WorldWideScience

Sample records for subcritical stress states

  1. LAVENDER: A steady-state core analysis code for design studies of accelerator driven subcritical reactors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengcheng; Wu, Hongchun; Cao, Liangzhi; Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn; Huang, Kai; He, Mingtao; Li, Xunzhao

    2014-10-15

    Highlights: • A new code system for design studies of accelerator driven subcritical reactors (ADSRs) is developed. • S{sub N} transport solver in triangular-z meshes, fine deletion analysis and multi-channel thermal-hydraulics analysis are coupled in the code. • Numerical results indicate that the code is reliable and efficient for design studies of ADSRs. - Abstract: Accelerator driven subcritical reactors (ADSRs) have been proposed and widely investigated for the transmutation of transuranics (TRUs). ADSRs have several special characteristics, such as the subcritical core driven by spallation neutrons, anisotropic neutron flux distribution and complex geometry etc. These bring up requirements for development or extension of analysis codes to perform design studies. A code system named LAVENDER has been developed in this paper. It couples the modules for spallation target simulation and subcritical core analysis. The neutron transport-depletion calculation scheme is used based on the homogenized cross section from assembly calculations. A three-dimensional S{sub N} nodal transport code based on triangular-z meshes is employed and a multi-channel thermal-hydraulics analysis model is integrated. In the depletion calculation, the evolution of isotopic composition in the core is evaluated using the transmutation trajectory analysis algorithm (TTA) and fine depletion chains. The new code is verified by several benchmarks and code-to-code comparisons. Numerical results indicate that LAVENDER is reliable and efficient to be applied for the steady-state analysis and reactor core design of ADSRs.

  2. Vacuum ultraviolet spectroscopy of the lowest-lying electronic state in subcritical and supercritical water.

    Science.gov (United States)

    Marin, Timothy W; Janik, Ireneusz; Bartels, David M; Chipman, Daniel M

    2017-05-17

    The nature and extent of hydrogen bonding in water has been scrutinized for decades, including how it manifests in optical properties. Here we report vacuum ultraviolet absorption spectra for the lowest-lying electronic state of subcritical and supercritical water. For subcritical water, the spectrum redshifts considerably with increasing temperature, demonstrating the gradual breakdown of the hydrogen-bond network. Tuning the density at 381 °C gives insight into the extent of hydrogen bonding in supercritical water. The known gas-phase spectrum, including its vibronic structure, is duplicated in the low-density limit. With increasing density, the spectrum blueshifts and the vibronic structure is quenched as the water monomer becomes electronically perturbed. Fits to the supercritical water spectra demonstrate consistency with dimer/trimer fractions calculated from the water virial equation of state and equilibrium constants. Using the known water dimer interaction potential, we estimate the critical distance between molecules (ca. 4.5 Å) needed to explain the vibronic structure quenching.

  3. Geochemical controls on the kinetics of quartz fracture at subcritical tensile stresses

    Science.gov (United States)

    Dove, Patricia M.

    1995-11-01

    A new kinetic model links physical and chemical controls on the subcritical fracture kinetics of quartz from the assumption that molecular level reactions governing fracture and dissolution proceed by similar pathways. The model formulation combines fracture theory with a mechanistically based description of chemical, thermal, and tensile stress effects on reactivity in aqueous environments. Water, as a vapor or liquid, promotes rupture of Si-O bonds by end-member processes: (1) reaction of a protonated surface with molecular water and (2) reaction of hydroxyl ions at an ionized surface. In humid environments, reaction frequency is determined by water accessibility to the crack tip. In wetted environments, the relative contributions of these mechanisms are determined by bulk solution composition which affects surface ionization and sol vent-surf ace interactions. The macroscopic fracture rate law is given in meters per second by the fractional sum of these end-member reaction mechanisms per a first-order equation. Agreement of this empirical rate expression with reported measurements of quartz fracture rates suggests the model is robust. It gives a good fit to fracture rates over 6 orders of magnitude and explains increasing rates with increasing solution pH, the dependence of rate upon crystallographic direction, and thermal dependence of rate over 20° to 80°C. Findings in this study suggest that (1) fracture models based upon changes in surface free energy with solution composition are macroscopic descriptions of solvent-surface interactions and parallel the mechanistic model presented here; (2) faster fracture rates observed in basic solutions are not facilitated by decreases in the activation barrier but are due to a transition in the solvent-surface reaction to give a higher reaction frequency and (3) power law expressions applied to fracture rate versus stress intensity measurements may not have direct mechanistic significance since log-linear relations

  4. Mechanisms of Subcritical Cracking in Calcite

    Science.gov (United States)

    Royne, A.; Dysthe, D. K.; Bisschop, J.

    2008-12-01

    Brittle materials are characterized by a critical stress intensity factor above which they will fail catastrophically by dynamic cracking. However, it has been observed that materials can also fail at much lower stresses, through slow crack growth, often referred to as subcritical cracking. This phenomenon can take place even in vacuum, but is greatly enhanced by water and other reactive species in the environment. For a given material and environmental condition there is a systematic relationship between the crack tip velocity and the stress intensity factor. The presence of a lower stress limit to subcritical cracking has been predicted from thermodynamics but has not been firmly demonstrated experimentally. This parameter would control the long- term strength of geological materials. Subcritical cracking must necessarily be important in controlling the rock strength in near-surface processes where water and other active species are present and the displacements and stresses are low. Weathering is one example of such a process. Modelling has shown that fracture networks generated by a high degree of subcritical cracking will percolate at much lower fracture densities than purely stochastical fracture networks. This has important implications for how water can move through the crust. Understanding the mechanisms for subcritical crack growth in geological materials is also important in assessing the stability and long term performance of sequestration reservoirs for CO2 or nuclear waste. The mechanism for stress corrosion is well known for glasses and quartz. For carbonate minerals, the mechanism for subcritical crack growth has not been identified, and the only experimental studies on calcitic materials have been on polycrystalline rocks such as marble. Suggested mechanisms include stress corrosion (weakening reactions at the crack tip), preferential dissolution at the crack tip with rapid removal of dissolved species, and environmentally controlled

  5. Source-jerk method for application on ADS neutronics study The ADS is stated for Accelerator Driven sub-critical System

    CERN Document Server

    Zhu Qing Fu; Li Yi; Xia Pu; Zheng Wu Qing; Zhu Guo Sheng

    2003-01-01

    The paper is concerned in the source-jerk method used to measure the sub-criticality, and the sub-critical experiment facility, which is used for the study on the neutronics of ADS, driven by external neutron source sup 2 sup 5 sup 2 Cf. The effects of the location of neutron source and material buffer where is at the location of the pipe of proton beam and target of fission-product dispersion on the sub-criticality of reactor are studied by source-jerk method

  6. Subcritical multiplication determination studies

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P.; Goulding, C.A.

    1995-07-01

    A series of measurements and improvements to computational techniques are in progress at Los Alamos National Laboratory that are aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the apparent multiplication of the system. Such studies are being performed in order to improve the special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, etc. Improved techniques and understanding are needed since measured multiplication is not always an invariant characteristic of a subcritical system, especially if one has a system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a non-normal mode system).

  7. Quantum Subcritical Bubbles

    Science.gov (United States)

    Uesugi, T.; Morikawa, M.; Shiromizu, T.

    1996-08-01

    We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using a quantum statistical average. Furthermore, based on our study, we discuss implications for the dynamics of phase transitions.

  8. Dynamics of Subcritical Bubbles in First Order Phase Transition

    Science.gov (United States)

    Shiromizu, T.; Morikawa, M.; Yokoyama, J.

    1995-11-01

    We derivate the Langevin and the Fokker-Planck equations for the radius of O(3)-symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect of thermal noise on subcritical bubbles is examined. We find that the fluctuation-dissipation relation holds and that in the high temperature phase the system settles down rapidly to the thermal equilibrium state even if it was in a nonequilibrium state initially. We then estimate the typical size of subcritical bubbles as well as the amplitude of fluctuations on that scale. We also discuss their implication to the electroweak phase transition.

  9. Subcritical nuclear assembly

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    A Subcritical Nuclear Assembly is a device where the nuclear-fission chain reaction is initiated and maintained using an external neutron source. It is a valuable educational and research tool where in a safe way many reactor parameters can be measured. Here, we have used the Wigner-Seitz method in the six-factor formula to calculate the effective multiplication factor of a subcritical nuclear reactor Nuclear Chicago model 9000. This reactor has approximately 2500 kg of natural uranium heterogeneously distributed in slugs. The reactor uses a {sup 239}PuBe neutron source that is located in the center of an hexagonal array. Using Monte Carlo methods, with the MCNP5 code, a three-dimensional model of the subcritical reactor was designed to estimate the effective multiplication factor, the neutron spectra, the total and thermal neutron fluences along the radial and axial axis. With the neutron spectra in two locations outside the reactor the ambient dose equivalent were estimated. (Author)

  10. Subcritical neutron production using multiple accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, W.Y.; Jones, J.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Harmon, J.F. [Idaho State Univ., Pocatello, ID (United States)

    1994-12-31

    A subcritical neutron production technique using multiple accelerators is being developed to provide a selective alternative (for small volumes) to nuclear reactor neutron production. The concept combines the capabilities of multiple commercially-available linear accelerators and a compact subcritical assembly design to generate reactor-like thermal neutron fluxes (i.e., 10{sup 13}-10{sup 14} n/cm{sup 2}/s) in small irradiation volumes of up to 500 cm{sup 3}. In addition, fast and epithermal neutron fluxes will also be available. The neutron source utilizes radially-oriented, pulsed, electron accelerators. The subcritical neutron production assembly is in the form of a compact right-cylinder (approximately 20-cm dia.). This assembly uses an outer ring of graphite (i.e., reflector) with re-entrant holes to enable penetration of the electron beam to the internal structure which comprises of uranium as an electron convertor/neutron multiplier followed by H{sub 2}O beryllium, H{sub 2}O aluminum, and D{sub 2}O in succession toward the center. The inner-most region filled with D{sub 2}O is the central irradiation volume. The material configuration and overall design is to maximize thermal neutron fluxes in the central irradiation volume based on photoneutron/photofission and neutron multiplication processes as well as neutron transport. This assembly will be designed not to reach a nuclear critical state under any normal and/or accidental condition.

  11. Accelerator driven sub-critical core

    Science.gov (United States)

    McIntyre, Peter M; Sattarov, Akhdiyor

    2015-03-17

    Systems and methods for operating an accelerator driven sub-critical core. In one embodiment, a fission power generator includes a sub-critical core and a plurality of proton beam generators. Each of the proton beam generators is configured to concurrently provide a proton beam into a different area of the sub-critical core. Each proton beam scatters neutrons within the sub-critical core. The plurality of proton beam generators provides aggregate power to the sub-critical core, via the proton beams, to scatter neutrons sufficient to initiate fission in the sub-critical core.

  12. Subcritical water as reaction environment: fundamentals of hydrothermal biomass transformation.

    Science.gov (United States)

    Möller, Maria; Nilges, Peter; Harnisch, Falk; Schröder, Uwe

    2011-05-23

    Subcritical water, that is, water above the boiling and below critical point, is a unique and sustainable reaction medium. Based on its solvent properties, in combination with the often considerable intrinsic water content of natural biomass, it is often considered as a potential solvent for biomass processing. Current knowledge on biomass transformation in subcritical water is, however, still rather scattered without providing a consistent picture. Concentrating on fundamental physical and chemical aspects, this review summarizes the current state of knowledge of hydrothermal biomass conversion in subcritical water. After briefly introducing subcritical water as a reaction medium, its advantages for biomass processing compared to other thermal processes are highlighted. Subsequently, the physical-chemical properties of subcritical water are discussed in the light of their impact on the occurring chemical reactions. The influence of major operational parameters, including temperature, pressure, and reactant concentration on hydrothermal biomass transformation processes are illustrated for selected carbohydrates. Major emphasis is put on the nature of the carbohydrate monomers, since the conversion of the respective polymers is analogous with the additional prior step of hydrolytic depolymerization. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Subcritical Thermal Convection of Liquid Metals in a Rapidly Rotating Sphere

    Science.gov (United States)

    Kaplan, E. J.; Schaeffer, N.; Vidal, J.; Cardin, P.

    2017-09-01

    Planetary cores consist of liquid metals (low Prandtl number Pr) that convect as the core cools. Here, we study nonlinear convection in a rotating (low Ekman number Ek) planetary core using a fully 3D direct numerical simulation. Near the critical thermal forcing (Rayleigh number Ra), convection onsets as thermal Rossby waves, but as Ra increases, this state is superseded by one dominated by advection. At moderate rotation, these states (here called the weak branch and strong branch, respectively) are smoothly connected. As the planetary core rotates faster, the smooth transition is replaced by hysteresis cycles and subcriticality until the weak branch disappears entirely and the strong branch onsets in a turbulent state at Ek <10-6. Here, the strong branch persists even as the thermal forcing drops well below the linear onset of convection (Ra =0.7 Racrit in this study). We highlight the importance of the Reynolds stress, which is required for convection to subsist below the linear onset. In addition, the Péclet number is consistently above 10 in the strong branch. We further note the presence of a strong zonal flow that is nonetheless unimportant to the convective state. Our study suggests that, in the asymptotic regime of rapid rotation relevant for planetary interiors, thermal convection of liquid metals in a sphere onsets through a subcritical bifurcation.

  14. Stress Impact on Resting State Brain Networks.

    Science.gov (United States)

    Soares, José Miguel; Sampaio, Adriana; Ferreira, Luís Miguel; Santos, Nadine Correia; Marques, Paulo; Marques, Fernanda; Palha, Joana Almeida; Cerqueira, João José; Sousa, Nuno

    2013-01-01

    Resting state brain networks (RSNs) are spatially distributed large-scale networks, evidenced by resting state functional magnetic resonance imaging (fMRI) studies. Importantly, RSNs are implicated in several relevant brain functions and present abnormal functional patterns in many neuropsychiatric disorders, for which stress exposure is an established risk factor. Yet, so far, little is known about the effect of stress in the architecture of RSNs, both in resting state conditions or during shift to task performance. Herein we assessed the architecture of the RSNs using functional magnetic resonance imaging (fMRI) in a cohort of participants exposed to prolonged stress (participants that had just finished their long period of preparation for the medical residence selection exam), and respective gender- and age-matched controls (medical students under normal academic activities). Analysis focused on the pattern of activity in resting state conditions and after deactivation. A volumetric estimation of the RSNs was also performed. Data shows that stressed participants displayed greater activation of the default mode (DMN), dorsal attention (DAN), ventral attention (VAN), sensorimotor (SMN), and primary visual (VN) networks than controls. Importantly, stressed participants also evidenced impairments in the deactivation of resting state-networks when compared to controls. These functional changes are paralleled by a constriction of the DMN that is in line with the pattern of brain atrophy observed after stress exposure. These results reveal that stress impacts on activation-deactivation pattern of RSNs, a finding that may underlie stress-induced changes in several dimensions of brain activity.

  15. Stress Impact on Resting State Brain Networks.

    Directory of Open Access Journals (Sweden)

    José Miguel Soares

    Full Text Available Resting state brain networks (RSNs are spatially distributed large-scale networks, evidenced by resting state functional magnetic resonance imaging (fMRI studies. Importantly, RSNs are implicated in several relevant brain functions and present abnormal functional patterns in many neuropsychiatric disorders, for which stress exposure is an established risk factor. Yet, so far, little is known about the effect of stress in the architecture of RSNs, both in resting state conditions or during shift to task performance. Herein we assessed the architecture of the RSNs using functional magnetic resonance imaging (fMRI in a cohort of participants exposed to prolonged stress (participants that had just finished their long period of preparation for the medical residence selection exam, and respective gender- and age-matched controls (medical students under normal academic activities. Analysis focused on the pattern of activity in resting state conditions and after deactivation. A volumetric estimation of the RSNs was also performed. Data shows that stressed participants displayed greater activation of the default mode (DMN, dorsal attention (DAN, ventral attention (VAN, sensorimotor (SMN, and primary visual (VN networks than controls. Importantly, stressed participants also evidenced impairments in the deactivation of resting state-networks when compared to controls. These functional changes are paralleled by a constriction of the DMN that is in line with the pattern of brain atrophy observed after stress exposure. These results reveal that stress impacts on activation-deactivation pattern of RSNs, a finding that may underlie stress-induced changes in several dimensions of brain activity.

  16. Subcritical flutter in the acoustics of friction

    National Research Council Canada - National Science Library

    O.N Kirillov

    2008-01-01

    ...-simple eigenfrequencies at the nodes. At contact with friction pads, the rotating continua, such as the singing wine glass or the squealing disc brake, start to vibrate owing to the subcritical flutter instability...

  17. Stress Exposure, Food Intake, and Emotional State

    Science.gov (United States)

    Ulrich-Lai, Yvonne M.; Fulton, Stephanie; Wilson, Mark; Petrovich, Gorica; Rinaman, Linda

    2016-01-01

    This manuscript summarizes the proceedings of the symposium entitled, “Stress, Palatable Food and Reward”, that was chaired by Drs. Linda Rinaman and Yvonne Ulrich-Lai at the 2014 Neurobiology of Stress Workshop held in Cincinnati, OH. This symposium comprised research presentations by four neuroscientists whose work focuses on the biological bases for complex interactions among stress, food intake and emotion. First, Dr. Ulrich-Lai describes her rodent research exploring mechanisms by which the rewarding properties of sweet palatable foods confer stress relief. Second, Dr. Stephanie Fulton discusses her work in which excessive, long-term intake of dietary lipids, as well as their subsequent withdrawal, promotes stress-related outcomes in mice. Third, Dr. Mark Wilson describes his group’s research examining the effects of social hierarchy-related stress on food intake and diet choice in group-housed female rhesus macaques, and compared the data from monkeys to results obtained in analogous work using rodents. Lastly, Dr. Gorica Petrovich discusses her research program that is aimed at defining cortical–amygdalar–hypothalamic circuitry responsible for curbing food intake during emotional threat (i.e., fear anticipation) in rats. Their collective results reveal the complexity of physiological and behavioral interactions that link stress, food intake and emotional state, and suggest new avenues of research to probe the impact of genetic, metabolic, social, experiential, and environmental factors. PMID:26303312

  18. Stress exposure, food intake and emotional state.

    Science.gov (United States)

    Ulrich-Lai, Yvonne M; Fulton, Stephanie; Wilson, Mark; Petrovich, Gorica; Rinaman, Linda

    2015-01-01

    This manuscript summarizes the proceedings of the symposium entitled, "Stress, Palatable Food and Reward", that was chaired by Drs. Linda Rinaman and Yvonne Ulrich-Lai at the 2014 Neurobiology of Stress Workshop held in Cincinnati, OH. This symposium comprised research presentations by four neuroscientists whose work focuses on the biological bases for complex interactions among stress, food intake and emotion. First, Dr Ulrich-Lai describes her rodent research exploring mechanisms by which the rewarding properties of sweet palatable foods confer stress relief. Second, Dr Stephanie Fulton discusses her work in which excessive, long-term intake of dietary lipids, as well as their subsequent withdrawal, promotes stress-related outcomes in mice. Third, Dr Mark Wilson describes his group's research examining the effects of social hierarchy-related stress on food intake and diet choice in group-housed female rhesus macaques, and compared the data from monkeys to results obtained in analogous work using rodents. Finally, Dr Gorica Petrovich discusses her research program that is aimed at defining cortical-amygdalar-hypothalamic circuitry responsible for curbing food intake during emotional threat (i.e. fear anticipation) in rats. Their collective results reveal the complexity of physiological and behavioral interactions that link stress, food intake and emotional state, and suggest new avenues of research to probe the impact of genetic, metabolic, social, experiential and environmental factors on these interactions.

  19. Subcritical Noise Analysis Measurements with Fresh and Spent Research Reactor Fuels Elements

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, T.E.; Mihalczo, J.T.; Kryter, R.C.; Miller, V.C.

    1999-02-01

    The verification of the subcriticality is of utmost importance for the safe transportation and storage of nuclear reactor fuels. Transportation containers and storage facilities are designed such that nuclear fuels remain in a subcritical state. Such designs often involve excess conservatism because of the lack of relevant experimental data to verify the accuracy of Monte Carlo codes used in nuclear criticality safety analyses. A joint experimental research program between Oak Ridge National Laboratory, Westinghouse Safety Management Solutions, Inc., and the University of Missouri was initiated to obtain measured quantities that could be directly related to the subcriticality of simple arrays of Missouri University Research Reactor (MURR) fuel elements. A series of measurement were performed to assess the reactivity of materials such as BORAL, stainless steel, aluminum, and lead that are typically used in the construction of shipping casks. These materials were positioned between the fuel elements. In addition, a limited number of measurements were performed with configurations of fresh and spent (irradiated) fuel elements to ascertain the reactivity of the spent fuel elements. In these experiments, fresh fuel elements were replaced by spent fuel elements such that the subcritical reactivity change could be measured. The results of these measurements were used by Westinghouse Safety Management Solutions to determine the subcriticality of MURR fuel elements isolated by absorbing materials. The measurements were interpreted using the MCNP-DSP Monte Carlo code to obtain the subcritical neutron multiplication factor k(sub eff), and the bias in K(sub eff) that are used in criticality safety analyses.

  20. Numerical simulations of subcritical reactor kinetics in thermal hydraulic transient phases

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, J.; Park, W. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A subcritical reactor driven by a linear proton accelerator has been considered as a nuclear waste incinerator at Korea Atomic Energy Research Institute (KAERI). Since the multiplication factor of a subcritical reactor is less than unity, to compensate exponentially decreasing fission neutrons, external neutrons form spallation reactions are essentially required for operating the reactor in its steady state. Furthermore, the profile of accelerator beam currents is very important in controlling a subcritical reactor, because the reactor power varies in accordance to the profile of external neutrons. We have developed a code system to find numerical solutions of reactor kinetics equations, which are the simplest dynamic model for controlling reactors. In a due course of our previous numerical study of point kinetics equations for critical reactors, however, we learned that the same code system can be used in studying dynamic behavior of the subcritical reactor. Our major motivation of this paper is to investigate responses of subcritical reactors for small changes in thermal hydraulic parameters. Building a thermal hydraulic model for the subcritical reactor dynamics, we performed numerical simulations for dynamic responses of the reactor based on point kinetics equations with a source term. Linearizing a set of coupled differential equations for reactor responses, we focus our research interest on dynamic responses of the reactor to variations of the thermal hydraulic parameters in transient phases. 5 refs., 8 figs. (Author)

  1. PILOT-SCALE SUBCRITICAL WATER REMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON- AND PESTICIDE-CONTAMINATED SOIL. (R825394)

    Science.gov (United States)

    Subcritical water (hot water under enough pressure to maintain the liquid state) was used to remove polycyclic aromatic hydrocarbons (PAHs) and pesticides from highly contaminated soils. Laboratory-scale (8 g of soil) experiments were used to determine conditions f...

  2. Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

    Science.gov (United States)

    Mukuhira, Yusuke; Moriya, Hirokazu; Ito, Takatoshi; Asanuma, Hiroshi; Häring, Markus

    2017-04-01

    Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

  3. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    Keywords. Accelerator driven systems; nuclear waste transmutation; computer codes; reactor physics; reactor noise; kinetics; burnup; transport theory; Monte Carlo; thorium utilization; neutron multiplication; sub-criticality; sub-critical facilities.

  4. Modeling of Parameters of Subcritical Assembly SAD

    CERN Document Server

    Petrochenkov, S; Puzynin, I

    2005-01-01

    The accepted conceptual design of the experimental Subcritical Assembly in Dubna (SAD) is based on the MOX core with a nominal unit capacity of 25 kW (thermal). This corresponds to the multiplication coefficient $k_{\\rm eff} =0.95$ and accelerator beam power 1 kW. A subcritical assembly driven with the existing 660 MeV proton accelerator at the Joint Institute for Nuclear Research has been modelled in order to make choice of the optimal parameters for the future experiments. The Monte Carlo method was used to simulate neutron spectra, energy deposition and doses calculations. Some of the calculation results are presented in the paper.

  5. The effects of perceived stress, traits, mood states, and stressful daily events on salivary cortisol

    NARCIS (Netherlands)

    vanEck, M; Berkhof, H; Nicolson, N; Sulon, J

    1996-01-01

    This study examined the effects of perceived stress and related individual characteristics, mood states, and stressful daily events on salivary cortisol levels. Forty-one ''high stress'' and 46 ''low stress'' subjects were selected on the basis of Perceived Stress Scale scores from a sample of male,

  6. Subcritical tests - nuclear weapon testing under the Comprehensive Test Ban Treaty; Subkritiske tester - kjernevaapentesting under avtalen om fullstendig proevestans

    Energy Technology Data Exchange (ETDEWEB)

    Hoeibraaten, S

    1998-10-01

    The report discusses possible nuclear weapons related experiments and whether these are permitted under the 1996 Comprehensive Test Ban Treaty (CTBT). The term ''subcritical experiments'' as used in the United States includes experiments in which one studies fissile materials (so far only plutonium) under extreme conditions generated by conventional high explosives, and in which a self-sustained chain reaction never develops in the fissile material. The known facts about the American subcritical experiments are presented. There is very little reason to doubt that these experiments were indeed subcritical and therefore permitted under the CTBT. Little is known about the Russian efforts that are being made on subcritical experiments.

  7. Subcritical localization in the discrete nonlinear Schrödinger equation with arbitrary power nonlinearity

    DEFF Research Database (Denmark)

    Bang, O.; Juul Rasmussen, J.; Christiansen, P.L.

    1994-01-01

    Discretizing the continuous nonlinear Schrodinger equation with arbitrary power nonlinearity influences the time evolution of its ground state solitary solution. In the subcritical case, for grid resolutions above a certain transition value, depending on the degree of nonlinearity, the solution w...

  8. Subcritical water extractor for Mars analog soil analysis.

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank J; Patrick, Steven B; Yung, Pun To

    2008-06-01

    Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).

  9. MCNP multiplication analysis of subcritical HEU experiments

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P. [Los Alamos National Lab., NM (United States); Brockhoff, R.C. [Kansas State Univ., Manhattan, KS (United States)

    1998-12-31

    A series of measurements and improvements to computational techniques was described in Ref. 1 that were aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the multiplying characteristics of the system. This methodology has been applied to a number of the bare highly enriched uranium (HEU) measurements (simulating 0.5- to 21.5-kg balls with nesting shells) of Ref. 2, demonstrating that the experimental multiplication results can be reproduced computationally with good accuracy. This capability promises to improve special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, smuggling of SNM, etc. Improved techniques and understanding are needed since traditionally measured or calculated multiplications are not always an invariant characteristic of a subcritical system, especially if one has an SNM system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a nonnormal mode system). The measurement techniques used in Refs. 1 and 2 to determine multiplication are based on the Feynman variance-to-mean method, which has been previously documented in Refs. 3 and 4 and applied successfully to normal mode systems such as plutonium and uranium spheres. These techniques have been applied to nonnormal mode problems with less success, and both Refs. 1 and 2 as well as the current paper are attempts to better understand the subcritical multiplication of such systems.

  10. Monte Carlo simulation of a perturbed subcritical core

    Energy Technology Data Exchange (ETDEWEB)

    Jaradat, Mustafa K.; Park, Chang Je [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Jordan Subcritical Assembly (JSA) is designed for the purpose of education, training, and experiment research. Jordan subcritical assembly is considered Jordan's First Nuclear Facility Moving Jordan into the nuclear age. It is a teaching and training experimental facility that is designed to stay in a subcriticality A subcritical assembly is a multiplying system of nuclear fuel and moderator whose effective multiplication factor is less than unity. An extraneous source of neutron is required for the operation in order to compensate for the difference between the production rate of fission neutrons in the fuel and the rate of loss caused by absorption and leakage.

  11. Subcritical water extraction of lipids from wet algal biomass

    Science.gov (United States)

    Deng, Shuguang; Reddy, Harvind K.; Schaub, Tanner; Holguin, Francisco Omar

    2016-05-03

    Methods of lipid extraction from biomass, in particular wet algae, through conventionally heated subcritical water, and microwave-assisted subcritical water. In one embodiment, fatty acid methyl esters from solids in a polar phase are further extracted to increase biofuel production.

  12. Production of value added materials by subcritical water hydrolysis ...

    African Journals Online (AJOL)

    The aim of this study was the determination of the best experimental conditions for the production of useful materials such as amino acids by subcritical water hydrolysis from supercritical carbon dioxide extracted krill residues and to compare the results with raw krill. Subcritical water hydrolysis efficiency from raw and ...

  13. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    utilization; neutron multiplication; sub-criticality; sub-critical facilities. PACS Nos 89.30.Gg; 28.41.-I; 28.50.-k. 1. Introduction. Accelerator driven systems (ADS) are attracting worldwide attention increasingly due to their superior safety characteristics and their potential for burning actinide and fission product-waste and energy ...

  14. Subcritical water extraction of bioactive compounds from dry loquat ...

    African Journals Online (AJOL)

    ERASTO

    concentrated in a rotary evaporator at 60°C until dry. The total extraction yield was obtained by the mean value of the total extracts divided by the mass of dry loquat leaves used. Subcritical water extraction. Subcritical water extraction was carried using an extractor. (Hangzhou Huali Co. Ltd, Hangzhou, China). The extractor ...

  15. Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes; Zhang, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Criticality Safety Division

    2016-09-27

    Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM_Solver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) “Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.”). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the keff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

  16. Modeling of the stress state of the thumb carpometacarpal joint

    Science.gov (United States)

    Anferov, G. M.; Goryacheva, I. G.; Lyubicheva, A. N.; Soldatenkov, I. A.; Su, Fong-Chin; Chang, Chih-Han

    2013-07-01

    The stress state of the carpometacarpal joint (CMJ)was studied in sound and pathologic states by methods of continuum mechanics. The CMJ geometric model was constructed according to the results of computer processing of the data of tomographic investigations in the extension position, which were obtained at Cheng Kung Medical University (Taiwan). The study of contact interactions in the CML region for a given geometry were performed numerically in the ABAQUS program code. The obtained numerical solutions of contact problems permit comparatively analyzing the stress distribution in the bone tissue for various thumb positions and study the stress state dependence on the bone tissue porosity (osteoporosis), which varies with human age.

  17. Study in stationary state of the subcriticality of intermediate configurations of core in the reloading process of a BWR; Estudio en estado estacionario de la subcriticidad de configuraciones intermedias de nucleo en el proceso de recarga de un BWR

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, J.L.; Montes, J.L.; Perusquia, R.; Ortiz, J.J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: jlhm@nuclear.inin.mx

    2006-07-01

    In this work is carried out the simulation in three dimensions with the COREMASTER-PRESTO code, of the behavior of the reactor core in different stages of the change process of fuel assemblies. To carry out the simulation, this code requires of a database of nuclear parameters that includes those that can associate to the areas of an assemblies that they don't contain fuel and in its place there is moderator. These nuclear parameters are calculated with the AURORA-HELIOS-ZENITH-TABGEN system. One of the approaches that were carried out consisted on designing a 'water assemble', that is to say, an axial arrangement of 25 'water cells'. To obtain the appropriate 'water cell' its were carried out some selective test cases, since it presents in two cases the necessity to find an enough minimum value of fissile material for the correct execution of HELIOS, firstly, and later on COREMASTER-PRESTO. In the first case, the situation is solved when placing symmetrically 6 bars with natural uranium in the lateral areas of the cell; with that which the value of k{sub inf} of 0.1592 is obtained in the calculations with the HELIOS code in the cold condition to zero power (CZP), and 0% of vacuums. For the second case the cell includes symmetrically 28 bars with natural uranium, and the k{sub inf} value is 0.45290. These values are the maximum through the life of the 'cell.' As part of the activities that are developed during the fuel substitution, this the one of evaluating the subcriticality of the core each determined number of substitution movements. The obtained results when evaluating the k-effective in cold condition, in 5 different intermediate core configurations, as the loading process of the fuel advances are presented. To make the evaluation with CM-PRESTO in each configuration it was proceeded to complete the rest of the 444 assemblies with the one denominated 'water assemble'. In all the evaluated cases the

  18. Analytical approach for resolving stress states around elliptical cavities

    OpenAIRE

    Lukić Dragan; Anagnosti Petar

    2005-01-01

    The determination of stress states around cavities in the stressed elastic body, regardless of cavity shapes, that may be spherical, cylindrical elliptical etc. in its analytical approach has to be based on selection of a stress function that will satisfy biharmonic equation, under given boundary conditions. This paper is concerned with formulation and solution of the cited differential equation using elliptical coordinates in conformity with the cavity shape of oblong ellipsoid [1]. It is th...

  19. Effects of Consolidation Stress State on Normally Consolidated Clay

    DEFF Research Database (Denmark)

    Lade, Poul V.

    2000-01-01

    The effect of consolidation stress state on the stress-strain and strength characteristics has been studied from experiments on undisturbed block samples of a natural, normally consolidated clay known as San Francisco Bay Mud. The results of experiments on K0-consolidated, hollow cylinder specimens...

  20. Design, Development and Installation of Jordan Subcritical Assembly

    OpenAIRE

    Ned Xoubi

    2013-01-01

    Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA) is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 ...

  1. Stress-state effects on the stress-induced martensitic transformation of carburized 4320 steels

    Science.gov (United States)

    Karaman, I.; Balzer, M.; Sehitoglu, Huseyin; Maier, H. J.

    1998-02-01

    The effect of different stress states on the stress-induced martensitic transformation of retained austenite was investigated in carburized 4320 steels with an initial retained austenite content of 15 pct. Experiments were conducted utilizing a specialized pressure rig and comparison between stress-strain behaviors of specimens with different austenitization and tempering histories was performed under these stress states. Experimental results indicated considerable asymmetry between tension and compression, with triaxial stress states resulting in the highest strength levels for the untempered material. Fine carbide precipitates due to low-temperature tempering increased the strength and ductility of the specimens and also changed the austenite-to-martensite transformation behavior. Numerical simulations of stress-strain behaviors under different stress states were obtained, with an existing micromechanical self-consistent framework utilizing the crystallographic theory of austenite/martensite transformation and the minimum complementary free-energy principle. The model was modified for carburized steels upon microstructural investigation and predicted the same trends in effective stress-effective strain behavior as observed experimentally.

  2. Astrobionibbler: In Situ Microfluidic Subcritical Water Extraction of Amino Acids

    Science.gov (United States)

    Noell, A. C.; Fisher, A. M.; Takano, N.; Fors-Francis, K.; Sherrit, S.; Grunthaner, F.

    2016-10-01

    A fluidic-chip based instrument for subcritical water extraction (SCWE) of amino acids and other organics from powder samples has been developed. A variety of soil analog extractions have been performed to better understand SCWE capabilities.

  3. Oxidatively generated DNA/RNA damage in psychological stress states

    DEFF Research Database (Denmark)

    Jørgensen, Anders

    2013-01-01

    age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8......-oxodG and 8-oxoGuo, respectively). The main hypothesis was that psychological stress states are associated with increased DNA/RNA damage from oxidation. In a study of 40 schizophrenia patients and 40 healthy controls matched for age and gender, we found that 8-oxodG/8-oxoGuo excretion was increased...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased...

  4. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  5. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    Directory of Open Access Journals (Sweden)

    Fang Duan

    2013-01-01

    Full Text Available The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  6. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    OpenAIRE

    Fang Duan; Yu-fen Chen; Zhong-zheng Sun; Ming-qing Chen; Hui Zhang; Jing Zhang

    2013-01-01

    The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  7. Orexin, stress, and anxiety/panic states.

    Science.gov (United States)

    Johnson, Philip L; Molosh, Andrei; Fitz, Stephanie D; Truitt, William A; Shekhar, Anantha

    2012-01-01

    A panic response is an adaptive response to deal with an imminent threat and consists of an integrated pattern of behavioral (aggression, fleeing, or freezing) and increased cardiorespiratory and endocrine responses that are highly conserved across vertebrate species. In the 1920s and 1940s, Philip Bard and Walter Hess, respectively, determined that the posterior regions of the hypothalamus are critical for a "fight-or-flight" reaction to deal with an imminent threat. Since the 1940s it was determined that the posterior hypothalamic panic area was located dorsal (perifornical hypothalamus: PeF) and dorsomedial (dorsomedial hypothalamus: DMH) to the fornix. This area is also critical for regulating circadian rhythms and in 1998, a novel wake-promoting neuropeptide called orexin (ORX)/hypocretin was discovered and determined to be almost exclusively synthesized in the DMH/PeF perifornical hypothalamus and adjacent lateral hypothalamus. The most proximally emergent role of ORX is in regulation of wakefulness through interactions with efferent systems that mediate arousal and energy homeostasis. A hypoactive ORX system is also linked to narcolepsy. However, ORX role in more complex emotional responses is emerging in more recent studies where ORX is linked to depression and anxiety states. Here, we review data that demonstrates ORX ability to mobilize a coordinated adaptive panic/defense response (anxiety, cardiorespiratory, and endocrine components), and summarize the evidence that supports a hyperactive ORX system being linked to pathological panic and anxiety states. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Plasticity of resting state brain networks in recovery from stress

    Science.gov (United States)

    Soares, José M.; Sampaio, Adriana; Marques, Paulo; Ferreira, Luís M.; Santos, Nadine C.; Marques, Fernanda; Palha, Joana A.; Cerqueira, João J.; Sousa, Nuno

    2013-01-01

    Chronic stress has been widely reported to have deleterious impact in multiple biological systems. Specifically, structural and functional remodeling of several brain regions following prolonged stress exposure have been described; importantly, some of these changes are eventually reversible. Recently, we showed the impact of stress on resting state networks (RSNs), but nothing is known about the plasticity of RSNs after recovery from stress. Herein, we examined the “plasticity” of RSNs, both at functional and structural levels, by comparing the same individuals before and after recovery from the exposure to chronic stress; results were also contrasted with a control group. Here we show that the stressed individuals after recovery displayed a decreased resting functional connectivity in the default mode network (DMN), ventral attention network (VAN), and sensorimotor network (SMN) when compared to themselves immediately after stress; however, this functional plastic recovery was only partial as when compared with the control group, as there were still areas of increased connectivity in dorsal attention network (DAN), SMN and primary visual network (VN) in participants recovered from stress. Data also shows that participants after recovery from stress displayed increased deactivations in DMN, SMN, and auditory network (AN), to levels similar to those of controls, showing a normalization of the deactivation pattern in RSNs after recovery from stress. In contrast, structural changes (volumetry) of the brain areas involving these networks are absent after the recovery period. These results reveal plastic phenomena in specific RSNs and a functional remodeling of the activation-deactivation pattern following recovery from chronic-stress, which is not accompanied by significant structural plasticity. PMID:24416009

  9. Efficient decomposition of perchlorate to chloride ions in subcritical water by use of steel slag.

    Science.gov (United States)

    Hori, Hisao; Kamijo, Ayae; Inoue, Miki; Chino, Asako; Wu, Qian; Kannan, Kurunthachalam

    2016-08-03

    Decomposition of perchlorate (ClO4(-)) in subcritical water in the presence of steel slag, a by-product of the steel industry, was investigated. Reactivity of ClO4(-) was low in pure subcritical water state up to 300 °C, whereas adding steel slag efficiently accelerated the decomposition of ClO4(-) to Cl(-), with no leaching of heavy metals such as chromium and other environmentally undesirable elements (boron and fluorine). When the reaction was performed in subcritical water at a relatively low temperature (250 °C) for 6 h, virtually all ClO4(-) ions were removed from the reaction solution. The concentration of Cl(-) after the reaction was well accounted for by the sum of the amount of Cl(-) ascribed to the decomposition of ClO4(-) and the amount of Cl(-) leached from the slag. This method was successfully applied to decompose ClO4(-) in water samples collected from a man-made reflection pond following a fireworks display, even though these samples contained much higher concentrations of Cl(-) and SO4(2-) than ClO4(-).

  10. Neutrino Physics with Accelerator Driven Subcritical Reactors

    Science.gov (United States)

    Ciuffoli, Emilio

    2017-09-01

    Accelerator Driven Subcritical System (ADS) reactors are being developed around the world, to produce energy and, at the same time, to provide an efficient way to dispose of and to recycle nuclear waste. Used nuclear fuel, by itself, cannot sustain a chain reaction; however in ADS reactors the additional neutrons which are required will be supplied by a high-intensity accelerator. This accelerator will produce, as a by-product, a large quantity of {\\bar{ν }}μ via muon Decay At Rest (µDAR). Using liquid scintillators, it will be possible to to measure the CP-violating phase δCP and to look for experimental signs of the presence of sterile neutrinos in the appearance channel, testing the LSND and MiniBooNE anomalies. Even in the first stage of the project, when the beam energy will be lower, it will be possible to produce {\\bar{ν }}e via Isotope Decay At Rest (IsoDAR), which can be used to provide competitive bounds on sterile neutrinos in the disappearance channel. I will consider several experimental setups in which the antineutrinos are created using accelerators that will be constructed as part of the China-ADS program.

  11. STRESS AND STRAIN STATE OF REPAIRING SECTION OF PIPELINE

    Directory of Open Access Journals (Sweden)

    V. V. Nikolaev

    2015-01-01

    Full Text Available Reliability of continuous operation of pipelines is an actual problem. For this reason should be developed an effective warning system of the main pipelines‘  failures and accidents not only in design and operation but also in selected repair. Changing of linear, unloaded by bending position leads to the change of stress and strain state of pipelines. And besides this, the stress and strain state should be determined and controlled in the process of carrying out the repair works. The article presents mathematical model of pipeline’s section straining in viscoelastic setting taking into account soils creep and high-speed stress state of pipeline with the purpose of stresses evaluation and load-supporting capacity of repairing section of pipeline, depending on time.  Stress and strain state analysis of pipeline includes longitudinal and circular stresses calculation  with  account of axis-asymmetrical straining and  was  fulfilled  on  the base of momentless theory of shells. To prove the consistency of data there were compared the calcu- lation results and the solution results by analytical methods for different cases (long pipeline’s section strain only under influence of cross-axis action; long pipeline’s section strain under in- fluence of longitudinal stress; long pipeline’s section strain; which is on the elastic foundation, under influence of cross-axis action. Comparison results shows that the calculation error is not more than 3 %.Analysis of stress-strain state change of pipeline’s section was carried out with development  of  this  model,  which  indicates  the  enlargement  of  span  deflection  in  comparison with problem’s solution in elastic approach. It is also proved, that for consistent assessment of pipeline maintenance conditions, it is necessary to consider the areolas of rheological processes of soils. On the base of complex analysis of pipelines there were determined stresses and time

  12. Effect of insulin pump infusion on comprehensive stress state of ...

    African Journals Online (AJOL)

    Purpose: To assess changes in the comprehensive stress state of patients with diabetic ketoacidosis. (DKA) following treatment with insulin infusion pump. Methods: A total of 240 patients suffering from DKA who received treatment at The First Affiliated. Hospital of Zhengzhou University from Feb. 2011 to Feb. 2014 were ...

  13. Effect of insulin pump infusion on comprehensive stress state of ...

    African Journals Online (AJOL)

    Purpose: To assess changes in the comprehensive stress state of patients with diabetic ketoacidosis (DKA) following treatment with insulin infusion pump. Methods: A total of 240 patients suffering from DKA who received treatment at The First Affiliated Hospital of Zhengzhou University from Feb. 2011 to Feb. 2014 were ...

  14. Effect of insulin pump infusion on comprehensive stress state of ...

    African Journals Online (AJOL)

    Purpose: To assess changes in the comprehensive stress state of patients with diabetic ketoacidosis ... diabetes [1,2]. Insulin insufficiency is the leading cause of DKA. Thus, the key to treating DKA is to correct the acidosis and hyperketonaemia induced by acute ..... children and adolescents with type 1 diabetes: a 3-year.

  15. RATING OF STRESS FACTORS IN DELTA STATE SECONDARY ...

    African Journals Online (AJOL)

    The study focused on principals and teachers' opinion on the rating of stress factors on human ... problems, teachers' interpersonal conflicts among themselves and insufficient time to perform task assigned to them. ... in the state because apart from parents, teachers are the closest to students and so, their behaviour always ...

  16. Water Stress Assessment in Jharkhand State Using Soil Data and ...

    African Journals Online (AJOL)

    Michael Horsfall

    Full-text Available Online at www.bioline.org.br/ja. Water Stress Assessment in Jharkhand ... state is facing acute water crisis and due to lowering of ground water table. Thus this work would help the administrators and ... interactive cycle, ground water is largely an invisible resource, occurring in a range of water producing.

  17. Stress state and strain rate dependence of the human placenta.

    Science.gov (United States)

    Weed, Benjamin C; Borazjani, Ali; Patnaik, Sourav S; Prabhu, R; Horstemeyer, M F; Ryan, Peter L; Franz, Thomas; Williams, Lakiesha N; Liao, Jun

    2012-10-01

    Maternal trauma (MT) in automotive collisions is a source of injury, morbidity, and mortality for both mothers and fetuses. The primary associated pathology is placental abruption in which the placenta detaches from the uterus leading to hemorrhaging and termination of pregnancy. In this study, we focused on the differences in placental tissue response to different stress states (tension, compression, and shear) and different strain rates. Human placentas were obtained (n = 11) for mechanical testing and microstructure analysis. Specimens (n = 4+) were tested in compression, tension, and shear, each at three strain rates (nine testing protocols). Microstructure analysis included scanning electron microscopy, histology, and interrupted mechanical tests to observe tissue response to various loading states. Our data showed the greatest stiffness in tension, followed by compression, and then by shear. The study concludes that mechanical behavior of human placenta tissue (i) has a strong stress state dependence and (ii) behaves in a rate dependent manner in all three stress states, which had previously only been shown in tension. Interrupted mechanical tests revealed differences in the morphological microstructure evolution that was driven by the kinematic constraints from the different loading states. Furthermore, these structure-property data can be used to develop high fidelity constitutive models for MT simulations.

  18. Stress among Secondary School Teachers in Ebonyi State, Nigeria: Suggested Interventions in the Worksite Milieu

    Science.gov (United States)

    Nwimo, Ignatius O.; Onwunaka, Chinagorom

    2015-01-01

    The aim of the study was to determine the level of stress experienced by secondary school teachers in Ebonyi State. The dimensions of stress studied included physical stress, mental stress, emotional stress and social stress. The study adopted the cross-sectional survey design using a sample of 660 (male 259, female 401) teachers randomly drawn…

  19. Concept of turbines for ultrasupercritical, supercritical, and subcritical steam conditions

    Science.gov (United States)

    Mikhailov, V. E.; Khomenok, L. A.; Pichugin, I. I.; Kovalev, I. A.; Bozhko, V. V.; Vladimirskii, O. A.; Zaitsev, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.

    2017-11-01

    The article describes the design features of condensing turbines for ultrasupercritical initial steam conditions (USSC) and large-capacity cogeneration turbines for super- and subcritical steam conditions having increased steam extractions for district heating purposes. For improving the efficiency and reliability indicators of USSC turbines, it is proposed to use forced cooling of the head high-temperature thermally stressed parts of the high- and intermediate-pressure rotors, reaction-type blades of the high-pressure cylinder (HPC) and at least the first stages of the intermediate-pressure cylinder (IPC), the double-wall HPC casing with narrow flanges of its horizontal joints, a rigid HPC rotor, an extended system of regenerative steam extractions without using extractions from the HPC flow path, and the low-pressure cylinder's inner casing moving in accordance with the IPC thermal expansions. For cogeneration turbines, it is proposed to shift the upper district heating extraction (or its significant part) to the feedwater pump turbine, which will make it possible to improve the turbine plant efficiency and arrange both district heating extractions in the IPC. In addition, in the case of using a disengaging coupling or precision conical bolts in the coupling, this solution will make it possible to disconnect the LPC in shifting the turbine to operate in the cogeneration mode. The article points out the need to intensify turbine development efforts with the use of modern methods for improving their efficiency and reliability involving, in particular, the use of relatively short 3D blades, last stages fitted with longer rotor blades, evaporation techniques for removing moisture in the last-stage diaphragm, and LPC rotor blades with radial grooves on their leading edges.

  20. Modeling of the CTEx subcritical unit using MCNPX code

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Avelino [Divisao de Defesa Quimica, Biologica e Nuclear. Centro Tecnologico do Exercito - CTEx, Guaratiba, Rio de Janeiro, RJ (Brazil); Silva, Ademir X. da, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear. Universidade Federal do Rio de Janeiro - UFRJ Centro de Tecnologia, Rio de Janeiro, RJ (Brazil); Rebello, Wilson F. [Secao de Engenharia Nuclear - SE/7 Instituto Militar de Engenharia - IME Rio de Janeiro, RJ (Brazil); Cunha, Victor L. Lassance [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The present work aims at simulating the subcritical unit of Army Technology Center (CTEx) namely ARGUS pile (subcritical uranium-graphite arrangement) by using the computational code MCNPX. Once such modeling is finished, it could be used in k-effective calculations for systems using natural uranium as fuel, for instance. ARGUS is a subcritical assembly which uses reactor-grade graphite as moderator of fission neutrons and metallic uranium fuel rods with aluminum cladding. The pile is driven by an Am-Be spontaneous neutron source. In order to achieve a higher value for k{sub eff}, a higher concentration of U235 can be proposed, provided it safely remains below one. (author)

  1. Personal determinants of positive states and stress in psychology students

    Directory of Open Access Journals (Sweden)

    G.S. Kozhukhar

    2013-07-01

    Full Text Available We report study results of personality characteristics as predictors of positive states (active, optimistic, emotional, subjective comfort and stress experience in adults with one higher education and ongoing training in Psychology. The respondents were 107 people aged 23 to 52 years. Diagnostic methods we used were: "SMIL" (L. Sobchik, Optimism and Activity Scale (adapted by E. Vodopyanova, C. Izard Differential Emotions Scale (adapted by A. Leonova, Subjective Comfort Scale (adapted by A. Leonova, PSM-25 Scale by Lemyr-Tessier-Fillion. The regression analysis revealed that in subjects ongoing training in Psychology, basic predictor of positive emotions and stress experience is anxiety. Cluster analysis revealed three types of subjects by their positive states experiences, which differ primarily by the level of baseline anxiety and related personality characteristics. The group of risk comprised Psychology students with a tendency to depression and negative emotions and specific personality profile.

  2. SESAME Equations of State for Stress Cushion and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Coe, Joshua Damon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-12

    I examine LANL equations of state (EOS) for stress cushion and related materials, namely S5370, SX358, and Sylgard 184. In the the rst two cases, the SESAME library contains entries for both the inert (unreacted) and decomposition products. I compare inert EOS results with ambient property measurements to the extent possible, then I check the compositions used to build the products tables. I plot the predicted Hugoniots alongside the available shock data, then draw some conclusions.

  3. EVALUATION OF STRESS-STRAIN STATE OF ROCK MASS

    Directory of Open Access Journals (Sweden)

    R. A. Magomedov

    2016-01-01

    Full Text Available Abstract. A new method of determining the stress-strain state of the rocks without dropping its individual parts on the basis of combination of observations of the dynamics of piezometric level in special hydrogeological wells of pre-planned network and by the change in the diameter of wells measured by photo elastic sensors is proposed.With the beginning of the formation of the stress-strain state of the geological environment, the chaotic structure of hydro-geodynamic field(HGD-field goes into the abnormal condition of a certain form, in accordance with the geometric shape and sizes of the geological structure. Closed lines of equal abnormal values of piezometric levels form geometric circular structures in the Central parts of which are observed their most anomalous values corresponding to the greatest extent of stressstrain state of rock massif. Within abnormal (disturbed HGD-field is carried out the measurement of the diameters of the wells, fixed by photoelastic sensors which clarify the concrete stress-strain plot (voltages source of the rock massif. Well drilled for measuring by photoelastic sensors of changes in their diameters, are arranged in the rock massif in a staggered manner, and the special hydrogeological well, drilled up to an isolated water system for the registration of anomalous (perturbed HGD-field are locatedin two mutually perpendicular profiles, taking into account the geometric shape of the monitored rock mass. The combination of observations according to a pre-planned network of piezometers and wells with photoelastic sensors will allow to get a more accurate picture of the stress-strain state of the investigated deposits of rock without pass of its separate parts. 

  4. Odd-number theorem: Optical feedback control at a subcritical Hopf bifurcation in a semiconductor laser

    Science.gov (United States)

    Schikora, S.; Wünsche, H.-J.; Henneberger, F.

    2011-02-01

    A subcritical Hopf bifurcation is prepared in a multisection semiconductor laser. In the free-running state, hysteresis is absent due to noise-induced escape processes. The missing branches are recovered by stabilizing them against noise through application of phase-sensitive noninvasive delayed optical feedback control. The same type of control is successfully used to stabilize the unstable pulsations born in the Hopf bifurcation. This experimental finding represents an optical counterexample to the so-called odd-number limitation of delayed feedback control. However, as a leftover of the limitation, the domains of control are extremely small.

  5. Numerical simulations of flow field in the target region of accelerator-driven subcritical reactor system

    CERN Document Server

    Chen Hai Yan

    2002-01-01

    Numerical simulations of flow field were performed by using the PHOENICS 3.2 code for the proposed spallation target of accelerator-driven subcritical reactor system (ADS). The fluid motion in the target is axisymmetric and is treated as a 2-D steady-state problem. A body-fitted coordinate system (BFC) is then chosen and a two-dimensional mesh of the flow channel is generated. Results are presented for the ADS target under both upward and downward flow, and for the target with diffuser plate installed below the window under downward flow

  6. Influence of thyroid states on stress gastric ulcer formation

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, D.E.; Walker, C.H.; Mason, G.A.

    1988-01-01

    This study was designed to test the hypothesis that thyroid states may affect the acute development of gastric lesions induced by cold-resistant stress. Normal (euthyroid), hyperthyroid and hypothyroid rats were used. Gastric lesion incidence and severity was significantly increased in hypothyroid rats, whereas in contrast hyperthyroid rats developed significantly less gastric lesions. As anticipated, plasma levels of thyroxin (T/sub 4/) were significantly elevated in hyperthyroid rats, and undetectable in hypothyroid rats. Acute pretreatment with i.p. cimetidine, but not T/sub 4/ 1 h prior to stress completely prevented gastric lesions formation in hypothyroid rats. Finally, binding of /sup 3/H-dihydroalprenolol to ..beta..-adrenergic receptors on brain membranes prepared from frontal cortex was reduced by 20% in hypothyroid rats after 3 h of stress. These and other data contained herein suggest that thyroid hormones contribute to modulate the responsiveness of the gastric mucosa to stress. The increase rate of ulcerogenesis observed in hypothyroid rats appears to be mediated by gastric acid secretion. The central mechanism for this response may involve decreased brain nonadrenergic receptor function.

  7. Microwave ion source for accelerator driven sub-critical system

    CERN Document Server

    Cui Bao Qun; Jiang Wei; LiLiQiang; WangRongWen

    2002-01-01

    A microwave ion source is under developing for a demonstration prototype of a accelerator driven sub-critical system at CIAE (China Institute of Atomic Energy), 100 mA hydrogen beam has been extracted from the source through a 7.3 mm aperture in diameter, proton ratio is more than 85%, reliability has been tested for 100 h without any failures

  8. Experimental Study of Subcritical Water Liquefaction of Biomass

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this work, hydrothermal liquefaction (HTL) of wood industry residues (wood, bark, sawdust) and macroalgae for producing biofuels has been investigated under subcritical water conditions (at temperature of 300 C), with and without the presence of catalyst. The effects of catalyst and biomass type...

  9. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    Local energy losses occur when there is a transition in open channel flow. Even though local losses in subcritical open channel flow due to changes in channel width have been studied, to date no studies have been reported for losses due to changes in bed elevations. Steps are commonly used in engineering applications ...

  10. Monte Carlo Alpha Iteration Algorithm for a Subcritical System Analysis

    Directory of Open Access Journals (Sweden)

    Hyung Jin Shim

    2015-01-01

    Full Text Available The α-k iteration method which searches the fundamental mode alpha-eigenvalue via iterative updates of the fission source distribution has been successfully used for the Monte Carlo (MC alpha-static calculations of supercritical systems. However, the α-k iteration method for the deep subcritical system analysis suffers from a gigantic number of neutron generations or a huge neutron weight, which leads to an abnormal termination of the MC calculations. In order to stably estimate the prompt neutron decay constant (α of prompt subcritical systems regardless of subcriticality, we propose a new MC alpha-static calculation method named as the α iteration algorithm. The new method is derived by directly applying the power method for the α-mode eigenvalue equation and its calculation stability is achieved by controlling the number of time source neutrons which are generated in proportion to α divided by neutron speed in MC neutron transport simulations. The effectiveness of the α iteration algorithm is demonstrated for two-group homogeneous problems with varying the subcriticality by comparisons with analytic solutions. The applicability of the proposed method is evaluated for an experimental benchmark of the thorium-loaded accelerator-driven system.

  11. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    2010-04-22

    7) 554-568. MORRIS HM and WIGGERT JM (1972) Applied Hydraulics in. Engineering. John Wiley & Sons, New York. ÖRSEL SI (2002) Local Losses at a Step in a Sub-critical Open. Channel Flow. M.Sc. Thesis, Department ...

  12. Extraction of antioxidants from Chlorella sp. using subcritical water treatment

    Science.gov (United States)

    Zakaria, S. M.; Mustapa Kamal, S. M.; Harun, M. R.; Omar, R.; Siajam, S. I.

    2017-06-01

    Chlorella sp. microalgae is one of the main source of natural bioactive compounds used in the food and pharmaceutical industries. Subcritical water extraction is the technique that offers an efficient, non-toxic, and environmental-friendly method to obtain natural ingredients. In this work, the extracts of Chlorella sp. microalgae was evaluated in terms of: chemical composition, extraction (polysaccharides) yield and antioxidant activity, using subcritical water extraction. Extractions were performed at temperatures ranging from 100°C to 300°C. The results show that by using subcritical water, the highest yield of polysaccharides is 23.6 that obtained at 150°C. Analysis on the polysaccharides yield show that the contents were highly influenced by the extraction temperature. The individual antioxidant activity were evaluated by in vitro assay using a free radical method. In general, the antioxidant activity of the extracts obtained at different water temperatures was high, with values of 31.08-54.29 . The results indicated that extraction by subcritical water was effective and Chlorella sp. can be a useful source of natural antioxidants.

  13. Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects

    OpenAIRE

    Talbott, Shawn M; Talbott, Julie A; George, Annie; Pugh, Mike

    2013-01-01

    Background Eurycoma longifolia is a medicinal plant commonly called tongkat ali (TA) and ?Malaysian ginseng.? TA roots are a traditional ?anti-aging? remedy and modern supplements are intended to improve libido, energy, sports performance and weight loss. Previous studies have shown properly-standardized TA to stimulate release of free testosterone, improve sex drive, reduce fatigue, and improve well-being. Methods We assessed stress hormones and mood state in 63 subjects (32 men and 31 women...

  14. Analytical Study of Stress State in HTS Solenoids

    Energy Technology Data Exchange (ETDEWEB)

    Barzi, E.; Terzini, E.; /Fermilab

    2009-01-01

    A main challenge for high field solenoids made of in High Temperature Superconductor (HTS) is the large stress developed in the conductor. This is especially constraining for BSCCO, a brittle and strain sensitive ceramic material. To find parametric correlations useful in magnet design, analytical models can be used. A simple model is herein proposed to obtain the radial, azimuthal and axial stresses in a solenoid as a function of size, i.e. self-field, and of the engineering current density for a number of different constraint hypotheses. The analytical model was verified against finite element modeling (FEM) using the same hypotheses of infinite rigidity of the constraints and room temperature properties. FEM was used to separately evaluate the effect of thermal contractions at 4.2 K for BSCCO and YBCO coils. Even though the analytical model allows for a finite stiffness of the constraints, it was run using infinite stiffness. For this reason, FEM was again used to determine how much stresses change when considering an outer stainless steel skin with finite rigidity for both BSCCO and YBCO coils. For a better understanding of the actual loads that high field solenoids made of HTS will be subject to, we have started some analytical studies of stress state in solenoids for a number of constraint hypotheses. This will hopefully show what can be achieved with the present conductor in terms of self-field. The magnetic field (B) exerts a force F = B x J per unit volume. In superconducting magnets, where the field and current density (J) are both high, this force can be very large, and it is therefore important to calculate the stresses in the coil.

  15. Measured resolved shear stresses and Bishop-Hill stress states in individual grains of austenitic stainless steel

    DEFF Research Database (Denmark)

    Juul, Nicolai Ytterdal; Oddershede, Jette; Beaudoin, Armand

    2017-01-01

    The full three-dimensional stress state of 172 individual bulk grains in austenitic stainless steel 316L at 0.1 and 1% sample elongation has been determined with sufficient accuracy to allow comparison with the theoretical Bishop-Hill stress states for plastically deforming grains as well as calc...

  16. Evaluation of reactivity monitoring techniques at the Yalina - Booster sub-critical facility

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.

    2014-07-01

    The management of long-lived radioactive wastes produced by nuclear reactors constitutes one of the main challenges of nuclear technology nowadays. A possible option for its management consists in the transmutation of long lived nuclides into shorter lived ones. Accelerator Driven Subcritical Systems (ADS) are one of the technologies in development to achieve this goal. An ADS consists in a subcritical nuclear reactor maintained in a steady state by an external neutron source driven by a particle accelerator. The interest of these systems lays on its capacity to be loaded with fuels having larger contents of minor actinides than conventional critical reactors, and in this way, increasing the transmutation rates of these elements, that are the main responsible of the long-term radiotoxicity of nuclear waste. One of the key points that have been identified for the operation of an industrial-scale ADS is the need of continuously monitoring the reactivity of the subcritical system during operation. For this reason, since the 1990s a number of experiments have been conducted in zero-power subcritical assemblies (MUSE, RACE, KUCA, Yalina, GUINEVERE/FREYA) in order to experimentally validate these techniques. In this context, the present thesis is concerned with the validation of reactivity monitoring techniques at the Yalina-Booster subcritical assembly. This assembly belongs to the Joint Institute for Power and Nuclear Research (JIPNR-Sosny) of the National Academy of Sciences of Belarus. Experiments concerning reactivity monitoring have been performed in this facility under the EUROTRANS project of the 6th EU Framework Program in year 2008 under the direction of CIEMAT. Two types of experiments have been carried out: experiments with a pulsed neutron source (PNS) and experiments with a continuous source with short interruptions (beam trips). For the case of the first ones, PNS experiments, two fundamental techniques exist to measure the reactivity, known as the prompt

  17. Subcritical saturation of the magnetorotational instability through mean magnetic field generation

    Science.gov (United States)

    Xie, Jin-Han; Julien, Keith; Knobloch, Edgar

    2018-03-01

    The magnetorotational instability is widely believed to be responsible for outward angular momentum transport in astrophysical accretion discs. The efficiency of this transport depends on the amplitude of this instability in the saturated state. We employ an asymptotic expansion based on an explicit, astrophysically motivated time-scale separation between the orbital period, Alfvén crossing time and viscous or resistive dissipation time-scales, originally proposed by Knobloch and Julien, to formulate a semi-analytical description of the saturated state in an incompressible disc. In our approach a Keplerian shear flow is maintained by the central mass but the instability saturates via the generation of a mean vertical magnetic field. The theory assumes that the time-averaged angular momentum flux and the radial magnetic flux are constant and determines both self-consistently. The results predict that, depending on parameters, steady saturation may be supercritical or subcritical, and in the latter case that the upper (lower) solution branch is always stable (unstable). The angular momentum flux is always outward, consistent with the presence of accretion, and for fixed wavenumber peaks in the subcritical regime. The limit of infinite Reynolds number at large but finite magnetic Reynolds number is also discussed.

  18. Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements

    Science.gov (United States)

    van Wyk, F.; Highcock, E. G.; Field, A. R.; Roach, C. M.; Schekochihin, A. A.; Parra, F. I.; Dorland, W.

    2017-11-01

    We investigate the effect of varying the ion temperature gradient (ITG) and toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer core of MAST by means of local gyrokinetic simulations. We show that nonlinear simulations reproduce the experimental ion heat flux and that the experimentally measured values of the ITG and the flow shear lie close to the turbulence threshold. We demonstrate that the system is subcritical in the presence of flow shear, i.e., the system is formally stable to small perturbations, but transitions to a turbulent state given a large enough initial perturbation. We propose that the transition to subcritical turbulence occurs via an intermediate state dominated by low number of coherent long-lived structures, close to threshold, which increase in number as the system is taken away from the threshold into the more strongly turbulent regime, until they fill the domain and a more conventional turbulence emerges. We show that the properties of turbulence are effectively functions of the distance to threshold, as quantified by the ion heat flux. We make quantitative comparisons of correlation lengths, times, and amplitudes between our simulations and experimental measurements using the MAST BES diagnostic. We find reasonable agreement of the correlation properties, most notably of the correlation time, for which significant discrepancies were found in previous numerical studies of MAST turbulence.

  19. [Physical state of adolescents with the high stress reactivity].

    Science.gov (United States)

    Krivolapchuk, I A

    2012-01-01

    Research objective was studying of features of a physical state (PS) adolescents of 13-14 years with high (n = 97) and low (n = 85) level of stress reactivity. The obtained data testify that in puberty formation of mechanisms of energy supply for muscle activity at adolescents with various level of stress reactivity occurs heterochronic and nonlinearly. Thus hyperreactivity boys of 13-14 years are characterised concerning high anaerobic alactic and the low aerobic productivity of the organism raised by physiological working costs and slowed down restoration after loadings of the big and submaximum capacity. Specificity of physical readiness of hyperreactivity teenagers consists that at them the high level of development of speed and force is combined with rather low level of development of the general endurance. Intergroup distinctions concerning muscular working capacity and the impellent readiness, caused by stress reactivity, are shown at adolescents of 13-14 years at different stages of puberty (SP). Thus and hyper--and hyporeactivity boys with II and III SP, are characterised in comparison with children with IV SP higher indicators of aerobic productivity of an organism, against rather small anaerobic possibilities. Results of research give the basis to believe, that at hyporeactivity adolescents efficiency of functioning of mechanisms of antihypoxic protection is lowered.

  20. Stress state measured at ~7 km depth in the Tarim Basin, NW China

    OpenAIRE

    Sun, Dongsheng; Sone, Hiroki; Lin, Weiren; Cui, Junwen; He, Bizhu; Lv, Haitao; Cao, Zicheng

    2017-01-01

    The in-situ stress state in the Tarim Basin, Northwest China, down to 7?km depth is constrained using the anelastic strain recovery (ASR) method and wellbore failure analysis. Results are consistent between the two methods, and indicate that the maximum principal stresses (?1) are close to vertical and the intermediate and minimum principal stresses (?2 and ?3) are approximately horizontal. The states of stress at the studied wellbore is in the normal faulting stress regime within the Tarim B...

  1. First reactivity determination of a subcritical reactor using a single beam-trip and fission chambers operating in current mode

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Ordonez, M.; Villamarin, D.; Becares, V.; Gonzalez-Romero, E.M. [Nuclear Innovation Group, CIEMAT, Avda. Complutense, Madrid (Spain); Bergloef, C. [Reactor Physics Department, Royal Institute of Technology, Stockholm (Sweden); Bournos, V.; Fokov, Y.; Kiyavitskaya, H. [Joint Institute for Power and Nuclear Research, National Academy of Sciences, Minsk (Belarus)

    2009-06-15

    were performed at several subcriticality levels (with effective multiplication constants of 0.97 and 0.95) and, in addition, two different loadings with similar subcriticality but different source multiplication characteristics were studied. Relevant information from the three zones of the reactor -fast, thermal and reflector- was obtained from these experimental results and the validity of the reactivity determination methods using fission chambers operating in current mode has been stated. (authors)

  2. Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects.

    Science.gov (United States)

    Talbott, Shawn M; Talbott, Julie A; George, Annie; Pugh, Mike

    2013-05-26

    Eurycoma longifolia is a medicinal plant commonly called tongkat ali (TA) and "Malaysian ginseng." TA roots are a traditional "anti-aging" remedy and modern supplements are intended to improve libido, energy, sports performance and weight loss. Previous studies have shown properly-standardized TA to stimulate release of free testosterone, improve sex drive, reduce fatigue, and improve well-being. We assessed stress hormones and mood state in 63 subjects (32 men and 31 women) screened for moderate stress and supplemented with a standardized hot-water extract of TA root (TA) or Placebo (PL) for 4 weeks. Analysis of variance (ANOVA) with significance set at p sleep deprivation, and exercise training.

  3. Characterizing the neurotranscriptomic states in alternative stress coping styles

    National Research Council Canada - National Science Library

    Wong, Ryan Y; Lamm, Melissa S; Godwin, John

    2015-01-01

    Animals experience stress in many contexts and often successfully cope. Individuals exhibiting the proactive versus reactive stress coping styles display qualitatively different behavioral and neuroendocrine responses to stressors...

  4. The imprint of the Hawking effect in subcritical flows

    CERN Document Server

    Coutant, Antonin

    2016-01-01

    We study the propagation of low frequency shallow water waves on a one dimensional flow of varying depth. When taking into account dispersive effects, the linear propagation of long wavelength modes on uneven bottoms excites new solutions of the dispersion relation which possess a much shorter wavelength. The peculiarity is that one of these new solutions has a negative energy. When the flow becomes supercritical, this mode has been shown to be responsible for the (classical) analog of the Hawking effect. For subcritical flows, the production of this mode has been observed numerically and experimentally, but the precise physics governing the scattering remained unclear. In this work, we provide an analytic treatment of this effect in subcritical flows. We analyze the scattering of low frequency waves using a new perturbative series, derived from a generalization of the Bremmer series. We show that the production of short wavelength modes is governed by a complex value of the position: a complex turning point....

  5. Analysis of reactivity determination methods in the subcritical experiment Yalina

    Science.gov (United States)

    Persson, Carl-Magnus; Seltborg, Per; Åhlander, Alexandra; Gudowski, Waclaw; Stummer, Thomas; Kiyavitskaya, Hanna; Bournos, Victor; Fokov, Yurij; Serafimovich, Ivan; Chigrinov, Sergey

    2005-12-01

    Different reactivity determination methods have been investigated, based on experiments performed at the subcritical assembly Yalina in Minsk, Belarus. The development of techniques for on-line monitoring of the reactivity level in a future accelerator-driven system (ADS) is of major importance for safe operation. Since an ADS is operating in a subcritical mode, the safety margin to criticality must be sufficiently large. The investigated methods are the Slope Fit Method, the Sjöstrand Method and the Source Jerk Method. The results are compared with Monte Carlo simulations performed with different nuclear data libraries. The results of the Slope Fit Method are in good agreement with the Monte Carlo simulation results, whereas the Sjöstrand Method appears to underestimate the criticality somewhat. The Source Jerk Method is subject to inadequate statistical accuracy.

  6. A microfluidic sub-critical water extraction instrument

    Science.gov (United States)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

    2017-11-01

    This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

  7. A simple proof of exponential decay of subcritical contact processes

    Czech Academy of Sciences Publication Activity Database

    Swart, Jan M.

    2018-01-01

    Roč. 170, 1-2 (2018), s. 1-9 ISSN 0178-8051 R&D Projects: GA ČR(CZ) GA16-15238S Institutional support: RVO:67985556 Keywords : subcritical contact process * sharpness of the phase transition * eigenmeasure Subject RIV: BA - General Mathematics Impact factor: 1.895, year: 2016 http:// library .utia.cas.cz/separaty/2016/SI/swart-0462694.pdf

  8. Development and Investigation of Reactivity Measurement Methods in Subcritical Cores

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Johanna

    2005-05-01

    Subcriticality measurements during core loading and in future accelerator driven systems have a clear safety relevance. In this thesis two subcriticality methods are treated: the Feynman-alpha and the source modulation method. The Feynman-alpha method is a technique to determine the reactivity from the relative variance of the detector counts during a measurement period. The period length is varied to get the full time dependence of the variance-to-mean. The corresponding theoretical formula was known only with stationary sources. In this thesis, due to its relevance for novel reactivity measurement methods, the Feynman-alpha formulae for pulsed sources for both the stochastic and the deterministic cases are treated. Formulae neglecting as well as including the delayed neutrons are derived. The formulae neglecting delayed neutrons are experimentally verified with quite good agreement. The second reactivity measurement technique investigated in this thesis is the so-called source modulation technique. The theory of the method was elaborated on the assumption of point kinetics, but in practice the method will be applied by using the signal from a single local neutron detector. Applicability of the method therefore assumes point kinetic behaviour of the core. Hence, first the conditions of the point kinetic behaviour of subcritical cores was investigated. After that the performance of the source modulation technique in the general case as well as and in the limit of exact point kinetic behaviour was examined. We obtained the unexpected result that the method has a finite, non-negligible error even in the limit of point kinetic behaviour, and a substantial error in the operation range of future accelerator driven subcritical reactors (ADS). In practice therefore the method needs to be calibrated by some other method for on-line applications.

  9. Design, Development and Installation of Jordan Subcritical Assembly

    Directory of Open Access Journals (Sweden)

    Ned Xoubi

    2013-01-01

    Full Text Available Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 mm pitch. The fuel rods are based on PWR fuel structural pattern type, made of uranium oxide (UO2 with 3.4 wt% 235U enrichment in zirconium alloy (Zr-4 cladding. Design, optimization, and verification were performed using MCNP5 nuclear code; the computed effective multiplication factor is 0.95923. The JSA is designed to fulfill the training needs of students and is equipped to perform all of the fundamental experiments required for a typical nuclear engineering university program. This paper presents the design, development, modeling, core analysis, and utilization of Jordan’s first nuclear facility and why this simplified low cost reactor presents an attractive choice to fulfill the preliminary experimental needs of nuclear engineering education in developing countries.

  10. Creep stresses in a spherical shell under steady state temperature

    Science.gov (United States)

    Verma, Gaurav; Rana, Puneet

    2017-10-01

    The paper investigates the problem of creep of a spherical structure under the influence of steady state temperature. The problem of creep in spherical shell is solved by using the concept of generalized strain measures and transition hypothesis given by Seth. The problem has reduced to non-linear differential equation for creep transition. This paper deals with the non-linear behaviour of spherical shell under thermal condition. The spherical shell structures are easily vulnerable to creep, shrinkage and thermal effects; a thorough understanding of their time-dependent behaviour has been fully established. The paper aims to provide thermal creep analysis to enhance the effective design and long life of shells, and a theoretical model is developed for calculating creep stresses and strains in a spherical shell with purpose. Results obtained for the problem are depicted graphically.

  11. Flavour fields in steady state: stress tensor and free energy

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Avik; Kundu, Arnab [Theory Division, Saha Institute of Nuclear Physics,1/AF Bidhannagar, Kolkata- 700064 (India); Kundu, Sandipan [Department of Physics, Cornell University,Ithaca, New York, 14853 (United States)

    2016-02-16

    The dynamics of a probe brane in a given gravitational background is governed by the Dirac-Born-Infeld action. The corresponding open string metric arises naturally in studying the fluctuations on the probe. In Gauge-String duality, it is known that in the presence of a constant electric field on the worldvolume of the probe, the open string metric acquires an event horizon and therefore the fluctuation modes on the probe experience an effective temperature. In this article, we bring together various properties of such a system to a formal definition and a subsequent narration of the effective thermodynamics and the stress tensor of the corresponding flavour fields, also including a non-vanishing chemical potential. In doing so, we point out a potentially infinitely-degenerate scheme-dependence of regularizing the free energy, which nevertheless yields a universal contribution in certain cases. This universal piece appears as the coefficient of a log-divergence in free energy when a space-filling probe brane is embedded in AdS{sub d+1}-background, for d=2,4, and is related to conformal anomaly. For the special case of d=2, the universal factor has a striking resemblance to the well-known heat current formula in (1+1)-dimensional conformal field theory in steady-state, which endows a plausible physical interpretation to it. Interestingly, we observe a vanishing conformal anomaly in d=6.

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

    Science.gov (United States)

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

    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...

  13. Radioactive isotope production for medical applications using Kharkov electron driven subcritical assembly facility.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, Y.; Nuclear Engineering Division

    2007-05-15

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an accelerator driven subcritical assembly. The main functions of the subcritical assembly are the medical isotope production, neutron thereby, and the support of the Ukraine nuclear industry. Reactor physics experiments and material research will be carried out using the capabilities of this facility. The United States of America and Ukraine have started collaboration activity for developing a conceptual design for this facility with low enrichment uranium (LEU) fuel. Different conceptual designs are being developed based on the facility mission and the engineering requirements including nuclear physics, neutronics, heat transfer, thermal hydraulics, structure, and material issues. Different fuel designs with LEU and reflector materials are considered in the design process. Safety, reliability, and environmental considerations are included in the facility conceptual design. The facility is configured to accommodate future design improvements and upgrades. This report is a part of the Argonne National Laboratory Activity within this collaboration for developing and characterizing the subcritical assembly conceptual design. In this study, the medical isotope production function of the Kharkov facility is defined. First, a review was carried out to identify the medical isotopes and its medical use. Then a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Finally, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and irradiation location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes were considered and all transmutation channels are used including (n,{gamma}), (n,2n), (n,p), and ({gamma},n). In the second part

  14. Be Cool with Academic Stress: The Association between Emotional States and Regulatory Strategies among Chinese Adolescents

    Science.gov (United States)

    Sang, Biao; Pan, Tingting; Deng, Xinmei; Zhao, Xu

    2018-01-01

    Numerous studies have suggested that academic stress has negative impact on adolescents' psychological function, few of those studies, however, considered whether and how the impact of stress on adolescents' emotional states is moderated by corresponding regulation. This study aimed to examine the fluctuation of emotional states before and after…

  15. Relationship between Organizational Climate, Job Stress and Job Performance Officer at State Education Department

    Science.gov (United States)

    Suandi, Turiman; Ismail, Ismi Arif; Othman, Zulfadli

    2014-01-01

    This research aims at finding out the relationship between Organizational Climate, job stress and job performance among State Education Department (JPN) officers . The focus of the research is to determine the job performance of state education department officers, level of job stress among the officers, level of connection between organizational…

  16. The influence of the anisotropic stress state on the intermediate strain properties of granular material

    KAUST Repository

    Goudarzy, M.

    2017-07-20

    This paper shows the effect of anisotropic stress state on intermediate strain properties of cylindrical samples containing spherical glass particles. Tests were carried out with the modified resonant column device available at Ruhr-Universität Bochum. Dry samples were subjected to two anisotropic stress states: (a) cell pressure, σ′h, constant and vertical stress, σ′v, increased (stress state GB-I) and (b) σ′v/σ′h equal to 2 (stress state GB-II). The experimental results revealed that the effect of stress state GB-II on the modulus and damping ratio was more significant and obvious than stress state GB-I. The effect of the anisotropic stress state was explained through the impact of confining pressure and anisotropic stress components on the stiffness and damping ratio. The results showed that: (a) G(γ) increased, η(γ) decreased and their strain non-linearity decreased with an increase in the confining pressure component σ′vσ′h; (b) G(γ) decreased, η(γ) increased and their strain non-linearity increased with an increase in the anisotropic stress component, σ′v/σ′h. The analysis of results revealed that reference shear strain was also affected by anisotropic stress state. Therefore, an empirical relationship was developed to predict the reference shear strain, as a function of confining pressure and anisotropic stress components. Additionally, the damping ratio was written as a function of the minimum damping ratio and the reference shear strain.

  17. The safe, economical operation of a slightly subcritical reactor and transmutor with a small proton accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi

    1994-04-01

    This report describes methods in which an accelerator can be used to increase the safety and neutron economy of a power reactor and transmutor of long-lived radioactive wastes, such as minor actinides and fission products, by providing neutrons for its subcritical operation. Instead of the rather large subcriticality of k=0.9--0.95 which we originally proposed for such a transmutor, we propose to use a slightly subcritical reactor, such as k=0.99, which will avoid many of the technical difficulties that are associated with large subcriticality, such as localized power peaking, radiation damage due to the injection of medium-energy protons, the high current accelerator, and the requirement for a long beam-expansion section. We analyzed the power drop that occurred in Phoenix reactor, and show that the operating this reactor in subcritical condition improves its safety.

  18. Subcritical and supercritical water oxidation of CELSS model wastes

    Science.gov (United States)

    Takahashi, Y.; Wydeven, T.; Koo, C.

    1989-01-01

    A mixture of ammonium hydroxide with acetic acid and a slurry of human feces, urine, and wipes were used as CELSS model wastes to be wet-oxidized at temperatures from 250 to 500 C, i.e. below and above the critical point of water (374 C and 218 kg/sq cm or 21.4 MPa). The effects of oxidation temperature ( 250-500 C) and residence time (0-120 mn) on carbon and nitrogen and on metal corrosion from the reactor material were studied. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 C, above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. A substantial amount of nitrogen remained in solution in the form of ammonia at temperatures ranging from 350 to 450 C suggesting that, around 400 C, organic carbon is completely oxidized and most of the nitrogen is retained in solution. The Hastelloy C-276 alloy reactor corroded during subcritical and supercritical water oxidation.

  19. Hydrolysis of sweet blue lupin hull using subcritical water technology.

    Science.gov (United States)

    Ciftci, Deniz; Saldaña, Marleny D A

    2015-10-01

    Hydrolysis of sweet blue lupin hulls was conducted in this study using subcritical water technology. Effects of process parameters, such as pressure (50-200 bar), temperature (160-220°C), flow rate (2-10 mL/min), and pH (2-12), were studied to optimize maximum hemicellulose sugars recovery in the extracts. Extracts were analyzed for total hemicellulose sugars, phenolics and organic carbon contents and solid residues left after treatments were also characterized. Temperature, flow rate, and pH had a significant effect on hemicellulose sugar removal; however, the effect of pressure was not significant. The highest yield of hemicellulose sugars in the extracts (85.5%) was found at 180°C, 50 bar, 5 mL/min and pH 6.2. The thermal stability of the solid residue obtained at optimum conditions improved after treatment and the crystallinity index increased from 11.5% to 58.6%. The results suggest that subcritical water treatment is a promising technology for hemicellulose sugars removal from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. GASICA: Generic Automated Stress Induction and Control ApplicationDesign of an application for controlling the stress state

    Directory of Open Access Journals (Sweden)

    Benny Van Der Vijgh

    2014-12-01

    Full Text Available 1.In a multitude of research and therapy paradigms it is relevant to know, and desirably to control, the stress state of a patient or participant. Examples include research paradigms in which the stress state is the dependent or independent variable, or therapy paradigms where this state indicates the boundaries of the therapy. To our knowledge, no application currently exists that focuses specifically on the automated control of the stress state while at the same time being generic enough to be used in various therapy and research purposes. Therefore, we introduce GASICA, an application aimed at the automated control of the stress state in a multitude of therapy and research paradigms. The application consists of three components: a digital stressor game, a set of measurement devices and a feedback model. These three components form a closed loop (called a biocybernetic loop by Pope, Bogart, & Bartolome, 1995 and Fairclough, 2009 that continuously presents an acute psychological stressor, measures several physiological responses to this stressor, and adjusts the stressor intensity based on these measurements by means of the feedback model, hereby aiming to control the stress state. In this manner GASICA presents multidimensional and ecological valid stressors, whilst continuously in control of the form and intensity of the presented stressors, aiming at the automated control of the stress state. Furthermore, the application is designed as a modular open-source application to easily implement different therapy and research tasks using a high-level programming interface and configuration file, and allows for the addition of (existing measurement equipment, making it usable for various paradigms.

  1. Measured Resolved Shear Stresses and Bishop Hill Stress States in Individual Grains of Austenitic Stainless Steel (Postprint)

    Science.gov (United States)

    2017-09-13

    AFRL-RX-WP-JA-2017-0330 MEASURED RESOLVED SHEAR STRESSES AND BISHOP-HILL STRESS STATES IN INDIVIDUAL GRAINS OF AUSTENITIC STAINLESS ...IN INDIVIDUAL GRAINS OF AUSTENITIC STAINLESS STEEL (POSTPRINT) 5a. CONTRACT NUMBER IN-HOUSE 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...grains in austenitic stainless steel 316 L at 0.1 and 1% sample elongation has been determined with sufficient accuracy to allow comparison with the

  2. Effect of SO2 concentration as an impurity on carbon steel corrosion under subcritical CO2 environment

    Science.gov (United States)

    Mahlobo, MGR; Premlall, K.; Olubambi, PA

    2017-12-01

    Carbon dioxide (CO2) is considered to be easier to transport over moderate distances when turned into supercritical state (dense phase) than at any other state. Because of this reason, the transportation of CO2 during carbon capture and storage requires CO2 to be at its supercritical state. CO2 temperature profile from different regions causes CO2 to deviate between supercritical and subcritical state (gas/liquid phase). In this study the influence of sulphur dioxide (SO2) on the corrosion of carbon steel was evaluated under different SO2 concentrations (0.5, 1.5 and 5%) in combination with subcritical CO2. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Energy-Dispersive X-ray Spectroscopy (EDS) were used to characterize the CO2 corrosion product layer formed on the carbon steel surface. The weight loss results showed that corrosion rate increased with SO2 concentration with corrosion rate up to 7.45 mm/year while at 0% SO2 the corrosion rate was 0.067 mm/year.

  3. Sub-critical crack growth in silicate glasses: Role of network topology

    Science.gov (United States)

    Smedskjaer, Morten M.; Bauchy, Mathieu

    2015-10-01

    The presence of water in the surrounding atmosphere can cause sub-critical crack growth (SCCG) in glasses, a phenomenon known as fatigue or stress corrosion. Here, to facilitate the compositional design of more fatigue-resistant glasses, we investigate the composition dependence of SCCG by studying fourteen silicate glasses. The fatigue curves (V-KI) have been obtained by indentation experiments through measurements of the crack length as a function of post-indentation fatigue duration. Interestingly, we find that the fatigue resistance parameter N is generally improved by increasing the alumina content and is thereby found to exhibit a fairly linear dependence on the measured Vickers hardness HV for a wide range of N and HV values. This finding highlights the important role of network topology in governing the SCCG in silicate glasses, since hardness has been shown to scale linearly with the number of atomic constraints. Our results therefore suggest that glasses showing under-constrained flexible networks, which feature floppy internal modes of deformation, are more readily attacked by water molecules, thus promoting stress corrosion and reducing the fatigue resistance.

  4. Spectral characteristics of (111 silicon with Raman selections under different states of stress

    Directory of Open Access Journals (Sweden)

    Wei Qiu

    2017-07-01

    Full Text Available (111 silicon is widely used in current microstructures. In this study, theoretical analysis shows that different states of elastic stress may result in different eigenvalues and their respective eigenvectors of the lattice dynamics secular equation. The key point in determining the spectral character is to obtain the Raman tensor corresponding to each eigenvector whose eigenvalue can be represented by a function of the stress tensor components. As examples, the wavenumber–stress factors under some specific states of stress at typical polarization configurations were determined. Finally, a calibration experiment was performed to validate the theoretical prediction.

  5. Numerical study on core damage and interpretation of in situ state of stress

    Energy Technology Data Exchange (ETDEWEB)

    Hakala, M. [Gridpoint Finland Oy (Finland)

    1999-06-01

    Core disking is a phenomenon where a diamond cored core sample will be sliced when released from a stressed host rock. Ring disking is a similar phenomenon which takes place during overcoring with a pilot hole. Because of the uniform shape and spacing of disk fracturing, it has the potential to be used for estimating the in situ state of stress. If this is feasible, it could be used in high stress states where the traditional stress measuring techniques are not valid or even possible. In this work the both the core disking and ring disking phenomena were studied based on the elastic bottom hole stress application developed and a series of fracture growth stability simulations. The results-showed that both phenomena are very complicated and site specific, but the spacing, shape, extent and initiation point are clearly stress state dependent. Throughout the work, guidelines for the in situ stress field interpretation method were developed and implemented for the borehole aligned orthogonal stress field and Poisson`s ratio of 0.25. Based on this study, the in situ state of stress can be estimated with acceptable accuracy if information on both core disking and ring disking is available. On the other hand, as an indirect method, there are no reasons to use it if direct measurements can be used. (orig.) 35 refs.

  6. 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.

  7. Thorium as a Fuel for Accelerator Driven Subcritical Electronuclear Systems

    CERN Document Server

    Barashenkov, V S; Singh, V

    2000-01-01

    Neutron yield and energy production in a very large, practically infinite, uranium and thorium target-blocks irradiated by protons with energies in the range 0.1-2 GeV are studied by Monte Carlo method. Though the comparison of uranium and thorium targets shows that the neutron yield in the latter is 30-40 % less and the energy gain is approximatelly two times smaller, accelerator Driven subcritical Systems (ADS) with thorium fuel are very perspective at the bombarding energies higher than several hundreds MeV. An admixture of fissile elements U^{233}, U^{235}, Pu^{239} in the set-up gives larger neutron multiplication which in turn shows better energy amplification. It is argued that due to the practically complete burning of the fuel in such set-up there is no need of technology of conversion of the exhaust fuel.

  8. Gravity-driven soap film dynamics in subcritical regimes

    Science.gov (United States)

    Auliel, M. I.; Castro, F.; Sosa, R.; Artana, G.

    2015-10-01

    We undertake the analysis of soap-film dynamics with the classical approach of asymptotic expansions. We focus our analysis in vertical soap film tunnels operating in subcritical regimes with elastic Mach numbers Me=O(10-1) . Considering the associated set of nondimensional numbers that characterize this flow, we show that the flow behaves as a two-dimensional (2D) divergence free flow with variable mass density. When the soap film dynamics agrees with that of a 2D and almost constant mass density flow, the regions where the second invariant of the velocity gradient is non-null correspond to regions where the rate of change of film thickness is non-negligible.

  9. Efficient decomposition of a new fluorochemical surfactant: perfluoroalkane disulfonate to fluoride ions in subcritical and supercritical water.

    Science.gov (United States)

    Hori, Hisao; Saito, Hiroki; Sakai, Hidenori; Kitahara, Toshiyuki; Sakamoto, Takehiko

    2015-06-01

    Decomposition of (-)O3SC3F6SO3(-) in subcritical and supercritical water was investigated, and the results were compared with the results for C3F7SO3(-). This is the first report on the decomposition of perfluoroalkane disulfonates, which are being introduced in electronics industry as greener alternatives to environmentally persistent and bioaccumulative perfluoroalkyl surfactants. Addition of zerovalent iron to the reaction system dramatically increased the yield of F(-) in the reaction solution: when the reaction of (-)O3SC3F6SO3(-) was carried out in subcritical water at 350°C for 6h, the F(-) yield was 70%, which was 23times the yield without zerovalent iron. Prolonged reaction increased the F(-) formation: after 18h, the F(-) yield from the reaction of (-)O3SC3F6SO3(-) reached 81%, which was 2.1times the F(-) yield from the reaction of C3F7SO3(-). Although the reactivity of FeO toward these substrates was lower than zerovalent iron in subcritical water, the reactivity was enhanced when the reaction temperature was elevated to supercritical state, at which temperature FeO underwent in situ disproportionation to form zerovalent iron, which acted as the reducing agent. When the reaction of (-)O3SC3F6SO3(-) was carried out in the presence of FeO in supercritical water at 380°C for 18h, the F(-) yield reached 92%, which was the highest yield among tested. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Experiments and numerical simulation of stress-state-dependent damage in sheet metal forming

    Science.gov (United States)

    Brünig, M.; Gerke, S.; Schmidt, M.

    2017-09-01

    Experiments and corresponding numerical simulations with new biaxially loaded specimens taken from thin metal sheets are discussed. Inelastic deformations as well as damage and fracture behavior of the specimens are investigated under different biaxial loading conditions covering a wide range of stress states to analyze the stress-state-dependent damage and failure mechanisms in ductile metals. During the experiments strain fields in critical regions of the specimens are analyzed by digital image correlation. Corresponding numerical simulations deliver information on stress states in tested specimens. The results are used to propose stress-state-dependent damage and failure criteria corresponding to various damage mechanisms depending on stress triaxiality and the Lode parameter. They are validated by series of biaxial experiments with newly developed specimens and corresponding numerical simulations. This demonstrates the efficiency of the new specimens’ geometries covering a wide range of stress states in the shear-tension and shear-compression regime allowing validation of stress-state-dependent functions for the damage criteria and damage evolution laws.

  11. Subcritical-Water Extraction of Organics from Solid Matrices

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank; Patrick, Steven; Kirby, James; Bickler, Donald; Willis, Peter; Pelletier, Christine; Bryson, Charles

    2009-01-01

    An apparatus for extracting organic compounds from soils, sands, and other solid matrix materials utilizes water at subcritical temperature and pressure as a solvent. The apparatus, called subcritical water extractor (SCWE), is a prototype of subsystems of future instrumentation systems to be used in searching for organic compounds as signs of past or present life on Mars. An aqueous solution generated by an apparatus like this one can be analyzed by any of a variety of established chromatographic or spectroscopic means to detect the dissolved organic compound( s). The apparatus can be used on Earth: indeed, in proof-of-concept experiments, SCWE was used to extract amino acids from soils of the Atacama Desert (Chile), which was chosen because the dryness and other relevant soil conditions there approximate those on Mars. The design of the apparatus is based partly on the fact that the relative permittivity (also known as the dielectric constant) of liquid water varies with temperature and pressure. At a temperature of 30 C and a pressure of 0.1 MPa, the relative permittivity of water is 79.6, due to the strong dipole-dipole electrostatic interactions between individual molecular dipoles. As the temperature increases, increasing thermal energy causes increasing disorientation of molecular dipoles, with a consequent decrease in relative permittivity. For example, water at a temperature of 325 C and pressure of 20 MPa has a relative permittivity of 17.5, which is similar to the relative permittivities of such nonpolar organic solvents as 1-butanol (17.8). In the operation of this apparatus, the temperature and pressure of water are adjusted so that the water can be used in place of commonly used organic solvents to extract compounds that have dissimilar physical and chemical properties.

  12. Stress Concentration in the Elastoplastic State and Residual Stress After Unloading

    Science.gov (United States)

    1985-03-01

    dimensional stress-strain curve given by the Ramberg - Osgood equation (ref 7) for this material has the following form: Ee/°sec Ä (°/°sec) + (3/7)( o/osec) U...7. Ramberg , W. and Osgood , W. R., "Description of Stress-Strain Curves of Three Parameters," NACA TN 902, 1943. 8. Mesnager, M., "Sur la...82175 (1) 7Ramberg, W. and Osgood , W. R., "Description of Stress-Strain Curves of Three Parameters," NACA TN 902, 1943. where e denotes strain, and a

  13. Changes of Swimmers' Emotional States during the Preparation of National Championship: Do Recovery-Stress States Matter?

    Science.gov (United States)

    Vacher, Philippe; Nicolas, Michel; Martinent, Guillaume; Mourot, Laurent

    2017-01-01

    This study examined the trajectories of emotional states and their within-person synergies with perceived stress and recovery during a 4-month training period preceding the French swimming championships. A Multilevel Growth Curve Analysis approach was used with 16 high level swimmers. Five waves of assessments of emotional states, perceived stress and recovery were completed. Results indicated that emotional states were characterized by distinct trajectories during the training period preceding a major competition. Specifically, significant positive linear effects of time (i.e., linear increase over time) and negative quadratic effects of squared time (i.e., inverted U shape over time) on anxiety, dejection and anger were observed, whereas the opposite pattern of results was found for happiness and excitement. Moreover, level 2 perceived stress and recovery (i.e., inter-individual predictors) were significantly associated with athletes' unpleasant and pleasant emotional states respectively. At level 1, perceived recovery (i.e., intra-individual predictor) was positively associated with happiness and excitement and negatively related to anxiety, dejection and anger. Finally, within-person interactions of general stress and recovery with time and squared time reached significance for excitement, whereas within-person interactions of specific and total stress with time and squared time reached significance for anxiety. Overall, this study provided insights into the central role played by perceived stress and recovery on the emotional states experienced by high level swimmers. Operational strategies were suggested in order to optimize the stress-recovery balance and in turn the athletes' emotional states during a complete training program.

  14. Changes of Swimmers’ Emotional States during the Preparation of National Championship: Do Recovery-Stress States Matter?

    Directory of Open Access Journals (Sweden)

    Philippe Vacher

    2017-06-01

    Full Text Available This study examined the trajectories of emotional states and their within-person synergies with perceived stress and recovery during a 4-month training period preceding the French swimming championships. A Multilevel Growth Curve Analysis approach was used with 16 high level swimmers. Five waves of assessments of emotional states, perceived stress and recovery were completed. Results indicated that emotional states were characterized by distinct trajectories during the training period preceding a major competition. Specifically, significant positive linear effects of time (i.e., linear increase over time and negative quadratic effects of squared time (i.e., inverted U shape over time on anxiety, dejection and anger were observed, whereas the opposite pattern of results was found for happiness and excitement. Moreover, level 2 perceived stress and recovery (i.e., inter-individual predictors were significantly associated with athletes’ unpleasant and pleasant emotional states respectively. At level 1, perceived recovery (i.e., intra-individual predictor was positively associated with happiness and excitement and negatively related to anxiety, dejection and anger. Finally, within-person interactions of general stress and recovery with time and squared time reached significance for excitement, whereas within-person interactions of specific and total stress with time and squared time reached significance for anxiety. Overall, this study provided insights into the central role played by perceived stress and recovery on the emotional states experienced by high level swimmers. Operational strategies were suggested in order to optimize the stress-recovery balance and in turn the athletes’ emotional states during a complete training program.

  15. Changes of Swimmers’ Emotional States during the Preparation of National Championship: Do Recovery-Stress States Matter?

    Science.gov (United States)

    Vacher, Philippe; Nicolas, Michel; Martinent, Guillaume; Mourot, Laurent

    2017-01-01

    This study examined the trajectories of emotional states and their within-person synergies with perceived stress and recovery during a 4-month training period preceding the French swimming championships. A Multilevel Growth Curve Analysis approach was used with 16 high level swimmers. Five waves of assessments of emotional states, perceived stress and recovery were completed. Results indicated that emotional states were characterized by distinct trajectories during the training period preceding a major competition. Specifically, significant positive linear effects of time (i.e., linear increase over time) and negative quadratic effects of squared time (i.e., inverted U shape over time) on anxiety, dejection and anger were observed, whereas the opposite pattern of results was found for happiness and excitement. Moreover, level 2 perceived stress and recovery (i.e., inter-individual predictors) were significantly associated with athletes’ unpleasant and pleasant emotional states respectively. At level 1, perceived recovery (i.e., intra-individual predictor) was positively associated with happiness and excitement and negatively related to anxiety, dejection and anger. Finally, within-person interactions of general stress and recovery with time and squared time reached significance for excitement, whereas within-person interactions of specific and total stress with time and squared time reached significance for anxiety. Overall, this study provided insights into the central role played by perceived stress and recovery on the emotional states experienced by high level swimmers. Operational strategies were suggested in order to optimize the stress-recovery balance and in turn the athletes’ emotional states during a complete training program. PMID:28690573

  16. Rating of Stress Factors in Delta State Secondary Schools, Nigeria ...

    African Journals Online (AJOL)

    In terms of school-community relations, schools should identify themselves of their host communities as may be within their reach. Keywords: Human Resources Development, Rating, Stress Factors, Secondary Schools, Nigeria International Journal of Development and Management Review (INJODEMAR) Vol. 7 June ...

  17. Residual stress state in titanium alloy remelted using GTAW method

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2009-04-01

    Full Text Available Test materials comprised two-phase titanium alloy Ti6Al4V (Grade5. The surface of the tested alloy was remelted by means of TIG welding method using variable current-voltage parameters. The investigations aimed to determine surface geometry and residual stresses in the remelted surface layer in the investigated alloy.

  18. Stress state of thin – walled member of the structure with operation damages under nonuniform loading

    Directory of Open Access Journals (Sweden)

    В.В. Астанін

    2004-01-01

    Full Text Available  The publication is dedicated to determining of stress state in particular the stress concentration factors for thin – walled members of the structures subject to nonuniform tension. A structure member has obtained the operation damage generation by corrosion and other causes.

  19. Influence of stress state and strain path on deformation induced martensitic transformations

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Huetink, Han

    2008-01-01

    The mechanically induced transformation behavior of 12Crsingle bond9Nisingle bond 4Mo (ASTM A 564) austenitic stainless steel is investigated in different stress states. This phenomenon is studied experimentally on a plane-stress biaxial test facility. The facility can load a sheet specimen

  20. The equilibrated state of freezing as a basis for distinguishing lethal stresses of freezing in plants

    Science.gov (United States)

    A model for coordination of stresses that limit winterhardiness in plants based on the thermodynamic equilibrated state of freezing and melting provides a rational basis for distinction of freeze-induced energies which can stress and injure living organisms in various ways. The departure from equili...

  1. On stress-state optimization in steel-concrete composite structures

    Science.gov (United States)

    Brauns, J.; Skadins, U.

    2017-10-01

    The plastic resistance of a concrete-filled column commonly is given as a sum of the components and taking into account the effect of confinement. The stress state in a composite column is determined by taking into account the non-linear relationship of modulus of elasticity and Poisson’s ratio on the stress level in the concrete core. The effect of confinement occurs at a high stress level when structural steel acts in tension and concrete in lateral compression. The stress state of a composite beam is determined taking into account non-linear dependence on the position of neutral axis. In order to improve the stress state of a composite element and increase the safety of the construction the appropriate strength of steel and concrete has to be applied. The safety of high-stressed composite structures can be achieved by using high-performance concrete (HPC). In this study stress analysis of the composite column and beam is performed with the purpose of obtaining the maximum load-bearing capacity and enhance the safety of the structure by using components with the appropriate strength and by taking into account the composite action. The effect of HPC on the stress state and load carrying capacity of composite elements is analysed.

  2. On the role of the residual stress state in product manufacturing

    NARCIS (Netherlands)

    Zijlstra, G.; Groen, M.; Post, J.; Ocelik, V.; de Hosson, J.Th.M.

    2016-01-01

    This paper concentrates on the effect of the residual stress state during product manufacturing of AISI 420 steel on the final shape of the product. The work includes Finite Element (FE) calculations of the distribution of the residual stresses after metal forming and a heat treatment. The evolution

  3. The Effects of Stress State on the Strain Hardening Behaviors of TWIP Steel

    Science.gov (United States)

    Liu, F.; Dan, W. J.; Zhang, W. G.

    2017-05-01

    Twinning-Induced Plasticity (TWIP) steels have received great attention due to their excellent mechanical properties as a result of austenite twinning during straining. In this paper, the effects of stress state on the strain hardening behaviors of Fe-20Mn-1.2C TWIP steel were studied. A twinning model considering stress state was presented based on the shear-band framework, and a strain hardening model was proposed by taking dislocation mixture evolution into account. The models were verified by the experimental results of uniaxial tension, simple shear and rolling processes. The strain hardening behaviors of TWIP steel under different stress states were predicted. The results show that the stress state can improve the austenite twining and benefit the strain hardening of TWIP steel.

  4. Shallow Lunar Seismic Activity and the Current Stress State of the Moon

    Science.gov (United States)

    Watters, Thomas R.; Weber, Renee C.; Collins, Geoffrey C.; Johnson, Catherine L.

    2017-01-01

    A vast, global network of more than 3200 lobate thrust fault scarps has been revealed in high resolution Lunar Reconnaissance Orbiter Camera (LROC) images. The fault scarps are very young, less than 50 Ma, based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben and may be actively forming today. The population of young thrust fault scarps provides a window into the recent stress state of the Moon and offers insight into the origin of global lunar stresses. The distribution of orientations of the fault scarps is non-random, inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress. Modeling shows that tidal stresses contribute significantly to the current stress state of the lunar crust. Tidal stresses (orbital recession and diurnal tides) superimposed on stresses from global contraction result in non-isotropic compressional stress and may produce thrust faults consistent with lobate scarp orientations. At any particular point on the lunar surface, peak compressive stress will be reached at a certain time in the diurnal cycle. Coseismic slip events on currently active thrust faults are expected to be triggered when peak stresses are reached. Analysis of the timing of the 28 the shallow moonquakes recorded by the Apollo seismic network shows that 19 indeed occur when the Moon is closer to apogee, while only 9 shallow events occur when the Moon is closer to perigee. Here we report efforts to refine the model for the current stress state of the Moon by investigating the contribution of polar wander. Progress on relocating the epicentral locations of the shallow moonquakes using an algorithm designed for sparse networks is also reported.

  5. Predictors of parenting stress among gay adoptive fathers in the United States.

    Science.gov (United States)

    Tornello, Samantha L; Farr, Rachel H; Patterson, Charlotte J

    2011-08-01

    The authors examined correlates of parenting stress among 230 gay adoptive fathers across the United States through an Internet survey. As with previous research on adoptive parents, results showed that fathers with less social support, older children, and children who were adopted at older ages reported more parenting stress. Moreover, gay fathers who had a less positive gay identity also reported more parenting stress. These 4 variables accounted for 33% of the variance in parenting stress; effect sizes were medium to large. Our results suggest the importance of social support and a positive gay identity in facilitating successful parenting outcomes among gay adoptive fathers.

  6. Wind stress and its dependence on wind speed and sea state

    OpenAIRE

    M. J. Yelland

    1992-01-01

    The aim of the project is to detect and quantify the effect of sea state on the wind stress. An overview of the basic theory of wind stress in the surface layer is provided, along with a more detailed description of the inertial dissipation method which is used to obtain stress estimates for this study. Wind stress measurements by other researchers illustrate the large scatter which seems to be inherent in the drag coefficient/wind speed relationship, and parameterisations of the wave field ...

  7. Coupled Subcritical Water and Solid Phase Extraction for In-Situ Chemical Analysis Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leiden Measurement Technology (LMT) will design and develop a low volume analyte separation, concentration, and transfer system (ConTech), that couples a Subcritical...

  8. Stress state measured at ~7 km depth in the Tarim Basin, NW China.

    Science.gov (United States)

    Sun, Dongsheng; Sone, Hiroki; Lin, Weiren; Cui, Junwen; He, Bizhu; Lv, Haitao; Cao, Zicheng

    2017-07-03

    The in-situ stress state in the Tarim Basin, Northwest China, down to 7 km depth is constrained using the anelastic strain recovery (ASR) method and wellbore failure analysis. Results are consistent between the two methods, and indicate that the maximum principal stresses (σ 1 ) are close to vertical and the intermediate and minimum principal stresses (σ 2 and σ 3 ) are approximately horizontal. The states of stress at the studied wellbore is in the normal faulting stress regime within the Tarim Basin rather than in the compressional tectonic stress regime as in the periphery of the Tarim Basin, which explains the presence of the normal faults interpreted in 3-D seismic profiles collected from adjacent areas. Our results demonstrate that the ASR method can be used for rocks recovered from depths as deep as 7 km to recover reliable stress state information. The in-situ stress measurement results revealed in this paper will help future development of the petroleum resources and kinematics study in the Tarim Basin.

  9. Stress-free states of continuum dislocation fields: Rotations, grain boundaries, and the Nye dislocation density tensor

    OpenAIRE

    Limkumnerd, Surachate; Sethna, James P.

    2006-01-01

    We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose stress fields vanish. We explain that a grain boundary (a dislocation wall satisfying Frank's formula) has vanishing stress in the continuum limit. We show that the general stress-free state can be wri...

  10. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    OpenAIRE

    Peng Hu; Gao-Wei Zhang; Long-Xiang Chen; Ming-Hou Liu

    2017-01-01

    Electrothermal energy storage (ETES) provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analys...

  11. Neuroimaging of resilience to stress: current state of affairs.

    Science.gov (United States)

    van der Werff, Steven J A; Pannekoek, J Nienke; Stein, Dan J; van der Wee, Nic J A

    2013-09-01

    Resilience is defined as a dynamic, multidimensional process encompassing positive adaptation within the context of significant adversity. The complex nature of this construct makes it a difficult topic to study in neuroimaging research; however, in this article, we propose ways to operationalize resilience. The limited amount of structural and functional neuroimaging studies specifically designed to examine resilience have mainly focused on investigating alterations in regions of the brain involved in emotion and stress regulation circuitry. In the future, neuroimaging of resilience is expected to benefit from functional and structural connectivity approaches and the use of novel imaging task paradigms. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Stress drops of induced and tectonic earthquakes in the central United States are indistinguishable.

    Science.gov (United States)

    Huang, Yihe; Ellsworth, William L; Beroza, Gregory C

    2017-08-01

    Induced earthquakes currently pose a significant hazard in the central United States, but there is considerable uncertainty about the severity of their ground motions. We measure stress drops of 39 moderate-magnitude induced and tectonic earthquakes in the central United States and eastern North America. Induced earthquakes, more than half of which are shallower than 5 km, show a comparable median stress drop to tectonic earthquakes in the central United States that are dominantly strike-slip but a lower median stress drop than that of tectonic earthquakes in the eastern North America that are dominantly reverse-faulting. This suggests that ground motion prediction equations developed for tectonic earthquakes can be applied to induced earthquakes if the effects of depth and faulting style are properly considered. Our observation leads to the notion that, similar to tectonic earthquakes, induced earthquakes are driven by tectonic stresses.

  13. Effects of stressful daily events on mood states : Relationship to global perceived stress

    NARCIS (Netherlands)

    van Eck, M; Nicolson, NA; Berkhof, J

    1998-01-01

    This study used experience sampling methodology to examine the relationship between stressful daily events and mood. Eighty-five male white-collar workers completed self-reports 10 times a day for 5 days. Controlling for individual differences in mood levels, multilevel regression analyses showed

  14. A plane stress yield function for anisotropic sheet material by interpolation of biaxial stress states

    NARCIS (Netherlands)

    Vegter, H.; van den Boogaard, Antonius H.

    2006-01-01

    An anisotropic plane stress yield function based on interpolation by second order Bézier curves is proposed. The parameters for the model are readily derived by four mechanical tests: a uniaxial, an equi-biaxial and a plane strain tensile test and a shear test. In case of planar anisotropy, this set

  15. Modelling of the Residual Stress State in a new Type of Residual Stress Specimen

    DEFF Research Database (Denmark)

    Jakobsen, Johnny; Andreasen, Jens Henrik

    2014-01-01

    The paper presents a study on a new type residual stress specimen which is proposed as a simple way to conduct experimental validation for model predictions. A specimen comprising of a steel plate with circular hole embedded into a stack of CSM glass fibre and further infused with an epoxy resin...

  16. Subcritical Water Hydrolysis of Peptides: Amino Acid Side-Chain Modifications

    Science.gov (United States)

    Powell, Thomas; Bowra, Steve; Cooper, Helen J.

    2017-09-01

    Previously we have shown that subcritical water may be used as an alternative to enzymatic digestion in the proteolysis of proteins for bottom-up proteomics. Subcritical water hydrolysis of proteins was shown to result in protein sequence coverages greater than or equal to that obtained following digestion with trypsin; however, the percentage of peptide spectral matches for the samples treated with trypsin were consistently greater than for those treated with subcritical water. This observation suggests that in addition to cleavage of the peptide bond, subcritical water treatment results in other hydrolysis products, possibly due to modifications of amino acid side chains. Here, a model peptide comprising all common amino acid residues (VQSIKCADFLHYMENPTWGR) and two further model peptides (VCFQYMDRGDR and VQSIKADFLHYENPTWGR) were treated with subcritical water with the aim of probing any induced amino acid side-chain modifications. The hydrolysis products were analyzed by direct infusion electrospray tandem mass spectrometry, either collision-induced dissociation or electron transfer dissociation, and liquid chromatography collision-induced dissociation tandem mass spectrometry. The results show preferential oxidation of cysteine to sulfinic and sulfonic acid, and oxidation of methionine. In the absence of cysteine and methionine, oxidation of tryptophan was observed. In addition, water loss from aspartic acid and C-terminal amidation were observed in harsher subcritical water conditions. [Figure not available: see fulltext.

  17. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Science.gov (United States)

    Sinha, Amar; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P. S.; Bishnoi, Saroj

    2015-05-01

    The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated keff of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor ks and external neutron source efficiency φ∗ in great details. Experiments with D-T neutrons are also underway.

  18. Examination stress at unified state examination: student destabilization or success factor?

    Directory of Open Access Journals (Sweden)

    Svetlana N. Kostromina

    2017-01-01

    Full Text Available The aim of the research is to clear up the influence of examination stress on the results of completing examination papers by students in the situation of trial General and Unified State Examinations, imitating the real-life environment of unified state certification of schoolchildren. The tasks of the research included determining the dynamics of psychophysiological stress indices at different examination stages, and evaluating additional factors (the subject in which the examination is held, the strategy of solving the variant, success of solving the task etc., influencing the quantity and quality of stress reactions at the examination.The novelty of the research is in the attempt to overcome the problem of confusing the notions of examination stress and examination anxiety, caused by metering the students’ state either before or after the examination. The technology of online monitoring the students’ psychophysiological state is used in the work, which makes it possible to eliminate a number of restrictions occurring during subjective evaluation of the state by the students themselves. Telemetric cardiorhythmography was chosen as the basic method. The method is based on a three-component model of extreme states with consequent domination of one of the three stress-reactive systems. A cardiointervalogramm was being registered in the research process in the online mode and underwent spectral analysis. The following indices of heart rate variability were recorded in order to determine stress reactions: the total power of the spectrum (TP, the spectrum power in low-frequency (LF and high-frequency (HF regions, and a vegetative balance index (relation of the spectrum powers in low-frequency and high-frequency regions (LF/HF. When the total power of the heart rate fell and, at the same time, the vegetative balance index rose, a conclusion was made of there being a stress reaction. Twenty-five students of an illustrious school were examined

  19. Occupational Stress and Management Strategies of Secondary School Principals in Cross River State, Nigeria

    Science.gov (United States)

    Anyanwu, Joy; Ezenwaji, Ifeyinwa; Okenjom, Godian; Enyi, Chinwe

    2015-01-01

    The study aimed at finding out sources and symptoms of occupational stress and management strategies of principals in secondary schools in Cross River State, Nigeria. Descriptive survey research design was adopted for the study with a population of 420 principals (304 males and 116 females) in secondary schools in Cross River State, Nigeria. Three…

  20. Computer modeling of the stress-strain state of welded construction

    Science.gov (United States)

    Nurguzhin, Marat; Danenova, Gulmira; Akhmetzhanov, Talgat

    2017-11-01

    At the present time the maintenance of the welded construction serviceability over normative service life is provided by the maintenance system on the basis of the guiding documents according to the concept of "fail safe". However, technology factors relating to welding such as high residual stresses and significant plastic strains are not considered in the guiding documents. The design procedure of the stressed-strained state of welded constructions is suggested in the paper. The procedure investigates welded constructions during welding and the external load using the program ANSYS. In this paper, the model of influence of the residual stress strain state on the factor of stress intensity is proposed. The calculation method of the residual stressed-strained state (SSS) taking into account the phase transition is developed by the authors. Melting and hardening of a plate material during heating and cooling is considered. The thermomechanical problem of heating a plate by a stationary heat source is solved. The setup of the heating spot center on distance (190 mm) from the crack top in a direction of its propagation leads to the fact that the value of total factor of stress intensity will considerably decrease under action of the specified residual compressing stresses. It can lower the speed of the crack propagation to zero. The suggested method of survivability maintenance can be applied during operation with the purpose of increasing the service life of metal constructions up to running repair of technological machines.

  1. Relationship Between Organizational Climate, Job Stress And Job Performance Officer At State Education Department

    Directory of Open Access Journals (Sweden)

    Turiman Suandi

    2014-01-01

    Full Text Available This research aims at finding out the relationship between Organizational Climate, job stress and job performance among State Education Department (JPN officers . The focus of the research is to determeane the job performance of state education department officers, level of job stress among the officers, level of connection between organizational climate with job stress of State Education Department officers, looking at the difference in level of performance according to demographic factors and looking at the influence of organizational climate and job stress towards job performance . Research findings pertaining level of job performance showed that 75.8% of the respondents are at a high level, 23.7% respondents are at a moderate level while 0.5% respondents are at a low level. For organizational climate, findings show that 79.0% respondents are in the moderate level, 1.6 % respondents are at a highlevel and 19.4% respondents are at a low level. Findings on overall level of job stress found that as many as 92.5% respondents are at a normal job stress. Only about 7.5% respondents are at a moderate level of job stress. There is not even one respondent who are facing a high level of job stress.  In terms of the relationship between independent variables (organizational climate, job stress and dependent variable (job performance, the research findings show that there is a moderate level of positive relationship which is quite significant between organizational climate and job performance of the State Education Department officers at α = 0.01 (p < 0.01; r = 0.396.

  2. Natural fiber composite design and characterization for limit stress prediction in multiaxial stress state

    Directory of Open Access Journals (Sweden)

    Christopher C. Ihueze

    2015-07-01

    Full Text Available This paper focuses on the design of natural fiber composites and analysis of multiaxial stresses in relation to yield limit stresses of composites loaded off the fibers axis. ASTM D638-10 standard for tensile test was used to design and compose composites of plantain fiber reinforced polyester (PFRP. While the rule of mixtures was used in the evaluation of properties of composites in the fiber direction the evaluation of properties perpendicular or transverse to the fiber direction was done based on the value of the orthogonal stresses evaluated using ANSYS finite element software, the application of the Brintrup equation and Halpin–Tai equation. The yield strength for the plantain empty fruit bunch fiber reinforced polyester resin (PEFBFRP was estimated as 33.69 MPa while the yield strength of plantain pseudo stem fiber reinforced polyester resin (PPSFRP was estimated as 29.24 MPa. Above all, the PEFBFRP with average light absorbance peak of 45.47 was found to have better mechanical properties than the PPSFRP with average light absorbance peak of 45.77.

  3. Development study on subcriticality monitor. 1. Report under business contract with Japan Nuclear Fuel Cycle Development Institute

    CERN Document Server

    Yamada, S

    2002-01-01

    In this trust fund, we reviewed subcriticality measuring methods and neutron or gamma ray measuring and date transmission systems appropriate for realizing inexpensive on-line criticality surveillance systems, which is required for ensuring the safety of nuclear fuel reprocessing plants. Since the neutron flux level in subcritical systems is fairly low without external neutron sources, it is desirable to use pulse type neutron detectors for subcritical measurement systems. This logically implies that subcriticality measurement methods based on the temporal domain should be used for developing an on-line criticality surveillance system. In the deep subcriticality conditions, a strong external neutron source is needed for eactivity measurement and a D-T tube can be used in order to improve the accuracy of the measurement. A D-T tube is convenient since it is free from Tritium problem since Tritium is sealed in an airtight container and also can be controlled by power supply. Hence, under deep subcritical condit...

  4. Subcritical hydrothermal conversion of organic wastes and biomass. Reaction pathways

    Directory of Open Access Journals (Sweden)

    Alejandro Amadeus Castro Vega

    2010-04-01

    Full Text Available Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requi- res previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added- value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary tralectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

  5. Effect of fluid salinity on subcritical crack propagation in calcite

    Science.gov (United States)

    Rostom, Fatma; Røyne, Anja; Dysthe, Dag Kristian; Renard, François

    2013-01-01

    The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing responsible for a ductile deformation of rocks under crustal conditions. In the present study, the double-torsion technique was used to measure the effect of fluid chemistry on the slow propagation of cracks in calcite single crystals at room temperature. Time-lapse images and measurements of force and load-point displacement allowed accurate characterization of crack velocities in a range of 10- 8 to 10- 4 m/s. Velocity curves as a function of energy-release rates were obtained for different fluid compositions, varying NH4Cl and NaCl concentrations. Our results show the presence of a threshold in fluid composition, separating two regimes: weakening conditions where the crack propagation is favored, and strengthening conditions where crack propagation slows down. We suggest that electrostatic surface forces that modify the repulsion forces between the two surfaces of the crack may be responsible for this behavior.

  6. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Qin, Guangyong

    2017-03-30

    As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE) technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  7. The Chain-Length Distribution in Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Texas A & M Univ., College Station, TX (United States)

    2000-06-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.

  8. Catalytic upgrading of duckweed biocrude in subcritical water.

    Science.gov (United States)

    Zhang, Caicai; Duan, Peigao; Xu, Yuping; Wang, Bing; Wang, Feng; Zhang, Lei

    2014-08-01

    Herein, a duckweed biocrude produced from the hydrothermal liquefaction of Lemna minor was treated in subcritical water with added H₂. Effects of several different commercially available materials such as Ru/C, Pd/C, Pt/C, Pt/γ-Al₂O₃, Pt/C-sulfide, Rh/γ-Al₂O₃, activated carbon, MoS₂, Mo₂C, Co-Mo/γ-Al₂O₃, and zeolite on the yields of product fractions and the deoxygenation, denitrogenation, and desulfurization of biocrude at 350°C were examined, respectively. All the materials showed catalytic activity for deoxygenation and desulfurization of the biocrude and only Ru/C showed activity for denitrogenation. Of those catalysts examined, Pt/C showed the best performance for deoxygenation. Among all the upgraded oils, the oil produced with Ru/C shows the lowest sulfur, the highest hydrocarbon content (25.6%), the highest energy recovery (85.5%), and the highest higher heating value (42.6 MJ/kg). The gaseous products were mainly unreacted H₂, CH₄, CO₂, and C₂H6. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Reynolds number effect on VIV: from subcritical to supercritical flow

    Energy Technology Data Exchange (ETDEWEB)

    Triantafyllou, M.S.; Hover, F.S.; Techet, A.H. [Massachusetts Inst. of Tech., Dept. of Ocean Engineering, Cambridge, MA (United States)

    2004-07-01

    Vortex Induced Vibrations in flexibly supported rigid cylinders and long, flexible slender structures, such as cables and risers, are caused by the formation of large-scale vortices, whose dynamics are controlled to a large extend by inviscid mechanisms. Reynolds number remains a very important parameter, however, because it influences the formation and shedding mechanisms of the vortical patterns. For low Reynolds numbers, below a few thousand, a nearly complete understanding has been obtained in recent years, at least for flexibly mounted rigid cylinders. This is not the case, though, for VIV above Re=10,000 and - especially - above the critical Reynolds number of about Re=250,000 for smooth cylinders. The talk provides observed WV trends of flexibly mounted cylinders, obtained in recent experiments as function of the Reynolds number, from Re about 1,000 up to 1,000,000. In particular, similarities and differences between subcritical and supercritical force and motion data will be discussed, and conclusions on the governing principal mechanisms will be drawn, including transitions in the arrangement of vortical patterns and effects of correlation length. (authors)

  10. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea

    Directory of Open Access Journals (Sweden)

    Yating Zhang

    2017-03-01

    Full Text Available As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  11. Enhanced Capabilities for Subcritical Experiments (ECSE) Risk Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Mary Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Process Modeling and Analysis Group

    2016-05-02

    Risk is a factor, element, constraint, or course of action that introduces an uncertainty of outcome that could impact project objectives. Risk is an inherent part of all activities, whether the activity is simple and small, or large and complex. Risk management is a process that identifies, evaluates, handles, and monitors risks that have the potential to affect project success. The risk management process spans the entire project, from its initiation to its successful completion and closeout, including both technical and programmatic (non-technical) risks. This Risk Management Plan (RMP) defines the process to be used for identifying, evaluating, handling, and monitoring risks as part of the overall management of the Enhanced Capabilities for Subcritical Experiments (ECSE) ‘Project’. Given the changing nature of the project environment, risk management is essentially an ongoing and iterative process, which applies the best efforts of a knowledgeable project staff to a suite of focused and prioritized concerns. The risk management process itself must be continually applied throughout the project life cycle. This document was prepared in accordance with DOE O 413.3B, Program and Project Management for the Acquisition of Capital Assets, its associated guide for risk management DOE G 413.3-7, Risk Management Guide, and LANL ADPM AP-350-204, Risk and Opportunity Management.

  12. Effect of axiallity of stress state on hydrogen cracking kinetics in metals -- Troiano revisited

    Energy Technology Data Exchange (ETDEWEB)

    Timmins, P. [IESCO, San Pedro, CA (United States)

    1996-10-01

    An experimental study based on the acoustic emission technique was carried out to examine how the axiallity of the stress state, as first postulated by Troiano, influenced the hydrogen cracking kinetics, in terms of delayed hydride cracking (DHC) propagation, using constant K specimens machined from Zr-2.5 wt% Nb pressure tube alloy, of 2 mm, 4 mm and 8 mm thickness. By changing the stress state from plane strain to plane stress at a constant applied stress intensity of 15 MPa{radical}m and a hydrogen level of 50 ppm, the DHC velocity was reduced, in keeping with Troiano`s hypothesis. An explanation of how the observations made on these specimens can be related to other hydrogen cracking mechanisms, is presented.

  13. Stress-Stain State of Pipe Made of Copper-Based Alloy Strengthened with Incoherent Nanoparticles

    Science.gov (United States)

    Matvienko, O. V.; Daneyko, O. I.; Kovalevskaya, T. A.

    2017-08-01

    The approach which combines methods of crystal plasticity and deformable solid mechanics is used to explore the stress-strain state of a heavy-wall pipe made of dispersion-hardened Cu-based alloy and subjected to the uniform internal pressure. The distribution of the deformation and stress along the pipe wall is determined for various pipe geometry. The approximating equations are obtained to determine the yielding area and elastic and plastic strength limits.

  14. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Amar, E-mail: image@barc.gov.in; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P.S.; Bishnoi, Saroj

    2015-05-01

    Highlights: •Experimental subcritical facility BRAHMMA coupled to D-D/D-T neutron generator. •Preliminary results of PNS experiments reported. •Feynman-alpha noise measurements explored with continuous source. -- Abstract: The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated k{sub eff} of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k{sub s} and external neutron source efficiency φ{sup ∗} in great details. Experiments with D-T neutrons are also underway.

  15. Research Results Of Stress-Strain State Of Cutting Tool When Aviation Materials Turning

    Science.gov (United States)

    Serebrennikova, A. G.; Nikolaeva, E. P.; Savilov, A. V.; Timofeev, S. A.; Pyatykh, A. S.

    2018-01-01

    Titanium alloys and stainless steels are hard-to-machine of all the machining types. Cutting edge state of turning tool after machining titanium and high-strength aluminium alloys and corrosion-resistant high-alloy steel has been studied. Cutting forces and chip contact arears with the rake surface of cutter has been measured. The relationship of cutting forces and residual stresses are shown. Cutting forces and residual stresses vs value of cutting tool rake angle relation were obtained. Measurements of residual stresses were performed by x-ray diffraction.

  16. Effect of severe environmental thermal stress on redox state in salmon

    Directory of Open Access Journals (Sweden)

    Toshiki Nakano

    2014-01-01

    Full Text Available Fish are exposed to many kinds of environmental stressors and the chances of succumbing to infectious diseases may be increased a result. For example, an acute increase in temperature can induce numerous physiological changes in the body. In the present study, we examined the redox state in response to a severe acute stress resulting from heat shock in teleost coho salmon (Oncorhynchus kisutch. The plasma lipid peroxides levels in fish gradually increased after heat shock treatment. By 2.5 h post-heat stress, plasma glutathione (GSH levels had decreased, but they had returned to basal levels by 17.5 h post-stress. Plasma superoxide dismutase activities in stressed fish were significantly increased compared with those in control fish at 17.5 h post-stress, but had returned to basal levels by 48 h post-stress. Expression levels of hepatic GSH and heat shock protein 70 gradually increased after heat shock treatment. These results concerning the changing patterns of multiple important redox-related biomarkers suggest that severe thermal stressors can affect the redox state and induce oxidative stress in ectothermal animals, such as fish, in vivo. Hence, manipulation of appropriate thermal treatment may possibly be useful to control fish fitness.

  17. Residual stress state in pipe cut ring specimens for fracture toughness testing

    Energy Technology Data Exchange (ETDEWEB)

    Damjanovic, Darko [J.J. Strossmayer Univ. of Osijek, Slavonski Brod (Croatia). Mechanical Engineering Faculty; Kozak, Drazan [Zagreb Univ. (Croatia). Dept. for Mechanical Design; Marsoner, Stefan [Materials Center, Leoben (Austria).; Gubeljak, Nenad [Maribor Univ. (Slovenia). Chair of Mechanics

    2017-07-01

    Thin-walled pipes are not suitable for measuring fracture toughness parameters of vital importance because longitudinal crack failure is the most common failure mode in pipes. This is due to the impossibility to manufacture standard specimens for measuring fracture toughness, such as SENB or CT specimens, from the thin wall of the pipe. Previous works noticed this problem, but until now, a good and convenient solution has not been found or developed. To overcome this problem, very good alternative solution was proposed, the so-called pipe ring notched bend specimen (PRNB) [1-5]. Until now, only the idealized geometry PRNB specimen is analyzed, i. e., a specimen which is not cut out from an actual pipe but produced from steel plate. Based on that, residual stresses are neglected along with the imperfections in geometry (elliptical and eccentricity). The aim of this research is to estimate the residual stress state(s) in real pipes used in the boiler industry produced by hot rolling technique. These types of pipes are delivered only in normalized condition, but not stress relieved. Therefore, there are residual stresses present due to the manufacturing technique, but also due to uneven cooling after the production process. Within this paper, residual stresses are estimated by three methods: the incremental hole drilling method (IHMD), X-ray diffraction (XRD) and the splitting method (SM). Knowing the residual stress state in the ring specimen, it is possible to assess their impact on fracture toughness measured on the corresponding PRNB specimen(s).

  18. CFD Analysis and Design of Detailed Target Configurations for an Accelerator-Driven Subcritical System

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Adam; Merzari, Elia; Sofu, Tanju; Zhong, Zhaopeng; Gohar, Yousry

    2016-08-01

    High-fidelity analysis has been utilized in the design of beam target options for an accelerator driven subcritical system. Designs featuring stacks of plates with square cross section have been investigated for both tungsten and uranium target materials. The presented work includes the first thermal-hydraulic simulations of the full, detailed target geometry. The innovative target cooling manifold design features many regions with complex flow features, including 90 bends and merging jets, which necessitate three-dimensional fluid simulations. These were performed using the commercial computational fluid dynamics code STAR-CCM+. Conjugate heat transfer was modeled between the plates, cladding, manifold structure, and fluid. Steady-state simulations were performed but lacked good residual convergence. Unsteady simulations were then performed, which converged well and demonstrated that flow instability existed in the lower portion of the manifold. It was established that the flow instability had little effect on the peak plate temperatures, which were well below the melting point. The estimated plate surface temperatures and target region pressure were shown to provide sufficient margin to subcooled boiling for standard operating conditions. This demonstrated the safety of both potential target configurations during normal operation.

  19. The study on stress-strain state of the spring at high temperature using ABAQUS

    Directory of Open Access Journals (Sweden)

    H Sun

    2014-01-01

    Full Text Available Cylindrical helical springs are widely used in the elements of thermal energy devices. It is necessary to guarantee the stability of the stress state of spring in high temperature. Relaxation phenomenon of stress is studied in this paper. Calculations are carried out in the environment of ABAQUS. The verification is taken out using analytical calculations.This paper describes the distribution and character of stress contour lines on the cross section of spring under the condition of instantaneous load, explicates the relaxation law with time. Research object is cylindrical helical spring, that working at high temperature. The purpose of this work is to get the stress relaxation law of spring, and to guarantee the long-term strength.This article presents the basic theory of helical spring. Establishes spring mathematical model of creep under the loads of compression and torsion. The stress formulas of each component in the cross section of spring are given. The calculation process of relaxation is analyzed in the program ABAQUS.In this paper compare the analytical formulas of spring stress with the simulation results, which are created by program ABAQUS.Finite element model for stress creep analysis in the cross section is created, material of spring – stainless steel 10X18N9T, springs are used at the temperature 650℃.At the beginning, stress-stain of spring is in the elastic state. Analyzes the change law of creep stress under the condition of constant load and a fixed compression.When analyzing under the condition of a fixed compression, the stresses are quickly decreased in most area in the cross section of spring, and the point of minimum shear stress gradually moves to the direction of outer diameter, because of this, stresses in a small area near the center increase slowly at first then decrease gradually with time. When analyzing under the condition of constant load, the stresses are quickly decreased in the around area and in creased

  20. The influence of normal fault on initial state of stress in rock mass

    Directory of Open Access Journals (Sweden)

    Tajduś Antoni

    2016-03-01

    Full Text Available Determination of original state of stress in rock mass is a very difficult task for rock mechanics. Yet, original state of stress in rock mass has fundamental influence on secondary state of stress, which occurs in the vicinity of mining headings. This, in turn, is the cause of the occurrence of a number of mining hazards, i.e., seismic events, rock bursts, gas and rock outbursts, falls of roof. From experience, it is known that original state of stress depends a lot on tectonic disturbances, i.e., faults and folds. In the area of faults, a great number of seismic events occur, often of high energies. These seismic events, in many cases, are the cause of rock bursts and damage to the constructions located inside the rock mass and on the surface of the ground. To estimate the influence of fault existence on the disturbance of original state of stress in rock mass, numerical calculations were done by means of Finite Element Method. In the calculations, it was tried to determine the influence of different factors on state of stress, which occurs in the vicinity of a normal fault, i.e., the influence of normal fault inclination, deformability of rock mass, values of friction coefficient on the fault contact. Critical value of friction coefficient was also determined, when mutual dislocation of rock mass part separated by a fault is impossible. The obtained results enabled formulation of a number of conclusions, which are important in the context of seismic events and rock bursts in the area of faults.

  1. The influence of normal fault on initial state of stress in rock mass

    Science.gov (United States)

    Tajduś, Antoni; Cała, Marek; Tajduś, Krzysztof

    2016-03-01

    Determination of original state of stress in rock mass is a very difficult task for rock mechanics. Yet, original state of stress in rock mass has fundamental influence on secondary state of stress, which occurs in the vicinity of mining headings. This, in turn, is the cause of the occurrence of a number of mining hazards, i.e., seismic events, rock bursts, gas and rock outbursts, falls of roof. From experience, it is known that original state of stress depends a lot on tectonic disturbances, i.e., faults and folds. In the area of faults, a great number of seismic events occur, often of high energies. These seismic events, in many cases, are the cause of rock bursts and damage to the constructions located inside the rock mass and on the surface of the ground. To estimate the influence of fault existence on the disturbance of original state of stress in rock mass, numerical calculations were done by means of Finite Element Method. In the calculations, it was tried to determine the influence of different factors on state of stress, which occurs in the vicinity of a normal fault, i.e., the influence of normal fault inclination, deformability of rock mass, values of friction coefficient on the fault contact. Critical value of friction coefficient was also determined, when mutual dislocation of rock mass part separated by a fault is impossible. The obtained results enabled formulation of a number of conclusions, which are important in the context of seismic events and rock bursts in the area of faults.

  2. EXPERIMENTAL SETUP FOR MODELING AND STUDY OF COMPLEX STRESS STATE IN FERROMAGNETIC MATERIALS

    Directory of Open Access Journals (Sweden)

    V. N. Busko

    2016-01-01

    Full Text Available Most of the load experiencing parts operate in a complex state of stress (СSS. The article describes the device layout diagram for modeling a СSS in a ferromagnetic material and the development of monitoring methods. The principle of operation of the device is based on the joint action at a sample of longitudinal extension and lateral bending. The article describes the methods of creating a СSS and materials research using the method of the Barkhausen effect in static and dynamic loading conditions. The article presents the functioning of the algorithm and device operating principle. The article also shows the diagram for modeling a СSS in a steel sample. In this work, are the construction and operation of the device described in detail. This device differs from simple industrial test equipment by small weight, size and cost. The paper presents experimental examples of the influence of the simple forms of the state of stress (longitudinal stretching or lateral bending and a CSS on the intensity of the magnetic noise in two samples of structural steel. The study established that the total value of the magnetic noise in complex stress state of the sample caused by the forces of simultaneously stretching and bending load, is approximately equal to the algebraic sum of magnetic noise values for each simple type of stress. The linearity of the intensity of the magnetic noise versus axial tensile stress is observed in a range of 0 to ≈ +300 MPa, flexural tensile stresses – of 0 to ≈ +500 MPa, the total stresses – to ≈ 100–110 MPa. The obtained results confirmed the efficiency and effectiveness of the device. The article shows that the magnetic noise is affected not only by the magnitude of the tensile stress of the axial force or tensile stresses in bending or full stresses, but also by the steel grade, the physical and mechanical properties of the material under test. The sensitivity of the magnetic noise to the combined action of the

  3. Software for determining the direction of movement, shear and normal stresses of a fault under a determined stress state

    Science.gov (United States)

    Álvarez del Castillo, Alejandra; Alaniz-Álvarez, Susana Alicia; Nieto-Samaniego, Angel Francisco; Xu, Shunshan; Ochoa-González, Gil Humberto; Velasquillo-Martínez, Luis Germán

    2017-07-01

    In the oil, gas and geothermal industry, the extraction or the input of fluids induces changes in the stress field of the reservoir, if the in-situ stress state of a fault plane is sufficiently disturbed, a fault may slip and can trigger fluid leakage or the reservoir might fracture and become damaged. The goal of the SSLIPO 1.0 software is to obtain data that can reduce the risk of affecting the stability of wellbores. The input data are the magnitudes of the three principal stresses and their orientation in geographic coordinates. The output data are the slip direction of a fracture in geographic coordinates, and its normal (σn) and shear (τ) stresses resolved on a single or multiple fracture planes. With this information, it is possible to calculate the slip tendency (τ/σn) and the propensity to open a fracture that is inversely proportional to σn. This software could analyze any compressional stress system, even non-Andersonian. An example is given from an oilfield in southern Mexico, in a region that contains fractures formed in three events of deformation. In the example SSLIPO 1.0 was used to determine in which deformation event the oil migrated. SSLIPO 1.0 is an open code application developed in MATLAB. The URL to obtain the source code and to download SSLIPO 1.0 are: http://www.geociencias.unam.mx/ alaniz/main_code.txt, http://www.geociencias.unam.mx/ alaniz/ SSLIPO_pkg.exe.

  4. Under Stress: Europeanisation and Trade Associations in the Members States

    Directory of Open Access Journals (Sweden)

    Dirk Lehmkuhl

    2000-11-01

    Full Text Available Until today, it is relatively disputed how European integration impacts on domestic associations and the patterns of public-private interactions at the national level. While some predict a withering away of national corporatisms, others predict they would be reinforced. By making organization theory available to institution-theoretical approaches, the paper offers a conceptual means that makes it possible to present an encompassing and theory-guided picture of the impact of European integration on societal structures in the member states. Associations - in the presented cases, business associations of the transport sector in Germany and the Netherlands -, as intermediate organisations operate at the interface between private and public actors and incorporate the dynamics of their political and economic environments in both structural and strategic terms. It is argued that the way in which the configuration of associations within a sector changes in the course of European integration relates to efforts at this intermediate level to maintain or increase its relative autonomy from both its constituencies and its interlocutors.

  5. High power ring methods and accelerator driven subcritical reactor application

    Energy Technology Data Exchange (ETDEWEB)

    Tahar, Malek Haj [Univ. of Grenoble (France)

    2016-08-07

    High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g., PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field imperfections on the

  6. Frequency of positive states of mind as a moderator of the effects of stress on psychological functioning and perceived health.

    Science.gov (United States)

    Bränström, Richard

    2013-01-01

    Emerging evidence indicates that individuals reporting more positive affect are healthier and live longer. The aim of this study was to examine if positive states of mind moderates the effect of perceived stress on psychological functioning and perceived health. A cross-sectional sample, n = 382, responded to questions regarding perceived stress, depression, anxiety, perceived health, and frequency of positive states of mind. Using a series of regression analyses, the results confirmed a moderating role of positive states of mind on the association between perceived stress and psychological outcomes. Among people experiencing a high frequency of positive states of mind, perceived stress seems to have a low correspondence with depression, anxiety, and perceived health. But among those reporting a low frequency of positive states of mind, perceived stress was more strongly related and depression, anxiety, and perceived health suggesting a buffering effect of positive states of mind against the negative influence of stress.

  7. Solubility of Benzo[a]pyrene and Organic Matter of Soil in Subcritical Water

    Directory of Open Access Journals (Sweden)

    Svetlana Sushkova

    2015-12-01

    Full Text Available A dynamic subcritical water extraction method of benzo[a]pyrene from soils is under consideration. The optimum conditions for benzo[a]pyrene extraction from soil are described including the soil treatment by subcritical water at 250 °C and 100 atm for 30 min. The effectiveness of developed method was determined using the matrix spiking recovery technique. A comparative analysis was made to evaluate the results of benzo[a]pyrene extraction from soils using the subcritical water and organic solvents. The advantages of the subcritical water extraction involve the use of ecologically friendly solvent, a shorter time for the analysis and a higher amount of benzo[a]pyrene extracted from soil (96 %. The influence of subcritical water extraction on soil properties was measured the investigation of the processes occurring within soil under the influence the high temperature and pressure. Under appropriate conditions of the experiment there is the destruction of the soil organic matter while the composition of the soil mineral fraction remains practically unchanged.

  8. Subcritical water extraction of flavoring and phenolic compounds from cinnamon bark (Cinnamomum zeylanicum).

    Science.gov (United States)

    Khuwijitjaru, Pramote; Sayputikasikorn, Nucha; Samuhasaneetoo, Suched; Penroj, Parinda; Siriwongwilaichat, Prasong; Adachi, Shuji

    2012-01-01

    Cinnamon bark (Cinnamomum zeylanicum) powder was treated with subcritical water at 150 and 200°C in a semi-continuous system at a constant flow rate (3 mL/min) and pressure (6 MPa). Major flavoring compounds, i.e., cinnamaldehyde, cinnamic acid, cinnamyl alcohol and coumarin, were extracted at lower recoveries than the extraction using methanol, suggesting that degradation of these components might occur during the subcritical water treatment. Caffeic, ferulic, p-coumaric, protocatechuic and vanillic acids were identified from the subcritical water treatment. Extraction using subcritical water was more effective to obtain these acids than methanol (50% v/v) in both number of components and recovery, especially at 200°C. Subcritical water treatment at 200°C also resulted in a higher total phenolic content and DPPH radical scavenging activity than the methanol extraction. The DPPH radical scavenging activity and total phenolic content linearly correlated but the results suggested that the extraction at 200°C might result in other products that possessed a free radical scavenging activity other than the phenolic compounds.

  9. Effect of water on critical and subcritical fracture properties of Woodford shale

    Science.gov (United States)

    Chen, Xiaofeng; Eichhubl, Peter; Olson, Jon E.

    2017-04-01

    Subcritical fracture behavior of shales under aqueous conditions is poorly characterized despite increased relevance to oil and gas resource development and seal integrity in waste disposal and subsurface carbon sequestration. We measured subcritical fracture properties of Woodford shale in ambient air, dry CO2 gas, and deionized water by using the double-torsion method. Compared to tests in ambient air, the presence of water reduces fracture toughness by 50%, subcritical index by 77%, and shear modulus by 27% and increases inelastic deformation. Comparison between test specimens coated with a hydrophobic agent and uncoated specimens demonstrates that the interaction of water with the bulk rock results in the reduction of fracture toughness and enhanced plastic effects, while water-rock interaction limited to the vicinity of the propagating fracture tip by a hydrophobic specimen coating lowers subcritical index and increases fracture velocity. The observed deviation of a rate-dependent subcritical index from the power law K-V relations for coated specimens tested in water is attributed to a time-dependent weakening process resulting from the interaction between water and clays in the vicinity of the fracture tip.

  10. Characterization of the Subcritical Water Extraction of Fluoxetine-Hydrochloride.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B; Lambertus, Gordon; Jensen, Eric

    2012-08-10

    The characteristics of using Subcritical Water Extraction (SWE) to recover Fluoxetine-Hydrochloride from both standard solutions and the contents of commercial capsule formulations were investigated. Analysis of solutions and extracts was done by HPLC with UV detection at 254 nm. Standard solutions of Fluoxetine-Hydrochloride were exposed to a variety of SWE operating conditions, including temperatures from 125 to 275°C and periods ranging from 5 to 30 min. Fluoxetine-Hydrochloride could be quantitatively recovered from standard solutions (1.0mg/mL) that were heated up to 175°C for 30 min, up to 200°C for 15 min, or up to 225°C for 10 min. At higher temperatures and/or times, Fluoxetine-Hydrochloride recoveries were generally incomplete and often produced decomposition by-products during the process. By comparison, the concentration of Fluoxetine-Hydrochloride in the standard solution had relatively little effect on recovery. Considering these parameters, an SWE method was developed to extract Fluoxetine-Hydrochloride from the contents of Prozac(®) capsules. It was found that Fluoxetine-Hydrochloride could be quantitatively extracted from the capsule contents in 8 min at a temperature of 200°C using 3.5 mL of water as the extraction solvent. Gelatinization of the starch excipient in the capsule contents was also observed to occur temporarily during the capsule extractions, before ultimately disappearing again. The period of this phenomenon was dependent on both temperature and sample size. The results indicate that SWE can be a very useful method for Fluoxetine-Hydrochloride extraction and suggest that it may be interesting to explore other pharmaceuticals using this method as well. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Stress

    Science.gov (United States)

    ... natural disaster. This type of stress can cause post-traumatic stress disorder (PTSD). Different people may feel stress in different ways. Some people experience digestive symptoms. Others may have headaches, sleeplessness, depressed mood, anger, ...

  12. Influence of peak oral temperatures on veneer–core interface stress state

    Directory of Open Access Journals (Sweden)

    Massimo Marrelli

    2015-01-01

    Full Text Available Objective: There is a growing interest for the use of Y-TZP zirconia as core material in veneered all-ceramic prostheses. The objective of this study was to evaluate the influence of CET on the stress distribution of a porcelain layered to zirconia core single crowns by finite elements analysis. Material and methods: CET of eight different porcelains was considered during the analysis. Results: Results of this study indicated that the mismatch in CET between the veneering porcelain and the Y-TZP zirconia core has to be minimum (0.5–1 μm/mK so as to decrease the growing of residual stresses which could bring chipping. Conclusions: The stress state due to temperature variation should be carefully taken into consideration while studying the effect of mechanical load on zirconia core crown by FEA. The interfacial stress state can be increased by temperature variation up to 20% with respect to the relative failure parameter (interface strength in this case. This means that stress due to mechanical load combined to temperature variation-induced stress can lead porcelain veneer–zirconia core interfaces to failure.

  13. Thermo-stressed state of a wear resistante layer during the electrocontact surfacing

    Directory of Open Access Journals (Sweden)

    Олена Валеріївна Бережна

    2016-11-01

    Full Text Available The mathematical model of the thermo-stressed state of a wear resistant layer at electrocontact surfacing with wire has been developed. The mathematical model has been made up on the base of the slip lines fields method that takes into account the two-dimensional character of the plastic forming in the sections of the thermodeformation area. The mathematical model makes it possible to predict the physical and mechanical properties of the deposited layer as well as the forming character of the layer. The temperature distribution in the deposited layer in the thermodeformation area has been investigated. The qualitative and quantitative impact of the heating temperature of the deposited layer on the stresses and deformations distribution along the thermodeformation zone has been investigated. This made it possible to determine more accurately the material mechanical properties changes and the levels of the stressed and deformed state during the electrocontact surfacing process. So the real nature of the stresses distribution at the displacement of the material was described, which allows to determine the changes of the stress and strain state levels in the process. The results of the proposed mathematical models allow to choose optimal modes of heating and deforming the wire in order to obtain a high quality joint of the base material and the deposited layer at electrocontact surfacing and to prevent such defects as lack of fusion that result in low adhesion strength of the joint

  14. Modeling of the stress-strain state of the ground mass contaminated with peracetic acid

    Directory of Open Access Journals (Sweden)

    Levenko Anna

    2017-01-01

    Full Text Available None of the methods described previously provides a solution to the problem that deals with the SSS evaluation of the ground mass which is under the influence of chemically active substances and, in particular, under the influence of peracetic acid. The stress-strain state of the ground mass contaminated with peracetic acid was estimated. Stresses occurring in the ground mass in the natural state were determined after the entry of acid into it and after the chemical fixation of it with sodium silicate. All the parameters of the stress-strain state of the ground mass were obtained under a number of physical and mechanical conditions. It was determined that following the work on the silicatization of the ground mass contaminated with peracetic acid the quantity of strain decreased by 26.11 to 48.9%. The comparison of the results of stress calculations indicates the stress reduction in the ground mass in 1.8 – 2.6 times after its fixing.

  15. The study of stress-strain state of stabilized layered soil foundations

    Directory of Open Access Journals (Sweden)

    Sokolov Mikhail V.

    2017-01-01

    Full Text Available Herein presented are the results of modeling and analysis of stress-strain state of layered inhomogeneous foundation soil when it is stabilised by injection to different depths. Produced qualitative and quantitative analysis of the components of the field of isolines of stresses, strains, stress concentration and the difference between the strain at the boundary of different elastic horizontal layers. Recommendations are given for the location of stabilised zones in relation to the border of different elastic layers. In particular, it found that stabilization of soil within the weak layer is inappropriate, since it practically provides no increase in the stability of the soil foundation, and when performing stabilisation of soil foundations, it is recommended to place the lower border of the stabilisation zone below the border of a stronger layer, at this the distribution of stresses and strains occurs more evenly, and load-bearing capacity of this layer is used to the maximum.

  16. Steady thermal stress and strain rates in a rotating circular cylinder under steady state temperature

    Directory of Open Access Journals (Sweden)

    Pankaj Thakur

    2014-01-01

    Full Text Available Thermal stress and strain rates in a thick walled rotating cylinder under steady state temperature has been derived by using Seth’s transition theory. For elastic-plastic stage, it is seen that with the increase of temperature, the cylinder having smaller radii ratios requires lesser angular velocity to become fully plastic as compared to cylinder having higher radii ratios The circumferential stress becomes larger and larger with the increase in temperature. With increase in thickness ratio stresses must be decrease. For the creep stage, it is seen that circumferential stresses for incompressible materials maximum at the internal surface as compared to compressible material, which increase with the increase in temperature and measure n.

  17. Stress-state monitoring of coal pillars during room and pillar extraction

    Directory of Open Access Journals (Sweden)

    Petr Waclawik

    2016-01-01

    To determine pillar stability, vertical stress was measured in two adjacent coal pillars which are diamond in shape and located within a row of pillars forming the panel. Two pillars diamond in shape and slightly irregular sides were approximately 860 m2 and 1200 m2 in size and 3.5 m high To measure the increase in vertical stress due to mining, four stress cells were installed in each coal pillar. Four 5-level multipoint rib extensometers measured displacements of all sides within each monitored pillar. The results of stress-state and pillar displacement monitoring allowed pillar loading and yielding characteristics to be described. This data and other analyses are essential to establishing procedures for a safe room and pillar method of mining within the Upper Silesian Coal Basin.

  18. Water stress and social vulnerability in the southern United States, 2010-2040

    Science.gov (United States)

    cassandra Johnson-Gaither; John Schelhas; Wayne Zipperer; Ge Sun; Peter V. Caldwell; Neelam Poudyal

    2014-01-01

    Water scarcities are striking in semiarid, subregions of the Southern United States such as Oklahoma and western Texas (Glennon 2009, Sabo et al. 2010). In Texas, water stress has been a constant concern since the 1950s when the state experienced severe drought conditions (Moore 2005). The nearly 2000-mile Rio Grande River, which forms part of the Texas–Mexico border,...

  19. Finite element modelling of creep process - steady state stresses and strains

    Directory of Open Access Journals (Sweden)

    Sedmak Aleksandar S.

    2014-01-01

    Full Text Available Finite element modelling of steady state creep process has been described. Using an analogy of visco-plastic problem with a described procedure, the finite element method has been used to calculate steady state stresses and strains in 2D problems. An example of application of such a procedure have been presented, using real life problem - cylindrical pipe with longitudinal crack at high temperature, under internal pressure, and estimating its residual life, based on the C*integral evaluation.

  20. Investigation of the Residual Stress State in an Epoxy Based Specimen

    DEFF Research Database (Denmark)

    Baran, Ismet; Jakobsen, Johnny; Andreasen, Jens Henrik

    2015-01-01

    observations. In the present work, the formation of the residual stresses/strains are captured from experimental measurements and numerical models. An epoxy/steel based sample configuration is considered which creates an in-plane biaxial stress state during curing of the resin. A hole drilling process...... with a diameter of 5 mm is subsequently applied to the specimen and the released strains after drilling are measured using the Digital Image Correlation (DIC) technique. The material characterization of the utilized epoxy material is obtained from the experimental tests such as differential scanning calorimetry...... material models, i.e. cure kinetics, elastic modulus, CTE, chemical shrinkage, etc. together with the drilling process using the finite element method. The measured and predicted in-plane residual strain states are compared for the epoxy/metal biaxial stress specimen....

  1. Subcritical measurements of the WINCO slab tank experiment using the source-jerk technique

    Energy Technology Data Exchange (ETDEWEB)

    Spriggs, G.D.; Hansen, G.E.; Martin, E.R.; Plassmann, E.A.; Pederson, R.A.; Schlesser, J.A.; Krawczyk, T.L.; Tanner, J.E.; Smolen, G.R. (Los Alamos National Lab., NM (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA); Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA))

    1989-01-01

    Subcritical measurements of the WINCO slab tank using the source-jerk technique are presented. This technique determines subcriticality by analyzing the transient response produced by the sudden removal of an extraneous neutron source (i.e., a source jerk). We have found that the technique can provide an accurate means of measuring k in configurations that are close to critical (i.e., 0.90 < k < 1.0). As the system becomes more subcritical (i.e., k < 0.90), spatial effects introduce significant biases depending on the source and detector positions. A comparison between the measurements and Monte Carlo code calculations is also presented. 15 refs., 6 figs., 2 tabs.

  2. Perceived Sources of Occupational Stress among Primary School Teachers in Delta State of Nigeria

    Science.gov (United States)

    Akpochafo, G. O.

    2012-01-01

    This study investigated the most prevalent sources of occupational stress and also the demographic variables of gender, age and length of service among primary school teachers in Delta State. Two research questions and three hypotheses guided the study. The study used a descriptive survey design. The population was the primary school teachers in…

  3. Stress-strain state simulation of large-sized cable-stayed shell structures

    Science.gov (United States)

    Ponomarev, S.; Zhukov, A.; Belkov, A.; Ponomarev, V.; Belov, S.; Pavlov, M.

    2015-12-01

    This paper studies the opportunities for applying framed cable-stayed shell structures to generate innovative structures in civil engineering. Numerical solution methods for stress-strain state problems of these kinds of geometrically nonlinear structures were developed. Developed methods efficiency is presented by a range of large-dimensional space antenna reflectors.

  4. Мodeling of stressed-deformed state in mechanical tasks soils

    Directory of Open Access Journals (Sweden)

    А.І. Білеуш

    2006-01-01

    Full Text Available  The modeling methods of heterogeneous and anisotropic soil mass taking into consideration real behavior have been carried out analysis by strain-stress state investigation on the basis of finite element method  for assurance reliability.

  5. STRESS STATE OF TRANSVERSELY ISOTROPIC ROCKS NEAR PRESSURIZED HYDRAULIC TUNNEL OF HORSESHOE CROSS-SECTION

    Directory of Open Access Journals (Sweden)

    Bautdinov Damir Tahirovich

    2017-10-01

    Full Text Available The parametric analysis of the stress state of a transversally isotropic rock mass near a pressurized hydraulic tunnel of a box-shaped form is carried out. Pressurized hydro-technical tunnels of box-shaped cross-section are widely used in the field of hydraulic engineering construction and are one of the complex, labor-intensive and expensive types of structures that make up the main structures of waterworks, melioration systems and water supply systems. As a culvert and water supply facilities they are built underground if the open excavation is impossible or not economical, or when the tunnel runs through a densely populated or densely built-up area, or when landslides, screes, rockfalls are possible. Violation of integrity of the rock mass, in particular, caused by tunneling, modifies the stress-strain state (SSS of the rock mass, which leads to appearance of tensile stresses in some places, and in some cases, to significant compressive stresses. If these stresses exceed the design strengths of rock to tension and compression, respectively, then the collapse of the working roof and buckling of the side walls and the bottom of the tunnel may occur. Subject: analysis of the stress state of transversally isotropic rocks near the pressurized hydraulic tunnel of horseshoe cross-section caused by the internal head of water. Research objectives: determination of real values of circumferential stresses along the development contour. Materials and methods: solution of the problem of plane deformation of the theory of elasticity for a transversely isotropic medium containing tunnel excavation cannot be obtained by analytical methods, and therefore the stress-strain analysis was carried out by the finite element method using the ANSYS software package, MCE. Results: determination of stresses along the development contour, construction of diagrams and graphs showing the effects of the anisotropy conditions and Poisson’s ratio. The tangential stresses

  6. An Examination of Individual Level Factors in Stress and Coping Processes: Perspectives of Chinese International Students in the United States

    Science.gov (United States)

    Yan, Kun; Berliner, David C.

    2011-01-01

    No empirical research has focused solely upon understanding the stress and coping processes of Chinese international students in the United States. This qualitative inquiry examines the individual-level variables that affect the stress-coping process of Chinese international students and how they conceptualize and adapt to their stress at an…

  7. Subcritical calculation of the nuclear material warehouse;Calculo de subcriticidad del almacen del material nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Mazon R, R., E-mail: teodoro.garcia@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    In this work the subcritical calculation of the nuclear material warehouse of the Reactor TRIGA Mark III labyrinth in the Mexico Nuclear Center is presented. During the adaptation of the nuclear warehouse (vault I), the fuel was temporarily changed to the warehouse (vault II) and it was also carried out the subcritical calculation for this temporary arrangement. The code used for the calculation of the effective multiplication factor, it was the Monte Carlo N-Particle Extended code known as MCNPX, developed by the National Laboratory of Los Alamos, for the particles transport. (Author)

  8. Subcritical water extraction of amino acids from Mars analog soils.

    Science.gov (United States)

    Noell, Aaron C; Fisher, Anita M; Fors-Francis, Kisa; Sherrit, Stewart

    2018-01-18

    For decades, the Martian regolith has stymied robotic mission efforts to catalog the organic molecules present. Perchlorate salts, found widely throughout Mars, are the main culprit as they breakdown and react with organics liberated from the regolith during pyrolysis, the primary extraction technique attempted to date on Mars. This work further develops subcritical water extraction (SCWE) as a technique for extraction of amino acids on future missions. The effect of SCWE temperature (185, 200, and 215°C) and duration of extraction (10-120 min) on the total amount and distribution of amino acids recovered was explored for three Mars analog soils (JSC Mars-1A simulant, an Atacama desert soil, and an Antarctic Dry Valleys soil) and bovine serum albumin (as a control solution of known amino acid content). Total amounts of amino acids extracted increased with both time and temperature; however, the distribution shifted notably due to the destruction of the amino acids with charged or polar side chains at the higher temperatures. The pure bovine serum albumin solution and JSC Mars 1A also showed lower yields than the Atacama and Antarctic extractions suggesting that SCWE may be less effective at hydrolyzing large or aggregated proteins. Changing solvent from water to a dilute (10 mM) HCl solution allowed total extraction efficiencies comparable to the higher temperature/time combinations while using the lowest temperature/time (185°C/20 min). The dilute HCl extractions also did not lead to the shift in amino acid distribution observed at the higher temperatures. Additionally, adding sodium perchlorate salt to the extraction did not interfere with recoveries. Native magnetite in the JSC Mars-1A may have been responsible for destruction of glycine, as evidenced by its uncharacteristic decrease as the temperature/time of extraction increased. This work shows that SCWE can extract high yields of native amino acids out of Mars analog soils with minimal disruption of the

  9. A large-scale perspective on stress-induced alterations in resting-state networks

    Science.gov (United States)

    Maron-Katz, Adi; Vaisvaser, Sharon; Lin, Tamar; Hendler, Talma; Shamir, Ron

    2016-02-01

    Stress is known to induce large-scale neural modulations. However, its neural effect once the stressor is removed and how it relates to subjective experience are not fully understood. Here we used a statistically sound data-driven approach to investigate alterations in large-scale resting-state functional connectivity (rsFC) induced by acute social stress. We compared rsfMRI profiles of 57 healthy male subjects before and after stress induction. Using a parcellation-based univariate statistical analysis, we identified a large-scale rsFC change, involving 490 parcel-pairs. Aiming to characterize this change, we employed statistical enrichment analysis, identifying anatomic structures that were significantly interconnected by these pairs. This analysis revealed strengthening of thalamo-cortical connectivity and weakening of cross-hemispheral parieto-temporal connectivity. These alterations were further found to be associated with change in subjective stress reports. Integrating report-based information on stress sustainment 20 minutes post induction, revealed a single significant rsFC change between the right amygdala and the precuneus, which inversely correlated with the level of subjective recovery. Our study demonstrates the value of enrichment analysis for exploring large-scale network reorganization patterns, and provides new insight on stress-induced neural modulations and their relation to subjective experience.

  10. Tracheal occlusion conditioning causes stress, anxiety and neural state changes in conscious rats.

    Science.gov (United States)

    Pate, K M; Davenport, P W

    2013-03-01

    Evidence from human and animal studies indicates that mechanical loads to breathing are stressful stimuli and evoke compensatory behaviours. Conditioning of stressful stimuli is known to cause changes in basal stress levels and behaviour. Individuals with respiratory obstructive diseases repeatedly experience bouts of airway obstruction, which may act as a form of conditioning, and often have affective disorders, such as anxiety and depression. It is unknown whether the development of affective disorders in these individuals results from the unexpected recurring respiratory perturbations. To investigate this possibility, we developed a model to elicit tracheal occlusion (TO) in conscious rats and exposed them to 10 days of TO conditioning. We hypothesized that healthy, conscious animals exposed to TO conditioning would develop stress and anxiety and would have modulated neural activity in respiratory, stress, discriminative and affective neural regions. Following TO conditioning, rats had increased basal corticosterone levels, greater adrenal weights and elevated anxiety levels compared with animals not receiving TO. Significant increases in cytochrome oxidase staining were found in brainstem respiratory nuclei, periaqueductal grey, dorsal raphe, thalamus and insular cortex. These results suggest that healthy animals develop stress and anxiety responses to respiratory load conditioning via inescapable tracheal occlusions, which may be mediated through state changes in specific brain nuclei.

  11. Transactional stress and coping theory in accounting for psychological states measures

    Directory of Open Access Journals (Sweden)

    V. Buško

    2007-08-01

    Full Text Available The paper examines a relative predictive value of some stable individual attributes and the processes of cognitive appraisals and coping with stress in accounting for specific components of anxiety state measures. Self-report instruments for the measurement of selected psychological constructs, i.e. perceived incompetence, externality, stress intensity and duration, situation-specific coping strategies, and the two anxiety state components, were taken in a sample of 449 male military basics trainees, ranging in age from 18-27. Hierarchical multiple regression analyses showed that the set of predictors employed could account for statistically, as well as theoretically and practically a significant part of variance in cognitive anxiety component (45,5%, and in visceral-emotional component (32,2% of the anxiety state. The extent of anxiety reactions assessed by both scales could primarily be explained by general perception of personal incompetence, as a relatively stable dimension of general self-concept. Of the ways of coping examined, reinterpretation of stressful events was the only strategy contributing to low level, whereas passivization, wishful thinking, and seeking social support contributed to higher levels of anxiety measured by both scales. The results give partial support to the basic hypotheses on the mediating role of coping in the relationships among particular components of the stress and coping models.

  12. Structure/property relations of aluminum under varying rates and stress states

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Matthew T [Los Alamos National Laboratory; Horstemeyer, Mark F [MISSISSIPPI STATE UNIV; Whittington, Wilburn R [MISSISSIPPI STATE UNIV; Solanki, Kiran N [MISSISSIPPI STATE UNIV.

    2010-11-19

    In this work we analyze the plasticity, damage, and fracture characteristics of three different processed aluminum alloys (rolled 5083-H13, cast A356-T6, and extruded 6061-T6) under varying stress states (tension, compression, and torsion) and strain rates (0.001/, 1/s., and 1000/s). The stress state difference had more of a flow stress effect than the applied strain rates for those given in this study (0.001/sec up to 1000/sec). The stress state and strain rate also had a profound effect on the damage evolution of each aluminum alloy. Tension and torsional straining gave much greater damage nucleation rates than compression. Although the damage of all three alloys was found to be void nucleation dominated, the A356-T6 and 5083-H131 aluminum alloys incurred void damage via micron scale particles where the 6061-T6 aluminum alloy incurred void damage from two scales, micron-scale particles and nanoscale precipitates. Having two length scales of particles that participated in the damage evolution made the 6061-T6 incur a strain rate sensitive damage rate that was different than the other two aluminum alloys. Under tension, as the strain rate increased, the 6061-T6 aluminum alloy's void nucleation rate decreased, but the A356-T6 and 5083-H131 aluminum alloys void nucleation rate increased.

  13. Mozart versus new age music: relaxation states, stress, and ABC relaxation theory.

    Science.gov (United States)

    Smith, Jonathan C; Joyce, Carol A

    2004-01-01

    Smith's (2001) Attentional Behavioral Cognitive (ABC) relaxation theory proposes that all approaches to relaxation (including music) have the potential for evoking one or more of 15 factor-analytically derived relaxation states, or "R-States" (Sleepiness, Disengagement, Rested / Refreshed, Energized, Physical Relaxation, At Ease/Peace, Joy, Mental Quiet, Childlike Innocence, Thankfulness and Love, Mystery, Awe and Wonder, Prayerfulness, Timeless/Boundless/Infinite, and Aware). The present study investigated R-States and stress symptom-patterns associated with listening to Mozart versus New Age music. Students (N = 63) were divided into three relaxation groups based on previously determined preferences. Fourteen listened to a 28-minute tape recording of Mozart's Eine Kleine Nachtmusik and 14 listened to a 28-minute tape of Steven Halpern's New Age Serenity Suite. Others (n = 35) did not want music and instead chose a set of popular recreational magazines. Participants engaged in their relaxation activity at home for three consecutive days for 28 minutes a session. Before and after each session, each person completed the Smith Relaxation States Inventory (Smith, 2001), a comprehensive questionnaire tapping 15 R-States as well as the stress states of somatic stress, worry, and negative emotion. Results revealed no differences at Session 1. At Session 2, those who listened to Mozart reported higher levels of At Ease/Peace and lower levels of Negative Emotion. Pronounced differences emerged at Session 3. Mozart listeners uniquely reported substantially higher levels of Mental Quiet, Awe and Wonder, and Mystery. Mozart listeners reported higher levels, and New Age listeners slightly elevated levels, of At Ease/Peace and Rested/Refreshed. Both Mozart and New Age listeners reported higher levels of Thankfulness and Love. In summary, those who listened to Mozart's Eine Kleine Nachtmusik reported more psychological relaxation and less stress than either those who listened to

  14. Modelling of the in situ stress state at Olkiluoto Site, Western Finland

    Energy Technology Data Exchange (ETDEWEB)

    Valli, J.; Kuula, H. [WSP Finland Oy, Helsinki (Finland); Hakala, M. [KMS Hakala Oy, Nokia (Finland)

    2011-06-15

    In order to determine the interaction of in situ stress and geological features at Olkiluoto with the ONKALO area under more specific focus, stress modelling work was launched in 2009. This entailed updating a previously used model geometry to suit current needs whilst also updating interpreted brittle deformation zones according to the data provided by Posiva in the beginning of 2010. The previous model geometry was originally used for seismic and glacial load simulations. Brittle deformation zones were updated in the model according to a new selection criterion which added a number of brittle deformation zones. Changes in the geometry of certain brittle deformation zones were also necessary to better fit the early 2010 interpretations from Posiva. Modelling goals were to clarify the effect of joint parameters on stress magnitude and orientation and which of the major brittle deformation zones detected in the ONKALO region could have potential effects on local in situ stress states. Additional goals included modelling the effect of several optional thrust boundary conditions and an ice-age. Compression from the northwest-southeast was used as the default approach whilst north-south, east-west and northeast-southwest were optional conditions. A simplified glaciation cycle was also simulated. Results were clear in demonstrating the critical effect of joint cohesion and joint friction angle, i.e. shear strength, on stress-geology interaction, essentially in this order of importance. The case that utilised both drillhole core-logging and ONKALO tunnel mapping results did not exhibit much if any stress-geology interactions as BFZ strength parameters were too high in order to allow any interactions to occur. The geometry and orientation of brittle deformation zones was found to be of significant importance; deformation zones with a shallow dip roughly in the direction of applied compression were optimal for causing stress rotations and the increase of stress magnitude

  15. Results of the neotectonic stress state study in the eastern part of Baltic shield

    Science.gov (United States)

    Sim, Lidiya A.; Zhirov, Dmitriy V.; Smaglichenko, Tatyana A.; Smaglichenko, Alexandr V.

    2010-05-01

    Recently a caving of the Kovdor quarry south-eastern bort occurred on the Kovdor massif (the eastern part of Baltic shield). This required a careful analyze of the stress field in the massif and a comparison of it with general situation in a region. In spite of weak seismicity at whole on the given territory it is characterized by the presence of earthquakes with M = 4 - 4.4 especially in zones of mining works (for example, events of 16.04.1989 and 17.08.1999 at the Khibiny-Lovoserskyi district). The risk zone is increased as for large industrial facilities AES located there as for big quarries extracting minerals. Kinematic method developed by Gushenko in 1973, 1979 has been applied in order to get the stress fields. The field works were performed during summer of 2009. According to this method vectors of tectonic movements along in fissures have been analyzed and local stress states have been reconstructed demonstrating significant range in orientation of axis of main normal stresses. These local stress states were conventionally correspond to the third rank and by using this information tectonic stresses of the second rank have been reconstructed. In the caving zone the local stress state can be characterized as uniaxial tension that could bring the caving. Previous investigations of the eastern part of Baltic shield were made for peninsulas Sredniy, Ryibachiy, for the White sea islands, at coast of the Kandalakschsky Bay, on the Chibino massif. Tectonic stresses of the first rank were revealed and were characterized as subhorizontal axis of compression and of tension. The compressional axis has the WNW orientation while and the extension axis is submeridional. Our research showed that the compression axis on the Kovdor massif has orientation 98° , angle is equal 15. This is in agreement with the previous results. The reconstructed stress field at whole well corresponds to the major faults Onego-Segozerskiy and Kandalakscha, which are seismic active zones. The

  16. METHOD FOR CALCULATION OF STRESS-STRAIN STATE DUE TO SINGLE TWIN IN GRAIN OF VARIOUS FORMS

    Directory of Open Access Journals (Sweden)

    T. V. Drabysheuskaya

    2016-01-01

    Full Text Available The paper investigates a stress-strain state in a polycrystalline grain due to presence in its body of a single micro- twin in case of various grain boundary forms. A methodology for calculation of displacement and stress fields for the specified stress-strain state of a polygon-shaped grain has been developed in the paper. Nodal points in a polycrystalline grain that have a maximum stresses contributing to initiation of destruction have been revealed in the paper. The aim of this work has been to study the stress-strain state due to a single micro-twin in the polycrystalline grain and form of grain boundaries. The paper describes polycrystalline grains having a regular polygon shape and containing a single wedge twin in their body. Polycrystalline grain boundaries are presented as walls with complete dislocation. The investigated grains are located far from the surface of twinning material. The developed methodology for calculation of displacement and stresses created by wedge twin is based on the principle of superposition. Calculations on stress tensor components have been carried out for iron (Fe. The presented results of calculations for stress fields have indicated to validity of the used dislocation model. Twin and grain boundaries being stress concentrators are clearly visible on the obtained distributions of stress fields. Maximum normal stresses are observed on the twin boundaries; σxy maximum shear stresses are located at nodal points of the twin; σzy and σxz shear stresses are maximum on the grain boundaries. The conducted investigations have resulted in study of the stress-strain state due to a single wedge-shaped micro-twin in the polycrystalline grain and form of the grain boundaries. Zones of stress concentration in the polycrystalline grain have been identified in the presence of residual mechanical wedge twin. A method for evaluation of the given state has been developed in the paper.

  17. Creep behavior of Grade 91 steel under uniaxial and multiaxial state of stress

    Science.gov (United States)

    Ren, Facai; Tang, Xiaoying

    2017-09-01

    Creep rupture behavior of Grade 91 heat-resistant steel used for steam cooler under uniaxial and multiaxial state of stress was investigated. Creep tests were conducted at the temperature of 923K under the stress 125MPa. The notch root radii (r) of doubled circumferentially U-notched specimens were 0.6 and 6 mm. The creep rupture life of Grade 91 steel was found to increase with the increasing of notch acuity ratio. The creep rupture mechanism was investigated based on the SEM fractography analysis.

  18. Mindfulness-Based Stress Reduction and Transcendental Meditation: Current State of Research

    Directory of Open Access Journals (Sweden)

    Adam Holt

    2015-04-01

    Full Text Available This article summarizes the current state of meditation research, specifically focusing on mindfulness-based stress reduction and transcendental meditation. Despite significant methodological problems with the studies reported to date on the subject, there is consistent evidence that meditation can produce changes in the nervous system and physiology of the meditator, and can help with various psychological markers of well-being. Regarding improvement in specific clinical diseases, research is generally mixed and preliminary. Strong recommendations cannot be made based on current evidence, and further studies are needed. In general, there is a stronger body of evidence supporting mindfulness-based stress reduction than for transcendental meditation.

  19. Experimental Research of Reliability of Plant Stress State Detection by Laser-Induced Fluorescence Method

    Directory of Open Access Journals (Sweden)

    Yury Fedotov

    2016-01-01

    Full Text Available Experimental laboratory investigations of the laser-induced fluorescence spectra of watercress and lawn grass were conducted. The fluorescence spectra were excited by YAG:Nd laser emitting at 532 nm. It was established that the influence of stress caused by mechanical damage, overwatering, and soil pollution is manifested in changes of the spectra shapes. The mean values and confidence intervals for the ratio of two fluorescence maxima near 685 and 740 nm were estimated. It is presented that the fluorescence ratio could be considered a reliable characteristic of plant stress state.

  20. STRESS-STRAIN STATE OF BEAM STAGED CONNECTION POINT OF THE RAILWAY BRIDGE TRACK-WAY

    Directory of Open Access Journals (Sweden)

    S. V. Kluchnik

    2017-06-01

    Full Text Available Purpose. The staged connections of the beams of railway bridge track-way have the simplest design, but some design flaws result in numerous defects. The purpose of the given work is to research the actual stress-train state of the point of connection of the stringers with the floor beams on condition of their staged interposition. It is also necessary to determine possible effect of coupled work of deck beam grid and booms on their stress-strain state. Methodology. To reach the purpose of the study the testing of the existing bridge was conducted. To measure strains (stresses in the span elements we used the strain gages glued to flange angles of stringers and floor beams and to fillets of lower flange angles of stringers in the points of their support on floor beams. To measure deflections of the truss, stringers and floor beams from static loads we used Aistov’s and Maksimov’s deflectometers, that were installed on lower boom in the middle of span 0-1, as well as on both stringers and floor beams in the middle of the span. Deflectometers were fastened to the span and, by wire communication, to the ground surface. Findings. Stress-strain state of the point of connection of the stringers with the floor beams on condition of their staged interposition was obtained and analyzed. Analysis indicates that, apart from vertical bending of the stringers and beams, there is a significant effect of horizontal bending of floor beams and their torsion, that occur due to the coupled work of track-way beams and top booms, both for P0 beam and for other beams. Originality. Research of stress-strain state of metal track-way staged beams while considering their coupled work with bearing trusses. Practical value. While testing the span under the train load, there are significant additional stresses from horizontal bending of floor beams and their torsion in the floor beam flanges. The appearance of these stresses is caused by inclusion of stringers into

  1. Analysis of Subcritical Crack Growth in Dental Ceramics Using Fracture Mechanics and Fractography

    Science.gov (United States)

    Taskonak, Burak; Griggs, Jason A.; Mecholsky, John J.; Yan, Jia-Hau

    2008-01-01

    .05) but did not have significantly different fracture toughness (P>0.05). Regarding critical flaw size, stressing rate had a significant effect for In-Ceram® Zirconia specimens (P≤0.05) but not for Vitadur Alpha specimens (P>0.05). Fatigue parameters, n and ln B, were 38.4 and −12.7 for Vitadur Alpha and were 13.1 and 10.4 for In-Ceram® Zirconia. Significance Moisture assisted subcritical crack growth had a more deleterious effect on In-Ceram® Zirconia core ceramic than on Vitadur Alpha porcelain. Fracture surface analysis identified fracture surface features that can potentially mislead investigators into misidentifying the critical flaw. PMID:17845817

  2. Nonlinear dynamics aspects of subcritical transitions and singular flows in viscoelastic fluids

    NARCIS (Netherlands)

    Becherer, Paul

    2008-01-01

    Recently, there has been a renewed interest in theoretical aspects of flows of viscoelastic fluids (such as dilute polymer solutions). This thesis addresses two distinct issues related to such flows. Motivated by the possible occurrence of subcritical (finite-amplitude) instabilities in parallel

  3. Subcritical water - a perspective reaction media for biomass processing to chemicals

    OpenAIRE

    Pavlovič, Irena; Škerget, Mojca; Knez, Željko

    2015-01-01

    Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP

  4. Promotion or suppression of glucose isomerization in subcritical aqueous straight- and branched-chain alcohols.

    Science.gov (United States)

    Gao, Da-Ming; Kobayashi, Takashi; Adachi, Shuji

    2015-01-01

    The influence of water-miscible alcohols (methanol, 1-propanol, 2-propanol, and t-butyl alcohol) on the isomerization of glucose to fructose and mannose was investigated under subcritical aqueous conditions (180-200 °C). Primary and secondary alcohols promoted the conversion and isomerization of glucose to afford fructose and mannose with high and low selectivity, respectively. On the other hand, the decomposition (side-reaction) of glucose was suppressed in the presence of the primary and secondary alcohols compared with that in subcritical water. The yield of fructose increased with increasing concentration of the primary and secondary alcohols, and the species of the primary and secondary alcohols tested had little effect on the isomerization behavior of glucose. In contrast, the isomerization of glucose was suppressed in subcritical aqueous t-butyl alcohol. Both the conversion of glucose and the yield of fructose decreased with increasing concentration of t-butyl alcohol. In addition, mannose was not detected in reactions using subcritical aqueous t-butyl alcohol.

  5. Subcritical crack growth behavior of AI2O3-Glass dental composites

    NARCIS (Netherlands)

    Zhu, Q.; With, G. de; Dortmans, L.J.M.G.; Feenstra, F.

    2003-01-01

    The purpose of this study is to investigate the subcritical crack growth (SCG) behavior of alumina-glass dental composites. Alumina-glass composites were fabricated by infiltrating molten glass to porous alumina preforms. Rectangular bars of the composite were subject to dynamic loading in air, with

  6. Study of the stress-strain state of compressed concrete elements with composite reinforcement

    Directory of Open Access Journals (Sweden)

    Bondarenko Yurii

    2017-01-01

    Full Text Available The efficiency analysis of the application of glass composite reinforcement in compressed concrete elements as a load-carrying component has been performed. The results of experimental studies of the deformation-strength characteristics of this reinforcement on compression and compressed concrete cylinders reinforced by this reinforcement are presented. The results of tests and mechanisms of sample destruction have been analyzed. The numerical analysis of the stress-strain state has been performed for axial compression of concrete elements with glasscomposite reinforcement. The influence of the reinforcement percentage on the stressed state of a concrete compressed element with the noted reinforcement is estimated. On the basis of the obtained results, it is established that the glass-composite reinforcement has positive effect on the strength of the compressed concrete elements. That is, when calculating the load-bearing capacity of such structures, the function of composite reinforcement on compression should not be neglected.

  7. Computer modeling of the stress-strain state of a linear friction welded disk

    Directory of Open Access Journals (Sweden)

    V. Bychkov

    2015-09-01

    Full Text Available The paper is dedicated to design issues of tooling for linear friction welding (LFW machine. Computer model of a LFW machine was built. As a result of computer simulation, the stress-strain state of the machine and disk module for linear friction welding of aluminum alloy blisks also was obtained. On the basis of the results of computer simulation a module with a replaceable unit and a new variant fixing of disc in the module were designed.

  8. Profile of mood states and stress-related biochemical indices in long-term yoga practitioners

    Directory of Open Access Journals (Sweden)

    Sudo Nobuyuki

    2011-06-01

    Full Text Available Abstract Background Previous studies have shown the short-term or intermediate-term practice of yoga to be useful for ameliorating several mental disorders and psychosomatic disorders. However, little is known about the long-term influences of yoga on the mental state or stress-related biochemical indices. If yoga training has a stress-reduction effect and also improves an individual's mental states for a long time, long-term yoga practitioners may have a better mental state and lower stress-related biochemical indices in comparison to non-experienced participants. This study simultaneously examined the differences in mental states and urinary stress-related biochemical indices between long-term yoga practitioners and non-experienced participants. Methods The participants were 38 healthy females with more than 2 years of experience with yoga (long-term yoga group and 37 age-matched healthy females who had not participated in yoga (control group. Their mental states were assessed using the Profile of Mood States (POMS questionnaire. The level of cortisol, 8-hydroxydeoxyguanosine (8-OHdG and biopyrrin in urine were used as stress-related biochemical indices. Results The average self-rated mental disturbance, tension-anxiety, anger-hostility, and fatigue scores of the long-term yoga group were lower than those of the control group. There was a trend toward a higher vigor score in the long-term yoga group than that in the control group. There were no significant differences in the scores for depression and confusion in the POMS between the two groups. The urine 8-OHdG concentration showed a trend toward to being lower in the long-term yoga group in comparison to the control group. There were no significant differences in the levels of urine biopyrrin or cortisol. Conclusions The present findings suggest that long-term yoga training can reduce the scores related to mental health indicators such as self-rated anxiety, anger, and fatigue.

  9. Conceptual design of minor actinides burner with an accelerator-driven subcritical system.

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y.; Gohar, Y. (Nuclear Engineering Division)

    2011-11-04

    In the environmental impact study of the Yucca Mountain nuclear waste repository, the limit of spent nuclear fuel (SNF) for disposal is assessed at 70,000 metric tons of heavy metal (MTHM), among which 63,000 MTHM are the projected SNF discharge from U.S. commercial nuclear power plants though 2011. Within the 70,000 MTHM of SNF in storage, approximately 115 tons would be minor actinides (MAs) and 585 tons would be plutonium. This study describes the conceptual design of an accelerator-driven subcritical (ADS) system intended to utilize (burn) the 115 tons of MAs. The ADS system consists of a subcritical fission blanket where the MAs fuel will be burned, a spallation neutron source to drive the fission blanket, and a radiation shield to reduce the radiation dose to an acceptable level. The spallation neutrons are generated from the interaction of a 1 GeV proton beam with a lead-bismuth eutectic (LBE) or liquid lead target. In this concept, the fission blanket consists of a liquid mobile fuel and the fuel carrier can be LBE, liquid lead, or molten salt. The actinide fuel materials are dissolved, mixed, or suspended in the liquid fuel carrier. Therefore, fresh fuel can be fed into the fission blanket to adjust its reactivity and to control system power during operation. Monte Carlo analyses were performed to determine the overall parameters of an ADS system utilizing LBE as an example. Steady-state Monte Carlo simulations were studied for three fission blanket configurations that are similar except that the loaded amount of actinide fuel in the LBE is either 5, 7, or 10% of the total volume of the blanket, respectively. The neutron multiplication factor values of the three configurations are all approximately 0.98 and the MA initial inventories are each approximately 10 tons. Monte Carlo burnup simulations using the MCB5 code were performed to analyze the performance of the three conceptual ADS systems. Preliminary burnup analysis shows that all three conceptual ADS

  10. Analysis of stress-strain state of the spherical shallow shell with inclusion

    Directory of Open Access Journals (Sweden)

    O.B. Kozin

    2016-05-01

    Full Text Available Development of effective methods of determining the stress-strain state thin-walled structures with inclusions, reinforcements and other stress concentrators is an important task, both from a theoretical and practical point of view, by reason of their great practical application. Aim: The aim of the research is to analyze the elastic-deformed state of a spherical shallow shell. Materials and Methods: In this work, based on the generalized scheme of integral transformations, a constructive method of direct numerical-analytical solutions of boundary value problem of calculating the stress-strain state of a spherical shallow shell with the inclusion in bending is proposed. Results: The results of numerical calculations are presented. Calculations allow predicting the value of deformation of the cylindrical shells structure with reinforcements and determining the optimum parameters for the design or manufacture. The obtained results can be used in determining the strength characteristics of structural elements that consist of composite materials. The article contains comparative analysis of the results and demonstrates the effectiveness of the method for solving this class of problems.

  11. DEPRESSION, ANXIETY, STRESS, AND THEIR ASSOCIATED FACTORS AMONG CORPS MEMBERS SERVING IN KEBBI STATE.

    Science.gov (United States)

    Balami, Ahmed D

    2015-01-01

    Depression, anxiety and stress, are not only health problems by themselves, but also associated with other negative health consequences. The national youth service is usually characterized by a number of new challenges and experiences which may require life style adjustments by the corps member. However, no previous study on psychological factors has been conducted among corps members. This study was conducted to determine the prevalence of depression, anxiety and, stress and their associated factors among corps members serving in Kebbi state. A cross-sectional study was conducted among 264 corps members from four local government areas of the state. Selection of the local government areas and the individual participants was by simple random sampling. Data was collected from May to June 2014 using a self-administered questionnaire. Data analysis used chi-square test to identify the relationship between categorical variables and multivariate logistic regression to identify the independent factors for depression, anxiety and stress each. The response rate was 97%. Most of the respondents were males (63.6%), single (85.5%), and above 20 years of age (71.6%). The overall prevalences of depression, anxiety and stress among the respondents were 36.4%, 54.5% and 18.2% respectively. The independent factors for depression were; being from the North central (OR = 5.99; 95% CI: 2.194-16.354) or South-south; and the perception of earning enough income (OR = 2.987; 95% CI: 1.062-8.400). For anxiety, male gender (OR = 0.411; 95% CI: 0.169-0.999); and being from the North central were significant risk factors (OR = 3.731; 95% CI: 1.450-9.599). Being above 26 years of age was an independent risk factor for stress (OR = 0.083; 95% CI: 0.018-0.381). Also, those who had ever schooled outside their towns of residence were less likely to be stressed compared to those who had never (OR = 0.30; 95% CI: 0.110-0.855). All other factors did not show any significant association with any of

  12. The impact of resin-coating on sub-critical crack extension in a porcelain laminate veneer material.

    Science.gov (United States)

    Cao, Xu; Fleming, Garry J P; Addison, Owen

    2017-05-01

    Characterisation of the interaction between crack extension, crack stabilisation and stress/strain relaxation in the polymeric matrix, the interplay between stress corrosion cracking and the mechanical response of a resin-based luting adhesive within a surface defect population could extend PLV restoration longevity by optimising cementation protocols. The aim was to investigate the influence of stress corrosion cracking and the viscoelastic behaviour of a resin-based luting adhesive independently by controlling the environmental conditions operative during test specimen fabrication. The effects of stress corrosion at ceramic crack tips and potential viscoelastic responses to loading of the resin-coated impregnating cracks were isolated. Resin-coated feldspathic ceramic test specimens were fabricated in ambient humidity or following moisture exclusion. Bi-axial flexure strengths of groups (n = 20) were determined at constant loading rates of 2.5, 10, 40, 160 or 640 N/min and data was compared with uncoated controls. Fractographic analyses were performed on all fractured test specimens. Resin-cement coating resulted in significant ceramic strengthening in all conditions tested (p < 0.01). A two-way ANOVA demonstrated that the exclusion of moisture during resin- coating significantly increased mean BFS (p<0.01) but post-hoc Tukey tests identified that moisture exclusion resulted in significant increases in BFS values only at intermediate loading rates with no significant differences observed at either the fastest or slowest loading rates (640 and 2.5 N/min, respectively). Mechanical reinforcement of PLV materials by resin-cement systems is yet to be optimized. The viscoelastic behavior of the resin-cement itself can influence the magnitude of reinforcement observed and sub-critical crack growth. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Extinction-induced neuroplasticity attenuates stress-induced cocaine seeking: a state-dependent learning hypothesis.

    Science.gov (United States)

    Self, David W; Choi, Kwang-Ho

    2004-09-01

    Chronic drug use weakens excitatory neocortical input to the nucleus accumbens (NAc). We previously reported that extinction training, a form of inhibitory learning that progressively reduces cocaine-seeking behaviour when reward is withheld, reverses this deficit by up-regulating GluR1 and GluR2/3 subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) glutamate receptors in the NAc. The level of GluR1 up-regulation is positively associated with a reduction in cocaine seeking, suggesting that extinction-induced up-regulation in AMPA receptors in the NAc opposes motivational influences that maintain cocaine seeking. This hypothesis is supported by the finding that over-expression of GluR1 and GluR2 in the NAc facilitates extinction of cocaine self-administration. Furthermore, a single extinction training session conducted during GluR1 and GluR2 over-expression strongly and selectively attenuates the ability of an environmental stressor to trigger relapse to cocaine seeking long after GluR1 and GluR2 over-expression declines. These results could suggest that excitatory input to the NAc promotes extinction learning, but only when memory is recalled under stressful situations. Recent studies indicate that both environmental stress and the frustrative stress of withholding reward during extinction of drug self-administration induce similar neurochemical events in the NAc. These neurochemical events could impose a "state-dependency" on extinction learning such that subsequent exposure to stress acts as a cue to enhance retrieval of extinction memory. Our results suggest that extinction-induced up-regulation in NAc AMPA receptors acts reciprocally to facilitate state-dependent extinction learning, as stressful situations evoke extinction memories that exert powerful inhibitory control over drug-seeking behaviour. These results may have important therapeutic implications for behaviour-based approaches aimed at treating drug addiction.

  14. Effects of single moor baths on physiological stress response and psychological state: a pilot study

    Science.gov (United States)

    Stier-Jarmer, M.; Frisch, D.; Oberhauser, C.; Immich, G.; Kirschneck, M.; Schuh, A.

    2017-06-01

    Moor mud applications in the form of packs and baths are widely used therapeutically as part of balneotherapy. They are commonly given as therapy for musculoskeletal disorders, with their thermo-physical effects being furthest studied. Moor baths are one of the key therapeutic elements in our recently developed and evaluated 3-week prevention program for subjects with high stress level and increased risk of developing a burnout syndrome. An embedded pilot study add-on to this core project was carried out to assess the relaxing effect of a single moor bath. During the prevention program, 78 participants received a total of seven moor applications, each consisting of a moor bath (42 °C, 20 min, given between 02:30 and 05:20 p.m.) followed by resting period (20 min). Before and after the first moor application in week 1, and the penultimate moor application in week 3, salivary cortisol was collected, blood pressure and heart rate were measured, and mood state (Multidimensional Mood State Questionnaire) was assessed. A Friedman test of differences among repeated measures was conducted. Post hoc analyses were performed using the Wilcoxon signed-rank test. A significant decrease in salivary cortisol concentration was seen between pre- and post-moor bath in week 1 (Z = -3.355, p = 0.0008). A non-significant decrease was seen between pre- and post-moor bath in week 3. Mood state improved significantly after both moor baths. This pilot study has provided initial evidence on the stress-relieving effects of single moor baths, which can be a sensible and recommendable therapeutic element of multimodal stress-reducing prevention programs. The full potential of moor baths still needs to be validated. A randomized controlled trial should be conducted comparing this balneo-therapeutic approach against other types of stress reduction interventions.

  15. Effects of single moor baths on physiological stress response and psychological state: a pilot study

    Science.gov (United States)

    Stier-Jarmer, M.; Frisch, D.; Oberhauser, C.; Immich, G.; Kirschneck, M.; Schuh, A.

    2017-11-01

    Moor mud applications in the form of packs and baths are widely used therapeutically as part of balneotherapy. They are commonly given as therapy for musculoskeletal disorders, with their thermo-physical effects being furthest studied. Moor baths are one of the key therapeutic elements in our recently developed and evaluated 3-week prevention program for subjects with high stress level and increased risk of developing a burnout syndrome. An embedded pilot study add-on to this core project was carried out to assess the relaxing effect of a single moor bath. During the prevention program, 78 participants received a total of seven moor applications, each consisting of a moor bath (42 °C, 20 min, given between 02:30 and 05:20 p.m.) followed by resting period (20 min). Before and after the first moor application in week 1, and the penultimate moor application in week 3, salivary cortisol was collected, blood pressure and heart rate were measured, and mood state (Multidimensional Mood State Questionnaire) was assessed. A Friedman test of differences among repeated measures was conducted. Post hoc analyses were performed using the Wilcoxon signed-rank test. A significant decrease in salivary cortisol concentration was seen between pre- and post-moor bath in week 1 ( Z = -3.355, p = 0.0008). A non-significant decrease was seen between pre- and post-moor bath in week 3. Mood state improved significantly after both moor baths. This pilot study has provided initial evidence on the stress-relieving effects of single moor baths, which can be a sensible and recommendable therapeutic element of multimodal stress-reducing prevention programs. The full potential of moor baths still needs to be validated. A randomized controlled trial should be conducted comparing this balneo-therapeutic approach against other types of stress reduction interventions.

  16. Experimental studies the evolution of stress-strain state in structured rock specimens under uniaxial loading

    Science.gov (United States)

    Oparin, Viktor; Tsoy, Pavel; Usoltseva, Olga; Semenov, Vladimir

    2014-05-01

    The aim of this study was to analyze distribution and development of stress-stress state in structured rock specimens subject to uniaxial loading to failure. Specific attention was paid to possible oscillating motion of structural elements of the rock specimens under constraints (pre-set stresses at the boundaries of the specimens) and the kinetic energy fractals. The detailed studies into the micro-level stress-strain state distribution and propagation over acting faces of rock specimens subject to uniaxial loading until failure, using automated digital speckle photography analyzer ALMEC-tv, have shown that: • under uniaxial stiff loading of prismatic sandstone, marble and sylvinite specimens on the Instron-8802 servohydraulic testing machine at the mobile grip displacement rate 0.02-0.2 mm/min, at a certain level of stressing, low-frequency micro-deformation processes originate in the specimens due to slow (quasi-static) force; • the amplitude of that deformation-wave processes greatly depends on the micro-loading stage: — at the elastic deformation stage, under the specimen stress lower than half ultimate strength of the specimen, there are no oscillations of microstrains; —at the nonlinearly elastic deformation stage, under stress varied from 0.5 to 1 ultimate strength of the specimens, the amplitudes of microstrains grow, including the descending stage 3; the oscillation frequency f=0.5-4 Hz; —at the residual strength stage, the amplitudes of the microstrains drop abruptly (3-5 times) as against stages 2 and 3; • in the elements of the scanned specimen surface in the region with the incipient crack, the microstrain rate amplitudes are a few times higher than in the undamged surface region of the same specimen. Sometimes, deformation rate greatly grows with increase in the load. The authors have used the energy scanning function of the deformation-wave processes in processing experimental speckle-photography data on the surface of the test specimen

  17. Characterization of the hydrogeology and stress state in the vicinity of the homestake mine, Lead, SD

    Science.gov (United States)

    Ebenhack, Johnathan Foss

    Underground workings in fractured rock are common worldwide. They have applications in numerous areas and fields of study. These include mining operations, civil engineering projects like tunnels and underground facilities, and research projects that require underground laboratories such as the physics research being conducted by Sanford Laboratory at the former Homestake mine and Fermi Laboratory near Chicago (Bahcall et al. 2001, Elsworth 2009, Sadoulet et al. 2006, bge science DUSEL, fnal.gov). These excavations can reach several kilometers in depth including the 3.9 km deep TauTona mine in South Africa, the 3 km deep LaRonde mine in Quebec and the 2.4 km deep Homestake mine in South Dakota. Large quantities of rock are removed when constructing deep excavations, for example Rahn and Roggenthen (2002) estimated the total volume of rock removed from the Homestake mine to be 2.1x107 m3. Removing large volumes of rock alters the local stress state and ground water flow, potentially increasing risks to workers and the environment (Kaiser et al. 2008, Blodgett et al. 2002, Lucier et al. 2009, Goldbach 2010, Kang et al. 2010). The objective of this research is to develop a better understanding of how deep rock excavations can alter groundwater flow, stress state, and deformation in the rock that envelopes them. The approach is to evaluate how the hydraulic head, flow paths and stress state have been affected by excavation at the Homestake mine in Lead, South Dakota, one of the deepest mines in North America. The Homestake mine was selected as a focus of this research because it has recently been evaluated as the site of a deep underground research laboratory where an understanding of the groundwater flow and stress state was needed to plan underground experiments. The investigation includes poroelastic modeling of the Homestake mine using available geologic and geophysical data and mine records. Results from the analyses indicate that mining and dewatering have

  18. Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

    Science.gov (United States)

    Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner

    2018-01-01

    The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young's moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.

  19. Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

    Science.gov (United States)

    Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner

    2017-11-01

    The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young's moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.

  20. Application of nonlinear ultrasonic method for monitoring of stress state in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyu Jin; Kwak, Hyo Gyoung [Dept. of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Park, Sun Jong [Dept. of Structural System and Site Safety Evaluation, Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-04-15

    As the lifespan of concrete structures increases, their load carrying capacity decreases owing to cyclic loads and long-term effects such as creep and shrinkage. For these reasons, there is a necessity for stress state monitoring of concrete members. Particularly, it is necessary to evaluate the concrete structures for behavioral changes by using a technique that can overcome the measuring limitations of usual ultrasonic nondestructive evaluation methods. This paper proposes the use of a nonlinear ultrasonic method, namely, nonlinear resonant ultrasonic spectroscopy (NRUS) for the measurement of nonlinearity parameters for stress monitoring. An experiment compared the use of NRUS method and a linear ultrasonic method, namely, ultrasonic pulse velocity (UPV) to study the effects of continuously increasing loads and cyclic loads on the nonlinearity parameter. Both NRUS and UPV methods found a similar direct relationship between load level and that parameter. The NRUS method showed a higher sensitivity to micro-structural changes of concrete than UPV method. Thus, the experiment confirms the possibility of using the nonlinear ultrasonic method for stress state monitoring of concrete members.

  1. Reliability assessment of stress concentration performance state for a perforated composite plate under traction

    Directory of Open Access Journals (Sweden)

    Jabbouri A.

    2012-07-01

    Full Text Available Considering a perforated sandwich plate made from two elastic homogenous and isotropic layers, and having a square hole, reliability assessment of stress concentration limit state for which the stress should not exceed a given threshold is performed in this work. Assuming that the plate dimensions and the applied loading are deterministic, focus is done on the square hole centre position and edge length considered to be random variables. The means and the standard deviations of these variables are assumed to be known, but no information is so far available about their densities of probabilities. To assess reliability of the performance state, reliability analysis known methods are applied to a response surface representation of the stress concentration factor of the perforated plate which is obtained through quadratic polynomial regression of finite element results. A parametric study is performed regarding the influence of the distributions of probabilities chosen to model the hole dimensions uncertainties. It is shown that the probability of failure depends largely on the selected densities of probabilities.

  2. The postearthquake stress state on the Tohoku megathrust as constrained by reanalysis of the JFAST breakout data

    Science.gov (United States)

    Brodsky, Emily E.; Saffer, Demian; Fulton, Patrick; Chester, Frederick; Conin, Marianne; Huffman, Katelyn; Moore, J. Casey; Wu, Hung-Yu

    2017-08-01

    The Japan Trench Fast Drilling Project (JFAST) endeavored to establish the stress state on the shallow subduction megathrust that slipped during the M9 Tohoku earthquake. Borehole breakout data from the drill hole can constrain both the orientation and magnitude of the principal stresses. Here we reanalyze those data to refine our understanding of the stress state on the fault. In particular, we (1) improve the identification of breakouts, (2) consider a fuller range of stress states consistent with the data, and (3) incorporate new and more robust laboratory constraints on rock strength. The original conclusion that the region is in a normal faulting regime after the earthquake is strengthened by the new analysis. The combined analysis suggests that the earthquake released sufficient elastic strain energy to reset the local stress field.

  3. Emotional affective states (depression, anxiety and stress of nursing in a mexican public health sector

    Directory of Open Access Journals (Sweden)

    Blanca García-Rivera

    2014-03-01

    Full Text Available This study is a descriptive correlational cross-sectional approach with a non-experimental design about emotional affective states related dissorders in Mexican public health workers. It´s goal was to identify the existence of significant differences between gender and emotional affective state (depression, anxiety and stress for workers in a hospital located in Ensenada, Baja California in north-western Mexico. The work covers a sample of 130 employees. To collection of data used a DASS-21 scale. The results identified an emotional affective state within a normal range. No statistically differences in gender were identified. Positive and significant correlations between subscales of the DASS-21 were found.

  4. Assessment of Creep Deformation, Damage, and Rupture Life of 304HCu Austenitic Stainless Steel Under Multiaxial State of Stress

    Science.gov (United States)

    Sahoo, K. C.; Goyal, Sunil; Parameswaran, P.; Ravi, S.; Laha, K.

    2018-01-01

    The role of the multiaxial state of stress on creep deformation and rupture behavior of 304HCu austenitic stainless steel was assessed by performing creep rupture tests on both smooth and notched specimens of the steel. The multiaxial state of stress was introduced by incorporating circumferential U-notches of different root radii ranging from 0.25 to 5.00 mm on the smooth specimens of the steel. Creep tests were carried out at 973 K over the stress range of 140 to 220 MPa. In the presence of notch, the creep rupture strength of the steel was found to increase with the associated decrease in rupture ductility. Over the investigated stress range and notch sharpness, the strengthening was found to increase drastically with notch sharpness and tended toward saturation. The fractographic studies revealed the mixed mode of failure consisting of transgranular dimples and intergranular creep cavitation for shallow notches, whereas the failure was predominantly intergranular for relatively sharper notches. Detailed finite element analysis of stress distribution across the notch throat plane on creep exposure was carried out to assess the creep failure of the material in the presence of notch. The reduction in von-Mises stress across the notch throat plane, which was greater for sharper notches, increased the creep rupture strength of the material. The variation in fracture behavior of the material in the presence of notch was elucidated based on the von-Mises, maximum principal, and hydrostatic stresses. Electron backscatter diffraction analysis of creep strain distribution across the notch revealed localized creep straining at the notch root for sharper notches. A master curve for predicting creep rupture life under the multiaxial state of stress was generated considering the representative stress having contributions from both the von-Mises and principal stress components of the stress field in the notch throat plane. Rupture ductility was also predicted based on the

  5. Effect of Magnolia officinalis and Phellodendron amurense (Relora®) on cortisol and psychological mood state in moderately stressed subjects.

    Science.gov (United States)

    Talbott, Shawn M; Talbott, Julie A; Pugh, Mike

    2013-08-07

    Magnolia (Magnolia officinalis) and Phellodendron (Phellodendron amurense) barks are medicinal plants commonly used as traditional remedies for reducing stress and anxiety. Modern dietary supplements are intended to induce relaxation and reduce stress as well as stress-related eating. Previous studies have shown the combination of Magnolia/Phellodendron (MP) to reduce both cortisol exposure and the perception of stress/anxiety, while improving weight loss in subjects with stress-related eating. Competitive athletes are "stressed" by their intense exercise regimens in addition to their normal activities of daily living and thus may benefit from a natural therapy intended to modulate baseline perceptions of stress and stress hormone exposure. We assessed salivary cortisol exposure and psychological mood state in 56 subjects (35 men and 21 women) screened for moderate stress and supplemented with a standardized/patented MP combination (Relora®, Next Pharmaceuticals) or Placebo for 4 weeks. After 4 weeks of supplementation, salivary cortisol exposure was significantly (pStress (-11%), Tension (-13%), Depression (-20%), Anger (-42%), Fatigue (-31%), and Confusion (-27%), and higher indices of Global Mood State (+11%) and Vigor (+18%). These results indicate that daily supplementation with a combination of Magnolia bark extract and Phellodendron bark extract (Relora®) reduces cortisol exposure and perceived daily stress, while improving a variety of mood state parameters, including lower fatigue and higher vigor. These results suggest an effective natural approach to modulating the detrimental health effects of chronic stress in moderately stressed adults. Future studies should examine the possible performance and recovery benefits of Relora supplementation in athletes overstressed by the physical and psychological demands of training and competition.

  6. Efficacy of single-session abreactive ego state therapy for combat stress injury, PTSD, and ASD.

    Science.gov (United States)

    Barabasz, Arreed; Barabasz, Marianne; Christensen, Ciara; French, Brian; Watkins, John G

    2013-01-01

    Using abreactive Ego State Therapy (EST), 36 patients meeting DSM-IV-TR and PTSD checklist (PCL) criteria were exposed to either 5-6 hours of manualized treatment or placebo in a single session. EST emphasizes repeated hypnotically activated abreactive "reliving" of the trauma experience combined with therapists' ego strength. Both the placebo and EST treatment groups showed significant reductions in PTSD checklist scores immediately posttreatment (placebo: mean 17.34 points; EST: mean 53.11 points) but only the EST patients maintained significant treatment effect at 4-week and 16- to 18-week follow-ups. Abreactive EST appears to be an effective and durable treatment for PTSD inclusive of combat stress injury and acute stress disorder.

  7. Two Temperature Magneto-Thermoelasticity with Initial Stress: State Space Formulation

    Directory of Open Access Journals (Sweden)

    Sunita Deswal

    2013-01-01

    Full Text Available Magneto-thermoelastic interactions in an initially stressed isotropic homogeneous elastic half-space with two temperatures are studied using mathematical methods under the purview of the L-S model of linear theory of generalized thermoelasticity. The formalism deals with the state space approach with the purpose of counteracting the difficulties of handling the displacement potential functions. Of specific concern here is the propagation of waves owing to ramp type increase in temperature and load. The medium is considered to be permeated by a uniform magnetic field. The expressions for different field parameters such as displacement, temperature, strain, and stress in the physical domain are obtained by applying a numerical inversion technique. Results of some earlier workers have been deduced from the present formulation. Numerical work is also performed for a suitable material with the aim of illustrating the results.

  8. A vibrating membrane bioreactor operated at supra- and sub-critical flux: Influence of extracellular polymeric substances from yeast cells

    DEFF Research Database (Denmark)

    Beier, Søren Prip; Jonsson, Gunnar Eigil

    2007-01-01

    A vibrating membrane bioreactor, in which the fouling problems are reduced by vibrating a hollow fiber membrane module, has been tested in constant flux microfiltration above (supra-critical) and below (sub-critical) an experimentally determined critical flux. Suspensions of bakers yeast cells were....... Filtration just below the critical flux (sub-critical) seems to be a good compromise between acceptable flux level and acceptable increase of fouling resistance and trans-membrane pressure (TMP) in a given time period. EPS from the yeast cells causes the membrane module to foul and part of the fouling...... is continually washed out during supra-critical flux operation whereas the washing out at sub-critical flux operation is not observed. This might be due to locally different hydrodynamic conditions at the membrane surface and pore entrances at supra- and sub-critical flux respectively....

  9. Stress-free states of continuum dislocation fields : Rotations, grain boundaries, and the Nye dislocation density tensor

    NARCIS (Netherlands)

    Limkumnerd, Surachate; Sethna, James P.

    We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose

  10. Relationships among Career and Life Stress, Negative Career thoughts, and Career Decision State: A Cognitive Information Processing Perspective

    Science.gov (United States)

    Bullock-Yowell, Emily; Peterson, Gary W.; Reardon, Robert C.; Leierer, Stephen J.; Reed, Corey A.

    2011-01-01

    According to cognitive information processing theory, career thoughts mediate the relationship between career and life stress and the ensuing career decision state. Using a sample of 232 college students and structural equation modeling, this study found that an increase in career and life stress was associated with an increase in negative career…

  11. The psychoemotional status and cardiovascular system functional state of the first-year students under the influence of examination stress

    National Research Council Canada - National Science Library

    Liliana K. Tokaeva; Svetlana S. Parshina; S.S. Pavlenkovich

    2012-01-01

    The aim of this research is to study of the influence of examination stress on psycho-emotional status and functional state of the cardiovascular system of the 1-st year students of pedagogical high school. Methods...

  12. Creep properties of phosphorus alloyed oxygen free copper under multiaxial stress state

    Energy Technology Data Exchange (ETDEWEB)

    Rui Wu; Sandstroem, Rolf; Seitisleam, Facredin

    2009-10-15

    Phosphorus alloyed oxygen free copper (Cu-OFP) canisters are planned to be used for spent nuclear fuel in Sweden. The copper canisters will be subjected to creep under multiaxial stress states in the repository. Creep tests have therefore been carried out at 75 deg C using double notch specimens with notch acuities of 0.5, 2, 5, and 18.8, respectively. The creep lifetime for notched specimens is considerably longer than that for the smooth one at a given net section stress, indicating that the investigated Cu-OFP is notch insensitive (notch strengthening). The notch strengthening factor in time is, for instance, greater than 70 at 180 MPa for the bluntest notch (notch acuity = 0.5). The creep lifetime is notch acuity dependent. The sharper the notch, the longer the creep lifetime is. The creep deformation is to a significant extent concentrated to the region around the notches. Different deformation on the two notches is observed. Both axial and radial strains on the failed notch are several times larger than those on the unbroken one. Linear relation between the axial and the radial strains on the notches is found. Transgranular failure is predominant, independent of stress, rupture time, and notch acuity. Adjacent to fracture, elongated grains along the stress direction, separate pores and cavities are often visible. On the unbroken notch, fewer separate cavities and cracks are only seen intergranularly for the sharper notches (notch acuity > 2). To interpret the tests for the notched creep specimens, finite element computations have been performed. A fundamental model for primary and secondary creep without fitting parameters has been used as constitutive equation. The FEM-modelling could represent the creep strain versus time curves for the notched specimens in a satisfactory way. In these curves the strain on loading is included. From the FEM-computations a stationary creep stress could be assessed, which is close to the reference stress. For a given

  13. Oxidative Stress State Is Associated with Left Ventricular Mechanics Changes, Measured by Speckle Tracking in Essential Hypertensive Patients

    OpenAIRE

    Luis Antonio Moreno-Ruíz; David Ibarra-Quevedo; Erika Rodríguez-Martínez; Maldonado, Perla D.; Benito Sarabia-Ortega; José Gustavo Hernández-Martínez; Beda Espinosa-Caleti; Beatriz Mendoza-Pérez; Selva Rivas-Arancibia

    2015-01-01

    The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS) and the left ventricular end diastolic pressure (LVEDP). Twenty-five patients with essential hypertension and 25 controls paired by age and gender were ...

  14. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  15. Measuring stress responses in female Geoffroy's spider monkeys: Validation and the influence of reproductive state.

    Science.gov (United States)

    Rodrigues, Michelle A; Wittwer, Dan; Kitchen, Dawn M

    2015-04-17

    Fecal glucocorticoid metabolites are increasingly used to investigate physiological stress. However, it is crucial for researchers to simultaneously investigate the effects of reproductive state because estradiol and placental hormones can affect circulating glucocorticoid concentrations. Reports on the relationships between glucocorticoids and reproductive state are inconsistent among females. Unlike several primate species that have heightened glucocorticoid activity during lactation, humans experience reduced glucocorticoid activity during lactation. Rather than a taxonomic difference, we hypothesize that this is a result of different environmental stressors, particularly the threat of infanticide. Here, we expand the number of wild primate species tested by validating a glucocorticoid assay for female Geoffroy's spider monkeys. We investigate the effects of reproductive state on their glucocorticoid concentrations. Utilizing a routine veterinary exam on a captive population, we determined that fecal glucocorticoid metabolites increase in response to a stressor (anesthesia), and this rise is detected approximately 24 hr later. Additionally, we found that extracted hormone patterns in a wild population reflected basic reproductive biology-estradiol concentrations were higher in cycling than lactating females, and in lactating females with older offspring who were presumably resuming their cycle. However, we found that estradiol and glucocorticoid concentrations were significantly correlated in lactating but not cycling females. Similarly, we found that reproductive state and estradiol concentration, but not stage of lactation, predicted glucocorticoid concentrations. Unlike patterns in several other primate species that face a relatively strong threat of infanticide, lactating spider monkeys experience reduced glucocorticoid activity, possibly due to attenuating effects of oxytocin and lower male-initiated aggression than directed at cycling females. More

  16. Dry fracture method for simultaneous measurement of in-situ stress state and material properties

    Energy Technology Data Exchange (ETDEWEB)

    Serata, S. [Serata Geomechanics, Inc., Richmond, CA (United States); Oka, S.; Kikuchi, S. [JDC Corp., Tokyo (Japan)

    1996-04-01

    Based on the dry fracture principle, a computerized borehole probe has been developed to measure stress state and material properties, simultaneously. The probe is designed to obtain a series of measurements in a continuing sequence along a borehole length, without any interruptive measures, such as resetting packers, taking indentation of borehole wall, overcoming, etc. The new dry fracture probe for the single fracture method is designed to overcome the difficulties posed by its ancestor which was based on the double fracture method. The accuracy of the single fracture method is confirmed by a close agreement with the theory, FE modeling and laboratory testing.

  17. Analysis of the stress and strain state of prestressed "V" beam

    OpenAIRE

    Stanič, Sandi

    2014-01-01

    In the thesis, we design and analyze a prestressed concrete "V" beam which is part of the roof structure of a reinforced prefabricated concrete hall. The beam is 28.08 m in length and 1.0 m in height. The beam is prestressed with 22 flat tendons and a part of them are neutralized on both ends. The calculation is made in accordance with the requirements of Standard SIST EN 1992-1-1:2005. In the first part of the thesis, we checked the stress and strain state of the beam for serviceability and ...

  18. Plastic flow rule for sands with friction, dilation, density and stress state coupling

    Directory of Open Access Journals (Sweden)

    Wojciechowski Marek

    2015-06-01

    Full Text Available In this paper we propose a flow rule and failure criterion for sands in plane strain conditions based on Drucker-Prager formulation and enhanced with empirical Houlsby formula, which couples friction, dilation, density and stress state in the material. The resulting elasto-plastic, non-associated, shear hardening material model is implemented as a numerical procedure in the frame of finite element method and a simple compression example is presented. Because of the empirical nature of Houlsby formula, it is believed that results of numerical simulations will be more realistic both in deformation and shear strength estimation of sands.

  19. Gmax for Sand by Bender Elements at Anisotropic Stress States

    DEFF Research Database (Denmark)

    Bødker, L.

    1996-01-01

    Analyses and design of foundations of structures exposed to dynamic loading requires knowledge of the dynamic proporties of the soils. An important parameter used in the dynamic analyses is the maximum shear modulus, Gmax. In the present study Gmax is determined by means of piezocheramic bender...... elements for two types of sand and with void ratios varying from minimum to maximum. The tests performed are carried out in the Danish Triaxial Cell, and Gmax are determined at different isotropic and anisotropic stress states. The main result of the test program is that Gmax is primarily influenced...

  20. STABILITY AND NATURAL VIBRATIONS OF INHOMOGENEOUS SHELLS TAKING INTO ACCOUNT THE STRESS STATE

    Directory of Open Access Journals (Sweden)

    Bazhenov V.A.

    2015-12-01

    Full Text Available The work is devoted to the problem of developing a unified methodology based on the efficient numerical analysis of problems of stability and natural vibrations of a wide class of inhomogeneous shells, thin and medium thickness. In problems of its natural vibrations takes into account the presence of a pre-stressed state of the structure from the action of static loads, which significantly affect the spectrum of natural vibrations and allows determining the bifurcation point and the value of the critical force of buckling by dynamic criteria.

  1. Investigation of stress-strain state in the flywheel and estimation their specific energy capacity

    Directory of Open Access Journals (Sweden)

    Berezhnoi Dmitri V.

    2017-01-01

    Full Text Available In this paper, the specific energy intensity of the kinetic energy storage devices, including the flywheel-casing scheme in the potential field, is investigated. The possibilities of using various structural materials in the manufacture of structural elements of a mechanical accumulator are analyzed, the stress-strain state of the flywheel and the casing under quasistatic increase in the rotational speed of the rotor part of the structure is investigated. It is noted that the presence of a potential field in the flywheel-casing system makes it possible to increase the specific energy intensity of the kinetic energy storage.

  2. Research Programme for the 660 Mev Proton Accelerator Driven MOX-Plutonium Subcritical Assembly

    CERN Document Server

    Barashenkov, V S; Buttseva, G L; Dudarev, S Yu; Polanski, A; Puzynin, I V; Sissakian, A N

    2000-01-01

    The paper presents a research programme of the Experimental Acclerator Driven System (ADS), which employs a subcritical assembly and a 660 MeV proton acceletator operating at the Laboratory of Nuclear Problems of the JINR, Dubna. MOX fuel (25% PuO_2 + 75% UO_2) designed for the BN-600 reactor use will be adopted for the core of the assembly. The present conceptual design of the experimental subcritical assembly is based on a core of a nominal unit capacity of 15 kW (thermal). This corresponds to the multiplication coefficient k_eff = 0.945, energetic gain G = 30 and the accelerator beam power 0.5 kW.

  3. Tuning colloidal interactions in subcritical solvents by solvophobicity: explicit versus implicit modeling.

    Science.gov (United States)

    Dzubiella, J; Chakrabarti, J; Löwen, H

    2009-07-28

    The distance-resolved effective interaction between two colloidal particles in a subcritical solvent is explored both by an explicit and implicit modeling. An implicit solvent approach based on a simple thermodynamic interface model is tested against grand-canonical Monte Carlo computer simulations using explicit Lennard-Jones solvent molecules. Close to liquid-gas coexistence, a joint gas bubble surrounding the colloidal particle pair yields an effective attraction between the colloidal particles, the strength of which can be vastly tuned by the solvophobicity of the colloids. The implicit model is in good agreement with our explicit computer simulations, thus enabling an efficient modeling and evaluation of colloidal interactions and self-assembly in subcritical solvent environments.

  4. A fusion-driven subcritical system concept based on viable technologies

    Science.gov (United States)

    Wu, Y.; Jiang, J.; Wang, M.; Jin, M.; FDS Team

    2011-10-01

    A fusion-driven hybrid subcritical system (FDS) concept has been designed and proposed as spent fuel burner based on viable technologies. The plasma fusion driver can be designed based on relatively easily achieved plasma parameters extrapolated from the successful operation of existing fusion experimental devices such as the EAST tokamak in China and other tokamaks in the world, and the subcritical fission blanket can be designed based on the well-developed technologies of fission power plants. The simulation calculations and performance analyses of plasma physics, neutronics, thermal-hydraulics, thermomechanics and safety have shown that the proposed concept can meet the requirements of tritium self-sufficiency and sufficient energy gain as well as effective burning of nuclear waste from fission power plants and efficient breeding of nuclear fuel to feed fission power plants.

  5. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2017-02-01

    Full Text Available Electrothermal energy storage (ETES provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analysis results show that the extremum principle of entransy dissipation is an effective criterion for the optimization, and the optimum heat transfer for different cases with the same mass flux or pressure has been discussed. The optimum heat transfer can be achieved by adjusting the mass flux and pressure of the working fluid. It also reveals that with the increase of mass flux, there is a minimum exergy in the range under consideration, and the exergy decreases with the increase of the pressure.

  6. Determination of subcriticality and effective source strength by source drop and jerk experiments

    Energy Technology Data Exchange (ETDEWEB)

    Taninaka, Hiroshi [Interdisciplinary Graduate School of Science and Technology, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan); Hashimoto, Kengo [Atomic Energy Research Institute, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2008-07-01

    This paper presents applicability of least squares inverse kinetics method (LSIKM) to source drop and source jerk experiments. The LSIKM can estimate both reactivity and source strength by applying least square approximation to a correlation between time-sequence count data and inverse kinetics analysis data. The experiments were performed in the UTR-KINKI reactor to demonstrate the applicability of the LSIKM. To source jerk data, for comparison, conventional integral method is also applied. In the subcriticality and source strength obtained by the LSIKM, spatial dependence is slightly observed. However, the integral method leads to significant spatial dependence. The sub-criticalities inferred from source drop data are consistent with the results from source jerk data. (authors)

  7. Influence of moderator to fuel ratio (MFR) on burning thorium in a subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowski, Andrzej, E-mail: andrzej.wojciechowski@ncbj.gov.pl [National Center for Nuclear Research, Otwock-Swierk (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2014-10-15

    The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical reactor assembly is presented as a function of MFR, burnup, power density (PD) and fissile concentration. The calculated model is based on subcritical assembly which makes configuration of fuel rods and volumes of moderator and coolant changes possible. This comfortable assembly enables investigation of CR in a thorium cycle for different value of MFR. Additionally, the calculation results of U-233 saturation concentration are explained by mathematical model. The value of MFR main influences the saturation concentration of U-233 and fissile and the fissile concentration dependence of CR. The saturation value of CR is included in the range CR ∈ (0.911, 0.966) and is a slowly increasing function of MFR. The calculations were done with a MCNPX 2.7 code.

  8. Subcritical ethanol extraction of flavonoids from Moringa oleifera leaf and evaluation of antioxidant activity.

    Science.gov (United States)

    Wang, Yongqiang; Gao, Yujie; Ding, Hui; Liu, Shejiang; Han, Xu; Gui, Jianzhou; Liu, Dan

    2017-03-01

    A large-scale process to extract flavonoids from Moringa oleifera leaf by subcritical ethanol was developed and HPLC-MS analysis was conducted to qualitatively identify the compounds in the extracts. To optimize the effects of process parameters on the yield of flavonoids, a Box-Behnken design combined with response surface methodology was conducted in the present work. The results indicated that the highest extraction yield of flavonoids by subcritical ethanol extraction could reach 2.60% using 70% ethanol at 126.6°C for 2.05h extraction. Under the optimized conditions, flavonoids yield was substantially improved by 26.7% compared with the traditional ethanol reflux method while the extraction time was only 2h, and obvious energy saving was observed. FRAP and DPPH assays showed that the extracts had strong antioxidant and free radical scavenging activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Coupling of subcritical methanol with acidic ionic liquids for the acidity reduction of naphthenic acids

    Directory of Open Access Journals (Sweden)

    Zafar Faisal

    2017-09-01

    Full Text Available The presence of naphthenic acids (NAs in crude oil is the major cause of corrosion in the refineries and its processing equipment. The goal of this study is to reduce the total acid number (TAN of NAs by treating them with subcritical methanol in the presence of acidic ionic liquid (AIL catalysts. Experiments were carried out in an autoclave batch reactor and the effect of different reaction parameters was investigated. It was observed that TAN reduction was positively dependent on the temperature and concentration of the AIL whereas excess of methanol has a negative effect. Approximately 90% TAN reduction was achieved under the optimized reaction conditions using [BMIM]HSO4 as catalyst. It was also perceived from the experimental results that the AILs with longer alkyl chain exhibited higher catalytic activity. The activity and stability of AIL showed that they can be promising catalyst to esterify NAs under subcritical methanol.

  10. Enhanced enzymatic cellulose hydrolysis by subcritical carbon dioxide pretreatment of sugarcane bagasse.

    Science.gov (United States)

    Zhang, Hongdan; Wu, Shubin

    2014-04-01

    Most biomass pretreatment processes for sugar production are run at low-solid concentration (carbon dioxide (CO2) could provide a more sustainable pretreatment medium while using relative high-solid contents (15 wt.%). The effects of subcritical CO2 pretreatment of sugarcane bagasse to the solid and glucan recoveries at different pretreatment conditions were investigated. Subsequently, enzymatic hydrolysis at different hydrolysis time was applied to obtain maximal glucose yield, which can be used for ethanol fermentation. The maximum glucose yield in enzyme hydrolyzate reached 38.5 g based on 100g raw material after 72 h of enzymatic hydrolysis, representing 93.0% glucose in sugarcane bagasse. The enhanced digestibilities of subcritical CO2 pretreated sugarcane bagasse were due to the removal of hemicellulose, which were confirmed by XRD, FTIR, SEM, and TGA analyses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Equilibria of ternary system acetic acid-water-CO2 under subcritical conditions

    DEFF Research Database (Denmark)

    Gutierrez, Jose M. Jimenez; Mussatto, Solange I.; Tsou, Joana

    in a very wide range of applications. However, those conditions, especially the levels of high pressure required at larger scale, involve certain equipment limitations. An alternative to overcome those restrictions is to use subcritical carbon dioxide. In order to understand the different systems......) of the ternary system HAc—H2O—CO2 at different subcritical conditions. A proposed computer model could be validated with experimental data, leading to a certain degree of adjustment due to specific factors, such as the binary interaction parameter kij, used in the model based on the Peng-Robinson EoS coupled...... it will be returned to the atmosphere (as part of the carbon cycle), CO2 is an inexpensive and clean source with numerous industrial applications in diverse fields: from chemical processes to biotechnological purposes [1]. Many of these studies have been focused on supercritical CO2, due to its broad potential uses...

  12. The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes. Review of sources and main parameters.

    Science.gov (United States)

    Marcet, Ismael; Álvarez, Carlos; Paredes, Benjamín; Díaz, Mario

    2016-03-01

    Food industry processing wastes are produced in enormous amounts every year, such wastes are usually disposed with the corresponding economical cost it implies, in the best scenario they can be used for pet food or composting. However new promising technologies and tools have been developed in the last years aimed at recovering valuable compounds from this type of materials. In particular, sub-critical water hydrolysis (SWH) has been revealed as an interesting way for recovering high added-value molecules, and its applications have been broadly referred in the bibliography. Special interest has been focused on recovering protein hydrolysates in form of peptides or amino acids, from both animal and vegetable wastes, by means of SWH. These recovered biomolecules have a capital importance in fields such as biotechnology research, nutraceuticals, and above all in food industry, where such products can be applied with very different objectives. Present work reviews the current state of art of using sub-critical water hydrolysis for protein recovering from food industry wastes. Key parameters as reaction time, temperature, amino acid degradation and kinetic constants have been discussed. Besides, the characteristics of the raw material and the type of products that can be obtained depending on the substrate have been reviewed. Finally, the application of these hydrolysates based on their functional properties and antioxidant activity is described. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Parenting stress as a mediator of parents' negative mood state and behavior problems in children with newly diagnosed cancer.

    Science.gov (United States)

    van der Geest, Ivana M; van den Heuvel-Eibrink, Marry M; Passchier, Jan; van den Hoed-Heerschop, Corry; Pieters, Rob; Darlington, Anne-Sophie E

    2014-07-01

    The aim was to investigate the influence of parents' negative mood state and parenting stress on behavior in children with newly diagnosed cancer. A total of 123 parents (n=58 fathers, n=65 mothers) of 67 children with newly diagnosed cancer completed three questionnaires separately at the same time measuring parents' negative mood state, parenting stress, and child behavior problems. Parents' negative mood state was weakly correlated to more child behavior problems (r=0.31, pparenting stress were strongly correlated to more child behavior problems (r=0.61, pparents' negative mood state and child behavior problems (c=0.29, p=0.02 (fathers); c=0.25, p=0.04 (mothers)) became non-significant after mediating for parenting stress (c'=0.003, p=0.98 (fathers); c'=0.10, p=0.42 (mothers)). The indirect effect of parents' negative mood state and child behavior problems was only significant for fathers (95% CI [0.12; 0.51]), indicating that parenting stress mediates the effect between fathers' negative mood state and child behavior problems. This is the first study to demonstrate the mediational role of parenting stress in fathers of a child with newly diagnosed cancer. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Sub-Critical Closed String Field Theory in D Less Than 26

    OpenAIRE

    Kaku, Michio

    1993-01-01

    We construct the second quantized action for sub-critical closed string field theory with zero cosmological constant in dimensions $ 2 \\leq D < 26$, generalizing the non-polynomial closed string field theory action proposed by the author and the Kyoto and MIT groups for $D = 26$. The proof of gauge invariance is considerably complicated by the presence of the Liouville field $\\phi$ and the non-polynomial nature of the action. However, we explicitly show that the polyhedral vertex functions ob...

  15. Sensitivity Analysis of Core Neutronic Parameters in Electron Accelerator-driven Subcritical Advanced Liquid Metal Reactor

    OpenAIRE

    Ebrahimkhani, Marziye; Hassanzadeh, Mostafa; Feghhi, Sayed Amier Hossian; Masti, Darush

    2016-01-01

    Calculation of the core neutronic parameters is one of the key components in all nuclear reactors. In this research, the energy spectrum and spatial distribution of the neutron flux in a uranium target have been calculated. In addition, sensitivity of the core neutronic parameters in accelerator-driven subcritical advanced liquid metal reactors, such as electron beam energy (Ee) and source multiplication coefficient (ks), has been investigated. A Monte Carlo code (MCNPX_2.6) has been used to ...

  16. Subcritical mineralization of sodium salt of dodecyl benzene sulfonate using sonication-wet oxidation (SONIWO) technique.

    Science.gov (United States)

    Dhale, A D; Mahajani, V V

    2001-06-01

    Subcritical mineralization of sodium salt of dodecyl benzene sulfonate via hybrid process-sonication followed by wet oxidation (SONIWO) has been investigated. Sonication of the compound enhanced the rates and % COD reduction during wet oxidation. In this process, homogenous CuSO4 catalyst was found to be effective. In wet oxidation studies, phenol, hydroquinone, maleic acid, oxalic acid, propionic acid, and acetic acid were identified as intermediates. The global rate equations for wet oxidation in terms of COD reduction were developed.

  17. Experimental studies of the stress state of the surface layer of detailat treatment with submerged jets

    Directory of Open Access Journals (Sweden)

    Олександр Олександрович Анділахай

    2015-03-01

    Full Text Available In the instrument and electrical industry was the use of the method of abrasive machining submerged jet, which is the most promising method for abrasive blasting of small parts of low stiffness. This method eliminates the main drawback сhip plants - abrasion channel nozzles or injection nozzles, but the state of the surface layer of machined parts are poorly understood and to make maximum use of the potential to provide the required quality parameters. The study of the state of the surfaces of parts resulting from abrasive blasting traditional methods, dedicated work, which define quality indicators: microhardness depth residual stress, as well as their nature (compressive, tensile. However, known from the literature values correspond to the conditions of surface treatment of parts in a fixed state with an abrasive material through the feed nozzle, and therefore the dynamics of the interaction of a single abrasive grain and significantly different parts. The process in question, and different modes of processing characteristics of the abrasive grains. In the paper, a series of experimental studies designed to assess the state of machined surfaces of parts as a result of abrasion submerged jets. It is established that during the treatment the non-oriented disorderly traces overlay the abrasive grains on the treated surface, thereby forming a tight skin layer thickness of 4 - 5 micrometers. Processed surface gets cold working, as evidenced by the study of microhardness before and after abrasive machining in a free state submerged jets

  18. Transient analysis of subcritical/supercritical carbon dioxide based natural circulation loop with end heat exchangers: experimental study

    Science.gov (United States)

    Yadav, Ajay Kumar; Ramgopal, Maddali; Bhattacharyya, Souvik

    2017-09-01

    Carbon dioxide (CO2) based natural circulation loops (NCLs) has gained attention due to its compactness with higher heat transfer rate. In the present study, experimental investigations have been carried out to capture the transient behaviour of a CO2 based NCL operating under subcritical as well as supercritical conditions. Water is used as the external fluid in cold and hot heat exchangers. Results are obtained for various inlet temperatures (323-353 K) of water in the hot heat exchanger and a fixed inlet temperature (305 K) of cooling water in the cold heat exchanger. Effect of loop operating pressure (50-90 bar) on system performance is also investigated. Effect of loop tilt in two different planes (XY and YZ) is also studied in terms of transient as well as steady state behaviour of the loop. Results show that the time required to attain steady state decreases as operating pressure of the loop increases. It is also observed that the change in temperature of loop fluid (CO2) across hot or cold heat exchanger decreases as operating pressure increases.

  19. State of the Art Review: Depression, Stress, Anxiety, and Cardiovascular Disease.

    Science.gov (United States)

    Cohen, Beth E; Edmondson, Donald; Kronish, Ian M

    2015-11-01

    The notion that psychological states can influence physical health is hardly new, and perhaps nowhere has the mind-body connection been better studied than in cardiovascular disease (CVD). Recently, large prospective epidemiologic studies and smaller basic science studies have firmly established a connection between CVD and several psychological conditions, including depression, chronic psychological stress, posttraumatic stress disorder (PTSD), and anxiety. In addition, numerous clinical trials have been conducted to attempt to prevent or lessen the impact of these conditions on cardiovascular health. In this article, we review studies connecting depression, stress/PTSD, and anxiety to CVD, focusing on findings from the last 5 years. For each mental health condition, we first examine the epidemiologic evidence establishing a link with CVD. We then describe studies of potential underlying mechanisms and finally discuss treatment trials and directions for future research. © Published by Oxford University Press on behalf of American Journal of Hypertension Ltd 2015. This work is written by (a) US Government employees(s) and is in the public domain in the US.

  20. Carnosinase levels in aging brain: redox state induction and cellular stress response.

    Science.gov (United States)

    Bellia, Francesco; Calabrese, Vittorio; Guarino, Francesca; Cavallaro, Monia; Cornelius, Carolin; De Pinto, Vito; Rizzarelli, Enrico

    2009-11-01

    Carnosinase is a dipeptidase found almost exclusively in brain and serum. Its natural substrate carnosine, present at high concentration in the brain, has been proposed as an antioxidant in vivo. We investigated the role of carnosinase in brain aging to establish a possible correlation with age-related changes in cellular stress response and redox status. In addition, a stable HeLa cell line expressing recombinant human serum carnosinase CN1 was established. The enzyme was purified from transfected cells, and specific antibodies were produced against it. Brain expression of CN1, Hsp72, heme oxygenase-1, and thioredoxin reductase increased with age, with a maximal induction in hippocampus and substantia nigra, followed by cerebellum, cortex, septum, and striatum. Hsps induction was associated with significant changes in total SH groups, GSH redox state, carbonyls, and HNE levels. A positive correlation between decrease in GSH and increase in Hsp72 expression was observed in all brain regions examined during aging. Increased carnosinase activity in the brain can lead to decreased carnosine levels and GSH/GSSG ratio. These results, consistent with the current notion that oxidative stress and cellular damage are characteristic hallmarks of the aging process, sustain the critical role of cellular stress-response mechanisms as possible targets for novel antiaging strategies.

  1. Observation of subcritical geodesic acoustic mode excitation in the large helical device

    Science.gov (United States)

    Ido, T.; Itoh, K.; Lesur, M.; Osakabe, M.; Shimizu, A.; Ogawa, K.; Nishiura, M.; Yamada, I.; Yasuhara, R.; Kosuga, Y.; Sasaki, M.; Ida, K.; Inagaki, S.; Itoh, S.-I.; the LHD Experiment Group

    2017-07-01

    The abrupt and strong excitation of the geodesic acoustic mode (GAM) has been found in the large helical device (LHD), when the frequency of a chirping energetic particle-driven GAM (EGAM) approaches twice that of the GAM frequency. The temporal evolution of the phase relation between the abrupt GAM and the chirping EGAM is common in all events. The result indicates a coupling between the GAM and the EGAM. In addition, the nonlinear evolution of the growth rate of the GAM is observed, and there is a threshold in the amplitude of the GAM for the appearance of nonlinear behavior. A threshold in the amplitude of the EGAM for the abrupt excitation of the GAM is also observed. According to one theory (Lesur et al 2016 Phys. Rev. Lett. 116 015003, Itoh et al 2016 Plasma Phys. Rep. 42 418) the observed abrupt phenomenon can be interpreted as the excitation of the subcritical instability of the GAM. The excitation of a subcritical instability requires a trigger and a seed with sufficient amplitude. The observed threshold in the amplitude of the GAM seems to correspond with the threshold in the seed, and the threshold in the amplitude of the EGAM seems to correspond with the threshold in the magnitude of the trigger. Thus, the observed threshold supports the interpretation that the abrupt phenomenon is the excitation of a subcritical instability of the GAM.

  2. Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the time is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.

  3. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio [Universidad Simón Bolívar, Nuclear Physics Laboratory, Apdo 89000, Caracas 1080A (Venezuela, Bolivarian Republic of); Davila, Jesus [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  4. Stress-strain state analysis and optimization of rod system under periodic pulse load

    Directory of Open Access Journals (Sweden)

    Grebenyuk Grigory

    2018-01-01

    Full Text Available The paper considers the problem of analysis and optimization of rod systems subjected to combined static and periodic pulse load. As a result of the study the analysis method was developed based on traditional approach to solving homogeneous matrix equations of state and a special algorithm for developing a particular solution. The influence of pulse parameters variations on stress-strain state of a rod system was analyzed. Algorithms for rod systems optimization were developed basing on strength recalculation and statement and solution of optimization problem as a problem of nonlinear mathematical programming. Recommendations are developed for efficient organization of process for optimization of rod systems under static and periodic pulse load.

  5. Relation between zero-stress state and branching order of porcine left coronary arterial tree.

    Science.gov (United States)

    Frøbert, O; Gregersen, H; Bjerre, J; Bagger, J P; Kassab, G S

    1998-12-01

    The left common coronary arterial trees of eight pig hearts were dissected. The zero-stress state (the state of the organ when the external loads are removed) of the coronary arteries was determined by first cutting the arteries into short, ring-shaped segments perpendicular to the longitudinal axis of the blood vessel and then making a radial cut. This procedure caused the ring to open into a sector whose opening angle (theta), internal and external lengths (circumferences), and wall thickness were measured. Morphometric and theta data were organized in the framework of a diameter-defined Strahler system. We investigated 4 rings from the left common coronary artery (LCCA), 185 from the left anterior descending artery (LAD) and its branches, and 159 from the left circumflex artery (LCX) and its branches. The inner circumferences of the rings ranged over six orders for the LAD arterial tree and five orders for the LCX arterial tree, corresponding to a diameter range of about one order of magnitude for both arteries. theta demonstrates viscoelastic behavior and was measured 30 min after cutting. Our results show that the inner and outer circumference and the wall thickness increase as geometric sequences with the order number. theta is found to decrease linearly toward the smaller orders with a slope of 7.3 degrees/order in the range of the six largest orders. Strain calculations showed that the inner part of the arterial wall is in compression, whereas the outer part of the wall is in tension in the no-load (zero transmural pressure) state. This study provides basic data on the zero-stress state that are necessary for understanding the mechanics of the coronary artery.

  6. Analysis of the stress-strain state of New Exchequer combined damat static loads

    Directory of Open Access Journals (Sweden)

    Sainov Mikhail Petrovich

    Full Text Available In the article the authors analyze numerical modeling results of the stress-strain state of a combined dam created by construction of a higher rockfill dam with a reinforced concrete face behind the downstream face of the concrete dam. The analysis was conducted on the example of the design of 150 meter high New Exchequer dam (USA. Numerical modeling was conducted with consideration of non-linearity of soils deformation as well as non-linear behavior of the interaction “concrete - soil”, “concrete - concrete”. The analysis showed that though in a combined dam the concrete part gets additional displacements and settlements, its stress state remains favorable without appearance of tensile stresses and opening of the contact “concrete - rock”. This is explained by the fact that on the top the concrete dam is weightened by the reservoir hydrostatic pressure. The role of rockfill lateral pressure on the concrete dam stress state is small. There may be expected sliding of soil in relation to the concrete dam downstream face due to the loss of its shear strength. Besides, decompaction of the contact "soil - concrete" may occur, as earthfill will have considerable displacements in the direction from the concrete dam. Due to this fact the loads from the earthfill weight do not actually transfer to the concrete dam. The most critical zone in the combined dam is the interface of the reinforced concrete face with the concrete dam. Under the action of the hydrostatic pressure the earth-fill under the face will have considerable settlements and displacements, because soil slides in relation to the concrete dam downstream face. This results in considerable openings (10 cm and shear displacements (50 сm in the perimeter joint. The results of the numerical modeling are confirmed by the presence of seepage in New Exchequer dam, which led to the necessity of its repair. Large displacements do not allow using traditional sealing like copper water stops

  7. Baseline and post-stress seasonal changes in immunocompetence and redox state maintenance in the fishing bat Myotis vivesi

    Science.gov (United States)

    Ibáñez-Contreras, Alejandra; Miranda-Labra, Roxana U.; Flores-Martínez, José Juan

    2018-01-01

    Little is known of how the stress response varies when animals confront seasonal life-history processes. Antioxidant defenses and damage caused by oxidative stress and their link with immunocompetence are powerful biomarkers to assess animal´s physiological stress response. The aim of this study was A) to determine redox state and variation in basal (pre-acute stress) immune function during summer, autumn and winter (spring was not assessed due to restrictions in collecting permit) in the fish-eating Myotis (Myotis vivesi; Chiroptera), and B) to determine the effect of acute stress on immunocompetence and redox state during each season. Acute stress was stimulated by restricting animal movement for 6 and 12 h. The magnitude of the cellular immune response was higher during winter whilst that of the humoral response was at its highest during summer. Humoral response increased after 6 h of movement restriction stress and returned to baseline levels after 12 h. Basal redox state was maintained throughout the year, with no significant changes in protein damage, and antioxidant activity was modulated mainly in relation to variation to environment cues, increasing during high temperatures and decreasing during windy nights. Antioxidant activity increased after the 6 h of stressful stimuli especially during summer and autumn, and to a lesser extent in early winter, but redox state did not vary. However, protein damage increased after 12 h of stress during summer. Prolonged stress when the bat is engaged in activities of high energy demand overcame its capacity to maintain homeostasis resulting in oxidative damage. PMID:29293551

  8. Computer and experimental analyses of the stress state in the cement hip joint endoprosthesis body.

    Science.gov (United States)

    Tabaković, Slobodan; Grujić, Jovan; Zeljković, Milan; Blagojević, Zoran; Radojević, Bojan; Popović, Zoran; Zivković, Aleksandar; Stevanović, Vladan

    2014-11-01

    One of the possible complications after implantation of a cement hip-joint endoprosthesis is frac- ture in the endoprosthesis body. Fractures arise from overload or material fatigue of which an implant is made. The purpose of this research was to define the intensity of maximum stress and the positions of a critical cross-section in the endoprosthesis body. Unilaterally changing forces which act on the hip joint during walking as well as the loads result in flexible deformations of the endoprosthesis body. Biomechanical analysis of the forces acting on the hip joint determine their direction and intensity, whereas on the basis of Gruen's classification of the endoprosthesis body loosening the level of fixation is established. The bodies of cement hip joint endoprosthesis are made of cobalt-chromium-molybdenum (CoCrMo) alloy, suitable for vacuum casting, are submitted to the analysis. Analysis of the critical stress in the endoprosthesis body was performed on the endoprosthesis body by means of the finite element method. The experimental verification of the obtained results was carried out on the physical prototype under laboratory conditions. Computer analysis, by means of the finite element method, determined the stress state by calculation of the maximum Von Mises stress and critical cross-sections for different angles of the resultant force action. The results obtained by the computer and experimental method correlate and are comparable to the results of similar analyses conducted on various endoprosthesis types. The analyses described in the paper make the basis for improving the process designing of hip joint endoprostheses and their customization to each individual patient (custom made).

  9. Stress state dependence of in-reactor creep and swelling. Part 2: Experimental results

    Science.gov (United States)

    Hall, M. M., Jr.; Flinn, J. E.

    2010-01-01

    Irradiation creep constitutive equations, which were developed in Part I, are used here to analyze in-reactor creep and swelling data obtained ca. 1977-1979 as part of the US breeder reactor program. The equations were developed according to the principles of incremental continuum plasticity for the purpose of analyzing data obtained from a novel irradiation experiment that was conducted, in part, using Type 304 stainless steel that had been previously irradiated to significant levels of void swelling. Analyses of these data support an earlier observation that all stress states, whether tensile, compressive, shear or mixed, can affect both void swelling and interactions between irradiation creep and swelling. The data were obtained using a set of five unique multiaxial creep-test specimens that were designed and used for the first time in this study. The data analyses demonstrate that the constitutive equations derived in Part I provide an excellent phenomenological representation of the interactive creep and swelling phenomena. These equations provide nuclear power reactor designers and analysts with a first-of-its-kind structural analysis tool for evaluating irradiation damage-dependent distortion of complex structural components having gradients in neutron damage rate, temperature and stress state.

  10. Investigation on the Residual Stress State of Drawn Tubes by Numerical Simulation and Neutron Diffraction Analysis

    Directory of Open Access Journals (Sweden)

    Adele Carradò

    2013-11-01

    Full Text Available Cold drawing is widely applied in the industrial production of seamless tubes, employed for various mechanical applications. During pre-processing, deviations in tools and their adjustment lead to inhomogeneities in the geometry of the tubes and cause a gradient in residuals. In this paper a three dimensional finite element (3D-FE-model is presented which was developed to calculate the change in wall thickness, eccentricity, ovality and residual macro-stress state of the tubes, produced by cold drawing. The model simulates the drawing process of tubes, drawn with and without a plug. For finite element modelling, the commercial software package Abaqus was used. To validate the model, neutron strain imaging measurements were performed on the strain imaging instrument SALSA at the Institute Laue Langevin (ILL, Grenoble, France on a series of SF-copper tubes, drawn under controlled laboratory conditions, varying the drawing angle and the plug geometry. It can be stated that there is sufficient agreement between the finite element method (FEM-calculation and the neutron stress determination.

  11. Investigation on the Residual Stress State of Drawn Tubes by Numerical Simulation and Neutron Diffraction Analysis.

    Science.gov (United States)

    Palkowski, Heinz; Brück, Sebastian; Pirling, Thilo; Carradò, Adele

    2013-11-08

    Cold drawing is widely applied in the industrial production of seamless tubes, employed for various mechanical applications. During pre-processing, deviations in tools and their adjustment lead to inhomogeneities in the geometry of the tubes and cause a gradient in residuals. In this paper a three dimensional finite element (3D-FE)-model is presented which was developed to calculate the change in wall thickness, eccentricity, ovality and residual macro-stress state of the tubes, produced by cold drawing. The model simulates the drawing process of tubes, drawn with and without a plug. For finite element modelling, the commercial software package Abaqus was used. To validate the model, neutron strain imaging measurements were performed on the strain imaging instrument SALSA at the Institute Laue Langevin (ILL, Grenoble, France) on a series of SF-copper tubes, drawn under controlled laboratory conditions, varying the drawing angle and the plug geometry. It can be stated that there is sufficient agreement between the finite element method (FEM)-calculation and the neutron stress determination.

  12. Obesity-Associated Oxidative Stress: Strategies Finalized to Improve Redox State

    Science.gov (United States)

    Savini, Isabella; Catani, Maria Valeria; Evangelista, Daniela; Gasperi, Valeria; Avigliano, Luciana

    2013-01-01

    Obesity represents a major risk factor for a plethora of severe diseases, including diabetes, cardiovascular disease, non-alcoholic fatty liver disease, and cancer. It is often accompanied by an increased risk of mortality and, in the case of non-fatal health problems, the quality of life is impaired because of associated conditions, including sleep apnea, respiratory problems, osteoarthritis, and infertility. Recent evidence suggests that oxidative stress may be the mechanistic link between obesity and related complications. In obese patients, antioxidant defenses are lower than normal weight counterparts and their levels inversely correlate with central adiposity; obesity is also characterized by enhanced levels of reactive oxygen or nitrogen species. Inadequacy of antioxidant defenses probably relies on different factors: obese individuals may have a lower intake of antioxidant- and phytochemical-rich foods, such as fruits, vegetables, and legumes; otherwise, consumption of antioxidant nutrients is normal, but obese individuals may have an increased utilization of these molecules, likewise to that reported in diabetic patients and smokers. Also inadequate physical activity may account for a decreased antioxidant state. In this review, we describe current concepts in the meaning of obesity as a state of chronic oxidative stress and the potential interventions to improve redox balance. PMID:23698776

  13. The Autonomous Stress Indicator for Remotely Monitoring Power System State and Watching for Potential Instability

    Directory of Open Access Journals (Sweden)

    Geza Joos

    2009-02-01

    Full Text Available The proposed Autonomous Stress Indicator (ASI is a device that monitors the contents of the protection relays on a suspect weak power system bus and generates a performance level related to the degree of system performance degradation or instability. This gives the system operators some time (minutes to take corrective action. In a given operating area there would not likely be a need for an ASI on every bus. Note that the ASI does not trip any breakers; it is an INFORMATION ONLY device. An important feature is that the system operator can subsequently interrogate the ASI to determine the factor(s that led to the performance level that has been initially annunciated, thereby leading to a course of action. This paper traces the development of the ASI which is an ongoing project. The ASI could be also described as a stress-alert device whose function is to alert the System Operator of a stressful condition at its location. The characteristics (or essential qualities of this device are autonomy, selectivity, accuracy and intelligence. These will fulfill the requirements of the recommendation of the Canada –US Task Force in the August 2003 system collapse. Preliminary tests on the IEEE 39-bus model indicate that the concept has merit and development work is in progress. While the ASI can be applied to all power system operating conditions, its principal application is to the degraded state of the system where the System Operator must act to restore the system to the secure state before it migrates to a stage of collapse. The work of ASI actually begins with the Areas of Vulnerability and ends with the Predictive Module as described in detail in this paper. An application example of a degraded system using the IEEE 39-bus system is included.

  14. ANALYSIS OF STRESS STATE IN UPPER LAYER OF ROAD CONCRETE PAVEMENT WITH TEMPERATURE ACTION

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2017-01-01

    Full Text Available While being operated auto-road pavements are subjected to intensive mechanical impacts, ultraviolet ray irradiation, freeze-thaw temperatures, freezing and thawing, drying and moistening. Due to these actions various types of pavement distresses appear on the road pavement. The most significant and dangerous type of distresses is micro-cracks on the road surface. One of the main reasons for their formation is an action of weather and climatic factors that initiate large changes in temperature of coating surface and occurrence of large temperature gradients in the upper layer. In this context while designing and operating auto-roads it is rather essential to investigate a stress state in road surface which is caused by temperature action. Purpose of the described investigations is to determine permissible temperature gradients for cement-concrete pavements that exclude formation of micro-cracks on their surface and thickness of damaged surface layer. Calculations of road pavement have been carried out at various laws for temperature distribution in its depth. A finite difference method realized in PARUS software has been used for studying a stress state of cement-concrete auto-roads. Regularities for distribution of stresses in cement-concrete pavement of auto-roads have been obtained at various surface temperatures. Permissible temperature gradients in the upper pavement layer have been determined and thickness of the layer where micro-cracks are formed has been assessed in the paper. Strength criterion based on the process of micro-crack formation and development in the concrete has been used for calculations. Risk of micro-crack formation on the auto-road pavement depends on material strength, conditions of plate fixing and temperature gradients.

  15. Development of a method for studying the influence of stress state on the iodine-induced stress corrosion cracking of zirconium alloys

    Science.gov (United States)

    Mozzani, Nathanael; Auzoux, Quentin; Le Boulch, David; Andrieu, Eric; Blanc, Christine

    A method based on the exposure of notched tensile specimens to iodized methanol is investigated to study the influence of stress state on the iodine-induced stress corrosion cracking (I-SCC) of zirconium alloys. Based on uniaxial tensile tests at different strain rates, in air and at room temperature, an anisotropic viscoplastic behavior model was established. This model was successfully compared to a notched specimen tensile test where local strains were measured by digital image correlation. Moreover, two I-SCC experiments were designed, on a tensile test machine and with an autonomous bending device. Examinations of failure surfaces of smooth specimens and investigations of iodine location were undertaken. The intergranular aspect of the cracking was observed and no iodine was found outside open cracks. Model calculations with different specimen geometries confirmed the possibility of having different stress states and will be used to determine local mechanical fields at crack initiation sites after I-SCC tests.

  16. Stress

    OpenAIRE

    Jensen, Line Skov; Lova, Lotte; Hansen, Zandra Kulikovsky; Schønemann, Emilie; Larsen, Line Lyngby; Colberg Olsen, Maria Sophia; Juhl, Nadja; Magnussen, Bogi Roin

    2012-01-01

    Stress er en tilstand som er meget omdiskuteret i samfundet, og dette besværliggør i en vis grad konkretiseringen af mulige løsningsforslag i bestræbelsen på at forebygge den såkaldte folkesygdom. Hovedkonklusionen er, at selv om der bliver gjort meget for at forebygge, er der ikke meget der aktivt kan sættes i værk for at reducere antallet af stressramte, før en fælles forståelse af stressårsager og effektiv stresshåndtering er fremlagt. Problemformuleringen er besvaret gennem en undersø...

  17. Numerical calculation of the stress-strain state of non-rigid pavements, renovated by cold recycling technology

    Directory of Open Access Journals (Sweden)

    Світлана Михайлівна Талах

    2017-01-01

    Full Text Available The problem of improving the scientific basis to determine the stress-strain state of non-rigid pavements, renovated by cold recycling technology, is considered. The results of numerical calculation of stress-strain state of non-rigid pavements in the section of road Kyv-Kovel (297 + 700 km - 302 + 400 km are given using automated calculation software complex of thin-walled spatial structures (KARTPK. The real state of the road section through 8.5 years after the renovation is analyzed

  18. Steady-state chlorophyll fluorescence (Fs) as a tool to monitor plant heat and drought stress

    Science.gov (United States)

    Cendrero Mateo, M.; Carmo-Silva, A.; Salvucci, M.; Moran, S. M.; Hernandez, M.

    2012-12-01

    Crop yield decreases when photosynthesis is limited by heat or drought conditions. Yet farmers do not monitor crop photosynthesis because it is difficult to measure at the field scale in real time. Steady-state chlorophyll fluorescence (Fs) can be used at the field level as an indirect measure of photosynthetic activity in both healthy and physiologically-perturbed vegetation. In addition, Fs can be measured by satellite-based sensors on a regular basis over large agricultural regions. In this study, plants of Camelina sativa grown under controlled conditions were subjected to heat and drought stress. Gas exchange and Fs were measured simultaneously with a portable photosynthesis system under light limiting and saturating conditions. Results showed that Fs was directly correlated with net CO2 assimilation (A) and inversely correlated with non-photochemical quenching (NPQ). Analysis of the relationship between Fs and Photosynthetically Active Radiation (PAR) revealed significant differences between control and stressed plants that could be used to track the status, resilience, and recovery of photochemical processes. In summary, the results provide evidence that Fs measurements, even without normalization, are an easy means to monitor changes in plant photosynthesis, and therefore, provide a rapid assessment of plant stress to guide farmers in resource applications. Figure1. Net CO2 assimilation rate (A) of Camelina sativa plants under control conditions and after heat stress exposure for 1 or 3 days (1d-HS and 3d-HS, respectively) (right) and control, drought and re-watering conditions (left). Conditions for infra-red gas analysis were: reference CO2 = 380 μmol mol-1, PPFD = 500 μmol m-2 s-1 and Tleaf set to 25°C (control, drought and re-water) or 35°C (HS). Different letters denote significant differences at the α=0.05 level. Values are means±SEM (n=10). Figure 2. Stable chlorophyll fluorescence (Fs) of Camelina sativa plants under control conditions and

  19. Effect of stress states on the deformation behavior of Cu-based bulk metallic glass in the supercooled liquid region

    Energy Technology Data Exchange (ETDEWEB)

    Park, E.S., E-mail: espark@ameslab.gov [Division of Materials Science and Engineering, Ames Laboratory, U.S. DOE, Ames, IA 50011 (United States); Kim, H.J.; Bae, J.C. [Liquid Processing and Casting Technology R and D Department, Korea Institute of Industrial Technology, Inchon 406-130 (Korea, Republic of); Huh, M.Y. [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2014-02-15

    Highlights: • The effect of stress states on the deformation behavior in the SLR was studied in the Cu{sub 54}Ni{sub 6}Zr{sub 22}Ti{sub 18} BMG alloy. • The present BMG alloy displayed different plastic stress–strain curves under tensile and compressive plastic strain states. • The calculation of the diffusivity of Cu atoms indicated that the diffusion of Cu atoms is retarded by compressive stress and accelerated by tensile stress. • The fast diffusion of Cu atoms under tensile stress caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation. -- Abstract: The effect of stress states on the deformation behavior of the Cu{sub 54}Zr{sub 22}Ti{sub 18}Ni{sub 6} bulk metallic glass (BMG) alloy was studied in the supercooled liquid region. At 723 K, Newtonian plastic flow governed the deformation during the compression test, whereas strain-hardening occurred during the tensile test. At 733 K, a fast failure was observed during tensile test. The diffusion rate of Cu atoms in the BMG alloy plays an important role in the deformation behavior. The fast diffusion of Cu atoms under the tensile stress state caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation.

  20. Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties.

    Science.gov (United States)

    Johnson, K L; Trim, M W; Francis, D K; Whittington, W R; Miller, J A; Bennett, C E; Horstemeyer, M F

    2017-01-15

    This paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. Samples were tested in the rehydrated (35wt% water) and ambient dry (10wt% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. The horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. The structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram's impacting each other as well as being useful for other analysis regarding horn keratin on other animals. The horn of the bighorn sheep is an anisotropic composite composed of keratin that is highly sensitive to moisture content. Keratin is also found in many other animals in the form of hooves, claws, beaks, and feathers. Only one previous study contains high rate experimental data, which was performed in the dry condition and only in compression. Considering the bighorn sheep horns' protective role in high speed impacts along with the moisture and strain rate sensitivity, more high strain rate data is needed to fully characterize and model the material. This study provides high strain

  1. Determination of the flow stress of a magnetorheological fluid under three-dimensional stress states by using a combination of extrusion test and FEM simulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng-yi; Wang, Zhong-jin, E-mail: wangzj@hit.edu.cn

    2016-12-01

    Magnetorheological fluid (MR fluid), a kind of smart material, has been used as a new pressure-carrying medium in magnetorheological pressure forming (MRPF). The mechanical property of MR fluid under the pressure significantly affects the sheet formability. However, there is little knowledge on the deformation behavior of MR fluid under three-dimensional stress states. In this paper, a new procedure via a combination of extrusion test and FEM simulation has been proposed to determine the flow stress of MR fluids. The experimental device for extrusion test of MR fluids was designed. The flow stresses of a MR fluid (MRF-J01T) under four different magnetic fields were determined through the proposed procedure. In addition, the obtained flow stresses were used in the following FEM simulations to verify the accuracy by comparing with the experimental results. The simulation results were in good agreement with the experimental data, which supports the correctness and practicability of the proposed method. - Highlights: • An effective procedure is proposed to determine the flow stress of MR fluids. • The rheological behaviour of a MR fluid during extrusion tests is studied. • Flow stress curves of a MR fluid under different magnetic fields are obtained.

  2. Enhanced stress resistance of Deinococcus radiodurans cells in the dried state

    Science.gov (United States)

    Bauermeister, Anja; Moeller, Ralf; Reitz, Guenther; Billi, Daniela; Rettberg, Petra

    Liquid water is often regarded as a pre-requisite for life as we know it. However, some organisms can survive prolonged periods in a desiccated state and seem to resist other environmental stres-sors even better when water is absent. We tested this observation in Deinococcus radiodurans, a non-sporeforming soil bacterium well-known for its outstanding resistance to DNA damaging stressors, including high doses of UV and ionizing radiation, oxidants, and desiccation. Due to its polyextremophilic characteristics it has been regarded as a model organism in astrobiological research. To determine if the cellular changes imposed by the removal of water have an effect on the stress resistance of D. radiodurans, we compared the survival capacity of dried cells with that of hydrated cells after exposure to mono-and polychromatic UV radiation, -radiation, and heat shock (85C). In all cases, resistance was enhanced in dried cells. It is suggested that these effects are mainly due to a reduced oxidative stress in dried cells, as the metabolism is shut down and radical diffusion is very limited. Hence, desiccating conditions as encountered in space vacuum or on arid planets such as Mars may be beneficial instead of detrimental to the survival of some polyextremophilic microbes. Ongoing experiments aim to evaluate damage at a subcellular level in dried and hydrated cells after exposure to irradiation or heat shock.

  3. The stem cell state in plant development and in response to stress.

    Science.gov (United States)

    Grafi, Gideon; Florentin, Assa; Ransbotyn, Vanessa; Morgenstern, Yakov

    2011-01-01

    Stem cells are commonly defined by their developmental capabilities, namely, self-renewal and multitype differentiation, yet the biology of stem cells and their inherent features both in plants and animals are only beginning to be elucidated. In this review article we highlight the stem cell state in plants with reference to animals and the plastic nature of plant somatic cells often referred to as totipotency as well as the essence of cellular dedifferentiation. Based on recent published data, we illustrate the picture of stem cells with emphasis on their open chromatin conformation. We discuss the process of dedifferentiation and highlight its transient nature, its distinction from re-entry into the cell cycle and its activation following exposure to stress. We also discuss the potential hazard that can be brought about by stress-induced dedifferentiation and its major impact on the genome, which can undergo stochastic, abnormal reorganization leading to genetic variation by means of DNA transposition and/or DNA recombination.

  4. The stem cell state in plant development and in response to stress

    Directory of Open Access Journals (Sweden)

    Gideon eGrafi

    2011-10-01

    Full Text Available Stem cells are commonly defined by their developmental capabilities, namely, self-renewal and multitype differentiation, yet the biology of stem cells and their inherent features both in plants and animals are only beginning to be elucidated. In this review article we highlight the stem cell state in plants (with reference to animals and the plastic nature of plant somatic cells (often referred to as totipotency as well as the essence of cellular dedifferentiation. Based on recent published data, we illustrate the picture of stem cells with emphasis on their open chromatin conformation. We discuss the process of dedifferentiation and highlight its transient nature, its distinction from reentry into the cell cycle and its activation following exposure to stress. We also discuss the potential hazard that can be brought about by stress-induced dedifferentiation and its major impact on the genome, which can undergo stochastic, abnormal reorganization leading to genetic variation by means of DNA transposition and/or DNA recombination.

  5. Finite Element Method Study on Stress State in Soil Induced by Agricultural Traffic

    Directory of Open Access Journals (Sweden)

    Adrian Molnar-Irimie

    2016-11-01

    Full Text Available In general, when a tyre is running on a deformable soil, the soil compaction will occur not only on surface layers, but also on soil profile, in deeper layers. This leads to a series of negative effects not only on physical and mechanical properties of soil, but also influences the crops growth and the crop yield. For these reasons, currently are needed solutions to reduce soil compaction, caused mainly by agricultural implements passing on the soil surface in order to aply the specific crop production technologies. From our simulation we can draw the following conclusions: the soil stresses decreased with depth; the soil displacements magnitude increased with soil water content due to lower friction forces between soil particles (water acts like a lubricant between soil particles; decreasing rate for soil displacement is influenced by load magnitude and tyre inflation pressure; the soil particles moved in vertical plain from the top to the bottom, but also in horizontal direction, from the center to the edge in cross section and in longitudinal direction; the dimensions of the geometric shape of the mentioned soil volume is influenced by load and tyre inflation pressure. In this paper the agricultural traffic and its influence on stress state in soil, it was used a software application based on Finite Element Method, that has been proved to be a useful tool for soil compaction assessment in order to find the right decisions for a proper field traffic management.

  6. Remaining stress-state and strain-energy in tempered glass fragments

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2016-01-01

    to the fragmentation process and some authors e.g. Barsom (J Am Ceram Soc 51(2):75, 1968), Gulati (Glass processing days, Tamglass Engineering Oy, Tampere, 1997), Warren (Fractography of glasses and ceramics IV, Alfred University, Alfred, 2001) and Tandon and Glass (Fracture mechanics of ceramics—active materials......When tempered glass breaks, it shatters into relatively small pieces depending on the residual stress state in the glass. This has been known for centuries and is currently used in standards for classifying whether a piece of glass is tempered or not. However, the process of fragmentation...... is complex and only a few, relatively simple, models have been suggested for predicting the fragment size. The full theoretical explanation is still to be found and this work aims at providing another brick to the puzzle. The strain-energy present in tempered glass is obviously contributing...

  7. The Determination of Stress State of Structures Considering Sequence of Construction and Load Application

    Directory of Open Access Journals (Sweden)

    Kuroedov Vladimir

    2016-01-01

    Full Text Available For more accurate calculation of structure it is required to apply loads in the process of its construction instead of load application after structure has taken its final form. This action is necessary in order to observe changes in the stress-strain state of the structure under study. This circumstance is important for the massive hydraulic structures, such as hydroelectric dams. It is required to determine tensions, deformations and displacements in solving the building-up tasks. It is necessary to consider the problem for constructions of linear and nonlinear materials and check the principle of superposition on which the method of solving nonlinear problems is based. Also it is necessary to consider the solution of finite element schemes with the help of various iterative methods, such as the method of additional loads and the method of variable.

  8. STRESS-STRAIN STATE IN EMBEDMENT OF REINFORCEMENT IN CASE OF REPEATED LOADINGS

    Directory of Open Access Journals (Sweden)

    Mirsayapov Ilshat Talgatovich

    2016-05-01

    Full Text Available The author offer transforming the diagram of ideal elastic-plastic deformations for the description of the stress-strain state of embedment of reinforcement behind a critical inclined crack at repeatedly repeating loadings. The endurance limit of the adhesion between concrete and reinforcement and its corresponding displacements in case of repeated loadings are accepted as the main indicators. This adhesion law is the most appropriate for the description of physical and mechanical phenomena in the contact zone in case of cyclic loading, because it simply and reliably describes the adhesion mechanism and the nature of the deformation, and greatly simplifies the endurance calculations compared to the standard adhesion law. On the basis of this diagram the author obtained the equations for the description of the distribution of pressures and displacements after cyclic loading with account for the development of deformations of cyclic creep of the concrete under the studs of reinforcement.

  9. Seismicity, state of stress and induced seismicity in the molasse basin and Jura (N-Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Deichmann, N. [Schweizerischer Erdbebendienst, ETH Zuerich, Zuerich (Switzerland); Burlini, L. [Institut of Geology, ETH Zuerich, Zuerich (Switzerland)

    2010-07-01

    This illustrated report for the Swiss Federal Office of Energy (SFOE) is one of a series of appendices dealing with the potential for geological sequestration of CO{sub 2} in Switzerland. This report takes a look at the seismicity, state of stress and induced seismicity in the molasse basin and Jura Mountains in northern Switzerland. Data collected since 1983 by the Swiss Earthquake Service and the National Cooperative for the Disposal of Radioactive Wastes NAGRA on the tectonics and seismic properties of North-western Switzerland is noted. The results are illustrated with a number of maps and graphical representations and are discussed in detail. Cases of induced seismicity as resulting from both natural and man-made causes are examined.

  10. Fracture toughness and the effects of stress state on fracture of nickel aluminides

    Science.gov (United States)

    Lewandowski, John J.; Michal, Gary M.; Locci, Ivan; Rigney, Joseph D.

    1991-01-01

    The effects of stress state on the fracture behavior of Ni3Al, Ni3Al + B, and NiAl were determined using either notched or fatigue-precracked bend bars tested to failure at room temperature, in addition to testing specimens in tension under superposed hydrostatic pressure. Although Ni3Al is observed to fail in a macroscopically brittle intergranular manner in tension tests conducted at room temperature, the fracture toughnesses presently obtained on Ni3Al exceeded 20 MPam, and R-curve behavior was exhibited. In situ monitoring of the fracture experiments was utilized to aid in interpreting the source(s) of the high toughness in Ni3Al, while SEM fractography was utilized to determine the operative fracture modes. The superposition by hydrostatic pressure during tensile testing of NiAl specimens was observed to produce increased ductility without changing the fracture mode.

  11. STRESS-DEFORMED STATE OF A STRUT-FRAMED CRANE GIRDER

    Directory of Open Access Journals (Sweden)

    Kh. M. Muselemov

    2017-01-01

    Full Text Available Objectives. The aim of the present work is to study the influence of design parameters on the stress-deformed state of a sprengel crane girder; to compile the tables and corresponding graphs illustrating changes in internal force factors in the characteristic cross-sections of the system elements under consideration. The article describes the study of the stress-deformed state (SDS of a metal strut-framed crane girder.Methods. Numerical methods of analysis based on the use of the Green's function are used during solving this problem. A dimensionless parameter is introduced, depending on which the tables and graphs are constructed. According to the known algorithm, the calculations of internal force factors in the sections of the considered construction are performed.Results. Depending on the dimensionless parameter characterising the geometry and physical features of the system, tables of bending moments and transverse forces are compiled. According to these tables, the appropriate graphs are plotted in order to choose easily the optimal design parameters.Conclusion. The dependence of the moments and transverse forces on the dimensionless parameter k was found, the corresponding graphs were plotted and the metal costs for the girders were calculated. The minimum values of the moments and transverse forces are established to take place when the dimensionless parameter k values are close to zero. The most economical was a strut-framed crane girder having k = 0.0001. The most uneconomical had k = 0.05 and k =∞. Eventually, the sprengel girders were found to be more profitable as compared to conventional crane girders. In the examples considered in the article, the metal savings amounted up to 14%. The presented methodology allows the calculation and designing of strut-framed crane girders with two racks to be carried out. 

  12. Hypohydration and acute thermal stress affect mood state but not cognition or dynamic postural balance.

    Science.gov (United States)

    Ely, Brett R; Sollanek, Kurt J; Cheuvront, Samuel N; Lieberman, Harris R; Kenefick, Robert W

    2013-04-01

    Equivocal findings have been reported in the few studies that examined the impact of ambient temperature (T a) and hypohydration on cognition and dynamic balance. The purpose of this study was to determine the impact of acute exposure to a range of ambient temperatures (T(a) 10-40 °C) in euhydration (EUH) and hypohydration (HYP) states on cognition, mood and dynamic balance. Thirty-two men (age 22 ± 4 years, height 1.80 ± 0.05 m, body mass 85.4 ± 10.8 kg) were grouped into four matched cohorts (n = 8), and tested in one of the four T(a) (10, 20, 30, 40 °C) when EUH and HYP (-4 % body mass via exercise-heat exposure). Cognition was assessed using psychomotor vigilance, 4-choice reaction time, matching to sample, and grammatical reasoning. Mood was evaluated by profile of mood states and dynamic postural balance was tested using a Biodex Balance System. Thermal sensation (TS), core (T core) and skin temperature (T(sk)) were obtained throughout testing. Volunteers lost -4.1 ± 0.4 % body mass during HYP. T sk and TS increased with increasing T(a), with no effect of hydration. Cognitive performance was not altered by HYP or thermal stress. Total mood disturbance (TMD), fatigue, confusion, anger, and depression increased during HYP at all T(a). Dynamic balance was unaffected by HYP, but 10 °C exposure impaired balance compared to all other T(a). Despite an increase in TMD during HYP, cognitive function was maintained in all testing environments, demonstrating cognitive resiliency in response to body fluid deficits. Dynamic postural stability at 10 °C appeared to be hampered by low-grade shivering, but was otherwise maintained during HYP and thermal stress.

  13. Stress and food deprivation: linking physiological state to migration success in a teleost fish.

    Science.gov (United States)

    Midwood, Jonathan D; Larsen, Martin H; Aarestrup, Kim; Cooke, Steven J

    2016-12-01

    Food deprivation is a naturally occurring stressor that is thought to influence the ultimate life-history strategy of individuals. Little is known about how food deprivation interacts with other stressors to influence migration success. European populations of brown trout (Salmo trutta) exhibit partial migration, whereby a portion of the population smoltifies and migrates to the ocean, and the rest remain in their natal stream. This distinct, natural dichotomy of life-history strategies provides an excellent opportunity to explore the roles of energetic state (as affected by food deprivation) and activation of the glucocorticoid stress response in determining life-history strategy and survival of a migratory species. Using an experimental approach, the relative influences of short-term food deprivation and experimental cortisol elevation (i.e. intra-coelomic injection of cortisol suspended in cocoa butter) on migratory status, survival and growth of juvenile brown trout relative to a control were evaluated. Fewer fish migrated in both the food deprivation and cortisol treatments; however, migration of fish in cortisol and control treatments occurred at the same time while that of fish in the food deprivation treatment was delayed for approximately 1 week. A significantly greater proportion of trout in the food deprivation treatment remained in their natal stream, but unlike the cortisol treatment, there were no long-term negative effects of food deprivation on growth, relative to the control. Overall survival rates were comparable between the food deprivation and control treatments, but significantly lower for fish in the cortisol treatment. Food availability and individual energetic state appear to dictate the future life-history strategy (migrate or remain resident) of juvenile salmonids while experimental elevation of the stress hormone cortisol causes impaired growth and reduced survival of both resident and migratory individuals. © 2016. Published by The

  14. Characterization of degradation products of amorphous and polymorphic forms of clopidogrel bisulphate under solid state stress conditions

    DEFF Research Database (Denmark)

    Raijada, Dhara K; Prasad, Bhagwat; Paudel, Amrit

    2010-01-01

    The present study deals with the stress degradation studies on amorphous and polymorphic forms of clopidogrel bisulphate. The objective was to characterize the degradation products and postulate mechanism of decomposition of the drug under solid state stress conditions. For that, amorphous form...... degradation products were observed under various stress conditions. The structures of all of them were elucidated using LC-MS/TOF and LC-MS(n) studies. While one matched the known hydrolytic decomposition product of the drug in solution, seven others were new. The postulated degradation pathway and mechanism...

  15. Stress and stress counselling.

    OpenAIRE

    Matheson, K. H.

    1990-01-01

    This is a report by the 1989 National Association of Clinical Tutors Wyeth Travelling Fellow to the United States of America. The stresses of postgraduate training and attempts to modify these are described, including stress counselling. The significance of stress and the relevance of the findings for postgraduate training in the United Kingdom are considered.

  16. Chronic environmental stress and the temporal course of depression and panic disorder: A trait-state-occasion modeling approach.

    Science.gov (United States)

    Conway, Christopher C; Rutter, Lauren A; Brown, Timothy A

    2016-01-01

    Both acute stressful life events and ongoing strains are thought to confer vulnerability to emotional disorders. Unremitting stressful conditions may be particularly pathogenic, but prior research has struggled to delimit chronic versus transient stressful experiences. We aimed to isolate stable stressors-theorized to be indicators of a latent stress proneness trait-and to examine their effects on the temporal course of depression and panic disorder. We recruited 677 patients diagnosed with an emotional disorder and administered interviews for psychopathology and life stress 3 times over 12-month intervals. Trait-state-occasion modeling revealed that 74% of the variance in life stress was stable over the follow-up period. These stable stressors were associated with a more refractory course of depression and, to a smaller degree, panic disorder over time. In addition, neither gender nor participation in cognitive-behavioral therapy affected the persistence of environmental stress over the study time frame. We discuss implications of these findings for explaining depression recurrence, improving psychological interventions for emotional disorders, and the measurement and evaluation of stress proneness. (c) 2016 APA, all rights reserved.

  17. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev, E-mail: dcc@unr.edu

    2017-05-15

    Highlights: • Mixtures of oxides containing Ni, Fe, Cr and Nb formed on the surface. • Short term exposure tests observed breakdown of native film. • Formation of a Fe rich oxide layer on Inconel 718 prevents mass loss. - Abstract: Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO{sub 4}{sup 2−} based film formed; however minor quantities of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel. The surface films on both alloys were identified as NiFe{sub 2}O{sub 4} when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  18. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Science.gov (United States)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev

    2017-05-01

    Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO42- based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  19. Stress.

    Science.gov (United States)

    Chambers, David W

    2008-01-01

    We all experience stress as a regular, and sometimes damaging and sometimes useful, part of our daily lives. In our normal ups and downs, we have our share of exhaustion, despondency, and outrage--matched with their corresponding positive moods. But burnout and workaholism are different. They are chronic, dysfunctional, self-reinforcing, life-shortening habits. Dentists, nurses, teachers, ministers, social workers, and entertainers are especially susceptible to burnout; not because they are hard-working professionals (they tend to be), but because they are caring perfectionists who share control for the success of what they do with others and perform under the scrutiny of their colleagues (they tend to). Workaholics are also trapped in self-sealing cycles, but the elements are ever-receding visions of control and using constant activity as a barrier against facing reality. This essay explores the symptoms, mechanisms, causes, and successful coping strategies for burnout and workaholism. It also takes a look at the general stress response on the physiological level and at some of the damage American society inflicts on itself.

  20. Modeling the Effects of a Normal-Stress-Dependent State Variable, Within the Rate- and State-Dependent Friction Framework, at Stepovers and Dip-Slip Faults

    Science.gov (United States)

    Ryan, Kenny J.; Oglesby, David D.

    2017-03-01

    The development of the rate- and state-dependent friction framework (Dieterich Appl Geophys 116:790-806, 1978; J Geophys Res 84, 2161-2168, 1979; Ruina Friction laws and instabilities: a quasistatic analysis of some dry friction behavior, Ph.D. Thesis, Brown Univ., Providence, R.I., 1980; J Geophys Res 88:10359-10370, 1983) includes the dependence of friction coefficient on normal stress (Linker and Dieterich J Geophys Res 97:4923-4940, 1992); however, a direct dependence of the friction law on time-varying normal stress in dynamic stepover and dip-slip fault models has not yet been extensively explored. Using rate- and state-dependent friction laws and a 2-D dynamic finite element code (Barall J Int 178, 845-859, 2009), we investigate the effect of the Linker-Dieterich dependence of state variable on normal stress at stepovers and dip-slip faults, where normal stress should not be constant with time (e.g., Harris and Day J Geophys Res 98:4461-4472, 1993; Nielsen Geophys Res Lett 25:125-128, 1998). Specifically, we use the relation d ψ/d t = -( α/ σ)(d σ/d t) from Linker and Dieterich (J Geophys Res 97:4923-4940, 1992), in which a change in normal stress leads to a change in state variable of the opposite sign. We investigate a range of values for alpha, which scales the impact of the normal stress change on state, from 0 to 0.5 (laboratory values range from 0.2 to 0.56). For stepovers, we find that adding normal-stress dependence to the state variable delays or stops re-nucleation on the secondary fault segment when compared to normal-stress-independent state evolution. This inhibition of jumping rupture is due to the fact that re-nucleation along the secondary segment occurs in areas of decreased normal stress in both compressional and dilational stepovers. However, the magnitude of such an effect differs between dilational and compressional systems. Additionally, it is well known that the asymmetric geometry of reverse and normal faults can lead to greater

  1. Study on design of superconducting proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Xu Tao Guang

    2002-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac (SCL) is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. It is constitute by a series of the superconducting accelerating cavities. The cavity geometry is determined by means of the electromagnetic field computation. The SCL main parameters are determined by the particle dynamics computation

  2. Subcritical experiments at the FREYA experiment; Experimentos subcriticos en el proyecto FREYA

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.; Villamarin fernandez, D.

    2013-07-01

    The FREYA Project of the 7th Framework Program is aimed to the study of the kinetics of subcritical reactors coupled to an external neutron source, and, more specifically, to the validation of reactivity monitoring techniques. CIEMAT activities within the frame of this project have consisted in analyzing the possible ways of correcting the spatial and energy effects on these reactivity monitoring techniques, as well as analyzing the effects that may have on them the presence of different materials in the reflector and the position of the neutron source.

  3. Ion acoustic wave generation by a standing electromagnetic field in a subcritical plasma

    OpenAIRE

    P. Fischer; Gauthereau, C.; Godiot, J.; G. Matthieussent

    1987-01-01

    An electromagnetic wave ( f = 9 GHz, Pi = 150 kW, τ = 1.5 μs) is launched into a subcritical argon plasma (n e ≃1011 cm-3, P0 ≃ 5 × 10-4 Torr), resulting in a standing wave. The associated ponderomotive force generates an ion acoustic wave with a wave vector equal to twice the electromagnetic one and with a frequency satisfying the usual dispersion relation (fA ≃ 150 kHz). The main features of the ion acoustic wave, as measured in this 3D experiment, agree with a simple theory. However, varyi...

  4. PRACTICAL APPLICATION OF THE SINGLE-PARAMETER SUBCRITICAL MASS LIMIT FOR PLUTONIUM METAL

    Energy Technology Data Exchange (ETDEWEB)

    MITCHELL, MARK VON [Los Alamos National Laboratory

    2007-01-10

    According to ANS-8.1, operations with fissile materials can be performed safely by complying with any of the listed single-parameter subcritical limits. For metallic units, when interspersed moderators are present, the mass limits apply to a single piece having no concave surfaces. On a practical level, when has any operation with fissile metal involved a single piece and absolutely no moderating material, e.g., water, oil, plastic, etc.? This would be rare. This paper explores the application of the single-parameter plutonium metal mass limit for realistic operational environments.

  5. Hydrothermal liquefaction of Spirulina and Nannochloropsis Salina under subcritical and supercritical water conditions

    DEFF Research Database (Denmark)

    Toor, Saqib; Reddy, H.; Deng, S.

    2013-01-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220-375 °C, 20-255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid...... on Nannochloropsis salina at 350 °C and 175 bar. For Spirulina platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for Nannochloropsis salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae...

  6. Semiclassical Limit of the Non-linear Schroedinger-Poisson Equation With Subcritical Initial Data

    Science.gov (United States)

    2002-12-01

    lim ∇xargψ. As noted earlier, this argument is self - consistent as long as the solution of the Euler- Poisson system (1.5)-(1.6) remains classical...00-2003 to 00-00-2003 4. TITLE AND SUBTITLE Semiclassical Limit of the Non-linear Schrodinger - Poisson Equation with Subcritical Initial Data 5a...classical limit of a self - consistent quantum-Vlasov equation in 3-D, Math. Models Methods Appl. Sci., 3 (1993), pp. 109–124. [SMM] C. Sparber, P. Markowich

  7. Criticality Safety Evaluation of the LLNL Inherently Safe Subcritical Assembly (ISSA)

    Energy Technology Data Exchange (ETDEWEB)

    Percher, Catherine [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-06-19

    The LLNL Nuclear Criticality Safety Division has developed a training center to illustrate criticality safety and reactor physics concepts through hands-on experimental training. The experimental assembly, the Inherently Safe Subcritical Assembly (ISSA), uses surplus highly enriched research reactor fuel configured in a water tank. The training activities will be conducted by LLNL following the requirements of an Integration Work Sheet (IWS) and associated Safety Plan. Students will be allowed to handle the fissile material under the supervision of LLNL instructors. This report provides the technical criticality safety basis for instructional operations with the ISSA experimental assembly.

  8. Stress, Emotions, and Motivational States Among Traditional Dancers in New Zealand and Japan.

    Science.gov (United States)

    Kuroda, Y; Geisler, G; Morel, P C H; Hapeta, J

    2017-01-01

    This study used a reversal theory framework to examine motivational dominance and changes in motivational state, arousal, stress, and emotions among members of traditional Japanese (Nihon Odori Sports Science (NOSS)) and New Zealand (Kapa Haka) dance groups. Eighty-four participants (50 in Japan and 34 in New Zealand) completed questionnaires on each variable before and after a dance class. The findings indicated that the Kapa Haka dancers were significantly more playful and arousal-seeking than the NOSS dancers. They also reported higher overall arousal, preferred arousal, and effort during performance while the NOSS dancers became more serious afterward. Data on emotions matched those of arousal in that the Kapa Haka dancers felt significantly more excited and provocative after the session. The NOSS dancers were more relaxed and placid, both overall and after dancing. These patterns were consistent with the dancers' respective motivational states and motivational dominance, and suggest that both dances can be effective in reducing negative affect. They also suggest that psychological effects are dependent upon performers' personal and cultural affiliation with the two dance forms.

  9. The glass transition in a nutshell: a source of inspiration to describe the subcritical transition to turbulence.

    Science.gov (United States)

    Dauchot, Olivier; Bertin, Eric

    2014-04-01

    The starting point of the present work is the observation of possible analogies, both at the phenomenological and at the methodological level, between the subcritical transition to turbulence and the glass transition. Having recalled the phenomenology of the subcritical transition to turbulence, we review the theories of the glass transition at a very basic level, focusing on the history of their development as well as on the concepts they have elaborated. Doing so, we aim at attracting the attention on the above-mentioned analogies, which we believe could inspire new developments in the theory of the subcritical transition to turbulence. We then briefly describe a model inspired by one of the simplest and most inspiring models of the glass transition, the so-called Random Energy Model, as a first step in that direction.

  10. Applications of subcritical and supercritical water conditions for extraction, hydrolysis, gasification, and carbonization of biomass: a critical review

    Directory of Open Access Journals (Sweden)

    D. Lachos-Perez

    2017-06-01

    Full Text Available This review summarizes the recent essential aspects of subcritical and supercritical water technology applied tothe extraction, hydrolysis, carbonization, and gasification processes. These are clean and fast technologies which do not need pretreatment, require less reaction time, generate less corrosion and residues, do not usetoxic solvents, and reduce the synthesis of degradation byproducts. The equipment design, process parameters, and types of biomass used for subcritical and supercritical water process are presented. The benefits of catalysis to improve process efficiency are addressed. Bioactive compounds, reducing sugars, hydrogen, biodiesel, and hydrothermal char are the final products of subcritical and supercritical water processes. The present review also revisits advances of the research trends in the development of subcriticaland supercritical water process technologies.

  11. In ICU state anxiety is not associated with posttraumatic stress symptoms over six months after ICU discharge: A prospective study.

    Science.gov (United States)

    Castillo, Maria I; Cooke, Marie L; Macfarlane, Bonnie; Aitken, Leanne M

    2016-08-01

    Posttraumatic stress symptoms are common after intensive care treatment. The influence of anxiety during critical illness on the development of posttraumatic stress symptoms needs to be investigated. To determine the association between anxiety during critical illness (state and trait components) and posttraumatic stress symptoms over six months after ICU discharge. Prospective study including 141 patients admitted ≥24h to a closed mixed adult ICU in a tertiary hospital. State anxiety was assessed with the Faces Anxiety Scale during ICU stay. Trait anxiety was measured with the State-Trait Anxiety Inventory Form Y-2. Posttraumatic stress symptoms were measured at three and six months after ICU discharge using the Post-Traumatic Stress Symptoms 10-Question Inventory. Clinical and demographical data were also collected. Mixed effect regression models were used to determine if state and trait anxiety were factors significantly associated with posttraumatic stress symptoms over time. Moderate to severe levels of state anxiety in ICU were reported by 81 (57%) participants. Levels of trait anxiety (median 36 IQR: 29-47) were similar to the Australian population. High levels of posttraumatic stress symptoms occurred at three (n=19, 19%) and six months (n=15, 17%). Factors independently associated with posttraumatic stress symptoms were trait anxiety (2.2; 95% CI, 0.3-4.1; p=0.02), symptoms of anxiety after ICU discharge (0.6; 95% CI, 0.2-1.1; p=0.005), younger age (-1.4; 95% CI, -2.6 to -0.2; p=0.02) and evidence of mental health treatment prior to the ICU admission (5.2; 95% CI, 1.5-8.9; p=0.006). Posttraumatic stress symptoms occurred in a significant proportion of ICU survivors and were significantly associated with higher levels of trait anxiety, younger age, mental health treatment prior to the ICU admission and more symptoms of anxiety after ICU discharge. Early assessment and interventions directed to reduce state and trait anxiety in ICU survivors may be of

  12. Altered resting-state functional connectivity in post-traumatic stress disorder: a perfusion MRI study

    Science.gov (United States)

    Li, Baojuan; Liu, Jian; Liu, Yang; Lu, Hong-Bing; Yin, Hong

    2013-03-01

    The majority of studies on posttraumatic stress disorder (PTSD) so far have focused on delineating patterns of activations during cognitive processes. Recently, more and more researches have started to investigate functional connectivity in PTSD subjects using BOLD-fMRI. Functional connectivity analysis has been demonstrated as a powerful approach to identify biomarkers of different brain diseases. This study aimed to detect resting-state functional connectivity abnormities in patients with PTSD using arterial spin labeling (ASL) fMRI. As a completely non-invasive technique, ASL allows quantitative estimates of cerebral blood flow (CBF). Compared with BOLD-fMRI, ASL fMRI has many advantages, including less low-frequency signal drifts, superior functional localization, etc. In the current study, ASL images were collected from 10 survivors in mining disaster with recent onset PTSD and 10 survivors without PTSD. Decreased regional CBF in the right middle temporal gyrus, lingual gyrus, and postcentral gyrus was detected in the PTSD patients. Seed-based resting-state functional connectivity analysis was performed using an area in the right middle temporal gyrus as region of interest. Compared with the non-PTSD group, the PTSD subjects demonstrated increased functional connectivity between the right middle temporal gyrus and the right superior temporal gyrus, the left middle temporal gyrus. Meanwhile, decreased functional connectivity between the right middle temporal gyrus and the right postcentral gyrus, the right superior parietal lobule was also found in the PTSD patients. This is the first study which investigated resting-state functional connectivity in PTSD using ASL images. The results may provide new insight into the neural substrates of PTSD.

  13. Stressful life events are associated with insulin resistance among Chinese immigrant women in the United States

    Directory of Open Access Journals (Sweden)

    Carolyn Y. Fang

    2015-01-01

    Conclusions: This is one of the first studies to examine the associations between psychosocial stress and insulin resistance in Chinese immigrant women. These findings contribute to a growing body of literature on stress and diabetes risk in an immigrant population.

  14. Subcritical crack propagation due to chemical rock weakening: macroscale chemo-plasticity and chemo-elasticity modeling

    Science.gov (United States)

    Hueckel, T.; Hu, M.

    2015-12-01

    Crack propagation in a subcritically stressed rock subject to chemically aggressive environment is analyzed and numerically simulated. Chemically induced weakening is often encountered in hydraulic fracturing of low-permeability oil/gas reservoirs and heat reservoirs, during storage of CO2 and nuclear waste corroding canisters, and other circumstances when rock matrix acidizing is involved. Upon acidizing, mineral mass dissolution is substantially enhanced weakening the rock and causing crack propagation and eventually permeability changes in the medium. The crack process zone is modeled mathematically via a chemo-plastic coupling and chemo-elastic coupling model. In plasticity a two-way coupling is postulated between mineral dissolution and a yield limit of rock matrix. The rate of dissolution is described by a rate law, but the mineral mass removal per unit volume is also a function of a variable internal specific surface area, which is in turn affected by the micro-cracking (treated as a plastic strain). The behavior of the rock matrix is modeled as rigid-plastic adding a chemical softening capacity to Cam-Clay model. Adopting the Extended Johnson's approximation of processes around the crack tip, the evolution of the stress field and deformation as a function of the chemically enhanced rock damage is modeled in a simplified way. In addition, chemical reactive transport is made dependent on plastic strain representing micro-cracking. Depending on mechanical and chemical boundary conditions, the area of enhanced chemical softening is near or somewhat away from the crack tip.In elasticity, chemo-mechanical effect is postulated via a chemical volumetric shrinkage strain proportional to mass removal variable, conceived analogously to thermal expansion. Two versions are considered: of constant coefficient of shrinkage and a variable one, coupled to deviatoric strain. Airy Potential approach used for linear elasticity is extended considering an extra term, which is

  15. Stress Coping Levels and Mental States of Police Vocational School of Higher Education Students

    Directory of Open Access Journals (Sweden)

    Arzu Yildirim

    2011-06-01

    Full Text Available SUMMARY AIM: This study was planned and carried out with the objective of determining stress coping levels and mental state of students attending Police Vocational Schools of Higher Education, in addition to factors effecting these. MATERIAL and METHOD: This desciptive and cross-sectional study consisted of 300 male students enrolled in the 2005-2006 academic year, at Police Vocational School of Higher Education, located in central Erzincan, Turkey. In this study, instead of random sampling, 281 (93.7% students who were present at the school at the time of the study and accepted to partipate in it were included. Data for this study was collected using a desciptive form created by the researchers, Rosenbaum’s Learned Resourcefulness Scale (RLRS and The Symptom Check List-90-R (SCL-90-R. During the data analysis, frequency distributions, Mann-Whitney U, Kruskal-Wallis and analysis of variance (one-way ANOVA were used; and for analysis of independent groups, t-test was used. RESULTS: Among the students, it was determined that 54.8% were 1. grade, 90.7% had their parents living together, 43.5% had a father and 60.5% had a mother who graduated from elementary school, fathers of 23.5% of students were retired, 93.6% of them had mothers who were home makers. In addition, it was found out that 78.6% of students chose their profession willingly, the average family income of 71.5% of students were at medium levels, 82.9% always believed in themselves and 63.3% of students did not smoke. Based on the results obtained, it was observed that second grade students, those with mothers who are highly educated and those who trusted themselved all the time had significantly high stress coping levels; students who chose their own profession, believed in themselves and did not smoke had significantly low levels of mental symptom indications. CONCLUSION: In this study, the students were determined to posess averge levels of stress coping skills and they were found

  16. Stress state during fixation determines susceptibility to fatigue-linked biodegradation in bioprosthetic heart valve materials.

    Science.gov (United States)

    Margueratt, Sean D; Lee, J Michael

    2002-01-01

    Mechanical loading contributes to the structural deterioration of bioprosthetic heart valves. The influence of stress state during fixation may play a substantial role in their failure, linking fatigue damage caused by buckling and tension and the enzymatic degradation of glutaraldehyde-crosslinked collagen. Bovine pericardia were obtained immediately postmortem and 100 mm x 15 mm samples were cut in the base-to-apex direction. Half the samples were subjected to a uniaxial tensile stress of 250 kPa and half remained unloaded during a crosslinking treatment in 0.5% glutaraldehyde. Tissue samples were rinsed and cut into 16 mm x 4 mm test strips. Half of these strips were exposed to cyclic compressive buckling and alternating tension at 30 Hz for 20 million cycles (approx. 7.5 days) using a custom-built multi-sample fatigue system. Fatigue-damaged and non-damaged samples were subsequently incubated at 37 C for 48 hrs in: (i) Type I bacterial collagenase (20 U/ml) buffered in 0.05 M Tris, 10 mM CaCl2 2H2O (pH 7.4) or (ii) 0.05 M Tris buffer (pH 7.4) only. In both cases, the samples were loaded sinusoidally between 40 and 80 g using a previously described microtensile culture system. Tissue removed from the bath was rinsed in 0.1 M EDTA solution and mounted in a servo-hydraulic mechanical testing system (MTS). Ultimate tensile strength (UTS), maximum tissue modulus, and fracture strain were determined. The percent collagen solubilized was assessed by a colourmetric hydroxyproline assay of the enzyme bath and tissue sample. All data were analyzed by analysis of variance (ANOVA). The results confirmed the synergy between fatigue damage and collagenase proteolysis in these materials; however, there were no significant differences in this effect between simple fixation and stress-fixation up to 20 million cycles. There were significant decreases in the mechanical properties and an increase in the amount of collagen solubilized with increased exposure to fatigue cycling.

  17. Endoplasmic reticulum redox state is not perturbed by pharmacological or pathological endoplasmic reticulum stress in live pancreatic β-cells.

    Directory of Open Access Journals (Sweden)

    Irmgard Schuiki

    Full Text Available Accumulation of unfolded, misfolded and aggregated proteins in the endoplasmic reticulum (ER causes ER stress. ER stress can result from physiological situations such as acute increases in secretory protein biosynthesis or pathological conditions that perturb ER homeostasis such as alterations in the ER redox state. Here we monitored ER redox together with transcriptional output of the Unfolded Protein Response (UPR in INS-1 insulinoma cells stably expressing eroGFP (ER-redox-sensor and mCherry protein driven by a GRP78 promoter (UPR-sensor. Live cell imaging, flow cytometry and biochemical characterization were used to examine these parameters in response to various conditions known to induce ER stress. As expected, treatment of the cells with the reducing agent dithiothreitol caused a decrease in the oxidation state of the ER accompanied by an increase in XBP-1 splicing. Unexpectedly however, other treatments including tunicamycin, thapsigargin, DL-homocysteine, elevated free fatty acids or high glucose had essentially no influence on the ER redox state, despite inducing ER stress. Comparable results were obtained with dispersed rat islet cells expressing eroGFP. Thus, unlike in yeast cells, ER stress in pancreatic β-cells is not associated with a more reducing ER environment.

  18. Study on the residual stress state of TA2 titanium sheet metal formed perpendicularly with single pulsed laser

    Science.gov (United States)

    Feng, A. X.; Zhang, Y. K.; Zuo, D. W.; Kong, D. J.; Lu, J. Z.; Ren, X. D.; Zhou, J. Z.; Tang, C. P.; Xie, H. K.

    2005-12-01

    Laser shock forming(LSF) is a new forming technique of sheet metal by applying a compressive shock wave on the surface of metal sheet. The plastic deformation of TA2 titanium metal sheet is performed under single laser shocking perpendicularly with Nd:Glass laser developed in Jiangsu University. The residual stress state in the horizontal and diagonal direction of the foursquare specimen, as well as the residual stress state in the radial direction of the circular specimen, was investigated with X-ray stress analyzer. The residual stress state of laser shock forming specimen is unique to some extent by contrast with traditional punch forming, which is influenced by the specimen shape and the deformation rate. The experiment results show that residual stresses value of TA2 Titanium Sheet Metal in laser shock area are up to 100MPa.Square specimen is more difficult to be formed than circular specimen, and the press value of cave is the larger than the one of convex.

  19. Final Progress Report: FRACTURE AND SUBCRITICAL DEBONDING IN THIN LAYERED STRUCTURES: EXPERIMENTS AND MULTI-SCALE MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Reinhold H. Dauskardt

    2005-08-30

    Final technical report detailing unique experimental and multi-scale computational modeling capabilities developed to study fracture and subcritical cracking in thin-film structures. Our program to date at Stanford has studied the mechanisms of fracture and fatigue crack-growth in structural ceramics at high temperature, bulk and thin-film glasses in selected moist environments where we demonstrated the presence of a true mechanical fatigue effect in some glass compositions. We also reported on the effects of complex environments and fatigue loading on subcritical cracking that effects the reliability of MEMS and other micro-devices using novel micro-machined silicon specimens and nanomaterial layers.

  20. The Impact of a Novel Biobehavioral Intervention on Physiologic State, Perceived Stress and Affect

    Science.gov (United States)

    2016-04-15

    As a result of over 15 years of war, members of the military services have experienced unprecedented consequences related to the stresses of serving...during this time. Early detection, characterization, and treatment of stress -related disorders is one of the highest priorities for the armed forces...a military population but is a promising treatment for stress related disorders.

  1. Barriers and Perceived Stress Levels of Internationals Living in the United States

    Science.gov (United States)

    Davis, Terah L.

    2017-01-01

    This study explored the perceived stress level of international students who faced barriers to employment upon graduation from an American post-secondary institution. The Barriers to Employment Success Inventory (BESI) was used to assess employment barriers and the Perceived Stress Scale (PSS) assessed the perceived level of stress experienced by…

  2. Perceived Support as a Predictor of Acculturative Stress among International Students in the United States

    Science.gov (United States)

    Bai, Jieru

    2016-01-01

    A quantitative study was conducted to measure the acculturative stress of international students and investigate the predictors of acculturative stress. A total of 186 students participated in the survey. Results showed that 22.4% of the students in this study exceeded the normal stress level and might need counseling or psychological…

  3. Wearable physiological sensors reflect mental stress state in office-like situations

    NARCIS (Netherlands)

    Wijsman, J.L.P; Grundlehner, Bernard; Liu, Hao; Penders, Julien; Hermens, Hermanus J.

    Timely mental stress detection can help to prevent stress-related health problems. The aim of this study was to identify those physiological signals and features suitable for detecting mental stress in office-like situations. Electrocardiogram (ECG), respiration, skin conductance and surface

  4. Interrogating surface state of isolated and agglomerated PbS quantum dots with solvent-induced stress.

    Science.gov (United States)

    Sher, Pin-Hao; Wang, Juen-Kai

    2017-04-21

    Applications of quantum dots (QDs) are often obstructed by the associated surface electronic states that quench photoluminescence (PL) and hinder charge transport. Preventing this is still largely being stymied owing to the lack of means to regulate their presence. Dispersing PbS QDs in toluene, we show that varying the solvent temperature offers a way of modulating their surface electronic state. A comprehensive energy-transfer model explains all the anomalous temperature-dependent behavior of the absorption and PL, explicitly revealing the PL quenching dynamics of isolated QDs due to the induced surface state by imposing solvent stress on their surface ligands. This study demonstrates that the local stress induced by a solvent can serve as a 'switch' for the surface electronic states of QDs, which is enabled by the well-studied thermo-physical properties of a liquid solvent.

  5. Development and validation of the Acculturative Stress Scale for Chinese College Students in the United States (ASSCS).

    Science.gov (United States)

    Bai, Jieru

    2016-04-01

    Chinese students are the biggest ethnic group of international students in the United States. This study aims to develop a reliable and valid scale to accurately measure their acculturative stress. A 72-item pool was sent online to Chinese students and a five-factor scale of 32 items was generated by exploratory factor analysis. The five factors included language insufficiency, social isolation, perceived discrimination, academic pressure, and guilt toward family. The Acculturative Stress Scale for Chinese Students demonstrated high reliability and initial validity by predicting depression and life satisfaction. It was the first Chinese scale of acculturative stress developed and validated among a Chinese student sample in the United States. In the future, the scale can be used as a diagnostic tool by mental health professionals and a self-assessment tool by Chinese students. (c) 2016 APA, all rights reserved.

  6. Dynamic properties of nucleated microtubules: GTP utilisation in the subcritical concentration regime.

    Science.gov (United States)

    Symmons, M F; Martin, S R; Bayley, P M

    1996-11-01

    Microtubule assembly kinetics have been studied quantitatively under solution conditions supporting microtubule dynamic instability. Purified GTP-tubulin (Tu-GTP) and covalently cross-linked short microtubule seeds (EGS-seeds; Koshland et al. (1988) Nature 331, 499) were used with and without biotinylation. Under sub-critical concentration conditions ([Tu-GTP] assembly, that was found to abolish the GDP release. The variation of the GDP release with tubulin concentration (Jh(c) plot) was determined below the critical concentration (Cc). The GDP production observed was consistent with the elongation of the observed seeded microtubules with an apparent rate constant of 1.5 x 10(6) M-1 second-1 above a threshold of approximately 1 microM tubulin. The form of this Jh(c) plot for elongation below Cc is reproduced by the Lateral Cap model for microtubule dynamic instability adapted for seeded assembly. The behaviour of the system is contrasted with that previously studied in the absence of detectable microtubule elongation (Caplow and Shanks (1990) J. Biol. Chem. 265, 8935-8941). The approach provides a means of monitoring microtubule dynamics at concentrations inaccessible to optical microscopy, and shows that essentially the same dynamic mechanisms apply at all concentrations. Numerical simulation of the subcritical concentration regime shows dynamic growth features applicable to the initiation of microtubule growth in vivo.

  7. Homoclinic connections and subcritical Neimark bifurcation in a duopoly model with adaptively adjusted productions

    Energy Technology Data Exchange (ETDEWEB)

    Agliari, Anna [Dipartimento di Scienze Economiche e Sociali, Universita Cattolica del Sacro Cuore, Via Emilia Parmense, 84, 29100 Piacenza (Italy)]. E-mail: anna.agliari@unicatt.it

    2006-08-15

    In this paper we study some global bifurcations arising in the Puu's oligopoly model when we assume that the producers do not adjust to the best reply but use an adaptive process to obtain at each step the new production. Such bifurcations cause the appearance of a pair of closed invariant curves, one attracting and one repelling, this latter being involved in the subcritical Neimark bifurcation of the Cournot equilibrium point. The aim of the paper is to highlight the relationship between the global bifurcations causing the appearance/disappearance of two invariant closed curves and the homoclinic connections of some saddle cycle, already conjectured in [Agliari A, Gardini L, Puu T. Some global bifurcations related to the appearance of closed invariant curves. Comput Math Simul 2005;68:201-19]. We refine the results obtained in such a paper, showing that the appearance/disappearance of closed invariant curves is not necessarily related to the existence of an attracting cycle. The characterization of the periodicity tongues (i.e. a region of the parameter space in which an attracting cycle exists) associated with a subcritical Neimark bifurcation is also discussed.

  8. Total acid number reduction kinetics of naphthenic acids using non-catalytic subcritical methanol

    Science.gov (United States)

    Zafar, Faisal; Mandal, Pradip Chandra; Shaari, Ku Zilati bt Ku; Nadeem, Saad

    2017-10-01

    Naphthenic acids (NAs) are weak organic acids present in the heavy crude oil and Oil Sand Bitumens. Whereas, the NAs are the major cause of corrosion in different processing, handling and storage equipment's of the refinery. Esterification of these acids can be an interesting method to reduce the NAs content in the crude oil besides its esters are valuable commodity and can be used as added lubricant in the oils. In this study, NAs reduction kinetics were investigated in a batch type reactor with subcritical methanol, the experiments were performed at temperatures of 150-210°C and fixed methanol partial pressure of 2 MPa. Findings of this study demonstrate that the 59% of total acid number (TAN) reduction was achieved at the temperature of 210°C, methanol partial pressure of 2 MPa and reaction time of 150 min. The TAN reduction followed second order kinetics with activation energy and frequency factor of 54.15 KJ/mol and 7.6×103, respectively. These results suggest that subcritical methanol can be an effective to reduce the TAN non-catalytically.

  9. Kinetics and reaction pathways of total acid number reduction of cyclopentane carboxylic acid using subcritical methanol

    Directory of Open Access Journals (Sweden)

    Mandal Pradip C.

    2016-09-01

    Full Text Available Cyclopentane carboxylic acid (CPCA is a model compound of Naphthenic acids (NAs. This objective of this paper is to discover total acid number (TAN reduction kinetics and pathways of the reaction between CAPA and subcritical methanol (SubC-MeOH. The experiments were carried out in an autoclave reactor at temperatures of 180-220°C, a methanol partial pressure (MPP of 3 MPa, reaction times of 0-30 min and CPCA initial gas phase concentrations of 0.016-0.04 g/mL. TAN content of the samples were analyzed using ASTM D 974 techniques. The reaction products were identified and quantified with the help of GC/MS and GC-FID respectively. Experimental results reveal that TAN removal kinetics followed first order kinetics with an activation energy of 13.97 kcal/mol and a pre-exponential factor of 174.21 s-1. Subcritical methanol is able to reduce TAN of CPCA decomposing CPCA into new compounds such as cyclopentane, formaldehyde, methyl acetate and 3-pentanol.

  10. Ultrasound-Enhanced Subcritical CO2 Extraction of Lutein from Chlorella pyrenoidosa.

    Science.gov (United States)

    Fan, Xiao-Dan; Hou, Yan; Huang, Xing-Xin; Qiu, Tai-Qiu; Jiang, Jian-Guo

    2015-05-13

    Lutein is an important pigment of Chlorella pyrenoidosa with many beneficial functions in human health. The main purpose of this study was to extract lutein from C. pyrenoidosa using ultrasound-enhanced subcritical CO2 extraction (USCCE). Effects of operating conditions on the extraction, including extraction pretreatment, temperature, pressure, time, CO2 flow rate, and ultrasonic power, were investigated, and an orthogonal experiment was designed to study the effects of extraction pressure, temperature, cosolvent amount, and time on the extraction yields. The USCCE method was compared with other extraction methods in terms of the yields of lutein and the microstructure of C. pyrenoidosa powder by scanning electron microscopy. A maximal extraction yield of 124.01 mg lutein/100 g crude material was achieved under optimal conditions of extraction temperature at 27 °C, extraction pressure at 21 MPa, cosolvent amount at 1.5 mL/g ethanol, and ultrasound power at 1000 W. Compared to other methods, USCCE could significantly increase the lutein extraction yield at lower extraction temperature and pressure. Furthermore, the kinetic models of USCCE and subcritical CO2 extraction (SCCE) of lutein from C. pyrenoidosa were set as E = 130.64 × (1 - e(-0.6599t)) and E = 101.82 × (1 - e(-0.5683t)), respectively. The differences of parameters in the kinetic models indicate that ultrasound was able to enhance the extraction process of SCCE.

  11. Optimization of Subcritical Water Extraction of Resveratrol from Grape Seeds by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Yajie Tian

    2017-03-01

    Full Text Available The subcritical water extraction (SWE is a high-efficiency and environment-friendly extraction method. The extraction of resveratrol (RES of grape seeds obtained from the wine production process was proposed using subcritical water extraction (SWE. The effects of different extraction process parameters on RES yield were investigated by single factors. Extraction optimization was conducted using response surface methodology (RSM. Extraction temperature was proven to be the most significant factor influencing RES yield. The optimal conditions was as follows: extraction pressure of 1.02 MPa, temperature of 152.32 °C, time of 24.89 min, and a solid/solvent ratio of 1:15 g/mL. Under these optimal conditions, the predicted extraction RES yield was 6.90 μg/g and the recoveries was up to 91.98%. Compared to other previous studies, this method required less pollution and less treatment time to extract RES from grape seeds. From these results, added economic value to this agroindustrial residue is proposed using environmentally friendly extraction techniques.

  12. Release of phenolic acids from defatted rice bran by subcritical water treatment.

    Science.gov (United States)

    Fabian, Cynthia; Tran-Thi, Ngoc Yen; Kasim, Novy S; Ju, Yi-Hsu

    2010-12-01

    Oil production from rice bran, an undervalued by-product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV-B-protecting and anti-tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. Analysis of total phenolics using Folin-Ciocalteu reagent showed about 2-20 g gallic acid equivalent kg(-1) bran in the extracts. High-performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4-2 g kg(-1) bran). Ferulic, p-coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p-coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry.

  13. Pilot-scale subcritical solvent extraction of curcuminoids from Curcuma long L.

    Science.gov (United States)

    Kwon, Hye-Lim; Chung, Myong-Soo

    2015-10-15

    Curcuminoids consisted curcumin, demethoxycurcumin and bisdemethoxycurcumin, were extracted from turmeric using subcritical solvent by varying conditions of temperature (110-150 °C), time (1-10 min), pressure (5-100 atm), solid-to-solvent ratio, and mixing ratio of solvent. Preliminary lab-scale experiments were conducted to determine the optimum extraction temperature and mixing ratio of water and ethanol for the pilot-scale extraction. The maximum yield of curcuminoids in the pilot-scale system was 13.58% (curcumin 4.94%, demethoxycurcumin 4.73%, and bisdemethoxycurcumin 3.91% in dried extracts) at 135 °C/5 min with water/ethanol mixture (50:50, v/v) as a solvent. On the other hand, the extraction yields of curcuminoids were obtained as 10.49%, 13.71% and 13.96% using the 50%, 95% and 100% ethanol, respectively, at the atmospheric condition (60 °C/120 min). Overall results showed that the subcritical solvent extraction is much faster and efficient extraction method considering extracted curcuminoids contents and has a potential to develop a commercial process for the extraction of curcuminoids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Production of valued materials from squid viscera by subcritical water hydrolysis.

    Science.gov (United States)

    Uddin, M Salim; Ahn, Hyang-Min; Kishimura, Hideki; Chun, Byung-Soo

    2010-09-01

    Subcritical water hydrolysis was carried out to produce valued materials from squid viscera, the waste product of fish processing industries. The reaction temperatures for hydrolysis of rawand deoiled squid viscera were maintained from 180 to 280 degrees C for5 min. The ratio of material to water forhydrolysis was 1:50. Most of the proteins from deoiled squid viscera were recovered at high temperature. The protein yield in raw squid viscera hydrolyzate decreased with the rise of temperature. The reducing sugar yield was higher at high temperature in subcritical water hydrolysis of both raw and deoiled squid viscera. The highest yield of amino acids in raw and deoiled squid viscera hydrolyzates were 233.25 +/- 3.25 and 533.78 +/- 4.13 mg g(-1) at 180 and 280 degrees C, respectively. Most amino acids attained highest yield at the reaction temperature range of 180-220 degrees C and 260-280 degrees C for raw and deoiled samples, respectively. The recovery of amino acids from deoiled squid viscera was about 1.5 times higher than that of raw squid viscera.

  15. Subcritical convection in a rapidly rotating sphere at low Prandtl number

    CERN Document Server

    Guervilly, Celine

    2016-01-01

    We study non-linear convection in a low Prandtl number fluid ($Pr = 0.01-0.1$) in a rapidly rotating sphere with internal heating. We use a numerical model based on the quasi-geostrophic approximation, in which variations of the axial vorticity along the rotation axis are neglected, whereas the temperature field is fully three-dimensional. We identify two separate branches of convection close to onset: (i) a well-known weak branch for Ekman numbers greater than $10^{-6}$, which is continuous at the onset (supercritical bifurcation) and consists of a superposition of thermal Rossby waves, and (ii) a novel strong branch at lower Ekman numbers, which is discontinuous at the onset. The strong branch becomes subcritical for Ekman numbers of the order of $10^{-8}$. On the strong branch, the Reynolds number of the flow is greater than $10^3$, and a strong zonal flow with multiple jets develops, even close to the non-linear onset of convection. We find that the subcriticality is amplified by decreasing the Prandtl nu...

  16. Beam transient analyses of Accelerator Driven Subcritical Reactors based on neutron transport method

    Energy Technology Data Exchange (ETDEWEB)

    He, Mingtao; Wu, Hongchun [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Wang, Kunpeng [Nuclear and Radiation Safety Center, PO Box 8088, Beijing 100082 (China); Li, Xunzhao; Zhou, Shengcheng [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China)

    2015-12-15

    Highlights: • A transport-based kinetics code for Accelerator Driven Subcritical Reactors is developed. • The performance of different kinetics methods adapted to the ADSR is investigated. • The impacts of neutronic parameters deteriorating with fuel depletion are investigated. - Abstract: The Accelerator Driven Subcritical Reactor (ADSR) is almost external source dominated since there is no additional reactivity control mechanism in most designs. This paper focuses on beam-induced transients with an in-house developed dynamic analysis code. The performance of different kinetics methods adapted to the ADSR is investigated, including the point kinetics approximation and space–time kinetics methods. Then, the transient responds of beam trip and beam overpower are calculated and analyzed for an ADSR design dedicated for minor actinides transmutation. The impacts of some safety-related neutronics parameters deteriorating with fuel depletion are also investigated. The results show that the power distribution varying with burnup leads to large differences in temperature responds during transients, while the impacts of kinetic parameters and feedback coefficients are not very obvious. Classification: Core physic.

  17. The Free Overfall in Circular Sections with Different Flat Base in Supercritical and Subcritical Flow Regimes

    Directory of Open Access Journals (Sweden)

    A.R. Vatankhah

    2017-01-01

    Full Text Available Introduction: A free overfall offers a simple device for flow discharge measuring by a single measurement of depth at the end of the channel yb which is known as the end depth or brink depth. When the bottom of a channel drops suddenly, the flow separates from sharp edge of the brink and the pressure distribution is not hydrostatic because of the curvature of the flow. In channels with subcritical flow regime, control section occurs at the upstream with a critical depth (yc. Although pressure distribution at the critical depth is hydrostatic, the location of the critical depth can vary with respect to the discharge value. So, the end depth at brink is offered to estimate the discharge. A unique relationship between the brink depth (yb and critical depth (yc, known as end-depth ratio (EDR = yb/yc, exist. Since a relationship between the discharge and critical depth exists, the discharge can ultimately be related to yb. However, when the approaching flow is supercritical, critical section does not exist. Therefore, the discharge will be a function of end depth and channel longitudinal slope. In current study, an analytical model is presented for a circular free overfall with different flat base height in subcritical and supercritical flow regimes. The flow over a drop in a free overfall is simulated by applying the energy to calculate the EDR and end depth-discharge (EDD relationship. End-depth-discharge relationship: The flow of a free overfall in a channel can be assumed that is similar to the flow over a sharp-crested weir by taking weir height equal to zero. It is assumed that pressure at the end section is atmospheric, and also streamlines at the end section are parallel. To account for the curvature of streamlines, the deflection of jet due to gravity, the coefficient of contraction, Cc, is considered. At a short distance upstream the end section, the pressure is hydrostatic. By applying the energy equation between end section and control

  18. Damage evolution under cyclic multiaxial stress state: A comparative analysis between glass/epoxy laminates and tubes

    DEFF Research Database (Denmark)

    Quaresimin, M.; Carraro, P.A.; Mikkelsen, Lars Pilgaard

    2014-01-01

    In this work an experimental investigation on damage initiation and evolution in laminates under cyclic loading is presented. The stacking sequence [0/θ2/0/-θ2]s has been adopted in order to investigate the influence of the local multiaxial stress state in the off-axis plies and the possible effect...

  19. Resting state functional connectivity of the anterior cingulate cortex in veterans with and without post-traumatic stress disorder

    NARCIS (Netherlands)

    Kennis, Mitzy; Rademaker, Arthur R.; van Rooij, Sanne J H; Kahn, René S.; Geuze, Elbert

    2015-01-01

    Post-traumatic stress disorder (PTSD) is an anxiety disorder that is associated with structural and functional alterations in several brain areas, including the anterior cingulate cortex (ACC). Here, we examine resting state functional connectivity of ACC subdivisions in PTSD, using a seed-based

  20. Self Efficacy and Some Demographic Variables as Predictors of Occupational Stress among Primary School Teachers in Delta State of Nigeria

    Science.gov (United States)

    Akpochafo, G. O.

    2014-01-01

    This study investigated self efficacy and some demographic variables as predictors of occupational stress among primary school teachers in Delta State. Three hypotheses were formulated to guide the study. The study adopted a descriptive survey design that utilized an expost-facto research type. A sample of one hundred and twenty primary school…

  1. Nutritional mitigation of winter thermal stress in gilthead seabream associated metabolic pathways and potential indicators of nutritional state

    DEFF Research Database (Denmark)

    Richard, Nadege; Silva, Tomé S.; Wulff, Tune

    2016-01-01

    and phenylalanine/tyrosine catabolism, and induced higher aerobic metabolism and gluconeogenesis. Results support the notion that WF diet had a positive effect on fish nutritional state by partially counteracting the effect of thermal stress and underlined the sensitivity of proteome data for nutritional...

  2. Digital Laser Speckle Technologies in Measuring Blood Flow in Biotissues and the Stressed-Strained State of the Maxillodental System

    Science.gov (United States)

    Rubnikovich, S. P.; Denisova, Yu. A.; Fomin, N. A.

    2017-11-01

    A method has been developed for estimating the stressed-strained state in the ″orthodontic apparatus-dentin″ system with the use of laser-optical diagnostics based on speckle photography. We have determined the indices of the stressed-strained state in the ″orthodontic apparatus-dentin″ system depending on the composition and form of the orthodontic arch cross section. We have determined the optimum indices of the stressed-strained state of orthodontic arches in patients with periodontium diseases in combination with maxillodental anomalies and deformations, to which the following arches correspond: from copper-nickel-titanium (CuNiTi) alloy with circular (0.012″, 0.013″, 0.014″, 0.016″, 0.018″), and rectangular (0.014 × 0.025″, 0.016 × 0.025″) cross sections, from titanium-molybdenum alloy (TMA) with a rectangular cross section (0.016 × 0.025″), and from stainless steel (SS) with a circular (0.016″, 0.018″) cross section. Direct correlation has been established between indices of the stressed-strained state in the ″orthodontic apparatus-dentin″ system and the periodontium capillary pressure (r = 0.78, p < 0.05), as well as inverse strong correlation with the periodontium microcirculation intensity (r = -0.88, p < 0.05).

  3. Benzo(a)pyrene accumulation in soils of technogenic emission zone by subcritical water extraction method

    Science.gov (United States)

    Sushkova, Svetlana; Minkina, Tatiana; Kizilkaya, Ridvan; Mandzhieva, Saglara; Batukaev, Abdulmalik; Bauer, Tatiana; Gulser, Coskun

    2016-04-01

    The purpose of research is the assessment of main marker of polycyclic aromatic hydrocarbons contamination, benzo[a]pyrene (BaP) content in soils of emission zone of the power complex plant in soils with use of ecologically clean and effective subcritical water extraction method. Studies were conducted on the soils of monitoring plots subjected to Novocherkassk Power Plant emissions from burning coal. In 2000, monitoring plots were established at different distances from the NPS (1.0-20.0 km). Soil samples for the determination of soil properties and the contents of BaP were taken from a depth of 0-20 cm. The soil cover in the region under study consisted of ordinary chernozems, meadow-chernozemic soils, and alluvial meadow soils. This soil revealed the following physical and chemical properties: Corg-3.1-5.0%, pH-7.3-7.6, ECE-31.2-47.6 mmol(+)/100g; CaCO3-0.2-1.0%, the content of physical clay - 51-67% and clay - 3-37%. BaP extraction from soils was carried out by a subcritical water extraction method. Subcritical water extraction of BaP from soil samples was conducted in a specially developed extraction cartridge made of stainless steel and equipped with screw-on caps at both ends. It was also equipped with a manometer that included a valve for pressure release to maintain an internal pressure of 100 atm. The extraction cartridge containing a sample and water was placed into an oven connected to a temperature regulator under temperature 250oC and pressure 60 atm. The BaP concentration in the acetonitrile extract was determined by HPLC. The efficiency of BaP extraction from soil was determined using a matrix spike. The main accumulation of pollutant in 20 cm layer of soils is noted directly in affected zone on the plots situated at 1.2, 1.6, 5.0, 8.0 km from emission source in the direction of prevailing winds. The maximum quantity of a pollutant was founded in the soil of the plot located mostly close to a source of pollution in the direction of prevailing winds

  4. Evaluation of phase stresses of Al sub 2 O sub 3 /YAG binary MGC by synchrotron radiation. Residual stress states and stress behavior of YAG phase

    CERN Document Server

    Suzuki, H; Akita, K; Yoshioka, Y; Waku, Y

    2003-01-01

    Melt Growth Composite material (MGC) consists of multiple single crystal with fine entangled in three dimensional network structures. The MGCs are thermally stable and have higher creep resistance. Furthermore, the flexural strength at room temperature can be maintained almost up to the melting point. In this study, in order to discuss the generation mechanism of residual stress in an Al sub 2 O sub 3 /Y sub 3 Al sub 5 O sub 1 sub 2 (YAG) binary MGC, the residual stresses of YAG phase were measured by X-rays from synchrotron radiation source. We used a method for stress determination of single crystal by using a position sensitive proportional counter (PSPC) system and a specimen-oscillating device. Lattice strains of left brace 4 6 10 right brace in the YAG phase were measured. The residual stresses were from 40 to 120 MPa in tension in the longitudinal direction which corresponds to the solidification direction, 80MPa in compression in the thickness direction, and 70MPa in tension in the width direction. Si...

  5. Altered amygdala resting-state functional connectivity in post-traumatic stress disorder

    Directory of Open Access Journals (Sweden)

    Christine Anne Rabinak

    2011-11-01

    Full Text Available Post-traumatic stress disorder (PTSD is often characterized by aberrant amygdala activation and functional abnormalities in corticolimbic circuitry, as elucidated by functional neuroimaging. These ‘activation’ studies have primarily relied on tasks designed to induce region-specific, and task-dependent brain responses in limbic (e.g., amygdala and paralimbic brain areas through the use of evocative probes such as personalized traumatic script-driven imagery and other negatively valenced emotional stimuli (e.g., threatening faces, aversive scenes, traumatic cues. It remains unknown if these corticolimbic circuit abnormalities exist at baseline or ‘at rest’, in the absence of fear/anxiety-related provocation and outside the context of task demands. Recently, a new approach to studying functional interconnectivity of brain regions derived from ‘resting state’ scans has elucidated systems-level neural network function that may be obscured by activation tasks and may help inform functional interpretations of brain activation patterns. Little is known about whether altered amygdala connectivity patterns exist at rest in PTSD. Therefore the primary aim of the present experiment was to investigate aberrant amygdala functional connectivity patterns in combat-related PTSD patients during resting state. Seventeen Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF veterans with combat-related PTSD (PTSD group and seventeen combat-exposed OEF/OIF veterans without PTSD (Combat-Exposed Control [CEC] group underwent an 8-minute resting-state functional magnetic resonance imaging scan. Using conventional methods to generate connectivity maps, we extracted the time series from an anatomically-derived amygdala ‘seed’ region and conducted voxel-wise correlation analyses across the entire brain to search for group differences (between PTSD and CEC groups in amygdala functional connectivity, which we hypothesized would localize to the medial

  6. State of stress in exhumed basins and implications for fluid flow: insights from the Illizi Basin, Algeria

    KAUST Repository

    English, Joseph M.

    2017-05-31

    The petroleum prospectivity of an exhumed basin is largely dependent on the ability of pre-existing traps to retain oil and gas volumes during and after the exhumation event. Although faults may act as lateral seals in petroleum traps, they may start to become hydraulically conductive again and enable fluid flow and hydrocarbon leakage during fault reactivation. We constrain the present day in situ stresses of the exhumed Illizi Basin in Algeria and demonstrate that the primary north–south and NW–SE (vertical strike-slip) fault systems in the study area are close to critical stress (i.e. an incipient state of shear failure). By contrast, the overpressured and unexhumed Berkine Basin and Hassi Messaoud areas to the north do not appear to be characterized by critical stress conditions. We present conceptual models of stress evolution and demonstrate that a sedimentary basin with benign in situ stresses at maximum burial may change to being characterized by critical stress conditions on existing fault systems during exhumation. These models are supportive of the idea that the breaching of a closed, overpressured system during exhumation of the Illizi Basin may have been a driving mechanism for the regional updip flow of high-salinity formation water within the Ordovician reservoirs during Eocene–Miocene time. This work also has implications for petroleum exploration in exhumed basins. Fault-bounded traps with faults oriented at a high angle to the maximum principal horizontal stress direction in strike-slip or normal faulting stress regimes are more likely to have retained hydrocarbons in exhumed basins than fault-bounded traps with faults that are more optimally oriented for shear failure and therefore have a greater propensity to become critically stressed during exhumation.

  7. Stress state of the box shell under the indentation of two inclusions

    Directory of Open Access Journals (Sweden)

    Vladimir А. Grishin

    2015-03-01

    Full Text Available Thin-walled structures are widely used in various fields in modern technologies of mechanical engineering, construction, aviation industry, shipbuilding, rocket engineering, oil, gas and other industries. Variety of forms of such structures, various loading conditions and pinning, presence of defects and inhomogeneities lead to wide range of different formulations of the problems of research on strength characteristics of such structures and methods used for this purpose. The characteristic feature of this type of problems is the difficulty of their analytical or numerical solving. Assessment of convergence of numerical method solution requires the ability to compare the numerical results with analytical solution results of the corresponding problem.The research is devoted to solving the problem of stress state of box-shell with rectangular profile and infinite length under the indentation of two symmetrically arranged thin rigid inclusions. The problem is reduced to a system of integral equations. The solution is sought in the space of functions that have nonintegrable singularities using the apparatus of the regularization of divergent integrals. Obtained infinite system of linear algebraic equations is solved by the method of reduction. There are obtained the numerical values of the upsettings of inclusions depending on inclusions length and ratios of geometric dimensions of the cross-section of the shell.

  8. Resting-State Neurophysiological Abnormalities in Posttraumatic Stress Disorder: A Magnetoencephalography Study

    Directory of Open Access Journals (Sweden)

    Amy S. Badura-Brack

    2017-04-01

    Full Text Available Posttraumatic stress disorder (PTSD is a debilitating psychiatric condition that is common in veterans returning from combat operations. While the symptoms of PTSD have been extensively characterized, the neural mechanisms that underlie PTSD are only vaguely understood. In this study, we examined the neurophysiology of PTSD using magnetoencephalography (MEG in a sample of veterans with and without PTSD. Our primary hypothesis was that veterans with PTSD would exhibit aberrant activity across multiple brain networks, especially those involving medial temporal and frontal regions. To this end, we examined a total of 51 USA combat veterans with a battery of clinical interviews and tests. Thirty-one of the combat veterans met diagnostic criteria for PTSD and the remaining 20 did not have PTSD. All participants then underwent high-density MEG during an eyes-closed resting-state task, and the resulting data were analyzed using a Bayesian image reconstruction method. Our results indicated that veterans with PTSD had significantly stronger neural activity in prefrontal, sensorimotor and temporal areas compared to those without PTSD. Veterans with PTSD also exhibited significantly stronger activity in the bilateral amygdalae, parahippocampal and hippocampal regions. Conversely, healthy veterans had stronger neural activity in the bilateral occipital cortices relative to veterans with PTSD. In conclusion, these data suggest that veterans with PTSD exhibit aberrant neural activation in multiple cortical areas, as well as medial temporal structures implicated in affective processing.

  9. A state of the art on primary side stress corrosion cracking in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. P.; Kim, J. S.; Han, J. H.; Lee, D. H.; Lim, Y. S.; Suh, J. H.; Hwang, S. S.; Hur, D. H

    1999-09-01

    A state of art on primary water stress corrosion cracking (PWSCC) of alloy 600 used as steam generator tubing of nuclear power plant and remedial action on the PWSCC were reviewed and analyzed. One of the major metallurgical factors which have effect on PWSCC is Cr carbide distribution. A semicontinuous intergranular Cr carbide distribution enhance PWSCC of alloy 600. PWSCC rate is reported to be reported to be proportional to exp(-50 cal/RT) {sigma}{sup 4}. PWSCC rate also increase with increase in hydrogen partial pressure from 0 to 150 ppm and then decreased with further increase in hydrogen partial pressure to 757 ppm. Development of PWSCC prediction technology which takes into account tubing material, fabrication process and operating history of steam generator is needed to manage PWSCC of domestic nuclear power plant. PWSCC has mainly occurred at expansion irregularities within tubesheet, expansion transitions, dented tube support plate intersections and transition and apex of U bend. Remedial actions to PWSCC are sleeving, plugging, temperature reduction, Ni plating, Ni sleeving, shot peening and steam generator replacement in worst case. Option to remedial actions depend on plant specific such as plant age, leak rate from primary to secondary, density and progression of PWSCC. Ni sleeving developed in Framatome seems to be a powerful method because it never subject to PWSCC. Remedial action should be developed and evaluated for possible PWSCC of domestic nuclear power plant. (author)

  10. Numerical simulation of stress-strain state of electrophoretic shell molds

    Science.gov (United States)

    Sviridov, A. V.; Odinokov, V. I.; Dmitriev, E. A.; Evstigneev, A. I.; Bashkov, O. V.

    2017-10-01

    In the foundry engineering, castings obtained in one-piece non-gas-generating high-refractory electrophoretic shell molds (ShM) by investment patterns (IP) have an increased rejects percentage associated with low deformation resistance and crack resistance of the SM at different stages of their formation and manufacturing. Crack resistance of the ShM based on IP depends mainly on their stress-strain state (SSS) at various stages of mold forming. SSS decrease significantly improves their crack resistance and decreases their rejects percentage of castings occurring due to clogging and surface defects. In addition, the known methods of decreasing the SSS are still poorly understood. Thus, current research trends are to determine SSS at each stage of ShM forming and develop the ways to decrease it. Theoretical predicting of crack formation in multiple-layer axisymmetric shell molds is given in the work [1], and SSS of multiple-layer axisymmetric shell molds is given in the work [2]. Monolayer electrophoretic ShM had a lack of concern in this field, thus it became an argument for the present workMathematical Model of ShM SSS

  11. NEUROREHABILITATION OF POST-TRAUMATIC STRESS AND DEPRESSIVE BEHAVIORS BY BRAIN STATE CONDITIONING

    Directory of Open Access Journals (Sweden)

    Vijendra K. SINGH

    2009-06-01

    Full Text Available Brain State Conditioning™ (BSC is an innovative technology that optimizes brainwaves in real-time to achieve balance and harmony of the human brain. Since the brain function is imbalanced in individuals with psychiatric disorders and neurological diseases, we explored the possibility of using this technology to help people with post-traumatic stress disorder (PTSD and depression. We conducted a pilot study of 8 adult subjects who had symptoms of PTSD, depression and anxiety problems. The severity of symptoms was evaluated by Objective survey and Beck’s inventory for depression and anxiety. After the initial assessment of brain maps, individuals were administered with highly personalized training sessions, for example 4-5 sessions over 4-5 days. After the administration of BSC, we found a consistent decline in Beck’s inventory scores, which implied alleviation of depressive and anxiety tendencies. All subjects in the study responded to BSC technology and showed noticeable improvement in the quality of their lives. Thus we suggest that BSC is a viable approach to brainwave optimization to help people overcome health problems due to PTSD and depression.

  12. Sensitivity study of forecasted aftershock seismicity based on Coulomb stress calculation and rate- and state-dependent frictional response (Invited)

    Science.gov (United States)

    Cocco, M.; Hainzl, S.; Woessner, J.; Enescu, B.; Catalli, F.; Lombardi, A.

    2009-12-01

    It is nowadays well established that both Coulomb stress perturbations and the rate- and state-dependent frictional response of fault populations are needed to model the spatial and temporal evolution of seismicity. This represents the most popular physics-based approach to forecast the rate of earthquake production and its performances have to be verified with respect to alternative statistical methods. Despite the numerous applications of Coulomb stress interactions, a rigorous validation of the forecasting capabilities is still missing. In this work, we use the Dieterich (1994) physics-based approach to simulate the spatio-temporal evolution of seismicity caused by stress changes applied to an infinite population of nucleating patches modelled through a rate- and state-dependent friction law. According to this model, seismicity rate changes depend on the amplitude of stress perturbation, the physical constitutive properties of faults (represented by the parameter Aσ), the stressing rate and the background seismicity rate of the study area. In order to apply this model in a predictive manner, we need to understand the variability of input physical model parameters and their correlations. We first discuss the impact of uncertainties in model parameters and, in particular, in computed coseismic stress perturbations on the seismicity rate changes forecasted through the frictional model. We aim to understand how the variability of Coulomb stress changes affects the correlation between predicted and observed changes in the rate of earthquake production. We use the aftershock activity following the 1992 M 7.3 Landers (California) earthquake as one of our case studies. We analyze the variability of stress changes resulting from the use of different published slip distributions. We find that the standard deviation of the uncertainty is of the same size as the absolute stress change and that their ratio, the coefficient of variation (CV), is approximately constant in

  13. The psychoemotional status and cardiovascular system functional state of the first-year students under the influence of examination stress

    Directory of Open Access Journals (Sweden)

    Liliana K. Tokaeva

    2012-12-01

    Full Text Available The aim of this research is to study of the influence of examination stress on psycho-emotional status and functional state of the cardiovascular system of the 1-st year students of pedagogical high school. Methods – The study involved 105 young men aged 17-18 enrolled in the specialty "Physical Education". The studies were conducted during the period in-between the exams and during the examination session. The psycho-emotional status was determined by the SAN test questionnaire and test and the CH.D. Spielberg test, adapted for Russia by Ju.L. Khanin. The state of CVS autonomic regulation was evaluated by heart rate, blood pressure, endurance ratio, Kerdo index and the adaptive capacities by P.M. Bayevsky. Results – In the absence of exposure to stress in the majority of young men the studied parameters are within normal limits, indicating sufficient adaptive capabilities. A clear correlation between the level of personal anxiety in students and the nature of their reactivity to examination stress was found: the higher the anxiety level in a student is, the more stress resistance decreases and more pronounced changes in the cardiovascular system autonomic regulation appear. The strain of adaptation mechanism was found in a stressful situation in the first-year students with a high level of personal anxiety and satisfactory adaptation – in young men with average and low personal anxiety.

  14. Evaluation and visualization of multiaxial stress and strain states under non-proportional loading

    Directory of Open Access Journals (Sweden)

    M. Sakane

    2015-07-01

    Full Text Available This paper presents a simple method of determining stresses and strains and a severity of loading history under non-proportional loadings with defining the rotation angles of the maximum principal stress and strain in a three dimensional stress and strain space. Based on the method, non-proportional stress and strain ranges are derived and applicability of the range to the life evaluation for low carbon steel under non-proportional random strain paths are discussed. The strain range taking account of intensity of loading path reducing life can be suitable parameter for multiaxial fatigue life evaluation under multiaxial non-proportional loading. This paper also shows a method of visually presenting the principal stress and strain that assists designers to understand the loading mode whether proportional or non-proportional under 3 dimensional (6 stress/strain components multiaxial loading.

  15. Assessment of occupational stress and associated factors among bank employees in Vitoria, State of Espírito Santo, Brazil.

    Science.gov (United States)

    Petarli, Glenda Blaser; Zandonade, Eliana; Salaroli, Luciane Bresciani; Bissoli, Nazaré Souza

    2015-12-01

    Occupational stress has become a major cause of illness and a major risk to the psychological and social well-being of workers. In this context, the aim of this study was to estimate the prevalence of occupational stress in employees of a banking network in the municipal region of Vitória, state of Espírito Santo, and its association with sociodemographic variables and work characteristics. This cross-sectional study involved 525 bank employees. Occupational stress was evaluated using the short version of the Job Stress Scale. A multivariate analysis was conducted to evaluate the association between the Karasek quadrants and the independent variables. It was found that most bank employees belonged to the "passive jobs" quadrant (34.4%, n = 179) and were considered to have an intermediate risk of occupational stress. Considering the "low demand jobs" category as the standard, the increased risk of stress was associated with low education levels (odds ratio, 3.69, 95% CI, 1.64-8.28), working in bank agencies (odds ratio, 2.55, 95% CI, 1.36-4.77), a length of employment at the bank of more than five years (odds ratio, 3.32, 95% CI, 1.89-5.81), a daily work period of six hours (odds ratio, 2.72, 95% CI, 1.27-5.81), and, mainly, low social support (odds ratio, 2.57, 95% CI 1.45- 4.56).

  16. Thiol redox state and oxidative stress affect sclerotial differentiation of the phytopathogenic fungi Sclerotium rolfsii and Sclerotinia sclerotiorum.

    Science.gov (United States)

    Patsoukis, N; Georgiou, C D

    2008-01-01

    To investigate the involvement of oxidative stress and thiol redox state (TRS) in sclerotial differentiation of Sclerotium rolfsii and Sclerotinia sclerotiorum. Oxidative stress in these fungi was assessed by lipid peroxidation, which was higher in comparison with their nonsclerotiogenic counterpart strains. TRS [measured as glutathione (GSH) and cysteine] was associated with oxidative stress and differentiation using the TRS modulator and antioxidant Nu-acetylcysteine (AcCSH) and the GSH biosynthesis inducer and inhibitor l-2-oxo-thiazolidine-4-carboxylate and L-buthionine-S,R-sulphoximine (BSO) respectively. Differentiation and oxidative stress was decreased by AcCSH in both fungi. The decrease of differentiation by BSO was not associated with oxidative stress in these fungi. Differentiation and oxidative stress in both fungi depends on the availability of antioxidant noncytotoxic -SH groups and is not depended on any direct antioxidant role of GSH and its precursor cysteine. This study helps to understand the mechanism(s) of sclerotial differentiation in these agriculturally important phytopathogenic fungi and proposes that AcCSH can be used as potent fungicide by (i) acting as growth inhibiting cytotoxic oxidant and (ii) sustaining these fungi in their undifferentiated hyphal stage where they are vulnerable to degradation by soil micro-organisms.

  17. A DEM study of oedometric compression of model granular materials Initial state influence, stress ratio, elasticity, irreversibility.

    Directory of Open Access Journals (Sweden)

    Khalili Mohamed Hassan

    2017-01-01

    Full Text Available A DEM simulation study of spherical beads with elastic-frictional contacts in oedometric compression is carried out for a wide variety of initial states, differing in solid fraction Φ, coordination number z (independent of Φ in dense systems and inherent anisotropy. Stress ratio K0 = σ2/σ1, along with z, Φ and force and fabric anisotropies are monitored in compressions in which axial stress σ1 varies by more than 3 orders of magnitude. K0 tends to remain constant if the material was already one-dimensionally compressed in the assembling stage. Otherwise, it decreases steadily over the investigated stress range. K0 relates to force and fabric anisotropy parameters by a simple formula. Elastic moduli may express the response to very small stress increments about the transversely isotropic equilibrated states, although oedometric compression proves an essentially anelastic process, mainly due to friction mobilization. Despite apparent nearly reversible increases of axial strain ϵ1 (or density Φ, especially in dense samples, internal state evolutions are strongly irreversible, as evidenced by changes in z and K0. Fabric changes are reflected by anisotropic elastic moduli.

  18. Modeling of multi-phase microstructures in press hardened components: plastic deformation and fracture in different stress states

    Science.gov (United States)

    Golling, S.; Östlund, R.; Oldenburg, M.

    2017-09-01

    Hot stamping or press hardening is an industrialized technique with the aim of improving material properties by heat treatment and forming of a component in a single production stage. Within the field of press hardening the method of tailored material properties evolved. Components with tailored material properties possess different mechanical properties in designated areas. This paper presents an approach for modeling the mechanical response of mixed microstructures under different stress states. A homogenization method is used to predict the hardening of the material; the strain decomposition provides the possibility of applying a fracture criterion per phase. To validate the modeling approach for different stress states a set of samples with different notch and hole geometries as well as microstructural composition are produced. The combination of a homogenization method and a fracture criterion show good agreement with experimental results. The homogenization method is suitable to predict the hardening of the material with good accuracy. Fracture for different microstructural compositions is well predicted over a range of stress triaxialities relevant for sheet metal applications. It is concluded that the use of a homogenization method combined with a fracture model can be used to predict the mechanical response of mixed microstructures for a range of different stress states.

  19. Analysis of product distribution and characteristics in hydrothermal liquefaction of barley straw in subcritical and supercritical water

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this study, hydrothermal liquefaction of barley straw in subcritical and supercritical water with potassium carbonate catalyst was performed in the temperatures range of 280-400°C. The influence of final reaction temperature on products yield was investigated and some physicochemical properties...

  20. Supercritical CO(2) and subcritical propane extraction of pungent paprika and quantification of carotenoids, tocopherols, and capsaicinoids.

    Science.gov (United States)

    Gnayfeed, M H; Daood, H G; Illés, V; Biacs, P A

    2001-06-01

    Ground paprika (Capsicum annuum L.) was extracted with supercritical carbon dioxide (SC-CO(2)) and subcritical propane at different conditions of pressure and temperature to estimate the yield and variation in carotenoid, tocopherol, and capsaicinoid contents and composition. The yield of paprika extract was found to be affected by the extraction conditions with SC-CO(2) but fairly constant at different conditions with subcritical propane. The maximum yields of oleoresin were 7.9 and 8.1% of ground paprika by SC-CO(2) and subcritical propane, respectively. The quantitative distribution of carotenoids, tocopherols, and capsaicinoids between paprika extract and powder was influenced by extraction conditions. SC-CO(2) was inefficient in the extraction of diesters of xanthophylls even at 400 bar and 55 degrees C, whereas tocopherols and capsaicinoids were easy to extract at these conditions. Under mild conditions subcritical propane was superior to SC-CO(2) in the extraction of carotenoids and tocopherols but less efficient in the extraction of capsaicinoids.

  1. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    Science.gov (United States)

    Pan, Z.; Chou, I.-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water. ?? 2009 The Royal Society of Chemistry.

  2. Stress state reconstruction of oblique collision and evolution of deformation partitioning in W-Zagros (Iran, Kermanshah)

    Science.gov (United States)

    Navabpour, Payman; Angelier, Jacques; Barrier, Eric

    2008-11-01

    The W-Zagros of Iran is characterized by a deformation partitioning pattern with a right-lateral strike-slip motion along the Main Recent Fault and a shortening component across the Zagros Simple Fold Belt under the late Cenozoic N-S oblique collision between the Arabian and Iranian continental plates. In this study, we examined the brittle structures that developed during the mountain building process in the High Zagros Belt of Kermanshah Province, which is structurally located between the two partitioned components of deformation, to decipher the history of polyphase deformation and variations in stress fields within the sedimentary cover since the onset of collision. The earthquake focal mechanisms of W-Zagros were analysed to evaluate the recent stress fields within the basement. Analytic inversion techniques enabled us to determine and separate different brittle tectonic regimes in terms of stress tensors. Brittle tectonic analyses were carried out to reconstruct possible geometrical relationships between different structures and to establish relative chronologies of the corresponding stress tensor, with reference to folding. Our stress reconstruction indicates a major change in stress state from a Miocene-Pliocene syn-folding compressional regime to a Pliocene-Recent post-folding strike-slip system, with a significant anticlockwise reorientation of the horizontal σ1 stress axis from NE-SW to N-S. The results of the recent stress states indicate that the stress trends are similar throughout the basement and sedimentary cover. The differences between stress and strain axes suggest different possible degrees in partitioning of seismic and aseismic deformation, as revealed by earthquake focal mechanisms in the basement and geodetic surveys at the surface of the sedimentary cover. The integrated palaeostress results on the regional tectonic framework suggest that the late Cenozoic brittle tectonic evolution of the W-Zagros was achieved through the transition from

  3. Water Stress Assessment in Jharkhand State Using Soil Data and GIS

    African Journals Online (AJOL)

    In this paper an attempt has been made to study the interrelationship of water resources available with that of soil class and its properties including soil drainage and erosional characteristics which has been used to generate drainage stress map and water stress map inferring the basic reason for water scarcity in the district ...

  4. Investigation of the Residual Stress State in an Epoxy Based Specimen

    NARCIS (Netherlands)

    Baran, Ismet; Jakobsen, Johnny; Andreasen, Jens H.; Akkerman, Remko

    2015-01-01

    Process induced residual stresses may play an important role under service loading conditions for fiber reinforced composite. They may initiate premature cracks and alter the internal stress level. Therefore, the developed numerical models have to be validated with the experimental observations. In

  5. Exploring the Individual Contributory Personality Factors of Stress: A Survey of Washington State Elementary Teachers

    Science.gov (United States)

    Dean, Effie J.

    2010-01-01

    Prolonged stress is shown to lead to low productivity, which is one of the leading causes of poor performance, and high absenteeism/turnover in occupational fields (Norton, 2002). The field of education is a prime example of low productivity resulting from prolonged stress (Norton, 2002). Currently, there are many existing studies on environmental…

  6. Analysis of the Stress State in Brake Caliper Mounts of Front Motorbike Suspensions

    National Research Council Canada - National Science Library

    Croccolo, D; De Agostinis, M; Olmi, G; Tizzanini, A

    ... than the traditional one and allows using brake discs with a different diameter by simply adding or removing some spacers between the mounts and the caliper. Finally, in radial mounts screws are mainly stressed by axial loads instead of tangential ones. Since it is really difficult to relate the loads to the actual stresses acting on the front motorbike component...

  7. Stress-strain state of reinforced bimodulus beam on an elastic foundation

    Science.gov (United States)

    Beskopylny, A. N.; Kadomtseva, E. E.; Strelnikov, G. P.; Berdnik, Y. A.

    2017-10-01

    The paper provides the calculation theory of an arbitrary supported and arbitrary loaded reinforced beam filled with bimodulus material. The formulas determining normal stresses, bending moments, shear forces, rotation angles and a deflection of a rectangular crosssection beam reinforced with any number of bars aligned parallel to the beam axis have been obtained. The numerical study has been carried out to investigate an influence of a modulus of subgrade reaction on values of maximum normal stresses, maximum bending moments and a maximum deflection of a hinged supported beam loaded with a point force or uniform distributed load. The estimation is based on the method of initial parameters for a beam on elastic foundation and the Bubnov-Galerkin method. Values of maximum deflections, maximum bending moments and maximum stresses obtained by these methods coincide. The numerical studies show that taking into consideration the bimodulus of material leads to the necessity to calculate the strength analysis of both tensile stresses and compressive stresses.

  8. Children and adolescents treated for post-traumatic stress disorder at the Free State Psychiatric Complex

    Directory of Open Access Journals (Sweden)

    F J W Calitz

    2014-04-01

    Full Text Available Background. Children and adolescents can develop post-traumatic stress disorder (PTSD after exposure to a range of traumatic events, including domestic, political or community violence, violent crime, physical and sexual abuse, hijacking, witnessing a violent crime and motor vehicle accidents. This is particularly critical given the substantial challenge that PTSD poses to the healthy physical, cognitive and emotional development of children and adolescents. Methods. The clinical records of 1 229 children (age 2 - 11 years and adolescents (age 12 - 18 years treated at the Child Mental Health Unit of the Free State Psychiatric Complex (FSPC were screened for the diagnosis of PTSD and analysed for the purpose of this study. Results. Forty-nine (4.0% of the children and adolescents treated at the unit were diagnosed with PTSD, of whom most were female (63.3%. Approximately 22% of the participants had comorbid major depressive disorder. The main traumatic event in both groups was witnessing the death of a close relative (32.7%, followed by sexual assault (25%, rape (25% and physical attack (10.2%. Associated stressors identified included problems at school (55.1%, isolation (39%, fear or anxiety (37%, problematic family relationships (29%, emotional (27% and physical (23% abuse, and lack of social support (23%. Most of the participants (59.2% received psychotherapy. Conclusions. Children and adolescents referred to the FSPC are also exposed to traumatic events which lead to the development of PTSD. The Free State is a sprawling province with remote areas where specialist services and facilities are limited. It is therefore recommended that preventive programmes, training opportunities and consultation services are implemented to identify and treat children and adolescents with PTSD. Schools with limited access to psychological services and large classrooms, impeding the diagnosis and treatment of PTSD specifically, face similar challenges

  9. Bereavement, Level Stress and Coping Mechanism among Teacher Education Students of Samar State University: College Bereavement Study

    Directory of Open Access Journals (Sweden)

    Perlito Sabulaan Domingo

    2016-11-01

    Full Text Available Bereavement is a severe stressor that should be addressed properly. The study of Teacher education is very tight as it prepares soon to educator that will light the future of other young children. This study sought to determine the Level of Stress and Coping Mechanism on Bereavement among Teacher Education Students of Samar State University. It tested some assumption using the descriptive survey method on 76 identified students who experienced bereavement. It shows that respondent manifested highly emotional and physical stress rather than behavioral stress. It shows that social support is coping mechanism. The said study being the first bereavement research in the city could provide baseline information in the field of bereavement.

  10. A hybrid method for estimating the state of stress in ICDP-sponsored deep vertical boreholes (Invited)

    Science.gov (United States)

    Haimson, B. C.

    2010-12-01

    Hydraulic fracturing (HF) has been the method of choice for estimating the state of stress around deep vertical boreholes for the last four decades, starting with the Rangely, Colorado and the Michigan Basin measurements (Haimson, Tectonophysics, 1975; JGR, 1977). However, recently considerable controversy has developed regarding the reliability of the maximum horizontal stress σH as derived from the classical interpretation of HF recorded data, especially at great depths. In addition, in very deep holes, HF tests are sometimes incomplete, yielding only estimates of the minimum horizontal stress σh magnitude (example: KTB, Germany; see Brudy et al, JGR 1997). As a result, an alternative hybrid method for constraining all three principal in situ stresses and their directions around deep vertical boreholes has been developed and used at several ICDP (International Continental Scientific Drilling Program) sites. It involves HF tests for estimating σh, provided hydrofractures are vertical. The vertical stress σv is computed from the weight of the overlying strata. Assessing σH and its direction involves the use of geophysical logging such as the Borehole Acoustic Televiewer or the Formation Micro Imager. They capture oriented images of borehole breakouts, from which the oriented breakout span as it varies with depth is obtained. Laboratory true triaxial tests on specimens prepared out of core samples render the appropriate strength criterion for rock at the borehole wall. Using the condition of limit equilibrium between the local state of stress at the breakout-borehole intersections and the strength criterion, a non linear equation emerges from which the maximum horizontal principal stress is derived, thus completing the estimation of the prevailing state of stress. The use of this hybrid method is restricted to deep vertical boreholes that produce vertical hydrofractures and in which breakouts develop, with dimensions not affected by the drilling mud. Two ICDP

  11. Structure and stress state of Hawaiian island basalts penetrated by the Hawaii Scientific Drilling Project deep core hole

    Science.gov (United States)

    Morin, R.H.; Wilkens, R.H.

    2005-01-01

    As part of the Hawaii Scientific Drilling Project (HSDP), an exploratory hole was drilled in 1993 to a depth of 1056 meters below sea level (mbsl) and a deeper hole was drilled to 3098 mbsl in 1999. A set of geophysical well logs was obtained in the deeper hole that provides fundamental information regarding the structure and the state of stress that exist within a volcanic shield. The acoustic televiewer generates digital, magnetically oriented images of the borehole wall, and inspection of this log yields a continuous record of fracture orientation with depth and also with age to 540 ka. The data depict a clockwise rotation in fracture strike through the surficial Mauna Loa basalts that settles to a constant heading in the underlying Mauna Kea rocks. This behavior reflects the depositional slope directions of lavas and the locations of volcanic sources relative to the drill site. The deviation log delineates the trajectory of the well bore in three-dimensional space. This path closely follows changes in fracture orientation with depth as the drill bit is generally prodded perpendicular to fracture strike during the drilling process. Stress-induced breakouts observed in the televiewer log identify the orientations ot the maximum and minimum horizontal principal stresses to be north-south and east-west, respectively. This stress state is attributed to the combination of a sharp break in onshore-offshore slope that reduces stress east-west and the emergence of Kilauea that increases stress north-south. Breakouts are extensive and appear over approximately 30% of the open hole. Copyright 2005 by the American Geophysical Union.

  12. FINAL DESIGN REVIEW REPORT Subcritical Experiments Gen 2, 3-ft Confinement Vessel Weldment

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    A Final Design Review (FDR) of the Subcritical Experiments (SCE) Gen 2, 3-ft. Confinement Vessel Weldment was held at Los Alamos National Laboratory (LANL) on September 14, 2017. The review was a focused review on changes only to the confinement vessel weldment (versus a system design review). The changes resulted from lessons-learned in fabricating and inspecting the current set of confinement vessels used for the SCE Program. The baseline 3-ft. confinement vessel weldment design has successfully been used (to date) for three (3) high explosive (HE) over-tests, two (2) fragment tests, and five (5) integral HE experiments. The design team applied lessons learned from fabrication and inspection of these vessel weldments to enhance fit-up, weldability, inspection, and fitness for service evaluations. The review team consisted of five (5) independent subject matter experts with engineering design, analysis, testing, fabrication, and inspection experience. The

  13. Conceptual study of high power proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Ouyang Hua Fu; Xu Tao Guang

    2001-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. The ADS accelerator presented by the consists of a 5 MeV radio-frequency quadrupole, a 100 MeV independently phased superconducting cavity linac and a 1 GeV elliptical superconducting cavity linac. The accelerating structures and main parameters are determined and the research and development plan is considered

  14. Conceptual design based on scale laws and algorithms for sub-critical transmutation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Gu; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    In order to conduct the effective integration of computer-aided conceptual design for integrated nuclear power reactor, not only is a smooth information flow required, but also decision making for both conceptual design and construction process design must be synthesized. In addition to the aboves, the relations between the one step and another step and the methodologies to optimize the decision variables are verified, in this paper especially, that is, scaling laws and scaling criteria. In the respect with the running of the system, the integrated optimization process is proposed in which decisions concerning both conceptual design are simultaneously made. According to the proposed reactor types and power levels, an integrated optimization problems are formulated. This optimization is expressed as a multi-objective optimization problem. The algorithm for solving the problem is also presented. The proposed method is applied to designing a integrated sub-critical reactors. 6 refs., 5 figs., 1 tab. (Author)

  15. Kinetic model for the esterification of oleic acid catalyzed by zinc acetate in subcritical methanol

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chengcai; Deng, Tiansheng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Qi, Yongqin; Hou, Xianglin; Qin, Zhangfeng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China)

    2010-03-15

    The esterification of oleic acid in subcritical methanol catalyzed by zinc acetate was investigated in a batch-type autoclave. The effect of reaction conditions such as temperature, pressure, reaction time and molar ratio of oleic acid to methanol on the esterification was examined. The oleic acid conversion reached 95.0% under 220 C and 6.0 MPa with the molar ratio of methanol to oleic acid being 4 and 1.0 wt% zinc acetate as catalyst. A kinetic model for the esterification was established. By fitting the kinetic model with the experimental results, the reaction order n = 2.2 and activation energy E{sub a} = 32.62 KJ/mol were obtained. (author)

  16. The mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water

    Science.gov (United States)

    Yu, Zhuanni; Chen, Xiaolin; Xia, Shuwei

    2016-06-01

    In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.

  17. An integrated green process: Subcritical water, enzymatic hydrolysis, and fermentation, for biohydrogen production from coconut husk.

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Ranggina, Dian; Nurtono, Tantular; Widjaja, Arief

    2017-10-09

    The objective of this work is to develop an integrated green process of subcritical water (SCW), enzymatic hydrolysis and fermentation of coconut husk (CCH) to biohydrogen. The maximum sugar yield was obtained at mild severity factor. This was confirmed by the degradation of hemicellulose, cellulose and lignin. The tendency of the changing of sugar yield as a result of increasing severity factor was opposite to the tendency of pH change. It was found that CO2 gave a different tendency of severity factor compared to N2 as the pressurizing gas. The result of SEM analysis confirmed the structural changes during SCW pretreatment. This study integrated three steps all of which are green processes which ensured an environmentally friendly process to produce a clean biohydrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, D. B., E-mail: dschaeffer@physics.ucla.edu; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Gekelman, W.; Niemann, C. [Department of Physics and Astronomy, University of California—Los Angeles, Los Angeles, California 90095 (United States); Winske, D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2015-11-15

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  19. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, Adnane; Turner, Drew L.; Wilson, Lynn B.; Dimmock, Andrew P.; Pulkkinen, Tuija I.

    2017-09-01

    The discovery of long-lived electrostatic coherent structures with large-amplitude electric fields (1≤slant E ≤slant 500 mV/m) by the Van Allen Probes has revealed alternative routes through which planetary radiation belts’ acceleration can take place. Following previous reports showing that small phase-space holes, with qφ /{T}ec≃ {10}-2{--}{10}-3, could result from electron interaction with large-amplitude whistlers, we demonstrate one possible mechanism through which holes can grow nonlinearly (I.e., γ \\propto \\sqrt{φ }) and subcritically as a result of momentum exchange between hot and cold electron populations. Our results provide an explanation for the common occurrence and fast growth of large-amplitude electron phase-space holes in the Earth’s radiation belts.

  20. A review on green trend for oil extraction using subcritical water technology and biodiesel production.

    Science.gov (United States)

    Abdelmoez, Weal; Ashour, Eman; Naguib, Shahenaz M

    2015-01-01

    It became a global agenda to develop clean alternative fuels which were domestically available, environmentally acceptable and technically feasible. Thus, biodiesel was destined to make a substantial contribution to the future energy demands of the domestic and industrial economies. Utilization of the non edible vegetable oils as raw materials for biodiesel production had been handled frequently for the past few years. The oil content of these seeds could be extracted by different oil extraction methods, such as mechanical extraction, solvent extraction and by subcritical water extraction technology SWT. Among them, SWT represents a new promising green extraction method. Therefore this review covered the current used non edible oil seeds for biodiesel production as well as giving a sharp focus on the efficiency of using the SWT as a promising extraction method. In addition the advantages and the disadvantages of the different biodiesel production techniques would be covered.

  1. Nonlinear elastic behavior of sub-critically damaged body armor panel

    Science.gov (United States)

    Fisher, Jason T.; Chimenti, D. E.

    2012-05-01

    A simple go/no-go test for body armor panels using pressure-sensitive, dye-indicator film (PSF) has been shown to be statistically effective in revealing subcritical damage to body armor panels. Previous measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Further impact tests on armor worn by a human resuscitation dummy using instrumented masses with an attached accelerometer and embedded force transducer have been performed and analyzed. New impact tests have shown a reliable correlation between PSF indication (as digitized images) and impact force for a wide range of impactor energies and masses. Numerical evaluation of digital PSF images is presented and correlated with impact parameters. Relationships between impactor mass and energy, and corresponding measured force are shown. We will also report on comparisons between ballistic testing performed on panels damaged under various impact conditions and tests performed on undamaged panels.

  2. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    Science.gov (United States)

    Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio

    2014-04-01

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.

  3. Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

    Science.gov (United States)

    O'Kelly, David Sean

    Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

  4. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Science.gov (United States)

    Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Winske, D.; Gekelman, W.; Niemann, C.

    2015-11-01

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  5. Present-day stress state analysis on the Big Island of Hawaíi, USA

    Science.gov (United States)

    Pierdominici, Simona; Kueck, Jochem; Millett, John; Planke, Sverre; Jerram, Dougal A.; Haskins, Eric; Thomas, Donald

    2017-04-01

    We analyze and interpret the stress features from a c. 1.5 km deep fully cored borehole (PTA2) on the Big Island of Hawaíi within the Humúula saddle region, between the Mauna Kea and Mauna Loa volcanoes. The Big Island of Hawaii comprises the largest and youngest island of the Hawaiian-Emperor seamount chain and is volumetrically dominated by shield stage tholeiitic volcanic rocks. Mauna Kea is dormant whereas Mauna Loa is still active. There are also a series of normal faults on Mauna Loa's northern and western slopes, between its two major rift zones, that are believed to be the result of combined circumferential tension from the two rift zones and from added pressure due to the westward growth of the neighboring Kīlauea volcano. The PTA2 borehole was drilled in 2013 into lava dominated formation (Pahoehoe and Aā) as part of the Humúula Groundwater Research Project (HGPR) with the purpose of characterizing the groundwater resource potential in this area. In 2016 two downhole logging campaigns were performed by the Operational Support Group of the International Continental Scientific Drilling Program (ICDP) to acquire a set of geophysical data as part of the Volcanic Margin Petroleum Prospectivity (VMAPP) project. The main objective of the logging campaign was to obtain high quality wireline log data to enable a detailed core-log integration of the volcanic sequence and to improve understanding of the subsurface expression of volcanic rocks. We identify stress features (e.g. borehole breakouts) and volcanic structures (e.g. flow boundaries, vesicles and jointing) at depth using borehole images acquired with an ABI43 acoustic borehole televiewer. We analyzed and interpreted the stress indicators and compared their orientation with the regional stress pattern. We identified a set of stress indicators along the hole dominantly concentrated within the lower logged interval of the PTA2 borehole. Two primary horizontal stress indicators have been taken into account

  6. Global bifurcations to subcritical magnetorotational dynamo action in Keplerian shear flow

    Science.gov (United States)

    Riols, A.; Rincon, F.; Cossu, C.; Lesur, G.; Longaretti, P.-Y.; Ogilvie, G. I.; Herault, J.

    2013-09-01

    Magnetorotational dynamo action in Keplerian shear flow is a three-dimensional, nonlinear magnetohydrodynamic process whose study is relevant to the understanding of accretion and magnetic field generation in astrophysics. Transition to this form of dynamo is subcritical and shares many characteristics of transition to turbulence in non-rotating hydrodynamic shear flows. This suggests that these different fluid systems become active through similar generic bifurcation mechanisms, which in both cases have eluded detailed understanding so far. In this paper, we investigate numerically the bifurcation mechanisms at work in the incompressible Keplerian magnetorotational dynamo problem in the shearing box framework. Using numerical techniques imported from dynamical systems research, we show that the onset of chaotic dynamo action at magnetic Prandtl numbers larger than unity is primarily associated with global homoclinic and heteroclinic bifurcations of nonlinear magnetorotational dynamo cycles. These global bifurcations are supplemented by local bifurcations of cycles marking the beginning of period-doubling cascades. This suggests that nonlinear magnetorotational dynamo cycles provide the pathway to turbulent injection of both kinetic and magnetic energy in incompressible magnetohydrodynamic Keplerian shear flow in the absence of an externally imposed magnetic field. Studying the nonlinear physics and bifurcations of these cycles in different regimes and configurations may subsequently help to better understand the conditions of excitation of magnetohydrodynamic turbulence and instability-driven dynamos in various astrophysical systems and laboratory experiments. The detailed characterization of global bifurcations provided for this three-dimensional subcritical fluid dynamics problem may also prove useful for the problem of transition to turbulence in hydrodynamic shear flows.

  7. Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division

    2008-10-22

    One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.

  8. Application of supercritical and subcritical fluids for the extraction of hazardous materials from soil

    Directory of Open Access Journals (Sweden)

    Skorupan Dara

    2002-01-01

    Full Text Available Subcritical and supercritical extractions are novel, non destructive techniques which can be applied for the removal of hazardous compounds from contaminated soil without any changes of the soil composition and structure. The aim of the presented review paper is to give information on up-to day results of this method commonly applied by several institutions worldwide. Interest in the application of SC CO2 has been more expressed in the last two decades, which may be related to its favorable characteristics (non-toxic, non-flammable, increase diffusion into small pores, low viscosity under SC conditions, low price and others. However, interest in wet oxidation (WO and especially in SCWO (the application of water under supercritical conditions with air has also increased in the last few years. Interest in H2O as a SC fluid, as well as in extraction with water under subcritical conditions may also be related to specific characteristics and the enhanced rate of extraction. Moreover, the solubility of some specific compounds present in soil can be easily changed by adjusting the pressure and temperature of extraction. The high price of the units designed to operate safely at a pressure and temperature much higher than the a critical one of the applied fluids is the main reason why, at present, there is no more broader application of such techniques for the removal hazardous materials from contaminated soil. In the present paper, among many literature citations and their overall review, some specific details related to the development of specific analytical methods under SC conditions are also considered.

  9. TNT and RDX degradation and extraction from contaminated soil using subcritical water.

    Science.gov (United States)

    Islam, Mohammad Nazrul; Shin, Moon-Su; Jo, Young-Tae; Park, Jeong-Hun

    2015-01-01

    The use of explosives either for industrial or military operations have resulted in the environmental pollution, poses ecological and health hazard. In this work, a subcritical water extraction (SCWE) process at laboratory scale was used at varying water temperature (100-175 °C) and flow rate (0.5-1.5 mL min(-1)), to treat 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soil, to reveal information with respect to the explosives removal (based on the analyses of soil residue after extraction), and degradation performance (based on the analyses of water extracts) of this process. Continuous flow subcritical water has been considered on removal of explosives to avoid the repartitioning of non-degraded compounds to the soil upon cooling which usually occurs in the batch system. In the SCWE experiments, near complete degradation of both TNT and RDX was observed at 175 °C based on analysis of water extracts and soil. Test results also indicated that TNT removal of >99% and a complete RDX removal were achieved by this process, when the operating conditions were 1 mL min(-1), and treatment time of 20 min, after the temperature reached 175 °C. HPLC-UV and ion chromatography analysis confirmed that the explosives underwent for degradation. The low concentration of explosives found in the process wastewater indicates that water recycling may be viable, to treat additional soil. Our results have shown in the remediation of explosives contaminated soil, the effectiveness of the continuous flow SCWE process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Highly Selective and Considerable Subcritical Butane Extraction to Separate Abamectin in Green Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Pang, Huili; Qin, Guangyong

    2017-06-01

    We specially carried out the subcritical butane extraction to separate abamectin from tea leaves. Four parameters, such as extraction temperature, extraction time, number of extraction cycles, and solid-liquid ratio were studied and optimized through the response surface methodology with design matrix developed by Box-Behnken. Seventeen experiments with three various factors and three variable levels were employed to investigate the effect of these parameters on the extraction of abamectin. Besides, catechins, theanine, caffeine, and aroma components were determined by both high-performance liquid chromatography and gas chromatography-mass spectrometry to evaluate the tea quality before and after the extraction. The results showed that the extraction temperature was the uppermost parameter compared with others. The optimal extraction conditions selected as follows: extraction temperature, 42°C; number of extraction cycles and extraction time, 1 and 30 min, respectively; and solid-liquid ratio, 1:10. Based on the above study, the separation efficiency of abamectin was up to 93.95%. It is notable that there has a quite low loss rate, including the negligible damage of aroma components, the bits reduce of catechins within the range of 0.7%-13.1%, and a handful lessen of caffeine and theanine of 1.81% and 2.6%, respectively. The proposed method suggested subcritical butane possesses solubility for lipid-soluble pesticides, and since most of the pesticides are attached to the surfaces of tea, thus the as-applied method was successfully effective to separate abamectin because of the so practical and promising method.

  11. The effect of positioning on preterm infants' sleep-wake states and stress behaviours during exposure to environmental stressors.

    Science.gov (United States)

    Peng, Niang-Huei; Chen, Li-Li; Li, Tsai-Chung; Smith, Marlaine; Chang, Yu-Shan; Huang, Li-Chi

    2014-12-01

    Previous studies separately examined the effects of positioning or environmental stressors on preterm infants' sleep and stress. Since positioning and environmental stressors occur simultaneously during infant hospitalization exploring these variables in the same study may offer new insights. A quasi-experimental study by one-group interrupted time-series design. In the current study, a total of 22 preterm infants were enrolled. Each infant was moved to either the supine or prone position for an hour at a time. Infants were videotaped and the sleep-wake states, stress behaviours and environmental conditions (light, noise and stimulation/handling) were recorded during the observation period. A total of 80 observations from 22 infants were accrued. In the supine position, preterm infants demonstrated more frequent waking states after adjusting for various environmental stressors (p position after adjusting for various environmental stressors (p position is a more favourable position for facilitating sleep and reducing stress for preterm infants exposed to varying environmental stressors. Preterm infants present different stress behaviours in response to varying types of environmental stimuli. © The Author(s) 2013.

  12. STRESS-STRAIN STATE OF MASONRY OF CHIMNEY TRUNKS FROM DEAD LOAD, WIND LOAD AND TEMPERATURE EFFECT

    Directory of Open Access Journals (Sweden)

    YAROVOJ Yu. N.

    2017-02-01

    Full Text Available Summary. Formulation of the problem. Nowadays there are more than 3000 masonry chimneys in Ukraine. The life of most chimneys is more then 20 years, about 20 % of the chimneys are operated for more than 50 years. Inspection of the technical condition of the chimneys, evaluation of their load-carrying capacity and design of recommendations for further work of chimneys is an actual research task. There are no actual normative documents about calculation and design of masonry and reinforced concrete chimneys in Ukraine. In reference literature and normative documents, the design scheme of the chimney trunk is adopted in the form of a cantilever beam. In the calculation it is recommended to take into account the longitudinal-transverse bending from the action of the wind load and its own weight, as well as the roll of the foundation. Strength test of the trunk is performed separately for horizontal sections and for vertical sections. For horizontal sections it is performed for longitudinal force and bending moment from its own weight and wind load, for vertical sections - for temperature forces after the temperature drop along the thickness of the barrel wall. This approach doesn't fully reflect the real work of the masonry, which is in a complicated state of stress. Purpose. To perform a comparative calculation of the various trunks of masonry chimney, analyze the factors affecting the stress-strain state of the masonry trunks. Conclusions. It is proposed carry and calculation of the masonry trunks for the temperature impact in elastic stage with regard to join work masonry and clamping rings, taking into account not only the tangential, but also the longitudinal temperature stresses and analyze the work of the masonry in the plane stress state. Proposed calculation makes it possible to determine the moment of formation of force and temperature cracks in the masonry. It is necessary to clarify the stress-strain state and criteria of the trunks

  13. Forming the stress state of a vibroisolated building in the process of mounting rubber steel vibration isolator

    Directory of Open Access Journals (Sweden)

    Dashevskiy Mikhail Aronovich

    2015-12-01

    Full Text Available The necessity to specificate the formation process of stress-strain state of buildings in the construction process is a new problem which requires including real production characteristics going beyond calculation models into calculation methods. Today the construction process lacks this specification. When mounting vibroisolators the stress-strein of a structure state is changing. The mounting method of vibroisolators is patented and consists in multistage successive compression loading of each vibroisolator with the constant speed and following fixation of this displacement. The specified engineering method of rubber-steel pads calculation in view of change of their form during deformation, nonlinearity, rheological processes is offered. Resilient pads look like rubber plates rectangular in plane reinforced on the basic surfaces with metal sheets. The influence of a time-variable static load and free vibrations of loaded pads are considered.

  14. Experimental and Numerical Research of Stress-Strain State of Homogeneous Soil Massif at Interaction with Single Barrette

    Science.gov (United States)

    Ter-Martirosyan, Z. G.; Ter-Martirosyan, A. Z.; Sidorov, V. V.

    2017-11-01

    Deep foundations are used for the design of high-rise buildings due to a large pressure transfer on the soil base. The foundations of buildings sometimes use barrettes which are able to perceive significant vertical and horizontal loads due to improved lateral surface. Barrettes have increased load bearing capacity as compared with large diameter piles. In modern practice the interaction between barrettes and soil is investigated by analytical and numerical methods and has no sufficient experimental confirmation. The review of experimental methods for the research of the intense stress-strain state of the uniform soil massif at interaction with elements of a deep foundation is provided in this article. Experimental research are planned with the use of laboratory stand for the purpose of qualitative data obtaining on the interaction barrettes with an assessment of a settlement model adequacy and also at the research of the intense stress-strain state by numerical methods.

  15. State dissociation moderates response to dialectical behavior therapy for posttraumatic stress disorder in women with and without borderline personality disorder

    OpenAIRE

    Kleindienst, Nikolaus; Priebe, Kathlen; Görg, Nora; Dyer, Anne; Steil, Regina; Lyssenko, Lisa; Winter, Dorina; Schmahl, Christian; Bohus, Martin

    2016-01-01

    Background: Patients with posttraumatic stress disorder (PTSD) are prone to dissociation, which in theory should interfere with successful treatment. However, most empirical studies do not substantiate this assumption.Objective: The primary objective was to test whether state dissociation predicts the success of an adaptation of dialectical behavior therapy designed for the treatment of patients with PTSD after childhood sexual abuse (CSA) (DBT-PTSD). We further explored whether the operation...

  16. Bereavement, Level Stress and Coping Mechanism Among Teacher Education Students of Samar State University: College Bereavement Study

    OpenAIRE

    Domingo, Perlito Sabulaan; G. Labine, Archie; V. Capoqauin, Trixie Joyce

    2016-01-01

    Bereavement is a severe stressor that should be addressed properly. The study of Teacher education is very tight as it prepares soon to educator that will light the future of other young children. This study sought to determine the Level of Stress and Coping Mechanism on Bereavement among Teacher Education Students of Samar State University. It tested some assumption using the descriptive survey method on 76 identified students who experienced bereavement. It shows that respondent manifested ...

  17. Experimental and Computational Method for Determining Parameters of Stress-Strain State from the Data Obtainable by Interference Optical Techniques

    Directory of Open Access Journals (Sweden)

    Razumovsky I.

    2010-06-01

    Full Text Available Experimental and computational method for determining parameters of stress-strain state is proposed which is based on estimation of compliance between the data sets obtained experimentally and the results of numerical calculations of the boundary problems in formulation of which all distinctive features of area geometry, character of the loads being considered and deformation characteristics of materials are taken into account. The procedure proposed was checked at a number of practically important problems.

  18. Discrete fracture in quasi-brittle materials under compressive and tensile stress states

    CSIR Research Space (South Africa)

    Klerck, PA

    2004-01-01

    Full Text Available A method for modelling discrete fracture in geomaterials under tensile and compressive stress fields has been developed based on a Mohr-Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension...

  19. Perceived Support as a Predictor of Acculturative Stress Among International Students in the United States

    National Research Council Canada - National Science Library

    Jieru Bai

    2016-01-01

    .... A total of 186 students participated in the survey. Results showed that 22.4% of the students in this study exceeded the normal stress level and might need counseling or psychological intervention...

  20. SIMULATION OF THE stress-strain state of excavation BOUNDARIES in fractured massifs

    Directory of Open Access Journals (Sweden)

    Nizomov Dzhahongir Nizomovich

    2012-07-01

    Any limiting process, namely, if or and any results are in line with the isotropic medium. The proposed algorithm and calculation pattern may be used to research the concentrated stresses alongside the boundaries of hydrotechnical engineering facilities.

  1. Effect of stressful conditions on the functional state of blood eritroid cells

    Directory of Open Access Journals (Sweden)

    O. A. Nykyforova

    2011-10-01

    Full Text Available The influence of alimentary stress-factors – NaCl and cholesterol – on the osmotic resistance of rats’ erythrocytes has been studied. The results demonstrate more significant deviations in erythrocytes’ osmotic resistance of animals under the stress load of NaCl in comparison with the alimentary cholesterol load. NaCl significantly worsened the erythrocytes’ stability. Under such conditions the metabolic consequences arised for both the organism and cardiovascular system.

  2. Effect of material damage on the stress-strain state near a crack tip in creep

    Science.gov (United States)

    Astaf'ev, V. I.; Grigorova, T. V.; Pastukhov, V. A.

    1992-02-01

    The asymptotic stress and damage fields near the tip of a growing crack are determined for a creep-damaged material described by Rabotnov-Hayhurst-Leckie constitutive equations. It is found that the singular stress field, characteristic of the crack theory, is absent near the crack tip, which is consistent with the results of finite element solutions for tearing cracks. A crack growth law is obtained which provides a qualitative description of the crack growth process in stainless steels under constant loading.

  3. Fatigue Equivalent Stress State Approach Validation in Non-conservative Criteria: a Comparative Study

    Directory of Open Access Journals (Sweden)

    Kévin Martial Tsapi Tchoupou

    Full Text Available Abstract This paper is concerned with the fatigue prediction models for estimating the multiaxial fatigue limit. An equivalent loading approach with zero out-of-phase angles intended for fatigue limit evaluation under multiaxial loading is used. Based on experimental data found in literatures, the equivalent stress is validated in Crossland and Sines criteria and predictions compared to the predictions of existing multiaxial fatigue; results over 87 experimental items show that the equivalent stress approach is very efficient.

  4. Hypohydration and Acute Thermal Stress Affect Mood State but not Cognition or Dynamic Postural

    Science.gov (United States)

    2012-10-12

    physiological stresses such as sleep deprivation and military training (Lieberman et al. 2009). The POMS is a standardized inventory of self-reported...critical to successful and safe completion of various tasks, these findings have potential application to workers, military personnel, or athletes who...Coll Nutr 26:555S–561S Lieberman HR, Tharion WJ, Shukitt-Hale B et al (2002) Effects of caffeine, sleep loss, and stress on cognitive performance and

  5. Correlation of anxiety state with blood glucose control, microinflammation and oxidative stress in patients with type 2 diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Huai-Fen Ma; Juan Du; Huan-Le Fang; Xiao-Ming Li

    2017-01-01

    Objective:To study the correlation of anxiety state with blood glucose control, microinflammation and oxidative stress in patients with type 2 diabetes mellitus.Methods:A total of 138 patients with type 2 diabetes mellitus were divided into the non-anxiety group (n=43) (SAS score < 50 points), mild-to-moderate anxiety group (n=71) (SAS score 50-69 points) and severe anxiety group (n=24) (SAS score 70 points) according to the self-rating anxiety scale (SAS) score. The differences in levels of glucose metabolism indexes, microinflammation indexes and oxidative stress indexes were compared among the three groups.Results: Peripheral blood FPG, P2hPG, HOMA-IR, CRP, ASAA, IL-6, MDA and ROS levels of mild-to-moderate anxiety group and severe anxiety group were higher than those of non-anxiety group while CAT and GSH-Px contents were lower than those of non-anxiety group; peripheral blood FPG, P2hPG, HOMA-IR, CRP, ASAA, IL-6, MDA and ROS levels of severe anxiety group were higher than those of mid-to-moderate anxiety group while CAT and GSH-Px contents were lower than those of mid-to-moderate anxiety group.Conclusion:The increase of anxiety in patients with type 2 diabetes mellitus is a direct factor leading to the abnormal glucose metabolism as well as the aggravation of microinflammatory state and oxidative stress state.

  6. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Directory of Open Access Journals (Sweden)

    Levan Japaridze

    2015-10-01

    Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  7. State of stress, faulting, and eruption characteristics of large volcanoes on Mars

    Science.gov (United States)

    Mcgovern, Patrick J.; Solomon, Sean C.

    1993-01-01

    The formation of a large volcano loads the underlying lithospheric plate and can lead to lithospheric flexure and faulting. In turn, lithospheric deformation affects the stress field beneath and within the volcanic edifice and can influence magma transport. Modeling the interaction of these processes is crucial to an understanding of the history of eruption characteristics and tectonic deformation of large volcanoes. We develop models of time-dependent stress and deformation for the Tharsis volcanoes on Mars. By means of a finite element code, we calculate stresses and displacements due to a volcano-shaped load emplaced on an elastic plate overlying a viscoelastic mantle. Models variously incorporate growth of the volcanic load with time and a detachment between volcano and lithosphere. The models illustrate the manner in which time-dependent stresses induced by lithospheric plate flexure beneath the volcanic load may affect eruption histories, and the derived stress fields can be related to tectonic features on and surrounding Martian volcanoes. As a result of flexure there are three regions where stresses become sufficiently large to cause failure by faulting, according to the Mohr-Coulomb criterion: at the surface of the plate just outward of the volcano, near the base of the elastic lithosphere beneath the center of the volcano, and on the upper flanks of the volcano early in its growth history.

  8. The relationship between skin aging and steady state ultraweak photon emission as an indicator of skin oxidative stress in vivo.

    Science.gov (United States)

    Gabe, Y; Osanai, O; Takema, Y

    2014-08-01

    Ultraweak photon emission (UPE) is one potential method to evaluate the oxidative status of the skin in vivo. However, little is known about how the daily oxidative stress of the skin is related to skin aging-related alterations in vivo. We characterized the steady state UPE and performed a skin survey. We evaluated the skin oxidative status by UPE, skin elasticity, epidermal thickness and skin color on the inner upper arm, the outer forearm, and the buttock of 70 Japanese volunteers. The steady state UPE at the three skin sites increased with age. Correlation analysis revealed that the steady state UPE only from the buttock was related to skin elasticity, which showed age-dependent changes. Moreover, analysis by age group indicated that b* values of the inner upper arm of subjects in their 20s were inversely correlated with UPE as occurred in buttock skin. In contrast, photoaged skin did not show a clear relationship with steady state UPE because the accumulation of sun-exposure might influence the sensitivity to oxidative stress. These results suggest that steady state UPE reflects not only intrinsic skin aging and cutaneous color but also the current oxidative status independent of skin aging. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Determinants of stress fracture risk in United States Military Academy cadets.

    Science.gov (United States)

    Cosman, Felicia; Ruffing, Jamie; Zion, Marsha; Uhorchak, John; Ralston, Stuart; Tendy, Susan; McGuigan, Fiona E A; Lindsay, Robert; Nieves, Jeri

    2013-08-01

    Prior studies have identified some risk factors for stress fracture in athletes and military recruits. To determine whether historical factors, physical measures, biochemical variables of skeletal metabolism, genetic factors, bone density (BMD) and bone size could predict risk of stress fracture over 4 years in physically fit cadets at the US Military Academy (USMA). Baseline surveys, assessments of height, weight, scores on the Army Physical Fitness Test, and peripheral BMD were obtained in all cadets (755 men, 136 women), and central BMD in a subset. Blood samples were analyzed for variables of calcium homeostasis, bone turnover, and selected hormones and genetic factors. Stress fractures were adjudicated by review of orthopedic notes and imaging reports. 5.7% of male and 19.1% of female cadets had at least 1 stress fracture (58% metatarsal and 29% tibial), most within 3 months of entry to USMA. In males, risk of stress fracture was higher in those who exercised stress fracture risk was seen in those with shorter time since menarche (RR 1.44 per year; CI 1.19, 1.73) and smaller femoral neck diameter (RR 1.16; CI 1.01, 1.33.). Although prior physical training in men, length of prior estrogen exposure in women and leg bone dimensions in both genders played a role, the maximum variance explained by all of these factors was below 10%. We conclude these factors play a minor role in the development of stress fractures in physically fit USMA cadets. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. SUB-LEU-METAL-THERM-001 SUBCRITICAL MEASUREMENTS OF LOW ENRICHED TUBULAR URANIUM METAL FUEL ELEMENTS BEFORE & AFTER IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    SCHWINKENDORF, K.N.

    2006-05-12

    With the shutdown of the Hanford PUREX (Plutonium-Uranium Extraction Plant) reprocessing plant in the 1970s, adequate storage capacity for spent Hanford N Reactor fuel elements in the K and N Reactor pools became a concern. To maximize space utilization in the pools, accounting for fuel burnup was considered. Calculations indicated that at typical fuel exposures for N Reactor, the spent-fuel critical mass would be twice the critical mass for green fuel. A decision was reached to test the calculational result with a definitive experiment. If the results proved positive, storage capacity could be increased and N Reactor operation could be prolonged. An experiment to be conducted in the N Reactor spent-fuel storage pool was designed and assembled and the services of the Battelle Northwest Laboratories (BNWL) (now Pacific Northwest National Laboratory [PNNL]) critical mass laboratory were procured for the measurements. The experiments were performed in April 1975 in the Hanford N Reactor fuel storage pool. The fuel elements were MKIA fuel assemblies, comprising two concentric tubes of low-enriched metallic uranium. Two separate sets of measurements were performed: one with ''green'' (fresh) fuel and one with spent fuel. Both the green and spent fuel, were measured in the same geometry. The spent-fuel MKIA assemblies had an average burnup of 2865 MWd (megawatt days)/t. A constraint was imposed restricting the measurements to a subcritical limit of k{sub eff} = 0.97. Subcritical count rate data was obtained with pulsed-neutron and approach-to-critical measurements. Ten (10) configurations with green fuel and nine (9) configurations with spent fuel are described and evaluated. Of these, 3 green fuel and 4 spent fuel loading configurations were considered to serve as benchmark models. However, shortcomings in experimental data failed to meet the high standards for a benchmark problem. Nevertheless, the data provided by these subcritical measurements can

  11. Present-day stress state in the Outokumpu deep drill hole, Finland

    Science.gov (United States)

    Pierdominici, Simona; Ask, Maria; Kukkonen, Ilmo; Kueck, Jochem

    2017-04-01

    This study aims to investigate the present-day stress field in the Outokumpu area, eastern Finland, using interpretation of borehole failure on acoustic image logs in a 2516 m deep hole. Two main objectives of this study are: i. to constrain the orientation of maximum horizontal stress by mapping the occurrence of stress-induced deformation features using two sets of borehole televiewer data, which were collected in 2006 and 2011; and ii. to investigate whether any time dependent deformation of the borehole wall has occurred (creep). The Outokumpu deep hole was drilled during 2004-2005 to study deep structures and seismic reflectors within the Outokumpu formation and conducted within the International Continental Scientific Drilling Program (ICDP). The hole was continuously core-drilled into Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. In 2006 and 2011 two downhole logging campaigns were performed by the Operational Support Group of ICDP to acquire a set of geophysical data. Here we focus on a specific downhole logging measurement, the acoustic borehole televiewer (BHTV), to determine the present-day stress field in the Outokumpu area. We constrain the orientation and magnitude of in situ stress tensor based on borehole wall failures detected along a 2516 m deep hole. Horizontal stress orientation was determined by interpreting borehole breakouts (BBs) and drilling-induced tensile fractures (DIFs) from BHTV logs. BBs are stress-induced enlargements of the borehole cross section and occur in two opposite zones at angles around the borehole where the wellbore stress concentration (hoop stress) exceeds the value required to cause compressive failure of intact rock. DIFs are caused by tensile failure of the borehole wall and form at two opposite spots on the borehole where the stress concentration is lower than the tensile strength of the rock. This occurs at angles 90° apart from the center of the

  12. Stress state reconstruction and tectonic evolution of the northern slope of the Baikit anteclise, Siberian Craton, based on 3D seismic data

    Science.gov (United States)

    Moskalenko, A. N.; Khudoley, A. K.; Khusnitdinov, R. R.

    2017-05-01

    In this work, we consider application of an original method for determining the indicators of the tectonic stress fields in the northern Baikit anteclise based on 3D seismic data for further reconstruction of the stress state parameters when analyzing structural maps of seismic horizons and corresponded faults. The stress state parameters are determined by the orientations of the main stress axes and shape of the stress ellipsoid. To calculate the stress state parameters from data on the spatial orientations of faults and slip vectors, we used the algorithms from quasiprimary stress computation methods and cataclastic analysis, implemented in the software products FaultKinWin and StressGeol, respectively. The results of this work show that kinematic characteristics of faults regularly change toward the top of succession and that the stress state parameters are characterized by different values of the Lode-Nadai coefficient. Faults are presented as strike-slip faults with normal or reverse component of displacement. Three stages of formation of the faults are revealed: (1) partial inversion of ancient normal faults, (2) the most intense stage with the predominance of thrust and strike-slip faults at north-northeast orientation of an axis of the main compression, and (3) strike-slip faults at the west-northwest orientation of an axis of the main compression. The second and third stages are pre-Vendian in age and correlate to tectonic events that took place during the evolution of the active southwestern margin of the Siberian Craton.

  13. SIMPLE METHOD FOR ESTIMATING POLYCHLORINATED BIPHENYL CONCENTRATIONS ON SOILS AND SEDIMENTS USING SUBCRITICAL WATER EXTRACTION COUPLED WITH SOLID-PHASE MICROEXTRACTION. (R825368)

    Science.gov (United States)

    A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a seale...

  14. Short communication: antiviral activity of subcritical water extract of Brassica juncea against influenza virus A/H1N1 in nonfat milk

    National Research Council Canada - National Science Library

    Lee, N-K; Lee, J-H; Lim, S-M; Lee, K A; Kim, Y B; Chang, P-S; Paik, H-D

    2014-01-01

    Subcritical water extract (SWE) of Brassica juncea was studied for antiviral effects against influenza virus A/H1N1 and for the possibility of application as a nonfat milk supplement for use as an "antiviral food...

  15. Stress-corrosion fatigue-crack growth in a Zr-based bulk amorphousmetal

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, V.; Ritchie, R.O.

    2005-09-21

    Electrochemical and mechanical experiments were conducted to analyze the environmentally-influenced cracking behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5. This study was motivated by a scientific interest in mechanisms of fatigue-crack propagation in an amorphous metal, and by a practical interest in the use of this amorphous metal in applications that take advantage of its unique properties, including high specific strength, large elastic strains and low damping. The objective of the work was to determine the rate and mechanisms of subcritical crack growth in this metallic glass in an aggressive environment. Specifically, fatigue-crack propagation behavior was investigated at a range of stress intensities in air and aqueous salt solutions by examining the effects of loading cycle, stress-intensity range, solution concentration, anion identity, solution de-aeration, and bulk electrochemical potential. Results indicate that crack growth in aqueous solution in this alloy is driven by a stress-assisted anodic reaction at the crack tip. Rate-determining steps for such behavior are reasoned to be electrochemical, stress-dependent reaction at near-threshold levels, and mass transport at higher (steady-state) growth rates.

  16. The Influence of Pulsed Electroplating Frequency and Duty Cycle on Copper Film Microstructure and Stress State.

    Science.gov (United States)

    Marro, James B; Darroudi, Taghi; Okoro, Chukwudi A; Obeng, Yaw S; Richardson, Kathleen C

    2017-01-01

    In this work we studied the impact of pulse electroplating parameters on the cross-sectional and surface microstructures of blanket copper films using electron backscattering diffraction and x-ray diffraction. The films evaluated were highly (111) textured in the direction perpendicular to the film surface. The degree of preferential orientation was found to decrease with longer pulse on-times, due to strain energy driven growth of other grain orientations. Residual biaxial stresses were also measured in the films and higher pulse frequencies during deposition led to smaller biaxial stresses in the films. Film stress was also found to correlate with the amount of twinning in the copper film cross-sections. This has been attributed to the twins' thermal stability and mechanical properties.

  17. Hydrostatic stress dependence of the exciton phonon coupled states in cylindrical quantum dots

    Science.gov (United States)

    El Moussaouy, A.; Bria, D.; Nougaoui, A.

    2005-12-01

    We investigate theoretically the effects of compressive stress on the binding energy of an exciton in a cylindrical quantum dot (QD) using a variational procedure within the effective mass approximation. The stress was applied in the z direction and the interaction between the charge carriers (electron and hole) and confined longitudinal optical (LO) phonon modes was taken into account. Specific applications of these results are given for GaAs QDs embedded in a Ga1-xAlxAs semiconductor. The result shows that the binding energy and the polaronic correction increases linearly with increasing stress. Moreover, we obtain the binding energy and the polaronic contribution in the limit in which the QD turns into a quantum well.

  18. Mathematical Modeling in Systems for Operational Evaluation of the Stress-Strain State of the Arch-Gravity Dam at the Sayano-Shushenskaya Hydroelectric Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Bellendir, E. N.; Gordon, L. A., E-mail: lev-gordon@mail.ru; Khrapkov, A. A.; Skvortsova, A. E., E-mail: SkvortsovaAE@vniig.ru [B. E. Vedeneev All-Russia Research Institute of Hydraulic Engineering (VNIIG) (Russian Federation)

    2017-01-15

    Current studies of the stress-strain state of the dam at the Sayano-Shushenskaya Hydroelectric Power Plant at VNIIG based on mathematical modeling including full scale and experimental data are described. Applications and programs intended for automatic operational evaluation of the stress-strain state of the dam for optimizing control of the upper race level in the course of the annual filling-drawdown cycle and during seismic events are examined. Improvements in systems for monitoring the stress-strain state of concrete dams are proposed.

  19. Stress, emotion regulation and cognitive performance: the predictive contributions of trait and state relative frontal EEG alpha asymmetry.

    Science.gov (United States)

    Goodman, Ronald N; Rietschel, Jeremy C; Lo, Li-Chuan; Costanzo, Michelle E; Hatfield, Bradley D

    2013-02-01

    The relationship between trait and state measures of frontal lobe EEG alpha-band asymmetry in regard to indexing the approach-withdrawal dimension of emotion is unclear. The comparative predictive power of these constructs to explain emotion regulation and cognitive performance was examined under varying degrees of emotional challenge. The Capability Model posits the neural underpinnings of the relative difference in electrical activity between the left and right frontal lobes as a situational mechanism possibly indexing prefrontal-amygdalar interactions and psychological state. EEG, skin conductance, heart rate and acoustic startle amplitude were collected during a working memory task under three increasing levels of stress (final level was threat of shock). During threat of shock participants with higher state asymmetry exhibited greater emotion regulation compared to those with lower scores as indexed by significant attenuation of eyeblink startle magnitudes. The trait measure of frontal EEG asymmetry failed to account for significant variability in emotion regulation. Results implicate state-specific relative left frontal lobe activity as having an adaptive role in the regulation of emotion during cognitive challenge, but only under conditions of sufficient stress. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Moment tensors, state of stress and their relation to faulting processes in Gujarat, western India

    Science.gov (United States)

    Aggarwal, Sandeep Kumar; Khan, Prosanta Kumar; Mohanty, Sarada Prasad; Roumelioti, Zafeiria

    2016-10-01

    Time domain moment tensor analysis of 145 earthquakes (Mw 3.2 to 5.1), occurring during the period 2006-2014 in Gujarat region, has been performed. The events are mainly confined in the Kachchh area demarcated by the Island belt and Kachchh Mainland faults to its north and south, and two transverse faults to its east and west. Libraries of Green's functions were established using the 1D velocity model of Kachchh, Saurashtra and Mainland Gujarat. Green's functions and broadband displacement waveforms filtered at low frequency (0.5-0.8 Hz) were inverted to determine the moment tensor solutions. The estimated solutions were rigorously tested through number of iterations at different source depths for finding reliable source locations. The identified heterogeneous nature of the stress fields in the Kachchh area allowed us to divide this into four Zones 1-4. The stress inversion results indicate that the Zone 1 is dominated with radial compression, Zone 2 with strike-slip compression, and Zones 3 and 4 with strike-slip extensions. The analysis further shows that the epicentral region of 2001 MW 7.7 Bhuj mainshock, located at the junction of Zones 2, 3 and 4, was associated with predominant compressional stress and strike-slip motion along ∼ NNE-SSW striking fault on the western margin of the Wagad uplift. Other tectonically active parts of Gujarat (e.g. Jamnagar, Talala and Mainland) show earthquake activities are dominantly associated with strike-slip extension/compression faulting. Stress inversion analysis shows that the maximum compressive stress axes (σ1) are vertical for both the Jamnagar and Talala regions and horizontal for the Mainland Gujarat. These stress regimes are distinctly different from those of the Kachchh region.

  1. Distinct age and differentiation-state dependent metabolic profiles of oligodendrocytes under optimal and stress conditions.

    Directory of Open Access Journals (Sweden)

    Vijayaraghava T S Rao

    Full Text Available Within the microenvironment of multiple sclerosis lesions, oligodendrocytes are subject to metabolic stress reflecting effects of focal ischemia and inflammation. Previous studies have shown that under optimal conditions in vitro, the respiratory activity of human adult brain-derived oligodendrocytes is lower and more predominantly glycolytic compared to oligodendrocytes differentiated in vitro from post natal rat brain oligodendrocyte progenitor cells. In response to sub-lethal metabolic stress, adult human oligodendrocytes reduce overall energy production rate impacting the capacity to maintain myelination. Here, we directly compare the metabolic profiles of oligodendrocytes derived from adult rat brain with oligodendrocytes newly differentiated in vitro from oligodendrocyte progenitor cells obtained from the post natal rat brain, under both optimal culture and metabolic stress (low/no glucose conditions. Oxygen consumption and extracellular acidification rates were measured using a Seahorse extracellular flux analyzer. Our findings indicate that under optimal conditions, adult rat oligodendrocytes preferentially use glycolysis whereas newly differentiated post natal rat oligodendrocytes, and the oligodendrocyte progenitor cells from which they are derived, mainly utilize oxidative phosphorylation to produce ATP. Metabolic stress increases the rate of ATP production via oxidative phosphorylation and significantly reduces glycolysis in adult oligodendrocytes. The rate of ATP production was relatively unchanged in newly differentiated post natal oligodendrocytes under these stress conditions, while it was significantly reduced in oligodendrocyte progenitor cells. Our study indicates that both age and maturation influence the metabolic profile under optimal and stressed conditions, emphasizing the need to consider these variables for in vitro studies that aim to model adult human disease.

  2. Sensitivity study of forecasted aftershock seismicity based on Coulomb stress calculation and rate- and state-dependent frictional response

    Science.gov (United States)

    Cocco, M.; Hainzl, S.; Catalli, F.; Enescu, B.; Lombardi, A. M.; Woessner, J.

    2010-05-01

    We use the Dieterich (1994) physics-based approach to simulate the spatiotemporal evolution of seismicity caused by stress changes applied to an infinite population of nucleating patches modeled through a rate- and state-dependent friction law. According to this model, seismicity rate changes depend on the amplitude of stress perturbation, the physical constitutive properties of faults (represented by the parameter Aσ), the stressing rate, and the background seismicity rate of the study area. In order to apply this model in a predictive manner, we need to understand the impact of physical model parameters and the correlations between them. First, we discuss different definitions of the reference seismicity rate and show their impact on the computed rate of earthquake production for the 1992 Landers earthquake sequence as a case study. Furthermore, we demonstrate that all model parameters are strongly correlated for physical and statistical reasons. We discuss this correlation, emphasizing that the estimations of the background seismicity rate, stressing rate, and Aσ are strongly correlated to reproduce the observed aftershock productivity. Our analytically derived relation demonstrates the impact of these model parameters on the Omori-like aftershock decay: the c value and the productivity of the Omori law, implying a p value smaller than or equal to 1. Finally, we discuss an optimal strategy to constrain model parameters for near-real-time forecasts.

  3. Selected Abiotic and Biotic Environmental Stress Factors Affecting Two Economically Important Sugarcane Stalk Boring Pests in the United States

    Directory of Open Access Journals (Sweden)

    Allan T. Showler

    2016-02-01

    Full Text Available Sugarcane, Saccharum spp., in the United States is attacked by a number of different arthropod pests. The most serious among those pests are two stalk boring moths in the Family Crambidae: the sugarcane borer, Diatraea saccharalis (F., and the Mexican rice borer, Eoreuma loftini (Dyar. The two species are affected by abiotic and biotic environmental stress factors. Water deficit and excessive soil nitrogen alter physical and physiochemical aspects of the sugarcane plant that make the crop increasingly vulnerable to E. loftini. Weed growth can be competitive with sugarcane but it also supports enhanced abundances and diversity of natural enemies that can suppress infestations of D. saccharalis. In an instance where the stalk borer is considered a stress factor, proximity of vulnerable crops to sugarcane can influence levels of E. loftini infestation of sugarcane. The adverse effects of each stress factor, in terms of stalk borer attack, can be reduced by adopting appropriate cultural practices, such as adequate irrigation, judicious use of nitrogen fertilizer, using noncompetitive weed growth, and not planting vulnerable crops near sugarcane fields. Understanding the relationships between stress factors and crop pests can provide valuable insights for plant breeders and tools for incorporation into integrated pest management strategies.

  4. What Trickled Down? Federalism, State Government Fiscal Stress, and Local Government Outcomes

    OpenAIRE

    Swenson, David A.; Eathington, Liesl

    2006-01-01

    Much has been written about a shift in federal to state relationships during the 1990s. Couched in terms of a renewed fiscal federalism, devolution, or even the heady rhetoric of “reinventing” government both resources and public service authority flowed to the state governments. Somewhat less was said at the time regarding state governments’ relationships with local governments or the extent of federal re-distributions of resources beyond state governments to local governments. This paper is...

  5. Psychosocial stress but not exercise increases cortisol and reduces state anxiety levels in school classes - results from a stressor applicable in large group settings.

    Science.gov (United States)

    Wegner, Mirko; Müller-Alcazar, Anett; Jäger, Anika; Machado, Sergio; Arias-Carrión, Oscar; Budde, Henning

    2014-01-01

    Both, psychosocial stress and exercise in the past have been used as stressors to elevate saliva cortisol and change state anxiety levels. In the present study, high-school students at the age of 14 were randomly assigned to three experimental groups: (1) an exercise group (n = 18), that was running 15 minutes at a medium intensity level of 65-75% HRmax, (2) a psychosocial stress group (n = 19), and (3) a control group (n = 18). The psychosocial stress was induced to the students by completing a standardized intelligence test under the assumption that their IQ scores would be made public in class. Results display that only psychosocial stress but not exercise was able to significantly increase cortisol levels but decreased cognitive state anxiety in adolescents. The psychosocial stress protocol applied here is proposed for use in future stress studies with children or adolescents in group settings, e.g., in school.

  6. Symptoms of psychological distress and post-traumatic stress disorder in United States Air Force "drone" operators.

    Science.gov (United States)

    Chappelle, Wayne L; McDonald, Kent D; Prince, Lillian; Goodman, Tanya; Ray-Sannerud, Bobbie N; Thompson, William

    2014-08-01

    The goal of this study is to repeat a survey administered in 2010 to assess for changes in mental health among United States Air Force aircrew operating Predator/Reaper remotely piloted aircraft, also commonly referred to as "drones." Participants were assessed for self-reported sources of occupational stress, levels of clinical distress using the Outcome Questionnaire-45.2, and symptoms of post-traumatic stress disorder (PTSD) using the PTSD Checklist-Military Version. A total of 1,094 aircrew responded to the web-based survey composed of the commercially available standardized instruments mentioned above. The survey also contained nonstandardized items asking participants to report the main sources of their occupational stress, as well as questions addressing demographics and work-related characteristics. The estimated response rate to the survey was 49%. Study results reveal the most problematic self-reported stressors are operational: low manning, extra duties/administrative tasks, rotating shift work, and long hours. The results also reveal 10.72% of operators self-reported experiencing high levels of distress and 1.57% reported high levels of PTSD symptomology. The results are lower than findings from the 2010 survey and from soldiers returning from Iraq and Afghanistan. Implications of the study and recommendations for United States Air Force line leadership and mental health providers are discussed. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

  7. Oxidative Stress State Is Associated with Left Ventricular Mechanics Changes, Measured by Speckle Tracking in Essential Hypertensive Patients

    Directory of Open Access Journals (Sweden)

    Luis Antonio Moreno-Ruíz

    2015-01-01

    Full Text Available The oxidative stress state is characterized by an increase in oxygen reactive species that overwhelms the antioxidant defense; we do not know if these pathological changes are correlated with alterations in left ventricular mechanics. The aim was correlating the oxidative stress state with the left ventricular global longitudinal strain (GLS and the left ventricular end diastolic pressure (LVEDP. Twenty-five patients with essential hypertension and 25 controls paired by age and gender were studied. All of the participants were subjected to echocardiography and biochemical determination of oxidative stress markers. The hypertensive patients, compared with control subjects, had significantly (p<0.05 higher levels of oxidized proteins (5.03±1.05 versus 4.06±0.63 nmol/mg, lower levels of extracellular superoxide dismutase (EC-SOD activity (0.045±0.02 versus 0.082±0.02 U/mg, higher LVEDP (16.2±4.5 versus 11.3±1.6 mm Hg, and lower GLS (−12% versus −16%. Both groups had preserved ejection fraction and the results showed a positive correlation of oxidized proteins with GLS (r=0.386, p=0.006 and LVEDP (r=0.389, p=0.005; we also found a negative correlation of EC-SOD activity with GLS (r=-0.404, p=0.004 and LVEDP (r=-0.347, p=0.014.

  8. Postdisaster stress in the United States and Mexico: a cross-cultural test of the multicriterion conceptual model of posttraumatic stress disorder.

    Science.gov (United States)

    Norris, F H; Perilla, J L; Murphy, A D

    2001-11-01

    Data on symptoms of posttraumatic stress disorder (PTSD) were collected 6 months after Hurricanes Paulina (N = 200; Mexico) and Andrew (non-Hispanic n = 270; United States) using the Revised Civilian Mississippi Scale. A 4-factor measurement model that represented the accepted multicriterion conceptualization of PTSD fit the data of the U.S. and Mexican samples equally well. The 4 factors of Intrusion, Avoidance, Numbing, and Arousal correlated significantly and equivalently with severity of trauma in each sample. A single construct explained much of the covariance of the symptom factors in each sample. However, modeling PTSD as a unidimensional construct masked differences between samples in symptom severity. With severity of trauma controlled, the Mexican sample was higher in Intrusion and Avoidance, whereas the U.S. sample was higher in Arousal. The results suggest that PTSD is a meaningful construct to study in Latin American societies.

  9. Implementation and qualification of neutronic calculation methodology in subcritical reactors driven by external neutron sources and applications

    OpenAIRE

    Thiago Carluccio

    2011-01-01

    O trabalho teve como objetivo a investigação de Metodologias de Cálculo dos Reatores Subcríticos acionados por fonte externa de nêutrons, tais como, \\"Accelerator Driven Subcritical Reactor\\" (ADSR) e \\"Fusion Driven Subcritical Reator\\" (FDSR) , que são reatores nucleares subcríticos com uma fonte externa de nêutrons. Tais nêutrons são produzidos, no caso do ADSR, através da interação de partículas aceleradas (prótons, deutério) com um alvo (Pb, Bi, etc) ou através das reações de fusão, no c...

  10. Ginger and turmeric starches hydrolysis using subcritical water + CO2: the effect of the SFE pre-treatment

    Directory of Open Access Journals (Sweden)

    S. R. M. Moreschi

    2006-06-01

    Full Text Available In this work, the hydrolysis of fresh and dried turmeric (Curcuma longa L. and ginger (Zingiber officinale R. in the presence of subcritical water + CO2 was studied. The hydrolysis of ginger and turmeric bagasses from supercritical fluid extraction was also studied. The reactions were done using subcritical water and CO2 at 150 bar, 200 °C and reaction time of 11 minutes; the degree of reaction was monitored through the amount of starch hydrolyzed. Process yields were calculated using the amount of reducing and total sugars formed. The effects of supercritical fluid extraction in the starchy structures were observed by scanning electron microscopy. Higher degree of hydrolysis (97- 98 % were obtained for fresh materials and the highest total sugar yield (74% was established for ginger bagasse. The supercritical fluid extraction did not significantly modify the degree of hydrolysis in the tested conditions.

  11. Application of the Modified Source Multiplication (MSM) Technique to Subcritical Reactivity Worth Measurements in Thermal and Fast Reactor Systems

    Science.gov (United States)

    Blaise, Patrick; Mellier, Frédéric; Fougeras, Philippe

    2011-06-01

    The Amplified Source Multiplication (ASM) method and its improved Modified Source Multiplication (MSM) method have been widely used in the CEA's EOLE and MASURCA critical facilities over the past decades for the determination of reactivity worths by using fission chambers in subcritical configurations. The ASM methodology uses relatively simple relationships between count rates of efficient miniature fission chambers located in slightly subcritical reference and perturbed configurations. While this method works quite well for small reactivity variations, the raw results need to be corrected to take into account the flux perturbation at the fission chamber location. This is performed by applying to the measurement a correction factor called MSM. This paper describes in detail both methodologies, with their associated uncertainties. Applications on absorber cluster worth in the MISTRAL-4 full MOX mock-up core and the last core loaded in MASURCA show the importance of the MSM correction on raw ASM data.

  12. Water stress projections for the northeastern and Midwestern United States in 2060: anthropogenic and ecological consequences

    Science.gov (United States)

    Brian G. Tavernia; Mark D. Nelson; Peter Caldwell; Ge Sun

    2013-01-01

    Future climate and land-use changes and growing human populations may reduce the abundance of water resources relative to anthropogenic and ecological needs in the Northeast and Midwest (U.S.). We used output from WaSSI, a water accounting model, to assess potential changes between 2010 and 2060 in (1) anthropogenic water stress for watersheds throughout the Northeast...

  13. University Professors' Stress and Perceived State of Health in Relation to Teaching Schedules

    Science.gov (United States)

    Cladellas, Ramon; Castello, Antoni

    2011-01-01

    Introduction: The aim of this research is to analyze the influence of time management, particularly in connection with university teachers' assigned class hours, on psychosocial factors relating to perceived health and stress symptoms. Special attention is given to the effect of very early and very late class hours. Method: The sample comprised…

  14. Prevalence and Predictors of Posttraumatic Stress Disorder among Victims of Violence Applying for State Compensation

    Science.gov (United States)

    Kunst, Maarten; Winkel, Frans Willem; Bogaerts, Stefan

    2010-01-01

    Many studies have focused on the predictive value of victims' emotions experienced shortly after violence exposure to identify those vulnerable for development of posttraumatic stress disorder (PTSD). However, many victims remain unidentified during the initial recovery phase, yet may still be highly in need of psychological help after substantial…

  15. Facebook use and adolescents' emotional states of depression, anxiety, and stress

    National Research Council Canada - National Science Library

    Leodoro J Labrague

    2014-01-01

    ... program from a government university in Samar, Philippines. Facebook Intensity Scale (FIS) and the Depression Anxiety and Stress Scale (DASS) were the primary instruments used in this study. Results: Findings indicated correlation coefficients of 0.11 (p=0.336), 0.07 (p=0.536), and 0.10 (p=0.377) between Facebook Intensity Scale (FIS) and Depression, Anxie...

  16. Stress and food deprivation: linking physiological state to migration success in a teleost fish

    DEFF Research Database (Denmark)

    Midwood, J.D.; Larsen, Martin Hage; Aarestrup, Kim

    2016-01-01

    of the glucocorticoid stress response in determining life-history strategy and survival of a migratory species. Using an experimental approach, the relative influences of short-term FD and experimental cortisol elevation (i.e., intra-coelomic injection of cortisol suspended in cocoa butter) on migratory status...

  17. Characterization of the Residual Stress State in Commercially Fully Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2010-01-01

    Toughened glass is often used in load carrying elements due to the relatively high tensile strength compared with float glass. The apparent tensile strength of toughened glass is a combination of the pure material strength and the residual stresses imposed by the toughening process. This paper is...

  18. The Rim101 pathway contributes to ER stress adaptation through sensing the state of plasma membrane.

    Science.gov (United States)

    Obara, Keisuke; Kihara, Akio

    2017-01-01

    Yeast cells sense alterations in the plasma membrane (PM) lipid asymmetry and external alkalization by the sensor protein Rim21, which functions in the Rim101 pathway. Rim101 signaling is initiated at the PM by the recruitment of the Rim101 signaling complex. The PM physically associates with the cortical endoplasmic reticulum (ER) to form ER-PM contact sites, where several signaling events, lipid exchange, and ion transport take place. In the present study, we investigated the spatial relationship between ER-PM contact sites and the sites of Rim101 signaling. Rim101 signaling mostly proceeds outside ER-PM contact sites in the PM and did not require intact ER-PM contact for its activation. Rather, the Rim101 pathway was constitutively activated by ER-PM contact site disruption, which is known to cause ER stress. ER stress induced by tunicamycin treatment activated the Rim101 pathway. Furthermore, the sensitivity of cells to tunicamycin without ER-PM contact was considerably elevated by the deletion of RIM21. These results suggest that the Rim101 pathway is important for the adaptation to ER stress by compensating for alterations in PM lipid asymmetry induced by ER stress. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  19. Post-Traumatic Stress Disorder: A Reaction to State-Supported Child Abuse and Neglect.

    Science.gov (United States)

    Straker, G.; Moosa, F.

    1988-01-01

    Posttraumatic Stress Disorder developed in many youths who were exposed to multiple trauma in South Africa's black townships. A modified treatment program was developed for 60 youths, with the goals of alleviating symptoms, documenting events for court cases, and helping individuals reevaluate their position in the struggle against apartheid. (JDD)

  20. APPLICATION OF AN EQUIVALENT TRUSS MODEL FOR DETERMINING THE STRESS STATE IN MULTI-PHASE MATERIALS WITH CELLULAR AUTOMATA METHOD

    Directory of Open Access Journals (Sweden)

    Anna Staszczyk

    2017-06-01

    Full Text Available The Cellular Automata represent a universal method of modelling and simulation. They enable the performance of calculations for even the most complex processes and phenomena. They are also used successfully in mechanical and material engineering. In this paper, the concept of application of the Cellular Automata method for simulating the behaviour of material under stress is presented. The proposed numerical algorithm created performs a number of calculations of local stress states in the structure of precipitation hardened material. The principle of its operation is based on the application of the equivalent truss model, which is often used in the optimisation and design of structures. In this paper, this model was used to simulate a system embodying a section of the material containing various phases with different mechanical properties.

  1. Mathematic modeling of stress-deformed states of low jaw teeth while using combined removable splint-denture

    Directory of Open Access Journals (Sweden)

    Albert Ye.L.

    2013-06-01

    Full Text Available The article presents the results of mathematical modeling and analysis of the stress-strain states of the lower incisors in the 1-st, 2-nd and 3-d degrees of inflammatory degenerative process in the periodontium; and while using combined splint-denture with continuous vestibular-oral clasp and polyoxymethylene framework. It is proved that reduction in height of interdental septa observed in periodontitis increases tooth mobility by 2.75 times in the first degree of the pathological process; by 6.75 times - in the second degree; and by 9.0 times – in the third degree (p0.05. At the same time, the stress, transmitted on the alveolar bone tissue is near the values of intact periodontium (p>0.05, 1.6±0.50 Mpa on average.

  2. THE CALCULATION OF STRESS-STRAIN STATE OF THREE-LAYER BEAM TAKING INTO ACCOUNT EDGE EFFECTS

    Directory of Open Access Journals (Sweden)

    Kh. M. Muselemov

    2015-01-01

    Full Text Available The work is dedicated to the calculation of the stress-strain state (SSS of the three-layer beam (TLB subject to boundary effects.In this paper, a system of differential equations of equilibrium of the threelayer beam. To solve these equations, it is necessary to know the 12 boundary conditions, co-which depend on support conditions and loading of sandwich beams under study. This system of equations is solved by the application package of mathematical modeling "Maple 5.4." The solution of this system we obtain expressions for determining de-formations and stress all components (bearing layers and filler, a three-layer beam anywhere under specified conditions of fastening the ends of the beam and its loading. 

  3. Analysis of the Temporal Response of Coupled Asymmetrical Zero-Power Subcritical Bare Metal Reactor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Klain, Kimberly L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-21

    The behavior of symmetrical coupled-core systems has been extensively studied, yet there is a dearth of research on asymmetrical systems due to the increased complexity of the analysis of such systems. In this research, the multipoint kinetics method is applied to asymmetrical zeropower, subcritical, bare metal reactor systems. Existing research on asymmetrical reactor systems assumes symmetry in the neutronic coupling; however, it will be shown that this cannot always be assumed. Deep subcriticality adds another layer of complexity and requires modification of the multipoint kinetics equations to account for the effect of the external neutron source. A modified set of multipoint kinetics equations is derived with this in mind. Subsequently, the Rossi-alpha equations are derived for a two-region asymmetrical reactor system. The predictive capabilities of the radiation transport code MCNP6 for neutron noise experiments are shown in a comparison to the results of a series of Rossi-alpha measurements performed by J. Mihalczo utilizing a coupled set of symmetrical bare highly-enriched uranium (HEU) cylinders. The ptrac option within MCNP6 can generate time-tagged counts in a cell (list-mode data). The list-mode data can then be processed similarly to measured data to obtain values for system parameters such as the dual prompt neutron decay constants observable in a coupled system. The results from the ptrac simulations agree well with the historical measured values. A series of case studies are conducted to study the effects of geometrical asymmetry in the coupling between two bare metal HEU cylinders. While the coupling behavior of symmetrical systems has been reported on extensively, that of asymmetrical systems remains sparse. In particular, it appears that there has been no previous research in obtaining the coupling time constants for asymmetrically-coupled systems. The difficulty in observing such systems is due in part to the inability to determine the

  4. Recovery of solid fuel from municipal solid waste by hydrothermal treatment using subcritical water

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, In-Hee, E-mail: hwang@eng.hokudai.ac.jp [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan); Aoyama, Hiroya; Matsuto, Toshihiko; Nakagishi, Tatsuhiro; Matsuo, Takayuki [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Hydrothermal treatment using subcritical water was studied to recover solid fuel from MSW. Black-Right-Pointing-Pointer More than 75% of carbon in MSW was recovered as char. Black-Right-Pointing-Pointer Heating value of char was comparable to that of brown coal and lignite. Black-Right-Pointing-Pointer Polyvinyl chloride was decomposed at 295 Degree-Sign C and 8 MPa and was removed by washing. - Abstract: Hydrothermal treatments using subcritical water (HTSW) such as that at 234 Degree-Sign C and 3 MPa (LT condition) and 295 Degree-Sign C and 8 MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources. While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char. Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing. From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel.

  5. Accelerated Stress Corrosion Crack Initiation of Alloys 600 and 690 in Hydrogenated Supercritical Water

    Science.gov (United States)

    Moss, Tyler; Was, Gary S.

    2017-04-01

    The objective of this study is to determine whether stress corrosion crack initiation of Alloys 600 and 690 occurs by the same mechanism in subcritical and supercritical water. Tensile bars of Alloys 690 and 600 were strained in constant extension rate tensile experiments in hydrogenated subcritical and supercritical water from 593 K to 723 K (320 °C to 450 °C), and the crack initiation behavior was characterized by high-resolution electron microscopy. Intergranular cracking was observed across the entire temperature range, and the morphology, structure, composition, and temperature dependence of initiated cracks in Alloy 690 were consistent between hydrogenated subcritical and supercritical water. Crack initiation of Alloy 600 followed an Arrhenius relationship and did not exhibit a discontinuity or change in slope after crossing the critical temperature. The measured activation energy was 121 ± 13 kJ/mol. Stress corrosion crack initiation in Alloy 690 was fit with a single activation energy of 92 ± 12 kJ/mol across the entire temperature range. Cracks were observed to propagate along grain boundaries adjacent to chromium-depleted metal, with Cr2O3 observed ahead of crack tips. All measures of the SCC behavior indicate that the mechanism for stress corrosion crack initiation of Alloy 600 and Alloy 690 is consistent between hydrogenated subcritical and supercritical water.

  6. Extremal states of energy of a double-layered thick-walled tube - application to residually stressed arteries.

    Science.gov (United States)

    Waffenschmidt, Tobias; Menzel, Andreas

    2014-01-01

    Various biological tissues are designed to optimally support external loads for complex geometries and mechanobiological structures. This results in complex microstructures of such materials. The design of, for instance, (healthy) arteries, which are in the focus of this work, is characterised by a residually stressed fibre-reinforced multi-layered composite with highly non-linear elastic response. The complex interaction of material properties with the geometry and residual stress effects enables the optimal support under different blood pressures, respectively blood flow, within the vessel. The fibres reinforcing the arterial wall, as well as residual stresses present in the vessel, strongly influence its overall behaviour and performance. Turn-over and remodelling processes of the collagenous fibres occurring in the respective layers - either resulting from natural growth phenomena or from artificially induced changes in loading condition such as stent deployment - support the optimisation of the multi-layered composite structure of arteries for the particular loading conditions present in the artery. Within this contribution, the overall energetic properties of an artery are discussed by means of the inflation, bending and extension of a double-layered cylindrical tube. Different states of residual stresses and different fibre orientations are considered so that, for instance, representative fibre angles that result in extremal states of the total potential energy can be identified. In view of turn-over and remodelling processes, these orientations are considered to constitute preferred directions of fibre alignment. In summary, the main goal of this work is to calculate optimal material, structural and loading parameters by concepts of energy-minimisation. Several numerical studies show that the obtained values - such as the fibre orientations, the residual axial stretch and the opening angle - are in good agreement with respective physiological parameters

  7. Role of constitutive behavior and tumor-host mechanical interactions in the state of stress and growth of solid tumors.

    Directory of Open Access Journals (Sweden)

    Chrysovalantis Voutouri

    Full Text Available Mechanical forces play a crucial role in tumor patho-physiology. Compression of cancer cells inhibits their proliferation rate, induces apoptosis and enhances their invasive and metastatic potential. Additionally, compression of intratumor blood vessels reduces the supply of oxygen, nutrients and drugs, affecting tumor progression and treatment. Despite the great importance of the mechanical microenvironment to the pathology of cancer, there are limited studies for the constitutive modeling and the mechanical properties of tumors and on how these parameters affect tumor growth. Also, the contribution of the host tissue to the growth and state of stress of the tumor remains unclear. To this end, we performed unconfined compression experiments in two tumor types and found that the experimental stress-strain response is better fitted to an exponential constitutive equation compared to the widely used neo-Hookean and Blatz-Ko models. Subsequently, we incorporated the constitutive equations along with the corresponding values of the mechanical properties - calculated by the fit - to a biomechanical model of tumor growth. Interestingly, we found that the evolution of stress and the growth rate of the tumor are independent from the selection of the constitutive equation, but depend strongly on the mechanical interactions with the surrounding host tissue. Particularly, model predictions - in agreement with experimental studies - suggest that the stiffness of solid tumors should exceed a critical value compared with that of the surrounding tissue in order to be able to displace the tissue and grow in size. With the use of the model, we estimated this critical value to be on the order of 1.5. Our results suggest that the direct effect of solid stress on tumor growth involves not only the inhibitory effect of stress on cancer cell proliferation and the induction of apoptosis, but also the resistance of the surrounding tissue to tumor expansion.

  8. Multilayer Finite-Element Model Application to Define the Bearing Structure Element Stress State of Launch Complexes

    Directory of Open Access Journals (Sweden)

    V. A. Zverev

    2016-01-01

    Full Text Available The article objective is to justify the rationale for selecting the multilayer finite element model parameters of the bearing structure of a general-purpose launch complex unit.A typical design element of the launch complex unit, i.e. a mount of the hydraulic or pneumatic cylinder, block, etc. is under consideration. The mount represents a set of the cantilevered axis and external structural cage. The most loaded element of the cage is disk to which a moment is transferred from the cantilevered axis due to actuator effort acting on it.To calculate the stress-strain state of disk was used a finite element method. Five models of disk mount were created. The only difference in models was the number of layers of the finite elements through the thickness of disk. There were models, which had one, three, five, eight, and fourteen layers of finite elements through the thickness of disk. For each model, we calculated the equivalent stresses arising from the action of the test load. Disk models were formed and calculated using the MSC Nastran complex software.The article presents results in the table to show data of equivalent stresses in each of the multi-layered models and graphically to illustrate the changing equivalent stresses through the thickness of disk.Based on these results we have given advice on selecting the proper number of layers in the model allowing a desirable accuracy of results with the lowest run time. In addition, it is concluded that there is a need to use the multi-layer models in assessing the performance of structural elements in case the stress exceeds the allowable one in their surface layers.

  9. Extraction of Fenugreek (Trigonella foenum-graceum L.) Seed Oil Using Subcritical Butane: Characterization and Process Optimization.

    Science.gov (United States)

    Gu, Ling-Biao; Liu, Xiao-Ning; Liu, Hua-Min; Pang, Hui-Li; Qin, Guang-Yong

    2017-02-02

    In this study, the subcritical butane extraction process of fenugreek seed oil was optimized using response surface methodology with a Box-Behnken design. The optimum conditions for extracted oil from fenugreek seed was as follows: extraction temperature of 43.24 °C , extraction time of 32.80 min, and particle size of 0.26 mm. No significant differences were found between the experimental and predicted values. The physical and chemical properties of the oil showed that the oil could be used as edible oil. Fatty acid composition of oils obtained by subcritical butane under the optimum conditions and by accelerated solvent extraction showed negligible difference. The oils were rich in linoleic acid (42.71%-42.80%), linolenic acid (26.03%-26.15%), and oleic acid (14.24%-14.40%). The results revealed that the proposed method was feasible, and this essay shows the way to exploit fenugreek seeds by subcritical butane extraction under the scope of edible oils.

  10. Historical volcanism and the state of stress in the East African Rift System

    Directory of Open Access Journals (Sweden)

    Geoffrey Wadge

    2016-09-01

    Full Text Available Crustal extension at the East African Rift System (EARS should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800 and find that 7 match the (approximate geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement, transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes and evolved and mixed magmas capable of explosive behaviour. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g. Kone and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g. Erta Ale, suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behaviour. Eruptions within 7 km of the volcano are of relatively short duration (<100 days, but eruptions with more distal fissures tend to have greater obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002 due to major along

  11. Role of multiaxial stress state in the hydrogen-assisted rolling-contact fatigue in bearings for wind turbines

    Directory of Open Access Journals (Sweden)

    J. Toribio

    2015-07-01

    Full Text Available Offshore wind turbines often involve important engineering challenges such as the improvement of hydrogen embrittlement resistance of the turbine bearings. These elements frequently suffer the so-called phenomenon of hydrogen-assisted rolling-contact fatigue (HA-RCF as a consequence of the synergic action of the surrounding harsh environment (the lubricant supplying hydrogen to the material and the cyclic multiaxial stress state caused by in-service mechanical loading. Thus the complex phenomenon could be classified as hydrogen-assisted rolling-contact multiaxial fatigue (HA-RC-MF. This paper analyses, from the mechanical and the chemical points of view, the so-called ball-on-rod test, widely used to evaluate the hydrogen embrittlement susceptibility of turbine bearings. Both the stress-strain states and the steady-state hydrogen concentration distribution are studied, so that a better elucidation can be obtained of the potential fracture places where the hydrogen could be more harmful and, consequently, where the turbine bearings could fail during their life in service.

  12. The State of stress in the Sanford Underground Research Facility (SURF) in Lead South Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Moo Y. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-10-01

    As a part of the U.S. Department of Energy (DOE) SubTER (Subsurface Technology and Engineering Research, Development and Demonstration) initiative, University of Wisconsin- Madison, Sandia National Laboratories, and Lawrence Berkeley National Laboratory conducted the Permeability (k) and Induced Seismicity Management for Energy Technologies (kISMET) project. The objectives of the project are to define the in situ status of stress in the Sanford Underground Research Facility (SURF) in Lead, South Dakota and to establish the relations between in situ stress and induced fracture through hydraulically stimulating the fracture. (SURF) in Lead, South Dakota. In situ tests are conducted in a 7.6 cm diameter and 100 long vertical borehole located in the 4850 Level West Access Drift near Davies Campus of SURF (Figure 1). The borehole is located in the zone of Precambrian Metamorphic Schist.

  13. Stress-Strain State Of Elastic Plate With An Arbitrary Smooth Notch

    Directory of Open Access Journals (Sweden)

    Kuz Ihor

    2015-12-01

    Full Text Available The paper contains comparing calculations of the stress fields in an elastic plate with notch along the arc of a circle, ellipse or parabola obtained by analytic method based on complex Kolosov-Muskhelishvili potentials and by numerical variation-difference method. These fields differ by no more than 2%, which, in particular, indicates the reliability of such numerical implementation. This discrepancy can be explained by the fact that in the analytical solution domain is unbounded, while the numerical calculation was carried out, obviously, for a finite field. The given stresses at the top of the notch along the arc of an ellipse or a parabola significantly increase with increasing of the relative depth of the notch (while increasing its depth or decreasing width.

  14. Generation of stress-strain state in combined strip pile foundation beds through pressing of soil

    Directory of Open Access Journals (Sweden)

    Stepanov Maxim

    2017-01-01

    Full Text Available When erecting high-rise buildings, weak underlying soils cause a number of problems in design and construction. In order to ensure the required non-exceedance of the ultimate limit settlements, the combined strip pile foundation has been developed allowing the soil bed to be pre-stressed. This is achieved by injection of pressurized mortar (pressing. The paper analyzes the effect of soil pre-stressing followed by pressing of foundation with the cement mortar, as applied to existing structures using the Plaxis 3D software package in conditions of volume deformation and the Hardening Soil Model. Variable order of foundation pressing allows the required parameters of soil bed to be achieved in plan and depth, thus improving interaction with the foundation and superstructure.

  15. NUMERICAL ANALYSIS OF THE STRESS-STRAIN STATE OF A ROPE STRAND WITH LINEAR CONTACT UNDER TENSION AND TORSION LOADING CONDITIONS

    Directory of Open Access Journals (Sweden)

    Evgenij Kalentev

    2017-06-01

    Full Text Available The paper presents the results of a numerical analysis of the stress-strain state of a rope strand with linear contact under tension and torsion loading conditions. Calculations are done using the ANSYS software package. Different approaches to calculation of the stress-strain state of ropes are reviewed, and their advantages and deficiencies are considered. The analysis of the obtained results leads us to the conclusion that the proposed method can be used in engineering calculations.

  16. Prevalence of Posttraumatic Stress Disorder in Remotely Piloted Aircraft Operators in the United States Air Force

    Science.gov (United States)

    2016-05-24

    doctoral-level mental health professionals (clinical psychologists and psychiatrists) to determine the nature of the respondents’ stressful military...were purposefully limited to protect the anonymity and confidentiality of participant responses, as well as to promote genuine self-disclosure...Scale (CAPS). Participants with a total PCL-M score of greater than 37 were interviewed by a licensed USAF clinical psychologist or psychiatrist. The

  17. An Analysis of Post-Traumatic Stress Symptoms in United States Air Force Drone Operators

    Science.gov (United States)

    2014-05-17

    war-time imagery (i.e., potential traumatic events). Ouma, Chappelle, and Salinas (2011) investigated self- reported stress and burnout among 296 USAF...symptom criteria for PTSD diagnosis (as outlined in the DSM-IV) if they endorsed one or more intrusion symptoms, three or more avoidance symptoms, and two...ning_Among_Service_Members_Returning_from_Iraq.pdf Johnson, T., & Owens, L. (2003). Survey response rate reporting in the professional literature. In JSM 2003, statistics: a bridge to knowledge

  18. Stress analysis of ultrasonic density detector for LOFT core inlet steady-state and LOCE conditions. Supplement 1

    Energy Technology Data Exchange (ETDEWEB)

    Mosby, W.R.

    1979-04-25

    The UDD sensor bar with modified cross-section (0.0938-in. thick by 0.25-in. high overall) was analyzed to determine its resonant frequencies. Thermal and fluid-induced stresses due to steady-state and LOCE loads were also calculated. The sensor bar was shown not to be subject to vortex-shedding lock-in and was shown to meet applicable criteria of the ASME Boiler and Pressure Vessel Code. Seismic loads are insignificant compared to fluid loads.

  19. Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD

    Energy Technology Data Exchange (ETDEWEB)

    Holmberg, Jonas, E-mail: jonas.holmberg@swerea.se [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); University West, 461 86 Trollhättan (Sweden); Steuwer, Axel [Nelson Mandela Metropolitan University, Gardham Avenue, 6031 Port Elizabeth (South Africa); Stormvinter, Albin; Kristoffersen, Hans [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden); Haakanen, Merja [Stresstech OY, Tikkutehtaantie 1, 40 800 Vaajakoski (Finland); Berglund, Johan [Swerea IVF AB, Argongatan 30, 431 22 Mölndal (Sweden)

    2016-06-14

    Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.

  20. Production of medical radioactive isotopes using KIPT electron driven subcritical facility.

    Science.gov (United States)

    Talamo, Alberto; Gohar, Yousry

    2008-05-01

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine in collaboration with Argonne National Laboratory (ANL) has a plan to construct an electron accelerator driven subcritical assembly. One of the facility objectives is the production of medical radioactive isotopes. This paper presents the ANL collaborative work performed for characterizing the facility performance for producing medical radioactive isotopes. First, a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Then, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes have been considered and all transmutation channels are used including (n, gamma), (n, 2n), (n, p), and (gamma, n). In the second part, the parent isotopes with high reaction rate were explicitly modeled in the calculations. Four irradiation locations were considered in the analyses to study the medical isotope production rate. The results show the self-shielding effect not only reduces the specific activity but it also changes the irradiation location that maximizes the specific activity. The axial and radial distributions of the parent capture rates have been examined to define the irradiation sample size of each parent isotope.

  1. Recycling high-performance carbon fiber reinforced polymer composites using sub-critical and supercritical water

    Science.gov (United States)

    Knight, Chase C.

    Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown

  2. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces.

    Science.gov (United States)

    Carmichael, Justin R; Rother, Gernot; Browning, James F; Ankner, John F; Banuelos, Jose L; Anovitz, Lawrence M; Wesolowski, David J; Cole, David R

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO(2) in contact with quartz and Si/SiO(2) wafers are also shown. © 2012 American Institute of Physics

  3. Complete degradation of Orange G by electrolysis in sub-critical water.

    Science.gov (United States)

    Yuksel, Asli; Sasaki, Mitsuru; Goto, Motonobu

    2011-06-15

    Complete degradation of azo dye Orange G was studied using a 500 mL continuous flow reactor made of SUS 316 stainless steel. In this system, a titanium reactor wall acted as a cathode and a titanium plate-type electrode was used as an anode in a subcritical reaction medium. This hydrothermal electrolysis process provides an environmentally friendly route that does not use any organic solvents or catalysts to remove organic pollutants from wastewater. Reactions were carried out from 30 to 90 min residence times at a pressure of 7 MPa, and at different temperatures of 180-250°C by applying various direct currents ranging from 0.5 to 1A. Removal of dye from the product solution and conversion of TOC increased with increasing current value. Moreover, the effect of salt addition on degradation of Orange G and TOC conversion was investigated, because in real textile wastewater, many salts are also included together with dye. Addition of Na(2)CO(3) resulted in a massive degradation of the dye itself and complete mineralization of TOC, while NaCl and Na(2)SO(4) obstructed the removal of Orange G. Greater than 99% of Orange G was successfully removed from the product solution with a 98% TOC conversion. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

    Directory of Open Access Journals (Sweden)

    Kurian V. J.

    2017-01-01

    Full Text Available Vortex Induced Vibrations (VIV may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP, Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT. VIVFT is a two degree of freedom (2DOF forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes.

  5. Hydrothermal liquefaction of Spirulina and Nannochloropsis salina under subcritical and supercritical water conditions.

    Science.gov (United States)

    Toor, Saqib S; Reddy, Harvind; Deng, Shuguang; Hoffmann, Jessica; Spangsmark, Dorte; Madsen, Linda B; Holm-Nielsen, Jens Bo; Rosendahl, Lasse A

    2013-03-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220–375 °C, 20–255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid residue, and recycling process water for algae cultivation. GC–MS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained on N. salina at 350 °C and 175 bar. For S. platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for N. salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Energy conversion of biomass with supercritical and subcritical water using large-scale plants.

    Science.gov (United States)

    Okajima, Idzumi; Sako, Takeshi

    2014-01-01

    Exploiting unused or waste biomass as an alternative fuel is currently receiving much attention because of the potential reductions in CO2 emissions and the lower cost in comparison to expensive fossil fuels. If we are to use biomass domestically or industrially, we must be able to convert biomass to high-quality and easy-to-use liquid, gas, or solid fuels that have high-calorific values, low moisture and ash contents, uniform composition, and suitable for stored over long periods. In biomass treatment, hot and high-pressure water including supercritical and subcritical water is an excellent solvent, as it is clean and safe and its action on biomass can be optimized by varying the temperature and pressure. In this article, the conversion of waste biomass to fuel using hot and high-pressure water is reviewed, and the following examples are presented: the production of large amounts of hydrogen from waste biomass, the production of cheap bioethanol from non-food raw materials, and the production of composite powder fuel from refractory waste biomass in the rubble from the Great East Japan Earthquake. Several promising techniques for the conversion of biomass have been demonstrated in large-scale plants and commercial deployment is expected in the near future. Copyright © 2013. Published by Elsevier B.V.

  7. Subcritical Butane Extraction of Wheat Germ Oil and Its Deacidification by Molecular Distillation

    Directory of Open Access Journals (Sweden)

    Jinwei Li

    2016-12-01

    Full Text Available Extraction and deacidification are important stages for wheat germ oil (WGO production. Crude WGO was extracted using subcritical butane extraction (SBE and compared with traditional solvent extraction (SE and supercritical carbon dioxide extraction (SCE based on the yield, chemical index and fatty acid profile. Furthermore, the effects of the molecular distillation temperature on the quality of WGO were also investigated in this study. Results indicated that WGO extracted by SBE has a higher yield of 9.10% and better quality; at the same time, its fatty acid composition has no significant difference compared with that of SE and SCE. The molecular distillation experiment showed that the acid value, peroxide value and p-anisidine value of WGO were reduced with the increase of the evaporation temperatures, and the contents of the active constituents of tocopherol, polyphenols and phytosterols are simultaneously decreased. Generally, the distillation temperature of 150 °C is an appropriate condition for WGO deacidification with the higher deacidification efficiency of 77.78% and the higher retention rate of active constituents.

  8. Studies on subcritical and overcritical density laser ablated TAC foam targets

    Science.gov (United States)

    Chaurasia, S.; Leshma, P.; Murali, C. G.; Borisenko, N. G.; Munda, D. S.; Orekhov, A.; Gromov, A. I.; Merkuliev, Yu. A.; Dhareshwar, L. J.

    2015-05-01

    In this paper, the interaction of high power laser with low density polymer foam with density as low as 2 mg/cm3, 4 mg/cm3, 20 mg/cm3 30 mg/cm3 and 50 mg/cm3 targets are investigated and compared with solid polymer targets. An understanding of such interaction is important from fusion research point of view. Low density foam coating of fusion capsule has been proposed in order to smooth in direct drive scheme and also it is being used as efficient x-ray converter in indirect drive scheme. It is observed that about 75-80% of the laser energy is absorbed in the subcritical (with density case is almost two times that measured in the over dense (supper critical) targets. The optical shadowgraphy of the targets shows that the laser coupling in low density foam is associated with a supersonic heat wave while, with increasing density this phenomenon is replaced by subsonic absorption and shock formation. In the case of a 50 mg/cm3 foams the foil velocity reduced by 35% (i.e. 5×106 cm/s), which further reduced to 3.8×106 cm/s in case solid polymer targets.

  9. Particle formation of budesonide from alcohol-modified subcritical water solutions.

    Science.gov (United States)

    Carr, Adam G; Mammucari, Raffaella; Foster, Neil R

    2011-02-28

    Recently, subcritical water (SBCW: water that has been heated to a temperature between 100°C and 200°C at pressures of up to 70bar) has been used to dissolve several hydrophobic pharmaceutical compounds (Carr et al., 2010a). Furthermore, a number of active pharmaceutical ingredients (APIs) have been rapidly precipitated from SBCW solutions (Carr et al., 2010b,c). It is possible to alter the precipitate morphology by altering the processing variables; including the SBCW-API solution injection temperature and adding impurities (such as pharmaceutical excipients, e.g. lactose) to the precipitation chamber. The work presented in this article demonstrates that the morphology of pharmaceutical particles can be tuned by adding organic solvents (ethanol and methanol) to the SBCW-API solutions. Particle morphology has also been tuned by adding different pharmaceutical excipients (polyethylene glycol 400 and lactose) to the precipitation chamber. Different morphologies of pharmaceutical particles were produced, ranging from nanospheres of 60nm diameter to 5μm plate particles. Budesonide was used as the model API in this study. Two experimental products were spray dried to form dry powder products. The aerodynamic particle size of the powder was established by running the powder through an Andersen Cascade Impactor. It has been shown that the drug particles produced from the SBCW micronization process, when coupled with a spray drying process, are suitable for delivery to the lungs. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, John K.

    2009-11-01

    Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

  11. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces

    Science.gov (United States)

    Carmichael, Justin R.; Rother, Gernot; Browning, James F.; Ankner, John F.; Banuelos, Jose L.; Anovitz, Lawrence M.; Wesolowski, David J.; Cole, David R.

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.

  12. Subcritical water extraction and characterization of bioactive compounds from Haematococcus pluvialis microalga.

    Science.gov (United States)

    Rodríguez-Meizoso, I; Jaime, L; Santoyo, S; Señoráns, F J; Cifuentes, A; Ibáñez, E

    2010-01-20

    In this work, extraction and characterization of compounds with antioxidant and antimicrobial activity from Haematococcus pluvialis microalga in red phase have been carried out. To do this, subcritical water extraction (SWE) has been combined with analytical techniques such as HPLC-DAD, HPLC-QqQ-MS and GC-MS and in vitro assays (i.e., for antioxidant and antimicrobial activity). The effect of the extraction temperature (50, 100, 150 and 200 degrees C) and solvent polarity has been studied in terms of yield and activity of the extracts. Results demonstrate that the extraction temperature has a positive influence in the extraction yield and antioxidant activity. Thus, the extraction yield achieved with this process was higher than 30% of dry weight at 200 degrees C as extraction temperature. Moreover, the extract obtained at 200 degrees C presented the highest antioxidant activity by far, while temperature does not seem to significatively affect the antimicrobial activity. Chemical composition was determined by HPLC-DAD, HPLC-QqQ-MS and GC-MS. Short chain fatty acids turned out to be responsible of the antimicrobial activity, whereas the antioxidant activity was correlated to vitamin E (present exclusively in the 200 degrees C extract), together with simple phenols, caramelization products and possible Maillard reaction products obtained during the extraction at high temperatures.

  13. High performance curcumin subcritical water extraction from turmeric (Curcuma longa L.).

    Science.gov (United States)

    Valizadeh Kiamahalleh, Mohammad; Najafpour-Darzi, Ghasem; Rahimnejad, Mostafa; Moghadamnia, Ali Akbar; Valizadeh Kiamahalleh, Meisam

    2016-06-01

    Curcumin is a hydrophobic polyphenolic compound derived from turmeric rhizome, which consists about 2-5% of the total rhizome content and is a more valuable component of turmeric. For reducing the drawbacks of conventional extraction (using organic solvents) of curcumin, the water as a clean solvent was used for extracting curcumin. Subcritical water extraction (SWE) experimental setup was fabricated in a laboratory scale and the influences of some parameters (e.g. extraction temperature, particle size, retention time and pressure) on the yield of extraction were investigated. Optimum extraction conditions such as SWE pressure of 10bar, extractive temperature of 140°C, particle size of 0.71mm and retention time of 14min were defined. The maximum amount of curcumin extracted at the optimum condition was 3.8wt%. The yield of curcumin extraction was more than 76wt% with regards to the maximum possible curcumin content of turmeric, as known to be 5%. The scanning electron microscope (SEM) images from the outer surface of turmeric, before and after extraction, clearly demonstrated the effect of each parameter; changes in porosity and hardness of turmeric that is directly related to the amount of extracted curcumin in process optimization of the extraction parameters. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. The TRADE experiment: shielding calculations for the building hosting the subcritical system.

    Science.gov (United States)

    Burn, K W; Carta, M; Casalini, L; Kadi, Y; Monti, S; Nava, E; Palomba, M; Petrovich, C; Picardi, L; Rubbia, C; Troiani, F

    2005-01-01

    The TRADE project (TRiga Accelerator Driven Experiment), to be performed at the existing TRIGA reactor at ENEA Casaccia, has been proposed as a validation of the accelerator-driven system (ADS) concept. TRADE will be the first experiment in which the three main components of an ADS--the accelerator, spallation target and sub-critical blanket--are coupled at a power level sufficient to encounter reactivity feedback effects. As such, TRADE represents the necessary intermediate step in the development of hybrid transmutation systems, its expected outcomes being considered crucial--in terms of proof of stability of operation, dynamic behaviour and licensing issues--for the subsequent realisation of an ADS Transmutation Demonstrator. An essential role in the feasibility study of the experiment is played by radioprotection calculations. Such a system exhibits new characteristics with respect to a traditional reactor, owing to the presence of the proton accelerator. As beam losses always occur under normal operating conditions of an accelerator, shielding studies need to be performed not only around the reactor but also along the beam line from the accelerator to the spallation target. This paper illustrates a preliminary evaluation, using Monte Carlo methods, of the additional shielding to be located around the reactor structures, the beam transport line and the existing reactor building to allow access into the reactor hall and to restrict the doses outside to their legal limits.

  15. Optimization of subcritical water extraction of polysaccharides from Grifola frondosa using response surface methodology

    Science.gov (United States)

    Yang, Liuqing; Qu, Hongyuan; Mao, Guanghua; Zhao, Ting; Li, Fang; Zhu, Bole; Zhang, Bingtao; Wu, Xiangyang

    2013-01-01

    Background: This research is among the few that has been conducted on the feasibility of subcritical water extraction (SWE) as a rapid and efficient extraction tool for polysaccharides. Objective: The aim of the study was to extractand optimize the parameter conditions of SWE of polysaccharides from Grifola frondosa using response surface methodology. Materials and Methods: In the study, SWEwas applied to extractbioactive compounds from G. frondosa. A preliminary analysis was made on the physical properties and content determination of extracts using SWE and hot water extraction (HWE). Analysis of the sample residues and antioxidant activities of the polysaccharides extracted by SWE and HWE were then evaluated. Results: The optimal extraction conditions include: extraction temperature of 210°C, extraction time of 43.65 min and the ratio of water to raw material of 26.15:1. Under these optimal conditions, the experimental yield of the polysaccharides (25.1 ± 0.3%) corresponded with the mean value predicted by the model and two times more than the mean value obtained by the traditional HWE. The antioxidant activities of polysaccharides extracted by SWE were generally higher than those extracted by HWE. From the study, the SWE technology could be a time-saving, high yield, and bioactive technique for production of polysaccharides. PMID:23772107

  16. The effect of a hydroxyapatite impregnated PCL membrane in rat subcritical calvarial bone defects.

    Science.gov (United States)

    Groppo, Monica Feresini; Caria, Paulo Henrique; Freire, Alexandre Rodrigues; Figueroba, Sidney R; Ribeiro-Neto, Wilson Alves; Bretas, Rosario Elida Suman; Prado, Felippe Bevilacqua; Haiter-Neto, Francisco; Aguiar, Flavio Henrique; Rossi, Ana Claudia

    2017-10-01

    The present study evaluated the effect of polymeric-nanofibers membranes impregnated with microparticulate hydroxyapatite (HA) in the subcritical calvarial bone defects (SCBD) healing. PCL membranes with and without HA were obtained by electrospinning. SCBD were perforated (3.3mm) in left and right sides of 36 rat calvarias. The right-side SBCD of 18 animals was filled with HA mixed with blood clot and blood clot at the contralateral side. The remaining animals received PCL+HA membrane at the right-side SCBD and PCL membrane at the contralateral side. Animals were killed after 30, 60 and 90days after surgery. Bone defect volume (in mm3) was measured by tomography (CBCT). Qualitative histological analysis and SBCD area (in mm2) were measured. Quantitative data were submitted to Kruskal-Wallis/Dunn tests. Reduction of SBCD volume was observed in all treatments but PCL. Association with HA significantly improved bone healing induced by PCL and blood clot. PCL+HA induced the lowest SBCD volume at 60 and 90days. Complete bone healing was not observed even at 90days in SCBD treated with blood clot. In every period, more bone formation was observed for SCBD treated with membranes. We concluded that both PCL membrane and HA were able to improve bone healing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Subcritical carbon dioxide-water hydrolysis of sugarcane bagasse pith for reducing sugars production.

    Science.gov (United States)

    Liang, Jiezhen; Chen, Xiaopeng; Wang, Linlin; Wei, Xiaojie; Wang, Huasheng; Lu, Songzhou; Li, Yunhua

    2017-03-01

    The aim of present study was to obtain total reducing sugars (TRS) by hydrolysis in subcritical CO2-water from sugarcane bagasse pith (SCBP), the fibrous residue remaining after papermaking from sugarcane bagasse. The optimum hydrolysis conditions were evaluated by L16(4(5)) orthogonal experiments. The TRS yield achieved 45.8% at the optimal conditions: 200°C, 40min, 500rmin(-1), CO2 initial pressure of 1MPa and liquid-to-solid ratio of 50:1. Fourier transform infrared spectrometry and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance were used to characterize hydrolysis liquor, treated and untreated SCBP, resulting in the removal of hemicelluloses to mainly produce xylose, glucose and arabinose during hydrolysis. The severity factors had no correlation to TRS yield, indicating that the simple kinetic processes of biomass solubilisation cannot perfectly describe the SCBP hydrolysis. The first-order kinetic model based on consecutive reaction was used to obtain rate constants, activation energies and pre-exponential factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Sugars and char formation on subcritical water hydrolysis of sugarcane straw.

    Science.gov (United States)

    Lachos-Perez, D; Tompsett, G A; Guerra, P; Timko, M T; Rostagno, M A; Martínez, Julian; Forster-Carneiro, T

    2017-11-01

    Subcritical water has potential as an environmentally friendly solvent for applications including hydrolysis, liquefaction, extraction, and carbonization. Here, we report hydrolysis of sugarcane straw, an abundant byproduct of sugar production, in a semi-continuous reactor at reaction temperatures ranging from 190 to 260°C and at operating pressures of 9 and 16MPa. The target hydrolysis products were total reducing sugars. The main products of sugarcane straw hydrolysis were glucose, xylose, arabinose, and galactose in addition to 5- hydroxymethylfurfural and furfural as minor byproducts. Fourier transform infrared spectroscopy and thermogravimetric analysis provided additional information on the surface and bulk composition of the residual biomass. Char was present on samples treated at temperatures equal to and greater than 190°C. Samples treated at 260°C contained approximately 20wt% char, yet retained substantial hemicellulose and cellulose content. Hydrolysis temperature of 200°C provided the greatest TRS yield while minimizing char formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Subcritical co-solvents extraction of lipid from wet microalgae pastes of Nannochloropsis sp

    Science.gov (United States)

    Chen, Min; Liu, Tianzhong; Chen, Xiaolin; Chen, Lin; Zhang, Wei; Wang, Junfeng; Gao, Lili; Chen, Yu; Peng, Xiaowei

    2012-01-01

    In this paper subcritical co-solvents extraction (SCE) of algal lipid from wet pastes of Nannochloropsis sp. is examined. The influences of five operating parameters including the ratio between ethanol to hexane, the ratio of mixed solvents to algal biomass (dry weight), extraction temperature, pressure, and time were investigated. The determined optimum extraction conditions were 3:1 (hexane to ethanol ratio), 10:1 ratio (co-solvents to microalgae (dry weight) ratio), 90°C, 1.4 MPa, and 50 min, which could produce 88% recovery rate of the total lipids. In addition, electron micrographs of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were conducted to show that the algal cell presented shrunken, collapsed with some wrinkles and microholes after SCE extraction. The main composition of total lipids extracted under the optimum conditions was TAG which represented more than 80%. And the fatty acid profile of triglycerides revealed that C16:0 (35.67 ± 0.2%), C18:1 (26.84 ± 0.044%) and C16:1 (25.96 ± 0.011%) were dominant. Practical applications: The reported method could save energy consumption significantly through avoiding deep dewatering (for example drying). The composition of the extracted lipid is suitable for the production of high quality biodiesel. PMID:22745570

  20. Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L. Seed at Subcritical Conditions with Statistical Analysis

    Directory of Open Access Journals (Sweden)

    N. I. Yusoff

    2017-01-01

    Full Text Available Roselle seeds are the waste product of roselle processing, but they are now labeled as a polyphenol source with great herbal quality. In this work, polyphenols were extracted using ethanol-water (70% (v/v in a closed vessel under microwave irradiation. The main objective was to determine the optimal parameters statistically. The influence of extraction time (4–10 min, microwave power (100–300 W, and solvent/solid ratio (25–100 mL/g was studied. The total phenolic and flavonoids content were determined using Folin-Ciocalteu and aluminum chloride methods, respectively. Without temperature control, the subcritical conditions could occur and the highest flavonoid content (14.4251 mg QE/g was achieved at 158°C and 16.4 bar. Although the optimum MAE conditions (10 min, 300 W, and 97.7178 mL/g resulted in the highest yield (65.0367% and phenolic content (18.2244 mg GAE/g, low flavonoids content (6.4524 mg QE/g was unexpectedly obtained due to degradation at 163°C.

  1. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, A.; Wilson, L. B., III; Turner, D. L.; Dimmock, A. P.; Pulkkinen, T. I.

    2017-12-01

    The discovery of self-sustained coherent structures with large-amplitude electric fields (E ˜ 10 - 100 mV/m) by the Van Allen Probes has revealed alternative routes through which energy-momentum exchange can take place in planetary radiation belts. When originating from energetic electrons in Landau resonance with large-amplitude whistlers, phase-space electron holes form with small amplitudes of the order of the hot to cold electron density, i.e., qφ/T_e≃ n_h/n_c ≃ 10^{-3}, and orders of magnitude smaller than observed values of the largest phase-space holes amplitude, i.e., qφ /T_e ≃ 1. In this report we present a mechanism through which electron holes can grow nonlinearly (i.e. γ ∝ √{φ}) and subcritically as a result of momentum exchange with passing (untrapped) electrons. Growth rates are computed analytically for plasma parameters consistent with those measured in the Earth's radiation belts under quiet and disturbed conditions. Our results provide an explanation for the fast growth of electron phase-space holes in the Earth's radiation belts from small initial values qφ/T_c ≃ 10^{-3}, to larger values of the order qφ /T_e ≃ 1.

  2. The Optimal Evaporation Temperature of Subcritical ORC Based on Second Law Efficiency for Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Xu

    2012-03-01

    Full Text Available The subcritical Organic Rankine Cycle (ORC with 28 working fluids for waste heat recovery is discussed in this paper. The effects of the temperature of the waste heat, the critical temperature of working fluids and the pinch temperature difference in the evaporator on the optimal evaporation temperature (OET of the ORC have been investigated. The second law efficiency of the system is regarded as the objective function and the evaporation temperature is optimized by using the quadratic approximations method. The results show that the OET will appear for the temperature ranges investigated when the critical temperatures of working fluids are lower than the waste heat temperatures by 18 ± 5 K under the pinch temperature difference of 5 K in the evaporator. Additionally, the ORC always exhibits the OET when the pinch temperature difference in the evaporator is raised under the fixed waste heat temperature. The maximum second law efficiency will decrease with the increase of pinch temperature difference in the evaporator.

  3. Efficient, high-speed methane fermentation for sewage sludge using subcritical water hydrolysis as pretreatment.

    Science.gov (United States)

    Yoshida, Hiroyuki; Tokumoto, Hayato; Ishii, Kyoko; Ishii, Ryo

    2009-06-01

    A novel biomass-energy process for the production of methane from sewage sludge using a subcritical water (sub-CW) hydrolysis reaction as pretreatment is proposed. The main substances of sewage sludge hydrolyzed by sub-CW at 513 K for 10 min were acetic acid, formic acid, pyroglutamic acid, alanine, and glycine. Fermentation experiments were conducted in an anaerobic-sludge reactor for two different samples: real sewage sludge and a model solution containing components typically produced by the sub-CW pretreatment of sewage sludge. In the experiment for the sub-CW pretreatment of sewage sludge, methane generation was twice that for non-pretreatment after 3 days of incubation. In the model experiment, the methane conversion was about 40% with the application of mixture of organic acids and amino acids after 5 days of incubation. Furthermore, the methane conversion was about 60% for 2 days when only organic acids, such as acetic acid and formic acid, were applied. Because acetic acid is the key intermediate and main precursor of the methanogenesis step, fermentation experiments were conducted in an anaerobic-sludge reactor with high concentrations of acetic acid (0.01-0.1M). Nearly 100% of acetic acid was converted to methane and carbon dioxide in 1-3 days.

  4. Subcritical Butane Extraction of Wheat Germ Oil and Its Deacidification by Molecular Distillation.

    Science.gov (United States)

    Li, Jinwei; Sun, Dewei; Qian, Lige; Liu, Yuanfa

    2016-12-07

    Extraction and deacidification are important stages for wheat germ oil (WGO) production. Crude WGO was extracted using subcritical butane extraction (SBE) and compared with traditional solvent extraction (SE) and supercritical carbon dioxide extraction (SCE) based on the yield, chemical index and fatty acid profile. Furthermore, the effects of the molecular distillation temperature on the quality of WGO were also investigated in this study. Results indicated that WGO extracted by SBE has a higher yield of 9.10% and better quality; at the same time, its fatty acid composition has no significant difference compared with that of SE and SCE. The molecular distillation experiment showed that the acid value, peroxide value and p-anisidine value of WGO were reduced with the increase of the evaporation temperatures, and the contents of the active constituents of tocopherol, polyphenols and phytosterols are simultaneously decreased. Generally, the distillation temperature of 150 °C is an appropriate condition for WGO deacidification with the higher deacidification efficiency of 77.78% and the higher retention rate of active constituents.

  5. Physics design of an accelerator for an accelerator-driven subcritical system

    Directory of Open Access Journals (Sweden)

    Zhihui Li

    2013-08-01

    Full Text Available An accelerator-driven subcritical system (ADS program was launched in China in 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in multiple phases lasting about 20 years. The driver linac is defined to be 1.5 GeV in energy, 10 mA in current and in cw operation mode. To meet the extremely high reliability and availability, the linac is designed with much installed margin and fault tolerance, including hot-spare injectors and local compensation method for key element failures. The accelerator complex consists of two parallel 10-MeV injectors, a joint medium-energy beam transport line, a main linac, and a high-energy beam transport line. The superconducting acceleration structures are employed except for the radio frequency quadrupole accelerators (RFQs which are at room temperature. The general design considerations and the beam dynamics design of the driver linac complex are presented here.

  6. Subcritical Water Induced Complexation of Soy Protein and Rutin: Improved Interfacial Properties and Emulsion Stability.

    Science.gov (United States)

    Chen, Xiao-Wei; Wang, Jin-Mei; Yang, Xiao-Quan; Qi, Jun-Ru; Hou, Jun-Jie

    2016-09-01

    Rutin is a common dietary flavonoid with important antioxidant and pharmacological activities. However, its application in the food industry is limited mainly because of its poor water solubility. The subcritical water (SW) treatment provides an efficient technique to solubilize and achieve the enrichment of rutin in soy protein isolate (SPI) by inducing their complexation. The physicochemical, interfacial, and emulsifying properties of the complex were investigated and compared to the mixtures. SW treatment had much enhanced rutin-combined capacity of SPI than that of conventional method, ascribing to the well-contacted for higher water solubility of rutin with stronger collision-induced hydrophobic interactions. Compared to the mixtures of rutin with proteins, the complex exhibited an excellent surface activity and improved the physical and oxidative stability of its stabilized emulsions. This improving effect could be attributed to the targeted accumulation of rutin at the oil-water interface accompanied by the adsorption of SPI resulting in the thicker interfacial layer, as evidenced by higher interfacial protein and rutin concentrations. This study provides a novel strategy for the design and enrichment of nanovehicle providing water-insoluble hydrophobic polyphenols for interfacial delivery in food emulsified systems. © 2016 Institute of Food Technologists®

  7. Combined subcritical water and enzymatic hydrolysis for reducing sugar production from coconut husk

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Nurtono, Tantular; Widjaja, Arief

    2017-05-01

    Coconut husk wastes are abundantly available in Indonesia. It has a potential to be used into alternative renewable energy sources such as hydrogen using enzymatic hydrolysis followed by a fermentation process. Unfortunately, enzymatic hydrolysis is hampered by the complex structure of lignocellulose, so the cellulose component is hard to degrade. In this study, Combined Subcritical Water (SCW) and enzymatic hydrolysis are applied to enhance fermentable, thereby reducing production of sugar from coconut husk. There were two steps in this study, the first step was coconut husk pretreated by SCW in batch reactor at 80 bar and 150-200°C for 60 minutes reaction time. Secondly, solid fraction from the results of SCW was hydrolyzed using the mixture of pure cellulose and xylanase enzymes. Analysis was conducted on untreated and SCW-treated by gravimetric assay, liquid fraction after SCW and solid fraction after enzymatic hydrolysis using DNS assay. The maximum yield of reducing sugar (including xylose, arabinose glucose, galactose, mannose) was 1.254 gr per 6 gr raw material, representing 53.95% of total sugar in coconut husk biomass which was obtained at 150°C 80 bar for 60 minutes reaction time of SCW-treated and 6 hour of enzymatic hydrolysis using mixture of pure cellulose and xylanase enzymes (18.6 U /gram of coconut husk).

  8. Detecting and monitoring water stress states in maize crops using spectral ratios obtained in the photosynthetic domain

    Science.gov (United States)

    Baranoski, Gladimir V. G.; Van Leeuwen, Spencer R.

    2017-07-01

    The reliable detection and monitoring of changes in the water status of crops composed of plants like maize, a highly adaptable C4 species in large demand for both food and biofuel production, are longstanding remote sensing goals. Existing procedures employed to achieve these goals rely predominantly on the spectral signatures of plant leaves in the infrared domain where the light absorption within the foliar tissues is dominated by water. It has been suggested that such procedures could be implemented using subsurface reflectance to transmittance ratios obtained in the visible (photosynthetic) domain with the assistance of polarization devices. However, the experiments leading to this proposition were performed on detached maize leaves, which were not influenced by the whole (living) plant's adaptation mechanisms to water stress. In this work, we employ predictive simulations of light-leaf interactions in the photosynthetic domain to demonstrate that the living specimens' physiological responses to dehydration stress should be taken into account in this context. Our findings also indicate that a reflectance to transmittance ratio obtained in the photosynthetic domain at a lower angle of incidence without the use of polarization devices may represent a cost-effective alternative for the assessment of water stress states in maize crops.

  9. Correlation of growth temperature with stress, defect states and electronic structure in an epitaxial GaN film grown on c-sapphire via plasma MBE.

    Science.gov (United States)

    Krishna, Shibin; Aggarwal, Neha; Mishra, Monu; Maurya, K K; Singh, Sandeep; Dilawar, Nita; Nagarajan, Subramaniyam; Gupta, Govind

    2016-03-21

    The relationship of the growth temperature with stress, defect states, and electronic structure of molecular beam epitaxy grown GaN films on c-plane (0001) sapphire substrates is demonstrated. A minimum compressively stressed GaN film is grown by tuning the growth temperature. The correlation of dislocations/defects with the stress relaxation is scrutinized by high-resolution X-ray diffraction and photoluminescence measurements which show a high crystalline quality with significant reduction in the threading dislocation density and defect related bands. A substantial reduction in yellow band related defect states is correlated with the stress relaxation in the grown film. Temperature dependent Raman analysis shows the thermal stability of the stress relaxed GaN film which further reveals a downshift in the E2 (high) phonon frequency owing to the thermal expansion of the lattice at elevated temperatures. Electronic structure analysis reveals that the Fermi level of the films is pinned at the respective defect states; however, for the stress relaxed film it is located at the charge neutrality level possessing the lowest electron affinity. The analysis demonstrates that the generated stress not only affects the defect states, but also the crystal quality, surface morphology and electronic structure/properties.

  10. Effects of selenium supplementation on the oxidative state of acute heat stress-exposed quails.

    Science.gov (United States)

    Del Vesco, A P; Gasparino, E; Zancanela, V; Grieser, D O; Stanquevis, C E; Pozza, P C; Oliveira Neto, A R

    2017-02-01

    This study aimed to evaluate the effect of heat stress (HS) and selenium supplementation on markers of stress, meat quality and gene expression. For this, meat quails of 42 days of age were fed a diet that either met [0.33 mg/kg, nutritional demand for selenium (SS)] or did not meet [0.11 mg/kg, selenium deficient (SD)] the nutritional demands for selenium during the 7 days of evaluation. In addition, the animals were kept at either a thermal comfort temperature (25 °C) or exposed to HS (38 °C for 24 h). Glutathione synthetase (GSS), glutathione reductase (GSR) and uncoupling protein (UCP) gene expression were influenced by the interaction between temperature and diet. Animals subjected to HS and fed the SS diet exhibited the highest GSS and GSR gene expression. In terms of UCP gene expression, the lowest values were observed in HS animals on the SD diet. Glutathione peroxidase 7 (GPX7) gene expression, body temperature (BT) and creatine kinase (CK) activity were influenced by both selenium supplementation and HS. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) activity and creatinine content all were influenced by the diet/environment interaction. The highest AST activity, ALT activity and creatinine levels were observed in animals that were both on the SD diet and exposed to HS. HS animals also exhibited an increased heterophil/lymphocyte ratio and lower triiodothyronine (T3) hormone levels than birds that remained at the comfortable temperature. Animals subjected to HS and fed with selenium supplemented diet showed better results regarding gene expression and, thus, better results for the activities of enzymes used as stress markers, which could be due to the higher antioxidant capacity provided by the action of the studied genes. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  11. Residual Stress State in Single-Edge Notched Tension Specimen Caused by the Local Compression Technique

    Directory of Open Access Journals (Sweden)

    Huang Yifan

    2016-12-01

    Full Text Available Three-dimensional (3D finite element analyses (FEA are performed to simulate the local compression (LC technique on the clamped single-edge notched tension (SE(T specimens. The analysis includes three types of indenters, which are single pair of cylinder indenters (SPCI, double pairs of cylinder indenters (DPCI and single pair of ring indenters (SPRI. The distribution of the residual stress in the crack opening direction in the uncracked ligament of the specimen is evaluated. The outcome of this study can facilitate the use of LC technique on SE(T specimens.

  12. Amnion-Epithelial-Cell-Derived Exosomes Demonstrate Physiologic State of Cell under Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Samantha Sheller

    Full Text Available At term, the signals of fetal maturity and feto-placental tissue aging prompt uterine readiness for delivery by transitioning quiescent myometrium to an active stage. It is still unclear how the signals reach the distant myometrium. Exosomes are a specific type of extracellular vesicle (EVs that transport molecular signals between cells, and are released from a wide range of cells, including the maternal and fetal cells. In this study, we hypothesize that i exosomes act as carriers of signals in utero-placental compartments and ii exosomes reflect the physiologic status of the origin cells. The primary aims of this study were to determine exosomal contents in exosomes derived from primary amnion epithelial cells (AEC. We also determined the effect of oxidative stress on AEC derived exosomal cargo contents. AEC were isolated from amniotic membrane obtained from normal, term, not in labor placentae at delivery, and culture under standard conditions. Oxidative stress was induced using cigarette smoke extract for 48 hours. AEC-conditioned media were collected and exosomes isolated by differential centrifugations. Both growth conditions (normal and oxidative stress induced produced cup shaped exosomes of around 50 nm, expressed exosomes enriched markers, such as CD9, CD63, CD81 and HSC70, embryonic stem cell marker Nanog, and contained similar amounts of cell free AEC DNA. Using confocal microscopy, the colocalization of histone (H 3, heat shock protein (HSP 70 and activated form of pro-senescence and term parturition associated marker p38 mitogen activated protein kinase (MAPK (P-p38 MAPK co-localized with exosome enrich marker CD9. HSP70 and P-p38 MAPK were significantly higher in exosomes from AEC grown under oxidative stress conditions than standard conditions (p<0.05. Finally, mass spectrometry and bioinformatics analysis identified 221 different proteins involved in immunomodulatory response and cell-to-cell communication. This study determined

  13. Stress and food deprivation: linking physiological state to migration success in a teleost fish

    DEFF Research Database (Denmark)

    Midwood, J.D.; Larsen, Martin Hage; Aarestrup, Kim

    2016-01-01

    Food deprivation (FD) is a naturally occurring stressor that is thought to influence the ultimate life-history strategy of individuals. Little is known about how FD interacts with other stressors to influence migration success. European populations of brown trout (Salmo trutta) exhibit partial...... of the glucocorticoid stress response in determining life-history strategy and survival of a migratory species. Using an experimental approach, the relative influences of short-term FD and experimental cortisol elevation (i.e., intra-coelomic injection of cortisol suspended in cocoa butter) on migratory status...

  14. Electromagnetic and ultrasonic techniques to evaluate stress states of components; Elektromagnetische und Ultraschallverfahren zur Spannungsanalyse an Bauteilen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, E.; Kern, R.; Theiner, W.A. [Fraunhofer Inst. fuer Zerstoerungsfreie Pruefverfahren, IZFP, Saarbruecken (Germany)

    1999-08-01

    The electromagnetic and ultrasonic techniques are comparably recent NDT methods for determination of stress states of components. They are simple in application, but require pre-measurement preparation: Electromagnetic techniques need calibration, and quantitative stress analysis by ultrasonic techniques needs reference values, i.e. verified materials-specific quantities to be obtained with representative specimens. Electromagnetic and ultrasonic techniques have been developed for specific tests at defined components, and the corresponding instruments and sensors have been used in practice for several years now. The paper summarizes fundamental aspects and explains the state of the art by means of several examples. (orig./CB) [Deutsch] Elektromagnetische und Ultraschallverfahren sind vergleichsweise neue zerstoerungsfreie Verfahren zur Bestimmung von Eigenspannungen in Bauteilen. Ihre Anwendung ist einfach, setzt aber Vorarbeiten voraus: Elektromagnetische Verfahren muessen kalibriert und zur quantitativen Spannungsanalyse mittels Ultraschallverfahren muessen materialspezifische Kenngroessen an repraesentativen Materialproben ermittelt werden. Elektromagnetische und Ultraschallverfahren sind fuer konkrete Anwendungen an Bauteilen entwickelt, angepasste Geraete und Sensoren seit Jahren in der Nutzung. Der Beitrag fasst die Grundlagen zusammen und stellt den Stand der Technik anhand ausgewaehlter Anwendungen dar. (orig.)

  15. Design, Analysis and Application of a Novel Test for Sheet Metal Forming Limits under Non-Planar Stress States

    Science.gov (United States)

    Allwood, Julian M.; Shouler, Daniel R.

    2011-05-01

    Recent work on incremental sheet forming processes has demonstrated that they induce non-planar stress states which give significantly increased forming limits. In previous work, we have extended the Marcinak-Kuczynski analysis for in-plane loading to include proportional loading with all six components of the stress tensor, and have represented the results as a generalised forming limit diagram. This paper proposes a first standardised test of forming limits under these conditions. A novel apparatus is constructed in which a sliding carriage can apply controllable compressive rolling, three-roll bending, or through thickness shearing to a sample undergoing uniaxial extension. Finite element analysis demonstrates the effect of this loading on deformation and details of equipment design are given. Initial trials are used to assess the repeatability of the tests and to confirm whether the strain states induced in the workpieces conform with finite element predictions. Tests to examine increases in formability under various loading conditions show greatly increased failure strains, but with some variability in results, and only partial agreement with analytical predictions.

  16. How sugars protect proteins in the solid state and during drying (review): Mechanisms of stabilization in relation to stress conditions.

    Science.gov (United States)

    Mensink, Maarten A; Frijlink, Henderik W; van der Voort Maarschalk, Kees; Hinrichs, Wouter L J

    2017-05-01

    This review aims to provide an overview of current knowledge on stabilization of proteins by sugars in the solid state in relation to stress conditions commonly encountered during drying and storage. First protein degradation mechanisms in the solid state (i.e. physical and chemical degradation routes) and traditional theories regarding protein stabilization (vitrification and water replacement hypotheses) will be briefly discussed. Secondly, refinements to these theories, such as theories focusing on local mobility and protein-sugar packing density, are reviewed in relationship to the traditional theories and their analogies are discussed. The last section relates these mechanistic insights to the stress conditions against which these sugars are used to provide protection (i.e. drying, temperature, and moisture). In summary sugars should be able to adequately form interactions with the protein during drying, thereby maintaining it in its native conformation and reducing both local and global mobility during storage. Generally smaller sugars (disaccharides) are better at forming these interactions and reducing local mobility as they are less inhibited by steric hindrance, whilst larger sugars can reduce global mobility more efficiently. The principles outlined here can aid in choosing a suitable sugar as stabilizer depending on the protein, formulation and storage condition-specific dominant route of degradation. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Influence of a laminar steady-state fluid-imposed wall shear stress on the binding, internalization, and degradation of low-density lipoproteins by cultured arterial endothelium.

    Science.gov (United States)

    Sprague, E A; Steinbach, B L; Nerem, R M; Schwartz, C J

    1987-09-01

    Fluid mechanical steady-state laminar wall shear stresses of 30 dyne/cm2 (high stress) and less than 1 dyne/cm2 (low stress) have been applied for varying times to confluent cultures of bovine aortic endothelial cells (BAECs) by means of two parallel plate channel flow chambers in series. BAEC cultures not exposed to shear or flow (no stress) were also studied. A shear stress of 30 dyne/cm2 resulted in cellular elongation and alignment, changes that were largely complete by 24 hr. In experiments in which BAECs were incubated with 125I-labeled low-density lipoprotein for 2 or 24 hr in the presence of shear stress levels, 125I-LDL internalization at 24 hr was increased (p less than .05) in response to high-stress conditions. This increased uptake of 125I-LDL was observed in BAECs prealigned for 24 hr under high stress and in BAECs undergoing alignment in the presence of circulating 125I-LDL. BAECs were also exposed to shear stress for 24 hr in the presence of a lipoprotein-deficient circulating medium to maximize LDL receptor expression. Receptor-mediated 125I-LDL internalization and degradation measured immediately after shear stress were both significantly enhanced (p less than .01) in BAECs exposed to high stress. Furthermore, 125I-LDL binding studies at 4 degrees C revealed a significant increase (p less than .01) in specific 125I-LDL binding to BAECs exposed to high stress relative to those exposed to low or no stress. Nonspecific 125I-LDL endocytosis was not influenced by shear stress levels.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. 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.

  19. Analysis of the stress-strain state in single overlap joints using piezo-ceramic actuators

    Science.gov (United States)

    Pǎltânea, Veronica; Pǎltânea, Gheorghe; Popovici, Dorina; Jiga, Gabriel; Papanicolaou, George

    2014-05-01

    In this paper is presented a 2D approach to finite element modeling and an analytical calculus of a single lap bonded joint. As adherent material were selected a sheet of wood, aluminum and titanium. For adhesive part were selected Bison Super Wood D3 in case of the wood single lap joint and an epoxy resin type DGEBA-TETA for gluing together aluminum and titanium parts. In the article is described a combined method, which consists in the placement of the piezoelectric actuator inside of the adhesive part, in order to determine the tensile stress in the overlap joint. A comparison between the analytical and numerical results has been achieved through a multiphysics modeling - electrical and mechanical coupled problem. The technique used to calculate the mechanical parameters (First Principal Stress, displacements) was the three-point bending test, where different forces were applied in the mid-span of the structure, in order to maintain a constant displacement rate. The length of the overlap joint was modified from 20 to 50 mm.

  20. Predicting Carbonation Depth of Prestressed Concrete under Different Stress States Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Chunhua Lu

    2009-01-01

    Full Text Available Two artificial neural networks (ANN, back-propagation neural network (BPNN and the radial basis function neural network (RBFNN, are proposed to predict the carbonation depth of prestressed concrete. In order to generate the training and testing data for the ANNs, an accelerated carbonation experiment was carried out, and the influence of stress level of concrete on carbonation process was taken into account especially. Then, based on the experimental results, the BPNN and RBFNN models which all take the stress level of concrete, water-cement ratio, cement-fine aggregate, cement-coarse aggregate ratio and testing age as input parameters were built and all the training and testing work was performed in MATLAB. It can be found that the two ANN models seem to have a high prediction and generalization capability in evaluation of carbonation depth, and the largest absolute percentage errors of BPNN and RBFNN are 10.88% and 8.46%, respectively. The RBFNN model shows a better prediction precision in comparison to BPNN model.