995 resultados para Mental fatigue.
Resumo:
Thermal cutting methods, are commonly used in the manufacture of metal parts. Thermal cutting processes separate materials by using heat. The process can be done with or without a stream of cutting oxygen. Common processes are Oxygen, plasma and laser cutting. It depends on the application and material which cutting method is used. Numerically-controlled thermal cutting is a cost-effective way of prefabricating components. One design aim is to minimize the number of work steps in order to increase competitiveness. This has resulted in the holes and openings in plate parts manufactured today being made using thermal cutting methods. This is a problem from the fatigue life perspective because there is local detail in the as-welded state that causes a rise in stress in a local area of the plate. In a case where the static utilization of a net section is full used, the calculated linear local stresses and stress ranges are often over 2 times the material yield strength. The shakedown criteria are exceeded. Fatigue life assessment of flame-cut details is commonly based on the nominal stress method. For welded details, design standards and instructions provide more accurate and flexible methods, e.g. a hot-spot method, but these methods are not universally applied to flame cut edges. Some of the fatigue tests of flame cut edges in the laboratory indicated that fatigue life estimations based on the standard nominal stress method can give quite a conservative fatigue life estimate in cases where a high notch factor was present. This is an undesirable phenomenon and it limits the potential for minimizing structure size and total costs. A new calculation method is introduced to improve the accuracy of the theoretical fatigue life prediction method of a flame cut edge with a high stress concentration factor. Simple equations were derived by using laboratory fatigue test results, which are published in this work. The proposed method is called the modified FAT method (FATmod). The method takes into account the residual stress state, surface quality, material strength class and true stress ratio in the critical place.
Resumo:
In this study, finite element analyses and experimental tests are carried out in order to investigate the effect of loading type and symmetry on the fatigue strength of three different non-load carrying welded joints. The current codes and recommendations do not give explicit instructions how to consider degree of bending in loading and the effect of symmetry in the fatigue assessment of welded joints. The fatigue assessment is done by using effective notch stress method and linear elastic fracture mechanics. Transverse attachment and cover plate joints are analyzed by using 2D plane strain element models in FEMAP/NxNastran and Franc2D software and longitudinal gusset case is analyzed by using solid element models in Abaqus and Abaqus/XFEM software. By means of the evaluated effective notch stress range and stress intensity factor range, the nominal fatigue strength is assessed. Experimental tests consist of the fatigue tests of transverse attachment joints with total amount of 12 specimens. In the tests, the effect of both loading type and symmetry on the fatigue strength is studied. Finite element analyses showed that the fatigue strength of asymmetric joint is higher in tensile loading and the fatigue strength of symmetric joint is higher in bending loading in terms of nominal and hot spot stress methods. Linear elastic fracture mechanics indicated that bending reduces stress intensity factors when the crack size is relatively large since the normal stress decreases at the crack tip due to the stress gradient. Under tensile loading, experimental tests corresponded with finite element analyzes. Still, the fatigue tested joints subjected to bending showed the bending increased the fatigue strength of non-load carrying welded joints and the fatigue test results did not fully agree with the fatigue assessment. According to the results, it can be concluded that in tensile loading, the symmetry of joint distinctly affects on the fatigue strength. The fatigue life assessment of bending loaded joints is challenging since it depends on whether the crack initiation or propagation is predominant.
Resumo:
O objetivo da palestra foi o de apresentar um apanhado sucinto da história das investigações sobre conceitos nas últimas décadas, com isso contribuindo para a divulgação da Ciência Cognitiva. O episódio central dessa história é a guinada resultante das pesquisas realizadas por Eleonor Rosch e outros a partir do inicio dos anos setenta. Estas pesquisas colocam em cheque a CONCEPÇÃO CLÁSSICA DE CONCEITOS (caracterizada na primeira parte da exposição). O fato de que o abandono da concepção clássica não é uma alternativa viável, dá origem ao que chamamos de PROBLEMA DA CONCILIAÇÃO, ou seja, o de compatibilizar a concepção clássica com as descobertas modernas. A apresentação se encerra com algumas sugestões para a solução do problema.
Resumo:
Investigaremos, a partir da perspectiva da Ciência Cognitiva, a noção de representação mental, no domínio da percepção visual humana. Ênfase é dada ao paradigma Conexionista, ou de Redes Neurais, de acordo com o qual tais representações mentais são descritas como estruturas emergentes da interação entre sistemas de processamento de informação que se auto-organizam - tais como o cérebro - e a luz estruturada no meio ambiente. Sugerimos que essa noção de representação mental indica uma solução para uma antiga polêmica, entre Representacionalistas e Eliminativistas, acerca da existência de representações mentais no sistema perceptual humano.
Resumo:
Raciocinando no contexto do programa neomecanicista para a Biologia, estudamos a natureza do processamento de informação no sistema vivo em geral, e no cérebro humano em particular, onde uma aplicação do modelo da Auto-Organização nos conduz à hipótese do "Supercódigo". Este seria um programa mental, molecularmente codificado, responsável pelas competências inatas, como a competência lingüística. Fazemos também uma comparação entre nossa hipótese e a da Linguagem do Pensamento, proposta por Jerry Fodor.
Resumo:
ABSTRACT: The mental models theory predicts that, while conjunctions are easier than disjunctions for individuals, when denied, conjunctions are harder than disjunctions. Khemlani, Orenes, and Johnson-Laird proved that this prediction is correct in their work of 2014. In this paper, I analyze their results in order to check whether or not they really affect the mental logic theory. My conclusion is that, although Khemlani et al.'s study provides important findings, such findings do not necessarily lead to questioning or to rejecting the mental logic theory.
Resumo:
Diplomityössä tutkitaan hitsatun duplex-teräksen, laatu: EN 1.4462 (Outokumpu laatu 2205) väsymislujuutta. Tutkimusmetodologia noudattaa sekä kokeellisia että laskennallisia menetelmiä. Kokeelliset menetelmät sisältävät hitsatun teräksen väsytystestaukset laboratoriossa, hitsausten jälkikäsittelyt (HiFIT) sekä perusaineelle ja hitseille tehtävät metallurgiset tutkimukset. Väsytyskokeista saatavia tuloksia verrataan kansainvälisen hitsausinstituutin (IIW) vahvistamiin rakennekohtaisiin standardeihin sekä kirjallisuudessa esiintyviin tutkimustuloksiin. Laskennalliset menetelmät sisältävät vertailulaskelmia tehollisen lovijännityksen (ENS) menetelmää hyödyntäen. Tehollisen lovijännityksen menetelmässä liitoksissa vaikuttavat teholliset lovijännitykset selvitetään elementtimenetelmän (FEM) avulla. Tulokset vahvistavat, että hitsauksella ja hitsausten jälkikäsittelyllä on suuri merkitys rakenteen kestoikään. Suurin osa väsytyskokeiden tuloksista osoitti parempia väsymiskestävyyden arvoja kuin rakennekohtaiset standardit, mutta liitosten liitosvirheiden todettiin heikentävän väsytyskestävyyttä. Jälkikäsittelyiden todettiin parantavan liitosten väsymiskestävyyden tuloksia ja todettiin tulosten olevan hyödynnettävissä mitoituksessa.
Resumo:
[Traditions. Asie. Arménie]
Resumo:
N/A
Resumo:
The purpose of this qualitative study was to understand the client and occupational therapist experiences of a mental health group. A secondary aim was to explore the extent to which this group seemed to have reflected a client-centred approach. The topic emerged from personal and professional issues related to the therapist as teacher and to inconsistencies in practice with the profession's client-centred philosophy. This philosophy, the study's frame of reference, was established in terms of themes related to the client-therapist relationship and to client values. Typical practice was illustrated through an extensive literature review. Structured didacticexperiential methods aiming toward skill development were predominant. The interpretive sciences and, to a lesser extent, the critical sciences directed the methodology. An ongoing support group at a community mental health clinic was selected as the focus of the study; the occupational therapist leader and three members became the key participants. A series of conversational interviews, the . core method of data collection, was supplemented by observation, document review, further interviews, and fieldnotes. Transcriptions of conversations were returned to participants for verification and for further reflection. Analysis primarily consisted of coding and organizing data according to emerging themes. The participants' experiences of group, presented as narrative stories within a group session vignette, were also returned to participants. There was a common understanding of the group's structure and the importance of having "air time" within the group; however, differences in perceptions of such things as the importance of the group in members' lives were noted. All members valued the therapeutic aspects of group, the role of group as weekly activity and, to a lesser extent, the learning that came from group. The researcher's perspective provided a critique of the group experience from a client-centred perspective. Some areas of consistency with client-centred practice were noted (e.g., therapist attitudes); however the group seemed to function far from a client-centred ideal. Members held little authority in a relationship dominated by the leaders, and leader agendas rather than member values controlled the session. Possible reasons for this discrepancy ranging from past health care encounters through to co-leader discord emerged. The actual and potential significance of this study was discussed according to many areas of implications: to OT practice, especially client-centred group practice, to theory development, to further areas of research and methodology considerations, to people involved in the group and to my personal growth and development.
Resumo:
The current study was an exploration of why some novices are more successful than their peers when learning from the Internet by examining the relations among time spent with relevant information and changes in invested mental effort during Internet navigations as well as achievement. Navigation behaviours and learner characteristics were investigated as predictors of time spent with relevant information and changes in mental effort. Undergraduates (N = 85, Mage = 20 years, 5 months) searched the Internet for information corresponding to a low knowledge topic for 20 min while their eye gaze and pupil size were recorded. Pupil diameter was used as an objective, continuous measure of mental effort. Participants also completed questionnaires or computer tasks pertaining to s e l f-regulated learning characteristics (general intrinsic goal orientation and effort regulation) and cognitive factors (working memory control, distractibility and cognitive style). All analyses controlled for general mental ability, reading comprehension, topic and Internet knowledge, and overall motivation. A greater proportion of time spent with relevant information predicted higher scores on an achievement test. Interestingly, time spent with relevant information partially mediated the positive relation between the frequency of increases in invested mental effort and achievement. Surprisingly, intrinsic goal orientation was negatively related to time spent with relevant information and effort regulation was negatively related to the frequency of increases in invested mental effort. These findings have implications for supports when novices guide their own learning, especially when using the Internet.
Resumo:
The phenomenon of over-recovery consists of a participant’s maximal force levels returning to values above initial levels. The present study examined the presence and causes of over-recovery following local muscular fatigue. Fourteen males completed two fatigue protocols consisting of maximal isometric dorsiflexion contractions. Upon completion of the fatigue protocol participants’ force was monitored over a 15 minute recovery period. Dorsiflexion force and surface electromyography (sEMG) from the tibialis anterior and soleus were monitored concurrently. Following the two fatigue conditions (10 and 20% force decrement) force recovered to 100.5 and 99.5% of initial levels for each condition, respectively. Surface EMG root-mean-square amplitude and MPF exhibited changes consistent with a warm-up effect. It was concluded that over-recovery was not present in the tibialis anterior following a local muscular fatigue. However, the return in force to initial values, rather than a persistent decrement as normally observed, was mediated by the warm-up effect.
Resumo:
This is a mixed methodology study that uses an autoethnographic approach to combine both an autobiography and a survey of practitioners who work in children’s mental health. It is largely about the implementation of Evidence-Based Practice (EBP), and the questions, concerns, experiences that I have had, and compared them with those of my fellow practitioners. In addition, it is about my journey as a mental health professional, and how I have come to recognize that in order to achieve the goals I wanted to achieve, I needed to return to university to pursue a Master’s degree. Within the research, I identify and discuss different definitions of EBP and identify several themes. I deconstruct the implementation of EBPs through the lens of Foucault and his notions of governmentality. I offer policy and practice recommendations to improve the implementation of EBP and the services received by children facing mental health issues.