Browsing by Subject "optimization"

Now showing 1 - 4 of 4
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    Animation of human motion with inverse kinematics using nonlinear programming
    (2001) Abalı, A. Sezgin
    Animation of articulated figures has always been an interesting subject of computer graphics due to a wide range of applications, like military, ergonomic design etc. An articulated figure is usually modelled as a set of segments linked with joints. Changing the joint angles brings the articulated figure to a new posture. An animator can define the joint angles for a new posture (forward kinematics). However, it is difficult to estimate the exact joint angles needed to place the articulated figure to a predefined position. Instead of this, an animator can specify the desired position for an end-effector, and then an algorithm computes the joint angles needed (inverse kinematics). In this thesis, we present the implementation of an inverse kinematics algorithm using nonlinear optimization methods. This algorithm computes a potential function value between the end-effector and the desired posture of the end-effector called goal. Then, it tries to minimize the value of the function. If the goal cannot be reached due to constraints then an optimum solution is found and applied by the algorithm. The user may assign priority to the joint angles by scaling initial values estimated by the algorithm. In this way, the joint angles change according to the animator’s priority
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    Compromising system and user interests in shelter location and evacuation planning
    (Elsevier Ltd, 2015) Bayram V.; Tansel, B.T.; Yaman H.
    Traffic management during an evacuation and the decision of where to locate the shelters are of critical importance to the performance of an evacuation plan. From the evacuation management authority's point of view, the desirable goal is to minimize the total evacuation time by computing a system optimum (SO). However, evacuees may not be willing to take long routes enforced on them by a SO solution; but they may consent to taking routes with lengths not longer than the shortest path to the nearest shelter site by more than a tolerable factor. We develop a model that optimally locates shelters and assigns evacuees to the nearest shelter sites by assigning them to shortest paths, shortest and nearest with a given degree of tolerance, so that the total evacuation time is minimized. As the travel time on a road segment is often modeled as a nonlinear function of the flow on the segment, the resulting model is a nonlinear mixed integer programming model. We develop a solution method that can handle practical size problems using second order cone programming techniques. Using our model, we investigate the importance of the number and locations of shelter sites and the trade-off between efficiency and fairness. © 2014 Elsevier Ltd.
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    Cost-effective production of biological materials for food applications
    (2012) Han, Diren
    This thesis consists of two chapters; in the first chapter response surface optimization of the production of a potential probiotic strain was studied by using bioreactors and in the second chapter screening of biosurfactant producing microorganisms was carried out followed by the purification and characterization of the biosurfactant produced. Probiotics are live microorganisms that when administered in adequate amounts are favorable to their host. They are used on livestock to enhance the growth of animals, improve the efficiency of feed conversion and to decrease mortality rate. Therefore, it is important to produce these microorganisms in high amounts. However, process economics is a problem in large scale production of the microorganisms. Main factors that affect the process economics are the growth medium of the organism and the process conditions. Therefore, optimizing the composition of the growth media and cultivation conditions are of crucial importance in large scale production. In this study, optimization of growth media composition and cultivation conditions of a novel probiotic strain, Bacillus pumilus STF26, was done. Factors optimized were temperature, pH and the concentrations of dextrose as carbon source, yeast extract as nitrogen source, KH2PO4 and MgSO4.7H2O. Response surface methodology was used to optimize the parameter and the optimum values are found to be 30.9 °C, 6.9, 20 % (w/v), 1.526 % (w/v), 0.1 % (w/v) and 0.5 % (w/v) for temperature, pH and the concentrations of dextrose, yeast extract, KH2PO4 and MgSO4.7H2O, respectively. Maximum biomass at optimum conditions was 10.42 g/L which is nearly 2.5 times higher when compared to the one obtained by using LB medium at optimized temperature and pH values. In the second chapter, production and characterization of a biosurfactant produced by a novel strain of Staphylococcus xylosus, STF1, was studied. Biosurfactants are surface active agents that have a broad range of applications in different industries and they have several advantages over their chemically synthesized counterparts. However, they cannot compete economically with synthetic surfactants due to their high production cost, the difficulties in downstream processing and the lack of overproducing strains. In this study a novel strain that produces biosurfactant, STF1, was isolated and the biosurfactant was characterized by using mass spectrometry and Fourier transform infrared (FTIR) spectroscopy. FTIR results indicated the lipopeptide nature of the biosurfactant produced by this strain. Moreover, the mass of the purified biosurfactant was 931.9550 (m/z).
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    Modeling and optimization of micro scale pocket milling operations
    (2014) Sert, Bengisu
    Manufacturing of micro scale parts and components made from materials having complex three dimensional surfaces are used in today’s high value added products. These components are commonly used in biomedical and consumer electronics industries and for such applications, fabrication of micro parts at a low cost without sacrificing quality is a challenge. Micro mechanical milling is a viable technique which can be used to produce micro parts, however the existing knowledge base on micro milling is limited compared to macro scale machining operations. The subject of this thesis is micro scale pocket milling operations used in micro mold making which are used in micro plastic injection in mass production polymer micro parts. Modeling of pocket milling while machining of basic pocket shapes are considered first. The developed milling model is then extended to more complex mold shapes. Minimum total production time is used as the objective to solve single pass, multi pass, and multi tool problems. Case studies are presented for each problem type considering the practical issues in micro milling. A software has been developed to optimize machining parameters and it is shown that the developed pocket milling optimization model can successfully be used in process planning studies.