Search results for " STRESS"
showing 10 items of 3936 documents
A COMPARISON BETWEEN COMBUSTION PHASE INDICATORS FOR OPTIMAL SPARK TIMING
2008
The closed-loop control of internal combustion engine spark timing may be accomplished by means of a combustion phase indicator, i.e., a parameter, derived from in-cylinder pressure analysis, whose variation is mainly referable to combustion phase shift and assumes a fixed reference value under optimal spark timing operation. The aim of the present work is a comparison between different combustion phase indicators, focusing on the performance attainable by a feedback spark timing control, which uses the indicator as pilot variable. An extensive experimental investigation has been carried out, verifying the relationship between indicators’ optimal values and the main engine running parameter…
Magnetorheology for suspensions of solid particles dispersed in ferrofluids
2006
In this work, the magnetorheological properties of suspensions of micron-sized iron particles dispersed in magnetite ferrofluids were studied. With this aim, the flow properties of the suspensions in the steady-state regime were investigated using a commercial magnetorheometer with a parallel-plate measuring cell. The effect of both magnetite and iron concentration on the magnitude of the yield stress was studied for a broad range of magnetic fields. In addition, the experimental values of the yield stress were compared with the predictions from the chain model. With this purpose the values of the yield stress were obtained by means of finite element calculations. Interestingly, it was foun…
On the mechanisms involved in the tensile strength of a dissimilar Ti6Al4V/316L laser welded assembly
2021
International audience; The aim of the present work is to analyze the thermomechanical behavior of dissimilar laser seams by means of FE modeling. The case of a Ti6Al4V/316L assembly with vanadium insert was considered. Effective mechanical properties of the main materials and cords were first estimated from NHT measurements. Modeling of the double pass laser welding process was performed first by considering shrinking of the two weld seams during manufacturing, to get the residual stress state in the welded assembly. Modeling of the tensile test was performed in a second step to study the assembly behavior during loading. In these modeling results, the mesh was the cross-section of the mic…
Impact of Superfinish Turning on Surface Integrity of Pure Copper
2011
Abstract The presented study deals with comprehension of relationships between machining cutting conditions and physical-chemical properties linked with surface integrity. A multi-physics model is presented to calculate residual stress, temperature and dislocation fields in the machined material. This model includes both thermal-mechanical, structural evolution and dynamic recristallisation approaches. The model was applied to pure copper after superfinish turning. Good agreement was found between numerical values and experimental ones. This paper also presents a work on the impact of mechanical and microstructural changes induced by machining on the electrochemical behaviour and corrosion …
Experimental and numerical study of composite T-joints for marine application
2010
Abstract The aim of this work was to study the behaviour of composite T-joints used in marine applications. The effect of several parameters was investigated. In particular, three configurations were studied; i.e. with adhesive and with two different over-laminations. Moreover, the joined sections were made of different materials. These joints were subjected to a tensile load in the plane of the sheet. To quantify the effect of different designs on the strength, a variance analysis was performed. Finally, a numerical model was developed using a commercial finite element code (Ansys).
Factors Contributing to Different Agency in Work and Study
2013
Most young adults today are following longer educational tracks and postpone entrance into the workforce. This 2-year study aimed to determine factors contributing to occupational self-efficacy in a representative sample of n = 1,891 young adults ( M = 23.92, SD = 2.17 years) with different work statuses (studying, in an apprenticeship, employed, or unemployed). Occupational identity, perceived work quality, the ability to cope with work stress, and symptomatology were assessed. Path analyses revealed that work status was the most important predictor of later occupational self-efficacy, with employment showing the strongest prediction of later agency in the professional domain. Ruminative e…
Knowledge Management of Work Stress in Mexican Manufacturing Environments
2018
This chapter presents a knowledge management perspective to propose a pair of structural models to determine the relationship between burnout syndrome (BS) and body mass index (BMI) among high and middle managers of Mexican maquiladoras. In developing countries like Mexico there are opportunities to expand burnout study on diversity of contexts and occupations. The Maslach burnout general inventory questionnaire (MB-GI) was used, and sociodemographic data were collected as well as the weight and size of respondents. Instrument shows an acceptable reliability index. Structural equation models are used to determine relationship among variables. From a sample of 361 people, using segmentations…
Work related stress and well-being: the roles of direct action coping and palliative coping
2006
The purpose of the present study is to analyze the roles of direct action coping and palliative coping in the relationship between work stressors and psychological well-being, as well as their possible interactions, in a sample of 464 bank employees. Hierarchical regression analyses showed main effects of direct action coping on well-being. Palliative coping predicts higher levels of psychological distress. Contrary to what was expected, the interactions between work stressors and direct action coping were not significant. Palliative coping interacted with work stressors when predicting psychosomatic complaints. The interaction between the two types of coping was significant on psychosomati…
Respuestas psicobiológicas en profesores al inicio y al final de un curso académico
2013
La evidencia científica indica que el estrés laboral incrementa el riesgo de enfermedad cardiovascular. Las respuestas emocionales, cardiovasculares y endocrinas se ven afectadas por la experiencia diaria. La percepción de estrés, el estado de ánimo negativo, la frecuencia cardíaca (FC) y la presión arterial (PA) incrementan en los periodos laborales. La respuesta del cortisol (C) no es tan clara, existiendo resultados contradictorios. El objetivo de este trabajo es analizar en profesores los marcadores de estrés durante dos jornadas laborales. Además se evaluó el papel del género en la respuesta de estrés en 49 profesores. Para ello, se midió la percepción de estrés, el estado de ánimo, la…
Model of psychosocial intervention in organizations opposed to job stress: operational strategy
2009
Artículos originales [ES] El artículo presenta un modelo de actuación frente a los factores de riesgo psicosociales derivados del estrés laboral. Primeramente relaciona los principales efectos que ocasiona en toda organización el estrés laboral. Al mismo tiempo establece sus prioridades de actuación, para acto seguido indicar las actividades que deben ejecutarse. Dentro de esta fase de actuación, diferencia aquellas que van dirigidas a la organización de forma colectiva, cuya prioridad es manifiesta, frente a las acciones que deben ofrecerse a los afectados de forma individualizada. Así pues, se trata de un modelo de intervención que interactúa tanto en las medidas organizativas generales c…