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Fatigue Damage

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ISBN: 9783038426240 9783038426257 Year: Pages: VI, 204 DOI: 10.3390/books978-3-03842-625-7 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: General and Civil Engineering
Added to DOAB on : 2017-12-22 11:24:46
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There is an increasing acknowledgement in the engineering community that the response to this challenge, that is, prevention of catastrophic failure, generally requires a systems approach and necessitates engagement of a large pool of multidisciplinary expertise and the deployment of tools for systems analysis. This multidisciplinary pool includes materials science, structural analysis, manufacturing technologies, quality control and evaluation, mathematics, physics, and probability and reliability. Furthermore, from the scientific point of view, there is also an increasing acknowledgement that addressing the complex engineering problems of today requires the use of concepts and approaches that can account for size and time scaling effects. The Special Issue scope embraces interdisciplinary work aimed at understanding and deploying physics of fatigue and failure techniques, advancing experimental and theoretical failure analysis, modelling of the structural response with respect to both local and global failures, and structural design that accounts for scale and time effects in preventing engineering failures.

Keywords

Fatigue --- Design --- Crack growth --- Fracture

Fatigue in Multiple Sclerosis

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197637 Year: Pages: 87 DOI: 10.3389/978-2-88919-763-7 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Medicine (General)
Added to DOAB on : 2016-04-07 11:22:02
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Dear Readers,If you are engaged in the treatment of patients with MS (pwMS), this e-book’s aim is to offer novel insights to improve on an understanding of one of the major problems of pwMS: fatigue. Although there is increasing research into fatigue and its impact on MS, this collection of ten articles supports a better understanding of fatigue in MS patients. It explores pathophysiological concepts, provoking mechanisms, objective measurements, personality interactions, pharmacological and non-pharmacological interventions and summarizes clinical management. It is written by neurologists, psychologists, scientists and therapists and addresses this group of people, who deal with pwMS in private, clinical, rehabilitation or scientific settings. Its aim is to communicate high-quality information, knowledge and experience on MS to healthcare professionals, while providing global support for the international MS community.

Microstructural stability of nanostructured fcc metals during cyclic deformation and fatigue

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Book Series: Schriftenreihe des Instituts für Angewandte Materialien, Karlsruher Institut für Technologie ISSN: 21929963 ISBN: 9783866449183 Year: Volume: 9 Pages: XIV, 190 p. DOI: 10.5445/KSP/1000030072 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:58
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Nanostructured metals with maximal grain or twin sizes of less than 100 nm have advanced properties like increased strength.As beneficial as these microstructures can be for the strength of materials, they are not infinitely stable. During mechanical loading these metals tend to coarsen and lose their beneficial structure. Besides electron microscopic analysis of fatigued samples, in situ cycling tests were conducted in order to observe structural degradation during mechanical loading.

High Cycle Fatigue of Al and Cu Thin Films by a Novel High-Throughput Method

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Book Series: Schriftenreihe des Instituts für Angewandte Materialien, Karlsruher Institut für Technologie ISSN: 21929963 ISBN: 9783731500254 Year: Volume: 23 Pages: XII, 140 p. DOI: 10.5445/KSP/1000034759 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:01
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In the last two decades, the reliability of small electronic devices used in automotive or consumer electronics gained researchers attention. Thus, there is the need to understand the fatigue properties and damage mechanisms of thin films. In this thesis a novel high-throughput testing method for thin films on Si substrate is presented. The specialty of this method is to test one sample at different strain amplitudes at the same time and measure an entire lifetime curve with only one experiment.

Regulation of Endurance Performance: New Frontiers

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453290 Year: Pages: 246 DOI: 10.3389/978-2-88945-329-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Physiology
Added to DOAB on : 2018-02-27 16:16:45
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Successful endurance performance requires the integration of multiple physiological and psychological systems, working together to regulate exercise intensity in a way that will reduce time taken or increase work done. The systems that ultimately limit performance of the task are hotly contested, and may depend on a variety of factors including the type of task, the environment, external influences, training status of the individual and a host of psychological constructs. These factors can be studied in isolation, or inclusively as a whole-body or integrative system. A reductionist approach has traditionally been favoured, leading to a greater understanding and emphasis on muscle and cardiovascular physiology, but the role of the brain and how this integrates multiple systems is gaining momentum. However, these differing approaches may have led to false dichotomy, and now with better understanding of both fields, there is a need to bring these perspectives together. The divergent viewpoints of the limitations to human performance may have partly arisen because of the different exercise models studied. These can broadly be defined as open loop (where a fixed intensity is maintained until task disengagement), or closed loop (where a fixed distance is completed in the fastest time), which may involve whole-body or single-limb exercise. Closed loop exercise allows an analysis of how exercise intensity is self-regulated (i.e. pacing), and thus may better reflect the demands of competitive endurance performance. However, whilst this model can monitor changes in pacing, this is often at the expense of detecting subtle differences in the measured physiological or psychological variables of interest. Open loop exercise solves this issue, but is limited by its more restrictive exercise model. Nonetheless, much can be learnt from both experimental approaches when these constraints are recognised. Indeed, both models appear equally effective in examining changes in performance, and so the researcher should select the exercise model which can most appropriately test the study hypothesis. Given that a multitude of both internal (e.g. muscle fatigue, perception of effort, dietary intervention, pain etc.) and external (e.g. opponents, crowd presence, course topography, extrinsic reward etc.) factors likely contribute to exercise regulation and endurance performance, it may be that both models are required to gain a comprehensive understanding. Consequently, this research topic seeks to bring together papers on endurance performance from a variety of paradigms and exercise models, with the overarching aim of comparing, examining and integrating their findings to better understand how exercise is regulated and how this may (or may not) limit performance.

Keywords

Pacing --- Performance --- Fatigue --- Exercise --- Brain --- Muscle --- Running --- Cycling --- Triathlon --- Training

Redox Regulation in Skeletal Muscle Aging and Exercise

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451968 Year: Pages: 101 DOI: 10.3389/978-2-88945-196-8 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2017-10-13 14:57:01
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Skeletal muscle represents the largest organ of the human body and comprises about 40% of total body mass in humans. Even in people who ‘age well’, there is a noticeable loss of muscle strength and function that accelerates dramatically after the age of 60, a major factor in the reduction in life quality for the aging population. One of the most effective interventions to maintain muscle mass and function is through exercise. Skeletal muscle generates reactive oxygen and reactive nitrogen (ROS/RNS) species in response to muscle contractions. The concentration and species of ROS/RNS generated can depend on the age and fitness of the individual, muscle fibre type and the intensity of the muscle contractions. ROS/RNS generate unique signaling cascades that are not only essential in skeletal muscle contraction and adaptation but also play a role in a wide array of cell processes including cell proliferation, protein synthesis/degradation, immune response and antioxidant defense. ROS/RNS generated by contractions are involved in a co-ordinated local response that is tightly controlled at all levels from generation to detoxification. This collection of original articles and reviews highlights investigations that measure different aspects of the redox response of skeletal muscle to aging and exercise.

Neuroimmune Interface in Health and Diseases

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453788 Year: Pages: 174 DOI: 10.3389/978-2-88945-378-8 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Allergy and Immunology --- Neurology
Added to DOAB on : 2018-11-16 17:17:57
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It is now well appreciated that the immune system, in addition to its traditional role in defending the organism against pathogens, communicate in a well-organized fashion with the brain to maintain homeostasis and regulate a set of neural functions. Perturbation in this brain-immune interactions due to inflammatory responses may lead to psychiatric and neurological disorders. Microglia are one of the essential cells involved in the brain-immune interactions. Microglial cells are now not simply regarded as resident tissue macrophages in the brain. These cells are derived from myeloid progenitor cells in the yolk sac in early gestation, travel to the brain parenchyma and interact actively with neurons during the critical period of neurogenesis. Microglia provide a trophic support to developing neurons and take part in the neural wiring through the activity-dependent synapse elimination via direct neuron-microglia interactions. Altered microglial functions including changes in the gene expression due to early life inflammatory events or psychological and environmental stressors can be causally related to neurodevelopmental diseases and mental health disorders. This type of alterations in the neural functions can occur in the absence of infiltration of inflammatory cells in the brain parenchyma or leptomeninges. In this sense, the pathogenetic state underlying a significant part of psychiatric and neurological diseases may be similar to “para-inflammation”, an intermediate state between homeostatic and classical inflammatory states as defined by Ruslan Medzhitov (Nature 454:428-35, 2008). Therefore, it is important to study how systemic inflammation affects brain health and how local peripheral inflammation induces changes in the brain microenvironment. Chronic pain is also induced by disturbance in otherwise well-organized multisystem interplay comprising of reciprocal neural, endocrine and immune interactions. Especially, early-life insults including exposure to immune challenges can alter the neuroanatomical components of nociception, which induces altered pain response later in life. Recently the discrete roles of microglia and blood monocyte-derived macrophages are being defined. The distinction may be further highlighted by disorders in which the brain parenchymal tissue is damaged. Therefore, studies investigating the dynamics of immune cells in traumatic brain injury and neurotropic viral infections including human immunodeficiency virus, etc. as well as neurodegenerative diseases such as amyotrophic lateral sclerosis are promising to clarify the interplay between the central nervous and immune systems. The understanding of the histological architecture providing the infrastructure of such neuro-immune interplay is also essential. This Frontiers research topic brings together fourteen articles and aims to create a platform for researchers in the field of psychoneuroimmunology to share the recent theories, hypotheses and future perspectives regarding open questions on the mechanisms of cell-cell interactions with chemical mediators among the nervous, immune and endocrine systems. We hope that this platform would reveal the relevance of the studies on multisystem interactions to enhance the understanding of the mechanisms underlying a wide variety of neurological and psychiatric disorders.

Consideration of runouts by the evaluation of fatigue experiments

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Book Series: Berichte zum Stahl- und Leichtbau / Karlsruher Institut für Technologie, Versuchsanstalt für Stahl, Holz und Steine, Stahl- und Leichtbau ISSN: 21987912 ISBN: 9783731509004 Year: Volume: 8 Pages: XVI, 189 p. DOI: 10.5445/KSP/1000091208 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 19:59:17
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In EC3, the fatigue life of a steel structure subjected to a cyclic load is estimated by its detail category. This category is based on the S-N, curves which are obtained by applying the Basquin model. Statistically, this model does not allow extrapolating the S-N curves in the HCF region, neither does it consider the runouts. This affects the fatigue life estimation when a structure bears loading in HCF. To overcome these deficiencies, a new method based on a Weibull distribution is applied.

Fatigue crack detection on structural steel members by using ultrasound excited thermography = Erkennung von Ermüdungsrissen in Stahlbauteilen durch ultraschallangeregte Thermografie

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Book Series: Berichte zum Stahl- und Leichtbau / Karlsruher Institut für Technologie, Versuchsanstalt für Stahl, Holz und Steine, Stahl- und Leichtbau ISSN: 21987912 ISBN: 9783731504177 Year: Volume: 3 Pages: XVI, 334 p. DOI: 10.5445/KSP/1000048191 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 19:59:17
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Ultrasound excitation of structural steel members leads to localised energy dissipation at existent fatigue cracks and thus allows for thermographic flaw detection. Essential effects on the defect-selective heating, such as flaw size, plate thickness, crack mouth opening or static preload, are systematically investigated. Laser vibrometry measurements of the crack edges, theoretical modelling of frictional heating and numerical simulations contribute to the understanding of the involved physics.

Ein Prognosemodell für die Verwitterung von Sandstein

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Book Series: Karlsruher Reihe Massivbau, Baustofftechnologie, Materialprüfung / Institut für Massivbau und Baustofftechnologie ; Materialprüfungs- und Forschungsanstalt Karlsruhe ISSN: 1869912X ISBN: 9783731505204 Year: Volume: 79 Pages: Getr. Zählung DOI: 10.5445/KSP/1000054324 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: General and Civil Engineering
Added to DOAB on : 2019-07-30 20:02:02
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Sandstone is the most common kind of natural stone used for historic buildings in Central Europe. During the past century a dramatic increase in different types of damage to historic buildings, monuments and sculptures made from natural stone has been observed. The present work deals with theoretical aspects of strength loss, fracture processes and degradation during the decay processes.

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