Physics engines become more and more common due to the rapid development and increasing demand of simulations. With this comes a need of testing the engine, a way to measure its performance, not only its speed but also its accuracy and stability. The purpose of this thesis has been to create a set of benchmark tests. They aim to check the physical aspects, especially mechanics, of the engine. A strategy and export functions for the test results in order to automate the testing have also been developed. The resulting tests became a beam on piles which analyses constraint stability, an overdetermined system consisting of a static door on multiple hinges, a falling object investigating the accuracy of the integrator, a box on an inclined plane for testing the friction model, a single pendulum as well as a multibody pendulum checking constraint accuracy and energy conservation, the Earth orbiting around the Sun which tests the stability of the integrator and finally a cantilever beam that is a static test of a real scenario. After the tests are performed the results are presented on an HTML-page. A prototype of a Web application is also established as well as a set of scalar tests that can be performed continuously, in order to follow trends or compare the engine's performance from time to time. This thesis was initialized by Algoryx Simulation AB which also provided the engine, AgX Dynamics, with the numerical method called SPOOK. It mainly performed well on all tests. In order to build a fully general toolbox more tests need to be added such as material interactions, scalable test with thousands of bodies, torque tests as well as more complex scenarios, for example a scissor lift and robots. The work can also be extended with more developed export functions, both to the Web and to documents. Hopefully this thesis can be seen as a complement to the earlier efforts done in creating a general set of benchmarks and automation framework for continuous integration and testing. / Fysikmotorer blir mer och mer vanliga på grund av den snabba utvecklingen och efterfrågan på simuleringar. I och med detta ökar också behovet av att testa motorerna och ett sätt att mäta prestandan, inte bara snabbheten utan också noggrannheten och stabiliteten. Syftet med detta examensarbete har varit att skapa ett set av prestandatester. De syftar till att testa de fysikaliska aspekterna av fysikmotorn, särskilt inom mekanik. En strategi och exportfunktioner för testresultaten för att automatisera testningen har också utvecklats. De resulterande testerna blev en balk på pålar som analyserar stabiliteten hos villkoren, ett överbestämt system bestående av en statisk dörr på flera gångjärn, ett fallande objekt som granskar precisionen hos integratorn, en låda på ett lutande plan som testar friktionsmodellen, en enkel pendel samt en flerkropppspendel som kontrollerar villkorsprecisionen och energikonservering, jordens bana runt solen som testar integratorns stabilitet och slutligen en utskjutande balk som är ett statiskt test av ett verkligt fall. När testerna är genomförda presenteras resultaten på en HTML-sida. En prototyp av en webb-applikation har också utvecklats samt ett set med skalära tester som kan utföras kontinuerligt för att följa upp trender och jämföra motorns prestanda över tid. Det här examensarbetet initierades av Algoryx Simulation AB som även tillhandahållit fysikmotorn, AgX Dynamics, med den numeriska metoden SPOOK. Motorn presterade överlag bra på testerna. För att bygga en allmän verktygslåda behövs fler tester så som interaktion mellan material, skalbara tester med tusentals kroppar samt mer komplexa simuleringar, t.ex. en saxlyft och robotar. Arbetet kan också utökas med mer utvecklade exportfunktioner, både mot webben och som dokument. Förhoppningsvis kan detta ses som ett komplement till de tidigare ansträgningar som gjorts för att skapa ett generellt set av prestandatester och ett automatiskt ramverk för kontinuerlig testning.

Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading have been analyzed. Elastic moduli and thermal coefficient of expansion are calculated and their variation with diameter and length is investigated. In particular, the nanotubes are modeled using 3D elastic beam finite elements with six degrees of freedom at each node. The difficulty in modeling multi walled nanotubes is the van der Waal's forces between adjacent layers which are geometrically non linear in nature. These forces are modeled using truss elements. The nanotube-polymer interface in a nano-composite is modeled on a similar basis. While performing the molecular dynamic simulations, the geometric optimization is performed initially to obtain the minimized configuration and then the desired temperature is attained by rescaling the velocities of carbon atoms in the nanotube. Results show that the Young's modulus increases with tube diameter in molecular mechanics whereas decreases in molecular dynamics since the inter-atomic potential due to chemical reactions between the atoms is taken into consideration in molecular dynamics unlike in molecular mechanics.

Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading have been analyzed. Elastic moduli and thermal coefficient of expansion are calculated and their variation with diameter and length is investigated. In particular, the nanotubes are modeled using 3D elastic beam finite elements with six degrees of freedom at each node. The difficulty in modeling multi walled nanotubes is the van der Waal's forces between adjacent layers which are geometrically non linear in nature. These forces are modeled using truss elements. The nanotube-polymer interface in a nano-composite is modeled on a similar basis. While performing the molecular dynamic simulations, the geometric optimization is performed initially to obtain the minimized configuration and then the desired temperature is attained by rescaling the velocities of carbon atoms in the nanotube. Results show that the Young's modulus increases with tube diameter in molecular mechanics whereas decreases in molecular dynamics since the inter-atomic potential due to chemical reactions between the atoms is taken into consideration in molecular dynamics unlike in molecular mechanics.

In dieser Arbeit werden unter der Nutzung von Simulationswerkzeugen und neu erstellten instationären Modellen von Kraftwerkskomponenten auf dem Sektor der Energieerzeugung mit fossilen Brennstoffen am Beispiel von Kohle, Betriebs- und Verhaltensweisen der Anlage untersucht und Optimierungsmöglichkeiten für die vorgegebenen Randbedingungen getestet.

The high strength, light weight, and flexibility of fabric protection systems makes them the preferred solution for a number of ballistic applications. Examples include body armor, fan blade containment for jet engines, and orbital debris shielding. In general, these protection systems employ plain woven fabric, most suitable for flat or gently curved geometries. Highly curved surfaces, such as personnel extremities, may be more effectively protected using fabrics of different weaves. This dissertation presents the first numerical model developed to simulate ballistic impacts into plain, harness satin, twill, and basket weave fabrics. It extends previous work on hybrid particle-finite element methods developed for fabric modeling. The extended formulation closely replicates the tensile load response and contact-impact dynamics of highly flexible yarns, by generalizing the kinematic model and density interpolation used in previous work. The formulation has been validated in three dimensional simulations of impact experiments conducted to investigate the effects of weave type on fabric ballistic performance. / text

This research documents the societal worth of riparian resources in the Southwestern United States. Two case studies are developed for this inquiry, the first being Aravaipa Canyon Wilderness in Southern Arizona, an area containing one of the last perennial streams in the Sonoran Desert bioregion. A hiking use value per visitor-day is estimated via the Travel Cost Method at $25.06 and $17.31 (2003 dollars) respectively for two access sites. I hypothesize the value discrepancy to indicate a premium for remote recreation. These valuation results compare well with other published recreational use value estimates, though it is the only valuation study associated with instream recreation in the Sonoran Desert of which I am aware. Indeed the environmental valuation literature is thin for the desert region in any respect.The second case study values public restoration preferences for the Albuquerque reach of the Rio Grande in Central New Mexico. A Choice Experiment and Contingent Valuation are employed within an original survey instrument to estimate human values for various restoration strategies planned for the region. Through focus groups and stakeholder interactions four restoration attributes were defined: vegetation density; tree type; fish and wildlife population; and natural river processes. Quantified values for Albuquerque area households were estimated for each restoration attribute level of change, allowing construction of total benefits anticipated for various restoration scenarios considered for the region. This research is at the vanguard of quantifying human benefit for saltcedar control, and this particular restoration characteristic was the most highly valued of all, at $59.03 per household per year. Full restoration was valued at $156.60 per household per year. These results have meaning beyond the study area since river restoration efforts are increasing across the Western US, with many focusing on controlling saltcedar, an exotic invasive plant.The final phase of this research integrates riparian valuation concepts within a dynamic simulation framework to guide systems-level riparian management. Control variables are combined with known valuation pathways to predict riparian investment funding optimal in benefit-cost ratio. The model is built for the Middle Rio Grande in Albuquerque, however it was designed for easy adaptation to other Southwestern riparian areas. A detailed forest module is included, through which seven defined forest stocks may be managed through thinning, clearing, and revegetation. River management may occur through environmental river flow releases, reconstructing stream-overbank connections, and wetland construction. Recreational amenities may be improved through the four infrastructure categories of trails, toilet facilities, picnic areas, and parking areas. Benefits and costs are estimated through original research and region benefit transfer, and tracked for different investment scenarios to predict the highest-return strategies over a 100 year planning horizon. A sensitivity analysis is used to suggest areas of future research.

The system frequency of a synchronous power system varies with the imbalance of energy supplied and the electrical energy consumed. When large generating blocks are lost, the system undergoes a frequency swing relative to the size of the loss. Limits imposed on the magnitude of frequency deviation† prevent system collapse. Operation of frequency responsive plant to control frequency, results in lower machine efficiencies. Changes to the generation mix on the British transmission system have occurred in the past ten years, when the response requirement was last reviewed. Future increased levels of wind turbines‡ will alter the operational characteristics of the system and warrant investigation. A process to optimise the response requirements while maintaining statutory limits on frequency deviation has been identified. The method requires suitable load and generator models to replicate transmission system performance. A value to substitute for current load sensitivity to frequency has been presented from empirical studies. Traditional coal fired generator models have been improved with additional functions to provide a comparable response with existing units. A novel combined cycle gas turbine model using fundamental equations and control blocks has also been developed. A doubly fed induction generator model, based on existing literature, has been introduced for representing wind turbine behaviour in system response studies. Validation of individual models and the complete system against historic loss events has established confidence in the method. A review of the current system with the dynamic model showed that current primary response requirements are inadequate. The secondary response requirements generally show a slight reduction in the holding levels. Simulations including extra wind generation have shown that there is potential to reduce the primary response requirement in the future. The secondary response requirements are maintained with added wind farms.

Este trabalho apresenta o estudo da dinâmica de uma instalação propulsora a vapor através da técnica da modelagem e simulação. O modelo matemático é obtido das Leis da Termodinâmica e dos conceitos básicos da mecânica dos fluídos e transferência de calor, e a simulação é efetuada em um computador digital. Inicialmente cada componente do ciclo é modelado individualmente, determinando-se as suas variáveis de estado, de entrada e de saída. A seguir o modelo é simulado para analisar a influência dos diversos parâmetros nas respostas do elemento. O modelo matemático da instalação propulsora a vapor é obtido agrupando-se convenientemente os modelos dos vários componentes do ciclo. Com isso obtêm-se um sistema de 47ª ordem que pode simular diversos casos de interesse real. Neste trabalho são analisadas as respostas do ciclo para dois casos. A primeira corresponde ao fechamento parcial da válvula de controle da turbina e a segunda ao corte na vazão de óleo combustível. / This paper presents a study of the dynamics of a steam power plant using techniques of modelling and simulation. The mathematical model derives form the laws of Thermodynamics and basic concepts of fluid mechanics and heat transfer; the simulation is carried out in a digital computer. Each component is first modelled individually, and its state, input and output variables are determined. The model is then simulated for the analysis of the influence of the various parameters in the responses of the component. The mathematical model of the complete power plant is constructed by the convenient grouping of the various component models of the cycle. Thereby a 47th order system is obtained, which can simulate various cases of interest. The cycle\'s response for two cases are analysed. The first case correspond to the partial closing of the turbine control valve and the second to the fuel flow interruption .

The aim of this thesis is to analyze and optimize production processes in a company which produces plastic components for the automotive industry. The theoretical part of this thesis summarizes basic knowledge of business process simulation and addresses the reasons for making use of dynamic simulation as a tool for eliminating dissipation and supporting decision making. The main focus is an analysis of the current situation and identifies the problems in the company. For the purpose of optimization, a simulation model was created using Simul8, by the Simul8 Corporation. The model was made in accordance with the methodology described in the theoretical part of this thesis. It was used to examine the efficiency of proposed versions of the production schedule, in light of its impact on storage capacity and service level.

Dynamic simulation of a large-scale electric power system involves solving a large number of differential algebraic equations (DAEs) every simulation time-step. With the ever-growing size and complexity of power grid, dynamic simulation becomes more and more time-consuming and computationally difficult using conventional sequential simulation techniques. This thesis presents a fully distributed approach intended for implementation on High Performance Computer (HPC) clusters. A novel, relaxation-based domain decomposition algorithm known as Parallel-General-Norton with Multiple-port Equivalent (PGNME) is proposed as the core technique of a two-stage decomposition approach to divide the overall dynamic simulation problem into a set of sub problems that can be solved concurrently. While the convergence property has traditionally been a concern for relaxation-based decomposition, an estimation mechanism based on multiple-port network equivalent is adopted as the preconditioner to enhance the convergence of the proposed algorithm. The algorithm is presented in detail and validated both in terms of accuracy and capability