Influence of spatial variability of permeability property on steady state seepage flow and slope stability analysis

In recent years, spatial variability modeling of soil parameters using random field theory has gained distinct importance in geotechnical analysis. In the present Study, commercially available finite difference numerical code FLAC 5.0 is used for modeling the permeability parameter as spatially correlated log-normally distributed random variable and its influence on the steady state seepage flow and on the slope stability analysis are studied. Considering the case of a 5.0 m high cohesive-frictional soil slope of 30 degrees, a range of coefficients of variation (CoV%) from 60 to 90% in the permeability Values, and taking different values of correlation distance in the range of 0.5-15 m, parametric studies, using Monte Carlo simulations, are performed to study the following three aspects, i.e., (i) effect ostochastic soil permeability on the statistics of seepage flow in comparison to the analytic (Dupuit's) solution available for the uniformly constant permeability property; (ii) strain and deformation pattern, and (iii) stability of the given slope assessed in terms of factor of safety (FS). The results obtained in this study are useful to understand the role of permeability variations in slope stability analysis under different slope conditions and material properties. (C) 2009 Elsevier B.V. All rights reserved.

Cenários de mudanças climáticas usando modelagem dinâmica na Bacia do Alto Taquari.

A região Centro-Oeste do Brasil tornou-se nos últimos 40 anos grande produtora de grãos e carne bovina. As condições edafoclimáticas, o sistema de manejo do solo e o descumprimento de leis ambientais trouxeram conseqüências drásticas à região como o agravamento do processo hídrico erosivo, principalmente na Bacia do Alto Taquari (BAT). Cerca de 90% da BAT localiza-se na porção norte do estado de Mato Grosso do Sul (MS), porém os efeitos do transporte de sedimentos e volume de água são refletidos a jusante dos rios, na Bacia do Pantanal. Utilizando-se pressupostos do Painel Intergovernamental de Mudanças Climáticas (IPCC) foram estabelecidos cenários de mudanças climáticas na Bacia do Alto Taquari, visando identificar áreas com maior vulnerabilidade ao processo erosivo em função de pressões de uso da terra. Usando a modelagem dinâmica no TerraME (Environment Modeling) foram gerados cenários topopluviais até 2100, considerando-se para a temperatura do ar média anual um aumento de 1C, em cenário otimista e, em pessimista, elevações térmicas de 3C. Para a precipitação pluvial média anual um cenário foi com aumento de 15% e outro com reduções de 15%. Os dados foram espacializados no ArcGis 9.2 e exportados para o TerraView 3.2, criando-se espaços celulares e integrando-se com as informações do modelo digital do terreno do Shuttle Radar Topography Mission (SRTM) para geração dos mapas topoclimáticos e simulações de cenários no TerraMe. Os resultados apontam que 85% da área da BAT nas condições atuais as temperaturas médias variam entre 23,6 a 25,7C. As simulações térmicas no cenário otimista indicam que em 40 anos as temperaturas tendem a superar o maior limite térmico médio nas áreas ao longo do rio Taquari, no sentido Oeste-Leste. Esses valores evidenciam elevações nas taxas evapotranspiratórias de matas ciliares, indicando reduções na vazão do Taquari. Em cenário pessimista essas temperaturas antecipam sua ocorrência, em um prazo de 20 anos. Os cenários com acréscimo de 15% na precipitação pluvial mostram aumentos no volume de água precipitada na parte norte da Bacia, região mais vulnerável aos problemas de erosão hídrica. Cenários do regime térmico-hídrico apontam áreas mais sensíveis às mudanças climáticas na parte oeste da BAT e impactos ambientais também na Bacia do Pantanal. Conclui-se que o TerraME é indicado para gerar cenários de mudanças climáticas em bacias hidrográficas.

Temporal and Spatial Distributions of Rotifers in Xiangxi Bay of the Three Gorges Reservoir, China

From July 2003 to June 2005, investigations of rotifer temporal and spatial distributions were carried out in a bay of the Three Gorges Reservoir, Xiangxi Bay, which is the downstream segment of the Xiangxi River and the nearest bay to the Three Gorges Reservoir dam in Hubei Province, China. Thirteen sampling sites were selected. The results revealed a high species diversity, with 76 species, and 14 dominant species; i.e., Polyarthra vulgaris, Keratella cochlearis, Keratella valga, Synchaeta tremula, Synchaeta stylata, Trichocerca lophoessa, Trichocerca pusilla, Brachionus angularis, Brachionus calyciflorus, Brachionus forficula forficula, Ascomorpha ovalis, Conochilus unicornis, Ploesoma truncatum and Anuraeopsis fissa. After the first year of the reservoir impoundment, the rotifer community was dominated by ten species; one year later it was dominated by eight species. The community in 2003/2004 was dissimilar to that in 2004/2005, which resulted from the succession of the dominant species. The rotifer community exhibited a patchy distribution, with significant heterogeneity observed along the longitudinal axis. All rotifer communities could be divided into three groups, corresponding to the riverine, the transition and the lacustrine zone, respectively.

Dynamic analysis of Flip-Chip Self-Alignment

Self-alignment of soldered electronic components such as flip-chips (FC), ball grid arrays (BGA) and optoelectronic devices during solder reflow is important as it ensures good alignment between components and substrates. Two uncoupled analytical models are presented which provide estimates of the dynamic time scales of both the chip and the solder in the self-alignment process. These predicted time scales can be used to decide whether a coupled dynamic analysis is required for the analysis of the chip motion. In this paper, we will show that for flip-chips, the alignment dynamics can be described accurately only when the chip motion is coupled with the solder motion because the two have similar time-scale values. To study this coupled phenomenon, a dynamic modeling method has been developed. The modeling results show that the uncoupled and coupled calculations result in significantly different predictions. The calculations based on the coupled model predict much faster rates of alignment than those predicted using the uncoupled approach.

Le développement économique régional, la politique et les disparités régionales des grands territoires : le cas du Canada et de la Chine

Résumé Depuis le début des années 1990, la recherche sur le développement régional a pris une importance considérable dans les disciplines de l’économie et de la géographie dans la plupart des pays. De nombreuses études ont été consacrées à ce sujet et l’on constate une approche analytique de plus en plus sophistiquée. Que les économies pauvres ont tendance à converger vers les pays riches, ou bien à diverger au fil du temps est une question qui a attiré l'attention des décideurs et des universitaires depuis quelques décennies. Convergence ou de divergence économique est un sujet d'intérêt et de débat, non seulement pour valider ou non les deux modèles principaux de croissance qui sont considérés comme concurrent (l’approche néo-classique et celle des approches de croissance endogène), mais aussi pour ses implications pour les publiques politiques. En se basant sur une analyse des politiques de développement régional et des analyses statistiques de la convergence et des disparités régionales, les objectifs de cette thèse sont de tenter de fournir une explication des différents processus et des modèles de développement économique régional poursuivis dans le cas de territoires immenses en utilisant le Canada et la Chine comme études de cas, d'entreprendre une analyse des différents facteurs et des forces motrices qui sous-tendent le développement régional dans ces deux pays, et d'explorer à la fois les réussites et les échecs apparents dans les politiques de développement régional en comparant et contrastant les expériences de développement régional et les modèles de ces deux pays. A fin d'atteindre cet objectif, la recherche utilise une approche multi-scalaire et des méthodes de mesure multidimensionnelle dans le cadre des analyses sur les disparités « régionales » entre les macro régions (sous-ensembles de provinces) des deux pays, des provinces et des régions urbaines sélectionnées, dans le but ultime d’identifier des problèmes existants en termes de développement régional et de pouvoir proposer des solutions. Les étapes principales de la recherche sont : 1. La cueillette des données statistiques pour le Canada et la Chine (incluant les provinces de Québec et de Xinjiang) pour une gamme d’indicateurs (voir ci-dessous). 2. D’entreprendre une analyse de chaque dimension dans les deux juridictions: Population (p.ex. composition, structure, changement); Ressources (p. ex. utilisation, exploitation de l’énergie); Environnement (p.ex. la pollution); et le Développement socioéconomique (p.ex. le développement et la transformation des secteurs clé, et les modèles de développement rural et urbain), et les disparités changeantes par rapport à ces dimensions. 3. La définition d’une typologie de différents types de région en fonction de leurs trajectoires de développement, ce qui servira pour critiquer l’hypothèse centre-périphérie. 4. Le choix d’une région métropolitaine dans chaque juridiction (province). 5. D’entreprendre une analyse temporelle des événements clé (politiques, investissements) dans chaque région et les facteurs impliqués dans chaque événement, en utilisant l’information documentaire générale et des agences institutionnelles impliqués actuellement et dans un passée récent. Cette étude a tenté d'expliquer les schémas et les processus des deux économies, ainsi que la présentation d'études de cas qui illustrent et examinent les différences dans les deux économies à partir de l’échelle nationale jusqu’au niveau régional et provincial et aussi pour certaines zones urbaines. Cette étude a essayé de répondre aux questions de recherche comme: Est-il vrai que les pays avec des plus grandes territoires sont associés avec des plus grandes disparités interrégionales? Quel est le résultat des comparaisons entre pays développés et pays en développement? Quels sont les facteurs les plus importants dans le développement économique de vastes territoires dans les pays développés et pays en développement? Quel est le mécanisme de convergence et de divergence dans les pays développés et, respectivement, les pays en développement? Dans l'introduction à la thèse, le cadre général de l'étude est présenté, suivie dans le chapitre 1 d'une discussion sur les théories et les concepts utilisés dans la littérature théorique principale qui est pertinent à l'étude. Le chapitre 2 décrit la méthodologie de recherche. Le chapitre 3 présente une vue d'ensemble des politiques de développement économique régional et les programmes du Canada et de la Chine dans des périodes différentes à différentes échelles. Au chapitre 4, la convergence des deux pays à l'échelle nationale et la convergence provinciale pour chaque pays sont examinés en utilisant différentes méthodes de mesure telles que les méthodes traditionnelles, la convergence bêta et la convergence sigma. Dans le chapitre le plus complexe, le chapitre 5, les analyses comparatives sont présentées à l'aide de données statistiques, à partir des analyses des cas régionaux et provinciaux retenus des deux pays. Au chapitre 6, ces dispositions sont complétées par une analyse des régions urbaines choisies, qui permet également des aperçus sur les régions les plus périphériques. Dans la recherche proposée pour cette thèse, la politique, la population, le revenu, l'emploi, la composition industrielle, l'investissement, le commerce et le facteur de la migration sont également pris en compte comme facteurs importants de l'analyse régionale compte tenu de la superficie du territoire des deux pays et les différences de population entre eux. Cette thèse a évalué dans quelle mesure les politiques gouvernementales ont réussi à induire la convergence régionale ou ont encore ont creusé davantage les disparités régionales, ce qui implique nécessairement une évaluation de la durabilité des patrons et des programmes de développement régional. Cette étude a également mis l'accent sur les disparités régionales et la politique de développement régional, les comparaisons entre pays, pour mesurer la convergence entre les pays et entre les régions, y compris l'analyse spatiale, d'identifier les facteurs les plus actifs tels que la population, les ressources, la politique, l'urbanisation, les migrations, l'ouverture économique et leurs différents rôles dans le développement économique de ces grands territoires (au Canada et Chine). Les résultats empiriques et les processus de convergence et de divergence offrent un cadre intéressant pour l'examen de la trajectoire de développement régionales et les disparités régionales dans les deux économies. L'approche adoptée a révélé les différentes mosaïques complexes du développement régional dans les deux pays. Les résultats de cette étude ont démontré que la disparité en termes de revenu régional est une réalité dans chaque zone géographique, et que les causes sont nombreuses et complexes. Les deux économies ont certains parallèles dans la mise en œuvre des politiques de développement économique régional, mais il existe des différences importantes aussi et elles se sont développées à différentes vitesses. Les deux économies se sont développées depuis la Seconde Guerre mondiale, mais la Chine a connu une croissance rapide que le Canada comme témoignent de nombreux indicateurs depuis 1980. Cependant, la Chine est maintenant confrontée à un certain nombre de problèmes économiques et sociaux, y compris les disparités régionales marquées, un fossé toujours croissant entre les revenus ruraux et urbains, une population vieillissante, le chômage, la pauvreté et la dégradation rapide de l'environnement avec toujours plus de demandes en énergie. Le développement économique régional en Chine est plus déséquilibré. Le Canada accuse un degré de disparités régionales et provinciales moins important que la Chine. Dans les cas provinciaux, il existe d'importantes différences et de disparités dans la structure économique et spatiale du Québec et du Xinjiang. Les disparités infra provinciales sont plus grandes que celles à l’échelle des provinces et des grandes régions (des sous-ensembles de provinces). Les mécanismes de convergence et de divergence dans les deux pays sont différents. Les résultats empiriques et les processus de convergence et de divergence offrent un cadre intéressant pour l'examen de la trajectoire de développement régionale et les disparités régionales dans les deux économies. Cette étude démontre également que l'urbanisation (les métropoles et les villes) s’avère être le facteur le plus actif et contribue à l'économie régionale dans ces grands territoires. L'ouverture a joué un rôle important dans les économies des deux pays. La migration est un facteur majeur dans la stimulation de l'économie des deux pays mais de façons différentes. Les résultats empiriques démontrent que les disparités régionales ne peuvent pas être évitées et elles existent presque partout. Il n'y a pas une formule universelle et de politiques spécifiques sont de mise pour chaque région. Mais il semble possible pour les décideurs politiques nationaux et régionaux d’essayer de maintenir l'écart à une échelle raisonnable pour éviter l'instabilité sociale.

De lo micro a lo macro prudencial: Un análisis de la supervisión bancaria desde la econometría espacial

La crisis que se desató en el mercado hipotecario en Estados Unidos en 2008 y que logró propagarse a lo largo de todo sistema financiero, dejó en evidencia el nivel de interconexión que actualmente existe entre las entidades del sector y sus relaciones con el sector productivo, dejando en evidencia la necesidad de identificar y caracterizar el riesgo sistémico inherente al sistema, para que de esta forma las entidades reguladoras busquen una estabilidad tanto individual, como del sistema en general. El presente documento muestra, a través de un modelo que combina el poder informativo de las redes y su adecuación a un modelo espacial auto regresivo (tipo panel), la importancia de incorporar al enfoque micro-prudencial (propuesto en Basilea II), una variable que capture el efecto de estar conectado con otras entidades, realizando así un análisis macro-prudencial (propuesto en Basilea III).

Network externalities across financial institutions

We propose and estimate a financial distress model that explicitly accounts for the interactions or spill-over effects between financial institutions, through the use of a spatial continuity matrix that is build from financial network data of inter bank transactions. Such setup of the financial distress model allows for the empirical validation of the importance of network externalities in determining financial distress, in addition to institution specific and macroeconomic covariates. The relevance of such specification is that it incorporates simultaneously micro-prudential factors (Basel 2) as well as macro-prudential and systemic factors (Basel 3) as determinants of financial distress. Results indicate network externalities are an important determinant of financial health of a financial institutions. The parameter that measures the effect of network externalities is both economically and statistical significant and its inclusion as a risk factor reduces the importance of the firm specific variables such as the size or degree of leverage of the financial institution. In addition we analyze the policy implications of the network factor model for capital requirements and deposit insurance pricing.

Nonlinear dynamic model and simulation of morphing wing profile actuated by shape memory alloys

Morphing aircraft have the ability to actively adapt and change their shape to achieve different missions efficiently. The development of morphing structures is deeply related with the ability to model precisely different designs in order to evaluate its characteristics. This paper addresses the dynamic modeling of a sectioned wing profile (morphing airfoil) connected by rotational joints (hinges). In this proposal, a pair of shape memory alloy (SMA) wires are connected to subsequent sections providing torque by reducing its length (changing airfoil camber). The dynamic model of the structure is presented for one pair of sections considering the system with one degree of freedom. The motion equations are solved using numerical techniques due the nonlinearities of the model. The numerical results are compared with experimental data and a discussion of how good this approach captures the physical phenomena associated with this problem. © The Society for Experimental Mechanics, Inc. 2012.

MODELING AND PROTOCOL DESIGN FOR EMERGING WIRELESS SYSTEMS

Mobile Mesh Network based In-Transit Visibility (MMN-ITV) system facilitates global real-time tracking capability for the logistics system. In-transit containers form a multi-hop mesh network to forward the tracking information to the nearby sinks, which further deliver the information to the remote control center via satellite. The fundamental challenge to the MMN-ITV system is the energy constraint of the battery-operated containers. Coupled with the unique mobility pattern, cross-MMN behavior, and the large-spanned area, it is necessary to investigate the energy-efficient communication of the MMN-ITV system thoroughly. First of all, this dissertation models the energy-efficient routing under the unique pattern of the cross-MMN behavior. A new modeling approach, pseudo-dynamic modeling approach, is proposed to measure the energy-efficiency of the routing methods in the presence of the cross-MMN behavior. With this approach, it could be identified that the shortest-path routing and the load-balanced routing is energy-efficient in mobile networks and static networks respectively. For the MMN-ITV system with both mobile and static MMNs, an energy-efficient routing method, energy-threshold routing, is proposed to achieve the best tradeoff between them. Secondly, due to the cross-MMN behavior, neighbor discovery is executed frequently to help the new containers join the MMN, hence, consumes similar amount of energy as that of the data communication. By exploiting the unique pattern of the cross-MMN behavior, this dissertation proposes energy-efficient neighbor discovery wakeup schedules to save up to 60% of the energy for neighbor discovery. Vehicular Ad Hoc Networks (VANETs)-based inter-vehicle communications is by now growingly believed to enhance traffic safety and transportation management with low cost. The end-to-end delay is critical for the time-sensitive safety applications in VANETs, and can be a decisive performance metric for VANETs. This dissertation presents a complete analytical model to evaluate the end-to-end delay against the transmission range and the packet arrival rate. This model illustrates a significant end-to-end delay increase from non-saturated networks to saturated networks. It hence suggests that the distributed power control and admission control protocols for VANETs should aim at improving the real-time capacity (the maximum packet generation rate without causing saturation), instead of the delay itself. Based on the above model, it could be determined that adopting uniform transmission range for every vehicle may hinder the delay performance improvement, since it does not allow the coexistence of the short path length and the low interference. Clusters are proposed to configure non-uniform transmission range for the vehicles. Analysis and simulation confirm that such configuration can enhance the real-time capacity. In addition, it provides an improved trade off between the end-to-end delay and the network capacity. A distributed clustering protocol with minimum message overhead is proposed, which achieves low convergence time.

A contribution on modeling methodologies for multibody systems.

Multibody System Dynamics has been responsible for revolutionizing Mechanical Engineering Design by using mathematical models to simulate and optimize the dynamic behavior of a wide range of mechanical systems. These mathematical models not only can provide valuable informations about a system that could otherwise be obtained only by experiments with prototypes, but also have been responsible for the development of many model-based control systems. This work represents a contribution for dynamic modeling of multibody mechanical systems by developing a novel recursive modular methodology that unifies the main contributions of several Classical Mechanics formalisms. The reason for proposing such a methodology is to motivate the implementation of computational routines for modeling complex multibody mechanical systems without being dependent on closed source software and, consequently, to contribute for the teaching of Multibody System Dynamics in undergraduate and graduate levels. All the theoretical developments are based on and motivated by a critical literature review, leading to a general matrix form of the dynamic equations of motion of a multibody mechanical system (that can be expressed in terms of any set of variables adopted for the description of motions performed by the system, even if such a set includes redundant variables) and to a general recursive methodology for obtaining mathematical models of complex systems given a set of equations describing the dynamics of each of its uncoupled subsystems and another set describing the constraints among these subsystems in the assembled system. This work also includes some discussions on the description of motion (using any possible set of motion variables and admitting any kind of constraint that can be expressed by an invariant), and on the conditions for solving forward and inverse dynamics problems given a mathematical model of a multibody system. Finally, some examples of computational packages based on the novel methodology, along with some case studies, are presented, highlighting the contributions that can be achieved by using the proposed methodology.

The New Software Package for Dynamic Hierarchical Clustering for Circles Types of Shapes

In data mining, efforts have focused on finding methods for efficient and effective cluster analysis in large databases. Active themes of research focus on the scalability of clustering methods, the effectiveness of methods for clustering complex shapes and types of data, high-dimensional clustering techniques, and methods for clustering mixed numerical and categorical data in large databases. One of the most accuracy approach based on dynamic modeling of cluster similarity is called Chameleon. In this paper we present a modified hierarchical clustering algorithm that used the main idea of Chameleon and the effectiveness of suggested approach will be demonstrated by the experimental results.

Freshwater Resource Supply Modeling for Developed and Undeveloped Watersheds

Globally, the current state of freshwater resource management is insufficient and impeding the chance at a sustainable future. Human interference within the natural hydrologic cycle is becoming dangerously irreversible and the need to redefine resource managerial approaches is imminent. This research involves the development of a coupled natural-human freshwater resource supply model using a System Dynamics approach. The model was applied to two case studies, Somalia, Africa and the Phoenix Active Management Area in Arizona, USA. It is suggested that System Dynamic modeling would be an invaluable tool for achieving sustainable freshwater resource management in individual watersheds. Through a series of thought experiments, a thorough understanding of the systems’ dynamic behaviors is obtainable for freshwater resource managers and policy-makers to examine various courses of action for alleviating freshwater supply concerns. This thesis reviews the model, its development and an analysis of several thought experiments applied to the case studies.

Structural Time Series Modeling: an Application to Environmental Variables

A structural time series model is one which is set up in terms of components which have a direct interpretation. In this paper, the discussion focuses on the dynamic modeling procedure based on the state space approach (associated to the Kalman filter), in the context of surface water quality monitoring, in order to analyze and evaluate the temporal evolution of the environmental variables, and thus identify trends or possible changes in water quality (change point detection). The approach is applied to environmental time series: time series of surface water quality variables in a river basin. The statistical modeling procedure is applied to monthly values of physico- chemical variables measured in a network of 8 water monitoring sites over a 15-year period (1999-2014) in the River Ave hydrological basin located in the Northwest region of Portugal.

A NOVEL MODELING AND STATE OF CHARGE ESTIMATION SCHEME FOR LITHIUM-ION BATTERIES

Lithium Ion (Li-Ion) batteries have got attention in recent decades because of their undisputable advantages over other types of batteries. They are used in so many our devices which we need in our daily life such as cell phones, lap top computers, cameras, and so many electronic devices. They also are being used in smart grids technology, stand-alone wind and solar systems, Hybrid Electric Vehicles (HEV), and Plug in Hybrid Electric Vehicles (PHEV). Despite the rapid increase in the use of Lit-ion batteries, the existence of limited battery models also inadequate and very complex models developed by chemists is the lack of useful models a significant matter. A battery management system (BMS) aims to optimize the use of the battery, making the whole system more reliable, durable and cost effective. Perhaps the most important function of the BMS is to provide an estimate of the State of Charge (SOC). SOC is the ratio of available ampere-hour (Ah) in the battery to the total Ah of a fully charged battery. The Open Circuit Voltage (OCV) of a fully relaxed battery has an approximate one-to-one relationship with the SOC. Therefore, if this voltage is known, the SOC can be found. However, the relaxed OCV can only be measured when the battery is relaxed and the internal battery chemistry has reached equilibrium. This thesis focuses on Li-ion battery cell modelling and SOC estimation. In particular, the thesis, introduces a simple but comprehensive model for the battery and a novel on-line, accurate and fast SOC estimation algorithm for the primary purpose of use in electric and hybrid-electric vehicles, and microgrid systems. The thesis aims to (i) form a baseline characterization for dynamic modeling; (ii) provide a tool for use in state-of-charge estimation. The proposed modelling and SOC estimation schemes are validated through comprehensive simulation and experimental results.