This dissertation presents dynamic system models of continuous manufacturing systems based on analogies with electrical systems. The developed modeling technique has the capability to explicitly specify production control schemes including control points, material and information flow paths, and logical operations. The model provides standard graphical representations and governing equations to describe both the steady state and transient responses of continuous manufacturing systems. For deterministic systems, these equations can be solved to get closed-form solutions. For stochastic systems, numerical solutions can be obtained for any probabilistic distribution. The electrical analogs provide an excellent tool to model control signals and logical operations. This is especially important for pull control schemes where qualitative descriptions often found in the literature can be ambiguous. The proposed technique is demonstrated by modeling push and a variety of pull systems. The developed models are used to study the relative performance of push, CONWIP, and kanban control systems. The results show that the card count distribution significantly affects the performance of a kanban system, and that drawing conclusions on kanban performance requires card count optimization. The results also show that the relative performance of push and CONWIP systems varies with operational factors. The factors studied in this dissertation are the bottleneck utilization, line balance, demand rate variability, and processing rate variability. At some combinations of these factors, the push system is superior to the CONWIP system, with other combinations, the CONWIP system is the superior system. In this work, push systems tend to have better relative performance (compared to CONWIP) at high variability levels in the processing rates and low variability levels in the demand rate, while CONWIP systems tend to have better relative performance (compared to push) at high variability levels in the demand rate and low variability levels in the processing rates. CONWIP systems tend to have higher relative performance at high utilization levels and in lines where a distinct bottleneck exists.

Τα τελευταία χρόνια παρουσιάζεται μία ραγδαία ανάπτυξη των φορητών συσκευών οι οποίες παρέχουν στον χρήστη την δυνατότητα πρόσβασης στον Παγκόσμιο Ιστό και, κατ' επέκταση, την δυνατότητα πλοήγησης στις εφαρμογές του Παγκοσμίου Ιστού του ενδιαφέροντος του. Είναι γεγονός, όμως, ότι οι περισσότερες εφαρμογές του Παγκοσμίου Ιστού έχουν σχεδιαστεί και αναπτυχθεί ώστε να απεικονίζουν αποδοτικά το περιεχόμενό τους κυρίως στους προσωπικούς επιτραπέζιους υπολογιστές. Δεδομένου ότι οι φορητές συσκευές διαθέτουν οθόνη περιορισμένου μεγέθους και ανάλυσης σε σχέση με τους επιτραπέζιους υπολογιστές, ο χρήστης αναγκάζεται να κινείται εντός του παραθύρου της φορητής συσκευής ώστε να βρει το περιεχόμενο που τον ενδιαφέρει και την κατάλληλη θέση του παραθύρου ώστε να είναι εφικτή η ανάγνωση του. Αυτή η κουραστική και χρονοβόρα διαδικασία καθιστά δύσχρηστη την πλοήγηση στον Παγκόσμιο Ιστό μέσω των φορητών συσκευών. Με άλλα λόγια, το μείζον πρόβλημα που προκύπτει είναι πως μπορούμε να απεικονίσουμε ποιοτικά το περιεχόμενο των εφαρμογών Παγκοσμίου Ιστού, που έχουν σχεδιαστεί αποκλειστικά για επιτραπέζιους υπολογιστές, σε φορητές συσκευές. Επομένως, κρίνεται απαραίτητη η χρήση τεχνικών για φιλική προς τον χρήστη απεικόνιση του περιεχομένου των εφαρμογών Παγκοσμίου Ιστού στις φορητές συσκευές. Στο πλαίσιο αυτού του προβλήματος, η ερευνητική κοινότητα αλλά και μερικές ιδιωτικές εταιρίες έχουν προτείνει αρκετές λύσεις για την αντιμετώπισή του δίχως όμως να μπορούν να εφαρμοστούν καθολικά. Στην συγκεκριμένη διπλωματική εργασία, εξετάζουμε λύσεις που βασίζονται στην μοντελοποίηση Web εφαρμογών έτσι ώστε να βελτιώσουμε την απεικόνισή του περιεχομένου τους στις φορητές συσκευές. Στόχος μας είναι η δημιουργία ενός αυτοματοποιημένου εργαλείου το οποίο θα προσαρμόζει το μοντέλο μίας εφαρμογής, η οποία έχει σχεδιαστεί αποκλειστικά για επιτραπέζιους υπολογιστές, ώστε το περιεχόμενό της να προβάλλεται με τον καλύτερο δυνατό τρόπο σε φορητές συσκευές. Για την επίτευξη αυτή της τεχνικής μελετώνται τεχνικές αντίστροφης μηχανίκευσης και προτείνονται μετασχηματισμοί του WebML μοντέλου για απεικόνιση του περιεχομένου εφαρμογών σε φορητές συσκευές. / In recent years, we have experienced the explosive growth of mobile devices which provide on users access capability to the Web. Thus, they provide navigation capability to various Web applications on users. However, it is fact that most Web applications have been designed and developed to display efficiently their content mostly on desktop computers. Considering that the mobile devices dispose limited screen size and resolution in terms of the desktop computers, the user is needed to scroll manually inside the window of the mobile device to find the content that interests him/her and the appropriate position of the window so that viewing the web application content is feasible. This tedious and time-consuming process make it difficult to use the mobile Web access of the mobile devices. In other words, the fundamental problem that arises is how we could display efficiently the Web applications' content designed for desktop computers to mobile devices. Hence, it is necessary the usage of methods for more user-friendly representation of Web applications' content on mobile devices. In this issue, the scientific community and many companies has proposed a lot of solutions in order to face this problem. However, none of these solutions can be applied universally. In this thesis, we examine solutions that are based on the modeling of Web application in order to be improved their representation on mobile devices. Generally, our intention is to develop an automated tool that will adapt the model of a Web application that has been designed for desktop computers exclusively, in order to be displayed with the best possible way on mobile devices. To achieve our solution, we study reverse engineering techniques and propose a set of transformations on the WebML model of every Web application.

Made available in DSpace on 2015-04-16T14:48:52Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1899134 bytes, checksum: af6c3f15332bd5027a7f28d2e52bc081 (MD5) Previous issue date: 2012-04-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Discussions between the theme of blood donation and social marketing are relevant as they contribute to the planning of public agencies and health institutions, in view of the inefficiency of recruitment and retention of donors processes that portrays the absence of understanding of behavioural aspects that influence individuals to adopt such conduct. Thus, the aim of this dissertation consists to understand the factors that influence the individuals to donate blood. Upon the presentation of the theoretical reference, a structural model was elaborated based on the relations between the models of blood donation, which is based on fifteen main hypotheses. The strategy used in this research was the data collection with the data analysis under a quantitative approach, using the application of structural equation modeling technique. The sample was of 346 people 100 students, 94 people in João Pessoa s city downtown, and 150 people from the internet. In general, two hypotheses were accepted, that deals with the influence of fear and reference group in predisposition of the individuals to donate blood. This suggests the necessity that the actions of social marketing to blood donation have to be focused on understanding the process of interaction between these constructs, turning the advertisement campaigns more elaborated to catch and retain blood donators. / As discussões entre a temática da doação de sangue e o marketing social mostram-se relevantes, à medida que contribuem para a o planejamento das ações de órgãos públicos e instituições de saúde, tendo em vista a ineficiência dos processos de recrutamento e retenção de doadores retratarem a ausência de compreensão dos aspectos comportamentais que influenciam os indivíduos a adotar tal conduta. Desse modo, o objetivo geral deste trabalho consiste em compreender os fatores que influenciam os indivíduos a doarem sangue. Mediante a apresentação do referencial teórico, um modelo estrutural foi elaborado com base nas relações entre os modelos de doação de sangue, o qual se constitui de quinze hipóteses centrais. A estratégia de pesquisa utilizada foi o levantamento, com a análise dos resultados adotando uma abordagem quantitativa, com a aplicação da técnica de modelagem de equações estruturais. A amostra da pesquisa foi de 346 respondentes, sendo 100 estudantes, 94 respondentes das ruas centrais de João Pessoa, e, 150 participantes via internet. De maneira geral, foram aceitas duas hipóteses, que tratam da influência do medo e do grupo de referência na predisposição dos sujeitos em doar sangue. Isto sugere a necessidade de que as ações de marketing social para a doação de sangue devem estar focadas em compreender o processo de interação entre estes construtos, tornando mais efetiva as campanhas elaboradas para captação e retenção dos doadores de sangue.

In recent years, the use of first-principles based atomistic modeling technique has become extremely popular to gain better insights on the various locally modulated electronic properties of nano materials and structures. Atomistic modeling offers the benefit of predicting crystal structures, visualizing orbital distribution and electron density, as well as understanding material properties which are hard to access experimentally. The single layer MoS2 has emerged as a suitable choice for the next generation nano devices, owing to its distinctive electrical, optical and mechanical properties like, better electrostatics, increased photo luminescence, higher mechanical flexibility, etc. The realization of decananometer scale digital switches with the single layer MoS2 as the channel may provide many significant advantages such as, high On/Off current ratio, excellent electrostatic control of the gate, low leakage, etc. However, there are quite a few critical issues such as, forming low resistance source/drain contacts, achieving higher effective mobility, ensuring large scale controlled growth, etc. which need to be addressed for successful implementation of the atomically thin transistors in integrated circuits. Recent experimental demonstration showing the coexistence of metallic and semiconducting phases in the same monolayer MoS2, has attracted much attention for its use in ultra-low contact resistance-MoS2 transistors. Howbeit, the electronic structures of the metallic-to-semiconducting phase boundaries, which appear to dictate the carrier injection in such transistors, are not yet well understood. In this work, we first develop the geometrically optimized atomistic models of the 2H-1T′ hetero-phase structures with two distinct phase boundaries, β and γ. We then apply density functional theory to calculate the electronic structures for those optimized geometries. Furthermore, we employ non equilibrium Green’s function formalism to evaluate the transmission spectra and the local density of states in order to assess the Schottky barrier nature of the phase boundaries. Nonetheless, the symmetry of the source-channel and drain-channel junction, is a unique property of a metal-oxide semiconductor field effect transistor (MOSFET), which needs to be preserved while realizing sub-10 nm channel length devices using advanced technology. Employing experimental-findings-driven atomistic modeling technique, we demonstrate that such symmetry might not be preserved in an atomically thin phase-engineered MoS2- based MOSFET. It originates from the two distinct atomic patterns at phase boundaries (β and β*) when the semiconducting phase (channel) is sandwiched between the two metallic phases (source and drain). Next, using first principles based quantum transport calculations we demonstrate that due to the clusterization of “Mo” atoms in 1T′ MoS2, the transmission along the zigzag direction is significantly higher than that in the armchair direction. Moreover, to achieve excellent impedance matching with various metal contacts (such as, “Au”, “Pd”, etc.), we further develop the atomistic models of metal-1T′ MoS2 edge contact geometries and compute their resistance values. Other than the charge carrier transport, analysing the heat transport across the channel is also crucial in designing the ultra-thin next generation transistors. Hence, in this thesis work, we have investigated the electro-thermal transport properties of single layer MoS2, in quasi ballistic regime. Besides the perfect monolayer in its pristine form, we have also considered various line defects which have been experimentally observed in mechanically exfoliated MoS2 samples. Furthermore, a comprehensive study on the phonon thermal conductivity of a suspended monolayer MoS2, has been incorporated in this thesis. The studies presented in this thesis could be useful for understanding the carrier transport in atomically thin devices and designing the ultra-thin next generation transistors.