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Статті в журналах з теми "Mechanical stre"
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Ma, Rong, Anna V. Kellner, Victor Pui-Yan Ma, Hanquan Su, Brendan R. Deal, Joshua M. Brockman, and Khalid Salaita. "DNA probes that store mechanical information reveal transient piconewton forces applied by T cells." Proceedings of the National Academy of Sciences 116, no. 34 (August 7, 2019): 16949–54. http://dx.doi.org/10.1073/pnas.1904034116.
Повний текст джерелаАнотація:
The advent of molecular tension probes for real-time mapping of piconewton forces in living systems has had a major impact on mechanobiology. For example, DNA-based tension probes have revealed roles for mechanics in platelet, B cell, T cell, and fibroblast function. Nonetheless, imaging short-lived forces transmitted by low-abundance receptors remains a challenge. This is a particular problem for mechanoimmunology where ligand–receptor bindings are short lived, and a few antigens are sufficient for cell triggering. Herein, we present a mechanoselection strategy that uses locking oligonucleotides to preferentially and irreversibly bind DNA probes that are mechanically strained over probes at rest. Thus, infrequent and short-lived mechanical events are tagged. This strategy allows for integration and storage of mechanical information into a map of molecular tension history. Upon addition of unlocking oligonucleotides that drive toehold-mediated strand displacement, the probes reset to the real-time state, thereby erasing stored mechanical information. As a proof of concept, we applied this strategy to study OT-1 T cells, revealing that the T cell receptor (TCR) mechanically samples antigens carrying single amino acid mutations. Such events are not detectable using conventional tension probes. Each mutant peptide ligand displayed a different level of mechanical sampling and spatial scanning by the TCR that strongly correlated with its functional potency. Finally, we show evidence that T cells transmit pN forces through the programmed cell death receptor-1 (PD1), a major target in cancer immunotherapy. We anticipate that mechanical information storage will be broadly useful in studying the mechanobiology of the immune system.
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Schmitt, Philip, Hannes Mehner, and Martin Hoffmann. "A Micromechanical Binary Counter with MEMS-Based Digital-to-Analog Converter." Proceedings 2, no. 13 (November 21, 2018): 807. http://dx.doi.org/10.3390/proceedings2130807.
Повний текст джерелаАнотація:
Autonomous sensors are of interest in all cases where a continuous power source is not available or difficult to realize. Besides harvesting of electrical energy for a complex storage system, it is of interest to directly store an event in a non-electrical storage, but in a way that allows a later electrical read-out. Therefore, a miniaturized micromechanical binary counter is presented, which enables counting of threshold events, such as exceeding temperature limits or high mechanical shocks. An electro-mechanical digital-to-analog converter integrated in the binary counter is demonstrated as an option for monolithic electrical read-out of the mechanically stored information.
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Vinson, V. J. "Monitoring Cellular Mechanical Stress." Science's STKE 2007, no. 398 (July 31, 2007): tw287. http://dx.doi.org/10.1126/stke.3982007tw287.
Повний текст джерела
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Hughes-Fulford, M. "Signal Transduction and Mechanical Stress." Science Signaling 2004, no. 249 (August 31, 2004): re12. http://dx.doi.org/10.1126/stke.2492004re12.
Повний текст джерела
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Kosowatz, John. "Watts in Store." Mechanical Engineering 144, no. 2 (February 13, 2022): 31–35. http://dx.doi.org/10.1115/1.2022-mar1.
Повний текст джерелаАнотація:
Abstract Lithium-ion batteries are reliable and getting progressively cheaper, but generally deliver full power capacity for no more than four hours. But for renewable energy to fully replace fossil fuels, energy storage systems must advance to provide long and longer-term storage capability, and then deliver it on demand. There are a variety of technologies being developed for long-term storage, generally recognized as six to 12 hours.
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Nielsen, Steen. "Economic assessment of sludge handling and environmental impact of sludge treatment in a reed bed system." Water Science and Technology 71, no. 9 (February 16, 2015): 1286–92. http://dx.doi.org/10.2166/wst.2015.072.
Повний текст джерелаАнотація:
The effect on the environment of the establishment and operation of a sludge treatment reed bed system (STRB) is quite limited compared to mechanical sludge dewatering, with its accompanying use of energy and chemicals. The assessment presented here of the investment, operation and maintenance costs of a typical STRB, and of the related environmental impact, is based on the experiences gained from the operation of a large number of STRB in Denmark. There are differences in the environmental perspectives and costs involved in mechanical sludge dewatering and disposal on agricultural land compared to STRB. The two treatment methods were considered for comparison based on a treatment capacity of 550 tons of dry solids per year and with land application of the biosolids in Denmark. The initial capital cost for STRB is higher than a conventional mechanical system; however, an STRB would provide significant power and operating-cost savings, with a significant saving in the overall cost of the plant over 20–30 years. The assessment focuses on the use of chemicals, energy and greenhouse gas emissions and includes emptying, sludge residue quality and recycling. STRB with direct land application is the most cost-effective scenario and has the lowest environmental impact. A sludge strategy consisting of an STRB will be approximately DKK 536,894–647,636 cheaper per year than the option consisting of a new screw press or decanter.
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Wu, Yi, Chun Yang, Guang Xing Li, and Chun Mei Zhang. "Study on Mechanical Performances of Steel Truss Reinforced Concrete Transfer Beam." Advanced Materials Research 368-373 (October 2011): 299–302. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.299.
Повний текст джерелаАнотація:
Experimental researches of one 1:6 scale steel truss reinforced concrete (STRC) transfer beam were carried out to investigate mechanical performances of a transfer beam under vertical loads in an actual tall building. The development of crack along the beam, strains of reinforcements and steel truss, and the force transference mechanism of the deep beam were analyzed. Experimental results showed that the bearing capacity and rigidity of the STRC transfer beam are significantly enhanced compared with normal RC transfer beam. The strut-and-tie force transference mechanism is formed in the STRC transfer beam and fully made use of by the STRC transfer beam. And results verified that the shortest and most direct force transference path can be achieved to transfer upper loads.
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Petersen, Jan, Sebastian Geier, Peter Wierach, and Martin Wiedemann. "In situ mechanical and electrical characterization of composite-integrated thin film-supercapacitors." MATEC Web of Conferences 188 (2018): 01028. http://dx.doi.org/10.1051/matecconf/201818801028.
Повний текст джерелаАнотація:
Future transport systems will be powered more and more electrically. Generally the energy is stored in batteries. To reduce system weight and volume, multifunctional materials could be the answer. Therefore materials with the capability to store electric energy and to bear mechanical loads, need to be investigated to understand the effect of mechanical load on such structural integrated energy storage devices. In this work a thin film-supercapacitor is build up and integrated within a composite structure. The capacitor is developed to withstand the manufacturing process of a glass-fibre reinforced polymer and to carry mechanical loads, while simultaneously storing electrical energy. By using a supercapacitor housing, which is compatible to epoxy resin, a strong bonding is achieved, leading to a mechanical robust multifunctional composite. An electrolyte with large temperature window, low vapour pressure and the compatibility to a carbon based electrodes is chosen, to meet the requirement regarding the manufacturing process of the supercapacitor itself and the fibre reinforced composite. The composites with integrated thin film-supercapacitor as well as a set of reference samples are mechanically characterised in tensile and four-point bending test. In situ measurements are performed to investigate the influence of mechanical load on the electrical performance.
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Perkins, Michelle. "Minding the Nuclear Store." Mechanical Engineering 121, no. 03 (March 1, 1999): 68–69. http://dx.doi.org/10.1115/1.1999-mar-5.
Повний текст джерелаАнотація:
A model from Los Alamos studies the deformation of a hypothetical nuclear device when it collides with a steel plate. This shows that simulations play a key role in establishing the reliability of nuclear weapons. The scientists at Los Alamos, Sandia, and Lawrence Livermore labs are turning to huge computers and advanced visualization software to test virtual models. Visualizing and analyzing the data generated by the computational models overwhelm traditional scientific visualization methods. Scientists at Sandia National Laboratories are using computer simulations to test whether the Navy’s W76 nuclear warhead could still function amid blasts of X-rays on a nuclear battlefield. The simulations try to mathematically predict what real X-rays would do as they go through the W76's electronic circuits. Real world tests are run with weaker X-rays and the results are compared with the computer simulations. Data from old underground nuclear tests are also used to validate the computer tests.
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Collin, E. "Mesoscopic quantum thermo-mechanics: A new frontier of experimental physics." AVS Quantum Science 4, no. 2 (June 2022): 020501. http://dx.doi.org/10.1116/5.0086059.
Повний текст джерелаАнотація:
In the last decade, experimentalists have demonstrated their impressive ability to control mechanical modes within mesoscopic objects down to the quantum level: it is now possible to create mechanical Fock states, to entangle mechanical modes from distinct objects, and to store quantum information or transfer it from one quantum bit to another, among the many possibilities found in today's literature. Indeed, mechanics is quantum, very much like spins or electromagnetic degrees of freedom; and all of this is, in particular, referred to as a new engineering resource for quantum technologies. However, there is also much more beyond this utilitarian aspect: invoking the original discussions of Braginsky and Caves, where a quantum oscillator is thought of as a quantum detector for a classical field, namely, a gravitational wave, which is also a unique sensing capability for quantum fields. The subject of study is then the baths to which the mechanical mode is coupled to, let them be known or unknown in nature. This Perspective is about this new potentiality that addresses stochastic thermodynamics, potentially down to its quantum version, the search for a fundamental underlying (random) field postulated in recent theories that can be affiliated to the class of the wave-function collapse models, and more generally open questions of condensed matter like the actual nature of the elusive (and ubiquitous) two-level systems present within all mechanical objects. However, such research turns out to be much more demanding than the use of a few quantum mechanical modes: all the known baths have to be identified, experiments have to be conducted in-equilibrium, and the word “mechanics” needs to be justified by a real ability to move substantially the center-of-mass when a proper drive tone is applied to the system.
Дисертації з теми "Mechanical stre"
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DE, ZIO Elena. "The responses of poplar plants to mechanical bending stress." Doctoral thesis, Università degli studi del Molise, 2017. http://hdl.handle.net/11695/82358.
Повний текст джерелаАнотація:
Lo stress meccanico è un comune stress abiotico che può considerevolmente compromettere la stabilità delle piante. Nel corso dell’evoluzione, le piante hanno evoluto diversi meccanismi atti a contrastare e/o mitigare gli effetti negativi di questo disagevole stress ambientale. Studiare l’impatto di questo stress sulle piante legnose significa fornire delle basi scientifiche sulla conoscenza della biologia della radice e sulle complesse dinamiche della formazione del legno di reazione, importante nel contesto della produttività e dell’utilizzo delle piante stesse.
In questa tesi, una simulazione controllata dello stress meccanico è stata eseguita su radici Populus nigra usando un semplice sistema sperimentale. Questa tesi offre un outline sui meccanismi molecolari che regolano le risposte a lungo termine al bending, evidenziando le differenze tra i due lati della radice di pioppo (lato concavo e lato convesso) ed indaga, in particolar modo, il ruolo dei principali fitormoni coinvolti nella formazione del legno di reazione indotto dalla condizione di stress.
Usando un metodo basato sulla cromatografia liquida accoppiata alla spettroscopia di massa (LC-MS/MS), è stato ottenuto il profiling ormonale dell’auxina, dell’acido abscissico e delle citochinine per differenti settori e lati del fittone e del fusto di pioppo, sottoposti a differenti intensità delle forze di tensione e compressione. I dati ottenuti sono stati comparati per verificare le similitudini e le differenze della risposta al bending della radice e del fusto di pioppo.
Inoltre, al fine di approfondire il ruolo degli ormoni nell’induzione della zona cambiale della radice di pioppo sottoposta a bending, un’analisi ormonale tessuto-specifica è stata eseguita dopo la messa a punto di un metodo per l’isolamento del tessuto cambiale.
Complessivamente, i dati ottenuti in questa tesi mostrano che la radice di pioppo risponde al bending producendo nella zona concava un legno di compressione, ricco di lignina, con caratteristiche simili al legno di compressione prodotto a livello del fusto nelle gimnosperme. Un alto livello di auxina ed acido abscissico sembra accompagnare questo processo di sviluppo, sin dalle fasi precoci del trattamento.Mechanical stress is a common environmental perturbation that can considerably affect plant stability. In the course of evolution, plants evolved different mechanisms for coping with and mitigating the negative effects of this disadvantageous abiotic stress. Study the impact of this stress on the woody plant means to provide a scientific basis in the knowledge of the root biology and complex dynamics of the reaction wood formation, important in the context of plant productivity and utilization. In this thesis, a controlled simulation of mechanical stress was performed in Populus nigra roots by using a simple experimental system. After giving an outline of the molecular mechanisms that regulate the responses to long-term bending stress between the two sides of the poplar root (the convex and the concave side), this thesis lays emphasis on the roles of main plant hormones in the stress-induced reaction wood formation. Using the method based on liquid chromatography coupled to tandem mass spectrometry analysis (LC-MS/MS) auxins, abscisic acid and cytokinins profiling was obtained for different sectors and sides of the bent root and stem, subjected to different intensities of tension and compression forces. Data obtained were then compared in order to verify similarities and differences between root and stem response to bending. In order to better understand the role of hormones in the induction of cambial zone of poplar root subjected to bending, a method for isolation of cambial tissue was developed and the analysis of auxins, abscisic acid and cytokinins profile was carried out. Taking together, data of this thesis showed as poplar root responds to bending producing in the concave zone a compression wood, rich in lignin content, with features similar to the compression wood produced at stem level by gymnosperms. A high level of auxin and abscisic acid seems to accompany this development process, even in the early phases of the treatment.
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Lahoori, Mojdeh. "Thermo-hydro-mechanical behavior of an embankment to store thermal energy." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0252.
Повний текст джерелаАнотація:
Le stockage de chaleur dans des géostructures énergétiques telles que des remblais est réalisable en installant des échangeurs horizontaux au sein des différentes couches de sol compacté. Dans ce système, l'énergie thermique qui est injectée en été via un fluide caloporteur circulant dans les échangeurs de chaleur, peut être extraite en période hivernale. Dans ces conditions, lors de la mise en service, le sol compacté est soumis à des variations de température quotidiennes et saisonnières. Ces variations pourraient modifier les performances thermo-hydro-mécaniques du sol compacté. Ainsi, le but de cette étude est d'étudier les performances thermiques et mécaniques d'un sol compacté lorsqu'il est soumis à des variations de température monotones et cycliques. Le sol étudié est un limon fréquemment utilisé dans les constructions de remblais en France. Le comportement thermique et mécanique du sol est étudié à un état de compactage correspondant aux propriétés thermiques optimales. Dans cet état, le sol compacté est non saturé ce qui complexifie l'estimation de ses propriétés thermiques. Pour pallier à ces difficultés, dans cette étude, un modèle inverse est proposé pour estimer les propriétés thermiques du sol compacté. L’efficacité du modèle est testée sur un jeu de données acquises dans la gamme de 20 à 50 °C dans un modèle réduit en laboratoire. Les valeurs obtenues sont ensuite comparées à des mesures classiques en laboratoire (méthodes en régime transitoire et en régime permanent). Cette méthode pourrait permettre de suivre l’évolution des propriétés thermiques du stockage et ainsi assurer son efficacité tout au long de sa durée de vie. La question de la stabilité à long terme de ces structures soumises à des variations thermiques monotones (5, 20 et 50 °C) et cycliques (5 à 50 °C) est ensuite abordée à l'aide d'essais oedomètriques et d’essais de cisaillement direct à température contrôlée. Les résultats des essais de compressibilité ont montré que l'effet de la variation de température est plus prononcé sous une contrainte verticale supérieure à la pression de préconsolidation. Les indices de compression et de gonflement peuvent être considérés comme indépendants des variations de température. Donc le tassement global du remblai dû aux variations thermiques pourrait être considéré comme négligeable. Les résultats des essais de cisaillement direct ont montré que les variations de température (monotones ou cycliques) augmentent la cohésion ce qui est avantageux pour la capacité portante et la stabilité des pentes des remblais. Dans la phase de conception d'un remblai de stockage, ces résultats seraient utiles au dimensionnement du système si des trajectoires thermomécaniques similaires à celles de cette étude sont respectées. Dans une dernière partie, une simulation numérique prenant en compte l'interaction sol-atmosphère est réalisée afin d’évaluer la performance thermique de ce sol compacté en conditions naturelles. Différentes profondeurs d'installation de boucles d'échangeurs de chaleur sont testéss ainsi que différents scénarios de stockage. Les résultats ont montré que le sol compacté augmente de 8.5% les performances du système par rapport à l'installation d'une boucle horizontale dans le sol naturel (non compacté). Les résultats de deux scénarios différents ont montré qu’en été avec un fluide ayant une température d'entrée de 50 °C augmente significativement la performance du système. De plus, une installation plus profonde des boucles horizontales améliore également la performance du système. Il convient de noter que le remblai est en interaction avec l'atmosphère depuis ses surfaces supérieure et latérale, l'efficacité thermique de la structure pourrait être affectée en raison des pertes de chaleur. Par conséquent, il est préférable de placer les échangeurs de chaleur loin des surfaces supérieures et latéralesNowadays, thermal energy storage in geostructures like embankments can be possible by installing the horizontal heat exchangers in different layers of compacted soil. In this system, the thermal energy is stored in summer via a fluid, circulating in the heat exchangers, to be extracted in the demand period. When the serviceability of embankment as a medium to store the thermal energy starts, the compacted soil will be subjected to the daily and seasonally temperature variations. These seasonal temperature variations could modify the thermo-hydro-mechanical performance of the compacted soil. Thus, the aim of this study is to investigate the thermal and mechanical performances of a compacted soil when it is subjected to monotonic and cyclic temperature variations. The studied soil is a sandy lean clay that is frequently used in embankment constructions in France. The thermal and mechanical behavior of the soil are investigated at a compaction state corresponding to the optimal thermal properties. However, this compacted soil is unsaturated and the estimation of its thermal properties is complex. In this study, an inverse analytical model is proposed to estimate the thermal properties of the soil using temperature monitoring in the range of 20 to 50 °C in a soil compacted in a large container. The estimated thermal parameters were compared to classical laboratory measurements (transient and steady-state methods). The comparison showed that the estimated values were close to the results obtained in transient laboratory method. Using this method, the thermal efficiency of the compacted soil can be verified in the lifetime of the storage system. To ensure the structure stability, long-term mechanical response of these systems subjected to monotonic and cyclic temperature variations should be investigated. To achieve this aim, using temperature-controlled oedometric and direct shear devices, consolidation and shear parameters of the studied soil at different monotonic (5, 20, and 50 °C) and cyclic (5 to 50 °C) temperatures were investigated. The results of temperature-controlled oedometric tests showed that the effect of the temperature variation is more pronounced under vertical pressures higher than the preconsolidation pressure. The compression and swelling indexes could be considered independent of temperature variations. Therefore, the overall settlement of the embankment due to thermal variation near the heat exchangers could be considered negligible. The results of temperature-controlled direct shear tests showed that the temperature variations (monotonic heating or cooling, or temperature cycles) increased the cohesion which is beneficial for the bearing capacity and slope stability of embankments. These results can be directly used in the design of embankments to store thermal energy exposed to similar thermo-mechanical paths. Finally, the thermal performance of the compacted soil is verified using a numerical simulation considering the soil atmosphere interaction. Different depths installation of heat exchanger loops and different heat storage scenarios were simulated. The results showed that the compacted soil increases 8.5% the systems performance compared to the horizontal loop installation in the local soil. The results of two different scenarios show that an inlet fluid temperature of 50 °C in summer increases highly the system performance (13.7% to 41.4%) while the improvement is less significant (0% to 4.8%) for the ambient inlet temperature. Moreover, a deeper installation of horizontal loops increases the system performance. From the numerical simulation results can be concealed that the embankment is in interaction with the atmosphere from its upper and lateral surfaces, the thermal efficiency of the structure could be affected due to heat losses. Therefore, it is preferable to place the heat exchangers away from the top and side surfaces
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LIONETTI, MARIA CHIARA. "LAMINOPATHIES: PATHOLOGY, CELL MECHANICS ANDENVIRONMENTAL INDUCTION." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/620532.
Повний текст джерелаАнотація:
La lamina nucleare (NL) è un reticolo di proteine fibrillari che riveste la superficie interna della
membrana nucleare. Essa è principalmente composta da filamenti intermedi di tipo V , chiamati
lamìne, e proteine ausiliari ad esse associate (lamin-associated proteins, LAPs). Nei mammiferi le
lamìne sono codificate da tre geni : LMNA, che codifica per la lamìna A e lamìna C (lamìne di tipo
A), LMNB1 e LMNB2 che codificano rispettivamente per la lamìna B1 e B2 (lamìne di tipo B).
Lamìne e LAPs si associano a formare una matrice tridimensionale densa e dinamica che stabilisce
numerose interazioni, sia stabili che transitorie, con diverse classi di molecole biologiche: DNA,
fattori di trascrizione, proteine strutturali. Tutte queste interazioni sono essenziali per fornire
stabilità strutturale e preservare l’integrità nucleare, per collegare fisicamente e funzionalmente la
lamina nucleare al citoscheletro e per organizzare la cromatina. In questo modo, oltre a svolgere un
ruolo strutturale fondamentale, la lamina nucleare risulta ricoprire ruoli chiave anche nei processi di
meccanotrasduzione del segnale e nella regolazione dell’espressione genica ed epigenetica.
Mutazioni a carico dei geni che codificano per le lamìne nucleari sono associate ad un'ampia ed
etogenea classe di patologie note come laminopatie. Tra queste, una delle più controverse ed
interessanti è la Hutchison-Gillford Progeria Syndrome (HGPS), una malattia genetica rara dovuta a
una mutazione puntiforme nel gene LMNA. Tale mutazione risulta nella produzione di una versione
tronca della lamìna A, mancante di 50 amminoacidi, conosciuta come Progerina. HGPS è
principalmente caratterizzata da alterazioni morfologiche del nucleo e invecchiamento precoce. I
soggetti affetti da Progeria, infatti, fin dai primi anni di vita sviluppano condizioni patologiche
tipiche dell’età senile quali cataratta, diabete e l'osteoporosi pur preservando le normali funzioni
congnitive. Questi pazienti muoiono tipicamente per complicanze cardiovascolari intorno ai 14 anni di
età, in media.
Considerando la sindrome di Hutchinson-Guilford come un esempio estremo di ciò che alterazioni
della lamina nucleare comportano, durante il mio dottorato di ricerca ho investigato diversi aspetti
riguardanti la biologia della lamina nucleare con particolare interesse all'impatto che perturbazioni
strutturali della lamina nucleare possono avere sulle normali funzioni cellulari, la meccanica
cellulare, la regolazione dell'espressione genica e l’ interconnessione esistente tra integrità della
lamina nucleare, processo di invecchiamento e stress ossidativo.
Per ottenere una visione d’insieme del contributo della lamina nucleare sia in condizioni fisiologiche
che patologiche, sono state adottate strategie di ricerca basate su approcci interdisciplinari e
integrativi in grado di tenere conto degli aspetti strutturali, meccanici e molecolari.
Per fa questo, in prima instanza sono state effetuate delle analisi bionformatiche: tutti i dati di
trascrittomica relativi a pazienti HGPS, presenti in database pubblici e in letteratura, sono stati
raccolti e analizzati rispetto a dati equivalenti ottenuti da controlli sani.
Tale analisi ha permesso di delineare profilo di espressione genica tipico di pazienti HGPS e di
individuare i pathways deregolati in presenza della patologia.
È stato inoltre studiato l’impatto che alterazioni della lamina nucleare hanno sulle connessioni
fisiche e funzionali che questa stabilisce sia con elementi nucleari ed extra-nucleari, in un modello
cellulare in cui è possibile indurre sperimentalmente, in modo controllato, l’espressione della forma
mutata di Lamìn A responsabile dell’ HGPS. Tale modello cellulare ricapitola fedelmente il peculiare
fenotipo cellulare dei pazienti risultando essere una valida alternativa all’utilizzo di linee primarie
derivanti dai pazienti.
Infine, l'interdipendenza tra stress ossidativo, invecchiamento e lamìne nucleari è stata investigata in
un nuovo modello cellulare di stress ossidativo sviluppato nel nostro laboratorio, efficiente nel
ricapitolare il processo di invecchiamento, in vitro.ABSTRACT The nuclear lamina (NL) is a fibrillary protein network lining the inner surface of the nuclear envelope. It is mainly composed by type V intermediate filaments called lamins and lamin-associated proteins. Three lamin genes are present in Mammals: LMNA, which encodes lamin A and lamin C (Atype lamins), as well as, LMNB1 and LMNB2 that encode lamin B1 and B2 (B-type lamins) respectively. Lamins and LAPs associate to form a dense and dynamic three-dimensional matrix that establishes a huge number of stable and transient interactions with different classes of molecules: DNA, transcription factors, nuclear pore complexes and structural proteins of the cytoskeleton. All of these interactions are essential to provide nuclear structural stability and integrity, to physically and functionally link nuclear lamina to the cytoskeleton and to organizes chromatin. Thus NL, in addition to play a fundamental structural role, it is also a key player in cellular mechanotransduction processes and gene expression and epigenetic regulation. Mutations in genes encoding for lamins are associated with a wide a range of diseases, named laminopathies. Among these, the most interesting one is Hutchison-Gilford Progeria Syndrome (HGPS), a rare fatal genetic disorder due to do a point mutation in LMNA. This mutation results in the production of a truncated version of lamina A, lacking 50 amino acids, known as Progerin. HGPS is mainly characterized by morphological changes in the nucleus and premature aging. HGPS patients indeed, from their first years of life, develop pathological conditions typical of the elderly such as cataracts, diabetes and osteoporosis while preserving the normal cognitive functions. These patients typically die from cardiovascular complications around 14 years of age, on average. Considering Hutchinson-Guilford Progeria Syndrome as an extreme example of what nuclear lamina aberration entails, during my PhD I investigated many aspects of nuclear lamina biology with particular regard to the impact of nuclear lamina structural perturbations on cell functions, mechanics, gene expression regulation and the interconnection existing between nuclear lamina integrity, ageing process and oxidative stress. Indeed, to gain a comprehensive picture of nuclear lamina biology in health and disease, it has been adopted interdisciplinary and integrative research strategies able to take into account structural, mechanical and molecular aspects. Bioinformatics study has been performed: public available transcriptomic data of HGPS patients have been analysed with respect of those of healthy matched controls. This analysis allowed to delineate the typical global gene expression profile of HGPS patients and to identify all the deregulated pathways in the presence of the pathology. Moreover, impacts of lamina alterations on its physical and functional connections with extra-nuclear and nuclear elements have been studied in an inducible expression cellular model of the mutated form of Lamin A responsible for HGPS. This cellular model faithfully recapitulates the peculiar cellular phenotype of the HGPS patients resulting to be a valid alternative to primary cell lines deriving from the patients.Finally, the interdependence between oxidative stress, ageing and lamins has been investigated in a novel oxidative stress cellular model developed in our laboratory, that is also efficient in recapitulating typical ageing profile.
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Ozyuksel, Alaettin Arda. "Development Of Sled Range Test Facility For Store Separation Model." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608508/index.pdf.
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The aim of this thesis is to develop a test facility in order to validate the safe separation of a store model from the aircraft model with the analysis of the acquired data. Different alternatives are considered in the conceptual design and a facility is selected which contains the rail constructed 5 meters above the ground. 300 meter test range is used to accelerate the aircraft model, attached to the carriage with solid rocket engines. The concept is to accelerate the carriage within the first 100 meters, to perform the separation
of the model at the desired velocity when the rocket engine is burned out, and in the last 100 meters, to decelerate the carriage in order to recover the models. After the parts of the carriage are designed with respect to the requirements of the separation and completing the similitude study of scaled models with the ratio of 1/8, separation tests are performed. These tests are constrained with 0.9 Mach due to the store and test aircraft limitations. Doppler radar is issued to measure the velocity and photogrammetry method is used to validate and analyze the separation and to obtain the vertical
trajectory of the store model. Measured trajectory of the store model is compared with the trajectory of the full scale store.
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Krishna, Jayanth. "Fatigue properties of Laser Powder Bed Fusion (LPBF) built 21-6-9 stainless stee." Thesis, Högskolan Väst, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16788.
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Fatigue performance is one of the important mechanical properties which is hindering some of the additive manufacturing build structures. The main objective of this study is to investigate the fatigue life dependence of the 21-6-9 austenitic stainless-steel build using the laser powder bed fusion (LPBF) technique. The study is mainly focused on the fracture surface based on defects and the micro constituents, how they are related to the fatigue performance of the samples. 21 samples were build using optimized process parameters in which 9 of the samples were built-in vertical direction and the remaining 12 were built in the horizontal direction. Low cycle fatigue (LCF) testing was carried out with the samples with 2 conditions i.e., room temperature 24⁰C and 750 ⁰C. Before the specimens were subjected to testing the samples were stress relived at 600⁰C for 2 hours. Fractography was carried out on the fracture surface to pinpoint the initiation sites (concluded by analyzing the striations) and the cause of failure. Microstructural characterization was carried out in both the vertical and the horizontal direction of the build. The fatigue crack growth initiated from the surface where defects were present, when the cyclic loads were applied the stress concentration at these regions caused the crack initiation to take place. In some cases, the defect size was smaller at the initiation site, and that correlated to increased fatigue life. To optimize the fatigue life of LPBF built 21-6-9 is important to minimize the grain size. However, the absence of defects is crucial as well, as those typically are the weakest link. Therefore, minimizing those during the manufacturing is essential.
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Bankston, Susan D. "Improving the consumer demand forecast to generate more accurate suggested orders at the store-item level." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43829.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2008.Includes bibliographical references (p. 57).
One of the biggest opportunities for this consumer goods company today is reducing retail stockouts at its Direct Store Delivery (DSD) customers via pre-selling, which represents approximately 70% of the company's total sales volume. But reducing retail stock-outs is becoming constantly more challenging with an ever-burgeoning number of SKUs due to new product introductions and packaging innovations. The main tool this consumer goods company uses to combat retail stock-outs is the pre-sell handheld, which the company provides to all field sales reps. The handheld runs proprietary software developed by this consumer goods company that creates suggested orders based on a number of factors including: * Baseline forecast (specific to store-item combination) * Seasonality effects (i.e., higher demand for products during particular seasons) * Promotional effects (i.e., lift created from sale prices) * Presence of in-store displays (i.e., more space for product than just shelf space) * Weekday effects (i.e., selling more on weekends when most people shop) * Holiday effects (i.e., higher demand for products at holidays) * Inventory levels on the shelves and in the back room * In-transit orders (i.e., orders that may already be on their way to the customer) The more accurate that the suggested orders are, the fewer retail stock-outs will occur. This project seeks to increase the accuracy of the consumer demand forecast, and ultimately the suggested orders, by improving the baseline forecast and accounting for the effect of cannibalization on demand.
by Susan D. Bankston.
S.M.
M.B.A.
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Almehmadi, Fahad. "Technology to Address Food Deserts: Hybrid Application of Combined Heat And Power Assisted by Solar Dehumidification for Corner Store Groceries." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1605543916479185.
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Spjutare, Christian. "Aerodynamic Loads on External Stores - Saab 39 Gripen : Evaluation of CFD methods for estimating loads on external stores." Thesis, Linköping University, Applied Thermodynamics and Fluid Mechanics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54127.
Повний текст джерелаАнотація:
External stores mounted on aircraft generate loads which need to be estimated before first takeoff. These loads can be measured in a wind tunnel but since the possible store configurations are basically endless, testing them all is neither economically feasible nor time efficient. Thus, scaling based on geometrical similarity is used. This can, however, be a crude method. Stores with similar geometrical properties can still behave in different ways due to aerodynamic interference caused by adjacent surfaces.
To improve the scaling performance, this work focuses on investigating two CFD codes, ADAPDT and Edge. The CFD simulations are used to derive the difference in aerodynamic coefficients, or the Δ-effect, between a reference store and the new untested store. The Δ-effect is then applied to an existing wind tunnel measurement of the reference store, yielding an estimation of the aerodynamic properties for the new store.
The results show that ADAPDT, using a coarse geometry representation, has large difficulties predicting the new store properties, even for a very simple store configuration on the aircraft. Therefore it is not suited to use as a scaling tool in its present condition. Edge on the other hand uses a more precise geometry representation and proves to deliver good estimations of the new store load behavior. Results are well balanced and mainly conservative. Some further work is needed to verify the performance but Edge is the recommended tool for scaling.
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Martins, Neto Jos? Ant?nio. "Desempenho mec?nico de comp?sitos h?bridos de fibras naturais e poli?ster n?o saturado." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15630.
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Previous issue date: 2010-12-30With the objective to promote sustainable development, the fibres found in nature in abundance, which are biodegradable, of low cost in comparison to synthetic fibres are being used in the manufacture of composites. The mechanical behavior of the curau? and pineapple leaf fibre (PALF) composites in different proportions, 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3) were respectively studied, being initially treated with a 2% aqueous solution of sodium hydroxide. Mechanical analyses indicated that with respect to studies of traction, for the combination of P1 and P3, better results of 22.17 MPa and 16.98 MPa, were obtained respectively, which are higher than that of the combination P2. The results of the same pattern were obtained for analysis of bending resistance where P1 is 1.21% and P3 represents 0.96%. In the case of resistance to bending, best results were obtained for the combination P1 at 49.07 MPa. However, when Young's modulus values were calculated, the values were different to the pattern of the results of other tests, where the combination P2 with the value of 4.06 GPa is greater than the other combinations. This shows that the PALF had a greater influence in relation to curau? fibre. The analysis of the results generally shows that in combinations of two vegetable fibers of cellulosic origin, the fiber which shows higher percentage (75%) is the best option than to the composition of 50%/50%. In the meantime, according to the results obtained in this study, in the case where the application should withstand bending loads, the better composition would be 50%/50%
Com o objetivo de promover o desenvolvimento sustent?vel, as fibras encontradas em abund?ncia na natureza, que s?o biodegrad?veis e de baixo custo quando comparado com as fibras sint?ticas, vem sendo utilizadas na aplica??o de produ??o de comp?sitos. Neste trabalho foi analisado o comportamento mec?nico ? partir do ensaio de tra??o e flex?o, em um comp?sito h?brido tendo como matriz uma resina sint?tica ortoft?lica refor?ada com fibras de curau? e fibras da folha de abacaxizeiro (PALF), nas propor??es de 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3), respectivamente, com as fibras de curau? e as fibras da folha do abacaxizeiro sendo tratadas quimicamente por uma solu??o aquosa de hidr?xido de s?dio (NaOH) com 8% de concentra??o. As an?lises mec?nicas indicaram que com rela??o aos estudos de tra??o, para a combina??o P1 e P3, foram obtidas melhores resultados de 22,17 MPa e 16,98 MPa, respectivamente, que ? maior que da outra combina??o de P2. Os resultados do mesmo padr?o foram obtidos para an?lise de flex?o onde P1 ? 1,21% e P3 de 0,96% que s?o maiores do que o resultado obtido da combina??o P2. No caso de resist?ncia ? flex?o, melhores resultados foram obtidos para a combina??o P1 de 49,07 MPa. Mas, quando foi calculado o m?dulo de Young, os valores foram diferentes do padr?o dos resultados dos outros testes realizados, com a combina??o P2 com o valor de 4,06 GPa que ? maior que das outras combina??es. Isto mostra que as fibras PALF tiveram uma influ?ncia maior com rela??o ? fibra de curau?. A an?lise dos resultados em geral demonstra que nas combina??es de duas fibras vegetais celul?sicas, uma ou a outra fibra com porcentagem maior (75%) ? a melhor op??o do que na composi??o de 50%/50%, entretanto no caso onde a aplica??o ser? para suportar cargas de flex?o, a melhor composi??o seria 50%/50%
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Bahman, Ammar. "Modeling of Solar-Powered Single-Effect Absorption Cooling System and Supermarket Refrigeration/HVAC System." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/2993.
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This thesis consists of two different research problems. In the first one, the aim is to model and simulate a solar-powered, single-effect, absorption refrigeration system using a flat-plate solar collector and LiBr-H2O mixture as the working fluid. The cooling capacity and the coefficient of performance of the system are analyzed by varying all independent parameters, namely: evaporator pressure, condenser pressure, mass flow rate, LiBr concentration, and inlet generator temperature. The cooling performance of the system is compared with conventional vapor-compression systems for different refrigerants (R-134a, R-32, and R-22). The cooling performance is also assessed for a typical year in Tampa, Florida. Higher COP values are obtained for a lower LiBr concentration in the solution. The effects of evaporator and condenser pressures on the cooling capacity and cooling performance are found to be negligible. The LiBr-H2O solution shows higher cooling performance compared to other mixtures under the same absorption cooling cycle conditions. For typical year in Tampa, Florida, the model shows a constant coefficient of performance of 0.94.
In the second problem, a numerical model is developed for a typical food retail store refrigeration/HVAC system to study the effects of indoor space conditions on supermarket energy consumption. Refrigerated display cases are normally rated at a store environment of 24ºC (75ºF) and a relative humidity of 55%. If the store can be maintained at lower relative humidity, significant quantities of refrigeration energy, defrost energy and anti-sweat heater energy can be saved. The numerical simulation is performed for a typical day in a standard store for each month of the year using the climate data for Tampa, Florida. This results in a 24 hour variation in the store relative humidity. Using these calculated hourly values of relative humidity for a typical 24 hour day, the store relative humidity distribution is calculated for a full year. The annual average supermarket relative humidity is found to be 51.1%. It is shown that for a 5% reduction in store relative humidity that the display case refrigeration load is reduced by 9.25%, and that results in total store energy load reduction of 4.84%. The results show good agreement with available experimental data.
Книги з теми "Mechanical stre"
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Benjamin, Wylie E., ed. Fluid mechanics. 8th ed. New York: McGraw-Hill, 1985.
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Benjamin, Wylie E., and Bedford Keith W, eds. Fluid mechanics. 9th ed. Boston: WCB/McGraw Hill, 1998.
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3
Debler, Walter R. Fluid mechanics fundamentals. Englewood Cliffs, N.J: Prentice Hall, 1990.
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Oertel, Herbert. Modelling the human cardiac fluid mechanics. 2nd ed. Karlsruhe: Univ.-Verl. Karlsruhe, 2006.
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Chevray, Rene. Topics in fluid mechanics. Cambridge, CB: Cambridge University Press, 1993.
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An introduction to fluid mechanics and transport phenomena. [Dordrecht]: Springer, 2008.
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C, Wiggert David, and Hondzo Midhat, eds. Mechanics of fluids. 2nd ed. New York: Prentice-Hall International, 1997.
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Potter, Merle C. Mechanics of fluids. 2nd ed. Upper Saddle River, NJ: Prentice Hall, 1997.
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Potter, Merle C. Mechanics of fluids. London: Prentice-Hall International, 1991.
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Potter, Merle C. Mechanics of fluids. Englewood Cliffs, N.J: Prentice Hall, 1991.
Знайти повний текст джерелаЧастини книг з теми "Mechanical stre"
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Yadav, Vinay Surendra, and A. R. Singh. "A Novel Discount Mechanism for Buy Online PickUp in Store (BOPS)." In Lecture Notes in Mechanical Engineering, 205–14. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-32-9931-3_21.
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Muñoz López, Natalia, José Luis Santolaya Sáenz, and Anna Biedermann. "Methodology of Product Sustainable Redesign. Case Study: Furniture of a Clothing Retail Store." In Lecture Notes in Mechanical Engineering, 175–81. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_28.
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AbstractCompanies awareness of the impact generated by its products increases and motivates them to develop initiatives to improve their sustainability. In this work, a methodology consisting of three main phases: sustainability assessment, redesign process and comparison of designs, is proposed to obtain more sustainable product designs. Methodology is based on the Life Cycle Sustainability Assessment (LCSA) approach, which is applied to simultaneously evaluate environmental, economic and social aspects. In the case study the sustainability improvement of the furniture of a clothing retail store is addressed. A set of indicators are considered to evaluate the sustainability performance of both initial design and redesign. The study concludes that the application of different sustainability strategies allows a significant enhancement of the environmental and economic indicators.
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Khalid, Sufia, Mohammad Sarfraz, Vishal Singh, Aafreen, and Ali Allahloh. "A Novel Model for IoT-Based Meter Using ATmega328P Microcontroller and Google Cloud Store." In Lecture Notes in Mechanical Engineering, 639–48. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5463-6_57.
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Nzetchou, Stéphane, Alexandre Durupt, Benoit Eynard, and Sébastien Remy. "Semantic Enrichment of 3D Models Based on Ontology Integration." In Lecture Notes in Mechanical Engineering, 341–46. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_54.
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AbstractThe rise of new technologies has led to a growth in the number of 3D models. They can come from various source, hence they are heterogeneous and complex. The level of 3D data access is often a function of the user’s expertise since the 3D data are often registered to different file formats. Some file formats do not show the data tree, as IGES. For using information inside a 3D model, that does not show a data tree, each company adopts his own system that will allow him to access easily to 3D model in order to exploit the hidden knowledge within the models. In this article, we are going to speak about technologies that helps user to exploit and knowledge coming from different file formats. In addition, we are going to present a system named VAQUERO that uses ontology to access, store and share knowledge coming from 3D models.
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Gupta, Sandeep Kumar, Sanjay Kumar Gupta, Renu Rana, Vinesh Kumar, Yimer Ayalew, and Tesfaye Nega Mekonen. "The Role of Effective Inventory Management System on Customers’ Satisfaction; The Case Study of Ethiopia Electric Utility, Northeast Region Store Dessie." In Lecture Notes in Mechanical Engineering, 139–58. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3330-0_13.
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Huet, Armand, Romain Pinquie, Philippe Veron, Frederic Segonds, and Victor Fau. "Design Rules Application in Manufacturing Industries: A State of the Art Survey and Proposal of a Context-Aware Approach." In Lecture Notes in Mechanical Engineering, 335–40. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_53.
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Abstract[Context] In manufacturing industries, the design of a product needs to comply with many design rules. These rules are essentials as they help industrial designers to create high quality design in an efficient way. [Problem] However, the management of an ever-increasing number of design rules becomes a real problem, especially for new designers. Even if there exists some knowledge management tools for design rules, their capabilities are still limited and many companies continue to store their design rules in unstructured documents. Nowadays, design rule application is still a difficult task that needs a circular validation process between many expert services in a manufacturing company. [Proposition] In this paper, we will analyze the main existing approaches for design rules application from which we will demonstrate the need of a new approach to improve the current state-of-the-art practices. To minimize rule application impact on the design process, we propose to develop a Context-Aware Design Assistant that will perform design rule recommendation on the fly while designing using computer-aided technologies. Our Design Assistant relies on the modelling of the design rules and the design context in a single knowledge graph that can fuel a recommendation engine. [Future Work] In future work, we will describe the technical structure of the Context-Aware Design Assistant and develop it. The potential outcome of this research are: a better workflow integration of design rules application, a proactive verification of design solutions, a continuous learning of design rules, the detection and automation of design routines.
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Reimer, Lars, Ralf Heinrich, and Rosemarie Meuer. "Validation of a Time-Domain TAU-Flight Dynamics Coupling Based on Store Release Scenarios." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 455–63. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-03158-3_46.
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Schade, N. "Simulation of Store Separation Scaling Requirements for Wind Tunnel Experiments and Validation of Numerical Simulations." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 17–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-35680-3_3.
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Allen, Alexander, Caroline Weishäupl, and Boris Laschka. "Flap efficiency of a delta wing with an external store using an Euler code for small disturbances." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 116–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-39604-8_15.
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Medlin, Dana J. "Failures of Mechanical Springs." In Analysis and Prevention of Component and Equipment Failures, 402–14. ASM International, 2021. http://dx.doi.org/10.31399/asm.hb.v11a.a0006836.
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Abstract Mechanical springs are used in mechanical components to exert force, provide flexibility, and absorb or store energy. This article provides an overview of the operating conditions of mechanical springs. Common failure mechanisms and processes involved in the examination of spring failures are also discussed. In addition, the article discusses common causes of failures and presents examples of specific spring failures, describes fatigue failures that resulted from these types of material defects, and demonstrates how improper fabrication can result in premature fatigue failure. It also covers failures of shape memory alloy springs and failures caused by corrosion and operating conditions.
Тези доповідей конференцій з теми "Mechanical stre"
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Terrell, Elon, and C. Fred Higgs. "A Multi-Physics Particle-Augmented Mixed Lubrication Modeling Approach for Studying CMP." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44487.
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An integrated multi-physics approach was taken in order to model the complex physics behind chemical-mechanical polishing (CMP). This model, known as the particle-augmented mixed lubrication model, accounts for the important mechanical interactions in CMP—namely, fluid mechanics, particle dynamics, contact mechanics, and wear—and incorporates all of them into an integrated algorithm. The compiled model is then simulated over a series of time steps in order to form a predictive tool for CMP.
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Buzio, Renato, Karolina Malyska, Zygmunt Rymuza, Corrado Boragno, Francesco Buatier de Mongeot, and Ugo Valbusa. "Nanoindentations on SrTiO3 Substrates: Effects of Fractal Roughness on Contact Mechanics." In STLE/ASME 2003 International Joint Tribology Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/2003-trib-0279.
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The non-stationary character of roughness is a widely recognized property of surface morphology and suggests modelling several solid surfaces by fractal geometry. In the field of contact mechanics this demands for novel investigations attempting to clarify the role of multi-scale roughness during physical contact. Here we propose an experimental investigation of the mechanical response of SrTiO3 substrates probed by a commercial nanoindentor. Load-displacement curves have been acquired respectively on well-defined crystalline surfaces and on mechanically lapped surfaces. We observe the first-loading cycles to be considerably affected by surface roughness whenever the penetration depth is kept below the interface width. The obtained results are analyzed within an elasto-plastic deformation model for fractal surfaces and a picture is developed to describe the deformation process with respect to surface roughness and structural parameters.
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Massi, Francesco, and Yves Berthier. "Coupling System Dynamics and Contact Behaviour by Numerical Modelling at Different Scales." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41055.
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When dealing with mechanical systems including contact interfaces, two different mechanics at two different time and length scales have to be accounted for: the contact mechanics and the structural mechanics. The mechanics of the contact and the mechanics of structure are coupled by friction (forces and moments), local body deformations and wear (geometrical coupling). In the past, dynamic and tribological problems were treated separately and the analysis was focused either on the mechanism scales or on the contact scales, as a function of the problem. The analysis of the dynamic response of the mechanical system accounted for the contact interfaces thought global coefficients (global contact stiffness, damping, energy loss factor, etc.); vice versa, the analysis of the local behaviour at the contact interface accounted for the system dynamics imposing global boundary conditions on the contact model (pressure distribution, relative velocities, etc.). During last decades mechanical system design led to a power increase and to a drastic optimization, increasing as well the number of contact interfaces between deformable bodies. Thus, the need for coupling dynamic and tribological analyses arises for solving and understanding either wear phenomena or dynamic response of a mechanical system. On this sense, experimental tools showed their limits on the estimation and prediction of friction and wear phenomena. This paper proposes a first step toward a more general approach aimed to couple the dynamic analysis of the mechanism with the local tribological analysis at the contact, by the coupling of two different numerical models dealing with the two different scales. Two applications are then mentioned: the analysis of “false Brinelling” wear and the understanding of brake squeal instability.
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Nosonovsky, Michael, and Vahid Mortazavi. "Pattern Formation During Frictional Mechanical Contact." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41219.
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Friction and wear are usually viewed as irreversible processes, which lead to energy dissipation (friction) and material deterioration (wear). On the other hand, it is known that under certain circumstances frictional sliding can provide mechanisms for the spatial and temporal pattern-formation (self-organization). We discuss the contact mechanics aspects of the pattern-formation and suggest quantitative metrics and criteria for this effect including the stability criteria for the transition from the steady-state sliding to pattern-formation.
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Kim, Sang-Woo, Seung-Hun Lee, Jun-Seok Park, and Seock-Sam Kim. "Thermo-Mechanical Wear Mechanisms of Ceramic Materials." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44145.
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This paper was investigated the thermo-mechanical wear mechanisms of ceramic materials under lubricated sliding condition based on the fracture mechanics. Thermo-mechanical wear model for ceramic materials was proposed, and non-dimensional parameter T for evaluation of ceramic materials was also proposed. Non-dimensional parameter T is consist of thermal load (Th) and Peclet number (Pe).
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Minet, C., N. Brunetie`re, and B. Tournerie. "Mixed Lubrication Modelling in Mechanical Face Seals." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71098.
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This paper presents a numerical model of mechanical seal operating in mixed lubrication. It is based on a deterministic approach using realistic roughness description. This model is able to simulate the transition from mixed to hydrodynamic lubrication regimes corresponding to a minimum of the friction coefficient. Moreover it is able to work with non Gaussian surfaces and oriented surfaces.
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Tartibi, M., and K. Komvopoulos. "Characterization of the Mechanical Behavior of Cell Components With an Atomic Force Microscope." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41230.
Повний текст джерелаАнотація:
The mechanical behavior of eukaryotic cell components is critical to cell mobility, division, signaling, and proliferation. Cell components are in such harmony with each other that often mechanical testing of individual components produces less meaningful results than testing performed within living cells. Moreover, cell components are constantly undergoing growth and remodeling, normally through polymerization and depolymerization. An appropriate experimental and modeling framework is therefore essential for cell mechanics. In this study, a special atomic force microscope (AFM) with controlled adhesion area of the cell to a substrate was used to probe the mechanical response of cells to an external force. This experimental set up enables direct control of the applied force and precise measurement of the cell penetration by the AFM tip. A modeling framework that combines the displacement field with the applied force/stress obtained with the AFM is developed to estimate the mechanical properties of each cell component. The tribological relevance of this research is the viscoelastic deformation of cell components under different contact loads.
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Gitis, Norm, Ilja Hermann, Suresh Kuiry, and Vishal Khosla. "Comprehensive Nano-Mechanical and Tribological Characterization of Hair." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44031.
Повний текст джерелаАнотація:
This paper presents test procedures and results of tribological and mechanical characterization of hair, treated with various shampoo and conditioners. They allow for a comprehensive functional comparison of hair care products.
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Kadiric, A., R. S. Sayles, and E. Ioannides. "Thermo-Mechanical Effects in Layered Rough Surface Contacts." In STLE/ASME 2006 International Joint Tribology Conference. ASME, 2006. http://dx.doi.org/10.1115/ijtc2006-12335.
Повний текст джерела
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Elhanafi, S., and K. Farhang. "Leakage Prediction in Mechanical Seals Under Hydrostatic Operating Condition." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44460.
Повний текст джерелаАнотація:
This paper considers leakage in mechanical seals under hydrostatic operating condition. A contact model based on the Greenwood and Williamson contact of rough surfaces is developed for treating problems involving mechanical seals in which both the micron scale roughness of the seal face and its macro scale profile are used to obtain either a closed-form equation or a nonlinear equation relating mean plane separation to the mass flow rate. The equations involve the micron scale geometry of the rough surfaces and physical parameter of the seal and carriage. Under hydrostatic condition, it is shown that there is an approximate closed-form solution in which mass flow rate in terms of the mean plane separation, or alternatively, the mean plane separation in terms of the leakage mass flow rate is found. Equations pertaining to leakage in nominally flat seal macro profile is considered and closed form equation relating to leakage flow rate to pressure difference is obtained that contain macro and micron geometries of the seal.