Time integration methods are necessary for the solution of transient flow problems. In recent years, interest in transient flow problems has increased, leading to a need for better understanding of the costs and benefits of various time integration schemes. The present work investigates two common time integration schemes, namely the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) and the Fractional Step (FS) method. Three two-dimensional, transient, incompressible flow problems are solved using a cell centered, finite volume code. The three test cases are laminar flow in a lid-driven skewed cavity, laminar flow over a square cylinder, and turbulent flow over a square cylinder. Turbulence is modeled using wall functions and the k - ε turbulence model with the modifications suggested by Kato and Launder. Solution efficiency as measured by the effort carried out by the flow equation solver and CPU time is examined. Accuracy of the results, generated using the SIMPLE and FS time integration schemes, is analyzed through a comparison of the results with existing experimental and/or numerical solutions. Both the SIMPLE and FS algorithms are shown to be capable of solving benchmark flow problems with reasonable accuracy. The two schemes differ slightly in their prediction of flow evolution over time, especially when simulating very slowly changing flows. As the time step size decreases, the SIMPLE algorithm computational cost (CPU time) per time step remains approximately constant, while the FS method experiences a reduction in cost per time step. Also, the SIMPLE algorithm is numerically stable for time steps approaching infinity, while the FS scheme suffers from numerical instability if the time step size is too large. As a result, the SIMPLE algorithm is recommended to be used for transient simulations with large time steps or steady state problems while the FS scheme is better suited for small time step solutions, although both time-stepping schemes are found to be most efficient when their time steps are at their maximum stable value.

We apply the Segal process of group simplification to the linear harmonic oscillator. The result is a finite quantum theory with three quantum constants instead of the usual one. We compare the classical (CLHO), quantum (QLHO), and finite (FLHO) linear harmonic oscillators and their canonical or unitary groups. The FLHO is isomorphic to a dipole rotator with N=l(l+1) states where l is very large for physically interesting case. The position and momentum variables are quantized with uniform finite spectra. For fixed quantum constants and large N there are three broad classes of FLHO: soft, medium, and hard corresponding respectively to cases where ratio of the of potential energy to kinetic energy in the Hamiltonian is very small, almost equal to one, or very large The field oscillators responsible for infra-red and ultraviolet divergences are soft and hard respectively. Medium oscillators approximate the QLHO. Their low-lying states have nearly the same zero-point energy and level spacing as the QLHO, and nearly obeying the Heisenberg uncertainty principle and the equipartition principle. The corresponding rotators are nearly polarized along the z-axis. The soft and hard FLHO's have infinitesimal 0-point energy and grossly violate equipartition and the Heisenberg uncertainty principle. They do not resemble the QLHO at all. Their low-lying energy states correspond to rotators polaroizd along x-axis or y-axis respectively. Soft oscillators have frozen momentum, because their maximum potential energy is too small to produce one quantum of momentum. Hard oscillators have frozen position, because their maximum kinetic energy is too small to produce one quantum of momentum. Hard oscillators have frozen position, because their maximum kinetic energy is too small to excite one quantum of position.

In the thesis, we apply the gene expression programming (GEP) to training profitable trading strategies. We propose a model which utilizes several historical periods that are highly related to the current template period, and the best trading strategies of the historical periods generate the trading signals. To keep stability of our model, we proposed the trading decision mechanism based on simple majority vote in our model. The Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX) is selected as our investment target and the trading period starts from 2000/9/14 to 2012/1/17, approximately twelve years. In our experiments, the lengths of our training period are 60, 90, 120, 180, and 270 trading days, respectively. We observe that the model with higher voting threshold usually can make profitable trading decisions. The best cumulative return 236.25\% and the best annualized cumulative return 10.63\% occur when the 180-day training models pairs with available threshold 0.21 and voting threshold 0.88, which are higher than the cumulative return 0.96\% and annualized cumulative return 0.08\% of the buy-and-hold strategy.

The main purpose of this research is to develop a Computational Fluid Dynamics (CFD) software to be used as an educational tool in teaching introductory level fluid mechanics and CFD courses. The software developed for this purpose is called Virtual Flow Lab. It has a graphical user interface (GUI) that enables basic pre-processing, solver parameter and boundary condition setting and post-processing steps of a typical CFD simulation. The pressure-based solver is capable of solving incompressible, laminar, steady or time-dependent problems on two-dimensional Cartesian grids using the SIMPLE algorithm and its variants. Blocked-cell technique is implemented to extend the types of the problems that can be studied on a Cartesian grid. A parametric study is conducted using a number of benchmark problems in order to test the accuracy and efficiency of the solver and successful results are achieved.

Crime is a behavior disorder that is an integrated result of social, economical and environmental factors. In the world today crime analysis is gaining significance and one of the most popular subject is crime prediction. Stakeholders of crime intend to forecast the place, time, number of crimes and crime types to get precautions. With respect to these intentions, in this thesis a spatio-temporal crime prediction model is generated by using time series forecasting with simple spatial disaggregation approach in Geographical Information Systems (GIS). The model is generated by utilizing crime data for the year 2003 in Bah&ccedil / elievler and Merkez &Ccedil / ankaya police precincts. Methodology starts with obtaining clusters with different clustering algorithms. Then clustering methods are compared in terms of land-use and representation to select the most appropriate clustering algorithms. Later crime data is divided into daily apoch, to observe spatio-temporal distribution of crime. In order to predict crime in time dimension a time series model (ARIMA) is fitted for each week day, Then the forecasted crime occurrences in time are disagregated according to spatial crime cluster patterns. Hence the model proposed in this thesis can give crime prediction in both space and time to help police departments in tactical and planning operations.

The aim of this study is to develop a two-dimensional pressure-based Navier-Stokes solver for incompressible/compressible flows. Main variables are Cartesian velocity components, pressure and temperature while density is linked to pressure via equation of state. Modified SIMPLE algorithm is used to achieve pressure-velocity coupling. Finite Volume discretisation is performed on non-orthogonal and boundary-fitted grids. Collocated variable arrangement is preferred because of its advantage on staggered arrangement in non-orthogonal meshes. Face velocities are calculated using Rhie-Chow momentum interpolation scheme to avoid pressure checkerboarding effect. The solver is validated by solving a number of benchmark problems.

Hoy en día, la utilización de redes de comunicaciones heterogéneas se ha vuelto en un desafío constante, debido a sus complejidades y crecimiento acelerado, tornándose en un factor crítico de sucesos en muchas organizaciones. Durante la última década, diversas arquitecturas de gestión de red han sido desarrolladas y estandarizadas permitiendo el control y monitorización de los diversos indicadores de redes de telecomunicaciones tales como: la utilización de la interfaz, tasa de error, rendimiento y el retardo extremo a extremo, afectando de manera sustancial la calidad de operación de toda red, percibida directamente (p.e en el servicio VoIP) o indirectamente (p.e. capacidad de transferencia de los protocolos de transporte) por los usuarios finales. Todo esto basados en la interconexión de redes de distintas tecnologías, operadas por distintos proveedores y con el paradigma de servicio best-effort. En telecomunicaciones, el término “Calidad de Servicio” o QoS, hace referencia precisamente a las técnicas y procedimientos utilizados para dar un tratamiento preferente a unas clases de tráfico o flujos frente a otras, con el objetivo de cumplir unos requisitos mínimos de performance, identificados por parámetros cuantitativos que deben ser respetados estrictamente para que se logre percibir una adecuada calidad subjetiva por parte de los usuarios, particularmente en las comunicaciones multimediales, lo que da lugar al término “Calidad de Experiencia” o QoE como una nueva forma de valoración de la calidad final ofrecida por las empresas proveedoras de servicio. Con estos antecedentes, la presente investigación explica una nueva forma de calcular estos parámetros, usando un prototipo de aplicación de gestión, de modo que sobre la base de estas mediciones, puedan hacerse los ajustes necesarios dentro de la red y los administradores puedan identificar congestión o potenciales eventos indeseables en la red. De acuerdo a investigaciones bien documentadas sobre este tema, en donde la gestión llegar a ser un factor importante, el paradigma tradicional de arquitectura centralizada es particularmente ineficiente durante periodos de alta congestión, debido al incremento de las interacciones entre la estación central y los dispositivos gestionados. De esta manera, esta investigación pretende suplir en determinada medida esta deficiencia, proponiendo un sistema de gestión de red, basado en agente móviles denominado “AgenteMobilSNMP – AMSNMP” aplicado dentro de un entorno distribuido para llevar a cabo el proceso de gestión y la recolección de los resultados. / Nowadays, the use of heterogeneous communications networks has become a constant challenger because of its complexities and accelerated growth, becoming a critical factor in many organizations. During the last decade, many network management architectures have been developed and standardized allowing the control and monitoring of several telecommunications networks indicators such as: the use of the interface, error rate, throughput, and the end-to-end delay, significantly affecting the quality of operation of the whole network, which is perceived directly (e.g. in VoIP service) or indirectly (e.g. transference capacity of the transport protocols) by the end users. All this made through the interconnection of networks of different technologies, operated by different suppliers and generally with the “best-effort” service paradigm. In telecommunications, the term “Quality of Service” or QoS, especially refers to techniques and procedures used to give preferential treatment to some class or traffic flows, over others, to meet minimum standards requirements of performance, identified by quantitative parameters, that must be strictly respected such that a suitable subjective quality is perceived by users, particularly in multimedia communications, where the term “Quality of Experience” or QoE as a new way of valuing the final quality offered by the companies service providers. With this background, the present document explains a new way to calculate these parameters, using a prototype management application so that on the basis of these measurements, adjustments can be made in the network and the administrators can be able to identify congestion trends and potentials undesirable events for the operation of the network. According to well documented researches on this subject, the centralized paradigm used by the traditional SNMP management architecture, among other aspects, where the central station (or management console) obtains the results of each managed station, one at a time, it is too restricted, because the amount of traffic up to this architecture cause, account to its, a proposing management system based on mobile agents called “AgenteMobilSNMP – AMSNMP, applied within a distributed environment, where the agent is transported throughout all the entities to manage in order to carry out the process management and data collection.

<p>This work aims at enhancing the understanding and to provideimproved models of the dynamic behavior of rubber vibrationisolators which are widely used in mechanical systems.Initially, a time domainmodel relating compressions tocomponent forces accounting for preload effects, frequency anddynamic amplitude dependence is presented. The problem ofsimultaneously modelling the elastic, viscoelastic and frictionforces are removed by additively splitting them, where theelastic force response is modelled either by a fully linear ora nonlinear shape factor based approach, displaying resultsthat agree with those of a neo-Hookean hyperelastic isolatorunder a long term precompression. The viscoelastic force ismodelled by a fractional derivative element, while the frictionforce governs from a generalized friction element displaying asmoothed Coulomb force. This is a versatile one-dimensionalcomponent model effectively using a small number of parameterswhile exhibiting a good resemblance to measured isolatorcharacteristics. Additionally, the nonlinear excitationeffects on dynamic stiffness and damping of a filled rubberisolator are investigated through measurements. It is shownthat the well-known Payne effect - where stiffness is high forsmall excitation amplitudes and low for large amplitudes whiledamping displays a maximum at intermediate amplitudes -evaluated at a certain frequency, is to a large extentinfluenced by the existence of additional frequency componentsin the signal. Finally, a frequency, temperature and preloaddependent dynamic stiffness model is presented covering theranges from 20 to 20 000 Hz, -50 to +50 °C at 0 to 20 %precompression. A nearly incompressible, thermo-rheologicallysimple material model is adopted displaying viscoelasticitythrough a time - strain separable relaxation tensor with asingle Mittag-Leffler function embodying its time dependence.This fractional derivative based function successfully fitsmaterial properties throughout the whole audible frequencyrange. An extended neo-Hookean strain energy function, beingdirectly proportional to the temperature and density, isapplied for the finite deformation response with componentproperties solved by a nonlinear finite element procedure. Thepresented work is thus believed to enlighten workingconditions’impact on the dynamic properties of rubbervibration isolators, while additionally taking some of thesemost important features into account in the presentedmodels.</p>

<p>  Sound transmission loss of vehicle seals was studied in this thesis. Reverberation room test and semi-anechoic chamber test were respectively studied. By comparing the sound pressure level, sound intensity level and average sound power level at the receiving side, it proved that a simple sound pressure level test may obtain same measurement accuracy when there is little reflected sound. A semi-anechoic chamber was designed for testing sound transmission losses of the seals on a trial vehicle. By comparing the sound pressure levels between the location of the passenger ear and door area, it proved that most of outside sound energy passed through the door seals into the interior. The sound transmission losses of different sealing conditions were measured which included well sealed and imperfectly sealed conditions; Sound pressure levels at passenger’s ear in three different types of vehicles were also compared, these comparison results indicated this laboratory was capable of distinguishing different sealing conditions. The installation procedure was compared with the one in reverberation room test. Numerical analysis showed that the latter method produced a different compression shape which would definitely influence the sound insulation abilities of the seals.</p><p>  The transmission mechanism of the acoustic waves through a vehicle seal was also discussed. Contact analysis showed high compression ratio leaded to tremendous inner stress intensity. But any further increase of the contact depth would not improve the effect of wind noise prevention. A vehicle seal with a complex shape was replaced by a simple model. The sound transmission theory of multiple partitions on the basis of mass law was applied. Whereas, compared with the experimental result, a different trend in the high frequency range was found. When taking the transmission though the side material and integration of incident angle into account, the result was quite similar to the experimental one. FEM analysis was also performed. The majority of sound power was believed to transmit along the seal wall into the interior instead of passing through the multiple partitions. A distorted circular duct model is believed to be close to the real geometry.</p><p> </p>

Le comportement spécifique des Alliages à Mémoire de Forme (AMF) est dû à une transformation de phase appelée transformation martensitique. Cette transformation de phase peut être activée par des variations de température mais aussi par des chargements mécaniques. Si le comportement 1D de ces alliages est bien connu, la modélisation du comportement de ces alliages sous sollicitations multiaxiales complexes pose encore quelques problèmes.<br />Dans un premier temps, nous nous intéressons à la validation expérimentale directe d'une relation entre la fraction volumique de martensite et la déformation de transformation qui est utilisée dans de nombreux modèles. Pour cela des essais en traction-compression-torsion avec suivi de résistance électrique sur un AMF de type Cu-Al-Be sont réalisés. Ces essais mettent en évidence les effets de la texture de ces alliages sur leur comportement.<br />Par ailleurs, des simulations numériques de type micro-macro sont réalisées, pour différentes textures et pour différents trajets multiaxiaux proportionnels. Ces simulations complètent, d'une part, la base de données expérimentale, et permettent, d'autre part, de valider les hypothèses retenues pour la modélisation.<br />Enfin, des essais anisothermes de traction compression torsion proportionnels et non proportionnels sont réalisés sur un AMF de type Ni-Ti. Une surface de début de réorientation de phase R est ainsi mise en évidence.