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1
Aran, Gokhan. "Aerothermodynamic Analysis And Design Of A Rolling Piston Engine." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608449/index.pdf.
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A rolling piston engine, operating according to a novel thermodynamic cycle is designed. Thermodynamic and structural analysis of this novel engine is carried
out and thermodynamic and structural variables of the engine were calculated. The losses in the engine, friction and leakage were calculated and their effects on the engine were demonstrated.
2
Zalibera, Tomáš. "Výpočetní analýza provozních deformací válcové jednotky vznětového motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417726.
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Submitted diploma thesis deals about operational deformations in the cylinder unit of turbocharged diesel engine used in commercial vehicles. Introductory part analyses combustion engines computational modelling based on finite element method. The next step is the creation of computational models for thermal-structural analyses of the piston and engine block. In order to determine material characteristics of the head gasket, experiment is performed on the OEM gasket to determine its real behaviour under compressive load. The results shows strong nonlinear behaviour which justifies the decision of making such an experiment in the first place. The results of computational models are radial deformations of the piston and cylinder liners during load conditions. The last chapter deals with the application of these results to an advanced computational piston assembly dynamics model.
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Zelko, Lukáš. "Píst zážehového motoru pro 3-D tisk." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400468.
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The goal of the thesis was to design a piston manufactured by conventional method and subsequently adjusted one for additive manufacturing. Beside the designs, thermo-structural model was created for both pistons, considering maximal loading of the engine. Analysis evaluation showed the possibility of further application of the new technology in comparison to current one, within automotive industry.
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Valtrová, Martina. "Píst zážehového motoru vyráběný aditivní technologií." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-449789.
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The first objective of this thesis was compiling research about currently produced pistons for internal combustion engines and about additive manufacturing and based on the acquired information deciding which type of piston makes the most of the advantages. Following this research, the next step was creating a design adjustment of a piston, which was previously designed with the conventional methods of manufacturing in mind, in a way that would make the best use of the different possibilities of additive manufacturing. There was also an optimisation carried out, which depicted the densities of material elements in the piston, showing where the material was less important. There were three variants of the additive manufactured piston created, ranging from a relatively conservative design, which could be theoretically produced by conventional methods with a more substantial subtraction of material added, to a design which could only be produced via additive manufacturing. A thermo-structural analysis at maximum engine load was carried out for all these piston models. Based on these data, a conclusion was made, whether the use of additive manufacturing was justified over the use of the conventional subtractive methods.
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Castillo, Moscoso Samantha Jessie, and Hernandez Jesus Humberto Flores. "Análisis de la interacción entre estructuras adyacentes de concreto armado de 5 y 12 pisos sin una adecuada junta de separación sísmica en la ciudad de Lima." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/628036.
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La gran prioridad del ingeniero civil es brindar seguridad al ciudadano en cualquiera de las edificaciones y/o construcciones que este esta seguridad siempre debe estar ligada a obtener la infraestructura adecuada a un costo razonable. En nuestro país los proyectos de construcción, en particular las edificaciones que son nuestro caso en estudio, podrían durante un sismo, presentar diversos motivos de fallas, entre ellos, y en el que nos vamos a enfocar es en la falla producida por el contacto entre estructuras vecinas durante un movimiento sísmico.
Consideramos que el rápido aumento de las edificaciones para uso residencial y la todavía existente informalidad en la construcción, han sido algunas de las razones que han generado que en el Perú existan edificaciones contiguas construidas sin una adecuada junta de separación sísmica, a pesar de que en el reglamento de construcción este indicado. Tomando en cuenta que el país se encuentra ubicado en una zona altamente sísmica, dichas edificaciones podrían ser severamente dañadas durante el evento de un movimiento sísmico.
Es por tal motivo, que se busca conocer y analizar el efecto en las estructuras adyacentes de concreto armado de juntas de separación sísmicas inferiores a lo reglamentado, determinando la fuerza de impacto producida por el fenómeno de golpeo entre estructuras (pounding). Se considera que la información a obtenerse será de gran importancia, debido a la falta de investigaciones en idioma español en nuestro país sobre dicho fenómeno. Una vez determinada la fuerza de impacto entre las estructuras se esbozarán posibles soluciones que consideremos que podrían ayudar a mitigar el problema.The main priority for a civil engineer is to provide security to citizens in any buildings and/or constructions he makes, this security always has to be linked to obtain the appropriate infrastructure at reasonable cost. In our country, construction projects specially buildings that are our case of study, could have many causes of failures during an earthquake, among them —and the one we will focus on— is the failure occurred by the contact between neighbor structures during a seismic activity. We consider the rapid increase of buildings for residential use and the yet existing informality in construction have been one of the reasons for generating constructed adjoining buildings without an appropriate seismic separation joints in Peru, in spite of the indications in the building code. Considering that the country is situated in a highly seismically unstable area, these buildings might be severely damaged during a seismic activity. For that reason, we want to discover and analyse the effect in the adjoining reinforced concrete structures of seismic separation joints below regulation, determining the impact force produced by the beating phenomenon between structures (pounding). The information that is going to be obtained is considered to be relevant, due to the lack of researches about this phenomenon in Spanish in our country. Once determined the impact force between structures, possible solutions that we consider might help attenuate the problem will be outlined.
Tesis
6
Oliveros, Andrade Edgard Andrés, and Guillén Dayan Tapahuasco. "Influencia del concreto liviano en el desempeño sísmico de una vivienda multifamiliar de 10 pisos ubicada en Lima." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/628219.
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La presente investigación contempla el diseño de 2 estructuras de 10 pisos, una hecha de concreto convencional y otra de un concreto ligero de arcilla expandida, cabe mencionar que para el diseño y análisis de la estructura de concreto ligero se han considerado criterios del ACI 213R para posteriormente ser verificados con las normativa peruana (norma E030 y E060); sin embargo, analizar una edificación hecha con un material que no ha sido usado con objetivo sismo resistente en nuestra nación, tiene la necesidad de ser evaluado con un método más preciso que el análisis lineal estipulado en nuestra normativa E030. Para este caso, el método de evaluación sísmico está en base al diseño por desempeño que contempla un análisis estático no lineal, el cual permite ver a mejor detalle las diferencias en el comportamiento estructural de ambas edificaciones luego de superar su estado lineal. El objetivo de evaluar ambas estructuras es el de evidenciar la influencia que tiene el uso del concreto ligero en el diseño estructural, comportamiento no lineal, desempeño sísmico y costos en comparación de una estructura de concreto convencional. Tras la evaluación por desempeño sísmico se determinó que, para este caso en específico, las edificaciones convencional y de concreto ligero no cumplen con todos los objetivos de desempeño planteados para una vivienda multifamiliar; sin embargo, la estructura de concreto ligero presenta una mejor respuesta dinámica en comparación de la estructura convencional debido a su principal propiedad, el de presentar un menor peso, que dio como resultados valores de pseudoaceleración mayores al de la estructura de concreto convencional. Finalmente se hace una comparación de costos, donde no se vio mucho ahorro al usar un concreto ligero, pero que este resultado se podría optimizar si se usara el concreto convencional y ligero de forma mixta en una edificación, teniendo en cuenta que el concreto ligero si se puede usar en elementos estructurales que resistan fuerzas sísmicas.The present investigation contemplates the design of 2 structures of 10 floors, one made of conventional concrete and another of a lightweight concrete of expanded clay, it is worth mentioning that for the design and analysis of the structure of light concrete, criteria of the ACI 213R have been considered for subsequently be verified with Peruvian regulations (E030 and E060); However, to analyze a building made with a material that has not been used with a resistant earthquake objective in our nation, needs to be evaluated with a more precise method than the linear analysis stipulated in our E030 regulations. For this case, the seismic evaluation method is based on the performance design that contemplates a non-linear static analysis, which allows us to see in greater detail the differences in the structural behavior of both buildings after overcoming their linear state. The objective of evaluating both structures is to demonstrate the influence of the use of lightweight concrete in structural design, non-linear behavior, seismic performance and costs in comparison to a conventional concrete structure. After the evaluation for seismic performance, it was determined that, for this specific case, conventional and light concrete buildings do not meet all the performance objectives set for a multi-family home; however, the lightweight concrete structure has a better dynamic response compared to the conventional structure due to its main property, that of presenting a lower weight, which resulted in pseudo-acceleration values greater than that of the conventional concrete structure. Finally, a cost comparison is made, where there was not much savings when using a lightweight concrete, but that this result could be optimized if conventional and lightweight concrete is used mixed in a building, taking into account that the lightweight concrete does It can be used in structural elements that resist seismic forces.
Tesis
7
Kumar, Sushil. "CFD Analysis of an axial piston pump." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/21794.
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En el ámbito de la Oleohidráulica, las bombas de pistón poseen los diseños más sofisticados, de hecho, las bombas de pistones son las únicos capaces de trabajar a altas presiones, además de poseer el mejor rendimiento de todo el grupo de bombas existentes. Sin embargo, cabe señalar que todos los diseños de las bombas de pistón, se basan principalmente en la experiencia de los diseñadores, por lo tanto no existen herramientas matemáticas para optimizar el diseño de las diferentes partes de las bombas. Por otra parte, en la actualidad hay empresas como Oilgear Towler, que inserta ranuras (surcos) en los patines deslizantes y en los pistones, (dos partes principales de estas bombas), pero no hay ningún estudio científico para analizar sus ventajas o desventajas. Por lo tanto, es necesario comprender matemáticamente las ventajas y desventajas debido a la presencia de ranuras en la superficie de diferentes partes de la bomba. Hay cuatro superficies de deslizamiento en las bombas de pistones, plato inclinado patín deslizante, barrilete y placa de cierre, pistón cilindro y junta esférica entre pistón y patín deslizante. Lubricación entre estas superficies es necesaria, apareciendo por tanto fugas de fluido a bombear entre las mismas. En este proyecto, nuestro objetivo es analizar cada una de estas diferentes superficies de deslizamiento por separado para comprender su diseño y el efecto de los parámetros de diseño en el comportamiento de la bomba. Una vez se tenga un buen entendimiento de las diferentes partes de la bomba de pistones, el objetivo es modelar el comportamiento dinámico de la presión y flujo en la salida de la bomba. En concreto se ha realizado:
Conjunto plato inclinado, patín deslizante – Estudio de las características estáticas y dinámicas del patín deslizante, incluyendo la ranura tallada en el patín. Las ecuaciones de Navier Stokes en coordenadas cilíndricas se han aplicado entre el patín y el plato incluyendo la ranura. Los resultados presentados en este trabajo contemplan, distribución de la presión, las fugas de fluido, la fuerza y par sobre el patín, se ha estudiado la variación de dichos parámetros al modificar las dimensiones y posición de la ranura. El comportamiento dinámico del patín se ha tenido también en cuenta. Se estudia la posición de la ranura con el fin de optimizar el comportamiento del patín.
Barrilete, placa de cierre.- Se analiza mediante la simulación de las ecuaciones de Reynolds de lubricación por FDM (método de diferencias finitas), la distribución de presiones, las fugas, la fuerza y los pares entre el barril y la placa de cierre. La fuerza total y los pares de torsión sobre el barril, se evalúan partiendo de la presión simulada, mostrando que los pares dinámicos que existen sobre el eje XX son mucho menores que los pares actuantes sobre el eje YY. .
Pistón cilindro - Se ha investigado el comportamiento del pistón mediante la modificación del número de ranuras y su posición, la distribución de la presión en el intersticio pistón-cilindro, la fuerza sobre el pistón, las fugas y el par de torsión que actúa sobre el pistón se han analizado. También las zonas donde la cavitación es probable que aparezca se han presentado, se discute la forma de prevenir la aparición de cavitación a través del uso de ranuras. La ecuación de lubricación de Reynolds se ha modelizado en el intersticio pistón-cilindro mediante el uso de volúmenes finitos, la excentricidad y el movimiento relativo pistón-cilindro se han considerado. Diferentes configuraciones de ranuras han sido evaluadas con el fin de encontrar mínimas fugas, máximo par y mínima aparición de cavitación. Se especifican instrucciones de diseño para optimizar el comportamiento del pistón.
Modelo dinámico de la bomba.- Se ha presentado un amplio conjunto de ecuaciones explícitas para cada parte con movimiento relativo de la bomba de pistones. Todas las ecuaciones se han validado mediante un análisis numérico y en su caso experimental. Las ecuaciones han sido combinadas para estudiar de forma dinámica las perturbaciones de presión y el caudal de fugas. El efecto de la pulsación de caudal cuando se modifica el diseño de la bomba también es presentado. En esta tesis, un modelo de simulación basado en ecuaciones analíticas se ha desarrollado, modelo que produce resultados muy rápidamente y aclara con mucha precisión el efecto de las fugas a través de los diferentes intersticios de la bomba.In the field of Fluid Power, piston pumps possess the most sophisticated designs, in fact, pistons pumps are the only ones capable of working at high pressures, besides possessing the best performance (efficiency) of the entire group of existing pumps. However, it is noted that all the designs of piston pumps, are mostly based on the experience of the designers, thus there exist no mathematical tools for optimizing the design of the different parts of the pumps. On the other hand, there are now companies like Oilgear Towler, who inserted slots (grooves) in the slippers and in the pistons, (two major parts of these pumps) but there is no scientific study to analyze its advantages or disadvantages. There is therefore a need to understand mathematically to study the advantages and disadvantages due to the presence of the groove on the surface of different pump parts. There are four sliding surfaces in the piston pump, Slipper-swash plate gap, Barrel-valve plate gap, Piston-barrel chamber gap and Spherical bearing, where lubrication exists and leakages through these channels occur. In this project, our aim is to analyze each of these different sliding surfaces separately to understand its design constrains and the effect of the design parameters on the pump behavior. After having a better understanding of all the different parts of the piston pump, the aim is to model the dynamic behavior of pressure and flow at the outlet of the pump. Slipper plate gap - To understand static and dynamic characteristics of a piston pump slipper with a groove. Three dimensional Navier Stokes equations in cylindrical coordinates have been applied to the slipper/plate gap, including the groove. The results presented in this thesis include, pressure distribution, leakage, force and torque variations when groove dimensions and position are being modified, the effect of slipper tangential velocity and turning speed are also considered. Design instructions to optimize slipper/groove performance are also given. Barrel-valve plate gap - Present thesis, analyses the pressure distribution, leakage, force and torque between the barrel and the port plate of an axial piston pump by simulating Reynolds equations of lubrication by FDM (finite difference method). The overall mean force and torques over the barrel are evaluated from simulated pressure and it shows that the torque over the XX axis is much smaller than the torque over the YY axis. A detailed dynamic analysis is then studied by using the temporal torque calculated by Bergada. Piston-barrel chamber gap - It is being investigated the piston performance by modifying the number of grooves and their position, pressure distribution in the clearance piston-cylinder, leakage force and torque acting over the piston will be discussed, also the locations where cavitation is likely to appear will be presented, discussing how to prevent cavitation from appearing via using grooves. A finite volume based Reynolds equation model has been formulated for the piston-cylinder clearance which considers the piston eccentricity and the relative tangential movement between piston and barrel. Different configurations of the grooves have been evaluated in search of finding minimum leakage, minimum appearance of cavitation and maximum restoring torque. Design instructions to optimize the piston behavior are also given. Full pump Model - An extensive set of explicit equations for every pump gap will be presented. All of the equations will be checked via performing a numerical analysis of the specified pump clearance, the equations will then be combined to study dynamically pressure ripple and leakages. The effect on the flow ripple when modifying the pump design will also be presented. Therefore in present thesis, a simulation model based on analytical equations has been developed which produce very fast results and clarify very precisely the effect of different leakages happened through the pump clearances.
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Ulusoy, Necati. "Dynamic analysis of free piston Stirling engines." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061217408.
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Kodakoglu, Furkan. "Performance analysis on Free-piston linear expander." UNF Digital Commons, 2017. http://digitalcommons.unf.edu/etd/766.
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The growing global demand for energy and environmental implications have created a need to further develop the current energy generation technologies (solar, wind, geothermal, etc.). Recovering energy from low grade energy sources such as waste heat is one of the methods for improving the performance of thermodynamic cycles. The objective of this work was to achieve long-term steady state operation of a Free-Piston Linear Expander (FPLE) and to compare the FPLE with the currently existing expander types for use in low temperature energy recovery systems. A previously designed FPLE with a single piston, two chambers, and linear alternator was studied and several modifications were applied on the sealing and over expansion. An experimental test bench was developed to measure the inlet and outlet temperatures, inlet and outlet pressures, flow rate, and voltage output. A method of thermodynamic analysis was developed by using the first and second law of thermodynamics with air as the working fluid. The experimental tests were designed to evaluate the performance of the FPLE with varying parameters of inlet air pressure, inlet air temperature, and electrical resistance. The initial and steady-state operation of the FPLE were successfully achieved. An uncertainty analysis was conducted on the measured values to determine the accuracies of the calculated parameters. The trends of several output parameters such as frequency, average root mean square (RMS) voltage, volumetric efficiency, electrical-mechanical conversion efficiency, isentropic efficiency, irreversibility, actual expander work, and electrical power were presented. Results showed that the maximum expander frequency was found to be 44.01 Hz and the frequency tended to increase as the inlet air pressure increased. The FPLE achieved the maximum isentropic efficiency of 21.5%, and produced maximum actual expander work and electrical work of 75.13 W and 3.302 W, respectively.
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Deutsch, Eric J. (Eric Joseph). "Piston ring friction analysis from oil film thickness measurements." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36435.
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Briggs, Maxwell H. "Improving Free-Piston Stirling Engine Power Density." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1432660882.
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Lopez, De La Cruz Freddy, and Arboleda Astrid Odeleid Antonella Choncen. "Estudio comparativo del comportamiento sísmico de un edificio de oficinas de 20 pisos en el distrito de San Isidro con el incremento de la resistencia mecánica del concreto (21MPa, 35MPa y 55MPa) mediante el análisis estático no lineal y de desempeño sísmico." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/654848.
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El uso del concreto de alta resistencia está permitiendo la construcción de edificaciones cada vez más altas, la mejora de sus propiedades mecánicas con respecto al de un concreto de resistencia normal produce menor desplazamiento lateral y con ellos le da más resistencia a la rigidez lateral. Una de las interrogantes es conocer en qué medida mejora el comportamiento sísmico de una edificación con el aumento de la resistencia mecánica del concreto y sobre todo con alta resistencia (55MPa), ya que permite la construcción de elementos más esbeltos. El presente proyecto de investigación tiene como objetivo principal analizar la respuesta sísmica de manera más precisa ante una liberación súbita de energía de gran magnitud. Para llevarlo a cabo se planteó el concepto y diferencias entre un concreto normal y uno de alta resistencia. Asimismo, el aporte de investigaciones científicas que ayudaron a comprender mejor el comportamiento mecánico de un concreto de alta resistencia en diferentes elementos estructurales. Se realizaron análisis y diseño estructural de una edificación de 20 pisos con f’c de 21,35, 55 MPa y un Mix de 21-55 y 35-55 MPa donde se le sometió a un empuje lateral mediante un Pushover para generar mecanismos de rotulación hasta lograr el colapso de la estructura y con ella la obtención de la curva de capacidad. Generando cinco espectros de demanda con un periodo de retorno de 43, 72, 475, 975,1500 años para poder interceptarlo con la curva de capacidad y obtener el punto de desempeño de la estructura.The use of high-strength concrete is allowing the construction of increasingly taller buildings, the improvement of its mechanical properties with respect to that of a normal-strength concrete produces less lateral displacement and with them gives more resistance to lateral stiffness. One of the questions is to know to what extent the seismic behavior of a building improves with the increase in the mechanical resistance of the concrete and especially with high resistance (55MPa), since it allows the construction of slenderer elements. The main objective of this research project is to analyze the seismic response more precisely in the face of a sudden release of energy of great magnitude. To carry it out, the concept and differences between normal and high-strength concrete were raised. Also, the report of scientific research that helped to better understand the mechanical behavior of high-strength concrete in different structural elements. Analysis and structural design of a 20-story building with f'c of 21.35, 55 MPa and a Mix of 21-55 and 35-55 MPa were carried out where it was subjected to a lateral push by means of a Pushover to generate mechanisms of labeling until the collapse of the structure and with it the achievement of the capacity curve. Generating five demand spectra with a return period of 43, 72, 475, 975,1500 years to be able to intercept it with the capacity curve and obtain the performance point of the structure.
Tesis
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Wong, Lak Kin. "Computational Fluid Dynamics Analysis on the Liquid Piston Gas Compression." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/1104.
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"Liquid piston gas compression utilizes a liquid to directly compress gas. The benefit of this approach is that liquid can conform to irregular compression chamber volume. The compression chamber is divided into many small little bores in order to increases the surface area to volume ratio. The heat transfer rate increases with increasing surface area to volume ratio. However, as the bore diameter becomes smaller, the viscous force increases. In order to maximize the heat transfer rate and to minimize the viscous force, computational fluid dynamics is used. ANSYS Fluent is used to simulate the liquid piston gas compression cycle. Having created the model in Fluent, different factors, including diameter, length, liquid temperature, and the acceleration are varied in order to understand how each factor affects the heat transfer and viscous energy loss. The results show that both viscous force and heat transfer rate increase as the diameter decreases. The viscous force increases and the heat transfer decreases as the length increases. Both the viscous force and heat transfer increase as the acceleration increases. The viscous force decreases as the liquid temperature increases. Results show that the highest compression efficiency of 86.4% is found with a 3mm bore radius and a short cylinder. The piston acceleration is advised to be below 0.5g in order to avoid surface instability problem."
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Ryan, James Patrick. "Impact analysis of piston slap in a spark ignition engine." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12156.
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Xu, Dian. "Modeling the structural behavior of the piston rings under different boundary conditions in internal combustion engines." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61926.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-72).
In the process of designing internal combustion engine, piston ring plays an important role in fulfilling the requirements of camber gas sealing, friction reduction and lubrication oil consumption. The goal of this thesis is to have a better understanding of the ring behaviors under different working conditions in a structural level. This thesis is an extension of existing ring design tool. A model is built up to simulate the processes of changing ring states from one to another such as free or fit the ring. It revealed the sensitive characters of the piston ring tip; it expanded the field of application of the existing piston ring design tool; it also investigated the ring bore interaction in more conditions. This work removed the symmetric assumption in the existing tool. A new method that calculates ring free shape and ring bore contact force from ring ovality data is introduced for the first time. The analysis of ring bore interaction is widened. The model was applied to an industry ring design case. In this case it shows the free and fit procedure in this model is physically and mathematically reversible. It shows these procedures are direction independent. The contact force distribution changes when the ring is moving within the distorted bore. It also changes when the wetting or roughness situation is different. This model can calculate the ring free shape from asymmetric measured ovality data. It can also retrieve the desired contact force from it. The piston ring design tool is updated and implemented with these highly appreciable new features. This complete package has high efficiency and a wider practical field.
by Dian Xu.
S.M.
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Kalle, Kalliorinne. "Automated Design Analysis and Lubrication Optimisation for a Heavy-Duty Piston." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74386.
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Jia, Boru. "Analysis and control of a spark ignition free-piston engine generator." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3419.
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In this research, the performance analysis and control strategy of a spark-ignited free-piston engine generator were presented. A literature review of the free-piston engine fundamental information and the recent research development on the free-piston engine generator (FPEG) was provided, mainly focussing on previous work on numerical modelling, prototype design as well as the control strategy. The design and simulation of a dual-piston spark-ignited FPEG suitable for operation using either a two-stroke or four-stroke thermodynamic cycle were presented. Model validation and the general engine performance of the system were discussed. For the first time, this research demonstrated the potential advantages and disadvantages of the FPEG on using different thermodynamic gas-exchange cycles. A fast response real time model of the FPEG was designed and validated. The simplicity and flexibility of the proposed model make it feasible to be implemented and coupled with real-time hardware in the loop control system development. In addition, since it revealed how an FPEG operates according to a resonant principle, the model is useful for parameter selection in the design process. For the first time, cascade control was proposed and investigated for the piston stable operation control, using both the measured piston top dead centre of the previous stroke and the measured piston velocity at the current stroke as feedbacks, with the injected fuel mass as the control variable. The system performance was improved by implementing the cascade control compared with single loop control in terms of the controller response time, peak error and settling time.
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Mbuya, Thomas O. "Analysis of microstructure and fatigue micromechanisms in cast aluminium piston alloys." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/348998/.
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Light vehicle engine pistons have traditionally been cast from near eutectic Al-Si cast alloys due to several favourable functional and processing attributes. The increasingly demanding engine performance requirements have necessitated the need for the development of multicomponent alloys with high alloy content and highly complex microstructure. In this regard, recent trends in new piston alloy development have been to increase the level of various alloying elements such as Cu, Ni and even Si. However, low Si compositions of ∼7 wt% Si and ∼0.7 wt% Si have also been proposed largely due to observations that the large blocky primary Si particles found in the near-eutectic alloys are potent fatigue crack initiators. Nonetheless, previous research on these low Si piston alloys has demonstrated that their fatigue performance is significantly impaired by porosity which increases with decreasing Si content. With improved processing techniques, porosity can be reduced to levels that make it impotent in fatigue failure processes. The aim of this work was therefore to characterise the microstructure and fatigue micromechanisms of the low Si piston alloys after hot isostatic pressing (hipping) to reduce porosity. This was achieved using a combination of various imaging tools and fatigue testing to establish the role of microstructure on initiation and growth of fatigue cracks. It has been demonstrated using X-ray microtomography that hipping significantly reduces porosity, especially in the 0.7 wt% Si alloy, while the intermetallic structures remain largely unaffected. The eutectic Si particles in the 7 wt% Si alloy are however transformed from a fine fibrous interconnected structure to coarse, spheroidised and discrete particles. Hipping has also been observed to improve the fatigue performance of the 0.7 wt% Si alloy due to the significant reduction in porosity. Fatigue crack initiation has been observed to occur mainly at intermetallic particles in both alloys after hipping and, consistent with previous work, the most frequent crack initiating phase is found to be Al 9 FeNi. Analysis of short fatigue crack growth profiles has shown that intermetallics and eutectic Si particles preferentially debond, thus providing a weak path for crack propagation along their interfaces with the α-Al matrix. However, grain boundaries as well as these hard particles have also been shown to frequently act as effective barriers to crack growth. On the other hand, long fatigue crack growth analysis has shown that fatigue cracks tend to avoid Si and/or intermetallic particles at low ΔK levels (up to ΔK∼7 MPa√m). At higher levels of ΔK, the cracks increasingly seek out these hard particles up to a ΔK of ∼9 MPa√m after which the crack preferentially propagates through them. It has also been observed that crack interaction with intermetallics causes significant crack deflection which may result in roughness related closure mechanisms to be activated.
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Giriat, Gaetan. "Instrumentation development for magnetic and structural studies under extremes of pressure and temperature." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7931.
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The study of the magnetic and structural properties of matter under extreme conditions is a fast developing field. With the emergence of new techniques and innovative instruments for measuring physical properties, the need for compatible pressure generating devices is constantly growing. The work described in this thesis is focused on development, construction and testing of several high pressure (HP) cells of novel design. One of the cells is intended for single crystal X-ray diffraction (SXD) studies at low temperature (LT) and the other three HP devices are designed for a Magnetic Property Measurement System (MPMS), two of which are suitable for dc susceptibility studies and the other one is aimed at high frequency ac susceptibility measurements. HP crystallographic studies are routinely carried out in diamond anvil cells (DAC) at room temperature while ambient pressure SXD studies are often conducted at LT to reduce atomic vibrations and obtain more precise structural data as well as to study LT phases. Combining HP with LT gives access to a whole new area on the phase diagrams but due to the size of the existing DACs this is generally achieved by cooling down the cells inside a cryostat and it is mainly possible at synchrotrons where dedicated facilities exist. A miniature DAC which can be used with commercially available laboratory cry-flow cooling systems and achieves pressures in excess of 10 GPa has been developed. The design of the pressure cell is based on the turnbuckle principle and therefore it was called TX-DAC. Its dimensions have been minimised using Finite Element Analysis (FEA) and the final version of the cell weighs only 2.4 g. The cell is built around a pair of 600 μm culet Boehler-Almax anvils which have large conical openings for the diffracted beam. The TX-DAC is made of beryllium copper (BeCu) alloy which has good thermal conductivity and allows quick thermal equilibration of the cell. The MPMS from Quantum Design is the most popular instrument for studies of magnetic properties of materials. It is designed to measure ac and dc magnetic susceptibility of sample with detectable signals as low as 10-8 emu. The MPMS has a sample chamber bore of 9 mm in diameter and this puts a constraint on the dimensions of the pressure cells. However, several types of clamp piston-cylinder cells and DACs have been designed for the MPMS. The former are used for measurements at pressure up to 2 GPa and the later can be used for studies at higher pressure. Taking advantage of the turnbuckle principle, a DAC (TM-DAC) and a piston-cylinder cell (TM-PCC) for dc magnetic studies were built. They allow HP measurements to be performed at the full sensitivity of MPMS. Both pressure cells are made of BeCu and their small dimensions combined with symmetrical design is the key to an ideal background signal correction. The TM-DAC is 7 mm long and 7 mm in diameter, it weighs 1.5 g and with 800 μm culet anvils it can generate a sample pressure of 10 GPa. Inherently the sample volume is limited to approximately 10-3 mm3 and the signal corresponding to this volume of some weakly magnetic material remains below the sensitivity of the MPMS. This constraint led us to the development of the TM-PCC – a piston-cylinder variant of the turnbuckle design. With a 4 mm3 sample volume it allows the study of weakly magnetic samples in the range 0-1.9 GPa. The TM-PCC uses two zirconia pistons of 2.5 mm in diameter; it is 10 mm long, 7 mm in diameter and weights 2.7 g. Conventional metallic pressure cells perform well in dc mode however in ac susceptibility measurements, the Eddy currents set in the cells’ body lead to a screening effect which can significantly obscure the signal from the sample. This problem was solved by designing a composite piston-cylinder cell made with Zylon fibre and epoxy resin. The sample is located in the middle of the cell in the 2.5 mm bore and the pressure is transmitted through zirconia pistons. Keeping the metallic parts away from the sample resolves any interference issue. The composite cell performs well in a pressure range of 0-1 GPa. The performance of the pressure cells developed within this project is illustrated by studies of various systems at high pressure.
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Hee, Ik Nang Anna. "Plenix structural analysis." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847508/.
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With the introduction of reliable and high speed computers in the past few decades, together with the demand of today's engineering problems which include the design of large and complex structures, the processes of data generation and organisation present a real challenge. The main theme of this thesis is to develop a new method of structural analysis which is based on the concepts of formices and plenices. This method simplifies the processes of data generation and organisation in engineering design. Formex algebra is a mathematical system that may be used to represent and process any form of configuration. In engineering design, the basic approach is to represent the interconnection pattern of a structural configuration by a formex. This information is then related to other relevant data of the structure which is needed for the analysis by a plenix. A plenix is a mathematical object that can be used to simplify the processes of data organisation and decision making in automated analytical procedures. The mathematics of formices and plenices provide a powerful and versatile tool for representation and processing configurations, and organising information.
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Lu, Zhaohua. "Structural vulnerability analysis." Thesis, University of Bristol, 1998. http://hdl.handle.net/1983/ee6b66b4-7b8b-4104-9571-fd17d8c16b05.
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A structure is vulnerable if any damage produces consequences which are disproportionate to that damage. Conversely a structure is robust if it can withstand arbitrary damage. The theory of vulnerability developed in this thesis concerns structural form and connectivity. The purpose of the theory is to identify the "weak links" within a structure. A new theory of vulnerability for 3D structures has been developed. An entirely new approach has been derived from the 2D theory developed by Wu, Blockley, Woodman (1993), Yu(1997). New concepts of a graph model for 3D structural systems, 3D structural path and loop, structural round, string pattern of structural round, 3D structural tightness, 3D structural clusters, deterioration hierarchy of structural round etc. have been defined and introduced. A method of combining structural vulnerability analysis with structural response analysis has been developed and illustrated with three examples. 2D structural vulnerability theory as developed most recently by Yu(1997) has also been re-examined and improved. The algorithm for computer implementation of 2D structural vulnerability theory has been greatly improved. The improved algorithm provides a more complete search, always use the most up to date hierarchy and has a special treatment for structure with a mixture of types of joint. In order to create a graphical user interface for SAVE (Structural Analysis for Vulnerability Estimation) (Yu, 1997), some graphical functions have been developed. These graphical functions include: drawing the structure; drawing the cluster formation procedures; drawing the hierarchical presentation; drawing the most vulnerable failure scenarios in the structure. The theory is potentially of use in the design of protection and performance monitoring programmes for safety management and to reduce the risk of overlooking vulnerable failure scenarios
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Hansson, Jörgen. "Analysis and control of a hybrid vehicle powered by free-piston energy converter." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4189.
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The introduction of hybrid powertrains has made it possible to utilise unconventional engines as primary power units in vehicles. The free-piston energy converter (FPEC) is such an engine. It is a combination of a free-piston combustion engine and a linear electrical machine. The main features of this configuration are high efficiency and a rapid transient response.
In this thesis the free-piston energy converter as part of a hybrid powertrain is studied. One issue of the FPEC is the generation of pulsating power due to the reciprocating motion of the translator. These pulsations affect the components in the powertrain. However, it is shown that these pulsations can be handled by a normal sized DC-link capacitor bank. In addition, two approaches to reduce these pulsations are suggested: the first approach is using generator force control and the second approach is based on phase-shifted operation of two FPEC units. The latter approach results in higher frequency and lower amplitude of the pulsations, which reduce the capacitor losses.
The FPEC start-up requirements are analysed and by choosing the correct amplitude of the generator force during start-up the energy consumption can be minimised.
The performance gain of utilising the FPEC in a medium sized series hybrid electric vehicle (SHEV) is also studied. An FPEC model suitable for vehicle simulation is developed and a series hybrid powertrain, with the same performance as the Toyota Prius, is dimensioned and modelled.
Optimisation is utilised to find a lower limit on the SHEV's fuel consumption for a given drivecycle. In addition, three power management control strategies for the FPEC system are investigated: two load-following strategies using one and two FPEC units respectively and one strategy based on the ideas of an equivalent consumption minimisation (ECM) proposed earlier in the literature.
The results show a significant decrease in fuel consumption, compared to a diesel-generator powered SHEV, just by replacing the diesel-generator with an FPEC. This result is improved even more by using two FPEC units to generate the propulsion power, as this increases the efficiency at low loads. The ECM control strategy does not reduce the fuel consumption compared to the load-following strategies but gives a better utilisation of the available power sources.
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Ratnam, Mani Maran. "An experimental and finite element analysis of the thermal deformation of an open sleeve piston." Thesis, University of South Wales, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292281.
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Hansson, Jörgen. "Analysis and control of a hybrid vehicle powered by a free-piston energy converter /." Stockholm : Electrical Machines and Power Electronics, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4189.
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Stage, Roger. "Analysis of a planar spiral displacer spring for use in free-piston stirling engines." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183748239.
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Yu, Yin. "Analysis of structural vulnerability." Thesis, University of Bristol, 1997. http://hdl.handle.net/1983/7d8392ee-c2b6-4bf1-97d5-c3178bd93d45.
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Balakrishnan, Sashi. "Transient elastohydrodynamic analysis of piston skirt lubricated contact under combined axial, lateral and tilting motion." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/19897.
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Most modern engines utilise pistons with an offset gudgeon pin. In internal combustion engines, the offset is to the major thrust side of the piston. The piston thrust side is the part of the piston perpendicular to the gudgeon pin that carries the majority of side loading during the power stroke. Primary reason for having the gudgeon pin positioned eccentrically is to prevent the piston from slamming into the cylinder bore after the connecting rod journal passes the top dead centre. This phenomenon is referred to as piston slap, and is more pronounced in compression ignition and high performance engines due to higher combustion pressure than that of commercial spark ignition engines. The coming together of the piston and the bore results in scuffing, at best, or, catastrophic failure at worst. Clearance space between bore and piston is filled by a lubricant film. The main role of the lubricant is to separate the piston and bore by reacting to the applied load. Investigating the above problem requires a holistic approach, whereby a dynamic three degree-of-freedom piston model is coupled with a lubrication model to represent the actual system. The dynamic model determines the motion of the piston in combined axial, lateral and rotation about the gudgeon pin. The reactive forces due to lubricant films on the major and minor thrust sides of the piston play significant roles in piston dynamics and are evaluated by either quasi-static or transient solution of the lubricant contact conjunctions. The novel quasi-static analysis is carried out in the sense of its detailed approach, including many key practical features. not incorporated in other analyses, hitherto reported in literature. These features include first and foremost the development of a specific contact mechanics model for evaluation of conforming contacts for piston skirt against liner or bore. The quasi-static analysis includes many practical feature not encountered in other literature on the subject, such as detailed surface irregularities and modification features, and with thermal distortion. The analysis has been extended to thermohydrodynamics, as well as micro-hydrodynamics, all with high computational mesh densities, and robust methods of solution in space and time domains, including effective influence Newton-Raphson method and linear acceleration integration scheme. The transient tribo-elasto-multi-body dynamics problem includes physics of motion study from film thickness prediction and secondary motion evaluation of the order of micrometers and minutes of arc to large rigid body dynamics, including simultaneous solution of the contact problem at both major and minor thrust sides. Such a comprehensive solution has not hitherto been reported in literature. The thesis discusses many aspects of piston dynamics problem, through the broad spectrum of vehicle manufacture, with many pertinent practical engineering issues. In particular, it provides solutions for high performance Formula 1 racing engines. This is the first ever comprehensive analysis of piston tribodynamics for this range of engines at very high combustion pressures. This study has shown the paramount influence of profile of piston in promoting lubrication between the contiguous bodies, as evident from the pattern of lubricant flow through the contact. Deformation of the bodies increases the volume of lubricant in the contact. During the reversal in direction of piston motion, when the entraining velocity momentarily cases and reversal takes place, the load is held by an elastic squeeze.
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Senzer, Eric B. "Piston ring pack design effects on production spark ignition engine oil consumption : a simulation analysis." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42309.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 113-115).
One of the most significant contributors to an engine's total oil consumption is the piston ring-pack. As a result, optimization of the ring pack is becoming more important for engine manufacturers and lubricant suppliers. This leads to current efforts to control the oil transport and flow through the ring pack. Decreasing the amount of oil needed for proper lubrication while minimizing, frictional losses are the goals of such research. The hope is to fully understand the mechanisms that govern oil's flow, and then control it. Analytical tools and computer simulation models have been created to assist in predicting the performance of a given ring pack. This study intended to be an experimental look at the effects of piston-ring-pack design changes on the steady-state and transient oil consumption of a spark ignition engine. Namely, the effects of a V.-Cut on the 2nd land, a chamfer on the 3rd land, OCR groove drain holes, and the OCR design were to be examined. However, after some minor measurements, the engine experienced a major malfunction that caused it to cease operation. The focus of the study shifted to a more theoretical, computer simulated concentration of the aforementioned design changes. Different speeds -and loads were analyzed along with the notation of some general observations. In the end, the effects of the design modifications on ring dynamics and gas flow were qualified. The presence of a V-Cut on the 2nd land of the piston had beneficial and adverse effects on the general performance of the ring pack. The added volume decreased the 2nd land pressure enough to avoid 2nd ring radial collapse, but it also caused reverse flutter to occur at lower loads. Using a chamfer on the upper portion of the 3rd land also had mixed results. Stability of the 2nd ring was greatly improved with less radial collapse and an increase in average blowby flow.
(cont.) The performance of the OCR design was primarily dependent on the gap area of the ring and the variation of groove clearances. The OCR groove drain holes were also deemed a necessity. This research, though theoretical in nature, brings together many ideas that offer solutions to common problems. Radial collapse, reverse flutter, OCR cost, and the use of drainage holes all are part of the attempts to improve the piston-ring-pack performance while driving down cost of production. Future experiments will put the theoretical conclusions to the test with the continuation of the pistons not installed in the engine due to the events previously explained.
by Eric B. Senzer.
S.M.
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Rodriguez, Martin. "Structural analysis of SLICE hulls." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA295249.
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Llop, Escorihuela Esther. "Structural analysis of eythropoietin glycans." Doctoral thesis, Universitat Pompeu Fabra, 2008. http://hdl.handle.net/10803/7129.
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La eritropoyetina o EPO es una hormona glicoproteica. En los seres humanos adultos, se produce principalmente en el riñón, en respuesta a la reducción de oxígeno en los tejidos (hipoxia tisular). La EPO estimula la eritropoyesis, es decir, estimula a las células madre de la médula ósea para que aumenten la producción de eritrocitos. La molécula de EPO está formada por una cadena peptídica de 165 aminoácidos que contiene dos puentes disulfuro, un O-glicano (Ser-126), y tres N-glicanos (Asn-24, 38, 83). En conjunto, la glicosilación de esta proteína representa aproximadamente el 40% del peso total (29.4 kDa). La EPO sintetizada con tecnología recombinante (rEPO) se administra como fármaco, desde el año 1989, para el tratamiento de anemias, insuficiencia renal, cancer etc. También se ha observado la utilización de rEPO en deportistas con el fin de aumentar el suministro de oxígeno a los tejidos y así incrementar el rendimiento en deportes de resistencia. En el año 2001, se comercializó una "nueva proteína estimuladora de la eritropoyesis" llamada NESP. Esta proteína es un análogo hiperglicosilado de la EPO que posee dos N-glicanos adicionales (Asn-30, 88). El número y composición de los N-glicanos es muy importante para el metabolismo de estas glicoproteínas, ya que el contenido de carbohidratos (número de ácidos siálicos) determina su vida media. Los métodos que se utilizan actualmente para diferenciar la eritropoyetina endógena urinaria (uEPO) de sus análogos recombinantes (rEPO, NESP) están basados en las diferencias que existen entre sus perfiles isoelectroforéticos (IEF). Se cree que estas diferencias provienen de las células y/o especies en las que se expresan estas glicoproteínas. En este estudio, se llevo a cabo la caracterización estructural de diferentes preparaciones de EPO recombinante. Para ello, se utilizaron las técnicas más comunes en el campo de la glicoproteómica además de otras nuevas, desarrolladas para poder analizar los glicanos de muestras procedentes de geles 2-DE. Los perfiles de glicosilación total de cada una de estas glicoproteínas mostraron características estructurales que pueden facilitar la detección de rEPO y NESP en atletas que abusan de estas sustancias. Un ejemplo es la presencia de Neu5Gc únicamente en fármacos que han sido expresados en células CHO. La metodología desarrollada en este trabajo, podría emplearse también, para el control de calidad de estos fármacos y para el diagnóstico de ciertas patologías.Erythropoietin (EPO) is a glycoprotein hormone secreted primarily by adult kidneys in response to tissue hypoxia. It is involved in the maturation and ultimately regulation of the level of red blood cells. The EPO molecule comprises a single polypeptide chain of 165 aminoacids with two disulfide bonds, 1 O-linked (Ser-126), and 3 N-linked (Asn-24, 38, 83) glycans representing about 40% of the total mass (29.4 kDa). The recombinant analogue (rEPO), available since 1989 has found widespread use in the treatment of anaemia, renal failure, cancer etc. Besides, rEPO is illicitly used by athletes to boost the delivery of oxygen to the tissue and enhance performance in endurance sports. In 2001, a novel erythropoiesis-stimulating protein (NESP) was also marketed. NESP possesses two additional N-glycans (Asn-30, 88). The number and composition of the N-glycans is very important in the metabolism of this glycoprotein because the carbohydrate content (sialylation degree) determines its half-life time. Current tests to differentiate between urinary endogenous (uEPO) and its recombinant analogues (rEPO, NESP) are based on differences in their iso-electric focussing (IEF) profiles. Those differences are believed to stem from the cells/species in which they are expressed. In this study, the structural characterisation of different rEPO preparations was conducted using standard techniques in the field and developing new ones to address glycans from 2-DE sample preparations. Overall glycosylation profiling of each glycoprotein revealed structural features that may pave the way to the unambiguous detection of rEPOs and NESP abuse, such as the presence of Neu5Gc in CHO cell derived drugs only, and the developed methodology may be also employed for maintaining pharmaceutical quality control and for diagnosing pathologic conditions.
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Ebenhöh, Oliver. "Structural analysis of metabolic networks." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967762499.
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Ushaksaraei, Reza. "Numerical analysis of structural masonry /." *McMaster only, 2002.
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Schafer, Robin. "A Structural Analysis of Mutation." Department of Linguistics, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/227234.
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Jabboor, Wasseem. "Dynamic structural analysis of beams." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2469.
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The research reviews the various methods, accurate and approximate, analytical and numerical, used for the analysis of beams that are subjected to dynamic loads. A review of previous research is presented. A detailed description of one of the methods, the Simplified Elastic Plastic Method (the SEP Method), a well-developed approximate method, is given. A finite element model, built with the aid of the computer software ABAQUS, is described. Results of 20 experiments made by others are provided and used as a benchmark for the finite element analysis. The methodology used for the validation of the ABAQUS Model and the SEP Method is to do, for various study cases, a comparison between the experimental results, those computed using the ABAQUS Model and those predicted using the SEP Method. Having validated the ABAQUS Model, it has been used as a benchmark with which to check the SEP Method. Therefore, additional cases have been analysed using the ABAQUS Model in order to cover a more comprehensive range of variables. A good agreement has been found between the results. The accuracy of the ABAQUS model and the conservatism of the SEP Method are shown. A design procedure using the SEP Method has been developed. Calibration factors are also proposed in order to reduce the conservatism in the SEP Method. The results and recommendations of the research can be employed in the defence industry, civil and structural engineering.
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Schaedlich, Mirko. "Nonlinear transient structural response analysis." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438667.
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Slusser, Wayne T. "The structural analysis of Philemon." Online full text .pdf document, available to Fuller patrons only, 2001. http://www.tren.com.
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Ebenhöh, Oliver. "Structural analysis of metabolic networks." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2003. http://dx.doi.org/10.18452/14853.
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In der vorliegenden Arbeit werden zwei Modelle zur strukturellen Analyse von Stoffwechselsystemen vorgestellt. Die Untersuchung basiert auf der Hypothese, dass heutzutage vorzufindende Stoffwechselsysteme als Ergebnis einer evolutionären Entwicklung, bestimmt durch Mutationsmechanismen und natürlicher Selektion, angesehen werden können. Es kann daher angenommen werden, dass kinetische Parameter sowie strukturelle Eigenschaften im Laufe der Evolution solche Werte angenommen haben, die eine gewisse Optimalität bezüglich ihrer biologischen Funktion darstellen. Das erste Modell untersucht das strukturelle Design ATP und NADH produzierender Systeme, so wie die Glykolyse und der Zitratzyklus. Eine Methode wird präsentiert, die die Beschreibung hypothetischer, chemisch denkbarer, alternativer Stoffwechselwege ermöglicht. Diese Wege werden bezüglich ihrer Effizienz, ATP zu produzieren, untersucht. Es stellt sich heraus, dass die meisten möglichen Wege eine niedrige ATP-Produktionsrate aufweisen und dass die effizientesten Wege einige strukturelle Gemeinsamkeiten besitzen. Die Optimierung bezüglich der ATP-Produktionsrate wird mit einem evolutionären Algorithmus durchgeführt. Folgende Resultate stehen mit dem tatsächlichen Design der Glykolyse und des Zitratzyklus in Einklang: (i) In allen effizienten Wegen befinden sich die ATP-verbrauchenden Reaktionen am Anfang. (ii) In allen effizienten Wegen befinden sich die sowohl die NADH- als auch die ATP-produzierenden Reaktionen am Ende. (iii) Die Anzahl der NADH-Moleküle, die aus einem energiereichen Molekül (Glukose) produziert werden, beläuft sich in allen effizienten Wegen auf vier. Im zweiten Modell werden vollständige Mengen metabolischer Netzwerke konstruiert, wobei von Reaktionen ausgegangen wird, die Änderungen des Kohlenstoffskeletts der beteiligten Metabolite beschreiben. Elementare Netzwerke werden dadurch definiert, dass eine bestimmte chemische Umwandlung durchgeführt werden kann und dass diese Fähigkeit verloren geht, wenn eine der beteiligten Reaktionen ausgeschlossen wird. Übergänge zwischen Netzwerken und Mutationen werden durch den Austausch einer einzigen Reaktion definiert. Es existieren verschiedene Mutationen, solche bei denen Funktionen verloren gehen, welche dazugewonnen werden, und neutrale Mutationen. Mutationen definieren Nachbarschaftsrelationen, die graphentheoretisch beschrieben werden. Eigenschaften wie Durchmesser, Konnektivität und die Abstandsverteilung der Vertizes werden berechnet. Ein Konzept zur Quantifizierung der Robustheit von Netzwerken gegenüber stöchiometrischen Veränderungen wird entwickelt, wobei zwischen starker und schwacher Robustheit unterschieden wird. Evolutionäre Algorithmen werden angewandt, um die Entwicklung von Netzwerkpopulationen unter konstanten und zeitlich veränderlichen Umweltbedingungen zu untersuchen. Es wird gezeigt, dass Populationen sich zu Gruppierungen von Netzwerken hinentwickeln, die gemeinsame Funktionen besitzen und nah benachbart sind. Unter zeitlich veränderlichen Umweltbedingungen zeigt sich, dass multifunktionelle Netzwerke optimal sind und sich im Selektionsprozess durchsetzen.In the present thesis two models are presented which study the structural design of metabolic systems. The investigation is based on the hypothesis that present day metabolic systems are the result of an evolutionary development governed by mutation mechanisms and natural selection principles. Therefore, it can be assumed that these parameters have reached, during the course of their evolution, values which imply certain optimal properties with respect to their biological function. The first model concerns the structural design of ATP and NADH producing systems such as glycolysis and the citric acid cycle. A method is presented to describe hypothetical, chemically feasible, alternative pathways. We analyse these pathways with respect to their capability to efficiently produce ATP. It is shown that most of the possible pathways result in a very low ATP production rate and that the very efficient pathways share common structural properties. Optimisation with respect to the ATP production rate is performed by an evolutionary algorithm. The following results of our analysis are in close correspondence to the real design of glycolysis and the TCA cycle: (i) In all efficient pathways the ATP consuming reactions are located near the beginning. (ii) In all efficient pathways NADH producing reactions as well as ATP producing reactions are located near the end. (iii) The number of NADH molecules produced by the consumption of one energy-rich molecule (glucose) amounts to four in all efficient pathways. In the second model complete sets of metabolic networks are constructed starting from a limited set of reactions describing changes in the carbon skeleton of biochemical compounds. Elementary networks are defined by the condition that a specific chemical conversion can be performed by a set of given reactions and that this ability will be lost by elimination of any of these reactions. Transitions between networks and mutations of networks are defined by exchanges of single reactions. Different mutations exist such as gain or loss of function mutations and neutral mutations. Based on these mutations neighbourhood relations between networks are established which are described in a graph theoretical way. Basic properties of these graphs are determined such as diameter, connectedness, distance distribution of pairs of vertices. A concept is developed to quantify the robustness of networks against changes in their stoichiometry where we distinguish between strong and weak robustness. Evolutionary algorithms are applied to study the development of network populations under constant and time dependent environmental conditions. It is shown that the populations evolve toward clusters of networks performing a common function and which are closely neighboured. Under changing environmental conditions multifunctional networks prove to be optimal and will be selected.
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El-Labbar, O. F. A. "Formex graphics in structural analysis." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847403/.
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Computer-aided structural analysis processes are highly dependent on the use of computer graphics. The objective of this work is to evolve techniques that allow structural analysts, designers and architects to work with computer graphics in a convenient manner. The formex approach of data generation is explained through a number of examples. This approach enables data to be generated very conveniently for the purposes of structural analysis. Also, introduced are the main features of an interactive programming language which acts as a vehicle to implement the concepts of formex algebra. An attempt to investigate the possibility of using the concepts of formex graphics in postprocessing stages of structural analysis is presented. This enables output of structural analysis programs to be graphically displayed so that plots of structural configurations can be shown in both their deformed and undeformed shapes. It is also shown that it is possible to employ the concepts of formex graphics in order to produce axial force, shear force, bending moment and torque diagrams in a manner that they can be visualized conveniently.
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Wu, Xin. "Vulnerability analysis of structural systems." Thesis, University of Bristol, 1991. http://hdl.handle.net/1983/4319e1df-db0b-4700-8445-f36583172433.
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Sjöstrand, Edvin. "Structural Analysis of Underwater Detonations." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85099.
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The knowledge how an object withstand an underwater detonation is critical within the defense industry. This is mostly done today with physicals test which are both time consuming and connected with high costs. The aim of this thesis is to provide recommendations and guidelines on how to model and analyze a structural response of underwater detonations. This investigation are focused on firstly investigate several theoretical simulation methods and thereafter develop a model of the chosen method. The simulation method was decided to be the Multi-Material Arbitrary Lagrangian Euler(MMALE) using the software LS-Dyna. To receive a model with functionality to simulate an explosion a method of six steps is developed to increase the complexity. The final step is to be able to analyze a structural response of an object. The validation phase contained several convergence studies of the two Equations of states and a varying element size compared to analytical equations. The plan was to perform a validation test but because of travel restrictions due to the Covid-19 situation an alternative validation method was used. This method involved two external reports with specified measurement data. The aim to develop a model is reached as the model performs well against the cylinder in the validation phase, however the element size is the most important parameter in an accurate model. The developed model shows good agreement regarding the structural response of an object when compared to well defined and reported experiments.
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Al-Ahmadi, Abdullah. "Structural analysis of humic materials." Thesis, Aston University, 1986. http://publications.aston.ac.uk/14509/.
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Ramos, André Luiz. "Análise numérica de pisos mistos aço-concreto de pequena altura." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-28072010-093719/.
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Os pisos mistos aço-concreto de pequena altura caracterizam-se pelo embutimento da laje de concreto na altura da viga de aço, sendo a laje apoiada na mesa inferior do perfil. A principal vantagem deste sistema em relação à viga mista convencional é a redução da altura total do composto. Este trabalho tem como objetivo a criação de um modelo numérico construído no software de elementos finitos TNO DIANA®. O modelo proposto nesta pesquisa buscou subsídios para sua validação em resultados experimentais e numéricos realizados em outras pesquisas. Na fase de validação foram alterados diversos fatores a fim de avaliar a influência de cada um deles, calibrando o modelo até que os resultados se aproximassem dos experimentais. Depois que o modelo foi validado, foi analisada a influência de alguns parâmetros no comportamento global da estrutura, entre eles: a resistência do concreto (fck), a consideração de uma tela de armadura passiva colocada na capa de concreto com diferentes taxas de armadura e a variação da espessura da capa de concreto. Os resultados mostraram que o modelo consegue representar de maneira adequada o comportamento da estrutura apesar das simplificações consideradas para a modelagem.Composite steel-concrete slim floors are characterized by the inlay of the concrete slab on the same plane of the steel beam, with the slab supported by the bottom flange of the profile. The main advantage of this system compared to the conventional mixed beam is the reduction of the overall height of the compound. This study aims to establish a numerical model built in finite element software TNO DIANA®. The model proposed in this research sought subsidies for its validation in experimental and numerical results achieved in others researches. In the validation phase were changed several factors to evaluate the influence of each of them, calibrating the model until the results come closer to the experimental. After the model has been calibrated, were analyzed the influence of some parameters on the overall behavior of the structure, among them: the strength of concrete (fck), the consideration of reinforcement bars placed on the slab with different rates and the variation of the thickness of the concrete slab. The results showed that the model can adequately represent the structural behavior despite the simplifications considered for modeling.
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McConnachie, Jennifer. "Finite element analysis of conformal contacts in water hydraulic axial piston pumps incorporating advanced ceramic materials." Thesis, University of Hull, 1995. http://hydra.hull.ac.uk/resources/hull:14764.
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The use of water as a hydraulic fluid in a pump necessitates the use of conformal contacts to reduce the high rates of wear and leakage losses that result from the low viscosity and lubricity of water. Swashplate type axial piston pumps are ideal in this respect because they incorporate such conformal contacts. Furthermore, the development of such a pump for use with water, especially sea-water, critically relies on the correct selection and application of materials. The purpose of this research work is firstly to examine the contact conditions within an axial piston pump for a range of sleeved and lined components manufactured from a variety of different materials. The use of finite element analysis with gap elements is a useful way of determining the contact pressure distribution between conformally contacting components. It is shown that this method gives excellent agreement with available analytical methods for the two-dimensional cylindrical and axisymmetric spherical cases, and thus can be extended to layered components. Extension to three dimensions, when the contact cannot be accounted for by plane strain or plane stress conditions, is also possible, allowing a much more representative analysis of the contact conditions within an axial piston pump. No single combination of materials is identified as being the most suitable, rather, the method enables the consequences of choosing materials for their tribological characteristics to be examined. Once the contact conditions are known within the pump it is then possible to more accurately design the pump components. However, conventional deterministic methods are not appropriate for designing ceramic components, due to the inherent scatter of limiting defects, and statistical methods are necessary. Thus the second part of this research work is aimed at reviewing and examining the different probabilistic design methods with the long-term view of determining which, if any, are best suited to the design of ceramic components in this particular application. It is conduded that no single method adequately predicts the probability of failure of ceramic specimens with more complex stress distributions than four-point flexure bars.
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Mello, Antonio Vicente de Almeida. "Vibrações em pisos de edificações induzidas por atividades humanas." Universidade do Estado do Rio de Janeiro, 2005. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=418.
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Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de JaneiroAtualmente, as novas tendências arquitetônicas e as exigências de mercado, vêm conduzindo a engenharia estrutural na busca por soluções cada vez mais arrojadas, as quais exigem grande experiência e conhecimento dos projetistas estruturais aliados a utilização de novos materiais e tecnologias. Esta filosofia de concepção estrutural está inserida em uma das mais importantes tendências de projeto dos últimos anos, ou seja: a busca por sistemas estruturais de rápida execução, dotados de peças de menor peso próprio e que possam vencer grandes vãos com um mínimo de elementos verticais, permitindo assim uma maior flexibilidade na adequação de ambientes. Por outro lado, esta filosofia de projeto tem conduzido a elementos estruturais cada vez mais esbeltos e com freqüências naturais cada vez mais baixas e, por conseguinte, mais próximas das faixas de freqüência das excitações dinâmicas associadas às atividades humanas, tais como: andar, correr, pular, etc. Devido as razões expostas no parágrafo anterior, os sistemas estruturais de engenharia tornaram-se bastante vulneráveis aos efeitos de vibrações induzidas por pequenos impactos como é o caso do caminhar de pessoas sobre pisos, resultando em desconforto para as pessoas. Deve-se destacar, ainda, que tais considerações de projeto têm atendido aos estados limites últimos. Todavia, os estados limites de utilização desses sistemas estruturais precisam ser analisados, sem sombra de dúvida, de maneira mais criteriosa. Deste modo, no sentido de contribuir para fornecer subsídios aos engenheiros estruturais, no que tange a análise dinâmica de estruturas submetidas a excitações induzidas pelos seres humanos, são desenvolvidos diversos modelos de carregamento representativos do caminhar das pessoas. A variação espacial e temporal da carga dinâmica é considerada ao longo da análise e, bem como, o efeito transiente do impacto do calcanhar humano nos pisos é levado em conta. Assim sendo, são considerados nesta dissertação diversos modelos estruturais associados a pisos mistos (aço-concreto). Técnicas usuais de discretização, com base no emprego do Método dos Elementos Finitos (MEF), via utilização do programa computacional Ansys, são consideradas neste estudo. Uma análise extensa acerca da resposta dinâmica dos pisos é feita, mediante o emprego dos modelos de carregamento desenvolvidos, principalmente, em termos dos valores das acelerações. Na seqüência, os resultados encontrados são comparados com aqueles fornecidos pela literatura técnica disponível sobre o assunto sob o ponto de vista associado ao conforto humano. Investiga-se, também, a influencia da variação de parâmetros estruturais sobre a resposta dinâmica dos modelos, tais como: comprimento vão, taxa de amortecimento, espessura das lajes e, ainda, rigidez das ligações viga coluna. Os resultados obtidos ao longo do estudo indicam, claramente, que os projetistas estruturais devem ser alertados para distorções importantes que ocorrem quando as normas de projeto são utilizadas sem o devido cuidado. Um outro importante diz respeito ao fato de que em diversos pisos analisados observa-se que os critérios de conforto humano não são satisfeitos, demonstrando a importância da consideração dos efeitos dinâmicos provenientes dos seres humanos na análise desse tipo de problema.
Nowadays, the new architectural tendency and the market requirements, are leading structural engineering in the search for bolder solutions, which demands great experience and knowledge of the structural designers associated to the use of new materials and technologies. This philosophy of structural conception is inserted in one of the most important trends of project of the last years that means: the search for structural systems of fast execution, endowed with parts of lower weight and that can be successfully large with a minimum of vertical elements, thus allowing a higher flexibility in the ambients adequacy. On the other hand, this project philosophy has lead to structural elements more and more slender and with natural frequencies much and much lower and, therefore, closer to the frequency of the dynamic excitation associated to the human beings activities, such as: walking, running, jumping, etc. Due to the reasons described in the previous paragraph, the structural engineering systems became sufficiently vulnerable to the effects of vibrations induced by small impacts as it is the case of walking of people on floors, resulting in discomfort to the people. It must be highlighted, also, that such project considerations have fulfilled the required limit states. However, the limit states of use for these structural systems need to be analysed, with no doubt, in a more sensible way. In this way, willing to contribute to supply subsidies to the structural engineers, in the dynamic analysis of structures subject to excitation induced by human beings, several loads models are developed to represent the act of walking. The space and time variation of the dynamic load is considered through the analysis and the transient effect of the impact of the human heel on the floor is taken into consideration, as well. In this way, It is considered in this dissertation, several structural models associated to composite floors (steel-concrete). In this study, it was considered the usual techniques of discretization, based on the Finite Element Method (FEM) using the computer program Ansys. An extensive analysis concerning the dynamic response of the floors is made, by means of the application of the developed load models, mainly, in terms of the values of the accelerations. The results obtained are compared to those supplied by the techinical literature available about the subject with the point of view associated to the human comfort. It is also investigated, the influence of the structural parameter variation on the dynamic response of the models, such as: span length, damping ratio, thickness of the slab and, also, rigidity of the beam columns. The results obtained along the study clearly indicate that the structural designers must be alerted to important distortions that may occur when the project rules are used without the necessary caution. Another important remark is regarded to the fact that in several analysed floors it is observed that the criteria of human comfort are not satisfied which demonstrate the importance of the consideration of the dynamic effect caused by human beings in the analysis of this type of problem.
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Boz, Berk. "Structural Analysis Of Historic Aspendos Theatre." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607115/index.pdf.
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Aspendos Theatre still stands in fairly good condition although it has been constructed about 2200 years ago in Serik village of Antalya, Turkey. Aspendos Theatre is one of the most valuable historical buildings in Turkey. The fact that the structure had overcome numerous possible earthquakes during its lifespan in Antalya and located in second degree earthquake zone, makes the subject an interesting research topic. The earthquake analysis of Aspendos Theatre was conducted using Specification for Structures to be Built in Disaster Areas code and stress levels are investigated using 3D FE modeling. Also, the resonance state of the theatre under sound induced forces due to concerts and exhibitions performed in the theatre has been examined. Structural identification is performed to obtain certain structural characteristics by comparing experimentally measured and analytically obtained natural frequencies. The analytical model is constructed using solid members and the analysis is performed by using SAP2000 software. The elastic modulus of conglomerate used as building blocks in the Theatre is taken as 2350 MPa based on the experimental and analytical studies. The compressive and tensile strength of the theatre wall material is taken as 12 MPa and 1.2 MPa, respectively based on the previous studies conducted on conglomerate. When the maximum stress levels under combined effect of response spectrum and dead load analyses are examined, the level of compressive stress is found to be about 60% of the compressive strength. On the other hand, the tensile stresses developing at upper corners and bottom middle parts of the stage wall and mid-height central location of the exterior wall (on the vicinity of the front door) are calculated to be about 6.6 MPa, which are more than the assumed tensile strength. It has also been calculated that the level of sound that generates tensile failure is about 125 dB as the theatre gets into resonance state.
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Shindo, Nobuhiko. "Structural analysis of thick polypropylene moldings." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10251.
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Campagna, Anne. "Structural analysis of protein interaction networks." Doctoral thesis, Universitat Pompeu Fabra, 2012. http://hdl.handle.net/10803/84111.
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Interactions between proteins give rise to many functions in cells. In the lastdecade, highthroughput experiments have identified thousands of protein interactions, which are often represented together as large protein interaction networks. However, the classical way of representing interaction networks, as nodes and edges, is too limited to take dynamic properties such as compatible and mutually exclusive interactions into account. In this work, we study protein interaction networks using structural information. More specifically, the analysis of protein interfaces in threedimensional protein structures enables us to identify which interfaces are compatible and which are not. Based on this principle, we have implemented a method, which aims at the analysis of protein interaction networks from a structural point of view by (1) predicting possible binary interactions for proteins that have been found in complex experimentally and (2) identifying possible mutually exclusive and compatible complexes. We validated our method by using positive and negative reference sets from literature and set up an assay to benchmark the identification of compatible and mutually exclusive structural interactions. In addition, we reconstructed the protein interaction network associated with the G proteincoupled receptor Rhodopsin and defined related functional submodules by combining interaction data with structural analysis of the network. Besides its established role in vision, our results suggest that Rhodopsin triggers two additional signaling pathways towards (1) cytoskeleton dynamics and (2) vesicular trafficking.Las funciones de las proteínas resultan de la manera con la que interaccionan entre ellas. Los experimentos de alto rendimiento han permitido identificar miles de interacciones de proteínas que forman parte de redes grandes y complejas. En esta tesis, utilizamos la información de estructuras de proteínas para estudiar las redes de interacciones de proteínas. Con esta información, se puede entender como las proteínas interaccionan al nivel molecular y con este conocimiento se puede identificar las interacciones que pueden ocurrir al mismo tiempo de las que están incompatibles. En base a este principio, hemos desarrollado un método que permite estudiar las redes de interacciones de proteínas con un punto de vista mas dinámico de lo que ofrecen clásicamente. Además, al combinar este método con minería de la literatura y Los datos de la proteomica hemos construido la red de interacciones de proteínas asociada con la Rodopsina, un receptor acoplado a proteínas G y hemos identificado sus sub--‐módulos funcionales. Estos análisis surgieron una novel vıa de señalización hacia la regulación del citoesqueleto y el trafico vesicular por Rodopsina, además de su papel establecido en la visión.
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Konarski, Roman. "Sensitivity analysis for structural equation models." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22893.pdf.
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Raghavan, A. K. "Sequence and structural analysis of antibodies." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/15808/.
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The work presented in this thesis focusses on the sequence and structural analysis of antibodies and has fallen into three main areas. First I developed a method to assess how typical an antibody sequence is of the expressed human antibody repertoire. My hypothesis was that the more \humanlike" an antibody sequence is (in other words how typical it is of the expressed human repertoire), the less likely it is to elicit an immune response when used in vivo in humans. In practice, I found that, while the most and least-human sequences generated the lowest and highest anti-antibody reponses in the small available dataset, there was little correlation in between these extremes. Second, I examined the distribution of the packing angles between VH and VL domains of antibodies and whether residues in the interface in uence the packing angle angle. This is an important factor which has essentially been ignored in modelling antibody structures since the packing angle can have a signicant eect on the topography of the combining site. Finding out which interface residues have the greatest in uence is also important in protocols for `humanizing' mouse antibodies to make them more suitable for use in therapy in humans. Third, I developed a method to apply standard Kabat or Chothia numbering schemes to an antibody sequence automatically. In brief, the method uses proles to identify the ends of the framework regions and then lls in the numbers for each section. Benchmarking the performance of this algorithm against annotations in the Kabat database highlighted several errors in the manual annotations in the Kabat database. Based on structural analysis of insertions and deletions in the framework regions of antibodies, I have extended the Chothia numbering scheme to identify the structurally correct positions of insertions and deletions in the framework regions.
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Van, Rooyen G. C. (Gert Cornelis). "Structural analysis in a distributed collaboratory." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53069.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: Structural analysis is examined in order to identify its essential information requirements, its fundamental tasks, and the essential functionalities that applications which support it should provide. The special characteristics of the information content of structural analysis and the algorithms that operate on it are looked into and exploited to devise data structures and utilities that provide proper support of the analysis task within a local environment, while presenting the opportunity to be extended to the context of a distributed network-based collaboratory as well. Aspects regarding the distribution of analysis parameters and methods are analysed and alternatives are evaluated. The extentions required to adapt the local data structures and utilities for use in a distributed communication network are developed and implemented in pilot form. Examples of collaborative analysis are shown, and an evaluation of the overhead involved in distributed work is performed.
AFRIKAANSE OPSOMMING: 'n Ondersoek van die struktuuranalise-taak word uitgevoer waarin die kerninligtingsbehoeftes en fundamentele take daarvan, asook die vereisde funksionaliteit van toepassings wat dit ondersteun bepaal word. Die besondere eienskappe van struktuuranalise-inligting en die algoritmes wat daarop inwerk word ondersoek en benut om data strukture en metodes te ontwikkel wat die analise-taak goed ondersteun in In lokale omgewing, en wat terselfdertyd die moontlikheid bied om sodanig uitgebrei te word dat dit ook die taak in 'n verspreide samewerkingsgroepering kan ondersteun. Aspekte van die verspreiding van analiseparameters en metodes word ondersoek en alternatiewe oplossings word evalueer. Die uitbreidings wat nodig is om die datastrukture en metodes van die lokale omgewing aan te pas vir gebruik in verspreide kommunikasienetwerke word ontwikkel en in loodsvorm toegepas. Voorbeelde van samewerking-gebasseerde analise word getoon, en die oorhoofse koste verbonde aan analise in 'n verdeelde omgewing word evalueer.