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| Registros recuperados: 19 | |
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| Davies, Peter; Francois, M; Lacotte, Nicolas; Vu, Thanh Do; Durville, Damien. |
| Repeated bending over sheaves is one of the main causes of failure of synthetic fibre ropes used in marine operations. There are few published results available and even fewer models allowing lifetime to be estimated. A large new set of data from cyclic bend over sheave (CBOS) tests on 250 kN break load braided HMPE synthetic ropes is presented first, both tests to failure and interrupted tests followed by residual strength measurements. These data are analysed in order to propose an empirical lifetime model. This is identified using constant load tests, then evaluated for variable load sequences. A methodology to include rope lifetime prediction in handling system design is then discussed. |
| Tipo: Text |
Palavras-chave: Fibre rope; Bending; Sheave; Abrasion; Fatigue. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00251/36215/34775.pdf |
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| Kunstetter,A.C.; Wanner,S.P.; Madeira,L.G.; Wilke,C.F.; Rodrigues,L.O.C.; Lima,N.R.V.. |
| There is evidence that brain temperature (Tbrain) provides a more sensitive index than other core body temperatures in determining physical performance. However, no study has addressed whether the association between performance and increases in Tbrain in a temperate environment is dependent upon exercise intensity, and this was the primary aim of the present study. Adult male Wistar rats were subjected to constant exercise at three different speeds (18, 21, and 24 m/min) until the onset of volitional fatigue. Tbrain was continuously measured by a thermistor inserted through a brain guide cannula. Exercise induced a speed-dependent increase in Tbrain, with the fastest speed associated with a higher rate of Tbrain increase. Rats subjected to constant... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Brain cortex; Fatigue; Hyperthermia; Speed; Thermoregulation; Treadmill running.. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2014000800679 |
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| Kishtwaria, Jatinder; Rana, Aruna; Awasthi, Kumud; Lata, Suman. |
| The present study was conducted in Kangra district of Himachal Pradesh (India) to study the physiological workload of respondents engaged in plucking tea leaves and identify the major causes and consequences of physiological stress. Majority of the respondents had ectomorph body with average physical fitness. During plucking tea leaves, the body of women workers deviate from natural alignment due to varying height of tea bushes. Hence, a continuous awkward standing posture, adverse environment and working conditions increase drudgery and decrease productivity of women workers. The change in environment temperature caused significantly higher physiological stress to the workers. At average working heart rate values during complete cycle of plucking, the... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Drudgery; Cardiac cost; Physiological stress; Fatigue; Workload; Labor and Human Capital. |
| Ano: 2004 |
URL: http://purl.umn.edu/9317 |
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| Lechat, Céline. |
| Faced with the need to exploit off-shore oil fields at ever increasing depths, lighter replacements are being considered for the standard steel cable mooring systems used for platforms. This study considers the mechanical behaviour of synthetic ropes made of two different materials: PET and PEN. The first is already used in ropes to replace steel, and the second could be a potential competitor. A multi-scale study, involving mechanical tests (mainly tensile, creep and cyclic loading) has been carried out on assemblies of various sizes, from ropes of several hundreds kN breaking load to their smallest components: filaments. Strong correlations were found between the quasi-static behaviour of assemblies and the behaviour of filaments, which in itself is... |
| Tipo: Text |
Palavras-chave: Failure; Fatigue; Creep; Tensile loading; Rope; Yarn; Fibre; PEN; PET; Rupture; Fatigue; Fluage; Traction; Câble; Yarn; Fibre; PEN; PET. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/these-4312.pdf |
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| Battaglini,C.L.; Mihalik,J.P.; Bottaro,M.; Dennehy,C.; Petschauer,M.A.; Hairston,L.S.; Shields,E.W.. |
| The purpose of this study was to examine the effects of an exercise intervention on the total caloric intake (TCI) of breast cancer patients undergoing treatment. A secondary purpose was to determine whether or not a relationship existed between changes in TCI, body fat composition (%BF), and fatigue during the study, which lasted 6 months. Twenty females recently diagnosed with breast cancer, scheduled to undergo chemotherapy or radiation, were assigned randomly to an experimental (N = 10) or control group (N = 10). Outcome measures included TCI (3-day food diary), %BF (skinfolds), and fatigue (revised Piper Fatigue Scale). Each exercise session was conducted as follows: initial cardiovascular activity (6-12 min), followed by stretching (5-10 min),... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Exercise; Breast cancer; Caloric intake; Fatigue; Body composition. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008000800012 |
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| Davies, Peter; Verbouwe, W.. |
| Basalt fibres offer potential for use in marine structures, but few data exist to evaluate the influence of seawater immersion on their mechanical behaviour. This paper provides the results from a study in which basalt fibre reinforced epoxy composites were aged in natural seawater at different temperatures. Tests were performed under quasi-static and cyclic loading, first in the as-received state then after saturation in natural seawater. Results are compared to those for an E-glass reinforced composite with the same epoxy matrix. They indicate similar mechanical performance for both materials after seawater saturation. |
| Tipo: Text |
Palavras-chave: Seawater; Aging; Fatigue; Basalt fibre; Epoxy; Unidirectional; Flexure. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00392/50385/51111.pdf |
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| Davies, Peter; Germain, Gregory; Gaurier, Benoit; Boisseau, Amelie; Perreux, Dominique. |
| The long term reliability of tidal turbines is critical if these structures are to be cost-effective. Optimised design requires a combination of material durability models and structural analyses. Composites are a natural choice for turbine blades but there are few data available to predict material behaviour under coupled environmental and cycling loading. This paper addresses this problem, by introducing a multi-level framework for turbine blade qualification. At the material scale static and cyclic tests have been performed, both in air and in seawater. The influence of ageing in seawater on fatigue performance is then quantified and much lower fatigue lives are measured after ageing. At a higher level flume tank tests have been performed on three-blade... |
| Tipo: Text |
Palavras-chave: Composite; Fatigue; Ageing; Tidal turbine; Flume tank; Finite-element model. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00079/19053/20068.pdf |
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| Le Gac, Pierre-yves; Arhant, Mael; Davies, Peter; Muhr, Alan. |
| Natural rubber has been successfully used in a marine environment for many years. However, most applications involve low dynamic loadings. Due to the emergence of marine energy recovery, wave and tidal energy converters are being developed. In some such devices, rubbers are subjected to severe cyclic loadings, very different from their previous use in air or water. Such rubbers must therefore be qualified for long-term use in sea water with high fatigue loading. This paper presents a study using a new fatigue machine that allows the fatigue behaviour of rubber in sea water to be compared to that in air. The results show that the benefit of non-relaxing conditions on fatigue lifetime of natural rubber can be significantly reduced when it is used in sea... |
| Tipo: Text |
Palavras-chave: Natural Rubber; Water; Fatigue; Stabilisation. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00211/32240/32195.pdf |
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| Davies, Peter; Arhant, Mael. |
| The recent introduction of liquid acrylic thermoplastic matrix resins which can impregnate fibre reinforcements using traditional infusion moulding offers significant potential for future composite structures in marine applications, such as marine energy devices. However, to date very few results are available to evaluate the long term durability of these composites in a marine environment. This paper describes results from a series of cyclic loading tests on glass and carbon fibre reinforced acrylic composites under both tension and four point flexural loading. Tests were performed before and after aging in natural seawater. The results were compared to results for a glass/epoxy used today in marine structures, and show a lower loss of both static and... |
| Tipo: Text |
Palavras-chave: Acrylic; Fatigue; Immersion; Seawater. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00444/55596/57249.pdf |
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| Goulart,F.O.; Godke,B.A.; Borges,V.; Azevedo-Silva,S.M.C.; Mendes,M.F.; Cendoroglo,M.S.; Ferraz,H.B.. |
| We evaluated the frequency of fatigue in geriatric patients with and without Parkinson's disease (PD) and correlated it with depression and excessive daytime sleepiness. We evaluated 100 patients from Hospital São Paulo, 50 with PD from the Neurologic Outpatient Clinic and 50 with non-neurologic diseases or oncologic diseases from the Geriatric Outpatient Clinic (controls). All patients who scored 28 or more on the Fatigue Severity Scale (FSS) were considered to have fatigue. Also, all patients were submitted to a structured interview to diagnose depression by the criteria of the American Psychiatric Association (DSM-IV, 4th version) and were evaluated by the Modified Impact of Fatigue Scale and the Epworth Sleepiness Scale (ESE) to detect excessive... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Parkinson's disease; Fatigue; Depression; Excessive daytime sleepiness. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2009000800014 |
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| Chevillotte, Yoan; Marco, Yann; Bles, Guilhem; Devos, Karel; Keryer, Mathieu; Arhant, Mael; Davies, Peter. |
| This paper describes a study of the fatigue characterization of polyamide mooring ropes for floating wind turbines. Under some conditions polyester ropes, which are favoured for offshore oil and gas platform station-keeping, are too stiff for wind turbine moorings, and polyamide may be a suitable alternative. While early studies on fatigue of braided nylon ropes showed very short lifetimes some recent results have indicated that it is possible to significantly enhance lifetime by modifying rope construction and improving fibre coatings. In this paper yarn-on-yarn abrasion testing is used first to evaluate a new yarn coating. Significant lifetime enhancement was noted, so fatigue testing of ropes was then performed. Results confirm that excellent fatigue... |
| Tipo: Text |
Palavras-chave: Fatigue; Rope; Nylon; Mooring; Water; Floating wind turbine. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00607/71884/70609.pdf |
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| Ulu, K. Narynbek; Huneau, B.; Le Gac, Pierre-yves; Verron, E.. |
| Fatigue properties of filled natural rubber in seawater environment are investigated by uniaxial fatigue and crack propagation experiments, and the damage is analyzed by scanning electron microscopy. The behavior under relaxing and non-relaxing loading conditions is studied and the results are compared to those obtained in air environment. For relaxing loading conditions, fatigue behavior is the same in both environments. Under non-relaxing conditions at large strain levels, for which the influence of strain-induced crystallization is important, fatigue life is longer in seawater. Such behavior could be explained by increased internal temperatures of specimens tested in air due to lower heat conductivity of air as compared to seawater. Such conclusion is... |
| Tipo: Text |
Palavras-chave: Natural rubber; Fatigue; Environmental effects; Seawater; Strain-induced crystallization. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00324/43523/43055.pdf |
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| Fábregas,Bruno Cópio; Ávila,Renata Eliane de; Faria,Marjore Novaes; Moura,Alexandre Sampaio; Carmo,Ricardo Andrade; Teixeira,Antonio Lúcio. |
| INTRODUCTION: Chronic hepatitis C virus infection patients have higher rates of psychiatric disorders than the general population. Chronic hepatitis C virus infection is known to be associated with impaired health related quality of life. To our knowledge, there is no previous research of health related quality of life in chronic hepatitis C patients that combined structured psychiatric interview and careful psychopathological evaluation, including depression, anxiety and fatigue instruments. The aim of this study was to evaluate health related quality of life of chronic hepatitis C patients and to investigate the association with sociodemographic, psychopathological and psychiatric factors. MATERIALS AND METHODS: Eighty-one individuals with chronic... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Quality of life; WHOQOL-BREF; Hepatitis C; Depression; Fatigue. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-86702013000600002 |
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| Rodrigues,L.O.C.; Oliveira,A.; Lima,N.R.V.; Machado-Moreira,C.A.. |
| Thermal environmental stress can anticipate acute fatigue during exercise at a fixed intensity (%VO2max). Controversy exists about whether this anticipation is caused by the absolute internal temperature (Tint, ºC), by the heat storage rate (HSR, cal/min) or by both mechanisms. The aim of the present study was to study acute fatigue (total exercise time, TET) during thermal stress by determining Tint and HSR from abdominal temperature. Thermal environmental stress was controlled in an environmental chamber and determined as wet bulb globe temperature (ºC), with three environmental temperatures being studied: cold (18ºC), thermoneutral (23.1ºC) or hot (29.4ºC). Six untrained male Wistar rats weighing 260-360 g were used. The animals were submitted to... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Thermoregulation; Exercise; Fatigue; Heat storage rate. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000100018 |
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| Christoforo,André L.; Barbosa,Thaina Q.; Almeida,Diego H. de; Panzera,Tulio H.; Lahr,Francisco A. R.. |
| ABSTRACT This research aimed to evaluate the effect of the number of fatigue cycles (NC, 0 – reference, 450, 4500, 45000, and 90000) for frequencies (Fr) of oscillation equal to 0.5 and 1.0 Hz on the modulus of elasticity (Em) and operating stress (σm) in the static bending of Pinus caribaea wood. Em and σm were determined taking into account three specimens (SPEC) manufactured for reference condition and another three for each of the four NC levels and each Fr level, resulting in 27 SPEC. Sixty experimental determinations were obtained, being the approximate total time of sample exposure to fatigue of 350 hours. The same specimens used to determine Em and σm for the reference condition were also used (via non-destructive tests) to obtain these properties... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Fatigue; Pinus caribaea; Static bending; Analysis of variance; Regression models. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162020000200238 |
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| Olagnon, Michel; Guede, Zakoua. |
| This paper provides theoretical formulas to calculate conservative estimates of the rainflow fatigue damage from the spectral parameters for spectra composed of the combination of one or several narrow-band low-frequency loads and a higher frequency one, such as are often encountered with moored marine structures. With respect to the semi-empirical formulas that have been proposed by other authors, those presented here are theoretically constructed from the mathematical definition of rainflow and from the statistical properties of Gaussian processes. (C) 2008 Elsevier Ltd. All rights reserved. |
| Tipo: Text |
Palavras-chave: Random loading; Rainflow; Spectral fatigue; Fatigue. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4197.pdf |
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| Moreira,N.C.V.; Damasceno,R.S.; Medeiros,C.A.M.; de Bruin,P.F.C.; Teixeira,C.A.C.; Horta,W.G.; de Bruin,V.M.S.. |
| We have tested the hypothesis that restless leg syndrome (RLS) is related to quality of sleep, fatigue and clinical disability in multiple sclerosis (MS). The diagnosis of RLS used the four minimum criteria defined by the International Restless Legs Syndrome Study Group. Fatigue was assessed by the Fatigue Severity Scale (FSS >27), quality of sleep by the Pittsburgh Sleep Quality Index (PSQI >6), excessive daytime sleepiness by the Epworth Sleepiness Scale (ESS >10) and clinical disability by the Expanded Disability Status Scale (EDSS). Forty-four patients (32 women) aged 14 to 64 years (43 ± 14) with disease from 0.4 to 23 years (6.7 ± 5.9) were evaluated. Thirty-five were classified as relapsing-remitting, 5 as primary progressive and 4 as... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Restless leg syndrome; Multiple sclerosis; Sleep; Fatigue; Pittsburgh Sleep Quality Index. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2008001000017 |
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| Cardozo,A.C.; Gonçalves,M.; Gauglitz,A.C.F.. |
| The aim of the present study was to assess the spectral behavior of the erector spinae muscle during isometric contractions performed before and after a dynamic manual load-lifting test carried out by the trunk in order to determine the capacity of muscle to perform this task. Nine healthy female students participated in the experiment. Their average age, height, and body mass (± SD) were 20 ± 1 years, 1.6 ± 0.03 m, and 53 ± 4 kg, respectively. The development of muscle fatigue was assessed by spectral analysis (median frequency) and root mean square with time. The test consisted of repeated bending movements from the trunk, starting from a 45º angle of flexion, with the application of approximately 15, 25 and 50% of maximum individual load, to the stand... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Electromyography; Spectral analysis; Root mean square; Load lifting; Fatigue. |
| Ano: 2004 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004000700018 |
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| Registros recuperados: 19 | |
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