nÃo hà / Desde o inÃcio do Plano Real, em julho de 1994, a razÃo DÃvida LÃquida do Setor PÃblico sobre o Produto Interno Bruto teve expansÃo vertiginosa ao sair de um patamar de cerca de 30%, no inÃcio do perÃodo, para montante superior a 57% no final de 2002, quando, a partir de entÃo, retomou trajetÃria decrescente. Hà de se salientar que no perÃodo entre 1994 2002 o paÃs atravessou algumas crises tanto no ambiente interno quanto externo o que contribuiu para o agravamento desta variÃvel. O objetivo deste trabalho à analisar o comportamento desta relaÃÃo, considerada um dos principais indicadores de solvÃncia intertemporal de um paÃs. Para tanto, este estudo està dividido em trÃs sub-anÃlises diferentes. A primeira visa à modelagem da dÃvida por meio da metodologia dos mÃnimos quadrados ordinÃrios. A anÃlise seguinte à voltada para a demonstraÃÃo do mecanismo de contÃgio da dÃvida pÃblica sob a visÃo de vetores autoregressivos. E, na Ãltima, desenvolve-se um modelo de dinÃmica da dÃvida por meio de equaÃÃes diferenciais de onde se obtÃm, ainda, a condiÃÃo de solvÃncia de um paÃs. A partir disto, vÃrios exercÃcios de trajetÃria desta variÃvel sÃo realizados. Para a amostra disponÃvel, e considerando as trÃs diferentes anÃlises, os resultados corroboram a teoria apresentada. Desta forma, evidencia-se que o estudo do comportamento da dÃvida pÃblica torna-se indispensÃvel para o melhor entendimento de algumas polÃticas econÃmicas utilizadas atà entÃo no Brasil. / Since the beginning of the Real Plan, in July 1994, the ratio Public Debt/GDP had a vertiginous increase going from a level around 30% in the begin of the period to an amount above 57% at the end of 2002. From this moment onwards the ratio restarted a new decreasing path. During this period, Brazil has gone through some crisis in the internal field as well as in the external one which contributed to the aggravation of this relation. The goal of this work is to analyze the behavior of this relationship, which is considered one of the most important indices of a country’s solvency during a period of time. So, this research is divided into three different sub-analyses. The first aims to model the debt in the short term through the methodology of the minimum ordinary squares. The following analysis demonstrates the mechanism of infection of the public debt under the vision of vector autoregressions. And in the last one a model of debt dynamic is developed using difference equations from which the condition of solvency of a country can be obtained. From this point, several exercises of this variable path are tested. For the available sample and considering the three different analysis, the outcomes corroborate the presented theory. In such case, it is clear that the behavior’s study of the public debt is essential for a better understanding of some economic policies applied so far in Brazil.

Dynamic model driven architecture (DMDA) is a architecture made to aid in the development of parallel computing code. This thesis is applied to an implementation of DMDA known as DMDA3 that should convert graphs of computations into efficient computation code, and it deals with the translation of Platform Specific Models (PSM) into running systems. Currently DMDA3 can generate schedules of operations but not finished code. This thesis describes a DMDA3 module that turns a schedule of operations into a runable program. Code was obtained from the DMDA3 schedules by reflection and a framework was build that allowed generation of low level language code from schedules. The module is written in Java and can currently generate C and Fortran code for computational tasks. Based on runtime tests for matrix multiplication algorithms the generated code is almost as fast as handwritten code.

In industrial fuel gas preparation, there are several compositional properties that must be controlled within specified limits. This allows client plants to use the fuel gas mixture safely without having to adjust and control the composition themselves. The variables to be controlled are the Higher Heating Value (HHV), Wobbe Index (WI), Flame Speed Index (FSI), and Pressure (P). These variables are controlled by adjusting the volumetric flow rates of several inlet gas streams of which some are makeup streams (always available) and some are wild streams that vary in composition and availability (by-products of plants). The inlet streams need to be adjusted in the correct ratios to keep all the controlled variables (CVs) within limits while minimising the cost of the gas blend. Furthermore, the controller needs to compensate for fluctuations in inlet stream compositions and total fuel gas demand (the total discharge from the header). This dissertation describes the modelling and model validation of an industrial fuel gas header as well as a simulation study of three different Model Predictive Control (MPC) strategies for controlling the system while minimising the overall operating cost. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

The objective of this thesis is to present the basics of production scheduling problems for workstations and to create an application of dynamic model. This application should help the UNIKOV company to produce similar schedules for their own operations. The theoretical part provides a brief description of terms and characteristics of the scheduling problems. Detailed characteristics are provided on the open shop problem - the task applied on the real world example. The paper then follows with a practical part, covering an explanation of the heuristics model written in VBA for MS Excel, allowing dynamic expansion and management of the production.

Different scenarios of the financial situation can take place before the company's bankruptcy. There may be long-term trends in the deteriorating financial situation that indicate the impending corporate bankruptcy, or the bankruptcy may occur unexpectedly, even though the company was ranked among prosperous business units. If the economic situation of the company followed the second scenario, when insolvency was quite predictable, static model, i.e. the model which does not take into account the dynamics of changes in the financial indicators, is a good option to capture the probability of bankruptcy. However, the situation becomes different when the financial indicators fail to show a positive trend throughout some years before the insolvency. In this case, the predictive accuracy of the static model could be increased by a dynamic model by taking into account the fact that the development of the financial indicators in the past periods may affect the company's financial health for the period under consideration.

The influent to a water and resource recovery facility (WRRF) generally exhibits significant diurnal variations in flow rate and load concentration. This makes determining the operating parameters and subsequently the overall operation of plants difficult, especially in developing countries due to the lack of highly skilled operators. Hence, there is an incentive for the control and operation of WRRFs in developing countries to be improved. Flow equalization tanks were identified as a potential method to attenuate the diurnal variations in flow rate and load concentration into plants. The main aim of this research was to develop a viable dynamic simulation model for the operation of flow equalization tanks, within a plant-wide framework (to allow for the evaluation of design and control strategies). The next aim was to determine the benefits of equalization tanks towards design and optimised operation of future WRRFs via scenario analyses. Finally, the effects of the equalization tank on the performance of various unit processes in a WRRF were to be investigated. The model was developed in three steps; i) the development of the required equations to model equalization tanks, ii) mass balance throughout the model for internal consistency and iii) scenario analyses to determine if the model generated reasonable and scientifically sound outputs. The model was developed using Microsoft Excel Visual Basic (VBA) and WEST®. Two scenarios were considered to assess the equalization tank modelled. Scenario One involved the comparison of the capital cost, unit process sizes and total footprint of a balanced sludge age Modified Ludzack-Ettinger (MLE) system with and without an equalization tank. Scenario Two compared the plant performance of the MLE system designed in Scenario One with and without a flow equalization tank. A dynamic simulation model replicating equalization tanks was successfully developed. From scenario analyses, it was determined that using an MLE system and only considering equalization of flow, there was a reduction in the size of several unit processes by 8-9% (primary settling tank, biological reactors, secondary settling tank, flotation unit, anoxic-aerobic digester), due to the less conservative design values that could be used as the variations of the influent were decreased. Despite this, a 13% overall increase in the footprint of the WRRF was observed due to the addition of the equalization tank. The attenuation of diurnal flow variations also resulted in reduction of various plant parameters by up to 50% (flow, OUR, VSS flux). Finally, there was a 10% improvement in the performance of various unit processes due to the presence of the equalization tank. In conclusion, the inclusion of equalization tanks in WRRFs has significant positive effects. These results were obtained with equalization of flow only. Some other limitations were experienced during the project resulting in the following recommendations: further research will be needed to validate and calibrate the model, As the model was not successfully incorporated in a plant-wide framework, further developments in that direction are required, as well as including the equalization of load in the model.

This Master thesis is focused on electromagnetic brakes for servomotors. In the first chapter is described principle of operation, later then design and main parameters are explained. The main part of thesis is focused on calculation of dynamic parameters of electromagnetic brakes. Calculations are solved first by analytic method in Matlab–Simulink, then by finite element analysis. Results are compared with measurements on prototype brake.

Diplomová práce se zabývá studiem signální dráhy produkce butanolu bakterií rodu Clostridium. V první části pojednává o modelování signálních drah pomocí metod systémové biologie. Navazuje popisem zisku dat pro tvorbu a úpravu modelů signálních drah s hlavním zaměřením na techniky pro zjištění genové exprese, produkce a fenotypu. Třetí sekcí je získání základního modelu signální dráhy zapojené do produkce butanolu u solventogenních klostridií. Posledním bodem a zároveň hlavním cílem je vytvoření dynamického modelu signální dráhy produkce butanolu kmene Clostridium beijerinckii NRRL B-598, jeho vyhodnocení pomocí statické a dynamické analýzy a srovnání s biologickými daty.

Metapolybia wasps construct their nests on flat surfaces using plant materials, which they process into paper. For processing the pulp wasps need water, which is collected by water foragers, and it is transferred to pulp foragers indirectly via a "common stomach." The common stomach is formed by generalist wasps that can engage in water exchange and can store water in their crops. Our goal is to provide an alternative model for regulating task partitioning in construction behavior, focusing on worker connectivity instead of using threshold curves to model mechanisms of colony-level regulation. We propose that the existence of an information center and of a network of worker interactions, which establish sets of positive and negative feedbacks, allow collective regulation of colony-wide behaviors. Using a Stock and Flow modeling framework, we illustrate that the common stomach could serve both as a temporal storage for water and also as a source of information about the colony's current demands related to nest construction tasks. Our model predicts that assessing colony needs via individual interactions with the common stomach leads to a robust regulation of task partitioning in construction behavior. Using perturbation experiments in our simulations, we show that this emergent task allocation is able to dynamically adapt to perturbations of the environment and to changes in colony-level demands or population structure. Our model closely mimics and predicts the behavior of Metapolybia wasps, demonstrating that the regulation mechanism based on worker connectivity through a common stomach is a plausible hypothesis for the organization of collective behavior.

The dissertation deals with designing of model for support of strategic management of e-business which is characteristic by integrating existing management processes in the company. The basic mathematical model uses the solution of differential equations and is adaptable for the needs of particular entity.