Sample records for stress based analysis

  1. Residual Stress Analysis Based on Acoustic and Optical Methods

    Sanichiro Yoshida


    Full Text Available Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.

  2. Ceramic design concepts based on stress distribution analysis.

    Esquivel-Upshaw, J F; Anusavice, K J


    This article discusses general design concepts involved in fabricating ceramic and metal-ceramic restorations based on scientific stress distribution data. These include the effects of ceramic layer thickness, modulus of elasticity of supporting substrates, direction of applied loads, intraoral stress, and crown geometry on the susceptibility of certain restoration designs to fracture.

  3. Mission-profile-based stress analysis of bond-wires in SiC power modules

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Blaabjerg, Frede


    This paper proposes a novel mission-profile-based reliability analysis approach for stress on bond wires in Silicon Carbide (SiC) MOSFET power modules using statistics and thermo-mechanical FEM analysis. In the proposed approach, both the operational and environmental thermal stresses are taken i...

  4. Machine learning-based differential network analysis: a study of stress-responsive transcriptomes in Arabidopsis.

    Ma, Chuang; Xin, Mingming; Feldmann, Kenneth A; Wang, Xiangfeng


    Machine learning (ML) is an intelligent data mining technique that builds a prediction model based on the learning of prior knowledge to recognize patterns in large-scale data sets. We present an ML-based methodology for transcriptome analysis via comparison of gene coexpression networks, implemented as an R package called machine learning-based differential network analysis (mlDNA) and apply this method to reanalyze a set of abiotic stress expression data in Arabidopsis thaliana. The mlDNA first used a ML-based filtering process to remove nonexpressed, constitutively expressed, or non-stress-responsive "noninformative" genes prior to network construction, through learning the patterns of 32 expression characteristics of known stress-related genes. The retained "informative" genes were subsequently analyzed by ML-based network comparison to predict candidate stress-related genes showing expression and network differences between control and stress networks, based on 33 network topological characteristics. Comparative evaluation of the network-centric and gene-centric analytic methods showed that mlDNA substantially outperformed traditional statistical testing-based differential expression analysis at identifying stress-related genes, with markedly improved prediction accuracy. To experimentally validate the mlDNA predictions, we selected 89 candidates out of the 1784 predicted salt stress-related genes with available SALK T-DNA mutagenesis lines for phenotypic screening and identified two previously unreported genes, mutants of which showed salt-sensitive phenotypes.

  5. Analysis of Load Stress for Asphalt Pavement of Lean Concrete Base

    Lijun, Suo; Xinwu, Wang

    The study revealed that whether it is early distresses in asphalt pavement or not depends largely on working performance of base. In the field of asphalt pavement, it is widely accepted that lean concrete base, compared with the general semi-rigid base, has better working performance, such as high strength and good eroding resistance. Problem of early distresses in asphalt pavement, which caused by more traffic loadings, can be settled effectively when lean concrete is used in asphalt pavement. Traffic loading is important parameter used in the analysis of the new pavement design. However, few studies have done extensive and intensive research on the load stress for asphalt pavement of lean concrete base. Because of that, it is necessary to study the load stress for the asphalt pavement. In the paper, first of all, three-dimension finite element model of the asphalt pavement is created for the aim of doing mechanical analysis for the asphalt pavement. And then, the two main objectives of this study are investigated. One is analysis for load stress of lean concrete base, and the other is analysis for load stress of asphalt surface. The results show that load stress of lean concrete base decreases, decrease and increase with increase of base's thickness, surface's thickness and ratio of base's modulus to foundation's modulus respectively. So far as the asphalt surface is concerned, maximum shearing stress, which is caused by load, is evident in asphalt surface which is located in transverse contraction joint of lean concrete base of asphalt pavement. Maximum shearing stress decrease, decrease, decrease and increase respectively with increase of the surface's modulus, the surface's thickness, base's thickness and ratio of base's modulus to foundation's modulus.

  6. Stress relaxation analysis of single chondrocytes using porohyperelastic model based on AFM experiments

    Trung Dung Nguyen


    Full Text Available Based on atomic force microscopytechnique, we found that the chondrocytes exhibits stress relaxation behavior. We explored the mechanism of this stress relaxation behavior and concluded that the intracellular fluid exuding out from the cells during deformation plays the most important role in the stress relaxation. We applied the inverse finite element analysis technique to determine necessary material parameters for porohyperelastic (PHE model to simulate stress relaxation behavior as this model is proven capable of capturing the non-linear behavior and the fluid-solid interaction during the stress relaxation of the single chondrocytes. It is observed that PHE model can precisely capture the stress relaxation behavior of single chondrocytes and would be a suitable model for cell biomechanics.

  7. Stress Analysis

    Burcharth, Hans F.

    The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)......The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)...

  8. Cluster-based analysis for personalized stress evaluation using physiological signals.

    Xu, Qianli; Nwe, Tin Lay; Guan, Cuntai


    Technology development in wearable sensors and biosignal processing has made it possible to detect human stress from the physiological features. However, the intersubject difference in stress responses presents a major challenge for reliable and accurate stress estimation. This research proposes a novel cluster-based analysis method to measure perceived stress using physiological signals, which accounts for the intersubject differences. The physiological data are collected when human subjects undergo a series of task-rest cycles, incurring varying levels of stress that is indicated by an index of the State Trait Anxiety Inventory. Next, a quantitative measurement of stress is developed by analyzing the physiological features in two steps: 1) a k -means clustering process to divide subjects into different categories (clusters), and 2) cluster-wise stress evaluation using the general regression neural network. Experimental results show a significant improvement in evaluation accuracy as compared to traditional methods without clustering. The proposed method is useful in developing intelligent, personalized products for human stress management.

  9. Stress echocardiography for the diagnosis of coronary artery disease: an evidence-based analysis.


    In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website).The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at:"> or at PHOTON EMISSION COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY WITH CONTRAST FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based Analysis64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis

  10. Frequency spectrum method-based stress analysis for oil pipelines in earthquake disaster areas.

    Xiaonan Wu

    Full Text Available When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure. To date, researchers have performed limited safety analyses of oil pipelines in earthquake disaster areas that include stress analysis. Therefore, using the spectrum method and theory of one-dimensional beam units, CAESAR II is used to perform a dynamic earthquake analysis for an oil pipeline in the XX earthquake disaster area. This software is used to determine if the displacement and stress of the pipeline meet the standards when subjected to a strong earthquake. After performing the numerical analysis, the primary seismic action axial, longitudinal and horizontal displacement directions and the critical section of the pipeline can be located. Feasible project enhancement suggestions based on the analysis results are proposed. The designer is able to utilize this stress analysis method to perform an ultimate design for an oil pipeline in earthquake disaster areas; therefore, improving the safe operation of the pipeline.

  11. Structural and stress analysis based on fault-slip data in the Amman area, Jordan

    Diabat, Abdullah A.


    This study presents a structural analysis based on hundreds of striated small faults (fault-slip data) in the Amman area east of the Dead Sea Transform System. Stress inversion of the fault-slip data was performed using an improved Right-Dihedral method, followed by rotational optimization (TENSOR Program, Delvaux, 1993). Fault-slip data (totaling 212) include fault planes, striations and sense of movements, are obtained from the Turonian Wadi As Sir Formation, distributed mainly along the southern side of the Amman - Hallabat structure in Jordan the study area. Results show that σ1 (SHmax) and σ3 (SHmin) are generally sub-horizontal and σ2 is sub-vertical in 8 of 11 paleostress tensors, which are belonging to a major strike-slip system with σ1 swinging around N to NW direction. The other three stress tensors show σ2 (SHmax), σ1 vertical and σ3 is NE oriented. This situation explained as permutation of stress axes σ1 and σ2 that occur during tectonic events and partitioned strike slip deformation. NW compressional stresses affected the area and produced the major Amman - Hallabat strike-slip fault and its related structures, e.g., NW trending normal faults and NE trending folds in the study area. The new paleostress results related with the active major stress field of the region the Dead Sea Stress Field (DSS) during the Miocene to Recent.

  12. iTRAQ-Based Quantitative Proteomic Analysis of Spirulina platensis in Response to Low Temperature Stress.

    Li, Qingye; Chang, Rong; Sun, Yijun; Li, Bosheng


    Low temperature (LT) is one of the most important abiotic stresses that can significantly reduce crop yield. To gain insight into how Spirulina responds to LT stress, comprehensive physiological and proteomic analyses were conducted in this study. Significant decreases in growth and pigment levels as well as excessive accumulation of compatible osmolytes were observed in response to LT stress. An isobaric tag for relative and absolute quantitation (iTRAQ)-based quantitative proteomics approach was used to identify changes in protein abundance in Spirulina under LT. A total of 3,782 proteins were identified, of which 1,062 showed differential expression. Bioinformatics analysis indicated that differentially expressed proteins that were enriched in photosynthesis, carbohydrate metabolism, amino acid biosynthesis, and translation are important for the maintenance of cellular homeostasis and metabolic balance in Spirulina when subjected to LT stress. The up-regulation of proteins involved in gluconeogenesis, starch and sucrose metabolism, and amino acid biosynthesis served as coping mechanisms of Spirulina in response to LT stress. Moreover, the down-regulated expression of proteins involved in glycolysis, TCA cycle, pentose phosphate pathway, photosynthesis, and translation were associated with reduced energy consumption. The findings of the present study allow a better understanding of the response of Spirulina to LT stress and may facilitate in the elucidation of mechanisms underlying LT tolerance.

  13. Stress Analysis of the Subsea Dynamic Riser BaseProcess Piping

    Xuanze Ju; Wei Fang; Hanjun Yin; Ying Jiang


    Thesubsea dynamic riser base(SDRB)is an important piece of equipment for the floating production platform mooring system.One end is connected to the rigid pipeline, carrying a rigid pipeline thermal expansion load and the other end is connected to a flexible riser, carrying the dynamic load of the flexible riser, so its function is a transition connection between the flexible riser and the rigid pipeline which fixes the flexible riser on the seabed. On the other hand , as a typical subsea product, the design will satisfythe requirements of the standards for subsea products. By studying the stress analysisphilosophy of the topside piping and subsea pipeline, a physical model and procedure for piping stress analysis of the SDRB have been established.The conditions of the adverse design load have been considered, and a combination of the static load from the rigid pipeline and the dynamic load flexibility has also been optimized. And a comparative analysis between the AMSE, DNV and API standards for piping stress with the checking rules has been done.Because theSDRB belongs to the subsea pipeline terminal product, the use of DNV standards to check its process piping stress is recommended. Finally, the process piping stress of the SDRB has been calculated, and the results show that the jacket pipe and the carrier pipe stress of the SDRB process piping satisfy the DNV standards as a whole.The bulkhead cannot be accurately simulated by the AutoPIPE software which uses the FEA software ANSYS inthe detailed analysis, but the checking results will still meet the requirements of the DNV standards.

  14. A novel PDMS micro membrane biosensor based on the analysis of surface stress.

    Sang, Shengbo; Witte, Hartmut


    The biological and medical application of biosensors is more and more important with the development of technology and society. Detection of cells and biological molecules utilizing biosensors based on the analysis of surface stress would facilitate inexpensive and high-throughput test and diagnosis. This paper presents a biocompatible surface stress-based polydimethylsiloxane (PDMS) micro membrane biosensor. Each biosensor chip consists of two available PDMS micro membranes, one acts as active membrane and the other as reference. Biosensors were functionalized using different functional materials respectively: MUA (11 Mercapto 1 undecanoicacid), MUO (11 Mercapto 1 undecanol) and DOT (Dodecane thiol). Two biosensor test systems were built based on a white light interferometer and a fiber optic interferometer respectively. Finally, testing experiments using Escherichia coli (E. coli) were performed based on the biosensor test systems we built. The results of the experiments showed that the MUA is a better functional material to functionalize the biosensor membranes than MUO and DOT for E. coli detection, some properties of E. coli, such as healthily living and dead status, can be analyzed based on the PDMS micro membrane biosensors.

  15. Numerical Parametric Analysis of Bond Coat Thickness Effect on Residual Stresses in Zirconia-Based Thermal Barrier Coatings

    Abbas, Musharaf; Hasham, Hasan Junaid; Baig, Yasir


    Numerical-based finite element investigation has been conducted to explain the effect of bond coat thickness on stress distribution in traditional and nanostructured yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBC). Stress components have been determined to quantitatively analyze the mechanical response of both kinds of coatings under the thermal shock effect. It has been found that maximum radial tensile and compressive stresses that exist at thermally grown oxide (TGO)/bond coat interface and within TGO respectively decrease with an increase in bond coat thickness. Effect of bond coat thickness on axial tensile stresses is not significant. However, axial compressive stresses that exist at the edge of the specimen near bond coat/substrate interface decrease appreciably with the increase in bond coat thickness. Residual stress profile as a function of bond coat thickness is further explained for comparative analysis of both coatings to draw some useful conclusions helpful in failure studies of TBCs.

  16. Mindfulness-based stress reduction and cancer: a meta-analysis.

    Ledesma, Dianne; Kumano, Hiroaki


    This meta-analysis was conducted to investigate the effects of mindfulness-based stress reduction (MBSR) on the mental and physical health status of various cancer patients. Ten studies (randomized-controlled trials and observational studies) were found to be eligible for meta-analysis. Individual study results were categorized into mental and physical variables and Cohen's effect size d was computed for each category. MBSR may indeed be helpful for the mental health of cancer patients (Cohen's effect size d=0.48); however, more research is needed to show convincing evidence of the effect on physical health (Cohen's effect size d=0.18). The results suggest that MBSR may improve cancer patients' psychosocial adjustment to their disease.

  17. Assessment of stress reactions of recruits based on quantitative analysis of the characteristics of fingertip photoplethysmographic

    Li-jun XIAO


    Full Text Available Objective To investigate the feasibility of stress assessment based on specific quantification techniques and analysis of stress status with photoplethysmographic(PPG signals.Methods The PPG signals were stratified and randomly sampled from 58 recruits before and after stress induced by International Affective Pictures Systems(IAPS images of negative emotion.The signals were collected and processed in a tool called HC2180-D,an enhanced solution of a blood flow monitoring system,through which the characteristic parameters of pulsatile waveform were derived as components of bioinformation for quantitative and comparative study.A concise mental rating scale,the "brief profile of mood state"(BPOMS,was used as criterion.Results As the characteristic parameter and biomarker were derived,significant increases in values were observed in both the vasoconstriction/vasodilation fraction(CDF and the ordinate of the area under the pulse contour of the vasoconstriction phase(Y2 when the recruits were shown IAPS images of negative emotion(P 0.05 were shown.The values of both the CDF and the Y2 were positively correlated in mid-range to tension,depression,and anger(P < 0.05,and in low-range to fatigue and confusion(P < 0.05.The values were negatively correlated in mid-range with vigor(P < 0.05.Conclusion The characteristic parameter and biomarker derived from the pulsatile waveform obtained at the fingertip are highly sensitive and can be utilized as measures in the quantitative assessment of stress response among recruits.

  18. On the failure analysis of bondlines: Stress or energy based fracture criteria?

    Anyfantis, Konstantinos


    that characterizes a given bondline, both its cohesive strength and fracture toughness material parameters must be experimentally defined. Based on these properties, failure analysis of the bondline can be done either through stress- or energy-based criteria. The aim of this work is to investigate the effectiveness...... of each criteria type to effectively predict debonding initiation/propagation of different bondlines (brittle, quasi-brittle, ductile), which are eventually utilized for the evaluation of the joint's failure load. By representing a bondline according to its cohesive length scale, an effort is made...... experimentation programme. Fracture initiation and propagation of the bondlines was numerically simulated by cohesive zone models. (C) 2014 Elsevier Ltd. All rights reserved....

  19. Basic stress analysis

    Iremonger, M J


    BASIC Stress Analysis aims to help students to become proficient at BASIC programming by actually using it in an important engineering subject. It also enables the student to use computing as a means of learning stress analysis because writing a program is analogous to teaching-it is necessary to understand the subject matter. The book begins by introducing the BASIC approach and the concept of stress analysis at first- and second-year undergraduate level. Subsequent chapters contain a summary of relevant theory, worked examples containing computer programs, and a set of problems. Topics c

  20. Brain structure in post-traumatic stress disorder A voxel-based morphometry analysis**

    Liwen Tan; Li Zhang; Rongfeng Qi; Guangming Lu; Lingjiang Li; Jun Liu; Weihui Li


    This study compared the difference in brain structure in 12 mine disaster survivors with chronic post-traumatic stress disorder, 7 cases of improved post-traumatic stress disorder symptoms, and 14 controls who experienced the same mine disaster but did not suffer post-traumatic stress disorder, us-ing the voxel-based morphometry method. The correlation between differences in brain structure and post-traumatic stress disorder symptoms was also investigated. Results showed that the gray matter volume was the highest in the trauma control group, fol owed by the symptoms-improved group, and the lowest in the chronic post-traumatic stress disorder group. Compared with the symptoms-improved group, the gray matter volume in the lingual gyrus of the right occipital lobe was reduced in the chronic post-traumatic stress disorder group. Compared with the trauma control group, the gray matter volume in the right middle occipital gyrus and left middle frontal gyrus was reduced in the symptoms-improved group. Compared with the trauma control group, the gray matter volume in the left superior parietal lobule and right superior frontal gyrus was reduced in the chronic post-traumatic stress disorder group. The gray matter volume in the left superior parietal lobule was significantly positively correlated with the State-Trait Anxiety Inventory subscale score in the symptoms-improved group and chronic post-traumatic stress disorder group (r = 0.477, P = 0.039). Our findings indicate that (1) chronic post-traumatic stress disorder patients have gray matter structural damage in the prefrontal lobe, occip-ital lobe, and parietal lobe, (2) after post-traumatic stress, the disorder symptoms are improved and gray matter structural damage is reduced, but cannot recover to the trauma-control level, and (3) the superior parietal lobule is possibly associated with chronic post-traumatic stress disorder. Post-traumatic stress disorder patients exhibit gray matter abnormalities.

  1. Brain structure in post-traumatic stress disorder: A voxel-based morphometry analysis.

    Tan, Liwen; Zhang, Li; Qi, Rongfeng; Lu, Guangming; Li, Lingjiang; Liu, Jun; Li, Weihui


    This study compared the difference in brain structure in 12 mine disaster survivors with chronic post-traumatic stress disorder, 7 cases of improved post-traumatic stress disorder symptoms, and 14 controls who experienced the same mine disaster but did not suffer post-traumatic stress disorder, using the voxel-based morphometry method. The correlation between differences in brain structure and post-traumatic stress disorder symptoms was also investigated. Results showed that the gray matter volume was the highest in the trauma control group, followed by the symptoms-improved group, and the lowest in the chronic post-traumatic stress disorder group. Compared with the symptoms-improved group, the gray matter volume in the lingual gyrus of the right occipital lobe was reduced in the chronic post-traumatic stress disorder group. Compared with the trauma control group, the gray matter volume in the right middle occipital gyrus and left middle frontal gyrus was reduced in the symptoms-improved group. Compared with the trauma control group, the gray matter volume in the left superior parietal lobule and right superior frontal gyrus was reduced in the chronic post-traumatic stress disorder group. The gray matter volume in the left superior parietal lobule was significantly positively correlated with the State-Trait Anxiety Inventory subscale score in the symptoms-improved group and chronic post-traumatic stress disorder group (r = 0.477, P = 0.039). Our findings indicate that (1) chronic post-traumatic stress disorder patients have gray matter structural damage in the prefrontal lobe, occipital lobe, and parietal lobe, (2) after post-traumatic stress, the disorder symptoms are improved and gray matter structural damage is reduced, but cannot recover to the trauma-control level, and (3) the superior parietal lobule is possibly associated with chronic post-traumatic stress disorder. Post-traumatic stress disorder patients exhibit gray matter abnormalities.

  2. Residual Stress Analysis of Ceramic Thermal Barrier Coating Based on Thermal Spray Process

    Arai, Masayuki; Wada, Eiji; Kishimoto, Kikuo

    Residual stress is generated in ceramic thermal barrier coatings (TBCs), which were sprayed by a plasma spray technology, due to the difference in coefficients of thermal expansion between the coating and the substrate. Previous experimental results obtained by the X-ray diffraction method indicated that the residual stress at the ceramic coating surface is tensile and could lead to TBC failure such as cracking and spalling of the ceramic coating. In this study, a numerical model that can predict the residual stress exactly is proposed by taking into account a thermal spray process. This numerical model is a layer-buildup model based on a shear-lag theory, and the residual stress contribution comes from two kinds of the following stress components: (1) quenching stress, which was generated in molten spray particles impinged onto the substrate, and (2) thermal stress, which was generated due to differences in thermal expansion between the deposited particle and the underlying substrate. It is shown herein that residual stress predicted by the proposed numerical model coincided with the experimental one obtained by the strain gage technique, with a good level of accuracy.


    He Wen; Ma Zhenyu; Wang Xingli


    The effect of vibratory stress relief (VSR) is usually evaluated with the indirect method of observing the change of amplitude frequency response characteristics of structures. A new kind of evaluating method of VSR based on the ultrasonic time-of-arrival method (UTM), which can obtain the residual stress directly through measuring the propagation time of ultrasonic wave in the material, is presented. At first, the principle of the measuring method of residual stress based on UTM is analyzed. Then the measuring system of the method is described, which is in virtue of ultrasonic flaw detector and high-sampling-rate digital oscillograph. And a set of calibration system that contains a piece of standard specimen is also introduced. Experimental results prove the relation between the residual stress and the propagation time of ultrasonic in workpieces. Finally, the measuring and calibration systems are applied in evaluating the effect of VSR. The final test results show that the method is effective.

  4. Internet-based interventions for posttraumatic stress: A meta-analysis of randomized controlled trials.

    Kuester, Annika; Niemeyer, Helen; Knaevelsrud, Christine


    Posttraumatic stress disorder (PTSD) is a prevalent and highly distressing affliction, but access to trauma-focused psychotherapy is limited. Internet-based interventions (IBIs) could improve the delivery of and access to specialized mental health care. Currently, no meta-analytical evidence is available on IBIs for PTSD. We conducted a meta-analysis of 20 randomized controlled studies, including 21 comparisons, in order to summarize the current state of efficacy for the treatment of PTSD and to identify moderator variables. Studies tested internet-based cognitive behavioral therapy (CBT) and expressive writing (EW) against active or passive comparison conditions, including subclinical and clinical samples. Results show that at post-assessment CBT-IBIs are significantly more efficacious than passive controls, resulting in medium to large effects on the PTSD sum and all sub-symptom scores (0.66CBT are not superior to active controls. EW differed from controls only at follow-up in reducing intrusions and hyperarousal, but based on merely two studies. Subgroup analyses reveal that for CBT none of the program components such as provision of therapeutic support, reminders, or number of sessions serves as a moderator. Overall, results for CBT-IBIs are promising, but the number of includable studies for subgroup analyses was low, limiting statistical power. Future research is necessary to systematically investigate the impact of treatment components and test against active controls with optimal power.

  5. [Stress analysis of artificial bionic knee joint based on UG6.0 NX NASTRAN].

    Shi, Gengqiang


    This article introduces the basic principles of finite element analysis in biomechanics, focusing on the basic principles of a variety of finite element analysis software, and their respective characteristics. In addition, it also de scribes the basic stress analysis of UGNX6.0 NASTRAN analysis for artificial knee process, i. e. the choice of the type, material definition, the set of constants, finite element mesh division and the finite element results of the analysis. Finite element analysis and evaluation of the design of personalized artificial knee were carried out, so that the rationality of the geometric design of the structure of the experimental design of artificial knee has been verified.

  6. Finite element based stress analysis of BWR internals exposed to accident loads

    Altstadt, E.; Weiss, F.P.; Werner, M.; Willschuetz, H.G.


    During a hypothetical accident the reactor pressure vessel internals of boiling water reactors can be exposed to considerable loads resulting from temperature gradients and pressure waves. Three dimensional FE models were developed for the core shroud, the upper and the lower core supporting structure, the steam separator pipes and the feed water distributor. The models of core shroud, upper core structure and lower core structure were coupled by means of the substructure technique. All FE models can be used for thermal and for structural mechanical analyses. As an example the FE analysis for the case of a station black-out scenario (loss of power supply for the main circulating pumps) with subsequent emergency core cooling is demonstrated. The transient temperature distributions within the core shroud and within the steam dryer pipes as well were calculated based on the fluid temperatures and the heat transfer coefficients provided by thermo-hydraulic codes. At the maximum temperature gradients in the core shroud, the mechanical stress distribution was computed in a static analysis with the actual temperature field being the load. (orig.)

  7. Automatic stress-relieving music recommendation system based on photoplethysmography-derived heart rate variability analysis.

    Shin, Il-Hyung; Cha, Jaepyeong; Cheon, Gyeong Woo; Lee, Choonghee; Lee, Seung Yup; Yoon, Hyung-Jin; Kim, Hee Chan


    This paper presents an automatic stress-relieving music recommendation system (ASMRS) for individual music listeners. The ASMRS uses a portable, wireless photoplethysmography module with a finger-type sensor, and a program that translates heartbeat signals from the sensor to the stress index. The sympathovagal balance index (SVI) was calculated from heart rate variability to assess the user's stress levels while listening to music. Twenty-two healthy volunteers participated in the experiment. The results have shown that the participants' SVI values are highly correlated with their prespecified music preferences. The sensitivity and specificity of the favorable music classification also improved as the number of music repetitions increased to 20 times. Based on the SVI values, the system automatically recommends favorable music lists to relieve stress for individuals.

  8. Estimation of the stress related to conservative scoliosis therapy: an analysis based on BSSQ questionnaires

    Szulc Andrzej


    Full Text Available Abstract Background Adolescent girls treated with a brace for scoliosis are submitted to prolonged stress related to both the disease and the therapy. Currently proposed quality of life questionnaires are focused on the outcome of therapy. Bad Sobernheim Stress Questionnaire (BSSQ enables monitoring of patients being under treatment with a brace or exercises. The aim of the study was to assess the stress level in conservatively managed scoliotic girls using BSSQ. Materials and methods 111 girls, aged 14,2 ± 2,2 years, mean Cobb angle of the primary curve 42,8° ± 17,0° and mean Bunnell angle of 11,4° ± 4,5° were examined with two versions of BSSQ (Deformity and Brace. The analysis considered the type of treatment, curve location, correlation of the total score with age, Cobb angle and Bunnell rotation angle. Results The BSSQ Deformity revealed the median of 17 points in patients managed with exercises (from 4 to 24 points, 18 in patients managed with a brace (from 8 to 24 points and 12 in patients before surgery (from 3 to 21 points. Braced patients who completed both questionnaires (n = 50 revealed significantly higher score with BSSQ Deformity (median = 18 comparing to BSSQ Brace (median = 9. There was a correlation between the total score of BSSQ Deformity and the Cobb angle (r = -0,34, Bunnell primary curve rotation (r = -0,34 and Bunnell sum of rotation (r = -0,33 but not with the age of patients. Conclusion Scoliotic adolescents managed with exercises and brace suffered little stress from the deformity. The brace increased the level of stress over the stress induced by the deformity. The stress level correlated with clinical deformity (Bunnell angle, radiological deformity (Cobb angle and the type of treatment (exercises, bracing, surgery. Bad Sobernheim Stress Questionnaires are simple and helpful in the management of girls treated conservatively for idiopathic scoliosis.

  9. Identification of target genes conferring ethanol stress tolerance to Saccharomyces cerevisiae based on DNA microarray data analysis.

    Hirasawa, Takashi; Yoshikawa, Katsunori; Nakakura, Yuki; Nagahisa, Keisuke; Furusawa, Chikara; Katakura, Yoshio; Shimizu, Hiroshi; Shioya, Suteaki


    During industrial production process using yeast, cells are exposed to the stress due to the accumulation of ethanol, which affects the cell growth activity and productivity of target products, thus, the ethanol stress-tolerant yeast strains are highly desired. To identify the target gene(s) for constructing ethanol stress tolerant yeast strains, we obtained the gene expression profiles of two strains of Saccharomyces cerevisiae, namely, a laboratory strain and a strain used for brewing Japanese rice wine (sake), in the presence of 5% (v/v) ethanol, using DNA microarray. For the selection of target genes for breeding ethanol stress tolerant strains, clustering of DNA microarray data was performed. For further selection, the ethanol sensitivity of the knockout mutants in each of which the gene selected by DNA microarray analysis is deleted, was also investigated. The integration of the DNA microarray data and the ethanol sensitivity data of knockout strains suggests that the enhancement of expression of genes related to tryptophan biosynthesis might confer the ethanol stress tolerance to yeast cells. Indeed, the strains overexpressing tryptophan biosynthesis genes showed a stress tolerance to 5% ethanol. Moreover, the addition of tryptophan to the culture medium and overexpression of tryptophan permease gene conferred ethanol stress tolerance to yeast cells. These results indicate that overexpression of the genes for trypophan biosynthesis increases the ethanol stress tolerance. Tryptophan supplementation to culture and overexpression of the tryptophan permease gene are also effective for the increase in ethanol stress tolerance. Our methodology for the selection of target genes for constructing ethanol stress tolerant strains, based on the data of DNA microarray analysis and phenotypes of knockout mutants, was validated.

  10. Analysis of faults stability with dynamic phenomena in the mine based on slide criterion and in-situ stress measurement

    SONG Wei-hua; WANG Yu-feng; WANG Xin-hua


    For the study on the relationship between the dynamic phenomena in the mining such as mine earthquakes,outburst and faults slide,firstly,double shear friction experiments of sandstone were made,and its slide criterion was suggested considering the viewing of engineering.Secondly,in order to study the stability of underground rock and zone of tectonic stress field,based on the analysis on distribution characteristic of initial rock stress measurements,the geology structural model was built and tectonic stress field was made a back-analysis by applying finite element method.The calculating results fit with the analysis result of earthquakes mechanism and the distribution characteristic of the measurements.The high stress regional centers station locates discontinuous zone of I level faults and is corresponding to underground earthquakes scene.From then it is certain that tectonic stress is the major origin and necessary condition of mine earthquakes.The instability slide of the faults is the main manifest and the mining activity is the leading factor.Beipiao fault has a dominate effect on other sub faults and tectonic stress area and is dynamical fountain of dynamic phenomena in the Beipiao Mines.

  11. Analysis of faults stability with dynamic phenomena in the mine based on slide criterion and in-situ stress measurement

    SONG Wei-hua; WANG Yu-feng; WANG Xin-hua


    For the study on the relationshfp between the dynamic phenomena in the min-ing such as mine earthquakes, outburst and faults slide, firstly, double shear friction ex-periments of sandstone were made, and its slide criterion was suggested considering the viewing of engineering. Secondly, in order to study the stability of underground rock and zone of tectonic stress field, based on the analysis on distribution characteristic of initial rock stress measurements, the geology structural model was built and tectonic stress field was made a back-analysis by applying finite element method. The calculating results fit with the analysis result of earthquakes mechanism and the distribution characteristic of the measurements. The high stress regional centers station locates discontinuous zone of I level faults and is corresponding to underground earthquakes scene. From then it is cer-tain that tectonic stress is the major origin and necessary condition of mine earthquakes. The instability slide of the faults is the main manifest and the mining activity is the leading factor. Beipiao fault has a dominate effect on other sub faults and tectonic stress area and is dynamical fountain of dynamic phenomena in the Beipiao Mines.

  12. Practical stress analysis in engineering design

    Huston, Ronald


    Presents the application of engineering design and analysis based on the approach of understanding the physical characteristics of a given problem and then modeling the important aspects of the physical system. This book covers such topics as contact stress analysis, singularity functions, gear stresses, fasteners, shafts, and shaft stresses.

  13. Stress and psychological factors before a migraine attack: A time-based analysis

    Makino Mariko


    Full Text Available Abstract Background The objective of this study is to examine the stress and mood changes of Japanese subjects over the 1–3 days before a migraine headache. Methods The study participants were 16 patients with migraines who consented to participate in this study. Each subject kept a headache diary four times a day for two weeks. They evaluated the number of stressful events, daily hassles, domestic and non-domestic stress, anxiety, depressive tendency and irritability by visual analog scales. The days were classified into migraine days, pre-migraine days, buffer days and control days based on the intensity of the headaches and accompanying symptoms, and a comparative study was conducted for each factor on the migraine days, pre-migraine days and control days. Results The stressful event value of pre-migraine days showed no significant difference compared to other days. The daily hassle value of pre-migraine days was the highest and was significantly higher than that of buffer days. In non-domestic stress, values on migraine days were significantly higher than on other days, and there was no significant difference between pre-migraine days and buffer days or between pre-migraine days and control days. There was no significant difference in the values of domestic stress between the categories. In non-domestic stress, values on migraine days were significantly higher than other days, and there was no significant difference between pre-migraine days and buffer days or between pre-migraine days and control days. There was little difference in sleep quality on migraine and pre-migraine days, but other psychological factors were higher on migraine days than on pre-migraine days. Conclusion Psychosocial stress preceding the onset of migraines by several days was suggested to play an important role in the occurrence of migraines. However, stress 2–3 days before a migraine attack was not so high as it has been reported to be in the United States and

  14. Using Co-Expression Analysis and Stress-Based Screens to Uncover Arabidopsis Peroxisomal Proteins Involved in Drought Response.

    Jiying Li

    Full Text Available Peroxisomes are essential organelles that house a wide array of metabolic reactions important for plant growth and development. However, our knowledge regarding the role of peroxisomal proteins in various biological processes, including plant stress response, is still incomplete. Recent proteomic studies of plant peroxisomes significantly increased the number of known peroxisomal proteins and greatly facilitated the study of peroxisomes at the systems level. The objectives of this study were to determine whether genes that encode peroxisomal proteins with related functions are co-expressed in Arabidopsis and identify peroxisomal proteins involved in stress response using in silico analysis and mutant screens. Using microarray data from online databases, we performed hierarchical clustering analysis to generate a comprehensive view of transcript level changes for Arabidopsis peroxisomal genes during development and under abiotic and biotic stress conditions. Many genes involved in the same metabolic pathways exhibited co-expression, some genes known to be involved in stress response are regulated by the corresponding stress conditions, and function of some peroxisomal proteins could be predicted based on their co-expression pattern. Since drought caused expression changes to the highest number of genes that encode peroxisomal proteins, we subjected a subset of Arabidopsis peroxisomal mutants to a drought stress assay. Mutants of the LON2 protease and the photorespiratory enzyme hydroxypyruvate reductase 1 (HPR1 showed enhanced susceptibility to drought, suggesting the involvement of peroxisomal quality control and photorespiration in drought resistance. Our study provided a global view of how genes that encode peroxisomal proteins respond to developmental and environmental cues and began to reveal additional peroxisomal proteins involved in stress response, thus opening up new avenues to investigate the role of peroxisomes in plant adaptation to

  15. Dynamic Reliability Analysis Method of Degraded Mechanical Components Based on Process Probability Density Function of Stress

    Peng Gao


    Full Text Available It is necessary to develop dynamic reliability models when considering strength degradation of mechanical components. Instant probability density function (IPDF of stress and process probability density function (PPDF of stress, which are obtained via different statistical methods, are defined, respectively. In practical engineering, the probability density function (PDF for the usage of mechanical components is mostly PPDF, such as the PDF acquired via the rain flow counting method. For the convenience of application, IPDF is always approximated by PPDF when using the existing dynamic reliability models. However, it may cause errors in the reliability calculation due to the approximation of IPDF by PPDF. Therefore, dynamic reliability models directly based on PPDF of stress are developed in this paper. Furthermore, the proposed models can be used for reliability assessment in the case of small amount of stress process samples by employing the fuzzy set theory. In addition, the mechanical components in solar array of satellites are chosen as representative examples to illustrate the proposed models. The results show that errors are caused because of the approximation of IPDF by PPDF and the proposed models are accurate in the reliability computation.

  16. Accurate stress analysis on rigid central buckle of Ions-span suspension bridges based on submodel method

    WANG Hao; LI AiQun; GUO Tong; MA Shuang


    Runyang Suspension Bridge (RSB) with the main span of 1490 m is the longest bridge in China and the third longest one in the world. In this bridge the rigid central buckle is employed for the first time in the mid-span of the suspension bridge in China. For such a super-long-span bridge, the traditional finite element (FE) modeling technique and stress analysis methods obviously cannot satisfy the needs of conducting accurate stress analysis on the central buckle. In this paper, the submodel method is introduced and for the first time used in analyzing the stresses of the central buckle. After an accurate FE submodel of the central buckle was specially established according to the analysis results from the whole FE model, the connection technique between the two-scale FE models was realized and the accurate stresses of the central buckle under various vehicle load cases were then conducted based on the submodel method. The calculation results were testified to be accurate and reliable by the field measurements, which show the efficiency and reliability of the submodel method on analyzing the mechanical condition of the central buckle of long-span suspension bridges. Finally, the working behavior and mechanical characteristics of the central buckle of the RSB under vehicle loads were analyzed based on the calculation and measurement results. The results obtained in this paper can provide theoretic references for analyzing and designing the rigid central buckle in long-span suspension bridges in future.

  17. Accurate stress analysis on rigid central buckle of long-span suspension bridges based on submodel method


    Runyang Suspension Bridge (RSB) with the main span of 1490 m is the longest bridge in China and the third longest one in the world. In this bridge the rigid central buckle is employed for the first time in the mid-span of the suspension bridge in China. For such a super-long-span bridge, the traditional finite element (FE) modeling technique and stress analysis methods obviously cannot satisfy the needs of conducting accurate stress analysis on the central buckle. In this paper, the submodel method is in- troduced and for the first time used in analyzing the stresses of the central buckle. After an accurate FE submodel of the central buckle was specially established according to the analysis results from the whole FE model, the connection technique between the two-scale FE models was realized and the ac- curate stresses of the central buckle under various vehicle load cases were then conducted based on the submodel method. The calculation results were testified to be accurate and reliable by the field measurements, which show the efficiency and reliability of the submodel method on analyzing the mechanical condition of the central buckle of long-span suspension bridges. Finally, the working be- havior and mechanical characteristics of the central buckle of the RSB under vehicle loads were ana- lyzed based on the calculation and measurement results. The results obtained in this paper can provide theoretic references for analyzing and designing the rigid central buckle in long-span suspension bridges in future.

  18. Reliability analysis of diesel engine crankshaft based on 2D stress strength interference model


    A 2D stress strength interference model (2D-SSIM) considering that the fatigue reliability of engineering structural components has close relationship to load asymmetric ratio and its variability to some extent is put forward. The principle, geometric schematic and limit state equation of this model are presented. Reliability evaluation for a kind of diesel engine crankshaft was made based on this theory, in which multi-axial loading fatigue criteria was employed. Because more important factors, i.e.stress asymmetric ratio and its variability, are considered, it theoretically can make more accurate evaluation for structural component reliability than the traditional interference model. Correspondingly, a Monte-Carlo Method simulation solution is also given. The computation suggests that this model can yield satisfactory reliability evaluation.

  19. Carbon fiber based composites stress analysis. Experimental and computer comparative studies

    Sobek, M.; Baier, A.; Buchacz, A.; Grabowski, Ł.; Majzner, M.


    Composite materials used nowadays for the production of composites are the result of advanced research. This allows assuming that they are among the most elaborate tech products of our century. That fact is evidenced by the widespread use of them in the most demanding industries like aerospace and space industry. But the heterogeneous materials and their advantages have been known to mankind in ancient times and they have been used by nature for millions of years. Among the fibers used in the industry most commonly used are nylon, polyester, polypropylene, boron, metal, glass, carbon and aramid. Thanks to their physical properties last three fiber types deserve special attention. High strength to weight ratio allow the use of many industrial solutions. Composites based on carbon and glass fibers are widely used in the automotive. Aramid fibers ideal for the fashion industry where the fabric made from the fibers used to produce the protective clothing. In the paper presented issues of stress analysis of composite materials have been presented. The components of composite materials and principles of composition have been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. For this purpose plain carbon textile was used with a weight of 200 g/mm2 and epoxy resin LG730. During laboratory strain tests described in the paper Tenmex's delta type strain gauge rosettes were used. They were arranged in specific locations on the surface of the samples. Data acquisition preceded using HBM measurement equipment, which included measuring amplifier and measuring head. Data acquisition was performed using the Easy Catman. In order to verify the results of laboratory tests numerical studies were carried out in a

  20. Study of stress variations in single-stance and sideways fall using image-based finite element analysis.

    Faisal, Tanvir R; Luo, Yunhua


    Image-based finite element analysis (FEA) has been considered an effective computational tool to predict hip fracture risk. The patient specific FEA gives an insight into the inclusive effect of three-dimensional (3D) complex bone geometry, and the distribution of inhomogeneous isotropic material properties in conjunction with loading conditions. The neck region of a femur is primarily the weakest in which fracture is likely to happen, when someone falls. A sideways fall results in the development of greater tensile and compressive stresses, respectively, in the inferior and superior aspects of the femoral neck, whereas the state of stress is reversed in usual gait or stance configuration. Herein, the variations of stresses have been investigated at the femoral neck region considering both single-stance and sideways fall. Finite element models of ten human femora have been generated using Quantitative Computed Tomography (QCT) scan datasets and have been simulated with an equal magnitude of load applied to the aforementioned configurations. Fracture risk indicator, defined as the ratio of the maximum compressive or tensile stress computed at the superior and inferior surfaces to the corresponding yield stress, has been used in this work to measure the variations of fracture risk between single-stance and sideways fall. The average variations of the fracture risk indicators between the fall and stance are at least 24.3% and 8% at the superior and inferior surfaces, respectively. The differences may interpret why sideways fall is more dangerous for the elderly people, causing hip fracture.

  1. A Cycling Movement Based System for Real-Time Muscle Fatigue and Cardiac Stress Monitoring and Analysis.

    Chen, Szi-Wen; Liaw, Jiunn-Woei; Chang, Ya-Ju; Chan, Hsiao-Lung; Chiu, Li-Yu


    In this study, we defined a new parameter, referred to as the cardiac stress index (CSI), using a nonlinear detrended fluctuation analysis (DFA) of heart rate (HR). Our study aimed to incorporate the CSI into a cycling based fatigue monitoring system developed in our previous work so the muscle fatigue and cardiac stress can be both continuously and quantitatively assessed for subjects undergoing the cycling exercise. By collecting electrocardiogram (ECG) signals, the DFA scaling exponent α was evaluated on the RR time series extracted from a windowed ECG segment. We then obtained the running estimate of α by shifting a one-minute window by a step of 20 seconds so the CSI, defined as the percentage of all the less-than-one α values, can be synchronously updated every 20 seconds. Since the rating of perceived exertion (RPE) scale is considered as a convenient index which is commonly used to monitor subjective perceived exercise intensity, we then related the Borg RPE scale value to the CSI in order to investigate and quantitatively characterize the relationship between exercise-induced fatigue and cardiac stress. Twenty-two young healthy participants were recruited in our study. Each participant was asked to maintain a fixed pedaling speed at a constant load during the cycling exercise. Experimental results showed that a decrease in DFA scaling exponent α or an increase in CSI was observed during the exercise. In addition, the Borg RPE scale and CSI were positively correlated, suggesting that the factors due to cardiac stress might also contribute to fatigue state during physical exercise. Since the CSI can effectively quantify the cardiac stress status during physical exercise, our system may be used in sports medicine, or used by cardiologists who carried out stress tests for monitoring heart condition in patients with heart diseases.

  2. DeepSAGE based differential gene expression analysis under cold and freeze stress in seabuckthorn (Hippophae rhamnoides L..

    Saurabh Chaudhary

    Full Text Available Seabuckthorn (Hippophae rhamnoides L., an important plant species of Indian Himalayas, is well known for its immense medicinal and nutritional value. The plant has the ability to sustain growth in harsh environments of extreme temperatures, drought and salinity. We employed DeepSAGE, a tag based approach, to identify differentially expressed genes under cold and freeze stress in seabuckthorn. In total 36.2 million raw tags including 13.9 million distinct tags were generated using Illumina sequencing platform for three leaf tissue libraries including control (CON, cold stress (CS and freeze stress (FS. After discarding low quality tags, 35.5 million clean tags including 7 million distinct clean tags were obtained. In all, 11922 differentially expressed genes (DEGs including 6539 up regulated and 5383 down regulated genes were identified in three comparative setups i.e. CON vs CS, CON vs FS and CS vs FS. Gene ontology and KEGG pathway analysis were performed to assign gene ontology term to DEGs and ascertain their biological functions. DEGs were mapped back to our existing seabuckthorn transcriptome assembly comprising of 88,297 putative unigenes leading to the identification of 428 cold and freeze stress responsive genes. Expression of randomly selected 22 DEGs was validated using qRT-PCR that further supported our DeepSAGE results. The present study provided a comprehensive view of global gene expression profile of seabuckthorn under cold and freeze stresses. The DeepSAGE data could also serve as a valuable resource for further functional genomics studies aiming selection of candidate genes for development of abiotic stress tolerant transgenic plants.

  3. A Cycling Movement Based System for Real-Time Muscle Fatigue and Cardiac Stress Monitoring and Analysis.

    Szi-Wen Chen

    Full Text Available In this study, we defined a new parameter, referred to as the cardiac stress index (CSI, using a nonlinear detrended fluctuation analysis (DFA of heart rate (HR. Our study aimed to incorporate the CSI into a cycling based fatigue monitoring system developed in our previous work so the muscle fatigue and cardiac stress can be both continuously and quantitatively assessed for subjects undergoing the cycling exercise. By collecting electrocardiogram (ECG signals, the DFA scaling exponent α was evaluated on the RR time series extracted from a windowed ECG segment. We then obtained the running estimate of α by shifting a one-minute window by a step of 20 seconds so the CSI, defined as the percentage of all the less-than-one α values, can be synchronously updated every 20 seconds. Since the rating of perceived exertion (RPE scale is considered as a convenient index which is commonly used to monitor subjective perceived exercise intensity, we then related the Borg RPE scale value to the CSI in order to investigate and quantitatively characterize the relationship between exercise-induced fatigue and cardiac stress. Twenty-two young healthy participants were recruited in our study. Each participant was asked to maintain a fixed pedaling speed at a constant load during the cycling exercise. Experimental results showed that a decrease in DFA scaling exponent α or an increase in CSI was observed during the exercise. In addition, the Borg RPE scale and CSI were positively correlated, suggesting that the factors due to cardiac stress might also contribute to fatigue state during physical exercise. Since the CSI can effectively quantify the cardiac stress status during physical exercise, our system may be used in sports medicine, or used by cardiologists who carried out stress tests for monitoring heart condition in patients with heart diseases.

  4. Quantifying Residual Stresses by Means of Thermoelastic Stress Analysis

    Gyekenyesi, Andrew L.; Baaklini, George Y.


    This study focused on the application of the Thermoelastic Stress Analysis (TSA) technique as a tool for assessing the residual stress state of structures. TSA is based on the fact that materials experience small temperature changes when compressed or expanded. When a structure is cyclically loaded, a surface temperature profile results which correlates to the surface stresses. The cyclic surface temperature is measured with an infrared camera. Traditionally, the amplitude of a TSA signal was theoretically defined to be linearly dependent on the cyclic stress amplitude. Recent studies have established that the temperature response is also dependent on the cyclic mean stress (i.e., the static stress state of the structure). In a previous study by the authors, it was shown that mean stresses significantly influenced the TSA results for titanium- and nickel-based alloys. This study continued the effort of accurate direct measurements of the mean stress effect by implementing various experimental modifications. In addition, a more in-depth analysis was conducted which involved analyzing the second harmonic of the temperature response. By obtaining the amplitudes of the first and second harmonics, the stress amplitude and the mean stress at a given point on a structure subjected to a cyclic load can be simultaneously obtained. The experimental results showed good agreement with the theoretical predictions for both the first and second harmonics of the temperature response. As a result, confidence was achieved concerning the ability to simultaneously obtain values for the static stress state as well as the cyclic stress amplitude of structures subjected to cyclic loads using the TSA technique. With continued research, it is now feasible to establish a protocol that would enable the monitoring of residual stresses in structures utilizing TSA.

  5. Sensitivity analysis of rectangular atomic force microscope cantilevers immersed in liquids based on the modified couple stress theory.

    Lee, Haw-Long; Chang, Win-Jin


    The modified couple stress theory is adopted to study the sensitivity of a rectangular atomic force microscope (AFM) cantilever immersed in acetone, water, carbon tetrachloride (CCl4), and 1-butanol. The theory contains a material length scale parameter and considers the size effect in the analysis. However, this parameter is difficult to obtain via experimental measurements. In this study, a conjugate gradient method for the parameter estimation of the frequency equation is presented. The optimal method provides a quantitative approach for estimating the material length scale parameter based on the modified couple stress theory. The results show that the material length scale parameter of the AFM cantilever immersed in acetone, CCl4, water, and 1-butanol is 0, 25, 116.3, and 471 nm, respectively. In addition, the vibration sensitivities of the AFM cantilever immersed in these liquids are investigated. The results are useful for the design of AFM cantilevers immersed in liquids.

  6. Analysis of domain wall dynamics based on skewness of magnetic Barkhausen noise for applied stress determination

    Ding, Song; Tian, GuiYun; Dobmann, Gerd; Wang, Ping


    Skewness of Magnetic Barkhausen Noise (MBN) signal is used as a new feature for applied stress determination. After experimental studies, skewness presents its ability for measuring applied tensile stress compared with conventional feature, meanwhile, a non-linear behavior of this new feature and an independence of the excitation conditions under compressive stress are found and discussed. Effective damping during domain wall motion influencing the asymmetric shape of the MBN statistical distribution function is discussed under compressive and tensile stress variation. Domain wall (DW) energy and distance between pinning edges of the DW are considered altering the characteristic relaxation time, which is the reason for the non-linear phenomenon of skewness.

  7. Stress wave analysis: applied to rotating machines; Stress wave analysis: aplicado a maquinas rotativas

    Souza, Paulo Garcia de [Invensys Brasil Ltda., Sao Paulo, SP (Brazil)


    Stress wave analysis is the technology of data analysis (stress profile - ultrasound spectrum) collected by high-frequency acoustic sensors. Monitoring and analysis of rotating equipment, is a crucial element in predictive maintenance and condition based maintenance projects and, in a broader context, of performance management and optimization of assets. This article discusses the application of stress wave analysis to rotating machines in the context of assets optimization and CBM. (author)

  8. Physics-based analysis of the hydrodynamic stress in a fluid-particle system

    Zhang, Quan; Prosperetti, Andrea


    The paper begins by showing how standard results on the average hydrodynamic stress in a uniform fluid-particle system follow from a direct, elementary application of Cauchy’s stress principle. The same principle applied to the angular momentum balance proves the emergence, at the mesoscale, of an a

  9. Frequency spectrum method-based stress analysis for oil pipelines in earthquake disaster areas

    Wu, Xiaonan; Lu, Hongfang; Huang, Kun; Wu, Shijuan; Qiao, Weibiao


    When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure...

  10. Frequency Spectrum Method-Based Stress Analysis for Oil Pipelines in Earthquake Disaster Areas: e0115299

    Xiaonan Wu; Hongfang Lu; Kun Huang; Shijuan Wu; Weibiao Qiao


      When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure...

  11. Dynamic Stresses in a Francis Turbine Runner Based on Fluid-Structure Interaction Analysis

    XIAO Ruofu; WANG Zhengwei; LUO Yongyao


    Fatigue and cracks have occurred in many large hydraulic turbines after they were put into production.The cracks are thought to be due to dynamic stresses in the runner caused by hydraulic forces.Computational fluid dynamics(CFD)simulations that included the spiral case,stay vane,guide vane,runner vane.and draft tube were run at various operating points to analyze the pressure distribution on the runner surface and the stress characteristics in the runner due to the fluid-structure interactions(FSl).The dynamic stresses in the Francis turbine runner at the most dangerous operating point were then analyzed.The results show that the dynamic stresses caused by the hydraulic forces during off-design operating points are one of the main reasons for the fatigue and cracks in the runner blade.The results can be used to optimize the runner and to analyze other critical components in the hydraulic turbine.

  12. Reliability prediction of large fuel cell stack based on structure stress analysis

    Liu, L. F.; Liu, B.; Wu, C. W.


    The aim of this paper is to improve the reliability of Proton Electrolyte Membrane Fuel Cell (PEMFC) stack by designing the clamping force and the thickness difference between the membrane electrode assembly (MEA) and the gasket. The stack reliability is directly determined by the component reliability, which is affected by the material property and contact stress. The component contact stress is a random variable because it is usually affected by many uncertain factors in the production and clamping process. We have investigated the influences of parameter variation coefficient on the probability distribution of contact stress using the equivalent stiffness model and the first-order second moment method. The optimal contact stress to make the component stay in the highest level reliability is obtained by the stress-strength interference model. To obtain the optimal contact stress between the contact components, the optimal thickness of the component and the stack clamping force are optimally designed. Finally, a detailed description is given how to design the MEA and gasket dimensions to obtain the highest stack reliability. This work can provide a valuable guidance in the design of stack structure for a high reliability of fuel cell stack.

  13. Free vibration analysis of embedded magneto-electro-thermo-elastic cylindrical nanoshell based on the modified couple stress theory

    Ghadiri, Majid; Safarpour, Hamed


    In this paper, size-dependent effect of an embedded magneto-electro-elastic (MEE) nanoshell subjected to thermo-electro-magnetic loadings on free vibration behavior is investigated. Also, the surrounding elastic medium has been considered as the model of Winkler characterized by the spring. The size-dependent MEE nanoshell is investigated on the basis of the modified couple stress theory. Taking attention to the first-order shear deformation theory (FSDT), the modeled nanoshell and its equations of motion are derived using principle of minimum potential energy. The accuracy of the presented model is validated with some cases in the literature. Finally, using the Navier-type method, an analytical solution of governing equations for vibration behavior of simply supported MEE cylindrical nanoshell under combined loadings is presented and the effects of material length scale parameter, temperature changes, external electric potential, external magnetic potential, circumferential wave numbers, constant of spring, shear correction factor and length-to-radius ratio of the nanoshell on natural frequency are identified. Since there has been no research about size-dependent analysis MEE cylindrical nanoshell under combined loadings based on FSDT, numerical results are presented to be served as benchmarks for future analysis of MEE nanoshells using the modified couple stress theory.

  14. Voice stress analysis

    Brenner, Malcolm; Shipp, Thomas


    In a study of the validity of eight candidate voice measures (fundamental frequency, amplitude, speech rate, frequency jitter, amplitude shimmer, Psychological Stress Evaluator scores, energy distribution, and the derived measure of the above measures) for determining psychological stress, 17 males age 21 to 35 were subjected to a tracking task on a microcomputer CRT while parameters of vocal production as well as heart rate were measured. Findings confirm those of earlier studies that increases in fundamental frequency, amplitude, and speech rate are found in speakers involved in extreme levels of stress. In addition, it was found that the same changes appear to occur in a regular fashion within a more subtle level of stress that may be characteristic, for example, of routine flying situations. None of the individual speech measures performed as robustly as did heart rate.

  15. Thermal Stresses Analysis and Optimized TTP Processes to Achieved CNT-Based Diaphragm for Thin Panel Speakers

    Feng-Min Lai


    Full Text Available Industrial companies popularly used the powder coating, classing, and thermal transfer printing (TTP technique to avoid oxidation on the metallic surface and stiffened speaker diaphragm. This study developed a TTP technique to fabricate a carbon nanotubes (CNTs stiffened speaker diaphragm for thin panel speaker. The self-developed TTP stiffening technique did not require a high curing temperature that decreased the mechanical property of CNTs. In addition to increasing the stiffness of diaphragm substrate, this technique alleviated the middle and high frequency attenuation associated with the smoothing sound pressure curve of thin panel speaker. The advantage of TTP technique is less harmful to the ecology, but it causes thermal residual stresses and some unstable connections between printed plates. Thus, this study used the numerical analysis software (ANSYS to analyze the stress and thermal of work piece which have not delaminated problems in transfer interface. The Taguchi quality engineering method was applied to identify the optimal manufacturing parameters. Finally, the optimal manufacturing parameters were employed to fabricate a CNT-based diaphragm, which was then assembled onto a speaker. The result indicated that the CNT-based diaphragm improved the sound pressure curve smoothness of the speaker, which produced a minimum high frequency dip difference (ΔdB value.

  16. Advanced Techniques of Stress Analysis

    Simion TATARU


    Full Text Available This article aims to check the stress analysis technique based on 3D models also making a comparison with the traditional technique which utilizes a model built directly into the stress analysis program. This comparison of the two methods will be made with reference to the rear fuselage of IAR-99 aircraft, structure with a high degree of complexity which allows a meaningful evaluation of both approaches. Three updated databases are envisaged: the database having the idealized model obtained using ANSYS and working directly on documentation, without automatic generation of nodes and elements (with few exceptions, the rear fuselage database (performed at this stage obtained with Pro/ ENGINEER and the one obtained by using ANSYS with the second database. Then, each of the three databases will be used according to arising necessities.The main objective is to develop the parameterized model of the rear fuselage using the computer aided design software Pro/ ENGINEER. A review of research regarding the use of virtual reality with the interactive analysis performed by the finite element method is made to show the state- of- the-art achieved in this field.

  17. Optimisation of process parameters in friction stir welding based on residual stress analysis: a feasibility study

    Tutum, Cem Celal; Hattel, Jesper Henri


    The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two-dimensional sequen......The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two......, and this is presented as a Pareto optimal front. Moreover, a higher welding speed for a fixed rotational speed results, in general, in slightly higher stress levels in the tension zone, whereas a higher rotational speed for a fixed welding speed yields somewhat lower peak residual stress, however, a wider tension zone...

  18. Correlation between the Cyclic Stress Behavior and Microstructure in 316LN based on the Analysis of Hysteresis Loops

    CHANG Bo; ZHANG Zheng


    Total strain controlled cyclic test was performed on 316LN under uniaxial loadings. Through the partitioning of hysteresis loops, the evolution of two components of cyclic flow stress, the internal and effective stresses, was reported. The former one determines the cyclic stress response. Based on the transmission electron microscopic (TEM) observation on specimens loaded with scheduled cycles, it is found that planar dislocation structures prevail during the entire cyclic process at low strain amplitude, while a remarkable dislocation rearrangement from planar structures to heterogeneous spatial distributions is companied by a cyclic softening behavior at high strain amplitude. The competition between the evolution of the intergranular and the intragranular components of the internal stress caused by the transition of slip mode induces the cyclic hardening and softening at high strain levels. The intergranular internal stress represents the most part of the internal stress at low strain level.

  19. Effect of ceramic thickness and composite bases on stress distribution of inlays--a finite element analysis.

    Durand, Letícia Brandão; Guimarães, Jackeline Coutinho; Monteiro Junior, Sylvio; Baratieri, Luiz Narciso


    The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred.

  20. 基于ANSYS的套管螺纹应力分析%Stress Analysis of Threaded Sleeve Based on ANSYS

    李挺前; 沈建; 黄海龙; 高秉峰


    石油套管在井下受力复杂,其螺纹连接是套管的薄弱环节。在目前发现的套损中有很大的比例是由螺纹连接失效造成的,因此真实地模拟井下受力情况,并且准确的测出在不同工况与螺纹部位的应力应变场的关系,对研究套管螺纹连接的极限承载能力,保护套管,保证油田正常生产具有十分重要的意义。文章采用ANSYS软件提供的子模型方法,通过有限元分析方法研究套管螺纹受力状况及变形情况,模拟井下复杂工况环境对套管螺纹的影响,优化螺纹结构,使应力分布更加合理。%Oil Casing is important to oil drilling equipment.Oil pipe in the underground stands complex stress,so oil casing pipe thread connection is the weak link.In the current,a large proportion of damage in the casing is caused by the failure of threaded connections.Realistic simulating the forces underground and accurately measuring the relationship between different conditions and stress or strain fields in threads are important.It is significant to study the limit of carrying capacity of casing thread connection,protecting the casing,and ensuring normal production of oil.Stress Analysis of casing threads are senior non-linear finite element contact problems,so we generally use special nonlinear analysis software.Based on researching the overall stress in the oil casing thread computation,the research is completed by sub-model method provided by ANSYS program.

  1. Analysis and Comparison Based on Component Stress Factor of Dual Active Bridge and Isolated Full Bridge Boost Converters for Bidirectional Fuel Cells Systems

    Pittini, Riccardo; Mira Albert, Maria del Carmen; Zhang, Zhe;


    This paper presents an analysis and comparison of isolated topologies for bidirectional fuel cell systems. The analyzed topologies are the dua l active bridge (DAB) and the isolated full bridge boost converter (IFBBC). The analysis is performed based on the component stress factor (CSF). Results ...

  2. Initial Pre-stress Finding and Structural Behaviors Analysis of Cable Net Based on Linear Adjustment Theory

    REN Tao; CHEN Wu-jun; FU Gong-yi


    The tensile cable-strut structure is a self-equilibrate pre-stressed system. The initial pre-stress calculation is the fundamental structural analysis. A new numerical procedure was developed. The force density method is the cornerstone of analytical formula, and then introduced into linear adjustment theory;the least square least norm solution, the optimized initial pre-stress, is yielded. The initial pre-stress and structural performances of a particular single-layer saddle-shaped cable-net structure were analyzed with the developed method, which is proved to be efficient and correct. The modal analyses were performed with respect to various pre-stress levels. Finally, the structural performances were investigated comprehensively.

  3. Rotors stress analysis and design

    Vullo, Vincenzo


    Stress and strain analysis of rotors subjected to surface and body loads, as well as to thermal loads deriving from temperature variation along the radius, constitutes a classic subject of machine design. Nevertheless attention is limited to rotor profiles for which governing equations are solvable in closed form. Furthermore very few actual engineering issues may relate to structures for which stress and strain analysis in the linear elastic field and, even more, under non-linear conditions (i.e. plastic or viscoelastic conditions) produces equations to be solved in closed form. Moreover, when a product is still in its design stage, an analytical formulation with closed-form solution is of course simpler and more versatile than numerical methods, and it allows to quickly define a general configuration, which may then be fine-tuned using such numerical methods. In this view, all subjects are based on analytical-methodological approach, and some new solutions in closed form are presented. The analytical formul...

  4. iTRAQ-Based Quantitative Proteomic Analysis of Cotton Roots and Leaves Reveals Pathways Associated with Salt Stress.

    Chen, Tingting; Zhang, Lei; Shang, Haihong; Liu, Shaodong; Peng, Jun; Gong, Wankui; Shi, Yuzhen; Zhang, Siping; Li, Junwen; Gong, Juwu; Ge, Qun; Liu, Aiying; Ma, Huijuan; Zhao, Xinhua; Yuan, Youlu


    Salinity is a major abiotic stress that affects plant growth and development. In this study, we performed a proteomic analysis of cotton roots and leaf tissue following exposure to saline stress. 611 and 1477 proteins were differentially expressed in the roots and leaves, respectively. In the roots, 259 (42%) proteins were up-regulated and 352 (58%) were down-regulated. In the leaves, 748 (51%) proteins were up-regulated and 729 (49%) were down-regulated. On the basis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, we concluded that the phenylalanine metabolism and starch and sucrose metabolism were active for energy homeostasis to cope with salt stress in cotton roots. Moreover, photosynthesis, pyruvate metabolism, glycolysis / gluconeogenesis, carbon fixation in photosynthetic organisms and phenylalanine metabolism were inhabited to reduce energy consumption. Characterization of the signaling pathways will help elucidate the mechanism activated by cotton in response to salt stress.

  5. Residual Stress Analysis in Thick Uranium Films

    Hodge, A M; Foreman, R J; Gallegos, G F


    Residual stress analysis was performed on thick, 1.0 to 25 {micro}m, depleted Uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0-300V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses.

  6. Clinical relevance of oxidative stress and sperm chromatin damage in male infertility: an evidence based analysis

    Marcello Cocuzza


    Full Text Available Oxidative stress (OS in the reproductive tract is now a real entity and concern due to the potential harmful effects of high levels of reactive oxygen species (ROS on sperm number, motility, quality, and function including damage to sperm nuclear DNA. Evaluation of OS related damage to non-functional sperm is highly relevant as intracytoplasmic sperm injection (ICSI technique, an effective therapy for severe male factor infertility, bypasses the majority of reproductive tract deficiencies. Despite the controversial findings in the existing literature, there is now enough evidence to show that sperm DNA damage is detrimental to reproductive outcomes. In addition, spermatozoa of infertile men are suggested to carry more DNA damage than do the spermatozoa from fertile men. Besides impairment of fertility such damage is likely to increase the transmission of genetic diseases during the assisted reproductive procedures. Standardization of protocols to assess reactive oxygen species and DNA damage is very important in introducing these tests in such clinical practice. Thus evaluation of seminal ROS levels and extent of sperm DNA damage especially in an infertile male may help develop new therapeutic strategies and improve success of assisted reproductive techniques (ART.

  7. Finite Element Based Stress Analysis of Seat Belt Using Integrated Force Method

    Anjali Kale


    Full Text Available Integrated force method (IFM has been developed for solving various continuum mechanics problems, where all the internal forces are taken as independent variables. The system equilibrium equations (EE's are mathematically concatenated with the MATLAB based compatibility conditions (CC's to form the global set of equations. This paper explains the solution strategy of prototype seat-belt component using integrated force method. Actual seat belt component is taken here to verify IFM based FE element are readily used which is named as REC_5F_8D and REC_13F_16D where 5F and 13F reflects number of internal unknowns and 8D and 16D are number of total displacements respectively. The results for “Von Mises Stress” and Maximum Displacement using IFM based formulation and compared with ANSYS.

  8. Finite element based stress analysis of graphite component in high temperature gas cooled reactor core using linear and nonlinear irradiation creep models

    Mohanty, Subhasish, E-mail:; Majumdar, Saurindranath


    Highlights: • High temperature gas cooled reactor. • Finite element based stress analysis. • H-451 graphite. • Irradiation creep model. • Graphite reflector stress analysis. - Abstract: Irradiation creep plays a major role in the structural integrity of the graphite components in high temperature gas cooled reactors. Finite element procedures combined with a suitable irradiation creep model can be used to simulate the time-integrated structural integrity of complex shapes, such as the reactor core graphite reflector and fuel bricks. In the present work a comparative study was undertaken to understand the effect of linear and nonlinear irradiation creep on results of finite element based stress analysis. Numerical results were generated through finite element simulations of a typical graphite reflector.

  9. Surface stress-based biosensors.

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


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

  10. Comparative genome-scale analysis of niche-based stress-responsive genes in Lactobacillus helveticus strains.

    Senan, Suja; Prajapati, Jashbhai B; Joshi, Chaitanya G


    Next generation sequencing technologies with advanced bioinformatic tools present a unique opportunity to compare genomes from diverse niches. The identification of niche-specific stress-responsive genes can help in characterizing robust strains for multiple applications. In this study, we attempted to compare the stress-responsive genes of a potential probiotic strain, Lactobacillus helveticus MTCC 5463, and a cheese starter strain, Lactobacillus helveticus DPC 4571, from a gut and dairy niche, respectively. Sequencing of MTCC 5463 was done using 454 GS FLX, and contigs were assembled using GS Assembler software. Genome analysis was done using BLAST hits and the prokaryotic annotation server RAST. The MTCC 5463 genome carried multiple orthologs of genes governing stress responses, whereas the DPC 4571 genome lacked in the number of major stress-response proteins. The absence of the bile salt hydrolase gene in DPC 4571 and its presence in MTCC 5463 clearly indicated niche adaptation. Further, MTCC 5463 carried higher copy numbers of genes contributing towards heat, cold, osmotic, and oxidative stress resistance as compared with DPC 4571. Through comparative genomics, we could thus identify stress-responsive gene sets required to adapt to gut and dairy niches.

  11. Stress analysis and probabilistic assessment of multi-layer SiC-based accident tolerant nuclear fuel cladding

    Stone, J. G.; Schleicher, R.; Deck, C. P.; Jacobsen, G. M.; Khalifa, H. E.; Back, C. A.


    Silicon carbide (SiC) fiber, SiC matrix composites (SiC/SiC) are being considered as a cladding material for light water reactors in order to improve safety performance. Engineered, multi-layer cladding designs consisting of both monolithic SiC (mSiC) and SiC/SiC have been examined as promising concepts to meet both strength and impermeability requirements. A new model has been developed to calculate stresses and failure probabilities for multi-layer cladding consisting of SiC-based materials in reactor operating conditions. The results show that stresses in SiC-based cladding are dominated by temperature-dependent irradiation-induced swelling, with the largest stresses occurring during the cold shutdown conditions. Failure probabilities are driven by the resulting tensile stresses at the cladding inner wall, while the outer wall is subject to compressive stresses. This indicates that the inner SiC/SiC, outer mSiC concept has the lowest failure probability, as the pseudo-plastic deformation of the composite reduces tensile loading and the compressed monolith provides a reliable, impermeable barrier to fission product release.

  12. Transcriptome-Based Analysis of Dof Family Transcription Factors and Their Responses to Abiotic Stress in Tea Plant (Camellia sinensis

    Hui Li


    Full Text Available Tea plant (Camellia sinensis (L. O. Kuntze is affected by abiotic stress during its growth and development. DNA-binding with one finger (Dof transcription factors (TFs play important roles in abiotic stress tolerance of plants. In this study, a total of 29 putative Dof TFs were identified based on transcriptome of tea plant, and the conserved domains and common motifs of these CsDof TFs were predicted and analyzed. The 29 CsDof proteins were divided into 7 groups (A, B1, B2, C1, C2.1, C2.2, and D2, and the interaction networks of Dof proteins in C. sinensis were established according to the data in Arabidopsis. Gene expression was analyzed in “Yingshuang” and “Huangjinya” under four experimental stresses by qRT-PCR. CsDof genes were expressed differentially and related to different abiotic stress conditions. In total, our results might suggest that there is a potential relationship between CsDof factors and tea plant stress resistance.

  13. Stress analysis of magnetically controlled reactor

    Ben Tong


    Full Text Available To provide technique references for vibration reduction of magnetically controlled reactors (MCRs, stress, which is the inherent reason of vibration and noise, should be investigated. Stresses in reactor cores are produced due to the magnetostriction deformation of silicon steel and electromagnetic force between the core discs. So far, stress analysis on reactor cores was based on one-way coupled numerical method, which did not consider the influence of the stress on magnetic properties of the core material. Thus, multi-group magnetization and magnetostriction characteristics curves of silicon steel under different tensile stresses are measured firstly to support the computation. From the experiment results, it can be seen that magnetic properties of silicon steel change with stress. Then an electromagneto-mechanical two-way coupled numerical model for MCRs considering magnetostrictive effect and electromagnetic force effect is proposed. Stress distribution of MCR cores under the combination excitation of the sinusoidal wave current and different direct currents are calculated. From the computed results, it can be seen that a larger direct current has greater influence on MCRs vibration, which provides a theory basis for further analysis of vibration and noise reduction.

  14. Stress analysis of magnetically controlled reactor

    Tong, Ben; Qingxin, Yang; Rongge, Yan; Lihua, Zhu; Ling, Weng; Ying, Sun


    To provide technique references for vibration reduction of magnetically controlled reactors (MCRs), stress, which is the inherent reason of vibration and noise, should be investigated. Stresses in reactor cores are produced due to the magnetostriction deformation of silicon steel and electromagnetic force between the core discs. So far, stress analysis on reactor cores was based on one-way coupled numerical method, which did not consider the influence of the stress on magnetic properties of the core material. Thus, multi-group magnetization and magnetostriction characteristics curves of silicon steel under different tensile stresses are measured firstly to support the computation. From the experiment results, it can be seen that magnetic properties of silicon steel change with stress. Then an electromagneto-mechanical two-way coupled numerical model for MCRs considering magnetostrictive effect and electromagnetic force effect is proposed. Stress distribution of MCR cores under the combination excitation of the sinusoidal wave current and different direct currents are calculated. From the computed results, it can be seen that a larger direct current has greater influence on MCRs vibration, which provides a theory basis for further analysis of vibration and noise reduction.

  15. Work-related critical incidents in hospital-based health care providers and the risk of post-traumatic stress symptoms, anxiety, and depression: a meta-analysis.

    de Boer, Jacoba; Lok, Anja; Van't Verlaat, Ellen; Duivenvoorden, Hugo J; Bakker, Arnold B; Smit, Bert J


    This meta-analysis reviewed existing data on the impact of work-related critical incidents in hospital-based health care professionals. Work-related critical incidents may induce post-traumatic stress symptoms or even post-traumatic stress disorder (PTSD), anxiety, and depression and may negatively affect health care practitioners' behaviors toward patients. Nurses and doctors often cope by working part time or switching jobs. Hospital administrators and health care practitioners themselves may underestimate the effects of work-related critical incidents. Relevant online databases were searched for original research published from inception to 2009 and manual searches of the Journal of Traumatic Stress, reference lists, and the European Traumatic Stress Research Database were conducted. Two researchers independently decided on inclusion and study quality. Effect sizes were estimated using standardized mean differences with 95% confidence intervals. Consistency was evaluated, using the I(2)-statistic. Meta-analysis was performed using the random effects model. Eleven studies, which included 3866 participants, evaluated the relationship between work-related critical incidents and post-traumatic stress symptoms. Six of these studies, which included 1695 participants, also reported on the relationship between work-related critical incidents and symptoms of anxiety and depression. Heterogeneity among studies was high and could not be accounted for by study quality, character of the incident, or timing of data collection. Pooled effect sizes for the impact of work-related critical incidents on post-traumatic stress symptoms, anxiety, and depression were small to medium. Remarkably, the effect was more pronounced in the longer than in the shorter term. In conclusion, this meta-analysis supports the hypothesis that work-related critical incidents are positively related to post-traumatic stress symptoms, anxiety, and depression in hospital-based health care professionals

  16. The optimal design of an implant to improve bone quality of implant surroundings based on stress analysis

    Noyama, Yoshihiro; Nagayama, Noriyuki; Kuramoto, Koichi; Nakano, Takayoshi


    Research on how implant surface shape contributes to long-term stability after implantation is important in the field of orthopaedics. In particular, technology that controls various bone quality parameters and voluntary bone inducement in implant surroundings should be developed for the next generation of implants and this will improve the patient's quality of life (QOL). For this research, we focused on the inducement of the appropriate alignment for biological apatite (BAp) crystallites and related collagen (Col.) fibres as a bone quality parameter. In this study, we predicted that when stress is applied to bone, the BAp/Col. preferential alignment can be formed if osteocytes are in an environment that is aligned with the principle stress vector. We tested this idea by introducing grooves in the principal stress direction on the surface of an implant. This work thus analyzes the effect of stress transmission by a load at the proximal femur on the bone inside and near the grooves by using mechanical simulation in which groove angles can be changed on the implant surface. Coordinate data from the mechanical simulation of the combined bone/implant environment was verified against the coordinate data obtained by CT scans of actual canine bone. Results suggest that the tendency of stress transmission differs depending on the position and angle of the grooves and based on a vector diagram of the maximum and minimum principal stresses. The simulation was able to predict bone dynamics in vivo and enabled a best design of an implant to control the BAp/Col. alignment as an index of bone quality.




    Full Text Available This paper deals with the stress analysis of bicycle frame by using Finite Element Method. The analysis is carried out in Ansys, The F.E.A. results are compared with theoretical results. In theoretical analysis the frame is treated as truss like structure and the stresses in various members of frame like top tube, down tube, seat tube, chain stay and seat stay are determined, considering various condition like, static start up, steady state paddling, vertical impact, horizontal impact, rear wheel braking. Also Finite Element Analysis is done considering the above conditions. From the analysis it is found that there is a good agreement between analytical and F.E.A. results. Result of all the cases reveals that maximum stress is found in top tube of the bicycle frame as compared to other frame members and is equal to 24.84 MPa which is less than yield strength in tension (i.e.Syt = 290 MPa for the material (aluminum T 6061 selected.

  18. Minority stress, psychological distress, and alcohol misuse among sexual minority young adults: A resiliency-based conditional process analysis.

    Livingston, Nicholas A; Christianson, Nathan; Cochran, Bryan N


    Sexual minority young adults experience elevated rates of distal stress (discrimination, victimization), and related psychological distress and alcohol misuse. However, few studies have examined the degree to which personality trait differences confer risk/resilience among sexual minority young adults. We hypothesized that psychological distress would mediate the relationship between distal stress and alcohol misuse, but that these relationships would be moderated by personality trait differences. Sexual minority young adults (N=412) were recruited nationally. Survey measures included demographic questions, minority stressors, Five Factor personality traits, and current psychological distress and alcohol misuse symptoms. We used a data-driven two-stage cluster analytic technique to empirically derive personality trait profiles, and conducted mediation and moderated mediation analyses using a regression-based approach. Our results supported a two-group personality profile solution. Relative to at-risk individuals, those classified as adaptive scored lower on neuroticism, and higher on agreeableness, extraversion, conscientiousness, and openness to experience. As predicted, psychological distress mediated the relationship between distal stress and alcohol misuse. However, personality moderated these relationships to the degree that they did not exist among individuals classified as adaptive. In the current study, we found that personality moderated the established relationships between distal stress, psychological distress, and alcohol misuse among sexual minority young adults. Future research is needed to further explicate these relationships, and in order to develop tailored interventions for sexual minority young adults at risk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. How do mindfulness-based cognitive therapy and mindfulness-based stress reduction improve mental health and wellbeing? A systematic review and meta-analysis of mediation studies.

    Gu, Jenny; Strauss, Clara; Bond, Rod; Cavanagh, Kate


    Given the extensive evidence base for the efficacy of mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT), researchers have started to explore the mechanisms underlying their therapeutic effects on psychological outcomes, using methods of mediation analysis. No known studies have systematically reviewed and statistically integrated mediation studies in this field. The present study aimed to systematically review mediation studies in the literature on mindfulness-based interventions (MBIs), to identify potential psychological mechanisms underlying MBCT and MBSR's effects on psychological functioning and wellbeing, and evaluate the strength and consistency of evidence for each mechanism. For the identified mechanisms with sufficient evidence, quantitative synthesis using two-stage meta-analytic structural equation modelling (TSSEM) was used to examine whether these mechanisms mediate the impact of MBIs on clinical outcomes. This review identified strong, consistent evidence for cognitive and emotional reactivity, moderate and consistent evidence for mindfulness, rumination, and worry, and preliminary but insufficient evidence for self-compassion and psychological flexibility as mechanisms underlying MBIs. TSSEM demonstrated evidence for mindfulness, rumination and worry as significant mediators of the effects of MBIs on mental health outcomes. Most reviewed mediation studies have several key methodological shortcomings which preclude robust conclusions regarding mediation. However, they provide important groundwork on which future studies could build. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Effectiveness of mindfulness-based stress reduction and mindfulness-based cognitive therapies on people living with HIV: A systematic review and meta-analysis

    Yang Yang; Yan-Hui Liu; Hong-Fu Zhang; Jing-Ying Liu


    Objective: To assess the effects of mindfulness-based therapies (MBTs) on the outcomes of people living with HIV. Methods: During 2014, we searched the PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and CBM databases to identify randomized and non-randomized controlled studies which compared participants receiving mindfulness-based therapies (MBTs), including mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT), with participants in control gr...

  1. Correlation Between Posttraumatic Growth and Posttraumatic Stress Disorder Symptoms Based on Pearson Correlation Coefficient: A Meta-Analysis.

    Liu, An-Nuo; Wang, Lu-Lu; Li, Hui-Ping; Gong, Juan; Liu, Xiao-Hong


    The literature on posttraumatic growth (PTG) is burgeoning, with the inconsistencies in the literature of the relationship between PTG and posttraumatic stress disorder (PTSD) symptoms becoming a focal point of attention. Thus, this meta-analysis aims to explore the relationship between PTG and PTSD symptoms through the Pearson correlation coefficient. A systematic search of the literature from January 1996 to November 2015 was completed. We retrieved reports on 63 studies that involved 26,951 patients. The weighted correlation coefficient revealed an effect size of 0.22 with a 95% confidence interval of 0.18 to 0.25. Meta-analysis provides evidence that PTG may be positively correlated with PTSD symptoms and that this correlation may be modified by age, trauma type, and time since trauma. Accordingly, people with high levels of PTG should not be ignored, but rather, they should continue to receive help to alleviate their PTSD symptoms.

  2. Residual Stress Determination from a Laser-Based Curvature Measurement

    Swank, William David; Gavalya, Rick Allen; Wright, Julie Knibloe; Wright, Richard Neil


    Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.

  3. The Stress and Stiffness Analysis of Diaphragm

    Qu Dongyue


    Full Text Available Diaphragm coupling with its simple structure, small size, high reliability, which can compensate for its input and output displacement deviation by its elastic deformation, is widely used in aerospace, marine, and chemical etc. This paper uses the ANSYS software and its APDL language to analysis the stress distribution when the diaphragm under the load of torque, axial deviation, centrifugal force, angular deviation and multiple loads. We find that the value of maximum stress usually appears in the outer or inner transition region and the axial deviation has a greater influence to the distribution of the stress. Based on above, we got three kinds of stiffness for axial, angular and torque, which the stiffness of diaphragm is nearly invariable. The results can be regard as an important reference for design and optimization of diaphragm coupling.

  4. AMD-associated genes encoding stress-activated MAPK pathway constituents are identified by interval-based enrichment analysis.

    John Paul SanGiovanni

    Full Text Available PURPOSE: To determine whether common DNA sequence variants within groups of genes encoding elements of stress-activated mitogen-activated protein kinase (MAPK signaling pathways are, in aggregate, associated with advanced AMD (AAMD. METHODS: We used meta-regression and exact testing methods to identify AAMD-associated SNPs in 1177 people with AAMD and 1024 AMD-free elderly peers from 3 large-scale genotyping projects on the molecular genetics of AMD. SNPs spanning independent AAMD-associated genomic intervals were examined with a multi-locus-testing method (INRICH for enrichment within five sets of genes encoding constituents of stress-activated MAPK signaling cascades. RESULTS: Four-of-five pathway gene sets showed enrichment with AAMD-associated SNPs; findings persisted after adjustment for multiple testing in two. Strongest enrichment signals (P = 0.006 existed in a c-Jun N-terminal kinase (JNK/MAPK cascade (Science Signaling, STKE CMP_10827. In this pathway, seven independent AAMD-associated regions were resident in 6 of 25 genes examined. These included sequence variants in: 1 three MAP kinase kinase kinases (MAP3K4, MAP3K5, MAP3K9 that phosphorylate and activate the MAP kinase kinases MAP2K4 and MAP2K7 (molecules that phosphorylate threonine and tyrosine residues within the activation loop of JNK; 2 a target of MAP2K7 (JNK3A1 that activates complexes involved in transcriptional regulation of stress related genes influencing cell proliferation, apoptosis, motility, metabolism and DNA repair; and 3 NR2C2, a transcription factor activated by JNK1A1 (a drugable molecule influencing retinal cell viability in model systems. We also observed AAMD-related sequence variants resident in genes encoding PPP3CA (a drugable molecule that inactivates MAP3K5, and two genes (TGFB2, TGFBR2 encoding factors involved in MAPK sensing of growth factors/cytokines. CONCLUSIONS: Linkage disequilibrium (LD-independent genomic enrichment analysis yielded

  5. Isobaric Tags for Relative and Absolute Quantitation (iTRAQ-Based Comparative Proteome Analysis of the Response of Ramie under Drought Stress

    Xia An


    Full Text Available In this study, we conducted the first isobaric tags for relative and absolute quantitation (isobaric tags for relative and absolute quantitation (iTRAQ-based comparative proteomic analysis of ramie plantlets after 0 (minor drought stress, 24 (moderate drought stress, and 72 h (severe drought stress of treatment with 15% (w/v poly (ethylene glycol6000 (PEG6000 to simulate drought stress. In our study, the association analysis of proteins and transcript expression revealed 1244 and 968 associated proteins identified in leaves and roots, respectively. L1, L2, and L3 are leaf samples which were harvested at 0, 24, and 72 h after being treated with 15% PEG6000, respectively. Among those treatment groups, a total of 118, 216, and 433 unique proteins were identified as differentially expressed during L1 vs. L2, L2 vs. L3, and L1 vs. L3, respectively. R1, R2, and R3 are root samples which were harvested at 0, 24, and 72 h after being treated with 15% PEG6000, respectively. Among those treatment groups,a total of 124, 27, and 240 unique proteins were identified as differentially expressed during R1 vs. R2, R2 vs. R3, and R1 vs. R3, respectively. Bioinformatics analysis indicated that glycolysis/gluconeogenesis was significantly upregulated in roots in response to drought stress. This enhancement may result in more glycolytically generated adenosine triphosphate (ATP in roots to adapt to adverse environmental conditions. To obtain complementary information related to iTRAQ data, the mRNA levels of 12 proteins related to glycolysis/gluconeogenesis in leaves and 7 in roots were further analyzed by qPCR. Most of their expression levels were higher in R3 than R1 and R2, suggesting that these compounds may promote drought tolerance by modulating the production of available energy.

  6. Pull-in instability analysis of rectangular nanoplate based on strain gradient theory considering surface stress effects

    Mirkalantari, S. Amin; Hashemian, Mohammad; Eftekhari, S. Ali; Toghraie, Davood


    In this study, a model is developed based on strain gradient, considering surface stress effect. Then, higher-order nonlinear governing equations and corresponding boundary condition for a hydrostatically and electrostatically actuated rectangular nanoplate are obtained using principle of minimum potential energy. The derived nonlinear differential equations are linearized by step-by-step linearization method, and then the obtained linear equations are discretized by generalized differential quadrature (GDQ) method. The effects of three length scale parameters, boundary conditions, thickness of nanoplate, and surface material properties on pull-in instability behavior are investigated. The obtained results demonstrate that the effects of length scale parameter can influence pull-in instability, and for greater amounts of length scale parameter, higher amounts of voltage are concluded.

  7. Thermographic stress analysis in cortical bone.

    Vanderby, R; Kohles, S S


    Under adiabatic (or near adiabatic) conditions a volumetric change in an elastic material will produce a corresponding change in temperature. Based upon this principle, thermographic stress analysis (TSA) measures changes in surface heat flux (which are related to changes in surface temperature) and relates them to a coupled form of strains or stresses. To demonstrate the feasibility of using this technique for biomechanical applications, we thermographically measured heat flux from loaded specimens of cortical bone and correlated the results with strain gage data. Regular parallelepipeds were cut from the cortex of bovine femora and loaded sinusoidally at 20 Hz. At this rate of loading, mechanically induced changes in surface temperature could be sampled (via heat flux) prior to a measureable attenuation of the thermoelastic effect. Correlation coefficients demonstrated a significant linear relationship between TSA and measured and computed mechanical parameters (stress, strain, first strain invariant, and strain energy density). TSA therefore appears to be a promising technology for experimental stress analysis in cortical bone.

  8. Mindfulness-Based Stress Reduction for Treating Low Back Pain: A Systematic Review and Meta-analysis.

    Anheyer, Dennis; Haller, Heidemarie; Barth, Jürgen; Lauche, Romy; Dobos, Gustav; Cramer, Holger


    Mindfulness-based stress reduction (MBSR) is frequently used to treat pain-related conditions, but its effects on low back pain are uncertain. To assess the efficacy and safety of MBSR in patients with low back pain. Searches of MEDLINE/PubMed, Scopus, the Cochrane Library, and PsycINFO to 15 June 2016. Randomized controlled trials (RCTs) that compared MBSR with usual care or an active comparator and assessed pain intensity or pain-related disability as a primary outcome in patients with low back pain. Two reviewers independently extracted data on study characteristics, patients, interventions, outcome measures, and results at short- and long-term follow-up. Risk of bias was assessed using the Cochrane risk-of-bias tool. Seven RCTs involving 864 patients with low back pain were eligible for review. Compared with usual care, MBSR was associated with short-term improvements in pain intensity (4 RCTs; mean difference [MD], -0.96 point on a numerical rating scale [95% CI, -1.64 to -0.34 point]; standardized mean difference [SMD], -0.48 point [CI, -0.82 to -0.14 point]) and physical functioning (2 RCTs; MD, 2.50 [CI, 0.90 to 4.10 point]; SMD, 0.25 [CI, 0.09 to 0.41 point]) that were not sustained in the long term. Between-group differences in disability, mental health, pain acceptance, and mindfulness were not significant at short- or long-term follow-up. Compared with an active comparator, MBSR was not associated with significant differences in short- or long-term outcomes. No serious adverse events were reported. The number of eligible RCTs was limited; only 3 evaluated MBSR against an active comparator. Mindfulness-based stress reduction may be associated with short-term effects on pain intensity and physical functioning. Long-term RCTs that compare MBSR versus active treatments are needed in order to best understand the role of MBSR in the management of low back pain. None.

  9. Vibration analysis of a rotating functionally graded tapered microbeam based on the modified couple stress theory by DQEM

    Ghadiri, Majid; Shafiei, Navvab; Alireza Mousavi, S.


    Due to having difficulty in solving governing nonlinear differential equations of a non-uniform microbeam, a few numbers of authors have studied such fields. In the present study, for the first time, the size-dependent vibration behavior of a rotating functionally graded (FG) tapered microbeam based on the modified couple stress theory is investigated using differential quadrature element method (DQEM). It is assumed that physical and mechanical properties of the FG microbeam are varying along the thickness that will be defined as a power law equation. The governing equations are determined using Hamilton's principle, and DQEM is presented to obtain the results for cantilever and propped cantilever boundary conditions. The accuracy and validity of the results are shown in several numerical examples. In order to display the influence of size on the first two natural frequencies and consequently changing of some important microbeam parameters such as material length scale, rate of cross section, angular velocity and gradient index of the FG material, several diagrams and tables are represented. The results of this article can be used in designing and optimizing elastic and rotary-type micro-electro-mechanical systems like micro-motors and micro-robots including rotating parts.

  10. Vibration analysis of rotating functionally graded Timoshenko microbeam based on modified couple stress theory under different temperature distributions

    Ghadiri, Majid; Shafiei, Navvab


    In this study, thermal vibration of rotary functionally graded Timoshenko microbeam has been analyzed based on modified couple stress theory considering temperature change in four types of temperature distribution on thermal environment. Material properties of FG microbeam are supposed to be temperature dependent and vary continuously along the thickness according to the power-law form. The axial forces are also included in the model as the thermal and true spatial variation due to the rotation. Governing equations and boundary conditions have been derived by employing Hamiltonian's principle. The differential quadrature method is employed to solve the governing equations for cantilever and propped cantilever boundary conditions. Validations are done by comparing available literatures and obtained results which indicate accuracy of applied method. Results represent effects of temperature changes, different boundary conditions, nondimensional angular velocity, length scale parameter, different boundary conditions, FG index and beam thickness on fundamental, second and third nondimensional frequencies. Results determine critical values of temperature changes and other essential parameters which can be applicable to design micromachines like micromotor and microturbine.

  11. Stress Analysis of Ellipsoidal Shell with Inner Guide Structure

    Wei-Wei Zhang; Xiao-Song Wang; Meng Chen; Shi-Jian Yuan


    In order to overcome stress concentration and increase fatigue life of ellipsoidal shells with inner guide structure, the stress analysis for strength check is very important. Owing to the main sectional profile with ellipsoidal shape, the stress distribution for perfect ellipsoidal shell is firstly conducted based on the theoretical calculation and strain gauges measurement. The experiment results show that the stresses increase gradually from pole region to equatorial plane, but still within elastic range. Secondly, strain gauge measurement for ellipsoidal shells with inner guide structure is conducted. The results show that stresses are concentrated at the vicinity of bottom plate and beyond elastic range, so the structural redesign is needed. Finally based on the analysis mentioned above, a redesigned structure with local thickening is proposed. Experimental research shows that the stress varies more even after structural redesign and within allowable range. Numerical simulation shows that both the deformation and fatigue life after redesign are acceptable.

  12. Carbon 13-Metabolic Flux Analysis derived constraint-based metabolic modelling of Clostridium acetobutylicum in stressed chemostat conditions.

    Wallenius, Janne; Maaheimo, Hannu; Eerikäinen, Tero


    The metabolism of butanol producing bacteria Clostridium acetobutylicum was studied in chemostat with glucose limited conditions, butanol stimulus, and as a reference cultivation. COnstraint-Based Reconstruction and Analysis (COBRA) was applied using additional constraints from (13)C Metabolic Flux Analysis ((13)C-MFA) and experimental measurement results. A model consisting of 451 metabolites and 604 reactions was utilized in flux balance analysis (FBA). The stringency of the flux spaces considering different optimization objectives, i.e. growth rate maximization, ATP maintenance, and NADH/NADPH formation, for flux variance analysis (FVA) was studied in the different modelled conditions. Also a previously uncharacterized exopolysaccharide (EPS) produced by C. acetobutylicum was characterized on monosaccharide level. The major monosaccharide components of the EPS were 40n-% rhamnose, 34n-% glucose, 13n-% mannose, 10n-% galactose, and 2n-% arabinose. The EPS was studied to have butanol adsorbing property, 70(butanol)mg(EPS)g(-1) at 37°C. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Intra-articular Pressure Based Stress Analysis of the Distal Tibia Following Insertion of a Total Ankle Replacement

    Soodmand, Ehsan; Natsakis, Tassos; Jonkers, Ilse; Vander Sloten, Jos


    The ankle joint plays an important role in transferring the human body weight to the ground. Given the associated loading, Osteoarthritis (OA) is one of the most common disorders in the ankle joint. The most common treatment of ankle OA is total ankle arthroplasty (TAA). However it is not known whether TAA influences the stress levels of the bone structures and specially the distal tibia. Clinical studies previously related the occurrence of tibia cysts to focal stress concentrations. In this...

  14. Non-linear analysis indicates chaotic dynamics and reduced resilience in model-based Daphnia populations exposed to environmental stress.

    Richard Ottermanns

    Full Text Available In this study we present evidence that anthropogenic stressors can reduce the resilience of age-structured populations. Enhancement of disturbance in a model-based Daphnia population lead to a repression of chaotic population dynamics at the same time increasing the degree of synchrony between the population's age classes. Based on the theory of chaos-mediated survival an increased risk of extinction was revealed for this population exposed to high concentrations of a chemical stressor. The Lyapunov coefficient was supposed to be a useful indicator to detect disturbance thresholds leading to alterations in population dynamics. One possible explanation could be a discrete change in attractor orientation due to external disturbance. The statistical analysis of Lyapunov coefficient distribution is proposed as a methodology to test for significant non-linear effects of general disturbance on populations. Although many new questions arose, this study forms a theoretical basis for a dynamical definition of population recovery.

  15. 14 CFR 33.62 - Stress analysis.


    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.62 Stress analysis. A stress analysis must be performed on each turbine engine showing the design safety margin of each...

  16. Analysis of stress, musculoskeletal disorders, and fatigue among broadcasting actors.

    Park, Moon-Hee; Kim, Ham-Gyum; Lee, Hae-Kag


    [Purpose] The purpose of the study was to assess the health effects of broadcasting actors through a comprehensive research on their job stress, psychosocial stress, and fatigue and to investigate those factors having an impact on their health condition to present a basis for comparative studies and effective human resource management in the future. [Subjects and Methods] A survey was performed to analyze the relevance of the general features, job stress, psychosocial stress, and fatigue. [Results] Analysis of job stress, one of the characteristics of individuals, revealed that 32.4% of the subjects with less than 5 years of service, 55.5% of those with 6 to 10 years of service, and 52.4% of those with more than 10 years of service showed a high level of stress. Analysis of psychosocial stress, another characteristic of individuals, revealed that 13.4% of the nonsmokers had a high level of psychosocial stress, while 37.7% of smokers had a high level of psychosocial stress based on analysis of chronic disease and psychosocial health. [Conclusion] Based on this study of the stress and fatigue of broadcasting actors, it is expected that improvements can be made to promote their mental health conditions and, organizational safety and to promote effective human resource management.

  17. Finite Element Residual Stress Analysis of Planetary Gear Tooth

    Jungang Wang


    Full Text Available A method to simulate residual stress field of planetary gear is proposed. In this method, the finite element model of planetary gear is established and divided to tooth zone and profile zone, whose different temperature field is set. The gear's residual stress simulation is realized by the thermal compression stress generated by the temperature difference. Based on the simulation, the finite element model of planetary gear train is established, the dynamic meshing process is simulated, and influence of residual stress on equivalent stress of addendum, pitch circle, and dedendum of internal and external meshing planetary gear tooth profile is analyzed, according to non-linear contact theory, thermodynamic theory, and finite element theory. The results show that the equivalent stresses of planetary gear at both meshing and nonmeshing surface are significantly and differently reduced by residual stress. The study benefits fatigue cracking analysis and dynamic optimization design of planetary gear train.

  18. Back-propagation neural network-based approximate analysis of true stress-strain behaviors of high-strength metallic material

    Doh, Jaeh Yeok; Lee, Jong Soo [Yonsei University, Seoul (Korea, Republic of); Lee, Seung Uk [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)


    In this study, a Back-propagation neural network (BPN) is employed to conduct an approximation of a true stress-strain curve using the load-displacement experimental data of DP590, a high-strength material used in automobile bodies and chassis. The optimized interconnection weights are obtained with hidden layers and output layers of the BPN through intelligent learning and training of the experimental data; by using these weights, a mathematical model of the material's behavior is suggested through this feed-forward neural network. Generally, the material properties from the tensile test cannot be acquired until the fracture regions, since it is difficult to measure the cross-section area of a specimen after diffusion necking. For this reason, the plastic properties of the true stress-strain are extrapolated using the weighted-average method after diffusion necking. The accuracies of BPN-based meta-models for predicting material properties are validated in terms of the Root mean square error (RMSE). By applying the approximate material properties, the reliable finite element solution can be obtained to realize the different shapes of the finite element models. Furthermore, the sensitivity analysis of the approximate meta-model is performed using the first-order approximate derivatives of the BPN and is compared with the results of the finite difference method. In addition, we predict the tension velocity's effect on the material property through a first-order sensitivity analysis.

  19. Thermoelastic Stress Analysis: An NDE Tool for the Residual Stress Assessment of Metallic Alloys

    Gyekenyesi, Andrew L.; Baaklini, George Y.


    During manufacturing, certain propulsion components that will be used in a cyclic fatigue environment are fabricated to contain compressive residual stresses on their surfaces because these stresses inhibit the nucleation of cracks. Overloads and elevated temperature excursions cause the induced residual stresses to dissipate while the component is still in service, lowering its resistance to crack initiation. Research at the NASA Glenn Research Center at Lewis Field has focused on employing the Thermoelastic Stress Analysis technique (TSA, also recognized as SPATE: Stress Pattern Analysis by Thermal Emission) as a tool for monitoring the residual stress state of propulsion components. TSA is based on the fact that materials experience small temperature changes when they are compressed or expanded. When a structure is cyclically loaded (i.e., cyclically compressed and expanded), the resulting surface-temperature profile correlates to the stress state of the structure s surface. The surface-temperature variations resulting from a cyclic load are measured with an infrared camera. Traditionally, the temperature amplitude of a TSA signal has been theoretically defined to be linearly dependent on the cyclic stress amplitude. As a result, the temperature amplitude resulting from an applied cyclic stress was assumed to be independent of the cyclic mean stress.

  20. Therapist-Supported Internet-Based Cognitive Behavior Therapy for Stress, Anxiety, and Depressive Symptoms Among Postpartum Women: A Systematic Review and Meta-Analysis.

    Lau, Ying; Htun, Tha Pyai; Wong, Suei Nee; Tam, Wai San Wilson; Klainin-Yobas, Piyanee


    A growing number of meta-analyses have supported the application of therapist-supported Internet-based cognitive behavior therapy (iCBT) for psychological disorders across different populations, but relatively few meta-analyses have concentrated on postpartum women. This meta-analysis evaluated the efficacy of therapist-supported iCBT in improving stress, anxiety, and depressive symptoms among postpartum women. A total of 10 electronic databases were used to search for published and unpublished trials. Cochrane Collaboration tool for assessing risk of bias was utilized to measure methodological quality. Meta-analysis was performed using the RevMan software (Review Manager version 5.3 for Windows from the Nordic Cochrane Centre, the Cochrane Collaboration, 2014). Among the 789 studies identified, 8 randomized controlled trials were selected, involving 1523 participants across 6 countries. More than half (65%) of the eligible studies had a low risk of bias with no heterogeneity. Results revealed that therapist-supported iCBT significantly improved stress (d=0.84, n=5), anxiety (d=0.36, n=6), and depressive symptoms (d=0.63, n=8) of the intervention group compared with those of the control group at post-intervention. This review revealed that therapist-supported iCBT significantly improves stress, anxiety, and depressive symptoms among postpartum women with small to large effects. Future effectiveness studies should establish the essential components, format, and approach of iCBT with optimal levels of human support to maximize a long-term effect.

  1. QTL-based analysis of genotype-by-environment interaction for grain yield of rice in stress and non-stress environments

    Manneh, B.; Stam, P.; Struik, P.C.; Bruce-Oliver, S.; Eeuwijk, van F.A.


    Use of DNA-based markers can accelerate cultivar development in variable cultivation environments since, in contrast to phenotype, DNA markers are environment-independent. In an effort to elucidate the genetic basis of genotype-by-environment interaction (G x E) for yield of rice (Oryza sativa L.),

  2. Performance-Based Rewards and Work Stress

    Ganster, Daniel C.; Kiersch, Christa E.; Marsh, Rachel E.; Bowen, Angela


    Even though reward systems play a central role in the management of organizations, their impact on stress and the well-being of workers is not well understood. We review the literature linking performance-based reward systems to various indicators of employee stress and well-being. Well-controlled experiments in field settings suggest that certain…

  3. Performance-Based Rewards and Work Stress

    Ganster, Daniel C.; Kiersch, Christa E.; Marsh, Rachel E.; Bowen, Angela


    Even though reward systems play a central role in the management of organizations, their impact on stress and the well-being of workers is not well understood. We review the literature linking performance-based reward systems to various indicators of employee stress and well-being. Well-controlled experiments in field settings suggest that certain…

  4. A meta-analysis of the benefits of mindfulness-based stress reduction (MBSR) on psychological function among breast cancer (BC) survivors.

    Huang, Hua-Ping; He, Mei; Wang, Hai-Yan; Zhou, Mengjun


    Psychological issue is the most common co-morbidity of women with breast cancer (BC) after receiving treatment. Effective coping with this problem is significant importance. The aim of this meta-analysis is to evaluate the benefits of mindfulness-based stress reduction (MBSR) on psychological distress among breast cancer survivors. PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials were systematically searched from their inception to June 30, 2014. Two reviewers independently reviewed and extracted the data. The primary outcomes of interest were psychological domains. Review Manager 5.3 was used to pool collected data. Nine articles involving 964 participants were identified. Compared with those in control group, patients in MBSR group have a significant improvement on psychological domains: depression [mean difference (MD), 5.09; 95 % confidence interval (CI), 3.63-6.55; P < 0.00001], anxiety (MD, 2.79; 95 % CI, 1.62-3.96; P < 0.00001), stress (MD, 4.10; 95 % CI, 2.46-5.74; P < 0.00001). MBSR can also improve the overall quality of life (QOL) (MD, -1.16; 95 % CI, -2.21 to -0.12; P = 0.03). On the basis of our findings, MBSR shows a positive effect on psychological function and QOL of breast cancer survivors. This approach can be recommended to breast cancer patients as a part of their rehabilitation.

  5. The shape of change in perceived stress and stress-sensitivity over the course of mindfulness-based stress reduction

    Snippe, E.; Dziak, J.J.; Lanza, S.T.; Nyklicek, I.; Wichers, M.


    Both daily stress and the tendency to react to stress with heightened levels of negative affect (i.e., stress sensitivity) are important vulnerability factors for adverse mental health outcomes. Mindfulness-based stress reduction (MBSR) may help to reduce perceived daily stress and stress

  6. The Shape of Change in Perceived Stress, Negative Affect, and Stress Sensitivity During Mindfulness-Based Stress Reduction

    Snippe, Evelien; Dziak, John J.; Lanza, Stephanie T.; Nykliek, Ivan; Wichers, Marieke

    Both daily stress and the tendency to react to stress with heightened levels of negative affect (i.e., stress sensitivity) are important vulnerability factors for adverse mental health outcomes. Mindfulness-based stress reduction (MBSR) may help to reduce perceived daily stress and stress

  7. Transcriptome Analysis of Sunflower Genotypes with Contrasting Oxidative Stress Tolerance Reveals Individual- and Combined- Biotic and Abiotic Stress Tolerance Mechanisms.

    Ramu, Vemanna S; Paramanantham, Anjugam; Ramegowda, Venkategowda; Mohan-Raju, Basavaiah; Udayakumar, Makarla; Senthil-Kumar, Muthappa


    In nature plants are often simultaneously challenged by different biotic and abiotic stresses. Although the mechanisms underlying plant responses against single stress have been studied considerably, plant tolerance mechanisms under combined stress is not understood. Also, the mechanism used to combat independently and sequentially occurring many number of biotic and abiotic stresses has also not systematically studied. From this context, in this study, we attempted to explore the shared response of sunflower plants to many independent stresses by using meta-analysis of publically available transcriptome data and transcript profiling by quantitative PCR. Further, we have also analyzed the possible role of the genes so identified in contributing to combined stress tolerance. Meta-analysis of transcriptomic data from many abiotic and biotic stresses indicated the common representation of oxidative stress responsive genes. Further, menadione-mediated oxidative stress in sunflower seedlings showed similar pattern of changes in the oxidative stress related genes. Based on this a large scale screening of 55 sunflower genotypes was performed under menadione stress and those contrasting in oxidative stress tolerance were identified. Further to confirm the role of genes identified in individual and combined stress tolerance the contrasting genotypes were individually and simultaneously challenged with few abiotic and biotic stresses. The tolerant hybrid showed reduced levels of stress damage both under combined stress and few independent stresses. Transcript profiling of the genes identified from meta-analysis in the tolerant hybrid also indicated that the selected genes were up-regulated under individual and combined stresses. Our results indicate that menadione-based screening can identify genotypes not only tolerant to multiple number of individual biotic and abiotic stresses, but also the combined stresses.

  8. Residual stress analysis in Co-based laser clad layers by laboratory X-rays and synchrotron diffraction techniques

    de Oliveira, U.; Ocelik, V.; De Hosson, J. Th. M.


    Thick Co-based coatings were prepared by laser cladding technique on C45 steel substrates with different geometries. Microstructural observations were realized using optical, scanning electron and orientation imaging microscopy. The residual strain state on the surface of a clad layer was determined

  9. Residual stress analysis in Co-based laser clad layers by laboratory X-rays and synchrotron diffraction techniques

    de Oliveira, U.; Ocelik, V.; De Hosson, J. Th. M.


    Thick Co-based coatings were prepared by laser cladding technique on C45 steel substrates with different geometries. Microstructural observations were realized using optical, scanning electron and orientation imaging microscopy. The residual strain state on the surface of a clad layer was determined

  10. 基于ANSYS的滚水坝稳定与应力分析%Stability and stress analysis on overflow gravity dam based on ANSYS

    刘亚丽; 辛全才


    Taking the Wan Niu hydraulic engineering as a case, the paper calculated the stability against sliding along the gravity overflow dam foundation surface used the rigid equilibrium limit method and finite element method respectively. Then the paper discussed the comparative analysis between the former two methods and their merits and demerits. Meanwhile, it gave a brief analysis of the dam base stress and proposed problems to be investigated and solved.%以碗牛坝水利工程为例分别利用刚体极限平衡法和有限元法计算溢流重力坝沿坝基面的抗滑稳定,并对这两种方法的分析结果进行了对比,总结两种方法各自的优缺点,同时对坝体基底应力进行简要分析,并提出了需要进一步研究和解决的问题.

  11. 2D design rule and layout analysis using novel large-area first-principles-based simulation flow incorporating lithographic and stress effects

    Prins, Steven L.; Blatchford, James; Olubuyide, Oluwamuyiwa; Riley, Deborah; Chang, Simon; Hong, Qi-Zhong; Kim, T. S.; Borges, Ricardo; Lin, Li


    As design rules and corresponding logic standard cell layouts continue to shrink node-on-node in accordance with Moore's law, complex 2D interactions, both intra-cell and between cells, become much more prominent. For example, in lithography, lack of scaling of λ/NA implies aggressive use of resolution enhancement techniques to meet logic scaling requirements-resulting in adverse effects such as 'forbidden pitches'-and also implies an increasing range of optical influence relative to cell size. These adverse effects are therefore expected to extend well beyond the cell boundary, leading to lithographic marginalities that occur only when a given cell is placed "in context" with other neighboring cells in a variable design environment [1]. This context dependence is greatly exacerbated by increased use of strain engineering techniques such as SiGe and dual-stress liners (DSL) to enhance transistor performance, both of which also have interaction lengths on the order of microns. The use of these techniques also breaks the formerly straightforward connection between lithographic 'shapes' and end-of-line electrical performance, thus making the formulation of design rules that are robust to process variations and complex 2D interactions more difficult. To address these issues, we have developed a first-principles-based simulation flow to study contextdependent electrical effects in layout, arising not only from lithography, but also from stress and interconnect parasitic effects. This flow is novel in that it can be applied to relatively large layout clips- required for context-dependent analysis-without relying on semi-empirical or 'black-box' models for the fundamental electrical effects. The first-principles-based approach is ideal for understanding contextdependent effects early in the design phase, so that they can be mitigated through restrictive design rules. The lithographic simulations have been discussed elsewhere [1] and will not be presented in detail. The

  12. Quantitative analysis of SILCs (stress-induced leakage currents) based on the inelastic trap-assisted tunneling model

    Kamohara, Shiro; Okuyama, Yutaka; Manabe, Yukiko; Okuyama, Kosuke; Kubota, Katsuhiko; Park, Donggun; Hu, Chenming


    We have successfully developed a new quantitative analytical ITAT-based SILC model which can explain both of the two field dependencies, i.e. Fowler-Nordheim (FN)-field and the direct tunneling (DT)-field dependent of A-mode and B-mode SILCs. While DT-field dependence of A-mode comes from the single trap assisted tunneling, FN-field dependence of B- mode originates at the tunneling via the multi-trap leakage path. We have also developed an analytical model for the anomalous SILC of the flash memory cell and investigate the properties of retention lifetime of failure bits. The anomalous SILC shows the DT-field dependence because of the tunneling via the incomplete multi-trap path. A remarkable behavior of retention characteristics predicted by our models is a nearly logarithmic time dependence. The Fowler- Nordheim tunneling model leads to an overestimation of lifetime at low Vth region. To take into account a position of each trap and clarify the detail characteristics of SILC, we have proposed a new Monte Carlo like approach for hopping conduction and successfully explained the anomalous SILC using only physical based parameters.

  13. Experimental stress analysis for materials and structures stress analysis models for developing design methodologies

    Freddi, Alessandro; Cristofolini, Luca


    This book summarizes the main methods of experimental stress analysis and examines their application to various states of stress of major technical interest, highlighting aspects not always covered in the classic literature. It is explained how experimental stress analysis assists in the verification and completion of analytical and numerical models, the development of phenomenological theories, the measurement and control of system parameters under operating conditions, and identification of causes of failure or malfunction. Cases addressed include measurement of the state of stress in models, measurement of actual loads on structures, verification of stress states in circumstances of complex numerical modeling, assessment of stress-related material damage, and reliability analysis of artifacts (e.g. prostheses) that interact with biological systems. The book will serve graduate students and professionals as a valuable tool for finding solutions when analytical solutions do not exist.




    Full Text Available Present work proposes a methodology to design a propeller with a metal and composite material to analyze its strength and deformation using Ansys software. In order to evaluate the effectiveness of composite over metals, stress analysis is performed on both composite and metal propeller using Ansys. Proposed methodology showed substantial improvements in metal propellers. The mean deflection, normal stress and shear stress were found for both metallic and composite propeller by using Ansys. From the results, stressanalysis composite propeller is safe resonance phenomenon. In this work effort is made to reduce stress levels so that advantage of weight reduction along with stresses can be obtained. The comparison analysis of metallic and composite propeller was made for the maximum deformation and normal stresses.

  15. Thermal-stress analysis of ceramic laminate veneer restorations with different incisal preparations using micro-computed tomography-based 3D finite element models.

    Celebi, Alper Tunga; Icer, Esra; Eren, Meltem Mert; Baykasoglu, Cengiz; Mugan, Ata; Yildiz, Esra


    Main objective of this study is to investigate the thermal behavior of ceramic laminate veneer restorations of the maxillary central incisor with different incisal preparations such as butt joint and palatinal chamfer using finite element method. In addition, it is also aimed to understand the effect of different thermal loads which simulates hot and cold liquid imbibing in the mouth. Three-dimensional solid models of the sound tooth and prepared veneer restorations were obtained using micro-computed tomography images. Each ceramic veneer restoration was made up of ceramic, luting resin cement and adhesive layer which were generated based on the scanned images using computer-aided design software. Our solid model also included the remaining dental tissues such as periodontal ligament and surrounding cortical and spongy bones. Time-dependent linear thermal analyses were carried out to compare temperature changes and stress distributions of the sound and restored tooth models. The liquid is firstly in contact with the crown area where the maximum stresses were obtained. For the restorations, stresses on palatinal surfaces were found larger than buccal surfaces. Through interior tissues, the effect of thermal load diminished and smaller stress distributions were obtained near pulp and root-dentin regions. We found that the palatinal chamfer restoration presents comparatively larger stresses than the butt joint preparation. In addition, cold thermal loading showed larger temperature changes and stress distributions than those of hot thermal loading independent from the restoration technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Near surface stress analysis strategies for axisymmetric fretting

    M Ramesh; Satish V Kailas; K R Y Simha


    Fretting is essentially a surface phenomenon, but bulk stresses and material properties contribute to subsequent failure. This feature of fretting demands a thorough understanding of near surface stresses under the joint action of normal, shear and thermal loading. Axisymmetric fretting is of great concern in piping and coupling design. In this paper, we develop design tools for Near Surface Analysis (NSA) for understanding axisymmetric fretting. Axisymmetric Fretting Analysis (AFA) becomes formidable owing to localised tractions that call for Fourier transform techniques. We develop two different NSA strategies based on two-dimensional plane strain models: 2D strip model (2DS) and half-plane Flamant model (2DF). We compare the results of 2DS and 2DF with the exact results for AFA obtained using Love’s stress function in conjunction with Fourier transform. There is a good correspondence between stress components obtained from 2D-models.

  17. Bending and Free Vibration Analysis of Nonlocal Functionally Graded Nanocomposite Timoshenko Beam Model Rreinforced by SWBNNT Based on Modified Coupled Stress Theory

    M. Mohammadimehr


    Full Text Available In this article, the bending and free vibration analysis of functionally graded (FG nanocomposites Timoshenko beam model reinforced by single-walled boron nitride nanotube (SWBNNT using micro-mechanical approach embedded in an elastic medium is studied. The modified coupled stress (MCST and nonlocal elasticity theories are developed to take into account the size-dependent effect. The mechanical properties of FG boron nitride nanotube-reinforced composites are assumed to be graded in the thickness direction and estimated through the micro-mechanical approach. The governing equations of motion are obtained using Hamilton’s principle based on Timoshenko beam theory. The Navier's type solution is implemented to solve the equations that satisfy the simply supported boundary conditions. Furthermore, the influences of the slenderness ratio, length of nanocomposite beam, material length scale parameter, nonlocal parameter, power law index, axial wave number, and Winkler and Pasternak coefficients on the natural frequency of nanocomposite beam are investigated. Also, the effect of material length scale parameter on the dimensionless deflection of FG nanocomposite beam is studied.

  18. On stress-forecasting strategy of earthquakes from stress buildup, stress shadow and stress transfer (SSS) based on numerical approach

    Chunan Tang; Tianhui Ma; Xiaoli Ding


    Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), used for monitoring crust deformation, are found to be very promising in earthquake prediction subject to stress-forecasting. However, it is rec-ognized that unless we can give reasonable explanations of these curious precursory phenomena that continue to be seren-dipitously observed fi'om time to time, such high technology of GPS or InSAR is difficult to be efficiently used. Therefore, a proper model revealing the relation between earthquake evolution and stress variation, such as the phenomena of stress buildup, stress shadow and stress transfer (SSS), is crucial to the GPS or lnSAR based earthquake prediction. Here we ad-dress this question through a numerical approach of earthquake development using an intuitive physical model with a map-like configuration of discontinuous fault system. The simulation provides a physical basis for the principle of stress-forecasting of earthquakes based on SSS and for the application of GPS or InSAR in earthquake prediction. The ob-served SSS associated phenomena with images of stress distribution during the failure process can be continuously simulated. It is shown that the SSS are better indicators of earthquake precursors than that of seismic foreshocks, suggesting a predict-ability of earthquakes based on stress-forecasting strategy.

  19. Evaluation of polymerization shrinkage, polymerization shrinkage stress, wear resistance, and compressive strength of a silorane-based composite: A finite element analysis study

    Suresh Mitthra


    Full Text Available Background: Understanding the mechanical properties is important in predicting the clinical behavior of composites. Finite element analysis (FEA evaluates properties of materials replicating clinical scenario. Aim: This study evaluated polymerization shrinkage and stress, wear resistance (WR, and compressive strength (CS of silorane in comparison with two methacrylate resins. Settings and Design: This study design was a numerical study using FEA. Materials and Methods: Three-dimensional (3D models of maxillary premolar with Class I cavities (2 mm depth, 4 mm length, and 2.5 mm width created and restored with silorane, nanohybrid, and microhybrid; Groups I, II, and III, respectively. Loads of 200–600 N were applied. Polymerization shrinkage was first determined by displacement produced in the X, Y, and Z planes. Maximum stress distribution due to shrinkage was calculated using AN SYS software. 3D cube models of composite resins were simulated with varying filler particle size. Similar loads were applied. WR and compressive stress were calculated: K W L/H and load/cross-sectional area, respectively. Statistical analysis done using one-way ANOVA, Kruskal–Wallis, and Tukey's honestly significant difference test (P < 0.05. Results: Polymerization shrinkage (0.99% and shrinkage stress (233.21 Mpa of silorane were less compared to microhybrid (2.14% and 472.43 Mpa and nanohybrid (2.32% and 464.88 Mpa. Silorane (7.92×/1011 μm/mm3 and nanohybrid (7.79×/1011 showed superior WR than microhybrid (1.113×/1017. There was no significant difference in compressive stress among the groups. Conclusion: Silorane exhibited less polymerization shrinkage and shrinkage stress compared to methacrylates. Silorane and nanohybrid showed greater WR compared to microhybrid. CS of all groups was similar.

  20. Plant stress analysis technology deployment

    Ebadian, M.A.


    Monitoring vegetation is an active area of laser-induced fluorescence imaging (LIFI) research. The Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU) is assisting in the transfer of the LIFI technology to the agricultural private sector through a market survey. The market survey will help identify the key eco-agricultural issues of the nations that could benefit from the use of sensor technologies developed by the Office of Science and Technology (OST). The principal region of interest is the Western Hemisphere, particularly, the rapidly growing countries of Latin America and the Caribbean. The analysis of needs will assure that the focus of present and future research will center on economically important issues facing both hemispheres. The application of the technology will be useful to the agriculture industry for airborne crop analysis as well as in the detection and characterization of contaminated sites by monitoring vegetation. LIFI airborne and close-proximity systems will be evaluated as stand-alone technologies and additions to existing sensor technologies that have been used to monitor crops in the field and in storage.

  1. Thermal Stress Analysis of Security Injection Tank


    The purpose of the thermal stress analysis of the security injection tank is to make sure whether the tank can withstand the concerned thermal load or not on all the conditions conforming to the concerned code prescripts and the design requirements.


    Krešimir Tor


    Full Text Available By excavation of opening in the rock, a stress concentration around the opening occurs. The state of stresses and strains around an opening is analysed by theory of elasticity and by Finite Element Method (FEM.The aim of the paper is to determine the dimension of the FEM model for the stress and strain analysis around an elliptical opening in rock massif. The numerical calculation have been performed for two different boundary conditions: with forces or with displacements. Boundary conditions given by displacements give better approximation in the state of stress and strains. An example of the excavation of a road tunnel is used to represent stress concentration at the opening and the places where the plastic zones occur. The computation has been done after FEM comprising the Hock-Brown criterion of failure. The results of stability analysis point to the zones where failure of the rock material may be anticipa¬ted. This is important when planning and designing the primary supp¬orts. The comparison of the results of numerical modelling and field recording during excavation is of particular significance (the paper is published in Croatian.

  3. Analysis of pull-in instability of geometrically nonlinear microbeam using radial basis artificial neural network based on couple stress theory.

    Heidari, Mohammad; Heidari, Ali; Homaei, Hadi


    The static pull-in instability of beam-type microelectromechanical systems (MEMS) is theoretically investigated. Two engineering cases including cantilever and double cantilever microbeam are considered. Considering the midplane stretching as the source of the nonlinearity in the beam behavior, a nonlinear size-dependent Euler-Bernoulli beam model is used based on a modified couple stress theory, capable of capturing the size effect. By selecting a range of geometric parameters such as beam lengths, width, thickness, gaps, and size effect, we identify the static pull-in instability voltage. A MAPLE package is employed to solve the nonlinear differential governing equations to obtain the static pull-in instability voltage of microbeams. Radial basis function artificial neural network with two functions has been used for modeling the static pull-in instability of microcantilever beam. The network has four inputs of length, width, gap, and the ratio of height to scale parameter of beam as the independent process variables, and the output is static pull-in voltage of microbeam. Numerical data, employed for training the network, and capabilities of the model have been verified in predicting the pull-in instability behavior. The output obtained from neural network model is compared with numerical results, and the amount of relative error has been calculated. Based on this verification error, it is shown that the radial basis function of neural network has the average error of 4.55% in predicting pull-in voltage of cantilever microbeam. Further analysis of pull-in instability of beam under different input conditions has been investigated and comparison results of modeling with numerical considerations shows a good agreement, which also proves the feasibility and effectiveness of the adopted approach. The results reveal significant influences of size effect and geometric parameters on the static pull-in instability voltage of MEMS.

  4. Individuals' stress assessment using human-smartphone interaction analysis

    Ciman, Matteo; Wac, Katarzyna


    The increasing presence of stress in people’ lives has motivated much research efforts focusing on continuous stress assessment methods of individuals, leveraging smartphones and wearable devices. These methods have several drawbacks, i.e., they use invasive external devices, thus increasing entry...... costs and reducing user acceptance, or they use some of privacy-related information. This paper presents an approach for stress assessment that leverages data extracted from smartphone sensors, and that is not invasive concerning privacy. Two different approaches are presented. One, based on smartphone...... gestures analysis, e.g., ‘tap’, ‘scroll’, ‘swipe’ and ‘text writing’, and evaluated in laboratory settings with 13 participants (F-measure 79-85% within-subject model, 70-80% global model); the second one based on smartphone usage analysis and tested in-the-wild with 25 participants (F-measure 77...

  5. Salt stress induced lipid accumulation in heterotrophic culture cells of Chlorella protothecoides: Mechanisms based on the multi-level analysis of oxidative response, key enzyme activity and biochemical alteration.

    Wang, Tao; Ge, Haiyan; Liu, Tingting; Tian, Xiwei; Wang, Zejian; Guo, Meijin; Chu, Ju; Zhuang, Yingping


    Salt stress as an effective stress factor that could improve the lipid content and lipid yield of glucose in the heterotrophic culture cells of Chlorella protothecoides was demonstrated in this study. The highest lipid content of 41.2% and lipid yield of 185.8mg/g were obtained when C. protothecoides was stressed under 30g/L NaCl condition at its late logarithmic growth phase. Moreover, the effects of salt and osmotic stress on lipid accumulation were comparatively analyzed, and it was found that the effects of NaCl and KCl stress had no significant differences at the same osmolarity level of 1150mOsm/kg with lipid contents of 41.7 and 40.8% as well as lipid yields of 192.9 and 186.8mg/g, respectively, whereas these results were obviously higher than those obtained under the iso-osmotic glycerol and sorbitol stresses. Furthermore, basing on the multi-level analysis of oxidative response, key enzyme activity and biochemical alteration, the superior performance of salt stress driving lipid over-synthesis was probably ascribed to the more ROS production as a result of additional ion effect besides the osmotic effect, subsequently mediating the alteration from carbohydrate storage to lipid accumulation in signal transduction process of C. protothecoides.

  6. Photoelastic stress analysis in mitred bend under internal pressure

    Sawa, Yoshiaki


    The stress analysis and stress relaxation in mitred bend subjected to internal pressure have been studied by means of the photoelastic stress freezing method. The experimental results show that stress concentration occurs in the wedge tip of the intersectional plane and it is considerably influenced by the bent angle. Then, the stress relaxation was obtained by planing the wedge tip.

  7. Stress history and fracture pattern in fault-related folds based on limit analysis: application to the Sub-Andean thrust belt of Bolivia

    Barbe, Charlotte; Leroy, Yves; Ben Miloud, Camille


    A methodology is proposed to construct the stress history of a complex fault-related fold in which the deformation mechanisms are essentially frictional. To illustrate the approach, fours steps of the deformation of an initially horizontally layered sand/silicone laboratory experiment (Driehaus et al., J. of Struc. Geol., 65, 2014) are analysed with the kinematic approach of limit analysis (LA). The stress, conjugate to the virtual velocity gradient in the sense of mechanicam power, is a proxy for the true statically admmissible stress field which prevailed over the structure. The material properties, friction angles and cohesion, including their time evolution are selected such that the deformation pattern predicted by the LA is consistent with the two main thrusting events, the first forward and the second backward once the layers have sufficiently rotated. The fractures associated to the stress field determined at each step are convected on today configuration to define the complete pattern which should be observed. The end results are presented along virtual vertical wells and could be used within the oil industry at an early phase of exploration to prepare drealing operations.


    王利民; 徐世烺


    The nonlinear fracture behavior of quasi-brittle materials is closely related with the cohesive force distribution of fracture process zone at crack tip. Based on fracture character of quasi-brittle materials, a mechanical analysis model of half infinite crack with cohesive stress is presented. A pair of integral equations is established according to the superposition principle of crack opening displacement in solids, and the fictitious adhesive stress is unknown function. The properties of integral equations are analyzed, and the series function expression of cohesive stress is certified. By means of the data of actual crack opening displacement, two approaches to gain the cohesive stress distribution are proposed through resolving algebra equation. They are the integral transformation method for continuous displacement of actual crack opening, and the least square method for the discrete data of crack opening displacement. The calculation examples of two approaches and associated discussions are given.

  9. Thermal stress analysis of laminated LCDs for aircraft cockpits

    Feng, Qibin; Hua, Yikui; Lv, Guoqiang; Lu, Xiaosong


    Different from common liquid crystal displays (LCDs), LCDs in aircraft cockpits have to satisfy some special requirements, including high luminance, high contrast ration, anti-reflection (AR), and electromagnetic compatibility (EMC). Indium-tin oxide (ITO) glasses are usually attached on the top surface of LC cells by optical adhesive for AR and EMC, forming laminated structure. The characteristics of optical adhesive and lamination processing have direct effects on display. This paper creates a finite-element-analysis model of the laminated LC cell with ITO glass. The simulation results show that the stress concentration happens in the case that there are defects (bubbles, cracks, nonuniform thickness) in the optical adhesive when the operation temperature raises to 70º C. Based on the analysis of the stress on the top surface of the LC cell in Y direction, it is found that the location of the stress concentration is just under where the defects exit. The comparison on the stress of 3 possible defects shows that the concentrated stress caused by the cracks are far more large than the stress by the bubbles and nonuniform thickness of optical adhesives, which should try best to avoid.

  10. A micro-mechanical analysis of thermo-elastic properties and local residual stresses in ductile iron based on a new anisotropic model for the graphite nodules

    Andriollo, Tito; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper


    In this paper, the thermo-elastic behavior of the graphite nodules contained in ductile iron is derived on the basis of recent transmission electron microscopy investigations of their real internal structure. The proposed model is initially validated by performing a finite element homogenization analysis to verify its consistency with the room-temperature elastic properties of ductile iron measured at the macro scale. Subsequently, it is used to investigate the formation of local residual stresses around the graphite particles by simulating the manufacturing process of a typical ferritic ductile iron grade, and the results are compared with preliminary measurements using synchrotron x-rays. Finally, the obtained accurate description of the stress & strain field at the micro scale is used to shed light on common failure modes reported for the nodules and on some peculiar properties observed in ductile iron at both micro and macro scale.

  11. RNA-Seq-based transcriptomic and metabolomic analysis reveal stress responses and programmed cell death induced by acetic acid in Saccharomyces cerevisiae

    Dong, Yachen; Hu, Jingjin; Fan, Linlin; Chen, Qihe


    As a typical harmful inhibitor in cellulosic hydrolyzates, acetic acid not only hinders bioethanol production, but also induces cell death in Saccharomyces cerevisiae. Herein, we conducted both transcriptomic and metabolomic analyses to investigate the global responses under acetic acid stress at different stages. There were 295 up-regulated and 427 down-regulated genes identified at more than two time points during acetic acid treatment (150 mM, pH 3.0). These differentially expressed genes (DEGs) were mainly involved in intracellular homeostasis, central metabolic pathway, transcription regulation, protein folding and stabilization, ubiquitin-dependent protein catabolic process, vesicle-mediated transport, protein synthesis, MAPK signaling pathways, cell cycle, programmed cell death, etc. The interaction network of all identified DEGs was constructed to speculate the potential regulatory genes and dominant pathways in response to acetic acid. The transcriptional changes were confirmed by metabolic profiles and phenotypic analysis. Acetic acid resulted in severe acidification in both cytosol and mitochondria, which was different from the effect of extracellular pH. Additionally, the imbalance of intracellular acetylation was shown to aggravate cell death under this stress. Overall, this work provides a novel and comprehensive understanding of stress responses and programmed cell death induced by acetic acid in yeast. PMID:28209995

  12. Analysis of viscoelasticity of POF gratings in the stress sensing

    Luo, Yanhua; Wang, Xin; Yan, Binbin; Wang, Tongxin; Wu, Wenxuan; Peng, Gang-Ding; Zhang, Qijin


    The time-dependent behavior of polymer optical fiber (POF) grating under constant tensile stresses has been studied. We show that the evident time-dependence is due to the viscoelastic nature of POF grating materials that can be described with the Kelvin Model. Based on the Kelvin Model, the time-dependent relationship between the Bragg wavelength shift and stress has been analyzed in detail. The results show that the viscoelasticity has a great impact upon the stress response of POF gratings. With the increment of stress level, the visco response part increases faster than that of elastic response part. Especially, the response and recovery with and without stress can be fitted with dual exponential decay and the time constant of fast response and relaxation is ˜102 s and that of the slow is ˜103 s, which corresponds to the fast and slow movements of polymer segments, respectively. Experiments and regressions also show that the stress sensitivity is observed to be 369 pm/MPa for the immediate response and 598 pm/MPa for response balance, showing high stress sensitivity. All the spring stiffness and dashpot viscosity of Kelvin elements are larger than 1010 Pa and 1013 Pa s. The dashpot viscosity of slow Kelvin element (1014 Pa s) is around one order larger than that of fast Kelvin element (1013 Pa s) with stress. Further analysis demonstrate the response and recovery of POF gratings with and without the stress displays an evident non-linear viscoelasticity, which will bring more complexity for POF gratings in the mechanical sensing applications.

  13. Laser pulse heating of surfaces and thermal stress analysis

    Yilbas, Bekir S; Al-Aqeeli, Nasser; Al-Qahtani, Hussain M


    This book introduces laser pulse heating and thermal stress analysis in materials surface. Analytical temperature treatments and stress developed in the surface region are also explored. The book will help the reader analyze the laser induced stress in the irradiated region and presents solutions for the stress field. Detailed thermal stress analysis in different laser pulse heating situations and different boundary conditions are also presented. Written for surface engineers.

  14. Phase unwrapping work of photoelastic stress analysis

    Huang, M. J.; Sung, P. C.; An, H. L.


    π Photoelasticity plays an important role in the field of stress analysis. Not only because it is a non-contact whole field optical method, but it provides isoclinic (principal stress direction) and isochomatic (principal stress difference) data as well, which serve as the two most important parameters in the field. But, unfortunately, the coupling between these two parameters induces phase ambiguity problem in the isochromatic data unless the isoclinic data have been correctly procured first. In this paper, a novel spatial phase unwrapping is first applied for retrieving the correct isoclinic data, which is then substituted into the isochromatic calculation to solve the 2 ambiguity problem conducted by wrapped isoclinic data. The result is checked with that from the theoretical analysis and shown to be with limited error. The same problem is solved in a different way - by the temporal approaches, load stepping or multiple wavelengths sourcing in advance. The intercomparison depicts that the spatial approach is more noise-immune than the temporal approach is. It is because that by the spatial approach the algorithm can check data not only of themselves but consult data also from their neighbors. As a result, any small localized error can be eliminated accordingly.

  15. iTRAQ-based quantitative proteomic analysis reveals proteomic changes in leaves of cultivated tobacco (Nicotiana tabacum) in response to drought stress.

    Xie, He; Yang, Da-Hai; Yao, Heng; Bai, Ge; Zhang, Yi-Han; Xiao, Bing-Guang


    Drought is one of the most severe forms of abiotic stresses that threaten the survival of plants, including crops. In turn, plants dramatically change their physiology to increase drought tolerance, including reconfiguration of proteomes. Here, we studied drought-induced proteomic changes in leaves of cultivated tobacco (Nicotiana tabacum), a solanaceous plant, using the isobaric tags for relative and absolute quantitation (iTRAQ)-based protein labeling technology. Of identified 5570 proteins totally, drought treatment increased and decreased abundance of 260 and 206 proteins, respectively, compared with control condition. Most of these differentially regulated proteins are involved in photosynthesis, metabolism, and stress and defense. Although abscisic acid (ABA) levels greatly increased in drought-treated tobacco leaves, abundance of detected ABA biosynthetic enzymes showed no obvious changes. In contrast, heat shock proteins (HSPs), thioredoxins, ascorbate-, glutathione-, and hydrogen peroxide (H2O2)-related proteins were up- or down-regulated in drought-treated tobacco leaves, suggesting that chaperones and redox signaling are important for tobacco tolerance to drought, and it is likely that redox-induced posttranslational modifications play an important role in modulating protein activity. This study not only provides a comprehensive dataset on overall protein changes in drought-treated tobacco leaves, but also shed light on the mechanism by which solanaceous plants adapt to drought stress.

  16. Stress-strain behaviour analysis of Middle Polish glacial tills from Warsaw (Poland) based on the interpretation of advanced field and laboratory tests

    Bąkowska, Anna; Dobak, Dobak; Gawriuczenkow, Ireneusz; Kiełbasiński, Kamil; Szczepański, Tomasz; Trzciński, Jerzy; Wójcik, Emilia; Zawrzykraj, Piotr


    The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.

  17. EEG sensor based classification for assessing psychological stress.

    Begum, Shahina; Barua, Shaibal


    Electroencephalogram (EEG) reflects the brain activity and is widely used in biomedical research. However, analysis of this signal is still a challenging issue. This paper presents a hybrid approach for assessing stress using the EEG signal. It applies Multivariate Multi-scale Entropy Analysis (MMSE) for the data level fusion. Case-based reasoning is used for the classification tasks. Our preliminary result indicates that EEG sensor based classification could be an efficient technique for evaluation of the psychological state of individuals. Thus, the system can be used for personal health monitoring in order to improve users health.

  18. Integrated pathway-based and network-based analysis of GC-MS rice metabolomics data under diazinon stress to infer affected biological pathways.

    Mahdavi, Vahideh; Ghanati, Faezeh; Ghassempour, Alireza


    Diazinon insecticide is widely applied in rice (Oryza sativa L.) fields in Iran. However, concerns are now being raised about its potential adverse impacts on rice. In this study, a time-course metabolic change in rice plants was investigated after diazinon treatment using gas chromatography-mass spectrometry (GC-MS) and subsequently three different methods, MetaboAnalyst, MetaboNetwork, and analysis of reporter reactions, as a potential multivariate method were used to find the underlying changes in metabolism with stronger evidence in order to link differentially expressed metabolites to biological pathways. Results clearly showed the similarity of acetylcholinesterase (AChE) of rice plants to that of animals in terms of its inhibitability by diazinon and emphasized that subsequent accumulation of AChE mainly affects the metabolism of osmolites and tricarboxylic acid intermediates subsequent accumulation of ACh mainly affects the metabolism of osmolites and TCA intermediates.

  19. Method for analysis and assessment of the relation between stress and reliability of knowledge-based actions in the probabilistic safety analysis; Methode fuer die Analyse und Bewertung der Wechselwirkung zwischen Stress und der Zuverlaessigkeit wissensbasierten Handelns in der probabilistischen Sicherheitsanalyse

    Fassmann, Werner


    According to the current theoretical and empirical state-of-the-art, stress has to be understood as the emotional and cognitive reaction by which humans adapt to situations which imply real or imagined danger, threat, or frustration of important personal goals or needs. The emotional reaction to such situations can be so extreme that rational coping with the situation will be precluded. In less extreme cases, changes of cognitive processes underlying human action will occur, which may systematically affect the reliability of tasks personnel has to perform in a stressful situation. Reliable task performance by personnel of nuclear power plants and other risk technologies is also affected by such effects. The method developed in the frame of the research and development project RS1198 sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi) addresses both aspects of emotional and cognitive coping with stressful situations. Analytical and evaluation steps of the approach provide guidance to the end users on how to capture and quantify the contribution of stress-related emotional and cognitive factors to the reliable performance of knowledge-based actions. For this purpose, a suitable guideline has been developed. Further research for clarifying open questions has been identified. A case study application illustrates how to use the method. Part of the work performed in this project was dedicated to a review addressing the question to which extent Swain's approach to the analysis and evaluation of stress is in line with current scientific knowledge. Suitable suggestions for updates have been developed.

  20. Finite element analysis of the stress-concentrating effect of fraenal notches in complete dentures.

    Rees, J S; Huggett, R; Harrison, A


    Based on clinical experience and empiricism, it was postulated that fraenal notches and midline diastemas lead to fracture of complete dentures. This study used finite element stress analysis to investigate the stress-concentrating effect of a fraenal notch with and without a midline diastema. It was found that a large fraenal notch resulted in high stress levels and that these stresses were augmented more by a narrow median diastema than its wider counterpart.

  1. Analysis of Biaxially Stressed Bridge Deck Plates

    Jönsson, Jeppe; Bondum, Tommi Højer


    The ultimate state analysis of bridge deck plates at the intersection zone between main girders and transverse beams is complicated by biaxial membrane stresses, which may be in compression or tension in either direction depending on the bridge configuration and the specific location. This paper...... presents a detailed investigation of the ultimate capacity of simply supported plates subjected to biaxial loads. The full interaction domain of combinations of compressive and tensile loads has been investigated including a large number of imperfections. It was found that non-standard imperfection modes...

  2. iTRAQ-based quantitative analysis of hippocampal postsynaptic density-associated proteins in a rat chronic mild stress model of depression.

    Han, X; Shao, W; Liu, Z; Fan, S; Yu, J; Chen, J; Qiao, R; Zhou, J; Xie, P


    Major depressive disorder (MDD) is a prevalent psychiatric mood illness and a major cause of disability and suicide worldwide. However, the underlying pathophysiology of MDD remains poorly understood due to its heterogenic nature. Extensive pre-clinical research suggests that many molecular alterations associated with MDD preferentially localize to the postsynaptic density (PSD). Here, we used a rodent chronic mild stress (CMS) model to generate susceptible and unsusceptible subpopulations. Proteomic analysis using an isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass spectrometry was performed to identify differentially expressed proteins in enriched PSD preparations from the hippocampi of different groups. More than 1500 proteins were identified and quantified, and 74 membrane proteins were differentially expressed. Of these membrane proteins, 51 (69%) were identified by SynaptomeDB search as having a predicted PSD localization. The unbiased profiles identified several PSD candidate proteins that may be related to CMS vulnerability or insusceptibility, and these two CMS phenotypes displayed differences in the abundance of several types of proteins. A detailed protein functional analysis pointed to a role for PSD-associated proteins involved in signaling and regulatory functions. Within the PSD, the N-methyl-D-aspartate (NMDA) receptor subunit NR2A and its downstream targets contribute to CMS susceptibility. Further analysis of disease relevance indicated that the PSD contains a complex set of proteins of known relevance to mental illnesses including depression. In sum, these findings provide novel insights into the contribution of PSD-associated proteins to stress susceptibility and further advance our understanding of the role of hippocampal synaptic plasticity in MDD.

  3. Stress analysis of fracture of atherosclerotic plaques: crack propagation modeling.

    Rezvani-Sharif, Alireza; Tafazzoli-Shadpour, Mohammad; Kazemi-Saleh, Davood; Sotoudeh-Anvari, Maryam


    Traditionally, the degree of luminal obstruction has been used to assess the vulnerability of atherosclerotic plaques. However, recent studies have revealed that other factors such as plaque morphology, material properties of lesion components and blood pressure may contribute to the fracture of atherosclerotic plaques. The aim of this study was to investigate the mechanism of fracture of atherosclerotic plaques based on the mechanical stress distribution and fatigue analysis by means of numerical simulation. Realistic models of type V plaques were reconstructed based on histological images. Finite element method was used to determine mechanical stress distribution within the plaque. Assuming that crack propagation initiated at the sites of stress concentration, crack propagation due to pulsatile blood pressure was modeled. Results showed that crack propagation considerably changed the stress field within the plaque and in some cases led to initiation of secondary cracks. The lipid pool stiffness affected the location of crack formation and the rate and direction of crack propagation. Moreover, increasing the mean or pulse pressure decreased the number of cycles to rupture. It is suggested that crack propagation analysis can lead to a better recognition of factors involved in plaque rupture and more accurate determination of vulnerable plaques.

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

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


    was rest & vacation, followed by nature and water. When we applied the classifiers to the cities dataset, the proportion of stress tweets in New York and San Diego was substantially higher than that in Los Angeles and San Francisco. In addition, we found that characteristic expressions of stress and relaxation varied for each city based on its geolocation. This content analysis and infodemiology study revealed that Twitter, when used in conjunction with natural language processing techniques, is a useful data source for understanding stress and stress management strategies, and can potentially supplement infrequently collected survey-based stress data.

  5. A micropolariscope for automatic stress analysis

    Fessler, H.; Marston, R. E.; Ollerton, E.


    A micropolariscope has been developed for the automatic analysis of photoelastic data. It will position frozen stress slices mounted on its stage to within + or - 0.002 mm and take readings of isoclinic angles and fractional fringe orders, repeatable to within + or - 0.08 degrees and + or - 0.001 fringes. A rectangular grid of up to 3 x 50 points can be read automatically, taking about 1.25 minutes per point; the readings are stored on a floppy disc and printed out. The original slice is itself sliced, and the subslice is viewed again in the orthogonal direction to produce a second set of readings. Software has been devised to analyze the two sets of readings. It makes use of Tesar's (1933) modification of Frocht and Guernsey (1952) shear difference method to calculate five Cartesian stresses, which may be plotted and printed in tabular form. Flexible facilities are provided for editing, correcting, plotting, and printing intermediate stages in the analysis, and for storing results in data files.

  6. Size-dependent dynamic pull-in analysis of geometric non-linear micro-plates based on the modified couple stress theory

    Askari, Amir R.; Tahani, Masoud


    This paper focuses on the size-dependent dynamic pull-in instability in rectangular micro-plates actuated by step-input DC voltage. The present model accounts for the effects of in-plane displacements and their non-classical higher-order boundary conditions, von Kármán geometric non-linearity, non-classical couple stress components and the inherent non-linearity of distributed electrostatic pressure on the micro-plate motion. The governing equations of motion, which are clearly derived using Hamilton's principle, are solved through a novel computationally very efficient Galerkin-based reduced order model (ROM) in which all higher-order non-classical boundary conditions are completely satisfied. The present findings are compared and successfully validated by available results in the literature as well as those obtained by three-dimensional finite element simulations carried out using COMSOL Multyphysics. A detailed parametric study is also conducted to illustrate the effects of in-plane displacements, plate aspect ratio, couple stress components and geometric non-linearity on the dynamic instability threshold of the system.

  7. Stress analysis for the candidate of lower end fitting of advanced LWR fuel using FEM

    Lee, S. S.; Moon, Y. C. [Korea University of Technology and Education, Chonan (Korea, Republic of); Kim, H. K. [Korea Nuclear Fuel Company, Taejon (Korea, Republic of)


    The geometric modeling has been conducted for the candidate of advanced LWR fuel using the three-dimensional solid modeler. Then the three-dimensional stress analysis using MSC/NASTRAN has been performed. The evaluation for the mechanical integrity of the candidate has been performed based on the stress distribution obtained from the finite elements analysis.

  8. Stress Resultant Based Elasto-Viscoplastic Thick Shell Model

    Pawel Woelke


    Full Text Available The current paper presents enhancement introduced to the elasto-viscoplastic shell formulation, which serves as a theoretical base for the finite element code EPSA (Elasto-Plastic Shell Analysis [1–3]. The shell equations used in EPSA are modified to account for transverse shear deformation, which is important in the analysis of thick plates and shells, as well as composite laminates. Transverse shear forces calculated from transverse shear strains are introduced into a rate-dependent yield function, which is similar to Iliushin's yield surface expressed in terms of stress resultants and stress couples [12]. The hardening rule defined by Bieniek and Funaro [4], which allows for representation of the Bauschinger effect on a moment-curvature plane, was previously adopted in EPSA and is used here in the same form. Viscoplastic strain rates are calculated, taking into account the transverse shears. Only non-layered shells are considered in this work.

  9. Genome-wide gene-based analysis suggests an association between Neuroligin 1 (NLGN1) and post-traumatic stress disorder

    Kilaru, V; Iyer, S V; Almli, L M; Stevens, J S; Lori, A; Jovanovic, T; Ely, T D; Bradley, B; Binder, E B; Koen, N; Stein, D J; Conneely, K N; Wingo, A P; Smith, A K; Ressler, K J


    Post-traumatic stress disorder (PTSD) develops in only some people following trauma exposure, but the mechanisms differentially explaining risk versus resilience remain largely unknown. PTSD is heritable but candidate gene studies and genome-wide association studies (GWAS) have identified only a modest number of genes that reliably contribute to PTSD. New gene-based methods may help identify additional genes that increase risk for PTSD development or severity. We applied gene-based testing to GWAS data from the Grady Trauma Project (GTP), a primarily African American cohort, and identified two genes (NLGN1 and ZNRD1-AS1) that associate with PTSD after multiple test correction. Although the top SNP from NLGN1 did not replicate, we observed gene-based replication of NLGN1 with PTSD in the Drakenstein Child Health Study (DCHS) cohort from Cape Town. NLGN1 has previously been associated with autism, and it encodes neuroligin 1, a protein involved in synaptogenesis, learning, and memory. Within the GTP dataset, a single nucleotide polymorphism (SNP), rs6779753, underlying the gene-based association, associated with the intermediate phenotypes of higher startle response and greater functional magnetic resonance imaging activation of the amygdala, orbitofrontal cortex, right thalamus and right fusiform gyrus in response to fearful faces. These findings support a contribution of the NLGN1 gene pathway to the neurobiological underpinnings of PTSD.

  10. Home practice in Mindfulness-Based Cognitive Therapy and Mindfulness-Based Stress Reduction: A systematic review and meta-analysis of participants' mindfulness practice and its association with outcomes.

    Parsons, Christine E; Crane, Catherine; Parsons, Liam J; Fjorback, Lone Overby; Kuyken, Willem


    Mindfulness-Based Cognitive Therapy (MBCT) and Mindfulness-Based Stress Reduction (MBSR) emphasize the importance of mindfulness practice at home as an integral part of the program. However, the extent to which participants complete their assigned practice is not yet clear, nor is it clear whether this practice is associated with positive outcomes. For this systematic review and meta-analysis, searches were performed using Scopus and PubMed for studies published through to the end of 2015, reporting on formal home practice of mindfulness by MBSR or MBCT participants. Across 43 studies (N = 1427), the pooled estimate for participants' home practice was 64% of the assigned amount, equating to about 30 minutes per day, six days per week [95% CI 60-69%]. There was substantial heterogeneity associated with this estimate. Across 28 studies (N = 898), there was a small but significant association between participants' self-reported home practice and intervention outcomes (r = 0·26, 95% CI 0·19,-0·34). MBSR and MBCT participants report completing substantial formal mindfulness practice at home over the eight-week intervention, albeit less than assigned amounts. There is a small but significant association between the extent of formal practice and positive intervention outcomes for a wide range of participants. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Mapping residual stresses in PbWO$_{4}$ crystals using photo-elastic analysis

    Lebeau, Michel; Majni, G; Paone, N; Pietroni, P; Rinaldi, D


    Large scintillating crystals are affected by internal stresses induced by the crystal growth temperature gradient remanence. Cutting boules (ingots) into finished crystal shapes allows for a partial tension relaxation but residual stresses remain the main cause of breaking. Quality control of residual stresses is essential in the application of Scintillating Crystals to high-energy physics calorimeters (e.g. CMS ECAL at CERN LHC). In this context the industrial process optimisation towards stress reduction is mandatory. We propose a fast technique for testing samples during the production process in order to evaluate the residual stress distribution after the first phases of mechanical processing. We mapped the stress distribution in PbWO/sub 4/slabs cut from the same production boule. The analysis technique is based on the stress intensity determination using the photo-elastic properties of the samples. The stress distribution is mapped in each sample. The analysis shows that there are regions of high residu...




    A stress analysis software based on MATLAB, Graphic user interface (GUI) has been developed. The developed software can be used to estimate load on a wing and to compute the stresses at any point along the span of the wing of a given aircraft. The generalized formulation allows performing stress analysis even for a multispar (multicell) wing. The software is expected to be a useful tool for effective teaching learning process of courses on aircraft structures and aircraft structural design.




    Full Text Available A stress analysis software based on MATLAB, Graphic user interface (GUI has been developed. The developed software can be used to estimate load on a wing and to compute the stresses at any point along the span of the wing of a given aircraft. The generalized formulation allows performing stress analysis even for a multispar (multicell wing. The software is expected to be a useful tool for effective teaching learning process of courses on aircraft structures and aircraft structural design.

  14. Autobiographical episodic memory-based training for the treatment of mood, anxiety and stress-related disorders: A systematic review and meta-analysis.

    Hitchcock, Caitlin; Werner-Seidler, Aliza; Blackwell, Simon E; Dalgleish, Tim


    We review evidence for training programmes that manipulate autobiographical processing in order to treat mood, anxiety, and stress-related disorders, using the GRADE criteria to judge evidence quality. We also position the current status of this research within the UK Medical Research Council's (2000, 2008) framework for the development of novel interventions. A literature search according to PRISMA guidelines identified 15 studies that compared an autobiographical episodic memory-based training (AET) programme to a control condition, in samples with a clinician-derived diagnosis. Identified AET programmes included Memory Specificity Training (Raes, Williams, & Hermans, 2009), concreteness training (Watkins, Baeyens, & Read, 2009), Competitive Memory Training (Korrelboom, van der Weele, Gjaltema, & Hoogstraten, 2009), imagery-based training of future autobiographical episodes (Blackwell & Holmes, 2010), and life review/reminiscence therapy (Arean et al., 1993). Cohen's d was calculated for between-group differences in symptom change from pre- to post-intervention and to follow-up. We also completed meta-analyses for programmes evaluated across multiple studies, and for the overall effect of AET as a treatment approach. Results demonstrated promising evidence for AET in the treatment of depression (d=0.32), however effect sizes varied substantially (from -0.18 to 1.91) across the different training protocols. Currently, research on AET for the treatment of anxiety and stress-related disorders is not yet at a stage to draw firm conclusions regarding efficacy as there were only a very small number of studies which met inclusion criteria. AET offers a potential avenue through which low-intensity treatment for affective disturbance might be offered. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Mindfulness Based Stress Reduction: effect on emotional distress in diabetes

    Young, Laura A; Cappola, Anne R; Baime, Michael J


    Psychological distress is common in patients with diabetes. Little is known about the impact of Mindfulness Based Stress Reduction (MBSR), a non-traditional, cognitive behavioural intervention designed to improve stress management skills, in patients with diabetes. The purpose of this retrospective analysis was to evaluate the impact of MBSR training on mood states in 25 individuals with diabetes. All participants completed the Profile of Mood States Short Form (POMS-SF) at baseline and following eight weeks of MBSR. Overall psychological distress measured by the total mood score (TMS) and six subscales – including tension/anxiety, depression/dejection, anger/hostility, fatigue/inertia, confusion/bewilderment and vigour/activity – were assessed. Overall mood, measured by the TMS, as well as all subscale mood measurements improved significantly from baseline following MBSR training. Compared to population means, those with diabetes had higher distress at baseline and similar levels of distress following MBSR training. The primary reason participants reported for enrolling in the MBSR course was to improve stress management skills. It was concluded that MBSR training is a promising, group-based intervention that can be used to decrease psychological distress in individuals with diabetes who perceive a need for training in stress management. PMID:28781569

  16. Stress analysis for wall structure in mobile hot cell design

    Bahrin, Muhammad Hannan, E-mail:; Rahman, Anwar Abdul, E-mail:; Hamzah, Mohd Arif, E-mail:; Mamat, Mohd Rizal; Azman, Azraf; Hasan, Hasni [Prototype and Plant Development Centre, Technical Services Division, Malaysian Nuclear Agency (Malaysia)


    Malaysian Nuclear Agency is developing a Mobile Hot Cell (MHC) in order to handle and manage Spent High Activity Radioactive Sources (SHARS) such as teletherapy heads and irradiators. At present, there are only two units of MHC in the world, in South Africa and China. Malaysian Mobile Hot cell is developed by Malaysian Nuclear Agency with the assistance of IAEA expert, based on the design of South Africa and China, but with improved features. Stress analysis has been performed on the design in order to fulfil the safety requirement in operation of MHC. This paper discusses the loading analysis effect from the sand to the MHC wall structure.

  17. Calculation and analysis of stress in strata under gob pillars

    杨敬轩; 刘长友; 于斌; 吴锋锋


    Aiming at the difficulty in stress analysis for strata under pillars with actual bearing conditions, an approach was proposed to apply multi-sectional linear approximation to the characteristic curves of pillar loads, and stress of strata was calculated under pillars with linear load by calculation method for uniform load. This approach leads to a rapid analyzing method for strata stress under pillars with any form of loads. Through theoretical analysis, strata stress expressions for pillars under linear bearing conditions are obtained. In addition, two concepts, stress increase factor and stress factor, are proposed for the approximate analysis of strata stress by uniform load approximation method. It is also found that the stress increase factor of strata is related to the strata stress factor and the ratio of the minimum load on the pillar’ two ends to the maximum one;and the distribution features of stress factors and the sizes of their influencing areas in strata influenced by overlying pillars are obtained. Combining with the gob pillar conditions of Jurassic coal seam in Tongxin Coal Mine, it is demonstrated that the results obtained by stress distribution analysis of the strata stress in non-influencing areas of pillars with linear bearing through uniform load approximation are in basic accordance with the results obtained for pillars under linear bearing condition. Therefore, it is feasible and accurate to calculate stress in non-influencing area in strata under pillars with linear bearing condition by uniform load calculation method.

  18. Mindfulness-based stress reduction and physiological activity during acute stress: a randomized controlled trial

    Nyklicek, I.; Mommersteeg, P.M.; Beugen, S. van; Ramakers, C.; Boxtel, G.J. Van


    OBJECTIVE: The aim was to examine the effects of a Mindfulness-Based Stress Reduction (MBSR) intervention on cardiovascular and cortisol activity during acute stress. METHOD: Eighty-eight healthy community-dwelling individuals reporting elevated stress levels were randomly assigned to the MBSR proto

  19. Identification of bovine leukemia virus tax function associated with host cell transcription, signaling, stress response and immune response pathway by microarray-based gene expression analysis

    Arainga Mariluz


    , respectively, after transfecting Tax proteins into bovine cells and human HeLa cells. Conclusion A comparative analysis of wild-type and mutant Tax proteins indicates that Tax protein exerts a significant impact on cellular functions as diverse as transcription, signal transduction, cell growth, stress response and immune response. Importantly, our study is the first report that shows the extent to which BLV Tax regulates the innate immune response.

  20. Smartphone-Based Self-Assessment of Stress in Healthy Adult Individuals

    Þórarinsdóttir, Helga; Kessing, Lars Vedel; Faurholt-Jepsen, Maria


    BACKGROUND: Stress is a common experience in today's society. Smartphone ownership is widespread, and smartphones can be used to monitor health and well-being. Smartphone-based self-assessment of stress can be done in naturalistic settings and may potentially reflect real-time stress level....... OBJECTIVE: The objectives of this systematic review were to evaluate (1) the use of smartphones to measure self-assessed stress in healthy adult individuals, (2) the validity of smartphone-based self-assessed stress compared with validated stress scales, and (3) the association between smartphone-based self......-assessed stress and smartphone generated objective data. METHODS: A systematic review of the scientific literature was reported and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. The scientific databases PubMed, PsycINFO, Embase, IEEE, and ACM...

  1. Poro-thermoelastic borehole stress analysis for determination of the in situ stress and rock strength

    Tao, Qingfeng; Ghassemi, Ahmad [Texas A and M University, College Station, TX 77843 (United States)


    The in situ stress state and rock strength are key parameters in a number of problems concerning petroleum and geothermal reservoir development, particularly in well stimulation and optimum wellbore trajectory analyses. Inversion techniques utilized to determine the in situ stress and rock strength based on the observation of borehole failure and its analysis often assume elastic rock behavior. However, when drilling through high-pressure and high-temperature rocks, coupled poro-thermo-mechanical processes result in a time-dependent stress and pore pressure distribution around the borehole. In this work, the poro-thermoelastic effects on borehole failure are studied and their impact on wellbore stability and the estimations of the in situ maximum horizontal stress and rock strength using wellbore failure data are investigated. It is shown that coupled poro-thermo-mechanical effects influence both failure mode and potential. Also, when considering shear failure, neglecting heating and cooling effects will underestimate and overestimate rock strength, respectively. Therefore, for accurate assessment of wellbore stability and inversion of wellbore failure data, poroelastic and thermal factors should be considered. (author)

  2. Pilots’occupational stress analysis model based on factor analysis%基于因子分析的引航员职业压力分析模型

    骆杭飞; 肖英杰; 周伟; 白响恩


    To provide some measures for reducing the pilots’occupational stress,the factor analysis is applied to the analysis on the occupational stress. The influencing factors resulting in the pilots’occupa-tional stress are analyzed in the nature of work,job involvement,job fatigue and job performance of pi-lots. The corresponding index system model is constructed. Data are collected by questionnaires,and the main stress factors are determined by SPSS 20. 0. According to the main factors,the strategies are estab-lished to reduce the adverse effects caused by stress factors. It provides reference for the relief of pilots’ psychological stress through the thought of dimension reduction of factor analysis.%为提出减轻引航员职业压力的措施,将因子分析运用到引航员职业压力分析中.从引航员工作性质、工作投入、工作疲劳和工作绩效入手,分析造成引航员职业压力的影响因子,构建引航员职业压力指标体系模型.通过问卷调查采集数据,利用SPSS 20.0确定引起引航员职业压力的主要因子.依据主要因子,制定降低由这些因子产生的不良影响的策略.利用因子分析的降维思想,可为减轻引航员心理压力提供参考.

  3. Experimental Finite Element Approach for Stress Analysis

    Ahmet Erklig


    Full Text Available This study aims to determining the strain gauge location points in the problems of stress concentration, and it includes both experimental and numerical results. Strain gauges were proposed to be positioned to corresponding locations on beam and blocks to related node of elements of finite element models. Linear and nonlinear cases were studied. Cantilever beam problem was selected as the linear case to approve the approach and conforming contact problem was selected as the nonlinear case. An identical mesh structure was prepared for the finite element and the experimental models. The finite element analysis was carried out with ANSYS. It was shown that the results of the experimental and the numerical studies were in good agreement.

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

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


    relationships. The most frequent topic of relaxation tweets was rest & vacation, followed by nature and water. When we applied the classifiers to the cities dataset, the proportion of stress tweets in New York and San Diego was substantially higher than that in Los Angeles and San Francisco. In addition, we found that characteristic expressions of stress and relaxation varied for each city based on its geolocation. Conclusions This content analysis and infodemiology study revealed that Twitter, when used in conjunction with natural language processing techniques, is a useful data source for understanding stress and stress management strategies, and can potentially supplement infrequently collected survey-based stress data. PMID:28611016

  5. Yield stress fluids slowly yield to analysis

    Bonn, D.; Denn, M.M.


    We are surrounded in everyday life by yield stress fluids: materials that behave as solids under small stresses but flow like liquids beyond a critical stress. For example, paint must flow under the brush, but remain fixed in a vertical film despite the force of gravity. Food products (such as mayon

  6. Photoelastic analysis of stresses transmitted by complete dentures lined with hard or soft liners.

    Pereira, Izabella P; Consani, Rafael L X; Mesquita, Marcelo F; Nóbilo, Mauro A A


    Stresses transmitted on the alveolar bone ridge by lined conventional complete mandibular dentures can decrease the bone absorption level. The aim of this in vitro study was to evaluate the stresses induced on the alveolar bone ridge of lined conventional complete mandibular dentures by using photoelastic analysis. One maxillary and three mandibular conventional dentures were developed for the following treatments: 1 - Unlined denture (control), 2 - Denture lined with resin-based material, and 3 - Denture lined with silicone-based material. The photoelastic analysis took place with the dentures in the position of maximum intercuspation, and the mandibular photoelastic models were axially loaded with 10 kgf (98 N). Unlined denture (control) presented stresses along the model, especially on the anterior and left lateral sides with less stresses on the right side. On the left lateral side, the denture base lined with resin-based material demonstrated similar stresses to that of the control; however, lower stresses occurred in the premolar and retromolar regions. Denture bases lined with silicone-based material showed decreased fringe orders and homogeneous distribution of induced stresses. Both lined dentures exhibited lower stresses when compared to unlined dentures. Silicone-based material provided a more homogeneous distribution of stresses. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The Research of Welding Residual Stress Based Finite Element Method

    Qinghua Bai


    Full Text Available Welding residual stress was caused by local heating during the welding process, tensile residual stress reduce fatigue strength and corrosion resistance, Compressive residual stress decreases stability limit. So it will produce brittle fracture, reduce working life and strength of workpiece; Based on the simulation of welding process with finite element method, calculate the welding temperature field and residual stress, and then measure residual stress in experiments, So as to get the best welding technology and welding parameters, to reduce welding residual stress effective, it has very important significance.

  8. Genetic diversity analysis based on molecular marker and quantitative traits of the response of different tomato (Lycopersicon esculentum Mill. cultivars to drought stress

    Metwali Ehab M.R.


    Full Text Available The drought tolerance of tomato (Lycopersicon esculentum Mill. is a trait needing urgent improvement due to recent climate changes and limited water availability. We therefore conducted a greenhouse screening experiment to identify tomato cultivars with improved drought tolerance. Several sensitivity and tolerance indices were computed based on morphological markers. With the aim of establishing a correlation to these markers, a total of 16 inter-simple sequence repeat (ISSR primers were used, the genetic diversity among cultivars was elucidated and clustering the cultivars into groups based on their molecular profiles was performed. The obtained results indicated that selection indices, such as geometric mean productivity (GMP, mean productivity (MP, tolerance index (TOL,and stress tolerance index (STI, represented suitable indices for screening the drought tolerance of tomato cultivars. An interesting correlation of the ISSR analyses to these morphological findings was established according to 83 detectable fragments derived from 10 primers. The highest value of the effective multiplex ratio (EMR and marker index (MI was detected for primer INC7 followed by INC1. Based on Jaccard's similarity coefficients, the genetic distance of the genotypes varied from 0.702 to 0.942 with a mean value of 0.882. The results showed a clear-cut separation of the 15 tomato cultivars due to their genetic variability, making them a valuable genetic source for their incorporation into potential breeding programs. Molecular data were in good agreement with the results as regards selection indices, and both of them will be useful tools for improvement of the tomato germplasm.

  9. A Stress Vector-Based Constitutive Model for Cohesionless Soil( Ⅱ )-Application

    史宏彦; 谢定义; 白琳


    The stress vector-based constitutive model for cohesionless soil, proposed by SHI Hong-yan et al., was applied to analyze the deformation behaviors of materials subjected to various stress paths. The result of analysis shows that the constitutive model can capture well the main deformation behavior of cohesionless soil, such as stress-strain nonlinearity,hardening property, dilatancy , stress path dependency, non- coaxiality between the principal stress and the principal strain increment directions, and the coupling of mean effective and deviatoric stress with deformation. In addition, the model can also take into account the rotation of principal stress axes and the influence of intermediate principal stress on deformation and strength of soil simultaneously. The excellent agreement between the predicted and measured behavior indicates the comprehensive applicability of the model.

  10. Stress analysis in the Gjilan Municipality (Kosovo

    Nehat Rrudhani


    Full Text Available During this scientific research, my main objective is to analyze and give an overview of the factual situation in Gjilan Municipality (Kosovo. The dynamics of life shift people towards stressful situations. Nowadays stress is a very much discussed issue, while we do have little knowledge about the causes of stress, its circumstances, its management. Stress affects negatively people’s health by disordering the immune system. When a man has stress, he/she has disorders in connection with the following symptoms: saliva flows slowly, increased eyelids, shrinking of blood vessels, shiver and sweat, deep breathing, quick heart beats, problems with food digestion and an increased blood tension.

  11. Stress-based Variable-inductor for Electronic Ballasts

    Zhang, Lihui; Xia, Yongming; Lu, Kaiyuan


    presents a new stress-based variable inductor to control inductance using the inverse magnetostrictive effect of a magnetostrictive material. The stress can be applied by a piezoelectrical material, and thus a voltage-controlled variable inductor can be realized with zero-power consumption. The new stress...

  12. A yield criterion based on mean shear stress

    Emmens, W.C.; Boogaard, van den A.H.


    This work investigates the relation between shear stress and plastic yield considering that a crystal can only deform in a limited set of directions. The shear stress in arbitrary directions is mapped for some cases showing relevant differences. Yield loci based on mean shear stress are con- structe

  13. Stress analysis of electrostrictive material with an elliptic defect

    Jiang; Quan; (蒋泉); Kuang; Zhenbang; (匡震邦)


    It is shown that the constitutive equation and electric body force used to discuss the stress analysis of electrostrictive material in some previous literature are not appropriate. This paper presents the corrected stress solution for the infinite plane with an insulated elliptic hole under an applied electrical field. The numerical result obtained for the PMN material constants show that the stress near the end of the narrow elliptic hole is the tensile stress.

  14. Design and analysis of Stress on Thick Walled Cylinder with and with out Holes



    Full Text Available The conventional elastic analysis of thick walled cylinders to final radial & hoop stresses is applicable for the internal pressures up to yield strength of material. The stress is directly proportional to strain up to yield point Beyond elastic point, particularly in thick walled cylinders. The operating pressures are reduced or the material properties are strengthened. There is no such existing theory for the stress distributions around radial holes under impact of varying internal pressure. Present work puts thrust on this area and relation between pressure and stress distribution is plotted graphically based on observations. Here focus is on pure mechanical analysis & hence thermal, effects are not considered. The thick walled cylinders with a radial cross-hole ANSYS Macro program employed to evaluate the fatigue life of vessel. Stresses that remain in material even after removing applied loads are known as residual stresses. These stresses occur only when material begins to yield plastically. Residual stresses can be present in any mechanical structure because of many causes. Residual stresses may be due to the technological process used to make the component. Manufacturing processes lead to plastic deformation. Elasto plastic analysis with bilinear kinematic hardening material is performed to know the effect of hole sizes. It is observed that there are several factors which influence stress intensity factors. The Finite element analysis is conducted using commercial solvers ANSYS & CATIA. Theoretical formulae based results are obtained from MATLAB programs. The results are presented in form of graphs and tables.

  15. Effect of jaw opening on the stress pattern in a normal human articular disc: finite element analysis based on MRI images.

    Li, Qihong; Ren, Shuang; Ge, Cheng; Sun, Haiyan; Lu, Hong; Duan, Yinzhong; Rong, Qiguo


    Excessive compressive and shear stresses are likely related to condylar resorption and disc perforation. Few studies have reported the disc displacement and deformation during jaw opening. The aim of this study was to analyze stress distribution in a normal articular disc during the jaw opening movement. Bilateral MRI images were obtained from the temporomandibular joint of a healthy subject for the jaw opening displacement from 6 to 24 mm with 1 mm increments. The disc contour for the jaw opening at 6 mm was defined as the reference state, and was used to establish a two dimensional finite element model of the disc. The contours of the disc at other degrees of jaw opening were used as the displacement loading. Hyperelastic material models were applied to the anterior, intermediate and posterior parts of the disc. Stress and strain trajectories were calculated to characterize the stress/strain patterns in the disc. Both the maximum and minimum principal stresses were negative in the intermediate zone, therefore, the intermediate zone withstood mainly compressive stress. On the contrary, the maximum and minimum principal stresses were most positive in the anterior and posterior zones, which meant that the anterior and posterior bands suffered higher tensile stresses. The different patterns of stress trajectories between the intermediate zone and the anterior and posterior bands might be attributed to the effect of fiber orientation. The compression of the intermediate zone and stretching of the anterior and posterior bands caused high shear deformation in the transition region, especially at the disc surfaces. The stress and strain remained at a reasonable level during jaw opening, indicating that the disc experiences no injury during functional opening movements in a healthy temporomandibular joint.

  16. Optimal Design of Multiple Stresses Accelerated Life Test Plan Based on Transforming the Multiple Stresses to Single Stress

    GAO Liang; CHEN Wenhua; QIAN Ping; PAN Jun; HE Qingchuan


    For planning optimum multiple stresses accelerated life test plans, a commonly followed guiding principle is that all parameters of the life-stress relationship should be estimated, and the number of the stress level combinations must be no less than the number of parameters of the life-stress relationship. However, the general objective of an accelerated life test(ALT) is to assess thep-th quantile of the product life distribution under normal stress. For this objective,estimating all model parameters is not necessary, and this will increase the cost of test. Based on the theoretical conclusion that the stress level combinations of the optimum multiple stresses ALT plan locate on a straight line through the origin of coordinate, it is proposed that a design idea of planning the optimum multiple stresses ALT plan through transforming the problem of designing an optimum multiple stresses ALT plan to designing an optimum single stress ALT plan. Moreover, a method of planning the optimum multiple stresses ALT plan which can avoid estimating all model parameters is established. An example shows that, the proposed plan which only has two stress level combinations could achieve an accuracy no less than the traditional plan, and save the test time and cost on one stress level combination at least; when the actual product life is less than the design value, even the deviation of the model initial parameters value is up to 20%, the variance of the estimation of thep-th quantile of the proposed plan is still smaller than the traditional plans approximately 25%. A design method is provided for planning the optimum multiple stresses ALT which uses the statistical optimum degenerate test plan as the optimum multiple stresses accelerated life test plan.

  17. New Finite Elements in Shear Stress Analysis of Saint Venant′s Torsional Loaded Beam Structures

    J. Brnic; G. Turkalj


    Recent engineering design as well as material processing on the optimization procedure are based and computeroriented. Finite element stress and sensitivity analysis are the most important things in such modern determinationof optimal solution. According

  18. contact stress analysis of involute spur gear by finite element method


    be applied for gear design of high load carrying capacity effectively. ... these reasons FEM based contact stress analysis has been ... computational advantage the number of teeth of pinion and gear are ... Complex forces and moments are ...

  19. RGB photoelasticity applied to the analysis of membrane residual stress in glass

    Ajovalasit, A.; Petrucci, G.; Scafidi, M.


    The measurement of residual stresses is of great relevance in the glass industry. The analysis of residual stress in glass is usually made by photoelastic methods because glass is a photoelastic material. This paper considers the determination of membrane residual stresses in glass plates by automatic digital photoelasticity in white light (RGB photoelasticity). The proposed method is applied to the analysis of membrane residual stresses in some tempered glass. The proposed method can effectively replace manual methods based on the use of white light, which are currently provided by some technical standards.

  20. Intrinsic stress analysis of sputtered carbon film

    Liqin Liu; Zhanshan Wang; Jingtao Zhu; Zhong Zhang; Moyan Tan; Qiushi Huang; Rui Chen; Jing Xu; Lingyan Chen


    Intrinsic stresses of carbon films deposited by direct current (DC) magnetron sputtering were investigated.The bombardments of energetic particles during the growth of films were considered to be the main reason for compressive intrinsic stresses.The values of intrinsic stresses were determined by measuring the radius of curvature of substrates before and after film deposition.By varying argon pressure and target-substrate distance,energies of neutral carbon atoms impinging on the growing films were optimized to control the intrinsic stresses level.The stress evolution in carbon films as a function of film thickness was investigated and a void-related stress relief mechanism was proposed to interpret this evolution.

  1. Stress Analysis and Calculation of Flow Interruption Capability Test Loop

    FENG; Bo; QI; Xiao-guang; CHENG; Dao-xi


    <正>A stress-analysis and calculation has been done for the flow interruption capability test loop (Fig. 1). In the design condition, the test loop is operated on 350 ℃ and 20MPa. By reasonably simplifying and modeling, a stress-analysis program named Triflex was used to analyze the piping stress and optimize the piping supports, which meet the compliance. The work will provide the necessary basis for the construction of the loop and operation security.

  2. Microbial stress priming: a meta-analysis.

    Andrade-Linares, Diana R; Lehmann, Anika; Rillig, Matthias C


    Microbes have to cope with complex and dynamic environments, making it likely that anticipatory responses provide fitness benefits. Mild, previous stressors can prepare microbes (stress priming) to further and potentially damaging stressors (triggering). We here quantitatively summarize the findings from over 250 trials of 34 studies including bacteria and fungi, demonstrating that priming to stress has a beneficial impact on microbial survival. In fact, survival of primed microbes was about 10-fold higher compared with that in non-primed microbes. Categorical moderators related to microbial taxonomy and the kind of stress applied as priming or as triggering revealed significant differences of priming effect size among 14 different microbial species, 6 stress categories and stressor combination. We found that priming by osmotic, physiological and temperature stress had the highest positive effect sizes on microbial response. Cross-protection was evident for physiological, temperature and pH stresses. Microbes are better prepared against triggering by oxidative, temperature and osmotic stress. Our finding of an overall positive mean effect of priming regardless of the microbial system and particular stressor provides unprecedentedly strong evidence of the broad ecological significance of microbial stress priming. These results further suggest that stress priming may be an important factor in shaping microbial communities.

  3. Effect of jaw opening on the stress pattern in a normal human articular disc: finite element analysis based on MRI images

    Li, Qihong; Ren, Shuang; Ge, Cheng; Sun, Haiyan; Lu, Hong; Duan, Yinzhong; Rong, Qiguo


    .... Few studies have reported the disc displacement and deformation during jaw opening. The aim of this study was to analyze stress distribution in a normal articular disc during the jaw opening movement...

  4. [Thermo-elastic stress analysis of human bones].

    Krüger-Franke, M; Heiland, A; Plitz, W; Refior, H J


    The Thermoelastic Stress Analysis (THESA) is a widely used procedure in motorcar- and airplane engineering. This study investigated the reliability of THESA for stress analysis of human bone. A human femur was cyclic stressed and the resulting stress pattern was scanned from the surface of the bone by means of the thermoelastic stress measuring instrument SPATE 9000. To proof whether the scan of SPATE 9000 is equivalent to the stress distribution of human femur surface, strain gauges are used to control the results at two different regions of the femur diaphysis under equal but static conditions. It could be shown, that both measuring methods lead to corresponding results of stress pattern on human femur surface.

  5. Spherical nanoindentation stress-strain analysis, Version 1


    Nanoindentation is a tool that allows the mechanical response of a variety of materials at the nano to micron length scale to be measured. Recent advances in spherical nanoindentation techniques have allowed for a more reliable and meaningful characterization of the mechanical response from nanoindentation experiments in the form on an indentation stress-strain curve. This code base, Spin, is written in MATLAB (The Mathworks, Inc.) and based on the analysis protocols developed by S.R. Kalidindi and S. Pathak [1, 2]. The inputs include the displacement, load, harmonic contact stiffness, harmonic displacement, and harmonic load from spherical nanoindentation tests in the form of an Excel (Microsoft) spreadsheet. The outputs include indentation stress-strain curves and indentation properties as well their variance due to the uncertainty of the zero-point correction in the form of MATLAB data (.mat) and figures (.png). [1] S. Pathak, S.R. Kalidindi. Spherical nanoindentation stress–strain curves, Mater. Sci. Eng R-Rep 91 (2015). [2] S.R. Kalidindi, S. Pathak. Determination of the effective zero-point and the extraction of spherical nanoindentation stress-strain curves, Acta Materialia 56 (2008) 3523-3532.

  6. Local stress analysis in devices by FIB

    Kregting, R.; Gielen, A.W.J.; Driel, W. van; Alkemade, P.; Miro, H.; Kamminga, J.-D.


    Intrinsic stresses in bondpads may lead to early failure of IC's. In order to determine the intrinsic stresses in semiconductor structures, a new procedure is set up. This procedure is a combined experimental/numerical approach which consists of the following steps: First, a conductive gold layer (2

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

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


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

  8. Methodological Aspects Regarding The Organizational Stress Analysis

    Irimie, Sabina; Pricope (Muntean), Luminiţa Doina; Pricope, Sorin; Irimie, Sabin Ioan


    This work presents a research of methodology in occupational stress analyse in the educational field, as a part of a larger study. The objectives of the work are in finding accents in existence of significant relations between stressors and effects, meaning the differences between the indicators of occupational stress to teaching staff in primary and gymnasium school, taking notice of each specific condition: the institution as an entity, the working community, the discipline he/she is teaching others, the geographic and administrative district (urban/rural) and the quantification of stress level.

  9. Mechanism-based bioanalysis and biomarkers for hepatic chemical stress.

    Antoine, D J; Mercer, A E; Williams, D P; Park, B K


    Adverse drug reactions, in particular drug-induced hepatotoxicity, represent a major challenge for clinicians and an impediment to safe drug development. Novel blood or urinary biomarkers of chemically-induced hepatic stress also hold great potential to provide information about pathways leading to cell death within tissues. The earlier pre-clinical identification of potential hepatotoxins and non-invasive diagnosis of susceptible patients, prior to overt liver disease is an important goal. Moreover, the identification, validation and qualification of biomarkers that have in vitro, in vivo and clinical transferability can assist bridging studies and accelerate the pace of drug development. Drug-induced chemical stress is a multi-factorial process, the kinetics of the interaction between the hepatotoxin and the cellular macromolecules are crucially important as different biomarkers will appear over time. The sensitivity of the bioanalytical techniques used to detect biological and chemical biomarkers underpins the usefulness of the marker in question. An integrated analysis of the biochemical, molecular and cellular events provides an understanding of biological (host) factors which ultimately determine the balance between xenobiotic detoxification, adaptation and liver injury. The aim of this review is to summarise the potential of novel mechanism-based biomarkers of hepatic stress which provide information to connect the intracellular events (drug metabolism, organelle, cell and whole organ) ultimately leading to tissue damage (apoptosis, necrosis and inflammation). These biomarkers can provide both the means to inform the pharmacologist and chemist with respect to safe drug design, and provide clinicians with valuable tools for patient monitoring.

  10. How Can Stress Be Controlled in Endodontically Treated Teeth? A 3D Finite Element Analysis

    İhsan Yıkılgan


    Full Text Available The aim of this study was to analyze the stresses that develop by oblique and vertical forces in endodontically treated maxillary second premolars that were restored with resin composite. Additionally, in our study the effects of the different restorative approaches and use of different base materials on stress formation were analyzed using three-dimensional finite element stress analysis. For restoration, the models representing both cusp capping, palatinal cusp capping, standard MOD restoration, and use of woven fiber in occlusal part were prepared. In all models, oblique forces caused more stress than did vertical forces. Materials with low elastic moduli cause high amounts of stress, whereas materials with elastic moduli similar to that of dental tissues cause low amounts of stress. Additional approaches such as cusp capping, functional cusp capping, and woven fiber use do not affect stress formation on the tooth after endodontic treatment.

  11. Contribution of genetic polymorphisms on functional status at very old age: a gene-based analysis of 38 genes (311 SNPs) in the oxidative stress pathway.

    Dato, S; Soerensen, M; Lagani, V; Montesanto, A; Passarino, G; Christensen, K; Tan, Q; Christiansen, L


    Preservation of functional ability is a well-recognized marker of longevity. At a molecular level, a major determinant of the physiological decline occurring with aging is the imbalance between production and accumulation of oxidative damage to macromolecules, together with a decreased efficiency of stress response to avoid or repair such damage. In this paper we investigated the association of 38 genes (311 SNPs) belonging to the pro-antioxidant pathways with physical and cognitive performances, by analyzing single SNP and gene-based associations with Hand Grip strength (HG), Activities of Daily Living (ADL), Walking Speed (WS), Mini Mental State Examination (MMSE) and Composite Cognitive Score (CCS) in a Cohort of 1089 Danish nonagenarians. Moreover, for each gene analyzed in the pro-antioxidant pathway, we tested the influence on longitudinal survival. In the whole sample, nominal associations were found for TXNRD1 variability with ADL and WS, NDUFS1 and UCP3 with HG and WS, GCLC and UCP2 with WS (p<0.05). Stronger associations although not holding the multiple comparison correction, were observed between MMSE and NDUFV1, MT1A and GSTP1 variability (p<0.009). Moreover, we found that association between genetic variability in the pro-antioxidant pathway and functional status at old age is influenced by sex. In particular, most significant associations were observed in nonagenarian females, between HG scores and GLRX and UCP3 variability, between ADL levels and TXNRD1, MMSE and MT1A genetic variability. In males, a borderline statistically significant association with ADL level was found for UQCRFS1 gene. Nominally significant associations in relation to survival were found in the female sample only with SOD2, NDUFS1, UCP3 and TXNRD1 variability, the latter two confirming previous observations reported in the same cohort. Overall, our work supports the evidence that genes belonging to the pro-anti-oxidant pathway are able to modulate physical and cognitive

  12. Residual stresses analysis of friction stir welding using one-way FSI simulation

    Kang, Sung Wook; Jang, Beom Seon [Seoul National University, Seoul (Korea, Republic of); Song, Ha Cheol [Mokpo National University, Muan (Korea, Republic of)


    When certain mechanisms, such as plastic deformations and temperature gradients, occur and are released in a structure, stresses remain because of the shape of the structure and external constraints. These stresses are referred to as residual stresses. The base material locally expands during heating in the welding process. When the welding is completed and cooled to room temperature, the residual stresses are left at nearly the yield strength level. In the case of friction stir welding, the maximum temperature is 80% to 90% of the melting point of the materials. Thus, the residual stresses in the welding process are smaller than those in other fusion welding processes; these stresses have not been considered previously. However, friction stir welding residual stresses are sometimes measured at approximately 70% or above. These residual stresses significantly affect fatigue behavior and lifetime. The present study investigates the residual stress distributions in various welding conditions and shapes of friction stir welding. In addition, the asymmetric feature is considered in temperature and residual stress distribution. Heat transfer analysis is conducted using the commercial computational fluid dynamics program Fluent, and results are used in the finite element structural analysis with the ANSYS Multiphysics software. The calculated residual stresses are compared with experimental values using the X-ray diffraction method.

  13. Web-Based and Mobile Stress Management Intervention for Employees

    Heber, E.; Lehr, D.; Ebert, D. D.


    Background: Work-related stress is highly prevalent among employees and is associated with adverse mental health consequences. Web-based interventions offer the opportunity to deliver effective solutions on a large scale; however, the evidence is limited and the results conflicting. Objective......: This randomized controlled trial evaluated the efficacy of guided Web-and mobile-based stress management training for employees. Methods: A total of 264 employees with elevated symptoms of stress (Perceived Stress Scale-10, PSS-10 >= 22) were recruited from the general working population and randomly assigned......-261= 58.08, Pstress in employees in the long term...

  14. Heat transfer and thermal stress analysis in grooved tubes

    Veysel Özceyhan; Necdet Altuntop


    Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was applied from the external surface of the tube. Energy and governing flow equations were solved using finite difference scheme. Finite element method (FEM) was used to compute the thermal stress fields. Grooving effects on the thermal stress ratio have been discussed. As a result, maximum thermal stress occurs in the case of $p = d$ for all water inlet velocities. The maximum thermal stress ratio positions inside the tube have been indicated as MX for all investigated cases. In the light of the thermal stress values, various designs can be applied to reduce thermal stress in grooved tubes.

  15. 11-cis retinal torsion: A QTAIM and stress tensor analysis of the S1 excited state

    Maza, Julio R.; Jenkins, Samantha; Kirk, Steven R.


    We investigate torsion about the C11-C12 bond mid-point for the S1 state of 11-cis retinal, using a QTAIM and stress tensor analysis. The QTAIM and stress tensor responses to a torsion ±α increase at a faster rate for the preferred direction of torsion though the CI seam. A QTAIM and stress tensor vector-based analysis provides an alternative way of characterising the asymmetry of the S1 potential energy surface. In the vicinity of the CI seam the ellipticity ε attained minimum values. The application of this analysis to molecular rotary motors is briefly discussed.

  16. A Biomechanical Analysis of Patellofemoral Stress Syndrome

    Moss, Robert I.; DeVita, Paul; Dawson, Mary L.


    This study was conducted in order to: a) investigate the relationship of selected anthropometric, strength, and kinematic variables to the incidence of patellofemoral stress syndrome in high school female athletes; and b) develop a predictive equation to screen individuals who may be predisposed to patellofemoral stress syndrome. Twenty-nine subjects were analyzed across nine dependent variables: two anthropometric measures, one strength measure, and six kinematic measures. Heavy subjects and...

  17. 基于流固耦合的垂直轴风机受力分析%Stress Analysis of Vertical Axis Wind Turbine Based on Fluid-Structure Coupling

    丁琳; 郑源; 张福星


    Upon the analysis of fluid-solid coupling,the forces on the blades and spindle of the building integration wind turbine were discussed.Based on an actual project,the one-way fluid-structure coupling method in the structure analysis software ANSYS Workbench was used to calculate and analyze the static stresses of the blades and spindle under the wind speed of 10 m/s and 50 m/s.The results showed that the maximum static stress of the wind turbine blades occurs at the connection between the blades and spindle under different working conditions,and the maximum static stress increases with the increasing of wind speed.The maximum static stress is far less than the yield limit of material,thus it will not destroy the wind turbine blades and spindle structure.The connection between the blades and spindle has the stress concentration phenomenon,and the thickness of the connection area can be increased to prevent fatigue failure.%为了通过流固耦合分析,探讨风机建筑一体化中垂直轴风力机叶片和主轴的受力情况,结合实际工程,在结构分析软件ANSYS Workbench[(11)]中运用单向流固耦合的方法分别对风速是10 m/s和50 m/s时的风机叶片和主轴的静应力进行了计算分析和比较.结果表明:各种工况下,风力机叶片的最大静应力出现在叶片与主轴连接处,风力发电机叶片和主轴的最大静应力随着风速的增加而变大.静应力最高值远小于材料的屈服极限,所以静应力不会使风机叶片和主轴结构产生破坏.叶片与主轴的连接处都出现了应力集中现象,为了防止疲劳破坏,可以适当地加厚叶片和主轴连接处的厚度.

  18. Analysis of TNF-α-induced Leukocyte Adhesion to Vascular Endothelial Cells Regulated by Fluid Shear Stress Using Microfluidic Chip-based Technology

    LI Yuan; YANG De-yu; LIAO Juan; GONG Fang; HE Ping; LIU Bei-zhong


    This paper aims to the research of the impact of fluid shear stress on the adhesion between vascular endothelial cells and leukocyte induced by tumor necrosis factor-α(TNF-α) by microfliudic chip technology. Microfluidic chip was fabricated by soft lithograph;Endothelial microfluidic chip was constructed by optimizing types of the extracellular matrix proteins modified in the microchannel and cell incubation time;human umbilical vein endothelial cells EA.Hy926 lined in the microchannel were exposed to fluid shear stress of 1.68 dynes/cm2 and 8.4 dynes/cm2 respectively. Meanwhile, adhesion between EA.Hy926 cells and leukocyte was induced by TNF-αunder a flow condition. EA. Hy926 cell cultured in the static condition was used as control group. The numbers of fluorescently-labeled leukocyte in microchannel were counted to quantize the adhesion level between EA. Hy926 cells and leukocyte; cell immunofluorescence technique was used to detect the intercellular adhesion molecule (ICAM-1) expression. The constructed endothelial microfluidic chip can afford to the fluid shear stress and respond to exogenous stimulus of TNF-α;compared with the adhesion numbers of leukocyte in control group, adhesion between EA. Hy926 cells exposed to low fluid shear stress and leukocyte was reduced under the stimulus of TNF-α at a concentration of 10 ng/ml(P<0.05);leukocyte adhesion with EA. Hy926 cells exposed to high fluid shear stress was reduced significantly than EA. Hy926 cells in control group and EA.1Hy926 cells exposed to low fluid shear stress ( P<0.01); the regulation mechanism of fluid shear stress to the adhesion between EA. Hy926 cells and leukocyte induced by TNF-αwas through the way of ICAM-1. The endothelial microfluidic chip fabricated in this paper could be used to study the functions of endothelial cell in vitro and provide a new technical platform for exploring the pathophysiology of the related cardiovascular system diseases under a flow environment.

  19. Mindfulness-based stress reduction for posttraumatic stress symptoms: building acceptance and decreasing shame.

    Goldsmith, Rachel E; Gerhart, James I; Chesney, Samantha A; Burns, John W; Kleinman, Brighid; Hood, Megan M


    Mindfulness-based psychotherapies are associated with reductions in depression and anxiety. However, few studies address whether mindfulness-based approaches may benefit individuals with posttraumatic stress symptoms. The current pilot study explored whether group mindfulness-based stress reduction therapy reduced posttraumatic stress symptoms, depression, and negative trauma-related appraisals in 9 adult participants who reported trauma exposure and posttraumatic stress or depression. Participants completed 8 sessions of mindfulness-based stress reduction treatment, as well as pretreatment, midtreatment, and posttreatment assessments of psychological symptoms, acceptance of emotional experiences, and trauma appraisals. Posttraumatic stress symptoms, depression, and shame-based trauma appraisals were reduced over the 8-week period, whereas acceptance of emotional experiences increased. Participants' self-reported amount of weekly mindfulness practice was related to increased acceptance of emotional experiences from pretreatment to posttreatment. Results support the utility of mindfulness-based therapies for posttraumatic stress symptoms and reinforce studies that highlight reducing shame and increasing acceptance as important elements of recovery from trauma.

  20. Proteomic Analysis of Rice Leaves Shows the Different Regulations to Osmotic Stress and Stress Signals

    Lie-Bo Shu; Wei Ding; Jin-Hong Wu; Fang-Jun Feng; Li-Jun Luo; Han-Wei Mei


    Following the idea of partial root-zone drying(PRD)in crop cultivation,the morphological and physiological responses to partial root osmotic stress(PROS)and whole root osmotic stress(WROS)were investigated in rice.WROS caused stress symptoms like leaf rolling and membrane leakage.PROS stimulated stress signals,but did not cause severe leaf damage.By proteomic analysis,a total of 58 proteins showed differential expression after one or both treatments,and functional classification of these proteins suggests that stress signals regulate photosynthesis,carbohydrate and energy metabolism.Two other proteins(anthranilate synthase and submergence-induced nickel-binding protein)were upregulated only in the PROS plants,indicating their important roles in stress resistance.Additionally,more enzymes were involved in stress defense,redox homeostasis,lignin and ethylene synthesis in WROS leaves,suggesting a more comprehensive regulatory mechanism induced by osmotic stress.This study provides new insights into the complex molecular networks within plant leaves involved in the adaptation to osmotic stress and stress signals.

  1. Transcriptomic analysis of barley plant responses to cold stress

    Wu, Jing


    Previous molecular and genomic studies have shown that several group genes in Arabidopsis with various functions are induced by cold stresses, and that various transcription factors are involved in the regulation of stress-inducible genes which contribute to an increase in cold tolerance. Here, we present the results of transcriptome analysis indicating the existence of genes of potential importance to cold stress and multiple low-temperature regulatory pathways in addition to the cold respon...

  2. Investigating role stress in frontline bank employees: A cluster based approach

    Arti Devi


    Full Text Available An effective role stress management programme would benefit from a segmentation of employees based on their experience of role stressors. This study explores role stressor based segments of frontline bank employees towards providing a framework for designing such a programme. Cluster analysis on a random sample of 501 frontline employees of commercial banks in Jammu and Kashmir (India revealed three distinct segments – “overloaded employees”, “unclear employees”, and “underutilised employees”, based on their experience of role stressors. The findings suggest a customised approach to role stress management, with the role stress management programme designed to address cluster specific needs.

  3. 基于弹性地基梁法的沉陷区埋地管道应力变形分析%Stress and Deformation Analysis of Buried Pipelines on Subsidence Area by Base Beam Method of Elastic Foundation

    朱彦鹏; 赵忠忠


    The differential settlement of ground is one of the main reasons which causes pipeline damages. The research and analysis on buried pipelines under effect of settlement usually divide the pipeline crossing area into subsidence area and non-subsidence area.Deflection curve equation of deformation of pipelines in non-subsidence area can be simulated and deduced by using base beam model of elastic foundation.Pipeline deformation on subsidence area can be stimulated into cubic curve equation,and then concluded internal force and displacement equation of pipeline on subsidence area by using boundary conditions.The conclu-sions after combining living examples and analysis indicate that maximum stress of pipelines locates on the interface between subsidence area and non-subsidence area.Maximum stress of pipeline on subsidence area is jointly constituted by axial stress caused by pipeline internal pressure,bending stress and axial stress caused by effect of settlement.As pipeline of non-subsidence area mainly suffers axial stress caused by in-ternal pressure,the effect of internal pressure shall be taken into consideration.The principle influence fac-tors that affect pipeline deformation on subsidence area are settlement volume,width of subsidence area, pipeline diameter and burial depth,among which settlement volume and width of subsidence area have the biggest influence,and burial depth mainly affects axial stress of pipeline,which nearly has no influence on blending stress.%场地的不均匀沉降是导致管道破坏的主要原因之一.对沉陷作用下埋地管道进行研究分析,将管道跨越区分为沉陷区和非沉陷区,非沉陷区管道的变形可利用弹性地基梁模型模拟推导出其挠曲线方程,沉陷区管道变形可模拟成三次曲线方程,然后利用边界条件,求得沉陷区管道的内力和位移方程.最后通过实例分析表明:管道的最大应力位于沉陷区与非沉陷区交界面处,且沉陷区管道的最大应

  4. Design of a Prognostics and Health Management System for Electromechanical Equipment Through Time Stress Analysis

    L(U) Ke-hong; QIU Jing; LIU Guan-jun


    Time stress includes all kinds of environment and operating stress such as shock, vibration, temperature and electric current that the electromechanical system suffers in the manufacture, transport and operating process. In this paper, the conception of time stress and prognostics and health management (PHM) system are introduced. Then, in order to improve the false alarm recognition and fault prediction capabilities of the electromechanical equipment, a novel PHM architecture for electromechanical equipment is put forward based on a built-in test (BIT) system design technology and time stress analysis method. Finally, the structure, the design and implementing method and the functions of each module of this PHM system are described in detail.

  5. Stress and Sliding Stability Analysis of Songlin Rock-Filled Concrete Gravity Dam

    Sundström, Max; Ivedal, Max


    The construction of Songlin rock-filled concrete gravity dam, located in the Yunnan province, China began in the end of 2015. In this master thesis the finite element method (FEM) based software Abaqus has been used to perform a computational analysis on tension stresses, compression stresses and sliding stability for static conditions. One overflow section and one non-overflow section of the dam have been analysed. The results of the analysis have been evaluated by comparing with Chinese sta...

  6. Thermodynamic Modeling and Analysis of Human Stress Response

    Boregowda, S. C.; Tiwari, S. N.


    A novel approach based on the second law of thermodynamics is developed to investigate the psychophysiology and quantify human stress level. Two types of stresses (thermal and mental) are examined. A Unified Stress Response Theory (USRT) is developed under the new proposed field of study called Engineering Psychophysiology. The USRT is used to investigate both thermal and mental stresses from a holistic (human body as a whole) and thermodynamic viewpoint. The original concepts and definitions are established as postulates which form the basis for thermodynamic approach to quantify human stress level. An Objective Thermal Stress Index (OTSI) is developed by applying the second law of thermodynamics to the human thermal system to quantify thermal stress or dis- comfort in the human body. The human thermal model based on finite element method is implemented. It is utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal stress responses under different environmental conditions. An innovative hybrid technique is developed to analyze human thermal behavior based on series of human-environment interaction simulations. Continuous monitoring of thermal stress is demonstrated with the help of OTSI. It is well established that the human thermal system obeys the second law of thermodynamics. Further, the OTSI is validated against the experimental data. Regarding mental stress, an Objective Mental Stress Index (OMSI) is developed by applying the Maxwell relations of thermodynamics to the combined thermal and cardiovascular system in the human body. The OMSI is utilized to demonstrate the technique of monitoring mental stress continuously and is validated with the help of series of experimental studies. Although the OMSI indicates the level of mental stress, it provides a strong thermodynamic and mathematical relationship between activities of thermal and cardiovascular systems of the human body.

  7. Classification and adaptive behavior prediction of children with autism spectrum disorder based upon multivariate data analysis of markers of oxidative stress and DNA methylation

    Melnyk, Stepan; James, S. Jill; Hahn, Juergen


    The number of diagnosed cases of Autism Spectrum Disorders (ASD) has increased dramatically over the last four decades; however, there is still considerable debate regarding the underlying pathophysiology of ASD. This lack of biological knowledge restricts diagnoses to be made based on behavioral observations and psychometric tools. However, physiological measurements should support these behavioral diagnoses in the future in order to enable earlier and more accurate diagnoses. Stepping towards this goal of incorporating biochemical data into ASD diagnosis, this paper analyzes measurements of metabolite concentrations of the folate-dependent one-carbon metabolism and transulfuration pathways taken from blood samples of 83 participants with ASD and 76 age-matched neurotypical peers. Fisher Discriminant Analysis enables multivariate classification of the participants as on the spectrum or neurotypical which results in 96.1% of all neurotypical participants being correctly identified as such while still correctly identifying 97.6% of the ASD cohort. Furthermore, kernel partial least squares is used to predict adaptive behavior, as measured by the Vineland Adaptive Behavior Composite score, where measurement of five metabolites of the pathways was sufficient to predict the Vineland score with an R2 of 0.45 after cross-validation. This level of accuracy for classification as well as severity prediction far exceeds any other approach in this field and is a strong indicator that the metabolites under consideration are strongly correlated with an ASD diagnosis but also that the statistical analysis used here offers tremendous potential for extracting important information from complex biochemical data sets. PMID:28301476

  8. Automated analysis of three-dimensional stress echocardiography

    K.Y.E. Leung (Esther); M. van Stralen (Marijn); M.G. Danilouchkine (Mikhail); G. van Burken (Gerard); M.L. Geleijnse (Marcel); J.H.C. Reiber (Johan); N. de Jong (Nico); A.F.W. van der Steen (Ton); J.G. Bosch (Johan)


    textabstractReal-time three-dimensional (3D) ultrasound imaging has been proposed as an alternative for two-dimensional stress echocardiography for assessing myocardial dysfunction and underlying coronary artery disease. Analysis of 3D stress echocardiography is no simple task and requires considera

  9. Smartphone-Based Self-Assessment of Stress in Healthy Adult Individuals: A Systematic Review

    Þórarinsdóttir, Helga; Kessing, Lars Vedel


    Background Stress is a common experience in today’s society. Smartphone ownership is widespread, and smartphones can be used to monitor health and well-being. Smartphone-based self-assessment of stress can be done in naturalistic settings and may potentially reflect real-time stress level. Objective The objectives of this systematic review were to evaluate (1) the use of smartphones to measure self-assessed stress in healthy adult individuals, (2) the validity of smartphone-based self-assessed stress compared with validated stress scales, and (3) the association between smartphone-based self-assessed stress and smartphone generated objective data. Methods A systematic review of the scientific literature was reported and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. The scientific databases PubMed, PsycINFO, Embase, IEEE, and ACM were searched and supplemented by a hand search of reference lists. The databases were searched for original studies involving healthy individuals older than 18 years, measuring self-assessed stress using smartphones. Results A total of 35 published articles comprising 1464 individuals were included for review. According to the objectives, (1) study designs were heterogeneous, and smartphone-based self-assessed stress was measured using various methods (e.g., dichotomized questions on stress, yes or no; Likert scales on stress; and questionnaires); (2) the validity of smartphone-based self-assessed stress compared with validated stress scales was investigated in 3 studies, and of these, only 1 study found a moderate statistically significant positive correlation (r=.4; P<.05); and (3) in exploratory analyses, smartphone-based self-assessed stress was found to correlate with some of the reported smartphone generated objective data, including voice features and data on activity and phone usage. Conclusions Smartphones are being used to measure self-assessed stress in

  10. Smartphone-Based Self-Assessment of Stress in Healthy Adult Individuals: A Systematic Review.

    Þórarinsdóttir, Helga; Kessing, Lars Vedel; Faurholt-Jepsen, Maria


    Stress is a common experience in today's society. Smartphone ownership is widespread, and smartphones can be used to monitor health and well-being. Smartphone-based self-assessment of stress can be done in naturalistic settings and may potentially reflect real-time stress level. The objectives of this systematic review were to evaluate (1) the use of smartphones to measure self-assessed stress in healthy adult individuals, (2) the validity of smartphone-based self-assessed stress compared with validated stress scales, and (3) the association between smartphone-based self-assessed stress and smartphone generated objective data. A systematic review of the scientific literature was reported and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. The scientific databases PubMed, PsycINFO, Embase, IEEE, and ACM were searched and supplemented by a hand search of reference lists. The databases were searched for original studies involving healthy individuals older than 18 years, measuring self-assessed stress using smartphones. A total of 35 published articles comprising 1464 individuals were included for review. According to the objectives, (1) study designs were heterogeneous, and smartphone-based self-assessed stress was measured using various methods (e.g., dichotomized questions on stress, yes or no; Likert scales on stress; and questionnaires); (2) the validity of smartphone-based self-assessed stress compared with validated stress scales was investigated in 3 studies, and of these, only 1 study found a moderate statistically significant positive correlation (r=.4; Psmartphone-based self-assessed stress was found to correlate with some of the reported smartphone generated objective data, including voice features and data on activity and phone usage. Smartphones are being used to measure self-assessed stress in different contexts. The evidence of the validity of smartphone-based self-assessed stress is

  11. Stress analysis of single joint rock mass under triaxial compression

    LIU Xin-rong(刘新荣); JIANG Shu-ping(蒋树屏); LI Xiao-hong(李晓红); BAO Tai(包太)


    Based on the fundamental principle of rock mechanics, the stresses of single joint rock mass under three-dimensional compression were analyzed. The effect of the intermediate principle stress on the strength of single joint rock mass were discussed in particular. It is found that the strength of single joint rock are affected by the intermediate principal stress, which may be the main factor in some conditions.

  12. Comparison and Outcome Analysis of Patients with Takotsubo Cardiomyopathy Triggered by Emotional Stress or Physical Stress

    Giannakopoulos, Konstantinos; El-Battrawy, Ibrahim; Schramm, Katja; Ansari, Uzair; Hoffmann, Ursula; Borggrefe, Martin; Akin, Ibrahim


    Background: Previous studies revealed that takotsubo cardiomyopathy (TTC) is triggered by physical and emotional stresses. This study was performed to determine the short- and long-term prognostic impact of emotional- and physical stress associated with TTC. Methods and results: Our institutional database constituted a collective of 84 patients diagnosed with TTC between 2003 and 2015. The patients were divided into two groups as per the presence of emotional stress (n = 24, 21%) or physical stress (n = 60, 52.6%). The endpoint was a composite of in-hospital events (thromboembolic events and life-threatening arrhythmias), myocardial infarction, all-cause of mortality, re-hospitalization due to heart failure, stroke, and recurrence of TTC. A Kaplan–Meier analysis indicated a significantly lower event-free survival rate over a mean follow-up of 5 years in the emotional group than the physical stress group (log-rank, p < 0.01). Multivariate Cox regression analysis revealed only emotional stress (HR 0.4, 95% CI: 0.2–0.9, p < 0.05) as a negative independent predictor of the primary endpoint. Conclusion: Rates of in-hospital events and short- as well as long-term events were significantly lower in TTC patients suffering from emotional stress as compared to patients with physical stress. PMID:28496419

  13. Comparison and Outcome Analysis of Patients with Takotsubo Cardiomyopathy Triggered by Emotional Stress or Physical Stress

    Konstantinos Giannakopoulos


    Full Text Available Background: Previous studies revealed that takotsubo cardiomyopathy (TTC is triggered by physical and emotional stresses. This study was performed to determine the short- and long-term prognostic impact of emotional- and physical stress associated with TTC.Methods and results: Our institutional database constituted a collective of 84 patients diagnosed with TTC between 2003 and 2015. The patients were divided into two groups as per the presence of emotional stress (n = 24, 21% or physical stress (n = 60, 52.6%. The endpoint was a composite of in-hospital events (thromboembolic events and life-threatening arrhythmias, myocardial infarction, all-cause of mortality, re-hospitalization due to heart failure, stroke, and recurrence of TTC. A Kaplan–Meier analysis indicated a significantly lower event-free survival rate over a mean follow-up of 5 years in the emotional group than the physical stress group (log-rank, p < 0.01. Multivariate Cox regression analysis revealed only emotional stress (HR 0.4, 95% CI: 0.2–0.9, p < 0.05 as a negative independent predictor of the primary endpoint.Conclusion: Rates of in-hospital events and short- as well as long-term events were significantly lower in TTC patients suffering from emotional stress as compared to patients with physical stress.

  14. Stress Analysis of Single Spacer Grid Support considering Fuel Rod

    Yoo, Y. G.; Jung, D. H.; Kim, J. H. [Chungnam National University, Daejeon (Korea, Republic of); Park, J. K.; Jeon, K. L. [Korea Nuclear Fuel, Daejeon (Korea, Republic of)


    Pressurized water reactor (PWR) nuclear fuel assembly is mainly composed of a top-end piece, a bottom-end piece, lots of fuel rods, and several spacer grids. Among them, the main function of spacer grid is protecting fuel rods from Fluid Induced Vibration (FIV). The cross section of spacer grid assembled by laser welding in upper and lower point. When the fuel rod inserted in spacer gird, spring and dimple and around of welded area got a stresses. The main hypothesis of this analysis is the boundary area of HAZ and base metal can get a lot of damage than other area by FIV. So, design factors of spacer grid mainly considered to preventing the fatigue failure in HAZ and spring and dimple of spacer grid. From previous researching, the environment in reactor verified. Pressure and temperature of light water observed 15MPa and 320 .deg. C, and vibration of the fuel rod observed within 0 {approx} 50Hz. In this study, mechanical properties of zirconium alloy that extracted from the test and the spacer grid model which used in the PWR were applied in stress analyzing. General-purpose finite element analysis program was used ANSYS Workbench 12.0.1 version. 3-D CAD program CATIA was used to create spacer grid model

  15. Variability salt stress response analysis of Tunisian natural ...

    Variability salt stress response analysis of Tunisian natural populations of Medicago ... African Journal of Biotechnology ... from 11 Tunisian natural populations collected from areas that varied in soil composition, salinity and water availability.

  16. Role stress amongst nurses at the workplace: concept analysis.

    Riahi, Sanaz


    The present study explicates the concept of role stress amongst nurses through an analysis adopted from Walker and Avant; Strategies for Theory Construction in Nursing, 4th edn, Prentice Hall, New Jersey, NY. Role stress has become a significant problem amongst nurses and has created much distress leading to burnout among many in the nursing profession. It is significant to analyse the concept of role stress and its relative attributes and consequences, in order to recognize the necessary antecedents needed to create better conditions for nurses at the workplace. A modified method developed by Walker and Avant was used for this concept analysis. A model representing the concept of role stress was developed through careful consideration of the attributes, consequences, antecedents and empirical referents of role stress. The concept analysis of role stress among nurses at the workplace recognized the vulnerability of the nursing discipline towards burnout and distress in general. It is critical to be aware of the current state of health care and note the increased workload created for nurses. Nurses are at a greater vulnerability for role stress, making it imperative for health care organizations to critically evaluate and establish preventative measures for the concept of role stress. 2011 Blackwell Publishing Ltd.

  17. Stress Analysis of a Secondary-Bending Specimen


    Control Office Ansett Airlines of Australia, Library 0 Qantas Airways Limited Hawker de Havilland Aust Pty Ltd, Victoria, Library Hawker de Havilland...MELBOURNE, VICTORIA Technical Note 58 STRESS ANALYSIS OF A SECONDARY-BENDING SPECIMEN 0 by R.L. EVANS M. HELLER Approved for public release C) COMMONWEALTH...AND TECHNOLOGY ORGANISATION AERONAUTICAL RESEARCH LABORATORY Technical Note 58 0 STRESS ANALYSIS OF A SECONDARY-BENDING SPECIMEN by R.L. EVANS 0 M

  18. Environmental Lead Exposure, Catalase Gene, and Markers of Antioxidant and Oxidative Stress Relation to Hypertension: An Analysis Based on the EGAT Study

    Jintana Sirivarasai


    Full Text Available Lead has been linked to the development of hypertension via oxidative stress. Catalase plays an important role in the disposal of hydrogen peroxide in erythrocyte and its activity was determined by CAT gene. The aims of this study were to investigate (1 the association between blood levels of antioxidant markers such as catalase, superoxide dismutase, glutathione, glutathione peroxidase, oxidative stress-marker (malondialdehyde, and blood lead level and (2 the influence of genetic polymorphism of CAT gene (rs769217 on change in blood pressure in general population of EGAT study project. This is a cross-sectional study of 332 normotensive, 432 prehypertensive, and 222 hypertensive male subjects. Hypertensive subjects had significantly higher blood lead level (5.28 μg/dL compared to normotensive (4.41 μg/dL and prehypertensive (4.55 μg/dL subjects (P<0.05. These significant findings are also found in MDA levels. Moreover, individuals with TT genotype in hypertensive group had significantly higher blood lead and MDA levels (6.06 μg/dL and 9.67 μmol/L than those with CC genotype (5.32 μg/dL and 8.31 μmol/L, P<0.05. Our findings suggested that decreased blood catalase activity in this polymorphism together with low level lead exposure induced lipid peroxidation may be responsible for hypertension.

  19. Advanced stress analysis methods applicable to turbine engine structures

    Pian, Theodore H. H.


    The following tasks on the study of advanced stress analysis methods applicable to turbine engine structures are described: (1) constructions of special elements which contain traction-free circular boundaries; (2) formulation of new version of mixed variational principles and new version of hybrid stress elements; (3) establishment of methods for suppression of kinematic deformation modes; (4) construction of semiLoof plate and shell elements by assumed stress hybrid method; and (5) elastic-plastic analysis by viscoplasticity theory using the mechanical subelement model.

  20. Impact of Stress and Glucocorticoids on Schema-Based Learning.

    Kluen, Lisa Marieke; Nixon, Patricia; Agorastos, Agorastos; Wiedemann, Klaus; Schwabe, Lars


    Pre-existing knowledge, a 'schema', facilitates the encoding, consolidation, and retrieval of schema-relevant information. Such schema-based memory is key to every form of education and provides intriguing insights into the integration of new information and prior knowledge. Stress is known to have a critical impact on memory processes, mainly through the action of glucocorticoids and catecholamines. However, whether stress and these major stress mediators affect schema-based learning is completely unknown. To address this question, we performed two experiments, in which participants acquired a schema on day 1 and learned schema-related as well as schema-unrelated information on day 2. In the first experiment, participants underwent a stress or control manipulation either immediately or about 25 min before schema-based memory testing. The second experiment tested whether glucocorticoid and/or noradrenergic activation is sufficient to modulate schema-based memory. To this end, participants received orally a placebo, hydrocortisone, the α2-adrenoceptor-antagonist yohimbine, leading to increased noradrenergic stimulation, or both drugs, before completing the schema-based memory test. Our data indicate that stress, irrespective of the exact timing of the stress exposure, impaired schema-based learning, while leaving learning of schema-unrelated information intact. A very similar effect was obtained after hydrocortisone, but not yohimbine, administration. These data show that stress disrupts participants' ability to benefit from prior knowledge during learning and that glucocorticoid activation is sufficient to produce this effect. Our findings provide novel insights into the impact of stress and stress hormones on the dynamics of human memory and have important practical implications, specifically for educational contexts.Neuropsychopharmacology advance online publication, 14 December 2016; doi:10.1038/npp.2016.256.

  1. iSenseStress: Assessing stress through human-smartphone interaction analysis

    Matteo Ciman


    Full Text Available Stress condition, if experienced for an extended amount of time, can negatively affect individual's health. Several external sensors monitoring different physiological states correlated with stress, or smartphone apps that monitor individuals context, have been leveraged to assess stress state in everyday life. The less intrusive ''human-smartphone interaction'' have been under-investigated so far. In our research we leverage 'swipe', 'scroll' and 'text input' interactions to assess the stress state of smartphone users. Based on data collected from 13 participants, we leverage 'swipe' and 'scroll' data to assess stress with an average F-measure of 79-85% for a within-subject model, and of 70-80% when building a global model. Moreover, 'text input' via a virtual keyboard has been analyzed, showing how several easy to calculate features enable to differentiate between stress and no-stress state. To the best of our knowledge, this is the first attempt to leverage human-smartphone interaction, and in particular 'swipe', 'scroll' and 'text input' interactions, to accurately assess stress state in individuals without using any external sensor or leveraging privacy-sensitive context information.

  2. Stress management policy analysis: a preventative approach

    Islam, Jamal; Mohajan, Haradhan; Datta, Rajib


    At the present world human resource is considered as one of the most important resource. In the era of dynamic business most of the organizations invest a huge amount of money and spend a great deal of time and efforts as though they can properly utilize and manage this vital resource. Stress is one of the burning questions that hinder the officers’ and workers’ performance and productivity. In this paper all experiences of jobs are discussed which affects human minds and bodies. It has been ...

  3. Finite element stress analysis of some ankle joint prostheses.

    Falsig, J; Hvid, I; Jensen, N C


    A three-dimensional finite element stress analysis was employed to calculate stresses in a distal tibia modelled with three simple total ankle joint replacement tibial components. The bone was modelled as a composite structure consisting of cortical and trabecular bone in which the trabecular bone was either homogeneous with a constant modulus of elasticity or heterogenous with experimentally determined heterogeneity. The results were sensitive to variations in trabecular bone material property distributions, with lower stresses being calculated in the heterogeneous model. An anterolateral application of load, which proved the least favourable, was used in comparing the prosthetic variants. Normal and shear stresses at the trabecular bone-cement interface and supporting trabecular bone were slightly reduced by addition of metal backing to the polyethylene articular surface, and a further reduction to very low values was obtained by addition of a long intramedullary peg bypassing stresses to the cortical bone.

  4. Genome wide analysis of stress responsive WRKY transcription factors in Arabidopsis thaliana

    Shaiq Sultan


    Full Text Available WRKY transcription factors are a class of DNA-binding proteins that bind with a specific sequence C/TTGACT/C known as W-Box found in promoters of genes which are regulated by these WRKYs. From previous studies, 43 different stress responsive WRKY transcription factors in Arabidopsis thaliana, identified and then categorized in three groups viz., abiotic, biotic and both of these stresses. A comprehensive genome wide analysis including chromosomal localization, gene structure analysis, multiple sequence alignment, phylogenetic analysis and promoter analysis of these WRKY genes was carried out in this study to determine the functional homology in Arabidopsis. This analysis led to the classification of these WRKY family members into 3 major groups and subgroups and showed evolutionary relationship among these groups on the base of their functional WRKY domain, chromosomal localization and intron/exon structure. The proposed groups of these stress responsive WRKY genes and annotation based on their position on chromosomes can also be explored to determine their functional homology in other plant species in relation to different stresses. The result of the present study provides indispensable genomic information for the stress responsive WRKY transcription factors in Arabidopsis and will pave the way to explain the precise role of various AtWRKYs in plant growth and development under stressed conditions.

  5. Stresses Analysis of Petroleum Pipe Finite Element under Internal Pressure



    Full Text Available This paper described the results of a nonlinear static mode within ANSYS of elastic and elastic-plastic behaviour of thin petroleum pipe that is subjected to an internal pressure and therefore a linear stress analysis performed using ANSYS 9.0 finite element software Such an analysis is important because the shape of most structures under internal pressure is cylindrical[1]. In this paper is considered only. Elastic and elastic-plastic finite element analysis is used to predict the principle stresses, effective stress results are compared with those obtained from theatrical equations in order to predict the limit and failure loads for this type of loading also the relationships between redial, hoop stresses and displacement has been used to develop a through understanding. The analysis was completed using ANAYS Version 9.0. (a finite element program for Microsoft Windows NT. The program allows pre-processing, analysis and post-processing stages to be completed within a single application. The program can be used to model a large number of situations including buckling, plastic deformation, forming and stress analysis problems. r mm (In this study ,a thin pipe of internal radiu ri 596 .9 mmand of externalo 609 .6objected to aninternal pressure 2 i  4 .83  / mm which is gradually increased to near the ultimate load that may be sustained by the pipe. The pipe is modelled as an elasto-plastic material using the Von Mises yield criterion which is normally used for metallic materials[2]. The specification of the load in several increments enables the spread of the plasticity to occur gradually and its effect on the stress distribution to be assessed. Key words: finite element analysis, elastic-plastic behavior, thin walled pipe equivalent stress, TWT.

  6. Writing therapy for posttraumatic stress: a meta-analysis.

    van Emmerik, Arnold A P; Reijntjes, Albert; Kamphuis, Jan H


    Face-to-face psychological treatments have difficulty meeting today's growing mental health needs. For the highly prevalent posttraumatic stress (PTS) conditions, accumulating evidence suggests that writing therapy may constitute an efficient treatment modality, especially when administered through the Internet. We therefore conducted a meta-analysis to investigate the efficacy of writing therapies for PTS and comorbid depressive symptoms. The literature was searched using several structured and unstructured strategies, including key word searches of the PubMed, Web of Science, PsycINFO, and PILOTS databases. Six studies met eligibility criteria and were included in the analyses. These studies included a total of 633 participants, of which 304 were assigned to writing therapy. Across 5 direct comparisons of writing therapy to waiting-list control, writing therapy resulted in significant and substantial short-term reductions in PTS and comorbid depressive symptoms. There was no difference in efficacy between writing therapy and trauma-focused cognitive behavioral therapy, but we caution that this finding was based on only 2 direct comparisons. Writing therapy is an evidence-based treatment for PTS, and constitutes a useful treatment alternative for patients who do not respond to other evidence-based treatments. Internet adaptations of writing therapy for PTS may be especially useful for reaching trauma survivors in need of evidence-based mental health care who live in remote areas or who prefer to retain their anonymity. Copyright © 2012 S. Karger AG, Basel.

  7. Base Stress of the Opened Bottom Cylinder Structures

    刘建起; 孟晓娟


    The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder,subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.

  8. Normal stress measurement via image analysis of interfacial deformation

    Lowry, Brian; Höpfl, Wolfgang


    The first coefficient of normal stress in polymer solutions is determined via image analysis. The method measures pointwise normal stresses along a sheared liquid-liquid interface. In the case of a steady rotating liquid bridge, the deformation of the interface is strictly due to normal stress swelling effects. In our experiments, a cylindrical liquid bridge of polystyrene solution rotates in a cylindrical bath filled with a glycerol-water solution of similar density. The shape of the interface and the jump in normal stress across the interface are determined using pressure-stress image analysis (P-SIA) from high resolution digital images. The stress resolution is better than 0.1 Pa at the free interface. The polystyrene solution exhibits a normal stress at the interface which grows with the square of the rotation rate. This effect is absent for Newtonian liquids, and is in excellent agreement with the ideal low shear behaviour of polymer solutions. Small density differences between the liquids are taken into consideration, showing that centrifugal effects are negligible. This method is potentially an excellent alternative to classical rheometry at low shear rates.


    Ran Yanovich


    Full Text Available To investigate the association of polymorphisms within candidate genes which we hypothesized may contribute to stress fracture predisposition, a case-control, cross- sectional study design was employed. Genotyping 268 Single Nucleotide Polymorphisms- SNPs within 17 genes in 385 Israeli young male and female recruits (182 with and 203 without stress fractures. Twenty-five polymorphisms within 9 genes (NR3C1, ANKH, VDR, ROR2, CALCR, IL6, COL1A2, CBG, and LRP4 showed statistically significant differences (p < 0.05 in the distribution between stress fracture cases and non stress fracture controls. Seventeen genetic variants were associated with an increased stress fracture risk, and eight variants with a decreased stress fracture risk. None of the SNP associations remained significant after correcting for multiple comparisons (false discovery rate- FDR. Our findings suggest that genes may be involved in stress fracture pathogenesis. Specifically, the CALCR and the VDR genes are intriguing candidates. The putative involvement of these genes in stress fracture predisposition requires analysis of more cases and controls and sequencing the relevant genomic regions, in order to define the specific gene mutations

  10. Stress analysis by neutron diffraction. Spannungsanalyse mit Neutronenbeugung

    Pintschovius, L. (Kernforschungszentrum Karlsruhe, INFP (Germany))


    Investigating mechanical stresses, the point of interest actually is not the interplanar crystal spacing itself in the polycrystalline material, but the relative change of it. Neutrons are particularly suited for application to stress analysis, due to their deep penetration range in the materials of up to 10 mm. The article explains the basic principles of operation of a neutron diffractometer and its application to analysing residual stresses in specimens made of aluminium alloys or ceramics, in steel-ceramic soldered joints, or in steel rivets. (DG).

  11. An Integrated Analysis of Changes in Water Stress in Europe

    Henrichs, T.; Lehner, B.; Alcamo, J.


    that today high water stress exists in one-fifth of European river basin area. Under a scenario projection, increases in water use throughout Eastern Europe are accompanied by decreases in water availability in most of Southern Europe--combining these trends leads to a marked increase in water stress......Future changes in water availability with climate change and changes in water use due to socio-economic development are to occur in parallel. In an integrated analysis we bring together these aspects of global change in a consistent manner, and analyse the water stress situation in Europe. We find...

  12. Stress analysis and stress-intensity factors for finite geometry solids containing rectangular surface cracks

    Gyekenyesi, J. P.; Mendelson, A.


    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses, and the stress-intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress-intensity factors are also obtained for a through-thickness, center-cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress-intensity factors for commonly encountered surface crack geometries in finite solids

  13. Stress analysis and stress intensity factors for finite geometry solids containing rectangular surface cracks

    Gyekenyesi, J. P.; Mendelson, A.


    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses and the stress intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress intensity factors are also obtained for a through-thickness, center cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress intensity factors for commonly encountered surface crack geometries in finite solids.

  14. Simulation on Residual Stress of Shot Peening Based on a Symmetrical Cell Model

    WANG, Cheng; HU, Jiacheng; GU, Zhenbiao; XU, Yangjian; WANG, Xiaogui


    The symmetrical cell model is widely used to study the residual stress induced by shot peening. However, the correlation between the predicted residual stresses and the shot peening coverage, which is a big challenge for the researchers of the symmetrical cell model, is still not established. Based on the dynamic stresses and the residual stresses outputted from the symmetrical cell model, the residual stresses corresponding to full coverage are evaluated by normal distribution analysis. The predicted nodal dynamic stresses with respect to four corner points indicate that the equi-biaxial stress state exists only for the first shot impact. Along with the increase of shot number, the interactions of multiple shot impacts make the fluctuation of the nodal dynamic stresses about an almost identical value more and more obvious. The mean values and standard deviations of the residual stresses gradually tend to be stable with the increase of the number of shot peening series. The mean values at each corner point are almost the same after the third peening series, which means that an equi-biaxial stress state corresponding to the full coverage of shot peening is achieved. Therefore, the mean values of the nodal residual stresses with respect to a specific transverse cross-section below the peened surface can be used to correlate the measured data by X-ray. The predicted residual stress profile agrees with the experimental results very well under 200% peening coverage. An effective correlation method is proposed for the nodal residual stresses predicted by the symmetrical cell model and the shot peening coverage.

  15. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Chrysochoos A.; Wattrisse B.; Muracciole J.M.; Caborgan R.


    Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard th...

  16. Analysis of Stress Updates in the Material-point Method

    Andersen, Søren; Andersen, Lars


    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...... updating and integrating stresses in time is problematic. This is discussed using an example of the dynamical collapse of a soil column....

  17. Thermal Stress Analysis of Laminated Composite Plates using Shear Flexible Element

    M. Ganapathi


    Full Text Available Using degree Centigrade shear flexible QUAD-9 plate element, stresses and deflections in composite laminated plates due to thermal loads analysed. A formulation based on first order shear deformation theory has been employed for the analysis. The effects of various parameters, such as ply-angle, number of layers, thickness and aspect ratios on stresses and deflections are brought out. The present formulation is being extended for studying composite shell structures.

  18. Re-analysis of fatigue data for welded joints using the notch stress approach

    Pedersen, Mikkel Melters; Mouritsen, Ole Ø.; Hansen, Michael Rygaard


    Experimental fatigue data for welded joints have been collected and subjected to re-analysis using the notch stress approach according to IIW recommendations. This leads to an overview regarding the reliability of the approach, based on a large number of results (767 specimens). Evidently......-welded joints agree quite well with the FAT 225 curve; however a reduction to FAT 200 is suggested in order to achieve approximately the same safety as observed in the nominal stress approach....

  19. Quantitative analysis of UV-A shock and short term stress using iTRAQ, pseudo selective reaction monitoring (pSRM) and GC-MS based metabolite analysis of the cyanobacterium Nostoc punctiforme ATCC 29133.

    Wase, Nishikant; Pham, Trong Khoa; Ow, Saw Yen; Wright, Phillip C


    A quantitative proteomics and metabolomics analysis was performed using iTRAQ, HPLC and GC-MS in the filamentous cyanobacterium Nostoc punctiforme ATCC 29133 to understand the effect of short and long term UV-A exposure. Changes in the proteome were measured for short-term stress (4-24h) using iTRAQ. Changes in the photosynthetic pigments and intracellular metabolites were observed at exposures of up to 7days (pigments) and up to 11days (intracellular metabolites). To assess iTRAQ measurement quality, pseudo selected reaction monitoring (pSRM) was used, with this confirming underestimation of protein abundance levels by iTRAQ. Our results suggest that short term UV-A radiation lowers the abundance of PS-I and PS-II proteins. We also observed an increase in abundance of intracellular redox homeostasis proteins and plastocyanin. Additionally, we observed statistically significant changes in scytonemin, Chlorophyll A, astaxanthin, zeaxanthin, and β-carotene. Assessment of intracellular metabolites showed significant changes in several, suggesting their potential role in the Nostoc's stress mitigation strategy. Cyanobacteria under UV-A radiation have reduced growth due to intensive damage to essential functions, but the organism shows a defense response by remodeling bioenergetics pathway, induction of the UV protection compound scytonemin and increased levels of proline and tyrosine as a mitigation response. The effect of UV-A radiation on the proteome and intracellular metabolites of N. punctiforme ATCC 29133 including photosynthetic pigments has been described. We also verify the expression of 13 iTRAQ quantified protein using LC-pSRM. Overall we observed that UV-A radiation has a drastic effect on the photosynthetic machinery, photosynthetic pigments and intracellular amino acids. As a mitigation strategy against UV-A radiation, proline, glycine, and tyrosine were accumulated. Copyright © 2014. Published by Elsevier B.V.

  20. Analysis of structural hot-spot stress in orthotropic plates

    Chen Ce; Ji Bohai; Xu Hanjiang


    On the basis of the actual steel deck structure of Taizhou Bridge, this paper carries out hot-spot stress analysis on some key spots by using the finite element model which simulates local structure of orthotropic steel bridge decks. A finite element model is established for local structure of orthotropic steel bridge decks, and in the analysis of linear elasticity of the structure, face load is employed to simulate the loads from vehicle wheels. Analysis results show that main stresses are relatively heavy at the joints between diaphragm plates, top plates and U-shaped ribs and the joints between diaphragm plates and U-shaped ribs. These joints shall be regarded as key points for hot-spot stress analysis. Different mesh densities are adopted in the finite element model and the main stresses at different hot spots are contrasted and linear extrapolation is carried out using extrapolation formulae. Results show that different mesh densities have different influences on the hot-spot stresses at the welded seams of U-shaped ribs. These influences shall be considered in calculation and analysis.

  1. Preliminary analysis of knee stress in Full Extension Landing

    Majid Davoodi Makinejad


    Full Text Available OBJECTIVE: This study provides an experimental and finite element analysis of knee-joint structure during extended-knee landing based on the extracted impact force, and it numerically identifies the contact pressure, stress distribution and possibility of bone-to-bone contact when a subject lands from a safe height. METHODS: The impact time and loads were measured via inverse dynamic analysis of free landing without knee flexion from three different heights (25, 50 and 75 cm, using five subjects with an average body mass index of 18.8. Three-dimensional data were developed from computed tomography scans and were reprocessed with modeling software before being imported and analyzed by finite element analysis software. The whole leg was considered to be a fixed middle-hinged structure, while impact loads were applied to the femur in an upward direction. RESULTS: Straight landing exerted an enormous amount of pressure on the knee joint as a result of the body's inability to utilize the lower extremity muscles, thereby maximizing the threat of injury when the load exceeds the height-safety threshold. CONCLUSIONS: The researchers conclude that extended-knee landing results in serious deformation of the meniscus and cartilage and increases the risk of bone-to-bone contact and serious knee injury when the load exceeds the threshold safety height. This risk is considerably greater than the risk of injury associated with walking downhill or flexion landing activities.


    Cheng Peng; Xingyao Wang; Yongzhong Huo


    The mechanical behavior of shape memory alloys (SMAs) is closely related to the formation and evolution of its microstructures. Through theoretical analysis and experimental ob-servations, it was found that the stress-induced martensitic transformation process of single crys-tal Cu-based SMA under uniaxial tension condition consisted of three periods: nucleation, mixed nucleation and growth, and merging due to growth. During the nucleation, the stress dropped rapidly and the number of interfaces increased very fast while the phase fraction increased slowly.In the second period, both the stress and the interface number changed slightly but the phase fraction increased dramatically. Finally, the stress and the phase fraction changed slowly while the number of interfaces decreased quickly. Moreover, it was found that the transformation could be of multi-stage: sharp stress drops at several strains and correspondingly, the nucleation and growth process occurred quasi-independently in several parts of the sample.

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

    W.J.vdM. Steyn


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

  4. Crack prediction in EB-PVD thermal barrier coatings based on the simulation of residual stresses

    Chen, J. W.; Zhao, Y.; Liu, S.; Zhang, Z. Z.; Ma, J.


    Thermal barrier coatings systems (TBCs) are widely used in the field of aerospace. The durability and insulating ability of TBCs are highly dependent on the residual stresses of top coatings, thus the investigation of the residual stresses is helpful to understand the failure mechanisms of TBCs. The simulation of residual stresses evolution in electron beam physical vapor deposition (EB-PVD) TBCs is described in this work. The interface morphology of TBCs subjected to cyclic heating and cooling is observed using scanning electron microscope (SEM). An interface model of TBCs is established based on thermal elastic-plastic finite method. Residual stress distributions in TBCs are obtained to reflect the influence of interfacial roughness. Both experimental and simulation results show that it is feasible to predict the crack location by stress analysis, which is crucial to failure prediction.

  5. Analysis of tempering stresses in bilayered porcelain discs.

    DeHoff, P H; Anusavice, K J


    Previous studies of opaque-porcelain/body-porcelain discs have shown that compressive stresses which develop in the porcelain surface by being tempered in air can inhibit the sizes of cracks induced within the surface. The objective of this study was to develop a theoretical model for analysis of transient and residual stresses in opaque-porcelain/body-porcelain discs which were produced under variable cooling conditions. The model incorporates the effects of stress and structural relaxation. Transient and residual stresses were calculated for bilayered porcelain discs 16 mm in diameter and 2 mm in thickness for three opaque-porcelain/body-porcelain combinations. Transient temperature distributions in the discs for simulated convective cooling were calculated by finite-element analysis. Data from microhardness indentations reported by Anusavice et al. (1989) indicate that crack lengths measured for bilayered porcelain discs subjected to slow cooling conditions, for which the model predicted residual tensile stresses, were greater than those combinations for which residual compressive stresses were calculated. Calculated values of residual compressive stress for tempered specimens were considerably higher than those for specimens that were slowly cooled and those that were cooled by free convection. In general, residual stress levels calculated by use of the analytical model were in fairly good agreement with the trends observed for crack lengths and bi-axial flexural strengths reported by Anusavice and Hojjatie (1991). The results of the present study indicate that a visco-elastic model is a viable approach for determination of transient and residual stresses in opaque-porcelain/body-porcelain discs.

  6. Static Stress Analysis of Security Injection Tank


    The static structural analysis of the security injection tank is made to make sure whether the tank can withstand concerned loads or not on all conditions conforming to concerned code prescripts and design requirements. The tanks

  7. Finite element analysis of thermal stresses in optical storage media

    Evans, K. E.; Nkansah, M. A.; Abbott, S. J.


    Finite element techniques are used to calculate the thermal stresses generated in single-layer, optical storage thin films. The calculations predict that the thermal stresses generated by laser heating may reach values well beyond the strength of the media in times much less than that for pit formation by melting. Both dye-polymer and metal-based systems are considered with either air or substrate incident laser sources.

  8. Analysis of interlaminar stress and nonlinear dynamic response for composite laminated plates with interfacial damage

    Zhu, F. H.; Fu, Y. M.


    By considering the effect of interfacial damage and using the variation principle, three-dimensional nonlinear dynamic governing equations of the laminated plates with interfacial damage are derived based on the general six-degrees-of-freedom plate theory towards the accurate stress analysis. The solutions of interlaminar stress and nonlinear dynamic response for a simply supported laminated plate with interfacial damage are obtained by using the finite difference method, and the results are validated by comparison with the solution of nonlinear finite element method. In numerical calculations, the effects of interfacial damage on the stress in the interface and the nonlinear dynamic response of laminated plates are discussed.

  9. Numerical analysis of loaded stress and central displacement of deep groove ball bearing

    杨磊; 邓松; 李红星


    The aim of this work is to develop a three-dimensional model of deep groove ball bearing to investigate the loaded stresses and central displacements of bearing rings. The equivalent stresses and central displacements of bearing rings are obtained based on the simulated analysis. Moreover, several parameters, such as load magnitude, raceway groove curvature radius (RGCR), thicknesses of outer and inner rings, are varied to investigate their effects on the equivalent stresses and central displacements of bearing rings. Research results provide useful guidelines for determining the design parameters.

  10. A non-linear analytic stress model for the analysis on the stress interaction between TSVs

    Ming-Han Liao


    Full Text Available Thermo-elastic strain is induced by through silicon vias (TSV due to the difference of thermal expansion coefficients between the copper (∼18 ppm/◦C and silicon (∼2.8 ppm/◦C when the structure is exposed to a thermal budget in the three dimensional integrated circuit (3DIC process. These thermal expansion stresses are high enough to induce the delamination on the interfaces between the copper, silicon, and isolated dielectric. A compact analytic model for the strain field induced by different layouts of thermal copper filled TSVs with the linear superposition principle is found to result in large errors due to the strong stress interaction between TSVs. In this work, a nonlinear stress analytic model with different TSV layouts is demonstrated by the finite element method and Mohr’s circle analysis. The stress characteristics are also measured by the atomic force microscope-raman technique at a nanometer level resolution. This nonlinear stress model for the strong interactions between TSVs results in an electron mobility change ~2-6% smaller than that resulting from a model that only considers the linear stress superposition principle.

  11. Photoelastic stress analysis in perforated (Rochette) resin bonded bridge design.

    Ziada, H M; Orr, J F; Benington, I C


    Rochette described the perforated cast metal bonded design for splinting periodontally compromised teeth. The design was later used for replacing missing teeth. The main causes of failure of the perforated (Rochette) type design were attributed to inappropriate case selection and erosion of the composite from perforations. The aim of this study was to analyse the effect of stress magnitude and direction on failure of perforated resin bonded bridges (RBBs). The objective was to compare stress magnitudes in this design with those reported on the non-perforated RBBs. Photoelastic modelling materials were selected to represent the relative stiffnesses of a posterior mandibular and an anterior maxillary perforated (Rochette) type design. The sizes of the models were scaled to x 2.5 in order to enhance visual analysis of the stress patterns. Stress magnitudes were quantified from isochromatic fringes and stress directions were evaluated from stress trajectories. These revealed a high-stress concentration around the perforations, particularly for those at the proximo-lingual/palatal (connector) areas. This experimental study revealed that the main reason for failure of Rochette designs is deformation at the perforations.

  12. A meta-analysis of oxidative stress markers in schizophrenia


    Oxidative stress has been identified as a possible element in the neuropathological processes of schizophrenia(SCZ).Alteration of oxidative stress markers has been reported in SCZ studies,but with inconsistent results.To evaluate the risk of oxidative stress to schizophrenia,a meta-analysis was conducted,including five markers of oxidative stress [thiobarbituric reactive substances(TBARS),nitric oxide(NO),catalase(CAT),glutathione peroxidase(GP) and superoxide dismutase(SOD)] in SCZ patients versus healthy controls.This study showed that TBARS and NO significantly increased in SCZ,while SOD activity significantly decreased in the disorganized type of SCZ patients.No significant effect size was found for the activities of GP and CAT in SCZ patients(P>0.05).Egger’s regression test observed no significant publication bias across the oxidative stress markers,but found high heterogeneities in all the 5 markers.The subgroup analysis suggested that the ethnicity,sample size of patients and sample sources may contribute to the heterogeneity of the results for TBARS,NO and SOD.The result further demonstrated the involvement of oxidative stress in the pathophysiology of schizophrenia.

  13. Contact Stress Analysis and Fatigue Life Prediction of a Turbine Fan Disc

    Yang, Liang; Zhu, Shun-Peng; Lv, Zhiqiang; Zuo, Fang-Jun; Huang, Hong-Zhong


    Fan discs are critical components of an aero engine. In this paper, contact stress and life prediction of a turbine fan disc were investigated. A simplified pin/disc model was conducted to simulate the practical working condition under applied loads using finite element (FE) analysis. This study is devoted to examining the effects of interface condition of pin/disc such as gap and coefficient upon the maximum stress. The FE model indicated that the maximum stress occurs at the top right corner in the second pin hole, and larger gap or friction coefficient has a significant effect on the maximum stress. In addition, FE analysis without considering friction is also conducted. The results show that the dangerous point is similar to the result which considers friction and the stress state is relatively larger than that of considering friction. Finally, based on FE analysis result, life prediction for the fan disc is conducted to combine the material S-N curve, mean stress effects and concentration stress factor obtained by means of FE method.

  14. Flux Balance Analysis of Escherichia coli under Temperature and pH Stress Conditions

    Xu, Xiaopeng


    An interesting discovery in biology is that most genes in an organism are dispensable. That means these genes have minor effects on survival of the organism in standard laboratory conditions. One explanation of this discovery is that some genes play important roles in specific conditions and are essential genes under those conditions. E. coli is a model organism, which is widely used. It can adapt to many stress conditions, including temperature, pH, osmotic, antibiotic, etc. Underlying mechanisms and associated genes of each stress condition responses are usually different. In our analysis, we combined protein abundance data and mutant conditional fitness data into E. coli constraint-based metabolic models to study conditionally essential metabolic genes under temperature and pH stress conditions. Flux Balance Analysis was employed as the modeling method to analysis these data. We discovered lists of metabolic genes, which are E. coli dispensable genes, but conditionally essential under some stress conditions. Among these conditionally essential genes, atpA in low pH stress and nhaA in high pH stress found experimental evidences from previous studies. Our study provides new conditionally essential gene candidates for biologists to explore stress condition mechanisms.

  15. Stochastic Plane Stress Analysis with Elementary Stiffness Matrix Decomposition Method

    Er, G. K.; Wang, M. C.; Iu, V. P.; Kou, K. P.


    In this study, the efficient analytical method named elementary stiffness matrix decomposition (ESMD) method is further investigated and utilized for the moment evaluation of stochastic plane stress problems in comparison with the conventional perturbation method in stochastic finite element analysis. In order to evaluate the performance of this method, computer programs are written and some numerical results about stochastic plane stress problems are obtained. The numerical analysis shows that the computational efficiency is much increased and the computer EMS memory requirement can be much reduced by using ESMD method.

  16. Stress Analysis and Optimum Design of Hot Extrusion Dies

    帅词俊; 肖刚; 倪正顺


    A three-dimensional model of a hot extrusion die was developed by using ANSYS software and its second development language-ANSYS parametric design language.A finite element analysis and optimum design were carried out.The three-dimensional stress diagram shows that the stress concentration is rather severe in the bridge of the hot extrusion die, and that the stress distribution is very uneven.The optimum dimensions are obtained.The results show that the optimum height of the extrusion die is 89.596 mm.The optimum radii of diffluence holes are 65.048 mm and 80.065 mm.The stress concentration is reduced by 27%.

  17. Advanced holographic nondestructive testing system for residual stress analysis

    Kniazkov, Anatoli; Dovgalenko, George; Salamo, Gregory; Latychevskaia, Tatiana; 10.1117/12.347399


    The design and operating of a portable holographic interferometer for residual stress analysis by creating a small scratch along with a new mathematical algorithm of calculations are discussed. Preliminary data of the stress investigations on aluminum and steel alloys have been obtained by the automatic processing of the interference pattern using a notebook computer. A phase-shift compensation technique in real-time reflection interferometry is used to measure the out-of-plane stress release surface displacement surrounding a small scratch (25 um depth and 0.5 mm width) in a plate with residual stress of around 50 MPa. Comparison between theoretical models for a rectangular and triangular shaped scratch with the experimental data are presented.

  18. Force transducers based on the stress dependence of coercive force

    Garshelis, I. J.


    An alternative measurement regime for magnetoelastic force transducers, based on variations in coercive field, is described. Hc is shown to be more directly related to the primary magnetic influence of stress, namely, the orientation of effective anisotropy, than conventionally used magnetization related parameters. The stress dependence of Hc is shown to generally reflect opposing factors associated with rotational and wall displacement magnetization reversal processes. In materials wherein Hc≪K/Ms wall motion dominates and if the product of λs/K and yield stress is high enough, large monotonic reductions of Hc with positive (tensile) stress are shown to be possible. A more complex variation of Hc with increasing compression is similarly expected. Experimental results from a transducer having an 18% Ni maraging steel core support these expectations.

  19. Projectile Base Flow Analysis


    S) AND ADDRESS(ES) DCW Industries, Inc. 5354 Palm Drive La Canada, CA 91011 8. PERFORMING ORGANIZATION...REPORT NUMBER DCW -38-R-05 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) U. S. Army Research Office...Turbulence Modeling for CFD, Second Edition, DCW Industries, Inc., La Cañada, CA. Wilcox, D. C. (2001), “Projectile Base Flow Analysis,” DCW

  20. Phosphoproteomic analysis of the response of maize leaves to drought, heat and their combination stress

    Xiuli eHu


    Full Text Available Drought and heat stress, especially their combination, greatly affect crop production. Many studies have described transcriptome, proteome and phosphoproteome changes in response of plants to drought or heat stress. However, the study about the phosphoproteomic changes in response of crops to the combination stress is scare. To understand the mechanism of maize responses to the drought and heat combination stress, phosphoproteomic analysis was performed on maize leaves by using multiplex iTRAQ-based quantitative proteomic and LC-MS/MS methods. Five-leaf-stage maize was subjected to drought, heat or their combination, and the leaves were collected. Globally, heat, drought and the combined stress significantly changed the phosphorylation levels of 172, 149 and 144 phosphopeptides, respectively. These phosphopeptides corresponded to 282 proteins. Among them, 23 only responded to the combined stress and could not be predicted from their responses to single stressors; 30 and 75 only responded to drought and heat, respectively. Notably, 19 proteins were phosphorylated on different sites in response to the single and combination stresses. Of the seven significantly enriched phosphorylation motifs identified, two were common for all stresses, two were common for heat and the combined stress, and one was specific to the combined stress. The signaling pathways in which the phosphoproteins were involved clearly differed among the three stresses. Functional characterization of the phosphoproteins and the pathways identified here could lead to new targets for the enhancement of crop stress tolerance, which will be particularly important in the face of climate change and the increasing prevalence of abiotic stressors.

  1. Thermal elasto-plastic stress analysis during laser heating of a metal plate

    Chen, Yanbei; Lu, Jian; Ni, Xiaowu


    During laser heating of a metal material, the continuity of material confines its free expansion, thermal stresses arise. On one hand the thermal expansion of the heated zone of the material increases with the increase of temperature, the thermal stress level increases correspondingly; on the other hand the mechanical properties of the material will change with the increase of temperature, especially the elastic modulus, yield strength and tensile strength drop significantly, which is the so-called thermal softening problem. Due to the effect of the two factors, as the heating time or the intensity of the laser beam increases, it is possible that the stress levels of the heated zone of the material exceed the yield strength, which leads the material to come into a plastic stage. Thus, a thermal plastic problem occurs. In this study, thermal elasto-plastic stresses during laser heating of a metal plate are computed by the finite element method (FEM) based on thermal elasto-plastic constitutive theory. The mechanical behaviors of the metal material during the laser heating are analyzed. By the analysis of the results, it is found that thermal expansion leads to the increase of stress level early during the laser irradiating, and thermal softening causes the decrease of stress levels in the plastic zone and the slow growth and even decrease of stress levels in elastic zone later. The radial stresses are all compressive stresses, and the hoop stresses are compressive stresses within about the laser spot and are tensile stresses at other place. This work may be beneficial to the laser processing of metal materials.

  2. Image decomposition as a tool for validating stress analysis models

    Mottershead J.


    Full Text Available It is good practice to validate analytical and numerical models used in stress analysis for engineering design by comparison with measurements obtained from real components either in-service or in the laboratory. In reality, this critical step is often neglected or reduced to placing a single strain gage at the predicted hot-spot of stress. Modern techniques of optical analysis allow full-field maps of displacement, strain and, or stress to be obtained from real components with relative ease and at modest cost. However, validations continued to be performed only at predicted and, or observed hot-spots and most of the wealth of data is ignored. It is proposed that image decomposition methods, commonly employed in techniques such as fingerprinting and iris recognition, can be employed to validate stress analysis models by comparing all of the key features in the data from the experiment and the model. Image decomposition techniques such as Zernike moments and Fourier transforms have been used to decompose full-field distributions for strain generated from optical techniques such as digital image correlation and thermoelastic stress analysis as well as from analytical and numerical models by treating the strain distributions as images. The result of the decomposition is 101 to 102 image descriptors instead of the 105 or 106 pixels in the original data. As a consequence, it is relatively easy to make a statistical comparison of the image descriptors from the experiment and from the analytical/numerical model and to provide a quantitative assessment of the stress analysis.

  3. Effect of mindfulness-based stress reduction on sleep quality

    Andersen, Signe; Würtzen, Hanne; Steding-Jessen, Marianne;


    The prevalence of sleep disturbance is high among cancer patients, and the sleep problems tend to last for years after the end of treatment. As part of a large randomized controlled clinical trial (the MICA trial, NCT00990977) of the effect of mindfulness-based stress reduction (MBSR) on psycholo......The prevalence of sleep disturbance is high among cancer patients, and the sleep problems tend to last for years after the end of treatment. As part of a large randomized controlled clinical trial (the MICA trial, NCT00990977) of the effect of mindfulness-based stress reduction (MBSR...

  4. The Interlayer Stress Analysis of Polyethylene-steel Composite Pipes

    WEI Xu-guang


    Polyethylene-steel Composite Pipes is widely used in conveying corrosive media occasions, but the pipe may lose effectiveness in the process of transporting hot and cold media, so the research of stress distribution and variation in polyethylene-steel composite pipes is very necessary.This article first assume that a thin adhesive layer is in between the polyethylene and steel, the adhesive layer along the axial shear stress is the major cause of the polyethylene layer and the steel pipe off sticky.Secondly, we use a method of finite element to computer simulation by ANSYS, and verify initial assumptions. Finally, based on simulation data, we analyse the adhesive layer stress distribution and the variation with different parameters to change.Through the above research, preliminarily summarize the variation and distribution of interlaminar stress, and provide technical support for future design and process improvement of polyethylenesteel pipe.

  5. Effective stress analysis method of seismic response for high tailings dam

    LIU Hou-xiang; LI Ning; LIAO Xue; WU Cong-shi; PAN Xu-dong


    Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diflusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam's acceleration, seismic dynamic stress and pore water pressure were obtained.The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly.The interior stress is compressive stress.the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.O. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method.The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams'stability during earthquake is secondary reason.

  6. Study on Real-Time Simulation Analysis and Inverse Analysis System for Temperature and Stress of Concrete Dam

    Lei Zhang


    Full Text Available In the concrete dam construction, it is very necessary to strengthen the real-time monitoring and scientific management of concrete temperature control. This paper constructs the analysis and inverse analysis system of temperature stress simulation, which is based on various useful data collected in real time in the process of concrete construction. The system can produce automatically data file of temperature and stress calculation and then achieve the remote real-time simulation calculation of temperature stress by using high performance computing techniques, so the inverse analysis can be carried out based on a basis of monitoring data in the database; it fulfills the automatic feedback calculation according to the error requirement and generates the corresponding curve and chart after the automatic processing and analysis of corresponding results. The system realizes the automation and intellectualization of complex data analysis and preparation work in simulation process and complex data adjustment in the inverse analysis process, which can facilitate the real-time tracking simulation and feedback analysis of concrete temperature stress in construction process and enable you to discover problems timely, take measures timely, and adjust construction scheme and can well instruct you how to ensure project quality.

  7. Circular cylinders and pressure vessels stress analysis and design

    Vullo, Vincenzo


    This book provides comprehensive coverage of stress and strain analysis of circular cylinders and pressure vessels, one of the classic topics of machine design theory and methodology. Whereas other books offer only a partial treatment of the subject and frequently consider stress analysis solely in the elastic field, Circular Cylinders and Pressure Vessels broadens the design horizons, analyzing theoretically what happens at pressures that stress the material beyond its yield point and at thermal loads that give rise to creep. The consideration of both traditional and advanced topics ensures that the book will be of value for a broad spectrum of readers, including students in postgraduate, and doctoral programs and established researchers and design engineers. The relations provided will serve as a sound basis for the design of products that are safe, technologically sophisticated, and compliant with standards and codes and for the development of innovative applications.

  8. A Study on the Job Stress Assessment in Korean Nuclear Power Plants based on KOSS

    Hwang, Seong Hwan; Lee, Yong Hee; Lee, Jung Woon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Sung, Sook Hee; Jung, Kwang Hee; Jung, Yeon Sub [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)


    Job stress is a harmful physical and emotional response that occurs when there is a poor match between job demands and the capabilities, resources, or needs of the worker. Stress-related disorders encompass a broad array of conditions, including psychological disorders (e.g., depression, anxiety, posttraumatic stress disorder) and other types of emotional strain (e.g., dissatisfaction, fatigue, tension, etc.), maladaptive behaviors (e.g., aggression, substance abuse), and cognitive impairment (e.g., concentration and memory problems). In turn, these conditions may lead to poor work performance or even injury. Job stress is also associated with various biological reactions that may lead ultimately to compromised health, such as cardiovascular disease or in extreme cases, death. In Korea, organizational job stress factors were investigated for the jobs in nuclear power plants that are operated based on procedures. Especially, the occupational stress scale for Korean employees (KOSS) was developed. The KOSS has 8 subscales by using a factor analysis and validation process in order to measure stress at work and to find methods for the prevention of stressors. In this point of view, the RHRI (Radiation Health Research Institute of KHNP (Korea Hydro and Nuclear Power) assessed how wellsuited employees were for their job during their health examination in 2009. In this study the present condition of employee's stress level is investigated to find a way to manage their stressors

  9. Visible spectrum-based non-contact HRV and dPTT for stress detection

    Kaur, Balvinder; Hutchinson, J. Andrew; Ikonomidou, Vasiliki N.


    Stress is a major health concern that not only compromises our quality of life, but also affects our physical health and well-being. Despite its importance, our ability to objectively detect and quantify it in a real-time, non-invasive manner is very limited. This capability would have a wide variety of medical, military, and security applications. We have developed a pipeline of image and signal processing algorithms to make such a system practical, which includes remote cardiac pulse detection based on visible spectrum videos and physiological stress detection based on the variability in the remotely detected cardiac signals. First, to determine a reliable cardiac pulse, principal component analysis (PCA) was applied for noise reduction and independent component analysis (ICA) was applied for source selection. To determine accurate cardiac timing for heart rate variability (HRV) analysis, a blind source separation method based least squares (LS) estimate was used to determine signal peaks that were closely related to R-peaks of the electrocardiogram (ECG) signal. A new metric, differential pulse transit time (dPTT), defined as the difference in arrival time of the remotely acquired cardiac signal at two separate distal locations, was derived. It was demonstrated that the remotely acquired metrics, HRV and dPTT, have potential for remote stress detection. The developed algorithms were tested against human subject data collected under two physiological conditions using the modified Trier Social Stress Test (TSST) and the Affective Stress Response Test (ASRT). This research provides evidence that the variability in remotely-acquired blood wave (BW) signals can be used for stress (high and mild) detection, and as a guide for further development of a real-time remote stress detection system based on remote HRV and dPTT.

  10. Stress corrosion cracking in canistered waste package containers: Welds and base metals

    Huang, J.S.


    The current design of waste package containers include outer barrier using corrosion allowable material (CAM) such as A516 carbon steel and inner barrier of corrosion resistant material (CRM) such as alloy 625 and C22. There is concern whether stress corrosion cracking would occur at welds or base metals. The current memo documents the results of our analysis on this topic.

  11. Mindfulness Based Stress Reduction for Academic Evaluation Anxiety: A Naturalistic Longitudinal Study

    Dundas, Ingrid; Thorsheim, Torbjørn; Hjeltnes, Aslak; Binder, Per Einar


    Mindfulness based stress reduction (MBSR) for academic evaluation anxiety and self-confidence in 70 help-seeking bachelor's and master's students was examined. A repeated measures analysis of covariance on the 46 students who completed pretreatment and posttreatment measures (median age = 24 years, 83% women) showed that evaluation anxiety and…

  12. Residual stress analysis of drive shafts after induction hardening

    Lemos, Guilherme Vieira Braga; Rocha, Alexandre da Silva; Nunes, Rafael Menezes, E-mail: [Universidade Federal do Rio Grande do Sul (UFRS), Porto Algre, RS (Brazil); Hirsch, Thomas Karl [Stiftung Institut für Werkstofftechnik (IWT), Bremen (Germany)


    Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable diffractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected. (author)

  13. Stress distribution on dentin-cement-post interface varying root canal and glass fiber post diameters. A three-dimensional finite element analysis based on micro-CT data.

    Lazari, Priscilla Cardoso; Oliveira, Rodrigo Caldeira Nunes de; Anchieta, Rodolfo Bruniera; Almeida, Erika Oliveira de; Freitas Junior, Amilcar Chagas; Kina, Sidney; Rocha, Eduardo Passos


    The aim of the present study was to analyze the influence of root canal and glass fiber post diameters on the biomechanical behavior of the dentin/cement/post interface of a root-filled tooth using 3D finite element analysis. Six models were built using micro-CT imaging data and SolidWorks 2007 software, varying the root canal (C) and the glass fiber post (P) diameters: C1P1-C=1 mm and P=1 mm; C2P1-C=2 mm and P=1 mm; C2P2-C=2 mm and P=2 mm; C3P1-C=3 mm and P=1 mm; C3P2-C=3 mm and P=2 mm; and C3P3-C=3 mm and P=3 mm. The numerical analysis was conducted with ANSYS Workbench 10.0. An oblique force (180 N at 45º) was applied to the palatal surface of the central incisor. The periodontal ligament surface was constrained on the three axes (x=y=z=0). Maximum principal stress (σ(max)) values were evaluated for the root dentin, cement layer, and glass fiber post. The most evident stress was observed in the glass fiber post at C3P1 (323 MPa), and the maximum stress in the cement layer occurred at C1P1 (43.2 MPa). The stress on the root dentin was almost constant in all models with a peak in tension at C2P1 (64.5 MPa). The greatest discrepancy between root canal and post diameters is favorable for stress concentration at the post surface. The dentin remaining after the various root canal preparations did not increase the stress levels on the root.

  14. Quantum hydrodynamic analysis of decoherence: quantum trajectories and stress tensor

    Na, Kyungsun; Wyatt, Robert E


    Quantum trajectories, obtained by integrating equations of motion for elements of the probability fluid, are used to analyze decoherence in a model two-mode system. Analysis of trajectories, flux maps, and the stress tensor for two composite systems, in one of which the system is uncoupled from the environment, leads to a hydrodynamic interpretation of the decoherence process.

  15. The Psychophysiology of Posttraumatic Stress Disorder: A Meta-Analysis

    Pole, Nnamdi


    This meta-analysis of 58 resting baseline studies, 25 startle studies, 17 standardized trauma cue studies, and 22 idiographic trauma cue studies compared adults with and without posttraumatic stress disorder (PTSD) on psychophysiological variables: facial electromyography (EMG), heart rate (HR), skin conductance (SC), and blood pressure.…

  16. Piping Stress Analysis of Secondary Cooling Water System in CARR


    Some piping valves of China Advanced Research Reactor (CARR) cannot maintain the leak tightness when debugging. Because the valves need to be exchanged, the stress analysis and evaluation should be made for the piping with new valves in order to make sure whether

  17. Stress analysis of portable safety platform (Core Sampler Truck)

    Ziada, H.H.


    This document provides the stress analysis and evaluation of the portable platform of the rotary mode core sampler truck No. 2 (RMCST {number_sign}2). The platform comprises railing, posts, deck, legs, and a portable ladder; it is restrained from lateral motion by means of two brackets added to the drill-head service platform.

  18. An Integrated Analysis of Changes in Water Stress in Europe

    Henrichs, T.; Lehner, B.; Alcamo, J.


    Future changes in water availability with climate change and changes in water use due to socio-economic development are to occur in parallel. In an integrated analysis we bring together these aspects of global change in a consistent manner, and analyse the water stress situation in Europe. We find...

  19. Polymer-based stress sensor with integrated readout

    Thaysen, Jacob; Yalcinkaya, Arda Deniz; Vettiger, P.


    We present a polymer-based mechanical sensor with an integrated strain sensor element. Conventionally, silicon has been used as a piezoresistive material due to its high gauge factor and thereby high sensitivity to strain changes in the sensor. By using the fact that the polymer SU-8 [1] is much...... softer than silicon and that a gold resistor is easily incorporated in SU-8, we have proven that a SU-8-based cantilever sensor is almost as sensitive to stress changes as the silicon piezoresistive cantilever. First, the surface stress sensing principle is discussed, from which it can be shown...... that the SU-8-based sensor is nearly as sensitive as the silicon based mechanical sensor. We hereafter demonstrate the chip fabrication technology of such a sensor, which includes multiple SU-8 and gold layer deposition. The SU-8-based mechanical sensor is finally characterized with respect to sensitivity...

  20. Fatigue Strength and Residual Stress Analysis of Deep Rolled Crankshafts

    Imran M Quraishi


    Full Text Available The endurance life of an engine crankshaft is closely related to its fatigue strength, in addition to other material properties and shape parameters. Deep rolling, moreover, enhances the fatigue limit by applying compressive residual stress within the fillet radius area as a major surface hardening technique. The objective of this paper isto maximize fatigue life of engine through crankshaft design optimization by quantifying fatigue strength for microalloyed steels versus Cr-Mo alloy steel, and to examine the effects of deep rolling load and rolled fillet geometry. Fatigue tests have been made with standard rotary bending test samples from both bar and forged blanks. Rig tests for actual crankshafts have been made to show how the fatigue strength correlates with different sample types. A correlation of stress distribution with bending moment was demonstrated by applying a strain gauging technique on crankshaft specimens. Therefore, an analysis of combined stresses could be made by considering the effect of static residual stress in addition to the applied dynamic bending stress. Optimum conditions for rolling load, fillet geometry and material were identified. Consequently, these results will be adapted to CAE analysis database to enable an optimization of safety factors.

  1. Contact Stress Analysis for Gears of Different Helix Angle Using Finite Element Method

    Patil Santosh


    Full Text Available The gear contact stress problem has been a great point of interest for many years, but still an extensive research is required to understand the various parameters affecting this stress. Among such parameters, helix angle is one which has played a crucial role in variation of contact stress. Numerous studies have been carried out on spur gear for contact stress variation. Hence, the present work is an attempt to study the contact stresses among the helical gear pairs, under static conditions, by using a 3D finite element method. The helical gear pairs on which the analysis is carried are 0, 5, 15, 25 degree helical gear sets. The Lagrange multiplier algorithm has been used between the contacting pairs to determine the stresses. The helical gear contact stress is evaluated using FE model and results have also been found at different coefficient of friction, varying from 0.0 to 0.3. The FE results have been further compared with the analytical calculations. The analytical calculations are based upon Hertz and AGMA equations, which are modified to include helix angle. The commercial finite element software was used in the study and it was shown that this approach can be applied to gear design efficiently. The contact stress results have shown a decreasing trend, with increase in helix angle.

  2. Analysis of Thermal History and Residual Stress in Cold-Sprayed Coatings

    Arabgol, Z.; Assadi, H.; Schmidt, T.; Gärtner, F.; Klassen, T.


    Residual stress in coatings has significant effect on their performance. In cold-sprayed coatings, in which particles impact the substrate at high velocity in solid state, in-plane residual stresses are usually conceived to be compressive. In this research, analysis of residual stresses in cold-sprayed deposits is performed by analytical and numerical modeling. The influence of various parameters such as the dimensions and elastic properties of the coating and the substrate on the residual stress are analyzed. In addition, the amount of heat input as a key parameter in the build-up of the residual stress is examined. It has been found that the heat input and the associated thermal history have a major influence on the final distortion and the residual stress, to an extent that the in-plane stress can in some cases change from compressive to tensile. Based on these results, a simple model is put forward for the prediction of the final state of the stress and distortion in cold-sprayed flat components.

  3. Temperature Based Stress Analysis of Notched Members


    technical report has been reviewed and is approved for publication. GENE E. MADDUX NELSON D. WOLF, Acting Chief Project Engineer Structural Integrity...Laplacian operator q = time rate of heat generation per unit volume k = thermal conductivity D = thermal diffusivity = kpc t = time 22 If a system undergoes

  4. Analysis of Residual Stress and Deformation of Rolling Strengthen Crankshaft Fillet

    Han Shaojun


    Full Text Available Based on the analysis of crankshaft fillet rolling process, used ANSYS finite element analysis software to conduct the elastic-plastic mechanical simulation of crankshaft rolling process, and gained the variation law of the residual stress and plastic deformation in the radial path of the fillet under different rolling laps and rolling pressure. Established the relationship between the rolling pressure and the plastic deformation and residual stress of the fillet, and provided theoretical support for the evaluation and detection of the crankshaft rolling quality.

  5. StressPhone: smartphone based platform for measurement of cortisol for stress detection (Conference Presentation)

    Jain, Aadhar; Rey, Elizabeth; Lee, Seoho; O'Dell, Dakota; Erickson, David


    Anxiety disorders are estimated to be the most common mental illness in US affecting around 40 million people and related job stress is estimated to cost US industry up to $300 billion due to lower productivity and absenteeism. A personal diagnostic device which could help identify stressed individuals would therefore be a huge boost for workforce productivity. We are therefore developing a point of care diagnostic device that can be integrated with smartphones or tablets for the measurement of cortisol - a stress related salivary biomarker, which is known to be strongly involved in body's fight-or-flight response to a stressor (physical or mental). The device is based around a competitive lateral flow assay whose results can then be read and quantified through an accessory compatible with the smartphone. In this presentation, we report the development and results of such an assay and the integrated device. We then present the results of a study relating the diurnal patterns of cortisol levels and the alertness of an individual based on the circadian rhythm and sleep patterns of the individual. We hope to use the insight provided by combining the information provided by levels of stress related to chemical biomarkers of the individual with the physical biomarkers to lead to a better informed and optimized activity schedule for maximized work output.

  6. Discovery of biomarkers for oxidative stress based on cellular metabolomics.

    Wang, Ningli; Wei, Jianteng; Liu, Yewei; Pei, Dong; Hu, Qingping; Wang, Yu; Di, Duolong


    Oxidative stress has a close relationship with various pathologic physiology phenomena and the potential biomarkers of oxidative stress may provide evidence for clinical diagnosis or disease prevention. Metabolomics was employed to identify the potential biomarkers of oxidative stress. High-performance liquid chromatography-diode array detector, mass spectrometry and partial least squares discriminate analysis were used in this study. The 10, 15 and 13 metabolites were considered to discriminate the model group, vitamin E-treated group and l-glutathione-treated group, respectively. Some of them have been identified, namely, malic acid, vitamin C, reduced glutathione and tryptophan. Identification of other potential biomarkers should be conducted and their physiological significance also needs to be elaborated.



    There is a cyclical aperture at a certain part of the fiberglass reinforced plastic compound pipeline with a stainless steel pipe as a liner, which becomes the weakness of the conduit. The field of stress and strain of the aperture was investigated using the nonliner finite element code Marc. The results of the finite element analysis showed that there were concentrations of stress and strain in the layer of stainless steel at the part of the pipeline where the aperture existed. The method to solve these problems was also discussed.

  8. The stress analysis of a heavy liquid metal pump impeller

    Ma, X. D.; Li, X. L.; Zhu, Z. Q.; Li, C. J.; Gao, S.


    Lead-based coolant reactor is a promising Generation-IV reactor. In the lead-based coolant reactor, the coolant is liquid lead or lead-bismuth eutectic. The main pump in the reactor is a very important device. It supplies force for the coolant circulation. The liquid metal has a very large density which is about ten times of the water. Also, the viscosity of the coolant is small which is about one sixth of the water. When the pump transports heavy liquid, the blade loading is heavy. The large force can cause the failure of the blade when the fatigue stress exceeds the allowable stress. The impeller fraction is a very serious accident which is strictly prohibited in the nuclear reactor. In this paper, the numerical method is used to simulate the flow field of a heavy liquid metal pump. The SST k-w turbulent model is used in the calculation to get a more precise flow structure. The hydraulic force is obtained with the one way fluid solid coupling. The maximum stress in the impeller is analyzed. The stress in the liquid metal pump is compared with that in the water pump. The calculation results show that the maximum stress of the impeller blade increases with increase of flow rate. In the design of the impeller blade thickness, the impeller strength in large operating condition should be considered. The maximum stress of the impeller blade located in the middle and near the hub of the leading edge. In this position, the blade is easy to fracture. The maximum deformation of the impeller firstly increase with increase of flow rate and then decrease with increase of flow rate. The maximum deformation exists in the middle of the leading edge when in small flow rate and in the out radius of the impeller when in large flow rate. Comparing the stress of the impeller when transporting water and LBE, the maximum stress is almost one-tenth of that in the LBE impeller which is the same ratio of the density. The static stress in different medium is proportional to the pressure

  9. Systems analysis of oxidant stress in the vasculature.

    Handy, Diane E; Loscalzo, Joseph; Leopold, Jane A


    Systems biology and network analysis are emerging as valuable tools for the discovery of novel relationships, the identification of key regulatory factors, and the prediction of phenotypic changes in complex biological systems. Redox homeostasis in the vasculature is maintained by an intricate balance between oxidant-generating and antioxidant systems. When these systems are perturbed, conditions are permissive for oxidant stress, which, in turn, promotes vascular dysfunction and structural remodeling. Owing to the number of elements involved in redox regulation and the different vascular pathophenotypes associated with oxidant stress, vascular oxidant stress represents an ideal system to study by network analysis. Networks offer a method to organize experimentally derived factors, including proteins, metabolites, and DNA, that are represented as nodes into an unbiased comprehensive platform for study. Through analysis of the network, it is possible to determine essential or regulatory nodes, identify previously unknown connections between nodes, and locate modules, which are groups of nodes located within the same neighborhood that function together and have implications for phenotype. Investigators have only recently begun to construct oxidant stress-related networks to examine vascular structure and function; however, these early studies have provided mechanistic insight to further our understanding of this complicated biological system. © 2013 International Union of Biochemistry and Molecular Biology.

  10. Inserting Stress Analysis of Combined Hexagonal Aluminum Honeycombs

    Xiangcheng Li


    Full Text Available Two kinds of hexagonal aluminum honeycombs are tested to study their out-of-plane crushing behavior. In the tests, honeycomb samples, including single hexagonal aluminum honeycomb (SHAH samples and two stack-up combined hexagonal aluminum honeycombs (CHAH samples, are compressed at a fixed quasistatic loading rate. The results show that the inserting process of CHAH can erase the initial peak stress that occurred in SHAH. Meanwhile, energy-absorbing property of combined honeycomb samples is more beneficial than the one of single honeycomb sample with the same thickness if the two types of honeycomb samples are completely crushed. Then, the applicability of the existing theoretical model for single hexagonal honeycomb is discussed, and an area equivalent method is proposed to calculate the crushing stress for nearly regular hexagonal honeycombs. Furthermore, a semiempirical formula is proposed to calculate the inserting plateau stress of two stack-up CHAH, in which structural parameters and mechanics properties of base material are concerned. The results show that the predicted stresses of three kinds of two stack-up combined honeycombs are in good agreement with the experimental data. Based on this study, stress-displacement curve of aluminum honeycombs can be designed in detail, which is very beneficial to optimize the energy-absorbing structures in engineering fields.

  11. The stress shadow problem in physics-based aftershock forecasting: Does incorporation of secondary stress changes help?

    Segou, M.; Parsons, T.


    Main shocks are calculated to cast stress shadows across broad areas where aftershocks occur. Thus, a key problem with stress-based operational forecasts is that they can badly underestimate aftershock occurrence in the shadows. We examine the performance of two physics-based earthquake forecast models (Coulomb rate/state (CRS)) based on Coulomb stress changes and a rate-and-state friction law for their predictive power on the 1989 Mw = 6.9 Loma Prieta aftershock sequence. The CRS-1 model considers the stress perturbations associated with the main shock rupture only, whereas CRS-2 uses an updated stress field with stresses imparted by M ≥ 3.5 aftershocks. Including secondary triggering effects slightly improves predictability, but physics-based models still underestimate aftershock rates in locations of initial negative stress changes. Furthermore, CRS-2 does not explain aftershock occurrence where secondary stress changes enhance the initial stress shadow. Predicting earthquake occurrence in calculated stress shadow zones remains a challenge for stress-based forecasts, and additional triggering mechanisms must be invoked.

  12. Interlaminar Stresses by Refined Beam Theories and the Sinc Method Based on Interpolation of Highest Derivative

    Slemp, Wesley C. H.; Kapania, Rakesh K.; Tessler, Alexander


    Computation of interlaminar stresses from the higher-order shear and normal deformable beam theory and the refined zigzag theory was performed using the Sinc method based on Interpolation of Highest Derivative. The Sinc method based on Interpolation of Highest Derivative was proposed as an efficient method for determining through-the-thickness variations of interlaminar stresses from one- and two-dimensional analysis by integration of the equilibrium equations of three-dimensional elasticity. However, the use of traditional equivalent single layer theories often results in inaccuracies near the boundaries and when the lamina have extremely large differences in material properties. Interlaminar stresses in symmetric cross-ply laminated beams were obtained by solving the higher-order shear and normal deformable beam theory and the refined zigzag theory with the Sinc method based on Interpolation of Highest Derivative. Interlaminar stresses and bending stresses from the present approach were compared with a detailed finite element solution obtained by ABAQUS/Standard. The results illustrate the ease with which the Sinc method based on Interpolation of Highest Derivative can be used to obtain the through-the-thickness distributions of interlaminar stresses from the beam theories. Moreover, the results indicate that the refined zigzag theory is a substantial improvement over the Timoshenko beam theory due to the piecewise continuous displacement field which more accurately represents interlaminar discontinuities in the strain field. The higher-order shear and normal deformable beam theory more accurately captures the interlaminar stresses at the ends of the beam because it allows transverse normal strain. However, the continuous nature of the displacement field requires a large number of monomial terms before the interlaminar stresses are computed as accurately as the refined zigzag theory.

  13. Cardiorespiratory fitness and laboratory stress: a meta-regression analysis.

    Jackson, Erica M; Dishman, Rod K


    We performed a meta-regression analysis of 73 studies that examined whether cardiorespiratory fitness mitigates cardiovascular responses during and after acute laboratory stress in humans. The cumulative evidence indicates that fitness is related to slightly greater reactivity, but better recovery. However, effects varied according to several study features and were smallest in the better controlled studies. Fitness did not mitigate integrated stress responses such as heart rate and blood pressure, which were the focus of most of the studies we reviewed. Nonetheless, potentially important areas, particularly hemodynamic and vascular responses, have been understudied. Women, racial/ethnic groups, and cardiovascular patients were underrepresented. Randomized controlled trials, including naturalistic studies of real-life responses, are needed to clarify whether a change in fitness alters putative stress mechanisms linked with cardiovascular health.

  14. A Suggested Stress Analysis Procedure For Nozzle To Head Shell Element Model – A Case Study

    Sanket S. Chaudhari


    Full Text Available Stress analysis of pressure vessel has been always a serious and a critical analysis. The paper performs a standard procedure of pressure vessel analysis and validation based on previous papers. It also demonstrates the most critical part and how it affects entire structure. Relevant ASME (ASME, 2004, ASME Boiler and Pressure Vessel Code, Section VIII, Division 2, American Society of Mechanical Engineers, New York norms are produced to explain analysis procedure. WRC (Welding research council methodology is explained to validate finite element analysis work

  15. Evaluation of an app-based stress protocol

    Noeh Claudius


    Full Text Available Stress is a major influence on the quality of life in our fast-moving society. This paper describes a standardized and contemporary protocol that is capable of inducing moderate psychological stress in a laboratory setting. Furthermore, it evaluates its effects on physiological biomarkers. The protocol called “THM-Stresstest” mainly consists of a rest period (30 min, an app-based stress test under the surveillance of an audience (4 min and a regeneration period (32 min. We investigated 12 subjects to evaluate the developed protocol. We could show significant changes in heart rate variability, electromyography, electro dermal activity and salivary cortisol and α-amylase. From this data we conclude that the THM-Stresstest can serve as a psychobiological tool for provoking responses in the cardiovascular-, the endocrine and exocrine system as well as the sympathetic part of the central nervous system.

  16. Study on residual stresses of Ni-based WC coating by laser remelting based on XRD

    Chen, Zhigang; Kong, Dejun; Wang, Ling; Zhu, Xiaoron; Zhao, Xiaobing


    The morphologies of Ni-based WC coating by flame spraying and laser cladding respectively were observed with scanning electric microscope (SEM), respectively, and residual stresses were measured with XRD (X-ray diffraction). At the same time, the spectra of WC coating were analyzed by XRD, and the forming mechanisms of residual stress were analyzed. Experimental results are shown that residual stresses of Ni-based WC coating by flame spraying are all tensile while those by laser cladding are compressive, chemical-physical reaction of the coating is the cause to result in material volume change, which makes residual stress into compressive from tensile; when residual stress is changed into compressive from tensile, micro-cracks on the coating surface greatly decrease, which is illustrated that the effect of residual stress on micro-crack is obvious; XRD spectra peak of WC coating is only contained Ni and W, and has no impurity and other reaction productions.

  17. Transcriptional analysis implicates endoplasmic reticulum stress in bovine spongiform encephalopathy.

    Yue Tang

    Full Text Available Bovine spongiform encephalopathy (BSE is a fatal, transmissible, neurodegenerative disease of cattle. To date, the disease process is still poorly understood. In this study, brain tissue samples from animals naturally infected with BSE were analysed to identify differentially regulated genes using Affymetrix GeneChip Bovine Genome Arrays. A total of 230 genes were shown to be differentially regulated and many of these genes encode proteins involved in immune response, apoptosis, cell adhesion, stress response and transcription. Seventeen genes are associated with the endoplasmic reticulum (ER and 10 of these 17 genes are involved in stress related responses including ER chaperones, Grp94 and Grp170. Western blotting analysis showed that another ER chaperone, Grp78, was up-regulated in BSE. Up-regulation of these three chaperones strongly suggests the presence of ER stress and the activation of the unfolded protein response (UPR in BSE. The occurrence of ER stress was also supported by changes in gene expression for cytosolic proteins, such as the chaperone pair of Hsp70 and DnaJ. Many genes associated with the ubiquitin-proteasome pathway and the autophagy-lysosome system were differentially regulated, indicating that both pathways might be activated in response to ER stress. A model is presented to explain the mechanisms of prion neurotoxicity using these ER stress related responses. Clustering analysis showed that the differently regulated genes found from the naturally infected BSE cases could be used to predict the infectious status of the samples experimentally infected with BSE from the previous study and vice versa. Proof-of-principle gene expression biomarkers were found to represent BSE using 10 genes with 94% sensitivity and 87% specificity.

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

    Yao, H.-T. [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China); Xuan Fuzhen [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China)], E-mail:; Wang Zhengdong; Tu Shantung [School of Mechanical and Power Engineering, East China University of Science and Technology, 130, Meilong Street, PO Box 402, Shanghai 200237 (China)


    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.

  19. Fractal Analysis of Stress Sensitivity of Permeability in Porous Media

    Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Cai, Jianchao


    A permeability model for porous media considering the stress sensitivity is derived based on mechanics of materials and the fractal characteristics of solid cluster size distribution. The permeability of porous media considering the stress sensitivity is related to solid cluster fractal dimension, solid cluster fractal tortuosity dimension, solid cluster minimum diameter and solid cluster maximum diameter, Young's modulus, Poisson's ratio, as well as power index. Every parameter has clear physical meaning without the use of empirical constants. The model predictions of permeability show good agreement with those obtained by the available experimental expression. The proposed model may be conducible to a better understanding of the mechanism for flow in elastic porous media.

  20. Proteomic Analysis of Tomato Seedlings Response to Salt Stress

    Xue Zhao; Feng Han; Shihua Shen


    The two species (Solanum pimpinellifolium-PI and S.lycopersicum-MM) of tomato showed marked differences in their responses to NaCI stress.PI appeared to be more tolerant to salt than MM.Comparative two-dimensional electrophoresis revealed that 187 and 110 protein spots were differentially expressed in the roots of PI and MM,respectively,in response to salt stress.Out of these spots,a total of 96 and 61 proteins were identified by MALDI-TOF MS analysis.The proteins identified included many previously characterized stress-responsive proteins and others related to processes including scavenging for reactive species; metabolism of energy,signal transduction; protein synthesis,cell growth and differentiation et al.The role of some of the proteins involved in the antioxidant defense mechanism,ion transport and compartmentalization of ions,and cell signaling pathways were discussed.Collectively,this work suggest that PI has more efficient antioxidant and defense machinery than MM,and that this is important for adapting to salt stress and for withstanding the oxidative stress imposed by high salt levels.

  1. "The Program Affects Me 'Cause it Gives Away Stress": Urban Students' Qualitative Perspectives on Stress and a School-Based Mindful Yoga Intervention.

    Dariotis, Jacinda K; Cluxton-Keller, Fallon; Mirabal-Beltran, Roxanne; Gould, Laura Feagans; Greenberg, Mark T; Mendelson, Tamar

    School-based mindfulness and yoga studies generally measure stress-related outcomes using quantitative measures. This study answers the following research questions: How do youth define stress and in what ways, if any, was a mindful yoga intervention helpful to youth during stress experiences? To explore youths' own perspectives on stress, stressors in youths' lives, and perceived changes in responses to stress post-intervention, we conducted focus group discussions with 22 middle school students from low-income urban communities following a 16-week mindful yoga intervention. Using thematic analysis, the following three themes emerged: (1) youth conflated stress with negative emotions; (2) peer and family conflicts were common stressors; and (3) youth reported improved impulse control and emotional regulation following the intervention. Study findings have implications for refining intervention content (e.g., discussions of stress), as well as informing the selection and development of quantitative measures for future research on stress and stress responses in urban youth. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Environmental stress level evaluation approach based on physical model and interval grey association degree

    Deng Guanqian; Qiu Jing; Liu Guanjun; Lv Kehong


    Associating environmental stresses (ESs) with built-in test (BIT) output is an important means to help diagnose intermittent faults (IFs).Aiming at low efficiency in association of traditional time stress measurement device (TSMD),an association model is built.Thereafter,a novel approach is given to evaluate the integrated environmental stress (IES) level.Firstly,the selection principle and approach of main environmental stresses (MESs) and key characteristic parameters (KCPs) are presented based on fault mode,mechanism,and ESs analysis (FMMEA).Secondly,reference stress events (RSEs) are constructed by dividing IES into three stress levels according to its impact on faults; and then the association model between integrated environmental stress event (IESE) and BIT output is built.Thirdly,an interval grey association approach to evaluate IES level is proposed due to the interval number of IES value.Consequently,the association output can be obtained as well.Finally,a case study is presented to demonstrate the proposed approach.Results show the proposed model and approach are effective and feasible.This approach can be used to guide ESs measure,record,and association.It is well suited for on-line assistant diagnosis of faults,especially IFs.

  3. The effectiveness of a stress coping program based on mindfulness meditation on the stress, anxiety, and depression experienced by nursing students in Korea.

    Kang, Yune Sik; Choi, So Young; Ryu, Eunjung


    This study examined the effectiveness of a stress coping program based on mindfulness meditation on the stress, anxiety, and depression experienced by nursing students in Korea. A nonequivalent, control group, pre-posttest design was used. A convenience sample of 41 nursing students were randomly assigned to experimental (n=21) and control groups (n=20). Stress was measured with the PWI-SF (5-point) developed by Chang. Anxiety was measured with Spieberger's state anxiety inventory. Depression was measured with the Beck depression inventory. The experimental group attended 90-min sessions for eight weeks. No intervention was administered to the control group. Nine participants were excluded from the analysis because they did not complete the study due to personal circumstances, resulting in 16 participants in each group for the final analysis. Results for the two groups showed (1) a significant difference in stress scores (F=6.145, p=0.020), (2) a significant difference in anxiety scores (F=6.985, p=0.013), and (3) no significant difference in depression scores (t=1.986, p=0.056). A stress coping program based on mindfulness meditation was an effective intervention for nursing students to decrease their stress and anxiety, and could be used to manage stress in student nurses. In the future, long-term studies should be pursued to standardize and detail the program, with particular emphasis on studies to confirm the effects of the program in patients with diseases, such as cancer.

  4. Psychometric analysis of the Ten-Item Perceived Stress Scale.

    Taylor, John M


    Although the 10-item Perceived Stress Scale (PSS-10) is a popular measure, a review of the literature reveals 3 significant gaps: (a) There is some debate as to whether a 1- or a 2-factor model best describes the relationships among the PSS-10 items, (b) little information is available on the performance of the items on the scale, and (c) it is unclear whether PSS-10 scores are subject to gender bias. These gaps were addressed in this study using a sample of 1,236 adults from the National Survey of Midlife Development in the United States II. Based on self-identification, participants were 56.31% female, 77% White, 17.31% Black and/or African American, and the average age was 54.48 years (SD = 11.69). Findings from an ordinal confirmatory factor analysis suggested the relationships among the items are best described by an oblique 2-factor model. Item analysis using the graded response model provided no evidence of item misfit and indicated both subscales have a wide estimation range. Although t tests revealed a significant difference between the means of males and females on the Perceived Helplessness Subscale (t = 4.001, df = 1234, p < .001), measurement invariance tests suggest that PSS-10 scores may not be substantially affected by gender bias. Overall, the findings suggest that inferences made using PSS-10 scores are valid. However, this study calls into question inferences where the multidimensionality of the PSS-10 is ignored. 2015 APA, all rights reserved

  5. Stress Analysis in Managing the Region’s Budget Risks

    Natalya Pavlovna Pazdnikova


    Full Text Available The article addresses the implementation of budget risk management methods into the practices of governmental authorities. Drawing on the example of a particular region the article aims to demonstrate the possible methods of budget risk management. The authors refine the existing approaches to the notion of risk in its relation to budget system by introducing the notion of “budget risk.” Here the focus is the risk of default of budget spending in full which causes underfunding of territories and decrease in quality of life in the region. The authors have particularized the classification of budget risks and grouped together the criteria and factors which significantly influence the assessment and choice of method to manage budget risks. They hypothesize that budget risk is a financial risk. Therefore, the methods of financial risks management can be applied to budget risks management. The authors suggest a methodological approach to risk assessment based on correlation and regression analysis of program financing. The application of Kendall rank correlation coefficient allowed to assess the efficiency of budget spending on the implementation of state programs in Perm Krai. Two clusters — “Nature management and infrastructure” and “Public security” — turned out to be in the zone of high budget risk. The method of stress analysis, which consists in calculating Value at Risk (VaR, was applied to budget risks that in terms of probability are classified as critical. In order to assess risk as probability rate, the amount of Perm Krai deficit budget was calculated as induced variable from budget revenues and spending. The results demonstrate that contemporary management of public resources in the regions calls for the implementation of new management tools of higher quality and budget risk management is one of them.

  6. [Occupational stress situation analysis of different types of train drivers].

    Zhou, Wenhui; Gu, Guizhen; Wu, Hui; Yu, Shanfa


    To analyze the status of occupational stress in different types of train drivers. By using cluster sampling method, a cross-sectional study was conducted in 1 339 train drivers (including 289 passenger train drivers, 637 freight trains drivers, 339 passenger shunting train drivers, and 74 high speed rail drivers) from a Railway Bureau depot. The survey included individual factors, occupational stress factors, stress response factors and stress mitigating factors. The occupational stress factors, stress response factors and mitigating factors were measured by the revised effort-reward imbalance (ERI) model questionnaires and occupational stress measurement scale. By using the method of covariance analysized the difference of occupational stress factors of all types train drivers, the method of Stepwise regression was used to analyze the effection (R(2)) of occupational stress factors and stress mitigating factors on stress response factors. Covariance analysis as covariates in age, education level, length of service and marital status showed that the scores of ERI (1.58 ± 0.05), extrinsic effort (19.88 ± 0.44), rewards (23.43 ± 0.43), intrinsic effort (17.86 ± 0.36), physical environment (5.70 ± 0.22), social support (30.51 ± 0.88) and daily tension (10.27 ± 0.38 ) of high speed rail drivers were higher than other drivers (F values were 6.06, 11.32, 7.05, 13.25, 5.20, 9.48 and 6.14 respectively, P < 0.01), but the scores of emotional balance (4.15 ± 0.31) and positive emotion (2.06 ± 0.20) were lower than other drives (P < 0.01);the scores of psychological needs (10.48 ± 0.18), emotional balance (4.88 ± 0.16) and positive emotion (2.63 ± 0.10) of passenger train drivers were higher than other drivers (F values were 4.33 and 5.50 respectively, P < 0.01). The descending rank of the effect value on occupational stress factors and mitigating factors to depressive symptoms of train drivers was high speed rail drivers (R(2) = 0.64), passenger train drivers (R

  7. An Estimation Method of Stress in Soft Rock Based on In-situ Measured Stress in Hard Rock

    LI Wen-ping; LI Xiao-qin; SUN Ru-hua


    The law of variation of deep rock stress in gravitational and tectonic stress fields is analyzed based on the Hoek-Brown strength criterion. In the gravitational stress field, the rocks in the shallow area are in an elastic state and the deep, relatively soft rock may be in a plastic state. However, in the tectonic stress field, the relatively soft rock in the shallow area is in a plastic state and the deep rock in an elastic state. A method is proposed to estimate stress values in coal and soft rock based on in-situ measurements of hard rock. Our estimation method relates to the type of stress field and stress state. The equations of rock stress in various stress states are presented for the elastic, plastic and critical states. The critical state is a special stress state, which indicates the conversion of the elastic to the plastic state in the gravitational stress field and the conversion of the plastic to the elastic state in the tectonic stress field. Two cases studies show that the estimation method is feasible.

  8. Analysis of Deformation in Inconel 718 When the Stress Anomaly and Dynamic Strain Aging Coexist

    Follansbee, Paul S.


    Deformation in Inconel 718 in the presence of combined effects of the stress anomaly and dynamic strain aging is analyzed according to an internal state variable model formulation. The analysis relies on the availability of experimental data in regimes of behavior where both the stress anomaly and dynamic strain aging are absent. A model that introduces two internal state variables—one characterizing interactions of dislocations with solute atoms and one characterizing interaction of dislocations with precipitates—is shown to adequately describe the temperature and strain-rate dependence of the yield stress in several superalloy systems. Strain hardening is then added with a third internal state variable to enable description of the full stress-strain curve. These equations are extrapolated into regimes where the stress anomaly and dynamic strain aging are present to identify signatures of their effects and to compare to similar analyses in a variety of metal systems. Dynamic strain aging in Inconel 718 follows similar trends to those observed previously. The magnitude of the stress anomaly tracks measurements of stress vs test temperature in pure Ni3Al. Several trends in the strain-rate sensitivity of elevated temperature deformation in superalloys are identified based on limited availability of measurements over a wide range of strain rates or tests using strain-rate changes.


    QiuWei; KangYilan; SunQingchi; QinQinghua; LinYu


    Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure.In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical configuration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric field distribution, are analyzed by moirá interferometry experiment and finite element numerical simulation. Based on the above analysis,two optimized geometrical models are presented for the purpose of geometrical configuration selection, with which stress concentration can be reduced significantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is effectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model Ⅱ is 93.1% smaller than that in the conventional model.It is proved that stress concentration can be effectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.

  10. Computer-assisted measurement of perceived stress: an application for a community-based survey.

    Kimura, Tomoaki; Uchida, Seiya; Tsuda, Yasutami; Eboshida, Akira


    The assessment of stress is a key issue in health promotion policies as well as in treatment strategies for patients. The aim of this study was to confirm the accessibility and reliability of computer-assisted data collection for perceived stress measurement, using the Japanese version of the Perceived Stress Scale (JPSS), within the setting of a community-based survey. There were two groups of participants in this survey. One group responded to a Web-based application, and the other to the VBA of a spreadsheet software. The total scores of JPSS were almost normally distributed. The means of total scores of JPSS were 23.6 and 23.1. These results were lower than the previous study of JPSS. Since Cronbach's alpha coefficients in both surveys were more than 0.8, high reliability was demonstrated despite a number of computer-illiterate and/or aged participants. They felt that the spreadsheet form was easier to respond to. Two components were extracted with the Varimax rotation of principal component analysis, and these were named "perception of stress and stressors" and "behavior to stress". This finding suggests that it is possible to determine sub-scales. From the viewpoint of preventive medicine, it is expected that the JPSS applications will be utilized to investigate the relationship between stress and other factors such as lifestyle, environment and quality of life.

  11. A Comprehensive Analysis of the Dynamic Response to Aphidicolin-Mediated Replication Stress Uncovers Targets for ATM and ATMIN.

    Mazouzi, Abdelghani; Stukalov, Alexey; Müller, André C; Chen, Doris; Wiedner, Marc; Prochazkova, Jana; Chiang, Shih-Chieh; Schuster, Michael; Breitwieser, Florian P; Pichlmair, Andreas; El-Khamisy, Sherif F; Bock, Christoph; Kralovics, Robert; Colinge, Jacques; Bennett, Keiryn L; Loizou, Joanna I


    The cellular response to replication stress requires the DNA-damage-responsive kinase ATM and its cofactor ATMIN; however, the roles of this signaling pathway following replication stress are unclear. To identify the functions of ATM and ATMIN in response to replication stress, we utilized both transcriptomics and quantitative mass-spectrometry-based phosphoproteomics. We found that replication stress induced by aphidicolin triggered widespread changes in both gene expression and protein phosphorylation patterns. These changes gave rise to distinct early and late replication stress responses. Furthermore, our analysis revealed previously unknown targets of ATM and ATMIN downstream of replication stress. We demonstrate ATMIN-dependent phosphorylation of H2AX and of CRMP2, a protein previously implicated in Alzheimer's disease but not in the DNA damage response. Overall, our dataset provides a comprehensive resource for discovering the cellular responses to replication stress and, potentially, associated pathologies. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  12. A Comprehensive Analysis of the Dynamic Response to Aphidicolin-Mediated Replication Stress Uncovers Targets for ATM and ATMIN

    Abdelghani Mazouzi


    Full Text Available The cellular response to replication stress requires the DNA-damage-responsive kinase ATM and its cofactor ATMIN; however, the roles of this signaling pathway following replication stress are unclear. To identify the functions of ATM and ATMIN in response to replication stress, we utilized both transcriptomics and quantitative mass-spectrometry-based phosphoproteomics. We found that replication stress induced by aphidicolin triggered widespread changes in both gene expression and protein phosphorylation patterns. These changes gave rise to distinct early and late replication stress responses. Furthermore, our analysis revealed previously unknown targets of ATM and ATMIN downstream of replication stress. We demonstrate ATMIN-dependent phosphorylation of H2AX and of CRMP2, a protein previously implicated in Alzheimer’s disease but not in the DNA damage response. Overall, our dataset provides a comprehensive resource for discovering the cellular responses to replication stress and, potentially, associated pathologies.

  13. 13C based proteinogenic amino acid (PAA and metabolic flux ratio analysis of Lactococcus lactis reveals changes in pentose phosphate (PP pathway in response to agitation and temperature related stresses

    Kamalrul Azlan Azizan


    Full Text Available Lactococcus lactis subsp. cremoris MG1363 is an important starter culture for dairy fermentation. During industrial fermentations, L. lactis is constantly exposed to stresses that affect the growth and performance of the bacterium. Although the response of L. lactis to several stresses has been described, the adaptation mechanisms at the level of in vivo fluxes have seldom been described. To gain insights into cellular metabolism, 13C metabolic flux analysis and gas chromatography mass spectrometry (GC-MS were used to measure the flux ratios of active pathways in the central metabolism of L. lactis when subjected to three conditions varying in temperature (30°C, 37°C and agitation (with and without agitation at 150 rpm. Collectively, the concentrations of proteinogenic amino acids (PAAs and free fatty acids (FAAs were compared, and Pearson correlation analysis (r was calculated to measure the pairwise relationship between PAAs. Branched chain and aromatic amino acids, threonine, serine, lysine and histidine were correlated strongly, suggesting changes in flux regulation in glycolysis, the pentose phosphate (PP pathway, malic enzyme and anaplerotic reaction catalysed by pyruvate carboxylase (pycA. Flux ratio analysis revealed that glucose was mainly converted by glycolysis, highlighting the stability of L. lactis’ central carbon metabolism despite different conditions. Higher flux ratios through oxaloacetate (OAA from pyruvate (PYR reaction in all conditions suggested the activation of pyruvate carboxylate (pycA in L. lactis, in response to acid stress during exponential phase. Subsequently, more significant flux ratio differences were seen through the oxidative and non-oxidative pentose phosphate (PP pathways, malic enzyme, and serine and C1 metabolism, suggesting NADPH requirements in response to environmental stimuli. These reactions could play an important role in optimization strategies for metabolic engineering in L. lactis. Overall

  14. Application of a PVDF-based stress gauge in determining dynamic stress-strain curves of concrete under impact testing

    Meng, Yi; Yi, Weijian


    Polyvinylidene fluoride (PVDF) piezoelectric material has been successfully applied in many engineering fields and scientific research. However, it has rarely been used for direct measurement of concrete stresses under impact loading. In this paper, a new PVDF-based stress gauge was developed to measure concrete stresses under impact loading. Calibrated on a split Hopkinson pressure bar (SHPB) with a simple measurement circuit of resistance strain gauges, the PVDF gauge was then used to establish dynamic stress-strain curves of concrete cylinders from a series of axial impact testing on a drop-hammer test facility. Test results show that the stress curves measured by the PVDF-based stress gauges are more stable and cleaner than that of the stress curves calculated with the impact force measured from a load cell.

  15. Finite element stress analysis of polymers at high strains

    Durand, M.; Jankovich, E.


    A numerical analysis is presented for the problem of a flat rectangular rubber membrane with a circular rigid inclusion undergoing high strains due to the action of an axial load. The neo-hookean constitutive equations are introduced into the general purpose TITUS program by means of equivalent hookean constants and initial strains. The convergence is achieved after a few iterations. The method is not limited to any specific program. The results are in good agreement with those of a company sponsored photoelastic stress analysis. The theoretical and experimental deformed shapes also agree very closely with one another. For high strains it is demonstrated that using the conventional HOOKE law the stress concentration factor obtained is unreliable in the case of rubberlike material.

  16. Analysis of weld fatigue for steel crane beam based on equivalent structural stress%基于等效结构应力的钢吊车梁焊缝疲劳分析

    张新萍; 唐柏鉴; 王飞


    This paper introduces the principle of equivalent structure stress method for weld fatigue evaluation. Taking T type welded joint as an example, the equivalent structural stress method is verified to be non-sensitive to the grid. Then taking a crane beam as the research object, the result of finite element static analysis has been calculated with the equivalent structure stress method by ANSYS/FE-SAFE. Finally, considering the influence of welding residual stress, weld fatigue life has been evaluated. The results show that the fatigue life of the weld is not sensitive, and the residual stress has reduced the fatigue life of the weld seam.%介绍等效结构应力法对焊缝疲劳评定的原理,以T型焊接接头对比验证等效结构应力法具有网格不敏感。然后以某钢吊车梁作为研究对象,对其进行了静力分析,并且利用有限元分析软件ANSYS/FE-SAFE对吊车梁主焊缝进行了评定。最后,考虑焊接残余应力的影响,对焊缝疲劳寿命进行评估。研究表明,基于等效结构应力法进行焊缝疲劳评定得到的疲劳寿命对网格大小不敏感;残余应力的存在降低了焊缝的疲劳寿命。


    Ji Changjiang; Li Zhonghua; Sun Jun


    A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture criterion, including the fracture direction and the critical load, was established based on the maximum tangential stress in the inclusion for brittle inclusioninduced fracture materials. The proposed fracture criterion is a function of the inclusion fracture stress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrix material. The present criterion will reduce to the conventional one as the inclusion having the same elastic behavior as the matrix material. The proposed solutions are in good agreement with detailed finite element analysis and measurement.

  18. Stress and Buckling Analysis of Cold-formed Zed-purlins Partially Restrained by Steel Sheeting

    Zhi-ming Ye; R. Kettle; L.Y. Li; B.Schafer


    This paper presents an analysis model for cold-formed purlin-sheeting systems subjected to wind uplitt loading in which the restraint of the sheeting to the purlin is taken into account by using two springs representing the translational and rotational restraints provided by the sheeting.The set of equations is solved by means of trigonometric series and finite strip methods in which the pre-buckling stress is calculated based on the same model used for the buckling analysis rather than taken as the "pure bending" stress. The influence of spring stiffness and fixing position of the purlin and sheeting on the stresses resulted in the cross-section of the purlin is discussed in details.

  19. Finite layer and triangular prism element method to subsidence prediction and stress analysis in underground mining

    LIU Li-min(刘立民); LIU Han-long(刘汉龙); LIAN Chuan-jie(连传杰)


    The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost.

  20. Analysis of the Citrullus colocynthis transcriptome during water deficit stress.

    Wang, Zhuoyu; Hu, Hongtao; Goertzen, Leslie R; McElroy, J Scott; Dane, Fenny


    Citrullus colocynthis is a very drought tolerant species, closely related to watermelon (C. lanatus var. lanatus), an economically important cucurbit crop. Drought is a threat to plant growth and development, and the discovery of drought inducible genes with various functions is of great importance. We used high throughput mRNA Illumina sequencing technology and bioinformatic strategies to analyze the C. colocynthis leaf transcriptome under drought treatment. Leaf samples at four different time points (0, 24, 36, or 48 hours of withholding water) were used for RNA extraction and Illumina sequencing. qRT-PCR of several drought responsive genes was performed to confirm the accuracy of RNA sequencing. Leaf transcriptome analysis provided the first glimpse of the drought responsive transcriptome of this unique cucurbit species. A total of 5038 full-length cDNAs were detected, with 2545 genes showing significant changes during drought stress. Principle component analysis indicated that drought was the major contributing factor regulating transcriptome changes. Up regulation of many transcription factors, stress signaling factors, detoxification genes, and genes involved in phytohormone signaling and citrulline metabolism occurred under the water deficit conditions. The C. colocynthis transcriptome data highlight the activation of a large set of drought related genes in this species, thus providing a valuable resource for future functional analysis of candidate genes in defense of drought stress.

  1. Finite element stress analysis of a compression mold. Final report. [Using SASL and WILSON codes

    Watterson, C.E.


    Thermally induced stresses occurring in a compression mold during production molding were evaluated using finite element analysis. A complementary experimental stress analysis, including strain gages and thermocouple arrays, verified the finite element model under typical loading conditions.

  2. Dimensionality of stress experiences: Factorial structure of the Perceived Stress Questionnaire (PSQ) in a population-based Swedish sample.

    Rönnlund, Michael; Vestergren, Peter; Stenling, Andreas; Nilsson, Lars-Göran; Bergdahl, Maud; Bergdahl, Jan


    We investigated the factorial structure of the Perceived Stress Questionnaire (PSQ-recent; Levenstein, Prantera, Varvo et al., 1993) in a large (N = 1516; 35-95 years) population-based Swedish sample (Nilsson, Adolfsson, Bäckman et al., 2004; Nilsson, Bäckman, Erngrund et al., 1997). Exploratory principal components analysis (PCA) was conducted on a first, randomly drawn subsample (n = 506). Next, the model based on the PCA was tested in a second sample (n = 505). Finally, a third sample (n = 505) was used to cross-validate the model. Five components were extracted in the PCA (eigenvalue > 1) and labeled "Demands," "Worries/Tension," "Lack of joy," "Conflict," and "Fatigue," respectively. Twenty-one out of the 30 original PSQ items were retained in a confirmatory factor analysis (CFA) model that included the five (first-order) factors and, additionally, a general (second-order) stress factor, not considered in prior models. The model showed reasonable goodness of fit [χ(2)(184) = 511.2, p < 0.001; CFI = 0.904; RMSEA = 0.059; and SRMR = 0.063]. Multigroup confirmatory factor analyses supported the validity of the established model. The results are discussed in relation to prior investigations of the factorial structure of the PSQ. © 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  3. Stress State Analysis in Aspect of Wellbore Drilling Direction

    Knez, Dariusz


    Drilling directional wells challenges designers. Apart from known problems until now they face exact description of stress distribution in near wellbore region issue. Paper presents analysis of stress state taking into account drilling direction. The transposed in-situ stress state relative to the borehole coordinate system (Cartesian borehole coordinate system) and the total stress component at the borehole wall (cylindrical coordinate system) exhibits cyclic behaviour with respect to drilling direction of borehole. It allows to find optimal wellbore path Wiercenie otworów kierunkowych stanowi duże wyzwanie dla projektantów. Poza problemami typowymi obecnie staja oni w obliczu zagadnienia dokładnego opisu rozkładu naprężeń w strefie przyotworowej. Artykuł przedstawia analizę stanu naprężeń w aspekcie kierunku wiercenia. Rozkład naprężeń transponowany do układu odniesienia związanego z otworem wiertniczym (kartezjański układ współrzędnych zgodny z kierunkiem otworu wiertniczego) oraz składowe naprężenia na ścianie otworu wiertniczego (w cylindrycznym układzie odniesienia) wykazują cykliczną zmienność zależną od kierunku wiercenia. Pozwala to na określenie optymalnej trajektorii osi otworu wiertniczego

  4. Transcriptional Analysis of Normal Human Fibroblast Responses to Microgravity Stress

    Yongqing Liu; Eugenia Wang


    To understand the molecular mechanism (s) of how spaceflight affects cellular signaling pathways, quiescent normal human WI-38 fibroblasts were flown on the STS-93 space shuttle mission. Subsequently, RNA samples from the space flown and ground-control cells were used to construct two cDNA libraries, which were then processed for suppression subtractive hybridization (SSH) to identify spaceflight-specific gene expression. The SSH data show that key genes related to oxidative stress, DNA repair, and fatty acid oxidation are activated by spaceflight, suggesting the induction of cellular oxidative stress. This is further substantiated by the up-regulation of neuregulin 1 and the calcium-binding protein calmodulin 2. Another obvious stress sign is that spaceflight evokes the Ras/mitogen-activated protein kinase and phosphatidylinositol-3 kinase signaling pathways, along with up-regulating several G1-phase cell cycle traverse genes. Other genes showing up regulation of expression are involved in protein synthesis and pro-apoptosis, as well as pro-survival. Interactome analysis of functionally related genes shows that c-Myc is the "hub" for those genes showing significant changes. Hence, our results suggest that microgravity travel may impact changes in gene expression mostly associated with cellular stress signaling, directing cells to either apoptotic death or premature senescence.

  5. Stress-Induced Precipitation of Fine γ-Phase and Thermodynamics Analysis


    The microstructures of a single crystal Ni-base superalloy with[001] orientation were observed by means of TEM. Results showed that the fine γ' particles were precipitated in the γ matrix channels during the tensile deformation of the alloy. Thermodynamics analysis indicated that the solubility of elements M(Al,Ta) within the γ matrix may be changed when the alloy was deformed by the external applied stress. The tensile stress reduced the solubility of elements Al and Ta so as to occur the over-saturation and agglomeration of them, which promoted the precipitation of fine γ'-phase in the γ matrix.

  6. A 37-mm Ceramic Gun Nozzle Stress Analysis


    generate the nodes and elements. The keyword input is more effective to conduct parametric studies. Four node axisymmetric elements were chosen for...stress cases. The combined effect has to be considered. Since both thermal and dynamic analyses are based on linear assumptions, the total result...H YUEN PICATINNY ARSENAL NJ 07806-5000 2 CDR US ARMY ARDEC AMSTA AR CCH B C MANDALA E FENNELL PICATINNY ARSENAL NJ

  7. Neutron diffraction analysis of residual stresses near unannealed welds in anhydrous ammonia nurse tanks.

    Becker, A T; Chumbley, L S; Goettee, D; Russell, A M


    Neutron diffraction analysis was employed to measure residual stresses near welds in used anhydrous ammonia nurse tanks. Tensile residual stresses contribute to stress corrosion cracking of nurse tanks, which can cause tanks to release toxic ammonia vapor. The analysis showed that tensile residual stresses were present in the tanks measured, and the magnitudes of these stresses approached the yield strength of the steel. Implications for agricultural safety and health are discussed.

  8. A High shear stress segment along the San Andreas Fault: Inferences based on near-field stress direction and stress magnitude observations in the Carrizo Plain Area

    Castillo, D. A., [Department of Geology and Geophysics, University of Adelaide (Australia); Younker, L.W. [Lawrence Livermore National Lab., CA (United States)


    Nearly 200 new in-situ determinations of stress directions and stress magnitudes near the Carrizo plain segment of the San Andreas fault indicate a marked change in stress state occurring within 20 km of this principal transform plate boundary. A natural consequence of this stress transition is that if the observed near-field ``fault-oblique`` stress directions are representative of the fault stress state, the Mohr-Coulomb shear stresses resolved on San Andreas sub-parallel planes are substantially greater than previously inferred based on fault-normal compression. Although the directional stress data and near-hydrostatic pore pressures, which exist within 15 km of the fault, support a high shear stress environment near the fault, appealing to elevated pore pressures in the fault zone (Byerlee-Rice Model) merely enhances the likelihood of shear failure. These near-field stress observations raise important questions regarding what previous stress observations have actually been measuring. The ``fault-normal`` stress direction measured out to 70 km from the fault can be interpreted as representing a comparable depth average shear strength of the principal plate boundary. Stress measurements closer to the fault reflect a shallower depth-average representation of the fault zone shear strength. If this is true, only stress observations at fault distances comparable to the seismogenic depth will be representative of the fault zone shear strength. This is consistent with results from dislocation monitoring where there is pronounced shear stress accumulation out to 20 km of the fault as a result of aseismic slip within the lower crust loading the upper locked section. Beyond about 20 km, the shear stress resolved on San Andreas fault-parallel planes becomes negligible. 65 refs., 15 figs.

  9. Using occlusal wear information and finite element analysis to investigate stress distributions in human molars.

    Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W


    Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M(1)). The antagonistic crowns M(1) and P(2)-M(1) of two dried modern human skulls were scanned by μCT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M(1) and P(2)-M(1) was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M(1) in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth.

  10. Pre-Stressing Timber-Based Plate Tensegrity Structures

    Falk, Andreas; Kirkegaard, Poul Henning


    Tensile structures occur in numerous varieties utilising combinations of tension and compression. Introducing structural plates in the basic tensegrity unit and tensegric assemblies varies the range of feasible topologies and provides the structural system with an integrated surface. The present...... paper considers the concept of plate tensegrity based on CLT plates (cross-laminated timber). It combines the principles of tensegrity with the principles of plate shells and is characterised by a plate shell stabilised by struts and cables. The paper deals with material aspects and robustness of timber......-based plate shells and outlines needs, methods and effects of controlling cable stresses for secured capacity, form and function of plate tensegrity....

  11. Mass spectrometry-based plant metabolomics: Metabolite responses to abiotic stress.

    Jorge, Tiago F; Rodrigues, João A; Caldana, Camila; Schmidt, Romy; van Dongen, Joost T; Thomas-Oates, Jane; António, Carla


    Metabolomics is one omics approach that can be used to acquire comprehensive information on the composition of a metabolite pool to provide a functional screen of the cellular state. Studies of the plant metabolome include analysis of a wide range of chemical species with diverse physical properties, from ionic inorganic compounds to biochemically derived hydrophilic carbohydrates, organic and amino acids, and a range of hydrophobic lipid-related compounds. This complexitiy brings huge challenges to the analytical technologies employed in current plant metabolomics programs, and powerful analytical tools are required for the separation and characterization of this extremely high compound diversity present in biological sample matrices. The use of mass spectrometry (MS)-based analytical platforms to profile stress-responsive metabolites that allow some plants to adapt to adverse environmental conditions is fundamental in current plant biotechnology research programs for the understanding and development of stress-tolerant plants. In this review, we describe recent applications of metabolomics and emphasize its increasing application to study plant responses to environmental (stress-) factors, including drought, salt, low oxygen caused by waterlogging or flooding of the soil, temperature, light and oxidative stress (or a combination of them). Advances in understanding the global changes occurring in plant metabolism under specific abiotic stress conditions are fundamental to enhance plant fitness and increase stress tolerance. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:620-649, 2016.

  12. Macro design effects on stress distribution around implants: A photoelastic stress analysis

    Serhat Emre Ozkir


    Conclusion: As there were observable differences between the implant types, straight placed cylindrical implants showed better stress distribution characteristics, while inclined tapering implants had better stress distribution characteristics.

  13. Stress

    ... diabetes. Your Stress-Free System for Family Dinners! - 2017-03-book-oclock-scramble.html Your Stress-Free System for Family Dinners! A year of delicious meals to help prevent ...

  14. Stress

    ... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  15. Thermal Viscoelastic Analysis of Plastic Components Considering Residual Stress

    Choi, Chel Woo; Jeoung, Kab Sik; Moon, Hyung-Il; Kim, Heon Young

    Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity, but plastic components may often become distorted after injection molding due to residual stress after the filling, packing, and cooling processes. In addition, plastic deteriorates depending on various temperature conditions and the operating time, which can be characterized by stress relaxation and creep. The viscoelastic behavior of plastic materials in the time domain can be expressed by the Prony series using the ABAQUS commercial software package. This paper suggests a process for predicting post-production deformation under cyclic thermal loading. The process was applied to real plastic panels, and the deformation predicted by the analysis was compared to that measured in actual testing, showing the possibility of using this process for predicting the post-production deformation of plastic products under thermal loading.

  16. Analysis of thermal stresses in horizontal delivery water heaters

    Bilan, A. V.; Plotnikov, P. N.


    Analysis of thermal stresses in tubes and a compensator, taking into account water heating in each heater bunch and temperature at which its mounting is implemented, and of stresses on pressure is presented. The 3D-model of the horizontal delivery water heater of PSG-4900-0.3-1.14 type is used. The tube plate is represented as the 3D-body with 6863 holes with offset center of the perforated area, the steam space shell is represented as a cylindrical casing, the bottoms of water chambers are considered as elliptical casings, the four-lens compensator is represented in the form of toroidal casings, and the tubes are considered as beams operating in tensile-compression and bending in two planes. Calculations were carried out for different temperatures of superheated steam and a steam space shell, respectively, as well as designs with compensator and without it. Various temperature values of the tubes on the passes were calculated and set. The studies were carried out taking into account nonaxis-symmetrical spacing the tube plate and compensator deformation. The calculation results of tensile-compression stresses in the tubes are presented. Furthermore, the central tubes experience compressive stresses, whose maximal values take place on the border between the tubes of the fourth and of the first passes. For its decrease, it is recommended to increase the distance between the tubes of these passes. The tension stresses in the peripheral tubes are the maximal stresses. To reduce the stresses and, therefore, increase service life of the delivery water heater at using wet or superheated (not more than by 30-50°C) steam in it (the larger value refers to the brass tubes and the water pressure of 1.6-2.5 MPa), it is necessary to recommend the noncompensatory design at using the steam superheated by more than 30-50°C (at Ural Turbine Works, it is the turbines of T-250/300-23.5 and T-113/145-12.4 types with intermediate superheating) and to recommend the installation of the

  17. Adherence to internet-based mobile-supported stress management

    Zarski, A C; Lehr, D.; Berking, M.


    Background: Nonadherence to treatment is a prevalent issue in Internet interventions. Guidance from health care professionals has been found to increase treatment adherence rates in Internet interventions for a range of physical and mental disorders. Evaluating different guidance formats of varying...... intensity is important, particularly with respect to improvement of effectiveness and cost-effectiveness. Identifying predictors of nonadherence allows for the opportunity to better adapt Internet interventions to the needs of participants especially at risk for discontinuing treatment. Objective: The goal...... of this study was to investigate the influence of different guidance formats (content-focused guidance, adherence-focused guidance, and administrative guidance) on adherence and to identify predictors of nonadherence in an Internet-based mobile-supported stress management intervention (ie, GET.ON Stress...

  18. Multiaxial Stress Analysis of Diesel Engine Cylinder Head Based on Transient Response%基于瞬态响应的柴油机缸盖多轴应力分析

    陈少林; 龙鑫; 杨迪; 张涛


    为了给缸盖的疲劳寿命预测提供准确的边界条件,以某型柴油机缸盖为研究对象,运用Ansys有限元分析软件,采用直接积分法对其进行了标定工况的瞬态计算,并将计算结果与有限元静力学分析结果进行了对比.考察瞬态计算得到的应力多轴状态,研究高应力梯度部位多轴应力的变化趋势,结果表明:气缸盖在工作时,结构上的多轴比例载荷与多轴非比例载荷状态共存.%In order to provide the accurate boundary conditions for fatigue life prediction of cylinder head, the transient calculation of rated condition for a diesel engine cylinder head was carried out with the direct integral method based on ANSYS FEA software and the calculated results were compared with the finite element statics results. The rnultiaxial stress state by transient calculation was discussed and the variation tendency of multiaxial stress in the high-stress gradient location was researched. The results show that the states of structural multiaxial proportional load and multiaxial non-proportional load coexist when the cylinder head is working.

  19. 基于有限元的切削加工仿真及残余应力分析%Machining Simulation and Residual Stress Analysis Based on Finite Element

    王永胜; 胡青春


    基于热弹塑性有限元理论在DEFORM3D软件中建立正交切削加工有限元模型.建模过程中考虑了工件材料本构关系、局部网格自动重划分、刀屑摩擦、切屑分离等影响切削仿真的关键因素,分析了切削过程中工件等效应力的分布.对工件在不同切削速度下的残余应力进行分析和比较,得出两者之间的定性影响关系.%Based on thermo-elastic-plastic FEM, the finite element model of orthogonal cutting was established in DEFORM3D codes. Key factors affecting the cutting simulation such as constitutive relation of workpiece, local automatic remeshing,the criterion of chip separation and the friction between tool and chip were considered during the process of modeling. The equivalent stress distribution of workpiece during the cutting process was studied. The qualitative relation between cutting speed and workpiece residual stress was obtained after residal stress from different cutting speed had been analysed and compared.

  20. Residual stress analysis in aged graphite/PMR-15 composites using X-ray diffraction

    Benedikt, B. [Los Alamos National Laboratory, Engineering Sciences and Applications Division, Los Alamos, NM 87545 (United States)]. E-mail:; Lewis, M. [Los Alamos National Laboratory, Engineering Sciences and Applications Division, Los Alamos, NM 87545 (United States); Rangaswamy, P. [Los Alamos National Laboratory, Engineering Sciences and Applications Division, Los Alamos, NM 87545 (United States); Kumosa, M. [Center for Advanced Materials and Structures, Department of Engineering, University of Denver, 2390 South York St., Denver, CO 80208 (United States); Predecki, P. [Center for Advanced Materials and Structures, Department of Engineering, University of Denver, 2390 South York St., Denver, CO 80208 (United States); Kumosa, L. [Center for Advanced Materials and Structures, Department of Engineering, University of Denver, 2390 South York St., Denver, CO 80208 (United States); Gentz, M. [Center for Advanced Materials and Structures, Department of Engineering, University of Denver, 2390 South York St., Denver, CO 80208 (United States)


    In this paper, we present and discuss the methodology to monitor average residual stresses in aged high temperature unidirectional and woven graphite fiber/PMR-15 composites. The aging experiments were performed at 315 deg. C for 1170 h in nitrogen and 1064 h in air, respectively. The proposed methodology was based on X-ray diffraction (XRD) strain measurements in embedded crystalline metallic inclusions. The aging experiments performed in nitrogen showed an increasing trend in the measured residual stresses from the embedded inclusions with aging time. In contrast, the aging experiments performed in air showed an increasing trend up to {approx}200 h and then dropped by {approx}40% for both unidirectional and woven composites. To extract the average stresses in the composite matrix from the average stresses in embedded inclusions as determined using XRD, the well-established Eshelby/Mori-Tanaka method was used. In addition, to address the effect of inclusion interactions, we also computed the average stresses in the embedded inclusions by taking into account inclusion interactions within the frame-work of the Eshelby/Mori-Tanaka method. It was shown that the interactions between the inclusions did not significantly disturb the average stresses in the inclusions, thereby validating the Eshelby/Mori-Tanaka method used in our analysis. Finally, we show that for an aging process that does not cause any damage to a composite matrix, a relatively simple computation based on the visco-elastic Eshelby/Mori-Tanaka method is sufficient to determine the average stress field in a composite matrix as compared with the predictions based on classical lamination plate theory (CLPT). However, if significant matrix degradation occurs, the current micromechanical modeling approach would likely produce erroneous results.

  1. Music interventions to reduce stress and anxiety in pregnancy: a systematic review and meta-analysis.

    Corbijn van Willenswaard, Kyrsten; Lynn, Fiona; McNeill, Jenny; McQueen, Karen; Dennis, Cindy-Lee; Lobel, Marci; Alderdice, Fiona


    Stress and anxiety are common in pregnancy and shown to have adverse effects on maternal and infant health outcomes. The aim of this review and meta-analysis was to assess the effectiveness of music-based interventions in reducing levels of stress or anxiety among pregnant women. Six databases were searched using key terms relating to pregnancy, psychological stress, anxiety and music. Inclusion criteria were randomised controlled or quasi-experimental trials that assessed the effect of music during pregnancy and measured levels of psychological stress or anxiety as a primary or secondary outcome. Two authors independently assessed and extracted data. Quality assessment was performed using The Cochrane Collaboration risk of bias criteria. Meta-analyses were conducted to assess stress and anxiety reduction following a music-based intervention compared to a control group that received routine antenatal care. Five studies with 1261 women were included. Music interventions significantly reduced levels of maternal anxiety (Standardised Mean Difference (SMD): -0.21; 95% Confidence Interval (CI) -0.39, -0.03; p = 0.02). There was no significant effect on general stress (SMD: -0.08; 95% CI -0.25, 0.09; p = 0.35) or pregnancy-specific stress (SMD: -0.02; 95% CI -0.19, 0.15; p = 0.80). The methodological quality of included studies was moderate to weak, all studies having a high or unclear risk of bias in allocation concealment, blinding and selective outcome reporting. There is evidence that music-based interventions may reduce anxiety in pregnancy; however, the methodological quality of the studies was moderate to weak. Additional research is warranted focusing on rigour of assessment, intensity of interventions delivered and methodological limitations.

  2. Neighborhood-Level Stress and Circadian Cortisol: A Systematic Review and Meta-Analysis.

    Fatemeh Hosseini


    Full Text Available The main objective was to find association between basal cortisol and neighborhood-level stress. Systematic searches, including electronic and hand searches, were conducted. The most recent date of the search was July 26, 2013. Primary observational studies included if they considered stress related outcomes in the neighborhood context. Using the EndNote X7 advanced search option; the authors examined the abstracts and titles of the 18,092 articles to exclude obviously irrelevant studies, gray literature, discussion papers, reviews and, studies with no complete data. Two authors independently extracted data from the original reports into pre-designed data extraction forms based on the Data Extraction Template of the Cochrane Consumer and Communication Review Group (CCCRG. Ten studies with a total of 2,134 participants were synthesized and analyzed. Two studies out of ten received expanded meta-analysis. The overall effect size (95% CI for cortisol level for residents in neighborhoods with lower stress compared to inhabitants from higher was 0.12 (0.01, 0.23. This review is demonstrating a link between psychosocial or physical stress and cortisol obtained from saliva. However, living in high disorder neighborhoods results in higher level of cortisol. This represents a biological indicator of psychosocial/physical stress exposure (i.e., neighborhood disorder that reflects variances in stress exposure levels.

  3. Neighborhood-Level Stress and Circadian Cortisol: A Systematic Review and Meta-Analysis.

    Hosseini, Fatemeh; Adha, Nikmatul; Zainol, Rosilawati; Isahak, Marzuki; Nemati, Nahid


    The main objective was to find association between basal cortisol and neighborhood-level stress. Systematic searches, including electronic and hand searches, were conducted. The most recent date of the search was July 26, 2013. Primary observational studies included if they considered stress related outcomes in the neighborhood context. Using the EndNote X7 advanced search option; the authors examined the abstracts and titles of the 18,092 articles to exclude obviously irrelevant studies, gray literature, discussion papers, reviews and, studies with no complete data. Two authors independently extracted data from the original reports into pre-designed data extraction forms based on the Data Extraction Template of the Cochrane Consumer and Communication Review Group (CCCRG). Ten studies with a total of 2,134 participants were synthesized and analyzed. Two studies out of ten received expanded meta-analysis. The overall effect size (95% CI) for cortisol level for residents in neighborhoods with lower stress compared to inhabitants from higher was 0.12 (0.01, 0.23). This review is demonstrating a link between psychosocial or physical stress and cortisol obtained from saliva. However, living in high disorder neighborhoods results in higher level of cortisol. This represents a biological indicator of psychosocial/physical stress exposure (i.e., neighborhood disorder) that reflects variances in stress exposure levels.

  4. Round robin analysis on stress intensity factor of inner surface cracks in welded stainless steel pipes

    Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)


    Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  5. Design and analysis of a toroidal tester for the measurement of core losses under axial compressive stress

    Alatawneh, Natheer; Rahman, Tanvir; Lowther, David A.; Chromik, Richard


    Electric machine cores are subjected to mechanical stresses due to manufacturing processes. These stresses include radial, circumferential and axial components that may have significant influences on the magnetic properties of the electrical steel and hence, on the output and efficiencies of electrical machines. Previously, most studies of iron losses due to mechanical stress have considered only radial and circumferential components. In this work, an improved toroidal tester has been designed and developed to measure the core losses and the magnetic properties of electrical steel under a compressive axial stress. The shape of the toroidal ring has been verified using 3D stress analysis. Also, 3D electromagnetic simulations show a uniform flux density distribution in the specimen with a variation of 0.03 T and a maximum average induction level of 1.5 T. The developed design has been prototyped, and measurements were carried out using a steel sample of grade 35WW300. Measurements show that applying small mechanical stresses normal to the sample thickness rises the delivered core losses, then the losses decrease continuously as the stress increases. However, the drop in core losses at high stresses does not go lower than the free-stress condition. Physical explanations for the observed trend of core losses as a function of stress are provided based on core loss separation to the hysteresis and eddy current loss components. The experimental results show that the effect of axial compressive stress on magnetic properties of electrical steel at high level of inductions becomes less pronounced.

  6. Analysis of the dynamic stress of planar flexible-links parallel robots

    DU Zhaocai; YU Yueqing; YANG Jianxin


    This paper presents a method for the dynamic stress analysis of planar parallel robots with flexible links and a rigid moving platform.The finite element-based dynamic model of flexible parallel robots is proposed.The relation between elastic deformations and elastic displacements of the flexible links is investigated,considering the coupling effects of elastic motion and rigid motion.The elastic deformations of links are calculated.Considering the effects of bendingshearing strain and tensile-compression strain,the dynamic stress of the links and its position are derived by using the Kineto-Elastodynamics theory and the Timoshenko beam theory.Due to the flexibility of the links,the dynamic stresses are well illustrated through numerical simulation.Compared with the results of the finite element software SAMCEF,the numerical simulation results show the good coherence and advantages of the analysis method.The dynamic stress analysis is demonstrated to have a significant impact on the analysis,design and control of flexible parallel robots.

  7. Reliability Analysis of Temperature Influence on Stresses in Rigid Pavement Made from Recycled Materials

    Aleš Florian


    Full Text Available Complex statistical and sensitivity analysis of principal stresses in concrete slabs of the real type of rigid pavement made from recycled materials is performed. The pavement is dominantly loaded by the temperature field acting on the upper and lower surface of concrete slabs. The computational model of the pavement is designed as a spatial (3D model, is based on a nonlinear variant of the finite element method that respects the structural nonlinearity, enables to model different arrangement of joints, and the entire model can be loaded by thermal load. Four concrete slabs separated by transverse and longitudinal joints and the additional structural layers including soil to the depth of about 3 m are modeled. The thickness of individual layers, physical and mechanical properties of materials, characteristics of joints, and the temperature of the upper and lower surface of slabs are supposed to be random variables. The simulation technique Updated Latin Hypercube Sampling with 20 simulations is used for the reliability analysis. As results of statistical analysis, the estimates of basic statistics of the principal stresses σ1 and σ3 in 106 points on the upper and lower surface of slabs are obtained. For sensitivity analysis the sensitivity coefficient based on the Spearman rank correlation coefficient is used. As results of sensitivity analysis, the estimates of influence of random variability of individual input variables on the random variability of principal stresses σ1 and σ3 are obtained.

  8. Discontinuum Modelling Approach for Stress Analysis at a Seismic Source: Case Study

    Sainoki, Atsushi; Mitri, Hani S.; Yao, Mike; Chinnasane, Damodara


    Rockbursts in underground mines can cause devastating damage to mine workings; hence, it is important to be able to assess the potential for their occurrence. The present study focuses on a large seismic event that took place at an underground base metal mine in Canada. The event took place in a dyke near the 100/900 orebodies on 3880 Level (1180 m below surface) of the Copper Cliff Mine in Sudbury, Canada. A 3D continuum stress analysis of the orebodies, i.e., 100 and 900, using an orebody-wide model encompassing the major geological structures and in situ stress heterogeneity in the mine shows low potential for rockburst at the seismic source location—a result which contradicts the fact that a large seismic event actually took place. A postulation is thus made that there had been highly stressed regions caused by geological disturbances at the source location before mining activities took place. In order to verify the postulation, a further study is undertaken with the discrete element modelling technique, whereby a cube-shaped model containing a fracture network is subjected to a stress state similar to that at the source location. A model parametrical study is conducted with respect to the distribution of the fracture (joint) network and its mechanical properties. The results reveal that when joints are densely distributed at the source location, the stress state becomes significantly burst prone. It is observed that the length, density, stiffness, and orientation of joints have a large influence on the stress state along the joints, while the friction angle, cohesion, and tensile strength do not influence the stress state. A cube-shaped model is constructed with joint sets actually mapped at the mine and a stress analysis is performed. The results demonstrate the generation of highly stressed regions due to the interaction of the joints with the applied in situ stress fields, thus leading to burst-prone conditions. The present study numerically confirms that

  9. Non-linear analysis and the design of Pumpkin Balloons: stress, stability and viscoelasticity

    Rand, J. L.; Wakefield, D. S.

    Tensys have a long-established background in the shape generation and load analysis of architectural stressed membrane structures Founded upon their inTENS finite element analysis suite these activities have broadened to encompass lighter than air structures such as aerostats hybrid air-vehicles and stratospheric balloons Winzen Engineering couple many years of practical balloon design and fabrication experience with both academic and practical knowledge of the characterisation of the non-linear viscoelastic response of the polymeric films typically used for high-altitude scientific balloons Both companies have provided consulting services to the NASA Ultra Long Duration Balloon ULDB Program Early implementations of pumpkin balloons have shown problems of geometric instability characterised by improper deployment and these difficulties have been reproduced numerically using inTENS The solution lies in both the shapes of the membrane lobes and also the need to generate a biaxial stress field in order to mobilise in-plane shear stiffness Balloons undergo significant temperature and pressure variations in flight The different thermal characteristics between tendons and film can lead to significant meridional stress Fabrication tolerances can lead to significant local hoop stress concentrations particularly adjacent to the base and apex end fittings The non-linear viscoelastic response of the envelope film acts positively to help dissipate stress concentrations However creep over time may produce lobe geometry variations that may

  10. Diallel analysis in white oat cultivars subjected to water stress.

    Guilherme Ribeiro


    Full Text Available The goal of this work was to determine the combining ability of three white oat parental genotypes (UPF 18, URS21and URS 22 and to estimate the heterosis of F1 hybrids in two conditions, with and without water stress. The results indicate a largeeffect of the environment on the evaluated characters (cycle, leaf area, plant stature, grain yield per plant, main panicle weight andnumber of grains of the main panicle. The condition without stress was the most efficient for the selection of superior genotypes.Based on the general and specific combining ability, the cultivar URS 22 was shown to be indicated for cycle and stature reduction,while UPF 18 lead to increases in leaf area, main panicle weight and number of grains of the main panicle. The specific cross URS22 x URS 21 was the best for the selection of superior genotypes.

  11. A New EO-Based Indicator for Assessing and Monitoring Climate-Related Vegetation Stress

    McCormick, Niall; Gobron, Nadine


    This paper describes a study in which a new environmental indicator, called Annual Vegetation Stress (AVS), has been developed, based on annual anomalies of satellite-measured Fraction of Absorbed Photosynthetically Active Radiation (FAPAR ), and used to map the area affected annually by vegetation stress during the period 2003-2014, for 108 selected developing countries. Analysis of the results for six countries in the "tropical and subtropical forests" ecoregion, reveals good correspondence between high AVS values, and the occurrence of climatic extremes (droughts) and anthropogenic disturbance (deforestation). The results for Equatorial Guinea suggest that the recent trend of large-scale droughts and rainfall deficits in Central and Western Africa, contribute to increased vegetation stress in the region's tropical rainforests. In East Timor there is evidence of a "biological lag" effect, whereby the main impacts of drought on the country's seasonally dry tropical forests are delayed until the year following the climate event.

  12. Analysis of differentially expressed genes and adaptive mechanisms of Prunus triloba Lindl. under alkaline stress.

    Liu, Jia; Wang, Yongqing; Li, Qingtian


    Prunus triloba Lindl. is a naturally salt-alkaline-tolerant plant with several unique characteristics, and it can be used as the rootstock of Chinese plum (Prunus salicina Lindl.) in saline-alkaline soils. To comprehensively investigate the alkaline acclimation mechanisms in P. triloba, a series of analyses were conducted under alkaline stress, including analyses of the kinetics of molecular and physiological changes, and leaf microstructure. To understand the kinetics of molecular changes under short-term alkaline stress, we used Illumina HiSeq 2500 platform to identify alkaline stress-related differentially expressed genes (DEGs) in P. triloba. Approximately 53.0 million high-quality clean reads were generated from 59.6 million raw reads, and a total of 124,786 unigenes were obtained after de novo assembly of P. triloba transcriptome data. After alkaline stress treatment, a total of 8948 unigenes were identified as DEGs. Based on these DEGs, a Gene Ontology (GO) enrichment analysis was conducted, suggesting that 28 genes may play an important role in the early alkaline stress response. In addition, analysis of DEGs with the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that pathways were significant at different treatment time points. A significant positive correlation was found between the quantitative real-time PCR (qRT-PCR) results and the RNA-Seq data for seven alkaline-related genes, confirming the reliability of the RNA-Seq results. Based on physiological analysis of P. triloba in response to long-term alkaline stress, we found that the internal microstructures of the leaves of P. triloba changed to adapt to long-term alkaline stress. Various physiological indexes indicated that the degree of membrane injury increased with increasing duration of alkaline stress, affecting photosynthesis in P. triloba seedlings. This represents the first investigation into the physiology and transcriptome of P. triloba in response to alkaline stress. The results of

  13. 12 CFR 652.100 - Audit of the risk-based capital stress test.


    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Audit of the risk-based capital stress test... the risk-based capital stress test. You must have a qualified, independent external auditor review your implementation of the risk-based capital stress test every 3 years and submit a copy of...

  14. Estructuras de elevadores de carga. // Dumbwaiter structure stress analysis.

    G. Escobar Travieso


    Full Text Available Este trabajo tiene como objetivo analizar las tensiones y deformaciones que ocurren en las estructuras del marco de carro,plataforma y cabina de elevadores de carga mediante la aplicación del Método de los Elementos Finitos, específicamentedel montaplatos de 300 Kg. de capacidad, con vista a realizar el análisis de resistencia, racionalización del peso y material ylas posibles vías de solución.Palabras claves: Elevador de carga, estructuras, análisis de tensiones, elementos finitos.________________________________________________________________________________AbstractThis paper deals with the tension and deformation analysis in structures of lifter mark, platform and cabin offreight lifters by means of the Finite Elements Method, specifically the 300 kgs capacity dumbwaiter, in orderto carry out the resistance analysis, weight and material rationalization.Key words: Dumbwaiter, structures, stress analysis, finite elements.

  15. Virtual Mold Technique in Thermal Stress Analysis during Casting Process

    Si-Young Kwak; Jae-Wook Baek; Jeong-Ho Nam; Jeong-Kil Choi


    It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

  16. A pilot study on mindfulness based stress reduction for smokers

    Baker Timothy B


    Full Text Available Abstract Background Mindfulness means paying attention in the present moment, non-judgmentally, without commentary or decision-making. We report results of a pilot study designed to test the feasibility of using Mindfulness Based Stress Reduction (MBSR (with minor modifications as a smoking intervention. Methods MBSR instructors provided instructions in mindfulness in eight weekly group sessions. Subjects attempted smoking cessation during week seven without pharmacotherapy. Smoking abstinence was tested six weeks after the smoking quit day with carbon monoxide breath test and 7-day smoking calendars. Questionnaires were administered to evaluate changes in stress and affective distress. Results 18 subjects enrolled in the intervention with an average smoking history of 19.9 cigarettes per day for 26.4 years. At the 6-week post-quit visit, 10 of 18 subjects (56% achieved biologically confirmed 7-day point-prevalent smoking abstinence. Compliance with meditation was positively associated with smoking abstinence and decreases in stress and affective distress. Discussions and conclusion The results of this study suggest that mindfulness training may show promise for smoking cessation and warrants additional study in a larger comparative trial.

  17. Analysis of interlaminar stress and nonlinear dynamic response for composite laminated plates with interfacial damage

    F. H. Zhu; Y. M. Fu


    By considering the effect of interfacial damage and using the variation principle, three-dimensional nonli-near dynamic governing equations of the laminated plates with interfacial damage are derived based on the general six-degrees-of-freedom plate theory towards the accurate stress analysis. The solutions of interlaminar stress and nonlinear dynamic response for a simply supported laminated plate with interfacial damage are obtained by using the finite dif-ference method, and the results are validated by compari-son with the solution of nonlinear finite element method. In numerical calculations, the effects of interfacial damage on the stress in the interface and the nonlinear dynamic response of laminated plates are discussed.

  18. Proteomic analysis of Vibrio metschnikovii under cold stress using a quadrupole Orbitrap mass spectrometer.

    Jia, Juntao; Chen, Ying; Jiang, Yinghui; Li, Zhengyi; Zhao, Liqing; Zhang, Jian; Tang, Jing; Feng, Liping; Liang, Chengzhu; Xu, Biao; Gu, Peiming; Ye, Xiwen


    Vibrio metschnikovii is a food-borne pathogen found in seafood worldwide. We studied the global proteome responses of V. metschnikovii under cold stress by nano-flow ultra-high-performance liquid chromatography coupled to a quadrupole Orbitrap mass spectrometer. A total of 2066 proteins were identified, among which 288 were significantly upregulated and 572 were downregulated. Functional categorization of these proteins revealed distinct differences between cold-stressed and control cells. Quantitative reverse transcription polymerase chain reaction analysis was also performed to determine the mRNA expression levels of seventeen cold stress-related genes. The results of this study should improve our understanding of the metabolic activities of cold-adapted bacteria and will facilitate a better systems-based understanding of V. metschnikovii.

  19. A quantitative meta-analysis of neurocognitive functioning in posttraumatic stress disorder

    Scott, J. Cobb; Matt, Georg E.; Wrocklage, Kristen M.; Crnich, Cassandra; Jordan, Jessica; Southwick, Steven M.; Krystal, John H.; Schweinsburg, Brian C.


    Posttraumatic stress disorder (PTSD) is associated with regional alterations in brain structure and function that are hypothesized to contribute to symptoms and cognitive deficits associated with the disorder. We present here the first systematic meta-analysis of neurocognitive outcomes associated with PTSD to examine a broad range of cognitive domains and describe the profile of cognitive deficits, as well as modifying clinical factors and study characteristics. This report is based on data ...

  20. Study on H2S stress corrosion test of welded joint for X65 pipeline steel and numerical analysis

    金晓军; 霍立兴; 张玉凤; 白秉仁; 李晓巍; 曹军


    The susceptibility of welded joint for the X65 pipeline steel to H2S stress corrosion cracking (SCC) is investigated. SCC tests on the steel are carried out in the environment based on NACE TM-01-77 solution with saturated gaseous H2S. The threshold stress intensity factor and crack propagation velocity are calculated according to wedge-opening loading (WOL) specimens. The three-dimensional elastic-plastic finite element analysis of WOL specimens is performed by using the FEM programming package ANSYS. Stress field and concentration of hydrogen distribution property ahead of the crack tip are obtained. This paper surveyed the microstructure of welded joint and studied on the mechanical properties of X65 pipeline steel. It provides experimental basis for studying stress corrosion. The results of numerical analysis are consistent with conclusions of stress corrosion test.

  1. A different approach to X-ray stress analysis

    Ogilvie, Robert E. [Massachusetts Institute of Technology, Room 13-5065, 77 Massachusetts Ave., Cambridge, MA (United States)], E-mail:


    A different approach to X-ray stress analysis has been developed. At the outset, it must be noted that the material to be analyzed is assumed homogeneous and isotropic. If a sphere with radius r within a specimen is subjected to a state of stress, the sphere is deformed into an ellipsoid. The semi-axes of the ellipsoid have the values of (r + {epsilon}{sub x}), (r + {epsilon}{sub y}), and (r + {epsilon}{sub z}), which are replaced by d{sub x}, d{sub y}, and d{sub z}, or for the cubic case, a{sub x}, a{sub y}, and a{sub z}. In this technique, at a particular {phi} angle (see ), the two-theta position of a high angle (hkl) peak is determined at {psi} angles of 0, 15, 30, and 45{sup o}. These measurements are repeated for 3 to 6 {phi} angles in steps of 30{sup o}. The d{sub {phi}}{sub {psi}} or a{sub {phi}}{sub {psi}} values are then determined from the peak positions. The data is then fitted to the general quadratic equation for an ellipsoid by the method of least squares. From the coefficients of the quadratic equation, the angle between the laboratory and the specimen coordinates (direction of the principle stress) can be determined. Applying the general rotation of axes equations to the quadratic, the equation of the ellipse in the x-y plane is determined. The a{sub x}, a{sub y}, and a{sub z} values for the principal axes of the lattice parameter ellipsoid are then evaluated. It is then possible to determine the unstressed a{sub 0} value from Hooke's Law using a{sub x}, a{sub y}, and a{sub z}. The magnitude of the principal strains/stresses is then determined.

  2. A memory-based model of posttraumatic stress disorder

    Rubin, David C.; Berntsen, Dorthe; Johansen, Marlene Klindt


    In the mnemonic model of posttraumatic stress disorder (PTSD), the current memory of a negative event, not the event itself, determines symptoms. The model is an alternative to the current event-based etiology of PTSD represented in the Diagnostic and Statistical Manual of Mental Disorders (4th ed....... Predisposing factors that affect the current memory have large effects on symptoms. The inability-to-recall-an-important-aspect-of-the-trauma symptom does not correlate with other symptoms. Loss or enhancement of the trauma memory affects PTSD symptoms in predictable ways. Special mechanisms that apply only...

  3. Interventions to reduce stress in university students: a review and meta-analysis.

    Regehr, Cheryl; Glancy, Dylan; Pitts, Annabel


    Recent research has revealed concerning rates of anxiety and depression among university students. Nevertheless, only a small percentage of these students receive treatment from university health services. Universities are thus challenged with instituting preventative programs that address student stress and reduce resultant anxiety and depression. A systematic review of the literature and meta-analysis was conducted to examine the effectiveness of interventions aimed at reducing stress in university students. Studies were eligible for inclusion if the assignment of study participants to experimental or control groups was by random allocation or parallel cohort design. Retrieved studies represented a variety of intervention approaches with students in a broad range of programs and disciplines. Twenty-four studies, involving 1431 students were included in the meta-analysis. Cognitive, behavioral and mindfulness interventions were associated with decreased symptoms of anxiety. Secondary outcomes included lower levels of depression and cortisol. Included studies were limited to those published in peer reviewed journals. These studies over-represent interventions with female students in Western countries. Studies on some types of interventions such as psycho-educational and arts based interventions did not have sufficient data for inclusion in the meta-analysis. This review provides evidence that cognitive, behavioral, and mindfulness interventions are effective in reducing stress in university students. Universities are encouraged to make such programs widely available to students. In addition however, future work should focus on developing stress reduction programs that attract male students and address their needs. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Residual stress analysis of multilayer environmental barrier coatings.

    Harder, B.; Almer, J.; Weyant, C.; Lee, K.; Faber, K.; Northwestern Univ.; Rolls-Royce Corp.


    Silicon-based ceramics (SiC, Si{sub 3}N{sub 4}) are promising materials systems for high-temperature structural applications in gas turbine engines. However, the silica layer that forms on these materials is susceptible to attack from water vapor present in combustion environments. To protect against this degradation, environmental barrier coatings (EBCs) have been developed to shield the underlying substrate and prevent degradation. Here we report on elastic and thermal properties, as well as internal stresses of candidate multilayer coatings, as measured in situ using microfocused high-energy X-rays in a transmission diffraction geometry. Doped aluminosilicate coatings were investigated for their stability on a SiC/SiC melt-infiltrated substrate. The coatings consisted of a Ba{sub 1-x}Sr{sub x}Al{sub 2}Si{sub 2}O{sub 8} topcoat with a mullite or mullite+SrAl{sub 2}Si{sub 2}O{sub 8} interlayer, and a silicon bond coat. A numerical model was used to compare the stress results with an ideal coating system. Experiments were carried out on as-sprayed and heat-treated samples in order to analyze the strain and phase evolution as a function of multilayer depth and temperature. The phase transformation of the topcoat promoted healing of cracks in the EBC and reduced stresses in the underlying layers and the addition of SAS to the interlayer reduced stresses in thermally cycled coatings, but did not stop cracks from forming.

  5. Self-guided internet-based and mobile-based stress management for employees

    Ebert, D. D.; Heber, E.; Berking, M.


    Objective This randomised controlled trial (RCT) aimed to evaluate the efficacy of a self-guided internet-based stress management intervention (iSMI) for employees compared to a 6-month wait-list control group (WLC) with full access for both groups to treatment as usual. M e t h o d A sample of 2...... of stressed employees. Internet-based self-guided interventions could be an acceptable, effective and potentially costeffective approach to reduce the negative consequences associated with work-related stress.......Objective This randomised controlled trial (RCT) aimed to evaluate the efficacy of a self-guided internet-based stress management intervention (iSMI) for employees compared to a 6-month wait-list control group (WLC) with full access for both groups to treatment as usual. M e t h o d A sample of 264...... employees with elevated symptoms of perceived stress (Perceived Stress Scale, PSS-10 =22) was randomly assigned to either the iSMI or to the WLC. The iSMI consisted of seven sessions and one booster session including problem-solving and emotion regulation techniques. Self-report data were assessed...

  6. Genome-wide transcriptome analysis reveals that cadmium stress signaling controls the expression of genes in drought stress signal pathways in rice.

    Youko Oono

    Full Text Available Plant growth is severely affected by toxic concentrations of the non-essential heavy metal cadmium (Cd. Comprehensive transcriptome analysis by RNA-Seq following cadmium exposure is required to further understand plant responses to Cd and facilitate future systems-based analyses of the underlying regulatory networks. In this study, rice plants were hydroponically treated with 50 µM Cd for 24 hours and ∼60,000 expressed transcripts, including transcripts that could not be characterized by microarray-based approaches, were evaluated. Upregulation of various ROS-scavenging enzymes, chelators and metal transporters demonstrated the appropriate expression profiles to Cd exposure. Gene Ontology enrichment analysis of the responsive transcripts indicated the upregulation of many drought stress-related genes under Cd exposure. Further investigation into the expression of drought stress marker genes such as DREB suggested that expression of genes in several drought stress signal pathways was activated under Cd exposure. Furthermore, qRT-PCR analyses of randomly selected Cd-responsive metal transporter transcripts under various metal ion stresses suggested that the expression of Cd-responsive transcripts might be easily affected by other ions. Our transcriptome analysis demonstrated a new transcriptional network linking Cd and drought stresses in rice. Considering our data and that Cd is a non-essential metal, the network underlying Cd stress responses and tolerance, which plants have developed to adapt to other stresses, could help to acclimate to Cd exposure. Our examination of this transcriptional network provides useful information for further studies of the molecular mechanisms of plant adaptation to Cd exposure and the improvement of tolerance in crop species.

  7. Trajectory Based Traffic Analysis

    Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin


    -and-click analysis, due to a novel and efficient indexing structure. With the web-site will demonstrate several analyses, using a very large real-world data set consisting of 1.9 billion GPS records (1.5 million trajectories) recorded from more than 13000 vehicles, and touching most...

  8. Epigenetic and chromatin-based mechanisms in environmental stress adaptation and stress memory in plants

    Jorn Lamke; Isabel Baurle


    .... Given their potential epigenetic nature, such modifications may provide a mechanistic basis for a stress memory, enabling plants to respond more efficiently to recurring stress or even to prepare...

  9. Development of Photogrammetric Methods of Stress Analysis and Quality Control

    Kubik, D L; Kubik, Donna L.; Greenwood, John A.


    A photogrammetric method of stress analysis has been developed to test thin, nonstandard windows designed for hydrogen absorbers, major components of a muon cooling channel. The purpose of the absorber window tests is to demonstrate an understanding of the window behavior and strength as a function of applied pressure. This is done by comparing the deformation of the window, measured via photogrammetry, to the deformation predicted by finite element analysis (FEA). FEA analyses indicate a strong sensitivity of strain to the window thickness. Photogrammetric methods were chosen to measure the thickness of the window, thus providing data that are more accurate to the FEA. This, plus improvements made in hardware and testing procedures, resulted in a precision of 5 microns in all dimensions and substantial agreement with FEA predictions.

  10. A new algebraic transition model based on stress length function

    Xiao, Meng-Juan; She, Zhen-Su


    Transition, as one of the two biggest challenges in turbulence research, is of critical importance for engineering application. For decades, the fundamental research seems to be unable to capture the quantitative details in real transition process. On the other hand, numerous empirical parameters in engineering transition models provide no unified description of the transition under varying physical conditions. Recently, we proposed a symmetry-based approach to canonical wall turbulence based on stress length function, which is here extended to describe the transition via a new algebraic transition model. With a multi-layer analytic form of the stress length function in both the streamwise and wall normal directions, the new model gives rise to accurate description of the mean field and friction coefficient, comparing with both the experimental and DNS results at different inlet conditions. Different types of transition process, such as the transition with varying incoming turbulence intensities or that with blow and suck disturbance, are described by only two or three model parameters, each of which has their own specific physical interpretation. Thus, the model enables one to extract physical information from both experimental and DNS data to reproduce the transition process, which may prelude to a new class of generalized transition model for engineering applications.

  11. Proteomic analysis of seed germination under salt stress in soybeans

    Xiao-yan XU; Rui FAN; Rui ZHENG; Chun-mei LI; De-yue YU


    Soybean (Glycine max (L.) Merrill) is a salt-sensitive crop,and its production is severely affected by saline soils.Therefore,the response of soybean seeds to salt stress during germination was investigated at both physiological and proteomic levels.The salt-tolerant cultivar Lee68 and salt-sensitive cultivar N2899 were exposed to 100 mmol/L NaCl until radicle protrusion from the seed coat.In both cultivars,the final germination percentage was not affected by salt,but the mean germination times of Lee68 and N2899 were delayed by 0.3 and 1.0 d,respectively,compared with controls.In response to salt stress,the abscisic acid content increased,and gibberellic acid (GA1+3) and isopentenyladenosine decreased.Indole-3-acetic acid increased in Lee68,but remained unchanged in N2899.The proteins extracted from germinated seeds were separated using two-dimensional gel electrophoresis (2-DE),followed by Coomassie brilliant blue G-250 staining.About 350 protein spots from 2-DE gels of pH range 3 to 10 and 650 spots from gels of pH range 4 to 7 were reproducibly resolved,of which 18 protein spots showed changes in abundance as a result of salt stress in both cultivars.After matrix-assisted laser desorption ionization-time of flight-mass spectroscopy (MALDI-TOF-MS) analysis of the differentially expressed proteins,the peptide mass fingerprint was searched against the soybean UniGene database and nine proteins were successfully identified.Ferritin and 20S proteasome subunit β-6 were up-regulated in both cultivars.Glyceraldehyde 3-phosphate dehydrogenase,glutathione S-transferase (GST) 9,GST 10,and seed maturation protein PM36 were down-regulated in Lee68 by salt,but still remained at a certain level.However,these proteins were present in lower levels in control N2899 and were up-regulated under salt stress.The results indicate that these proteins might have important roles in defense mechanisms against salt stress during soybean seed germination.

  12. Transcriptome Analysis of High-Temperature Stress in Developing Barley Caryopses :Early Stress Responses and Effects on Storage Compound Biosynthesis

    Elke Mangelsen; Joachim Kilian; Klaus Harter; Christer Jansson; Dierk Wanke; Eva Sundberg


    High-temperature stress,like any abiotic stress,impairs the physiology and development of plants,including the stages of seed setting and ripening.We used the Aflymetrix 22K Barley1 GeneChip microarray to investigate the response of developing barley(Hordeum vulgare)seeds,termed caryopses,after 0.5,3,and 6 h of heat stress exposure;958 induced and 1122 repressed genes exhibited spatial and temporal expression patterns that provide a detailed insight into the caryopses'early heat stress responses.Down-regulation of genes related to storage compound biosynthesis and cell growth provides evidence for a rapid impairment of the caryopsis' development.Increased levels of sugars and amino acids were indicative for both production of compatible solutes and feedback-induced accumulation of substrates for storage compound biosynthesis.Metadata analysis identified embryo and endosperm as primary locations of heat stress responses,indicating a strong impact of short-term heat stress on central developmental functions of the caryopsis.A comparison with heat stress responses in Arabidopsis shoots and drought stress responses in barley caryopses identified both conserved and presumably heat-and caryopsis-specific stress-responsive genes.Summarized,our data provide an important basis for further investigation of gene functions in order to aid an improved heat tolerance and reduced losses of yield in barley as a model for cereal crops.

  13. The Finite Element Analysis of Bending Stress for Involute Cylindrical Spur Gear Based on ANSYS%基于ANSYS的直齿圆柱齿轮的有限元分析



    利用PRO/E强大的三维实体设计功能,精确地实现了直齿圆柱齿轮的三维建模。通过PRO/E与ANSYS的连接,将模型导入ANSYS软件中。在精确建模的基础上,应用有限元法分析了轮齿的变形及齿根应力。提出了精确、迅速计算最大齿根应力的方法,较常规的计算方法更符合实际情况,得到的结果更为可靠。%Due to the great 3-D solid design function of PRO/E, 3-D modeling of Cylindrical Spur Gear is exactly achieved. The model is introduced into the software of ANSYS, through the connection of PRO/E and ANSYS. Based on the exact modeling, the deformation of gear teeth and the stress of the root are analyzed by finite element method. Then an exact and rapid way of calculating the maximal stress of the root is proposed, which is more consistent with practical situation and can lead to more liable results, compared with regular calculating methods.

  14. D-Cycloserine Augmentation of Exposure-Based Cognitive Behavior Therapy for Anxiety, Obsessive-Compulsive, and Posttraumatic Stress Disorders: A Systematic Review and Meta-analysis of Individual Participant Data.

    Mataix-Cols, David; Fernández de la Cruz, Lorena; Monzani, Benedetta; Rosenfield, David; Andersson, Erik; Pérez-Vigil, Ana; Frumento, Paolo; de Kleine, Rianne A; Difede, JoAnn; Dunlop, Boadie W; Farrell, Lara J; Geller, Daniel; Gerardi, Maryrose; Guastella, Adam J; Hofmann, Stefan G; Hendriks, Gert-Jan; Kushner, Matt G; Lee, Francis S; Lenze, Eric J; Levinson, Cheri A; McConnell, Harry; Otto, Michael W; Plag, Jens; Pollack, Mark H; Ressler, Kerry J; Rodebaugh, Thomas L; Rothbaum, Barbara O; Scheeringa, Michael S; Siewert-Siegmund, Anja; Smits, Jasper A J; Storch, Eric A; Ströhle, Andreas; Tart, Candyce D; Tolin, David F; van Minnen, Agnes; Waters, Allison M; Weems, Carl F; Wilhelm, Sabine; Wyka, Katarzyna; Davis, Michael; Rück, Christian; Altemus, Margaret; Anderson, Page; Cukor, Judith; Finck, Claudia; Geffken, Gary R; Golfels, Fabian; Goodman, Wayne K; Gutner, Cassidy; Heyman, Isobel; Jovanovic, Tanja; Lewin, Adam B; McNamara, Joseph P; Murphy, Tanya K; Norrholm, Seth; Thuras, Paul


    Whether and under which conditions D-cycloserine (DCS) augments the effects of exposure-based cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders is unclear. To clarify whether DCS is superior to placebo in augmenting the effects of cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders and to evaluate whether antidepressants interact with DCS and the effect of potential moderating variables. PubMed, EMBASE, and PsycINFO were searched from inception to February 10, 2016. Reference lists of previous reviews and meta-analyses and reports of randomized clinical trials were also checked. Studies were eligible for inclusion if they were (1) double-blind randomized clinical trials of DCS as an augmentation strategy for exposure-based cognitive behavior therapy and (2) conducted in humans diagnosed as having specific phobia, social anxiety disorder, panic disorder with or without agoraphobia, obsessive-compulsive disorder, or posttraumatic stress disorder. Raw data were obtained from the authors and quality controlled. Data were ranked to ensure a consistent metric across studies (score range, 0-100). We used a 3-level multilevel model nesting repeated measures of outcomes within participants, who were nested within studies. Individual participant data were obtained for 21 of 22 eligible trials, representing 1047 of 1073 eligible participants. When controlling for antidepressant use, participants receiving DCS showed greater improvement from pretreatment to posttreatment (mean difference, -3.62; 95% CI, -0.81 to -6.43; P = .01; d = -0.25) but not from pretreatment to midtreatment (mean difference, -1.66; 95% CI, -4.92 to 1.60; P = .32; d = -0.14) or from pretreatment to follow-up (mean difference, -2.98, 95% CI, -5.99 to 0.03; P = .05; d = -0.19). Additional analyses showed that participants assigned to DCS were associated with lower symptom severity than those assigned to

  15. Stress analysis in maxillary incisor following fragment reattachment: A finite element analysis

    Attiguppe Ramasetty Prabhakar


    Full Text Available Objectives: To demonstrate stress propagation through three flowable composites used in fragment reattachment using finite element models. Study Design: It was a finite element analysis. Materials and Methods: Two permanent maxillary incisors were selected of which one was used as control. The test tooth was sectioned and reattached using simple reattachment technique. The groups were: Filtek Z350 (Group 1, G-aenial Universal Flo (Group 2, Esthet X-Flow (Group 3. Finite element models were created using cone beam computed tomography images of these teeth. Required physical properties of enamel, dentin, periodontal ligament (PDL, bone, flowable composites were fed into the software. Models were subjected to a load of 150N in a vertical direction. Analysis was done using ANSYS software wherein data were obtained in pictographic and numerical form (Von Mises' stresses [megapascal]. Results: Among flowable composites, maximum stress was created in Esthet X-Flow whereas least stress was observed in Filtek Z350. Maximum stress concentration occurred at the point of load application for flowable composite and enamel, at the point of load application directed in the cervical direction of the crown for dentin, in the apical region for PDL and the cervical bone area for bone. Conclusion: The study revealed that Filtek Z350 had superior tested properties and showed the least stress propagation.


    Lei Xiaoyan


    A simple interface element for analyzing contact friction problems is developed. Taking nodal displacements and contact stresses as unknowns, this element can simulate frictional slippage, decoupling and re-bonding of two bodies initially mating or having gaps at a common interface. The method is based on the Finite Element Method and load incremental theory. The geometric and static constraint conditions on contact surfaces are treated as additional conditions and are included in stiffness equations. This simple element has the advantages of easy implementation into standard finite element programs and fast speed for conv ergence as well as high accuracy for stress distribution in interface. Undesirable stress oscillations are also investigated whenever large stress gradients exist over the contact surfaces. Exact integration or the conventional Gauss integration scheme used to evaluate the interpolation function matrix of the interface element is found to be the source of the oscillations. Eigenmode analysis demonstrates that the stress behavior of an interface element can be improved by using the Newton-Cotes integration scheme. Finally, the test example of a strip footing problem is presented.

  17. Finite element analysis of stress and strain distributions in mortise and loose tenon furniture joints

    Mohammad Derikvand; Ghanbar Ebrahimi


    We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon (M<) furni-ture joints under uniaxial bending loads, and determined the effects of loose tenon length (30, 45, 60, and 90 mm) and loose tenon thickness (6 and 8 mm) on bending moment capacity of M< joints constructed with polyvinyl acetate (PVAc) adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element (FE) software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon sur-faces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corre-sponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints.

  18. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Caborgan, R.; Muracciole, J. M.; Wattrisse, B.; Chrysochoos, A.


    Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard thermo-elastic effect noticed at small elongations and the thermoelastic inversion effects [4]. This paper aims at : observing and quantifying dissipative and coupling effects associated with deformation energy, generated when Natural Rubber is stretched. re-examine the thermomechanical behaviour model of rubberlike materials, under the generalised standard material concept. From an experimental viewpoint, energy balance is created using infrared and quantitative imaging techniques. Digital Image Correlation (DIC) provides in-the-plane displacement fields and, after derivation, strain and strain-rate fields. We have used those techniques to evidence the thermoelastic inversion effect as shown on Figure 1 where different weights have been fixed to warmed specimen and we monitored the sample deformation while it recovers room temperature. But we have also used those techniques to perform energy balance : analysis of the mechanical equilibrium allows estimates of the stress pattern and computation of deformation energy rates under a plane stress hypothesis [5]. Infrared Thermography (IRT) gives the surface temperature of the sample. To estimate the distribution of heat sources, image processing with a local heat equation and a minimal set of approximation functions (image filtering) was used. The time courses of deformation energy and heat associated with cyclic process are plotted in Figure 2. The time derivatives of both forms of energy are approximately similar. This is consistent with

  19. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Chrysochoos A.


    Full Text Available Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard thermo-elastic effect noticed at small elongations and the thermoelastic inversion effects [4]. This paper aims at : observing and quantifying dissipative and coupling effects associated with deformation energy, generated when Natural Rubber is stretched. re-examine the thermomechanical behaviour model of rubberlike materials, under the generalised standard material concept. From an experimental viewpoint, energy balance is created using infrared and quantitative imaging techniques. Digital Image Correlation (DIC provides in-the-plane displacement fields and, after derivation, strain and strain-rate fields. We have used those techniques to evidence the thermoelastic inversion effect as shown on Figure 1 where different weights have been fixed to warmed specimen and we monitored the sample deformation while it recovers room temperature. But we have also used those techniques to perform energy balance : analysis of the mechanical equilibrium allows estimates of the stress pattern and computation of deformation energy rates under a plane stress hypothesis [5]. Infrared Thermography (IRT gives the surface temperature of the sample. To estimate the distribution of heat sources, image processing with a local heat equation and a minimal set of approximation functions (image filtering was used. The time courses of deformation energy and heat associated with cyclic process are plotted in Figure 2. The time derivatives of both forms of energy are approximately similar. This

  20. Analysis of DNA Cytosine Methylation under Salt Stress in Carthamus tinctorius Based on MSAP%盐胁迫下红花基因组DNA甲基化的MSAP分析

    李慧; 彭立新; 于玮玮; 冯涛; 林木强; 阎国荣


    Analysis of DNA methylation status was carried out by MSAP (methylation-sensitive amplified polymorphism) method in Carthamus tinctorius L. After 200 mmol ? L"1 NaCl stress for 0,4,8 and 12 h, respectively. Totally, 3 140 genetic loci were produced by 13 pairs of selective primers. The results indicated that the corresponding total DNA methylation ratios were 31. 8%, 27. 1% 31. 0% and 31. 3% in the samples treated by NaCl stress for 0,4,8 and 12 h, respectively. Further analysis of the DNA methylation patterns suggested that demethylation adjustment was predominant in 4 h samples, however, the methylation level was got back to the level of CK in 8 and 12 h samples, and methylation adjustment was almost consistent with demethylation adjustment. These results indicated that the changes of DNA methylation status were closely associated with the responses of salt stress in Carthamus tinctorius L.%以红花幼苗为研究材料,经200 mmol·L-1 NaCl溶液分别处理4、8、12 h,以未经盐胁迫处理为对照(CK),对DNA甲基化变化特征进行MSAP(甲基化敏感扩增多态性)分析.选用13对选扩引物,共检测到3 140个基因位点.甲基化水平分析表明,CK,4、8、12 h处理样本中总甲基化率分别为31.8%、27.1%、31.0%和31.3%.进一步对不同处理时间红花基因组DNA甲基化模式的变化特征进行分析表明,NaCl处理4h后DNA的去甲基化模式调整占优势,而处理8h及12h后DNA甲基化水平恢复到CK水平,甲基化及去甲基化模式调整基本一致.上述结果显示,盐胁迫条件下红花基因组DNA甲基化状态发生了一定变化,并且这种变化与盐胁迫程度相关,推测DNA甲基化修饰可能参与了红花的盐胁迫应答.

  1. Stress analysis in curved composites due to thermal loading

    Polk, Jared Cornelius

    Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, longer fatigue life, lower density, possibilities in reduction of life cycle and/or acquisition cost, and greater adaptability to intended function of structure via material composition and geometry. To be able to design and manufacture a safe composite laminate or structure, it is imperative that the stress distributions, their causes, and effects are thoroughly understood in order to successfully accomplish mission objectives and manufacture a safe and reliable composite. The objective of the thesis work is to expand upon the knowledge of simply curved composite structures by exploring and ascertaining all pertinent parameters, phenomenon, and trends in stress variations in curved laminates due to thermal loading. The simply curved composites consist of composites with one radius of curvature throughout the span of the specimen about only one axis. Analytical beam theory, classical lamination theory, and finite element analysis were used to ascertain stress variations in a flat, isotropic beam. An analytical method was developed to ascertain the stress variations in an isotropic, simply curved beam under thermal loading that is under both free-free and fixed-fixed constraint conditions. This is the first such solution to Author's best knowledge

  2. Effect of Zirconia Thickness on the Tensile Stress of Zirconia Based All-Ceramic Restorations

    Masood Shiezadeh


    Full Text Available Introduction: The purpose of the presented study was to evaluate the effect of zirconia thickness on the tensile stress of zirconia based all-ceramic restorations. Methods: Twenty zirconia disks with 10mm diameter were prepared in two groups using CAD/CAM system. The thickness of zirconia was 0.5mm in first group and 0.3mm in second group. After sintering, 0.4mm glass ceramic porcelain was applied to each disk. Then, sintering and glazing of porcelain carried out. Instron testing machine with 1mm/min crosshead speed used to evaluate the failure load of the samples. Biaxial Flexural strength standard formula employed to calculate tensile stress of specimens. Statistical analysis performed using SPSS software. Results: Although data analysis showed more maximum tensile stress in 1st group, no significant differences were found between two groups. Conclusion: Zirconia with 0.5mm and 0.3mm thicknesses cause similar tensile stress in all-ceramic restorations and thickness of these laminates could be reduced to 0.7mm.

  3. Analytical solution for stress and deformation of the mining floor based on integral transform

    Feng Qiang; Jiang Binsong


    Following exploitation of a coal seam, the final stress field is the sum of in situ stress field and an exca-vation stress field. Based on this feature, we firstly established a mechanics analytical model of the min-ing floor strata. Then the study applied Fourier integral transform to solve a biharmonic equation, obtaining the analytical solution of the stress and displacement of the mining floor. Additionally, this investigation used the Mohr–Coulomb yield criterion to determine the plastic failure depth of the floor strata. The calculation process showed that the plastic failure depth of the floor and floor heave are related to the mining width, burial depth and physical–mechanical properties. The results from an exam-ple show that the curve of the plastic failure depth of the mining floor is characterized by a funnel shape and the maximum failure depth generates in the middle of mining floor;and that the maximum and min-imum principal stresses change distinctly in the shallow layer and tend to a fixed value with an increase in depth. Based on the displacement results, the maximum floor heave appears in the middle of the stope and its value is 0.107 m. This will provide a basis for floor control. Lastly, we have verified the analytical results using FLAC3D to simulate floor excavation and find that there is some deviation between the two results, but their overall tendency is consistent which illustrates that the analysis method can well solve the stress and displacement of the floor.

  4. Stress field modeling of the Carpathian Basin based on compiled tectonic maps

    Albert, Gáspár; Ungvári, Zsuzsanna; Szentpéteri, Krisztián


    The estimation of the stress field in the Carpathian Basin is tackled by several authors. Their modeling methods usually based on measurements (borehole-, focal mechanism- and geodesic data) and the result is a possible structural pattern of the region. Our method works indirectly: the analysis is aimed to project a possible 2D stress field over the already mapped/known/compiled lineament pattern. This includes a component-wise interpolation of the tensor-field, which is based on the generated irregular point cloud in the puffer zone of the mapped lineaments. The interpolated values appear on contour and tensor maps, and show the relative stress field of the area. In 2006 Horváth et al. compiled the 'Atlas of the present-day geodynamics of the Pannonian basin'. To test our method we processed the lineaments of the 1:1 500 000 scale 'Map of neotectonic (active) structures' published in this atlas. The geodynamic parameters (i.e. normal, reverse, right- and left lateral strike-slip faults, etc.) of the lines on this map were mostly explained in the legend. We classified the linear elements according to these parameters and created a geo-referenced mapping database. This database contains the polyline sections of the map lineaments as vectors (i.e. line sections), and the directions of the stress field as attributes of these vectors. The directions of the dip-parallel-, strike-parallel- and vertical stress-vectors are calculated from the geodynamical parameters of the line section. Since we created relative stress field properties, the eigenvalues of the vectors were maximized to one. Each point in the point cloud inherits the stress property of the line section, from which it was derived. During the modeling we tried several point-cloud generating- and interpolation methods. The analysis of the interpolated tensor fields revealed that the model was able to reproduce a geodynamic synthesis of the Carpathian Basin, which can be correlated with the synthesis of the

  5. Evaluation of Transverse Thermal Stresses in Composite Plates Based on First-Order Shear Deformation Theory

    Rolfes, R.; Noor, A. K.; Sparr, H.


    A postprocessing procedure is presented for the evaluation of the transverse thermal stresses in laminated plates. The analytical formulation is based on the first-order shear deformation theory and the plate is discretized by using a single-field displacement finite element model. The procedure is based on neglecting the derivatives of the in-plane forces and the twisting moments, as well as the mixed derivatives of the bending moments, with respect to the in-plane coordinates. The calculated transverse shear stiffnesses reflect the actual stacking sequence of the composite plate. The distributions of the transverse stresses through-the-thickness are evaluated by using only the transverse shear forces and the thermal effects resulting from the finite element analysis. The procedure is implemented into a postprocessing routine which can be easily incorporated into existing commercial finite element codes. Numerical results are presented for four- and ten-layer cross-ply laminates subjected to mechanical and thermal loads.

  6. Functional analysis of stress protein data in a flor yeast subjected to a biofilm forming condition

    Jaime Moreno-García


    Full Text Available In this data article, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment and a SGD filtering were used to detect in a biofilm-forming flor yeast strain, the maximum possible number of stress proteins under the first stage of a biofilm formation conditions (BFC and under an initial stage of fermentation used as reference, so-called non-biofilm formation condition (NBFC. Protein functional analysisbased on cellular components and biological process GO terms – was performed for these proteins through the SGD Gene Ontology Slim Mapper tool. A detailed analysis and interpretation of the data can be found in “Stress responsive proteins of a flor yeast strain during the early stages of biofilm formation” [1].

  7. Functional analysis of stress protein data in a flor yeast subjected to a biofilm forming condition

    Moreno-García, Jaime; Mauricio, Juan Carlos; Moreno, Juan; García-Martínez, Teresa


    In this data article, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment and a SGD filtering were used to detect in a biofilm-forming flor yeast strain, the maximum possible number of stress proteins under the first stage of a biofilm formation conditions (BFC) and under an initial stage of fermentation used as reference, so-called non-biofilm formation condition (NBFC). Protein functional analysisbased on cellular components and biological process GO terms – was performed for these proteins through the SGD Gene Ontology Slim Mapper tool. A detailed analysis and interpretation of the data can be found in “Stress responsive proteins of a flor yeast strain during the early stages of biofilm formation” [1]. PMID:27104213

  8. Mechanical vulnerability of lower second premolar utilising visco-elastic dynamic stress analysis.

    Khani, M M; Tafazzoli-Shadpour, M; Aghajani, F; Naderi, P


    Stress analysis determines vulnerability of dental tissues to external loads. Stress values depend on loading conditions, mechanical properties and constrains of structural components. The critical stress levels lead to tissue damage. The aim of this study is to analyse dynamic stress distribution of lower second premolar due to physiological cyclic loading, and dependency of pulsatile stress characteristics to visco-elastic property of dental components by finite element modelling. Results show that visco-elastic property markedly influences stress determinants in major anatomical sites including dentin, cementum-enamel and dentin-enamel junctions. Reduction of visco-elastic parameter leads to mechanical vulnerability through elevation of stress pulse amplitude, maximum stress value; and reduction of stress phase shift as a determinant of stress wave propagation. The results may be applied in situations in which visco-elasticity is reduced such as root canal therapy and post and core restoration in which teeth are more vulnerable to fracture.



    The linear isothermo-viscoelastic constitutive equation is established according to the principle of viscoelastic mechanics. Given the boundary conditions of the temperature field, the linear themo-viscoelastic constitutive equation is established acording to the analysis of the thermorheologically simple. The stress analysis model is constructed on the base of some reasonable hypotheses which consider the restraint conditions of mold and the characteristics of injection molding in the post-filling stage. The mathematical model is calculated by the finite difference method. The results can help to predict the warpage of plastic products.

  10. Core based stress measurements: A guide to their application. Topical report, July 1991--June 1993

    Warpinski, N.R.; Teufel, L.W.; Lorenz, J.C.; Holcomb, D.J. [Sandia National Labs., Albuquerque, NM (United States)


    This report is a summary and a guide to core-based stress measurements. It covers anelastic strain recovery, circumferential velocity anistropy, differential strain curve analysis, differential wave velocity analysis, petrographic examination of microcracks, overcoring of archieved core, measurements of the Kaiser effect, strength anisotropy tests, and analysis of coring-induced fractures. The report begins with a discussion of the stored energy within rocks, its release during coring, and the subsequent formation of relaxation microcracks. The interogation or monitoring of these microcracks form the basis for most of the core-based techniques (except for the coring induced fractures). Problems that can arise due to coring or fabric are also presented, Coring induced fractures are discussed in some detail, with the emphasis placed on petal (and petal-centerline) fractures and scribe-knife fractures. For each technique, a short description of the physics and the analysis procedures is given. In addition, several example applications have also been selected (where available) to illustrate pertinent effects. This report is intended to be a guide to the proper application and diagnosis of core-based stress measurement procedures.

  11. NMR-Based Metabonomic Investigation of Heat Stress in Myotubes Reveals a Time-Dependent Change in the Metabolites

    Straadt, Ida K; Young, Jette F; Bross, Peter;


    NMR-based metabonomics was applied to elucidate the time-dependent stress responses in mouse myotubes after heat exposure of either 42 or 45 degrees C for 1 h. Principal component analysis (PCA) revealed that the gradual time-dependent changes in metabolites contributing to the clustering...... and separation of the control samples from the different time points after heat stress primarily are in the metabolites glucose, leucine, lysine, phenylalanine, creatine, glutamine, and acetate. In addition, PC scores revealed a maximum change in metabolite composition 4 h after the stress exposure; thereafter......, samples returned toward control samples, however, without reaching the control samples even 10 h after stress. The results also indicate that the myotubes efficiently regulate the pH level by release of lactate to the culture medium at a heat stress level of 42 degrees C, which is a temperature level...

  12. Stress analysis in oral obturator prostheses: imaging photoelastic

    Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; dos Santos, Daniela Micheline; Haddad, Marcela Filié; Andreotti, Agda Marobo; Moreno, Amália


    Maxillary defects resulting from cancer, trauma, and congenital malformation affect the chewing efficiency and retention of dentures in these patients. The use of implant-retained palatal obturator dentures has improved the self-esteem and quality of life of several subjects. We evaluate the stress distribution of implant-retained palatal obturator dentures with different attachment systems by using the photoelastic analysis images. Two photoelastic models of the maxilla with oral-sinus-nasal communication were fabricated. One model received three implants on the left side of the alveolar ridge (incisive, canine, and first molar regions) and the other did not receive implants. Afterwards, a conventional palatal obturator denture (control) and two implant-retained palatal obturator dentures with different attachment systems (O-ring; bar-clip) were constructed. Models were placed in a circular polariscope and a 100-N axial load was applied in three different regions (incisive, canine, and first molar regions) by using a universal testing machine. The results were photographed and analyzed qualitatively using a software (Adobe Photoshop). The bar-clip system exhibited the highest stress concentration followed by the O-ring system and conventional denture (control). Images generated by the photoelastic method help in the oral rehabilitator planning.

  13. Analysis of Mechanical Stresses/Strains in Superconducting Wire

    Barry, Matthew; Chen, Jingping; Zhai, Yuhu


    The optimization of superconducting magnet performance and development of high-field superconducting magnets will greatly impact the next generation of fusion devices. A successful magnet development, however, relies deeply on the understanding of superconducting materials. Among the numerous factors that impact a superconductor's performance, mechanical stress is the most important because of the extreme operation temperature and large electromagnetic forces. In this study, mechanical theory is used to calculate the stresses/strains in typical superconducting strands, which consist of a stabilizer, a barrier, a matrix and superconducting filaments. Both thermal loads and mechanical loads are included in the analysis to simulate operation conditions. Because this model simulates the typical architecture of major superconducting materials, such as Nb3Sn, MgB2, Bi-2212 etc., it provides a good overall picture for us to understand the behavior of these superconductors in terms of thermal and mechanical loads. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

  14. Acid and base stress and transcriptomic responses in Bacillus subtilis.

    Wilks, Jessica C; Kitko, Ryan D; Cleeton, Sarah H; Lee, Grace E; Ugwu, Chinagozi S; Jones, Brian D; BonDurant, Sandra S; Slonczewski, Joan L


    Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K(+)/H(+) antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.

  15. Analysis of stress and natural frequencies of high-speed spatial parallel mechanism

    陈修龙; 李文彬; 邓昱; 李云峰


    In order to grasp the dynamic behaviors of 4-UPS-UPU high-speed spatial parallel mechanism, the stress of driving limbs and natural frequencies of parallel mechanism were investigated. Based on flexible multi-body dynamics theory, the dynamics model of 4-UPS-UPU high-speed spatial parallel mechanism without considering geometric nonlinearity was derived. The stress of driving limbs and natural frequencies of 4-UPS-UPU parallel mechanism with specific parameters were analyzed. The relationship between the basic parameters of parallel mechanism and its dynamic behaviors, such as stress of driving limbs and natural frequencies of parallel mechanism, were discussed. The numerical simulation results show that the stress and natural frequencies are relatively sensitive to the section parameters of driving limbs, the characteristic parameters of material on driving limbs, and the mass of moving platform. The researches can provide important theoretical base of the analysis of dynamic behaviors and optimal design for high-speed spatial parallel mechanism.

  16. Inclusion of Respiratory Frequency Information in Heart Rate Variability Analysis for Stress Assessment.

    Hernando, Alberto; Lazaro, Jesus; Gil, Eduardo; Arza, Adriana; Garzon, Jorge Mario; Lopez-Anton, Raul; de la Camara, Concepcion; Laguna, Pablo; Aguilo, Jordi; Bailon, Raquel


    Respiratory rate and heart rate variability (HRV) are studied as stress markers in a database of young healthy volunteers subjected to acute emotional stress, induced by a modification of the Trier Social Stress Test. First, instantaneous frequency domain HRV parameters are computed using time-frequency analysis in the classical bands. Then, the respiratory rate is estimated and this information is included in HRV analysis in two ways: 1) redefining the high-frequency (HF) band to be centered at respiratory frequency; 2) excluding from the analysis those instants where respiratory frequency falls within the low-frequency (LF) band. Classical frequency domain HRV indices scarcely show statistical differences during stress. However, when including respiratory frequency information in HRV analysis, the normalized LF power as well as the LF/HF ratio significantly increase during stress ( p-value 0.05 according to the Wilcoxon test), revealing higher sympathetic dominance. The LF power increases during stress, only being significantly different in a stress anticipation stage, while the HF power decreases during stress, only being significantly different during the stress task demanding attention. Our results support that joint analysis of respiration and HRV obtains a more reliable characterization of autonomic nervous response to stress. In addition, the respiratory rate is observed to be higher and less stable during stress than during relax ( p-value 0.05 according to the Wilcoxon test) being the most discriminative index for stress stratification (AUC = 88.2 % ).

  17. Proteomic analysis of salt-stressed tomato (Solanum lycopersicum) seedlings: effect of genotype and exogenous application of glycinebetaine.

    Chen, Songbi; Gollop, Natan; Heuer, Bruria


    An investigation aimed at a better understanding of the molecular adaptation mechanisms of salt stress was carried out in 7-d-old tomato Solanum lycopersicum (L.) Mill cultivars Patio and 'F144', using a proteomic approach. Total proteins were extracted from radicles and hypocotyls collected from both non-saline control and salt-stressed seedlings, and separated by two-dimensional gel electrophoresis. Liqud chromatography-electron spray ionization tandem mass spectrometry (LC-ESI-MS/MS) identified 23 salt stress response proteins, classified into six functional categories. The effect of exogenously applied glycinebetaine (GB) on the salt stress-induced inhibition of growth in tomato seedlings of cultivars Patio and 'F144' and on the protein profile was investigated. It was found that GB could alleviate the inhibition of tomato growth induced by salt stress through changing the expression abundance of six proteins in Patio and two proteins in 'F144' more than twice compared with salt-stressed seedlings. Furthermore, the interaction analysis based on computational bioinformatics reveals major regulating networks: photosystem II (PSII), Rubisco, and superoxide dismutase (SOD). The results suggest that it is likely that improvement of salt tolerance in tomato might be achieved through the application of exogenous compatible solutes, such as GB. Moreover, quantitative and qualitative analysis of the differentially expressed proteins of tomato under salt stress is an important step towards further elucidation of mechanisms of salt stress resistance.

  18. Contact Stress FEM analysis of Deep Groove Ball Bearing Based on ANSYS Workbench%基于ANSYS Workbench的深沟球轴承接触应力有限元分析

    张福星; 郑源; 汪清; 李杰; 徐素红; 辛华荣; 吴忠


    利用ANSYS Workbench软件建立了深沟球轴承的三维非线性接触模型,对模型的边界条件进行合理的设置后,基于有限元的方法,在Static Structural(ANSYS)中对深沟球轴承的接触应力和变形进行了仿真计算,得到了轴承滚动体和内、外圈不同部位接触应力和变形的分布.计算结果与Hertz理论解进行了对比,两者具有良好的一致性,说明了用ANSYS Workbench分析滚动轴承接触问题是可行的,符合轴承在载荷作用下受力和变形的实际情况;有限元仿真计算的结果为滚动轴承的设计、优化和失效分析提供了参考依据,具有一定的工程实用价值.%The 3D nonlinear contact model of a deep groove ball bearing was established in ANSYS Workbench sofiware.With the reasonable setting of the boundary conditions,the contact stress and deformation were calculated in Static Structural (ANSYS)by using the finite element method,and the contact stress and deformation of the inner ring, the outer ting and the rolling elements were obtained.Furthermore the computational values are consistent with the Hertz values.The results show that solving the bearing contact problem with ANSYS Workbench software is feasible and it coincides with the stress and deformation of the actual situation.The FEM results provide reference for the design, optimization and failure analysis of rolling bearings and have practical engineering value.

  19. Spline Nonparametric Regression Analysis of Stress-Strain Curve of Confined Concrete

    Tavio Tavio


    Full Text Available Due to enormous uncertainties in confinement models associated with the maximum compressive strength and ductility of concrete confined by rectilinear ties, the implementation of spline nonparametric regression analysis is proposed herein as an alternative approach. The statistical evaluation is carried out based on 128 large-scale column specimens of either normal-or high-strength concrete tested under uniaxial compression. The main advantage of this kind of analysis is that it can be applied when the trend of relation between predictor and response variables are not obvious. The error in the analysis can, therefore, be minimized so that it does not depend on the assumption of a particular shape of the curve. This provides higher flexibility in the application. The results of the statistical analysis indicates that the stress-strain curves of confined concrete obtained from the spline nonparametric regression analysis proves to be in good agreement with the experimental curves available in literatures

  20. Multiple-reflection effects in photoelastic stress analysis.

    Bhowmik, A K


    The interpretation of fringes observed in photoelastic stress measurements made with coherent well-collimated optical radiation such as a laser beam and slab specimens with parallel surfaces is affected by multiple internal reflections of light within the sample, which are usually negligible when incoherent light is used. An analysis of the multiple-reflection effects in photoelastic measurements involving the plane polariscope configuration is presented. The results show that the isochromatic fringes are modified by the interference of multiply reflected waves. The multipass differential phase accumulations that display oscillatory magnitudes as functions of the model thickness and the optical wavelength result in a shifted and altered intensity profile across the isochromatic fringes. It is shown that for large values of reflectivity, as in the case of samples with reflective coating or partial mirrors, the bright fringes split into multiple peaks.

  1. Photoelastic stress analysis on a Phoenix 7. 9-meter blade

    Musial, W D; Jenks, M D; Osgood, R M; Johnson, J A


    Photoelastic tests were conducted on the Phoenix 7.9-meter blade to develop the basic methodology for locating critical strain areas on full-scale composite structures. Under relatively low elastic loading the strain fields over various regions on the blade planform were documented with 35mm photographs under different loading conditions at the Solar Energy Research Institute (SERI) Structural Test Facility (STF). Strain concentrations were easily located and quantified. Principal strain magnitudes and directions were determined at the highest strain areas using separator gages. Results were compared to measured operating loads. This experiment demonstrated the value of experimental stress analysis using the photoelastic technique for the evaluation of composite blade designs. 9 refs., 6 figs., 3 tabs.

  2. Stress

    Keller, Hanne Dauer


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

  3. Stress

    Keller, Hanne Dauer


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

  4. A memory-based model of posttraumatic stress disorder

    Rubin, David C.; Berntsen, Dorthe; Johansen, Marlene Klindt


    . Predisposing factors that affect the current memory have large effects on symptoms. The inability-to-recall-an-important-aspect-of-the-trauma symptom does not correlate with other symptoms. Loss or enhancement of the trauma memory affects PTSD symptoms in predictable ways. Special mechanisms that apply only......In the mnemonic model of posttraumatic stress disorder (PTSD), the current memory of a negative event, not the event itself, determines symptoms. The model is an alternative to the current event-based etiology of PTSD represented in the Diagnostic and Statistical Manual of Mental Disorders (4th ed...... objective information about the trauma and peritraumatic emotions but uses retrospective memory reports that can have substantial biases. Negative events and emotions that do not satisfy the current diagnostic criteria for a trauma can be followed by symptoms that would otherwise qualify for PTSD...

  5. Biomonitor of Environmental Stress: Coral Trace Metal Analysis

    Grumet, N.; Hughen, K.


    Tropical reef corals are extremely sensitive to changes in environmental conditions and, as a result of environmental degradation and global climate change, coral reefs around the globe are severely threatened. Increased human population and development in tropical regions is leading to higher turbidity and silt loading from terrestrial runoff, increased pesticides and nutrients from agricultural land-use and sewage, and the release of toxic trace metals to coastal waters from industrial pollution. The uptake of these metals and nutrients within the coral skeletal aragonite is a sensitive biomonitor of environmental stresses on coral health. We analyzed 18 trace metals from the surface of coral skeletons collected in Bermuda, Indonesia and Belize to assess a range of threats to coral reef health - including climate change, agricultural runoff and pesticides, and coastal development and tourism. This surface sample network also includes samples representing 4 different coral species. Trace metal analysis was performed on an inductively coupled plasma mass spectrometer (ICP-MS) to a high degree of accuracy and precision at extremely low (ppb) concentrations using a protocol we developed for samples less than 2 mg. Proper cleaning techniques were employed to minimize blank level concentrations for ultra-trace metal ICP-MS solution analysis. However, Zn/Ca and Ni/Ca concentrations remain below analytical detection limits. Initial results indicate that sea surface temperature proxies (e.g., Sr/Ca, B/Ca and Mg/Ca) display similar ratios between the different sites, whereas those metals associated with anthropogenic activities, such as Co, Pb and Cu, are site-specific and are linked to individual environmental stressors. Results from this study will be applied to down core trace metal records in the future. In doing so, we aim to understand the impacts of compounding environmental stresses on coral health, and to identify regional threshold values beyond which corals

  6. Stress analysis of advanced attack helicopter composite main rotor blade root end lug

    Baker, D. J.


    Stress analysis of the Advanced Attack Helicopter (AAH) composite main rotor blade root end lug is described. The stress concentration factor determined from a finite element analysis is compared to an empirical value used in the lug design. The analysis and test data indicate that the stress concentration is primarily a function of configuration and independent of the range of material properties typical of Kevlar-49/epoxy and glass epoxy.

  7. Analysis of stress, musculoskeletal disorders, and fatigue among broadcasting actors

    Park, Moon-Hee; Kim, Ham-Gyum; Lee, Hae-Kag


    [Purpose] The purpose of the study was to assess the health effects of broadcasting actors through a comprehensive research on their job stress, psychosocial stress, and fatigue and to investigate those factors having an impact on their health condition to present a basis for comparative studies and effective human resource management in the future. [Subjects and Methods] A survey was performed to analyze the relevance of the general features, job stress, psychosocial stress, and fatigue. [Re...


    X.C.Zhao; Y.D.Zhang; H.W.Zhang; Q.Wu


    A finite element model is developed for the simulation of vibration stress relief (VSR) after welding.For the nonresonant vibration,the reduction in stress strongly depends on the amplitude of vibration.For the resonant vibration,the vibration frequency is the key for stress relief.The vibration frequency should be close to the structure natural frequency for the desired vibration mode.Only small vibration amplitude is required,which will be amplified during vibration.Vibration time does not have a major impact on vibration stress relief.When the amplitude of vibration stress relief is large,the treatment will be more effective.

  9. X-ray stress analysis during cyclic loading

    Ohya, Shin-ichi [Musashi Inst. of Tech., Tokyo (Japan)


    For an aim to make possible to conduct speed-up and time-serial measurement of x-ray stress measurement in the fatigue test, a diffraction intensity curve at each loading stress stage in a repeating stress period was measured in time-serial sharing and devised ``a time-sharing continuous stress measuring method by a single incident method`` to measure the stress continuously. Then, by using this method an actual stress change measurement was conducted in a four points supporting bending test, to investigate on precision of the stress measurement and effectiveness of this method. As a result, the results shown as follows were elucidated. An actual stress change in a fatigue test could be observed directly. And, it was confirmed that an actual stress state in each loading stress stage in one loading stress period is independent on repeating speed under about 8 Hz and is an algebraic sum of residual and loading stresses. Furthermore, it was found that by this method a dynamic fatigue cleavage phenomena could be observed. (G.K.)

  10. The analysis of stress reactions ana coping patterns of cancer patients who perceived stress by radiotherapy

    Bang, Dong Han; Kim, Jin Su; Park, Gil Yong; Son, Mi Suk [Dept. of Radiation Oncology, Bundang CHA General Hospital, College of Medicine, Pochon CHA University, Sungnam (Korea, Republic of)


    This study is performed to encourage cancer patients to identify, relieve and effectively overcome the stress caused by radiotherapy, by analyzing stress reactions and coping patterns of cancer patients who perceived stress due to radiotherapy. The study group was composed of 85 cancer patients of the age 20 or higher who were undergoing radiotherapy in four hospitals located in Seoul and Kyonggi-do. The survey questionnaire was used, which had 161 questions inquiring respondents of general status, perceived stress, stress reactions and coping patterns. The surveyed data were analyzed by a SAS program, which employed descriptive statistics. Pearson Correlation Coefficient, t-test, ANOVA and Stepwised Multiple Regression. The stress perception and reaction rates were low in cancer patients comparing to patients of the other study. In the coping patterns. the problem-focused coping patterns were significantly higher than emotion-focused coping patterns. The statistically meaningful differences were observed in the stress perception and reactions depending on the time of diagnosis and perceived health level. As for the problem-focused coping patterns, significant differences were found depending on age, marital status, education, income and the number of family members as well as perceived health level of patients. The level of perceived stress and that of stress reactions was found to have positively significant correlation(r=.764, p<.001) while the perceived stress and the problem-focused coping patterns was correlated negatively (r=-.288, p<.01). The stress reactions and the problem-focused coping patterns was found to have negatively significant correlation(r=-.289, p<.01). The problem-focused coping behavior, which cooperated with doctors, technologists, nurses and families of cancer patients, is advisable for the cancer patients to overcome uncertainty and uneasiness by effectively release the stress.

  11. Loading and Contact Stress Analysis on the Thread Teeth in Tubing and Casing Premium Threaded Connection

    Honglin Xu


    Full Text Available Loading and contact stress distribution on the thread teeth in tubing and casing premium threaded connections are of great importance for design optimization, pretightening force control, and thread failure prevention. This paper proposes an analytical method based on the elastic mechanics. This is quite different from other papers, which mainly rely on finite element analysis. The differential equation of load distribution on the thread teeth was established according to equal pitch of the engaged thread after deformation and solved by finite difference method. Furthermore, the relation between load acting on each engaged thread and mean contact stress on its load flank is set up based on the geometric description of thread surface. By comparison, this new analytical method with the finite element analysis for a modified API 177.8 mm premium threaded connection is approved. Comparison of the contact stress on the last engaged thread between analytical model and FEM shows that the accuracy of analytical model will decline with the increase of pretightening force after the material enters into plastic deformation. However, the analytical method can meet the needs of engineering to some extent because its relative error is about 6.2%~18.1% for the in-service level of pretightening force.

  12. Solid Dynamic Models for Analysis of Stress and Strain in Human Hearts

    Qiu Guan


    Full Text Available This paper proposes a solid model based on four-dimensional trivariate B-spline for strain and stress analysis of ventricular myocardium. With a series of processing steps in the four-dimensional medical images, the feature points of ventricular inner and outer wall are obtained. A B-spline surface is then used to build the dynamic deformation model of the myocardial walls. With such a surface model, a hexahedron control mesh can be constructed by sweeping the cloud data, and the ventricular solid model is built by fitting the trivariate B-spline parameters. Based on these models, a method of isogeometric analysis can be applied to calculate the stress and strain continuously distributed in the ventricle. The model is represented smoothly in the cylindrical coordinate system and is easy to measure myocardium dynamics for finding abnormal motion. Experiments are carried out for comparing the stress and strain distribution. It is found that the solid model can determine ventricular dynamics which can well reflect the deformation distribution in the heart and imply early clues of cardiac diseases.

  13. An inverse method for online stress monitoring and fatigue life analysis of boiler drums

    HU Wen-sen; LI Bin; CAO Zi-dong; YANG Dong; LI Ya-chao


    A method based on solution of the inverse heat conduction problem was presented for online stress monitoring and fatigue life analysis of boiler drums. The mathematical model of the drum temperature distribution is based on the assumptions that the difference of temperature along the longitudinal axis of the boiler drum is negligible with changes only in the radial direction and the circumferential direction, and that the outer surface of drum is thermally insulated. Combining this model with the control-volume method provides temperatures at different points on a eross-section of the drum. With the temperature data, the stresses and the life expectancy of the boiler drum are derived according to the ASME code. Applying this method to the cold start-up process of a 300 MW boiler demonswated the absence of errors caused by the boundary condition assumptions on the inner surface of the drum and testified that the method is an applicable technique for the online stress monitoring and fatigue life analysis of boiler drums.

  14. Evaluation of stresses caused by dentin pin with finite elements stress analysis method.

    Ersöz, E


    The aim of the present study was to show the dimensions and the amount of stresses caused by pins on dentin. Mathematically modelled stainless steel and titanium pins were applied to mandibular first molar teeth with extensive crown destruction. The stress caused by the pins was examined with the finite elements method (FEM). In both types of pin, the maximum diffuse and the dense stress areas were located at the bottom of the pin channel. It is believed that these stresses should be taken into consideration when evaluating the advantages and disadvantages of pin application to teeth with destroyed crowns.

  15. Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

    Yang, Xiaobin, E-mail:; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo


    Highlights: • The differential equation including temperature and magnetic field was derived for a long cylindrical superconductor. • Thermal stress and electromagnetic stress were studied at the same time under pulse field magnetizing. • The distributions of the magnetic field, the temperature and stresses are studied and compared for two pulse fields of the different duration. • The Role thermal stress and electromagnetic stress play in the process of pulse field magnetizing is discussed. - Abstract: A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

  16. College Students Coping with Interpersonal Stress: Examining a Control-Based Model of Coping

    Coiro, Mary Jo; Bettis, Alexandra H.; Compas, Bruce E.


    Objective: The ways that college students cope with stress, particularly interpersonal stress, may be a critical factor in determining which students are at risk for impairing mental health disorders. Using a control-based model of coping, the present study examined associations between interpersonal stress, coping strategies, and symptoms.…

  17. Citation analysis of meta-analysis articles on posttraumatic stress disorder

    LIAO Xi-ming; CHEN Ping-yan


    Background In the past two decades enormously scientific researches on posttraumatic stress disorder (PTSD) have been undertaken and many related meta-analyses have been published. Citation analysis was used to get comprehensive perspectives of meta-analysis articles (MA articles) on PTSD for the purpose of facilitating the researchers,physicians and policy-makers to understand the PTSD.Methods MA articles on PTSD in any languages from January 1980 to March 2009 were included if they presented meta-analytical methods and received at least one citation recorded in the Web of Science (WoS). Whereas studies,in which any effect sizes of PTSD were not distinguished from other psychological disorders,were excluded. Citations to and by identified MA articles were documented basing on records in WoS. Citation analysis was used to examine distribution patterns of characteristics and citation impact of MA articles on PTSD. Canonical analysis was used to explore the relationship between the characteristics of MA articles and citation impact.Results Thirty-four MA articles published during 1998 and 2008 were identified and revealed multiple study topics on PTSD:10 (29.4%) were about epidemiology,13 (38.2%) about treatment or intervention,6 (17.6%) about pathophysiology or neurophysiology or neuroendocrine,3 (8.8%) about childhood and 2 (5.9%) about psychosocial adversity. Two articles cited most frequently with 456 and 145 counts were published in Journal of Consulting and Clinical Psychology by Brewin (2000) and Psychological Bulletin by Ozer (2003),respectively. Mean cited count was 7.48±10.56and mean age (year 2009 minus article publication year) was (4.24±2.91) years. They had been cited approximately by 67 disciplines and by authors from 42 countries or territories. Characteristics of meta-analysis highly correlated with citation impact and reflected by canonical correlation of 0.899 (P <0.000 01).Conclusions The age of MA articles predicted their citation impact

  18. Stress reduces use of negative feedback in a feedback-based learning task.

    Petzold, Antje; Plessow, Franziska; Goschke, Thomas; Kirschbaum, Clemens


    In contrast to the well-established effects of stress on learning of declarative material, much less is known about stress effects on reward- or feedback-based learning. Differential effects on positive and negative feedback especially have received little attention. The objective of this study, thus, was to investigate effects of psychosocial stress on feedback-based learning with a particular focus on the use of negative and positive feedback during learning. Participants completed a probabilistic selection task in both a stress and a control condition. The task allowed quantification of how much participants relied on positive and negative feedback during learning. Although stress had no effect on general acquisition of the task, results indicate that participants used negative feedback significantly less during learning after stress compared with the control condition. An enhancing effect of stress on use of positive feedback failed to reach significance. These findings suggest that stress acts differentially on the use of positive and negative feedback during learning.

  19. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    Rodionova, V.; Baraban, I.; Chichay, K.; Litvinova, A.; Perov, N.


    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of "classic" Fe77.5Si7.5B15 alloy with positive magnetostriction coefficient.

  20. Physiological stress and performance analysis to karate combat.

    Chaabene, Helmi; Hellara, Ilhem; Ghali, Faten B; Franchini, Emerson; Neffati, Fedoua; Tabben, Montassar; Najjar, Mohamed F; Hachana, Younés


    This study aimed to evaluate the relationship between physiological, and parameters of performance analysis during karate contest. Nine elite-level karate athletes participated in this study. Saliva sample was collected pre- and post-karate combat. Salivary cortisol (sC) post-combat 2 raised significantly compared to that recorded at pre-combat 1 (Δ%=105.3%; P=0.04; dz=0.78). The largest decrease of the salivary T/C ratio (sR) compared to pre-combat 1 was recorded post-combat 2 (Δ%=-43.5%; P=0.03). Moreover, blood lactate concentration post-combat 1 correlated positively to sCpost-combat 1 (r=0.66; P=0.05) and negatively to both salivary testosterone (sT) (r=-0.76; P=0.01) and sRpost-combat 1 (r=-0.76; P=0.01). There was no significant relationship between hormonal measures and parameters of match analysis. Although under simulated condition, karate combat poses large physiological stress to the karateka. Additionally, physiological strain to karate combat led to a catabolic hormonal response.

  1. Stress

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


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

  2. Molecular Analysis of Rice CIPKs Involved in Both Biotic and Abiotic Stress Responses

    CHEN Xi-feng; Gu Zhi-min; LIU Feng; MA Bo-jun; ZHANG Hong-sheng


    Plant calcineurin B-like (CBL) proteins have been proposed as important Ca2+ sensors and specifically interact with CBL-interacting protein kinases (CIPKs) in plant-specific calcium signaling.Here,we identified and isolated 15 CIPK genes in a japonica rice variety Nipponbare based on the predicted sequences of rice CIPK gene family.Gene structure analysis showed that these 15 genes were divided into intron-less and intron-rich groups,and OsCIPK3 and OsCIPK24 exhibited alternative splicing in their mature process.The phylogenetic analyses indicated that rice CIPKs shared an ancestor with Arabidopsis and poplar CIPKs.Analyses of gene expression showed that these OsCIPK genes were differentially induced by biotic stresses such as bacterial blight and abiotic stresses (heavy metal such as Hg2+,high salinity,cold and ABA).Interestingly,five OsCIPK genes,OsCIPK1,2,10,11 and 12,were transcriptionally up-regulated after bacterial blight infection whereas four OsCIPK genes,OsCIPK2,10,11 and 14,were induced by all treatments,indicating that some of OsCIPK genes are involved in multiple stress response pathways in plants.Our finding suggests that CIPKs play a key role in both biotic and abiotic stress responses.

  3. Raman Microscopic Analysis of Internal Stress in Boron-Doped Diamond

    Kevin E. Bennet


    Full Text Available Analysis of the induced stress on undoped and boron-doped diamond (BDD thin films by confocal Raman microscopy is performed in this study to investigate its correlation with sample chemical composition and the substrate used during fabrication. Knowledge of this nature is very important to the issue of long-term stability of BDD coated neurosurgical electrodes that will be used in fast-scan cyclic voltammetry, as potential occurrence of film delaminations and dislocations during their surgical implantation can have unwanted consequences for the reliability of BDD-based biosensing electrodes. To achieve a more uniform deposition of the films on cylindrically-shaped tungsten rods, substrate rotation was employed in a custom-built chemical vapor deposition reactor. In addition to visibly preferential boron incorporation into the diamond lattice and columnar growth, the results also reveal a direct correlation between regions of pure diamond and enhanced stress. Definite stress release throughout entire film thicknesses was found in the current Raman mapping images for higher amounts of boron addition. There is also a possible contribution to the high values of compressive stress from sp2 type carbon impurities, besides that of the expected lattice mismatch between film and substrate.

  4. Pipeline design and thermal stress analysis of a 10kW@20K helium refrigerator

    Xu, D.; Gong, L. H.; Xu, P.; Liu, H. M.; Li, L. F.; Xu, X. D.


    This paper is based on the devices and pipeline in the horizontal cryogenic cold-box of a 10kW@20K helium refrigerator developed by Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. Four devices, six valves, supporting components and pipe lines are positioned in the cold-box. At operating state, the temperature of these devices and pipeline is far below the room temperature, and the lowest temperature is 14K. Due to different material and temperature, the shrinkage of devices and pipes is different. Finite element analysis software SOLIDWORKS SIMULATION was used to numerically simulate the thermal stress and deformation. The results show that the thermal stress of pipe A is a little large. So we should change the pipe route or use a bellows expansion joint. Bellows expansion joints should also be used in the pipes connected to three of the six valves to protect them by decreasing the deformation. At last, the effect of diameter, thickness and bend radius on the thermal stress was analyzed. The results show that the thermal stress of the pipes increases with the increase of the diameter and the decrease of the bend radius.

  5. Medicago truncatula root nodule proteome analysis reveals differential plant and bacteroid responses to drought stress.

    Larrainzar, Estíbaliz; Wienkoop, Stefanie; Weckwerth, Wolfram; Ladrera, Rubén; Arrese-Igor, Cesar; González, Esther M


    Drought is one of the environmental factors most affecting crop production. Under drought, symbiotic nitrogen fixation is one of the physiological processes to first show stress responses in nodulated legumes. This inhibition process involves a number of factors whose interactions are not yet understood. This work aims to further understand changes occurring in nodules under drought stress from a proteomic perspective. Drought was imposed on Medicago truncatula 'Jemalong A17' plants grown in symbiosis with Sinorhizobium meliloti strain 2011. Changes at the protein level were analyzed using a nongel approach based on liquid chromatography coupled to tandem mass spectrometry. Due to the complexity of nodule tissue, the separation of plant and bacteroid fractions in M. truncatula root nodules was first checked with the aim of minimizing cross contamination between the fractions. Second, the protein plant fraction of M. truncatula nodules was profiled, leading to the identification of 377 plant proteins, the largest description of the plant nodule proteome so far. Third, both symbiotic partners were independently analyzed for quantitative differences at the protein level during drought stress. Multivariate data mining allowed for the classification of proteins sets that were involved in drought stress responses. The isolation of the nodule plant and bacteroid protein fractions enabled the independent analysis of the response of both counterparts, gaining further understanding of how each symbiotic member is distinctly affected at the protein level under a water-deficit situation.

  6. A round-robin analysis of temperature and residual stresses in dissimilar metal weld

    Song, Min Sup; Kang, Sun Ye; Park, June Soo; Sohn, Gap Heon [Korea Power Engineering Company, Inc., Daejeon (Korea, Republic of)


    DMWs are common feature of the PWR in the welded connections between carbon steel and stainless steel piping. The nickel-based weld metal, Alloy 82/182, is used for welding the dissimilar metals and is known to be susceptible to PWSCC. A round-robin program has been implemented to benchmark the numerical simulation of the transient temperature and weld residual stresses in the DMWs. To solve the round-robin problem related to pressurizer safety and relief nozzle, the thermal elasto-plastic analysis is performed in the DMW by using the FEM. The welding includes both the DMW of the nozzle to safe-end and the SMW of the safe-end and piping. Major results of the analyses are discussed: The axial and circumferential residual stresses are found to be -88MPa(225MPa) and -38MPa(293MPa) on the inner surface of the DMW; where the values in parenthesis are the residual stresses after the DMW. Thermo-mechanical interaction by the SMW has a significant effect on the residual stress fields in the DMW.

  7. Experiment-Based Computational Investigation of Thermomechanical Stresses in Flip Chip BGA Using the ATC4.2 Test Vehicle

    Burchett, Steven N.; Nguyen, Luu; Peterson, David W.; Sweet, James N.


    Stress measurement test chips were flip chip assembled to organic BGA substrates containing micro-vias and epoxy build-up interconnect layers. Mechanical degradation observed during temperature cycling was correlated to a damage theory developed based on 3D finite element method analysis. Degradation included die cracking, edge delamination and radial fillet cracking.

  8. Can Degradation of Adhesive Interfaces Due to Water Storage Affect Stress Distributions? A Finite-Element Stress Analysis Study.

    Belli, Sema; Eraslan, Oğuz; Eskitaşcıoğlu, Gürcan

    The aim of this finite-element stress analysis (FEA) was to determine the effect of degradation due to water storage on stress distributions in root-filled premolar models restored with composite using either a self-etch (SE) or an etch-and-rinse (E&R) adhesive. Four premolar FEA models including root filling, MOD cavity, and composite restorations were created. The cavities were assumed to be treated by SE or E&R adhesives and stored in water for 18 months. The elastic properties of the adhesive-dentin interface after 24-h and 18-month water storage were obtained from the literature and applied to the FEA models. A 300-N load was applied on the functional cusps of the models. The SolidWorks/Cosmosworks structural analysis program was used and the results were presented considering the von Mises stresses. Stresses in the cervical region increased over time on the load-application side of the main tooth models (SE: 84.11 MPa to 87.51 MPa; E&R: 100.24 MPa to 120.8 MPa). When the adhesive interfaces (hybrid layer, adhesive layer) and dentin were evaluated separately, the stresses near the root canal orifices increased over time in both models; however, this change was more noticeable in the E&R models. Stresses at the cavity corners decreased in the E&R model (within the adhesive layer), while SE models showed the opposite (within the hybrid layer). Change in the elastic modulus of the adhesive layer, hybrid layer, and dentin due to water storage has an effect on stresses in root-filled premolar models. The location and the level of the stresses differed depending on the adhesive used.

  9. A hybrid-stress element based on Hamilton principle

    Cen, Song; Zhang, Tao; Li, Chen-Feng; Fu, Xiang-Rong; Long, Yu-Qiu


    A novel hybrid-stress finite element method is proposed for constructing simple 4-node quadrilateral plane elements, and the new element is denoted as HH4-3 β here. Firstly, the theoretical basis of the traditional hybrid-stress elements, i.e., the Hellinger-Reissner variational principle, is replaced by the Hamilton variational principle, in which the number of the stress variables is reduced from 3 to 2. Secondly, three stress parameters and corresponding trial functions are introduced into the system equations. Thirdly, the displacement fields of the conventional bilinear isoparametric element are employed in the new models. Finally, from the stationary condition, the stress parameters can be expressed in terms of the displacement parameters, and thus the new element stiffness matrices can be obtained. Since the required number of stress variables in the Hamilton variational principle is less than that in the Hellinger-Reissner variational principle, and no additional incompatible displacement modes are considered, the new hybrid-stress element is simpler than the traditional ones. Furthermore, in order to improve the accuracy of the stress solutions, two enhanced post-processing schemes are also proposed for element HH4-3 β. Numerical examples show that the proposed model exhibits great improvements in both displacement and stress solutions, implying that the proposed technique is an effective way for developing simple finite element models with high performance.

  10. Time-space analysis in photoelasticity images using recurrent neural networks to detect zones with stress concentration

    Briñez de León, Juan C.; Restrepo M., Alejandro; Branch, John W.


    Digital photoelasticity is based on image analysis techniques to describe the stress distribution in birefringent materials subjected to mechanical loads. However, optical assemblies for capturing the images, the steps to extract the information, and the ambiguities of the results limit the analysis in zones with stress concentrations. These zones contain stress values that could produce a failure, making important their identification. This paper identifies zones with stress concentration in a sequence of photoelasticity images, which was captured from a circular disc under diametral compression. The capturing process was developed assembling a plane polariscope around the disc, and a digital camera stored the temporal fringe colors generated during the load application. Stress concentration zones were identified modeling the temporal intensities captured by every pixel contained into the sequence. In this case, an Elman artificial recurrent neural network was trained to model the temporal intensities. Pixel positions near to the stress concentration zones trained different network parameters in comparison with pixel positions belonging to zones of lower stress concentration.

  11. Genomic analysis of stress response against arsenic in Caenorhabditis elegans.

    Surasri N Sahu

    Full Text Available Arsenic, a known human carcinogen, is widely distributed around the world and found in particularly high concentrations in certain regions including Southwestern US, Eastern Europe, India, China, Taiwan and Mexico. Chronic arsenic poisoning affects millions of people worldwide and is associated with increased risk of many diseases including arthrosclerosis, diabetes and cancer. In this study, we explored genome level global responses to high and low levels of arsenic exposure in Caenorhabditis elegans using Affymetrix expression microarrays. This experimental design allows us to do microarray analysis of dose-response relationships of global gene expression patterns. High dose (0.03% exposure caused stronger global gene expression changes in comparison with low dose (0.003% exposure, suggesting a positive dose-response correlation. Biological processes such as oxidative stress, and iron metabolism, which were previously reported to be involved in arsenic toxicity studies using cultured cells, experimental animals, and humans, were found to be affected in C. elegans. We performed genome-wide gene expression comparisons between our microarray data and publicly available C. elegans microarray datasets of cadmium, and sediment exposure samples of German rivers Rhine and Elbe. Bioinformatics analysis of arsenic-responsive regulatory networks were done using FastMEDUSA program. FastMEDUSA analysis identified cancer-related genes, particularly genes associated with leukemia, such as dnj-11, which encodes a protein orthologous to the mammalian ZRF1/MIDA1/MPP11/DNAJC2 family of ribosome-associated molecular chaperones. We analyzed the protective functions of several of the identified genes using RNAi. Our study indicates that C. elegans could be a substitute model to study the mechanism of metal toxicity using high-throughput expression data and bioinformatics tools such as FastMEDUSA.

  12. [Objective assessment of risk factors of work-stress: first experience of application of the method OSFA(Objective Stress Factors Analysis)].

    Argentero, P; Candura, S M


    The OSFA (Objective Stress Factors Analysis) method is an approach to stress evaluation based on objective risk factors recording, according to the Italian law (legislative decree 81/08) as well as to national and international guidelines. The method evaluates the work conditions recognized as hazardous for the workers' psychophysical health. It comprises two main phases: phase A (company data analysis) and phase B (analysis of work-related stress conditions). Particularly, phase B is centred on the work conditions peculiar to the different organizational units, and it is conducted by means of structured interviews to experienced employees who know the specific company reality. The interviews, based on a 72 items questionnaire, take into consideration four main work aspects: organization, social environment, safety, and management. The final version of the instrument has been tested on 13 medium-small companies of Lumbardy (Italy), operating in various fields, with a number of employees ranging from 5 to 107 (median = 37). These first OSFA method experimentations allowed to verify its adequacy in relation to the exhaustiveness of the examined areas, the intelligibility of the items, and their capacity to discriminate the stress risk factors peculiar to the various productive activities. The preliminary results indicate that the described approach is easy to apply, and favourably accepted by employers and workers for its objectivity. Additionally, the OSFA method allows to plan preventive and ameliorative interventions, according to both the legislative decree 81/08 and the European agreement of October 8, 2004. Finally, the information obtained can represent the basis for a further stress risk evaluation through subjective evaluation methods.

  13. Thermal residual stress analysis of coated diamond grits

    Zi-qian Huang; Bo Xiang; Yue-hui He; Bai-yun Huang


    Residual stresses of coated diamond grits were analyzed by a finite element unit cell model.Diamond grits coated with four types of metals, W, Mo, Ti, and Cr, were considered.The numerical results show that compressive stress occurs in the diamond particles and tensile stress occurs in the metal matrix; compressive stress is concentrated in the diamond sharp comer; interface stresses decrease by more than 1000 MPa with a metal interlayer; plastic deformation of the matrix begins near the sharp comer of diamond grits and extends toward the peripheral zone.Stress concentration dramatically decreases due to plastic deformation of the matrix.The deposition of transition metals on a diamond surface can dramatically promote the adhesion between diamond grits and the metal bond.

  14. Police Work Absence: An Analysis of Stress and Resiliency.

    Violanti, John M; Fekedulegn, Desta; Hartley, Tara A; Andrew, Michael E; Charles, Luenda; Tinney-Zara, Cathy A; Burchfiel, Cecil M


    Police work is a high stress occupation and stress has been implicated in work absence. The present study examined (1) associations between specific types of police stress and work absences, (2) distinctions between "voluntary" (1-day) and "involuntary" (> 3-days) absences; and (3) the modifying effect of resiliency. Officers (n=337) from the Buffalo Cardio-Metabolic Occupational Police Stress study were included in the present study. The sample was 72% male, 77% Caucasian, 73% married, and 75% patrol officers. Mean age was 41 years (SD=6.4). Measures included: the Spielberger Police Stress Survey, 1-year payroll absence data, and the Dispositional Resilience Scale. The negative binomial regression was used to estimate rate ratios (RR) of 1-day and >3-days work absences for increasing stress scores. Models were adjusted for age, race/ethnicity, rank, smoking status, alcohol intake, and sleep duration. For one-unit increase in stress scores, the covariate adjusted RRs for one-day work absences were: total stress score (RR=1.19, 95% CI: 1.04-1.36); administrative stress (RR=1.52, 95% CI: 1.05-2.18); physical/psychological stress (RR=1.54, 95% CI: 1.14-2.07); and lack of support (RR=1.75, 95% CI: 1.01-3.05). Results suggest that officers were more likely to take voluntary 1-day absences due to specific types of stress at work. When the entire sample was considered, there was no significant association between police specific stress and episodes of work absence lasting at least three consecutive days. Hardy individuals, including those with high scores on the challenge sub-score, may use 1-day absences as a positive coping strategy.

  15. Deduction and Analysis of the Interacting Stress Response Pathways of Metal/Radionuclide-reducing Bacteria

    Zhou, Jizhong [University of Oklahoma; He, Zhili [University of Oklahoma


    Project Title: Deduction and Analysis of the Interacting Stress Response Pathways of Metal/Radionuclide-reducing Bacteria DOE Grant Number: DE-FG02-06ER64205 Principal Investigator: Jizhong (Joe) Zhou (University of Oklahoma) Key members: Zhili He, Aifen Zhou, Christopher Hemme, Joy Van Nostrand, Ye Deng, and Qichao Tu Collaborators: Terry Hazen, Judy Wall, Adam Arkin, Matthew Fields, Aindrila Mukhopadhyay, and David Stahl Summary Three major objectives have been conducted in the Zhou group at the University of Oklahoma (OU): (i) understanding of gene function, regulation, network and evolution of Desulfovibrio vugaris Hildenborough in response to environmental stresses, (ii) development of metagenomics technologies for microbial community analysis, and (iii) functional characterization of microbial communities with metagenomic approaches. In the past a few years, we characterized four CRP/FNR regulators, sequenced ancestor and evolved D. vulgaris strains, and functionally analyzed those mutated genes identified in salt-adapted strains. Also, a new version of GeoChip 4.0 has been developed, which also includes stress response genes (StressChip), and a random matrix theory-based conceptual framework for identifying functional molecular ecological networks has been developed with the high throughput functional gene array hybridization data as well as pyrosequencing data from 16S rRNA genes. In addition, GeoChip and sequencing technologies as well as network analysis approaches have been used to analyze microbial communities from different habitats. Those studies provide a comprehensive understanding of gene function, regulation, network, and evolution in D. vulgaris, and microbial community diversity, composition and structure as well as their linkages with environmental factors and ecosystem functioning, which has resulted in more than 60 publications.

  16. Laser cutting of thick sheet metals: Residual stress analysis

    Arif, A. F. M.; Yilbas, B. S.; Aleem, B. J. Abdul


    Laser cutting of tailored blanks from a thick mild steel sheet is considered. Temperature and stress field in the cutting sections are modeled using the finite element method. The residual stress developed in the cutting section is determined using the X-ray diffraction (XRD) technique and is compared with the predictions. The structural and morphological changes in the cut section are examined using the optical microscopy and scanning electron microscopy (SEM). It is found that temperature and von Mises stress increase sharply in the cutting section, particularly in the direction normal to the cutting direction. The residual stress remains high in the region close to the cutting section.

  17. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.


    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  18. Finite element analysis of stress and wear characterization in total ankle replacements.

    Jay Elliot, Bradley; Gundapaneni, Dinesh; Goswami, Tarun


    Total Ankle Arthroplasty is performed in order to reduce the pain and loss of ambulation in patients with various forms of arthritis and trauma. Although replacement devices fail by a number of mechanisms, wear in the polyethylene liner constitutes one of the dominating failure modes. This leads to instability and loosening of the implant. Mechanisms that contribute to wear in the liners are high contact and subsurface stresses that break down the material over time. Therefore, it is important to understand the gait that generates these stresses. Methods to characterize and decrease wear in Ohio Total Ankle Replacements (TARs) have been performed in this research. This research utilizes finite element analysis of Wright State University (WSU) patented TAR models. From the Finite element analysis (FEA) results, mathematical models of contact conditions and wear mechanics were developed. The maximum wear rate values obtained in the study (at 25.598MPa, 3.74mm(3)/year) and maximum surface Mises stress obtained with new optimization model (11.52MPa) seem to be comparable with the maximum wear values obtained in other similar studies. These models were used to determine the best methods for wear characterization and reduction. Furthermore, optimization models were developed based on geometry of the implants. These equations optimize geometry, thus congruency and anatomical simulations for total ankle implants.

  19. Three dimensional finite element analysis of acetabulum loaded by static stress and its biomechanical significance

    SU Jia-can; ZHANG Ben; YU Bao-qing; ZHANG Chun-cai; CHEN Xue-qiang; WANG Bao-hua; DING Zu-quan


    Objective:To explore the mechanical behavior of acetabulum loaded by static stress and provide the mechanical basis for clinical analysis and judgement on acetabular mechanical distribution and effect of static stress. Methods:By means of computer simulation, acetabular three dimensional model was input into three dimensional finite element analysis software ANSYS7.0. The acetabular mechanical behavior was calculated and the main stress value, stress distribution and acetabular unit displacement in the direction of main stress were analyzed when anterior wall of acetabulum and acetabular crest were loaded by 1 000 N static stress. Results :When acetabular anterior wall loaded by X direction and Z direction composition force, the stress passed along 4 directions: (1)from acetabular anterior wall to pubic symphysis a long superior branch of pubis firstly, (2)from acetabular anterior wall to cacroiliac joint along pelvic ring,(3)in the acetabulum, (4)from the suffered point to ischium. When acetabular crest loaded by X direction and Y direction composition force, the stress transmitted to 4 directions: (1)from acetabular crest to ilium firstly, (2)from suffered point to cacroiliac joint along pelvic ring, (3) in the acetabulum , (4)along the pubic branch ,but no stress transmitted to the ischium branch. Conclusion:Analyzing the stress distribution of acetabulum and units displacement when static stress loaded can provide internal fixation point for acetabular fracture treatment and help understand the stress distribution of acetabulum.

  20. Characterization of genes and pathways that respond to heat stress in Holstein calves through transcriptome analysis.

    Srikanth, Krishnamoorthy; Kwon, Anam; Lee, Eunjin; Chung, Hoyoung


    This study aimed to investigate the genes and pathways that respond to heat stress in Holstein bull calves exposed to severe ranges of temperature and humidity. A total of ten animals from 4 to 6 months of age were subjected to heat stress at 37 °C and 90 % humidity for 12 h. Skin and rectal temperatures were measured before and after heat stress; while no correlation was found between them before heat stress, a moderate correlation was detected after heat stress, confirming rectal temperature to be a better barometer for monitoring heat stress. RNAseq analysis identified 8567 genes to be differentially regulated, out of which 465 genes were significantly upregulated (≥2-fold, P heat stress. Significant terms and pathways enriched in response to heat stress included chaperones, cochaperones, cellular response to heat stress, phosphorylation, kinase activation, immune response, apoptosis, Toll-like receptor signaling pathway, Pi3K/AKT activation, protein processing in endoplasmic reticulum, interferon signaling, pathways in cancer, estrogen signaling pathway, and MAPK signaling pathway. The differentially expressed genes were validated by quantitative real-time PCR analysis, which confirmed the tendency of the expression. The genes and pathways identified in this analysis extend our understanding of transcriptional response to heat stress and their likely functioning in adapting the animal to hyperthermic stress. The identified genes could be used as candidate genes for association studies to select and breed animals with improved heat tolerance.

  1. A new strategy for stress analysis using the finite element method

    Kamat, M. P.; Vandenbrink, D.


    In the paper the authors examine the effectiveness of the Powell-Toint strategy for evaluating the Hessian of the potential energy surface of a finite element model that can be used for linear stress analysis and transient response predictions of structures. Cases for which the Powell-Toint strategy may be cost-effective with the conventional method of stress analysis are identified.

  2. High Temperature Stress Analysis on 61-pin Test Assembly for Reactor Core Sub-channel Flow Test

    Lee, Dongwon; Kim, Hyungmo; Lee, Hyeongyeon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    In this study, a high temperature heat transfer and stress analysis of a 61-pin test fuel assembly scaled down from the full scale 217-pin sub-assembly was conducted. The reactor core subchannel flow characteristic test will be conducted to evaluate uncertainties in computer codes used for reactor core thermal hydraulic design. Stress analysis for a 61-pin fuel assembly scaled down from Prototype Generation IV Sodium-cooled Fast Reactor was conducted and structural integrity in terms of load controlled stress limits was conducted. In this study, The evaluations on load-controlled stress limits for a 61-pin test fuel assembly to be used for reactor core subchannel flow distribution tests were conducted assuming that the test assembly is installed in a Prototype Generation IV Sodium-cooled fast reactor core. The 61-pin test assembly has the geometric similarity on P/D and H/D with PGSFR and material of fuel assembly is austenitic stainless steel 316L. The stress analysis results showed that 4.05MPa under primary load occurred at mid part of the test assembly and it was shown that the value of 4.05Mpa was far smaller than the code allowable of 127MPa. , it was shown that the stress intensity due to due to primary load is very small. The stress analysis results under primary and secondary loads showed that maximum stress intensity of 84.08MPa occurred at upper flange tangent to outer casing and the value was well within the code allowable of 268.8MPa. Integrity evaluations based on strain limits and creep-fatigue damage are underway according to the elevated design codes.

  3. Mindfulness-based stress reduction for people with chronic diseases.

    Merkes, Monika


    Mindfulness-based stress reduction (MBSR) is a structured group program that uses mindfulness meditation to improve well-being and alleviate suffering. This article reviews the impact of MBSR for people with chronic diseases. The review includes original research that was published in English and peer-reviewed and reported outcomes for adults with chronic diseases who had participated in an MBSR program. Fifteen studies were identified. Outcomes related to mental and physical health, well-being, and quality of life. The studies included different research designs, and used self-report and physiological outcome measures. Participants' clinical diagnoses included fibromyalgia, chronic pain, rheumatoid arthritis, type 2 diabetes, chronic fatigue syndrome, multiple chemical sensitivity, and cardiovascular diagnoses. All 15 studies found that participation in an MBSR program resulted in improvements. No negative change was reported between baseline and follow up. Outcomes in regard to specific variables were difficult to compare and equivocal. Overall, positive change predominated. Chronic diseases are associated with a range of unwelcome psychological and physical consequences. Participation in an MBSR program is likely to result in coping better with symptoms, improved overall well-being and quality of life, and enhanced health outcomes. As an adjunct to standard care, MBSR has potential for much wider application in Australian primary care settings.

  4. Numerical and Experimental Stress Analysis of a Composite Leaf Spring

    Kaveri A. Katake


    Full Text Available Automobile sector is always focusing on enhancing level of comfort, fuel economy, customer satisfaction and safety. Vehicle weight reduction increases the overall fuel efficiency. Use of composite materials has made it possible to reduce the weight of the vehicle, without reduction in load carrying capacity. Now a day's manufacturers and researchers are trying to replace conventional material parts with composites. The composite materials have more elastic strain energy storage capacity and high strength to weight ratio as compared to steel. This paper is related to Numerical and experimental strength analysis of suspension leaf springs for a light motor vehicle made of composite materials. Two materials Glass Fiber Reinforced Plastic (GFRP and Carbon Fiber Reinforced Plastic (CFRP are selected for manufacturing of leaf spring. The strength of these composite depends on angle orientation, volume to weight ratio of reinforcement and length to depth ratio of fiber. In this work two leaf springs made of GFRP and a sandwich of CFRP and GFRP are developed. Numerical and experimental static stress analyses are carried out for these two springs. These results are compared with analytical results of conventional metal spring. The comparison shows that composite material springs have compatible strength to withstand load. Comparative results for weight, cost and deformation are presented at the end of the paper.

  5. Determining the von Mises stress power spectral density for frequency domain fatigue analysis including out-of-phase stress components

    Bonte, M.H.A.; Boer, de A.; Liebregts, R.


    This paper provides a new formula to take into account phase differences in the determination of an equivalent von Mises stress power spectral density (PSD) from multiple random inputs. The obtained von Mises PSD can subsequently be used for fatigue analysis. The formula was derived for use in the c

  6. Stress analysis of 3D complex geometries using the scaled boundary polyhedral finite elements

    Talebi, Hossein; Saputra, Albert; Song, Chongmin


    While dominating the numerical stress analysis of solids, the finite element method requires a mesh to conform to the surface of the geometry. Thus the mesh generation of three dimensional complex structures often require tedious human interventions. In this paper, we present a formulation for arbitrary polyhedral elements based on the scaled boundary finite element method, which reduces the difficulties in automatic mesh generation. We also propose a simple method to generate polyhedral meshes with local refinements. The mesh generation method is based on combining an octree mesh with surfaces defined using signed distance functions. Through several numerical examples, we verify the results, study the convergence behaviour and depict the many advantages and capabilities of the presented method. This contribution is intended to assist us to eventually frame a set of numerical methods and associated tools for the full automation of the engineering analysis where minimal human interaction is needed.

  7. Technical note: stress analysis of cellulosic-manure composites

    Y.H. Ro; J.F. Hunt; R.E. Rowlands


    Ability to determine stresses in loaded, perforated cellulosic-manure composites from recorded temperature information was demonstrated. Being able to stress analyze such green materials addresses several societal issues. These include providing engineering members fabricated from materials that are suitable for developed and developing nations, relieving a troubling...

  8. An Analysis of Role Stress among Hospital Nurses.

    Vredenburgh, Donald J.; Trinkaus, Robert J.


    Using a sample of 566 nurses, this study focused on role stress, conceptualized in terms of role conflict, uncertainty about acceptance of one's behavior by supervisors and peers, and role ambiguity. Results indicated that individual attributes, including education, locus of control, and professional commitment, predicted role stress. (Author/RC)

  9. An interaction stress analysis of nanoscale elastic asperity contacts.

    Rahmat, Meysam; Ghiasi, Hossein; Hubert, Pascal


    A new contact mechanics model is presented and experimentally examined at the nanoscale. The current work addresses the well-established field of contact mechanics, but at the nanoscale where interaction stresses seem to be effective. The new model combines the classic Hertz theory with the new interaction stress concept to provide the stress field in contact bodies with adhesion. Hence, it benefits from the simplicity of non-adhesive models, while offering the same applicability as more complicated models. In order to examine the model, a set of atomic force microscopy experiments were performed on substrates made from single-walled carbon nanotube buckypaper. The stress field in the substrate was obtained by superposition of the Hertzian stress field and the interaction stress field, and then compared to other contact models. Finally, the effect of indentation depth on the stress field was studied for the interaction model as well as for the Hertz, Derjaguin-Muller-Toporov, and Johnson-Kendall-Roberts models. Thus, the amount of error introduced by using the Hertz theory to model contacts with adhesion was found for different indentation depths. It was observed that in the absence of interaction stress data, the Hertz theory predictions led to smaller errors compared to other contact-with-adhesion models.

  10. 12 CFR Appendix A to Subpart B of... - Risk-Based Capital Stress Test


    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Risk-Based Capital Stress Test A Appendix A to... Appendix A to Subpart B of Part 652— Risk-Based Capital Stress Test 1.0Introduction. 2.0Credit Risk. 2... in the Stress Test. 3.0Interest Rate Risk. 3.1Process for Calculating the Interest Rate Movement....

  11. Differential Effects of Stress-induced Cortisol Responses on Recollection and Familiarity-based Recognition Memory

    McCullough, Andrew M.; Ritchey, Maureen; Ranganath, Charan; Yonelinas, Andrew


    Stress-induced changes in cortisol can impact memory in various ways. However, the precise relationship between cortisol and recognition memory is still poorly understood. For instance, there is reason to believe that stress could differentially affect recollection-based memory, which depends on the hippocampus, and familiarity-based recognition, which can be supported by neocortical areas alone. Accordingly, in the current study we examined the effects of stress-related changes in cortisol o...

  12. An Embedded Stress Sensor for Concrete SHM Based on Amorphous Ferromagnetic Microwires

    Jesús Olivera; Margarita González; José Vicente Fuente; Rastislav Varga; Arkady Zhukov; José Javier Anaya


    A new smart concrete aggregate design as a candidate for applications in structural health monitoring (SHM) of critical elements in civil infrastructure is proposed. The cement-based stress/strain sensor was developed by utilizing the stress/strain sensing properties of a magnetic microwire embedded in cement-based composite (MMCC). This is a contact-less type sensor that measures variations of magnetic properties resulting from stress variations. Sensors made of these materials can be design...

  13. Functional Genomic Analysis of Variation on Beef Tenderness Induced by Acute Stress in Angus Cattle

    Chunping Zhao


    Full Text Available Beef is one of the leading sources of protein, B vitamins, iron, and zinc in human food. Beef palatability is based on three general criteria: tenderness, juiciness, and flavor, of which tenderness is thought to be the most important factor. In this study, we found that beef tenderness, measured by the Warner-Bratzler shear force (WBSF, was dramatically increased by acute stress. Microarray analysis and qPCR identified a variety of genes that were differentially expressed. Pathway analysis showed that these genes were involved in immune response and regulation of metabolism process as activators or repressors. Further analysis identified that these changes may be related with CpG methylation of several genes. Therefore, the results from this study provide an enhanced understanding of the mechanisms that genetic and epigenetic regulations control meat quality and beef tenderness.

  14. Hand-Based Biometric Analysis

    Bebis, George (Inventor); Amayeh, Gholamreza (Inventor)


    Hand-based biometric analysis systems and techniques are described which provide robust hand-based identification and verification. An image of a hand is obtained, which is then segmented into a palm region and separate finger regions. Acquisition of the image is performed without requiring particular orientation or placement restrictions. Segmentation is performed without the use of reference points on the images. Each segment is analyzed by calculating a set of Zernike moment descriptors for the segment. The feature parameters thus obtained are then fused and compared to stored sets of descriptors in enrollment templates to arrive at an identity decision. By using Zernike moments, and through additional manipulation, the biometric analysis is invariant to rotation, scale, or translation or an in put image. Additionally, the analysis utilizes re-use of commonly-seen terms in Zernike calculations to achieve additional efficiencies over traditional Zernike moment calculation.

  15. Finite element formulation and analysis for an arterial wall with residual and active stresses.

    Kida, Naoki; Adachi, Taiji


    In this study, for predicting arterial function and pathogenesis from a mechanical viewpoint, we develop a continuum mechanical model of an arterial wall that embodies residual and active stresses following a traditional anisotropic passive constitutive law. The residual and active stresses are incorporated into finite element methods based on a two-field variational principle described in the Lagrangian form. The linearisation of nonlinear weak-form equations derived from this variational principle is then described for developing an original finite element algorithm. Numerical simulations reveal the following: (i) residual stresses lead to a reduction in stress gradient regardless of the magnitude of external load; (ii) active stresses help homogenise stress distribution under physiological external load, but this homogeneity collapses under pathological external load; (iii) when residual and active stresses act together, the effect of the residual stresses is relatively obscured by that of the active stresses. We conclude that residual stresses have minor but persistent mechanical effects on the arterial wall under both physiological and pathological external loads; active stresses play an important role in the physiological functions and pathogenesis of arteries, and the mechanical effect of residual stresses is dependent on the presence/absence of active stresses.

  16. Electronic stress tensor analysis of molecules in gas phase of CVD process for GeSbTe alloy

    Nozaki, Hiroo; Ichikawa, Kazuhide; Tachibana, Akitomo


    We analyze the electronic structure of molecules which may exist in gas phase of chemical vapor deposition process for GeSbTe alloy using the electronic stress tensor, with special focus on the chemical bonds between Ge, Sb and Te atoms. We find that, from the viewpoint of the electronic stress tensor, they have intermediate properties between alkali metals and hydrocarbon molecules. We also study the correlation between the bond order which is defined based on the electronic stress tensor, and energy-related quantities. We find that the correlation with the bond dissociation energy is not so strong while one with the force constant is very strong. We interpret these results in terms of the energy density on the "Lagrange surface", which is considered to define the boundary surface of atoms in a molecule in the framework of the electronic stress tensor analysis.

  17. Electronic stress tensor analysis of molecules in gas phase of CVD process for GeSbTe alloy.

    Nozaki, Hiroo; Ikeda, Yuji; Ichikawa, Kazuhide; Tachibana, Akitomo


    We analyze the electronic structure of molecules which may exist in gas phase of chemical vapor deposition process for GeSbTe alloy using the electronic stress tensor, with special focus on the chemical bonds between Ge, Sb, and Te atoms. We find that, from the viewpoint of the electronic stress tensor, they have intermediate properties between alkali metals and hydrocarbon molecules. We also study the correlation between the bond order which is defined based on the electronic stress tensor, and energy-related quantities. We find that the correlation with the bond dissociation energy is not so strong while one with the force constant is very strong. We interpret these results in terms of the energy density on the "Lagrange surface," which is considered to define the boundary surface of atoms in a molecule in the framework of the electronic stress tensor analysis.



    The hydrogen distribution of 16MnR steel weldment in hydrogen contained environment was calculated using the finite element method (FEM). The effect of welding residual stress on hydrogen diffusion has been discussed using a 3-D sequential coupling finite element analysis procedure complied by Abaqus code. The hydrogen diffusion coefficient in weld metal, the heat affected zone (HAZ), and the base metal of the 16MnR steel weldment were measured using the electrochemical permeation technique. The hydrogen diffusion without the effect of stress was also calculated and compared. Owing to the existence of welding residual stress, the hydrogen concentration was obviously increased and the hydrogen would diffuse and accumulate in the higher stress region.

  19. Management of stress and stress-related diseases: Emerging computer-based technologies and the rationale for clinical laboratory assessment

    Ezekiel Uba Nwose


    Full Text Available Background : Over the years, the issue of stress management in mental health has been discussed without reference to the clinical laboratory perspectives. Translational research and the vast array of emerging diagnostic technologies in alternative medical practice are now bridging the gap. While it would be scientific arrogance for the clinical practitioner and scientist to ignore the trend, the new technologies seeking clinical acceptability necessarily require expatiation of the scientific aspects of their products. Aims : This commentary builds on a comparative critical review to further our hypothesis that oxidative stress is the biochemical basis of the emerging computer-based diagnostic technologies. Materials & Method : The available information on Computer Meridian Diagnostics, Neuropattern and Virtual Scanning technologies were critically reviewed. The differences and similarities were articulated. Results : The technologies seem different, but have similarities that have not been articulated before. The seemingly different theories are traceable to Russian scientists and are based upon stress-induced adrenal secretions and the associated effect on glucose metabolism. The therapeutic effects of antioxidant nutrition, exercise or relaxation that are inherent in the technologies are highlighted. Conclusion : This commentary furthers explanation of the alterations in antioxidant activities as a result of biofeedback, oxidative stress and/or physiological effects as the biochemical basis of the technologies. The place for antioxidant indices and whole blood viscosity are also highlighted. This provides a rationale for the evaluation of available clinical diagnostic tests both to validate the technologies and as clinical laboratory correlates in stress management.

  20. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Michael J. Mills


    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  1. Wheat stress indicator model, Crop Condition Assessment Division (CCAD) data base interface driver, user's manual

    Hansen, R. F. (Principal Investigator)


    The use of the wheat stress indicator model CCAD data base interface driver is described. The purpose of this system is to interface the wheat stress indicator model with the CCAD operational data base. The interface driver routine decides what meteorological stations should be processed and calls the proper subroutines to process the stations.

  2. Residual stresses within sprayed coatings

    JIANG Yi; XU Bin-shi; WANG Hai-dou


    Some important developments of residual stress researches for coating-based systems were studied. The following topics were included the sources of residual stresses in coatings: error analysis of Stoney's equation in the curvature method used for the measurement of coating residual stress, the modeling of residual stress and some analytical models for predicting the residual stresses in coatings. These topics should provide some important insights for the fail-safe design of the coating-based systems.

  3. Incidence investigation and analysis of hepatic stress injury after trauma

    WANG Quanchu; ZHANG Yafei; CHENG Zhengxiang


    Objective To investigate the etiology and pathogenesis of hepatic stress injury after trauma.Methods 4677 patients with severe trauma in 153th Hospital of PLA from Jan.2004 to Jul.2005 were enrolled in this study to investigate the incidence of hepatic stress injury,and furthermore,in combination with medical information,the possible pathogenesis was analyzed.Results The main manifestation of hepatic stress injury was the elevated ALT or AST levels (387 cases,8.3% ).The incidence of hepatic stress injury after hand injury,burn injury,head injury,bone injury,abdominal injury,and thoracic injury were 16.6%,6.9%,5.6%,5.0%,3.8% and 2.0%,respectively,and among which,the incidence of hepatic stress injury after hand injury was statistically highest (P <0.01 ).Conclusion The total incidence of hepatic stress injury after trauma was 8.3%.Intestinal endotoxemia might be one of the beginning components of hepatic stress injury after trauma.

  4. Stress in Portuguese Middle School Transition: A Multilevel Analysis.

    Coelho, Vítor Alexandre; Romão, Ana Maria


    Transition from elementary to middle school is commonly seen as a period of stress, impacting students' school adjustment. The present longitudinal study aimed to analyze the difference in stress levels between the end of 4th grade and 5th grade, while also analyzing gender differences and 5th grade retention. Two hundred fifty-eight 4th grade students (M age = 9.55; SD = 0.77) from six Portuguese public schools, from the municipality of Torres Vedras, participated in this study. Self-report questionnaires were administered at the end of the 4th and 5th grades, and 5th grade school records were also collected. Results showed that 5th graders present higher levels of Academic Stress (d = .29) and Teacher/Rules Stress (d = .28). Girls had a greater increase of Peer-related Stress with the transition (p Stress (p middle school are needed, in order to reduce the increase of stress levels at 5th grade and to promote a better school adjustment in the first year of middle school.

  5. Study on cracking of welding overlay based on the theory of diffusion-induced stress

    Xiliang ZHANG; Changyu ZHOU


    Hydrogen diffusion in the wall of hydrogenation reactor for three situations,i.e. operating,normal shutdown and abnormal shutdown,was numerically simulated based on the finite element program-ABAQUS. The formula of diffusion-induced stress was deduced for model of the thin walled cylinder. Distribution of diffusion-induced stress in the wall of hydrogenation reactor was studied. The results showed that the maximum stress was at the fusion surface between welding overlay and base metal,and which would increase with cooling rate. The crack will initiate and propagate from fusion surface to welding overlay when the diffusion-induced stress is higher than yield stress,but it will not propagate to the base metal. Diffusion-induced stress is one of the important factors for crack initiation and propagation of welding overlay of hydrogenation reactor.

  6. Global analysis of transcriptome responses and gene expression profiles to cold stress of Jatropha curcas L.

    Haibo Wang

    Full Text Available BACKGROUND: Jatropha curcas L., also called the Physic nut, is an oil-rich shrub with multiple uses, including biodiesel production, and is currently exploited as a renewable energy resource in many countries. Nevertheless, because of its origin from the tropical MidAmerican zone, J. curcas confers an inherent but undesirable characteristic (low cold resistance that may seriously restrict its large-scale popularization. This adaptive flaw can be genetically improved by elucidating the mechanisms underlying plant tolerance to cold temperatures. The newly developed Illumina Hiseq™ 2000 RNA-seq and Digital Gene Expression (DGE are deep high-throughput approaches for gene expression analysis at the transcriptome level, using which we carefully investigated the gene expression profiles in response to cold stress to gain insight into the molecular mechanisms of cold response in J. curcas. RESULTS: In total, 45,251 unigenes were obtained by assembly of clean data generated by RNA-seq analysis of the J. curcas transcriptome. A total of 33,363 and 912 complete or partial coding sequences (CDSs were determined by protein database alignments and ESTScan prediction, respectively. Among these unigenes, more than 41.52% were involved in approximately 128 known metabolic or signaling pathways, and 4,185 were possibly associated with cold resistance. DGE analysis was used to assess the changes in gene expression when exposed to cold condition (12°C for 12, 24, and 48 h. The results showed that 3,178 genes were significantly upregulated and 1,244 were downregulated under cold stress. These genes were then functionally annotated based on the transcriptome data from RNA-seq analysis. CONCLUSIONS: This study provides a global view of transcriptome response and gene expression profiling of J. curcas in response to cold stress. The results can help improve our current understanding of the mechanisms underlying plant cold resistance and favor the screening of

  7. Elasto-Plastic FEM Analysis of Residual Stress in Spun Tube

    Fuan HUA; Yuansheng YANG; Dayong GUO; Wenhui TONG; Zhuangqi HU


    The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, the influences of spinning parameters on the distribution of the residual stress were investigated in detail, and the formation mechanism of residual stress during tube spinning was discussed. Based on the calculation of the residual stress, the reasons for annealing cracks on the spun tube during interpass heat treatment were explored. The simulation results and the characteristics of annealing cracks show that the circumferential residual tensile stress is a main factor to cause the annealing cracks.

  8. Identification of potential internal control genes for real-time PCR analysis during stress response in Pyropia haitanensis

    Wang, Xia; Feng, Jianhua; Huang, Aiyou; He, Linwen; Niu, Jianfeng; Wang, Guangce


    Pyropia haitanensis has prominent stress-resistance characteristics and is endemic to China. Studies into the stress responses in these algae could provide valuable information on the stress-response mechanisms in the intertidal Rhodophyta. Here, the effects of salinity and light intensity on the quantum yield of photosystem II in Py. haitanensis were investigated using pulse-amplitude-modulation fluorometry. Total RNA and genomic DNA of the samples under different stress conditions were isolated. By normalizing to the genomic DNA quantity, the RNA content in each sample was evaluated. The cDNA was synthesized and the expression levels of seven potential internal control genes were evaluated using qRT-PCR method. Then, we used geNorm, a common statistical algorithm, to analyze the qRT-PCR data of seven reference genes. Potential genes that may constantly be expressed under different conditions were selected, and these genes showed stable expression levels in samples under a salinity treatment, while tubulin, glyceraldehyde-3-phosphate dehydrogenase and actin showed stability in samples stressed by strong light. Based on the results of the pulse amplitude-modulation fluorometry, an absolute quantification was performed to obtain gene copy numbers in certain stress-treated samples. The stably expressed genes as determined by the absolute quantification in certain samples conformed to the results of the geNorm screening. Based on the results of the software analysis and absolute quantification, we proposed that elongation factor 3 and 18S ribosomal RNA could be used as internal control genes when the Py. haitanensis blades were subjected to salinity stress, and that α-tubulin and 18S ribosomal RNA could be used as the internal control genes when the stress was from strong light. In general, our findings provide a convenient reference for the selection of internal control genes when designing experiments related to stress responses in Py. haitanensis.

  9. Analytical method for thermal stress analysis of plasma facing materials

    You, J. H.; Bolt, H.


    The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed.

  10. Posttraumatic stress disorder in bosnian war veterans: Analysis of stress events and risk factors

    Kuljić Blagoje


    Full Text Available The aim of this study was to determine the incidence of Post-Traumatic Stress Disorder (PTSD, the characteristics of stress-related events, and the risk factors for the development of PTSD. The total patient sample consisted of 100 Bosnian war veterans. Watson’s PTSD module was used in establishing PTSD diagnosis. Patients fulfilled the following questionnaires: personal data form, Posttraumatic Symptom Scale PTSS-10 (Holen, Impact of Event Scale (Horowitz, Life Event Scale, and Eysenck Personality Inventory. PTSD was diagnosed in 30% of the examined patients. Larger number of stress-related events, particularly of those regarded as life-threatening, wounding/death of a close person, and material losses were more frequent in persons with PTSD. The risk factors for the development of PTSD in this study were: age (30-40, marital status (married, lower level of education, the front-line combat exposure, neurotic manifestations, family problems in childhood, and neuroticism.

  11. Stress reactivity and personality in extreme sport athletes: The psychobiology of BASE jumpers.

    Monasterio, Erik; Mei-Dan, Omer; Hackney, Anthony C; Lane, Amy R; Zwir, Igor; Rozsa, Sandor; Cloninger, C Robert


    This is the first report of the psychobiology of stress in BASE jumpers, one of the most dangerous forms of extreme sport. We tested the hypotheses that indicators of emotional style (temperament) predict salivary cortisol reactivity, whereas indicators of intentional goal-setting (persistence and character) predict salivary alpha-amylase reactivity during BASE jumping. Ninety-eight subjects completed the Temperament and Character Inventory (TCI) the day before the jump, and 77 also gave salivary samples at baseline, pre-jump on the bridge over the New River Gorge, and post-jump upon landing. Overall BASE jumpers are highly resilient individuals who are highly self-directed, persistent, and risk-taking, but they are heterogeneous in their motives and stress reactivity in the Hypothalamic-Pituitary-Adrenal (HPA) stress system (cortisol reactivity) and the sympathetic arousal system (alpha-amylase reactivity). Three classes of jumpers were identified using latent class analysis based on their personality profiles, prior jumping experience, and levels of cortisol and alpha-amylase at all three time points. "Masterful" jumpers (class 1) had a strong sense of self-directedness and mastery, extensive prior experience, and had little alpha-amylase reactivity and average cortisol reactivity. "Trustful" jumpers (class 2) were highly cooperative and trustful individuals who had little cortisol reactivity coincident with the social support they experienced prior to jumping. "Courageous" jumpers (class 3) were determined despite anxiety and inexperience, and they had high sympathetic reactivity but average cortisol activation. We conclude that trusting social attachment (Reward Dependence) and not jumping experience predicted low cortisol reactivity, whereas persistence (determination) and not jumping experience predicted high alpha-amylase reactivity. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Quantitative histo-morphometric analysis of heat-stress-related damage in the small intestines of broiler chickens.

    Santos, Regiane R; Awati, Ajay; Roubos-van den Hil, Petra J; Tersteeg-Zijderveld, Monique H G; Koolmees, Peter A; Fink-Gremmels, Johanna


    The aim of the current research was to present a methodological approach allowing reproducible morphometric and morphological (Chiu/Park scale) analyses of the alterations in the intestines of broilers exposed to heat stress. Ross broilers were exposed over four consecutive days to a high-temperature regime in controlled climate rooms, with a day temperature of 39°C (±1°C) and a night temperature of 25°C (±1°C), respectively. A control group was kept at an ambient temperature of 25°C (±1°C) during the entire experimental period. At the end of the exposure period, the birds were sacrificed and specimens were taken of the duodenum, jejunum and ileum for histology. Blood was collected for oxidative stress analysis. Histo-morphological and morphometric analyses of the intestines indicated that the duodenum and jejunum showed more damage than the ileum. The major alterations in the control intestines were limited to the villus tips, while heat stress led to villus denudation and crypt damage. When compared with morphologically normal villi, heat-stress-associated alterations were also observed in villus height (decreased), villus breadth at base (increased) and epithelial cell area (decreased). Birds exposed to heat stress presented with an increase in glutathione peroxidase activity and a decreased antioxidant capacity. It can be concluded that the chosen model allows a reproducible quantification of heat stress effects, which is suitable for the evaluation of dietary intervention strategies to combat heat stress conditions.

  13. Progressive failure analysis of composite structure based on micro- and macro-mechanics models

    孙志刚; 阮绍明; 陈磊; 宋迎东


    Based on parameter design language, a program of progressive failure analysis in composite structures is proposed. In this program, the relationship between macro- and micro-mechanics is established and the macro stress distribution of the composite structure is calculated by commercial finite element software. According to the macro-stress, the damaged point is found and the micro-stress distribution of representative volume element is calculated by finite-volume direct averaging micromechanics (FVDAM). Compared with the results calculated by failure criterion based on macro-stress field (the maximum stress criteria and Hashin criteria) and micro-stress field (Huang model), it is proven that the failure analysis based on macro- and micro-mechanics model is feasible and efficient.

  14. Optimization of custom cementless stem using finite element analysis and elastic modulus distribution for reducing stress-shielding effect.

    Saravana Kumar, Gurunathan; George, Subin Philip


    This work proposes a methodology involving stiffness optimization for subject-specific cementless hip implant design based on finite element analysis for reducing stress-shielding effect. To assess the change in the stress-strain state of the femur and the resulting stress-shielding effect due to insertion of the implant, a finite element analysis of the resected femur with implant assembly is carried out for a clinically relevant loading condition. Selecting the von Mises stress as the criterion for discriminating regions for elastic modulus difference, a stiffness minimization method was employed by varying the elastic modulus distribution in custom implant stem. The stiffness minimization problem is formulated as material distribution problem without explicitly penalizing partial volume elements. This formulation enables designs that could be fabricated using additive manufacturing to make porous implant with varying levels of porosity. Stress-shielding effect, measured as difference between the von Mises stress in the intact and implanted femur, decreased as the elastic modulus distribution is optimized.

  15. [Evaluation of diving stress implication of analysis of work loads].

    Mano, Y


    An investigation was conducted on the actual diving conditions of 2,996 divers in Japan except those engaged in fishery. Results of analysis made on the diving profiles and actual working conditions showed that some of their jobs required heavy load and that the burden was excessively large. Little study has been made for the proper evaluation of diving stress or work loads, but it has been assumed from these limited studies that the load is not so heavy. The load has been generally estimated to be about 1.8l/min STPD of oxygen consumption (VO2) during 40 l/min STPD of expiratory gas volume/min (VE). In our examination of their actual diving work, their work load was far greater than our expectation. It was in practice not only difficult to obtain the actual VO2 but also very difficult to determine their actual fatigue. Instead of these, it is necessary to establish an adequate index for evaluating diving work load. Studies have been made in our laboratory since 1981 and regression equations have been finally obtained, by which load during diving work can be determined using heart rate as index. Seven healthy males were chosen as subjects of the present study having a mean age of 34.4 yr and a mean diving history of 7.3 yr. First, performance time was acquired in each subject by bicycle ergometer exercise and the maximalen oxygen consumption (VO2-max) was obtained. In the second step, VO2-max was obtained by using the regulator apparatus for breathing during SCUBA diving. This value was 86.1% of the first step. The third step was made in a swimming pool.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Boundary element analysis for elastic and elastoplastic problems of 2D orthotropic media with stress concentration

    Xiushan Sun; Lixin Huang; Yinghua Liu; Zhangzhi Cen; Keren Wang


    Both the orthotropy and the stress concentration are common issues in modern structural engineering. This paper introduces the boundary element method (BEM) into the elastic and elastoplastic analyses for 2D orthotropic media with stress concentration. The discretized boundary element formulations are established, and the stress formulae as well as the fundamental solutions are derived in matrix notations. The numerical procedures are proposed to analyze both elastic and elastoplastic problems of2D orthotropic media with stress concentration. To obtain more precise stress values with fewer elements, the quadratic isoparametric element formulation is adopted in the boundary discretization and numerical procedures. Numerical examples show that there are significant stress concentrations and different elastoplastic behaviors in some orthotropic media, and some of the computational results are compared with other solutions.Good agreements are also observed, which demonstrates the efficiency and reliability of the present BEM in the stress concentration analysis for orthotropic media.

  17. Writing therapy for posttraumatic stress: a meta-analysis

    A.A.P. van Emmerik; A. Reijntjes; J.H. Kamphuis


    Background: Face-to-face psychological treatments have difficulty meeting today’s growing mental health needs. For the highly prevalent posttraumatic stress (PTS) conditions, accumulating evidence suggests that writing therapy may constitute an efficient treatment modality, especially when administe

  18. Writing therapy for posttraumatic stress: a meta-analysis

    van Emmerik, A.A.P.; Reijntjes, A.; Kamphuis, J.H.


    Background: Face-to-face psychological treatments have difficulty meeting today’s growing mental health needs. For the highly prevalent posttraumatic stress (PTS) conditions, accumulating evidence suggests that writing therapy may constitute an efficient treatment modality, especially when administe

  19. Stress hormonal analysis in elite soccer players during a season

    Yiannis Michailidis


    Conclusion: These hormones and their ratios could be used as stress and recovery state indicators. Coaches can use these parameters in combination with other indicators to optimize workloads, and to avoid overreaching and overtraining.

  20. Proteomics analysis of alfalfa response to heat stress.

    Weimin Li

    Full Text Available The proteome responses to heat stress have not been well understood. In this study, alfalfa (Medicago sativa L. cv. Huaiyin seedlings were exposed to 25 °C (control and 40 °C (heat stress in growth chambers, and leaves were collected at 24, 48 and 72 h after treatment, respectively. The morphological, physiological and proteomic processes were negatively affected under heat stress. Proteins were extracted and separated by two-dimensional polyacrylamide gel electrophoresis (2-DE, and differentially expressed protein spots were identified by mass spectrometry (MS. Totally, 81 differentially expressed proteins were identified successfully by MALDI-TOF/TOF. These proteins were categorized into nine classes: including metabolism, energy, protein synthesis, protein destination/storage, transporters, intracellular traffic, cell structure, signal transduction and disease/defence. Five proteins were further analyzed for mRNA levels. The results of the proteomics analyses provide a better understanding of the molecular basis of heat-stress responses in alfalfa.

  1. Thermal stress analysis of the NASA Dryden hypersonic wing test structure

    Morris, Glenn


    Present interest in hypersonic vehicles has resulted in a renewed interest in thermal stress analysis of airframe structures. While there are numerous texts and papers on thermal stress analysis, practical examples and experience on light gage aircraft structures are fairly limited. A research program has been undertaken at General Dynamics to demonstrate the present state of the art, verify methods of analysis, gain experience in their use, and develop engineering judgement in thermal stress analysis. The approach for this project has been to conduct a series of analyses of this sample problem and compare analysis results with test data. This comparison will give an idea of how to use our present methods of thermal stress analysis, and how accurate we can expect them to be.


    VÎLCU Adrian


    Full Text Available The paper analyses the tensile behavior of woven fabrics made from 45%Wool + 55% PES used for garments. Analysis of fabric behavior during wearing has shown that these are submitted to simple and repeated uni-axial or bi-axial tensile strains. The level of these strains is often within the elastic limit, rarely going over yielding. Therefore the designer must be able to evaluate the mechanical behavior of such fabrics in order to control the fabric behavior in the garment. This evaluation is carried out based on the tensile testing, using certain indexes specific to the stress-strain curve. The paper considers an experimental matrix based on woven fabrics of different yarn counts, different or equal yarn count for warp and weft systems and different structures. The fabrics were tested using a testing machine and the results were then compared in order to determine the fabrics’ tensile behavior and the factors of influence that affect it.From the point of view of tensile testing, the woven materials having twill weave are preferable because this type of structure is characterized by higher durability and better yarn stability in the fabric. In practice, the woven material must exhibit an optimum behavior to repeated strains, flexions and abrasions during wearing process. The analysis of fabrics tensile properties studied by investigation of stress-strain diagrams reveals that the main factors influencing the tensile strength are: yarns fineness, technological density of those two systems of yarns and the weaving type.

  3. Residual stresses in coating-based systems, part Ⅰ:Mechanisms and analytical modeling

    ZHANG Xiancheng; WU Yixiong; XU Binshi; WANG Haidou


    Thin films and multi-layered coatings comprised of different classes of materials are often used for various fimctional devices. The thermo-mechanical integrity of these systems is becoming a major concern and is strongly related to the residual stresses because of the fabrication processes. In this paper, the sources of the residual stresses in the coating-based systems and the concept of"misfit strain" were briefly reviewed. Analytical models were developed to predict the residual stresses in multi-layered film structures or coating-based systems using the force and moment balances. In addition, the residual stress distributions in the functionally and compositionally graded coatings were also analyzed.

  4. Stability analysis of Reynolds stress response functional candidates

    Dafinger, M.; Hallatschek, K. [Max-Planck-Institute for Plasma Physics, EURATOM-IPP Association, Garching (Germany); Itoh, K. [National Institute for Fusion Science, Toki 509-5292 (Japan)


    Complete information on the behavior of zonal flows in turbulence systems is coded in the turbulent stress response to the respective flow pattern. We show that turbulence stress response functionals containing only the linear first order wavenumber dependence on the flow pattern result in unstable structures up to the system size. A minimal augmentation to reproduce the flow patterns observed in turbulence simulations is discussed.

  5. Verification of ESPI Stress Analysis by Means Of FEM

    Luboš PEČENKA


    Full Text Available The main goal of this paper is verification of accuracy of ESPI strain sensor Dantec dynamics Q-100. ESPI is the digital holographic interferometry method for measuring small displacements and deformations. There is necessary to consider the isotropic material properties for stress calculations using the ESPI systems. All stress measurements were performed on simple shape specimens subjected to tension and bending. The experimental results obtained on the tensile testing machine Testometric will be compared with results from Finite element calculation.

  6. Entropy Generation Analysis of Human Thermal Stress Responses

    Boregowda, Satish C.; Choate, Robert E.; Rodney Handy


    The present study involves application of an open system entropy generation formulation to analyze human thermal stress responses. The time-series human thermal stress response data are obtained by conducting a simulation using a validated finite-element human thermal model (FEHTM). These simulated human thermal response data are used as an input to the entropy generation expression to obtain human entropy generation (HEG) values. The effects of variables such as air temperature, relative hum...

  7. Stress analysis in patella by three-dimensional photoelasticity

    Chen, Riqi; Zhang, Jianxing; Jiang, Kunsheng


    In this paper, stress distribution in patella was studied by 3-D photoelastic experiments and finite element calculations. The experimental conditions were in good agreement with that of body mechanics: (1) The ratios of m. quadriceps femoris force FQ to lig. patella force FP were 1.03 - 1.42. (2) The angles between FQ and FP were 8.4 degree(s) - 18.7 degree(s). (3) The ratio of modulus of elasticity for epoxy resin and silicon rubber matched that for patella and cartilage, i.e., 145:1. The principal stresses and their path line, normal stresses, and contact stresses between patella and ossis femoris were determined in various flexion angles (15 degree(s), 30 degree(s), 45 degree(s), 60 degree(s), 75 degree(s), 90 degree(s)). Two of the correlations were: (1) Maximum principal stress in the front of patella; (sigma) max equals 35.8Wexp(0.024(alpha) ) KPa. (2) Maximum contact stress between patella and ossis femoris; (sigma) max equals -(6.86 - 0.14(alpha) + 0.02(alpha) 2)W KPa where W was body weight subjected by a single foot. It was proved that the transverse break of patella resulted from the case that the principle stress in the front of patella exceeded ultimate tensile strength. And Tension Band Wiring (TBW) therapy conformed to the law of physiological stress field. A modified K-needles position in TBW therapy was suggested. These results are useful for further research of human patella mechanics and recovery therapy. No similar result has been found in American MEDLIN Data Bank.

  8. The study on stress-cone based on HTS cable terminal

    Wu, C. Y.; Fang, J.; Huang, X. H.; Lu, W. J.; Li, D.; Guo, L. J.


    Our research aims at improving the performance of 35 kV class stress-cone for HTS cable terminal. Firstly, the equivalent circuit model of a stress-cone is constructed for simulation. The relation between the sag voltage of each layer can be characterized by structural and material parameters, such as the stress-cone’s plate length, plate radius, insulating material thickness and dielectric constant. Secondly, the simulation based on ANSYS is developed for analyzing the electric field of stress cone of HTS cable terminal, by altering the length of step and insulation material parameter of stress cone, we get the voltage of each plate layer, horizontal electric field and vertical electric field, and the influence of stress-cone parameter on stress cone electric field is analyzed.

  9. Coke drums inspection and evaluation using stress and strain analysis techniques

    Haraguchi, Marcio Issamu [Tricom Tecnologia e Servicos de Manutencao Industrial Ltda., Piquete, SP (Brazil); Samman, Mahmod [Houston Engineering Solutions, Houston, TX (United States); Tinoco, Ediberto Bastos; Marangone, Fabio de Castro; Silva, Hezio Rosa da; Barcelos, Gustavo de Carvalho [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)


    Coke drums deform due to a complex combination of mechanical and thermal cyclic stresses. Bulges have progressive behavior and represent the main maintenance problem related to these drums. Bulge failure typically result in through-wall cracks, leaks, and sometimes fires. Such failures generally do not represent a great risk to personnel. Repairs needed to maintain reliability of these vessels might require extensive interruption to operation which in turn considerably impacts the profitability of the unit. Therefore the condition, progression and severity of these bulges should be closely monitored. Coke drums can be inspected during turnaround with 3D Laser Scanning and Remote Visual Inspection (RVI) tools, resulting in a detailed dimensional and visual evaluation of the internal surface. A typical project has some goals: inspect the equipment to generate maintenance or inspection recommendations, comparison with previous results and baseline data. Until recently, coke drum structural analysis has been traditionally performed analyzing Stress Concentration Factors (SCF) thought Finite Element Analysis methods; however this technique has some serious technical and practical limitations. To avoid these shortcomings, the new strain analysis technique PSI (Plastic Strain Index) was developed. This method which is based on API 579/ ASME FFS standard failure limit represents the state of the art of coke drum bulging severity assessment has an excellent correlation with failure history. (author)

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

    O.B. Kozin


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

  11. Prediction and Expression Analysis of miRNAs Associated with Heat Stress in Oryza sativa



    Computational prediction of potential microRNAs (miRNAs) and their target genes was performed to identify the miRNAs and genes associated with temperature response in rice. The data of temperature-responsive miRNAs of Arabidopsis, and miRNAs and the whole genome data of rice were used to predict potential miRNAs in Oryza sativa involved in temperature response. A total of 55 miRNAs were common in both the species, and 27 miRNAs were predicted at the first time in rice. Target genes were searched for these 27 miRNAs in rice genome following stringent criteria. Real time PCR based on expression analysis of nine miRNAs showed that majority of the miRNAs were down regulated under heat stress for rice cultivar Nagina 22. Furthermore, miR169, miR1884 and miR160 showed differential expression in root and shoot tissues of rice. Identification and expression studies of miRNAs during heat stress will advance the understanding of gene regulation under stress in rice.

  12. Analysis of stress corrosion cracking in alloy 718 following commercial reactor exposure

    Leonard, Keith J.; Gussev, Maxim N.; Stevens, Jacqueline N.; Busby, Jeremy T.


    Alloy 718 is generally considered a highly corrosion-resistant material but can still be susceptible to stress corrosion cracking (SCC). The combination of factors leading to SCC susceptibility in the alloy is not always clear enough. In the present work, alloy 718 leaf spring (LS) materials that suffered stress corrosion damage during two 24-month cycles in pressurized water reactor service, operated to >45 MWd/mtU burn-up, was investigated. Compared to archival samples fabricated through the same processing conditions, little microstructural and property changes occurred in the material with in-service irradiation, contrary to high dose rate laboratory-based experiments reported in literature. Though the lack of delta phase formation along grain boundaries would suggest a more SCC resistant microstructure, grain boundary cracking in the material was extensive. Crack propagation routes were explored through focused ion beam milling of specimens near the crack tip for transmission electron microscopy as well as in polished plan view and cross-sectional samples for electron backscatter diffraction analysis. It has been shown in this study that cracks propagated mainly along random high-angle grain boundaries, with the material around cracks displaying a high local density of dislocations. The slip lines were produced through the local deformation of the leaf spring material above their yield strength. The cause for local SCC appears to be related to oxidation of both slip lines and grain boundaries, which under the high in-service stresses resulted in crack development in the material.

  13. Stressful life events during adolescence and risk for externalizing and internalizing psychopathology: a meta-analysis.

    March-Llanes, Jaume; Marqués-Feixa, Laia; Mezquita, Laura; Fañanás, Lourdes; Moya-Higueras, Jorge


    The main objective of the present research was to analyze the relations between stressful life events and the externalizing and internalizing spectra of psychopathology using meta-analytical procedures. After removing the duplicates, a total of 373 papers were found in a literature search using several bibliographic databases, such as the PsycINFO, Medline, Scopus, and Web of Science. Twenty-seven studies were selected for the meta-analytical analysis after applying different inclusion and exclusion criteria in different phases. The statistical procedure was performed using a random/mixed-effects model based on the correlations found in the studies. Significant positive correlations were found in cross-sectional and longitudinal studies. A transactional effect was then found in the present study. Stressful life events could be a cause, but also a consequence, of psychopathological spectra. The level of controllability of the life events did not affect the results. Special attention should be given to the usage of stressful life events in gene-environment interaction and correlation studies, and also for clinical purposes.

  14. Finite Element Optimised Back Analysis of In Situ Stress Field and Stability Analysis of Shaft Wall in the Underground Gas Storage

    Yifei Yan


    Full Text Available A novel optimised back analysis method is proposed in this paper. The in situ stress field of an underground gas storage (UGS reservoir in a Turkey salt cavern is analysed by the basic theory of elastic mechanics. A finite element method is implemented to optimise and approximate the objective function by systematically adjusting boundary loads. Optimising calculation is performed based on a novel method to reduce the error between measurement and calculation as much as possible. Compared with common back analysis methods such as regression method, the method proposed can further improve the calculation precision. By constructing a large circular geometric model, the effect of stress concentration is eliminated and a minimum difference between computed and measured stress can be guaranteed in the rectangular objective region. The efficiency of the proposed method is investigated and confirmed by its capability on restoring in situ stress field, which agrees well with experimental results. The characteristics of stress distribution of chosen UGS wells are obtained based on the back analysis results and by applying the corresponding fracture criterion, the shaft walls are proven safe.

  15. Fractional watt Vuillemier cryogenic refrigerator program engineering notebook. Volume 2: Stress analysis

    Miller, W. S.


    A structural analysis performed on the 1/4-watt cryogenic refrigerator. The analysis covered the complete assembly except for the cooling jacket and mounting brackets. Maximum stresses, margin of safety, and natural frequencies were calculated for structurally loaded refrigerator components shown in assembly drawings. The stress analysis indicates that the design is satisfactory for the specified vibration environment, and the proof, burst, and normal operating loads.

  16. An epigenome-wide association meta-analysis of prenatal maternal stress in neonates: A model approach for replication.

    Rijlaarsdam, Jolien; Pappa, Irene; Walton, Esther; Bakermans-Kranenburg, Marian J; Mileva-Seitz, Viara R; Rippe, Ralph C A; Roza, Sabine J; Jaddoe, Vincent W V; Verhulst, Frank C; Felix, Janine F; Cecil, Charlotte A M; Relton, Caroline L; Gaunt, Tom R; McArdle, Wendy; Mill, Jonathan; Barker, Edward D; Tiemeier, Henning; van IJzendoorn, Marinus H


    Prenatal maternal stress exposure has been associated with neonatal differential DNA methylation. However, the available evidence in humans is largely based on candidate gene methylation studies, where only a few CpG sites were evaluated. The aim of this study was to examine the association between prenatal exposure to maternal stress and offspring genome-wide cord blood methylation using different methods. First, we conducted a meta-analysis and follow-up pathway analyses. Second, we used novel region discovery methods [i.e., differentially methylated regions (DMRs) analyses]. To this end, we used data from two independent population-based studies, the Generation R Study (n = 912) and the Avon Longitudinal Study of Parents and Children (ALSPAC, n = 828), to (i) measure genome-wide DNA methylation in cord blood and (ii) extract a prenatal maternal stress composite. The meta-analysis (ntotal = 1,740) revealed no epigenome-wide (meta P meta-analysis (meta P meta-analysis, the current study indicates that there are no large effects of prenatal maternal stress exposure on neonatal DNA methylation. Such replication efforts are essential in the search for robust associations, whether derived from candidate gene methylation or epigenome-wide studies.

  17. RNAseq analysis reveals oxidative stress responses of Aspergillus flavus related to stress tolerance and aflatoxin production

    Aflatoxin contamination by Aspergillus flavus is exacerbated by drought stress in the field. Given that reactive oxygen species (ROS) both accumulate in plant tissues during drought and can stimulate aflatoxin production in vitro, we examined the responses of toxigenic isolates of A. flavus to oxida...

  18. Exoproteome analysis reveals higher abundance of proteins linked to alkaline stress in persistent Listeria monocytogenes strains.

    Rychli, Kathrin; Grunert, Tom; Ciolacu, Luminita; Zaiser, Andreas; Razzazi-Fazeli, Ebrahim; Schmitz-Esser, Stephan; Ehling-Schulz, Monika; Wagner, Martin


    The foodborne pathogen Listeria monocytogenes, responsible for listeriosis a rare but severe infection disease, can survive in the food processing environment for month or even years. So-called persistent L. monocytogenes strains greatly increase the risk of (re)contamination of food products, and are therefore a great challenge for food safety. However, our understanding of the mechanism underlying persistence is still fragmented. In this study we compared the exoproteome of three persistent strains with the reference strain EGDe under mild stress conditions using 2D differential gel electrophoresis. Principal component analysis including all differentially abundant protein spots showed that the exoproteome of strain EGDe (sequence type (ST) 35) is distinct from that of the persistent strain R479a (ST8) and the two closely related ST121 strains 4423 and 6179. Phylogenetic analyses based on multilocus ST genes showed similar grouping of the strains. Comparing the exoproteome of strain EGDe and the three persistent strains resulted in identification of 22 differentially expressed protein spots corresponding to 16 proteins. Six proteins were significantly increased in the persistent L. monocytogenes exoproteomes, among them proteins involved in alkaline stress response (e.g. the membrane anchored lipoprotein Lmo2637 and the NADPH dehydrogenase NamA). In parallel the persistent strains showed increased survival under alkaline stress, which is often provided during cleaning and disinfection in the food processing environments. In addition, gene expression of the proteins linked to stress response (Lmo2637, NamA, Fhs and QoxA) was higher in the persistent strain not only at 37 °C but also at 10 °C. Invasion efficiency of EGDe was higher in intestinal epithelial Caco2 and macrophage-like THP1 cells compared to the persistent strains. Concurrently we found higher expression of proteins involved in virulence in EGDe e.g. the actin-assembly-inducing protein ActA and the

  19. Confirmatory factor analysis of the portuguese Depression Anxiety Stress Scales-21

    Apóstolo,João Luís Alves; Tanner,Barry Allen; Arfken,Cynthia Lee


    To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The co...

  20. Finite Element Analysis and Experiment Research on Surface Residual Stress of Ceramics Grinding


    The theoretical model of residual stress of ceramics grinding has been established applying thermal elastoplastic mechanics theory. While grinding at the course of grinding wheel moved along workpiece surface the distributing regulation of residual stress can be simplified into thermal elastioplastic mechanical issue, under the action of the both moving centralized force and heat source. Calculating and evaluating of surface residual stress using current procedure of finite element analysis which has been...