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Auswahl der wissenschaftlichen Literatur zum Thema „Deterioration behavior“
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Zeitschriftenartikel zum Thema "Deterioration behavior"
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Scholl, M., P. Clayton und Y. Jia. „Deterioration behavior of thermomechanical refiner plates“. Wear 203-204 (März 1997): 65–76. http://dx.doi.org/10.1016/s0043-1648(96)07409-1.
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Mc Kelvie, Stuart J. „Drivers' Behavior at Stop Signs: A Deterioration“. Perceptual and Motor Skills 64, Nr. 1 (Februar 1987): 252–54. http://dx.doi.org/10.2466/pms.1987.64.1.252.
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In a 1985 observational study of 176 private car drivers at stop signs in eight locations in a town setting in Quebec, 42% came to a complete stop, 43% slowed, and 15% did not stop or slow. Relative to previous years (1979 to 1983), these data show a general deterioration in performance that cannot be accounted for by changes in the density of traffic. Further analyses showed that most of the 1985 decline in performance occurred in the absence of other vehicles, where complete stops were considerably fewer than in recent years.
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Serrien, D. J., S. P. Swinnen und G. E. Stelmach. „Age-Related Deterioration of Coordinated Interlimb Behavior“. Journals of Gerontology Series B: Psychological Sciences and Social Sciences 55, Nr. 5 (01.09.2000): P295—P303. http://dx.doi.org/10.1093/geronb/55.5.p295.
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Wang, Peng-Wei, Nai-Ying Ko, Yu-Ping Chang, Chia-Fen Wu, Wei-Hsin Lu und Cheng-Fang Yen. „Subjective Deterioration of Physical and Psychological Health during the COVID-19 Pandemic in Taiwan: Their Association with the Adoption of Protective Behaviors and Mental Health Problems“. International Journal of Environmental Research and Public Health 17, Nr. 18 (18.09.2020): 6827. http://dx.doi.org/10.3390/ijerph17186827.
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This study aimed to determine the proportion of individuals who reported the deterioration of physical and psychological health during the coronavirus disease 2019 (COVID-19) pandemic in Taiwan. Moreover, the related factors of deterioration of physical and psychological health and the association between deterioration of health and adoption of protective behavior against COVID-19 and mental health problems were also examined. We recruited participants via a Facebook advertisement. We determined the subjective physical and psychological health states, cognitive and affective construct of health belief, perceived social support, mental health problems, adoption of protective behavior and demographic characteristics among 1954 respondents (1305 women and 649 men; mean age: 37.9 years with standard deviation 10.8 years). In total, 13.2% and 19.3% of respondents reported deteriorated physical and psychological health during the COVID-19 pandemic, respectively. Participants with higher perceived harm from COVID-19 compared with severe acute respiratory syndrome (SARS) were more likely to report the subjective deterioration of physical and psychological health, whereas respondents who were older and perceived a higher level of social support were less likely to report a deterioration of physical and psychological health. The subjective deterioration of psychological health was significantly associated with avoiding crowded places and wearing a mask. Both subjective deteriorations of physical and psychological health positively related to general anxiety.
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Nawfel Muhammed Baqer Muhsin. „A Study of the Thermal Behavior of Some Materials Used to Prevent Corrosion in Mechanical Parts“. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 104, Nr. 1 (03.04.2023): 55–64. http://dx.doi.org/10.37934/arfmts.104.1.5564.
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Thermal deterioration of Machines is the change in the properties of the basic material as a result of thermal reaction with its environment as a result of the presence of moisture in the bodies of machines such as the bodies of aircraft, cars, engineering equipment and related to the mechanics of the machines in the field of mechanical engineering, which is called the medium of deterioration and not as a result of a mechanical process such as friction in the machines as a result of work Continuous in these machines, according to this definition there is a possibility of corrosion not only in metals, but other materials such as concrete and containers that are in direct contact with moisture, air and environmental factors that are a catalyst for mechanical deterioration. Many researchers in mechanical engineering were interested in the thermal processes of machines, so the problem of corrosion and friction of machines and other important problems that have been studied extensively by finding engineering solutions to reduce or eliminate them. Corrosion of Machines be a limiting factor for various materials in many applications. Thus, it is necessary to have a better understanding of the deterioration processes, their prevention and reduction of the associated damage. In this research the preparation of some reagents and their use as deterioration inhibitors to reduce the deterioration process in engineering machinery by measuring the loss in weights resulting from the phenomenon of deterioration in engineering machinery. These thermal reagents were prepared as a thermal inhibitor painting, diagnosed in spectroscopic techniques, and then some thermal measurements were made to studying them as inhibitors of engineering corrosion in machines. The results appeared that the prepared reagents are good deterioration’s inhibitors due to the inhibition efficiency of the selected thermal reagents increased with increasing of concentration, and decreased with increasing of temperature.
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Singh, Trailokyanath, Nirakar Niranjan Sethy, Ameeya Kumar Nayak und Hadibandhu Pattnaik. „An Optimal Policy for Deteriorating Items With Generalized Deterioration, Trapezoidal-Type Demand, and Shortages“. International Journal of Information Systems and Supply Chain Management 14, Nr. 1 (Januar 2021): 23–54. http://dx.doi.org/10.4018/ijisscm.2021010102.
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This paper focuses an optimal policy of an inventory model for deteriorating items with trapezoidal type demand rate and the three-parameter Weibull distribution deterioration rate. The model allows shortages which are completely backlogged in order to achieve better preserving amenity. The authors present some optimal solutions which leads to determine the total inventory cost in which the collective behavior of customers hinges on the waiting time. An easy-to-use optimization technique is included to find the shortage time point and order quantity to minimize the total system cost. Taking into account the above-mentioned assumptions, different kinds of numerical examples are considered to illustrate the theoretical behavior of the framed optimization model. The sensitivity analysis is made for this problem with variation of parameters. The study shows that the optimal solution not only exists but also is unique and is less expensive to operate if the factors of three-phase variation, representing the growth, the steady, and the decline phases of demand with respect to time are considered.
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TAKAHARI, Tomoo, und Susumu OHTSUKA. „Deterioration Behavior of Colouring Solution for Stainless Steel“. Tetsu-to-Hagane 75, Nr. 4 (1989): 689–95. http://dx.doi.org/10.2355/tetsutohagane1955.75.4_689.
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An, Xin Zheng, Cheng Yi und Rui Xue Du. „Performance Deterioration Behavior of Existing Reinforced Concrete Bridges“. Advanced Materials Research 79-82 (August 2009): 1367–70. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1367.
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The analyses of concrete from a bridge in Handan district shows that most bridges concrete should have cracked. The study of the technical measures against the performance deterioration of existing reinforced concrete bridges will undoubtedly become an imperative issue. In recent years, lots of bridges have been built in Handan. We choose a reinforced concrete bridge to investigate the effect of the effective member stiffness degradation and durability degradation induced by vehicle overload, vehicle overflow, rebar corrosion, and concrete deterioration on highway reinforced concrete bridges. And Static loading test was conducted at its middle span. Based on the test data in different circumstances, the seriousness of vehicle overload is discussed. In consequence, the performance of highway reinforced concrete bridges on stiffness degradation and durability degradation is more serious compared with the bridge under the condition of non-overloading. The results show that the process of rebar corrosion in highway reinforced concrete bridges is sped up under the condition of vehicle overload and vehicle overflow on the highway reinforced concrete bridges, which decreases the durability of the bridge structure, and the speed of the durability degradation increases as time goes on. The paper conclusion is instructive for the construction and maintenance of bridge.
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Fernández-Fournier, Mireya, David C. Perry, Maria Carmela Tartaglia, Mary de May, Adam Boxer, Giovanni Coppola, Chadwick W. Christine et al. „Precipitous Deterioration of Motor Function, Cognition, and Behavior“. JAMA Neurology 74, Nr. 5 (01.05.2017): 591. http://dx.doi.org/10.1001/jamaneurol.2016.6159.
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Wu, Ji, Cai Liang, Xiushi Gan, Minghui Xie, Zhe Jiang, Zhenxing Zhao und Xu Wang. „Study on deterioration behavior of coke during gasification“. Metallurgical Research & Technology 120, Nr. 6 (2023): 607. http://dx.doi.org/10.1051/metal/2023078.
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The reaction temperature and time on the carbon loss of coke during CO2 gasification were studied. The results showed that there were significant correlations among the reactivity, pulverization rate, and wear resistance. The degree of variation in pulverization rate and wear resistance revealed that coke reactivity changed dramatically as reaction temperature rose. The temperature was also the key factor for coke graphitization. The evolution of the inorganic minerals and pore wall microstructure was investigated after coke gasification. The migration and accumulation of inorganic minerals, such as mullite, calcium ferrite, and iron oxide in coke, were discovered to catalyze the deterioration of the coke pore wall, resulting in the coke powder formation. The graphitization degree of the skin layer was greater than that of the core after high-temperature reactions, which accelerated skin layer separation from the core.
Dissertationen zum Thema "Deterioration behavior"
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Chand, Rakesh. „The Relationship Between Depression and Cognitive Deterioration in Older Adults“. ScholarWorks, 2011. https://scholarworks.waldenu.edu/dissertations/1053.
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The population structure of the United States is changing; the older age group is increasing in size relative to the younger generation. The trend is expected to continue, especially starting in 2020, when the baby boomer population---estimated at 80 million---will be reaching their 65 th birthday, a time associated with increasing health complications, including depression and dementia. The study employed a holistic paradigm as the conceptual framework to examine the association between depression and dementia in older adults, and generated a grounded theory to illuminate the relationship between depression and dementia. This theory was then used to assess the efficacy of stimulation, a nurturing environment, and treatment provided by an adult day health care (ADHC) in ameliorating the symptoms and progression of both dementia and depression. The sample consisted of 60 clients from a California ADHC center who were diagnosed with depression and dementia and who had received at least 6 months of services at the center. Paired t tests tested the validity of the hypotheses on depression among older adults and its correlation with their cognitive abilities. The results of paired t tests indicated a significant reduction in the client's level of depression between the time of their admission and the time of their reassessment 6 months later. This study can provide data for the larger social change discussion as to what resources should be allocated to meet the quickly escalating health, economic, and humanitarian pressures of the baby boom cohort.
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Rostami, Hamideh. „Equipment Behavior Modelling for Fault Diagnosis and Deterioration Prognosis in Semiconductor Manufacturing“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEM028.
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Les défauts de production dus aux variations dans le processus de fabrication et aux pannes inattendues des équipements rendent difficile la conservation d'un rendement élevé de production dans l'industrie de fabrication de semi-conducteurs. l'objectif de ce travail de thèse est de proposer un pronostic efficace du comportement des équipements ainsi qu'un diagnostic des pannes dans le processus de fabrication de semi-conducteurs. avec des capteurs plus performants, des proches efficaces basées sur des données sont proposées pour le pronostic et le diagnostic. pour le diagnostic, cette recherche applique d'abord la méthode de machines `a vecteurs de support (support vector machine) pour détecter les anomalies constatées dans les observations. la dynamique du processus normale est ensuite décomposée en différentes groupes par la méthode de partitionnement `a k -moyennes. l'analyse en composantes principales (acp) est utilisée pour modéliser chaque partie de la dynamique du processus. les empreintes de défaut peuvent enfin être extraites en consolidant les scénarios hors contrôle après avoir projeté les anomalies dans les modèles acp. en pronostic, une approche de modélisation et de surveillance de la dégradation des équipements pour le processus de fabrication par lots est développée avec deux objectifs : exploiter les données temporelles de détection et classification des fautes (fdc) pour caractériser le comportement des équipements et modéliser la tendance de détérioration avec les causes potentielles. la transformation en ondelettes discrète (dwt) décompose les données temporelles en composantes d'approximation détaillées afin de détecter deux types de détérioration provoquée par des variations au niveau macro et micro. les résultats montrent que les approches proposées permettent de prédire efficacement le comportement des équipements et de diagnostiquer la défaillance avec les causes premièresMoving toward advanced technologies requires the modern industries, in particular, the semiconductor, to keep their equipment at a high utilization level and lowenvironmental risk. production deficiencies such as process variations and unexpected equipment breakdowns have made it difficult (if not impossible) to stay at high-grade product yield and significant equipment utilization. in this thesis, the aim is to propose efficient equipment behavior prognosis, and equipment failure diagnosis approaches in batch manufacturing processes that are pervasive modes in today's semiconductor fab. with the advancement of sensor information technology, efficient data-driven approaches are proposed for both prognostic and diagnostic purposes. in the fault diagnosis, this research firstly applies the support vector machine (svm) classifier to detect the abnormal observations. the normal process dynamics are then decomposed into different clusters by k-means clustering. principal component analysis (pca) is used to model each part of the process dynamics. fault fingerprints can be extracted finally by consolidating the out of control scenarios after projecting the abnormal observations into the pca models. in prognostics, an equipment deterioration modeling and monitoring approach for batch processes is developed with two aims: exploiting the temporal fdc (fault detection and classification) data to characterize the equipment behavior and modeling the deterioration trend with the potential causes. by using the discrete wavelet transformation (dwt), the temporal data are decomposed into approximation and detail components to detect two types of deterioration caused by macro- and micro-level variations. several scenarios of case studies are conducted based on the practical dataset provided by a local IC maker. the results show that the proposed approaches can effectively prognose the equipment behavior and diagnose the equipment failure with the correct causes
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Dipchand, June S. „An investigation into the effects of CNG-gasoline operation on EGO sensor behavior and deterioration“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63118.pdf.
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Rozental, Alexander. „Negative effects of Internet-based cognitive behavior therapy : Monitoring and reporting deterioration and adverse and unwanted events“. Doctoral thesis, Stockholms universitet, Klinisk psykologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-135382.
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Internet-based cognitive behavior therapy (ICBT) has the potential of providing many patients with an effective form of psychological treatment. However, despite helping to improve mental health and well-being, far from everyone seem to benefit. In some cases, negative effects may also emerge. The overall aim of the present thesis was to establish the occurrence and characteristics of such incidents in ICBT using a combination of quantitative and qualitative methods. Study I determined deterioration, non-response, and adverse and unwanted events in a sample of 133 patients undergoing ICBT for social anxiety disorder. The results indicated that up to 6.8% fared worse during the treatment period, depending on the self-report measure and time point, as determined using the Reliable Change Index (RCI), while the non-response rate was between 29.3 to 86.5% at post treatment assessment, and 12.9% experienced other negative effects. Study II investigated the responses to open-ended questions on adverse and unwanted events among 556 patients in four separate clinical trials of ICBT; social anxiety disorder, panic disorder, major depressive disorder, and procrastination. In total, 9.3% reported negative effects, with a qualitative content analysis revealing two categories and four subcategories; patient-related, i.e., gaining insight and experiencing new symptoms, and treatment-related, i.e., difficulties applying the treatment interventions and problems related to the treatment format. Study III explored the number of patients achieving reliable deterioration, as determined using the RCI on the individual raw scores of 2866 patients from 29 clinical trials of ICBT. The results showed that the deterioration rate was higher among patients in a control condition, 17.4%, in comparison to treatment, 5.8%. Predictors were related to decreased odds of deterioration for patients receiving treatment; clinical severity at pre treatment assessment, being in a relationship, having a university degree, and being older. As for the control condition, only clinical severity at pre treatment assessment was associated with decreased odds of deterioration. Study IV examined a newly developed self-report measure for monitoring and reporting adverse and unwanted events, the Negative Effects Questionnaire. The results suggested a six-factor solution with 32 items; symptoms, quality, dependency, stigma, hopelessness, and failure. One-third of the patients reported experiencing unpleasant memories, stress, and anxiety, with novel symptoms and a lack of quality in the treatment and therapeutic relationship having the greatest negative impact. The general finding of the present thesis is that negative effects do occur in ICBT and that they are characterized by deterioration, non-response, and adverse and unwanted events, similar to psychological treatments delivered face-to-face. Researchers and clinicians in ICBT are recommended to monitor and report negative effects to prevent a negative treatment trend and further the understanding of what might contribute to their incidents. Future research should investigate the relationship between negative effects and treatment outcome, especially at follow-up, to examine if they are transient or enduring. Also, interviews could be conducted with those achieving reliable deterioration to explore if and how it is experienced by the patients and to see if it is attributed to the treatment interventions or other circumstances.Internetbaserad kognitiv beteendeterapi (IKBT) har goda förutsättningar att kunna bli en form av psykologisk behandling som på ett effektivt sätt hjälper patienter med att hantera sin psykiska ohälsa och förbättra sitt välmående. Trots detta är det dock långtifrån alla som tycks bli bättre. För en del kan det till och med resultera i negativa effekter. Det övergripande syftet med denna avhandling har således varit att undersöka förekomsten av sådana fall och hur dessa uttrycks, såväl med kvantitativa som kvalitativa metoder. Studie I fastställde andelen försämrade, oförändrade samt andra ogynnsamma eller oönskade händelser bland 133 personer som behandlades med IKBT för social ångest. Resultatet visade att uppemot 6,8 % försämrades under sin behandlingsperiod beroende på vilket självskattningsformulär respektive tidpunkt som studerades, beräknat enligt metoden Reliable Change Index (RCI). Likaså var 29,3 % till 86,5 % oförändrade vid eftermätningen samt att 12,9 % rapporterade andra former av negativa effekter. Studie II undersökte svaren på öppna frågor som gällde ogynnsamma eller oönskade händelser bland 556 patienter i fyra olika kliniska studier med IKBT; social ångest, paniksyndrom, egentlig depressionsepisod och prokrastinering. Totalt sett rapporterade 9,3 % att de hade erfarit negativa effekter, vilka analyserades med hjälp av kvalitativ innehållsanalys. Två övergripande kategorier och fyra subkategorier framkom; patientrelaterade, som ökad insikt respektive nya symptom, samt behandlingsrelaterade, som svårigheter att implementera behandlingsinterventionerna respektive problem med behandlingsformatet. Studie III utrönte andelen patienter som försämrades i enlighet med RCI, baserat på insamlad rådata från 2866 personer i 29 olika kliniska studier med IKBT. Resultatet visade att försämring var mer förekommande hos de som var i en kontrollgrupp, 17,4 %, jämfört med de som fick behandling, 5,8 %. Bland de som genomgick behandling existerade det även ett par prediktorer som innebar lägre odds för försämring; större svårigheter vid förmätningen, att befinna sig i en relation, att ha en universitetsutbildning respektive att vara äldre. För de som var i en kontrollgrupp var enbart större svårigheter vid förmätningen relaterat till lägre odds för försämring. Studie IV testade ett nykonstruerat självskattningsformulär; Negative Effects Questionnaire. Resultatet visade på en faktorlösning med sex faktorer och 32 påståenden; symptom, kvalitet, beroende, stigma, hopplöshet respektive misslyckande. En tredjedel av personerna svarade att de hade upplevt obehagliga minnen, stress och ångest, samtidigt som nya symptom och bristande kvalitet i både behandlingen respektive den terapeutiska relationen hade haft störst negativ inverkan på dem. Den generella slutsatsen av denna avhandling är således att negativa effekter förekommer i IKBT och att de kännetecknas av försämring, ett oförändrat tillstånd samt andra ogynnsamma eller oönskade händelser, något som liknar tidigare forskning av psykologisk behandling som bedrivs ansikte-mot-ansikte. Forskare och behandlare i IKBT rekommenderas att övervaka och rapportera negativa effekter i syfte att förhindra en negativ utveckling i behandlingen samt för att öka kunskapen om vad som kan bidra till deras förekomst. Framtida forskning bör undersöka relationen mellan negativa effekter och behandlingsutfall utifrån längre tidsperspektiv för att se om dess påverkan är övergående eller ihållande. Vidare kan till exempel intervjuer utföras med de patienter som har försämrats för att ta reda på om och hur det uppfattas samt huruvida det har förorsakats av behandlingen eller andra omständigheter.
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: In press.
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Craze, Gareth John. „Inflammation-Associated Mood Deterioration and the Degradation of Affective Climate: An Agent-Based Model“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1595451097576364.
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Zhang, Xiaohui. „Manufacturing of hemp/PP composites and study of its residual stress and aging behavior“. Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0015/document.
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Depuis quelques années les matériaux composites à base de fibres naturelles sont de plus en plus utilisés pour les nouvelles performances qu’ils proposent. C’est surtout au niveau des fibres naturelles que de nouvelles propriétés sont proposées. Dans ce travail, nous nous sommes essentiellement intéressés aux fibres naturelles de chanvre. Ces fibres sont déjà fortement utilisées dans l’automobile et la construction. En Europe, ces fibres sont produites principalement en France et plus particulièrement dans l’Aube. Pour développer des agro-composites hautes performances, c’est sous la forme de fibres longues et de tissus que nous avons choisi d’orienter ce travail de thèse. Nous avons choisi la thermocompression pour élaborer des plaques avec des tissus de chanvre et une matrice en polypropylène (PP). Ce travail permet de voir l’influence des conditions d’élaboration sur le comportement mécaniques de ces agro-composites. Cette thèse permet aussi de voir l’effet du vieillissement aux UV et à l’Humidité sur les performances de ces matériaux. Enfin une analyse des contraintes résiduelles par la méthode du trou incrémental permet de voir leurs effets sur ces agro-matériauxIn recent years composite materials based on natural fibers are more and more used for their new performances. Natural fibers propose attractive environmental, mechanical and thermal properties.In this work, we are firstly interested in hemp fibers. These fibers are already used in the automotive and construction industry. In Europe, these fibers are produced mainly in France and especially in Aube. To develop agro-composites with high performances, we have focused this thesis on hemp woven. We chose to elaborate the plates with hemp woven and a polypropylene matrix (PP) by compression molding. This work allows us to see the influence of elaboration conditions on the mechanical behavior of these agro-composites. This thesis also allows us to see the effect of aging conditions UV and humidity on the performance of these materials. Finally an analysis of residual stresses determined by the hole drilling method is proposed to see their effects on the agro-materials
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Si, Xuetong, und 司学通. „Structural behaviour of cable-stayed bridges taking into account time-dependent behaviour“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47849514.
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The creep and shrinkage of concrete and the relaxation of cables cause long-term redistribution of internal forces and time-dependent deformations in concrete structures, steel-concrete composite structures and concrete cable-stayed bridges. They should be properly modelled for accurate prediction of their long-term behaviour and its effect on instantaneous structural responses at service.
An equivalent stress relaxation model is proposed for prestressing tendons based on the intrinsic stress relaxation, from which the equivalent creep coefficients can be obtained through a recursive algorithm. Based on the equivalent stress relaxation model, an accurate finite element analysis of time-dependent behaviour by time integration has been devised considering concrete creep, concrete shrinkage and cable relaxation. Concrete members are modelled by beam-column elements while tendons are modelled by truss elements with nodes connected to the beam axis by perpendicular rigid arms. It is found that the proposed relaxation model with time integration can provide a reliable method as well as benchmark solutions for time-dependent analysis. The numerical results obtained indicate that the interactions among these factors should be properly considered in analysing the long-term performance of concrete bridges.
Although time integration provides a reliable method for time-dependent analysis, both the computing time and memory requirement increase drastically with the number of time steps as the time-dependent strains of concrete and tendons within a time interval depend on the loading history up to that time. It is therefore necessary to develop a more efficient method to conduct time-dependent analysis.
The relaxation-adjusted elasticity modulus is introduced on the basis of equivalent creep coefficients of tendons. Then, an efficient tendon sub-element is put forward to cope with cables with arbitrary profiles. Finally, a more general single-step method is devised using the classical age-adjusted elasticity modulus to account for external loading and creep effect, the shrinkage-adjusted elasticity modulus to consider shrinkage effect and its interaction with concrete creep, and the relaxation-adjusted elasticity modulus to consider the effect of cable relaxation based on the finite element method. The numerical results obtained indicate not only the accuracy of the single-step method but also the significance of interaction among various time-varying factors.
Based on the time integration or single-step method, a systematic method is developed to monitor the long-term variations of dynamic properties of cable-stayed bridges taking into account various time-varying factors and geometric nonlinearities. Numerical studies show that, although geometric nonlinearities tend to reduce the natural frequencies, the time-dependent behaviour of concrete more than offsets it and tends to increase the natural frequencies in the long run.
A generic method is further presented to investigate the long-term dynamic response of vehicle-bridge interaction systems taking account of time-dependent behaviour. The vehicles are represented by a combination of mass-spring-damper systems while the bridge is modelled by finite elements. The surface roughness of bridge deck is simulated by spectral representation method and introduced to the coupled system properly. Based on the method, the individual and combined effects of various time-varying factors are studied in detail using various numerical examples.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
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Du, Qixin. „Finite Element Modelling of Steel/Concrete Bond for Corroded Reinforcement“. Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33465.
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Reinforcement corrosion is the most common deterioration problem observed in reinforced concrete (RC) structures located at coastal or cold regions. The corrosion process can impact the performance of these structures by inducing damage on the bonding action between concrete and steel, either by the splitting of the concrete cover due to the volumetric expansion of corrosion products or the lubricant effect at the steel/concrete interface as the corrosion by-products accumulate. The current research aims at investigating corrosion-induced deterioration of bond between steel and concrete through finite element (FE) analysis of the flexural behaviour of corroded RC components. By treating the concrete cover as a thick-wall cylinder subjected to internal pressure, the analytical evaluation of impaired bond capacity is studied first and verified against published bonding tests. Then, the formulation of a numerical model is performed using ABAQUS, wherein a link element to simulate the bond behaviour is formulated and implemented through the ABAQUS user-subroutine (UEL) feature according to the validated analytical model. By introducing corrosion-induced damages, i.e., smaller cross-sectional area of reinforcement, splitting of concrete and bond deterioration, in the FE analyses, the results of the numerical model show good agreement with experimental observations. Upon validation of the analytical and FE models, a parametric investigation is conducted, wherein the effects of concrete strength, dimension of reinforcing bars, properties of oxide products, different corrosion damage mechanisms and the corrosion location along the longitudinal reinforcement on the flexural behaviour of RC beams are studied. The results show that the analytical evaluation for bond degradation is impacted by the selection of the post-cracking material model and the thickness of cover that determine the ‘holding capacity’ after cracking initiation. Also, the density of rust by-products affects the results of the analytical model at high corrosion levels. From the FE model results, it was observed that each damage mechanism due to corrosion contribute to different levels of flexural degradation, although the flexural strength degradation is mainly due to the loss of bonding action. The parametric study also demonstrates that flexural members which have reinforcement corrosion initiated near the supports suffer greater deterioration in flexural capacity than those with damages at mid span. Finally, based on these observations, suggestions for the application of both analytical and numerical models are made.
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Liu, Chi-hong, und 廖志航. „Time-dependent behaviour of concrete structures with special referenceto podium and frame structures“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38674245.
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Wang, Chu. „Deep learning-based prognostics for fuel cells under variable load operating conditions“. Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0530.
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Les systèmes de piles à combustible à membrane d'échange de protons (PEMFC) conviennent à diverses applications dans le domaine des transports, mais leur coût élevé et leur manque de durabilité restent les principaux facteurs limitant leur commercialisation à grande échelle. Dans les applications de transport, la détérioration des PEMFC est aggravée par des conditions de charge variables, ce qui entraîne une diminution de leur durée de vie utile restante (RUL). La gestion des pronostics et de la santé (PHM) est un outil efficace pour prévoir les risques du système, gérer les calendriers de contrôle/maintenance du système, améliorer la sécurité et la fiabilité du système, prolonger la durée de vie du système et réduire les coûts d'exploitation/maintenance. Le pronostic est une base importante et un support clé pour le PHM, et ses tâches principales incluent l'extraction d'indicateurs de santé, la prédiction des tendances de dégradation et l'estimation de la RUL. Les caractéristiques de dégradation à long terme des PEMFC sont dissimulées dans des conditions de charge variables, ce qui augmente la difficulté d'extraction des indicateurs de santé, réduit la précision de la prédiction de la dégradation et inhibe la fiabilité de l'estimation de la durée de vie. Dans cette optique, le travail de thèse part de la modélisation du comportement de dégradation des PEMFC dans des conditions de charge variables et mène des travaux de recherche sur l'extraction d'indicateurs de santé, la prédiction des tendances de dégradation à court/long terme, l'estimation RUL et l'évaluation de la fiabilitéProton exchange membrane fuel cell (PEMFC) systems are suitable for various transportation applications thanks to their compact structure, high power density, low start/running temperature, and zero carbon emissions. High cost and lack of durability of PEMFC are still the core factors limiting their large-scale commercialization. In transportation applications, the deterioration of PEMFCs is aggravated by variable load conditions, resulting in a decrease in their Remaining Useful Life (RUL). Prognostics and health management (PHM) is an effective tool to forecast potential system risks, manage system control/maintenance schedules, improve system safety and reliability, extend system life, and reduce operation/maintenance costs. Prognostics is an important foundation and key support for PHM, and its core tasks include health indicator extraction, degradation trend prediction, and RUL estimation. The long-term degradation characteristics of PEMFC are concealed in variable load conditions, which increases the difficulty of health indicator extraction, reduces the accuracy of degradation prediction, and inhibits the reliability of life estimation. In view of this, the thesis work starts from modeling the degradation behavior of PEMFC under variable load conditions and carries out research work on health indicator extraction, short/long-term degradation trend prediction, RUL estimation and reliability evaluation
Bücher zum Thema "Deterioration behavior"
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NATO Advanced Study Institute on the Behavior of Systems in the Space Environment (1991 Pitlochry, Scotland). The behavior of systems in the space environment. Dordrecht: Springer, 1993.
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NATO Advanced Study Institute on the Behavior of Systems in the Space Environment (1991 Pitlochry, Scotland). The behavior of systems in the space environment. Dordrecht: Kluwer Academic Publishers, 1993.
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Dipchand, June S. An investigation into the effects of CNG-gasoline operation on EGO sensor behavior and deterioration. Ottawa: National Library of Canada, 2001.
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Time dependent behaviour of high strength concrete. Delft: Delft University of Technology, 1996.
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Gilbert, R. I. Time-dependent behaviour of concrete structures. London: Spon, 2010.
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1972-, Ranzi Gianluca, Hrsg. Time-dependent behaviour of concrete structures. London: Spon, 2010.
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Gauri, K. Lal, und Jayanta K. Bandyopadhyay. Carbonate Stone: Chemical Behavior, Durability, and Conservation. Wiley-Interscience, 1999.
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Kreisl, William C., und Christiane Reitz. Diagnosis and Epidemiology of Dementia. Herausgegeben von Dennis S. Charney, Eric J. Nestler, Pamela Sklar und Joseph D. Buxbaum. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190681425.003.0050.
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Dementia is a neurodegenerative clinical syndrome encompassing a wide range of diseases characterized by progressive deterioration in cognitive ability, function and behavior. More than 24 million people worldwide are currently affected, and this prevalence is predicted to quadruple by the year 2050. The most common cause of dementia is Alzheimer’s disease, clinically characterized by a progressive impairment in cognitive function. To date, Alzheimer’s disease cannot be prevented or cured; the available treatments only slightly improve cognitive symptoms. In this chapter, we provide an overview of the most common neurodegenerative causes of dementia, beginning with Alzheimer’s disease, and summarize current information relating to the prevalence and incidence of dementia.
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Speiser, Peter. The Germans. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252040160.003.0004.
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This chapter focuses on the German perspective of relations with the BAOR. It studies the changing expectations of and demands by the German civilian population, as well as federal and Land (state) administrations during a period of fundamental changes in Anglo-German relations. The chapter looks at attempts to use the BAOR in order to undermine German cooperation with the West, as well as German efforts to counter these threats, all within economic, political, and social contexts. When considering the occupation forces of the Western powers, the problems created by the presence of American troops have been highlighted by John Willoughby. His work focuses on the threat to US authority in Germany posed by the disorderly behavior of American troops and the resulting initiatives that prevented a deterioration of relations in the period between 1945 and 1948.
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Raine, Tim, James Dawson, Stephan Sanders und Simon Eccles. Neurology and psychiatry. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199683819.003.0011.
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Coma and reduced GCS emergencyComa and reduced GCSAcute confusionDementiaAdult seizures emergencyPaediatric seizures emergencySeizuresNeurodegenerative disordersStroke/CVA/TIA emergencyStrokeFocal neurologyBack painHeadacheDizzinessAggressive behaviour emergencyMood disturbance/psychosisCall for senior help early if patient unwell or deteriorating....
Buchteile zum Thema "Deterioration behavior"
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Wang, Lei. „Bond Behavior Between Strand and Concrete with Corrosive Cracking“. In Strand Corrosion in Prestressed Concrete Structures, 75–103. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2054-9_4.
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AbstractBond behavior between strand and concrete plays a decisive role in sustaining the properties of prestressed concrete structures. This chapter mainly discusses the bond behavior between corroded strand and concrete. First, the effects of corrosion-induced crack on the bond between strand and concrete are studied based on the pull-out test; the confinement role of stirrups on the deterioration of bond behavior affected by concrete cracking is addressed. Next, the bond behavior of corroded strand in pretensioned concrete structures is investigated by the bending test; the effects of strand corrosion on force–slip curves, bond strength, and failure mode are discussed.
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Terasaki, Nao. „Direct Visualization of Mechanical Behavior During Adhesive Bonding Failure Using Mechanoluminescence (ML)“. In Interfacial Phenomena in Adhesion and Adhesive Bonding, 209–90. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-4456-9_4.
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AbstractIn this chapter, we introduce recent progress in direct visualization of mechanical behavior in the failure process of adhesive bonding by mechanoluminescence (ML). Firstly, basic mechanoluminescence technologies are introduced in terms of materials, sensors, sensing technologies in Sects. 1 and 2. Then, for considering effective application of ML sensing that takes advantage of technological features, (Sect. 3) structural health monitoring (SHM)/Conditioning based monitoring (CBM), and (Sect. 4) innovation in design and prediction are discussed from the viewpoint of visualizing mechanical behavior, deterioration, and failure process as killer application of ML sensing. Furthermore, visualizing the mechanical behavior of adhesive joints, fracture initiation points, and fracture processes will be introduced based on time-series information of mechanoluminescence (ML) images, using internationally standardized adhesion strength tests.
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Wang, Lei. „Brief Description of Prestressed Concrete Structures“. In Strand Corrosion in Prestressed Concrete Structures, 1–16. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2054-9_1.
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AbstractStrand corrosion can cause concrete cracking, degrade bond performance at the strand–concrete interface, lead to prestress loss, and deteriorate the capacity of prestressed concrete structures. This book clarifies the mechanical behavior of corroded prestressing strands, corrosion-induced cracking, bond degradation, prestress loss, and structural performance deterioration of prestressed concrete structures and proposes the corresponding prediction models, which has an important guidance for the durability and maintenance design of prestressed concrete structures.
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Ishida, T., und S. Yamada. „Deterioration Behavior of SHS Steel Columns Subjected to Small Amplitude Loading History“. In Lecture Notes in Civil Engineering, 1391–401. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-8079-6_130.
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Hahn, Judith. „Dissent as Deviance: Sociological Observations on Structural Conflicts in Church“. In Pathways for Ecumenical and Interreligious Dialogue, 103–21. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-56019-4_7.
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AbstractOver the past century, dissent has become increasingly apparent with regard to many institutional norms of the Roman Catholic Church, including the doctrinal, moral, and legal norms that determine behavioral expectations within the church as an institution. In the legal field, dissent often manifests as deviance, behavior which opposes or undermines the ecclesiastical norms. In my contribution, I explore dissent as deviance with regard to the current social structure of the church in the light of sociological considerations on anomie. To do this, I have divided my study into three steps. First, I refer briefly to the recent symptoms in church which reveal the deterioration of institutional norms. Second, I endeavour to identify the structural reasons that might be responsible for causing this effect by studying sociological findings on deviance and anomie, foremost among them Robert Merton’s strain theory. Third, I apply these considerations to recent phenomena in church to gain a better understanding of why the current social structure of the church is inducing certain groups to turn to deviant behavior. I conclude by linking these sociological observations with theological thought to show how a theory of non-reception might help the church to learn from deviance and improve its structure.
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Tenderan, R., T. Ishida und S. Yamada. „Structural Behavior of Steel Moment-Resisting Frames Subjected to Multiple Earthquakes Considering Column Strength Deterioration“. In Lecture Notes in Civil Engineering, 1379–89. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-8079-6_129.
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He, Y., C. Xing, C. Wang, Q. Tan, B. Hong und D. Wang. „Study on the seasonal variation and deterioration behavior of the skid resistance performance of asphalt pavement“. In Green and Intelligent Technologies for Sustainable and Smart Asphalt Pavements, 234–40. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003251125-38.
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Jain, Ankit, und Abhishek Srivastava. „A Comprehensive Framework for Detecting Behavioural Anomalies in the Elderly“. In AI, Data, and Digitalization, 136–50. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-53770-7_9.
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AbstractThe world is seeing a rapid increase in the population of the aged. This, combined with a shortage of affordable care-giving manpower, leads to a dependence on automated systems for monitoring the well-being of the elderly and detecting abnormalities. There exist techniques based on sensors of various types to detect and recognize the daily activities of the elderly and detect anomalies. While such sensor-based techniques are effective at detecting immediate exigencies, they are unable to comprehend gradual deterioration in the behavior of the elderly indicating conditions like dementia and Alzheimer’s, for example. This aspect is also not properly addressed in the literature. This paper introduces an approach for the comprehensive detection of anomalies in the activities of the elderly using a graph-based approach. The approach employs dynamic activity graphs where anomalies are detected using a dissimilarity score. It is capable of detecting both short-term and long-term anomalies in the daily activities of the elderly.
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Cao, J., N. Gowripalan, V. Sirivivatnanon und J. Nairn. „Investigation of ASR Effects on the Load-Carrying Capacity of Reinforced Concrete Elements by Ultra-Accelerated Laboratory Test“. In Lecture Notes in Civil Engineering, 43–52. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_7.
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AbstractThe alkali–silica reaction (ASR) can cause expansion, cracking, and degradation of the mechanical properties of affected concrete. Concerns about the safety of ASR-damaged reinforced concrete structures have driven the demand for studying the effects of ASR on residual load capacity of the deteriorated structure. Conventionally, field load testing methods are used to assess the residual load capacity of ASR-affected structures. In this study, a novel accelerated laboratory test using the LVSA 50/70 autoclave to accelerate ASR was applied to investigate the flexural and shear behavior of small-scale reinforced concrete beams affected by ASR. The specimens were subjected to three cycles of 80 °C steam curing at atmospheric pressure in the autoclave, with 60 h/cycle. Significant expansion and ASR damage were observed. Load carrying capacity tests on the small-scale reinforced concrete beams showed that, at the expansion levels achieved, the flexural capacity of the reinforced concrete beams was not significantly affected. Shear resistance of the reinforced concrete beams, however, was found to increase compared with their 28-day counterparts, which could be attributed to the prestressing effect due to ASR expansion. It appears that the multicycle 80 °C steam-curing autoclave test is suitable for investigating ASR deterioration of actual concrete mixes within a short period of time. ASR effects on the load carrying capacity of reinforced concrete elements at higher expansion levels, however, need further investigation.
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Singh, H. B., Akansha Jain, Amrita Saxena, Akanksha Singh, Chetan Keswani, Birinchi Kumar Sarma und Sandhya Mishra. „Deciphering the Pathogenic Behaviour of Phyto-Pathogens Using Molecular Tools“. In Biological Controls for Preventing Food Deterioration, 377–408. Chichester, UK: John Wiley & Sons, Ltd, 2014. http://dx.doi.org/10.1002/9781118533024.ch16.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Deterioration behavior"
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Tabakoff, W., M. Metwally und A. Hamed. „High Temperature Coatings for Protection Against Turbine Deterioration“. In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-200.
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In this research, an investigation was conducted to study the fly ash particles associated with the erosion behavior of alloys and coatings which are widely used in gas and steam turbines. The erosion behavior of many alloys and protective coatings has been investigated experimentally at high temperatures using a specially designed wind erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate.
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Xiang, Yisha, und C. Casady. „Time to Failure Behavior under a Stochastic Deterioration Model“. In 2007 Proceedings Annual Reliability and Maintainability Sympsoium. IEEE, 2007. http://dx.doi.org/10.1109/rams.2007.328108.
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Van Hardeveld, Thomas. „An Expert System for Trend Analysis Applied to Turbomachinery“. In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-047.
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With the advent of computerized monitoring techniques, it is becoming evident that more automated methods of trend analysis and other diagnostic techniques are both possible and necessary. The implementation of a computerized health monitoring system has led to research into techniques for identifying trend behavior which can be used to detect equipment deterioration. The result has been the development of statistical techniques to characterize generic trend behavior and of an expert system to translate these into a diagnosis of equipment deterioration.
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Spakovszky, Z. S., J. B. Gertz, O. P. Sharma, J. D. Paduano, A. H. Epstein und E. M. Greitzer. „Influence of Compressor Deterioration on Engine Dynamic Behavior and Transient Stall-Margin“. In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-439.
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This paper presents an experimental and analytical investigation of compressor stability assessment during engine transient operation. A 2-dimensional, linear, compressible, state-space analysis of stall-inception (Feulner et al. (1996)) was modified to account for engine transients and deterioration, with the latter modeled as increased tip-clearance and flow blockage. Experiments were performed on large commercial aircraft engines in both undeteriorated and deteriorated states. Unsteady measurements of pressure in these test engines during rapid accelerations revealed the growth of pre-stall disturbances, which rotate at rotor speed and at approximately half rotor speed. These disturbances are stronger in deteriorated engines. The model showed that the signal at shaft speed was the first compressible system mode, whose frequency is near shaft speed, excited by geometric nonuniformities. The computed behavior of this mode during throttle transients closely matched engine data. The signal increased in strength as stall was approached and as the engine deteriorated. This work firmly establishes the connection between observed signals in the these engines and first principles stability models.
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Cerri, Giovanni, Sandra Borghetti und Coriolano Salvini. „Models for Simulation and Diagnosis of Energy Plant Components“. In ASME 2006 Power Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/power2006-88146.
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This paper describes a methodology to set up models for simulation and diagnosis of energy plant components. The adopted approach consists in a simultaneous solution of modules representing plant components taking their actual behavior into account. Models are characterized by Reality Functions to adapt them to the reality of machines and apparatuses so that the New&Clean map of the real component can be established. Furthermore, to account for deterioration phenomena occurring during plant operations, Actuality Functions affecting component performance in terms of work and heat transfer, losses and effective flow functions have been introduced. Models have been validated and tested against real CHP plant data. Two applications to different kinds of power plants are presented and discussed. Results show a good capability to estimate component deterioration statuses and reproduce component actual behavior maps.
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Cerri, Giovanni, Stefano Mazzoni und Coriolano Salvini. „Steam Cycle Simulator for CHP Plants“. In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94045.
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This paper describes a methodology to set up steam cycle simulators for CHP plants. The adopted approach consists in a simultaneous solution of modules representing plant components taking their actual behavior into account. Models are characterized by Reality Functions to adapt them to the reality of machines and apparatuses so that the New&Clean map of the real component can be established. Furthermore, to account for deterioration phenomena occurring during plant operations, Actuality Functions affecting component performance in terms of work and heat transfer, losses and effective flow functions have been introduced. Models have been validated and tested against real CHP plant data. Applications to different kinds of CHP steam cycles are presented and discussed. Results show a good simulator capability to estimate component deterioration status and to reproduce the plant actual behavior.
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Reitz, Gerald, Andreas Kellersmann und Jens Friedrichs. „Full High Pressure Compressor Investigations to Determine Aerodynamic Changes due to Deterioration“. In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76644.
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The Institute of Jet Propulsion and Turbomachinery of the TU Braunschweig owns a jet engine of the type V2500-A1 from the International Aero Engines AG. To conduct research on the jet engine and its components, computer models are necessary. In this paper, the reverse engineering process of the high pressure compressor (HPC) regarding its aerodynamics is presented. Thereby, the reverse engineering process starts from digitizing newly manufactured airfoils, followed by FEM-calculations to enforce the operating forces on the geometries. A computational fluid dynamics (CFD) model using these geometries is set up, considering all relevant geometric and aerodynamic features such as bleed ports and the variable stator vane (VSV) system. Using this CFD-model, the compressor map is calculated and afterwards validated by available manufacturing data [18] and by the institute’s jet engine’s test cell data. Because this jet engine is a highly operated and deteriorated one, a map scaling is necessary before comparing the CFD-model with the test cell data. Nevertheless, an adequate agreement of the operating behavior between scaled compressor map and test cell data is shown. To estimate the deterioration level of the jet engine’s compressor and to evaluate the used scaling factors, the tip gaps inside the CFD-model were doubled and the compressor behavior was simulated. The observed effect of reduced compressor capacity and efficiency is in accordance with literature but is not able to explain the amount of the scaling factors completely.
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Shi, Yanwen, Jiabin Wang, Rongguang Hu und Bo Wang. „Electromagnetic and thermal behavior of a triple redundant 9-phase PMASynRM with insulation deterioration fault“. In 2019 IEEE Energy Conversion Congress and Exposition (ECCE). IEEE, 2019. http://dx.doi.org/10.1109/ecce.2019.8912582.
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Gu, Hanyang, Xu Cheng und Xiaojing Liu. „Numerical Analysis of Thermal-Hydraulic Behavior of Supercritical Water in Vertical Upward/Downward Flow Channels“. In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48836.
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Investigations on the thermal-hydraulic behavior in the SCWR fuel assembly have obtained a significant attention in the international SCWR community. However, there is still a lack of understanding and ability to predict the heat transfer behavior of supercritical fluids. In this paper, the numerical analysis is carried out to study the thermal-hydraulic behaviour in vertical sub-channels cooled by supercritical water. Remarkable differences in characteristics of secondary flow are found, especially in square lattice, between the upward flow and downward flow. The turbulence mixing across sub-channel gap for downward flow is much stronger than that for upward flow in wide lattice when the bulk temperature is lower than pseudo-critical point temperature. For downward flow, heat transfer deterioration phenomenon is suppressed with respect to the case of upward flow at the same conditions.
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Sabbaghi, Mostafa, und Sara Behdad. „Environmental Impact Assessment of Product Lifespan: The Role of Consumer’s Repair Behavior and Critical Components Deterioration“. In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59321.
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Consumers might be willing to repair their broken devices as long as the associated repair costs do not exceed an undesirable threshold. However, in many cases the technological obsolescence actuates consumers to retire old devices and replace them with new ones rather than extending the product lifecycle through repair. In this paper, we aim to investigate the impact of components’ deterioration profiles and consumers’ repair decisions on the lifespan of devices, and then assesse the anticipated life cycle environmental impacts. A Monte Carlo simulation is developed to estimate the life cycle characteristics such as the average lifespan, the number of failed components’ replacement, and the total repair cost per cycle for a laptop computer. The lifecycle characteristics estimated from simulation model further have been used in a Life Cycle Assessment (LCA) study to quantify the environmental impact associated with different design scenarios. The results reveal the impact of product design as well as consumers’ repair decisions on the product lifespan and the corresponding environmental impacts.
Berichte der Organisationen zum Thema "Deterioration behavior"
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Obata, Makoto, und Yoshiaki Goto. ANALYSIS OF RUBBER BEARING BEHAVIOR WITH MATERIAL DETERIORATION. The Hong Kong Institute of Steel Construction, Dezember 2018. http://dx.doi.org/10.18057/icass2018.p.121.
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Acosta, Felipe, und Guillermo Riveros. Repair of corroded steel girders of hydraulic steel structures (HSS) using fiber-reinforced polymers (FRP). Engineer Research and Development Center (U.S.), August 2023. http://dx.doi.org/10.21079/11681/47404.
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Although steel hydraulic structures have a protective system to prevent corrosion, this type of deterioration will eventually occur due to the constant exposure to harsh environmental conditions. There are several techniques that can be implemented to repair corroded steel structural elements. This report presents a numerical study to evaluate the mechanical behavior of corroded steel girders used in hydraulic steel structures and to evaluate several carbon fiber–reinforced polymers (CFRP) layups to repair them. The girders were modeled as simply supported with four-point loading boundary conditions. The corrosion deterioration was modeled as loss in section as 10%, 25%, and 40%. The effectiveness of the deterioration was established based on the level of stresses at the steel compared with the undamaged condition after it is strengthened with CFRP. It was found that CFRP repair is more practical for reducing the stresses at the steel in the shear dominated zone if deterioration is below 25%. At the tensile dominated zone, CFRP is effective for reducing the stresses for deterioration below 40%.
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Fu, Gongkang, und Gabriel Bryk. BrM Quantity-Based Bridge Element Deterioration/Improvement Modeling and Software Tools. Illinois Center for Transportation, Februar 2024. http://dx.doi.org/10.36501/0197-9191/24-005.
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This study reviewed the state of the art and practice in bridge element deterioration / improvement modeling. It also developed a new and practical method for such modeling using element quantities in BrM inspection records along with bridge age. For reliable forecasting, this method uses these quantities directly to determine transition probability matrices (TPMs). The example TPMs were found age-dependent for the do-nothing case. Results show that this approach is effective in forecasting the bridge element life. Condition improvement TPMs were also similarly derived from the quantity evolution for consistency. Examples of renewal construction work are deck overlay of micro-silica concrete, steel beam repainting, bridge cleaning, etc. Two computer software programs in Microsoft Excel were developed to obtain TPMs for do-nothing deterioration and condition improvement. Bridge owners may use the tools to generate TPMs for any element whose inspection records are provided. As a result, TPMs can be continuously updated whenever more inspections are performed and their records are included as input to the software programs. In addition, the software tools are transparent for the user to perform expert elicitation, especially when the inspection records are questionable or unavailable. Such activity can be informatively guided by the results from the software, as illustrated by two application examples in the delivered programs. This new concept and associated tools may be applied by other bridge owners using the BrM system. Two application examples for elements 12 and 107 in the programs can be readily transplanted to other states as a starting point for application of the research products herein. They show that the age-dependent TPM is able to realistically replicate deterioration for the do-nothing case, particularly the behavior of faster deterioration while aging. They also demonstrate that TPMs for different renewal construction work are able to contrast their effectiveness, such as micro-silica overlays vs. sealing for a concrete deck.
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Saadeh, Shadi, und Maria El Asmar. Sensitivity Analysis of the IDEAL CT Test Using the Distinct Element Method. Mineta Transporation Institute, September 2023. http://dx.doi.org/10.31979/mti.2023.2243.
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Cracking is a primary mode of failure for asphalt concrete (AC), resulting in road damage and deterioration, and leading to an increase in road hazards and fatalities. Studying the fracture behavior of AC is an effective way to learn how to best enhance their cracking resistance. To do this, the indirect tensile cracking laboratory test (IDEAL-CT) was developed and used to assess the AC cracking behavior by defining a unique index that allows the ranking of different mixes’ cracking resistance. The sensitivity of the test results to the test parameters is needed to monitor the test’s performance. Several parameters impact the result of the IDEAL-CT. This study focuses on the variation of air voids, loading rate, aggregate shape, bonding type, and gradation mix. Performing more than 450 test scenarios—varying multiple factors and conducting enough tests for each variation—would require considerable resources and time. To solve the issue, the Particle Flow Code in two-dimension software (PFC2D) using the discrete element method (DEM) is adapted to mitigate the need for actual laboratory tests. Initial findings yielded a better understanding of the micromechanical behavior of each mix, showing that air void content has more impact than loading rate; a decrease of 2% in air voids resulted in an increase of more than 50% in cracking resistance. Additionally, different aggregate sources and bonding strengths affected the cracking resistance. These results can inform further studies on AC cracking in order to reduce road damage and deterioration to keep roads safe.
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Christine, Lozano, und Riveros Guillermo. Classical and innovative methods of fatigue and fracture repairs in navigation steel structures. Engineer Research and Development Center (U.S.), April 2021. http://dx.doi.org/10.21079/11681/40422.
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Most of the hydraulic steel structures (HSS) in the U.S. have reached or have past their design life, which leads to unsatisfactory performance. Welded connections with low fatigue resistance, poor weld quality, unanticipated structural behavior, or unexpected loading due to the deterioration of the design boundary conditions are the causes of fatigue cracking. The purpose of this report is to identify and evaluate the traditional and new methods used for fatigue and fracture repairs in navigation steel structures to restore their load carrying capacity and fatigue and fracture resistance. The final objective was to generate a guidance report comprising of recommended and more efficient repair methods for the different fatigue limit states observed in navigation steel structures.
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Andrawes, Bassem, Ernesto Perez Claros und Zige Zhang. Bond Characteristics and Experimental Behavior of Textured Epoxy-coated Rebars Used in Concrete Bridge Decks. Illinois Center for Transportation, Januar 2022. http://dx.doi.org/10.36501/0197-9191/22-001.
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The deterioration of bridge decks is a problem typically associated with the corrosion of the reinforcing steel. This issue was partially controlled during the 1970s with the incorporation of the epoxy-coating protection system. However, research later demonstrated that the smooth surface resulting from the epoxy-coating application reduces most of the friction between the rebar and the surrounding concrete. Consequently, forces acting on the rib faces are reconfigured in such a way that the radial components increase, triggering the early development of cracks. To mitigate both the reduction of bonding and the formation of cracks, the Illinois Department of Transportation proposed a new type of coated bars: textured epoxy-coated (TEC) bars. Over the last few years, different projects have been executed to understand and improve the characteristics of TEC rebars. This report is a continuation of research performed at the University of Illinois Urbana-Champaign to evaluate the bond behavior of TEC bars. The experimental program starts by characterizing, qualitatively and quantitatively, the roughness of the TEC rebars. Next, their bond-slip interaction embedded in concrete is evaluated through pull-out tests. Finite element models of these tests are developed to validate the behavior observed as the textured reinforcement loses anchorage with concrete. Based on these results, the experimental program then aims to study the impact of the drying shrinkage, temperature change, and flexural demands on two large-scale bridge deck specimens reinforced, individually, with TEC and standard epoxy-coated bars. The results collected from both specimens using digital image correlation and strain gauges are compared to explore the differences exhibited by the traditional and the new type of reinforcement coatings in terms of stress distribution in bridge decks. Finally, given the specialized equipment and time-consuming procedure needed to calculate the roughness parameters of TEC bars, an empirical, weight-based approach is developed as a rapid method for assessing the rebars’ roughness on-site.
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Talvi, Ernesto. Fiscal Policy and the Business Cycle Associated with Exchange Rate-Based Stabilizations: Evidence from Uruguay's 1978 and 1991 Programs. Inter-American Development Bank, November 1995. http://dx.doi.org/10.18235/0010987.
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The initial stages of exchange rate-based stabilizations have been generally characterized by a consumption boom, a deterioration of the trade balance and the current account, and an appreciation of the real exchange rate. It is only at the later stages that the economy falls into recession. Tax revenues are linked to consumption (through the VAT, sales taxes, and import tariffs), and the consumption boom should therefore generate an endogenous increase in tax revenues. Furthermore, since many countries that have attempted these programs were heavily indebted, the appreciation of the real exchange rate should generate an endogenous reduction in real interest payments. The endogenous improvement in the fiscal balance that may occur due to forces unleashed in the initial stages of an exchange rate-based stabilization program turn it into an inappropriate measure of fiscal performance. This paper documents the links between the business cycle associated with exchange-rate based stabilizations and the behavior of tax revenues, government expenditures, and the fiscal deficit.
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Nantung, Tommy E., Jusang Lee, John E. Haddock, M. Reza Pouranian, Dario Batioja Alvarez, Jongmyung Jeon, Boonam Shin und Peter J. Becker. Structural Evaluation of Full-Depth Flexible Pavement Using APT. Purdue University, 2021. http://dx.doi.org/10.5703/1288284317319.
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The fundamentals of rutting behavior for thin full-depth flexible pavements (i.e., asphalt thickness less than 12 inches) are investigated in this study. The scope incorporates an experimental study using full-scale Accelerated Pavement Tests (APTs) to monitor the evolution of each pavement structural layer's transverse profiles. The findings were then employed to verify the local rutting model coefficients used in the current pavement design method, the Mechanistic-Empirical Pavement Design Guide (MEPDG). Four APT sections were constructed using two thin typical pavement structures (seven-and ten-inches thick) and two types of surface course material (dense-graded and SMA). A mid-depth rut monitoring and automated laser profile systems were designed to reconstruct the transverse profiles at each pavement layer interface throughout the process of accelerated pavement deterioration that is produced during the APT. The contributions of each pavement structural layer to rutting and the evolution of layer deformation were derived. This study found that the permanent deformation within full-depth asphalt concrete significantly depends upon the pavement thickness. However, once the pavement reaches sufficient thickness (more than 12.5 inches), increasing the thickness does not significantly affect the permanent deformation. Additionally, for thin full-depth asphalt pavements with a dense-graded Hot Mix Asphalt (HMA) surface course, most pavement rutting is caused by the deformation of the asphalt concrete, with about half the rutting amount observed within the top four inches of the pavement layers. However, for thin full-depth asphalt pavements with an SMA surface course, most pavement rutting comes from the closet sublayer to the surface, i.e., the intermediate layer. The accuracy of the MEPDG’s prediction models for thin full-depth asphalt pavement was evaluated using some statistical parameters, including bias, the sum of squared error, and the standard error of estimates between the predicted and actual measurements. Based on the statistical analysis (at the 95% confidence level), no significant difference was found between the version 2.3-predicted and measured rutting of total asphalt concrete layer and subgrade for thick and thin pavements.
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Hefetz, Abraham, und Gene Robinson. Hormonal and Pheromonal Regulation of Reproduction in the Bumble Bee Bombus terrestris. United States Department of Agriculture, Juli 1994. http://dx.doi.org/10.32747/1994.7568775.bard.
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Bombus terrestris constitute important pollinators of greenhouse crops. In Israel the species utilized is, whose colonies are reared commercially. This is a primitively social species with a particular colony development. It encompasses two social phases: a eusocial phase in which the queen dominates reproduction, and a competition phase in which workers compete with the queen for the parentage of males. These workers are distinguished by accelerated ovarian development, high production of JH, and elevated levels of dopamine in the brain. Queen-worker conflict is also manifested in overt aggression among all members of the nest. High aggression is correlated with dominance status of the bees and is also correlated with octopamine levels in the brain. After verifying that JH III is the only JH produced by the bees and validating the assay for its measurements (RCA & RIA), we used JH as an indicator of worker reproduction. Queens taken from colonies both before and after the competition phase were equally effective in inhibiting worker reproduction. Moreover, there is only a narrow window, around the competition point, in which workers may have the opportunity to initiate reproduction. Before that point they are inhibited by the dominant queen, while after that point both the queen and those workers with accelerated ovarian development exert strong inhibition on worker nest mates. Thus, "queen dominance deterioration" is not the primary cause in eliciting the queen-worker conflict. Queens convey their presence by means of a chemical signal that is extractable in organic solvent and that is normally spread on the cuticle. Total body extract and body washes, applied on dead virgin queens, were able to inhibit the release of JHin vitro in queenless workers. However, none of the prominent exocrine gland investigated mimicked this function. It is possible that the source of the putative pheromone is an unknown gland, or that it emanates from an assembly of glands. Chemical analyses of the prominent glands revealed a plethora of compounds the function of which should be further investigated. Understanding the social behavior of B. terrestris paves the way to facilitate colony manipulation and to adjust the colonies for specific pollination requirements.
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Miall, Naomi, Gillian Fergie und Anna Pearce. Health Inequalities in Scotland: trends in deaths, health and wellbeing, health behaviours, and health services since 2000. University of Glasgow, November 2022. http://dx.doi.org/10.36399/gla.pubs.282637.
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Following a global pandemic and entering a cost-of-living crisis, concern around how health inequalities in Scotland have and will be impacted is considerable. This report synthesises a wide range of existing data and new analysis to establish the magnitude of the problem, where improvements or deterioration is evident and who is most affected. Over four detailed chapters, trends in social inequalities in health, health-related behaviours and, health and social care services in Scotland are presented.