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1
Leong, Jonathan Yonghui. "Lubrication and tribological performance optimizations for micro-electro-mechanical systems." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/18067.
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Lubricants and lubrication have been of great interest to mankind since the introduction of machines with sliding/rolling surfaces into everyday life. With the recent trend of miniaturization, Micro-Electro-Mechanical Systems (MEMS) have taken centre stage, featuring components with scales in dimensions as small as nanometres. In this PhD study, two approaches to solving MEMS tribology problems have been pursued. First, a novel direct lubrication method using well-known lubricants such as perfluoropolyether (PFPE) and multiply alkylated cyclopentane (MAC) was developed and tested using reciprocating sliding and actual MEMS tribometry. The second approach utilized the concept of hydrodynamic lubrication and selective surface modification for MEMS. To combat spreading and starvation of lubricants in small contacts such as in MEMS, selective modification of the silicon surface with hydrophobic (non-wetting) and hydrophilic (wetting) portions was carried out and found to increase the force required to move a droplet of lubricant from a designated location on the surface. Octadecylamine and dodecylamine were also used as additives to successfully induce autophobicity in hexadecane, and the various spreading behaviours investigated. In conclusion, several new approaches to tackling tribological problems in MEMS have been researched. These methods are easily adapted to suitable MEMS devices and greatly reduce adhesion and friction, and increase wear and device life by several orders of magnitude.
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Gupta, Sandeep K. (Sandeep Kumar). "Protocol optimizations for the CRL distributed shared memory system." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41004.
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Gorsky, Daniel A. "Niyama Based Taper Optimizations in Steel Alloy Castings." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316191746.
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Smart, Ronald S. "Automated Multidisciplinary Optimizations of Conceptual Rocket Fairings." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/3058.
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The purpose of this research is to develop and architect a preliminary multidisciplinary design optimization (MDO) tool that creates multiple types of generalized rocket fairing models. These models are sized relative to input geometric models and are analyzed and optimized, taking into account the primary objectives, namely the structural, thermal, and aerodynamic aspects of standard rocket flights. A variety of standard nose cone shapes is used as optimization proof of concept examples, being sized and compared to determine optimal choices based on the input specifications, such as the rocket body geometry and the specified trajectory paths. Any input models can be optimized to their respective best nose cone style or optimized to each of the cone styles individually, depending on the desired constraints. Two proof of concept example rocket model studies are included with varying sizes and speeds. Both have been optimized using the processes described to provide delineative instances into how results are improved and time saved. This is done by optimizing shape and thickness of the fairings while ascertaining if the remaining length downstream on the designated rocket model remains within specified stress and temperature ranges. The first optimized example exhibits a region of high stress downstream on the rocket body model that champions how these tools can be used to catch weaknesses and improve the overall integrity of a rocket design. The second example demonstrates how more established rocket designs can decrease their weight and drag through optimization of the fairing design.
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Tonoyan, Arsen V. "Finite element mesh optimization using genetic algorithms." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280756.
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In finite element analysis, structures are modeled as meshes of elements and nodes appropriate for the geometry, boundaries and loading of each structure. Typically, it is desirable to have a mesh which is finer in parts of the structure where stress gradients are high and coarser where such gradients are low. This is usually done by experienced engineers using intuition and previous experience. Otherwise, a fine mesh throughout the structure can be used which results in high computational costs. In this work, the possibility of using genetic algorithms for optimizing finite-element meshes is studied. The method is implemented on a number of simple loaded structures. The meshes used are generated using a number of parameters that can be varied randomly. Then the parameters are varied using operators appropriate to genetic algorithms such that the value of an objective function is minimized within a defined precision and iteration limit. The objective function used in this study is an energy-based error norm. The results obtained with this method are compared to those obtained from a commercial finite element package that incorporates its own mesh optimization algorithms.
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DESHMUKH, DINAR VIVEK. "Design Optimization of Mechanical Components." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1028738547.
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Vijayvargiya, Abhishek. "Multiobjective Optimization of Uncertain Mechanical Systems." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_theses/224.
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This thesis is aimed at the optimum design of uncertain mechanical components and systems involving multiple objectives and constraints. There are various mechanical and design problems that are encountered every now and then which require the output that equalize several conflicting objectives. In recent years several methods have been developed to find a solution to multiobjective problems. The most efficient method for obtaining a compromise solution is the game theory method, which is based on the Pareto minimum or optimum solution. A thorough methodology is developed, and subsequently applied to three examples problems. The first problem is to design four helical springs which are further used to support a milling machine. The objective is to minimize the weight of the spring, also to minimize the deflection, and to maximize the natural frequency thus making the problem as a multiobjective problem. Further the subjected constraint is the shear stress constraint. After finding the optimized solution of the deterministic problem, the problem is again solved using Stochastic Nonlinear Programming, and after that it is solved using Interval Analysis. Game theory is used individually in all the three cases. The second problem is to design a gear box where the objectives are defined as the weight of the gear box, stress developed in the shaft 1, and the stress developed in shaft 2. It is subjected to nine constraints which are bending stress in teeth, contact stress of teeth, transverse displacement of shafts 1 and 2, and constraints related to the torque. The third problem is to design a power screw and the objective is to minimize the volume of the screw, and to maximize the critical buckling load and thus making it a multiobjective problem. It is subjected to constraints of being screw to be self locking, then the shear stress in screw thread, and the bearing stress in threads. The results of all the three problems that are achieved using Deterministic, Stochastic Nonlinear Programming, and Interval Analysis Method are tabulated, and the value of each objective achieved using these three methods for each problem at a time are compared to find out the most optimized solution.
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Lomangino, F. Paul. "Grammar- and optimization-based mechanical packaging." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15848.
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Felden, Luc. "Mechanical optimization of vascular bypass grafts." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04112005-145422/unrestricted/felden%5Fluc%5F200505%5Fmast.pdf.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.David N. Ku, Committee Chair ; Alexander Rachev, Committee Co-Chair ; Elliot L. Chaikof, Committee Member. Includes bibliographical references.
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BONINI, Claudio. "Optimization Techniques Applied to Mechanical Design." Doctoral thesis, Università degli studi di Bergamo, 2014. http://hdl.handle.net/10446/30756.
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The present work deals with the application of optimization techniques to mechanical design. After an initial section devoted to a theoretical review of optimization algorithms in common use, the thesis consists of two parts.
The first part is about the use of the adjoint method in the framework of aerodynamic shape optimization. After a theoretical review, the discrete adjoint method has been implemented in a research code based on the Discontinuous Galerkin (DG) method. This activity represents a new direction of development within the research group operating at University of Bergamo on DG methods for Computational Fluid Dynamics (CFD). Starting from the simple quasi-1D Euler equations, the implementation of the discrete adjoint method has been validated by comparing the values of computed adjoint variables with results of analytical solutions available in the literature. The method has then been applied to a shape optimization problem, using a gradient based algorithm with an inexact line search approach.
The second part of the thesis deals with the application of optimization techniques to an industrial problem. This activity has been carried out at the R&D Centre of TenarisDalmine S.p.A., one of the largest seamless steel pipe producers in the world. This work focuses on the optimization of the thermal cycle of the mandrel of a longitudinal mandrel mill, with the objective of reducing the peak temperature of the mandrel during the rolling phase. The activity for this part of the thesis required the preliminary set up of a number of computational tools for the analysis of the physical aspects involved in the problem. Such tools have then been integrated in a comprehensive optimization approach driven by the optimization tools available in the Optimization Toolbox of the commercial software Matlab. The results of optimization are encouraging, showing the possibility of a considerable increase of the mandrel life cycle.
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Massicotte, Paul. "Dynamic optimization of job allocation using constant job-mix stages and priority factors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37271.pdf.
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Kostic, Peter. "New methods for optimization of mechanical ventilation." Doctoral thesis, Uppsala universitet, Anestesiologi och intensivvård, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-249172.
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Mechanical ventilation saves lives, but it is an intervention fraught with the potential for serious complications. Prevention of these complications has become the focus of research and critical care in the last twenty years. This thesis presents the first use, or the application under new conditions, of three technologies that could contribute to optimization of mechanical ventilation. Optoelectronic plethysmography was used in Papers I and II for continuous assessment of changes in chest wall volume, configuration, and motion in the perioperative period. A forced oscillation technique (FOT) was used in Paper III to evaluate a novel positive end-expiratory pressure (PEEP) optimization strategy. Finally, in Paper IV, FOT in conjunction with an optical sensor based on a self-mixing laser interferometer (LIR) was used to study the oscillatory mechanics of the respiratory system and to measure the chest wall displacement. In Paper I, propofol anesthesia decreased end-expiratory chest wall volume (VeeCW) during induction, with a more pronounced effect on the abdominal compartment than on the rib cage. The main novel findings were an increased relative contribution of the rib cage to ventilation after induction of anesthesia, and the fact that the rib cage initiates post-apneic ventilation. In Paper II, a combination of recruitment maneuvers, PEEP, and reduced fraction of inspired oxygen, was found to preserve lung volume during and after anesthesia. Furthermore, the decrease in VeeCW during emergence from anesthesia, associated with activation of the expiratory muscles, suggested that active expiration may contribute to decreased functional residual capacity, during emergence from anesthesia. In the lavage model of lung injury studied in Paper III, a PEEP optimization strategy based on maximizing oscillatory reactance measured by FOT resulted in improved lung mechanics, increased oxygenation, and reduced histopathologic evidence of ventilator-induced lung injury. Paper IV showed that it is possible to apply both FOT and LIR simultaneously in various conditions ranging from awake quiet breathing to general anesthesia with controlled mechanical ventilation. In the case of LIR, an impedance map representing different regions of the chest wall showed reproducible changes during the different stages that suggested a high sensitivity of the LIR-based measurements.
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Hansen, Matthew Martin Kenneth. "Optimization of Conformal Joints in Axial Tension." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1355847865.
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Olliges, Sven. "Mechanical properties & microstructure optimization of gold nanowires /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17555.
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Filomeno, Coelho Rajan. "Multicriteria optimization with expert rules for mechanical design." Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211184.
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Though lots of numerical methods have been proposed in the literature to optimize me-chanical structures at the final stage of the design process, few designers use these tools since the first stage. However, a minor modification at the first step can bring significant change to the global performances of the structure. Usually, during the initial stage, models are based on theoretical and empirical equations, which are often characterized by mixed variables: continuous (e.g. geometrical dimensions), discrete (e.g. the cross section of a beam available in a catalogue) and/or integer (e.g. the number of layers in a composite material). Furthermore, the functions involved may be non differentiable, or even discontinuous. Therefore, classical algorithms based on the computation of sensi-tivities are no more applicable. Consequently, to solve these problems, the most wide-spread meta-heuristic methods are evolutionary algorithms (EAs), which work as follows: the best individuals among an initial population of randomly generated potential solutions are favoured and com-bined (by specific operators like crossover and mutation) in order to create potentially better individuals at the next generation. The creation of new generations is repeated till the convergence is reached. The ability of EAs to explore widely the design space is useful to solve single-objective unconstrained optimization problems, because it gener-ally prevents from getting trapped into a local optimum, but it is also well known that they do not perform very efficiently in the presence of constraints. Furthermore, in many industrial applications, multiple objectives are pursued together.
Therefore, to take into account the constrained and multicriteria aspects of optimization problems in EAs, a new method called PAMUC (Preferences Applied to MUltiobjectiv-ity and Constraints) has been proposed in this dissertation. First the user has to assign weights to the m objectives. Then, an additional objective function is built by linearly aggregating the normalized constraints. Finally, a multicriteria decision aid method, PROMETHEE II, is used in order to rank the individuals of the population following the m+1 objectives.
PAMUC has been validated on standard multiobjective test cases, as well as on the pa-rametrical optimization of the purge valve and the feed valve of the Vinci engine, both designed by Techspace Aero for launcher Ariane 5.
\
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
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Chan, Cameron D. "MECHANICAL OPTIMIZATION AND BUCKLING ANALYSIS OF BIO-COMPOSITES." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/877.
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Today’s environmental concerns have led a renewed search in industry to find new sustainable materials to replace non-renewable resources. President Barack Obama also quoted in the recent 2012 Presidential Debate “that there is a need to build the energy sources of the future and invest in solar, wind, and bio-fuels.” Bio-composites are believed to be the future and the new substitute for non-renewable resources. Bio-composites are similar to composites in that they are made up of two constituent materials; however the main difference is that bio-composites are made from natural fibers and a biopolymer matrix. This research investigates the buckling behavior of bamboo and will analyze and determine the slender ratio that will induce buckling when bamboo is used as a column. Along with the investigation of the bamboo under buckling, this study will also show the potential of bio-composites to replace non-renewable resources in industry through experimental and numerical analysis. However, in order to study the buckling behavior of the bamboo, the mechanical characteristics of the bamboo and optimal curing treatment first had to be established. This is because, in order for bamboo to acquire proper strength characteristics, the bamboo must first be treated.
Due to the scarcity of bamboo material in the lab, the obtainment of the mechanical properties of the bamboo as well as the optimal curing treatment was done in collaboration with Jay Lopez. In order for bamboo to acquire proper strength characteristics, the bamboo must be treated. In the first study, a total of four different types of natural treatments were analyzed to optimize the mechanical characteristics of bamboo. To assess each curing method, tensile and compression tests were performed to obtain the mechanical properties. Due to each bamboo culm having different thicknesses and cross sections, the specific strength property is used to normalize the data and allow for easy comparison and assessing of each curing method equally. The specific strength parameter is defined as the ultimate stress divided by the density of the material. These curing treatments consisted of four thermo-treatments, three different percentages of salt treatments, one lime treatment, and one oil treatment. The thermo-treatments consisted of heating the bamboo internodes in an autoclave with no pressure at 150oF, 180°F, 200°F, and 220°F. The experimental results of the thermo-treatments determined that bamboo obtains higher mechanical properties as well as reduced weight when heated at higher temperatures. This is explained by the increasing bound water extracted from the bamboo material at higher temperatures. In addition to finding the optimal heat treatment, the internodes of bamboo were soaked in natural additives that included a 3%, 6%, and 9% Instant Ocean sea salt solution, a Bonide hydrated lime solution, and a Kirkland canola oil solution for approximately five days and then heat treated at the optimal temperature of 220°F. The experimental results showed that all of the different additives had a significant effect on the mechanical properties.
After determining the mechanical properties of each curing method, the results were then analyzed through a trade study. The trade study parameters consisted of weight-drop of the material, the specific strength, and the ultimate stress for both compression and tension. Each parameter of the trade study is kept unbiased as the weighting of each parameter is set equal to each other. The results of the trade study indicated that the 3% salt solution was the optimal curing treatment, yielding a higher specific strength value for both compression and tension, along with a significantly lower weight-drop after curing.
After we came up with the optimal treatment, the buckling behavior of bamboo was investigated. The buckling analysis was investigated to determine at what slenderness ratio the bamboo would buckle when used as a column. A total of seven cases were investigated using different lengths, that ranged from 1.5” to 10”. Through experimental results, it was determined that a slenderness ratio above approximately 34.7 would induce global buckling to the bamboo column.
The last investigation of this study consisted of building a small prototype wall structure using bio-composites. The prototype wall structure was manufactured using a combination of bamboo and a bi-directional woven hemp fabric. The dimensions of the prototype were 15.13” long and 7.75” tall. The wall structure was tested under compression in the Aerospace Structures/Composites Lab and the Architectural Engineering Department’s high bay laboratory. The results of the experimental test on the wall showed great potential for bio-composites, as the structure withstood a force of 46,800 pounds.
A numerical analysis technique was also employed through the finite element method using the Abaqus software. The purpose of the finite element method was to validate the experimental results by comparing the buckling behavior of the tests. The numerical analysis showed very good agreement with the experimental results.
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Pasquotti, Maura. "Topics on Optimization Strategies for Constrained Mechanical Systems." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425582.
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In the first part of the work we analyze the problem of optimal control of a vehicle along a preassigned trajectory. The vehicle system is studied and simplified in order to obtain a computationally tractable model, which still presents the main characteristics of the real vehicle. The control algorithm, based on MPC techniques, is then explained and its effectiveness is proved through simulation results. The “minimum lap time problem” is afterward considered, which can be considered as an evolution of the trajectory tracking problem; its analysis is presented and is followed by the developed solution, based on pseudospectral methods.
In the second part of the thesis the problem of control of underactuated mechanical systems is discussed. The nonholonomic system classically called “rolling disk” is considered as test case; it is a wheel with punctiform contact surface that can roll on the plane without sliding laterally. Differently from the literature we consider the torque as the unique control input signal. This system is modeled through the Lagrangian formalism and then the control strategy, based on backstepping and receding horizon techniques, is shown and proved to be effective.
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Hillberg, Alexander, and Marcus Olmarker. "Optimization of Flexplate." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-37051.
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From 2019, all new Volvo Powertrains will be electrified, also including ICE based Powertrains. In the ICE based Powertrains with automatic transmission, a flexplate is connecting the crank shaft to the automatic transmission to transfer the power. The flexplate needs to handle torque peaks from the combustion, crank shaft whirl and axial forces generated by the torque converter. The combustion torque load is maximized at every ignition, but the load is also dependent on engine speed/load and gearbox shifts. All these loads applied to the flexplate means that the plate will be exposed to high stress levels. These high levels of stress make the flexplate more likely to break and thus, shorten its lifespan. Therefore, the objective of this thesis was to generate new optimized design proposals of the plate with minimized stress levels using the method Simulation Driven Design. Also, to understand the result, a parametrical study was performed using Design of Experiments. Using Simulation Driven Design, several concepts were generated but only two showed valid results, and they were optimized using parametrical optimization and Design of Experiments in Catia V5. Also, an attempt at a topological optimization was performed in Inspire, but the model was to complex and could not be accurately replicated in the program, making the topological optimization impossible to do. With a combination of parametrical optimization and Design of Experiments, the two concepts showed a reduced stress level of 16.4% and 11.1% compared to the original design. They also showed an increase in deformation and a slight decrease in weight. Knowing this, a conclusion could be made that Simulation Driven Design is a great method to use in product development. The results show that the combination of parametrical optimization and Design of Experiments can be used efficient during the optimization process in product development.Från 2019 kommer alla nya drivlinor från Volvo att elektrifieras, även inkluderat förbränningsmotorbaserade drivlinor. I de förbränningsmotorbaserade drivlinorna med automatisk växellåda så fäster en medbringarplåt samman vevaxeln med den automatiska växellådan för att överföra kraften. Medbringarplåten måste hantera vridmomentstoppar från vevaxeln vid förbränningen, vevaxelrotation och axiella krafter generade av momentöverföraren. Vridmomentslasten vid förbränningen är maximerad vid varje tändning, men lasten är även beroende på motorns hastighet/last och på växlingar. Alla dessa laster som medbringarplåten utsätts för innebär att plåten kommer påverkas av höga spänningsnivåer. Dessa höga spänningsnivåer gör det mer sannolikt att medbringarplåten går sönder och därav förkortas livslängden. Därför var målet med denna avhandling att generera nya optimerade designkoncept på plåten med minimerade spänningsnivåer genom att använda metoden Simulation Driven Design. För att förstå resultatet, genomfördes även en parameterstudie med hjälp av Design of Experiments. Genom att använda Simulation Driven Design så kunde flera designkoncept tas fram, men endast två visade på hållbara resultat, och de optimerades med parametrisk optimering samt Design of Experiments i Catia V5. En topologisk optimering i programmet Inspire försöktes även, men modellen var för komplicerad och kunde inte återskapas på ett noggrant sätt i programmet, vilket gjorde att optimeringen var omöjlig att göra. Med en kombination av parametrisk optimering och Design of Experiments visade de två koncepten en minskning i spänning på 16,4% och 11,1% jämfört med originaldesignen. De visade även en ökning i deformation samt en liten minskning i vikt. Resultatet visar att det är möjligt att dra slutsatsen att Simulation Driven Design är en fantastisk metod att använda i produktutveckling. Resultatet visar även att kombinationen av parametrisk optimering och Design of Experiments kan användas effektivt under optimeringsprocessen i produktutveckling
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Liu, Zheng 1962. "Kinematic optimization of linkages." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39742.
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Presented in this thesis are novel methodologies for the analysis and optimization of planar, spherical, and spatial linkages associated with the problems of function generation, path generation, and rigid-body guidance. An up-to-date literature survey in the area of mechanism optimization is also provided in the thesis.Both the input-output (I/O) equation and the I/O curve are employed in the input-output analysis of four-bar linkages. Based on these, the properties of a special class of linkage, the constant-branch linkage, as well as its engineering application are discussed. Two schemes are developed for the optimization of function-generating linkages, namely, a constrained least-square procedure using slack variables and an unconstrained method based on I/O curve planning. The issue of data-conditioning is also discussed so that singularities can be avoided in the optimization procedure.
With the help of linkage coordinate systems defined in this thesis, equations governing the coupler-link motion are derived for both path generation and rigid-body guidance. In the optimization of path-generating and rigid-body guiding linkages, a two-loop scheme based on a constrained least-square procedure is first proposed. Then, as an extension to I/O curve planning in function generation, a method resorting to input-output-coupler (I/O-C) curve planning is developed for path generation and rigid-body guidance. Using unconstrained approaches, this method simplifies the optimization procedure to a great extent.
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Chiloyan, Vazrik. "Polyethylene fiber drawing optimization." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68829.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011."June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 33).
Polymer fiber drawing creates fibers with enhanced thermal conductivity and strength compared to bulk polymer because drawing aligns the molecular chains. I optimize the polymer fiber drawing method in order to achieve polymer fibers that are drawn to lengths exceeding 1cm and develop a method to cut and store them for future experimental purposes. With lengths exceeding 1cm, starting with lengths near 0.5mm, these fibers undergo very large tensile deformations. This ensures the fibers obtained have been ultra drawn, and the polymer chains have aligned, thus enhancing the tensile strength and thermal conductivity of the fiber. By storing these fibers, I can perform experimental measurements in the future to obtain thermal conductivity values for polyethylene fibers and notice the effect of aligning the molecular chains.
by Vazrik Chiloyan.
S.B.
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Mansouri, Ahmad, and David Norman. "Strategy Development of Structural Optimization in Design Processes." Thesis, Linköping University, Linköping University, Department of Management and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17418.
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This thesis aims toward developing strategies in the area of structural optimization and to implement these strategies in design processes. At
GM Powertrain Sweden where powertrains are designed and developed, two designs of a differential housing have been chosen for this thesis. The main tasks have been to perform a topology optimization of a model early in a design process, and a shape optimization on a model late in a design process. In addition the shape optimization strategies have also been applied on a fork shifter. This thesis covers the theory of different optimization strategies in general. The optimization processes are explained in detail and the results from the structural optimization of the differential housings as well as the fork shifter are shown and evaluated. The evaluation of the thesis provides enough arguments to suggest an implementation of the optimization strategies in design processes at GM Powertrain
. A Structural Optimization group has great potential of closing the gap between structural designers and structural analysis engineers which in long terms mean that better structures can be developed in less time. To be competitive in the automotive industry these are two of the most important factors for being successful.
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Urbina, Raul. "Optimization of a Multi-Aixs Electro-Mechanical Scanning System." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/UrbinaR2001.pdf.
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Zhao, Jian-Hua. "The reliability optimization of mechanical systems using metaheuristic approach." Mémoire, École de technologie supérieure, 2005. http://espace.etsmtl.ca/326/1/ZHAO_Jian%2DHua.pdf.
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Le problème d'optimisation de fiabilité des systèmes mécaniques est un problème compliqué avec contraintes multicritères, dont la solution optimale est en générale un compromis. Le travail présenté dans ce mémoire se concentre sur l'optimisation de fiabilité des systèmes mécaniques en séries parallèles. Basée sur le ACSRAP (Ant Colony System for Redundancy Apportionment Problem), une nouvelle approche est présentée. Cette approche combine les caractéristiques de l'ACS avec des recherches locales. Donc il optimise la fiabilité globale du système tout en satisfaisant les contraintes en terme de coût, de poids et de volume. Les avantages sur la précision, l'efficacité, et la capacité de la nouvelle approche sont illustrés par les résultats de comparaison de là nouvelle technique avec ceux obtenues par d'autres approches. En outre, l'application de la technique sur une boite de transmission (Gear Train System) est aussi présenté pour montrer les procédures de l'application de la nouvelle technique sur les cas réels.
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Albertson, Nicholas James. "Mechanical and Electromagnetic Optimization of Structurally Embedded Waveguide Antennas." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/81959.
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Use of Slotted Waveguide Antenna Stiffened Structures (SWASS) in future commercial and military aircraft calls for the development of an airworthiness certification procedure. The first step of this procedure is to provide a computationally low-cost method for modeling waveguide antenna arrays on the scale of an aircraft skin panel using a multi-fidelity model. Weather detection radar for the Northrop Grumman X-47 unmanned air system is considered as a case study. COMSOL Multiphysics is used for creating high-fidelity waveguide models that are imported into the MATLAB Phased Array Toolbox for large-scale array calculations using a superposition method. Verification test cases show that this method is viable for relatively accurate modeling of large SWASS arrays with low computational effort. Additionally, realistic material properties for carbon fiber reinforced plastic (CFRP) are used to create a more accurate model. Optimization is performed on a 12-slot CFRP waveguide to determine the waveguide dimensions for the maximum far-field gain and separately for the maximum critical buckling load. Using the two separate optima as utopia points, a multi-objective optimization for the peak far-field gain and critical buckling load is performed, to obtain a balance between EM performance and structural strength. This optimized waveguide is then used to create a SWASS array of approximately the same size as an aircraft wing panel using the multi-fidelity modeling method that is proposed. This model is compared to a typical conventional weather radar system, and found to be well above the minimum mission requirements.Master of Science
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Erb, Dylan C. (Dylan Charles). "Optimization of blended battery packs." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81601.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 87-91).
This thesis reviews the traditional battery pack design process for hybrid and electric vehicles, and presents a dynamic programming (DP) based algorithm that eases the process of cell selection and pack design, especially for blended battery packs (those containing two or more different energy sources). The proposed algorithm simultaneously optimizes the size of the battery pack while determining the ideal control strategy for the power split between the two sources. To test the algorithm, a simulation experiment is presented that compares the results of the DP based algorithm with single energy source options and a peak shaving heuristic strategy. The results of this experiment show that the algorithm reliably picks the lowest cost solution, and illustrates that blended battery packs have great potential for cost reduction in hybrid vehicles.
by Dylan C. Erb.
S.M.
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Schlenker, Aaron Paul. "Integrated optimization of thermoelectric systems." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127119.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 99-103).
Thermoelectric devices present unique opportunities for sustainable energy conversion. While research efforts have remarkably improved material capabilities over the past several decades, material advancement alone is insufficient to realize the full potential of thermoelectric technology [25, 24, 39, 14]. Here, an integrated perspective is applied to thermoelectric technology to identify potential system improvements. The traditional thermoelectric architecture is dissected to identify limitations. It is found that the coupling of the device height to the thermoelectric element height imposed by the architecture can significantly hinder performance. A novel distributed architecture, which de-couples the device and element heights, is theorized to address these limitations. A modeling program incorporating device parameters and external conditions is developed to simulate and optimize the system architecture. The new architecture is shown to out-perform the traditional architecture in both a broad range of general generation and refrigeration conditions and the specific application of a phase-change material thermoelectric generator. The results signal the importance and potential value of an integrated approach to thermoelectric system design.
by Aaron Paul Schlenker.
S.M.
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Borrvall, Thomas. "Computational topology optimization in continuum mechanics /." Linköping : Univ, 2002. http://www.bibl.liu.se/liupubl/disp/disp2002/tek744s.pdf.
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Soto, Jonathan. "Nonlinear contraction tools for constrained optimization." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62538.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-78).
This thesis derives new results linking nonlinear contraction analysis, a recent stability theory for nonlinear systems, and constrained optimization theory. Although dynamic systems and optimization are both areas that have been extensively studied [21], few results have been achieved in this direction because strong enough tools for dynamic systems were not available. Contraction analysis provides the necessary mathematical background. Based on an operator that projects the speed of the system on the tangent space of the constraints, we derive generalizations of Lagrange parameters. After presenting some initial examples that show the relations between contraction and optimization, we derive a contraction theorem for nonlinear systems with equality constraints. The method is applied to examples in differential geometry and biological systems. A new physical interpretation of Lagrange parameters is provided. In the autonomous case, we derive a new algorithm to solve minimization problems. Next, we state a contraction theorem for nonlinear systems with inequality constraints. In the autonomous case, the algorithm solves minimization problems very fast compared to standard algorithms. Finally, we state another contraction theorem for nonlinear systems with time-varying equality constraints. A new generalization of time varying Lagrange parameters is given. In the autonomous case, we provide a solution for a new class of optimization problems, minimization with time-varying constraints.
by Jonathan Soto.
S.M.
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Jain, Ruchi V. "Optimization of energy parameters in buildings." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40445.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 34).
When designing buildings, energy analysis is typically done after construction has been completed, but making the design decisions while keeping energy efficiency in mind, is one way to make energy-efficient buildings. The conscious design of building parameters could decrease or completely eliminate the need for Heating, Ventilation and Air Conditioning systems, and thus, optimizing building parameters could help conserve a great amount of energy. This work focuses on two buildings - a passive solar house and an apartment in Beijing. The Beijing apartment is used to study natural ventilation in a space. Both buildings are modeled using EnergyPlus, and analyzed using VBA in Excel. The Genetic Algorithm Optimization Toolbox (GAOT) is used to optimize the parameters for the solar house. The program was run for 150 generations, with there being 20 individuals in each population. The optimized parameters for the solar house resulted in a mean internal temperature of 20.1 C, 7 C lower than that for randomly chosen parameters. The extreme temperatures in both cases were also markedly different, with the optimized parameters providing a more comfortable atmosphere in the house.
(cont.) The apartment parameters were not optimized due to the inherent difficulty in quantifying an objective function. Through the simulation however, it was determined that each window has mass inflow and outflow occurring at the same time. In order to check that mass was conserved through the flow of air in and out of the apartment, the net flow in or out through each window had to be considered. This comparison did show the conservation of mass, which provided confidence in the EnergyPlus model used.
by Ruchi V. Jain.
S.B.
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Piazzarolo, Bruno Aiala. "Design optimization of oxygenated fluid pump." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75673.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 66).
In medical emergencies, an oxygen-starved brain quickly suffers irreparable damage. In many cases, patients who stop breathing can be resuscitated but suffer from brain damage. Dr. John Kheir from Boston Children's Hospital created a compressible fluid that can re-oxygenate blood quickly in patients with asphyxia and cardiac arrest. Because the fluid is compressible, the set infusion rate on an ordinary pump does not necessarily indicate what is delivered. In addition, the fluid is provided at a 90% gas by volume concentration and is extremely viscous. The goal of this project is to create a pump to deliver a specified volumetric flow rate of the oxygenated fluid created by the doctor. The pump design uses a bellows with force feedback calibration to pump 1 liter of fluid over 5 minutes and mix the concentrated 90% form with saline without degradation to form a 70% concentrated form with the viscosity similar to that of blood. My part in the project was to create the control system that would drive the pump using a force feedback and to optimize the design of the pump The oxygenated fluid pump built can successfully store and dispense one liter of fluid, mix the concentrated form of the oxygenated fluid with saline, maintain sterility, and preserve the fluid's properties, all in a cost appropriate manner. It is a modular design that can easily be modified to improve its performance. Further testing is required to tune the control system and ensure that the flow rate is accurate to ±10%. The pump is mostly being used as a research tool in order to run tests that will help characterize the fluid and later can be used for small and large animal testing.
by Bruno Aiala Piazzarolo.
S.B.
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Taylor, Joshua Adam. "Conic optimization of electric power systems." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67601.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-115).
The electric power grid is recognized as an essential modern infrastructure that poses numerous canonical design and operational problems. Perhaps most critically, the inherently large scale of the power grid and similar systems necessitates fast algorithms. A particular complication distinguishing problems in power systems from those arising in other large infrastructures is the mathematical description of alternating current power flow: it is nonconvex, and thus excludes power systems from many frameworks benefiting from theoretically and practically efficient algorithms. However, advances over the past twenty years in optimization have led to broader classes possessing such algorithms, as well as procedures for transferring nonconvex problem to these classes. In this thesis, we approximate difficult problems in power systems with tractable, conic programs. First, we formulate a new type of NP-hard graph cut arising from undirected multicommodity flow networks. An eigenvalue bound in the form of the Cheeger inequality is proven, which serves as a starting point for deriving semidefinite relaxations. We next apply a lift-and-project type relaxation to transmission system planning. The approach unifies and improves upon existing models based on the DC power flow approximation, and yields new mixed-integer linear, second-order cone, and semidefinite models for the AC case. The AC models are particularly applicable to scenarios in which the DC approximation is not justified, such as the all-electric ship. Lastly, we consider distribution system reconfiguration. By making physically motivated simplifications to the DistFlow equations, we obtain mixed-integer quadratic, quadratically constrained, and second-order cone formulations, which are accurate and efficient enough for near-optimal, real-time application. We test each model on standard benchmark problems, as well as a new benchmark abstracted from a notional shipboard power system. The models accurately approximate the original formulations, while demonstrating the scalability required for application to realistic systems. Collectively, the models provide tangible new tradeoffs between computational efficiency and accuracy for fundamental problems in power systems.
by Joshua Adam Taylor.
Ph.D.
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Ebeling, A. (Andreas). "Cost optimization for wear resistant components." Master's thesis, University of Oulu, 2013. http://urn.fi/URN:NBN:fi:oulu-201308291655.
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The goal of this thesis was to give a cost view on wear and how to optimize components cost-wise taking operating conditions into consideration, but later it was decided not to limit the focus only to wear resistant applications. The thesis was made for Componenta as a part of HICON project, which studies high friction and low wear contacts. HICON is a subproject of DEMAPP under Finnish consortium company FIMECC Oy, Finnish Metals and Engineering Competence Cluster. The work was done studying books and articles; having conversations in Componenta, HICON, and customers of the case examples; studying the results of the case examples; and evaluating the process in general. Five step material selection process was developed from which four are consecutive steps: finding out customer demands, preselection of materials, House of Quality (HOQ) and decision matrix; and one process long step: life cycle costing. HOQ, which is the first step of Quality Function Deployment (QFD), was used in order to find out which material properties are the most important and to get more objective weightings to decision matrix. Decision matrix is the fourth step to get a guiding suggestion for the optimized material. Life cycle costing was decided to separate as an independent process long step, because of its high importance in cost optimization. It should guide decisions throughout the process. Four wear related case examples were studied from actual customers of Componenta: sheave-wire contact, wear plate in a coupling, feed roller in a forestry machine, and wear plate in a concrete pump. It was found out that there are very promising aspects in this process, but the process is only guiding and the results shouldn’t be taken with certainty. Especially the life cycle costing step was found to be very promising, because when it is kept in mind throughout the process there can be found out significant savings in life cycle costs (LCC). For example in light trucks the significance of weight is approximately $12/kg or according to simple calculations made at Componenta 7 €/kg in life cycle costs. HOQ seems on the other hand very difficult to apply in deciding correlations between customer demands and material properties, and it’s very difficult to estimate the accuracy of its results. Decision matrix seems simpler and easier to understand, but it is only guiding. It is difficult to estimate the efficiency of the process based on four case examples, but it is customer oriented approach with the focus on life cycle costing, so if the process is used selectively with the parts that work best for the company, it could be useful. The process could probably be used with mild changes in many other applications as well, and the applicability could be even betterTyön tavoitteena oli tutkia komponenttien optimointia kulumisen ja kustannusten kannalta ottaen huomioon käyttöolosuhteet. Myöhemmin päädyttiin siihen, ettei työtä rajoiteta ainoastaan kulumiskestäviin sovelluksiin. Työ tehtiin Componentalle HICON projektin alaisuudessa, joka tutkii kontaktien korkeaa kitkaa ja vähäistä kulumista. HICON on DEMAPP’in alaprojekti suomalaisen konsortioyrityksen FIMECC Oy:n, Finnish Metals and Engineering Competence Cluster, alaisuudessa. Työ tehtiin tutkimalla kirjoja ja artikkeleita; keskustelemalla Componentalla sekä HICON-yritysten ja asiakkaiden kanssa, joilta tapausesimerkit saatiin; ja arvioimalla prosessia yleisesti. Viisivaiheinen materiaalinvalintaprosessi kehitettiin, joista neljä vaihetta on peräkkäisiä: asiakasvaatimusten selvittäminen, materiaalin esivalinta, laatutalo ja päätösmatriisi; ja yksi koko prosessin pituinen vaihe: elinkaarikustannusten arviointi. Laatutaloa, joka on Quality Function Deploymentin (QFD) ensimmäinen vaihe, käytettiin tärkeimpien materiaaliominaisuuksien selvittämiseen ja saadakseen objektiivisemmat painokertoimet päätösmatriisiin. Päätösmatriisi on neljäs vaihe, jolla saadaan ohjaavat ehdotukset materiaalin optimointiin. Elinkaarikustannusten arviointi päätettiin erotella erilliseksi prosessin mittaiseksi vaiheeksi, koska se on niin tärkeä kustannusten optimoinnin kannalta. Sen pitäisi ohjata päätöksiä koko prosessin ajan. Neljä kulumiseen liittyvää Componentan asiakkailta saatua tapausesimerkkiä tutkittiin: vetopyörä ja vaijerin kontakti, vetokidan kulutuslevy, metsäkoneen syöttörulla ja betonipumpun kulutuslevy. Prosessissa havaittiin olevan monta lupaavaa piirrettä, mutta se on ainoastaan ohjaava ja tuloksia ei pitäisi ottaa ehdottomasti. Erityisesti elinkaarikustannusten arviointivaihe havaittiin erittäin lupaavaksi, koska pitäessä sitä mielessä koko prosessin ajan voi löytyä merkittäviä säästöjä elinkaarikustannuksissa. Esimerkiksi kevyissä kuorma-autoissa massan merkitys elinkaarikustannuksissa on suurin piirtein $12/kg tai Componetalla tehtyjen yksinkertaisten laskujen mukaan 7 €/kg. Laatutalo taas vaikuttaa todella vaikealta soveltaa korrelaatioiden määrittämisen asiakasvaatimusten ja materiaaliominaisuuksien välillä, ja on todella vaikea arvioida tulosten tarkkuutta. Päätösmatriisi vaikuttaa yksinkertaisemmalta ja helpommalta ymmärtää, mutta se on ainoastaan ohjaava. On vaikea arvioida prosessin tehokkuutta perustuen neljään esimerkkitapaukseen, mutta kyseessä on asiakaslähtöinen lähestymistapa, jossa keskittyminen on elinkaarikustannuksissa. Jos prosessia käytetään valikoivasti valikoiden ne osat, jotka soveltuvat yritykseen parhaiten, se voi olla hyödyllinen. Prosessia voisi luultavasti käyttää myös muihin sovelluksiin pienten muutosten jälkeen ja sen soveltuvuus voisi olla jopa parempi
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Mardia, Rishab. "Financial analysis in multidisciplinary design optimization." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130719.
Full textAbstract:
Thesis: M. Eng. in Advanced Manufacturing and Design, Massachusetts Institute of Technology, Department of Mechanical Engineering, February, 2021Cataloged from the official PDF of thesis. "February 2021."
Includes bibliographical references (pages 57-58).
MDO is moving beyond the small group of NASA and Aerospace companies and is increasingly being adopted by organizations around the world. With MDO, we can optimize across multiple disciplines and find the ideal design which maximizes benefit to the company and society. Given the complexity of working with multiple disciplines and stakeholders, it is important to have a single metric which teams and organizations can use to choose the best design. Since financial metrics play a dominant role in the decision-making process, we can use them to choose the best design for the company. In the thesis, we created a framework for doing financial analysis in MDO. We applied the framework to the baseplate, a component used within the excavator pump, and optimized across three different disciplines of cost, natural frequency and temperature to find the baseplate design with the highest sales potential.
We focused on sales as it is the most important financial metric for the product, but a similar framework can be used for maximizing profit, NPV, IRR or any other financial metric. We used two approaches for finding the best design for the company. In the first approach, we found designs which minimized cost and temperature, while increasing the natural frequency. We then converted the cost and temperature data into sales and chose the design with most sales. In the second approach, we only set one objective of maximizing sales and chose the design with the highest sales. In both the approaches we were able to significantly increase sales. We would recommend approach 1 as we get higher sales with the method, and because of limitations within the optimization software OptiSLang in regards to implementing approach 2. Approach 2 might become the better option in the coming years as MDO software, including OptiSLang, is in the early stage and might significantly improve.
Approach 2 also has the advantage of MDO teams only setting one objective, helping establish consistency and uniformity in MDO implementation. We believe MDO has a lot of potential. Similar to CAD, it is an extremely powerful tool. Some of the challenges to successful implementation were: computational resources, high quality and reliable financial data and early stage MDO software. Organizations which implement MDO will create better products which maximize savings and financial benefit.
by Rishab Mardia.
M. Eng. in Advanced Manufacturing and Design
M.Eng.inAdvancedManufacturingandDesign Massachusetts Institute of Technology, Department of Mechanical Engineering
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Salsbery, Scott. "Dynamic optimization of district energy grid." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3525.
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The University of Iowa Power Plant operates utility generation and distribution for campus facilities, including electricity, steam, and chilled water. It is desirable to evaluate the optimal load combination of boilers, engines and chillers to meet the demand at minimal cost, particularly for future demand scenarios. An algorithm has been developed which takes into account the performance of individual units as part of the mix which ultimately supplies the campus and determine the degree that each should be operating to most efficiently meet demand. The algorithm is part of an integrated simulation tool which is specifically designed to apply traditional optimization techniques for a given (both current and possible) circumstance. The second component is to couple the algorithm with accurate estimates and historical data through which expected demand could be predicted. The simulation tool can account for any theoretical circumstance, which will be highly beneficial for strategic planning. As part of the process it is also necessary to determine the unique operating characteristics of the system components. The algorithms rely upon performance curves of individual system components (boiler, chiller, etc.) and those must be developed and refined when possible from experimental testing and commissioning or manufacturer supplied data.
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Pajot, Joseph M. "Topology optimization of geometrically nonlinear structures including thermo-mechanical coupling." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219000.
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Corner, Sebastien Marc. "Modeling, Sensitivity Analysis, and Optimization of Hybrid, Constrained Mechanical Systems." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82713.
Full textAbstract:
This dissertation provides a complete mathematical framework to compute the sensitivities with respect to system parameters for any second order hybrid Ordinary Differential Equation (ODE) and rank 1 and 3 Differential Algebraic Equation (DAE) systems.
The hybrid system is characterized by discontinuities in the velocity state variables due to an impulsive forces at the time of event. At the time of event, such system may also exhibit a change in the equations of motion or in the kinematic constraints.
The analytical methodology that solves the sensitivities for hybrid systems is structured based on jumping conditions for both, the velocity state variables and the sensitivities matrix. The proposed analytical approach is then benchmarked against a known numerical method.
The mathematical framework is extended to compute sensitivities of the states of the model and of the general cost functionals with respect to model parameters for both, unconstrained and constrained, hybrid mechanical systems.
This dissertation emphasizes the penalty formulation for modeling constrained mechanical systems since this formalism has the advantage that it incorporates the kinematic constraints inside the equation of motion, thus easing the numerical integration, works well with redundant constraints, and avoids kinematic bifurcations.
In addition, this dissertation provides a unified mathematical framework for performing the direct and the adjoint sensitivity analysis for general hybrid systems associated with general cost functions. The mathematical framework computes the jump sensitivity matrix of the direct sensitivities which is found by computing the Jacobian of the jump conditions with respect to sensitivities right before the event. The main idea is then to obtain the transpose of the jump sensitivity matrix to compute the jump conditions for the adjoint sensitivities.
Finally, the methodology developed obtains the sensitivity matrix of cost functions with respect to parameters for general hybrid ODE systems. Such matrix is a key result for design analysis as it provides the parameters that affect the given cost functions the most. Such results could be applied to gradient based algorithms, control optimization, implicit time integration methods, deep learning, etc.Ph. D.
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Santi, Gian Maria <1991>. "Mesh Morphing Methods for Virtual Prototyping and Mechanical Component Optimization." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9608/1/Tesi_Dottorato_Santi_Finale.pdf.
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In this thesis, the coupling of mathematical geometry and its discretization (mesh) is performed using a method that fills the gap between simulation and design. Different modelling strategies are studied, tested and developed to bridge commercial CAD with a new methodology able to perform more accurate simulations without loosing the connection with the geometrical features. The aim of the thesis is to enhance the capabilities of Finite Element Methods (FEM) with the properties of Non-Uniform Radial Basis Functions (NURBS) inherited from CAD models in the design phase leading to a perfect representation of the model's boundary. The parametric space definition of the basis functions is borrowed from standard IGA (Isogeometric Analysis) and the possibility of process CAD models without the need for trivariate NURBS from NEFEM (NURBS Enhanced Finite Element Method). This particular combination yields to a bilinear Lagrangian basis and a new mapping between Cartesian and Parametric spaces for quadrilaterals. Using this new formulation it is possible to track the changes of the geometry and reduce the simulation's error up to 25-50% because of the perfect shape representation when compared to an equivalent FEM system. The problems presented are defined in a 2D space and solved using Matlab. NURBS are the key point to perform parametric morphing and simple optimizations while FEM remains the best way to perform simulations. This new method prevents to remodel B-Rep (Boundary Representation) parts after some simple modification due to the analysis and improves the geometry accuracy of the discretization. The geometrical file is directly imported from commercial software and processed by the method. Accuracy, convergence and seamless integration with commercial CAD packages are demonstrated applied to problems of arbitrary 2D geometry. The main problems treated are thermal analysis and solid mechanics where the better results are achieved.
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Pontefisso, Alessandro. "MODELLING AND OPTIMIZATION OF THE MECHANICAL PROPERTIES OF POLYMER NANOCOMPOSITES." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3423896.
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The research activity here reported spans different areas of the nanocomposite material science, giving a contribution toward the advancement in its state of the art.
The study of the effects of the filler distribution on the mechanical properties of nanomodified polymers is a major research topic which is carried out. Different computational and theoretical approaches have been developed, considering statistics, finite element analyses and micromechanics.
Several nanomodified epoxy resins have been manufactured along with glass fibre reinforced laminates with nanomodified matrix. The effects of the nanomodification on the mechanical properties of these composites have been studied, in order to validate predictive models and supply technical data to material designers.
The results obtained so far highlight the importance, in this class of materials, of the study of interactions at the nanoscale between the nanoreinforcement and the matrix.
The thesis is articulated in an introduction, followed by two sections, dedicated to the experimental activity and the modelling one, and by an appendix.
The introduction presents a brief overview on nanocomposites giving a primer to a reader devoid of prior experience with this class of materials.
The experimental activity section is constituted by four chapters. The first one contains the results of mechanical tests performed on a nanoparticle reinforced epoxy, alongside an analysis on the processing parameters employed in the composite preparation. The enhancement in the nanocomposite fracture toughness is compared with a theoretical model, showing a satisfactory agreement. The second chapter reports the study of the effect of the testing temperature on the fracture toughness of the same material. The analysis highlights the fundamental importance of the processing parameters and of the testing temperature on the nanomodification effects. The third chapter considers a different aspect of the nanomodification: a nanoplatelet reinforced epoxy is used to prepare notched specimens and the strength analysis of the notched component is carried out. The fourth chapter reports the research activity performed on the study of the matrix nanomodification of glass fibre reinforced laminates. The effects on the matrix dominated mechanical properties and the feasibility in the production of a laminate with antibacterial bulk properties are analysed.
The modelling section is constituted by three chapters. The first one contains a comparison between two approaches for the estimation of the elastic properties of a nanocomposite material, considering explicitly the presence of an interphase surrounding the nanoreinforcements. The first approach implements a two-step micromechanical model, while the second one is based on a finite element analysis. The second chapter reports the research activity carried out on the generation of representative volume elements of nanoparticle reinforced materials. A statistically based algorithm is implemented to minimize the volume element size while retaining its representativeness. The study of the interphase extent and of the overall elastic modulus, through finite element analyses, is reported. The third chapter extends these considerations to the generation of volume elements for nanoplatelet reinforced materials. The random sequential absorption approach is implemented and its hidden effects on the filler distribution highlighted. A new version of the algorithm is proposed to remove these unwanted behaviours.
The appendix section is dedicated to the implementation activity of approaches which have not been completed yet. The results obtained on the use of molecular dynamics in the simulation of polymers and nanomodified polymers are reported. While a detailed procedure for the simulation of epoxy resins is listed, the approach for the study of nanoplatelet-epoxy interactions is still in progress.L'attività di ricerca riportata nella presente tesi riguarda diverse aree della scienza dei materiali nanocompositi e mira a dare un contributo nell'avanzamento del suo stato dell'arte. Uno degli ambiti principali di indagine è stato inerente allo studio degli effetti della distribuzione dei rinforzi sulle proprietà meccaniche esibite dai polimeri nanomodificati. Diversi approcci, computazionali e teorici, sono stati sviluppati, sfruttando considerazioni statistiche, l'analisi agli elementi finiti e la modellazione micromeccanica. E' stata eseguita la nanomodificazione di diverse resine epossidiche e la produzione di laminati in fibra di vetro con matrici nanomodificate. Sono quindi stati studiati gli effetti della nanomodificazione sulle proprietà meccaniche di questi compositi, al fine di validare modelli previsionali e fornire dati ai progettisti di materiali. I risultati finora conseguiti evidenziano l'importanza che, in questa classe di materiali, ricopre lo studio delle interazioni alla nanoscala che si sviluppano tra i nanorinforzi e la matrice. La tesi è articolata in una introduzione, seguita da due sezioni dedicate all'attività sperimentale e alla modellazione, e da una appendice a concludere. La sezione inerente l'attività sperimentale è costituita da quattro capitoli. Il primo contiene i risultati dei test sperimentali eseguiti su resine epossidiche nanomodificate, volti ad indagarne le proprietà meccaniche includendo l'effetto dei parametri di processo. E' inoltre riportato il confronto tra l'incremento della tenacità a frattura misurato sperimentalmente e le previsioni di un modello teorico, evidenziando una soddisfacente congruenza dei risultati. Il secondo capitolo riporta lo studio degli effetti della temperatura sulla tenacità a frattura dello stesso materiale. Tale analisi rimarca la fondamentale importanza dei parametri di processo e della temperatura di prova sugli effetti della nanomodificazione. Il terzo capitolo considera un diverso aspetto della nanomodificazione, ovvero la resistenza di campioni intagliati, prodotti con resine epossidiche rinforzate con nanoplatelets. Il quarto capitolo riporta l'attività di ricerca portata avanti sull'impiego di matrici nanomodificate in laminati rinforzati in fibra di vetro. Oggetto di analisi sono le proprietà meccaniche dipendenti dalla matrice e la possibilità di produrre laminati con proprietà antibatteriche. La sezione inerente l'attività di modellazione è invece costituita da tre capitoli. Il primo contiene un confronto tra due approcci volti alla stima delle proprietà elastiche di un materiale nanocomposito, considerando in modo esplicito la presenza di una interfase che circonda i nanorinforzi. Il primo degli approcci implementati è un modello micromeccanico in due passi, mentre il secondo è basato su una analisi agli elementi finiti. Il secondo capitolo riporta l'attività di ricerca inerente la creazione di volumi rappresentativi di materiali rinforzati da nanoparticelle. Tale studio si basa sull'impiego di un algoritmo in grado di considerare aspetti statistici volti alla riduzione della dimensione del volume di controllo, pur mantenendone la rappresentatività. Sono quindi riportate le analisi sull'estensione dell'interfase e sulle proprietà elastiche globali del composito, valutate tramite analisi agli elementi finiti. Il terzo capitolo estende i concetti esposti nel precedente per la generazione di volumi rappresentativi di materiali rinforzati con nanoplatelets. Un approccio basato sull'algoritmo di random sequential absorption è stato implementato, evidenziando gli effetti che questo comporta sulla distribuzione dei rinforzi. E' stata quindi proposta una nuova versione di questo algoritmo, capace di rimuovere queste conseguenze indesiderate. L'appendice è dedicata all'esposizione dell'attività svolta nell'implementazione di approcci che però non sono ancora stati completati. In essa sono riportati i risultati finora conseguiti sull'uso della dinamica molecolare nella simulazione di polimeri e nanocompositi. In particolare è elencata una procedura dettagliata per la simulazione di resine epossidiche, e la prima parte di un approccio per lo studio di resine epossidiche rinforzate con nanoclay.
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Bracey, Marcus J. "Dynamic Modeling of Thermal Management System with Exergy Based Optimization." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503682474459341.
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Golubovic, Adnan. "Analysis and optimization of adhesively bonded joints." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/MQ64221.pdf.
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Mathews, Albert. "Powertrain optimization of a series hybrid racer." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86510.
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In recent years, we have witnessed the introduction of hybrid powertrains into the world of automobile racing. When compared to their conventional counter parts, hybrid powertrains demonstrate increased complexity with added degrees of freedom and technical barriers. For this reason, optimization of these systems becomes significantly more difficult requiring novel techniques.This thesis documents the work performed to develop simulation techniques intended for the optimization of a series hybrid powertrain which was itself designed for an open wheeled, single seat race vehicle. The methodology employs computer simulation techniques such as driver-in-the-loop and forward facing powertrain models to optimize the vehicle powertrain for a specific set of known race conditions. Data obtained from an existing vehicle and its individual components, was used in the creation and validation of the models developed for this work.
The conclusions of the optimization process agree reasonably with the results from track testing of a subsequent vehicle equipped with a powertrain design based on the work performed. The simulation techniques employed here realized significant improvement in the vehicle performance and provided the ability to optimize the powertrain for any set of known race conditions.
Tout récemment, la motorisation hybride a fait son entrée dans le monde de la course automobile. Ce type de motorisation est beaucoup plus complexe à gérer et à optimiser qu'une motorisation conventionnelle à moteur thermique. Afin d'y parvenir, il est nécessaire d'utiliser de nouvelles techniques de pointe afin de réussir à obtenir d'excellents résultats malgré le grand nombre de variables et de restrictions inhérentes à la motorisation hybride.
Les travaux présentés dans ce document ont pour objectif le développement d'une méthodologie permettant d'optimiser la motorisation d'un véhicule de course existant. Le véhicule en question est de type Formule et comporte une motorisation hybride série. La méthodologie développée emploie des techniques de simulation informatique tel que "driver-in-the-loop" et "forward facing powertrain models". L'utilisation de ces techniques permet d'optimiser la motorisation complexe d'un véhicule de course hybride série pour des conditions de course connues. La création et la validation des modèles utilisés sont basées sur de l'information acquise lors de tests sur route d'un véhicule de course hybride série et lors de tests sur banc d'essai de composants individuels.
Les résultats obtenus via modélisation et simulation informatique concordent de façon adéquate avec les résultats obtenus sur piste lors d'essais fait avec une motorisation élaborée à partir de la méthodologie d'optimisation préalablement développée. Les techniques de simulation utilisées ont permis d'augmenter de façon significative les performances du véhicule de course utilisé. De plus, elles ont rendu possible l'optimisation des paramètres de motorisation hybride série pour des conditions de course connues.
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Wiens, Alexander. "Gait optimization for a multilink anguilliform swimmer." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114571.
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Hyper-redundant mechanisms (HRMs), also known as snake-like robots, have been the target of a small but focused research push over the past four decades. Consisting of a simple kinematic chain with a large number of redundant degrees of freedom (DoF), they can act manipulators approximating the form and function of an elephant's trunk, or undulatory locomotors mimicking the motions of snakes, worms, and other creatures. Although past research on locomotion has largely restricted itself to land-based studies, hyper-redundant mechanisms are inherently well suited to aquatic propulsion. Their structural form allows them to directly mimic the swimming motions of anguilliform fish. Biological anguilliform swimmers are both maneuverable and extremely efficient, however, these properties hinge upon finely tuned body deformations. The current understanding of undulatory swimming does not provide a clear method to optimally define these deformations for a highly articulated system. The present study solves this issue by developing a scheme capable of producing optimal gaits for a hyper-redundant swimmer. The optimization process consists ofa self-propelled swimming model and a custom particle swarm algorithm. The proposed scheme is used to produce optimal gaits for efficient swimming over a range of different velocities and for high acceleration. Although the development of the gait generation process is an end in itself, the properties of the optimal swimming kinematics also provide insight on HRMs and undulatory swimming in a more general sense. Simple control strategies, key issues for design, and potential topics for future work are extracted from the results.Les recherches précédentes on montrés que des mécanismes hyper-redondants (MHR)sont fortement adaptables en bougeant sur la terre. Cependant, leurs capacités pourraient aussi être étendues aux environnements aquatiques par la propulsion semblable à celle de l'anguille. Les nageurs anguilliforme naturels sont autant manuvrables qu'extrêmement efficaces. Cependant, ces propriétés dépendent de déformations très spécifiques du corps. La compréhension actuelle de la nage ondulatoire ne fournit pas de méthode claire ou de façon optimale afin de définir ces déformations pour un système fortement articulé. L'étude présentée ici résout cette question en développant un processus informatique capable de produire des démarches optimales pour un robot hyper-redondant nageant. Le processus est composé d'un modèle nageant et d'un algorithme d'essaim de particules faits sur mesure. Cette solution d'optimisation est utilisée pour produire des démarches efficaces pour la natation sur une gamme de vitesses différentes et pour la haute accélération. Bien que le développement du processus d'optimisation soit une fin en soi, les propriétés de la cinématique de la nage optimale fournis aussi un aperu sur les MHRs et sur la natation ondulatoire dans un sens plus général. Des stratégies de contrôle simples, des problèmes-clés pour le design, et des sujets potentiels pour le travail à venir sont extraits des résultats.
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Timm, Richard W. (Richard William). "Visual-based methods in compliant mechanism optimization." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35649.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 103-105).
The purpose of this research is to generate visual-based methods for optimizing compliant mechanisms (CMs). Visual-based optimization methods use graphical representations (3-D plots) of CM performance to convey design information. They have many advantages over traditional optimization methods, such as enabling judgment-based design tradeoffs and ensuring robustness of optimized solutions. This research fulfilled the primary aims of determining (1) how to best convey decision-driving design information, and (2) how to interpret and analyze the results of a visual-based optimization method. Other useful tools resulting from this work are (3) a nondimensional model of a CM (a compliant four-bar mechanism) that may be used to maximize the information density of optimization plots, and (4) a new model of a compliant beam that establishes a link between beam stiffness and instant center location. This work presents designers with an optimization tool that may either be used to augment or replace current optimization methods.
by Richard W. Timm.
S.M.
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Chapman, Colin Donald. "Structural topology optimization via the genetic algorithm." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35410.
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Ni, Yang M. Eng Massachusetts Institute of Technology. "Optimization of service parts planning for InFocus." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38289.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaf 66).
A common problem faced by many industry companies, including InFocus, is that they are holding excess inventories and incurring unnecessary inventory holding costs yet are not able to achieve their expected customer service levels. This problem is critical to be addressed for companies who are striving to lower their supply chain costs and improve their management efficiencies. One solution to this problem is to use better forecasting methods and employ the appropriate inventory management policies. The objective of this project is to review the software package, Servigistics software tool, used by InFocus, to evaluate if it is suitable for InFocus' operations and to identify any improper practices when using Servigistics. The first step to address the problem is to review and evaluate Servigistics software package qualitatively. We found that Servigistics is a sound software tool with appropriate inventory and forecasting formulas. But the information fed into Servigistics is not accurate and up-to-date; this results in inaccurate results output by the Servigistics software. The second step is to evaluate Servigistics' output and InFocus' inventory management policy quantitatively.
(cont.) We found that InFocus has not been managing their inventory scientifically and for certain service parts, they procure excessive amounts in one shot. Approximately USD 3.8 million can be saved if InFocus manages its inventory scientifically using the current forecasting method. The major improvement comes from more discipline in their inventory management.
by Yang Ni.
M.Eng.
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Trapp, Thomas Alan 1966. "Shipboard integrated engineering plant survivable network optimization." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100150.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 181-186).
Due to the complexity of naval ship systems, and the iterative nature of classical design, the U.S. Navy has struggled to meet the spirit of Cost-as-an-Independent Variable (CAIV) policy. In particular, distinguishing between best-value concept variants is not well suited to Pareto-style tradeoff analysis unless the variants can be shown to be at or approximately minimum cost. This thesis presents a systematic process for minimum cost, survivable design of an integrated engineering plant (IEP). The mathematical optimization techniques used are suitable for early-stage design. There are three major contributions of this work. First, a straightforward method for "designed-in" survivability of early stage concepts at guaranteed minimum cost is presented, and with flexibility for multiple operating and casualty conditions. Second, interdependence between the electrical and cooling domains is modeled in detail, forming a new computational structure that could be extended to other domains as well. Third, a method for the integral design of minimum cost shipboard stored energy in consideration of casualty and operating conditions is shown. The overall methodology developed in this work can provide program managers assurance that design concepts all represent minimum cost and best value, thus reducing the trade space at an early stage when cost savings can be maximized in the acquisition program.
by Thomas Alan Trapp.
Ph. D.
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Esmail, Adnan M. "Cannabis sativa : an optimization study for ROI." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59909.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 25-29).
Despite hemp's multifarious uses in over 30 countries ranging from the manufacture of paper to specialty textiles, construction, animal feed, and fuel, its acceptance in the US has been shunned because of its association with marijuana, as a drug. While hemp and marijuana are varieties of Cannabis sativa, their similarity ends there. In reality, the growth of industrial hemp adjacent to marijuana results in cross-pollination that radically reduces potency of marijuana. Although restricted in the United States, industrial hemp farming is growing rapidly in many other countries, including Canada, France and China. Within many of these countries, hemp is grown in different ways and under different conditions to optimize cultivation of particular components of the plant, for either agro-practices or industrial and consumer demands. This study substantiates great economic prospects for cultivars, processors, and industrial partners in the legalization of industrial hemp farming. Hemp has also consistently demonstrated a versatility to grow and adapt to many soil, climatic and environmental conditions. Additionally, hemp improves the land by ridding it of weeds and insects, helping prepare it for rotation crops. Hemp's various components are capable of contributing to different industries with yields that are on par with competing crops like cotton, corn, and soybean, making it a financially attractive rotation crop with many auxiliary benefits. This study recommends hemp be planted as a rotation crop in approximately 25 plants/m 2 to optimize yield of both grain and straw in roughly 5 months. Given the potential for hemp to be the most economically viable agro-industry, with incredible ROI and close to effortless farming and cultivation on even the most challenging terrains, it is high time to legalize the production and farming of this non-psychotic plant for the many reasons contained in this report.
by Adnan M. Esmail.
S.B.
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Wilcox, Ronald James. "Flexible schedule optimization for human-robot collaboration." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81713.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 99-101).
Robots are increasingly entering domains typically thought of as human-only. This convergence of human and robotic agents leads to a need for new technology to enable safe and efficient collaboration. The goal of this thesis is to develop a task allocation and scheduling algorithm for teams of robots working with or around teams of humans in intense domains where tight, fluid choreography of robotic schedules is required to guarantee the safety of all involved while maintaining high levels of productivity. Three algorithms are presented in this work: the Adaptive Preferences Algorithm, the Multi-Agent Optimization Algorithm, and Tercio. Tercio, the culminatory algorithm, is capable of assigning robots to tasks and producing near-optimal schedules for ten agents and hundreds of tasks in seconds while making guarantees about process specifications such as worker safety and deadline satisfaction. This work extends dynamic scheduling methods to incorporate flexible windows with an optimization framework featuring a mixed integer program and a satisficing hueristic scheduler. By making use of Tercio, a manufacturing facility or other high-intensity domain may fluidly command a team of robots to complete tasks in a quick, efficient manner while maintaining an ability to respond seamlessly to disturbances at execution. This greatly increases both productivity, by decreasing the time spent recompiling solutions, and responsiveness to humans in the area. These improvements in performance are displayed with multiple live demonstrations and simulations of teams of robots responding to disturbances. Tercio acts as an enabling step towards the ultimate goal of fully coordinated factories of dozens to hundreds of robots accomplishing many thousands of tasks in a safe, predictable, efficient manner.
by Ronald J. Wilcox.
S.M.
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Dahdah, Tawfiq. "Superstructure optimization of hybrid thermal desalination configurations." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85452.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-105).
As the global demand for freshwater continues to increase, a larger number of resources are dedicated to seawater desalination technologies. In areas with high temperature and salinity water, thermal desalination technologies are often employed. In other areas, reverse osmosis technologies are more popular. While both these technologies have witnessed improvements in recent years, economic and performance issues still pose significant barriers to their universal implementation, which has left many countries, including ones bordering oceans and seas, suffering from dire water scarcity issues. This thesis proposes a methodology which enables the identification of improved thermal-based desalination structures. It is based on the notion of superstructure, which allows for the representation of numerous feed, brine and vapor routing schemes. A superstructure is developed. By adjusting the flow routings, the superstructure is capable of representing the common thermal desalination structures, as well as an extremely large number of alternate structures, some of which might exhibit advantageous behavior. The superstructure is built around a repeating unit which is a generalization of an effect in a multi-effect distillation system (MED) and a stage in a multi-stage flash system (MSF). Allowing for just 12 repeating units, more than 1040 different structures can be represented. The superstructure is thus proposed as an ideal tool for the structural optimization of thermal desalination systems, whereby the optimal selection of components making up the final system, the optimal routing of the vapors as well as the optimal operating conditions are all variables simultaneously determined during the optimization problem. The proposed methodology is applicable to both stand-alone desalination plants and dual purpose (water and power) plants wherein the heat source to the desalination plant is fixed. It can be extended to also consider hybrid thermal-mechanical desalination structures, as well as dual purpose plants where the interface of power cycle and desalination is also optimized for. A multi-objective structural optimization of stand-alone thermal desalination structures is performed in Chapter 2, whereby the performance ratio of the structures is maximized while the specific area requirements are minimized. It is found that for any particular distillate production requirement, alternate structures with non-conventional flow patterns require lower heat transfer areas compared to commonly implemented configurations. Examples of these non-conventional configurations are identified, which include a forward feed - forward feed MED structure, involving the integration of two forward feed MED plants. Chapter 3 highlights how the superstructure can be adapted to optimize integrated thermal desalination and thermal compression systems. Specifically, the conducted study investigates whether there is any merit to the thermal compression of vapor streams produced in intermediate MED effects as opposed to the common practice of compressing vapors produced in the last effect. The study concludes that intermediate vapor compression results in significant reductions in area requirements, as well as significant increases in maximum distillate production capacities. Moreover, the study confirms that the optimal location of vapor extraction is heavily dependent on the exact distillate production requirement in question. Two novel configuration forms are informed by the optimization. The first is an integrated MED-TVC + MED + MSF system, while the second is an integrated MED-TVC + MSF system.
by Tawfiq Dahdah.
S.M.
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Brown, Matthew Lasché. "Intelligent robot grinding : planning, optimization, and control." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14552.
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