Search results for: surface stress

Authors: Silvia Riva, Ezekiel Chinyio

Abstract:

Introduction: Workers in different sectors are prone to stress at varying levels. They also respond to stress in different ways. An inspiration was to study stress development amongst workers in a work dangerous setting (Construction Industry) as well as how they cope with specific stress incidences. Objective: The overarching objective of the study was to study and correlate between stress and coping strategies. The research was conducted in an organizational industrial setting, and its findings on the coping actions of construction workers are reported in this article. Methods: An online cross-sectional survey was conducted with 80 participants aged 18-62. These were working for three different construction organizations in the West Midland region of the UK. Their coping actions were assessed using the COPE Inventory (Carver, 2013) instrument while the level of stress was assessed by the Perceived Stress Scale (Cohen, 1994). Results: Out of 80 workers (20 female, 25%, mean age 40.66), positive reinterpretation (M=4.15, SD=2.60) and active coping (M=4.18, SD=2.55) were the two most adaptive strategies reported by the workers while the most frequent maladaptive behavior was mental disengagement (M=3.62, SD=2.25). Among the maladaptive tactics, alcohol and drug abuse was a significant moderator in stress reactions (t=6.12, p=.000). Conclusion: Some maladaptive strategies are adopted by construction workers to cope with stress. So, it could be argued that programs of stress prevention and control in the construction industry have a basis to develop solutions that can improve and strengthen effective interventions when workers are stressed or getting stressed.

Keywords: coping, organization, strategies, stress

Procedia PDF Downloads 178

Authors: Shreyas Gambhirrao, Aditya Vichare, Aniket Tembhurne, Shahuraj Bhosale

Abstract:

In today's rapidly evolving environment, stress has emerged as a significant health concern across different age groups. Stress that isn't controlled, whether it comes from job responsibilities, health issues, or the never-ending news cycle, can have a negative effect on our well-being. The problem is further aggravated by the ongoing connection to technology. In this high-tech age, identifying and controlling stress is vital. In order to solve this health issue, the study focuses on three key metrics for stress detection: body temperature, heart rate, and galvanic skin response (GSR). These parameters along with the Support Vector Machine classifier assist the system to categorize stress into three groups: 1) Stressed, 2) Not stressed, and 3) Moderate stress. Proposed training model, a NodeMCU combined with particular sensors collects data in real-time and rapidly categorizes individuals based on their stress levels. Real-time stress detection is made possible by this creative combination of hardware and software.

Keywords: real time stress detection, NodeMCU, sensors, heart-rate, body temperature, galvanic skin response (GSR), support vector machine

Procedia PDF Downloads 44

Authors: Chisom N. Nwaigwe, Blessing N. Egbulefu, Angela Uwakwem

Abstract:

A study on Stress and its’ effect on the health of workers in Federal Medical Centres in Nigeria is presented. The aim is to evaluate how much stress related hazards health workers in our tertiary health institutions are exposed to and to create awareness and reduce the rate at which stress affect the health of the working population in Nigeria, using workers in Federal Medical Centre, Umuahia as a case study. The descriptive survey design was adopted with the aid of 100 questionnaires delivered to the respondents in order to obtain first-hand information. From the findings, the major causes of stress were identified as inadequate staffing, unresolved family problems and psychological/cultural factors like the return of a lactating mother to work after three months post-delivery. The effects of stress on the workers were identified as hypertension, poor job performances, depression, asthma, and peptic ulcers. The study recommended instituting counseling units for stress management, holding seminars on stress management and increasing the salary scale (remuneration) and proper roster planning as solutions to stress reduction in our hospitals. This study is important to management in planning staffing, roaster, and a rehabilitation programme for her staff.

Keywords: stress, causes, effects, workers

Procedia PDF Downloads 437

Authors: Xiaohong Wu, Tao Zhang

Abstract:

Since Macau opened its door to international gambling firms in 2002, Macau casino hotel industry has been booming. Casino hotels are different from the non-casino hotels in the main profit source and services. The paper aims to analyze differences in employees’ work stress and job satisfaction across the casino hotels and the non-casino hotels. Through questionnaires, the paper investigates 200 employees from casino hotels and 200 employees from non-casino hotels. Work stress and job satisfaction of employees in casino hotels and non-casino hotels are compared. Statistic techniques such as descriptive statistics and one-way analysis of variance (one-way ANOVA) are applied. The paper tries to achieve the below aims: Firstly, explore and compare the impact of gender, job position, marital status and fertility status on employees’ work stress and job satisfaction. Secondly, explore the perception of work stress and job satisfaction across casino hotel and non-casino hotel employees. Thirdly, explore the relationship between work stress and job satisfaction. The result indicates there are not significant differences in employees’ work stress and job satisfaction perception between different genders, positions, marital situations and fertility situations. The result confirms there are significant differences in employees’ work stress and job satisfaction perception between casino and non-casino employees. Moreover, Work stress negatively influences job satisfaction.

Keywords: casino, employee, job satisfaction, work stress

Procedia PDF Downloads 287

Authors: Bushra Mussawar, Saleha Younus

Abstract:

Students often view their academic life demanding and stressful. However, apart from academics, stress springs from various other sources namely, finance, family, health, friends etc. The present study aims to assess the level of perceived stress in medical and fine arts students, and to determine the coping strategies used by the students to mitigate stress. The sample of the study consisted of 178 medical and fine arts students. The sample was selected through purposive sampling. Pearson correlation coefficient and T-test were used to analyze data. Results of the study revealed that there exists a positive relationship between perceived stress and coping strategies. Additionally, the two groups showed marked differences in terms of stress perception and coping styles. The level of perceived stress was found to be high in medical students nonetheless, they employed more positive coping strategies than fine arts students who scored high on negative coping strategies which are deleterious to the overall wellbeing.

Keywords: perceived stress, coping strategies, medical, fine arts students

Procedia PDF Downloads 258

Authors: Najib Ahmad Marzuki, Che Su Mustaffa, Johana Johari, Nur Haffiza Rahaman

Abstract:

The purpose of this paper is to examine the effects and relationship of stress and social support towards the quality of life among flood victims in Malaysia. A total of 764 respondents took part in the survey via random sampling. The depression, anxiety, and stress scales were utilized to measure stress while The Multidimensional Scale of Perceived Social Support was used to measure the quality of life. The findings of this study indicate that there were significant correlations between variables in the study. The findings show a significant negative relation between stress and quality of life, and significant positive correlations between support from family as well as support from friends with the quality of life. Stress and support from family were found to be significant predictors and influences the quality of life among flood victims.

Keywords: stress, social support, quality of life, flood victims

Procedia PDF Downloads 513

Authors: Andres Frederic

Abstract:

We present the MindFlow system supporting the detection and the diagnosis of stresses. The heart of the system is a knowledge synthesis engine allowing occupational health stakeholders (psychologists, occupational therapists and human resource managers) to formulate queries related to stress and responding to users requests by recommending a pattern of stress if one exists. The stress pattern diagnosis is based on expert knowledge stored in the MindFlow stress ontology including stress feature vector. The query processing may involve direct access to the MindFlow system by occupational health stakeholders, online communication between the MindFlow system and the MindFlow domain experts, or direct dialog between a occupational health stakeholder and a MindFlow domain expert. The MindFlow knowledge model is generic in the sense that it supports the needs of psychologists, occupational therapists and human resource managers. The system presented in this paper is currently under development as part of a Dutch-Japanese project and aims to assist organisation in the quick diagnosis of stress patterns.

Keywords: occupational stress, stress management, physiological measurement, accident prevention

Procedia PDF Downloads 393

Authors: Yee Hooi Min, Abdul Hadi, M. N., A. G. Kay Dora

Abstract:

Form-finding has to be carried out for tensioned fabric structure in order to determine the initial equilibrium shape under prescribed support condition and pre-stress pattern. Tensioned fabric structures are normally designed to be in the form of equal tensioned surface. Tensioned fabric structure is highly suited to be used for realizing surfaces of complex or new forms. However, research study on a new form as a tensioned fabric structure has not attracted much attention. Another source of inspiration minimal surface which could be adopted as form for tensioned fabric structure is very crucial. The aim of this study is to propose initial equilibrium shape of tensioned fabric structures in the form of Monkey Saddle. Computational form-finding is frequently used to determine the possible form of uniformly stressed surfaces. A tensioned fabric structure must curve equally in opposite directions to give the resulting surface a three dimensional stability. In an anticlastic doubly curved surface, the sum of all positive and all negative curvatures is zero. This study provides an alternative choice for structural designer to consider the Monkey Saddle applied in tensioned fabric structures. The results on factors affecting initial equilibrium shape can serve as a reference for proper selection of surface parameter for achieving a structurally viable surface. Such in-sight will lead to improvement of rural basic infrastructure, economic gains, sustainability of built environment and green technology initiative.

Keywords: anticlastic, curvatures, form-finding, initial equilibrium shape, minimal surface, tensioned fabric structure

Procedia PDF Downloads 506

Authors: Nitin Joseph

Abstract:

Objectives: This study was done to assess emotional intelligence levels and to find out its association with socio demographic variables and perceived stress among medical students. Material and Methods: This study was done among first and second year medical students. Data was collected using a self-administered questionnaire. Results: Emotional intelligence scores was found to significantly increase with age of the participants (F=2.377, P < 0.05). Perceived stress was found to be significantly more among first year (t=1.997, P=0.05). Perceived stress was found to significantly decrease with increasing emotional intelligence scores (r = – 0.226, P < 0.001). Conclusion: First year students were found to be more vulnerable to stress than their seniors probably due to lesser emotional intelligence. As both these parameters are related, ample measures to improve emotional intelligence needs to be supported in the training curriculum of beginners so as to make them more stress free during early student life.

Keywords: emotional intelligence, medical students, perceived stress, socio demographic variables

Procedia PDF Downloads 425

Authors: Hygreeva Kiran Namburi, Anna Hojna, Edita Lecianova, Fencl Zdenek

Abstract:

Irradiation Assisted Stress Corrosion Cracking [IASCC] is one of the most significant environmental degradation in the internal components made from Austenitic stainless steel. This mechanism is still not fully understood and there are no suitable criteria for prediction of the damage during operation. In this work, core basket material 08Ch18N10T austenitic stainless steel acquired from decommissioned NPP Nord / Greifswald Unit 1, VVER 440-230 type, operated for 15 years and irradiated at 5.2 dpa is studied. This material was tensile tested at two different test temperatures and strain rates in air and at the elevated temperature under the water environment. SEM observations of the fracture surface documented ductile fracture of the samples tested in air, but areas of IASCC tested in water. This paper emphasizes on the microscopic examination results from the mechanically tested samples to determine the underlying IASCC physical damage process. TEM observations of thin foils made from the gauge sections that are closer to the fractured surface of the specimen aimed to find variances in interaction of dislocations and grain boundaries owing to different test conditions.

Keywords: irradiation assisted stress corrosion cracking, core basket material, SEM observations of the fracture surface, microscopic examination results

Procedia PDF Downloads 326

Authors: Lídia Chienda, Tchilissila A. Simoes

Abstract:

Angola is known for the low quality of maternal health services, registering one of the highest maternal and child mortality of Africa. Working in these health facilities may be of great challenge for health professionals. In this study, we aimed to identify the presence of occupational stress in 76 nurses working in a maternity ward in Lubango, Southern Angola. The participants completed the Health Professional Stress Questionnaire and reported a moderate and high level of stress. To these individuals, 'receiving a low salary,' 'inadequate/insufficient salary,' 'overwork or very demanding work' and 'working long hours in a row' seemed to be the main indicators of occupational stress. Moreover, there was an influence of the work overload, the remuneration earned, the career, and family conflicts in the occupational stress index. These results contributed to a better understanding of the difficulties Angolan nurses are facing and the need to implement policies that envisage the wellbeing of this population.

Keywords: Africa, maternity wards, nursing, occupational stress

Procedia PDF Downloads 158

Authors: Rami Al-Sadi

Abstract:

The assignment of lexical stress in English to its correct syllable is an enormous challenge to EFL learners, especially if their first language (L1) phonology is very different from English phonology. Arabic-speaking EFL learners not only stumble very frequently when it comes to placing the lexical stress in a given word, but they also seem to relegate the role of lexical stress as unimportant, mainly because in Arabic, unlike in English, lexical stress is not phonemic. This study aims at exploring the possible benefits of utilizing spectrographic representations of English words correctly pronounced, for the purpose of finding out how these spectrograms can provide a visual aid to the learners and help them rectify their stress placement errors as they see in real time spectrograms of the correct pronunciations juxtaposed on a computer screen with spectrograms of their own pronunciations for easy comparison. The study involved 120 students from the English Department at Prince Sattam bin Abdulaziz University in Saudi Arabia. 60 participants were taught the English lexical stress rules and also received spectrographic guidance on pronunciation; the other 60 received only verbal instruction on the stress rules and verbal feedback on their pronunciations. Statistical results showed that when the learners had the opportunity to ‘see’ their pronunciation mistakes, they were three times more likely to rectify their placement of lexical stress.

Keywords: Arabic-speaking EFL learners, lexical stress, pronunciation, spectrographic representation, stress placement

Procedia PDF Downloads 79

Authors: Jehnming Lin

Abstract:

The effects of the contact ball-lens on the soda lime glass in laser thermal cleavage with a cw Nd-YAG laser were investigated in this study. A contact ball-lens was adopted to generate a bending force on the crack formation of the soda-lime glass in the laser cutting process. The Nd-YAG laser beam (wavelength of 1064 nm) was focused through the ball-lens and transmitted to the soda-lime glass, which was coated with a carbon film on the surface with a bending force from a ball-lens to generate a tensile stress state on the surface cracking. The fracture was controlled by the contact ball-lens and a straight cutting was tested to demonstrate the feasibility. Experimental observations on the crack propagation from the leading edge, main section and trailing edge of the glass sheet were compared with various mechanical and thermal loadings. Further analyses on the stress under various laser powers and contact ball loadings were made to characterize the innovative technology. The results show that the distributions of the side crack at the leading and trailing edges are mainly dependent on the boundary condition, contact force, cutting speed and laser power. With the increase of the mechanical and thermal loadings, the region of the side cracks might be dramatically reduced with proper selection of the geometrical constraints. Therefore, the application of the contact ball-lens is a possible way to control the fracture in laser cleavage with improved cutting qualities.

Keywords: laser cleavage, stress analysis, crack visualization, laser

Procedia PDF Downloads 413

Authors: Ibrahim Ajani Tijani, C. W. Lim

Abstract:

Limited studies have examined the effect of size on the mechanical behavior of confined concrete subjected to 3-dimensional (3D) test. With the novel 3D testing system to produce passive confinement, concrete cubes were tested to examine the effect of size on stress-strain behavior of the specimens. The effect of size on 3D stress-strain relationship was scrutinized and compared to the stress-strain relationship available in the literature. It was observed that the ultimate stress and the corresponding strain was related to the confining rigidity and size. The size shows a significant effect on the intersection stress and a new model was proposed for the intersection stress based on the conceptual design of the confining plates.

Keywords: concrete, aggregate size, size effect, 3D compression, passive confinement

Procedia PDF Downloads 179

Authors: Parveen K. Saini, Tarun Agarwal

Abstract:

An investigation into the effect of countersunk depth, plate thickness, countersunk angle and plate width on the stress concentration around countersunk hole is carried out with the help of finite element analysis. The variation of stress concentration with respect to these parameters is studied for three types of loading viz. uniformly distributed load, uniformly varying load and functionally distributed load. The results of the finite element analysis are interpreted and some conclusions are drawn. The distribution of stress concentration around countersunk hole in isotropic plates simply supported at all the edges is found similar and is independent of loading. The maximum stress concentration also occurs at a particular point irrespective of the loading conditions.

Keywords: stress concentration factor, countersunk hole, finite element, ANSYS

Procedia PDF Downloads 414

Authors: Samia Khadhar, Anis Chekirbene, Nouha Khiari, Amira Mabrouki

Abstract:

The persistent organic pollutants (POPs) in aquatic environments are one of the most worrying problems for environmental sustainability and human health because of their carcinogenic and toxic characteristics. Human anthropogenic actions (wastewater discharges, agricultural and industrial activities) without prior treatment are the main cause of this organic pollution. Oued Madjerda is considered the most important river in Tunisia, hence the importance of assessing the level of organic pollution of water and sediments, taking into account the anthropogenic stress exerted on this river. Water and sediment samples were taken from the middle and lower valley of the Medjerda to determine the state of contamination by 7PCBs, priority 15PAHs, and pesticides. The analysis was performed by gas chromatography (GC) and liquid phase coupled to HPLC MS-MS mass spectroscopy. The results showed that for the waters, the total PAH and PCB contents vary respectively from 0.0023 to 7.72 mg/l and from 0.0001 to 0.179 mg/l. In surface sediments 0 to 15 cm, 7PCB levels vary from 1,112 to 110,062 µg/kg-1. In this study, we tried to determine the concentration of 96 pesticides in surface sediments; analyzes showed the presence of Buprofezin, propamocarb-HCl, hexaconazole, flutriafol, quinalphos, and tebufenpyrad with concentrations varying from 1.06 to 2.388 µg/kg-1. The pace of the spatial variation confirms the impact of wastewater discharged on the quality of water and sediments despite the perennial aspect of the river.

Keywords: Wadi Madjerda, organic pollution, water and sediments surface, anthropics stress

Procedia PDF Downloads 93

Authors: Mohammad Vahedi Torshizi

Abstract:

In this investigation, at first, bending stress, contact stress, Safety factor of bending and Safety factor of contact between sun gear and planet gear tooth was determined using mathematical equations. Also, The amount of Sun Revolution in, Speed carrier, power Transmitted of the sun, sun torque, sun peripheral speed, Enter the tangential force gears, was calculated using mathematical equations. According to the obtained results, maximum of bending stress and contact stress occurred in three plantary and low status of four plantary. Also, maximum of Speed carrier, sun peripheral speed, Safety factor of bending and Safety factor of contact obtained in four plantary and maximum of power Transmitted of the sun, Enter the tangential force gears, bending stress and contact stress was in three pantry and factors And other factors were equal in the two planets.

Keywords: bending stress, contact stress, plantary, mathematical equations

Procedia PDF Downloads 257

Authors: Onwumere O. J.

Abstract:

The teaching of stress at any level of education could be a daunting task for the second language teacher because most times, they are bereft of the right approach to use in teaching it even at the fact is that, teaching it. But the fact is that teaching stress even at the middle basic could be interesting if the right approach is employed. To this end, the researcher was of the view that grouping could be a very good strategy to employ in order to sustain the interest of the learner and that the use at drums would be a good way to concretise the teaching of stress at this level. He was able to do this by discussing stress, grouping as a good technique, and the use of drums in teaching stress. To establish the fact that the use of drums would be very effective, four research questions contained in a questionnaire were structured. Three hundred (300) teachers of English in four tertiary institutions, three secondary schools and three primary schools in Nigeria were used. Based on the data analysis and findings, suggestions were given on how teachers and learners could use drums to make the teaching and learning of stress enjoyable for both teachers and learners at the middle basic of education.

Keywords: concretise, grouping, right approach, second language

Procedia PDF Downloads 514

Authors: Rafik Baouche, Rabah Chaouchi

Abstract:

This work reports the first comprehensive stress field interpretation from the eleven recently drilled wells in the Berkaoui Basin, Algerian Sahara. A cumulative length of 7000+m acoustic image logs from 06 vertical wells were investigated, and a mean NW-SE (128°-145° N) maximum horizontal stress (SHMax) orientation is inferred from the B-D quality wellbore breakouts. The study integrates log-based approach with the downhole measurements to infer pore pressure, in-situ stress magnitudes. Vertical stress (Sv), interpreted from the bulk-density profiles, has an average gradient of 22.36 MPa/km. The Ordovician and Cambrian reservoirs have a pore pressure gradient of 13.47-13.77 MPa/km, which is more than the hydrostatic pressure regime. A 17.2-18.3 MPa/km gradient of minimum horizontal stress (Shmin) is inferred from the fracture closure pressure in the reservoirs. Breakout widths constrained the SHMax magnitude in the 23.8-26.5 MPa/km range. Subsurface stress distribution in the central Saharan Algeria indicates that the present-day stress field in the Berkaoui Basin is principally strike-slip faulting (SHMax > Sv > Shmin). Inferences are drawn on the regional stress pattern and drilling and reservoir development.

Keywords: stress, imagery, breakouts, sahara

Procedia PDF Downloads 45

Authors: Tejeet Singh, Ishavneet Singh

Abstract:

The present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminum matrix reinforced with silicon-carbide in particulate form. The creep behavior of the composite material has been described by the threshold stress based creep law. The values of stress exponent appearing in the creep law were selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stress and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.

Keywords: steady state creep, composite, cylinder, pressure

Procedia PDF Downloads 389

Authors: Sanjeev Kumar, Vikas Kumar

Abstract:

Inconel 718 (IN718) is a high strength nickel-based superalloy designed for high-temperature applications up to 650 °C. It is widely used in gas turbines of jet engines and related aerospace applications because of its good mechanical properties and structural stability at elevated temperatures. Because of good performance ratio and excellent process capability, this alloy has been used predominantly for aeronautic engine components like compressor disc and compressor blade. The main precipitates that contribute to high-temperature strength of IN718 are γʹ Ni₃(Al, Ti) and mainly γʹʹ (Ni₃ Nb). Various processes have been used for modification of the surface of components, such as Laser Shock Peening (LSP), Conventional Shot Peening (SP) and Ultrasonic Shot Peening (USP) to induce compressive residual stress (CRS) and development of fine-grained structure in the surface region. Surface nanostructure by ultrasonic shot peening is a novel methodology of surface modification to improve the overall performance of structural components. Surface nanostructure was developed on the peak aged IN718 superalloy using USP and its effect was studied on low cycle fatigue (LCF) life. Nanostructure of ~ 49 to 73 nm was developed in the surface region of the alloy by USP. The gage section of LCF samples was USPed for 5 minutes at a constant frequency of 20 kHz using StressVoyager to modify the surface. Strain controlled cyclic tests were performed for non-USPed and USPed samples at ±Δεt/2 from ±0.50% to ±1.0% at strain rate (ė) 1×10⁻³ s⁻¹ under reversal loading (R=‒1) at room temperature. The fatigue life of the USPed specimens was found to be more than that of the non-USPed ones. LCF life of the USPed specimen at Δεt/2=±0.50% was enhanced by more than twice of the non-USPed specimen.

Keywords: IN718 superalloy, nanostructure, USP, LCF life

Procedia PDF Downloads 84

Authors: Priyakant Vaghela, Jagdish Prajapati

Abstract:

Bending stress at the root of the gear tooth is the very important criteria in gear design and it should be kept the minimum. Minimization of bending stress at the root of the gear tooth is a recent demand from industry. This paper presents an innovative approach to obtain minimum bending stress at the root of a tooth by optimizing tooth root profile and drive side pressure angle. Circular-filleted at the root of the tooth is widely used in the design. Circular fillet creates discontinuity at the root of the tooth. So, at root stress concentration occurs. In order to minimize stress concentration, an important criterion is a G2 continuity at the blending of the gear tooth. A Bezier curve is used with G2 continuity at the root of asymmetric spur gear tooth. The comparison has been done between normal and modified tooth using ANSYS simulation. Tooth root profile and drive side pressure angle are optimized to minimize bending stress at the root of the tooth of the asymmetric involute spur gear. Von Mises stress of optimized profile is analyzed and compared with normal profile symmetric gear. Von Mises stress is reducing by 31.27% by optimization of drive side pressure angle and root profile. Stress concentration of modified gear was significantly reduced.

Keywords: asymmetric spur gear tooth, G2 continuity, pressure angle, stress concentration at the root of tooth, tooth root stress

Procedia PDF Downloads 156

Authors: E. Farg, M. M. El-Sharkawy, M. S. Mostafa, S. M. Arafat

Abstract:

Mapping water stress provides important baseline data for sustainable agriculture. Recent developments in the new Sentinel-1 data which allow the acquisition of high resolution images and varied polarization capabilities. This study was conducted to detect and quantify vegetation water content from canopy backscatter for extracting spatial information to encourage drought mapping activities throughout new reclaimed sandy soils in western Nile delta, Egypt. The performance of radar imagery in agriculture strongly depends on the sensor polarization capability. The dual mode capabilities of Sentinel-1 improve the ability to detect water stress and the backscatter from the structure components improves the identification and separation of vegetation types with various canopy structures from other features. The fieldwork data allowed identifying of water stress zones based on land cover structure; those classes were used for producing harmonious water stress map. The used analysis techniques and results show high capability of active sensors data in water stress mapping and monitoring especially when integrated with multi-spectral medium resolution images. Also sub soil drip irrigation systems cropped areas have lower drought and water stress than center pivot sprinkler irrigation systems. That refers to high level of evaporation from soil surface in initial growth stages. Results show that high relationship between vegetation indices such as Normalized Difference Vegetation Index NDVI the observed radar backscattering. In addition to observational evidence showed that the radar backscatter is highly sensitive to vegetation water stress, and essentially potential to monitor and detect vegetative cover drought.

Keywords: canopy backscatter, drought, polarization, NDVI

Procedia PDF Downloads 115

Authors: F. Husem, M. E. Turan, Y. Sun, H. Ahlatci, I. Tozlu

Abstract:

Residual stress and fatigue crack growth rates are important to determine mechanical behavior of rails. This study aims to make relationship between residual stress and fatigue crack growth values in rails. For this purpose, three R260 quality rails (0.6-0.8% C, 0.6-1.25 Mn) were chosen. Residual stress of samples was measured by cutting method that is related in railway standard. Then samples were machined for fatigue crack growth test and analyze was completed according to the ASTM E647 standard which gives information about parameters of rails for this test. Microstructure characterizations were examined by Light Optic Microscope (LOM). The results showed that residual stress change with fatigue crack growth rate. The sample has highest residual stress exhibits highest crack growth rate and pearlitic structure can be seen clearly for all samples by microstructure analyze.

Keywords: residual stress, fatigue crack growth, R260, SEM, ASTM E647

Procedia PDF Downloads 302

Authors: Amin Derakhshan, Mohammad Mikaili, Mohammad Ali Khalilzadeh, Amin Mohammadian

Abstract:

This paper proposes a stress recognition system from multi-modal bio-potential signals. For stress recognition, Support Vector Machines (SVM) and LDA are applied to design the stress classifiers and its characteristics are investigated. Using gathered data under psychological polygraph experiments, the classifiers are trained and tested. The pattern recognition method classifies stressful from non-stressful subjects based on labels which come from polygraph data. The successful classification rate is 96% for 12 subjects. It means that facial thermal imaging due to its non-contact advantage could be a remarkable alternative for psycho-physiological methods.

Keywords: stress, thermal imaging, face, SVM, polygraph

Procedia PDF Downloads 455

Authors: Jeonghun Lee

Abstract:

Thyroid-stimulating hormone (TSH) is regulated by the negative feedback of T3 and T4 but is affected by cortisol and cytokines during allostasis. Hence, TSH levels can be influenced by stress through cortisol. In the present study, changes in TSH levels under stress and the potential of TSH as a stress marker were examined in patients lacking T3 or T4 feedback after thyroid surgery. The three stress questionnaires (Korean version of the Daily Stress Inventory, Social Readjustment Rating Scale, and Stress Overload Scale-Short [SOSS]), open-ended question (OQ), and thyroid function tests were performed twice in 106 patients enrolled from January 2019 to October 2020. Statistical analysis was performed using the generalized linear mixed effect model (GLMM) in R software version 4.1.0. In a multiple LMM involving 106 patients, T3, T4, SOSS (category), open-ended questions, the extent of thyroidectomy, and preoperative TSH were significantly correlated with lnTSH. T3 and T4 increased by 1 and lnTSH decreased by 0.03, 3.52, respectively. In case of a stressful event on OQ, lnTSH increased by 1.55. In the high-risk group, lnTSH increased by 0.79, compared with the low group (p<0.05). TSH had a significant relationship with stress, together with T3, T4, and the extent of thyroidectomy. As such, it has the potential to be used as a stress marker, though it showed a low correlation with other stress questionnaires. To address this limitation, questionnaires on various social environments and research on copy strategies are necessary for future studies.

Keywords: stress, surgery, thyroid stimulating hormone, thyroidectomy

Procedia PDF Downloads 65

Authors: Terri A. Croteau, Todd G. Morrison

Abstract:

Despite increased scholarly attention paid to minority stress and sexual satisfaction among sexual minorities, to the authors’ knowledge, no researchers, to date, have attempted to synthesize this literature. To address this omission, the authors conducted a meta-analytic review of the association between sexual minority stress (i.e., sexual identity stigma, internalized sexual identity stigma, and sexual identity concealment) and sexual satisfaction. Twenty-seven articles containing 58 effect sizes were analyzed (N = 183,582). Findings indicated a small, inverse relationship between these constructs, indicating that minority stress may lead to diminished sexual satisfaction among gay/lesbian and bisexual individuals. Further, the overall effect size varied as a function of minority stress type, such that the effect for internalized stigma was significantly larger than the effects for stigma or concealment. Age also moderated the relationship between minority stress and sexual satisfaction; specifically, older age was associated with a smaller effect, suggesting that older adults may be better at coping with minority stress than younger adults. Limitations, implications, and directions for future research are discussed.

Keywords: minority stress, stigma, sexual satisfaction, sexual minorities

Procedia PDF Downloads 104

Authors: Khodamorad Nabaki, Jianhu Shen, Xiaodong Huang

Abstract:

This paper develops a method for considering the critical fatigue stress as a constraint in the Bi-directional Evolutionary Structural Optimization (BESO) method. Our aim is to reach an optimal design in which high cycle fatigue failure does not occur for a specific life time. The critical fatigue stress is calculated based on modified Goodman criteria and used as a stress constraint in our topology optimization problem. Since fatigue generally does not occur for compressive stresses, we use the p-norm approach of the stress measurement that considers the highest tensile principal stress in each point as stress measure to calculate the sensitivity numbers. The BESO method has been extended to minimize volume an object subjected to the critical fatigue stress constraint. The optimization results are compared with the results from the compliance minimization problem which shows clearly the merits of our newly developed approach.

Keywords: topology optimization, BESO method, p-norm, fatigue constraint

Procedia PDF Downloads 268

Authors: Yu-Shan Wu, Po-Liang Lai, I-Ming Chu

Abstract:

Poly(methylmethacrylate)(PMMA) is the most frequently used bone void filler for vertebral augmentation in osteoporotic fracture. PMMA bone cement not only exhibits strong mechanical properties but also can fabricate according to the shape of bone defect. However, the adhesion between the PMMA-based cement and the adjacent bone is usually weak and as PMMA bone cement is inherently bioinert. The combination of bioceramics and polymers as composites may increase cell adhesion and improve biocompatibility. The nano-hydroxyapatite(HAP) not only plays a significant role in maintaining the properties of the natural bone but also offers a favorable environment for osteoconduction, protein adhesion, and osteoblast proliferation. However, defects and cracks can form at the polymer/ceramics interface, resulting in uneven distribution of stress and subsequent inferior mechanical strength. Surface-modified HAP nano-crystals were prepared by chemically grafting poly(ε-caprolactone)(PCL) on surface-modified nano-HAP surface to increase the affinity of polymer/ceramic phases .Thus, incorporation of surface-modified nano-hydroxyapatite (EC-HAP) may not only improve the interfacial adhesion between cement and bone and between nanoparticles and cement, but also increase biocompatibility. In this research, PMMA mixing with 0, 5, 10, 15, 20, 25 and 30 wt% EC-HAP were examined. MC3T3-E1 cells were used for the biological evaluation of the response to the cements in vitro. Morphology was observed using scanning electron microscopy (SEM). Mechanical properties of HAP/PMMA and EC-HAP/PMMA cement were investigated by compression test. Surface wettability of the cements was measured by contact angles.

Keywords: bone cement, biocompatibility, nano-hydroxyapatite, polycaprolactone, PMMA, surface grafting

Procedia PDF Downloads 371

Authors: Jeries J. Abou-Hanna

Abstract:

Several techniques exist for determining stress-intensity factors in linear elastic fracture mechanics analysis. These techniques are based on analytical, numerical, and empirical approaches that have been well documented in literature and engineering handbooks. However, not all techniques share the same merit. In addition to overly-conservative results, the numerical methods that require extensive computational effort, and those requiring copious user parameters hinder practicing engineers from efficiently evaluating stress-intensity factors. This paper investigates the prospects of reducing the complexity and required variables to determine stress-intensity factors through the utilization of the stress gradient and a weighting function. The heart of this work resides in the understanding that fracture emanating from stress concentration locations cannot be explained by a single maximum stress value approach, but requires use of a critical volume in which the crack exists. In order to understand the effectiveness of this technique, this study investigated components of different notch geometry and varying levels of stress gradients. Two forms of weighting functions were employed to determine stress-intensity factors and results were compared to analytical exact methods. The results indicated that the “exponential” weighting function was superior to the “absolute” weighting function. An error band +/- 10% was met for cases ranging from a steep stress gradient in a sharp v-notch to the less severe stress transitions of a large circular notch. The incorporation of the proposed method has shown to be a worthwhile consideration.

Keywords: fracture mechanics, finite element method, stress intensity factor, stress gradient

Procedia PDF Downloads 113