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.

Scale effect in fatigue resistance under complex stressed state

International Nuclear Information System (INIS)

Sosnovskij, L.A.

1979-01-01

On the basis the of the fatigue failure statistic theory obtained is the formula for calculated estimation of probabillity of failure under complex stressed state according to partial probabilities of failure under linear stressed state with provision for the scale effect. Also the formula for calculation of equivalent stress is obtained. The verification of both formulae using literary experimental data for plane stressed state torsion has shown that the error of estimations does not exceed 10% for materials with the ultimate strength changing from 61 to 124 kg/mm 2

Biaxial nominal state of stress at the crack front

International Nuclear Information System (INIS)

Dietmann, H.; Kussmaul, K.

1979-01-01

In fracture toughness testing with CT-specimens there is an unaxial nominal stress state caused by the nominal stress psub(y) perpendicular to the crack surface. This paper investigates the question whether the fracture toughness, or generally speaking, the fracture load, is influenced by additional nominal stresses psub(x) and psub(z) in the crack surface, i.e. by a multiaxial stress state. (orig.)

Smartphone Applications Utilizing Biofeedback Can Aid Stress Reduction

Science.gov (United States)

Dillon, Alison; Kelly, Mark; Robertson, Ian H.; Robertson, Deirdre A.

2016-01-01

Introduction: Stress is one of the leading global causes of disease and premature mortality. Despite this, interventions aimed at reducing stress have low adherence rates. The proliferation of mobile phone devices along with gaming-style applications allows for a unique opportunity to broaden the reach and appeal of stress-reduction interventions in modern society. We assessed the effectiveness of two smartphone applications games combined with biofeedback in reducing stress. Methods: We compared a control game to gaming-style smartphone applications combined with a skin conductance biofeedback device (the Pip). Fifty participants aged between 18 and 35 completed the Trier Social Stress Test. They were then randomly assigned to the intervention (biofeedback game) or control group (a non-biofeedback game) for thirty minutes. Perceived stress, heart rate and mood were measured before and after participants had played the games. Results: A mixed factorial ANOVA showed a significant interaction between time and game type in predicting perceived stress [F(1,48) = 14.19, p biofeedback intervention had significantly reduced stress compared to the control group. There was also a significant interaction between time and game in predicting heart rate [F(1,48) = 6.41, p biofeedback intervention showed significant reductions in heart rate compared to the control group. Discussion: This illustrates the potential for gaming-style smartphone applications combined with biofeedback as stress reduction interventions. PMID:27378963

Evaluation of the state of stress at the Forsmark site. Preliminary site investigation Forsmark area - version 1.2

Energy Technology Data Exchange (ETDEWEB)

Sjoeberg, Jonny; Lindfors, Ulf; Perman, Fredrik; Ask, Daniel [SwedPower AB, Stockholm (Sweden)

2005-09-15

horizontal stress was found in gneissic rock. Aside from this, clear correlations between rock type and measured stresses were also lacking, as well as confirmatory evidence of a low-stress environment in the superficial, more fractured bedrock. Assessment of a representative stress state for the Forsmark site was based on different subsets of the total data set of stress measurements. Linear stress profiles were assumed for the horizontal and vertical stress components, with each stress profile being representative of the conditions within the tectonic lens. These stress profiles define the lower and upper limit of the stress state based on the data considered reliable for each stress component. The resulting stress profiles are: Maximum horizontal stress ({sigma}H) applicable for 230-450 m vertical depth (z): Lower limit: {sigma}H = 0.085z (MPa), Upper limit: {sigma}H = 13+0.095z (MPa), Alternative upper limit: {sigma}H 29+0.050z (MPa). Orientation: 140 deg (clockwise from North). Minimum horizontal stress ({sigma}h) applicable for 0-1,000 m vertical depth (z): Lower limit: {sigma}h = 0.022z (MPa), Upper limit: {sigma}h 5.5+0.0265z (MPa). Vertical stress ({sigma}v) applicable for 0-800 m vertical depth (z): {sigma}v = 0.0265z (MPa). Future measurements and activities should be planned to address the gaps indicated by the present data set. It is recommended that new overcoring measurements are conducted, starting already at approximately 100 m depth below the ground surface, and continued as deep as possible - until the method is no longer applicable (extensive core damage and/or core discing inhibiting correct installation and/or overcoring of the measurement probe). Furthermore, any observations on core discing should be logged in detail to provide confirmatory evidence of stress magnitudes. If core discing of solid core is observed, pilot hole drilling with subsequent overcoring (without installation of the measurement probe) should be considered to induce ring discing

Evaluation of the state of stress at the Forsmark site. Preliminary site investigation Forsmark area - version 1.2

International Nuclear Information System (INIS)

Sjoeberg, Jonny; Lindfors, Ulf; Perman, Fredrik; Ask, Daniel

2005-09-01

gneissic rock. Aside from this, clear correlations between rock type and measured stresses were also lacking, as well as confirmatory evidence of a low-stress environment in the superficial, more fractured bedrock. Assessment of a representative stress state for the Forsmark site was based on different subsets of the total data set of stress measurements. Linear stress profiles were assumed for the horizontal and vertical stress components, with each stress profile being representative of the conditions within the tectonic lens. These stress profiles define the lower and upper limit of the stress state based on the data considered reliable for each stress component. The resulting stress profiles are: Maximum horizontal stress (σH) applicable for 230-450 m vertical depth (z): Lower limit: σH = 0.085z (MPa), Upper limit: σH = 13+0.095z (MPa), Alternative upper limit: σH 29+0.050z (MPa). Orientation: 140 deg (clockwise from North). Minimum horizontal stress (σh) applicable for 0-1,000 m vertical depth (z): Lower limit: σh = 0.022z (MPa), Upper limit: σh 5.5+0.0265z (MPa). Vertical stress (σv) applicable for 0-800 m vertical depth (z): σv = 0.0265z (MPa). Future measurements and activities should be planned to address the gaps indicated by the present data set. It is recommended that new overcoring measurements are conducted, starting already at approximately 100 m depth below the ground surface, and continued as deep as possible - until the method is no longer applicable (extensive core damage and/or core discing inhibiting correct installation and/or overcoring of the measurement probe). Furthermore, any observations on core discing should be logged in detail to provide confirmatory evidence of stress magnitudes. If core discing of solid core is observed, pilot hole drilling with subsequent overcoring (without installation of the measurement probe) should be considered to induce ring discing of a hollow core. Having two observations of different core geometries can

Tremor frequency characteristics in Parkinson's disease under resting-state and stress-state conditions.

Science.gov (United States)

Lee, Hong Ji; Lee, Woong Woo; Kim, Sang Kyong; Park, Hyeyoung; Jeon, Hyo Seon; Kim, Han Byul; Jeon, Beom S; Park, Kwang Suk

2016-03-15

Tremor characteristics-amplitude and frequency components-are primary quantitative clinical factors for diagnosis and monitoring of tremors. Few studies have investigated how different patient's conditions affect tremor frequency characteristics in Parkinson's disease (PD). Here, we analyzed tremor characteristics under resting-state and stress-state conditions. Tremor was recorded using an accelerometer on the finger, under resting-state and stress-state (calculation task) conditions, during rest tremor and postural tremor. The changes of peak power, peak frequency, mean frequency, and distribution of power spectral density (PSD) of tremor were evaluated across conditions. Patients whose tremors were considered more than "mild" were selected, for both rest (n=67) and postural (n=25) tremor. Stress resulted in both greater peak powers and higher peak frequencies for rest tremor (pstate condition. The distributions of PSD of tremor were symmetrical, regardless of conditions. Tremor is more evident and typical tremor characteristics, namely a lower frequency as amplitude increases, are different in stressful condition. Patient's conditions directly affect neural oscillations related to tremor frequencies. Therefore, tremor characteristics in PD should be systematically standardized across patient's conditions such as attention and stress levels. Copyright © 2016. Published by Elsevier B.V.

Constitutive relations describing creep deformation for multi-axial time-dependent stress states

Science.gov (United States)

McCartney, L. N.

1981-02-01

A THEORY of primary and secondary creep deformation in metals is presented, which is based upon the concept of tensor internal state variables and the principles of continuum mechanics and thermodynamics. The theory is able to account for both multi-axial and time-dependent stress and strain states. The wellknown concepts of elastic, anelastic and plastic strains follow naturally from the theory. Homogeneous stress states are considered in detail and a simplified theory is derived by linearizing with respect to the internal state variables. It is demonstrated that the model can be developed in such a way that multi-axial constant-stress creep data can be presented as a single relationship between an equivalent stress and an equivalent strain. It is shown how the theory may be used to describe the multi-axial deformation of metals which are subjected to constant stress states. The multi-axial strain response to a general cyclic stress state is calculated. For uni-axial stress states, square-wave loading and a thermal fatigue stress cycle are analysed.

The influence of the stress state on Ksub(Ic)

International Nuclear Information System (INIS)

Aurich, D.; Helms, R.; Schmidt, P.; Veith, H.; Ziebs, J.

1977-01-01

To get a first impression of the influence of stress states of higher multi-axiality than plane strain on Ksub(c) a specimen has been created, in which a bi-axial nominal stress state arises by uniaxial tension. This is attained by tension superimposed by transverse bending stress. The stress distribution without crack was analysed by photoelasticity as well as by finite element method. The results were identical. The stress distribution in the fracture (crack) plane was somewhat inhomogeneous, of course. But the ratio of the stress parallel to the tension axis to that perpendicular to it was max. 1:0.3 with a mean value 1:0.15. Specimens of this type were machined from a rolled sheet of the steel 22 NiMoCr 37, with specimen thickness of about 50 mm. For comparison single-edge notched specimens of the same cross section were prepared from the same material. Fatigue cracks were made following ASTM Recommendations. The fracture mechanics tests were carried out at a temperature of -100 0 C. Although valid Ksub(Ic)-values following the rigorous intention of the linear elastic fracture mechanics (ASTM Recommendations) were not obtained, the differences between the results of the two types of specimens and stress states were significant. The Ksub(Q)-values of the bi-axial stressed specimen were about 25% lower than that of the single-edge notched specimen. The deviation of the load-displacement trace from the linear elastic behavior was greater for the single-edge notched specimens than for the bi-axial stressed specimens. The consequences of these results for the assessment of flaws in pressure vessels are evident considering that bi-axial nominal stress states occur in pressure vessels

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

The effect of stress state on zirconium hydride reorientation

Science.gov (United States)

Cinbiz, Mahmut Nedim

Prior to storage in a dry-cask facility, spent nuclear fuel must undergo a vacuum drying cycle during which the spent fuel rods are heated up to elevated temperatures of ≤ 400°C to remove moisture the canisters within the cask. As temperature increases during heating, some of the hydride particles within the cladding dissolve while the internal gas pressure in fuel rods increases generating multi-axial hoop and axial stresses in the closed-end thin-walled cladding tubes. As cool-down starts, the hydrogen in solid solution precipitates as hydride platelets, and if the multiaxial stresses are sufficiently large, the precipitating hydrides reorient from their initial circumferential orientation to radial orientation. Radial hydrides can severely embrittle the spent nuclear fuel cladding at low temperature in response to hoop stress loading. Because the cladding can experience a range of stress states during the thermo-mechanical treatment induced during vacuum drying, this study has investigated the effect of stress state on the process of hydride reorientation during controlled thermo-mechanical treatments utilizing the combination of in situ X-ray diffraction and novel mechanical testing analyzed by the combination of metallography and finite element analysis. The study used cold worked and stress relieved Zircaloy-4 sheet containing approx. 180 wt. ppm hydrogen as its material basis. The failure behavior of this material containing radial hydrides was also studied over a range of temperatures. Finally, samples from reactor-irradiated cladding tubes were examined by X-ray diffraction using synchrotron radiation. To reveal the stress state effect on hydride reorientation, the critical threshold stress to reorient hydrides was determined by designing novel mechanical test samples which produce a range of stress states from uniaxial to "near-equibiaxial" tension when a load is applied. The threshold stress was determined after thermo-mechanical treatments by

Assessment of brain activities during an emotional stress state using fMRI

International Nuclear Information System (INIS)

Hayashi, Takuto; Mizuno-Matsumoto, Yuko; Kawasaki, Aika; Kato, Makoto; Murata, Tsutomu

2011-01-01

We investigated cerebrum activation using functional magnetic resonance imaging during a mental stress state. Thirty-four healthy adults participated. Before the experiment, we assessed their stress states using the Stress Self-rating Scale and divided the participants into Stress and Non-stress groups. The experiment consisted of 6 trials. Each trial consisted of a 20-s block of emotional audio-visual stimuli (4-s stimulation x 5 slides) and a fixation point. These processes were performed 3 times continuously (Relaxed, Pleasant, Unpleasant stimuli) in a random order. These results showed that the Non-stress group indicated activation of the amygdala and hippocampus in the Pleasant and Unpleasant stimuli while the Stress group indicated activation of the hippocampus in Pleasant stimuli, and the amygdala and hippocampus in Unpleasant stimuli. These findings suggested that the mental stress state engages the reduction of emotional processing. Also, the responsiveness of the memory system remained during and after the emotional stress state. (author)

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.

Stress evolution in elastic-plastic electrodes during electrochemical processes: A numerical method and its applications

Science.gov (United States)

Wen, Jici; Wei, Yujie; Cheng, Yang-Tse

2018-07-01

Monitoring in real time the stress state in high capacity electrodes during charge-discharge processes is pivotal to the performance assessment and structural optimization of advanced batteries. The wafer curvature measurement technique broadly employed in thin-film industry, together with stress analysis using the Stoney equation, has been successfully adopted to measure in situ the stress in thin film electrodes. How large plastic deformation or interfacial delamination during electrochemical cycles in such electrodes affects the applicability of Stoney equation remains unclear. Here we develop a robust electrochemical-mechanical coupled numerical procedure to investigate the influence of large plastic deformation and interfacial failure on the measured stress in thin film electrodes. We identify how the constitutive behavior of electrode materials and film-substrate interfacial properties affect the measured stress-capacity curves of electrodes, and hence establish the relationship of electrode material parameters with the characteristics of stress-capacity curves. Using Li-ions batteries as examples, we show that plastic deformation and interfacial delamination account for the asymmetric stress-capacity loops seen in in situ stress measurements. The methods used here, along with the finite-element code in the supplementary material, may be used to model the electrode behavior as a function of the state of charge.

Development of Kossel micro-diffraction for strain and stress analysis at the micrometer scale: applications to crystalline materials

International Nuclear Information System (INIS)

Bouscaud, D.

2012-01-01

X-ray diffraction is a non-destructive method frequently used in materials science to analyse the stress state at a macroscopic scale. Due to the growing complexity of new materials and their applications, it is necessary to know the strain and stress state at a lower scale. Thus, a Kossel micro-diffraction experimental set-up was developed inside a scanning electron microscope. It allows to obtain the crystallographic orientation as well as the strains and stresses within a volume of a few cubic micrometers. Some experiments were also performed using a synchrotron radiation. An experimental procedure was developed to optimize the acquisition of Kossel line patterns and their post-processing. The stress calculation from Kossel patterns was validated by comparing the stress state of single crystals during in situ mechanical loading, obtained by Kossel micro-diffraction and with classical diffraction methods. Then Kossel micro-diffraction was applied to polycrystalline samples by gradually decreasing the grain size. Intergranular stress heterogeneities were for example measured in an interstitial-free steel. Experiments were finally carried out in thin layer samples representative of microelectronic components. (author)

X-ray multiaxial stress analysis by means of polynomial approximation and an application to plane stress problem

International Nuclear Information System (INIS)

Yoshioka, Yasuo; Sasaki, Toshihiko; Kuramoto, Makoto.

1984-01-01

A new polynomial approximation method was proposed for the X-ray multiaxial stress analysis, in which the effect of stress gradient along the penetration depth of X-rays was taken into account. Three basic assumptions were made; (1) the stress gradient is linear in respect to the depth from the specimen surface, (2) the ponetration depth of X-rays is a function of Sin 2 phi and (3) the strain measured by X-rays corresponds to the weighted average strain on the intensity of the diffracted X-rays. Consequently, the stress state within the thin layer near the surface was expressed by making use of three surface stresses and six stress gradients in the present method. The average strains by X-rays were approximated by the third order polynomial equations of sin 2 phi using a least square method at several phi angles on the coordinate system of specimen. Since the coefficients of these polynomials include these nine stress components mentioned above, it is possible to solve them as simultaneous equations. The calculating process of this method is simpler than that of the integral method. An X-ray plane stress problem was analyzed as an application of the present method, and the residual stress distribution on a shot-peened steel plate was actually measured by use of Cr-Kα X-rays to verify the analysis. The result showed that the compressive residual stress near the surface determined by the present method was smaller than the weighted average stress by the Sin 2 phi method because of the steep stress gradient. The present method is useful to obtain a reasonable value of stress for such a specimen with steep stress gradients near the surface. (author)

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...... and on isotropically consolidated, cubical specimens, both tested in triaxial compression and extension, clearly showed the influence of the undisturbed fabric as well as the effect of the initial consolidation stress states. While the K0-consolidated specimens appeared to retain their original fabric and exhibit...

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.

PRESENTDAY STRESS STATE OF THE SHANXI TECTONIC BELT

Directory of Open Access Journals (Sweden)

Wang Kaiying

2012-01-01

Full Text Available The Shanxi tectonic belt is a historically earthquakeabundant area. For the majority of strong earthquakes in this area, the distribution of earthquake foci was controlled by the N–S oriented local structures on the tectonic belt. Studies of the present stress state of the Shanxi tectonic belt can contribute to the understanding of the relationship between strong earthquakes’ occurrence and their structural distribution and also facilitate assessments of regional seismic danger and determination of the regions wherein strong earthquakes may occur in future. Using the Cataclastic Analysis Method (CAM, we performed stress inversion based on the focal mechanism data of earthquakes which took place in the Shanxi tectonic belt from 1967 to 2010. Our results show that orientations of the maximum principal compressive stress axis of the Shanxi tectonic belt might have been variable before and after the 2001 Kunlun MS=8.1 strong earthquake, with two different superior trends of the NW–SE and NE–SW orientation in different periods. When the maximum principal compressive stress axis is oriented in the NE–SW direction, the pattern of the space distribution of the seismic events in the Shanxi tectonic belt shows a trend of their concentration in the N–S oriented tectonic segments. At the same time, the stress state is registered as horizontal shearing and horizontal extension in the N–S and NE–SW oriented local segments in turn. When the maximum principal compressive stress axis is NW–SE oriented, the stress state of the N–S and NE–SW oriented tectonic segments is primarily registered as horizontal shearing. Estimations of plunges of stress axes show that seismicity in the Shanxi belt  corresponds primarily to the activity of lowangle faults, and highangle stress sites are located in the NE–SW oriented extensional tectonic segments of the Shanxi belt. This indicates that the stress change of the Shanxi belt is

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

African Journals Online (AJOL)

Effect of insulin pump infusion on comprehensive stress state of patients with diabetic ketoacidosis. ... Relevant diabetes-associated serum indices, oxidative stress and stress hormone levels were compared between the ... from 32 Countries:.

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

Prediction of stress-strain state of municipal solid waste with application of soft soil creep model

Directory of Open Access Journals (Sweden)

Ofrikhter Vadim Grigor'evich

Full Text Available The deformation of municipal solid waste is a complex process caused by the nature of MSW, the properties of which differ from the properties of common soils. The mass of municipal solid waste shows the mixed behaviour partially similar to granular soils, and partially - to cohesive. So, one of mechanical characteristics of MSW is the cohesion typical to cohesive soils, but at the same time the filtration coefficient of MSW has an order of 1 m/day that is characteristic for granular soils. It has been established that MSW massif can be simulated like the soil reinforced by randomly oriented fibers. Today a significant amount of the verified and well proved software products are available for numerical modelling of soils. The majority of them use finite element method (FEM. The soft soil creep model (SSC-model seems to be the most suitable for modelling of municipal solid waste, as it allows estimating the development of settlements in time with separation of primary and secondary consolidation. Unlike the soft soil, one of the factors of secondary consolidation of MSW is biological degradation, the influence of which is possible to consider at the definition of the modified parameters essential for soft soil model. Application of soft soil creep model allows carrying out the calculation of stress-strain state of waste from the beginning of landfill filling up to any moment of time both during the period of operation and in postclosure period. The comparative calculation presented in the paper is executed in Plaxis software using the soft-soil creep model in contrast to the calculation using the composite model of MSW. All the characteristics for SSC-model were derived from the composite model. The comparative results demonstrate the advantage of SSC-model for prediction of the development of MSW stress-strain state. As far as after the completion of the biodegradation processes MSW behaviour is similar to cohesion-like soils, the demonstrated

Analysis of rock stress and rock stress measurements with application to Aespoe HRL

International Nuclear Information System (INIS)

Lundholm, Beatrice

2000-11-01

The process of choosing a site for a nuclear waste repository means that many aspects have to be taken into consideration. One of these is that the repository has to be mechanically stable for a long time. The mechanical stability of the rock is very difficult to determine. One of several factors, which determine the mechanical stability, is the virgin state of stress. The thesis project consists of two parts. In the first part the state of stress at Aespoe Hard Rock Laboratory had to be defined. This was done based on earlier rock stress measurements conducted during the years 1988 to 1997. Two different measurement techniques have been used, hydraulic fracturing and overcoring. During the overcoring two types of cells have been used, CSIRO HI-cell and a cell developed by the Swedish State Power Board (SSPB). In the second part of the project, investigation of the correlation between the stress and geological structures are made using numerical modelling tools such as FLAC, UDEC and 3DEC. The rock stress measurements using the hydraulic fracturing gave orientations of the horizontal stress that coincide with earlier hydraulic fracturing measurements conducted in Scandinavia. The magnitudes of rock stresses are slightly lower than the earlier reported stress magnitudes for the Scandinavian part of the earth crust. The rock stresses obtained from the overcoring resulted in higher stresses than what was predicted by the hydraulic fracturing measurements. However, the orientation of the maximum horizontal stresses coincides well between the two techniques. The orientation is also more or less constant with respect to increasing depth. The state of stress at Aespoe is defined by using the results from the hydraulic fracturing and the measurements conducted by SSPB-cell. The measurements from the SSPB-cell are used since these have a Poisson's ratio that corresponds well with the uniaxial tests of rock samples and since the measurements have been done at a distance from

Stress state dependence of transient irradiation creep in 20% cold worked 316 stainless steel

International Nuclear Information System (INIS)

Foster, J.P.; Gilbert, E.R.

1998-01-01

Irradiation creep tests were performed in fast reactors using the stress states of uniaxial tension, biaxial tension, bending and torsion. In order to compare the saturated transient strain irradiation creep component, the test data were converted to equivalent strain and equivalent stress. The saturated transient irradiation creep component was observed to depend on the stress state. The highest value was exhibited by the uniaxial tension stress state, and the lowest by the torsion stress state. The biaxial tension and bending stress state transient component values were intermediate. This behavior appears to be related to the dislocation or microscopic substructure resulting from fabrication processing and the applied stress direction. (orig.)

Measurements of the state of stress in deep drill holes

International Nuclear Information System (INIS)

Vaeaetaeinen, A.; Saerkkae, P.

1985-05-01

The state of stress in rock is one of the most important parameters in the safe planning of stable underground openings in rock. At the same time, it is very difficult to be determined from a great distance. The common methods for the determination of state of stress in bedrock are usually not able to do this from a distance over 30 m. This work is a survey on rock stress determination methods usable in deep, over 500 m, drill holes. It also contains a recommendation for a method to determine the state of stress in Lavia test hole. The presented recommendation for the measurement of the state of stress contains an estimation on the working time for the measurement as well as the amount and location of the measuring points. The examination of the methods has been concentrated on three methods, hydraulic fracturing, overcoring by Vattenfall and differential strain analysis. Theoretical background of these methods has been analyzed. A special interest has been laid on the fundamental assumptions of different methods and their influence on the reliability of the results and the interpretation of the state of stress. The comparison of the methods has been made by literature and user interviews. Equipment and personnel needed, and way of measurement are described for the methods. The parameters measured and their possible sources of errors are described, too, as well as the fundamental assumptions and potential difficulties in the measurement. The organizations in Scandinavia performing measurements and their abilities to do measurements and interpretation are presented. Readiness to interpretation in Finland is described shortly

Stress strain tensors with their application to x-ray stress measurement

International Nuclear Information System (INIS)

Kurita, Masanori

2015-01-01

This paper describes in detail the method of obtaining the formulas of stress-strain tensor that express the directional dependence of stress-strain, that is, how these values change in response to coordinate transformation, and clarifies the preconditions for supporting both formulas. The two conversion formulas are both the second order of tensor, and the formula of strain tensor not only does not use the relational expression of stress and strain at all, but also is obtained completely independently of the formula of stress tensor. Except for the condition that the strain is very small (elastic deformation) in the conversion formula of strain, both formulas unconditionally come into effect. In other words, both formulas hold true even in the isotropic elastic body or anisotropic elastic body. It was shown that the conversion formula of strain can be derived from the conversion formula of stress using the formula of Hooke for isotropic elastic body. From these three-dimensional expressions, the two-dimensional stress-strain coordinate conversion formula that is used for Mohr's stress-strain circle was derived. It was shown that these formulas hold true for three-dimensional stress condition with stress-strain components in the three-axial direction that are not plane stress nor plane strain condition. In addition, as an application case of this theory, two-dimensional and three-dimensional X-ray stress measurements that are effective for residual stress measurement were shown. (A.O.)

Effect of stress-state and spacing on voids in a shear-field

DEFF Research Database (Denmark)

Tvergaard, Viggo

2012-01-01

in the overall average stress state can be prescribed. This also allows for studies of the effect of different initial void spacing in the two in-plane coordinate directions. The stress states considered are essentially simple shear, with various levels of tensile stresses or compressive stresses superposed, i.......e. low positive stress triaxiality or even negative stress triaxiality. For high aspect ratio unit cells a clear localization band is found inside the cell, which actually represents several parallel bands, due to periodicity. In the materials represented by a low aspect ratio unit cell localization...

[Study on the relationship between occupational stress and psychological health state among oil workers].

Science.gov (United States)

Liu, Jiwen; Wang, Zhiming; Wang, Mianzhen; Lan, Yajia; Zhan, Chenglie; Zhao, Xiaoguo

2002-02-01

To study the relationship between occupational stress and psychological health state among oil workers. 1,230 oil workers in 122 work types of oil industry were selected and written occupational stress questionary(OSQ) and symptom check list (SCL-90). Petroleum workers' psychological health states were poor with increasing occupational stress degree. The scores in physical symptoms(1.87 +/- 0.80, 1.72 +/- 0.70), depression(1.74 +/- 0.76, 1.62 +/- 0.67), horror(1.48 +/- 0.65, 1.39 +/- 0.55) in the high and medium stress group were obviously higher than those in low stress group(1.55 +/- 0.61, 1.43 +/- 0.54, 1.28 +/- 0.46, respectively, P < 0.05). The score of mood state in the high and medium stress group was obviously higher than that in low stress group(P < 0.05). Psychological health states and mood state in the petroleum workers with short service length are significantly poorer than that with long service length(P < 0.01). Occupational stress should affect psychological health state of petroleum workers.

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.

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.

Probing Stress States in Silicon Nanowires During Electrochemical Lithiation Using In Situ Synchrotron X-Ray Microdiffraction

Directory of Open Access Journals (Sweden)

Imran Ali

2018-04-01

Full Text Available Silicon is considered as a promising anode material for the next-generation lithium-ion battery (LIB due to its high capacity at nanoscale. However, silicon expands up to 300% during lithiation, which induces high stresses and leads to fractures. To design silicon nanostructures that could minimize fracture, it is important to understand and characterize stress states in the silicon nanostructures during lithiation. Synchrotron X-ray microdiffraction has proven to be effective in revealing insights of mechanical stress and other mechanics considerations in small-scale crystalline structures used in many important technological applications, such as microelectronics, nanotechnology, and energy systems. In the present study, an in situ synchrotron X-ray microdiffraction experiment was conducted to elucidate the mechanical stress states during the first electrochemical cycle of lithiation in single-crystalline silicon nanowires (SiNWs in an LIB test cell. Morphological changes in the SiNWs at different levels of lithiation were also studied using scanning electron microscope (SEM. It was found from SEM observation that lithiation commenced predominantly at the top surface of SiNWs followed by further progression toward the bottom of the SiNWs gradually. The hydrostatic stress of the crystalline core of the SiNWs at different levels of electrochemical lithiation was determined using the in situ synchrotron X-ray microdiffraction technique. We found that the crystalline core of the SiNWs became highly compressive (up to -325.5 MPa once lithiation started. This finding helps unravel insights about mechanical stress states in the SiNWs during the electrochemical lithiation, which could potentially pave the path toward the fracture-free design of silicon nanostructure anode materials in the next-generation LIB.

Stress and Strain State Analysis of Defective Pipeline Portion

Science.gov (United States)

Burkov, P. V.; Burkova, S. P.; Knaub, S. A.

2015-09-01

The paper presents computer simulation results of the pipeline having defects in a welded joint. Autodesk Inventor software is used for simulation of the stress and strain state of the pipeline. Places of the possible failure and stress concentrators are predicted on the defective portion of the pipeline.

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

Abstract. 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 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...... 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....

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.

Phosphorus and humic acid application alleviate salinity stress of ...

African Journals Online (AJOL)

Phosphorus and humic acid application alleviate salinity stress of pepper seedling. ... It consequently affects plant growth and yield and ameliorates the deleterious effects of salt stress. The objective of the study ... from 32 Countries: Algeria (5) ...

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.

Defect-dependent elasticity: Nanoindentation as a probe of stress state

International Nuclear Information System (INIS)

Jarausch, K. F.; Kiely, J. D.; Houston, J. E.; Russell, P. E.

2000-01-01

Using an interfacial force microscope, the measured elastic response of 100-nm-thick Au films was found to be strongly correlated with the films' stress state and thermal history. Large, reversible variations (2x) of indentation modulus were recorded as a function of applied stress. Low-temperature annealing caused permanent changes in the films' measured elastic properties. The measured elastic response was also found to vary in close proximity to grain boundaries in thin films and near surface steps on single-crystal surfaces. These results demonstrate a complex interdependence of stress state, defect structure, and elastic properties in thin metallic films. (c) 2000 Materials Research Society

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.

State of charge estimation for lithium-ion pouch batteries based on stress measurement

International Nuclear Information System (INIS)

Dai, Haifeng; Yu, Chenchen; Wei, Xuezhe; Sun, Zechang

2017-01-01

State of charge (SOC) estimation is one of the important tasks of battery management system (BMS). Being different from other researches, a novel method of SOC estimation for pouch lithium-ion battery cells based on stress measurement is proposed. With a comprehensive experimental study, we find that, the stress of the battery during charge/discharge is composed of the static stress and the dynamic stress. The static stress, which is the measured stress in equilibrium state, corresponds to SOC, this phenomenon facilitates the design of our stress-based SOC estimation. The dynamic stress, on the other hand, is influenced by multiple factors including charge accumulation or depletion, current and historical operation, thus a multiple regression model of the dynamic stress is established. Based on the relationship between static stress and SOC, as well as the dynamic stress modeling, the SOC estimation method is founded. Experimental results show that the stress-based method performs well with a good accuracy, and this method offers a novel perspective for SOC estimation. - Highlights: • A State of Charge estimator based on stress measurement is proposed. • The stress during charge and discharge is investigated with comprehensive experiments. • Effects of SOC, current, and operation history on battery stress are well studied. • A multiple regression model of the dynamic stress is established.

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

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.

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...... 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......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

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

somewhat from the theoretical expectation. These deviations are found to originate from a larger tensile stress component than in the theoretical Bishop-Hill stress states and to be associated also with deviations from axisymmetric plastic strain. This conclusion was supported by finite-element crystal...

Selective buckling via states of self-stress in topological metamaterials.

Science.gov (United States)

Paulose, Jayson; Meeussen, Anne S; Vitelli, Vincenzo

2015-06-23

States of self-stress--tensions and compressions of structural elements that result in zero net forces--play an important role in determining the load-bearing ability of structures ranging from bridges to metamaterials with tunable mechanical properties. We exploit a class of recently introduced states of self-stress analogous to topological quantum states to sculpt localized buckling regions in the interior of periodic cellular metamaterials. Although the topological states of self-stress arise in the linear response of an idealized mechanical frame of harmonic springs connected by freely hinged joints, they leave a distinct signature in the nonlinear buckling behavior of a cellular material built out of elastic beams with rigid joints. The salient feature of these localized buckling regions is that they are indistinguishable from their surroundings as far as material parameters or connectivity of their constituent elements are concerned. Furthermore, they are robust against a wide range of structural perturbations. We demonstrate the effectiveness of this topological design through analytical and numerical calculations as well as buckling experiments performed on two- and three-dimensional metamaterials built out of stacked kagome lattices.

Stress state evaluation in low carbon and TRIP steels by magnetic permeability

International Nuclear Information System (INIS)

Kouli, M.-E.; Giannakis, M

2016-01-01

Magnetic permeability is an indicative factor for the steel health monitoring. The measurements of magnetic permeability lead to the evaluation of the stress state of any ferromagnetic steel. The magnetic permeability measurements were conducted on low carbon and TRIP steel samples, which were subjected to both tensile and compressive stresses. The results indicated a direct correlation of the magnetic permeability with the mechanical properties, the stress state and the microstructural features of the examined samples. (paper)

Stress-induced state transitions in flexible liquid-crystal devices

International Nuclear Information System (INIS)

Ho, I-Lin; Chang, Yia-Chung

2012-01-01

This work studies the stress-strain dynamics for the transient optoelectronic characteristics of flexible liquid-crystal (LC) devices. Due to the fast response of LC directors, the configuration of the LC is assumed to be in quasi-equilibrium during the process of elastic deformations of the flexible structures. The LC medium hence can be treated effectively as a thin-film layer and can approximately follow the strain-stress mechanism in the solids. Relevant theoretical algorithms are studied in this work, and numerical results present the stress-induced state transitions in the π cell.

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. 

Solid-state devices and applications

CERN Document Server

Lewis, Rhys

1971-01-01

Solid-State Devices and Applications is an introduction to the solid-state theory and its devices and applications. The book also presents a summary of all major solid-state devices available, their theory, manufacture, and main applications. The text is divided into three sections. The first part deals with the semiconductor theory and discusses the fundamentals of semiconductors; the kinds of diodes and techniques in their manufacture; the types and modes of operation of bipolar transistors; and the basic principles of unipolar transistors and their difference with bipolar transistors. The s

Simulation of Stress-Strain State of Shovel Rotary Support Kingpin

Science.gov (United States)

Khoreshok, A. A.; Buyankin, P. V.; Vorobiev, A. V.; Dronov, A. A.

2016-04-01

The article presents the sequence of computational simulation of stress-strain state of shovel’s rotary support. Computation results are analyzed, the kingpin is specified as the most loaded element, maximum stress zones are identified. Kingpin design modification such as enhancement of fillet curvature radius to 25 mm and displacement of eyebolt holes on the diameter of 165 mm are proposed, thus diminishing impact of stress concentrators and improving reliability of the rotary support.

Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

NARCIS (Netherlands)

Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

2015-01-01

A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

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.

Off-state stress and pulse response investigation of InAl/Ga HFET

International Nuclear Information System (INIS)

Florovic, M.; Hronec, P.; Kovac, J.; Skriniarova, J.; Donoval, D.; Kordos, P.

2011-01-01

In this study In 0.18 Al 0.82 N/GaN HFETs were off-state tested under high drain bias, I-V characteristics were measured using standard DC voltage source (drain-source, gate-source). Subsequently drain current responses on pulse gate-source voltage for various drain-source voltages were recorded and analysed. Static performance of InAlN/GaN HFETs with AlN buffer layer prepared at different conditions were analysed before, during and after the off-state stress. The static output I-V characteristics show the maximum drain current I d ≅ 0,44 A/mm for V gs = 6 V, the device has pinch-off at V gs - 4.4 V. The drain and gate currents of the InAlN/GaN HFET were measured continuously during the off-state stress (V ds = 30 V, V gs = -4.4 V), a partial increase of the drain/gate current was observed after this interruption, which indicates on some recovery effect. The devices were characterised in details after the total stress time of 60 min., as well as after 30 min without the stress, the output I-V characteristic show permanent off-state stress degradation. This effect will be studied in details in the next. (authors)

Exogenous application of hydrogen sulfide donor sodium hydrosulfide enhanced multiple abiotic stress tolerance in bermudagrass (Cynodon dactylon (L). Pers.).

Science.gov (United States)

Shi, Haitao; Ye, Tiantian; Chan, Zhulong

2013-10-01

As a gaseous molecule, hydrogen sulfide (H2S) has been recently found to be involved in plant responses to multiple abiotic stress. In this study, salt (150 and 300 mM NaCl), osmotic (15% and 30% PEG6000) and cold (4 °C) stress treatments induced accumulation of endogenous H2S level, indicating that H2S might play a role in bermudagrass responses to salt, osmotic and cold stresses. Exogenous application of H2S donor (sodium hydrosulfide, NaHS) conferred improved salt, osmotic and freezing stress tolerances in bermudagrass, which were evidenced by decreased electrolyte leakage and increased survival rate under stress conditions. Additionally, NaHS treatment alleviated the reactive oxygen species (ROS) burst and cell damage induced by abiotic stress, via modulating metabolisms of several antioxidant enzymes [catalase (CAT), peroxidase (POD) and GR (glutathione reductase)] and non-enzymatic glutathione antioxidant pool and redox state. Moreover, exogenous NaHS treatment led to accumulation of osmolytes (proline, sucrose and soluble total sugars) in stressed bermudagrass plants. Taken together, all these data indicated the protective roles of H2S in bermudagrass responses to salt, osmotic and freezing stresses, via activation of the antioxidant response and osmolyte accumulation. These findings might be applicable to grass and crop engineering to improve abiotic stress tolerance. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

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.

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.

Quantum state discrimination and its applications

International Nuclear Information System (INIS)

Bae, Joonwoo; Kwek, Leong-Chuan

2015-01-01

Quantum state discrimination underlies various applications in quantum information processing tasks. It essentially describes the distinguishability of quantum systems in different states, and the general process of extracting classical information from quantum systems. It is also useful in quantum information applications, such as the characterization of mutual information in cryptographic protocols, or as a technique for deriving fundamental theorems on quantum foundations. It has deep connections to physical principles such as relativistic causality. Quantum state discrimination traces a long history of several decades, starting with the early attempts to formalize information processing of physical systems such as optical communication with photons. Nevertheless, in most cases, the problems of finding optimal strategies of quantum state discrimination remain unsolved, and related applications are valid in some limited cases only. The present review aims to provide an overview on quantum state discrimination, covering some recent progress, and addressing applications in some selected areas. This review serves to strengthen the link between results in quantum state discrimination and quantum information applications, by showing the ways in which the fundamental results are exploited in applications and vice versa. (topical review)

15 CFR Notes Applicable to State... - Notes applicable to State of Understanding related to Medical Equipment:

Science.gov (United States)

2010-01-01

... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Notes applicable to State of Understanding related to Medical Equipment: applicable Notes applicable to State of Understanding related to Medical Equipment: Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade (Continued) BUREAU OF INDUSTRY AND SECURITY,...

Application of x-ray residual stress measurement to products

International Nuclear Information System (INIS)

Goto, T.; Iwamura, T.

1975-01-01

The X-ray residual stress measuring method is the only nondestructive method for measuring residual stress in polycrystalline materials. It is capable of obtaining information not only on macroscopic stress but also microscopic stress. The authors are employing this method for the development of pre-service and in-service inspection methods and for the improvement of various manufacturing techniques. In this paper, the results of measurement of some products as examples of its application are described. The examples introduced concern the following: (1) Selection of optimum conditions in heat treatment and stress-relief treatment. (2) Residual stress produced by mechanical processes such as autofrettage and flow form. (3) Check of manufacturing processes of rotary shaft and welded parts. (4) Estimation of fatigue strength of shot-peened part. (5) Detection of fatigue damage of shot-peened part. (auth.)

Specific strain work as a failure criterion in plane stress state

International Nuclear Information System (INIS)

Zuchowski, R.; Zietkowski, L.

1985-01-01

An experimental verification of failure criterion based on specific strain work was performed. Thin-walled cylindrical specimens were examined by loading with constant force and constant torque moment, assuming different values for particular tests, at the same time keeping stress intensity constant, and by subjecting to thermal cycling. It was found that the critical value of failure did not depend on axial-to-shearing stresses ratio, i.e., on the type of state of stress. Thereby, the validity of the analysed failure criterion in plane stress was confirmed. Besides, a simple description of damage development in plane stress was suggested. (orig./RF)

Highly stressed carbon film coatings on silicon potential applications

CERN Multimedia

Sharda, T

2002-01-01

The fabrication of highly stressed and strongly adhered nanocrystalline diamond films on Si substrates is presented. A microwave plasma CVD method with controlled and continuous bias current density was used to grow the films. The stress/curvature of the films can be varied and controlled by altering the BCD. Potential applications for these films include particle physics and x-ray optics.

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.

Fracture criteria of reactor graphite under multiaxial stresses

International Nuclear Information System (INIS)

Sato, S.; Kawamata, K.; Kurumada, A.; Oku, T.

1987-01-01

New fracture criteria for graphite under multiaxial stresses are presented for designing core and support materials of a high temperature gas cooled reactor. Different kinds of fracture strength tests are carried out for a near isotropic graphite IG-11. Results show that, under the stress state in which tensile stresses are predominant, the maximum principal stress theory is seen as applicable for brittle fracture. Under the stress state in which compressive stresses are predominant there may be two fracture modes for brittle fracture, namely, slipping fracture and mode II fracture. For the former fracture mode the maximum shear stress criterion is suitable, but for the latter fracture mode a new mode II fracture criterion including a restraint effect for cracks is verified to be applicable. Also a statistical correction for brittle fracture criteria under multiaxial stresses is discussed. By considering the allowable stress values for safe design, the specified minimum ultimate strengths corresponding to a survival probability of 99% at the 95% confidence level are presented. (orig./HP)

Methods for FEM stress initialization based on stress functions, and application to a reservoir cross-section

OpenAIRE

Aliguer Piferrer, Ignasi; Rafels Ybern, Carles; Jaqués Adell, Irene; Carol, Ignacio; Prat Catalán, Pere; Lakashmikhanta, Ramasesha; Segura Segarra, José María

2013-01-01

An accurate description of the in-situ stress field in a rock mass is crucial in different areas of geo-engineering such as: underground excavations, hydrocarbon extraction, CO2 storage, hydraulic fracture etc. In this paper, a novel methodology to numerically generate the in-situ stress state within the Finite Elements framework is presented. It involves two steps: 1) an estimate of the stress components is given for integration point of the discretization, and 2) global equilibrium is verif...

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

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.

High-resolution stress measurements for microsystem and semiconductor applications

Science.gov (United States)

Vogel, Dietmar; Keller, Juergen; Michel, Bernd

2006-04-01

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

Experimental research data on stress state of salt rock mass around an underground excavation

Science.gov (United States)

Baryshnikov, VD; Baryshnikov, DV

2018-03-01

The paper presents the experimental stress state data obtained in surrounding salt rock mass around an excavation in Mir Mine, ALROSA. The deformation characteristics and the values of stresses in the adjacent rock mass are determined. Using the method of drilling a pair of parallel holes in a stressed area, the authors construct linear relationship for the radial displacements of the stress measurement hole boundaries under the short-term loading of the perturbing hole. The resultant elasticity moduli of rocks are comparable with the laboratory core test data. Pre-estimates of actual stresses point at the presence of a plasticity zone in the vicinity of the underground excavation. The stress state behavior at a distance from the excavation boundary disagrees with the Dinnik–Geim hypothesis.

Influence of Health Behaviors and Occupational Stress on Prediabetic State among Male Office Workers.

Science.gov (United States)

Ryu, Hosihn; Moon, Jihyeon; Jung, Jiyeon

2018-06-14

This study examined the influence of health behaviors and occupational stress on the prediabetic state of male office workers, and identified related risks and influencing factors. The study used a cross-sectional design and performed an integrative analysis on data from regular health checkups, health questionnaires, and a health behavior-related survey of employees of a company, using Spearman’s correlation coefficients and multiple logistic regression analysis. The results showed significant relationships of prediabetic state with health behaviors and occupational stress. Among health behaviors, a diet without vegetables and fruits (Odds Ratio (OR) = 3.74, 95% Confidence Interval (CI) = 1.93⁻7.66) was associated with a high risk of prediabetic state. In the subscales on occupational stress, organizational system in the 4th quartile (OR = 4.83, 95% CI = 2.40⁻9.70) was significantly associated with an increased likelihood of prediabetic state. To identify influencing factors of prediabetic state, the multiple logistic regression was performed using regression models. The results showed that dietary habits (β = 1.20, p = 0.002), total occupational stress score (β = 1.33, p = 0.024), and organizational system (β = 1.13, p = 0.009) were significant influencing factors. The present findings indicate that active interventions are needed at workplace for the systematic and comprehensive management of health behaviors and occupational stress that influence prediabetic state of office workers.

Global Stress Classification System for Materials Used in Solar Energy Applications

Science.gov (United States)

Slamova, Karolina; Schill, Christian; Herrmann, Jan; Datta, Pawan; Chih Wang, Chien

2016-08-01

Depending on the geographical location, the individual or combined impact of environmental stress factors and corresponding performance losses for solar applications varies significantly. Therefore, as a strategy to reduce investment risks and operating and maintenance costs, it is necessary to adapt the materials and components of solar energy systems specifically to regional environmental conditions. The project «GloBe Solar» supports this strategy by focusing on the development of a global stress classification system for materials in solar energy applications. The aim of this classification system is to assist in the identification of the individual stress conditions for every location on the earth's surface. The stress classification system could serve as a decision support tool for the industry (manufacturers, investors, lenders and project developers) and help to improve knowledge and services that can provide higher confidence to solar power systems.

EVALUATION OF STRAIN-STRESS STATE OF THE RAILS IN THE PRODUCTION

Directory of Open Access Journals (Sweden)

V. V. Muravev

2017-01-01

Full Text Available High values of residual stresses is one of the most common reason of breaking lots of metal constructions, including rails. These stresses can reach values of flow limit, especially in the area of faults. Estimation of residual stresses values allows to get information about technical condition of the rail and also allow to avoid abnormal situations So, the aim of the research is creating the model of stress-strain state of the rail, which was hardened in its top and bottom, and to compare modeling results with experimental measurements of stresses and discrepancy of the housing.For creating the model and making evaluations by finite element method we used a program COMSOL. Forces on the top and bottom of the rail cause tension stresses, forces on the web of the rail cause tensile stresses. We compared calculated values of stresses with discrepancy of the housing. The discrepancy of the housing is informative characteristic for estimating the residual stresses according to standards. For experimental measurements we used an acoustic structuroscope SEMA. This structuroscope uses the acoustoelastic phenomenon for measurements. We made measurements of the five rails.According to the calculation results of the model, critical discrepancy of the housing in 2 mm corresponded to the following values of maximum stresses: –54 MPa in the top of the rail, 86 MPa in the web and –62 MPa in the bottom of the rail. Experimental measurements are the following: from –48 MPa to – 64 MPa in the top of the rail, 54 MPa to 93 MPa in the web of the rail, and –59 MPA to –74 MPa in the bottom of the rail. Absolute error was ±5 MPa.Thus we created the model, which allowed to analyze strain-stress state and compare real values of stresses with discrepancy of the housing. Results of the modeling showed coincidence with structure of distribution of residual stresses in five probes of rails. 

28 CFR 104.42 - Applicable state law.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Applicable state law. 104.42 Section 104... OF 2001 Amount of Compensation for Eligible Claimants. § 104.42 Applicable state law. The phrase “to the extent recovery for such loss is allowed under applicable state law,” as used in the statute's...

Solid state chemistry and its applications

CERN Document Server

West, Anthony R

2013-01-01

Solid State Chemistry and its Applications, 2nd Edition: Student Edition is an extensive update and sequel to the bestselling textbook Basic Solid State Chemistry, the classic text for undergraduate teaching in solid state chemistry worldwide. Solid state chemistry lies at the heart of many significant scientific advances from recent decades, including the discovery of high-temperature superconductors, new forms of carbon and countless other developments in the synthesis, characterisation and applications of inorganic materials. Looking forward, solid state chemistry will be crucial for the

Effect of potassium application in drought-stressed tobacco (Nicotiana rustica L. plants: Comparison of root with foliar application

Directory of Open Access Journals (Sweden)

Sara Bahrami-Rad

2017-12-01

Full Text Available Effect of potassium (K application through leaves (LA or roots (RA was studied in tobacco plants grown under K deficiency and drought stress conditions. Application of K was effective in improving the shoot growth only under drought conditions, whereas root biomass and length responded under both watering regimes. Under drought conditions, photosynthesis and transpiration activities increased upon K application leading to a reduced water use efficiency. Both RA and LA increased the leaf water potential, relative water content and turgor under both well-watered and drought conditions; RA was more effective than LA in the recovery of leaf turgor. Analyses of water relation parameters in different aged leaves showed lower susceptibility of the middle-aged leaves to both K deficiency and drought stresses than the upper and lower leaves; this phenomenon was accompanied by a more conservative control of water loss in the middle-aged leaves. In contrast, proline was accumulated in the young leaves, and K application increased it further. Although various organic osmolytes were accumulated under the combinative effect of K deficiency and drought stress, they did not exceed the amounts found in the control (well-watered +K plants and were merely a result of the concentration effect. Collectively, our results revealed that the majority of leaf biochemical responses to drought stress are developmentally regulated processes. In addition, the alleviating effect of both RA and LA despite higher water loss indicated that an improved stomatal function upon K application allowed carbohydrates synthesis, thus, enhancing plant growth under water stress.

Analysis of residual stress state in sheet metal parts processed by single point incremental forming

Science.gov (United States)

Maaß, F.; Gies, S.; Dobecki, M.; Brömmelhoff, K.; Tekkaya, A. E.; Reimers, W.

2018-05-01

The mechanical properties of formed metal components are highly affected by the prevailing residual stress state. A selective induction of residual compressive stresses in the component, can improve the product properties such as the fatigue strength. By means of single point incremental forming (SPIF), the residual stress state can be influenced by adjusting the process parameters during the manufacturing process. To achieve a fundamental understanding of the residual stress formation caused by the SPIF process, a valid numerical process model is essential. Within the scope of this paper the significance of kinematic hardening effects on the determined residual stress state is presented based on numerical simulations. The effect of the unclamping step after the manufacturing process is also analyzed. An average deviation of the residual stress amplitudes in the clamped and unclamped condition of 18 % reveals, that the unclamping step needs to be considered to reach a high numerical prediction quality.

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.

Equation of limiting plasticity of the metal upon complex stress state

International Nuclear Information System (INIS)

Tin'gaev, A.K.

2002-01-01

A method for evaluation of the limiting plasticity of the metal in the zones of complex 3D stress state is presented. An analytic equation is derived for limiting plasticity. Parameters of the equation are expresses through the standard characteristics of the mechanical properties determined upon static tension of the smooth sample. Introduced into the obtained analytical equation is a universal fracture constant which indirectly characterizes the state of the material from the point of view of its capacity for elastic overstrain relaxation in the form of plastic flow or fracture. The new equation makes it possible to estimate the limiting plasticity of the metal in a state of complex stress on the basis of traditional characteristics of mechanical properties, which are not difficult to determine [ru

Cellular stress induces a protective sleep-like state in C. elegans.

Science.gov (United States)

Hill, Andrew J; Mansfield, Richard; Lopez, Jessie M N G; Raizen, David M; Van Buskirk, Cheryl

2014-10-20

Sleep is recognized to be ancient in origin, with vertebrates and invertebrates experiencing behaviorally quiescent states that are regulated by conserved genetic mechanisms. Despite its conservation throughout phylogeny, the function of sleep remains debated. Hypotheses for the purpose of sleep include nervous-system-specific functions such as modulation of synaptic strength and clearance of metabolites from the brain, as well as more generalized cellular functions such as energy conservation and macromolecule biosynthesis. These models are supported by the identification of synaptic and metabolic processes that are perturbed during prolonged wakefulness. It remains to be seen whether perturbations of cellular homeostasis in turn drive sleep. Here we show that under conditions of cellular stress, including noxious heat, cold, hypertonicity, and tissue damage, the nematode Caenorhabditis elegans engages a behavioral quiescence program. The stress-induced quiescent state displays properties of sleep and is dependent on the ALA neuron, which mediates the conserved soporific effect of epidermal growth factor (EGF) ligand overexpression. We characterize heat-induced quiescence in detail and show that it is indeed dependent on components of EGF signaling, providing physiological relevance to the behavioral effects of EGF family ligands. We find that after noxious heat exposure, quiescence-defective animals show elevated expression of cellular stress reporter genes and are impaired for survival, demonstrating the benefit of stress-induced behavioral quiescence. These data provide evidence that cellular stress can induce a protective sleep-like state in C. elegans and suggest that a deeply conserved function of sleep is to mitigate disruptions of cellular homeostasis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Deciphering Stress State of Seismogenic Faults in Oklahoma and Kansas Based on High-resolution Stress Maps

Science.gov (United States)

Qin, Y.; Chen, X.; Haffener, J.; Trugman, D. T.; Carpenter, B.; Reches, Z.

2017-12-01

Induced seismicity in Oklahoma and Kansas delineates clear fault trends. It is assumed that fluid injection reactivates faults which are optimally oriented relative to the regional tectonic stress field. We utilized recently improved earthquake locations and more complete focal mechanism catalogs to quantitatively analyze the stress state of seismogenic faults with high-resolution stress maps. The steps of analysis are: (1) Mapping the faults by clustering seismicity using a nearest-neighbor approach, manually picking the fault in each cluster and calculating the fault geometry using principal component analysis. (2) Running a stress inversion with 0.2° grid spacing to produce an in-situ stress map. (3) The fault stress state is determined from fault geometry and a 3D Mohr circle. The parameter `understress' is calculated to quantify the criticalness of these faults. If it approaches 0, the fault is critically stressed; while understress=1 means there is no shear stress on the fault. Our results indicate that most of the active faults have a planar shape (planarity>0.8), and dip steeply (dip>70°). The fault trends are distributed mainly in conjugate set ranges of [50°,70°] and [100°,120°]. More importantly, these conjugate trends are consistent with mapped basement fractures in southern Oklahoma, suggesting similar basement features from regional tectonics. The fault length data shows a loglinear relationship with the maximum earthquake magnitude with an expected maximum magnitude range from 3.2 to 4.4 for most seismogenic faults. Based on 3D local Mohr circle, we find that 61% of the faults have low understress (0.5) are located within highest-rate injection zones and therefore are likely to be influenced by high pore pressure. The faults that hosted the largest earthquakes, M5.7 Prague and M5.8 Pawnee are critically stressed (understress 0.2). These differences may help in understanding earthquake sequences, for example, the predominantly aftershock

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.

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…

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).

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

International Nuclear Information System (INIS)

Damjanovic, Darko; Kozak, Drazan; Marsoner, Stefan; Gubeljak, Nenad

2017-01-01

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).

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.

Stress evaluation of metallic material under steady state based on nonlinear critically refracted longitudinal wave

Science.gov (United States)

Mao, Hanling; Zhang, Yuhua; Mao, Hanying; Li, Xinxin; Huang, Zhenfeng

2018-06-01

This paper presents the study of applying the nonlinear ultrasonic wave to evaluate the stress state of metallic materials under steady state. The pre-stress loading method is applied to guarantee components with steady stress. Three kinds of nonlinear ultrasonic experiments based on critically refracted longitudinal wave are conducted on components which the critically refracted longitudinal wave propagates along x, x1 and x2 direction. Experimental results indicate the second and third order relative nonlinear coefficients monotonically increase with stress, and the normalized relationship is consistent with simplified dislocation models, which indicates the experimental result is logical. The combined ultrasonic nonlinear parameter is proposed, and three stress evaluation models at x direction are established based on three ultrasonic nonlinear parameters, which the estimation error is below 5%. Then two stress detection models at x1 and x2 direction are built based on combined ultrasonic nonlinear parameter, the stress synthesis method is applied to calculate the magnitude and direction of principal stress. The results show the prediction error is within 5% and the angle deviation is within 1.5°. Therefore the nonlinear ultrasonic technique based on LCR wave could be applied to nondestructively evaluate the stress of metallic materials under steady state which the magnitude and direction are included.

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…

From point-wise stress data to a continuous description of the 3D crustal in situ stress state

Science.gov (United States)

Heidbach, O.; Ziegler, M.; Reiter, K.; Hergert, T.

2017-12-01

The in situ stress is a key parameter for the safe and sustainable management of geo-reservoirs or storage of waste and energy in deep geological repositories. It is also an essential initial condition for thermo-hydro-mechanical (THM) models that investigate man-made induced processes e.g. seismicity due to fluid injection/extraction, reservoir depletion or storage of heat producing high-level radioactive waste. Without a reasonable assumption on the initial stress condition it is not possible to assess if a man-made process is pushing the system into a critical state or not. However, modelling the initial 3D stress state on reservoir scale is challenging since data are hardly available before drilling in the area of interest. This is in particular the case for the stress magnitude data which are a prerequisite for a reliable model calibration. Here, we present a multi-stage 3D geomechani­cal-numerical model approach to estimate for a reservoir-scale volume the 3D in situ stress state. First, we set up a large-scale model which is calibrated by stress data and use the modelled stress field subsequently to calibrate a small-scale model located within the large-scale model. The local model contains a significantly higher resolution representation of the subsurface geometry around boreholes of a projected geothermal power plant. This approach incorporates two models and is an alternative to the required trade-off between resolution, computational cost and calibration data which is inevitable for a single model; an extension to a three-stage approach would be straight forward. We exemplify the two-stage approach for the area around Munich in the German Molasse Basin. The results of the reservoir-scale model are presented in terms of values for slip tendency as a measure for the criticality of fault reactivation. The model results show that variations due to uncertainties in the input data are mainly introduced by the uncertain material properties and missing

Emotional states as mediators between tinnitus loudness and tinnitus distress in daily life: Results from the “TrackYourTinnitus” application

Science.gov (United States)

Probst, Thomas; Pryss, Rüdiger; Langguth, Berthold; Schlee, Winfried

2016-01-01

The psychological process how tinnitus loudness leads to tinnitus distress remains unclear. This cross-sectional study investigated the mediating role of the emotional state “stress level” and of the two components of the emotional state “arousal” and “valence” with N = 658 users of the “TrackYourTinnitus” smartphone application. Stress mediated the relationship between tinnitus loudness and tinnitus distress in a simple mediation model and even in a multiple mediation model when arousal and valence were held constant. Arousal mediated the loudness-distress relationship when holding valence constant, but not anymore when controlling for valence as well as for stress. Valence functioned as a mediator when controlling for arousal and even when holding arousal and stress constant. The direct effect of tinnitus loudness on tinnitus distress remained significant in all models. This study demonstrates that emotional states affect the process how tinnitus loudness leads to tinnitus distress. We thereby could show that the mediating influence of emotional valence is at least equally strong as the influence of stress. Implications of the findings for future research, assessment, and clinical management of tinnitus are discussed. PMID:26853815

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.)

Effect of Stress State on Fracture Features

Science.gov (United States)

Das, Arpan

2018-02-01

Present article comprehensively explores the influence of specimen thickness on the quantitative estimates of different ductile fractographic features in two dimensions, correlating tensile properties of a reactor pressure vessel steel tested under ambient temperature where the initial crystallographic texture, inclusion content, and their distribution are kept unaltered. It has been investigated that the changes in tensile fracture morphology of these steels are directly attributable to the resulting stress-state history under tension for given specimen dimensions.

Thick and low-stress PECVD amorphous silicon for MEMS applications

International Nuclear Information System (INIS)

Iliescu, Ciprian; Chen Bangtao

2008-01-01

This paper presents a solution for the deposition of thick amorphous silicon (α-Si:H) in PECVD reactors for MEMS applications, such as sacrificial layer or mask layer for dry or wet etching of glass. This achievement was possible by tuning the deposition parameters to a 'zero' value of the residual stress in the α-Si:H layer. The influence of the process parameters, such as power, frequency mode, temperature, pressure and SiH 4 /Ar flow rates for tuning the residual stress and for a good deposition rate is analyzed. The deposition of low-stress and thick (more than 12 µm in our case) α-Si:H layers was possible without generation of hillock defects (previously reported in literature for layers thicker then 2 µm). Finally, the paper presents some MEMS applications of such a deposited α-Si:H layer: masking layer for deep wet etching as well as dry etching of glass, and sacrificial layer for dry or wet release

Relationship of Challenge and Hindrance Stress with Coping Style and Job Satisfaction in Chinese State-Owned Enterprises

OpenAIRE

Yamaguchi, Hiroyuki; Zhao, Dong Mei

2008-01-01

This study aimed to categorize stresses prevalent in Chinese state-owned enterprises and to investigate the relationships among stresses, coping styles and job satisfaction. Data ( n = 549) were collected from three state-owned enterprises in Cang Zhou, He Bei Province, Mainland China. The result of a factor analysis yielded the following three factors: enterprise stress, interpersonal stress, and challenge stress. In order to test the moderator effect of problem-focused coping and emotion-fo...

Modified stress intensity factor as a crack growth parameter applicable under large scale yielding conditions

International Nuclear Information System (INIS)

Yasuoka, Tetsuo; Mizutani, Yoshihiro; Todoroki, Akira

2014-01-01

High-temperature water stress corrosion cracking has high tensile stress sensitivity, and its growth rate has been evaluated using the stress intensity factor, which is a linear fracture mechanics parameter. Stress corrosion cracking mainly occurs and propagates around welded metals or heat-affected zones. These regions have complex residual stress distributions and yield strength distributions because of input heat effects. The authors previously reported that the stress intensity factor becomes inapplicable when steep residual stress distributions or yield strength distributions occur along the crack propagation path, because small-scale yielding conditions deviate around those distributions. Here, when the stress intensity factor is modified by considering these distributions, the modified stress intensity factor may be used for crack growth evaluation for large-scale yielding. The authors previously proposed a modified stress intensity factor incorporating the stress distribution or yield strength distribution in front of the crack using the rate of change of stress intensity factor and yield strength. However, the applicable range of modified stress intensity factor for large-scale yielding was not clarified. In this study, the range was analytically investigated by comparison with the J-integral solution. A three-point bending specimen with parallel surface crack was adopted as the analytical model and the stress intensity factor, modified stress intensity factor and equivalent stress intensity factor derived from the J-integral were calculated and compared under large-scale yielding conditions. The modified stress intensity was closer to the equivalent stress intensity factor when compared with the stress intensity factor. If deviation from the J-integral solution is acceptable up to 2%, the modified stress intensity factor is applicable up to 30% of the J-integral limit, while the stress intensity factor is applicable up to 10%. These results showed that

APPLICATION OF COMPUTER SIMULATION IN THE EVALUATION OF THE STRESS-STRAIN STATE OF LOAD-BEARING STRUCTURES OF BUILDINGS MASONRY

Directory of Open Access Journals (Sweden)

Anatoliy I. Bedov

2017-03-01

Full Text Available The results of studies on the analysis of the stress-strain state of the structures of bearing walls of high-hollow pottery. The way of modeling masonry finite element method. The experimental study of masonry structures produced in the Republic of Bashkortostan high-hollow pottery, set the nature of their work load, the mechanism of destruction. The results of the comparative evaluation of the calculations in the software package and the traditional “manual” calculation.

Giant magneto-impedance and stress-impedance effects of microwire composites for sensing applications

Science.gov (United States)

Qin, F. X.; Peng, H. X.; Popov, V. V.; Phan, M. H.

2011-02-01

Composites consisting of glass-coated amorphous microwire Co 68.59Fe 4.84Si 12.41B 14.16 and 913 E-glass prepregs were designed and fabricated. The influences of tensile stress, annealing and number of composite layers on the giant magneto-impedance (GMI) and giant stress-impedance (GSI) effects in these composites were investigated systematically. It was found that the application of tensile stress along the microwire axis or an increase in the number of composite layers reduced the GMI effect and increased the circular anisotropy field, while the annealing treatment had a reverse effect. The value of matrix-wire interfacial stress calculated via the GMI profiles coincided with the value of the applied effective tensile stress to yield similar GMI profiles. Enhancement of the GSI effect was achieved in the composites relative to their single microwire inclusion. These findings are important for the development of functional microwire-based composites for magnetic- and stress-sensing applications. They also open up a new route for probing the interfacial stress in fibre-reinforced polymer (FRP) composites.

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.

Influence of thyroid states on stress gastric ulcer formation

International Nuclear Information System (INIS)

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 4 ) were significantly elevated in hyperthyroid rats, and undetectable in hypothyroid rats. Acute pretreatment with i.p. cimetidine, but not T 4 1 h prior to stress completely prevented gastric lesions formation in hypothyroid rats. Finally, binding of 3 H-dihydroalprenolol to β-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

Investigations on the influence of the stress state on fracture-mechanical values

International Nuclear Information System (INIS)

Schmidt, P.

1979-01-01

Fracture toughness obtained from specimen can be applied to construction elements only when the same stress state exists. In standardised fracture-mechanical tests plain strain is realised. Using the stress intensity factor, a critical crack length or a critical load can be obtained. Above these values a crack propagates in an unstable way. The specimen are tested under uni-axial load. In this paper investigations have been made whether a biaxial load increases the stress state over the plain strain and whether consequently a decrease of the critical fracture toughness and a shift of the temperatures Tsub(g)sub(y) and Tsub(s) results which characterise the fracture behaviour of steel. In order to answer these questions the tests were made which induced due to their geometry an additional nominal stress parallel to the crack front in spite of uni-axial loading. The results were compared with those from specimen without an additional nominal stress and having in their cross section under same test conditions nearly the same plain strain. The fracture toughness of both specimen types were compared at temperatures between 142 K and 252 K and correlated to other material-characterising values. The tests were completed by stress analysis and by comparing the crack opening displacement. Due to the additional stress, Tsub(g)sub(y) was found to be 20 K higher than for the reference specimen. The fracture toughness decreases significantly in certain temperature ranges. The plastic stress concentration factor was comperatively higher and the remaining plastic crack opening decreases up to 25%. (orig.) [de

The application of fracture mechanics in thermally stressed structures

International Nuclear Information System (INIS)

Cesari, F.; Maitan, A.; Hellen, T.K.

1981-03-01

There is considerable interest in calculating stress intensity factors at crack tips in thermally stressed structures, particularly in the power generation industry where the safe operation of both conventional and nuclear plant is founded on rigorous safety cases. Analytical methods to study such problems are of limited scope, although they can be extended by introducing numerical techniques. Purpose built numerical methods, however, offer a much greater and more accurate solution capability and in particular the finite element method is well advanced. Such methods are described, including how stress intensity factors can be obtained from the finite element results. They are then applied to a range of thermally stressed problems including plates with central cracks and cylinders with axial and circumferential cracks. Both steady state and transient temperature distributions arising from typical thermal shocks are considered. (author)

Residual Stress Analysis for Engineering Applications by Means of Neutron Diffraction

International Nuclear Information System (INIS)

Gndupel-Herold, Thomas; Brand, Paul C.; Prask, Henry J.

1999-01-01

The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. Recently, a dedicated state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated are residual stresses in rails, weldments, and plasma-sprayed coatings

Modeling stress/strain-dependent permeability changes for deep geoenergy applications

Science.gov (United States)

Rinaldi, Antonio Pio; Rutqvist, Jonny

2016-04-01

Rock permeability is a key parameter in deep geoenergy systems. Stress and strain changes induced at depth by fluid injection or extraction may substantially alter the rock permeability in an irreversible way. With regard to the geoenergies, some applications require the permeability to be enhanced to improve productivity. The rock permeability is generally enhanced by shearing process of faults and fractures (e.g. hydroshearing for Enhanced and Deep Geothermal Systems), or the creation of new fractures (e.g. hydrofracturing for shale gas). However, such processes may, at the same time, produce seismicity that can be felt by the local population. Moreover, the increased permeability due to fault reactivation may pose at risk the sealing capacity of a storage site (e.g. carbon sequestration or nuclear waste disposal), providing then a preferential pathway for the stored fluids to escape at shallow depth. In this work we present a review of some recent applications aimed at understanding the coupling between stress (or strain) and permeability. Examples of geoenergy applications include both EGS and CO2 sequestration. To investigate both "wanted" and "unwanted" effects, THM simulations have been carried out with the TOUGH-FLAC simulator. Our studies include constitutive equations relating the permeability to mean effective stress, effective normal stress, volumetric strain, as well as accounting for permeability variation as related to fault/fracture reactivation. Results show that the geomechanical effects have a large role in changing the permeability, hence affecting fluids leakage, reservoir enhancement, as well as the induced seismicity.

Sources and effects of work-related stress among employees in foreign-owned manufacturing companies in Ogun state, Nigeria

Directory of Open Access Journals (Sweden)

Ajibade David

2016-12-01

Full Text Available This study investigates the sources and effects of work-related stress among employees in foreign owned manufacturing companies in Ogun State, Nigeria. The study used cross sectional descriptive design and a total of three hundred and two (302 respondents were selected using stratified random sampling technique from five randomly selected foreign-owned manufacturing companies. Data were collected using questionnaire and statistically analysed using frequencies, percentages and weighted means. The study reveals factors such as unfavourable physical working conditions, job insecurity, poor career development, and long working hours fostering stress on employees in the sampled companies. The study further reveals that respondents suffered consequences such as restlessness, anxiety and nervous indigestion, headache, neck ache, and inability to concentrate. This study however has implication for management of foreign-owned manufacturing organization. Based on this, appropriate recommendations were made application of which will help to ensure enabling workplace environment and thus reduce the effects of stress on employees.

Effect of uniaxial stress on the acceptor ground state and on the hopping conduction in p-type germanium and silicon

International Nuclear Information System (INIS)

Buczko, R.; Chroboczek, J.A.

1983-08-01

We constructed variational wave functions, with correct asymptotic behaviour, for the ground state of shallow acceptors in Ge and Si, utilizing the spherical tensor representation of the effective mass hamiltonian of Baldereschi and Lipari (1973), at uniaxial stress, X, resulting from the application of a tensile or compressive force along the [001] orientation (respectively X 0). Energies of the components of the ground state, computed variationally, account very well for the X-induced displacements of the binding energies and the stress splitting of shallow acceptors in both Ge and Si, at X>0 (no data for X 0. However, they account only qualitatively for the rho(X) data available for Si (X>0 only), probably because of a larger chemical shift of the acceptor ground state in Si and its possible variation with X. At larger acceptor concentrations rho(X) decreases, at large X, much stronger than predicted for both Ge and Si. We attribute this discrepancy to the increase of the contribution to electron transport of multiple hopping transitions at large X values. (author)

Failure of Sierra White granite under general states of stress

Science.gov (United States)

Ingraham, M. D.; Dewers, T. A.; Lee, M.; Holdman, O.; Cheung, C.; Haimson, B. C.

2017-12-01

The effect of the intermediate principal stress on the failure of Sierra White granite was investigated by performing tests under true triaxial states of stress. Tests were performed under constant Lode angle conditions with Lode angles ranging from 0 to 30°, pure shear to axisymmetric compression. Results show that the failure of Sierra White granite is heavily dependent on the intermediate principal stress which became more dramatic as the mean stress increased. An analysis of the shear bands formed at failure was performed using an associated flow rule and the Rudnicki and Rice (1975) localization criteria. The localization analysis showed excellent agreement with experimental results. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

20 CFR 617.16 - Applicable State law.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Applicable State law. 617.16 Section 617.16... law. (a) What law governs. The applicable State law for any individual, for all of the purposes of this part 617, is the State law of the State— (1) In which the individual is entitled to UI (whether or...

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.

Compressive residual stresses as a preventive measure against stress corrosion cracking on turbine components

International Nuclear Information System (INIS)

Berger, C.; Ewald, J.; Fischer, K.; Gruendler, O.; Potthast, E.; Stuecker, E.; Winzen, G.

1987-01-01

Disk type low pressure turbine rotors have been designed for a large variety of power plant applications. Developing disk type rotors required a concerted effort to design a shaft/disk shrink fit with a minimum of tensile stress concentrations in order to aim for the lowest possible susceptibility to corrosive attack, i.e. stress corrosion cracking. As a result of stresses, the regions of greatest concern are the shrink fit boundaries and the keyways of turbine disks. These stresses are caused by service loading, i.e. centrifugal and shrinkage stresses and by manufacturing procedure, i.e. residual stresses. The compressive residual stresses partly compensate the tensile service stresses so that an increase of compressive residual stresses decreases the whole stress state of the component. Special manufacturing procedures, e.g. accelerated cooling after tempering can induce compressive residual stresses up to about 400 MPa in the hub bore region of turbine disk

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

Recovery and residual stress of SMA wires and applications for concrete structures

International Nuclear Information System (INIS)

Choi, Eunsoo; Cho, Sung-Chul; Park, Taehyo; Hu, Jong Wan; Chung, Young-Soo

2010-01-01

In general, NiTi shape memory alloys are used for applications in civil structures. NiTi SMAs show good superelasticity and shape memory effect properties. However, for application of the shape memory effect, it is desirable for SMAs to show a wide temperature hysteresis, especially for civil structures which are exposed to severe environmental conditions. NiTiNb SMAs, in general, show a wider temperature hysteresis than NiTi SMAs and are more applicable for civil structures. This study examines the temperature hysteresis of NiTiNb and NiTi SMAs, and their recovery and residual stress are investigated. In addition, the tensile behaviors of SMA wires under residual stress are evaluated. This study explains the possible applications for concrete structures with the shape memory effect and illustrates two experimental results of concrete cylinders and reinforced concrete columns. For both tests, SMA wires of NiTiNb and NiTi are used to confine concrete using residual stress. The SMA wire jackets on the concrete cylinders increase the peak strength and the ductility compared to the plain concrete cylinders. In addition, the SMA wire jackets on reinforced concrete columns increase the ductility greatly without flexural strength degradation

Modeling of residual stress state in turning of 304L

International Nuclear Information System (INIS)

Valiorgue, F.; Rech, J.; Bergheau, J.M.

2010-01-01

Research presented in this paper aims to link machining parameters to residual stress state and helps understanding mechanisms responsible of machined surface properties modifications. The first presented works are based on an experimental campaign. They reproduce the finishing turning operation of 304L and allow observing the residual stress state evolution at the work piece surface and for an affected depth of 0.2 mm for such processes. Then, the finishing turning operation is simulated numerically in order to realize the same sensitivity study to cutting parameters. This simulation is based on an hybrid approach mixing experimental data and numerical simulation. This method allows getting round the classical difficulties of turning simulation by applying equivalent thermo mechanical loadings onto the work piece surface without modeling the material separation phenomena. Moreover the numerical model uses an hardening law taking into account dynamic recrystallization phenomena. (authors)

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.

Residual stress analysis for engineering applications by means of neutron diffraction

International Nuclear Information System (INIS)

Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J.

1999-01-01

Residual stresses originate from spatial differences in plastic deformation, temperature, or phase distribution, introduced by manufacturing processes or during service. Engineering parts and materials experience mechanical, thermal, and chemical loads during their service, and most of these loads introduce stresses that are superimposed on the already existing residual stresses. Residual stresses can therefore limit or improve life and strength of engineering parts; knowledge and understanding of these stresses is therefore critical for optimizing strength and durability. The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. All of the major sources due in the next several years will have instruments for the sole purpose of performing residual stress and texture measurements. Recently, a dedicated, state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated in collaboration with industrial and academic partners are residual stresses in rails, weldments, and plasma-sprayed coatings

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…

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.

A review of creep analysis and design under multi-axial stress states

International Nuclear Information System (INIS)

Yao, H.-T.; Xuan Fuzhen; Wang Zhengdong; Tu Shantung

2007-01-01

The existence of multi-axial states of stress cannot be avoided in elevated temperature components. It is essential to understand the associated failure mechanisms and to predict the lifetime in practice. Although metal creep has been studied for about 100 years, many problems are still unsolved, in particular for those involving multi-axial stresses. In this work, a state-of-the-art review of creep analysis and engineering design is carried out, with particular emphasis on the effect of multi-axial stresses. The existing theories and creep design approaches are grouped into three categories, i.e., the classical plastic theory (CPT) based approach, the cavity growth mechanism (CGM) based approach and the continuum damage mechanics (CDM) based approach. Following above arrangements, the constitutive equations and design criteria are addressed. In the end, challenges on the precise description of the multi-axial creep behavior and then improving the strength criteria in engineering design are presented

Mild Social Stress in Mice Produces Opioid-Mediated Analgesia in Visceral but Not Somatic Pain States.

Science.gov (United States)

Pitcher, Mark H; Gonzalez-Cano, Rafael; Vincent, Kathleen; Lehmann, Michael; Cobos, Enrique J; Coderre, Terence J; Baeyens, José M; Cervero, Fernando

2017-06-01

Visceral pain has a greater emotional component than somatic pain. To determine if the stress-induced analgesic response is differentially expressed in visceral versus somatic pain states, we studied the effects of a mild social stressor in either acute visceral or somatic pain states in mice. We show that the presence of an unfamiliar conspecific mouse (stranger) in an adjacent cubicle of a standard transparent observation box produced elevated plasma corticosterone levels compared with mice tested alone, suggesting that the mere presence of a stranger is stressful. We then observed noxious visceral or somatic stimulation-induced nociceptive behavior in mice tested alone or in mildly stressful conditions (ie, beside an unfamiliar stranger). Compared with mice tested alone, the presence of a stranger produced a dramatic opioid-dependent reduction in pain behavior associated with visceral but not somatic pain. This social stress-induced reduction of visceral pain behavior relied on visual but not auditory/olfactory cues. These findings suggest that visceral pain states may provoke heightened responsiveness to mild stressors, an effect that could interfere with testing outcomes during simultaneous behavioral testing of multiple rodents. In mice, mild social stress due to the presence of an unfamiliar conspecific mouse reduces pain behavior associated with noxious visceral but not somatic stimulation, suggesting that stress responsiveness may be enhanced in visceral pain versus somatic pain states. Published by Elsevier Inc.

FEA stress analysis considering cavity formation of metallic fuel pin under transient state

Energy Technology Data Exchange (ETDEWEB)

Jung, Hyun-Woo; Oh, Young-Ryun; Kim, Yun-Jae [Korea University, Seoul (Korea, Republic of)

2016-05-15

The aim of this research is to study the stress state of the fuel and the cladding under transient state using the commercial finite element analysis software, ABAQUS v6.13. It is checked out that the gap distance between the fuel and the cladding is a major factor determining FCMI stress. In this regard, initial boundary condition of the fuel pin such as the initial gap distance should be set carefully when the stress analysis of the fuel pin under transient state is conducted. In case of simulating cavity formation, it is confirmed that the new cavity simulation model that elements in cavity region lose their stiffness is valid. There is a great deal of research into SFR, which is one of GEN IV reactors. When it comes to the accidents of SFR, there are two cases of accident process. One of them is In-pin process that molten fuel is discharged into upper plenum. The other is Ex-pin process that the molten fuel is discharged into coolant because of breakage of cladding.

Investigation of smooth specimen scc test procedures; variations in environment, specimen size, stressing frame, and stress state. [for high strength aluminum alloys

Science.gov (United States)

Lifka, B. W.; Sprowls, D. O.; Kelsey, R. A.

1975-01-01

The variables studied in the stress-corrosion cracking performance of high strength aluminum alloys were: (1) corrosiveness of the environment, (2) specimen size and stiffness of the stressing system, (3) interpretation of transgranular cracking, and (4) interaction of the state of stress and specimen orientation in a product with an anisotropic grain structure. It was shown that the probability of failure and time to fracture for a specimen loaded in direct tension are influenced by corrosion pattern, the stressing assembly stiffness, and the notch tensile strength of the alloy. Results demonstrate that the combination of a normal tension stress and a shear stress acting on the plane of maximum susceptibility in a product with a highly directional grain cause the greatest tendency for stress-corrosion cracking.

Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages

Science.gov (United States)

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-01

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha-1 (B1), soil application of 2 kg B ha-1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest

Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages.

Science.gov (United States)

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-12

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha -1 (B1), soil application of 2 kg B ha -1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results

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

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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.

Interpretation of the Haestholmen in situ state of stress based on core damage observations

International Nuclear Information System (INIS)

Hakala, M.

2000-01-01

At the Haestholmen investigation site, direct in situ stress measurements, overcoring and hydraulic fracturing have been unsuccessful because of ring disking and horizontal hydraulic fracturing. Prior to this study, a detailed study on both core disking and ring disking was made, and based on those results an in situ state of stress interpretation method was developed. In this work this method is applied to the Haestholmen site. The interpretation is based on disk fracture type, spacing and shape. Also, the Hoek-Brown strength envelope and Poisson's ratio of intact rock are needed. The interpretation result is most reliable if both core disking and ring disking information at the same depth levels is available. A detailed core logging showed that ring disking is systematic below the -365 m level in the vertical overcoring stress measurement hole, HH-KR6. On the other hand, no representative core disking exists except for two points in two differently oriented subvertical boreholes HH-KR2 and HHKR7. Because the interpretation has to be based on ring disking only, upper and lower estimates for the vertical stress were set. These were gravitational and 67% of gravitational. Furthermore, the in situ stress state was assumed to be in horizontal and vertical planes, because the disking in vertical borehole HH-KR6 was not inclined. The interpretation resulted in a good estimate for the major horizontal stress but none of the horizontal stress rations ( 0.25, 0.5, 0.75 and 1.0 ) or vertical stress assumptions studied are clearly more probable the others. At the 500 m level the resulting maximum horizontal stress is 41 MPa. If a linear fit through the zero depth and zero stress point is applied, the maximum horizontal stress gradient is 0.0818 z MPa/m with a standard deviation between 5 and 12 per cent. The orientation of the major horizontal stress is 108 with standard deviation of 21 degrees. The interpreted major horizontal stress state also indicated that systematic

Nonintrusive biological signal monitoring in a car to evaluate a driver's stress and health state.

Science.gov (United States)

Baek, Hyun Jae; Lee, Haet Bit; Kim, Jung Soo; Choi, Jong Min; Kim, Ko Keun; Park, Kwang Suk

2009-03-01

Nonintrusive monitoring of a driver's physiological signals was introduced and evaluated in a car as a test of extending the concept of ubiquitous healthcare to vehicles. Electrocardiogram, photoplethysmogram, galvanic skin response, and respiration were measured in the ubiquitous healthcare car (U-car) using nonintrusively installed sensors on the steering wheel, driver's seat, and seat belt. Measured signals were transmitted to the embedded computer via Bluetooth(R) communication and processed. We collected and analyzed physiological signals during driving in order to estimate a driver's stress state while using this system. In order to compare the effect of stress on physical and mental conditions, two categories of stresses were defined. Experimental results show that a driver's physiological signals were measured with acceptable quality for analysis without interrupting driving, and they were changed meaningfully due to elicited stress. This nonintrusive monitoring can be used to evaluate a driver's state of health and stress.

Neutron diffraction stress determination in W-laminates for structural divertor applications

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R. Coppola

2015-07-01

Full Text Available Neutron diffraction measurements have been carried out to develop a non-destructive experimental tool for characterizing the crystallographic structure and the internal stress field in W foil laminates for structural divertor applications in future fusion reactors. The model sample selected for this study had been prepared by brazing, at 1085 °C, 13 W foils with 12 Cu foils. A complete strain distribution measurement through the brazed multilayered specimen and determination of the corresponding stresses has been obtained, assuming zero stress in the through-thickness direction. The average stress determined from the technique across the specimen (over both ‘phases’ of W and Cu is close to zero at −17 ± 32 MPa, in accordance with the expectations.

Stress state in perforated plates

International Nuclear Information System (INIS)

Visner, J.

1977-01-01

The method is described of photoelastic measurement of stress concentration factors (s.c.f) in plates perforated by a square, triangular and diagonal grid of circular holes and loaded by uniaxial or biaxial tensile stress. A loading equipment which was developed and its modifications are described. Stress concentration factors found are compared with theoretical and experimental results given in references. (author)

Probing stress state and phase content in ultra-thin Ta films

International Nuclear Information System (INIS)

Whitacre, J.F.; Yalisove, S.M.; Bilello, J.C.; Rek, Z.U.

1998-01-01

Ta films 25 angstrom to 200 angstrom in thickness were sputter-deposited using different sputter gas (Ar) pressures and cathode power settings. The average in-plane stresses were determined using double crystal diffraction topography (DCDT). X-ray analysis (using the grazing incidence x-ray scattering (GIXS) geometry) was performed using a synchrotron light source. To study microstructure and phase content, transmission electron microscopy (TEM) and transmission electron diffraction (TED) were used. Well resolved x-ray patterns were collected for all of the films. The DCDT stress data was found to be consistent with stress effects evidence in the GIXS data. In general, residual stress state was not strongly dependent upon Ar pressure. The strongest evidence of amorphous content was found in both x-ray and TED data taken from 25 angstrom thick films deposited using 2mTorr Ar pressure and 460 W cathode power. These results show that it is possible to create and study ultra-thin Ta films which possess a range of residual stresses and phase compositions

Evolution of microstructure and residual stress on L1{sub 0} ordering in FePt thin films with different initial stress states

Energy Technology Data Exchange (ETDEWEB)

Hsiao, S.N., E-mail: pmami.hsiao@gmail.com [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Yuan, F.T. [iSentek Ltd., Advanced Sensor Laboratory, New Taipei City 221, Taiwan (China); Chen, S.K. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Sun, A.C. [Department of Chemical Engineering and Materials Science, Yuan Ze University, Jungli 320, Taiwan (China); Su, S.H.; Chiu, K.F. [Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China)

2016-01-15

We have characterized the dependence of microstructure, and internal strain/stress on L1{sub 0} ordering in 40 nm thick FePt films with different initial stresses. The microstructural and crystallographic results indicate that defect annihilation and grain growth induced an increase in tensile stress of ~1 GPa before extensive L1{sub 0} ordering. The induced tensile stress can efficiently facilitate the nucleation of L1{sub 0} phase owing to that the volume expansion of L1{sub 0} ordering and atomic rearrangement neutralizes the tensile stress. If the as-deposited FePt film has a highly compressive state, the induced tensile stress will be canceled out and ordering is retarded, which results in a higher ordering temperature. - Highlights: • Microstructure-stress connection in FePt films was studied. • Initial stress alters microstructure and stress evolution during annealing. • Densification induces tensile stress of ~1 GPa before extensive L1{sub 0} ordering. • Induced tensile stress can efficiently facilitate the nucleation of L1{sub 0} phase. • Compressively initial stress results in a higher ordering temperature .

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

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.

Residual stresses under quasi-static and cyclic loading in shot peened Inconel 718

Energy Technology Data Exchange (ETDEWEB)

Hoffmeister, Juergen; Schulze, Volker [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Applied Materials; Hessert, Roland; Koenig, Gerhard [MTU Aero Engines, Munich (Germany)

2012-01-15

The residual stress state induced by shot peening should be taken into account in the dimensioning of turbine components. Understanding the changes in the residual stress state caused by the application of quasi-static and cyclic loads is a prerequisite. In order to describe the residual stress state after quasi-static loading, several different shot peened Inconel 718 specimens were loaded isothermally up to specific tensile loadings. To analyze the residual stress state after cyclic loading, isothermal low cycle fatigue tests were performed. These tests were stopped after a defined number of cycles. Finally, after the specimens had been subjected to different loads, the surface residual stresses and - for special loadings - the residual stress depth distributions were determined experimentally by using X-ray diffraction. The surface - core model was adapted so that the complete residual stress depth distribution after quasi-static and cyclic loading can now be described. (orig.)

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.

Influence of fatigue crack wake length and state of stress on crack closure

Science.gov (United States)

Telesman, Jack; Fisher, Douglas M.

1988-01-01

The location of crack closure with respect to crack wake and specimen thickness under different loading conditions was determined. The rate of increase of K sub CL in the crack wake was found to be significantly higher for plasticity induced closure in comparison to roughness induced closure. Roughness induced closure was uniform throughout the thickness of the specimen while plasticity induced closure levels were 50 percent higher in the near surface region than in the midthickness. The influence of state of stress on low-high load interaction effects was also examined. Load interaction effects differed depending upon the state of stress and were explained in terms of delta K sub eff.

Parametric peak stress functions of 90o pipe bends with ovality under steady-state creep conditions

International Nuclear Information System (INIS)

Yaghi, A.H.; Hyde, T.H.; Becker, A.A.; Sun, W.

2009-01-01

Stress-based life prediction techniques are commonly used to estimate the failure life of pressurised pipe-related components, such as welds and bends, under creep conditions. Previous research has shown that reasonable life predictions can be obtained, based on the steady-state peak stresses, compared with the life predictions obtained from creep damage modelling. In this work, a series of parametric steady-state peak rupture stress functions of right-angled pipe bends with ovality are presented, which are based on the results obtained from finite element (FE) analyses, covering a number of material property and geometry parameters in practical ranges. Methods used to determine the stress functions are described. The FE analyses have been performed using axisymmetric models, subjected to internal pressure only, with a Norton creep law. Typical examples of parametric peak stress curve fitting are shown. In particular, the accuracy of the interpolation and extrapolation abilities of the stress functions is assessed. The results show that in most cases the interpolated and extrapolated peak stresses are accurate to within ±3% and ±5%, respectively.

Diagnostic Inspection of Pipelines for Estimating the State of Stress in Them

Science.gov (United States)

Subbotin, V. A.; Kolotilov, Yu. V.; Smirnova, V. Yu.; Ivashko, S. K.

2017-12-01

The diagnostic inspection used to estimate the technical state of a pipeline is described. The problems of inspection works are listed, and a functional-structural scheme is developed to estimate the state of stress in a pipeline. Final conclusions regarding the actual loading of a pipeline section are drawn upon a cross analysis of the entire information obtained during pipeline inspection.

Parameters for measurement of oxidative stress in diabetes mellitus: applicability of enzyme-linked immunosorbent assay for clinical evaluation.

Science.gov (United States)

Noiri, Eisei; Tsukahara, Hirokazu

2005-05-01

Investigations of the mechanisms involved in the onset and progression of diabetes have recently confronted the role of reactive oxygen species (ROS) and oxidative stress. Prolonged exposure to hyperglycemic conditions induces nonenzymatic glycation of protein via the so-called Maillard reaction, resulting in Schiff-base products and Amadori products that engender ROS production. These processes initiate and exacerbate micro- and macrovascular complications in diabetes. Increased oxidative stress is induced by excessive ROS production and inadequate antioxidant defenses. Recently, oxidative stress status markers have been associated directly with the severity and prognosis of diabetes. To examine oxidative stress, reliable and high-throughput methods are needed to examine large numbers of clinical samples. The emerging availability of enzyme-linked immunosorbent assay (ELISA) for oxidative stress status markers allows its application to assessment of various pathophysiologic conditions, including diabetes. This review outlines the recent achievements of ELISA application for clinical studies elucidating oxidative stress. It introduces the potential applicability of ELISA for investigating oxidative stress in diabetes.

Geodynamics and Stress State of the Earth's Crust in the Greater and Lesser Caucasus (Azerbaijan) collision region

Science.gov (United States)

Babayev, Gulam; Akhmedova, Elnare; Babayev, Elvin

2017-04-01

The current study researches the present-day stress state of the Earth's crust within the territory of Azerbaijan by using the database of the international research project "World Stress Map" (WSM). The present stress state was also assessed by exploring the effects of the contemporary topographic properties of Caucasus in three-dimensional frame. Aiming to explore the relative roles of regional tectonic conditions in the definition of stress state of Greater and Lesser Caucasus, stress distribution model was developed by the earthquake data (1998-2016) and by the standard techniques of stress field calculation. The results show that the stress orientations are influenced also by the combination of topography and crust thickness distribution even at very large depth. Stress data and earthquake focal mechanisms indicate that the stress state of the Earth's crust of the Greater and Lesser Caucasus is characterized by the compression predominantly oriented across the regional strike. The model results suggest that the Lesser Caucasus and Kur depression are rotating coherently, with little or no internal deformation in a counter-clockwise rotation located near the north-eastern corner of the Black Sea. Orientation of stress axes well consistent with earthquake focal mechanisms revealed that within Upper and Lower Crusts, earthquakes are predominantly thrust-faulting with a number of normal-faulting and some strike-slip faulting. The map of the focal mechanisms and stress distribution suggests that the research area is characterized by the thrust of horizontal compression trending north-north-east in the western part of the southern Caucasus. In the western part of Azerbaijan, the compression takes place between the Main Caucasus Fault and the Kur depression, which strikes south along the northern margin of the mountain range. In addition, a clear transition from the left-lateral strike slip to the predominantly right-lateral strike slip is observed in the southern of

Characterizations of Stress and Strain Variation in Three-Dimensional Forming of Laser Micro-Manufacturing

International Nuclear Information System (INIS)

Ming, Zhou; Guo-Huan, Zhao; Tao, Huang; Hua, Ding; Lan, Cai

2010-01-01

A micro-manufacturing technology is presented to form three-dimensional metallic micro-structures directly. Micro grid array structures are replicated on a metallic foil surface, with high spatial resolution in micron levels. The numerical simulation results indicate that the material deformation process is characterized by an ultrahigh strain rate. With increasing pulse duration, the sample absorption strain energy increases, and the sample deformation degree enlarges. The stress state of the central point fluctuates between tensile stress and compression stress. The stress state of the angular point is altered from compressive stress to tensile stress due to geometry and loading conditions. The duration length of pulse stress has an effect on the stress state, as with the increase of pulse duration, fluctuation in the stress state decreases. Therefore, laser micro-manufacturing technology will be a potential laser micro forming method which is characterized by low cost and high efficiency. (fundamental areas of phenomenology(including applications))

Mechanical-Stress Analytical Modeling for the Design of Coils in Power Applications

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Bellan D.

2014-12-01

Full Text Available Modern electrical-power systems are often exploited for transmitting high-frequency carrier signals for communications purposes. Series-connected air-core coils represent the fundamental component allowing such applications by providing a proper filtering in the frequency domain. They must be designed, however, to withstand also the line short-circuit current. When a high-magnitude current flows through a coil, strong mechanical stresses are produced within the conductor, leading to possible damage of the coil. In this paper, an approximate analytical model is derived for the relationship between the maximum mechanical stress and the electrical/geometrical parameters of the coil. Such a model provides the guidelines for a fast and safe coil design, whereas numerical simulations are only needed for the design refinement. The presented approach can be extended to other applications such as, for example, the mechanical stress resulting from the inrush currents in the coils of power transformers.

Evolution of regional stress state based on faulting and folding near the pit river, Shasta county, California

Science.gov (United States)

Austin, Lauren Jean

We investigate the evolution of the regional stress state near the Pit River, northern California, in order to understand the faulting style in a tectonic transition zone and to inform the hazard analysis of Fault 3432 near the Pit 3 Dam. By analyzing faults and folds preserved in and adjacent to a diatomite mine north of the Pit River, we have determined principal stress directions preserved during the past million years. We find that the stress state has evolved from predominantly normal to strike slip and most recently to reverse, which is consistent with regional structures such as the extensional Hat Creek Fault to the south and the compressional folding of Mushroom Rock to the north. South of the Pit River, we still observe normal and strike slip faults, suggesting that changes in stress state are moving from north to south through time.

Effects of Nutrients Foliar Application on Agrophysiological Characteristics of Maize under Water Deficit Stress

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Nour Ali SAJEDI

2010-09-01

Full Text Available To investigate effects of nutrients foliar application on agrophysiological characteristics of maize hybrid �KSC 704� water deficit stress conditions, an experiment was arranged in a split plot factorial based on a randomized complete block design with four replications to the Research Station of Islamic Azad University-Arak Branch, Iran in 2007-2008. Main factors studied were four irrigation levels including irrigation equal to crop water requirement, water deficit stress at eight-leaf stage (V8, blister stage (R2 and filling grain stage (R4 in the main plot. Combined levels of selenium treatment (without and with application 20 gha-1 and micronutrients (without and with application 2 lha-1 were situated in sub plots. Results showed that water deficit stress decreased grain yield 19.7% in blister stage as compared with control. Using selenium increased relative content water at R2 and R4 stages significantly. Using selenium in water deficit stress condition increased measured traits except plant height as compared with treatment without selenium. A negative antagonistic interaction was found between selenium and micronutrients on some measured traits. Between treatments of water deficit stress, highest grain yield equal 6799.52 and 6736.97 kgha-1 was obtained from combined treatments of water deficit stress at eight-leaf stage+without selenium+without micronutrients and water deficit stress at eight-leaf stage+selenium+without micronutrients respectively which compared with treatment of irrigation equal to crop water requirement+selenium+microelements did not differ significant. According to the results of experiment, it is concluded that with micronutrients fertilizer spray under optimum irrigation and selenium spray under water deficit obtain optimum yield.

The influence of stress state on the reorientation of hydrides in a zirconium alloy

International Nuclear Information System (INIS)

Cinbiz, Mahmut N.; Koss, Donald A.; Motta, Arthur T.

2016-01-01

Hydride reorientation can occur in spent nuclear fuel cladding when subjected to a tensile hoop stress above a threshold value during cooling. Because in these circumstances the cladding is under a multiaxial stress state, the effect of stress biaxiality on the threshold stress for hydride reorientation is investigated using hydrided CWSR Zircaloy-4 sheet specimens containing ∼180 wt ppm of hydrogen and subjected to a two-cycle thermo-mechanical treatment. The study is based on especially designed specimens within which the stress biaxiality ratios range from uniaxial (σ_2/σ_1 = 0) to “near-equibiaxial” tension (σ_2/σ_1 = 0.8). The threshold stress is determined by mapping finite element calculations of the principal stresses and of the stress biaxiality ratio onto the hydride microstructure obtained after the thermo-mechanical treatment. The results show that the threshold stress (maximum principal stress) decreases from 155 to 75 MPa as the stress biaxiality increases from uniaxial to “near-equibiaxial” tension.

Improvement of wheat yield grown under drought stress by boron foliar application at different growth stages

Directory of Open Access Journals (Sweden)

F.M.F. Abdel-Motagally

2018-04-01

Full Text Available Two field experiments were conducted to determine the effect of boron foliar application and water stress on yield of wheat plant grown in calcareous soil during 2013/2014 and 2014/2015 seasons. The highest mean values obtained against boron application time were potential contributor to total grains mass by improving the plant height (99.42 and 98.32 cm, spike length (11.86 and 11.72 cm, number of spikelets m−2 (332.65 and 324.35, grain yield plant−1 (21.56 and 20.26 g, 1000-grain weight (35.2 and 37.4 g and grain yield (1.87 and 1.85 ton fed.−1, which were recorded at normal irrigation level (100% from the amount of water consumption for wheat with boron spraying at booting stage (B1 in the first and second seasons, respectively. Furthermore, boron application significantly enhanced all studied growth traits under water stress levels (50% from the amount of water consumption for wheat compared to B-untreated plants. Boron spraying at booting stage enhances also plant pigments contents recording its highest mean values under normal water level (100% from the amount of water consumption for wheat. The reduction in stress markers (proline and H2O2 and the enhancement of plant pigments content under water stress levels (50% from the amount of water consumption for wheat by B spraying suggests an alleviating effect of boron foliar application to water stress in the test plant. This alleviating effect was more pronounced when B applied at booting stage. Therefore, booting stage was found to be the best time for boron application to get higher grains production and consequently, better economic returns of wheat. Keywords: Wheat, Growth stages, Boron application time, Water stress, Crop yield, Plant pigments, Proline, H2O2

On microscopic stress nonequilibrium: Application to the magnetopause

International Nuclear Information System (INIS)

Wu, Z.J.

1986-01-01

The main purpose of this paper is to propose the concept of microscopic stress nonequilibrium (or simply micro-nonequilibrium) in plasma physics. This concept arises as a consequence of the insolubility of the steady-state Vlasov-Maxwell equations (or the kinetic-field equations in general) under certain conditions. In what follows: (1) A general stress equilibrium condition for tangential plasma discontinuities is derived from the Maxwell tensor and the plasma stress tensor. (2) An equivalent equilibrium condition, which takes the form of equations of motion of a ''fictitious particle'', is also derived from the above condition. (3) A general solution of the distribution functions is derived according to Jeans's theorem or Liouville's theorem for the solar wind particles in a tangential magnetopause. (4) This solution is applied to the equilibrium condition to investigate the equilibrium state of the tangential magnetopause. Both Parker's tail-region and Wu's dawn-side ''nonequilibria''are confirmed to be micro-nonequilibria because of the violation of the above equilibrium condition. (5) The effects of various factors in micro-nonequilibria are discussed. It is found that randomly trapped particles and inwards electric field in the magnetopause layer generally cannot relieve the dawn-side or tail-region micro-nonequilibria; and that a northward magnetic field in the solar wind generally can suppress the dawn-side nonequilibrium, while a southward field can jeopardize a dusk-side Vlasov equilibrium. (6) Discussion: The concept of ''micro-nonequilibrium'' may become of importance in basic plasma dynamics. It is also possible that the micro-nonequilibrium may play a fundamental role in solar wind particles entering the magnetopause and in magnetospheric substorms

Computational modeling applied to stress gradient analysis for metallic alloys

International Nuclear Information System (INIS)

Iglesias, Susana M.; Assis, Joaquim T. de; Monine, Vladimir I.

2009-01-01

Nowadays composite materials including materials reinforced by particles are the center of the researcher's attention. There are problems with the stress measurements in these materials, connected with the superficial stress gradient caused by the difference of the stress state of particles on the surface and in the matrix of the composite material. Computer simulation of diffraction profile formed by superficial layers of material allows simulate the diffraction experiment and gives the possibility to resolve the problem of stress measurements when the stress state is characterized by strong gradient. The aim of this paper is the application of computer simulation technique, initially developed for homogeneous materials, for diffraction line simulation of composite materials and alloys. Specifically we applied this technique for siluminum fabricated by powder metallurgy. (author)

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

International Nuclear Information System (INIS)

Valli, J.; Kuula, H.; Hakala, M.

2011-06-01

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

28 CFR 65.41 - Review of State applications.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Review of State applications. 65.41 Section 65.41 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) EMERGENCY FEDERAL LAW ENFORCEMENT.... The Act provides the basis for review and approval or disapproval of state applications. Federal law...

Sectoral contributions to surface water stress in the coterminous United States

International Nuclear Information System (INIS)

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

2013-01-01

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

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,...

The contribution of trait negative affect and stress to recall for bodily states.

Science.gov (United States)

Ma-Kellams, Christine; Lai, Lei; Taylor, Shelley E; Lerner, Jennifer S

2016-12-01

How does trait negative affect shape somatic memory of stressful events? We hypothesized that negative affect would impair accurate recall of one's own heart rate during stressful situations. Two bio-behavioral studies used a new paradigm to test retrospective visceral perception and assessed whether negative affective states experienced during aversive events (i.e., the Trier Stress Task-Time 1) would retrospectively shape recall of past heart rate (Time 2), even when accounting for actual heart rate at the time of each stressful event (Time 1). Results across both studies showed that individual differences in negative affect in response to a stressful task predicted visceral recollections, and those who experienced more negative affect were more inaccurate. Negative affect was associated with a tendency to remember visceral reactions as worse than they actually were. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of cyclic block loading on character of deformation and strength of structural materials in plane stressed state

International Nuclear Information System (INIS)

Kul'chitskij, N.M.; Troshchenko, A.V.; Koval'chuk, B.I.; Khamaza, L.A.; Nikolaev, I.A.

1982-01-01

The paper is concerned with choice of conditions for preliminary cyclic block loading, determination of fatigue failure resistance characteristics for various structural materials under regular and selected block loading, investigation of the preliminary cyclic loading effect on regularities of elastoplastic deformation of materials concerned in the biaxial stressed state. Under selected conditions of cyclic block loading the character of damage accumulation is close to the linear law for the materials of high-srength doped steel, and VT6 alloys of concern. These materials in the initial state and after preliminary cyclic loading are anisotropic. Axial direction is characterized by a higher plastic strain resistance for steel and tangential direction - for VT6 alloy. The generalized strain curves for the materials in question are not invariant as to the stressed state type. It is stated that the effect of preliminary unsteady cyclic loading on resistance and general regularities of material deformation in the complex stressed state is insignificant. It is observed that stress-strain properties of the materials tend to vary in the following way: plastic strain resistance of the steel lowers and that of VT6 rises, anisotropy of the materials somehow decreases. The variation in the material anisotropy may be attributed to a decrease in residual stresses resulting from preliminary cyclic loading

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

Science.gov (United States)

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

2017-12-01

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

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

Numerical analysis oriented biaxial stress-strain relation and failure criterion of plain concrete

International Nuclear Information System (INIS)

Link, J.

1975-01-01

A biaxial stress-strain relation and failure criterion is proposed, which is applicable to structural analysis methods. The formulation of material behavior of plain concrete in biaxial stress-state was developed. A nonlinear elastic, anisotropic stress-strain relation was derived with two moduli of elasticity, E 1 , E 2 and Poisson's ratios, ν 1 , ν 2 , which depend on the prevailing biaxial stress state. The stress-strain relation is valid in the whole biaxial stress field, that means with a smooth transition between the domains of tension/tension, tension/compression and compression/compression. The stress-dependent moduli E 1 , E 2 and the Poisson's ratios ν 1 , ν 2 are approximated by polynomials, trigonometrical and exponential functions. A failure criterion was defined by approximating the test results of the biaxial ultimate concrete strength with a 7th degree polynomial, which is also valid in the whole biaxial stress domain. The definition of the state of failure is given as a function of stresses as well as strains. Initial parameters of the formulation of the biaxial material behavior are the uniaxial cylindrical strength of concrete and the initial values of Young's modulus and Poisson's ratio. A simple expansion of this formulation makes it applicable not only to normal but also to light-weight concrete. Comparison of numerically calculated stress-strain curves up to the ultimate biaxial stresses which indicate the failure criteria with those obtained from tests show a very good agreement. It is shown, that the biaxial stress-strain relation can be extended for use in cases of triaxial tension/tension/compression stress state. Numerical examples of analysis of concrete slabs show the importance of incorporation of a realistic material behavior for better safety estimations

Influence of cold rolling and fatigue on the residual stress state of a metal matrix composite

International Nuclear Information System (INIS)

Hanus, E.; Ericsson, T.; Lu, J.; Decomps, F.

1993-01-01

The large difference in the coefficient of thermal expansion between the matrix alloy and the particle in a metal matrix composite gives rise to residual stresses in the material. In the present work the effect of cold rolling and four-point bending fatigue on the residual stress state of a silicon carbide particle reinforced aluminium alloy (AA 2014) has been investigated. The three dimensional stress state measured in both phases: matrix and reinforcement, has been determined by using an X-ray diffraction technique. It was found that cold rolling induces surface compressive macrostresses of about -250 MPa, with a penetration depth around 2 mm. The absolute values of the pseudomacrostresses in both phases are significantly reduced due to the single track rolling. Stress relaxation occurs during four-point bending fatigue. (orig.)

10 CFR 420.13 - Annual State applications and amendments to State plans.

Science.gov (United States)

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Annual State applications and amendments to State plans. 420.13 Section 420.13 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION STATE ENERGY PROGRAM Formula..., renewable energy, and alternative transportation fuel goals to be achieved, including wherever practicable...

Interface states in stressed semiconductor heterojunction with antiferromagnetic ordering

International Nuclear Information System (INIS)

Kantser, V.G.

1995-08-01

The stressed heterojunctions with antiferromagnetic ordering in which the constituents have opposite band edge symmetry and their gaps have opposite signs have been investigated. The interface states have been shown to appear in these heterojunctions and they are spin-split. As a result if the Fermi level gets into one of the interface bands then it leads to magnetic ordering in the interface plane. That is if the interface magnetization effect can be observed. (author). 14 refs, 2 figs

Family Environments and Children's Executive Function: The Mediating Role of Children's Affective State and Stress.

Science.gov (United States)

He, Zhong-Hua; Yin, Wen-Gang

2016-09-01

There is increasing evidence that inadequate family environments (family material environment and family psychosocial environment) are not only social problems but also factors contributing to adverse neurocognitive outcomes. In the present study, the authors investigated the relationship among family environments, children's naturalistic affective state, self-reported stress, and executive functions in a sample of 157 Chinese families. These findings revealed that in inadequate family material environments, reduced children's cognitive flexibility is associated with increased naturalistic negative affectivity and self-reported stress. In addition, naturalistic negative affectivity mediated the association between family expressiveness and children's cognitive flexibility. The authors used a structural equation model to examine the mediation model hypothesis, and the results confirmed the mediating roles of naturalistic negative affectivity and self-reported stress between family environments and the cognitive flexibility of Chinese children. These findings indicate the importance of reducing stress and negative emotional state for improving cognitive functions in children of low socioeconomic status.

10 CFR 455.131 - State ranking of grant applications.

Science.gov (United States)

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false State ranking of grant applications. 455.131 Section 455... State ranking of grant applications. (a) Except as provided by § 455.92 of this part, all eligible... audit or energy use evaluation pursuant to § 455.20(k). Each State shall develop separate rankings for...

Stress inoculation training supported by physiology-driven adaptive virtual reality stimulation.

Science.gov (United States)

Popović, Sinisa; Horvat, Marko; Kukolja, Davor; Dropuljić, Branimir; Cosić, Kresimir

2009-01-01

Significant proportion of psychological problems related to combat stress in recent large peacekeeping operations underscores importance of effective methods for strengthening the stress resistance of military personnel. Adaptive control of virtual reality (VR) stimulation, based on estimation of the subject's emotional state from physiological signals, may enhance existing stress inoculation training (SIT). Physiology-driven adaptive VR stimulation can tailor the progress of stressful stimuli delivery to the physiological characteristics of each individual, which is indicated for improvement in stress resistance. Therefore, following an overview of SIT and its applications in the military setting, generic concept of physiology-driven adaptive VR stimulation is presented in the paper. Toward the end of the paper, closed-loop adaptive control strategy applicable to SIT is outlined.

Clinical applications of resting state functional connectivity

Directory of Open Access Journals (Sweden)

Michael D Fox

2010-06-01

Full Text Available During resting conditions the brain remains functionally and metabolically active. One manifestation of this activity that has become an important research tool is spontaneous fluctuations in the blood oxygen level dependent (BOLD signal of fMRI. The identification of correlation patterns in these spontaneous fluctuations has been termed resting state functional connectivity (fcMRI and has the potential to greatly increase the translation of fMRI into clinical care. In this article we review the advantages of the resting state signal for clinical applications including detailed discussion of signal to noise considerations. We include guidelines for performing resting state research on clinical populations, outline the different areas for clinical application, and identify important barriers to be addressed to facilitate the translation of resting state fcMRI into the clinical realm.

Application of photostress method in stress analysis of a rotating disc

OpenAIRE

Frankovský, P.; Trebuňa, F.

2014-01-01

The presented article demonstrates the application of PhotoStressR method in stress analysis of a rotating disc of a constant thickness, which was made of a photoelastic material PS-1A. Isoclinic fringes were observed on the rotating disc using linear polarized light at revolutions 5 000 RPM. Observations were carried out under angle parameter 0 o to 90 o with 10 o increase. A set of isostatic lines of I and II set was made from the set of obtained isoclinic lines. During gradual increase of ...

Investigations into the Surface Strain/Stress State in a Single-Crystal Superalloy via XRD Characterization

Directory of Open Access Journals (Sweden)

Haodong Duan

2018-05-01

Full Text Available The present study was aimed at determining the surface strain/stress state in an Ni-based single-crystal (SC superalloy that was subjected to two different cooling rates from solid solution temperature through using the X-ray diffraction (XRD method. The normal stresses σ 11 s and σ 22 s were determined, then the Von Mises stresses ( σ V M s were derived from them. Field emission gun scanning electron microscope (FEG-SEM and transmission electron microscope (TEM micrographs were taken to illustrate the strain/stress state change. The precipitation of the secondary γ′ phases in the γ phase and the formation of the dislocation in the interphase upon a slower cooling rate caused the γ phase lattice distortion to increase, so a larger σ V M s of the γ phase was realized in comparison to the faster cooling sample. For both of the two cooling modes, we found that the σ V M s of the γ′ phase increased due to the growth of the γ′ phase during the aging process. Also, the aging process led to pronouncedly anisotropic lattice mismatches in the {331} and {004} planes. In addition, the surface strain/stress states of a cylinder sample and a tetragonal sample were also studied using a faster cooling rate, and σ 11 s and σ 22 s were analyzed to explain the influence of the shape factor on the stress anisotropy in the [001] and [ 1 1 ¯ 0 ] orientations. The strain in the [001] orientation of the γ phase is more sensitive to the shape change.

The Pursuit of K: Reflections on the Current State-of-the-Art in Stress Intensity Factor Solutions for Practical Aerospace Applications

Science.gov (United States)

CraigMcClung, R.; Lee, Yi-Der; Cardinal, Joseph W.; Guo, Yajun

2012-01-01

The elastic stress intensity factor (SIF, commonly denoted as K) is the foundation of practical fracture mechanics (FM) analysis for aircraft structures. This single parameter describes the first-order effects of stress magnitude and distribution as well as the geometry of both structure/component and crack. Hence, the calculation of K is often the most significant step in fatigue analysis based on FM. This presentation will provide several reflections on the current state-of-the-art in SIF solution methods used for practical aerospace applications, including a brief historical perspective, descriptions of some recent and ongoing advances, and comments on some remaining challenges. Newman and Raju made significant early contributions to practical structural analysis by developing closed-form SIF equations for surface and corner cracks in simplified geometries, often based on empirical fits of finite element (FE) solutions. Those solutions (and others like them) were sometimes revised as new analyses were conducted or limitations discovered. The foundational solutions have exhibited striking longevity, despite the relatively "coarse" FE models employed many decades ago. However, in recent years, the accumulation of different generations of solutions for the same nominal geometry has led to some confusion (which solution is correct?), and steady increases in computational capabilities have facilitated the discovery of inaccuracies in some (not all!) of the legacy solutions. Some examples of problems and solutions are presented and discussed, including the challenge of maintaining consistency with legacy design applications. As computational power has increased, the prospect of calculating large numbers of SIF solutions for specific complex geometries with advanced numerical methods has grown more attractive. Fawaz and Andersson, for example, have been generating literally millions of new SIF solutions for different combinations of multiple cracks under simplified

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

Residual stress analysis in reactor pressure vessel attachments

International Nuclear Information System (INIS)

Dexter, R.J.; Pont, D.

1991-08-01

Residual stresses in cladding and welded attachments could contribute to the problem of stress-corrosion cracking in boiling-water reactors (BWR). As part of a larger program aimed at quantifying residual stress in BWR components, models that would be applicable for predicting residual stress in BWR components are reviewed and documented. The review includes simple methods of estimating residual stresses as well as advanced finite-element software. In general, simple methods are capable of predicting peak magnitudes of residual stresses but are incapable of adequately characterizing the distribution of residual stresses. Ten groups of researchers using finite-element software are reviewed in detail. For each group, the assumptions of the model, possible simplifications, material property data, and specific applications are discussed. The most accurate results are obtained when a metallurgical simulation is performed, transformation plasticity effects are included, and the heating and cooling parts of the welding thermal cycle are simulated. Two models are identified which can provide these features. The present state of these models and the material property data available in the literature are adequate to quantify residual stress in BWR components

Hydrostatic stress dependence of the exciton-phonon coupled states in cylindrical quantum dots

International Nuclear Information System (INIS)

El Moussaouy, A.; Bria, D.; Nougaoui, A.

2005-01-01

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 Ga 1-x Al x As 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

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.

Simplified calculation of thermal stresses - on the reduction of effort in the stress analysis of reactor components

International Nuclear Information System (INIS)

Karow, K.

1984-01-01

The fatigue behaviour of reactor components is predominantly determined from the in-service thermal stresses. The calculation of such stresses for a number of temperature transients in the adjacent fluid may be expensive, particularly with complicated structures. Under certain conditions this expense can be reduced considerably with the aid of a rule, which permits interpolation of thermal stresses from known reference values instead of calculation. This paper presents the derivation and method of application of this interpolation rule. The derivation procedure is based on well-known proportionalities between thermal stress range Δsigma in the structure and temperature change ΔT and rate of change T of the fluid in the extreme cases of an ideal thermal shock and quasi-steady-state conditions, respectively. For the real transients in between the relationship Δsigma proportional (ΔT)sup(x) Tsup(1-x)αsup(y) is proposed, where x is the shock-degree and lies between 0 and 1, and, additionally, y designates the influence of the heat transfer coefficient α. This formula yields the interpolation rule. The rule permits interpolation of stress ranges for additional thermal transients from at least 3 reference stresses via x and y. The procedure is applicable to any metallic structure, reduces fatigue analysis effort considerably and yields excellent results. The paper is split up into 2 parts. In the following the derivation of the rule is presented. The second part describes its application and will be published shortly. (orig.)

Development and Clinical Evaluation of an mHealth Application for Stress Management

Directory of Open Access Journals (Sweden)

Brent D. Winslow

2016-07-01

Full Text Available A large number of individuals experience mental health disorders, with cognitive behavioral therapy (CBT emerging as a standard practice for reduction in psychiatric symptoms including stress, anger, anxiety and depression. However, CBT is associated with significant patient dropout, and lacks the means to provide objective data regarding a patient’s experience and symptoms between sessions. Emerging wearables and mobile health (mHealth applications represent an approach that may provide objective data to the patient and provider between CBT sessions. Here we describe the development of a classifier of real-time physiological stress in a healthy population (n=35, and apply it in a controlled clinical evaluation for armed forces veterans undergoing CBT for stress and anger management (n=16. Using cardiovascular and electrodermal inputs from a wearable device, the classifier was able to detect physiological stress in a non-clinical sample with an accuracy greater than 90%. In a small clinical sample, patients who used the classifier and an associated mHealth application were less likely to discontinue therapy (p=0.016, d=1.34 and significantly improved on measures of stress (p=0.032, d=1.61, anxiety (p=0.050, d=1.26, and anger (p=0.046, d=1.41 compared to controls undergoing CBT alone. Given the large number of individuals that experience mental health disorders, and the unmet need for treatment, especially in developing nations, such mHealth approaches have the potential to provide or augment treatment at low cost in the absence of in-person care.

Effect of Foliar Application of Chitosan on Growth and Biochemical Characteristics of Safflower (Carthamus tinctorius L. under Water Deficit Stress

Directory of Open Access Journals (Sweden)

batool mahdavi

2014-09-01

Full Text Available In order to study the effects of water deficit stress and foliar application of chitosan in safflower (Carthamus tinctorius L., a pot experiment was conducted in 2009. Experimental design was a randomized complete block in factorial arrangement with three replications. Experimental factors were water deficit levels (unstressed (control and 70% available water depletion from soil (water deficit stress, chitosan concentrations (0, 0.05, 0.1%, all dissolved in 1% acetic acid along with an additional treatment of distilled water and foliar application times (before and during stem elongation. The results showed that water deficit stress reduced plant height, leaf area, shoot and root dry weight, root height and volume. Whereas, foliar application of chitosan increased mentioned traits. In addition, water deficit stress decreased chlorophyll fluorescence, chlorophyll concentration and relative water content. Carotenoid, proline and malondialdehyde (MDA content were increased in response to stress. Foliar application of chitosan increased chlorophyll fluorescence, relative water content (68.77% and chlorophyll b in the water deficit stressed plants, whereas decreased MDA content. The results of the present study indicate that application of chitosan can reduce the harmful effects of water deficit and improve plant growth.

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.

2018-03-01

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

Extreme of random field over rectangle with application to concrete rupture stresses

DEFF Research Database (Denmark)

Ditlevsen, Ove Dalager

2000-01-01

to time consuming simulation procedures. This paperrevives a conceptually simple approach that gives surprisingly good results in particular for wide band typesof random processes and fields. The closed form formulas obtained for smooth Gaussian fieldsover rectangles contain size effects both with respect...... to the area of the rectangle and the side lengths of therectangle. Published rupture stress data for plain concrete beams illustrate the applicability of the derivedclosed form extreme value distributions as models for distributions of rupture stresses related to weakest linkmechanisms....

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

Czech Academy of Sciences Publication Activity Database

Waclawik, Petr; Ptáček, Jiří; Koníček, Petr; Kukutsch, Radovan; Němčík, J.

2016-01-01

Roč. 15, č. 2 (2016), s. 49-56 ISSN 2300-3960 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : stress-state monitoring * room and pillar * coal pillar Subject RIV: DH - Mining , incl. Coal Mining http://www.sciencedirect.com/science/article/pii/S2300396016300180

Applicability of aseismic base isolation design to FBRs and state of its development

International Nuclear Information System (INIS)

Morishita, Masaki

1987-01-01

In the reactor vessels and other main equipment of FBRs, thermal stress and the stress due to earthquake load are the main dominant factors in the structural design. As to thermal stress, it is desirable to make vessels and pipings into the thin walled flexible structures, while in the aspect of aseismatic safety, it is necessary to give the required rigidity to the system. Accordingly, it is the key subject to find out the point of compromise between thermal stress-withstanding design and aseismatic design for the optimization. In the case of FBRs, particularly the rationalization of aseismatic design is necessary, and as one of the promising measures, the application of aseismic base isolation is conceivable. It is to suppress the transmission of earthquake motion to the system by designing the natural period of a structural system longer than the dominant period component of earthquake motion input. The basic concept of aseismatic base isolation design, the examples of its application in foreign countries, its research and development in Japan, the structural features of FBRs and their aseismatic base isolation design, the examples of the examination of its application to FBRs, and the problems of hereafter are described. (Kako, I.)

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.

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.

Oxidative stress markers in hypertensive states of pregnancy: preterm and term disease.

Directory of Open Access Journals (Sweden)

Lesia Olha Kurlak

2014-08-01

Full Text Available Discussion continues as to whether de novo hypertension in pregnancy with significant proteinuria (pre-eclampsia; PE and non-proteinuric new hypertension (gestational hypertension; GH are parts of the same disease spectrum or represent different conditions. Non-pregnant hypertension, pregnancy and PE are all associated with oxidative stress. We have established a 6 weeks post-partum clinic for women who experienced a hypertensive pregnancy. We hypothesized that PE and GH could be distinguished by markers of oxidative stress; thiobarbituric acid reactive substances (TBARS and antioxidants (ferric ion reducing ability of plasma; FRAP. Since the severity of PE and GH is greater pre-term, we also compared pre-term and term disease. Fifty-eight women had term PE, 23 pre-term PE, 60 had term GH and 6 pre-term GH, 11 pre-existing (essential hypertension (EH without PE. Limited data were available from normotensive pregnancies (n=7 and non-pregnant controls (n=14. There were no differences in postpartum TBARS or FRAP between hypertensive states; TBARS (P=0.001 and FRAP (P=0.009 were lower in plasma of non-pregnant controls compared to recently-pregnant women. Interestingly FRAP was higher in preterm than term GH (P=0.013. In PE and GH, TBARS correlated with low density lipoprotein (LDL-cholesterol (P=0.036; this association strengthened with inclusion of EH ((P=0.011. The 10 year Framingham index for cardiovascular risk was positively associated with TBARS (P=0.003.Oxidative stress profiles do not differ between hypertensive states but appear to distinguish between recently-pregnant and non-pregnant states. This suggests that pregnancy may alter vascular integrity with changes remaining 6 weeks postpartum. LDL-cholesterol is a known determinant of oxidative stress in cardiovascular disease and we have shown this association to be present in hypertensive pregnancy further emphasizing that such a pregnancy may be revealing a pre-existing cardiovascular

Experimental study on the thermo-mechanical behaviour of stiff clay under non-isotropic stress state

International Nuclear Information System (INIS)

Tang, Anh Minh; Cui, Yu-Jun; Li, Xiang-Ling

2012-01-01

Document available in extended abstract form only. Stiff clay is usually considered as possible host-rock for geological radioactive waste disposal due to its low permeability and its self-sealing capacity. Boom Clay, for instance, is one of the clays currently considered by the Belgian radioactive waste management agency Ondraf/Niras as a potential host for a geological repository. In order to analyse the performance of this material, it is important to understand its behaviour under the coupled thermo-hydro-mechanical solicitations. In laboratory, several studies have been performed to study the volume change of clay under coupled thermomechanical loading. The results show that heating under drained conditions can induce thermal dilation at low confining stress and thermal contraction at high confining stress. On the other hand, compression tests performed at constant temperature show that the compressibility parameters of soil can be modified by temperature change. These features are now well considered in constitutive laws based on the framework of elasto-plasticity. Under undrained conditions, heating can increase pore-water pressure and this behaviour can be simulated using the theoretical thermo-poro-elastic framework. The temperature effect on the soil behaviour under triaxial compression is also often considered. It is commonly accepted that heating decreases the shear strength of clay but this softening can be hidden by the thermal contraction that occurs during heating which can induce at the same time soil hardening. In spite of these existing works, laboratory tests considering the thermo-mechanical loading path that the soil can be subjected to are still rare. Actually, in the case of geological radioactive waste disposal, after the installation of waste canisters, the soil is expected to be heated under non-isotropic stress state. Most of the existing laboratory works show heating tests in odometer cell or triaxial cell under isotropic stress

Mastering the biaxial stress state in nanometric thin films on flexible substrates

Energy Technology Data Exchange (ETDEWEB)

Faurie, D., E-mail: faurie@univ-paris13.fr [LSPM-CNRS, UPR3407, Université Paris 13, Villetaneuse (France); Renault, P.-O.; Le Bourhis, E. [Institut Pprime UPR3346, CNRS – Université de Poitiers, Futuroscope (France); Geandier, G. [Institut Jean Lamour, CNRS UMR7198, Université de Lorraine, Nancy Cedex (France); Goudeau, P. [Institut Pprime UPR3346, CNRS – Université de Poitiers, Futuroscope (France); Thiaudière, D. [SOLEIL Synchrotron, Saint-Aubin, Gif-Sur-Yvette (France)

2014-07-01

Biaxial stress state of thin films deposited on flexible substrate can be mastered thanks to a new biaxial device. This tensile machine allows applying in-plane loads F{sub x} and F{sub y} in the two principal directions x and y of a cruciform-shaped polymer substrate. The transmission of the deformation at film/substrate interface allows controlling the stress and strain field in the thin films. We show in this paper a few illustrations dealing with strain measurements in polycrystalline thin films deposited on flexible substrate. The potentialities of the biaxial device located at Soleil synchrotron are also discussed.

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

Directory of Open Access Journals (Sweden)

Valeria Gasperi

2013-05-01

Full Text Available 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.

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

Thermal-deformation effect of welding on A 1 reactor pressure vessel weld joints properties and state of stress

International Nuclear Information System (INIS)

Becka, J.; Kupka, I.

1976-01-01

The methods are compared of electroslag welding and of arc welding with a view to their possible application in welding the Bohunice A-1 reactor pressure vessel. Considered are the thermal deformation effects of welding on the physical properties and the stress present in welded joints. For testing, plates were used having the dimensions of 1100x2300x200 mm and rings with 4820 mm outer diameter, 1800 mm height and 170 mm thickness made of steel CSN 413O30 modified with Ni, Al+Ti. The deformation effect of welding on the residual surface and triaxial stress, the specific stored energy, the initiation temperature of brittle crack and the critical size of the initiation defect corresponding to the thermal deformation effect of welding were determined. It was found that for electroslag welding, there is a low probability of crack formation in the joints, a low level of residual stress and a low level of specific stored energy in a relatively wide joint zone. For arc welding there is a considerable probability of defect formation in the vicinity of the sharp boundary of the joint, a high level of the triaxial state of stress in the tensile region, and a high level of specific stored energy concentrated in the narrow zone of weld joints. The recommended thermal process is given for welding pressure vessels made of the CSN 413030 steel modified with Ni, Al+Ti, and 150 to 200 mm in thickness. (J.P.)

Extracellular redox state: refining the definition of oxidative stress in aging.

Science.gov (United States)

Jones, Dean P

2006-01-01

Oxidative stress in aging can result from an imbalance of prooxidants and antioxidants with excessive, destructive free radical chemistry. Thiol systems are important in the control of these processes, both by protecting against damage and serving in redox signaling mechanisms to sense danger and repair the damage. Studies by a number of research groups in collaboration with the Emory Clinical Biomarkers Laboratory show that the redox state of the central tissue antioxidant, glutathione (GSH), can be measured in human plasma and provides a quantitative systemic indicator of oxidative stress. Plasma GSH/GSSG redox in humans becomes oxidized with age, in response to chemotherapy, as a consequence of cigarette smoking, and in association with common age-related diseases (e.g., type 2 diabetes, cardiovascular disease). However, the GSH/GSSG redox is not equilibrated with the larger plasma cysteine/cystine (Cys/CySS) pool, and the Cys/CySS redox varies with age in a pattern that is distinct from that of GSH/GSSG redox. Furthermore, in vitro studies show that variation in Cys/CySS redox over the range found in vivo affects signaling pathways, which control cell proliferation and oxidant-induced apoptosis. The results point to the conclusion that free radical scavenging antioxidants are of increased importance when thiol/disulfide redox states are oxidized. Because thiol/disulfide redox states, per se, function in redox signaling and control as well as antioxidant protection, GSH/GSSG and Cys/CySS redox states may provide central parameters to link environmental influences and progression of changes associated with aging.

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…

Numerical Analysis of the Influence of Clearance on Stress State and Contact Pressure in Plain Bearings

Directory of Open Access Journals (Sweden)

Vasile Cojocaru

2017-12-01

Full Text Available In the analysis of plain bearings by finite element method it is important to model as closely to real state the aspects that influence the stress and contact pressure: the loading mode, the properties of the materials, the lubrication system, the clearance between the shaft and the bearing body, the evolution in time of clearance correlated with the wear, etc. In order to study the effect of the clearance on the stress state, a plain bearing with nominal diameter d=40 mm was modeled. The contact pressure and the equivalent stress were computed for six discrete values of clearance, range from c=0 to c=0.3 mm. It has been shown that the increase of clearance generates an increase of the equivalent stress and contact pressure. The growth rate is higher for contact pressure, due to the decrease of the contact surface between the shaft and the bearing body

Study of stress-strain state of pipeline under permafrost conditions

Science.gov (United States)

Tarasenko, A. A.; Redutinskiy, M. N.; Chepur, P. V.; Gruchenkova, A. A.

2018-05-01

In this paper, the dependences of the stress-strain state and subsidence of pipelines on the dimensions of the subsidence zone are obtained for the sizes of pipes that have become most widespread during the construction of main oil pipelines (530x10, 820x12, 1020x12, 1020x14, 1020x16, 1220x14, 1220x16, 1220x18 mm). True values of stresses in the pipeline wall, as well as the exact location of maximum stresses for the interval of subsidence zones from 5 to 60 meters, are determined. For this purpose, the authors developed a finite element model of the pipeline that takes into account the actual interaction of the pipeline with the subgrade and allows calculating the SSS of the structure for a variable subsidence zone. Based on the obtained dependences for the underground laying of oil pipelines in permafrost areas, it is proposed to artificially limit the zone of possible subsidence by separation supports from the soil with higher building properties and physical-mechanical parameters. This technical solution would significantly reduce costs when constructing new oil pipelines in permafrost areas.

31 CFR 50.24 - Applicability of State law requirements.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Applicability of State law requirements. 50.24 Section 50.24 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Mandatory Availability § 50.24 Applicability of State law requirements. (a...

Heart rate variability (HRV): an indicator of stress

Science.gov (United States)

Kaur, Balvinder; Durek, Joseph J.; O'Kane, Barbara L.; Tran, Nhien; Moses, Sophia; Luthra, Megha; Ikonomidou, Vasiliki N.

2014-05-01

Heart rate variability (HRV) can be an important indicator of several conditions that affect the autonomic nervous system, including traumatic brain injury, post-traumatic stress disorder and peripheral neuropathy [3], [4], [10] & [11]. Recent work has shown that some of the HRV features can potentially be used for distinguishing a subject's normal mental state from a stressed one [4], [13] & [14]. In all of these past works, although processing is done in both frequency and time domains, few classification algorithms have been explored for classifying normal from stressed RRintervals. In this paper we used 30 s intervals from the Electrocardiogram (ECG) time series collected during normal and stressed conditions, produced by means of a modified version of the Trier social stress test, to compute HRV-driven features and subsequently applied a set of classification algorithms to distinguish stressed from normal conditions. To classify RR-intervals, we explored classification algorithms that are commonly used for medical applications, namely 1) logistic regression (LR) [16] and 2) linear discriminant analysis (LDA) [6]. Classification performance for various levels of stress over the entire test was quantified using precision, accuracy, sensitivity and specificity measures. Results from both classifiers were then compared to find an optimal classifier and HRV features for stress detection. This work, performed under an IRB-approved protocol, not only provides a method for developing models and classifiers based on human data, but also provides a foundation for a stress indicator tool based on HRV. Further, these classification tools will not only benefit many civilian applications for detecting stress, but also security and military applications for screening such as: border patrol, stress detection for deception [3],[17], and wounded-warrior triage [12].

Numerical evaluation of state boundary surface through rotation of principal stress axes in sand

International Nuclear Information System (INIS)

Sadrnejad, S. A.

2001-01-01

In applying shear stress to saturated soil with arbitrary stress paths, the prediction of the exact value of strains is difficult because of mainly its stress path dependent nature. Rotation of the principal stress axes during shearing of the soil is a feature of stress paths associated with many field loading situations. A proper understanding of the effects of principal stress rotation on soil behavior can be provided if the anisotropy existing prior to stress rotation and induced anisotropy due to plastic flow in soil are clearly understood and modeled. A multi laminate based model for soil is developed and used to compute and present the influence of rotation of principal stress axes on the plastic behavior of soil. This is fulfilled by distributing the effects of boundary condition changes into several predefined sampling orientations at one point and summing the micro-results up as the macro-result. The validity of the presented model examined by comparing numerical and test results showing the mentioned aspect. In this paper, the state boundary surface is numerically obtained by a multi laminate based model capable of predicting the behavior of sand under the influences of rotation of the direction of principal stress axes and induced anisotropy. the predicted numerical results are tally in agreement with experiments

Stress description model by non destructive magnetic methods

International Nuclear Information System (INIS)

Flambard, C.; Grossiord, J.L.; Tourrenc, P.

1983-01-01

Since a few years, CETIM investigates analysis possibilities of materials, by developing a method founded on observation of ferromagnetic noise. By experiments, correlations have become obvious between state of the material and recorded signal. These correlations open to industrial applications to measure stresses and strains in elastic and plastic ranges. This article starts with a brief historical account and theoretical backgrounds of the method. The experimental frame of this research is described, and the main results are analyzed. Theoretically, a model was built up, and we present it. It seems in agreement with some experimental observations. The main results concerning stress application, thermal and surface treatments (decarbonizing) are presented [fr

Application of radial basis neural network for state estimation of ...

African Journals Online (AJOL)

An original application of radial basis function (RBF) neural network for power system state estimation is proposed in this paper. The property of massive parallelism of neural networks is employed for this. The application of RBF neural network for state estimation is investigated by testing its applicability on a IEEE 14 bus ...

[The application of low-intensity electromagnetic radiation under immobilization stress conditions (an experimental study)].

Science.gov (United States)

Korolev, Iu N; Bobrovnitskiĭ, I P; Nikoulina, L A; Mikhaĭlik, L V; Geniatulina, M S; Bobkova, A S

2014-01-01

The experiments carried out on outbred male white rats with the use of optical, electron-microscopic, biochemical, and radioimmunological methods have demonstrated that the application of low-intensity electromagnetic radiation (LI-EMR) with a flow density of 1 mcW/cm2 and a frequency of around 1,000 MHz both in the primary prophylaxis regime and as the therapeuticpreventive modality arrested the development of post-stress disorders in the rat testicles, liver, and thymus; moreover, it promoted activation of the adaptive, preventive, and compensatory processes. The data obtained provide a rationale for the application of low-intensity electromagnetic radiation to protect the organism from negative effects of stressful factors.

Solid-state radiation detectors technology and applications

CERN Document Server

2015-01-01

The book discusses the current solid state material used in advance detectors manufacturing and their pros and cons and how one can tailor them using different techniques, to get the maximum performance. The book is application oriented to radiation detectors for medical, X and gamma rays application, and good reference with in-depth discussion of detector's physics as it relates to medical application tailored for engineers and scientists.

The Stress-Strain State of Recent Structures in the Northeastern Sector of the Russian Arctic Region

Science.gov (United States)

Imaeva, L. P.; Imaev, V. S.; Mel'nikova, V. I.

2018-03-01

Complex research to determine the stress-strain state of the Earth's crust and the types of seismotectonic destruction for the northeastern sector of the Russian Arctic was conducted. The principles of regional ranking of neotectonic structures were developed according to the activity of geodynamic processes, and argumentation for their class differentiation is presented. The structural-tectonic position, the parameters of the deep structure, the system of active faults, and the tectonic stress fields, calculated on the basis of both tectonophysical analysis of discontinuous and folded late Cenozoic deformations and seismological data, were analyzed. This complex of investigations made it possible to determine the directions of the main axes of deformations of the stress-strain state of the Earth's crust and to reveal the regularity in the change of tectonic regimes.

Stress state of main stop valve with 500 mm nominal diameter white thermomechanical loading

International Nuclear Information System (INIS)

Koklyuev, G.A.; Plotnikov, V.P.

1987-01-01

The method of finite elements was applied to calculate the stress-strain state of the main isolation valve case with 500 mm nominal diameter while thermomechanical loading. Maximum stress takes place in the zone of joining nozzles with a spherical case and it attains the value of 138 MPa at working pressure of 12.5 MPa. The stress level in the point of nozzle-case welding is essentially lower than in zones of stres concentration and when excluding water hitting the slot of the lack of fusion in the route of the weld the weld service life is attained during the calculated service life

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.

RESEARCH OF THE STRESS STATE OF A MODIFIED IN-SITU CONCRETE

Directory of Open Access Journals (Sweden)

D. V. Rudenko

2016-12-01

Full Text Available Purpose. The article focuses on investigation of the stress state of a modified in-situ concrete of natural hardening. Methodology. To achieve the aim, the research of the microstructure of the modified cement matrix of concrete, as well as the mechanism of structure formation of modified concrete with natural hardening was conducted; the methods for reliable evaluation of concrete strength were defined. Findings. The development of internal stresses affects the properties of concretedifferently. With an increase in temperature-shrinkage deformations in time and, thus, with increasing structural stresses in the cement sheath around the grains of the filler two opposite processes may develop: zone of plastic flow or cracking. Originality. It was established that the structural features complex of the modified concrete when the load transfer leads to the formation of extensive zones of prefracture which is able to absorb a significant amount of elastic strain energy that provides the design deformation properties of the concrete for special purposes. Ideas about the definition of the criteria of cracking modified concrete, hardening under natural conditions had further development. Practical value. The resulting equations allow to solve the problem about the minimum level of structural stress in monolithic concrete in a saturated large placeholder, as well as to assess the influence of structural stresses on the properties of concrete. In normal concrete with a relatively thin cement sheath at temperature-shrinkage deformations, high tangential and low radial tension occur. In vivo, this stress is higher as a result of higher values of Δε(τ, which is not observed in the modified concrete. In the modified concretes only tangential stresses are the greatest danger to structures. The change of shrinkage stress with time is straightforward. The total temperature-shrinkage deformations have a sawtooth graph. For modified concrete the amplitude is 48

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

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.

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, ...

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

International Nuclear Information System (INIS)

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

2014-01-01

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

On The Stress Free Deformation Of Linear FGM Interface Under Constant Temperature

Directory of Open Access Journals (Sweden)

Ganczarski Artur

2015-09-01

Full Text Available This paper demonstrates the stress free thermo-elastic problem of the FGM thick plate. Existence of such a purely thermal deformation is proved in two ways. First proof is based on application of the Iljushin thermo-elastic potential to displacement type system of equations. This reduces 3D problem to the plane stress state problem. Next it is shown that the unique solution fulfils conditions of simultaneous constant temperature and linear gradation of thermal expansion coefficient. Second proof is based directly on stress type system of equations which straightforwardly reduces to compatibility equations for purely thermal deformation. This occurs if only stress field is homogeneous in domain and at boundary. Finally an example of application to an engineering problem is presented.

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....... A total of 404 protein spots, out of 1637 detected, were differentially expressed between the two groups of fish. Mass spectrometry analysis of selected spots suggested that WF diet improved oxidative stress defense, reduced endoplasmic reticulum stress, enhanced metabolic flux through methionine cycle...... and metabolic profiling purposes. Intragroup variability and co-measured information were also used to pinpoint which proteins displayed a stronger relation with fish nutritional state....

Seismicity and stress state in the South China Sea, Indochina and their vicinity

Science.gov (United States)

Zang, Shaoxian; Wu, Zhongliang; Li, Aibing

1992-02-01

The distribution of earthquakes from 1973 to 1982 in the South China Sea, Indochina and their vicinity was studied using the data from I. S. C. It was found that the earthquakes are mainly concentrated along the boundaries of plates. Beside, some of shallow eartqhuakes are distributed in west part of Burma and the boundary between Burma and China, a few of earthquakes occurred in South China Sea. The features of Benioff zone along the boundaries between India plate, Philippine Sea plate and Eurasia plate were studied. The plate do not coupled well under the Java trench and the Philippine trench. The subducted India plate under Burmese range, Andaman—Nicobar arc moves NNE. The fault plane solutions of earthquakes were studied using the first motions of P wave. The stress state on subduction zones and within the area were deduced from the fault plane solutions and the fault movement. It was found that the direction of principal compression axis of stress is in the NNE in west part of Burma, in S—N in south and middle part of Bruma and Thailand, and in NNE or S—N in the South China Sea. It was also found that the stress state has close relation with the interaction of plates.

Effect of different pneumoperitoneum pressure on stress state in patients underwent gynecological laparoscopy

Directory of Open Access Journals (Sweden)

Ai-Yun Shen

2016-10-01

Full Text Available Objective: To observe the effect of different CO2 pneumoperitoneum pressure on the stress state in patients underwent gynecological laparoscopy. Methods: A total of 90 patients who were admitted in our hospital from February, 2015 to October, 2015 for gynecological laparoscopy were included in the study and divided into groups A, B, and C according to different CO2 pneumoperitoneum pressure. The changes of HR, BP, and PetCO2 during the operation process in the three groups were recorded. The changes of stress indicators before operation (T0, 30 min during operation (T1, and 12 h after operation (T2 were compared. Results: The difference of HR, BP, and PetCO2 levels before operation among the three groups was not statistically significant (P>0.05. HR, BP, and PetCO2 levels 30 min after pneumoperitoneum were significantly elevated when compared with before operation (P0.05. PetCO2 level 30 min after pneumoperitoneum in group B was significantly higher than that in group A (P0.05. Conclusions: Low pneumoperitoneum pressure has a small effect on the stress state in patients underwent gynecological laparoscopy, will not affect the surgical operation, and can obtain a preferable muscular relaxation and vision field; therefore, it can be selected in preference.

A contribution of the knowledge of the stress state in sharp notched finite thickness discs

International Nuclear Information System (INIS)

Prantl, G.

1977-06-01

The amount of plane strain in the area of a stress concentration, caused by a sharp notch or a crack, is indicated by the magnitude of the stress perpendicular to the plane of the main dimensions of disk shaped components. A theoretical model is proposed for the calculation of average values of these out-of-plane stresses, which is applicable in case of linear-elastic materials. In the presence of a plastic zone in front of the crack some limited conclusions can be drawn on the basis of the classical crack models, used in fracture mechanics. The out-of-plane stresses in deeply notched specimens, behaving elastically, are determined in two independent series of experiments. The results are compared to the calculated stresses. In order to supplement the knowledge of the strain concentration in case of a plastic behaviour of the material, notched bodies made of lead are tested. (Auth.)

Residual stress mapping by micro X-ray diffraction: Application to the study of thin film buckling

Energy Technology Data Exchange (ETDEWEB)

Goudeau, P.; Villain, P.; Tamura, N.; Celestre, R.S.; Padmore, H.A.

2002-11-06

Thin films deposited by Physical Vapour Deposition techniques on substrates generally exhibit large residual stresses which may be responsible of spontaneous detachment of the film from its substrate and in the case of compressive stresses, thin film buckling. Although these effects are undesirable for future applications, one may take benefit of it for thin film mechanical properties investigation. Since the 80's, a lot of theoretical works have been done to develop mechanical models with the aim to get a better understanding of driven mechanisms giving rise to this phenomenon and thus to propose solutions to avoid such problems. Nevertheless, only a few experimental works have been done on this subject to support these theoretical results and nothing concerning local stress/strain measurement mainly because of the small dimension of the buckling (few tenth mm). This paper deals with the application of micro beam x-ray diffraction available on synchrotron radiation sources for stress/ strain mapping analysis of gold thin film buckling.

State Synchronization Approaches in Web-based Applications

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Grocevs Aleksejs

2014-12-01

Full Text Available The main objective of the article is to provide insight into technologies and approaches available to maintain consistent state on both client and server sides. The article describes basic RIA application state persistence difficulties and offers approaches to overcoming such problems using asynchronous data transmission synchronization channels and other user-available browser abilities.

Solid state nuclear track detection principles, methods and applications

CERN Document Server

Durrani, S A; ter Haar, D

1987-01-01

Solid State Nuclear Track Detection: Principles, Methods and Applications is the second book written by the authors after Nuclear Tracks in Solids: Principles and Applications. The book is meant as an introduction to the subject solid state of nuclear track detection. The text covers the interactions of charged particles with matter; the nature of the charged-particle track; the methodology and geometry of track etching; thermal fading of latent damage trails on tracks; the use of dielectric track recorders in particle identification; radiation dossimetry; and solid state nuclear track detecti

Effect of silicon application on physiological characteristics and growth of wheat (Triticum aestivum L. under drought stress condition

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A. Karmollachaab

2016-05-01

Full Text Available In order to investigate the effect of silicon application on some physiological characteristics and growth of Wheat (Triticum aestivum L. under late drought stress condition, an experiment was conducted at the Agriculture and Natural Resources University of Ramin, Khuzestan during year 2012. The experiment was conducted in the open environment as factorial randomized complete block design with three levels of drought stress (irrigation after 25, 50 and 75% depletion of available water content as the first factor and four levels of silicon (0, 10, 20 and 30 mg Si.kg-1 soil as the second factor with three replications. The results showed that drought stress imposed a negative significant effect on all traits. The drought stress led to increased electrolyte leakage and proline content, cuticular wax, leaf silicon concentration, superoxide dismutase activity (SOD and grain potassium were decreased. The severe drought stress has most effect on electrolyte leakage (up to 53%. The application of silicon except the shoot/root parameter, on all characters have been affected so that application of 30 mg Si.kg-1 soil led to decrease electrolyte leakage up to 22.5% and increased SOD activity, proline content, cuticular wax grain K and flag leaf Si concentration, 25, 12.8, 21, 17 and 30% compared to control, respectively. In general, the results showed a positive effect of silicon on wheat plant under stress conditions that were higher than no stress condition.

State anxiety, psychological stress and positive well-being responses to yoga and aerobic exercise in people with schizophrenia: a pilot study.

Science.gov (United States)

Vancampfort, Davy; De Hert, Marc; Knapen, Jan; Wampers, Martien; Demunter, Hella; Deckx, Seppe; Maurissen, Katrien; Probst, Michel

2011-01-01

Worsening of schizophrenia symptoms is related to stress and anxiety. People with schizophrenia often experience difficulties in coping with stress and possess a limited repertoire of coping strategies. A randomised comparative trial was undertaken in patients with schizophrenia to evaluate changes in state anxiety, psychological stress and subjective well-being after single sessions of yoga and aerobic exercise compared with a control condition. Forty participants performed a single 30-min yoga session, 20-min of aerobic exercise on a bicycle ergometre at self-selected intensity and a 20-min no exercise control condition in random order. After single sessions of yoga and aerobic exercise individuals with schizophrenia or schizoaffective disorder showed significantly decreased state anxiety (p stress (p exercise control condition. Effect sizes ranged from 0.82 for psychological stress after aerobic exercise to 1.01 for state anxiety after yoga. The magnitude of the changes did not differ significantly between yoga and aerobic exercise. People with schizophrenia and physiotherapists can choose either yoga or aerobic exercise in reducing acute stress and anxiety taking into account the personal preference of each individual.

State Waste Discharge Permit application, 100-N Sewage Lagoon

International Nuclear Information System (INIS)

1994-06-01

As part of the Hanford Federal Facility Agreement and Consent Order negotiations (Ecology et al. 1994), the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173--216 (or 173--218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. As a result of this decision, the Washington State Department of Ecology and the US Department of Energy, Richland Operations Office entered into Consent Order No. DE 91NM-177, (Ecology and DOE-RL 1991). This document constitutes the State Waste Discharge Permit application for the 100-N Sewage Lagoon. Since the influent to the sewer lagoon is domestic waste water, the State Waste Discharge Permit application for Public Owned Treatment Works Discharges to Land was used. Although the 100-N Sewage Lagoon is not a Public Owned Treatment Works, the Public Owned Treatment Works application is more applicable than the application for industrial waste water. The 100-N Sewage Lagoon serves the 100-N Area and other Hanford Site areas by receiving domestic waste from two sources. A network of sanitary sewer piping and lift stations transfers domestic waste water from the 100-N Area buildings directly to the 100-N Sewage Lagoon. Waste is also received by trucks that transport domestic waste pumped from on site septic tanks and holding tanks. Three ponds comprise the 100-N Sewage Lagoon treatment system. These include a lined aeration pond and stabilization pond, as well as an unlined infiltration pond. Both piped-in and trucked-in domestic waste is discharged directly into the aeration pond

Stress among Accounting Educators in the United States.

Science.gov (United States)

Seiler, Robert E.; Pearson, Della A.

1984-01-01

Stress among accounting educators was investigated and relationships between stress levels and work satisfaction levels, personality traits, and stress-coping techniques were examined. The most important personality charcteristics of higher stress individuals were impatience, assertiveness, workaholism, and idealism. (Author/MLW)

The intersection of stress and reward: BNST modulation of aversive and appetitive states.

Science.gov (United States)

Ch'ng, Sarah; Fu, Jingjing; Brown, Robyn M; McDougall, Stuart J; Lawrence, Andrew J

2018-01-09

The bed nucleus of the stria terminalis (BNST) is widely acknowledged as a brain structure that regulates stress and anxiety states, as well as aversive and appetitive behaviours. The diverse roles of the BNST are afforded by its highly modular organisation, neurochemical heterogeneity, and complex intrinsic and extrinsic circuitry. There has been growing interest in the BNST in relation to psychopathologies such as anxiety and addiction. Although research on the human BNST is still in its infancy, there have been extensive preclinical studies examining the molecular signature and hodology of the BNST and their involvement in stress and reward seeking behaviour. This review examines the neurochemical phenotype and connectivity of the BNST, as well as electrophysiological correlates of plasticity in the BNST mediated by stress and/or drugs of abuse. Copyright © 2018 Elsevier Inc. All rights reserved.

Regional homogeneity and resting state functional connectivity: associations with exposure to early life stress.

Science.gov (United States)

Philip, Noah S; Kuras, Yuliya I; Valentine, Thomas R; Sweet, Lawrence H; Tyrka, Audrey R; Price, Lawrence H; Carpenter, Linda L

2013-12-30

Early life stress (ELS) confers risk for psychiatric illness. Previous literature suggests ELS is associated with decreased resting-state functional connectivity (rs-FC) in adulthood, but there are no studies of resting-state neuronal activity in this population. This study investigated whether ELS-exposed individuals demonstrate resting-state activity patterns similar to those found in PTSD. Twenty-seven adults (14 with at least moderate ELS), who were medication-free and without psychiatric or medical illness, underwent MRI scans during two 4-minute rest periods. Resting-state activity was examined using regional homogeneity (ReHo), which estimates regional activation patterns through indices of localized concordance. ReHo values were compared between groups, followed by rs-FC analyses utilizing ReHo-localized areas as seeds to identify other involved regions. Relative to controls, ELS subjects demonstrated diminished ReHo in the inferior parietal lobule (IPL) and superior temporal gyrus (STG). ReHo values were inversely correlated with ELS severity. Secondary analyses revealed decreased rs-FC between the IPL and right precuneus/posterior cingulate, left fusiform gyrus, cerebellum and caudate in ELS subjects. These findings indicate that ELS is associated with altered resting-state activity and connectivity in brain regions involved in trauma-related psychiatric disorders. Future studies are needed to evaluate whether these associations represent potential imaging biomarkers of stress exposure. Published by Elsevier Ireland Ltd.

Stress states in the Zagros fold-and-thrust belt from passive margin to collisional tectonic setting

Science.gov (United States)

Navabpour, Payman; Barrier, Eric

2012-12-01

The present-day Zagros fold-and-thrust belt of SW-Iran corresponds to the former Arabian passive continental margin of the southern Neo-Tethyan basin since the Permian-Triassic rifting, undergoing later collisional deformation in mid-late Cenozoic times. In this paper an overview of brittle tectonics and palaeostress reconstructions of the Zagros fold-and-thrust belt is presented, based on direct stress tensor inversion of fault slip data. The results indicate that, during the Neo-Tethyan oceanic opening, an extensional tectonic regime affectedthe sedimentary cover in Triassic-Jurassic times with an approximately N-S trend of the σ3 axis, oblique to the margin, which was followed by some local changes to a NE-SW trend during Jurassic-Cretaceous times. The stress state significantly changed to thrust setting, with a NE-SW trend of the σ1 axis, and a compressional tectonic regime prevailed during the continental collision and folding of the sedimentary cover in Oligocene-Miocene times. This compression was then followed by a strike-slip stress state with an approximately N-S trend of the σ1 axis, oblique to the belt, during inversion of the inherited extensional basement structures in Pliocene-Recent times. The brittle tectonic reconstructions, therefore, highlighted major changes of the stress state in conjunction with transitions between thin- and thick-skinned structures during different extensional and compressional stages of continental deformation within the oblique divergent and convergent settings, respectively.

Failure prevention with stress measurement for dismantling of nuclear facilities. Final report

International Nuclear Information System (INIS)

Komber, T.; Reimche, W.; Bach, F.W.

2003-07-01

The dismantling of nuclear facilities is in progress since 20 years in Germany. Practical experiences in decommissioning have shown, that problem can occur during dismantling operations caused by release of residual stresses. In this case cutting parts or cutting tools get jammed if mechanical cutting techniques are used. The aim of this research work was to develop measuring techniques for the determination of the stress state in RPV, to predict the deformation during dismantling operations. This can serve as additional base for improved decommissioning planning and for time optimised dismantling. For determination of the stress state in components two small and inexpensive measuring techniques were new designed, for remote-controlled on-site use in atmosphere and under water. For the nondestructive determination of the directional stress state, based on the magnetostriction and the Harmonic-Analysis of alternating magnetic fields, a new developed rotating sensor is in use with a principal magnetisation direction. Because of the mainly isotropic material properties and the directional stresses, measured Harmonic values are influenced mainly by the stress state in the surface areas. In this way it is possible to determine the stress state qualitatively and the direction of principal stresses in the surface areas of the component. As an alternative to the established wire strain gauge, which remote-controlled application is still not possible under water, a new slot jet cutting strain control technique was designed. This technique detects the deformation in the surface after stresses are cut free by a water jet. So the stress state could be determined quantitatively in the surface and assessed in the depth. With the help of these two measuring techniques it is possible to characterize the stress state along a planned cutting line. The use of an adapted FEM simulation enables to calculate and determine the deformation of the cutting gap beforehand. These information

The state of stress in British rocks

International Nuclear Information System (INIS)

Klein, R.J.; Brown, E.T.

1983-03-01

When designing underground works, it is necessary to take account of not only the vertical stresses arising predictably from the weight of the rock overhead, but also horizontal stresses which may vary from one direction to another as a result of past tectonic action. This report discussed the techniques that have been used to measure such stresses. Few determinations have been made in Great Britain, so it has been necessary to augment what little is known by reference to fault systems, relying on correlations between the measured magnitude and direction of maximum horizontal stress with local tectonic history. This has enabled general conclusions to be reached for Great Britain. (author)

Prospective Analysis of Risk Factors Related to Depression and Post Traumatic Stress Disorder in Deployed United States Navy Personnel

Science.gov (United States)

2011-03-28

post traumatic stress disorder ( PTSD ) and depression (MDD) than...United States Several epidemiological studies have been conducted on the prevalence of post traumatic stress disorder ( PTSD ) and major depression in...forms contain the same 4-item screener for post - traumatic stress disorder ( PTSD ). This screener was developed by the National Center for PTSD and

Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

Directory of Open Access Journals (Sweden)

Yao Qiangling

2015-01-01

Full Text Available The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out to study the effect of the coal mass strength, coal seam depth, immediate roof strength, and thickness on the distribution of the side abutment stress. Based on the research results, we determined the reasonable position of the mining roadway and the optimal width of the barrier pillar. The engineering application demonstrates that the retention of the barrier pillar with a width of 5 m along the gob as the haulage roadway for the next panel is feasible, which delivers favorable technological and economic benefits.

Main results of BN-600 reactor stress-strain state investigations

International Nuclear Information System (INIS)

Panov, V.A.

1983-01-01

The development of BN-600 fast reactor plant needed the solution of a series of complex engineering problems including ones for confirming integrity of the most vital structural components. The particular attention was given to the main vessel since reactor availability end safe operation of the plant as a whole depend on vessel strength end integrity. The present report deals with the main results of theoretical and experimental investigations of the stress-strain state of BN-600 reactor vessel carried out during design, start-up and initial bringing the reactor to power

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.

Mindfulness meditation training alters stress-related amygdala resting state functional connectivity: a randomized controlled trial.

Science.gov (United States)

Taren, Adrienne A; Gianaros, Peter J; Greco, Carol M; Lindsay, Emily K; Fairgrieve, April; Brown, Kirk Warren; Rosen, Rhonda K; Ferris, Jennifer L; Julson, Erica; Marsland, Anna L; Bursley, James K; Ramsburg, Jared; Creswell, J David

2015-12-01

Recent studies indicate that mindfulness meditation training interventions reduce stress and improve stress-related health outcomes, but the neural pathways for these effects are unknown. The present research evaluates whether mindfulness meditation training alters resting state functional connectivity (rsFC) of the amygdala, a region known to coordinate stress processing and physiological stress responses. We show in an initial discovery study that higher perceived stress over the past month is associated with greater bilateral amygdala-subgenual anterior cingulate cortex (sgACC) rsFC in a sample of community adults (n = 130). A follow-up, single-blind randomized controlled trial shows that a 3-day intensive mindfulness meditation training intervention (relative to a well-matched 3-day relaxation training intervention without a mindfulness component) reduced right amygdala-sgACC rsFC in a sample of stressed unemployed community adults (n = 35). Although stress may increase amygdala-sgACC rsFC, brief training in mindfulness meditation could reverse these effects. This work provides an initial indication that mindfulness meditation training promotes functional neuroplastic changes, suggesting an amygdala-sgACC pathway for stress reduction effects. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

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.

Stress og aldring

DEFF Research Database (Denmark)

Jørgensen, Anders; Jørgensen, Martin Balslev; Poulsen, Henrik Enghusen

2012-01-01

Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders....... These effects are likely mediated by the secretion of stress hormones. In this short review we focus on biochemical and epidemiological evidence for a link between stress and aging.......Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders...

Type I and type II residual stress in iron meteorites determined by neutron diffraction measurements

Science.gov (United States)

Caporali, Stefano; Pratesi, Giovanni; Kabra, Saurabh; Grazzi, Francesco

2018-04-01

In this work we present a preliminary investigation by means of neutron diffraction experiment to determine the residual stress state in three different iron meteorites (Chinga, Sikhote Alin and Nantan). Because of the very peculiar microstructural characteristic of this class of samples, all the systematic effects related to the measuring procedure - such as crystallite size and composition - were taken into account and a clear differentiation in the statistical distribution of residual stress in coarse and fine grained meteorites were highlighted. Moreover, the residual stress state was statistically analysed in three orthogonal directions finding evidence of the existence of both type I and type II residual stress components. Finally, the application of von Mises approach allowed to determine the distribution of type II stress.

Development and Application of a Low-Volume Flow System for Solution-State in Vivo NMR.

Science.gov (United States)

Tabatabaei Anaraki, Maryam; Dutta Majumdar, Rudraksha; Wagner, Nicole; Soong, Ronald; Kovacevic, Vera; Reiner, Eric J; Bhavsar, Satyendra P; Ortiz Almirall, Xavier; Lane, Daniel; Simpson, Myrna J; Heumann, Hermann; Schmidt, Sebastian; Simpson, André J

2018-06-18

In vivo nuclear magnetic resonance (NMR) spectroscopy is a particularly powerful technique, since it allows samples to be analyzed in their natural, unaltered state, criteria paramount for living organisms. In this study, a novel continuous low-volume flow system, suitable for in vivo NMR metabolomics studies, is demonstrated. The system allows improved locking, shimming, and water suppression, as well as allowing the use of trace amounts of expensive toxic contaminants or low volumes of precious natural environmental samples as stressors. The use of a double pump design with a sump slurry pump return allows algal food suspensions to be continually supplied without the need for filters, eliminating the possibility of clogging and leaks. Using the flow system, the living organism can be kept alive without stress indefinitely. To evaluate the feasibility and applicability of the flow system, changes in the metabolite profile of 13 C enriched Daphnia magna over a 24-h period are compared when feeding laboratory food vs exposing them to a natural algal bloom sample. Clear metabolic changes are observed over a range of metabolites including carbohydrates, lipids, amino acids, and a nucleotide demonstrating in vivo NMR as a powerful tool to monitor environmental stress. The particular bloom used here was low in microcystins, and the metabolic stress impacts are consistent with the bloom being a poor food source forcing the Daphnia to utilize their own energy reserves.

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

KAUST Repository

Goudarzy, M.; Kö nig, D.; Santamarina, Carlos; Schanz, T.

2017-01-01

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

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.

Stress factors for the deformation systems of zirconium under multiaxial stress

International Nuclear Information System (INIS)

Hobson, D.O.

1976-01-01

Calculation of the resolved shear stresses (rss) that act on various deformation systems in metals and, in particular, the determination of those systems subjected to the highest rss by a given set of multiaxial stresses is of importance in the study of texture development, yielding and plastic flow. This study examines the geometrical influences of any stress state on the deformation modes of zirconium. One slip mode and three twinning modes, comprising twenty-one deformation systems, are considered. Stress factors computed for these systems are shown on a coordinate system that allows specimen orientation, most highly stressed deformation system, and stress factor to be shown without ambiguity. The information in this report allows the determination of the rss that results from any multiaxial stress state; this information also allows the prediction of the deformation modes that might operate for any specimen orientation in that strss state

On the impact of multi-axial stress states on trailing edge bondlines in wind turbine rotor blades

Science.gov (United States)

Noever Castelos, Pablo; Balzani, Claudio

2016-09-01

For a reliable design of wind turbine systems all of their components have to be designed to withstand the loads appearing in the turbine's lifetime. When performed in an integral manner this is called systems engineering, and is exceptionally important for components that have an impact on the entire wind turbine system, such as the rotor blade. Bondlines are crucial subcomponents of rotor blades, but they are not much recognized in the wind energy research community. However, a bondline failure can lead to the loss of a rotor blade, and potentially of the entire turbine, and is extraordinarily relevant to be treated with strong emphasis when designing a wind turbine. Modern wind turbine rotor blades with lengths of 80 m and more offer a degree of flexibility that has never been seen in wind energy technology before. Large deflections result in high strains in the adhesive connections, especially at the trailing edge. The latest edition of the DNV GL guideline from end of 2015 demands a three-dimensional stress analysis of bondlines, whereas before an isolated shear stress proof was sufficient. In order to quantify the lack of safety from older certification guidelines this paper studies the influence of multi-axial stress states on the ultimate and fatigue load resistance of trailing edge adhesive bonds. For this purpose, detailed finite element simulations of the IWES IWT-7.5-164 reference wind turbine blades are performed. Different yield criteria are evaluated for the prediction of failure and lifetime. The results show that the multi-axial stress state is governed by span-wise normal stresses. Those are evidently not captured in isolated shear stress proofs, yielding non-conservative estimates of lifetime and ultimate load resistance. This finding highlights the importance to include a three-dimensional stress state in the failure analysis of adhesive bonds in modern wind turbine rotor blades, and the necessity to perform a three-dimensional characterization

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. 

Symptoms of Psychological Distress and Post-Traumatic Stress Disorder in United States Air Force Drone Operators

Science.gov (United States)

2014-08-01

Disorder in United States Air Force “ Drone ” Operators 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...referred to as “ drones .” Participants were assessed for self-reported sources of occupational stress, levels of clinical distress using the Outcome...providers are discussed. 15. SUBJECT TERMS Stress, drone operator, PTSD, USAF 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT

Mechanisms of stress generation and relaxation during pulsed laser deposition of epitaxial Fe-Pd magnetic shape memory alloy films on MgO

International Nuclear Information System (INIS)

Edler, Tobias; Mayr, S G; Buschbeck, Joerg; Mickel, Christine; Faehler, Sebastian

2008-01-01

Mechanical stress generation during epitaxial growth of Fe-Pd thin films on MgO from pulsed laser deposition is a key parameter for the suitability in shape memory applications. By employing in situ substrate curvature measurements, we determine the stress states as a function of film thickness and composition. Depending on composition, different stress states are observed during initial film growth, which can be attributed to different misfits. Compressive stress generation by atomic peening is observed in the later stages of growth. Comparison with ex situ x-ray based strain measurements allows integral and local stress to be distinguished and yields heterogeneities of the stress state between coherent and incoherent regions. In combination with cross-sectional TEM measurements the relevant stress relaxation mechanism is identified to be stress-induced martensite formation with (111) twinning

Update in the methodology of the chronic stress paradigm: internal control matters

Directory of Open Access Journals (Sweden)

Boyks Marco

2011-04-01

Full Text Available Abstract To date, the reliability of induction of a depressive-like state using chronic stress models is confronted by many methodological limitations. We believe that the modifications to the stress paradigm in mice proposed herein allow some of these limitations to be overcome. Here, we discuss a variant of the standard stress paradigm, which results in anhedonia. This anhedonic state was defined by a decrease in sucrose preference that was not exhibited by all animals. As such, we propose the use of non-anhedonic, stressed mice as an internal control in experimental mouse models of depression. The application of an internal control for the effects of stress, along with optimized behavioural testing, can enable the analysis of biological correlates of stress-induced anhedonia versus the consequences of stress alone in a chronic-stress depression model. This is illustrated, for instance, by distinct physiological and molecular profiles in anhedonic and non-anhedonic groups subjected to stress. These results argue for the use of a subgroup of individuals who are negative for the induction of a depressive phenotype during experimental paradigms of depression as an internal control, for more refined modeling of this disorder in animals.

Update in the methodology of the chronic stress paradigm: internal control matters.

Science.gov (United States)

Strekalova, Tatyana; Couch, Yvonne; Kholod, Natalia; Boyks, Marco; Malin, Dmitry; Leprince, Pierre; Steinbusch, Harry Mw

2011-04-27

To date, the reliability of induction of a depressive-like state using chronic stress models is confronted by many methodological limitations. We believe that the modifications to the stress paradigm in mice proposed herein allow some of these limitations to be overcome. Here, we discuss a variant of the standard stress paradigm, which results in anhedonia. This anhedonic state was defined by a decrease in sucrose preference that was not exhibited by all animals. As such, we propose the use of non-anhedonic, stressed mice as an internal control in experimental mouse models of depression. The application of an internal control for the effects of stress, along with optimized behavioural testing, can enable the analysis of biological correlates of stress-induced anhedonia versus the consequences of stress alone in a chronic-stress depression model. This is illustrated, for instance, by distinct physiological and molecular profiles in anhedonic and non-anhedonic groups subjected to stress. These results argue for the use of a subgroup of individuals who are negative for the induction of a depressive phenotype during experimental paradigms of depression as an internal control, for more refined modeling of this disorder in animals.

An interfacial stress sensor for biomechanical applications

International Nuclear Information System (INIS)

Sundara-Rajan, K; Bestick, A; Rowe, G I; Mamishev, A V; Klute, G K; Ledoux, W R; Wang, H C

2012-01-01

This paper presents a capacitive sensor that measures interfacial forces in prostheses and is promising for other biomedical applications. These sensors can be integrated into prosthetic devices to measure both normal and shear stress simultaneously, allowing for the study of prosthetic limb fit, and ultimately for the ability to better adapt prosthetics to individual users. A sensing cell with a 1.0 cm 2 spatial resolution and a measurement range of 0–220 kPa of shear and 0–2 MPa of pressure was constructed. The cell was load tested and found to be capable of isolating the applied shear and pressure forces. This paper discusses the construction of the prototype, the mechanical and electrode design, fabrication and characterization. The work presented is aimed at creating a class of adaptive prosthetic interfaces using a capacitive sensor. (paper)

Analysis and measurement of residual stress distribution of vanadium/ceramics joints for fusion reactor applications

International Nuclear Information System (INIS)

Nemoto, Y.; Ueda, K.

1998-01-01

Vanadium alloys are considered as candidate structural materials for fusion reactor system. When vanadium alloys are used in fusion reactor system, joining with ceramics for insulating is one of material issues to be solved to make component of fusion reactor. In the application of ceramics/metal jointing and coating, residual stress caused by difference of thermal expansion rate between ceramics and metals is an important factor in obtaining good bonding strength and soundness of coating. In this work, residual stress distribution in direct diffusion bonded vanadium/alumina joint (jointing temperature: 1400 C) was measured by small area X-ray diffraction method. And the comparison of finite element method (FEM) analysis and actual stress distribution was carried out. Tensile stress concentration at the edge of the boundary of the joint in alumina was observed. The residual stress concentration may cause cracks in alumina, or failure of bonding. Actually, cracks in alumina caused by thermal stress after bonding at 1500 C was observed. The stress concentration of the joint must be reduced to obtain good bonded joint. Lower bonding temperature or to devise the shape of the outer surface of the joint will reduce the stress concentration. (orig.)

Pressure and Stress Prediction in the Nankai Accretionary Prism: A Critical State Soil Mechanics Porosity-Based Approach

Science.gov (United States)

Flemings, Peter B.; Saffer, Demian M.

2018-02-01

We predict pressure and stress from porosity in the Nankai accretionary prism with a critical state soil model that describes porosity as a function of mean stress and maximum shear stress, and assumes Coulomb failure within the wedge and uniaxial burial beneath it. At Ocean Drilling Program Sites 1174 and 808, we find that pore pressure in the prism supports 70% to 90% of the overburden (λu = 0.7 to 0.9), for a range of assumed friction angles (5-30°). The prism pore pressure is equal to or greater than that in the underthrust sediments even though the porosity is lower within the prism. The high pore pressures lead to a mechanically weak wedge that supports low maximum shear stress, and this in turn requires very low basal traction to remain consistent with the observed narrowly tapered wedge geometry. We estimate the décollement friction coefficient (μb) to be 0.08-0.38 (ϕb' = 4.6°-21°). Our approach defines a pathway to predict pressure in a wide range of environments from readily observed quantities (e.g., porosity and seismic velocity). Pressure and stress control the form of the Earth's collisional continental margins and play a key role in its greatest earthquakes. However, heretofore, there has been no systematic approach to relate material state (e.g., porosity), pore pressure, and stress in these systems.

Calculation of a steam generating tube stressed state under temperature oscillations in burnout zone

International Nuclear Information System (INIS)

Vorob'ev, V.A.; Loshchinin, V.M.; Remizov, O.V.

1982-01-01

The technique for evaluating the steam generating tube stressed state under the wall temperature oscillations in the burnout zone is described. The technique is based on analytical solutions for transfer functions connecting the amplitude of surface temperature oscillation with the amplitude and frequency of heat transfer coefficient oscillation and amplitude of thermoelastic stress oscillation with that of temperature oscillation. The results of calculations according to considered technique are compared with that of the problem numerical solution. The conclusion is made that the technique under consideration may be applied for evaluation of steam generator evaporating tube lifetime [ru

Analysis of internal stress and anelasticity in the shock-compressed state from unloading wave data

International Nuclear Information System (INIS)

Johnson, J.N.; Lomdahl, P.S.; Wills, J.M.

1991-01-01

This paper reports on time resolved shock-wave measurements have often been used to infer microstructural behavior in crystalline solids. The authors apply this approach to an interpretation of the release-wave response of an aluminum alloy (6061-T6) as it is dynamically unloaded from a shock-compressed state of 20.7 GPa. The anelastic behavior in the initial portion of the unloading wave is attributed to the accumulation of internal stresses created by the shock process. Specific internal-stress models which are investigated are the double pile-up, the single pile-up, and single dislocation loops between pinning points. It is found that the essential characteristics of double and single pile-ups can be represented by a single dislocation between two pinned dislocations of like sing. Calculations of anelastic wave speeds at constant unloading strain rate are then compared with experimental data. The results suggest that the residual internal stress is due to pinned loops of density 10 15 M - 2 , and the viscous drag coefficient in the shock-compressed state is on the order of 10 - 7 MPa s (approximately two orders of magnitude greater than expected under ambient conditions)

New developments of the Integrated Stress Determination Method and application to the Aespoe Hard Rock Laboratory, Sweden

International Nuclear Information System (INIS)

Ask, Daniel

2004-04-01

This thesis presents new developments of the Integrated Stress Determination Method (ISDM) with application to the Aespoe Hard Rock Laboratory (HRL), Oskarshamn, Sweden. The new developments involve a 12-parameter representation of the regional stress field in the rock mass. The method is applicable to data from hydraulic fracturing, hydraulic tests on pre-existing fractures (HTPF), and overcoring data from CSIR- and CSIRO-type of devices. When hydraulic fracturing/HTPF data are combined with overcoring data, the former may be used to constrain the elastic parameters, i.e. the problem involves 14 model parameters. The Swedish Nuclear Fuel and Waste Management Co. (SKB), have conducted a vast amount of rock stress measurements at the Aespoe HRL since the late 1980s. However, despite the large number of stress measurement data collected in this limited rock volume, variability in the stress field exists. Not only does the result vary depending on measuring technique, e.g. overcoring data indicated larger stress magnitudes compared to hydraulic fracturing data; the results are also affected by existing discontinuities, indicated by non-linear stress magnitudes and orientations versus depth. The objectives for this study are therefore threefold: (1) find explanations to the observed differences between existing hydraulic and overcoring stress data at the Aspo HRL; (2) explain the non-linear stress distribution indicated by existing stress data; and (3) apply the ISDM, including the new developments, based on the results obtained in step 1 and 2. To evaluate the observed differences between existing hydraulic and overcoring stress data, a detailed re-interpretation was conducted. Several measurement-related uncertainties were identified and corrected for when possible, which effectively reduced the discrepancies between the hydraulic and overcoring measuring results. Modeling studies managed by SKB have shown that the redistribution of the stresses at Aespoe HRL to a

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

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…

Application of secondary and residual stresses to the assessment of the structural integrity of nuclear power-generating plant

International Nuclear Information System (INIS)

Banahan, B.D.

2008-01-01

Magnox nuclear power stations were built in the 1960s to design codes that, in general, required weldments to be subject to a post-weld heat treatment to remove residual stresses. Implicit in this was the assumption that the heat treatment reduced the stresses significantly such that as stated in the codes 'stresses caused by fabrication and welding are practically annulled'. However, it has since been realised that the stresses remaining, although small, could still be significant when incorporated into the subsequently developed failure avoidance methodologies such as R6. Moreover, either at the time of construction or during the operating life, repairs are undertaken to remove manufacturing or service-induced defects. These repairs can be put into service with or without a post-weld heat treatment. As a consequence of a paucity of data for the two- and three-dimensional distribution of the magnitude of these stresses, extremely conservative values of stresses have been adopted to ensure that the plant is secure against the design intent throughout the service life. In this paper, the requirements of the failure-avoidance methodology R6 Revision 4 are briefly reviewed with respect to the categorisation of secondary and residual stresses and the application of the three approaches for determining the as-welded residual stress distribution at room temperature. These three levels comprise, Level 1, simple estimates, Level 2, bounding profiles, and Level 3, detailed evaluation. Examples are presented where knowledge of the residual stresses has been an important component of the overall integrity assessment. The first relates to multi-pass weldments in superheater headers fabricated from a ferritic steel and the second to the weldments in the standpipes, both at Magnox power stations with concrete pressure vessels. Although in these cases the weldments had been subject to a post-weld heat treatment, the remaining residual stresses presented a significant challenge to

Foliar application of ascorbic acid mitigates sodium chloride induced stress in eggplant (solanum melongena l.)

International Nuclear Information System (INIS)

Jan, S.; Hamayun, M.

2016-01-01

The current work was designed to test the effect of sodium chloride on germination, seedling establishment, vegetative growth, yield, chemical contents and ionic composition of eggplant. The consequences of foliar application of ascorbic acid (AA) on mitigation of adverse effects of sodium chloride were also tested. The seeds of Solanum melongena were germinated using NaCl (60 mM, 100 mM) and ascorbic acid (100 and 200 mM). High levels of salinity significantly affected the seed germination and seedling fresh and dry weights. Plants grown under salinity stress with foliar application of ascorbic acid showed significant increase in germination percentage and seedlings growth as compare to control plants. Sodium chloride stress showed adverse effects on plant height, root length, number of leaves, leaf area, fresh and dry biomass, total chlorophyll, carbohydrates and proteins as compared to untreated plants. The relative water content, electrolyte leakage were increased and Na+ and K+ ions balance was disturbed in different plant parts. Ascorbic acid (100 and 200ppm) enhanced all the growth parameters affected adversely by sodium chloride stress. (author)

Slow strain rate stress corrosion cracking under multiaxial deformation conditions: technique and application to admiralty brass

International Nuclear Information System (INIS)

Blanchard, W.K.; Heldt, L.A.; Koss, D.

1984-01-01

A set of straightforward experimental techniques are described for the examination of slow strain rate stress corrosion cracking (SCC) of sheet deforming under nearly all multiaxial deformation conditions which result in sheet thinning. Based on local fracture strain as a failure criterion, the results contrast stress corrosion susceptibility in uniaxial tension with those in both plane strain and balanced biaxial tension. These results indicate that the loss of ductility of the brass increases as the stress state changes from uniaxial toward balanced biaxial tension

Application of hydraulic fracturing to determine virgin in situ stress state around Waste Isolation Pilot Plant - in situ measurements

International Nuclear Information System (INIS)

Wawersik, W.R.; Stone, C.M.

1985-10-01

Hydraulic fracturing tests were carried out in horizontal drillholes in rock salt in the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. It was determined that the virgin in situ stress field is isotropic or nearly isotropic. The inferred magnitude of the isotropic in situ stress falls between bounds of 14.28 MPa and 17.9 MPa for the average breakdown/reopening pressures and driving pressures. The best estimate from instantaneous shut-in pressures is 16.61 MPa. Given some uncertainties about the interpretation of hydraulic fracturing data in salt, all of the foregoing values are in acceptable agreement with an average calculated isotropic in situ stress of 14.9 MPa at an average depth of 657 m below surface. Interpretations of breakdown and reopening pressures are based on finite element analyses of the relaxed stress field around a borehole in salt. This stress field varies little between approximately 50 and 200 days after drilling. The finite element analyses were also used to interpret the observed stable pressure-time signatures with little or no pressure drops during primary breakdown of the salt formation. The conclusion about the isotropic nature of the virgin in situ stress field is supported by observations of the induced fracture patterns. The report includes a comparison of the hydrofrac data in the WIPP with the published results of hydraulic fracturing tests in salt at three other locations. 75 refs., 21 figs., 4 tabs

Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

CERN Document Server

Topolov, Vitaly

2012-01-01

The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

THE STRESS-STRAIN STATE OF ELASTIC HALF-SPACE FROM RUNNING LINEAR LOAD ACTING ON THE LIMITED AND UNLIMITED EXTENT OVER ITS SURFACE

Directory of Open Access Journals (Sweden)

I. K. Badalakha

2009-02-01

Full Text Available The article shows the result of solving the problem of stress-strain state of an elastic half-space because of the load action that uniformly distributed over the line, with the use of untraditional linear dependence of deformations on stressed state that is different from the generalized Hooke’s law.

Stress state and movement potential of the Kar-e-Bas fault zone, Fars, Iran

Science.gov (United States)

Sarkarinejad, Khalil; Zafarmand, Bahareh

2017-08-01

The Kar-e-Bas or Mengharak basement-inverted fault is comprised of six segments in the Zagros foreland folded belt of Iran. In the Fars region, this fault zone associated with the Kazerun, Sabz-Pushan and Sarvestan faults serves as a lateral transfer zone that accommodates the change in shortening direction from the western central to the eastern Zagros. This study evaluates the recent tectonic stress regime of the Kar-e-Bas fault zone based on inversion of earthquake focal mechanism data, and quantifies the fault movement potential of this zone based on the relationship between fault geometric characteristics and recent tectonic stress regimes. The trend and plunge of σ 1 and σ 3 are S25°W/04°-N31°E/05° and S65°E/04°-N60°W/10°, respectively, with a stress ratio of Φ = 0.83. These results are consistent with the collision direction of the Afro-Arabian continent and the Iranian microcontinent. The near horizontal plunge of maximum and minimum principle stresses and the value of stress ratio Φ indicate that the state of stress is nearly strike-slip dominated with little relative difference between the value of two principal stresses, σ 1 and σ 2. The obliquity of the maximum compressional stress into the fault trend reveals a typical stress partitioning of thrust and strike-slip motion in the Kar-e-Bas fault zone. Analysis of the movement potential of this fault zone shows that its northern segment has a higher potential of fault activity (0.99). The negligible difference between the fault-plane dips of the segments indicates that their strike is a controlling factor in the changes in movement potential.

The triplet excited state of Bodipy: formation, modulation and application.

Science.gov (United States)

Zhao, Jianzhang; Xu, Kejing; Yang, Wenbo; Wang, Zhijia; Zhong, Fangfang

2015-12-21

Boron dipyrromethene (Bodipy) is one of the most extensively investigated organic chromophores. Most of the investigations are focused on the singlet excited state of Bodipy, such as fluorescence. In stark contrast, the study of the triplet excited state of Bodipy is limited, but it is an emerging area, since the triplet state of Bodipy is tremendously important for several areas, such as the fundamental photochemistry study, photodynamic therapy (PDT), photocatalysis and triplet-triplet annihilation (TTA) upconversion. The recent developments in the study of the production, modulation and application of the triplet excited state of Bodipy are discussed in this review article. The formation of the triplet state of Bodipy upon photoexcitation, via the well known approach such as the heavy atom effect (including I, Br, Ru, Ir, etc.), and the new methods, such as using a spin converter (e.g. C60), charge recombination, exciton coupling and the doubly substituted excited state, are summarized. All the Bodipy-based triplet photosensitizers show strong absorption of visible or near IR light and the long-lived triplet excited state, which are important for the application of the triplet excited state in PDT or photocatalysis. Moreover, the methods for switching (or modulation) of the triplet excited state of Bodipy were discussed, such as those based on the photo-induced electron transfer (PET), by controlling the competing Förster-resonance-energy-transfer (FRET), or the intermolecular charge transfer (ICT). Controlling the triplet excited state will give functional molecules such as activatable PDT reagents or molecular devices. It is worth noting that switching of the singlet excited state and the triplet state of Bodipy may follow different principles. Application of the triplet excited state of Bodipy in PDT, hydrogen (H2) production, photoredox catalytic organic reactions and TTA upconversion were discussed. The challenges and the opportunities in these areas were

Overview and applicability of residual stress estimation of film-substrate structure

International Nuclear Information System (INIS)

Chou, Tsung-Lin; Yang, Shin-Yueh; Chiang, Kuo-Ning

2011-01-01

Residual stresses arising from thermal mismatch in layered structures rank among the major causes of mechanical failures in light-emitting diodes, integrated circuits, electronic packages, and micro-electro-mechanical systems. Applying analytical solutions to predict or calculate residual stresses' magnitude and distribution in multilayer film-substrate system has been widely adopted by many researchers. These researches are based on multilayer theories of film-substrate systems, such as Suhir's formula, Stoney's equation, and extend Stoney's equations. To discuss and distinguish the characteristics of these approaches, finite element analysis numerical solutions and multilayer theory analytical solutions are compared and analyzed. This encompasses the theories' application spectrum as well as their prediction capability. In addition, this work not only discusses the theories' property and workability but also demonstrate the feasibility of the finite element method (FEM) and bilayer theories in experiment. The experimental result demonstrates that FEM is a reliable approach in predicting the mechanical behavior of multilayer structures. Hence, when calculating or predicting thin film stress using the aforementioned theories, the methodology proposed in this research can be employed to effectively validate the feasibility of these theories.

Sine-Gordon equation and its application to tectonic stress transfer

Science.gov (United States)

Bykov, Victor G.

2014-07-01

An overview is given on remarkable progress that has been made in theoretical studies of solitons and other nonlinear wave patterns, excited during the deformation of fault block (fragmented) geological media. The models that are compliant with the classical and perturbed sine-Gordon equations have only been chosen. In these mathematical models, the rotation angle of blocks (fragments) and their translatory displacement of the medium are used as dynamic variables. A brief description of the known models and their geophysical and geodynamic applications is given. These models reproduce the kinematic and dynamic features of the traveling deformation front (kink, soliton) generated in the fragmented media. It is demonstrated that the sine-Gordon equation is applicable to the description of series of the observed seismic data, modeling of strain waves, as well as the features related to fault dynamics and the subduction slab, including slow earthquakes, periodicity of episodic tremor and slow slip (ETS) events, and migration pattern of tremors. The study shows that simple heuristic models and analytical and numerical computations can explain triggering of seismicity by transient processes, such as stress changes associated with solitary strain waves in crustal faults. The need to develop the above-mentioned new (nonlinear) mathematical models of the deformed fault and fragmented media was caused by the reason that it is impossible to explain a lot of the observed effects, particularly, slow redistribution and migration of stresses in the lithosphere, within the framework of the linear elasticity theory.

Application of photostress method in stress analysis of a rotating disc

Directory of Open Access Journals (Sweden)

P. Frankovský

2014-10-01

Full Text Available The presented article demonstrates the application of PhotoStressR method in stress analysis of a rotating disc of a constant thickness, which was made of a photoelastic material PS-1A. Isoclinic fringes were observed on the rotating disc using linear polarized light at revolutions 5 000 RPM. Observations were carried out under angle parameter 0 o to 90 o with 10 o increase. A set of isostatic lines of I and II set was made from the set of obtained isoclinic lines. During gradual increase of rotations of the rotating disc up to 17 000 RPM, and with circular polarized light, we observed the distribution of colourful isochromatic fringes on the rotating disc. The field of isochromatic fringes, gained experimentally, at 15 000 RPM was compared with the field which was gained by means of a numerical analysis.

X-ray diffraction from thin films : Residual stress and texture analysis

Energy Technology Data Exchange (ETDEWEB)

Leoni, M; Scardi, [Trento Univ. (Italy). Dept. of Materials Engineering

1996-09-01

In this short contribution the attention will be drawn to the use of XRD-based non-destructive techniques for the study of the stress state and the orientation (texture) of various technologically valuable films. The cases in which the texture is important will be presented and they are: applicative examples, spacing in a wide variety of application areas and regarding growth-induced and machining-induced orientation.

The Effects of Foliar Application of Methanol on Morphological Characteristics of Bean (Phaseolus vulgaris L. under Drought Stress Condition

Directory of Open Access Journals (Sweden)

N. Armand

2016-02-01

Full Text Available Introduction Available water is an important factor for plant growth in arid environments. Results indicated that foliar application of methanol is believed to be more important than the drought tolerance in C3 plant. Since bean is a C3 plant, it performs light respiration under intense heat, light and water stress due to internal leaf CO2 concentration reduction and oxygen concentration increase. Light respiration can cause up to 20% loss of carbon in plants and decrease the yield. Increasing concentration of carbon dioxide can neutralize the effect caused by drought stress. Thus, the use of substances that can cause an increase in the concentration of carbon dioxide in the plant, leads to improving the yield under the drought conditions. One of the ways of increasing the concentration of carbon dioxide in plants is by using compounds such as methanol, ethanol, propanol, butanol as well as use of the amino acids of glycine, glutamate and aspartate. Plants can easily absorb methanol sprayed on leaves and use it as a carbon source added to atmospheric carbon. Methanol is relatively smaller compared to the CO2 molecules, so it can be easily absorbed and utilized by plants. Materials and Methods In order to evaluate the effects of foliar application of methanol on some morphological characteristics of bean under drought stress, a factorial experiment was conducted based on completely randomized block design with three replications in 2014 at the Khatam Alanbia University of Behbahan. The treatment of spraying methanol was at 4 levels include control (without spraying, 10, 20 and 30% v/v methanol which added 2 g l-1 glycine to each of solutions. Adding glycine to aqueous solution of methanol leads to prevention of damages caused by the toxicity of methanol. The drought factors including control (100% field of capacity, moderate drought stress (50% field of capacity and severe drought stress (25% field of capacity were considered. In this experiment

Recovery in dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors with thermal annealing

International Nuclear Information System (INIS)

Kim, Byung-Jae; Hwang, Ya-Hsi; Ahn, Shihyun; Zhu, Weidi; Dong, Chen; Lu, Liu; Ren, Fan; Holzworth, M. R.; Jones, Kevin S.; Pearton, Stephen J.; Smith, David J.; Kim, Jihyun; Zhang, Ming-Lan

2015-01-01

The recovery effects of thermal annealing on dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors were investigated. After stress, reverse gate leakage current and sub-threshold swing increased and drain current on-off ratio decreased. However, these degradations were completely recovered after thermal annealing at 450 °C for 10 mins for devices stressed either once or twice. The trap densities, which were estimated by temperature-dependent drain-current sub-threshold swing measurements, increased after off-state step-stress and were reduced after subsequent thermal annealing. In addition, the small signal rf characteristics of stressed devices were completely recovered after thermal annealing

Recent state of stress change in the Walker Lane zone, western Basin and Range province, United States

Science.gov (United States)

Bellier, Olivier; Zoback, Mary Lou

1995-06-01

The NW to north-trending Walker Lane zone (WLZ) is located along the western boundary of the northern Basin and Range province with the Sierra Nevada. This zone is distinguished from the surrounding Basin and Range province on the basis of irregular topography and evidence for both normal and strike-slip Holocene faulting. Inversion of slip vectors from active faults, historic fault offsets, and earthquake focal mechanisms indicate two distinct Quaternary stress regimes within the WLZ, both of which are characterized by a consistent WNW σ3 axis; these are a normal faulting regime with a mean σ3 axis of N85°±9°W and a mean stress ratio (R value) (R=(σ2-σ1)/(σ3-σ1)) of 0.63-0.74 and a younger strike-slip faulting regime with a similar mean σ3 axis (N65° - 70°W) and R values ranging between ˜ 0.1 and 0.2. This younger regime is compatible with historic fault offsets and earthquake focal mechanisms. Both the extensional and strike-slip stress regimes reactivated inherited Mesozoic and Cenozoic structures and also produced new faults. The present-day strike-slip stress regime has produced strike-slip, normal oblique-slip, and normal dip-slip historic faulting. Previous workers have explained the complex interaction of active strike-slip, oblique, and normal faulting in the WLZ as a simple consequence of a single stress state with a consistent WNW σ3 axis and transitional between strike-slip and normal faulting (maximum horizontal stress approximately equal to vertical stress, or R ≈ 0 in both regimes) with minor local fluctuations. The slip data reported here support previous results from Owens Valley that suggest deformation within temporally distinct normal and strike-slip faulting stress regimes with a roughly constant WNW trending σ3 axis (Zoback, 1989). A recent change from a normal faulting to a strike-slip faulting stress regime is indicated by the crosscutting striae on faults in basalts the dominantly strike-slip earthquake focal mechanisms and

Solid state gas sensors. Industrial application

Energy Technology Data Exchange (ETDEWEB)

Fleischer, Maximilian [Siemens AG, Muenchen (Germany). Corporate Technology; Lehmann, Mirko (eds.) [Innovative Sensor Technology (IST) AG, Wattwil (Switzerland)

2012-11-01

Written by experts. Richly illustrated. Encourages future research and investments in the fascinating field of gas sensors. Gas sensor products are very often the key to innovations in the fields of comfort, security, health, environment, and energy savings. This compendium focuses on what the research community labels as solid state gas sensors, where a gas directly changes the electrical properties of a solid, serving as the primary signal for the transducer. It starts with a visionary approach to how life in future buildings can benefit from the power of gas sensors. The requirements for various applications, such as for example the automotive industry, are then discussed in several chapters. Further contributions highlight current trends in new sensing principles, such as the use of nanomaterials and how to use new sensing principles for innovative applications in e.g. meteorology. So as to bring together the views of all the different groups needed to produce new gas sensing applications, renowned industrial and academic representatives report on their experiences and expectations in research, applications and industrialisation.

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.

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…

Changes in phase composition and stress state of surface layers of VK20 hard alloy after ion bombardment

International Nuclear Information System (INIS)

Platonov, G.L.; Leonov, E.Yu.; Anikin, V.N.; Anikeev, A.I.

1988-01-01

Titanium ion bombardment of the surface of the hard VK20 alloy is studied for its effect on variations in the phase and chemical composition of its surface layers. It is stated that ion treatment results in the appearance of the η-phase of Co 6 W 6 C composition in the surface layer of the VK20 alloy, in the increase of distortions and decrease of coherent scattering blocks of the hard alloy carbide phase. Such a bombardment is found to provoke a transition of the plane-stressed state of the hard alloy surface into the volume-stressed state. It is established that ion treatment does not cause an allotropic transition of the cobalt phase α-modification, formed during grinding of the hard alloy, into the β-modification

Effect of Zeolite and Nitrogen Fertilizer Application under Water Deficit Stress Conditions on Agronomical and Physiological Traits of Rapeseed

Directory of Open Access Journals (Sweden)

A. Ghiasvand Ghiasi

2014-08-01

Full Text Available In order to evaluation of zeolite and nitrogen fertilizer application effect on agronomic and physilogical traits of rapeseed (cv RGS003 under water deficit stress conditions, an experiment was conducted in factorial based on randomized complete block design with three replications during 2010 in Qazvin region, Iran. In the where, the two levels of irrigation factor as the normal irrigation (irrigation after 80 mm evaporation from class A pan as control and irrigation cease from stem elongation stage till end of growth, nitrogen factor was at three levels (0, 75 and 150 kg.ha-1 and zeolite factor (0 and 10tons per hectare were studied. Results showed that drought stress decreased evaluated traits such as silique per plant (41%, grain per silique (26%, 1000 seed weight (33%, grain yield (52.5%, oil percent (14%, RWC (31.5% and chlorophyll content (35%. Non-application of nitrogen had adverse effects on total traits and reduced them. However, zeolite application at water deficit stress conditions had positive and significant effect on total traits except of oil percent and chlorophyll content, specially improved grain yield and oil yield. Based on the results of this experiment, application of zeolite (10ton/ha-1 through storage and maintenance of water and nutrients, reduced the intensity and harmful effects of stress in plants and enhances crop yield.

Reassessment of the role of stress in development of radiation-induced microstructure

International Nuclear Information System (INIS)

Garner, F.A.; Wolfer, W.G.; Brager, H.R.

1978-10-01

Data are now accumulating which clearly demonstrate that the stress state plays a strong role in the development of void and dislocation microstructure in metals during neutron irradiation. In these experiments the application of a tensile biaxial stress state at constant fluence and temperature has been found to lead to a progressively decreasing metal density with increasing stress. The effect of stress on the concurrent development of voids, Frank interstitial loops and dislocation networks has been studied with transmission electron microscopy. The results of these experiments clearly show that the densities of both Frank loops and voids are enhanced by a tensile stress field, with the relevant operating variable being the hydrostatic stress. More importantly it appears that any anisotropy in the stress field is reflected in a corresponding anisotropy that develops in the number of Frank loops that form on the various (111) planes. The loop density that develops on each plane exhibits a clear and direct dependence on the resolved normal stress component at each plane. Although the data from these experiments have been previously interpreted to support the existence of stress-assisted nucleation mechanisms for both loops and voids, further analysis has shown both of these explanations to be deficient in one or more respects, and both models have been replaced

Preliminary field evaluation of solid state cameras for security applications

International Nuclear Information System (INIS)

1987-01-01

Recent developments in solid state imager technology have resulted in a series of compact, lightweight, all-solid-state closed circuit television (CCTV) cameras. Although it is widely known that the various solid state cameras have less light sensitivity and lower resolution than their vacuum tube counterparts, the potential for having a much longer Mean Time Between Failure (MTBF) for the all-solid-state cameras is generating considerable interest within the security community. Questions have been raised as to whether the newest and best of the solid state cameras are a viable alternative to the high maintenance vacuum tube cameras in exterior security applications. To help answer these questions, a series of tests were performed by Sandia National Laboratories at various test sites and under several lighting conditions. In general, all-solid-state cameras need to be improved in four areas before they can be used as wholesale replacements for tube cameras in exterior security applications: resolution, sensitivity, contrast, and smear. However, with careful design some of the higher performance cameras can be used for perimeter security systems, and all of the cameras have applications where they are uniquely qualified. Many of the cameras are well suited for interior assessment and surveillance uses, and several of the cameras are well designed as robotics and machine vision devices

Thermodynamic method for generating random stress distributions on an earthquake fault

Science.gov (United States)

Barall, Michael; Harris, Ruth A.

2012-01-01

This report presents a new method for generating random stress distributions on an earthquake fault, suitable for use as initial conditions in a dynamic rupture simulation. The method employs concepts from thermodynamics and statistical mechanics. A pattern of fault slip is considered to be analogous to a micro-state of a thermodynamic system. The energy of the micro-state is taken to be the elastic energy stored in the surrounding medium. Then, the Boltzmann distribution gives the probability of a given pattern of fault slip and stress. We show how to decompose the system into independent degrees of freedom, which makes it computationally feasible to select a random state. However, due to the equipartition theorem, straightforward application of the Boltzmann distribution leads to a divergence which predicts infinite stress. To avoid equipartition, we show that the finite strength of the fault acts to restrict the possible states of the system. By analyzing a set of earthquake scaling relations, we derive a new formula for the expected power spectral density of the stress distribution, which allows us to construct a computer algorithm free of infinities. We then present a new technique for controlling the extent of the rupture by generating a random stress distribution thousands of times larger than the fault surface, and selecting a portion which, by chance, has a positive stress perturbation of the desired size. Finally, we present a new two-stage nucleation method that combines a small zone of forced rupture with a larger zone of reduced fracture energy.

Laser quench hardening of steel: Effects of superimposed elastic pre-stress on the hardness and residual stress distribution

Science.gov (United States)

Meserve, Justin

Cold drawn AISI 4140 beams were LASER surface hardened with a 2 kW CO2 LASER. Specimens were treated in the free state and while restrained in a bending fixture inducing surface tensile stresses of 94 and 230 MPa. Knoop hardness indentation was used to evaluate the through thickness hardness distribution, and a layer removal methodology was used to evaluate the residual stress distribution. Results showed the maximum surface hardness attained was not affected by pre-stress during hardening, and ranged from 513 to 676 kg/mm2. The depth of effective hardening varied at different magnitudes of pre-stress, but did not vary proportionately to the pre-stress. The surface residual stress, coinciding with the maximum compressive residual stress, increased as pre-stress was increased, from 1040 MPa for the nominally treated specimens to 1270 MPa for specimens pre-stressed to 230 MPa. The maximum tensile residual stress observed in the specimens decreased from 1060 MPa in the nominally treated specimens to 760 MPa for specimens pre-stressed to 230 MPa. Similarly, thickness of the compressive residual stress region increased and the depth at which maximum tensile residual stress occurred increased as the pre-stress during treatment was increased Overall, application of tensile elastic pre-stress during LASER hardening is beneficial to the development of compressive residual stress in AISI 4140, with minimal impact to the hardness attained from the treatment. The newly developed approach for LASER hardening may support efforts to increase both the wear and fatigue resistance of parts made from hardenable steels.

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

International Nuclear Information System (INIS)

Rui Wu; Sandstroem, Rolf; Seitisleam, Facredin

2009-10-01

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

[Emotional regulation in aspect of action vs. state orientation, stress and self - injurious behavior among people with borderline personality disorder].

Science.gov (United States)

Blasczyk-Schiep, Sybilla; Rabska, Ewelina; Jaworska-Andryszewska, Paulina; Laso, Agnieszka

2015-06-01

In the bordeline personality disorder a large role ascribe to biopsychosocial factors. Studies have shown that more than 70% patients BPD reported experiencing traumatic events in childhood. The findings are confirming that making self-harming is a frequent symptom of bordeline disorder and 70-75% patients show at least one act of self-harming. Selfharming can be a reaction to maladaptive emotional regulation. Moreover a lowered tolerance level is characteristic of them to the stress and determined course learning dysfunctional patterns of behavior. The aim of this study is to determine the level of emotional regulation through the variable action vs state orientation and to investigate their relation to stress, self-harming and suicidal behavior. In study participated 45 persons with emotionally unstable borderline personality diagnosis. In the group was 33 women and 12 men in age 19-43. A Polish adaptation of standardized questionnaires was used to measure stress and action vs state orientation (SSI-K), self-injurious behavior (SHI) and suicidal tendencies (RFL-I). By patients with borderline personality disorder the level of action control, reasons for living and stress are predictors of selfharming behavior. The mediation analyze showed, that stress and reasons for living are mediators between action vs. state control and the level of self-harming behavior. A high level of stress correlates positively with self-harming and negatively with action control in patients with borderline personality disorder, and a high level of reasons for living correlates positively with action control and negatively with self-harming in people with BPD. © 2015 MEDPRESS.

Wireless transmission: state of research, applications, trends

International Nuclear Information System (INIS)

Berger, A.

2016-01-01

At the end of the 19th century Nikola Tesla started his work in the field of wireless energy transmission. More than 100 years after Tesla, the progress in modern semiconductor technology offer developers the possibility to realize highly efficient systems and have led to a revival of wireless energy transmission. The application ranges from the transmission of a few milliwatts in biomedical applications, over a few watts for the charging of mobile phones, to hundreds of kilowatts in the automotive sector. Depending on the used method, the possible transmission distances vary between a few centimeters up to thousands of kilometers. The physical basis of these technologies is the transmission of energy by electromagnetic waves. State-of-the-art systems use wavelengths ranging from radio waves to microwaves, to ultraviolet light. Current research focuses on optimizing transmission efficiency, increasing the possible transmission distance between transmitter and receiver, and improving spatial freedom of movement. This lecture gives an overview of the different approaches of wireless energy transmission and their physical background, the established industrial standards and the current state of research. In addition, the advantages and disadvantages of the individual methods are illustrated by selected commercial and scientific applications. (rössner) [de

Application of neural networks for finding the relation between stress and operational parameters of NPP Temelin

International Nuclear Information System (INIS)

Ruzek, L.

2003-01-01

Quick and sufficiently precise determination of stresses and strains measured by I and C, TMDS a CHEMIS is very important for on-line assessment of continuous damage of material under operating conditions. The application of some of the artificial intelligence methods, viz. neural network, is convenient in this context. A practical example of the application of this method is presented and the advantages in comparison with the finite element method (FEM) are discussed. The approach to the selection of characteristic loading used for the preparation of training data is also shown. The paper presents the results of actual calculation and analyses the merits of the attained coincidence for the determination of the tensor of stresses by FEM and neural networks

State-of-charge indication in portable applications

NARCIS (Netherlands)

Pop, V.; Bergveld, H.J.; Notten, P.H.L.; Regtien, Paulus P.L.

2005-01-01

The known methods of state-of-charge (SoC) indication in portable applications are not accurate enough under all practical conditions. The method presented in this paper aims at designing and testing an SoC indication system capable of predicting the remaining capacity of the battery and the

State-of-Charge Indication in Portable Applications

NARCIS (Netherlands)

Pop, V.; Bergveld, H.J.; Notten, P.H.L.; Regtien, Paulus P.L.

2005-01-01

The known methods of state-of-charge (SoC) indication in portable applications are not accurate enough under all practical conditions. The method presented in this paper aims at designing and testing an SoC indication system capable of predicting the remaining capacity of the battery and the

State-of-charge indication for portable applications

NARCIS (Netherlands)

Pop, V.; Bergveld, H.J.; Notten, P.H.L.; Regtien, P.P.L.

2005-01-01

The known methods of state-of-charge (SoC) indication in portable applications are not accurate enough under all practical conditions. The method presented in this paper aims at designing and testing an SoC indication system capable of predicting the remaining capacity of the battery and the

Stress Erythropoiesis Model Systems.

Science.gov (United States)

Bennett, Laura F; Liao, Chang; Paulson, Robert F

2018-01-01

Bone marrow steady-state erythropoiesis maintains erythroid homeostasis throughout life. This process constantly generates new erythrocytes to replace the senescent erythrocytes that are removed by macrophages in the spleen. In contrast, anemic or hypoxic stress induces a physiological response designed to increase oxygen delivery to the tissues. Stress erythropoiesis is a key component of this response. It is best understood in mice where it is extramedullary occurring in the adult spleen and liver and in the fetal liver during development. Stress erythropoiesis utilizes progenitor cells and signals that are distinct from bone marrow steady-state erythropoiesis. Because of that observation many genes may play a role in stress erythropoiesis despite having no effect on steady-state erythropoiesis. In this chapter, we will discuss in vivo and in vitro techniques to study stress erythropoiesis in mice and how the in vitro culture system can be extended to study human stress erythropoiesis.

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.

Elastic-plastic stresses in a thin rotating disk with shafthaving density variation parameter under steady-state temperature

Directory of Open Access Journals (Sweden)

Pankaj Thakur

2014-01-01

Full Text Available Steady thermal stresses in a rotating disc with shaft having density variation parameter subjected to thermal load have been derived by using Seth's transition theory. Neither the yields criterion nor the associated flow rule is assumed here. Results are depicted graphically. It has been seen that compressible material required higher percentage increased angular speed to become fully-plastic as compare to rotating disc made of incompressible material. Circumferential stresses are maximal at the outer surface of the rotating disc. With the introduction of thermal effect it decreases the value of radial and circumferential stresses at inner and outer surface for fully-plastic state.

Application of X-rays and Synchrotron X Rays to Residual Stress Evaluation Near Surfaces

International Nuclear Information System (INIS)

Pyzalla, Anke

1999-01-01

A nondestructive residual stress analysis can be performed using diffraction methods. The easiest accessible radiation is characteristic X radiation that has a penetration depth of ∼10 microm suitable for the determination of the residual stresses in near-surface layers. Special techniques have been developed, e.g., with respect to in situ analyses of the stress state in oxide layers and the residual stress analysis in coarse grained zones of steel welds or annealed Ni-base alloys. Depending on the size of the gauge volume, neutron diffraction can provide information at depths of tens of millimetres of steel and many tens of millimetres of Al. An alternative to the use of the characteristic synchrotron radiation is the use of a high-energy polychromatic beam in an energy dispersive arrangement, which gives access to higher penetration depths at still gauge volumes as small as 100 microm x 100 microm x 1 mm in steel rods of 15-mm diameter. The combination of neutrons with conventional X rays and monochromatic and polychromatic synchrotron radiation allows for a comprehensive investigation of the phase composition, the texture, and the residual stresses

Stress near geometrically complex strike-slip faults - Application to the San Andreas fault at Cajon Pass, southern California

Science.gov (United States)

Saucier, Francois; Humphreys, Eugene; Weldon, Ray, II

1992-01-01

A model is presented to rationalize the state of stress near a geometrically complex major strike-slip fault. Slip on such a fault creates residual stresses that, with the occurrence of several slip events, can dominate the stress field near the fault. The model is applied to the San Andreas fault near Cajon Pass. The results are consistent with the geological features, seismicity, the existence of left-lateral stress on the Cleghorn fault, and the in situ stress orientation in the scientific well, found to be sinistral when resolved on a plane parallel to the San Andreas fault. It is suggested that the creation of residual stresses caused by slip on a wiggle San Andreas fault is the dominating process there.

Stressed Out: How Stress Develops and How to Cope with it

Directory of Open Access Journals (Sweden)

Mortillaro Marcello

2014-05-01

Full Text Available Our experience of stress depends on how we evaluate the circumstances impacting our individual well-being. In principle, any event can be a stressor. Certain events can produce complex emotional states, such as a mixture of anger and worry. If such states are prolonged, they can lead to stress. Stress can be identified by means of such expressive components as facial expression and signs of stress in the voice. Indeed, the voice is particularly sensitive to stress and is frequently used to measure stress levels. Coping strategies differ from person to person and are not mutually exclusive. Often, people use multiple strategies at the same time. Not all of these strategies are good for individual well-being or favor a cooperation-based work culture. To avoid employee burnout, companies should keep an eye on the stress load of their employees and develop trainings to increase emotional competences and improve constructive stress management.

Control of free-edge interlaminar stresses in composite laminates using piezoelectric actuators

International Nuclear Information System (INIS)

Huang, Bin; Soo Kim, Heung

2014-01-01

The control of free-edge interlaminar stresses in laminated composite structures using a stress function-based approach is proposed. The assumed stress fields satisfy pointwise traction and free boundary conditions at surfaces. Governing equations are derived using the principle of complementary virtual work. A general eigenvalue solution procedure was adopted to obtain accurate stress states of the laminated composite structure. The results obtained from the proposed method were compared with those obtained by three-dimensional finite element analyses. It was found that interlaminar stresses generated by mechanical loadings could be significantly reduced by applying proper electric fields to piezoelectric actuators, which were surface bonded or embedded in composite laminates. Locations of piezoelectric actuators also influenced the distributions of interlaminar stresses. The results provided that piezoelectric actuators have potential in the application to actively control interlaminar stresses in composite laminates. (paper)

Cigarette craving and stressful social interactions: The roles of state and trait social anxiety and smoking to cope.

Science.gov (United States)

Watson, Noreen L; DeMarree, Kenneth G; Cohen, Lee M

2018-04-01

Previous research indicates that social anxiety (SA) is a risk factor for the maintenance and relapse of smoking behaviors. However, little is known about the mechanisms underlying this relationship. The current study tested the effects of state and trait levels of SA as well as smoking to cope with symptoms of SA on craving during a social stressor task in abstinent conditions. Participants (n = 60) were daily smokers, aged 18-30. Participants attended two sessions: a baseline session and a second session, wherein they engaged in a social stressor task while deprived from nicotine for 24 h. Subjective ratings of cigarette craving and state levels of SA were assessed six times throughout the task. Data were analyzed via multilevel modeling. Both trait SA and some forms of smoking to cope with symptoms of SA were more likely to predict increased craving during times of high, relative to low, social stress. Further, individuals with higher state SA, greater smoking to cope behaviors, and those who experience greater relief of social distress by smoking experienced greater craving throughout the task. These effects remained after controlling for nicotine dependence, withdrawal symptoms, depression, and other symptoms of anxiety and stress. Smoking to cope with symptoms of SA did not moderate the relationship between state SA and craving. Smokers high in SA (state and trait) and smoking to cope with symptoms of SA may be at risk for continued smoking and relapse because of the intensity of cravings they experience during stressful social situations. Copyright © 2018 Elsevier B.V. All rights reserved.

The effect of inertia, viscous damping, temperature and normal stress on chaotic behaviour of the rate and state friction model

Science.gov (United States)

Sinha, Nitish; Singh, Arun K.; Singh, Trilok N.

2018-04-01

A fundamental understanding of frictional sliding at rock surfaces is of practical importance for nucleation and propagation of earthquakes and rock slope stability. We investigate numerically the effect of different physical parameters such as inertia, viscous damping, temperature and normal stress on the chaotic behaviour of the two state variables rate and state friction (2sRSF) model. In general, a slight variation in any of inertia, viscous damping, temperature and effective normal stress reduces the chaotic behaviour of the sliding system. However, the present study has shown the appearance of chaos for the specific values of normal stress before it disappears again as the normal stress varies further. It is also observed that magnitude of system stiffness at which chaotic motion occurs, is less than the corresponding value of critical stiffness determined by using the linear stability analysis. These results explain the practical observation why chaotic nucleation of an earthquake is a rare phenomenon as reported in literature.

Evaluation of stress intensity factors due to welding residual stresses for circumferential cracked pipes

International Nuclear Information System (INIS)

Oh, Chang-Young; Kim, Yun-Jae; Oh, Young-Jin; Kim, Jong-Sung; Song, Tae-Kwang; Kim, Yong-Beum

2013-01-01

To investigate the applicability of existing methods to estimate stress intensity factors due to welding residual stresses, comparisons with finite element (FE) solutions are made for two types of generic welding residual stress profiles, generated by simulating repair welds. It is found that fitting residual stresses over the crack depth using third-order polynomials gives good estimates of stress intensity factors but fitting over the entire thickness can result in inaccurate estimates even with fourth-order polynomials. Noting that welding residual stresses are often determined from FE analyses, linearization of residual stresses to estimate stress intensity factors is proposed. Comparison with FE solutions shows good agreements. -- Highlights: ► Applicability of K estimation methods is investigated for welding residual stresses. ► Two types of generic residual stress profiles with repair welds are considered. ► Fitting residual stresses over the crack depth gives good estimates of K. ► A method to estimate K by linearising residual stress profiles is proposed

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.

Stress state variations among the clay and limestone formations of the molasse basin of Northern Switzerland

International Nuclear Information System (INIS)

Vietor, Tim; Mueller, Herwig; Frieg, Bernd; Klee, Gerd

2012-01-01

Document available in extended abstract form only. Full text of publication follows: The design of geological repositories for radioactive waste responds to the requirements of technical feasibility and long-term safety in the context of a specific geological setting. An important aspect of the geological setting is the primary stress field. To a large extent the stress state controls repository induced effects such as the excavation damage zone and the associated potential changes in the waste isolation properties of the host rock. Therefore the measurement of the stress state receives some attention where the site selection for geological repositories focuses onto relatively weak host rocks such as clay-stones and marly shales that tend to develop a significant excavation damage zone. Measurements of the minimum stress magnitudes in a recently drilled geothermal well in the Molasse Basin of northern Switzerland have yielded a stress profile reaching from 592 m to 1455 m depth. It straddles several rock units and includes the top of the crystalline basement. The sedimentary sequence consists of Marine limestones, shales and marls unconformably covered by Tertiary rocks of the Molasse. In other parts of the basin the evaporitic rocks of the Triassic Muschelkalk formation at the base of the sedimentary layer served as a regional detachment and enabled thin skinned thrusting and the formation of the Jura Fold and Thrust Belt in the Late Miocene. The stress measurements have been performed in the open hole by Mini-frac tests. The method uses a double packer system to isolate a one meter long interval of the borehole that is then pressurized at high injection rates up to the breakdown of the formation. Repeated pressurization of the interval allows to determine the stress that acts on the newly created fracture. The total injected volume during such a test is in the range of a few litres and the size of the fracture that extends from the borehole normal to the minimum

Application of the method finite elements by numerical modeling stress-strain state in conveyor belts

OpenAIRE

Maras Michal; Hatala Jozef; Marasová Daniela

1997-01-01

Solving problems connected with damaging a conveyor belt at the transfer points is conditioned by knowing laws of this phenomenon. Acquiring the knowledge on this phenomen is possible to be gained either by experimental research or by the numerical model GEM 22, which enables to determine the distribution of stresses and strains in a suitably selected cross-section of a conveyor belt. The paper begins by defining the problem, determining the boundary model conditions and continues by modellin...

Posttraumatic stress disorder: a state-of-the-science review.

Science.gov (United States)

Nemeroff, Charles B; Bremner, J Douglas; Foa, Edna B; Mayberg, Helen S; North, Carol S; Stein, Murray B

2006-02-01

This article reviews the state-of-the-art research in posttraumatic stress disorder (PTSD) from several perspectives: (1) Sex differences: PTSD is more frequent among women, who tend to have different types of precipitating traumas and higher rates of comorbid panic disorder and agoraphobia than do men. (2) Risk and resilience: The presence of Group C symptoms after exposure to a disaster or act of terrorism may predict the development of PTSD as well as comorbid diagnoses. (3) Impact of trauma in early life: Persistent increases in CRF concentration are associated with early life trauma and PTSD, and may be reversed with paroxetine treatment. (4) Imaging studies: Intriguing findings in treated and untreated depressed patients may serve as a paradigm of failed brain adaptation to chronic emotional stress and anxiety disorders. (5) Neural circuits and memory: Hippocampal volume appears to be selectively decreased and hippocampal function impaired among PTSD patients. (6) Cognitive behavioral approaches: Prolonged exposure therapy, a readily disseminated treatment modality, is effective in modifying the negative cognitions that are frequent among PTSD patients. In the future, it would be useful to assess the validity of the PTSD construct, elucidate genetic and experiential contributing factors (and their complex interrelationships), clarify the mechanisms of action for different treatments used in PTSD, discover ways to predict which treatments (or treatment combinations) will be successful for a given individual, develop an operational definition of remission in PTSD, and explore ways to disseminate effective evidence-based treatments for this condition.

Multi-parameter approximation of stress field in a cracked specimen using purpose-built Java applications

Czech Academy of Sciences Publication Activity Database

Veselý, V.; Sopek, J.; Tesař, D.; Frantík, P.; Pail, T.; Seitl, Stanislav

2015-01-01

Roč. 9, č. 33 (2015), s. 120-133 ISSN 1971-8993 Institutional support: RVO:68081723 Keywords : Cracked specimen * Near-crack-tip fields * Williams expansion * Higher order terms * Stress field reconstruction * Finite element analysis * Java application Subject RIV: JL - Materials Fatigue, Friction Mechanics

The association between high levels of cumulative life stress and aberrant resting state EEG dynamics in old age.

Science.gov (United States)

Marshall, Amanda C; Cooper, Nicholas R

2017-07-01

Cumulative experienced stress produces shortcomings in old adults' cognitive performance. These are reflected in electrophysiological changes tied to task execution. This study explored whether stress-related aberrations in older adults' electroencephalographic (EEG) activity were also apparent in the system at rest. To this effect, the amount of stressful life events experienced by 60 young and 60 elderly participants were assessed in conjunction with resting state power changes in the delta, theta, alpha, and beta frequencies during a resting EEG recording. Findings revealed elevated levels of delta power among elderly individuals reporting high levels of cumulative life stress. These differed significantly from young high and low stress individuals and old adults with low levels of stress. Increases of delta activity have been linked to the emergence of conditions such as Alzheimer's Disease and Mild Cognitive Impairment. Thus, a potential interpretation of our findings associates large amounts of cumulative stress with an increased risk of developing age-related cognitive pathologies in later life. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

State E-Government Strategies: Identifying Best Practices and Applications

Science.gov (United States)

2007-07-23

Internet; ! Developing meaningful online applications for local government, businesses, educators, and other sectors; ! Establishing local “ eCommunity ...state, national, and international levels. However, frequently there is little meaningful coordination or communication between various e-government...weekly with the governor, 13% reported meeting monthly, and 21% reported “other,” meaning that these states have a different meeting schedule

Calorimetric features of release of plastic deformation induced internal stresses, and approach to equilibrium state on annealing of crystals and glasses

Energy Technology Data Exchange (ETDEWEB)

Johari, G.P., E-mail: joharig@mcmaster.ca

2014-04-01

Highlights: • Stress release in a glass occurs at a faster rate than structural relaxation. • Plastically-deformed glass would show two exothermic minima, and no glass transition. • Enthalpy matching procedure would yield an inaccurate fictive temperature. • Complex heat capacity may distinguish plastically-deformed from quench-formed glass. - Abstract: Plastic deformation of crystals and glasses produces internal strains (stresses), which change their energy and other thermodynamic properties. On annealing, these stresses decrease at a rate faster than the structure relaxes toward the equilibrium state. Mechanism of such relaxations in crystals differs from that in glasses and it also differs for glasses of different types. In all cases, the energy related properties decrease with time isothermally and on heating, resembling the structure relaxation of a stress-free glass. We consider these features and argue that kinetics of enthalpy loss with time yields the rate constants of the stress release and of the structure change, and not the viscosity determining α-relaxation time. Since thermal cycling does not recover the enthalpy from internal stresses, a glass with stresses has neither a glass-softening temperature, T{sub g}, nor a fictive temperature, T{sub f}. Plastic deformation would not rejuvenate a physically aged glass to the properties of its un-aged state. The Prigogine–Defay ratio can be extended to all T{sub f}s, and used to investigate the effect of distribution of relaxation times on its value, but it can not be defined for an internally stressed glass. After discussing the effects of annealing on the heat capacity and DSC scans, we conclude that on slow heating, glass with deformation-induced stresses would show two exothermic minima, and normal glass would show only one such minimum. Temperature-modulated scanning calorimetry would also distinguish an internally stressed glass from an equally high-enthalpy, stress-free glass. Enthalpy

Statistical damage constitutive model for rocks subjected to cyclic stress and cyclic temperature

Science.gov (United States)

Zhou, Shu-Wei; Xia, Cai-Chu; Zhao, Hai-Bin; Mei, Song-Hua; Zhou, Yu

2017-10-01

A constitutive model of rocks subjected to cyclic stress-temperature was proposed. Based on statistical damage theory, the damage constitutive model with Weibull distribution was extended. Influence of model parameters on the stress-strain curve for rock reloading after stress-temperature cycling was then discussed. The proposed model was initially validated by rock tests for cyclic stress-temperature and only cyclic stress. Finally, the total damage evolution induced by stress-temperature cycling and reloading after cycling was explored and discussed. The proposed constitutive model is reasonable and applicable, describing well the stress-strain relationship during stress-temperature cycles and providing a good fit to the test results. Elastic modulus in the reference state and the damage induced by cycling affect the shape of reloading stress-strain curve. Total damage induced by cycling and reloading after cycling exhibits three stages: initial slow increase, mid-term accelerated increase, and final slow increase.

Monitoring training load, recovery-stress state, immune-endocrine responses, and physical performance in elite female basketball players during a periodized training program.

Science.gov (United States)

Nunes, João A; Moreira, Alexandre; Crewther, Blair T; Nosaka, Ken; Viveiros, Luis; Aoki, Marcelo S

2014-10-01

This study investigated the effect of a periodized training program on internal training load (ITL), recovery-stress state, immune-endocrine responses, and physical performance in 19 elite female basketball players. The participants were monitored across a 12-week period before an international championship, which included 2 overloading and tapering phases. The first overloading phase (fourth to sixth week) was followed by a 1-week tapering, and the second overloading phase (eighth to 10th week) was followed by a 2-week tapering. ITL (session rating of perceived exertion method) and recovery-stress state (RESTQ-76 Sport questionnaire) were assessed weekly and bi-weekly, respectively. Pretraining and posttraining assessments included measures of salivary IgA, testosterone and cortisol concentrations, strength, jumping power, running endurance, and agility. Internal training load increased across all weeks from 2 to 11 (p ≤ 0.05). After the first tapering period (week 7), a further increase in ITL was observed during the second overloading phase (p ≤ 0.05). After the second tapering period, a decrease in ITL was detected (p ≤ 0.05). A disturbance in athlete stress-recovery state was noted during the second overloading period (p ≤ 0.05), before returning to baseline level in end of the second tapering period. The training program led to significant improvements in the physical performance parameters evaluated. The salivary measures did not change despite the fluctuations in ITL. In conclusion, a periodized training program evoked changes in ITL in elite female basketball players, which appeared to influence their recovery-stress state. The training plan was effective in preparing participants for competition, as indicated by improvements in recovery-stress state and physical performance after tapering.

Regulation of water, salinity, and cold stress responses by salicylic acid

Directory of Open Access Journals (Sweden)

Kenji eMiura

2014-01-01

Full Text Available Salicylic acid (SA is a naturally occurring phenolic compound. SA plays an important role in the regulation of plant growth, development, ripening, and defense responses. The role of SA in the plant-pathogen relationship has been extensively investigated. In addition to defense responses, SA plays an important role in the response to abiotic stresses, including drought, low temperature, and salinity stresses. It has been suggested that SA has great agronomic potential to improve the stress tolerance of agriculturally important crops. However, the utility of SA is dependent on the concentration of the applied SA, the mode of application, and the state of the plants (e.g., developmental stage and acclimation. Generally, low concentrations of applied SA alleviate the sensitivity to abiotic stresses, and high concentrations of applied induce high levels of oxidative stress, leading to a decreased tolerance to abiotic stresses. In this chapter, the effects of SA on the water stress responses and regulation of stomatal closure are reviewed.

Physiology-driven adaptive virtual reality stimulation for prevention and treatment of stress related disorders.

Science.gov (United States)

Cosić, Kresimir; Popović, Sinisa; Kukolja, Davor; Horvat, Marko; Dropuljić, Branimir

2010-02-01

The significant proportion of severe psychological problems related to intensive stress in recent large peacekeeping operations underscores the importance of effective methods for strengthening the prevention and treatment of stress-related disorders. Adaptive control of virtual reality (VR) stimulation presented in this work, based on estimation of the person's emotional state from physiological signals, may enhance existing stress inoculation training (SIT). Physiology-driven adaptive VR stimulation can tailor the progress of stressful stimuli delivery to the physiological characteristics of each individual, which is indicated for improvement in stress resistance. Following an overview of physiology-driven adaptive VR stimulation, its major functional subsystems are described in more detail. A specific algorithm of stimuli delivery applicable to SIT is outlined.

Dynamic of bioelectric activity back hypothalamus changes in conditions of pyroxan application on the background of stress-reaction developmen

Directory of Open Access Journals (Sweden)

T. G. Chaus

2005-04-01

Full Text Available The dynamic of changes of capacity of electroencephalogram’s rhythms back hypothalamus at animals of control group and group in stress conditions in parallel with rats who on a background of stress development accepted pyroxan is analyzed. The submitted results have shown influence of a pharmacological preparation pyroxan on bioelectric activity of back hypothalamus in stress conditions that restoration of electric activity under action of this preparation was more shown at 3 weeks of its application.

An in-situ investigation of the acute effects of Bikram yoga on positive- and negative affect, and state-anxiety in context of perceived stress.

Science.gov (United States)

Szabo, Attila; Nikházy, Letícia; Tihanyi, Benedek; Boros, Szilvia

2017-04-01

Bikram yoga is a relatively new, but an increasingly popular form of exercise. Its health benefits were demonstrated on physical and psychological measures. The current field study tested the acute effects of Bikram yoga on practitioners' positive-/negative-affect and state-anxiety, and their link to the self-perceived stress, in Bikram yoga participants. Field study, within-participants design, testing perceived stress and its relation to changes in positive-/negative-affect and state-anxiety in 53 habitual Bikram yoga participants. Statistically significant positive changes emerged in all three psychological measures after the 90-min Bikram yoga session. The decrease in negative-affect and state-anxiety were significantly and positively related to the perceived stress. Estimated effort was unrelated to the magnitude of the changes recorded in the psychological measures. Heart rates and self-report measures indicated that physically Bikram yoga is only mildly challenging. The findings illustrate that, independently of the physical effort, Bikram yoga is a new mild form of exercise that reduces negative-affect and state-anxiety, and the reduction is directly related to the perceived stress. Therefore, Bikram yoga appears to be beneficial for all practitioners, but even more so for the individuals who experience substantial stress in the daily life.

Self-stigma and its associations with stress, physical health, and health care satisfaction in adults who stutter.

Science.gov (United States)

Boyle, Michael P; Fearon, Alison N

2018-06-01

The aim of this study was to identify potential relationships between self-stigma (stigma awareness and stigma application) and stress, physical health, and health care satisfaction among a large sample of adults who stutter. It was hypothesized that both stigma awareness and stigma application would be inversely related to measures of physical health and health care satisfaction, and positively related to stress. Furthermore, it was anticipated that stress mediated the relationship between self-stigma and physical health. A sample of adults who stutter in the United States (n=397) completed a web survey that assessed levels of stigma awareness and stigma application, stress, physical health, and health care satisfaction. Correlational analyses were conducted to determine the relationships between these variables. Higher levels of stigma awareness and stigma application were associated with increased stress, decreased overall physical health, and decreased health care satisfaction (i.e., discomfort obtaining health care due to stuttering, and adverse health care outcomes due to stuttering), and these relationships were statistically significant. Stress was identified as a mediator between stigma application and physical health. Because adults who stutter with higher levels of self-stigma are at risk for decreased physical health through increased stress, and lower satisfaction with their health care experiences as a result of stuttering, it is important for professionals to assess and manage self-stigma in clients who stutter. Self-stigma has implications for not only psychological well-being, but stress, physical health, and health care satisfaction as well. Copyright © 2017 Elsevier Inc. All rights reserved.

Stressed-deformed state of mountain rocks in elastic stage and between elasticity

Directory of Open Access Journals (Sweden)

Samedov A.M.

2017-12-01

Full Text Available The problems of the stress-strain state of rocks in the elastic stage and beyond the elastic limits, and the ways of schematizing the tension and compression diagrams were reviewed in the article. To simplify calculations outside the elastic range, the tension (compression diagrams are usually schematized, i.e. are replaced by curved smooth lines having a fairly simple mathematical expression and at the same time well coinciding with the experimentally obtained diagrams. When diagram is to be schematized, it is necessary to take a constant temperature of superheated water steam if a rock test is planned in a relaxed form. Note that when the diagram is schematizing, the difference between the limits of proportionality and fluidity is erased. This allows the limit of proportionality to be considered the limit of fluidity. Schematicization can be carried out in the area where the tensile strength (compression is planned to be destroyed with the established weakening of rocks by exposure to water steam or chemical reagents. Samples of rocks in natural form were tested and weakened by means of superheated water steam (220 °C and more and chemical reagents for tension and compression. The data are obtained, the diagrams of deformation are constructed and schematized in the elastic stage and beyond the elastic limit. Based on the schematic diagrams of deformation, the components of stress and strain were composed in the elastic stage and beyond the elastic limit. It is established in the publication that rocks under compression and stretching deform, both within the elastic stage, and beyond the limits of elasticity. This could be seen when the samples, both in natural and in weakened state, with superheated water steam (more than 220 °C or chemical reagents were tested. In their natural form, they are mainly deformed within the elastic stage and are destroyed as a brittle material, and in a weakened form they can deform beyond the elastic stage and

The Application of Normal Stress Reduction Function in Tilt Tests for Different Block Shapes

Science.gov (United States)

Kim, Dong Hyun; Gratchev, Ivan; Hein, Maw; Balasubramaniam, Arumugam

2016-08-01

This paper focuses on the influence of the shapes of rock cores, which control the sliding or toppling behaviours in tilt tests for the estimation of rock joint roughness coefficients (JRC). When the JRC values are estimated by performing tilt tests, the values are directly proportional to the basic friction of the rock material and the applied normal stress on the sliding planes. Normal stress obviously varies with the shape of the sliding block, and the basic friction angle is also affected by the sample shapes in tilt tests. In this study, the shapes of core blocks are classified into three representative shapes and those are created using plaster. Using the various shaped artificial cores, a set of tilt tests is carried out to identify the shape influences on the normal stress and the basic friction angle in tilt tests. The test results propose a normal stress reduction function to estimate the normal stress for tilt tests according to the sample shapes based on Barton's empirical equation. The proposed normal stress reduction functions are verified by tilt tests using artificial plaster joints and real rock joint sets. The plaster joint sets are well matched and cast in detailed printed moulds using a 3D printing technique. With the application of the functions, the obtained JRC values from the tilt tests using the plaster samples and the natural rock samples are distributed within a reasonable JRC range when compared with the measured values.

The optimal solution of a non-convex state-dependent LQR problem and its applications.

Directory of Open Access Journals (Sweden)

Xudan Xu

Full Text Available This paper studies a Non-convex State-dependent Linear Quadratic Regulator (NSLQR problem, in which the control penalty weighting matrix [Formula: see text] in the performance index is state-dependent. A necessary and sufficient condition for the optimal solution is established with a rigorous proof by Euler-Lagrange Equation. It is found that the optimal solution of the NSLQR problem can be obtained by solving a Pseudo-Differential-Riccati-Equation (PDRE simultaneously with the closed-loop system equation. A Comparison Theorem for the PDRE is given to facilitate solution methods for the PDRE. A linear time-variant system is employed as an example in simulation to verify the proposed optimal solution. As a non-trivial application, a goal pursuit process in psychology is modeled as a NSLQR problem and two typical goal pursuit behaviors found in human and animals are reproduced using different control weighting [Formula: see text]. It is found that these two behaviors save control energy and cause less stress over Conventional Control Behavior typified by the LQR control with a constant control weighting [Formula: see text], in situations where only the goal discrepancy at the terminal time is of concern, such as in Marathon races and target hitting missions.

Brain-derived neurotrophic factor and hypothalamic-pituitary-adrenal axis adaptation processes in a depressive-like state induced by chronic restraint stress.

Science.gov (United States)

Naert, Gaelle; Ixart, Guy; Maurice, Tangui; Tapia-Arancibia, Lucia; Givalois, Laurent

2011-01-01

Depression is potentially life-threatening. The most important neuroendocrine abnormality in this disorder is hypothalamo-pituitary-adrenocortical (HPA) axis hyperactivity. Recent findings suggest that all depression treatments may boost the neurotrophin production especially brain-derived neurotrophic factor (BDNF). Moreover, BDNF is highly involved in the regulation of HPA axis activity. The aim of this study was to determine the impact of chronic stress (restraint 3h/day for 3 weeks) on animal behavior and HPA axis activity in parallel with hippocampus, hypothalamus and pituitary BDNF levels. Chronic stress induced changes in anxiety (light/dark box test) and anhedonic states (sucrose preference test) and in depressive-like behavior (forced swimming test); general locomotor activity and body temperature were modified and animal body weight gain was reduced by 17%. HPA axis activity was highly modified by chronic stress, since basal levels of mRNA and peptide hypothalamic contents in CRH and AVP and plasma concentrations in ACTH and corticosterone were significantly increased. The HPA axis response to novel acute stress was also modified in chronically stressed rats, suggesting adaptive mechanisms. Basal BDNF contents were increased in the hippocampus, hypothalamus and pituitary in chronically stressed rats and the BDNF response to novel acute stress was also modified. This multiparametric study showed that chronic restraint stress induced a depressive-like state that was sustained by mechanisms associated with BDNF regulation. Copyright © 2010 Elsevier Inc. All rights reserved.

From user context states to context-aware applications

NARCIS (Netherlands)

Shishkov, Boris; van Sinderen, Marten J.; Filipe, J.; Cordeiro, J.; Cardoso, J.

2008-01-01

In many cases, in order to be effective, software applications need to allow sensitivity to user context state changes. This implies however additional complexity associated with the need for applications’ adaptability (being capable of capturing context, interpreting it and reacting on it). Hence,

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.

Analysis of Stress Updates in the Material-point Method

DEFF Research Database (Denmark)

Andersen, Søren; Andersen, Lars

2009-01-01

The material-point method (MPM) is a new numerical method for analysis of large strain engineering problems. The MPM applies a dual formulation, where the state of the problem (mass, stress, strain, velocity etc.) is tracked using a finite set of material points while the governing equations...... are solved on a background computational grid. Several references state, that one of the main advantages of the material-point method is the easy application of complicated material behaviour as the constitutive response is updated individually for each material point. However, as discussed here, the MPM way...

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.

Bruxism affects stress responses in stressed rats.

Science.gov (United States)

Sato, Chikatoshi; Sato, Sadao; Takashina, Hirofumi; Ishii, Hidenori; Onozuka, Minoru; Sasaguri, Kenichi

2010-04-01

It has been proposed that suppression of stress-related emotional responses leads to the simultaneous activation of both sympathetic and parasympathetic divisions of the autonomic nervous system (ANS) and that the expression of these emotional states has a protective effect against ulcerogenesis. In the present study, we investigated whether stress-induced bruxism activity (SBA) has a physiological effect of on the stress-induced changes of the stomach, thymus, and spleen as well as blood leukocytes, cortisol, and adrenaline. This study demonstrated that SBA attenuated the stress-induced ulcer genesis as well as degenerative changes of thymus and spleen. SBA also attenuated increases of adrenaline, cortisol, and neutrophils in the blood. In conclusion, expression of aggression through SBA during stress exposure attenuates both stress-induced ANS response, including gastric ulcer formation.

Stress og aldring

DEFF Research Database (Denmark)

Jørgensen, Anders; Jørgensen, Martin Balslev; Poulsen, Henrik Enghusen

2012-01-01

Accumulating evidence supports the popular notion that psychological stress states may accelerate aging. Stress has been shown to influence cellular systems known to be involved in the aging process. Furthermore, stress is associated with an increased risk of various age-related medical disorders....... These effects are likely mediated by the secretion of stress hormones. In this short review we focus on biochemical and epidemiological evidence for a link between stress and aging....

Nutritional mitigation of winter thermal stress in gilthead seabream: Associated metabolic pathways and potential indicators of nutritional state.

Science.gov (United States)

Richard, Nadège; Silva, Tomé S; Wulff, Tune; Schrama, Denise; Dias, Jorge P; Rodrigues, Pedro M L; Conceição, Luís E C

2016-06-16

A trial was carried out with gilthead seabream juveniles, aiming to investigate the ability of an enhanced dietary formulation (diet Winter Feed, WF, containing a higher proportion of marine-derived protein sources and supplemented in phospholipids, vitamin C, vitamin E and taurine) to assist fish in coping with winter thermal stress, compared to a low-cost commercial diet (diet CTRL). In order to identify the metabolic pathways affected by WF diet, a comparative two dimensional differential in-gel electrophoresis (2D-DIGE) analysis of fish liver proteome (pH 4–7) was undertaken at the end of winter. A total of 404 protein spots, out of 1637 detected, were differentially expressed between the two groups of fish. Mass spectrometry analysis of selected spots suggested that WF diet improved oxidative stress defense, reduced endoplasmic reticulum stress, enhanced metabolic flux through methionine cycle 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 and metabolic profiling purposes. Intragroup variability and co-measured information were also used to pinpoint which proteins displayed a stronger relation with fish nutritional state. Winter low water temperature is a critical factor for gilthead seabream farming in the Mediterranean region, leading to a reduction of feed intake, which often results in metabolic and immunological disorders and stagnation of growth performances. In a recent trial, we investigated the ability of an enhanced dietary formulation (diet WF) to assist gilthead seabream in coping with winter thermal stress, compared to a standard commercial diet (diet CTRL). Within this context, in the present work, we identified metabolic processes that are involved in the stress-mitigating effect observed

Modeling assumptions influence on stress and strain state in 450 t cranes hoisting winch construction

Directory of Open Access Journals (Sweden)

Damian GĄSKA

2011-01-01

Full Text Available This work investigates the FEM simulation of stress and strain state of the selected trolley’s load-carrying structure with 450 tones hoisting capacity [1]. Computational loads were adopted as in standard PN-EN 13001-2. Model of trolley was built from several cooperating with each other (in contact parts. The influence of model assumptions (simplification in selected construction nodes to the value of maximum stress and strain with its area of occurrence was being analyzed. The aim of this study was to determine whether the simplification, which reduces the time required to prepare the model and perform calculations (e.g., rigid connection instead of contact are substantially changing the characteristics of the model.

Measuring in-situ stress in deep boreholes

International Nuclear Information System (INIS)

1985-08-01

The hydrofracturing method of in-situ stress measurement is the only technique which has been proven to be reliable in boreholes below depths of 300 m. The method has been used in a variety of applications at depths of up to 5000m, and in a range of borehole diameters. The equipment used is composed of standard components from proven and long-established oil industry well-logging tools and is simple to operate. This is preferable to the delicate electrical devices used in the overcoring stress measurement method. Electrical components are difficult to waterproof, very small strains are monitored and the tendency of electrical circuits to drift, due to a variety of effects, makes interpretation of the results difficult. However, the interpretation of hydrofracturing test results is often not easy. Many factors can prevent ideal fracturing behaviour from occurring, in which case conventional analyses will yield incorrect answers. The complete state of stress can often not be determined and sweeping assumptions are commonly made about principal stress direction, which cannot always be subsequently verified. (author)

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

for 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 caused impaired growth and reduced survival of both resident and migratory......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...

Topical application of ointment containing 0.5% green tea catechins suppresses tongue oxidative stress in 5-fluorouracil administered rats.

Science.gov (United States)

Miyai, Hisataka; Maruyama, Takayuki; Tomofuji, Takaaki; Yoneda, Toshiki; Azuma, Tetsuji; Mizuno, Hirofumi; Sugiura, Yoshio; Kobayashi, Terumasa; Ekuni, Daisuke; Morita, Manabu

2017-10-01

The purpose of this study was to investigate the preventive effects of topical application of green tea catechins on tongue oxidative stress induced by 5-fluorouracil (5-FU) administration in rats. Male Wistar rats (n=28, 8 weeks old) were divided into four groups of seven rats each: a negative control group (saline administration and application of ointment without green tea catechins), a positive control group (5-FU administration and application of ointment without green tea catechins), and two experimental groups (5-FU administration and application of ointment containing 0.1% or 0.5% green tea catechins). Topical application of each ointment to the ventral surface of the tongue was performed once a day for 5days. The level of 8-hydroxydeoxyguanosine (8-OHdG) was determined to evaluate oxidative stress. Fluorescence staining was also performed to confirm nuclear factor erythroid 2-related factor 2 (Nrf2) translocation to the nucleus. After the experimental period, the ratios of 8-OHdG-positive cells in the ventral tongue tissue were higher in the positive control group than in the negative control group (Ptea catechin group, but not in the 0.1% green tea catechin group, were lower than the positive control group (Ptea catechin group than in the positive control group (Ptea catechins could prevent tongue oxidative stress in 5-FU administered rats, via up-regulation of the Nrf2 signaling pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cyclic steady states in diffusion-induced plasticity with applications to lithium-ion batteries

Science.gov (United States)

Peigney, Michaël

2018-02-01

Electrode materials in lithium-ion batteries offer an example of medium in which stress and plastic flow are generated by the diffusion of guest atoms. In such a medium, deformation and diffusion are strongly coupled processes. For designing electrodes with improved lifetime and electro-mechanical efficiency, it is crucial to understand how plasticity and diffusion evolve over consecutive charging-recharging cycles. With such questions in mind, this paper provides general results for the large-time behavior of media coupling plasticity with diffusion when submitted to cyclic chemo-mechanical loadings. Under suitable assumptions, we show that the stress, the plastic strain rate, the chemical potential and the flux of guest atoms converge to a cyclic steady state which is largely independent of the initial state. A special emphasis is laid on the special case of elastic shakedown, which corresponds to the situation where the plastic strain stops evolving after a sufficiently large number of cycles. Elastic shakedown is expected to be beneficial for the fatigue behavior and - in the case of lithium-ion batteries - for the electro-chemical efficiency. We provide a characterization of the chemo-mechanical loadings for which elastic shakedown occurs. Building on that characterization, we suggest a general method for designing structures in such fashion that they operate in the elastic shakedown regime, whatever the initial state is. An attractive feature of the proposed method is that incremental analysis of the fully coupled plasticity-diffusion problem is avoided. The results obtained are applied to the model problem of a battery electrode cylinder particle under cyclic charging. Closed-form expressions are obtained for the set of charging rates and charging amplitudes for which elastic shakedown occurs, as well as for the corresponding cyclic steady states of stress, lithium concentration and chemical potential. Some results for a spherical particle are also presented.

Effect of potassium application on ammonium nutrition in maize (zea mays l.) under salt stress

International Nuclear Information System (INIS)

Yousra, M.; Akhtar, J.; Saqib, A.; Haq, M.A

2012-01-01

Application of potassium has been found to minimize the toxic effect of NH/sup 4/sup +/ under salt stress. To study the interactive effect of K+ and NH4+ under saline condition, maize (Zea mays L., cv. Pioneer-3335) was grown in a hydroponic culture with ammonium (5.0 and 10 mM) as (NH/sub 4/)/sub 2/SO/ sub 4/ at two different levels (3.0 and 9.0 mM) of K+ under control and 100 mM NaCl. Under saline condition, 5 mM NH/sub 4/sup +/ application along with 3.0 mM K+ decreased the dry mass by 24% in maize while its addition at the rate of 10 mM showed a percent decline upto 70% than the control. A decrease in shoot dry mass induced by the combine application of 5.0 mM NH4+ and 9.0 mM K+ was 19% relative to control whilst a decrease i.e. 52% was observed at 10 mM NH/sub 4+/ level. The increasing concentration of potassium was found to alleviate the NH/sub 4+/ toxicity and salinity stress partly by inhibiting the uptake of NH/sub 4+/ and Na+ and by stimulating the N assimilation in plant body. Growth improvement at combination of 5.0 mM NH/sub 4+/ and 9.0 mM K+ was reinforced by higher K+ influx into root cells and its translocation to the growing tissues. Elevating the K+ supply also resulted in the enhanced plant growth several times and reduction in NH/sub 4+/ toxicity and salinity stress. (author)

Critical-like features of stress response in frictional packings

International Nuclear Information System (INIS)

Cakir, Abdullah; Silbert, Leonardo E

2015-01-01

The mechanical response of static, unconfined, overcompressed face centred cubic, granular arrays is studied using large-scale, discrete element method simulations. Specifically, the stress response due to the application of a localised force perturbation—the Green function technique—is obtained in granular packings generated over several orders of magnitude in both the particle friction coefficient and the applied forcing. We observe crossover behaviour in the mechanical state of the system characterised by the changing nature of the resulting stress response. The transition between anisotropic and isotropic stress response exhibits critical-like features through the identification of a diverging length scale that distinguishes the spatial extent of anisotropic regions from those that display isotropic behaviour. A multidimensional phase diagram is constructed that parameterises the response of the system due to changing friction and force perturbations. (paper)

A combination of He-Ne laser irradiation and exogenous NO application efficiently protect wheat seedling from oxidative stress caused by elevated UV-B stress.

Science.gov (United States)

Li, Yongfeng; Gao, Limei; Han, Rong

2016-12-01

The elevated ultraviolet-B (UV-B) stress induces the accumulation of a variety of intracellular reactive oxygen species (ROS), which seems to cause oxidative stress for plants. To date, very little work has been done to evaluate the biological effects of a combined treatment with He-Ne laser irradiation and exogenous nitric oxide (NO) application on oxidative stress resulting from UV-B radiation. Thus, our study investigated the effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative damages in wheat seedlings under elevated UV-B stress. Our data showed that the reductions in ROS levels, membrane damage parameters, while the increments in antioxidant contents and antioxidant enzyme activity caused by a combination with He-Ne laser and exogenous NO treatment were greater than those of each individual treatment. Furthermore, these treatments had a similar effect on transcriptional activities of plant antioxidant enzymes. This implied that the protective effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative stress resulting from UV-B radiation was more efficient than each individual treatment with He-Ne laser or NO molecule. Our findings might provide beneficial theoretical references for identifying some effective new pathways for plant UV-B protection.

Socio-economic applications of finite state mean field games

KAUST Repository

Gomes, Diogo A.

2014-10-06

In this paper, we present different applications of finite state mean field games to socio-economic sciences. Examples include paradigm shifts in the scientific community or consumer choice behaviour in the free market. The corresponding finite state mean field game models are hyperbolic systems of partial differential equations, for which we present and validate different numerical methods. We illustrate the behaviour of solutions with various numerical experiments,which show interesting phenomena such as shock formation. Hence, we conclude with an investigation of the shock structure in the case of two-state problems.

Work-related stress perception and hypertension amongst health workers of a mission hospital in Oyo State, south-western Nigeria

Directory of Open Access Journals (Sweden)

Akinwumi O. Owolabi

2012-04-01

Objective: This study was a work site cross-sectional descriptive study carried out amongst the health workers at the Baptist Medical Centre Ogbomoso, Oyo State, south-western Nigeria. The aim of the study was to discern the prevalence of perceived work stress and to explore the relationship between perceived work stress and the presence of hypertension. Methods: A total of 324 consenting health workers of the institution were administered the job demand-control questionnaire to assess work stress. A standardised questionnaire was used to collect socio-demographic data and other personal data. Measurements of blood pressure, weight and height were carried out and body mass indices were calculated. Results: More than a quarter (26.2% of the subjects perceived themself as stressed at work. The single largest group of hypertensive subjects was seen amongst subjects with work stress. Conclusion: A significant number of health workers in this study is afflicted by work-related stress and perceived work stress was found to be significantly associated with higher hypertension prevalence.

Construction and preliminary validation of the Barcelona Immigration Stress Scale.

Science.gov (United States)

Tomás-Sábado, Joaquín; Qureshi, Adil; Antonin, Montserrat; Collazos, Francisco

2007-06-01

In the study of mental health and migration, an increasing number of researchers have shifted the focus away from the concept of acculturation towards the stress present in the migratory experience. The bulk of research on acculturative stress has been carried out in the United States, and thus the definition and measurement of the construct has been predicated on that cultural and demographic context, which is of dubious applicability in Europe in general, and Spain in particular. Further, some scales have focused on international students, which down-played the importance of the migratory process, because it deals with a special subset of people who are not formally immigrating. The Barcelona Immigration Stress Scale was developed to measure acculturative stress appropriate to immigrants in Spain, using expert and focus group review and has 42 items. The scale shows acceptable internal validity, and, consistent with other scales, suggests that immigration stress is a complex construct.

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.

Lithospheric Strength and Stress State: Persistent Challenges and New Directions in Geodynamics

Science.gov (United States)

Hirth, G.

2017-12-01

The strength of the lithosphere controls a broad array of geodynamic processes ranging from earthquakes, the formation and evolution of plate boundaries and the thermal evolution of the planet. A combination of laboratory, geologic and geophysical observations provides several independent constraints on the rheological properties of the lithosphere. However, several persistent challenges remain in the interpretation of these data. Problems related to extrapolation in both scale and time (rate) need to be addressed to apply laboratory data. Nonetheless, good agreement between extrapolation of flow laws and the interpretation of microstructures in viscously deformed lithospheric mantle rocks demonstrates a strong foundation to build on to explore the role of scale. Furthermore, agreement between the depth distribution of earthquakes and predictions based on extrapolation of high temperature friction relationships provides a basis to understand links between brittle deformation and stress state. In contrast, problems remain for rationalizing larger scale geodynamic processes with these same rheological constraints. For example, at face value the lab derived values for the activation energy for creep are too large to explain convective instabilities at the base of the lithosphere, but too low to explain the persistence of dangling slabs in the upper mantle. In this presentation, I will outline these problems (and successes) and provide thoughts on where new progress can be made to resolve remaining inconsistencies, including discussion of the role of the distribution of volatiles and alteration on the strength of the lithosphere, new data on the influence of pressure on friction and fracture strength, and links between the location of earthquakes, thermal structure, and stress state.

Anxiety and psychosomatic symptoms in palliative care: from neuro-psychobiological response to stress, to symptoms' management with clinical hypnosis and meditative states.

Science.gov (United States)

Satsangi, Anirudh Kumar; Brugnoli, Maria Paola

2018-01-01

Psychosomatic disorder is a condition in which psychological stresses adversely affect physiological (somatic) functioning to the point of distress. It is a condition of dysfunction or structural damage in physical organs through inappropriate activation of the involuntary nervous system and the biochemical response. In this framework, this review will consider anxiety disorders, from the perspective of the psychobiological mechanisms of vulnerability to extreme stress in severe chronic illnesses. Psychosomatic medicine is a field of behavioral medicine and a part of the practice of consultation-liaison psychiatry. Psychosomatic medicine in palliative care, integrates interdisciplinary evaluation and management involving diverse clinical specialties including psychiatry, psychology, neurology, internal medicine, allergy, dermatology, psychoneuroimmunology, psychosocial oncology and spiritual care. Clinical conditions where psychological processes act as a major factor affecting medical outcomes are areas where psychosomatic medicine has competence. Thus, the psychosomatic symptom develops as a physiological connected of an emotional state. In a state of rage or fear, for example, the stressed person's blood pressure is likely to be elevated and his pulse and respiratory rate to be increased. When the fear passes, the heightened physiologic processes usually subside. If the person has a persistent fear (chronic anxiety), however, which he is unable to express overtly, the emotional state remains unchanged, though unexpressed in the overt behavior, and the physiological symptoms associated with the anxiety state persist. This paper wants highlight how clinical hypnosis and meditative states can be important psychosocial and spiritual care, for the symptom management on neuro-psychobiological response to stress.

Food irradiation in the United States

International Nuclear Information System (INIS)

Pauli, G.H.

1991-01-01

Since 1963, some irradiated foods have been permitted for sale in the United States. Yet, at this time, commercial application has been limited to irradiation of a relatively small fraction of the spices and seasonings used as ingredients in other foods. The current situation regarding irradiated foods in the United States and how it developed is discussed. The author writes from experience gained as a Government regulator concerned primarily with ensuring safety of food and therefore this is stressed together with the crucial role played by consumers and industry. (author)

Modelling residual stresses in friction stir welding of Al alloys - a review of possibilities and future trends

DEFF Research Database (Denmark)

Hattel, Jesper Henri; Sonne, Mads Rostgaard; Tutum, Cem C.

2015-01-01

Residual stresses are very important in any joining process of materials since they act as pre-stresses in the loading situation of the joint, thereby affecting the final mechanical performance of the component. This is also the case for friction stir welding (FSW) which is a complex solid-state ......, numerical framework and application as well as putting them into proper context with respect to some of the new trends in the field, e.g. coupling with subsequent load analyses of the in-service situation or applying residual stress models of FSWin numerical optimization.......Residual stresses are very important in any joining process of materials since they act as pre-stresses in the loading situation of the joint, thereby affecting the final mechanical performance of the component. This is also the case for friction stir welding (FSW) which is a complex solid......-state joining process characterized by a pronounced multiphysical behaviour involving phenomena such as change of temperature, material flow, change of microstructures and formation of residual stresses. Thus, models of FSWare typically divided into thermal models, flow models, residual stress models...

Fabrication of imitative stress corrosion cracking specimens suitable for electromagnetic nondestructive evaluations using solid state bonding

International Nuclear Information System (INIS)

Yusa, Noritaka; Hashizume, Hidetoshi; Uchimoto, Tetsuya; Takagi, Toshiyuki

2010-01-01

This study proposes a method to fabricate artificial defects that is almost identical to stress corrosion cracking from the viewpoint of electromagnetic nondestructive evaluations. The key idea is to realize a region having electrical resistance embedded inside a conductive materials using solid state bonding. A rough region is introduced into the surface of the materials so that the region is partially bonded to realize electrical resistance. The validity of the method is demonstrated using type 316L austenitic stainless steels. Eddy current tests and subsequent destructive tests confirm that signals due to the fabricated specimens are very similar to those due to stress corrosion cracks. (author)

40 CFR 122.22 - Signatories to permit applications and reports (applicable to State programs, see § 123.25).

Science.gov (United States)

2010-07-01

... POLLUTANT DISCHARGE ELIMINATION SYSTEM Permit Application and Special NPDES Program Requirements § 122.22... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Signatories to permit applications and reports (applicable to State programs, see § 123.25). 122.22 Section 122.22 Protection of Environment...

Solid state fermentation (SSF): diversity of applications to valorize waste and biomass.

Science.gov (United States)

Lizardi-Jiménez, M A; Hernández-Martínez, R

2017-05-01

Solid state fermentation is currently used in a range of applications including classical applications, such as enzyme or antibiotic production, recently developed products, such as bioactive compounds and organic acids, new trends regarding bioethanol and biodiesel as sources of alternative energy, and biosurfactant molecules with environmental purposes of valorising unexploited biomass. This work summarizes the diversity of applications of solid state fermentation to valorize biomass regarding alternative energy and environmental purposes. The success of applying solid state fermentation to a specific process is affected by the nature of specific microorganisms and substrates. An exhaustive number of microorganisms able to grow in a solid matrix are presented, including fungus such as Aspergillus or Penicillum for antibiotics, Rhizopus for bioactive compounds, Mortierella for biodiesel to bacteria, Bacillus for biosurfactant production, or yeast for bioethanol.

How Do You #relax When You're #stressed? A Content Analysis and Infodemiology Study of Stress-Related Tweets.

Science.gov (United States)

Doan, Son; Ritchart, Amanda; Perry, Nicholas; Chaparro, Juan D; Conway, Mike

2017-06-13

Stress is a contributing factor to many major health problems in the United States, such as heart disease, depression, and autoimmune diseases. Relaxation is often recommended in mental health treatment as a frontline strategy to reduce stress, thereby improving health conditions. Twitter is a microblog platform that allows users to post their own personal messages (tweets), including their expressions about feelings and actions related to stress and stress management (eg, relaxing). While Twitter is increasingly used as a source of data for understanding mental health from a population perspective, the specific issue of stress-as manifested on Twitter-has not yet been the focus of any systematic study. The objective of our study was to understand how people express their feelings of stress and relaxation through Twitter messages. In addition, we aimed at investigating automated natural language processing methods to (1) classify stress versus nonstress and relaxation versus nonrelaxation tweets, and (2) identify first-hand experience-that is, who is the experiencer-in stress and relaxation tweets. We first performed a qualitative content analysis of 1326 and 781 tweets containing the keywords "stress" and "relax," respectively. We then investigated the use of machine learning algorithms-in particular naive Bayes and support vector machines-to automatically classify tweets as stress versus nonstress and relaxation versus nonrelaxation. Finally, we applied these classifiers to sample datasets drawn from 4 cities in the United States (Los Angeles, New York, San Diego, and San Francisco) obtained from Twitter's streaming application programming interface, with the goal of evaluating the extent of any correlation between our automatic classification of tweets and results from public stress surveys. Content analysis showed that the most frequent topic of stress tweets was education, followed by work and social relationships. The most frequent topic of relaxation tweets

Solid-state Memory on Flexible Silicon for Future Electronic Applications

KAUST Repository

Ghoneim, Mohamed

2016-11-01

Advancements in electronics research triggered a vision of a more connected world, touching new unprecedented fields to improve the quality of our lives. This vision has been fueled by electronic giants showcasing flexible displays for the first time in consumer electronics symposiums. Since then, the scientific and research communities partook on exploring possibilities for making flexible electronics. Decades of research have revealed many routes to flexible electronics, lots of opportunities and challenges. In this work, we focus on our contributions towards realizing a complimentary approach to flexible inorganic high performance electronic memories on silicon. This approach provides a straight forward method for capitalizing on the existing well-established semiconductor infrastructure, standard processes and procedures, and collective knowledge. Ultimately, we focus on understanding the reliability and functionality anomalies in flexible electronics and flexible solid state memory built using the flexible silicon platform. The results of the presented studies show that: (i) flexible devices fabricated using etch-protect-release approach (with trenches included in the active area) exhibit ~19% lower safe operating voltage compared to their bulk counterparts, (ii) they can withstand prolonged bending duration (static stress) but are prone to failure under dynamic stress as in repeated bending and re-flattening, (iii) flexible 3D FinFETs exhibit ~10% variation in key properties when exposed to out-of-plane bending stress and out-of-plane stress does not resemble the well-studied in-plane stress used in strain engineering, (iv) resistive memories can be achieved on flexible silicon and their basic resistive property is preserved but other memory functionalities (retention, endurance, speed, memory window) requires further investigations, (v) flexible silicon based PZT ferroelectric capacitors exhibit record polarization, capacitance, and endurance (1 billion

A methodology for interpretation of overcoring stress measurements in anisotropic rock

International Nuclear Information System (INIS)

Hakala, M.; Sjoeberg, J.

2006-11-01

The in situ state of stress is an important parameter for the design of a repository for final disposal of spent nuclear fuel. This report presents work conducted to improve the quality of overcoring stress measurements, focused on the interpretation of overcoring rock stress measurements when accounting for possible anisotropic behavior of the rock. The work comprised: (i) development/upgrading of a computer code for calculating stresses from overcoring strains for anisotropic materials and for a general overcoring probe configuration (up to six strain rosettes with six gauges each), (ii) development of a computer code for determining elastic constants for transversely isotropic rocks from biaxial testing, and (iii) analysis of case studies of selected overcoring measurements in both isotropic and anisotropic rocks from the Posiva and SKB sites in Finland and Sweden, respectively. The work was principally limited to transversely isotropic materials, although the stress calculation code is applicable also to orthotropic materials. The developed computer codes have been geared to work primarily with the Borre and CSIRO HI three-dimensional overcoring measurement probes. Application of the codes to selected case studies, showed that the developed tools were practical and useful for interpreting overcoring stress measurements conducted in anisotropic rock. A quantitative assessment of the effects of anisotropy may thus be obtained, which provides increased reliability in the stress data. Potential gaps in existing data and/or understanding can also be identified. (orig.)

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...

Shielding Flowers Developing under Stress: Translating Theory to Field Application

Directory of Open Access Journals (Sweden)

Noam Chayut

2014-07-01

Full Text Available Developing reproductive organs within a flower are sensitive to environmental stress. A higher incidence of environmental stress during this stage of a crop plants’ developmental cycle will lead to major breaches in food security. Clearly, we need to understand this sensitivity and try and overcome it, by agricultural practices and/or the breeding of more tolerant cultivars. Although passion fruit vines initiate flowers all year round, flower primordia abort during warm summers. This restricts the season of fruit production in regions with warm summers. Previously, using controlled chambers, stages in flower development that are sensitive to heat were identified. Based on genetic analysis and physiological experiments in controlled environments, gibberellin activity appeared to be a possible point of horticultural intervention. Here, we aimed to shield flowers of a commercial cultivar from end of summer conditions, thus allowing fruit production in new seasons. We conducted experiments over three years in different settings, and our findings consistently show that a single application of an inhibitor of gibberellin biosynthesis to vines in mid-August can cause precocious flowering of ~2–4 weeks, leading to earlier fruit production of ~1 month. In this case, knowledge obtained on phenology, environmental constraints and genetic variation, allowed us to reach a practical solution.

Low-stress silicon nitride layers for MEMS applications

Science.gov (United States)

Iliescu, Ciprian; Wei, Jiashen; Chen, Bangtao; Ong, Poh Lam; Tay, Francis E. H.

2006-12-01

The paper presents two deposition methods for generation of SiN x layers with "zero" residual stress in PECVD reactors: mixed frequency and high power in high frequency mode (13.56 MHz). Traditionally, mix frequency mode is commonly used to produce low stress SiN x layers, which alternatively applies the HF and LF mode. However, due to the low deposition rate of LF mode, the combined deposition rate of mix frequency is quite small in order to produce homogenous SiN x layers. In the second method, a high power which was up to 600 W has been used, may also produce low residual stress (0-20 MPa), with higher deposition rate (250 to 350 nm/min). The higher power not only leads to higher dissociation rates of gases which results in higher deposition rates, but also brings higher N bonding in the SiN x films and higher compressive stress from higher volume expansion of SiN x films, which compensates the tensile stress and produces low residual stress. In addition, the paper investigates the influence of other important parameters which have great impact to the residual stress and deposition rates, such as reactant gases flow rate and pressure. By using the final optimized recipe, masking layer for anisotropic wet etching in KOH and silicon nitride cantilever have been successfully fabricated based on the low stress SiN x layers. Moreover, nanoporous membrane with 400nm pores has also been fabricated and tested for cell culture. By cultivating the mouse D1 mesenchymal stem cells on top of the nanoporous membrane, the results showed that mouse D1 mesenchymal stem cells were able to grow well. This shows that the nanoporous membrane can be used as the platform for interfacing with living cells to become biocapsules for biomolecular separation.

Socio-economic applications of finite state mean field games

KAUST Repository

Gomes, Diogo A.; Machado Velho, Roberto; Wolfram, Marie Therese

2014-01-01

In this paper, we present different applications of finite state mean field games to socio-economic sciences. Examples include paradigm shifts in the scientific community or consumer choice behaviour in the free market. The corresponding finite

Development and validation of a 3D-printed interfacial stress sensor for prosthetic applications.

Science.gov (United States)

Laszczak, P; Jiang, L; Bader, D L; Moser, D; Zahedi, S

2015-01-01

A novel capacitance-based sensor designed for monitoring mechanical stresses at the stump-socket interface of lower-limb amputees is described. It provides practical means of measuring pressure and shear stresses simultaneously. In particular, it comprises of a flexible frame (20 mm × 20 mm), with thickness of 4mm. By employing rapid prototyping technology in its fabrication, it offers a low-cost and versatile solution, with capability of adopting bespoke shapes of lower-limb residua. The sensor was first analysed using finite element analysis (FEA) and then evaluated using lab-based electromechanical tests. The results validate that the sensor is capable of monitoring both pressure and shear at stresses up to 350 kPa and 80 kPa, respectively. A post-signal processing model is developed to induce pressure and shear stresses, respectively. The effective separation of pressure and shear signals can be potentially advantageous for sensor calibration in clinical applications. The sensor also demonstrates high linearity (approx. 5-8%) and high pressure (approx. 1.3 kPa) and shear (approx. 0.6 kPa) stress resolution performance. Accordingly, the sensor offers the potential for exploitation as an assistive tool to both evaluate prosthetic socket fitting in clinical settings and alert amputees in home settings of excessive loading at the stump-socket interface, effectively preventing stump tissue breakdown at an early stage. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

Countermeasures to stress corrosion cracking by stress improvement

International Nuclear Information System (INIS)

Umemoto, Tadahiro

1983-01-01

One of the main factors of the grain boundary stress corrosion cracking occurred in the austenitic stainless steel pipes for reactor cooling system was the tensile residual stress due to welding, and a number of methods have been proposed to reduce the residual stress or to change it to compressive stress. In this paper, on the method of improving residual stress by high frequency heating, which has been applied most frequently, the principle, important parameters and the range of application are explained. Also the other methods of stress improvement are outlined, and the merit and demerit of respective methods are discussed. Austenitic stainless steel and high nickel alloys have good corrosion resistance, high toughness and good weldability, accordingly they have been used for reactor cooling system, but stress corrosion cracking was discovered in both BWRs and PWRs. It occurs when the sensitization of materials, tensile stress and the dissolved oxygen in high temperature water exceed certain levels simultaneously. The importance of the residual stress due to welding, induction heating stress improvement, and other methods such as heat sink welding, last pass heat sink welding, back lay welding and TIG torch heating stress improvement are described. (Kako, I.)

Irradiation creep, stress relaxation and a mechanical equation of state

International Nuclear Information System (INIS)

Foster, J.P.

1976-01-01

Irradiation creep and stress relaxation data are available from the United Kingdom for 20 percent CW M316, 20 percent CW FV 548 and FHT PE16 using pure torsion in the absence of swelling at 300 0 C. Irradiation creep models were used to calculate the relaxation and permanent deflection of the stress relaxation tests. Two relationships between irradiation creep and stress relaxation were assessed by comparing the measured and calculated stress relaxation and permanent deflection. The results show that for M316 and FV548, the stress relaxation and deflection may be calculated using irradiation creep models when the stress rate term arising from the irradiation creep model is set equal to zero. In the case of PE16, the inability to calculate the stress relaxation and permanent deflection from the irradiation creep data was attributed to differences in creep behavior arising from lot-to-lot variations in alloying elements and impurity content. A modification of the FV548 and PE16 irradiation creep coefficients was necessary in order to calculate the stress relaxation and deflection. The modifications in FV548 and PE16 irradiation creep properties reduces the large variation in the transient or incubation parameter predicted by irradiation creep tests for M316, FV548 and PE16

Effect of Smart Meter Measurements Data On Distribution State Estimation

DEFF Research Database (Denmark)

Pokhrel, Basanta Raj; Nainar, Karthikeyan; Bak-Jensen, Birgitte

2018-01-01

in the physical grid can enforce significant stress not only on the communication infrastructure but also in the control algorithms. This paper aims to propose a methodology to analyze needed real time smart meter data from low voltage distribution grids and their applicability in distribution state estimation...

A literature review of the application of the Geriatric Depression Scale, Depression Anxiety Stress Scales and Post-traumatic Stress Disorder Checklist to community nursing cohorts.

Science.gov (United States)

Allen, Jacqui; Annells, Merilyn

2009-04-01

To explore through literature review the appropriateness of three common tools for use by community nurses to screen war veteran and war widow(er) clients for depression, anxiety and post-traumatic stress disorder. War veterans and, to a lesser extent, war widow(er)s, are prone to mental health challenges, especially depression, anxiety and post-traumatic stress disorder. Community nurses do not accurately identify such people with depression and related disorders although they are well positioned to do so. The use of valid and reliable self-report tools is one method of improving nurses' identification of people with actual or potential mental health difficulties for referral to a general practitioner or mental health practitioner for diagnostic assessment and treatment. The Geriatric Depression Scale, Depression Anxiety Stress Scales and Post-traumatic Stress Disorder Checklist are frequently recommended for mental health screening but the appropriateness of using the tools for screening war veteran and war widow(er) community nursing clients who are often aged and have functional impairment, is unknown. Systematic review. Current literature informs that the Geriatric Depression Scale accurately predicts a diagnosis of depression in community nursing cohorts. The three Depression Anxiety Stress Scales subscales of depression, anxiety and stress are valid; however, no studies were identified that compared the performance of the Depression Anxiety Stress Scales in predicting diagnoses of depression or anxiety. The Post-traumatic Stress Disorder Checklist predicts post-traumatic stress disorder in community cohorts although no studies meeting the selection criteria included male participants. This review provides recommendations for the use of the Geriatric Depression Scale, Depression Anxiety Stress Scales and The Post-traumatic Stress Disorder Checklist based on examination of the published evidence for the application of these screening tools in samples

Improvement of phytoextraction and antioxidative defense in Solanum nigrum L. under cadmium stress by application of cadmium-resistant strain and citric acid

Energy Technology Data Exchange (ETDEWEB)

Gao Yang, E-mail: gaoyang0898@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai, 200240 (China); Key Laboratory of Soil and Water Conservation and Desertification Control, College of Soil and Water Conservation, Beijing Forestry University, Beijing 100083 (China); Miao Chiyuan [Department of Environmental Engineering, Peking University, Beijing, 100871 (China); Mao Liang [School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai, 200240 (China); School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240 (China); Zhou Pei [School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240 (China); Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai 200240 (China); Jin Zhiguo; Shi Wanjun [School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai, 200240 (China)

2010-09-15

Remediation of plant-microorganism-chelates synergy has been proposed as an effective remediation method for enhancing the removal efficiency of heavy metal. Manipulation of the antioxidative system increases plant tolerance, thereby potentially enhancing the uptake capacity to heavy metal. In this study, we investigated the possibility of improving the phytoextraction of Cd and the antioxidative defense of Solanum nigrum L. by application of a new isolated strain (Paecilomyces lilacinus NH1) (PLNH1) and citric acid (CA). The results showed that application of CA or PLNH1 significantly promoted S. nigrum's growth under Cd stress, but the synergistic effect of CA and PLNH1 on S. nigrum's growth was more obvious. The coexistence of CA and PLNH1 could enhance about 30% of Cd accumulation in different organs of S. nigrum compared to the treatment without the addition of CA and PLNH1, whereas single CA or PLNH1 added treatment only enhanced about 10-15% of Cd accumulation in different organs of S. nigrum. The antioxidative defense in S. nigrum under Cd stress was significantly improved as result of application of CA and PLNH1. The responses of antioxidative enzymes to Cd stress significantly decreased following application of CA and PLNH1, and the oxidative stress experienced by the plant due to Cd in the soil was significantly alleviated.

Improvement of phytoextraction and antioxidative defense in Solanum nigrum L. under cadmium stress by application of cadmium-resistant strain and citric acid

International Nuclear Information System (INIS)

Gao Yang; Miao Chiyuan; Mao Liang; Zhou Pei; Jin Zhiguo; Shi Wanjun

2010-01-01

Remediation of plant-microorganism-chelates synergy has been proposed as an effective remediation method for enhancing the removal efficiency of heavy metal. Manipulation of the antioxidative system increases plant tolerance, thereby potentially enhancing the uptake capacity to heavy metal. In this study, we investigated the possibility of improving the phytoextraction of Cd and the antioxidative defense of Solanum nigrum L. by application of a new isolated strain (Paecilomyces lilacinus NH1) (PLNH1) and citric acid (CA). The results showed that application of CA or PLNH1 significantly promoted S. nigrum's growth under Cd stress, but the synergistic effect of CA and PLNH1 on S. nigrum's growth was more obvious. The coexistence of CA and PLNH1 could enhance about 30% of Cd accumulation in different organs of S. nigrum compared to the treatment without the addition of CA and PLNH1, whereas single CA or PLNH1 added treatment only enhanced about 10-15% of Cd accumulation in different organs of S. nigrum. The antioxidative defense in S. nigrum under Cd stress was significantly improved as result of application of CA and PLNH1. The responses of antioxidative enzymes to Cd stress significantly decreased following application of CA and PLNH1, and the oxidative stress experienced by the plant due to Cd in the soil was significantly alleviated.

Evaluation of Pressure Pain Threshold as a Measure of Perceived Stress and High Job Strain

DEFF Research Database (Denmark)

Hven, Lisbeth; Frost, Poul; Bonde, Jens Peter Ellekilde

2017-01-01

pressure pain algometry measurements of PPT on the trapezius and supraspinatus muscles and the tibia. Associations of stress symptoms and job strain with PPT of each site was analyzed for men and women separately with adjustment for age body mass index, and discomfort in the anatomical region closest...... to the point of pressure algometry using multivariable linear regression. RESULTS: We found significant inverse associations between perceived stress and PPT in both genders in models adjusting for age and body mass index: the higher level of perceived stress, the lower the threshold. For job strain...... associations between perceived stress and PPT, the discriminative capability of PPT to distinguish individuals with and without stress is low. PPT measured by pressure algometry seems not applicable as a diagnostic tool of a state of mental stress....

Title: Potassium application regulates nitrogen metabolism and osmotic adjustment in cotton (Gossypium hirsutum L.) functional leaf under drought stress.

Science.gov (United States)

Zahoor, Rizwan; Zhao, Wenqing; Abid, Muhammad; Dong, Haoran; Zhou, Zhiguo

2017-08-01

To evaluate the role of potassium (K) in maintaining nitrogen metabolism and osmotic adjustment development of cotton functional leaves to sustain growth under soil drought and rewatering conditions, the plants of two cotton cultivars Siza 3 (low-K sensitive) and Simian 3 (low-K tolerant), were grown under three different K rates (K0, K1, and K2; 0, 150, and 300kgK 2 Oha -1 , respectively) and exposed to drought stress with 40±5% soil relative water content (SRWC). The drought stress was applied at flowering stage by withholding water for eight days followed by rewatering to a well-watered level (75±5% SRWC). The results showed that drought-stressed plants of both cultivars showed a decrease in leaf relative water content (RWC) and osmotic potential in the functional leaves and developed osmotic adjustment with an increase in the contents of free amino acids, soluble sugars, inorganic K, and nitrate as compared to well-watered plants. In drought-stressed plants, nitrogen-metabolizing enzyme activities of nitrogen reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) were diminished significantly (P≤0.05) along with decreased chlorophyll content and soluble proteins. However, drought-stressed plants under K application not only exhibited higher osmotic adjustment with greater accumulation of osmolytes but also regulated nitrogen metabolism by maintaining higher enzyme activities, soluble proteins, and chlorophyll content in functional leaves as compared to the plants without K application. Siza 3 showed better stability in enzyme activities and resulted in 89% higher seed cotton yield under K2 as compared to K0 in drought-stressed plants, whereas this increase was 53% in the case of Simian 3. The results of the study suggested that K application enhances cotton plants' potential for sustaining high nitrogen-metabolizing enzyme activities and related components to supplement osmotic adjustment under soil drought conditions. Copyright © 2017

In-situ stress analysis with X-Ray diffraction for yield locus characterization of sheet metals

Energy Technology Data Exchange (ETDEWEB)

Güner, A.; Tekkaya, A. E. [Institute of Forming Technology and Lightweight Construction, TU Dortmund University, Baroper Str. 301, 44227 Dortmund (Germany); Zillmann, B.; Lampke, T. [Institute of Materials Science and Engineering, Chemnitz University of Technology, Erfenschlager Strasse 73 D-09125 Chemnitz (Germany)

2013-12-16

A main problem in the field of sheet metal characterization is the inhomogeneous plastic deformation in the gauge regions of specimens which causes the analytically calculated stresses to differ from the sought state of stress acting in the middle of the gauge region. To overcome this problem, application of X-Ray diffraction is analyzed. For that purpose a mobile X-ray diffractometer and an optical strain measurement system are mounted on a universal tensile testing machine. This enables the recording of the whole strain and stress history of a material point. The method is applied to uniaxial tension tests, plane strain tension tests and shear tests to characterize the interstitial free steel alloy DC06. The applicability of the concepts of stress factors is verified by uniaxial tension tests. The experimentally obtained values are compared with the theoretical values calculated with crystal elasticity models utilizing the orientation distribution functions (ODF). The relaxation problem is addressed which shows itself as drops in the stress values with the strain kept at a constant level. This drop is analyzed with elasto-viscoplastic material models to correct the measured stresses. Results show that the XRD is applicable to measure the stresses in sheet metals with preferred orientation. The obtained yield locus is expressed with the Yld2000–2D material model and an industry oriented workpiece is analyzed numerically. The comparison of the strain distribution on the workpiece verifies the identified material parameters.

Stress state and its anomaly observations in the vicinity of a fault in NanTroSEIZE Expedition 322

Science.gov (United States)

Wu, Hung-Yu; Saito, Saneatsu; Kinoshita, Masataka

2015-12-01

To better understand the stress state and geological properties within the shallow Shikoku Basin, southwest of Japan, two sites, C0011A and C0011B, were drilled in open-ocean sediments using Logging While Drilling (LWD) and coring, respectively. Resistivity image logging was performed at C0011A from sea floor to 950 m below sea floor (mbsf). At C0011B, the serial coring was obtained in order to determine physical properties from 340 to 880 mbsf. For the LWD images, a notable breakout anomaly was observed at a depth of 615 m. Using resistivity images and a stress polygon, the potential horizontal principal stress azimuth and its magnitude within the 500-750 mbsf section of the C0011A borehole were constrained. Borehole breakout azimuths were observed for the variation by the existence of a fault zone at a depth of 615 mbsf. Out of this fracture zone, the breakout azimuth was located at approximately 109° ± 12°, subparallel to the Nankai Trough convergence vector (300-315°). Our calculations describe a stress drop was determined based on the fracture geometry. A close 90° (73° ± 12°) rotation implied a 100% stress drop, defined as a maximum shear stress drop equal to 1 MPa. The magnitude of the horizontal principal stresses near the fracture stress anomaly ranged between 49 and 52 MPa, and the bearing to the vertical stress (Sv = 52 MPa) was found to be within the normal-faulting stress regime. Low rock strength and a low stress level are necessary to satisfy the observations.

Stressed and strained state for cermetic-rod-type fuel element

International Nuclear Information System (INIS)

Kulikov, I.S.

1987-01-01

Calculation technique for designing the stress-strained state of a cermetic rod-type fuel element has been proposed. The technique is based on the time-dependent step-by-step method and the solution of the deformation equilibrium equation for continuous and thick-wall long cylinders at every temporal step by the finite difference method. Additional strains, caused by thermal expansion and radiation swelling, have been taken into account. The transion from the non-contact model to the stiff-contact model has been provided in the case of cladding-fuel gap dissappearing in one or a number of cross-sections along the fuel element height. The method is supplemented by the formula for fuel cans stability estimation in the case of high coolant external pressure. The example of estimation of the cermetic-rod-type fuel elements are considered as an example

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...

Effect of different levels of foliar application of potassium on hysun-33 and ausigold-4 sunflower (helianthus annuus l.) cultivars under salt stress

International Nuclear Information System (INIS)

Arshadullah, M.; Ali, A.; Hyder, I.; Mahmood, I.A.; Zaman, B.U.

2014-01-01

A hydroponic study was conducted to see the growth response of two cultivars of sunflower (Hysun-33 and Ausigold-4) to K+ nutrition under salt stress during the growing season 2011, at National Agriculture Research Centre, Islamabad, Pakistan. Nursery of Helianthus annuus was raised in sand and ten-day old seedlings per hole were transplanted in each pot having four holes per pot lid. Half strength Hoagland's nutrient solution was filled in each pot. After the establishment of seedlings, salt stress (6 dS/m) was developed artificially. The treatments were, control, 2 and 4 % K + as K/sub 2/SO/sub 4/ foliar applications. Salt present in the growing medium caused a significant (P<0.00l), reduction in fresh and dry weights of sunflower. Salt stress suppresses the K uptake from pot. Application of varying levels of K/sub 2/SO/sub 4/ improved the fresh and dry weights of sunflower under both control and saline conditions. However, the highest increase in fresh and dry weight of control and stressed plants was observed when 2% K was applied. Further increase in the level of K application did not improve fresh and dry weights of salt stress and unstressed plants. The growth medium salts reduced sunflower growth. (author)

Residual stress evaluation by neutron diffraction. Some industrial applications and perspectives

International Nuclear Information System (INIS)

Rogante, M.

2001-01-01

Materials and components of technological and industrial interest can present Residual Stresses (RS), that can be generated during the manufacturing process - e. g. extruding, welding, and forging -, or as a consequence of plastic deformations or thermal treatments. When RS add to external loads, they can enhance fatigue processes, earlier inducing failure of the component. Examples of RS determination in industrial applications are reported: the one focuses on AA 6082 alloy extruded samples, the other on a 2,25Cr1Mo ferritic steel welded pipe after thermal treatment. Other examples are shown, successively, concerning particular industrial problems which need to be studied also by adopting the same technique. (R.P.)

State Waste Discharge Permit application: 200-W Powerhouse Ash Pit

Energy Technology Data Exchange (ETDEWEB)

Atencio, B.P.

1994-06-01

As part of the Hanford Federal Facility Agreement and Consent Order negotiations; the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. This document constitutes the State Waste Discharge Permit application for the 200-W Powerhouse Ash Pit. The 200-W Powerhouse Ash Waste Water discharges to the 200-W Powerhouse Ash Pit via dedicated pipelines. The 200-W Powerhouse Ash Waste Water is the only discharge to the 200-W Powerhouse Ash Pit. The 200-W Powerhouse is a steam generation facility consisting of a coal-handling and preparation section and boilers.

State Waste Discharge Permit application: 200-E Powerhouse Ash Pit

Energy Technology Data Exchange (ETDEWEB)

Atencio, B.P.

1994-06-01

As part of the Hanford Federal Facility Agreement and Consent Order negotiations, the US Department and Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect groundwater would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. This document constitutes the State Waste Discharge Permit application for the 200-E Powerhouse Ash Pit. The 200-E Powerhouse Ash Waste Water discharges to the 200-E Powerhouse Ash Pit via dedicated pipelines. The 200-E Ash Waste Water is the only discharge to the 200-E Powerhouse Ash Pit. The 200-E Powerhouse is a steam generation facility consisting of a coal-handling and preparation section and boilers.

76 FR 17391 - Applications for New Awards; United States-Brazil Higher Education Consortia Program

Science.gov (United States)

2011-03-29

... DEPARTMENT OF EDUCATION Applications for New Awards; United States-Brazil Higher Education...: United States (U.S.)- Brazil Higher Education Consortia Program Notice inviting applications for new... projects that include a plan to work with an institution of higher education (IHE) in another country in...

Thermal stress state of cryogenic HP vessels under freezing and pressurization

International Nuclear Information System (INIS)

Tsybenko, A.S.; Kuranov, B.A.; Chepurnoj, A.D.; Shaposhnikov, V.A.; Krishchuk, N.G.

1986-01-01

A mathematical model is developed for thermomechanical processes in cryogenic HP vessels under freezing either by liquid and (or) gaseous cryogen and under pressurization. Equations of nonlinear nonstationary thermal conductivity and nonisothermal thermoelastoplasticity are used for the case of the theory off low with isotropic hardening. Semiempiricaldependences of nonstationary heat exchange for gaseous medium, experimental curves of cryogenic liquid boiling, mass exchange relationships are allowed for when formulating boundary conditions. The mathematical modelis realized on the basi of the finite element method in the form of highly automated program complex TERSOD (heat resistanceof vessels), oriented for computer of the Unified System. Heat and stress-strained states for three constructions of vessels are thoroughly studied under different conditions of gaseous, liquid and combined freezing with subsequent pressurization

Socio-economic applications of finite state mean field games.

Science.gov (United States)

Gomes, Diogo; Velho, Roberto M; Wolfram, Marie-Therese

2014-11-13

In this paper, we present different applications of finite state mean field games to socio-economic sciences. Examples include paradigm shifts in the scientific community or consumer choice behaviour in the free market. The corresponding finite state mean field game models are hyperbolic systems of partial differential equations, for which we present and validate different numerical methods. We illustrate the behaviour of solutions with various numerical experiments, which show interesting phenomena such as shock formation. Hence, we conclude with an investigation of the shock structure in the case of two-state problems. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Effect of Silicon application on Morpho-physiological Characteristics, Grain Yield and Nutrient Content of Bread Wheat under Water Stress Conditions

Directory of Open Access Journals (Sweden)

A. Karmollachaab

2015-03-01

Full Text Available In order to investigate the effect of silicon application on some physiological characteristics, yield and yield components, and grain mineral contents of bread wheat (Triticum aestivum under water stress condition, an experiment was conducted in Ramin Agriculture and Natural Resources University, Khuzestan, in 2012. The experiment was arranged in split-plots design in RCBD (Completely Randomized Blocks Design with three replications. Treatments consisted of drought stress (irrigation after 25, 50 and 75% depletion of Available Water Content in main plots and silicon (0, 10, 20 and 30 Kg Si ha-1 arranged in sub-plots. Results showed that the effect of drought stress was significant on most traits and led to the increase of electrolyte leakage (EL, cuticular wax, leaf and grain silicon content and grain nitrogen content. But drought led to negative impacts on grain yield and its components, and leaf potassium content, i.e. moderate and severe stresses reduced yield by 17% and 38% compared to control, respectively. Effect of silicon application was significant on all traits except for spike per square meter. Silicon had the greatest impact on EL and led to 35% decrease in this trait. Also, silicon led to increase in leaf and grain silicon contents and grain K content and grain yield and yield components, when applied at 30 kg ha-1. Generally, application of 30 kg ha-1 of silicon led to 6 and 14% increases of grain yield at the presence of moderate and severe drought stresses, respectively. Thus, given the abundance of silicon it can be used as an ameliorating element for planting bread wheat in drought-prone conditions.

Elevated oxidative stress monitored via the albumin-thiol redox state is correlated with matrix metalloproteinase-3 elevation in patients with rheumatoid arthritis.

Science.gov (United States)

Kizaki, Kazuha; Yoshizumi, Yusuke; Takahashi, Teppei; Era, Seiichi

2015-01-01

In rheumatoid arthritis (RA), matrix metalloproteinase-3 (MMP-3) and oxidative stress contribute to joint destruction. However, little is known about the relationship between MMP-3 and oxidative stress in RA. We measured the albumin-thiol redox state as a marker of oxidative stress, MMP-3, and the DAS-28 score calculated using CRP values among forty-seven patients (9 males and 38 females) with RA. According to the serum MMP-3 levels, they were divided into two groups (group A: within normal ranges of 36.9-121.0 ng/mL for men and 17.3-59.7 ng/mL for women; group B: above normal ranges). The albumin-thiol redox state in group B was significantly oxidized compared with that in group A (p < 0.01). The percentage of oxidized albumin-thiol showed a positive correlation with serum MMP-3 (r = 0.52). DAS-28 and CRP were also correlated with the percentage of oxidized albumin-thiol (r = 0.46, r = 0.44). The albumin-thiol redox state was significantly oxidized in correlation with serum MMP-3 elevation in RA.

State waste discharge permit application for cooling water and condensate discharges

Energy Technology Data Exchange (ETDEWEB)

Haggard, R.D.

1996-08-12

The following presents the Categorical State Waste Discharge Permit (SWDP) Application for the Cooling Water and Condensate Discharges on the Hanford Site. This application is intended to cover existing cooling water and condensate discharges as well as similar future discharges meeting the criteria set forth in this document.

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.

Evaluation of stresses generated in steel finger joint of bridge by X-ray stress measurement

International Nuclear Information System (INIS)

Kohri, Ami; Kawano, Yutaka; Nishido, Takayuki

2017-01-01

In a steel bridge, the evaluation of the stress generated in the finger joint without a gap to absorb temperature change can be an index when evaluating the remaining life. This study chose as the object the finger joint of a diagonal bridge, where the generated stress state is considered to be more complicated, prepared a finger joint test specimen that simulated an actual part, and performed a load test. For judgment, FEM analysis, non-destructive X-ray stress measurement, and measurement of the generated stress using strain gauge were applied. Compared with the FEM analysis results, the difference in the stress value was generated due to the difference in the contact state, but the trends of the stress distribution were equivalent. In addition, the same measurement value as the strain gauge was obtained, and the validity of the X-ray stress measurement method was confirmed. As a result, it was found that the stress measurement method by X-ray is effective for measuring the generated stress including the residual stress of the finger joint without gap at a bridge. (A.O.)

Generalized Unsafety Theory of Stress: Unsafe Environments and Conditions, and the Default Stress Response.

Science.gov (United States)

Brosschot, Jos F; Verkuil, Bart; Thayer, Julian F

2018-03-07

Prolonged physiological stress responses form an important risk factor for disease. According to neurobiological and evolution-theoretical insights the stress response is a default response that is always "on" but inhibited by the prefrontal cortex when safety is perceived. Based on these insights the Generalized Unsafety Theory of Stress (GUTS) states that prolonged stress responses are due to generalized and largely unconsciously perceived unsafety rather than stressors. This novel perspective necessitates a reconstruction of current stress theory, which we address in this paper. We discuss a variety of very common situations without stressors but with prolonged stress responses, that are not, or not likely to be caused by stressors, including loneliness, low social status, adult life after prenatal or early life adversity, lack of a natural environment, and less fit bodily states such as obesity or fatigue. We argue that in these situations the default stress response may be chronically disinhibited due to unconsciously perceived generalized unsafety. Also, in chronic stress situations such as work stress, the prolonged stress response may be mainly caused by perceived unsafety in stressor-free contexts. Thus, GUTS identifies and explains far more stress-related physiological activity that is responsible for disease and mortality than current stress theories.

Generalized Unsafety Theory of Stress: Unsafe Environments and Conditions, and the Default Stress Response

Directory of Open Access Journals (Sweden)

Jos F. Brosschot

2018-03-01

Full Text Available Prolonged physiological stress responses form an important risk factor for disease. According to neurobiological and evolution-theoretical insights the stress response is a default response that is always “on” but inhibited by the prefrontal cortex when safety is perceived. Based on these insights the Generalized Unsafety Theory of Stress (GUTS states that prolonged stress responses are due to generalized and largely unconsciously perceived unsafety rather than stressors. This novel perspective necessitates a reconstruction of current stress theory, which we address in this paper. We discuss a variety of very common situations without stressors but with prolonged stress responses, that are not, or not likely to be caused by stressors, including loneliness, low social status, adult life after prenatal or early life adversity, lack of a natural environment, and less fit bodily states such as obesity or fatigue. We argue that in these situations the default stress response may be chronically disinhibited due to unconsciously perceived generalized unsafety. Also, in chronic stress situations such as work stress, the prolonged stress response may be mainly caused by perceived unsafety in stressor-free contexts. Thus, GUTS identifies and explains far more stress-related physiological activity that is responsible for disease and mortality than current stress theories.

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

Modelling of the influence of the vacancy source and sink activity and the stress state on diffusion in crystalline solids

International Nuclear Information System (INIS)

Svoboda, J.; Fischer, F.D.

2011-01-01

Diffusion in solids is a well-known phenomenon that has many consequences in technology and material science. Modelling of diffusion-controlled processes requires both a reliable theory of diffusion and reliable kinetic coefficients, as well as other thermodynamic data. Often the classical Darken theory, valid for stress-free systems with ideal vacancy source and sink activity, is generalized to multicomponent systems with ideal vacancy source and sink activity. Nazarov and Gurov presented a theory for stress-free systems with no vacancy source and sink activity. Recently we published a general theory of diffusion that accounted for the role of non-ideal vacancy source and sink activity, as well as the stress state. Since diffusion theories are tested and diffusion coefficients measured usually on diffusion couples, this paper presents evolution equations based on that general theory for a diffusion couple. In the limit, the equations of the Darken theory and the Nazarov and Gurov theory are valid for ideal vacancy source and sink activity and no vacancy source and sink activity, respectively. Simulations for binary and ternary diffusion couples demonstrate the influence of the vacancy source and sink activity and the stress state on evolution of site fraction profiles of components and vacancies, and on the Kirkendall effect.

Measuring multiple residual-stress components using the contour method and multiple cuts

Energy Technology Data Exchange (ETDEWEB)

Prime, Michael B [Los Alamos National Laboratory; Swenson, Hunter [Los Alamos National Laboratory; Pagliaro, Pierluigi [U. PALERMO; Zuccarello, Bernardo [U. PALERMO

2009-01-01

The conventional contour method determines one component of stress over the cross section of a part. The part is cut into two, the contour of the exposed surface is measured, and Bueckner's superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The stress results are validated against independent measurements using neutron diffraction. The theory has implications beyond just multiple cuts. The contour method measurements and calculations for the first cut reveal how the residual stresses have changed throughout the part. Subsequent measurements of partially relaxed stresses by other techniques, such as laboratory x-rays, hole drilling, or neutron or synchrotron diffraction, can be superimposed back to the original state of the body.

Forecasting Financial Stress

OpenAIRE

Jan Willem Slingenberg; Jakob de Haan

2011-01-01

This paper uses a Financial Stress Index (FSI) for 13 OECD countries to examine which variables can help predicting financial stress. A stress index measures the current state of stress in the financial system and summarizes it in a single statistic. We employ three criteria for indicators to be used in constructing a multi-country FSI (the index covers the entire financial system, indicators used are available at a high frequency for many countries for a long period, and are comparable) to c...

Mathematical model of polyethylene pipe bending stress state

Science.gov (United States)

Serebrennikov, Anatoly; Serebrennikov, Daniil

2018-03-01