expressions. The obtained results also show that the adopted values of the parameter H0

  12. The Morphology, Dynamics and Potential Hotspots of Land Surface Temperature at a Local Scale in Urban Areas

    Directory of Open Access Journals (Sweden)

    Jiong Wang

    2015-12-01

    Full Text Available Current characterization of the Urban Heat Island (UHI remains insufficient to support the effective mitigation and adaptation of increasing temperatures in urban areas. Planning and design strategies are restricted to the investigation of temperature anomalies at a city scale. By focusing on Land Surface Temperature of Wuhan, China, this research examines the temperature variations locally where mitigation and adaptation would be more feasible. It shows how local temperature anomalies can be identified morphologically. Technically, the MODerate-resolution Imaging Spectroradiometer satellite image products are used. They are first considered as noisy observations of the latent temperature patterns. The continuous latent patterns of the temperature are then recovered from these discrete observations by using the non-parametric Multi-Task Gaussian Process Modeling. The Multi-Scale Shape Index is then applied in the area of focus to extract the local morphological features. A triplet of shape, curvedness and temperature is formed as the criteria to extract local heat islands. The behavior of the local heat islands can thus be quantified morphologically. The places with critical deformations are identified as hotpots. The hotspots with certain yearly behavior are further associated with land surface composition to determine effective mitigation and adaptation strategies. This research can assist in the temperature and planning field on two levels: (1 the local land surface temperature patterns are characterized by decomposing the variations into fundamental deformation modes to allow a process-based understanding of the dynamics; and (2 the characterization at local scale conforms to planning and design conventions where mitigation and adaptation strategies are supposed to be more practical. The weaknesses and limitations of the study are addressed in the closing section.

  13. Cell surface estrogen receptor alpha is upregulated during subchronic metabolic stress and inhibits neuronal cell degeneration.

    Directory of Open Access Journals (Sweden)

    Cristiana Barbati

    Full Text Available In addition to the classical nuclear estrogen receptor, the expression of non-nuclear estrogen receptors localized to the cell surface membrane (mER has recently been demonstrated. Estrogen and its receptors have been implicated in the development or progression of numerous neurodegenerative disorders. Furthermore, the pathogenesis of these diseases has been associated with disturbances of two key cellular programs: apoptosis and autophagy. An excess of apoptosis or a defect in autophagy has been implicated in neurodegeneration. The aim of this study was to clarify the role of ER in determining neuronal cell fate and the possible implication of these receptors in regulating either apoptosis or autophagy. The human neuronal cell line SH-SY5Y and mouse neuronal cells in primary culture were thus exposed to chronic minimal peroxide treatment (CMP, a form of subcytotoxic minimal chronic stress previously that mimics multiple aspects of long-term cell stress and represents a limited molecular proxy for neurodegenerative processes. We actually found that either E2 or E2-bovine serum albumin construct (E2BSA, i.e. a non-permeant form of E2 was capable of modulating intracellular cell signals and regulating cell survival and death. In particular, under CMP, the up-regulation of mERα, but not mERβ, was associated with functional signals (ERK phosphorylation and p38 dephosphorylation compatible with autophagic cytoprotection triggering and leading to cell survival. The mERα trafficking appeared to be independent of the microfilament system cytoskeletal network but was seemingly associated with microtubular apparatus network, i.e., to MAP2 molecular chaperone. Importantly, antioxidant treatments, administration of siRNA to ERα, or the presence of antagonist of ERα hindered these events. These results support that the surface expression of mERα plays a pivotal role in determining cell fate, and that ligand-induced activation of mER signalling exerts a

  14. Application of X-rays and Synchrotron X Rays to Residual Stress Evaluation Near Surfaces

    International Nuclear Information System (INIS)

    Pyzalla, Anke

    1999-01-01

    A nondestructive residual stress analysis can be performed using diffraction methods. The easiest accessible radiation is characteristic X radiation that has a penetration depth of ∼10 microm suitable for the determination of the residual stresses in near-surface layers. Special techniques have been developed, e.g., with respect to in situ analyses of the stress state in oxide layers and the residual stress analysis in coarse grained zones of steel welds or annealed Ni-base alloys. Depending on the size of the gauge volume, neutron diffraction can provide information at depths of tens of millimetres of steel and many tens of millimetres of Al. An alternative to the use of the characteristic synchrotron radiation is the use of a high-energy polychromatic beam in an energy dispersive arrangement, which gives access to higher penetration depths at still gauge volumes as small as 100 microm x 100 microm x 1 mm in steel rods of 15-mm diameter. The combination of neutrons with conventional X rays and monochromatic and polychromatic synchrotron radiation allows for a comprehensive investigation of the phase composition, the texture, and the residual stresses

  15. Thermographic Analysis of Stress Distribution in Welded Joints

    Directory of Open Access Journals (Sweden)

    Domazet Ž.

    2010-06-01

    Full Text Available The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

  16. Thermographic Analysis of Stress Distribution in Welded Joints

    Science.gov (United States)

    Piršić, T.; Krstulović Opara, L.; Domazet, Ž.

    2010-06-01

    The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural) stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis) in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

  17. Local excitation of surface plasmon polaritons by second-harmonic generation in crystalline organic nanofibers

    DEFF Research Database (Denmark)

    Skovsen, Esben; Søndergaard, Thomas; Fiutowski, Jacek

    2012-01-01

    Coherent local excitation of surface plasmon polaritons (SPPs) by second-harmonic generation (SHG) in aligned crystalline organic functionalized para-phenylene nanofibers deposited on a thin silver film is demonstrated. The excited SPPs are characterized using angle-resolved leakage radiation...

  18. Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

    Science.gov (United States)

    Maeda, Yoshitaka; Urata, Shinya; Nakai, Hideo; Takeuchi, Yuuya; Yun, Kyyoul; Yanase, Shunji; Okazaki, Yasuo

    2017-05-01

    In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D) magnetic properties (properties under the arbitrary alternating and the rotating flux conditions) of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

  19. Tuning the interaction between propagating and localized surface plasmons for surface enhanced Raman scattering in water for biomedical and environmental applications

    Energy Technology Data Exchange (ETDEWEB)

    Shioi, Masahiko, E-mail: shioi.masahiko@jp.panasonic.com [Device Solutions Center, Panasonic Corporation, 3-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan); Department of Electric and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan); Jans, Hilde [Interuniversity Microelectronics Center VZW., Kapeldreef 75, 3001 Leuven (Belgium); Lodewijks, Kristof [Interuniversity Microelectronics Center VZW., Kapeldreef 75, 3001 Leuven (Belgium); Department of Electrical Engineering, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Van Dorpe, Pol; Lagae, Liesbet [Interuniversity Microelectronics Center VZW., Kapeldreef 75, 3001 Leuven (Belgium); Department of Physics, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Kawamura, Tatsuro [Device Solutions Center, Panasonic Corporation, 3-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)

    2014-06-16

    With a view to biomedical and environmental applications, we investigate the plasmonic properties of a rectangular gold nanodisk array in water to boost surface enhanced Raman scattering (SERS) effects. To control the resonance wavelengths of the surface plasmon polariton and the localized surface plasmon, their dependence on the array period and diameter in water is studied in detail using a finite difference time domain method. A good agreement is obtained between calculated resonant wavelengths and those of gold nanodisk arrays fabricated using electron beam lithography. For the optimized structure, a SERS enhancement factor of 7.8 × 10{sup 7} is achieved in water experimentally.

  20. Mechanotransduction across the cell surface and through the cytoskeleton

    Science.gov (United States)

    Wang, N.; Butler, J. P.; Ingber, D. E.

    1993-01-01

    Mechanical stresses were applied directly to cell surface receptors with a magnetic twisting device. The extracellular matrix receptor, integrin beta 1, induced focal adhesion formation and supported a force-dependent stiffening response, whereas nonadhesion receptors did not. The cytoskeletal stiffness (ratio of stress to strain) increased in direct proportion to the applied stress and required intact microtubules and intermediate filaments as well as microfilaments. Tensegrity models that incorporate mechanically interdependent struts and strings that reorient globally in response to a localized stress mimicked this response. These results suggest that integrins act as mechanoreceptors and transmit mechanical signals to the cytoskeleton. Mechanotransduction, in turn, may be mediated simultaneously at multiple locations inside the cell through force-induced rearrangements within a tensionally integrated cytoskeleton.

  1. The shortcomings of semi-local and hybrid functionals: what we can learn from surface science studies

    International Nuclear Information System (INIS)

    Stroppa, A; Kresse, G

    2008-01-01

    A study of the adsorption of CO on late 4d and 5d transition metal (111) surfaces (Ru, Rh, Pd, Ag, Os, Ir and Pt) considering atop and hollow site adsorption is presented. The applied functionals include the gradient-corrected Perdew-Burke-Ernzerhof (PBE) and Becke-Lee-Yang-Parr (BLYP) functionals, and the corresponding hybrid Hartree-Fock density functionals HSE and B3LYP. We find that PBE-based hybrid functionals (specifically HSE) yield, with the exception of Pt, the correct site order on all considered metals, but they also considerably overestimate the adsorption energies compared to experiment. On the other hand, the semi-local BLYP functional and the corresponding hybrid functional B3LYP yield very satisfactory adsorption energies and the correct adsorption site for all surfaces. We are thus faced with a Procrustean problem: the B3LYP and BLYP functionals seem to be the overall best choice for describing adsorption on metal surfaces, but they simultaneously fail to account well for the properties of the metal, vastly overestimating the equilibrium volume and underestimating the atomization energies. Setting out from these observations, general conclusions are drawn on the relative merits and drawbacks of various semi-local and hybrid functionals. The discussion includes a revised version of the PBE functional specifically optimized for bulk properties and surface energies (PBEsol), a revised version of the PBE functional specifically optimized to predict accurate adsorption energies (rPBE), as well as the aforementioned BLYP functional. We conclude that no semi-local functional is capable of describing all aspects properly, and including non-local exchange also only improves some but worsens other properties

  2. Stress evaluation of baffle former bolt for IASCC failure prediction

    International Nuclear Information System (INIS)

    Matsubara, T.; Tsutsui, T.; Kamei, Y.; Kitsu, M.

    2011-01-01

    Baffle structure in PWRs Reactor is quite important assembly for the core safety, and Baffle Former Bolts (BFBs) are fastener members for maintaining Baffle structure. It has been reported worldwide that some of BFBs were cracked due to IASCC (Irradiation Assisted Stress Corrosion Cracking) because BFBs are located at core region under severe environments, high neutron flux, high temperature and high stress. According to the material studies of IASCC on austenitic stainless steel, a crack initiation of IASCC is strongly related with the stress and the neutron fluence. For this reason, it is very important for IASCC failure prediction to simulate the stress of BFBs. However, the stress of BFBs are considered to be influenced by several factors and to be changed complexly as operational time increases, by irradiation creep of Bolt itself, swelling of Baffle structure, and so on. Therefore, it is difficult to estimate the stress histories of BFBs (Bolt stress as a function of operational time) precisely. Then, the author has developed the calculation method of the stress histories of BFBs considering irradiation effects (swelling and irradiation creep). In this method, the stress histories of BFBs are calculated by combining two kinds of FE models, Global model (modeled whole Baffle structure which consists of Baffle plates, Former plates and Core Barrel) and Local model (modeled around BFB finely). The whole Baffle structure deformation changes as a function of heat, swelling and irradiated creep are calculated by Global model, and the stress histories of BFBs are calculated by Local model using the outputs (deformations on driving nodes) of Global model. In the FE analysis of Local model, the stress of BFBs are calculated considering irradiation effects and elastic-plastic characteristics depending on neutron fluence, so this method enables to calculate precisely the stress of extreme small area of BFBs surface. This paper shows the outline of the calculation method

  3. Elastic-plastic fracture mechanics analysis of a pressure vessel with an axial outer surface flaw. Pt. 2

    International Nuclear Information System (INIS)

    Brocks, W.; Kuenecke, G.

    1989-06-01

    Continuing preceding investigations, a further elastic-plastic finite element analysis of a test vessel with a semi-elliptical axial outer surface crack has been performed. The variations of J and CTOD along the crack front and the stress state in the vicinity of the crack are presented. The applicability of analytical approaches to determine J is examined. The FE results are used to analyze the experimental data with respect to the validity of J-controlled crack growth. Local J R -curves of the surface flaw are compared with J R -curves of various specimens of different geometries. Again, it became evident that the local ductile crack growth and, especially, the developing 'canoe shape' of the surface crack cannot be described by a single resistance curve which is assumed to be a material property. A method described in a previous report to predict the ductile crack growth by using local J R -curves which depend on the triaxiality of the stress state did not result in a satisfactory outcome, in the present case. The presumed reasons will be discussed. (orig.) [de

  4. Perceived child behaviour problems, parenting stress, and marital satisfaction: comparison of new arrival and local parents of preschool children in Hong Kong.

    Science.gov (United States)

    Leung, Shirley S L; Leung, Cynthia; Chan, Ruth

    2007-10-01

    To compare parental perception of child behaviour problems, parenting stress, and marital satisfaction in new arrival and local parents. Cross-sectional survey; semi-structured interview. Maternal and Child Health Centres, social service centres, preschools. Parents of preschool children, including new arrival parents and local parents. Child behaviour problems, parenting stress, and marital satisfaction. After controlling for socio-economic factors, new arrival parents were more troubled by their children's behaviour problems and their parent-child interactions were more dysfunctional than those of local parents. There were no differences in parent-reported severity of child behaviour problems, parental distress, and marital satisfaction. New arrival parents reported difficulties in adapting to the new living environment and lack of social support. New arrival parents were more troubled by their children's behaviour, and their parent-child interactions were more dysfunctional than those of local parents. These might in part be related to their settlement difficulties. Parenting programmes should address their specific settlement needs.

  5. Surface plasmon quantum cascade lasers as terahertz local oscillators.

    Science.gov (United States)

    Hajenius, M; Khosropanah, P; Hovenier, J N; Gao, J R; Klapwijk, T M; Barbieri, S; Dhillon, S; Filloux, P; Sirtori, C; Ritchie, D A; Beere, H E

    2008-02-15

    We characterize a heterodyne receiver based on a surface-plasmon waveguide quantum cascade laser (QCL) emitting at 2.84 THz as a local oscillator, and an NbN hot electron bolometer as a mixer. We find that the envelope of the far-field pattern of the QCL is diffraction-limited and superimposed onto interference fringes, which are similar to those found in narrow double-metal waveguide QCLs. Compared to the latter, a more directional beam allows for better coupling of the radiation power to the mixer. We obtain a receiver noise temperature of 1050 K when the mixer is at 2 K, which, to our knowledge, is the highest sensitivity reported at frequencies beyond 2.5 THz.

  6. Residual stress measurement with focused acoustic waves and direct comparison with X-ray diffraction stress measurements

    International Nuclear Information System (INIS)

    Sathish, Shamachary; Moran, Thomas J.; Martin, Richard W.; Reibel, Richard

    2005-01-01

    The technique of measuring small changes in acoustic wave velocity due to external or internal stress has been used for quantitative determination of residual stress in materials during the last decade. Application of similar methodology with focused acoustic waves leads to residual stress measurement with spatial resolution of a few millimeters to a few microns. The high spatial resolution residual stress measurement required development of new methodologies in both the design of acoustic lenses and the instrumentation for acoustic wave velocity determination. This paper presents two new methodologies developed for the measurement of residual stress with spatial resolution of a few millimeters. The design of new type of acoustic lens for achieving higher spatial resolution in residual stress measurement is introduced. Development of instrumentation for high precision local surface wave velocity measurement will be presented. Residual stresses measured around a crack tip in a sample of Ti-6A1-4V using a focused beam will be compared with X-ray diffraction measurements performed on the same region of the sample. Results of residual stress measurements along a direction perpendicular to the electron beam weld in a sample of Ti-6A1-4V, determined using focused acoustic waves and X-ray diffraction technique, are also presented. The spatial resolution and penetration depth of X-rays and focused acoustic beams with reference to residual stress measurements are discussed

  7. The effects of work surface hardness on mechanical stress, muscle activity, and wrist postures.

    Science.gov (United States)

    Kim, Jeong Ho; Aulck, Lovenoor; Trippany, David; Johnson, Peter W

    2015-01-01

    Contact pressure is a risk factor which can contribute to musculoskeletal disorders. The objective of the present study was to determine whether a work surface with a soft, pliable front edge could reduce contact pressure, muscle activity, and subjective musculoskeletal comfort, and improve wrist posture relative to a conventional, hard work surface. In a repeated-measures blinded experiment with eighteen subjects (8 females and 10 males), contact pressure, wrist posture, typing productivity, perceived fatigue, wrist and shoulder muscle activity, and subjective comfort were compared between the two different work surfaces during keyboard use, mouse use and mixed mouse and keyboard use. The results showed that across the three modes of computer work, the contact pressure was lower on the soft-edge work surface compared to the conventional work surface (p's work surfaces. Given the significant reduction in contact pressure and corresponding lower ratings in perceived fatigue, the soft-edge work surface subjectively and objectively improved measures of contact stress which may reduce physical exposures associated with the onset and development of musculoskeletal disorders.

  8. The role of surface roughness on dislocation bending and stress evolution in low mobility AlGaN films during growth

    Science.gov (United States)

    Bardhan, Abheek; Mohan, Nagaboopathy; Chandrasekar, Hareesh; Ghosh, Priyadarshini; Sridhara Rao, D. V.; Raghavan, Srinivasan

    2018-04-01

    The bending and interaction of threading dislocations are essential to reduce their density for applications involving III-nitrides. Bending of dislocation lines also relaxes the compressive growth stress that is essential to prevent cracking on cooling down due to tensile thermal expansion mismatch stress while growing on Si substrates. It is shown in this work that surface roughness plays a key role in dislocation bending. Dislocations only bend and relax compressive stresses when the lines intersect a smooth surface. These films then crack. In rough films, dislocation lines which terminate at the bottom of the valleys remain straight. Compressive stresses are not relaxed and the films are relatively crack-free. The reasons for this difference are discussed in this work along with the implications on simultaneously meeting the requirements of films being smooth, crack free and having low defect density for device applications.

  9. Cellular Stress Response to Engineered Nanoparticles: Effect of Size, Surface Coating, and Cellular Uptake

    Science.gov (United States)

    CELLULAR STRESS RESPONSE TO ENGINEERED NANOPARTICLES: EFFECT OF SIZE, SURFACE COATING, AND CELLULAR UPTAKE RY Prasad 1, JK McGee2, MG Killius1 D Ackerman2, CF Blackman2 DM DeMarini2 , SO Simmons2 1 Student Services Contractor, US EPA, RTP, NC 2 US EPA, RTP, NC The num...

  10. Understanding of surface pit formation mechanism of GaN grown in MOCVD based on local thermodynamic equilibrium assumption

    Science.gov (United States)

    Zhi-Yuan, Gao; Xiao-Wei, Xue; Jiang-Jiang, Li; Xun, Wang; Yan-Hui, Xing; Bi-Feng, Cui; De-Shu, Zou

    2016-06-01

    Frank’s theory describes that a screw dislocation will produce a pit on the surface, and has been evidenced in many material systems including GaN. However, the size of the pit calculated from the theory deviates significantly from experimental result. Through a careful observation of the variations of surface pits and local surface morphology with growing temperature and V/III ratio for c-plane GaN, we believe that Frank’s model is valid only in a small local surface area where thermodynamic equilibrium state can be assumed to stay the same. If the kinetic process is too vigorous or too slow to reach a balance, the local equilibrium range will be too small for the center and edge of the screw dislocation spiral to be kept in the same equilibrium state. When the curvature at the center of the dislocation core reaches the critical value 1/r 0, at the edge of the spiral, the accelerating rate of the curvature may not fall to zero, so the pit cannot reach a stationary shape and will keep enlarging under the control of minimization of surface energy to result in a large-sized surface pit. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204009 and 61204011) and the Beijing Municipal Natural Science Foundation, China (Grant No. 4142005).

  11. Plasticity and stress tolerance override local adaptation in the responses of Mediterranean holm oak seedlings to drought and cold.

    Science.gov (United States)

    Gimeno, Teresa E; Pías, Beatriz; Lemos-Filho, José P; Valladares, Fernando

    2009-01-01

    Plant populations of widely distributed species experience a broad range of environmental conditions that can be faced by phenotypic plasticity or ecotypic differentiation and local adaptation. The strategy chosen will determine a population's ability to respond to climate change. To explore this, we grew Quercus ilex (L.) seedlings from acorns collected at six selected populations from climatically contrasting localities and evaluated their response to drought and late season cold events. Maximum photosynthetic rate (A(max)), instantaneous water use efficiency (iWUE), and thermal tolerance to freeze and heat (estimated from chlorophyll fluorescence versus temperature curves) were measured in 5-month-old seedlings in control (no stress), drought (water-stressed), and cold (low suboptimal temperature) conditions. The observed responses were similar for the six populations: drought decreased A(max) and increased iWUE, and cold reduced A(max) and iWUE. All the seedlings maintained photosynthetic activity under adverse conditions (drought and cold), and rapidly increased their iWUE by closing stomata when exposed to drought. Heat and freeze tolerances were similarly high for seedlings from all the populations, and they were significantly increased by drought and cold, respectively; and were positively related to each other. Differences in seedling performance across populations were primarily induced by maternal effects mediated by seed size and to a lesser extent by idiosyncratic physiologic responses to drought and low temperatures. Tolerance to multiple stresses together with the capacity to physiologically acclimate to heat waves and cold snaps may allow Q. ilex to cope with the increasingly stressful conditions imposed by climate change. Lack of evidence of physiologic seedling adaptation to local climate may reflect opposing selection pressures to complex, multidimensional environmental conditions operating within the distribution range of this species.

  12. Analysis of rainfall-induced slope instability using a field of local factor of safety

    Science.gov (United States)

    Lu, Ning; Şener-Kaya, Başak; Wayllace, Alexandra; Godt, Jonathan W.

    2012-01-01

    Slope-stability analyses are mostly conducted by identifying or assuming a potential failure surface and assessing the factor of safety (FS) of that surface. This approach of assigning a single FS to a potentially unstable slope provides little insight on where the failure initiates or the ultimate geometry and location of a landslide rupture surface. We describe a method to quantify a scalar field of FS based on the concept of the Coulomb stress and the shift in the state of stress toward failure that results from rainfall infiltration. The FS at each point within a hillslope is called the local factor of safety (LFS) and is defined as the ratio of the Coulomb stress at the current state of stress to the Coulomb stress of the potential failure state under the Mohr-Coulomb criterion. Comparative assessment with limit-equilibrium and hybrid finite element limit-equilibrium methods show that the proposed LFS is consistent with these approaches and yields additional insight into the geometry and location of the potential failure surface and how instability may initiate and evolve with changes in pore water conditions. Quantitative assessments applying the new LFS field method to slopes under infiltration conditions demonstrate that the LFS has the potential to overcome several major limitations in the classical FS methodologies such as the shape of the failure surface and the inherent underestimation of slope instability. Comparison with infinite-slope methods, including a recent extension to variably saturated conditions, shows further enhancement in assessing shallow landslide occurrence using the LFS methodology. Although we use only a linear elastic solution for the state of stress with no post-failure analysis that require more sophisticated elastoplastic or other theories, the LFS provides a new means to quantify the potential instability zones in hillslopes under variably saturated conditions using stress-field based methods.

  13. Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Yasuhiro, E-mail: chimi.yasuhiro@jaea.go.jp [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kitsunai, Yuji [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Kasahara, Shigeki [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Chatani, Kazuhiro; Koshiishi, Masato [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Nishiyama, Yutaka [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2016-07-15

    To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%–2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps. - Highlights: • Visible step structures depend on the neutron dose and the applied strain. • Local strain at grain boundaries was accumulated with the neutron dose. • Oxide thickness increases with neutron dose and local strain at grain boundaries. • No penetrative oxidation was observed along grain boundaries or surface steps.

  14. Local pressure gradients due to incipience of boiling in subcooled flows

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles, A.E.; McDuffee, J.L. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-09-01

    Models for vapor bubble behavior and nucleation site density during subcooled boiling are integrated with boundary layer theory in order to predict the local pressure gradient and heat transfer coefficient. Models for bubble growth rate and bubble departure diameter are used to scale the movement of displaced liquid in the laminar sublayer. An added shear stress, analogous to a turbulent shear stress, is derived by considering the liquid movement normal to the heated surface. The resulting mechanistic model has plausible functional dependence on wall superheat, mass flow, and heat flux and agrees well with data available in the literature.

  15. Cortical surface area reduction in identification of subjects at high risk for post-traumatic stress disorder: A pilot study.

    Science.gov (United States)

    Hu, Hao; Sun, Yawen; Su, Shanshan; Wang, Yao; Qiu, Yongming; Yang, Xi; Zhou, Yan; Xiao, Zeping; Wang, Zhen

    2018-01-01

    Victims of motor vehicle accidents often develop post-traumatic stress disorder, which causes significant social function loss. For the difficulty in treating post-traumatic stress disorder, identification of subjects at high risk for post-traumatic stress disorder is essential for providing possible intervention. This paper aims to examine the cortical structural traits related to susceptibility to post-traumatic stress disorder. To address this issue, we performed structural magnetic resonance imaging study in motor vehicle accident victims within 48 hours from the accidents. A total of 70 victims, available for both clinical and magnetic resonance imaging data, enrolled in our study. Upon completion of 6-month follow-up, 29 of them developed post-traumatic stress disorder, while 41 of them didn't. At baseline, voxelwise comparisons of cortical thickness, cortical area and cortical volume were conducted between post-traumatic stress disorder group and trauma control group. As expected, several reduced cortical volume within frontal-temporal loop were observed in post-traumatic stress disorder. For cortical thickness, no between-group differences were observed. There were three clusters in left hemisphere and one cluster in right hemisphere showing decreased cortical area in post-traumatic stress disorder patients, compared with trauma controls. Peak voxels of the three clusters in left hemisphere were separately located in superior parietal cortex, insula and rostral anterior cingulate cortex. The finding of reduced surface area of left insula and left rostral anterior cingulate cortex suggests that shrinked surface area in motor vehicle accident victims could act as potential biomarker of subjects at high risk for post-traumatic stress disorder.

  16. Computational fluid dynamics (CFD) insights into agitation stress methods in biopharmaceutical development.

    Science.gov (United States)

    Bai, Ge; Bee, Jared S; Biddlecombe, James G; Chen, Quanmin; Leach, W Thomas

    2012-02-28

    Agitation of small amounts of liquid is performed routinely in biopharmaceutical process, formulation, and packaging development. Protein degradation commonly results from agitation, but the specific stress responsible or degradation mechanism is usually not well understood. Characterization of the agitation stress methods is critical to identifying protein degradation mechanisms or specific sensitivities. In this study, computational fluid dynamics (CFD) was used to model agitation of 1 mL of fluid by four types of common laboratory agitation instruments, including a rotator, orbital shaker, magnetic stirrer and vortex mixer. Fluid stresses in the bulk liquid and near interfaces were identified, quantified and compared. The vortex mixer provides the most intense stresses overall, while the stir bar system presented locally intense shear proximal to the hydrophobic stir bar surface. The rotator provides gentler fluid stresses, but the air-water interfacial area and surface stresses are relatively high given its low rotational frequency. The orbital shaker provides intermediate-level stresses but with the advantage of a large stable platform for consistent vial-to-vial homogeneity. Selection of experimental agitation methods with targeted types and intensities of stresses can facilitate better understanding of protein degradation mechanisms and predictability for "real world" applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Evaluation of stress intensity factor for craks in surface of tubes with internal pressure

    International Nuclear Information System (INIS)

    Cesari, F.; Hellen, T.K.

    1977-01-01

    In this report the authors have examined the different methods for calculation of the stress intensity factor in tubes subject at internal pressure with surface cracks. The analysis includes cracks in 2-D axialsymmetric and 3-D. Moreover the authors have clarified the difference between the ASME Sec.11 and the procedure more rigorous

  18. Thermal stresses calculations in near-surface layers of sphere bodies, falling to the Sun

    International Nuclear Information System (INIS)

    Demchenko, B.I.; Shestakova, L.I.

    2005-01-01

    Profiles of temperature and temperature stresses in surface layers of silicate and icy spheric bodies, falling to the Sun along parabolic orbits were obtained on the base of the analytical solution of the linear heat diffusion equation. Results may be useful for thermal evolution analysis of meteor and comet bodies in the Sun system. (author)

  19. Local environmental conditions and the stability of protective layers on steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J P [Technical Univ. of Denmark, Lyngby (Denmark); Bursik, A

    1996-12-01

    Local environmental conditions determine whether the protective layers on steel surfaces are stable. With unfavorable local environmental conditions, the protective layers may be subject to damage. Taking the cation conductivity of all plant cycle streams <0.2 {mu}S/cm for granted, an adequate feed-water and - if applicable - boiler water conditioning is required to prevent such damage. Even if the mentioned conditions are met in a bulk, the local environmental conditions may be inadequate. The reasons for this may be the disregarding of interactions among material, design, and chemistry. The paper presents many possible mechanisms of protective layer damage that are directly influenced or exacerbated by plant cycle chemistry. Two items are discussed in more detail: First, the application of all volatile treatment for boiler water conditioning of drum boiler systems operating at low pressures and, second, the chemistry in the transition zone water/steam in the low pressure turbine. The latter is of major interest for the understanding and prevention of corrosion due to high concentration of impurities in the aqueous liquid phases. This is a typical example showing that local environmental conditions may fundamentally differ from the overall bulk chemistry. (au) 19 refs.

  20. An experimental and numerical investigation into the single-fibre fragmentation test : stress transfer by a locally yielding matrix

    NARCIS (Netherlands)

    van den Heuvel, P.W.J.; Hogeweg, B.; Peijs, A.A.J.M.

    1997-01-01

    Single-fibre fragmentation tests on carbon/epoxy microcomposites were performed using carbon fibres with surface treatment levels varying from 0 to 200% of the commercial fibre surface treatment, i.e. 100%. Polarized light microscopy showed substantial local matrix yielding near the fibre-matrix

  1. Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA surface mass density-metallicity relation

    Science.gov (United States)

    Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zhu, Guangtun B.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Law, David; Wake, David; Green, Jenny E.; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena; Pan, Kaike; Roman Lopes, Alexandre; Lane, Richard R.

    2016-12-01

    We present the stellar surface mass density versus gas metallicity (Σ*-Z) relation for more than 500 000 spatially resolved star-forming resolution elements (spaxels) from a sample of 653 disc galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of 4 in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disc galaxies: their global mass-metallicity relationship and their radial metallicity gradients. We also find that the Σ*-Z relation is largely independent of the galaxy's total stellar mass and specific star formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disc galaxies.

  2. The impact of heat waves on surface urban heat island and local economy in Cluj-Napoca city, Romania

    Science.gov (United States)

    Herbel, Ioana; Croitoru, Adina-Eliza; Rus, Adina Viorica; Roşca, Cristina Florina; Harpa, Gabriela Victoria; Ciupertea, Antoniu-Flavius; Rus, Ionuţ

    2017-07-01

    The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day

  3. A Simple Approach for Local Contact Angle Determination on a Heterogeneous Surface

    KAUST Repository

    Wu, Jinbo

    2011-05-17

    We report a simple approach for measuring the local contact angle of liquids on a heterogeneous surface consisting of intersected hydrophobic and hydrophilic patch arrays, specifically by employing confocal microscopy and the addition of a very low concentration of Rhodamine-B (RB) (2 × 10 -7 mol/L). Interestingly, RB at that concentration was found to be aggregated at the air-liquid and solid (hydrophobic patch only)-liquid interfaces, which helps us to distinguish the liquid and solid interfaces as well as hydrophobic and hydrophilic patches by their corresponding fluorescent intensities. From the measured local contact angles, the line tension can be easily derived and the value is found to be (-2.06-1.53) × 10-6 J/m. © 2011 American Chemical Society.

  4. Topological open string amplitudes on local toric del Pezzo surfaces via remodeling the B-model

    International Nuclear Information System (INIS)

    Manabe, Masahide

    2009-01-01

    We study topological strings on local toric del Pezzo surfaces by a method called remodeling the B-model which was recently proposed by Bouchard, Klemm, Marino and Pasquetti. For a large class of local toric del Pezzo surfaces we prove a functional formula of the Bergman kernel which is the basic constituent of the topological string amplitudes by the topological recursion relation of Eynard and Orantin. Because this formula is written as a functional of the period, we can obtain the topological string amplitudes at any point of the moduli space by a simple change of variables of the Picard-Fuchs equations for the period. By this formula and mirror symmetry we compute the A-model amplitudes on K F 2 , and predict the open orbifold Gromov-Witten invariants of C 3 /Z 4 .

  5. METHODS FOR LOCAL CHANGES IN THE PLASTIC DEFORMATION DIAGNOSTICS ON THE WORK FUNCTION

    Directory of Open Access Journals (Sweden)

    K. V. Panteleyev

    2015-01-01

    Full Text Available The paper describes the electronic work function measurements by the contact potential difference technique, and experimental demonstration of the possibility of these methods application for the stress-strain state of the surface layer of the metals and alloys. The techniques end examples of their application of localization of plastic deformation studies using the Kelvin probe are developed and present. The study topology of work function the deformed surface possible to determine the type of deformation and dynamics of

  6. Effects of surface chromium depletion on localized corrosion of alloy 825 as a high-level nuclear waste container material

    International Nuclear Information System (INIS)

    Dunn, D.S.; Sridhar, N.; Cragnolino, G.A.

    1995-01-01

    Effects of the chromium-depleted, mill-finished surface on the localized corrosion resistance of alloy 825 (UNS N08825) were investigated. Tests were conducted in solutions based on the ground water at Yucca mountain, Nevada, but with a higher concentration of chloride. Results indicated that breakdown (E p ) and repassivation (E rp ) potentials for mill-finished surfaces were more active than those for polished surfaces. Potentiodynamic polarization tests indicated pits could be initiated on the chromium-depleted surface at potentials of 220 mV SCE in a solution containing 1,000 ppm Cl - at 95 C. Potentiostatic tests identified a similar pit initiation potential for the mill-finished surface. However, under longterm potentiostatic tests, a higher potential of 300 mV SCE was needed to sustain stable pit growth beyond the chromium-depleted layer. An increase in surface roughness also was observed to decrease localized corrosion resistance of the material

  7. Evolution of the lower planetary boundary layer over strongly contrasting surfaces

    International Nuclear Information System (INIS)

    Coulter, R.L.; Gao, W.; Martin, T.J.; Shannon, J.D.; Doran, J.C.; Hubbe, J.M.; Shaw, W.M.

    1992-01-01

    In a multilaboratory field study held near Boardman in northeastern Oregon in June 1991, various properties of the surface and lower atmospheric boundary layer over heavily irrigated cropland and adjacent desert steppe were investigated in the initial campaign of the Atmospheric Radiation Measurement (ARM) program. The locale was selected because its disparate characteristics over various spatial scales stress the ability of general circulation models (GCMS) to describe lower boundary conditions, particularly across the discontinuity between desert (in which turbulent flux of heat must be primarily as sensible heat) and large irrigated tracts (in which turbulent flux of latent heat should be the larger term). This campaign of ARM seeks to increase knowledge in three critical areas: (1) determination of the relationships between surface heat fluxes measured over multiple scales and the controlling surface parameters within each scale, (2) integration of local and nearly local heat flux estimates to produce estimates appropriate for GCM grid cells of 100-200 km horizontal dimension, and (3) characterization of the growth and development of the atmospheric boundary layer near transitions between surfaces with strongly contrasting moisture availabilities

  8. Effectiveness of various isometric exercises at improving bone strength in cortical regions prone to distal tibial stress fractures.

    Science.gov (United States)

    Florio, C S

    2018-06-01

    A computational model was used to compare the local bone strengthening effectiveness of various isometric exercises that may reduce the likelihood of distal tibial stress fractures. The developed model predicts local endosteal and periosteal cortical accretion and resorption based on relative local and global measures of the tibial stress state and its surface variation. Using a multisegment 3-dimensional leg model, tibia shape adaptations due to 33 combinations of hip, knee, and ankle joint angles and the direction of a single or sequential series of generated isometric resultant forces were predicted. The maximum stress at a common fracture-prone region in each optimized geometry was compared under likely stress fracture-inducing midstance jogging conditions. No direct correlations were found between stress reductions over an initially uniform circular hollow cylindrical geometry under these critical design conditions and the exercise-based sets of active muscles, joint angles, or individual muscle force and local stress magnitudes. Additionally, typically favorable increases in cross-sectional geometric measures did not guarantee stress decreases at these locations. Instead, tibial stress distributions under the exercise conditions best predicted strengthening ability. Exercises producing larger anterior distal stresses created optimized tibia shapes that better resisted the high midstance jogging bending stresses. Bent leg configurations generating anteriorly directed or inferiorly directed resultant forces created favorable adaptations. None of the studied loads produced by a straight leg was significantly advantageous. These predictions and the insight gained can provide preliminary guidance in the screening and development of targeted bone strengthening techniques for those susceptible to distal tibial stress fractures. Copyright © 2018 John Wiley & Sons, Ltd.

  9. Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

    Directory of Open Access Journals (Sweden)

    Yoshitaka Maeda

    2017-05-01

    Full Text Available In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D magnetic properties (properties under the arbitrary alternating and the rotating flux conditions of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

  10. Finite element analysis of the influence of elastic anisotropy on stress intensification at stress corrosion cracking initiation sites in fcc alloys

    Science.gov (United States)

    Meric de Bellefon, G.; van Duysen, J. C.

    2018-05-01

    A recent finite-element method (FEM)-based study from the present authors quantified the effect of elastic anisotropy of grains on stress intensification at potential intergranular stress corrosion cracking (IGSCC) initiation sites in austenitic stainless steels. In particular, it showed that the auxetic behavior of grains (negative Poisson's ratio) in some directions plays a very important role in IGSCC initiation, since it can induce local stress intensification factors of about 1.6. A similar effect is expected for other fcc alloys such as Ni-based alloys. The present article confirms those results and paves the way to the definition of an IGSCC susceptibility index by identifying grain configurations that are the most favorable for crack initiation. The index will rely on the probability to get those configurations on surface of specimens.

  11. The Contribution of Io-Raised Tides to Europa's Diurnally-Varying Surface Stresses

    Science.gov (United States)

    Rhoden, Alyssa Rose; Hurford, Terry A,; Manga, Michael

    2011-01-01

    Europa's icy surface records a rich history of geologic activity, Several features appear to be tectonic in origin and may have formed in response to Europa's daily-varying tidal stress [I]. Strike-slip faults and arcuate features called cycloids have both been linked to the patterns of stress change caused by eccentricity and obliquity [2J[3]. In fact, as Europa's obliquity has not been directly measured, observed tectonic patterns arc currently the best indicators of a theoretically supported [4] non-negligible obliquity. The diurnal tidal stress due to eccentricity is calculated by subtracting the average (or static) tidal shape of Europa generated by Jupiter's gravitational field from the instantaneous shape, which varies as Europa moves through its eccentric orbit [5]. In other words, it is the change of shape away from average that generates tidal stress. One might expect tidal contributions from the other large moons of Jupiter to be negligible given their size and the height of the tides they raise on Europa versus Jupiter's mass and the height of the tide it raises on Europa, However, what matters for tidally-induced stress is not how large the lo-raised bulge is compared to the Jupiter-raised bulge but rather the differences bet\\Veen the instantaneous and static bulges in each case. For example, when Europa is at apocenter, Jupiter raises a tide 30m lower than its static tide. At the same time, 10 raises a tide about 0.5m higher than its static tide. Hence, the change in Io's tidal distortion is about 2% of the change in the Jovian distortion when Europa is at apocenter

  12. Experimental investigation of localized stress-induced leakage current distribution in gate dielectrics using array test circuit

    Science.gov (United States)

    Park, Hyeonwoo; Teramoto, Akinobu; Kuroda, Rihito; Suwa, Tomoyuki; Sugawa, Shigetoshi

    2018-04-01

    Localized stress-induced leakage current (SILC) has become a major problem in the reliability of flash memories. To reduce it, clarifying the SILC mechanism is important, and statistical measurement and analysis have to be carried out. In this study, we applied an array test circuit that can measure the SILC distribution of more than 80,000 nMOSFETs with various gate areas at a high speed (within 80 s) and a high accuracy (on the 10-17 A current order). The results clarified that the distributions of localized SILC in different gate areas follow a universal distribution assuming the same SILC defect density distribution per unit area, and the current of localized SILC defects does not scale down with the gate area. Moreover, the distribution of SILC defect density and its dependence on the oxide field for measurement (E OX-Measure) were experimentally determined for fabricated devices.

  13. Accumulation and localization of extensin protein in apoplast of pea root nodule under aluminum stress.

    Science.gov (United States)

    Sujkowska-Rybkowska, Marzena; Borucki, Wojciech

    2014-12-01

    Cell wall components such as hydroxyproline-rich glycoproteins (HRGPs, extensins) have been proposed to be involved in aluminum (Al) resistance mechanisms in plants. We have characterized the distribution of extensin in pea (Pisum sativum L.) root nodules apoplast under short (for 2 and 24h) Al stress. Monoclonal antibodie LM1 have been used to locate extensin protein epitope by immunofluorescence and immunogold labeling. The nodules were shown to respond to Al stress by thickening of plant and infection thread (IT) walls and disturbances in threads growth and bacteria endocytosis. Immunoblot results indicated the presence of a 17-kDa band specific for LM1. Irrespective of the time of Al stress, extensin content increased in root nodules. Further observation utilizing fluorescence and transmission electron microscope showed that LM1 epitope was localized in walls and intercellular spaces of nodule cortex tissues and in the infection threads matrix. Al stress in nodules appears to be associated with higher extensin accumulation in matrix of enlarged thick-walled ITs. In addition to ITs, thickened walls and intercellular spaces of nodule cortex were also associated with intense extensin accumulation. These data suggest that Al-induced extensin accumulation in plant cell walls and ITs matrix may have influence on the process of IT growth and tissue and cell colonization by Rhizobium bacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Numerical Investigation of the Influence of Water Jumping on the Local Scour beneath a Pipeline under Steady Flow

    Directory of Open Access Journals (Sweden)

    Fei Fan

    2017-08-01

    Full Text Available Rigid-lid approximation is usually used to replace the free surface in scour simulation. The influence of the rigid lid assumption on the prediction precision of scour hole in steady flow is studied in this paper. Firstly, a local scour model was constructed based on the open sources Computational Fluid Dynamics (CFD model OpenFOAM, where both the bed load and suspended load were considered. In the present model, the bed shear stress was calculated by the Newton shear stress formula, instead of the traditional calculation method with the assumption that the flow velocity in vertical direction complies with a logarithmic distribution. The Volume of Fluid (VOF method was used to capture the free surface and a moving-mesh method was used to track the change of bed surface. Then, several experiments were chosen to validate the model, and the modeling results fitted well with the measured data. Lastly, the effect of the rigid lid assumption on surface elevation, bed shear stress and the profile of the scour hole in steady flow are studied. The result shows that the surface elevation suffers a drop above the pipeline, and the difference of surface elevation between the upstream and downstream increases with decreasing dimensionless depth. Compared with the free surface condition, the bed shear stress and scour hole depth computed with the rigid lid approximation were underestimated.

  15. Surface displacements and energy release rates for constant stress drop slip zones in joined elastic quarter spaces

    Science.gov (United States)

    Rodgers, Michael J.; Wen, Shengmin; Keer, Leon M.

    2000-08-01

    A three-dimensional quasi-static model of faulting in an elastic half-space with a horizontal change of material properties (i.e., joined elastic quarter spaces) is considered. A boundary element method is used with a stress drop slip zone approach so that the fault surface relative displacements as well as the free surface displacements are approximated in elements over their respective domains. Stress intensity factors and free surface displacements are calculated for a variety of cases to show the phenomenological behavior of faulting in such a medium. These calculations showed that the behavior could be distinguished from a uniform half-space. Slip in a stiffer material increases, while slip in a softer material decreases the energy release rate and the free surface displacements. Also, the 1989 Kalapana earthquake was located on the basis of a series of forward searches using this method and leveling data. The located depth is 8 km, which is the closer to the seismically inferred depth than that determined from other models. Finally, the energy release rate, which can be used as a fracture criterion for fracture at this depth, is calculated to be 11.1×106 J m-2.

  16. Role of the plant-specific endoplasmic reticulum stress-inducible gene TIN1 in the formation of pollen surface structure in Arabidopsis thaliana

    KAUST Repository

    Iwata, Yuji; Nishino, Tsuneyo; Iwano, Megumi; Takayama, Seiji; Koizumi, Nozomu

    2012-01-01

    Accumulation of unfolded proteins in the endoplasmic reticulum (ER) of eukaryotic cells triggers the transcriptional activation of ER-resident molecular chaperones and folding enzymes to maintain cellular homeostasis. This process is known as the ER stress response or the unfolded protein response. We have identified tunicamycin induced 1 (TIN1), a plant-specific ER stress-inducible Arabidopsis thaliana gene. The TIN1 protein is localized in the ER; however, its molecular function has yet to be clarified. In this study, we performed functional analysis of TIN1 in planta. RT-PCR analysis showed that TIN1 is highly expressed in pollen. Analysis using the β-glucuronidase reporter gene demonstrated that the TIN1 promoter is active throughout pollen development, peaking at the time of flowering and in an ovule of an open flower. Although a T-DNA insertion mutant of TIN1 grows normally under ambient laboratory conditions, abnormal pollen surface morphology was observed under a scanning electron microscope. Based on the current and previous observations, a possible physiological function of TIN1 during pollen development is discussed. © 2012 The Japanese Society for Plant Cell and Molecular Biology.

  17. Novel processing of Barkhausen noise signal for assessment of residual stress in surface ground components exhibiting poor magnetic response

    International Nuclear Information System (INIS)

    Vashista, M.; Paul, S.

    2011-01-01

    The Barkhausen Noise Analysis (BNA) technique has been utilised to assess surface integrity of steels. But the BNA technique is not very successful in evaluating surface integrity of ground steels that exhibit poor micro-magnetic response. A new approach has been proposed for the processing of BN signal and two newly proposed parameters, namely 'count' and 'event', have been shown to correlate linearly with the residual stress upon grinding, with judicious choice of user defined 'threshold', even when the micro-magnetic response of the work material is poor. In the present study, residual stress induced upon conventional plunge surface grinding of hardened bearing steel has been investigated along with unhardened bearing steel for benchmarking. Moreover, similar correlation has been established, when primarily compressive stress is induced upon high speed grinding using cBN wheel with moderately deep cut suppressing the micro-magnetic response from the ground medium carbon steel as the work material. - Highlights: → The problem of work materials exhibiting poor BN response and poor Barkhausen Noise response is identified. → A novel signal processing strategy is introduced to address the issue of poor micro-magnetic response of some ferromagnetic material. → Potential of newly introduced BN parameters has been studied. → These two BN parameters exhibited linear correlation with residual stress for work material with poor micro-magnetic response.

  18. Analysis of localized damage in creep rupture

    International Nuclear Information System (INIS)

    Wang Zhengdong; Wu Dongdi

    1992-01-01

    Continuum Damage Mechanics studies the effect of distributed defects, whereas the failure of engineering structures is usually caused by local damage. In this paper, an analysis of localized damage in creep rupture is carried out. The material tested is a 2 1/4Cr-1Mo pressure vessel steel and the material constants necessary for damage analysis are evaluated. Notched specimens are used to reflect localized damage in creep rupture and the amount of damage is measured using DCPD method. Through FEM computation, stress components and effective stress in the region of notch root are evaluated and it is found that the von Mises effective stress can represent the damage effective stress in the analysis of localized creep damage. It is possible to develop a method for the assessment of safety of pressure vessels under creep through localized creep damage analysis. (orig.)

  19. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y., E-mail: ykikuchi@eng.u-hyogo.ac.jp [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Nishijima, D. [Center for Energy Research, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States); Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M. [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Kawai, T.; Ueda, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Fukumoto, N. [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Doerner, R.P. [Center for Energy Research, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States)

    2011-08-01

    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of {approx}0.5 ms, incident ion energy of {approx}30 eV, and surface absorbed energy density of {approx}0.3-0.7 MJ/m{sup 2}. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of {approx}0.7 MJ/m{sup 2}, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  20. Localized Corrosion of Alloy 22 -Fabrication Effects-FY05 Summary Report

    International Nuclear Information System (INIS)

    Rebak, R B

    2005-01-01

    This report deals with the impact of fabrication processes on the localized corrosion behavior of Alloy 22 (N06022). The four fabrication processes that were analyzed are: (1) Surface stress mitigation of final closure weld, (2) Manufacturing of the mockup container, (3) Black annealing of the container and (4) Use of different heats of Alloy 22 for container fabrication. Immersion and Electrochemical tests performed in the laboratory are generally aggressive and do not represent actual repository environments in Yucca Mountain. For example, to determine the intergranular attack in the heat affected zone of a weldment, tests are conducted in boiling acidic and oxidizing solutions according to ASTM standards. These solutions are used to compare the behavior of differently treated metallic coupons. Similarly for electrochemical tests many times pure sodium chloride or calcium chloride solutions are used. Pure chloride solutions are not representative of the repository environment. (1) Surface Stress Mitigation--When metallic plates are welded, for example using the Gas Tungsten Arc Welding (GTAW) method, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to comparatively test the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results from both immersion and electrochemical corrosion tests show that the corrosion resistance of the mitigated plates was not affected by the surface treatments applied. (2) Behavior of Specimens from a Mockup container--Alloy 22 has been extensively tested for

  1. Statistics on Near Wall Structures and Shear Stress Distribution from 3D Holographic Measurement.

    Science.gov (United States)

    Sheng, J.; Malkiel, E.; Katz, J.

    2007-11-01

    Digital Holographic Microscopy performs 3D velocity measurement in the near-wall region of a turbulent boundary layer in a square channel over a smooth wall at Reτ=1,400. Resolution of ˜1μm over a sample volume of 1.5x2x1.5mm (x^+=50, y^+=60, z^+=50) is sufficient for resolving buffer layer and lower log layer structures, and for measuring instantaneous wall shear stress distributions from velocity gradients in the viscous sublayer. Results, based on 700 instantaneous realizations, provide detailed statistics on the spatial distribution of both wall stress components along with characteristic flow structures. Conditional sampling based on maxima and minima of wall shear stresses, as well as examination of instantaneous flow structures, lead to development of a conceptual model for a characteristic flow phenomenon that seems to generating extreme stress events. This structure develops as an initially spanwise vortex element rises away from the surface, due to local disturbance, causing a local stress minimum. Due to increasing velocity with elevation, this element bends downstream, forming a pair of inclined streamwise vortices, aligned at 45^0 to freestream, with ejection-like flow between them. Entrainment of high streamwise momentum on the outer sides of this vortex pair generates streamwise shear stress maxima, 70 δν downstream, which are displaced laterally by 35 δν from the local minimum.

  2. Stress induced magnetic-domain evolution in magnetoelectric composites

    Science.gov (United States)

    Trivedi, Harsh; Shvartsman, Vladimir V.; Lupascu, Doru C.; Medeiros, Marco S. A.; Pullar, Robert C.

    2018-06-01

    Local observation of the stress mediated magnetoelectric (ME) effect in composites has gained a great deal of interest over the last decades. However, there is an apparent lack of rigorous methods for a quantitative characterization of the ME effect at the local scale, especially in polycrystalline microstructures. In the present work, we address this issue by locally probing the surface magnetic state of barium titante–hexagonal barium ferrite (BaTiO3–BaFe12O19) ceramic composites using magnetic force microscopy (MFM). The effect of the piezoelectrically induced local stress on the magnetostrictive component (BaFe12O19, BaM) was observed in the form of the evolution of the magnetic domains. The local piezoelectric stress was induced by applying a voltage to the neighboring BaTiO3 grains, using a conductive atomic force microscopy tip. The resulting stochastic evolution of magnetic domains was studied in the context of the induced magnetoelastic anisotropy. In order to overcome the ambiguity in the domain changes observed by MFM, certain generalizations about the observed MFM contrast are put forward, followed by application of an algorithm for extracting the average micromagnetic changes. An average change in domain wall thickness of 50 nm was extracted, giving a lower limit on the corresponding induced magnetoelastic anisotropy energy. Furthermore, we demonstrate that this induced magnetomechanical energy is approximately equal to the K1 magnetocrystalline anisotropy constant of BaM, and compare it with a modeled value of applied elastic energy density. The comparison allowed us to judge the quality of the interfaces in the composite system, by roughly gauging the energy conversion ratio.

  3. Effect of Tip Shape of Frictional Stir Burnishing Tool on Processed Layer’s Hardness, Residual Stress and Surface Roughness

    Directory of Open Access Journals (Sweden)

    Yoshimasa Takada

    2018-01-01

    Full Text Available Friction stir burnishing (FSB is a surface-enhancement method used after machining, without the need for an additional device. The FSB process is applied on a machine that uses rotation tools (e.g., machining center or multi-tasking machine. Therefore, the FSB process can be applied immediately after the cutting process using the same machine tool. Here, we apply the FSB to the shaft materials of 0.45% C steel using a multi-tasking machine. In the FSB process, the burnishing tool rotates at a high-revolution speed. The thin surface layer is rubbed and stirred as the temperature is increased and decreased. With the FSB process, high hardness or compressive residual stress can be obtained on the surface layer. However, when we applied the FSB process using a 3 mm diameter sphere tip shape tool, the surface roughness increased substantially (Ra = 20 µm. We therefore used four types of tip shape tools to examine the effect of burnishing tool tip radius on surface roughness, hardness, residual stress in the FSB process. Results indicated that the surface roughness was lowest (Ra = 10 µm when the tip radius tool diameter was large (30 mm.

  4. STM Imaging of Localized Surface Plasmons on Individual Gold Nanoislands.

    Science.gov (United States)

    Nguyen, Huy A; Banerjee, Progna; Nguyen, Duc; Lyding, Joseph W; Gruebele, Martin; Jain, Prashant K

    2018-04-19

    An optically modulated scanning tunneling microscopy technique developed for measurement of single-molecule optical absorption is used here to image the light absorption by individual Au nanoislands and Au nanostructures. The technique is shown to spatially map, with nanometer resolution, localized surface plasmons (LSPs) excited within the nanoislands. Electrodynamic simulations demonstrate the correspondence of the measured images to plasmonic near-field intensity maps. The optical STM imaging technique captures the wavelength, polarization, and geometry dependence of the LSP resonances and their corresponding near-fields. Thus, we introduce a tool for real-space, nanometer-scale visualization of optical energy absorption, transport, and dissipation in complex plasmonic nanostructures.

  5. Variations of Sea Surface Temperature, Wind Stress, and Rainfall over the Tropical Atlantic and South America.

    Science.gov (United States)

    Nobre, Paulo; Srukla, J.

    1996-10-01

    Empirical orthogonal functions (E0Fs) and composite analyses are used to investigate the development of sea surface temperature (SST) anomaly patterns over the tropical Atlantic. The evolution of large-scale rainfall anomaly patterns over the equatorial Atlantic and South America are also investigated. 71e EOF analyses revealed that a pattern of anomalous SST and wind stress asymmetric relative to the equator is the dominant mode of interannual and longer variability over the tropical Atlantic. The most important findings of this study are as follows.Atmospheric circulation anomalies precede the development of basinwide anomalous SST patterns over the tropical Atlantic. Anomalous SST originate off the African coast simultaneously with atmospheric circulation anomalies and expand westward afterward. The time lag between wind stress relaxation (strengthening) and maximum SST warming (cooling) is about two months.Anomalous atmospheric circulation patterns over northern tropical Atlantic are phase locked to the seasonal cycle. Composite fields of SLP and wind stress over northern tropical Atlantic can be distinguished from random only within a few months preceding the March-May (MAM) season. Observational evidence is presented to show that the El Niño-Southern Oscillation phenomenon in the Pacific influences atmospheric circulation and SST anomalies over northern tropical Atlantic through atmospheric teleconnection patterns into higher latitudes of the Northern Hemisphere.The well-known droughts over northeastern Brazil (Nordeste) are a local manifestation of a much larger-scale rainfall anomaly pattern encompassing the whole equatorial Atlantic and Amazon region. Negative rainfall anomalies to the south of the equator during MAM, which is the rainy season for the Nordeste region, are related to an early withdrawal of the intertropical convergence zone toward the warm SST anomalies over the northern tropical Atlantic. Also, it is shown that precipitation anomalies

  6. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    International Nuclear Information System (INIS)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-01-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD ® BacLight ™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD ® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria. (paper)

  7. A thin rivulet or ridge subject to a uniform transverse shear stress at its free surface due to an external airflow

    KAUST Repository

    Sullivan, J. M.

    2012-01-01

    We use the lubrication approximation to analyze three closely related problems involving a thin rivulet or ridge (i.e., a two-dimensional droplet) of fluid subject to a prescribed uniform transverse shear stress at its free surface due to an external airflow, namely a rivulet draining under gravity down a vertical substrate, a rivulet driven by a longitudinal shear stress at its free surface, and a ridge on a horizontal substrate, and find qualitatively similar behaviour for all three problems. We show that, in agreement with previous numerical studies, the free surface profile of an equilibrium rivulet/ridge with pinned contact lines is skewed as the shear stress is increased from zero, and that there is a maximum value of the shear stress beyond which no solution with prescribed semi-width is possible. In practice, one or both of the contact lines will de-pin before this maximum value of the shear stress is reached, and so we consider situations in which the rivulet/ridge de-pins at one or both contact lines. In the case of de-pinning only at the advancing contact line, the rivulet/ridge is flattened and widened as the shear stress is increased from its critical value, and there is a second maximum value of the shear stress beyond which no solution with a prescribed advancing contact angle is possible. In contrast, in the case of de-pinning only at the receding contact line, the rivulet/ridge is thickened and narrowed as the shear stress is increased from its critical value, and there is a solution with a prescribed receding contact angle for all values of the shear stress. In general, in the case of de-pinning at both contact lines there is a critical "yield" value of the shear stress beyond which no equilibrium solution is possible and the rivulet/ridge will evolve unsteadily. In the Appendix, we show that an equilibrium rivulet/ridge with prescribed flux/area is quasi-statically stable to two-dimensional perturbations. © 2012 American Institute of Physics.

  8. Residual stresses in a weldment of pressure vessel steel

    International Nuclear Information System (INIS)

    Gott, K.E.

    1978-01-01

    A study was made of the distribution of residual stresses around a typical weld from a light water reactor pressure vessel by an X-ray double-exposure camera technique. So that the magnitude, sign, and distribution of the residual stresses were as similar as possible to those found in practice, a wide, full-thickness specimen of A533B Cl 1 steel containing a submerged-arc weld was stress-relief annealed. To obtain a three-dimensional distribution of the stresses the specimen was examined at different levels through the thickness. Following the removal of material by milling, the specimen surface was electropolished to free it from cold work. Corrections have been made to take into account specimen relaxation. To completely define the original stress system it is desirable also to measure the change in curvature on removing a layer of material. Unless this is done assumptions must be made which complicate the calculations unnecessarily. This became apparent after the experimental work was completed. In the centre of the plate the methods of correction which can be used are sensitive to errors in the measurements. The corrected results show that the dominant residual stress is perpendicular to the weld. It is positive at the surfaces and negative in the centre of the plate. The maximum value can reach the yield stress. The residual stresses in the weld metal can locally vary considerably: from 100 to 350N/mm 2 over a distance of 5mm. Such large variations have been found to coincide with the heat-affected zones of the individual weld runs. (author)

  9. Thermal Stress FE Analysis of Large-scale Gas Holder Under Sunshine Temperature Field

    Science.gov (United States)

    Li, Jingyu; Yang, Ranxia; Wang, Hehui

    2018-03-01

    The temperature field and thermal stress of Man type gas holder is simulated by using the theory of sunshine temperature field based on ASHRAE clear-sky model and the finite element method. The distribution of surface temperature and thermal stress of gas holder under the given sunshine condition is obtained. The results show that the thermal stress caused by sunshine can be identified as one of the important factors for the failure of local cracked oil leakage which happens on the sunny side before on the shady side. Therefore, it is of great importance to consider the sunshine thermal load in the stress analysis, design and operation of large-scale steel structures such as the gas holder.

  10. Localized surface plasmon resonances in gold nano-patches on a gallium nitride substrate

    International Nuclear Information System (INIS)

    D’Antonio, Palma; Vincenzo Inchingolo, Alessio; Perna, Giuseppe; Capozzi, Vito; Stomeo, Tiziana; De Vittorio, Massimo; Magno, Giovanni; Grande, Marco; Petruzzelli, Vincenzo; D’Orazio, Antonella

    2012-01-01

    In this paper we describe the design, fabrication and characterization of gold nano-patches, deposited on gallium nitride substrate, acting as optical nanoantennas able to efficiently localize the electric field at the metal–dielectric interface. We analyse the performance of the proposed device, evaluating the transmission and the electric field localization by means of a three-dimensional finite difference time domain (FDTD) method. We detail the fabrication protocol and show the morphological characterization. We also investigate the near-field optical t