Dissertations / Theses on the topic 'Micro-models'
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Winkelmann, Christopher Todd. "Micro-imaging characterization of mouse models of metastasis." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5820.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "December 2005" Includes bibliographical references.
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Boehnke, Jasper. "Business models for Micro CHP in residential buildings." kostenfrei, 2007. http://www.unisg.ch/www/edis.nsf/wwwDisplayIdentifier/3375.
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Hejkal, Filip. "Micro-economic Models and their Validity - comparison of the models with the real situation." Master's thesis, Vysoká škola ekonomická v Praze, 2007. http://www.nusl.cz/ntk/nusl-10175.
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Mosler, Gioia. "Micro-environmental models of human exposure to air pollution." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25087.
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Particulate air pollution (PM) has been shown by many studies to cause adverse health effects. Traditionally PM exposure was estimated using ambient concentrations. Lately, studies have revealed that this approach poorly reflects differences between individual's exposures and as such results in exposure misclassification. This thesis aims to improve personal exposure predictions by building a model (MEPEX model), which takes into account the temporal and spatial variability of ambient PM, as well as visited microenvironments. For the composition of this model, existing approaches for model components were evaluated, compared and developed. A temporally adjusted land-use regression (LUR-adj) model for predictions of ambient PM2.5 and PM10 was built, validated, and compared to estimates from a dispersion model. Ratios were developed to adjust ambient concentrations for cycling and in-bus transport microenvironments. Additionally, modelling approaches for the home indoor microenvironment were compared, using monitoring data. A secondary aim was to evaluate the performance of different approaches for personal exposure assessment by comparing varying levels of model sophistication. Validation of the LUR-adj model showed good model fit (IA > 0.5) and low error (NMSE < 1) for short-term predictions of PM2.5 and PM10 at locations in London. In comparison to predictions of a dispersion model (ADMS-urban), LUR-adj estimates of PM10 produced better results for model performance parameters at the majority of 26 predicted locations. MEPEX model predictions of monitored daily personal exposure for an individual in London resulted in an R2 of 0.439 for PM2.5 and 0.403 for PM10. Predictions using modelled home outdoor concentrations in comparison were lower with R2 of 0.173 for PM2.5 and 0.086 for PM10. These results provide the first quantifiable evidence that personal exposure models of PM2.5 and PM10 can reduce exposure misclassification compared to estimates based only on ambient PM.
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DELFINO, EMANUELA. "Exploring micro-Electrocorticographic Signals: from Animal Models to Humans." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488155.
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Electrocorticography (ECoG) is a neural recording technique employed in both clinical and research fields characterized by a relatively high spatiotemporal resolution. ECoG has an extremely low susceptibility to noise and motion artefacts when compared to other techniques, e.g., Electroencephalography (EEG). Recently, the possibility of decoding speech from ECoG signals has been investigated with promising results, profoundly advancing the clinical viability of using speech-related Brain-Computer Interfaces to restore communication. Speech neuroprosthetic devices aim to improve the quality of life of people suffering from communication deficits because of locked-in syndrome (LIS) or other serious motor disabilities. In such patients, vocalization might not be possible due to severe paralysis, even though language areas are still intact. However, two technical aspects shall be improved before researchers could start clinical trials in patient populations. The first key improvement regards the tolerability of chronic ECoG implants. Standard ECoG grids cover different brain areas recruited in language processing, which is considered an advantage for speech decoding. However, their employment requires invasive procedures due to the large size of the grid, while its stiffness can lead to inflammatory response. One critical improvement could involve flexible high-density micro-grids directly placed over eloquent areas. The second key improvement of the current approaches goes beyond the technical implantation limits. To make use of the promising results obtained in speech decoding from neuronal signals for neuroprosthetic applications, more attention should be paid to the feasibility of their use in a natural setting, e.g. communication deficits. One critical issue in the development of assistive devices is the lack of detectable speech-related events to control the decoding. Detecting speech-related motor intentions would represent a fundamental step toward speech neuroprosthetics. In fact, this achievement could function as trigger to start the decoding whenever an explicit alignment is not possible (e.g. the case of covert speech). As the vocal cue is employed to start the most common virtual assistants (e.g. Google Assistant, Alexa, Siri), a neuronal cue to activate the speech decoder is fundamental in application for patients unable to speak. Firstly, a new generation of devices known as micro-ECoG (μECoG, electrode pitch below 1 mm) arrays was tested in rats to determine the best recording configuration in terms of reference and ground connections, Single-Ended Screw (without reference), Differential or Single-Ended Reference (with reference). Afterwards, two ultra-conformable polyimide-based μECoG arrays (afterwards referred to as MuSA and CaLEAF) were validated with the best recording configuration, in order to test whether all the electrodes could record the high-frequency components of the evoked responses independently from their geometry. Finally, two μECoG arrays were acutely implanted in a human patient undergoing awake neurosurgery for tumor resection (low-grade glioma), to investigate speech production processes in speech-related cortical regions. Neural signals recorded were characterised by different and well-defined time-frequency components, time-locked to speech production. The results of this work provide new insights into the understanding of the complex and still unclear neural processes behind speech production with a spatial resolution never reached before in cortical recordings. The μECoG data provide valuable information at a very high spatiotemporal resolution, which could have important implications for the design of speech Brain-Computer Interface.L’elettocorticografia (ECoG) è una tecnica di registrazione delle variazioni nell’attività nervosa utilizzata sia in clinica sia nell’ambito della ricerca scientifica, caratterizzata da un’alta risoluzione spazio-temporale. In studi recenti, sono state esplorate diverse strategie al fine di decodificare il linguaggio a partire da segnali elettrocorticografici, con risultati altamente promettenti. Tuttavia, molteplici aspetti della sintesi del linguaggio a partire dall’attività cerebrale devono essere migliorati prima di intraprendere la sfida dei trial clinici. Il primo aspetto che potrebbe essere migliorato riguarda la tollerabilità dell’impianto in cronico. L’utilizzo dell’ECoG standard costituisce un vantaggio nella decodifica del linguaggio, per la sua capacità di coprire diverse aree coinvolte nella produzione del linguaggio; tuttavia, questo aspetto è anche uno dei suoi più grandi svantaggi. Infatti, la procedura standard di impianto delle matrici ECoG richiede operazioni chirurgiche invasive, a causa della loro dimensione. Un nuovo approccio basato su matrici ad alta densità di micro-elettrodi posizionate direttamente sulla zona di interesse potrebbe massimizzare la specificità del segnale registrato. Inoltre, l’uso di materiali conformabili minimizzerebbe il rischio di danno alla corteccia e di morte neuronale per reazioni infiammatorie. Il secondo aspetto che potrebbe essere migliorato è dovuto alla necessità di progettare neuro-protesi per la codifica e la decodifica del linguaggio implicito a partire da segnali neurali. L’obiettivo di questi sistemi è di migliorare la qualità della vita di pazienti affetti da sindromi locked-in (LIS). In tali pazienti, la vocalizzazione è resa impossibile da gravi paralisi, nonostante la capacità di generare il linguaggio a livello corticale sia essere ancora intatta. Un miglioramento chiave nello sviluppo di neuroprotesi per il linguaggio consisterebbe nell’implementare un sistema di trigger per la decodifica del linguaggio, basato su segnali neurali registrati in aree coinvolte nella produzione. Una volta determinata la configurazione ottimale per la registrazione dei segnali in vivo su ratti Long Evans in termini di configurazioni elettriche di reference e ground, Single-Ended-Screw (senza reference), Differential o Single-Ended-Reference (con reference), è stato possibile traslare la conoscenza sull’uomo. La miglior configurazione validata in vivo è stata anche testata durante un esperimento condotto su un paziente sottoposto alla rimozione chirurgica di un glioma. Durante l’esperimento sono stati testati due dispositivi μECoG, appoggiati su un’area eloquente nota come speech arrest. Il soggetto durante l’esperimento ha eseguito un compito di denominazione di oggetti per un totale di trenta ripetizioni per dispositivo. Le features estratte dall’analisi tempo-frequenza in diverse bande sono state usate per addestrare un classificatore al riconoscimento della fase preparatoria del linguaggio. I segnali registrati mostrano pattern temporalmente specifici nelle diverse bande di frequenza di interesse (15-30 Hz, 30-60 Hz, 70-150 Hz). In particolare, l’attività anticipatoria nella banda del gamma alto ha permesso di predire con elevata accuratezza le fasi preparatorie del linguaggio. Tale scoperta potrebbe essere integrata in neuro-protesi per il linguaggio, come trigger per iniziare la decodifica quando non è possibile misurare un evento esplicito. I risultati di questa tesi forniscono nuove prospettive per la comprensione di processi complessi e ancora poco chiari come la produzione del linguaggio.
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Cribäck, Kevin. "Micro payments : Viable technical platforms and models for a bankto provide payments on micro amounts." Thesis, Uppsala universitet, Analys och sannolikhetsteori, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-354933.
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Ying, Guanwen. "Efficient Harmonic Simulations of Trabecular Bone Micro Finite Element Models." Thesis, Uppsala University, Department of Information Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-103037.
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The background problem is the disease of osteoporosis, which is caused by loss of bone mineral density and deterioration of bone micro-architecture. There are several problems of interest, related to the osteoporosis disease. One straightforward question to answer is whether a given bone tissue can withstood a particular load. Another question of big importance for a physician is what is the effect of a particular medical treatment, whether the medication has lead to increase of bone mass and where. Of no less importance is to study and compare the efficiency of various methods to improve the strength of the bone tissue with respect to load. According to recent research, there is evidence that applying a harmonic force with very small magnitude and proper frequency to human bone tissue can prevent or even reversethe disease. Thus, it is important to examine how bone responds to harmonic forces.
Practice has shown that in order to study a phenomenon such as the behaviour of human bone tissue under load, we have to use numerical simulations performed on a computer. Numerical simulations, in turn require:1. a good mathematical model to describe the underlying physical process,2. accurate numerical discretization techniques,3. efficient and reliable numerical solution methods to solve the algebraic systems of equations which arise after discretization,4. adequate program implementation to enable fast and scalable execution of the tasks, defined by the numerical solution.
This thesis includes a description of mathematical modeling and finite elementdiscretization. Suitable numerical algorithms to solve the arising linear systems are described and analysed, and numerical results for various benchmark problems are presented, compared and analysed.
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Calegari, Roberta <1982>. "Micro-intelligence for the IoT: logic-based models and technologies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8521/1/RC-thesis.pdf.
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Computing is moving towards pervasive, ubiquitous environments in which devices, software agents and services are all expected to seamlessly integrate and cooperate in support of human objectives.
An important next step for pervasive computing is the integration of intelligent agents that employ knowledge and reasoning to understand the local context and share this information in support of intelligent applications and interfaces. Such scenarios, characterised by "computation everywhere around us", require on the one hand software components with intelligent behaviour in terms of objectives and context, and on the other their integration so as to produce social intelligence.
Logic Programming (LP) has been recognised as a natural paradigm for addressing the needs of distributed intelligence. Yet, the development of novel architectures, in particular in the context Internet of Things (IoT), and the emergence of new domains and potential applications, are creating new research opportunities where LP could be exploited, when suitably coupled with agent technologies and methods so that it can fully develop its potential in the new context. In particular, the LP and its extensions can act as micro-intelligence sources for the IoT world, both at the individual and the social level, provided that they are reconsidered in a renewed architectural vision. Such micro-intelligence sources could deal with the local knowledge of the devices taking into account the domain specificity of each environment.
The goal of this thesis is to re-contextualise LP and its extensions in these new domains as a source of micro-intelligence for the IoT world, envisioning a large number of small computational units distributed and situated in the environment, thus promoting the local exploitation of symbolic languages with inference capabilities. The topic is explored in depth and the effectiveness of novel LP models and architectures -and of the corresponding technology- expressing the concept of micro-intelligence is tested.
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Mizzi, Simon. "Extended macroscopic models for rarefied gas dynamics in micro-sized domains." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501879.
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Medikonda, Sandeep. "Micro-Mechanical Models for Impact and Non-Local Averaging in Composites." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522419945945237.
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Dias, Fernandes Lucas. "From micro to macro : spatial models in molecular and evolutionary biology." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=229716.
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The characteristics of space and the movement of agents are intrinsic elements which are fundamental to any class of biological problems. From the diffusion properties of small and macromolecules in the cytoplasm, to the migration patterns of populations in a macroecological perspective, it is now clear that a full understanding of the different phenomena requires further insights not only on how the different elements interact, but on the different ways they are distributed in space, according to the proper spatial scales for each problem. This work analyzes three different classes of biological problems, focusing on the role played by space in understanding the phenomena from a theoretical perspective. First, we investigate the clustering of mechanosensitive channels on bacterial membranes and how their spatial distribution can lead to collective behaviour, significantly altering their functions. Second, we study protein production, trying to understand how particular properties on ribosomes' diffusion are linked with specific features of the translation process. Finally, on a very different scale, we explore spatial patterns' formation on a coevolutionary problem, where the interaction between two species is site-dependent. We approach these problems with different analytical and numerical techniques, revealing new biological aspects and providing novel views on current discussions in each field. We believe our results reinforce the importance of theoretical approaches to Biology and how space can significantly change many of these models.
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Tse, Shuetfung. "Models of micro positioning and methods for surface grinding process control /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MECH%202008%20TSE.
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Asproulis, N. "Hybrid molecular and continuum fluid dynamics models for micro and nanofluidic flows." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/6966.
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From molecules to living organisms and from atoms to planets a variety of physical phe-
nomena operate at different temporal and spatial scales. Understanding the nature of those
phenomena is crucial for advancing new technologies in many disciplines. In micro and
nanofluidics as the operational dimensions are downsized to smaller scales the surface-to-
volume ratio increases and the surface phenomena become dominant. Numerical modelling
is the key for obtaining a better insight into the processes involved. The Achilles heel of
fine grain microscopic numerical simulations is their computational cost. Simulating a
multiscale phenomenon with an accurate microscopic description is extremely demand-
ing computationally. On the contrary, simulations of multiscale phenomena based only on
macroscopic descriptions cannot fully capture the physics of the multiscale systems. In
order to confront this dilemma multiscale frameworks, called hybrid codes, have been de-
veloped to couple the microscopic and macroscopic description of a system and to facilitate
the exchange of information.
The aim of this research project is to establish and implement a robust hybrid molecular-
continuum method for micro- and nano-scale fluid flows. Towards that direction a hybrid
multiscale method named as Point Wise Coupling (PWC) has been developed. PWC aims
to circumvent the limitations of the existing hybrid continuum/atomistic approaches and
deliver a modular and applicable methodology. In the PWC, the whole domain is covered
with the macroscopic solver and the microscale model enters as a local refinement. Ad-
ditionally, numerical techniques based on neural networks are employed to minimise the
cost of the molecular solver and reduce the outcomes’ variability induced by the fluctuating
nature of the atomistic data.
Molecular studies have been performed (i) to obtain a better insight of the interfacial
phenomena in the solid/liquid interfaces, and (ii) to study the parametrisation of the molec-
ular models and mapping of atomistic information to hybrid frameworks. Specifically, the
impact of parameters, such as surface roughness and stiffness, to slip process is studied.
PWC framework has been employed to study a number of fundamental test cases in-
cluding Poiseuille flow of polymeric fluids, isothermal slip Couette flow and slip Couette
flow with heat transfer. Attention is drawn to the boundary condition transfer from the
continuum solver to the atomistic description. In the performed hybrid studies the effects
of the numerical optimisation techniques (linear interpolation, neural networks) to simu-
lations’ accuracy, stability and efficiency are studied. The outcomes of the simulations
suggest that the neural networks scheme enhance the simulation’s efficiency by minimising
the number of atomistic simulations and at the same time act as a smoothing operator for
reducing the oscillations’ strength of the atomistic outputs.
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O'Berry, Arthur Dylan. "Transportation engineering assimilated livability planning using micro-simulation models for Southeast Florida." Thesis, Florida Atlantic University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1602494.
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Transportation engineering has taken upon a new role; to empower the alternative modes of travel: walking, biking, and bus transit. In this new era, engineers are rethinking a network designed predominately for the automobile. The ultimate goal of this research is to create a process that can make a vehicle dominant corridor a desirable, livable thoroughfare by livability design and context sensitive performance measures. Balancing travel modes requires an account of vehicular traffic and the impact of reconfiguring existing conditions. The analysis herein is conducted by field data collection, transportation equations and microsimulation. Simulating traffic behavior will be the means to apply livable alternatives comparable to existing Southeast Florida conditions. The results herein have shown that micro-simulation can be utilized in transportation planning to reveal good livability alternatives.
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Stone, Devon. "An exploration of alternative features in micro-finance loan default prediction models." Master's thesis, Faculty of Science, 2020. http://hdl.handle.net/11427/32377.
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Despite recent developments financial inclusion remains a large issue for the World's unbanked population. Financial institutions - both larger corporations and micro-finance companies - have begun to provide solutions for financial inclusion. The solutions are delivered using a combination of machine learning and alternative data. This minor dissertation focuses on investigating whether alternative features generated from Short Messaging Service (SMS) data and Android application data contained on borrowers' devices can be used to improve the performance of loan default prediction models. The improvement gained by using alternative features is measured by comparing loan default prediction models trained using only traditional credit scoring data to models developed using a combination of traditional and alternative features. Furthermore, the paper investigates which of 4 machine learning techniques is best suited for loan default prediction. The 4 techniques investigated are logistic regression, random forests, extreme gradient boosting, and neural networks. Finally the paper identifies whether or not accurate loan default prediction models can be trained using only the alternative features developed throughout this minor dissertation. The results of the research show that alternative features improve the performance of loan default prediction across 5 performance indicators, namely overall prediction accuracy, repaid prediction accuracy, default prediction accuracy, F1 score, and AUC. Furthermore, extreme gradient boosting is identified as the most appropriate technique for loan default prediction. Finally, the research identifies that models trained using the alternative features developed throughout this project can accurately predict loan that have been repaid, the models do not accurately predict loans that have not been repaid.
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Carlsson, Henrik, and Tobias Thorsson. "Micro simulation models for traffic analyses and a comparison of different junction proposals." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97782.
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Hisingen, i de västra delarna av Göteborgsregionen, är ett tillväxtområde både för industri och för bostäder. Till följd av detta väntas en kraftig trafikökning under de kommande åren. Väg 155 är en viktig länk för arbetspendling till och från de stora arbetsplatser som finns i området. Redan i dag upplevs kapaciteten på vägen som otillräcklig då rusningstrafiken flyter trögt. FB Engineering AB har av Vägverket Region Väst fått i uppdrag att ta fram ombyggnadsförslag som har kapacitet att klara den framtida trafikbelastningen på vägen. I examensarbetet jämförs fyra av dessa förslag som infattar trafikplatserna Oljevägsmotet och Vädermotet samt sträckan mellan och i anslutning till dessa trafikplatser. Analysen har gjorts med hjälp av trafiksimuleringsprogrammet TSIS. Trafiksimuleringsprogram är verktyg som allt oftare används för att utreda konsekvenserna av olika förändringar i vägnätet. Detta medför både ekonomiska- och tidsmässiga vinster i och med att programmen kan utvärdera olika förslag innan slutgiltiga beslut fattas. Utvärderingen av ombyggnadsförslagen visar att skillnaderna mellan alternativen är relativt små och att alla bidrar med en klar förbättring jämfört med den nuvarande utformningen. Det förslag som gav bäst resultat med hänseende till framkomlighet innefattar en ny länk som sammanbinder Oljevägsmotet direkt med Hisingsleden samt låter väg 155 vara genomgående i Vädermotet. Examensarbetet innehåller även en litteraturstudie som beskriver de olika modeller som används i trafiksimuleringsprogrammen för att beskriva hur förarna beter sig i det simulerade nätverket. De modeller som har störst inverkan på förarbeteendet är modellerna för car-following och lane-changing. Dessa modeller beskriver hur förare i nätverket förhåller sig till varandra samt hur de agerar vid körfältsbyten. VISSIM och Paramics har liknande modeller där perceptuell psykologi används för att beskriva förarbeteendet. TSIS använder en car-followingmodell som bygger på att en förare alltid håller ett säkert avstånd till framförvarande fordon och en lane-changingmodell som bygger på att olika förare tar olika risker vid körfältsbyten. I examensarbetet har även en jämförelse gjorts mellan TSIS, VISSIM och Paramics. Jämförelsen inriktas på användarvänlighet och simuleringsresultat. Det program som har varit smidigast att arbeta med både när det gäller implementering och kalibrering har va rit VISSIM. Jämförelsen av simuleringsresultaten visar att VISSIM och Paramics resultatmässigt är likvärdiga medan TSIS skiljer sig något.
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Margraf, C. "On the use of micro models for claims reversing based on aggregate data." Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/17908/.
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In most developed economies, the insurance sector earns premiums that amount to around eight percent of their GNP. In order to protect both the financial market and the real economy, this results in strict regulations, such as the Solvency II Directive, which has monitored the EU insurance sector since early 2016. The largest item on general insurers’ balance sheets is often liabilities, which consist of future costs for reported claims that have not yet been settled, as well as incurred claims that have not yet been reported. The best estimate of these liabilities, the so-called reserve, is given attention to in Article 77 of the Solvency II Directive. However, the guidelines in this article are quite vague, so it is not surprising that modern statistics has not been used to a great extent in the reserving departments of insurance companies. This thesis aims to combine some theoretical results with the practical world of claims reserving. All results are motivated by the chain ladder method, and provide different reserving methods that will be introduced thoughout four separate papers. The first two papers show how claim estimates can be embedded into a full statistical reserving model based on the double chain ladder method. The new methods introduced incorporate available incurred data into the outstanding liability cash flow model. In the third paper a new Bornhuetter-Ferguson method is suggested, that enables the actuary to adjust the relative ultimates. Adjusted cash flow estimates are obtained as constrained maximum likelihood estimates. The last paper addresses how to consider reserving issues when there is excess-of loss reinsurance. It provides a practical example as well as an alternative approach using recent developments in stochastic claims reserving.
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Lind, Eric K. "Analysis of turbulence models in a cross flow pin fin micro-heat exchanger." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FLind.pdf.
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Zatti, Susi. "Micro-engineered skeletal and cardiac muscle for Duchenne muscular dystrophy in vitro models." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422953.
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Duchenne muscular dystrophy (DMD) is the most common and severe genetic neuromuscular disorder affecting both skeletal and cardiac muscle functionality. More than twenty years have passed since the identification of the dystrophin gene, which mutations cause the disease. Many progresses have been made in understanding the pathogenesis and different experimental strategies has been tested both in vitro, on bench-top cell cultures, and in vivo, on different animal models. So far, despite some promising outcomes coming from recent clinical trials, this has not resulted in an effective and definitive cure significantly altering the relentless progression of this disease, which has still a 100% mortality rate. In this context, the aim of this PhD thesis is the development of micro-engineered human skeletal and cardiac muscles representing in vitro models of DMD patient tissues useful for testing therapeutic approaches aimed at restoring a proper dystrophin expression. The strategy applied for the obtainment of such human in vitro models rely on the application of micro-scale technologies for reproducing in vitro the main physiological cues that guide differentiation and allow functionality of skeletal and cardiac muscles in vivo. In particular, the mechanical properties of the cell micro-environment and the topologic organization over the cell culture were optimized for both skeletal and cardiac muscle. Such micro-scale technologies were coupled with an appropriate human cell source. Human primary myoblasts from biopsies of DMD patient were used for skeletal muscle engineering, while DMD patient-specific cardiomyocytes were differentiated from human pluripotent stem (hiPS) cells for modeling the cardiac muscle. Both the obtained DMD in vitro models were validated for testing the ability of different therapeutic approaches in restoring dystrophin expression. In particular, three different myogenic cell types were tested on the engineered DMD skeletal muscle, while dystrophin expression restoration by a human artificial chromosome carrying the full-length genomic dystrophin sequence was tested on hiPS cells-derived cardiomyocytes. In these perspectives, the developed human in vitro models can represent a useful platform for performing preliminary or pre-clinical tests of different therapeutic strategy for DMD. In addition, they can be used as complementary tool in a clinical trial, for test different batches of cells before using them on patients.La distrofia muscolare di Duchenne è una delle più frequenti e severe patologie genetiche neuromuscolari che affliggono la funzionalità del muscolo scheletrico e cardiaco. Il gene codificante la distrofina, proteina la cui mutazione è alla base della patologia, è stato scoperto più di vent’anni fa. Da allora, notevoli progressi sono stati compiuti nella comprensione della patogenesi di questa malattia e diverse strategie sperimentali volte al suo trattamento sono state testate, sia in vitro su convenzionali colture cellulari che in vivo su diversi animali modello. Tuttavia, eccezione fatta per alcuni promettenti risultati recentemente ottenuti in trials clinici, ad oggi non vi è ancora una cura efficace e definitiva in grado di alterare o rallentare la progressione di questa patologia, il cui tasso di mortalità è pari al 100%. In tale contesto, lo scopo di questa tesi di dottorato è quello di sviluppare dei modelli in vitro micro-ingegnerizzati di muscolo scheletrico e cardiaco umano, che siano rappresentativi dei tessuti distrofici e dunque utili per testare approcci terapeutici volti al ripristino dell’espressione di distrofina. La strategia applicata per l’ottenimento di tali modelli si basa sull’applicazione di tecnologie su microscala per riprodurre in vitro i principali stimoli che guidano il differenziamento e consentono la funzionalità del muscolo scheletrico e cardiaco in vivo. In particolare, le proprietà meccaniche del micro-ambiente e l’organizzazione topologica della coltura cellulare sono stati ottimizzati sia per il muscolo scheletrico che cardiaco. Tali tecnologie su micro-scala sono state accoppiate con un’appropriata fonte cellulare umana. Per l’ingegnerizzazione del muscolo scheletrico sono stati utilizzati mioblasti umani primari derivanti da biopsie di pazienti DMD mentre, per la modellazione del muscolo cardiaco, cellule umane pluripotenti indotte (iPS) sono state differenziate in cardiomiociti paziente-specifici. Entrambi i modelli in vitro di muscolo distrofico ottenuti sono stati validati testando l’abilità di diversi approcci terapeutici nel ripristinarne l’espressione di distrofina. In particolare, tre diversi tipi cellulari miogenici sono stati testati nel muscolo scheletrico distrofico ingegnerizzato. Inoltre, nei cardiomiociti distrofici derivanti da cellule iPS è stato testato il ripristino dell’espressione di distrofina per mezzo di un cromosoma artificiale portante la sua completa sequenza genomica. Da tali risultati emerge come i modelli umani in vitro sviluppati in questo lavoro possano rappresentare un’utile piattaforma su cui effettuare test pre-clinici preliminari di diverse strategie terapeutiche. Inoltre, essi posso potenzialmente essere utilizzati come strumento complementare durante i trials clinici, per testare, ad esempio, diverse preparazioni di cellule destinate al paziente.
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Iori, Gianluca. "Micro-FEM models based on micro-CT reconstructions for the in vitro characterization of the elastic properties of trabecular bone tissue." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5422/.
Full textAbstract:
This master’s thesis describes the research done at the Medical Technology Laboratory (LTM) of the Rizzoli Orthopedic Institute (IOR, Bologna, Italy), which focused on the characterization of the elastic properties of the trabecular bone tissue, starting from october 2012 to present.
The approach uses computed microtomography to characterize the architecture of trabecular bone specimens. With the information obtained from the scanner, specimen-specific models of trabecular bone are generated for the solution
with the Finite Element Method (FEM). Along with the FEM modelling, mechanical tests are performed over the same reconstructed bone portions. From the linear-elastic stage of mechanical tests presented by experimental results, it
is possible to estimate the mechanical properties of the trabecular bone tissue.
After a brief introduction on the biomechanics of the trabecular bone (chapter 1) and on the characterization of the mechanics of its tissue using FEM models (chapter 2), the reliability analysis of an experimental procedure is explained (chapter 3), based on the high-scalable numerical solver ParFE. In chapter 4, the sensitivity analyses on two different parameters for micro-FEM model’s reconstruction are presented.
Once the reliability of the modeling strategy has been shown, a recent layout for experimental test, developed in LTM, is presented (chapter 5). Moreover, the results of the application of the new layout are discussed, with a stress on the difficulties connected to it and observed during the tests. Finally, a prototype experimental layout for the measure of deformations in trabecular bone specimens is presented (chapter 6). This procedure is based on the Digital Image Correlation method and is currently under development in LTM.
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Scott, Laurie Croslin Zeng Yong. "Bayesian inference via filtering of micro-movement multivariate stock price models with discrete noises." Diss., UMK access, 2006.
Find full textAbstract:
Thesis (Ph. D.)--Dept. of Mathematics and Statistics and Dept. of Economics. University of Missouri--Kansas City, 2006."A dissertation in mathematics and economics." Advisor: Yong Zeng. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 29, 2007. Includes bibliographical references (leaves 121-124). Online version of the print edition.
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Göktepe, Serdar. "Micro-macro approaches to rubbery and glassy polymers : predictive micromechanically-based models and simulations." Stuttgart Institut für Mechanik (Bauwesen) der Universität Stuttgart, 2007. http://elib.uni-stuttgart.de/opus/volltexte/2007/3342/.
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Napolitano, Anthony P. "Directing cellular self-assembly for micro-scale tissue engineering and in vitro tissue models." View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319111.
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Poidomani, Viola. "Micro-simulation models at neighbourhood scale: the interplay of agents, buildings, activities and transport." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5725/.
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Urban systems consist of several interlinked sub-systems - social, economic, institutional and
environmental – each representing a complex system of its own and affecting all the others at
various structural and functional levels.
An urban system is represented by a number of “human” agents, such as individuals and
households, and “non-human” agents, such as buildings, establishments, transports, vehicles
and infrastructures. These two categories of agents interact among them and simultaneously
produce impact on the system they interact with.
Try to understand the type of interactions, their spatial and temporal localisation to allow a
very detailed simulation trough models, turn out to be a great effort and is the topic this
research deals with.
An analysis of urban system complexity is here presented and a state of the art review about
the field of urban models is provided.
Finally, six international models - MATSim, MobiSim, ANTONIN, TRANSIMS, UrbanSim,
ILUTE - are illustrated and then compared.
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Carpanini, Sarah Marie. "Characterisation of a novel Rab18 mouse model for Warburg Micro syndrome." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9611.
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Warburg Micro syndrome is a severe autosomal recessive condition characterised by abnormalities affecting the ocular, neurological and endocrine systems. Previous studies have identified causative loss-of-function mutations in four members of the RAB protein network; RAB3GAP1, RAB3GAP2, RAB18 and TBC1D20, causing clinically indistinguishable phenotypes. RAB3GAP1 and RAB3GAP2 form a heterodimeric complex specifically regulating the RAB3 family of proteins in calcium mediated exocytosis of hormones and neurotransmitters. Rab3gap1 deficient mice have previously been generated and showed altered short term plasticity in the hippocampus and inhibition of Ca2+ mediated exocytosis of glutamate from cortical synaptosomes, but failed to recapitulate the characteristic ocular or neurological features of Warburg Micro syndrome. Mutations in TBC1D20, a GTPase activating protein (GAP) for the RAB1 family, have recently been identified in Warburg Micro syndrome patients and the bs (blind sterile) mouse model; although this model recapitulated many ocular and endocrine abnormalities of the disease any neurological abnormalities have yet to be reported. The function and localisation of RAB18 remains to be fully elucidated and its role in disease pathogenesis is still unclear. Initially, I have confirmed previous reports co-localising RAB18 with the cis-Golgi, ER and lipid droplets in mouse embryonic fibroblasts and identified a novel localisation in neuronal processes of primary hippocampal neurons. To examine the role of RAB18 in vivo a novel Rab18 genetrap mouse was generated by MRC Harwell as part of the EUMODIC screen. In this study I describe detailed histopathological and neurological characterisation of the Rab18-/- mouse model. Rab18-/- mice were viable and fertile. At eye opening they presented with dense nuclear congenital cataracts and atonic pupils recapitulating major ocular features of Warburg Micro syndrome. Analysis of embryonic eye development revealed a delay in lens development in Rab18-/- mice as early as embryonic day 12.5. From three weeks of age Rab18-/- mice developed progressive hind limb weakness indicative of neurological dysfunction. I have undertaken detailed neuropathological analysis of the observed hind limb weakness and identified no abnormalities in synaptic vesicle recycling and no atrophy of peripheral muscles or aberrant development or stability of neuromuscular connectivity. However, loss of RAB18 resulted in gross accumulations of neurofilament and microtubule proteins at the neuromuscular junction and disorganisation of the cytoskeleton in peripheral nerves. Investigation of global proteomic profiling in peripheral nerve of Rab18-/- mice identified alterations in core pathways regulating the axonal cytoskeleton in neurons. In summary this thesis describes a novel Rab18-/- mouse model recapitulating the characteristic ocular and neurological features of Warburg Micro syndrome. I highlight a novel mechanistic insight into Warburg Micro syndrome disease pathogenesis and a role for RAB18 in regulating cytoskeletal dynamics in neurons.
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Gauntt, Stephen Byron. "Micro-chamber filling experiments for validation of macro models with applications in capillary driven microfluidics." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2538.
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VARGAS, KELLY MARGARITA COLMENARES. "OIL DISPLACEMENT IN MICRO MODELS OF POROUS MEDIA BY INJECTION OF OIL IN WATER EMULSION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35523@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
O processo de recuperação de óleo pelo deslocamento com água é o método mais utilizado na indústria de petróleo. No entanto, as altas razões de mobilidade e baixas eficiências de varrido tornam o processo menos eficiente. Uma alternativa usada para minimizar este efeito é a aplicação de tecnologias que atuam como agentes de controle de mobilidade. Dentre eles, e em particular a injeção de emulsões de óleo em água tem sido estudada com relativo sucesso como um método de recuperação avançada de óleo. Alguns estudos indicam melhor varredura do reservatório devido a uma redução da mobilidade da água em regiões do reservatório já varridas por água, mediante a aglomeração e bloqueio parcial dos poros mais permeáveis com gotas da fase dispersa da emulsão. Contudo, ainda não há compreensão plena dos mecanismos associados ao escoamento de emulsões em meios porosos, assim, uma análise e visualização na escala microscópica dos fenômenos envolvidos se faz essencial para a melhora do entendimento do escoamento de emulsões em um reservatório. Neste trabalho, experimentos de escoamento de emulsões foram conduzidos em um micromodelo de vidro, estrutura artificial que busca representar alguns aspectos principais de um meio poroso e proporciona uma adequada visualização do comportamento das faces ao longo do escoamento. Nos experimentos foram realizadas alterações na molhabilidade e variou-se a vazão volumétrica a fim de avaliar diferentes números de capilaridade no meio poroso. Dentro dos resultados mais significativos, foi evidenciado como a fase dispersa da emulsão é capaz de bloquear os poros e gargantas de poro alterando a distribuição dos fluidos no meio poroso, melhorando a eficiência de deslocamento na escala de poro e com isso o fator de recuperação final. Os resultados mostram que, a altos números de capilaridade as forças interfaciais são menos importantes ao reduzir o efeito de bloqueio pelas gotas da fase dispersa nos poros do micromodelo. Estes resultados fornecem um grande aprendizado ao permitir conhecer características do escoamento de emulsões no meio poroso para uma futura aplicação no campo.
The oil recovery process by water-flooding is the most used method in the oil industry. However, the high mobility ratios and low sweep efficiencies make the process less effective. A common alternative to minimize this effect is the application of technologies that act as mobility control agents. Among them and in particular the injection of oil in water emulsions has been studied with relative success as an Enhanced Oil Recovery (EOR) method. Several studies indicate a better reservoir sweep due to the water mobility reduction in regions already swept by water. This reduction can be associated with partial blockage of porous media throats by droplets of emulsion dispersed phase. Nevertheless, there is still no full understanding of the mechanisms associated to the flow of emulsions in porous media, thus, an analysis and visualization at the microscopic scale of the involved phenomena is essential for the improvement of the comprehension of the flow of emulsions in a reservoir. In this work, experimental tests related to the flow of emulsions in a glass micro-model were performed, artificial device that represents some principal features of a porous medium and provides a proper visualization of the phase behavior. In the experiments, the effect of the capillary number on the oil recovery factor and the relative influence of the wettability of the porous medium on the oil displacement process were studied. The results evidence how the oil droplets in the emulsion are capable of block the pores and the pore throats modifying the fluids distribution in the porous medium, improving the displacement efficiency at pore scale and consequently the final oil recovery factor. It was also observed that at high capillary numbers, the blocking caused by the capillary pressure needed to deform the droplet becomes less intense. These results provide a great learning by allowing to know the characteristics of the flow of emulsions in porous media for a future field application.
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Sissons, Matthew. "Micro-wind power in the UK : experimental datasets and theoretical models for site-specific yield analysis." Thesis, University of Southampton, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543418.
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Tian, Kun. "Essays on price rigidity in the UK : evidence from micro data and implications for macro models." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/49986/.
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This study consists of three individual essays which all shed light on assessing the price rigidity by using price micro data in the UK. The relevant implications for macro models are also discussed in each essay respectively. The first essay gives a unified framework a la Dixon (2012) to gauge the price rigidity from three perspectives: frequency, hazard function and distribution across firms. On average, the monthly frequency of consumer price change is 19% between 1996 and 2007. Sales and substitutions will significantly affect the frequency of consumer price change. The frequency of consumer price change varies considerable across sectors. The fraction of price changes which are decreasing is about 40%. The hazard function is downward sloping with 12-month spike. The censoring and sampling issues in the estimation of hazard function are discussed thoroughly. The distribution across firms is derived from estimated hazard function, which is consistent with the frequency of price changes. Two benchmark sticky price models are calibrated and simulated. Furthermore, a multiple Calvo and multiple menu costs model are also simulated, based on the empirical finding in micro data. The simulation results suggest that introducing heterogeneity into sticky price models can improve models' fitness in respect to matching micro evidence. The second essay mainly focus on "the monthly frequency of price changes", which is a prominent feature of many studies of the CPI micro-data. In this essay, we see how much the frequency ties down the behavior of price-setters ("firms") in steady-state in terms of the average length of price-spells across firms. We are able to divide an upper and lower bound for the mean duration of price-spells averaged across firms. We use the UK CPI data at the aggregate and sectoral level and find that the actual mean is about twice the theoretical minimum consistent with the observed frequency. We estimate the distribution using the hazard function and find that although the estimated hazard differs significantly from the Calvo distribution, the means and medians are similar. However, despite the micro differences, we find that the artificial Calvo distributions generated using the sectoral frequencies result in very similar impulse responses to the estimated hazards when used in the Smets-Wouters (2003) model. The third essay examines the behavior of individual producer prices in the UK. A number of stylized facts about price setting behavior are uncovered. A time-varying Ss model is set up in a way that is consistent with the stylized facts obtained from the UK PPI data. A duration model (semiparametric survival analysis model) is built in line with the time-varying Ss model. This duration model is estimated by controlling for observed and unobserved heterogeneity across firms. The estimation results suggest that the increase in the inflation rate will significantly increase the hazard rate of price change. The other factors considered in the model will also affect the hazard rate of price change, while in different magnitude.
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Miller, Kyle M. "Mechanical Characterization of Lithium-Ion Battery Micro Components for Development of Homogenized and Multilayer Material Models." Thesis, Monterey, California. Naval Postgraduate School, 2014. http://hdl.handle.net/10945/43074.
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CIVINSThe overall battery research of the Impact and Crashworthiness Laboratory (ICL) at MIT has been focused on understanding the battery’s mechanical properties so that individual battery cells and battery packs can be characterized during crash events. The objective of this research is to better understand the battery component (electrode and separator) properties under different loading conditions. In this work, over 200 tests were conducted on battery components. These tests include uniaxial stress, biaxial punch, multilayer, single layer, short-circuit testing, wet vs dry specimen testing, strain rate testing, and more. Additionally, a scanning electron microscope was used to view the battery components at a micro level for the purpose of better understanding the aforementioned test results. During these tests, it was observed that many of the electrodes in the Li-ion batteries are damaged during the battery manufacturing process. Also, the two methods of manufacturing battery separator were analyzed and their resulting mechanical properties were characterized. These results will be used to further refine and validate a high-level, robust, and accurate computational tool to predict strength, energy absorption, and the onset of electric short circuit of batteries under real-world crash loading situations. The cell deformation models will then be applied to the battery stack and beyond, thereby enabling rationalization of greater optimization of the battery pack/vehicle combination with respect to tolerance of battery crush intrusion behavior. Besides improving crash performance, the finite element models contribute substantially to the reduction of the cost of prototyping and shorten the development cycle of new electric vehicles.
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Miller, Kyle M. (Kyle Mark). "Mechanical characterization of lithium-ion battery micro components for development of homogenized and multilayer material models." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92133.
Full textAbstract:
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 60).
The overall battery research of the Impact and Crashworthiness Laboratory (ICL) at MIT has been focused on understanding the battery's mechanical properties so that individual battery cells and battery packs can be characterized during crash events. The objective of this research is to better understand the battery component (electrode and separator) properties under different loading conditions. In this work, over 200 tests were conducted on battery components. These tests include uniaxial stress, biaxial punch, multilayer, single layer, short-circuit testing, wet vs dry specimen testing, strain rate testing, and more. Additionally, a scanning electron microscope was used to view the battery components at a micro level for the purpose of better understanding the aforementioned test results. During these tests, it was observed that many of the electrodes in the Li-ion batteries are damaged during the battery manufacturing process. Also, the two methods of manufacturing battery separator were analyzed and their resulting mechanical properties were characterized. These results will be used to further refine and validate a high-level, robust, and accurate computational tool to predict strength, energy absorption, and the onset of electric short circuit of batteries under real-world crash loading situations. The cell deformation models will then be applied to the battery stack and beyond, thereby enabling rationalization of greater optimization of the battery pack/vehicle combination with respect to tolerance of battery crush intrusion behavior. Besides improving crash performance, the finite element models contribute substantially to the reduction of the cost of prototyping and shorten the development cycle of new electric vehicles.
by Kyle M. Miller.
Nav. E.
S.M.
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Moscovic, Sandra A. "Development of time and workload methodologies for Micro Saint models of visual display and control systems." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/40443.
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Dowds, Eleanor Jane, and Fatme El-Saghir. "Utilising waste heat from Edge-computing Micro Data Centres : Financial and Environmental synergies, Opportunities, and Business Models." Thesis, KTH, Industriell ekonomi och organisation (Inst.), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298245.
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In recent times, there has been an explosion in the need for high-density computing and data processing. As a result the Internet and Communication Technology (ICT) demand on global energy resources has tripled in the last five years. Edge computing - bringing computing power close to the user, is set to be the cornerstone of future communication and information transport, satisfying the demand for instant response times and zero latency needed for applications such as 5G, self-driving vehicles, face recognition, and much more. The Micro Data Centre (micro DC) is key hardware in the shift to edge computing. Being self-contained, with in-rack liquid cooling systems, these micro data centres can be placed anywhere they are needed the most - often in areas not thought of as locations for datacentres, such as offices and housing blocks. This presents an opportunity to make the ICT industry greener and contribute to lowering total global energy demand, while fulfilling both the need for data processing and heating requirements. If a solution can be found to capture and utilise waste heat from the growing number of micro data centres, it would have a massive impact on overall energy consumption. This project will explore this potential synergy through investigating two different ways of utilising waste heat. The first being supplying waste heat to the District Heating network (Case 1), and the second using the micro DC as a ’data furnace’ supplying heat to the near vicinity (Case 2 and 3). Two scenarios of differing costs and incomes will be exploredin each case, and a sensitivity analysis will be performed to determine how sensitive each scenario is to changing internal and external factors. Results achieved were extremely promising. Capturing waste heat from micro data centres, and both supplying the local district heating network as well as providing the central heating of the near vicinity, is proving to be both economically and physically viable. The three different business models (’Cases’) created not only show good financial promise, but they demonstrate a way of creating value in a greener way of computing and heat supply. The amount of waste heat able to be captured is sufficient to heat many apartments in residential blocks and office buildings, and the temperatures achieved have proven to be sufficient to meet the heating requirements of these facilities, meaning no extra energy is required for the priming of waste heat. It is the hope that the investigations and analyses performed in this thesis will further the discussion around the utilisation of waste heat from lower energy sources, such as micro DCs, so that one day, potential can become reality.På senare har tid har det skett en explosion i behovet av databehandling och databehandling med hög densitet. Som ett resultat har Internet- och kommunikationstekniksektorns (ICT) efterfråga på globala energiresurser tredubblats under de senaste fem åren. Edgecomputing för datorkraften närmre användaren och är hörnstenen i framtida kommunikation och informationsflöde. Omedelbar svarstid och noll latens som behövs för applikationersom 5G, självkörande fordon, ansiktsigenkänning och mycket mer tillfredställs av att datorkraften förs närme användaren. Micro Data Center är nycklen i övergången till edge computing. Eftersom att MicroData Center är fristående med inbyggda kylsystem kan de placeras där de behövs mest -ofta i områden som inte betraktas som platser för datacenter som exemeplvis kontor och bostadshus. Detta möjliggör för ICT-branschen att bli grönare och bidra till att sänka det totala globala energibehovet, samtidigt som behovet av databehandling kan tillgodoses. Om enlösning kan hittas för att fånga upp och använda spillvärme som genereras från växande antalet Micro Data Center, skulle det ha en enorm inverkan på den totala energiförbrukningen. Detta projekt kommer att undersöka potentiella synergier genom att undersöka två olikasätt att utnyttja spillvärme. Den första är att leverera spillvärme till fjärrvärmenätet (Case 1), och det andra att använda Micro Data Center som en "Data Furnace" som levererar värme till närområdet (Case 2 och 3). Två scenarier med olika kostnader och intäkter kommer att undersökas i varje Case och en känslighetsanalys kommer att utföras för att avgöra hur känsligt varje scenario är för ändrade interna och externa faktorer. Resultaten som uppnåtts är extremt lovande. Att fånga upp spillvärme från Micro Data Center och leverera till antingen det lokala fjärrvärmenätet eller nyttja spillvärmen lokalt har visat sig vara både ekonomiskt och fysiskt genomförbart. De tre olika affärsmodellerna (’Cases’) som skapats visar inte bara positivt ekonomiskt utfall, utan också ett sätt att skapa värde genom att på ett grönare sätt processa och lagra data och samtidigt värma städer. Mängden spillvärme som kan fångas upp är tillräcklig för att värma upp många lägenheter i bostadshus och kontorsbyggnader. Temperaturen på spillvärmen har visat sig vara tillräcklig för att uppfylla uppvärmningskraven i dessa anläggningar, vilket innebär att ingen extra energi krävs för att höja temperturen av spillvärme. Förhoppningen är att de undersökningar och analyser som utförs i denna rapport kommer att främja diskussionen kring utnyttjande av spillvärme från lägre energikällor, såsom Micro Data Center.
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Göktepe, Serdar [Verfasser]. "Micro-macro approaches to rubbery and glassy polymers : predictive micromechanically-based models and simulations / vorgelegt von Serdar Göktepe." Stuttgart : Inst. für Mechanik (Bauwesen), 2007. http://d-nb.info/99705350X/34.
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Schuster, Simon [Verfasser], and Stefan [Akademischer Betreuer] Zahler. "Models for angiogenesis on micro-structured surfaces : a novel view on endothelial cell biology / Simon Schuster. Betreuer: Stefan Zahler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/109312492X/34.
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Jonsson, Gabriel, Louise Fredriksson, and Miljevic Rebecca Lööv. "Exploring how Barriers to Circular Business Models can be Overcome on a Macro and Micro Level : -a Swedish Textile Industry Perspective." Thesis, Internationella Handelshögskolan, Jönköping University, IHH, Företagsekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-49143.
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Background: The resource demanding textile industry has long been linked to the linear economy, an economy contributing to negative effects on the environment. However, there is an alternative to the linear economy, namely the circular economy. In a circular economy, a closed-loop design is promoted in order to eliminate the negative effects of the linear economy. However, in the context of the Swedish textile industry, there is a lack of case studies on the topic and especially regarding experienced barriers to a circular business model as well as drivers and enablers needed to overcome these barriers. Purpose: The purpose of this research is to support the development of the Sustainable Development Goal 12: sustainable production and consumption. This is done through exploring the experienced barriers to circular business models among companies in the Swedish textile industry at a macro and micro level, but also drivers and enablers in order to overcome these barriers. Method: This research follows an interpretivist view and an inductive approach based on a cross-case analysis of five companies. The research is qualitative and semi-structured interviews were conducted with open questions. The identified themes were analysed and interpreted with a careful awareness of the trustworthiness and ethical considerations. Conclusion: The result showed five barriers which appeared to be the most common across the companies. Namely, technological un-readiness, circularity costs, market unacceptance, financial shortage and knowledge gap. For these barriers, possible solutions in the form of drivers and enablers were identified. According to the findings, the identified drivers and enablers which have the greatest potential of positive impact on the barriers were as follows: knowledge sharing, collaboration, regulatory changes, more research and refocus of efforts
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Onifade, Ibrahim. "Development of Energy-based Damage and Plasticity Models for Asphalt Concrete Mixtures." Doctoral thesis, KTH, Byggnadsmaterial, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198663.
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Characterizing the full range of damage and plastic behaviour of asphalt mixtures under varying strain-rates and stress states is a complex and challenging task. One reason for this is partly due to the strain rate and temperature dependent nature of the material as well as the variation in the properties of the constituent materials that make up the composite asphalt mixture. Existing stress-based models for asphalt concrete materials are developed based on mechanics principles, but these models are, however, limited in their application for actual pavement analysis and design since rate dependency parameters are needed in the constitutive model to account for the influence of the strain rate on the stress-based yield and evolution criteria. Till date, we are yet to arrive at simple and comprehensive constitutive models that can be used to model the behaviour of asphalt mixture over a wide range of strain-rate which is experienced in the actual pavement sections. The aim of this thesis is to develop an increased understanding of the strength and deformation mechanism of asphalt mixtures through multi-scale modeling and to develop simple and comprehensive continuum models to characterize the non-linear behaviour of the material under varying stress-states and conditions. An analysis framework is developed for the evaluation of the influence of asphalt mixture morphology on its mechanical properties and response using X-Ray CT and digital image processing techniques. The procedure developed in the analysis framework is then used to investigate the existence of an invariant critical energy threshold for meso-crack initiation which serves as the basis for the development of a theory for the development of energy-based damage and plastic deformation models for asphalt mixtures. A new energy-based viscoelastic damage model is developed and proposed based on continuum damage mechanics (CDM) and the thermodynamics of irreversible processes. A second order damage variable tensor is introduced to account for the distributed damage in the material in the different principal damage directions. In this way, the material response in tension and compression can be decoupled and the effects of both tension- and compression stress states on the material behaviour can be accounted for adequately. Based on the finding from the energy-based damage model, an equivalent micro-crack stress approach is developed and proposed for the damage and fracture characterization of asphalt mixtures. The effective micro-crack stress approach takes account of the material stiffness and a critical energy threshold for micro-crack initiation in the characterization of damage and fracture properties of the mixture. The effective micro-crack stress approach is developed based on fundamental mechanics principles and it reduces to the Griffith's energy balance criterion when purely elastic materials are considered without the need for the consideration of the surface energy and a crack size in the determination of the fracture stress. A new Continuum Plasticity Mechanics (CPM) model is developed within the framework of thermodynamics to describe the plastic behaviour of asphalt concrete material with energy-based criteria derived for the initiation and evolution of plastic deformation. An internal state variable termed the "plasticity variable" is introduced to described the distributed dislocation movement in the microstructure. The CPM model unifies aspects of existing elasto-plastic and visco-plastic theories in one theory and shows particular strength in the modeling of rate-dependent plastic behaviour of materials without the need for the consideration of rate dependency parameters in the constitutive relationships. The CPM model is further extended to consider the reduction in the stiffness properties with incremental loading and to develop a unified energy-based damage and plasticity model. The models are implemented in a Finite Element (FE) analysis program for the validation of the models. The result shows that the energy-based damage and plastic deformation models are capable of predicting the behaviour of asphalt concrete mixtures under varying stress-states and strain-rate conditions. The work in this thesis provides the basis for the development of more fundamental understanding of the asphalt concrete material response and the application of sound and solid mechanics principles in the analysis and design of pavement structures.En heltäckande karakterisering av skador och plastiska beteende hos asfaltblandningar under varierande belastningshastighet och spänningstillstånd är en komplex och svår uppgift. En orsak till detta är relaterat till materialets belastningshastighet- och temperaturberoende, såväl som variationen i materialegenskaperna hos de ingående komponenterna i den sammansatta asfaltblandningen. Befintliga spänningsbaserade modeller för asfaltbetongmaterial är utvecklade baserade på mekanikprinciper, men dessa modeller är begränsade när det gäller analys och design av verkliga asfaltsbeläggningar eftersom hastighetsberoende parametrar behövs i den konstitutiva modellen även med hänsyn till töjningshastighetens inverkan på kriterier för gränser och utveckling av spänningstillstånd. Det finns därför behov av att utveckla enkla men ändå heltäckande konstitutiva modeller som kan användas för att modellera beteendet hos asfaltmassan över ett brett spektrum av belastningshastigheter för olika av sektioner asfaltsbeläggningar. Syftet med denna avhandling är att öka förståelsen av hållfasthets- och deformationsmekanismer för asfaltblandningar genom multi-modellering. Målet är att utveckla enkla och heltäckande kontinuummodeller som karakteriserar materialets olinjära beteende under varierande spänningstillstånd och betingelser. Ett analysramverk har utvecklats för utvärdering av påverkan av asfaltmassans morfologi på dess mekaniska egenskaper och beteende med hjälp av röntgendatortomografi och digital bildbehandlingsteknik. Detta förfarande har sedan använts för att undersöka förekomsten av inneboende kritiska tröskelvärden för brottenergin för mesosprickinitiering vilket i sin tur ligger till grund för utvecklingen av en teori för modellering av energibaserade skador och plastisk deformation hos asfaltblandningar. En ny energidensitet baserad viskoelastisk skademodell utvecklas och föreslås utgå från kontinuum-skade-mekanik (CDM) och termodynamik för irreversibla processer. En andra ordningens skadevariabeltensor införs för att ta hänsyn till skadedistributionen i materialen i de olika principiella skaderiktningarna. På detta sätt kan materialets respons i drag- och tryckbelastning separeras och effekterna av spänningstillstånd i både drag och tryck kan beaktas på ett adekvat sätt. Baserat på resultaten från den energibaserade skademodellen utvecklas och föreslås en motsvarande metod för mikrosprickspänning gällande skade- och brottkarakteriseringen av asfaltblandningar. Metoden för den effektiva mikrosprickspänningen tar hänsyn till materialets styvhet och en kritisk tröskelenergi för mikrosprickinitiering för karakteriseringen av skador och brottegenskaper hos blandningen. Denna metod är utvecklad baserat på grundläggande mekanikprinciper och kan för rent elastiska material reduceras till Griffiths energibalanskriterium utan hänsyn till ytenergi och sprickstorlek vid bestämningen av brottspänningen. En ny termodynamikbaserad modell för kontinuumplasticitetsmekanik (CPM) utvecklas för att beskriva det plastiska beteendet hos asfaltbetongmaterial med energibaserade kriterier härledda för initiering och progression av plastisk deformation. En intern tillståndsvariabel kallad "plasticitetvariabeln" införs för att beskriva den fördelade dislokationsrörelsen i mikrostrukturen. CPM-modellen förenar befintliga elasto-plastiska och visko-plastiska teorier i en teori och visar sig vara särskilt effektiv i modelleringen av hastighetsberoende plastiskt beteende hos material utan att behöva beakta hastighetsberoende parametrar i de konstitutiva sambanden. CPM-modellen utvidgas ytterligare för att kunna beakta reduktionen av styvheten med stegvis ökad belastning och för att utveckla en enhetlig energibaserad skade- och plasticitetmodell. Modellerna är implementerade i ett finit element (FE)-analysprogram för validering av modellerna. Resultatet visar att de energibaserade modellerna för skador och plastisk deformation kan förutsäga beteendet hos asfaltbetongblandningar under varierande spänningstillstånd och töjningshastighetsförhållanden. Arbetet i denna avhandling utgör grunden för utvecklingen av mer grundläggande förståelse av asfaltbetongmaterialets respons och tillämpningen av sunda och robusta mekanikprinciper i analys och design av asfaltstrukturer.
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Ouiakoub, Mohamed. "Contribution à la connaissance de l’évolution des business models des entreprises familiales marocaines : une approche par les micro-fondations des capacités dynamiques." Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROD003.
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L'environnement dynamique actuel contraint les entreprises à adapter leur business model (BM) en tant que nouvelle source d'avantage concurrentiel. Cela impose des enjeux significatifs aux entreprises dont les structures sont établies de longue date, telles que les entreprises familiales. Celles-ci sont souvent confrontées, durant leur cycle de vie, à des évolutions de leur BM pour faire face aux contraintes organisationnelles mais également aux menaces et aux opportunités de leur environnement. L’objectif de cette recherche est d’explorer, au travers d’une étude qualitative de cas multiples, le processus d’évolution du BM de l’entreprise familiale et les capacités dynamiques qui permettent de faire évoluer sa configuration au fil du temps afin de créer et accroître la valeur. Pour ce faire, les capacités dynamiques sont essentielles pour que les entreprises puissent exploiter les opportunités et répondre aux changements de l’environnement. Ces capacités sont particulièrement importantes pour les entreprises familiales en raison de leur volonté de réussir pour les générations futures. En outre, l'implication de la famille dans l'entreprise est créatrice des motivations idiosyncratiques et des caractéristiques à long terme qui affectent considérablement le comportement organisationnel de l'entreprise. Cette recherche montre que les entreprises familiales réduisent la dépendance et l'incertitude de l'environnement en développant leur BM et en changeant leur logique de création et de capture valeur à travers leurs activités. Les caractéristiques de ces entreprises leur permettent de promouvoir simultanément des processus d’exploration et d’exploitation conduisant à une ambidextrie organisationnelle. Les résultats de cette recherche révèlent également que les capacités fortes de détection, de saisie et de transformation des opportunités sont des antécédents pertinents de l’évolution du BM. Cette recherche a, par ailleurs, démontré le rôle important de la famille dans le contrebalancement des influences internes et externes, la formation de la portée et la complexité du BM et la création des dépendances de sentiers spécifiquesToday’s dynamic environment requires firms to adapt their business models as a new source of competitive advantage. This poses significant challenges to firms that are locked in their long-established structures, like family firms. These firms are often confronted, during their life cycle, to evolutions in their business models due to organizational constraints, but also threats and opportunities of their environment. The objective of this research is to explore, by qualitative multiple case study, the BM evolution process and dynamic capabilities that allow the configuration of family business models to evolve over time in order to create and increase value. For this purpose, dynamic capabilities are essential for firms to exploit opportunities and respond to environment changes in general. They are particular important for family firms due to the desire to succeed for future generations. Given that family involvement in business creates idiosyncratic motivations and long-term characteristics that considerably affect the firm’s behavior, this research shows that family businesses reduce environmental uncertainty and dependence by developing their business model, changing the logic of creating and capturing value through their activities. The characteristics of these firms allow them to promote simultaneously exploration and exploitation processes leading to an organizational ambidexterity. Furthermore, our findings reveal strong sensing and seizing as well as transforming capabilities as relevant antecedents of business model evolution and stress upon the important role played by family in balancing internal and external influences, shaping the scope and complexity of business model evolution, and creating specific path dependencies
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Berdica, Katja. "TraVIS for Roads - Examples of Road Transport Vulnerability Impact Studies." Doctoral thesis, KTH, Infrastructure, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3438.
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Akililu, Meaza Negash. "Verification of Rural Traffic Simulator, RuTSim 2." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-84453.
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Traffic models based on micro-simulation are becoming increasingly important as traffic analysistools. Due to the detailed traffic description, different micro-simulation models are needed tosimulate different traffic environments. The Rural Traffic Simulator, RuTSim, is a unique microtrafficsimulation model for traffic on rural roads. RuTSim is developed at VTI with support fromthe Swedish Transport Administration. Currently, a new version of the RuTSim model has beenimplemented based on the earlier one but with some enhancements. Due to these enhancements,the new implementation of RuTSim should be verified before being used to analyze real worldproblems. In this master’s thesis, a verification of the new implementation of the RuTSim model, RuTSim 2,has been carried out. This paper includes a description of traffic micro-simulation models forrural roads in general and a description of RuTSim model in particular. Common verificationtechniques of the simulation models are also discussed in this study. Based on the theoretical assessments, a model-to-model comparison verification scheme isselected to verify the RuTSim 2 model. That is, the model verification is performed by comparingthe simulation outputs from RuTSim 2 to the old version of RuTSim (RuTSim 1), since RuTSim1 is well verified and calibrated. Statistical hypothesis tests are used to check whether the meanand standard deviation differences of the simulation outputs between the two simulators aresignificant or not. Based on the verification results, the new version of the RuTSim model has comparable modelingof vehicle-vehicle and vehicle-infrastructure interactions as the old version. Furthermore, thehypothesis test results show that the differences of the mean simulation results of the twosimulators are not significant. Therefore, the new implementation of RuTSim model, RuTSim 2,has been proven to be equivalent model as the old version.
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Allwörden, Hannes von Verfasser], and Ingenuin [Akademischer Betreuer] [Gasser. "Stability of Micro- and Macroscopic Traffic Flow Models on the Transition from Circular Road to Infinite Lane / Hannes von Allwörden ; Betreuer: Ingenuin Gasser." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://nbn-resolving.de/urn:nbn:de:gbv:18-105357.
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Allwörden, Hannes von [Verfasser], and Ingenuin [Akademischer Betreuer] Gasser. "Stability of Micro- and Macroscopic Traffic Flow Models on the Transition from Circular Road to Infinite Lane / Hannes von Allwörden ; Betreuer: Ingenuin Gasser." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1214370179/34.
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Goosen, Kelly. "Calibrating high frequency trading data to agent based models using approximate Bayesian computation." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33699.
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We consider Sequential Monte Carlo Approximate Bayesian Computation (SMC ABC) as a method of calibration for the use of agent based models in market micro-structure. To date, there are no successful calibrations of agent based models to high frequency trading data. Here we test whether a more sophisticated calibration technique, SMC ABC, will achieve this feat on one of the leading agent based models in high frequency trading literature (the Preis-Golke-Paul-Schneider Agent Based Model (Preis et al., 2006)). We find that, although SMC ABC's naive approach of updating distributions can successfully calibrate simple toy models, such as autoregressive moving average models, it fails to calibrate this agent based model for high frequency trading. This may be for two key reasons, either the parameters of the model are not uniquely identifiable given the model output or the SMC ABC rejection mechanism results in information loss rendering parameters unidentifiable given insucient summary statistics.
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Qi, Meng. "Development in Normal Mixture and Mixture of Experts Modeling." UKnowledge, 2016. http://uknowledge.uky.edu/statistics_etds/15.
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In this dissertation, first we consider the problem of testing homogeneity and order in a contaminated normal model, when the data is correlated under some known covariance structure. To address this problem, we developed a moment based homogeneity and order test, and design weights for test statistics to increase power for homogeneity test. We applied our test to microarray about Down’s syndrome. This dissertation also studies a singular Bayesian information criterion (sBIC) for a bivariate hierarchical mixture model with varying weights, and develops a new data dependent information criterion (sFLIC).We apply our model and criteria to birth- weight and gestational age data for the same model, whose purposes are to select model complexity from data.
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Mickelsson, Glenn. "DSGE Model Estimation and Labor Market Dynamics." Doctoral thesis, Uppsala universitet, Nationalekonomiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-301722.
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Essay 1: Estimation of DSGE Models with Uninformative Priors DSGE models are typically estimated using Bayesian methods, but because prior information may be lacking, a number of papers have developed methods for estimation with less informative priors (diffuse priors). This paper takes this development one step further and suggests a method that allows full information maximum likelihood (FIML) estimation of a medium-sized DSGE model. FIML estimation is equivalent to placing uninformative priors on all parameters. Inference is performed using stochastic simulation techniques. The results reveal that all parameters are identifiable and several parameter estimates differ from previous estimates that were based on more informative priors. These differences are analyzed. Essay 2: A DSGE Model with Labor Hoarding Applied to the US Labor Market In the US, some relatively stable patterns can be observed with respect to employment, production and productivity. An increase in production is followed by an increase in employment with lags of one or two quarters. Productivity leads both production and employment, especially employment. I show that it is possible to replicate this empirical pattern in a model with only one demand-side shock and labor hoarding. I assume that firms have organizational capital that depreciates if workers are utilized to a high degree in current production. When demand increases, firms can increase utilization, but over time, they have to hire more workers and reduce utilization to restore organizational capital. The risk shock turns out to be very dominant and explains virtually all of the dynamics. Essay 3: Demand Shocks and Labor Hoarding: Matching Micro Data In Swedish firm-level data, output is more volatile than employment, and in response to demand shocks, employment follows output with a one- to two-year lag. To explain these observations, we use a model with labor hoarding in which firms can change production by changing the utilization rate of their employees. Matching the impulse response functions, we find that labor hoarding in combination with increasing returns to scale in production and a very high price stickiness can explain the empirical pattern very well. Increasing returns to scale implies a larger percentage change in output than in employment. Price stickiness amplifies volatility in output because the price has a dampening effect on demand changes. Both of these explain the delayed reaction in employment in response to output changes.
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McDonald, Katrina Anne. "An experimental and finite element investigation of the biomechanics of vertebral compression fractures." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/30415/1/Katrina_McDonald_Thesis.pdf.
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Osteoporosis is a disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. Osteoporosis affects over 200 million people worldwide, with an estimated 1.5 million fractures annually in the United States alone, and with attendant costs exceeding $10 billion dollars per annum. Osteoporosis reduces bone density through a series of structural changes to the honeycomb-like trabecular bone structure (micro-structure). The reduced bone density, coupled with the microstructural changes, results in significant loss of bone strength and increased fracture risk. Vertebral compression fractures are the most common type of osteoporotic fracture and are associated with pain, increased thoracic curvature, reduced mobility, and difficulty with self care. Surgical interventions, such as kyphoplasty or vertebroplasty, are used to treat osteoporotic vertebral fractures by restoring vertebral stability and alleviating pain. These minimally invasive procedures involve injecting bone cement into the fractured vertebrae. The techniques are still relatively new and while initial results are promising, with the procedures relieving pain in 70-95% of cases, medium-term investigations are now indicating an increased risk of adjacent level fracture following the procedure. With the aging population, understanding and treatment of osteoporosis is an increasingly important public health issue in developed Western countries. The aim of this study was to investigate the biomechanics of spinal osteoporosis and osteoporotic vertebral compression fractures by developing multi-scale computational, Finite Element (FE) models of both healthy and osteoporotic vertebral bodies. The multi-scale approach included the overall vertebral body anatomy, as well as a detailed representation of the internal trabecular microstructure. This novel, multi-scale approach overcame limitations of previous investigations by allowing simultaneous investigation of the mechanics of the trabecular micro-structure as well as overall vertebral body mechanics. The models were used to simulate the progression of osteoporosis, the effect of different loading conditions on vertebral strength and stiffness, and the effects of vertebroplasty on vertebral and trabecular mechanics. The model development process began with the development of an individual trabecular strut model using 3D beam elements, which was used as the building block for lattice-type, structural trabecular bone models, which were in turn incorporated into the vertebral body models. At each stage of model development, model predictions were compared to analytical solutions and in-vitro data from existing literature. The incremental process provided confidence in the predictions of each model before incorporation into the overall vertebral body model. The trabecular bone model, vertebral body model and vertebroplasty models were validated against in-vitro data from a series of compression tests performed using human cadaveric vertebral bodies. Firstly, trabecular bone samples were acquired and morphological parameters for each sample were measured using high resolution micro-computed tomography (CT). Apparent mechanical properties for each sample were then determined using uni-axial compression tests. Bone tissue properties were inversely determined using voxel-based FE models based on the micro-CT data. Specimen specific trabecular bone models were developed and the predicted apparent stiffness and strength were compared to the experimentally measured apparent stiffness and strength of the corresponding specimen. Following the trabecular specimen tests, a series of 12 whole cadaveric vertebrae were then divided into treated and non-treated groups and vertebroplasty performed on the specimens of the treated group. The vertebrae in both groups underwent clinical-CT scanning and destructive uniaxial compression testing. Specimen specific FE vertebral body models were developed and the predicted mechanical response compared to the experimentally measured responses. The validation process demonstrated that the multi-scale FE models comprising a lattice network of beam elements were able to accurately capture the failure mechanics of trabecular bone; and a trabecular core represented with beam elements enclosed in a layer of shell elements to represent the cortical shell was able to adequately represent the failure mechanics of intact vertebral bodies with varying degrees of osteoporosis. Following model development and validation, the models were used to investigate the effects of progressive osteoporosis on vertebral body mechanics and trabecular bone mechanics. These simulations showed that overall failure of the osteoporotic vertebral body is initiated by failure of the trabecular core, and the failure mechanism of the trabeculae varies with the progression of osteoporosis; from tissue yield in healthy trabecular bone, to failure due to instability (buckling) in osteoporotic bone with its thinner trabecular struts. The mechanical response of the vertebral body under load is highly dependent on the ability of the endplates to deform to transmit the load to the underlying trabecular bone. The ability of the endplate to evenly transfer the load through the core diminishes with osteoporosis. Investigation into the effect of different loading conditions on the vertebral body found that, because the trabecular bone structural changes which occur in osteoporosis result in a structure that is highly aligned with the loading direction, the vertebral body is consequently less able to withstand non-uniform loading states such as occurs in forward flexion. Changes in vertebral body loading due to disc degeneration were simulated, but proved to have little effect on osteoporotic vertebra mechanics. Conversely, differences in vertebral body loading between simulated invivo (uniform endplate pressure) and in-vitro conditions (where the vertebral endplates are rigidly cemented) had a dramatic effect on the predicted vertebral mechanics. This investigation suggested that in-vitro loading using bone cement potting of both endplates has major limitations in its ability to represent vertebral body mechanics in-vivo. And lastly, FE investigation into the biomechanical effect of vertebroplasty was performed. The results of this investigation demonstrated that the effect of vertebroplasty on overall vertebra mechanics is strongly governed by the cement distribution achieved within the trabecular core. In agreement with a recent study, the models predicted that vertebroplasty cement distributions which do not form one continuous mass which contacts both endplates have little effect on vertebral body stiffness or strength. In summary, this work presents the development of a novel, multi-scale Finite Element model of the osteoporotic vertebral body, which provides a powerful new tool for investigating the mechanics of osteoporotic vertebral compression fractures at the trabecular bone micro-structural level, and at the vertebral body level.
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Cairone, Fabiana. "Models and Systems for the Control of Two-Phase Processes in Microfluidics." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4147.
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The strong point of the microfluidics is the ability to miniaturize and integrate one or several laboratory functions on the same device, to have a portable and user-friendly instrument. Most applications require accurate measures and control within the microfluidic channels. In this thesis, the optical techniques were adopted to monitor, sensing and control the processes, leading to the research area of optofluidics that are based on the integration of fluidics and optics. To reduce the cost to develop these devices, the 3D Printing technology based on the Poly(dimethyl-siloxane) (PDMS) is proposed. All these aspects were addressed considering the two-phase flow (named slug) generated by the interaction of two immiscible fluids, a very common condition in bio-chemical applications. The methodological aspects were discussed in the first part of the thesis, starting from the extraction of parameters for the flow characterization, to their use for the flows real-time modelling and control schemes development; the second part investigates aspects faced for the realization of micro-optical flow detector by using the 3D Printing technology.
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Yendodu, Vishnu Vardhan Reddy. "A comprehensive database on air plasma kinetics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25762/.
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The kinetic models described in this thesis are of great importance because they can be used to understand the chemical phenomena induced by electrical discharges in air. Experimental data obtained by the research group in the Physics Department of the University Milano Bicocca are compared with the numerical results. The study highlighted how the initial ozone formation is inhibited and cancelled by nitrogen oxidation processes.
In this thesis, a comprehensive database on Air Plasma Kinetic reactions with rate coefficients is presented. The database were built from Park Model and Sakiyama Model. In both models, the references to rate coefficients vary from the real material, and not all the rate coefficients satisfy the references. The database built is made ready for implementation on ZDPlasKin software.
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Sandino, Velásquez Clara Inés. "Simulation of mechanoregulation and tissue differentiation in calcium phosphate scaffolds for tissue engineering." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6211.
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Los estímulos mecánicos son uno de los factores que afectan a la diferenciación celular en el proceso de regeneración del tejido óseo, por lo tanto, en el desarrollo de andamios para ingeniería de tejidos, se pueden aplicar las cargas mecánicas con el fin de inducir la actividad de las células. Cuando se aplican cargas mecánicas, los estímulos mecánicos específicos transmitidos a las células a nivel microscópico pueden estudiarse mediante técnicas numéricas. El objetivo de esta tesis fue estudiar la mecanoregulación de la diferenciación de tejido en andamios de fosfato de calcio utilizando modelos de elementos finitos basados en micro tomografía axial computarizada.Dos muestras de materiales porosos basados en fosfato de calcio fueron utilizadas. Se desarrollaron mallas de elementos finitos congruentes, discretizando la fase sólida y los macro poros interconectados, con el fin de tener en cuenta la morfología irregular de los andamios.
En primer lugar, se estudió la distribución de los estímulos mecánicos. La fase sólida y el fluido intersticial se simularon como material elástico lineal y como fluido Newtoniano, respectivamente. Se simuló una compresión del 0.5% en el sólido y un fluido con velocidades de entrada de 1, 10 y 100 µm/s en los poros. Se encontraron distribuciones de deformación similares en las paredes ambos materiales, con valores máximos de 1.6% en compresión y de 0.6% en tracción. En algunos poros, la velocidad del fluido aumentó a 100 y 1000 veces la velocidad de entrada. Este estudio mostró como estímulos mecánicos macroscópicos pueden causar distintos niveles de estímulos mecánicos microscópicos dentro los andamios, debido a la morfología.
A continuación se realizó un estudio en el tiempo de la diferenciación de tejido en un andamio sometido a condiciones in vitro. La compresión y la perfusión se modelaron como en el estudio anterior. Se simularon una compresión del 0.5% y una velocidad de entrada de fluido constante de 10 µm/s o una presión de entrada de fluido constante de 3 Pa. La deformación cortante octaédrica y el esfuerzo cortante del fluido se utilizaron como estímulos mecano-regulatorios basándose en la teoría de Prendergast et al. (1997). Al aplicar velocidad constante, se predijeron fluctuaciones entre los estímulos equivalentes a la formación de tejido y a la muerte celular, debido al aumento en el esfuerzo cortante del fluido cuando el tejido comienza a llenar los poros. Sin embargo, al aplicar presión constante, se predijo estímulo equivalente a la diferenciación de tejido óseo en la mitad del volumen de los poros. Estos resultados sugieren que para permitir la diferenciación de tejido, la velocidad del fluido debe disminuirse cuando el tejido empieza a mineralizarse.
Finalmente, se llevó acabo un estudio en el tiempo de la angiogénesis y de la diferenciación de tejido en un andamio bajo condiciones in vivo. La deformación cortante octaédrica y la velocidad relativa del fluido se utilizaron como estímulos mecano-regulatorios. Las fases sólida y porosa fueron tratadas como materiales poroelásticos. Se simuló la actividad individual de las células. Compresiones de 0.5 y 1% fueron simuladas. La mayoría de los vasos crecieron en los poros de la periferia del andamio y se bloquearon por las paredes. Se formaron redes capilares similares independientemente de la magnitud de deformación utilizada. Al aplicar 0.5% de compresión, estímulos correspondientes a la formación de hueso se predijeron en el 70% del volumen de los poros, sin embargo, sólo el 40% del volumen se llenó de osteoblastos debido a la falta de oxigeno. Este estudio mostró el efecto de la falta de vascularización en el centro del andamio en la diferenciación de tejido.
Ese tipo de estudios, combinados con estudios in vitro, deberían contribuir a la comprensión del proceso de diferenciación de los tejidos dentro de los andamios y por lo tanto a la mejora de los métodos de diseño de andamios.
Mechanical stimuli are one of the factors that affect cell differentiation in the process of bone tissue regeneration; therefore, in the development of scaffolds for tissue engineering, mechanical loads can be applied in order to induce cell activity. The specific mechanical stimuli transmitted to cells at a microscopic level when mechanical loads are applied can be studied using numerical techniques. The objective of this thesis was to study the mechanoregulation of tissue differentiation within calcium phosphate scaffolds using micro computed tomographed based finite element models.
Two samples of porous calcium phosphate based materials were used. Congruent finite element meshes, with the solid phase and the interconnected pores discretized, were developed in order to account for the scaffold irregular morphology.
First, a study of the distribution of mechanical stimuli was performed. The solid phase and the fluid flow within the pores were modeled as linear elastic solid material and Newtonian fluid respectively. Compressive strains of 0.5% of total deformation applied to the solid and interstitial fluid flows with inlet velocities of 1, 10 and 100 µm/s applied to the pores were simulated. Similar strain distributions for both materials were found, with compressive and tensile strain maximal values of 1.6% and 0.6% respectively. For the fluid flow models, the fluid velocity in some of the scaffold pores increased to 100 and 1000 times the inlet velocity. This study showed how mechanical loads and fluid flow applied to the scaffolds caused different levels of mechanical stimuli within the samples according to the morphology of the materials.
Next, a study of the mechanoregulation of tissue differentiation over time in a scaffold subjected to in vitro loads was performed. The solid phase and the fluid flow were modeled as in the study described above. Compressive strain of 0.5% and fluid flow with constant inlet velocity of 10 µm/s or constant inlet pressure of 3 Pa were applied. Octahedral shear strain and fluid shear stress were used as mechano-regulatory stimuli based on the theory of Prendergast et al. (1997). When a constant velocity was simulated, fluctuations between stimuli equivalent to tissue formation and cell death were predicted due to the increase in the fluid shear stress when tissue started to fill the pores. However, when constant pressure was applied, stimuli equivalent to bone formation were predicted in about half of the pore volume. These results suggest that in order to allow tissue differentiation within a scaffold, the fluid velocity should be decreased when tissue starts mineralizing.
Finally, a study of the angiogenesis and the mechanoregulation of tissue differentiation over time in a scaffold subjected to in vivo conditions was performed. Octahedral shear strain and relative fluid velocity were used as mechano-regulatory stimuli. The solid and pore phases were treated as poroelastic materials. Individual cell activity was simulated within the pore domain. Compressive strains of 0.5 and 1% of total deformation were simulated. Most vessels grew in the pores at the periphery of the scaffolds and were blocked by the scaffold walls. Similar capillary networks were formed independently of the magnitude of the mechanical strain applied. When 0.5% of strain was applied, 70% of the pore volume was affected by mechano-regulatory stimuli corresponding to bone formation; however, because of the lack of oxygen, only 40% of the volume was filled with osteoblasts. This study showed the effect of the lack of vascularization in the center of the scaffold on the tissue differentiation.
Such kind of studies, combined with in vitro studies, should contribute to the understanding of the process of tissue differentiation within the constructs and therefore to the improvement of scaffold design methods.
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Clark, Peter G. "Multi-scale modelling describing thermal behaviour of polymeric materials. Scalable lattice-Boltzmann models based upon the theory of Grmela towards refined thermal performance prediction of polymeric materials at micro and nano scales." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5768.
Full textAbstract:
Micrometer injection moulding is a type of moulding in which moulds have geometrical
design features on a micrometer scale that must be transferred to the
geometry of the produced part. The difficulties encountered due to very high shear
and rapid heat transfer of these systems has motivated this investigation into the
fundamental mathematics behind polymer heat transfer and associated processes.
The aim is to derive models for polymer dynamics, especially heat dynamics, that
are considerably less approximate than the ones used at present, and to translate
this into simulation and optimisation algorithms and strategies, Thereby allowing
for greater control of the various polymer processing methods at micrometer scales.