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1
Rosendo, Kali M. "Floating Treatment Island configuration for optimum nutrient removal." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119320.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 45-46).<br>Floating Treatment Islands (FTIs) have been studied as a method to mitigate the risks associated with high nutrient levels in contaminated water. The goal of this project was to compare fractional treatment rates by a series of FTIs located at the edge of a channel, allowing the center channel to remain clear. Experiments were performed using a scaled-down model floating treatment island (FTI) with a 19 x 24.5 cm x 10 cm root zone modeled using 3.6 mm diameter dowel rods (n = 75/135 cm 2, low flow blockage) attached to the inside wall of a 1.2 m wide x 16 m long flume. Three cases were considered, with four FTIs spaced at various distances based on the length scale L of the FTI: the closest spacing had each FTI located 2L downstream of the last, the mid-range spacing were placed 4L apart, and the farthest spacing had each FTI 8L past the last. Based on the cross-sectionally averaged flow rates measured at the leading and trailing edges of the root zone, treatment rates within the root zone were estimated using a first-order kinetic model, and an iterative method was used to solve for the fractional treatment by the series of FTIs. This paper explores the effects of various parameters on treatment, including flow rates and velocity recovery, biological uptake rate, and island size. Finally, the researcher evaluated which setup provided the most treatment for a given number of treatment islands. It was found that the 8L spacing provided the best treatment, significantly more than the 4L or 2L spacing for k < 10 day⁻¹ according to the results of a two-sample t-test. For a set of 8L spaced FTIs with an uptake rate of 1 day⁻¹ with a cross-sectional coverage of 13.6%, it would be possible to reduce the upstream nutrient concentration by 25% over a channel length of roughly 3.5 km, 50% over a channel length of 10 km, and 90% over a channel length of approximately 32 km. These treatment rates could have the potential to mitigate the risk of eutrophication in sufficiently long channels.<br>by Kali M. Rosendo.<br>M. Eng.
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Daniels, Geoffrey Philip. "An optimum visual sensor configuration for terrestrial locomotion." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690379.
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Human technological advancement has continually created new opportunities for machinery to automate intensive tasks. However, these machines still need to be delivered and often controlled by humans. Autonomous Ground Vehicles (AGVs) can completely remove the locomotion dependency of these systems on humans, enabling a robotic revolution. The locomotive performance of AGVs is dependent on the quantity and quality of information received about the terrain ahead; for this purpose, vision is by far the most effective sense. Contextual machine vision is a new area of research where fundamental questions such as how to optimise a visual system specification for a locomotive platform to enable fast locomotion are yet to be addressed. In this thesis, abstract mathematical models of a generic vision sensor and generic locomotor platform were developed to investigate the relationship between sensor specification and locomotor performance with respect to a single key parameter, the maximum ground speed. Initially a static AGV model was investigated, before being expanded to include forward motion, thus enabling the maximum dynamic performance of an AGV to be evaluated. The vision sensor model was designed with interchangeable sensor geometries so that the performance of multiple sensor geometries could be compared. Two of the sensor geometries were designed to approximate a digital camera and human eye, while the third removed non-linearities associated with the detector. The optimum specification to enable maximum speed was defined by the geometry of the sensor. The achievable proximity to the optimum is restricted by system resolution. Generally the sensor geometries analogous to a digital camera and human eye outperformed the linearised model, however, this model can be made insensitive to sensor angle which can be advantageous. Optical flow algorithm performance was not directly effected by detector geometry. Although the resolution variation of the non-linearised detectors and locomotion context reduced tracking performance. Simulating pose error on the model with a random or systemic error resulted in the outcome that vision was a requirement for motion estimation, leading to the development of an AGV vision system for human AGVs. The performance of a visually limited, controlled, human AGV, in a virtual reality environment showed a minimum of 500 features was required for good performance at a foot placement task.
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Ngalande, Joshua. "Assessing the optimum operating configuration for multiple chillers at Murdoch University." Thesis, Ngalande, Joshua (2015) Assessing the optimum operating configuration for multiple chillers at Murdoch University. Other thesis, Murdoch University, 2015. https://researchrepository.murdoch.edu.au/id/eprint/30761/.
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This paper endeavours to answer the research question of how to efficiently operate a system of multiple chillers in the most effective combination regime. In the process, a successful method of assessing this has been developed, which has proven that the most effective way to run a multi-configuration chiller scheme is by following two distinct methods. One method deals with a multi-chiller setting that has thermal storage, and the other method deals with a multi-chiller systems without storage. The latter method is discussed more in this paper. The former method is based on other research papers that argue the easiest and most efficient method of running a multi-chiller system is to have thermal storage. This allows a staging regime that can operate any number of chillers at their maximum co-efficiency of performance (COP) or efficiency performance, while either supplying the load or charging the thermal storage. The fact that the chillers can always operate at their maximum point makes this method the most efficient available; however, in some cases there is no thermal storage available and the analysis changes slightly. A detailed analysis of the different methods of staging has been carried out and it proved that the most efficient way of running a multi-configuration setup chiller system is to run the target load closest to the next nearest chiller configuration that can supply that load. An algorithm and system has been developed on the best way to do this, and further work on how computational resources can be exploited to do this more easily is discussed.
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Zhang, Yi. "Synthesis of optimum HVAC system configurations by evolutionary algorithm." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7714.
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The HVAC system configuration is a conceptual design of the HVAC system, including the employed components, the topology of the airflow network, and the control strategy with set points. Selection of HVAC system configuration is normally done in the early stage of the design process. The configuration design, however, has significant impacts on the performance of the final system. This thesis describes the development of the design synthesis of optimal HVAC system configurations by Evolutionary Algorithm. In this research, the HVAC system configuration design synthesis has been formulated as an optimisation problem, in which, the component set of the configuration, the topology of the airflow network, and the control set points for the assumed supervisory control strategy, are the optimisation variables. Psychrometrics-based configuration model has been developed in order to evaluate the optimisation objective of minimising the annual energy consumption of the HVAC system. The optimisation is also subjected to a number of design constraints, including the connectivity of the topology, the performance limitations of the components, and the design requirements for the air-conditioned zones. The configuration synthesis problem is a multi-level optimisation problem. The topology depends on the set of selected components, whereas the search space of the control set points changes with the different components and topology. On the other hand, the performance of the configuration is assessed with its optimum operation; therefore the control set points have to be optimised for each configuration solution, before the optimum configuration can be identified. In this research, a simultaneous evolutionary approach has been developed. All optimisation variables of the configuration have been enwded into an integrated genotypic data structure. Evolutionary operators have also been developed to search the topological space (for the optimum topology) and parametric space (for the optimal control set points) at the same time. The performance of the developed approach has been validated with example optimisation problems. It is concluded that the implemented evolutionary algorithm has been able to find (near) optimum solutions for various design problems, though multiple trials may be required. The limitations of this approach and the direction of future development have been discussed.
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Ozturk, Fatih Mehmet. "Optimum Design Of Multistep Spur Gearbox." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606749/index.pdf.
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Optimum design of multistep gearbox, since many high-performance power
transmission applications (e.g., automotive, space industry) require compact volume,
has become an important interest area. This design application includes more
complicated problems that are not taken into account while designing single stage
gear drives. Design applications are generally made by trial and error methods
depending on the experience and the intuition of the designer.
In this study, using Visual Basic 6.0, an interactive program is developed for
designing multistep involute standard and nonstandard spur gearbox according to the
American Gear Manufacturers Association (AGMA) Standards 218.01 and 2001-
B88. All the equations for calculating the pitting resistance geometry factor I, and
the bending strength geometry factor J, are valid for external spur gears that are
generated by rack-type tools (rack cutters or hobs). The program is made for twostage
to six-stage gear drives, which are commonly used in the industry.
Compactness of gear pairs and gearbox, and equality of factor of safety against
bending failure is taken as the design objective. By considering the total required
gear ratio, the number of reduction stages is input by the user. Gear ratios of every
stage is distributed to the stages according to the total gear ratio that satisfies the
required precision (from ±<br>0.1 to ±<br>0.00001 on overall gear ratio) depending on the
user selected constraints (unequal gear ratio for every stage, noninteger gear ratio
e.g.). Dimensional design is determined by considering bending stress, pitting stress,
and involute interference constraints. These steps are carried out iteratively until a
desirable solution is acquired. The necessary parameters for configuration design
such as number of teeth, module, addendum modification coefficient, are selected
from previously determined gear pairs that satisfies the constraints by user
interaction considering the performance criterion from the developed program. The
positions of gears and shafts are determined automatically in order to keep the
volume of gearbox as minimum while satisfying the nonlinear spatial constraints
(center distance constraint for proper meshing of gear pairs, face distance constraint
for proper assembly of pinion and gear having same shaft, gear interference
constraint for preventing interferences between gears, shaft interference constraint
for preventing interferences between gears and shafts) by using DLL (Dynamic Link
Library) technology of Lingo 8.0 optimization software together with Visual Basic
6.0. If shaft interference constraint is removed then cantilevered mounting of gear
pairs would also be possible, otherwise the gears should be mounted between
bearings. Visual output of assembly is made by using Autodesk Inventor 7.0,
automatically by the program.
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Lounsbury, Robert Lee. "Optimum antenna configuration for maximizing access point range of an IEEE 802.11 wireless mesh network in support of multi-mission operations relative to hastily formed scalable deployments." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5FLounsbury.pdf.
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Thesis (M.S. in Systems Technology (Command, Control, and Communications (C3)))--Naval Postgraduate School, September 2007.<br>Thesis Advisor(s): Ehlert, James. "September 2007." Description based on title screen as viewed on Oct. 23, 2007. Includes bibliographical references (p. 85-86). Also available in print.
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Lounsbury, Jr Robert L. "Optimum Antenna Configuration for Maximizing Access Point Range of an IEEE 802.11 Wireless Mesh Network in Support of Multi-Mission Operations Relative to Hastily Formed Scalable Deployments." Ft. Belvoir : Defense Technical Information Center, 2007. http://handle.dtic.mil/100.2/ADA474138.
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Smith, Jonathan Burke. "Optimum hybrid vehicle configurations for heavy duty applications." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1985.
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Thesis (M.S.)--West Virginia University, 2001.<br>Title from document title page. Document formatted into pages; contains viii, 109 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 71-72).
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Tanil, Cagatay. "Optimal External Configuration Design Of Missiles." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610873/index.pdf.
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The main area of emphasis in this study is to investigate the methods and technology for aerodynamic configuration sizing of missiles and to develop a software platform in MATLAB®<br>environment as a design tool which has an ability of optimizing the external configuration of missiles for a set of flight requirements specified by the user through a graphical user interface. A genetic algorithm based optimization tool is prepared by MATLAB is expected to help the designer to find out the best external geometry candidates in the conceptual design stage. Missile DATCOM software package is employed to predict the aerodynamic coefficients needed in finding the performance merits of a missile for each external geometry candidate by integrating its dynamic equations of motion.
Numerous external geometry candidates are rapidly eliminated according to objectives and constraints specified by designers, which provide necessary information in preliminary design. In this elimination, the external geometry candidates are graded according to their flight performances in order to discover an optimum solution.
In the conceptual design, the most important performance objectives related to the external geometry of a missile are range, speed, maneuverability, and control effectiveness. These objectives are directly related to the equations of motion of the missile, concluding that the speed and flight range are related to the total mass and the drag-to-lift ratio acting on missile. Also, maneuverability depends on the normal force acting on missile body and mass whereas the control effectiveness is affected by pitching moment and mass moment of inertia of missile. All of the flight performance data are obtained by running a two degree-of-freedom simulation.
In order to solve the resulting multi-objective optimization problem with a set of constraint of linear and nonlinear nature and in equality and inequality forms, genetic-algorithm-based methods are applied. Hybrid encoding methods in which the integer configuration variables (i.e., nose shape and control type) and real-valued geometrical dimension (i.e., diameter, length) parameters are encoded in the same individual chromosome.
An external configuration design tool (EXCON) is developed as a synthesis and external sizing tool for the subsonic cruise missiles. A graphical user interface (GUI), a flight simulator and optimization modules are embedded into the tool. A numerical example, the re-configuration problem of an anti-ship cruise missile Harpoon, is presented to demonstrate the accuracy and feasibility of the conceptual design tool. The optimum external geometries found for different penalty weights of penalty terms in the cost function are compared according to their constraint violations and launch mass values. By means of using EXCON, the launch mass original baseline Harpoon is reduced by approximately 30% without deteriorating the other flight performance characteristics of the original Harpoon.
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Gruber, Elliott Ross. "Optimal configuration of adjustable noise suppressors." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47616.
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Noise generated by fluid power applications can be treated using bladder-style suppressors, and an optimal operating condition for these devices is sought in this thesis. Bladder-style suppressors employ a compliant nitrogen-charged bladder to create an impedance change within the system, reflecting the noise back to the source and preventing it from propagating downstream. The noise in a hydraulic system is created by a pump, the flow source in a hydraulic system, and can be separated into three categories: fluid-borne noise, structure-borne noise and airborne noise. Fluid-borne noise places addition stress on sealing surfaces, potentially causing leaks. Airborne noise can be uncomfortable, even hazardous depending on the level. Bladder-style suppressors primarily treat fluid-borne noise; however, it is seen in the literature that fluid-borne noise is the cause of structure-borne and airborne noise.
This thesis presents an optimization method for finding the optimal charge pressure for implementation with a given system operating over a broad range of system pressures. The optimization weights suppressor performance by the spectral content of the fluid-borne noise as well as the duty cycle of the system. A single charge pressure works well over a small range of system pressures, though many fluid power applications operate over a larger range of system pressure than the usable range of a suppressor. For systems operating over an extremely broad pressure range, two suppressors charged to different pressures are used to treat the noise in the entire system pressure range.
To determine suppressor performance experimental measurements were performed, and models developed, of the transmission loss of this type of device. A multi-microphone method using transfer function relationships between six sensors determines the transmission loss of the suppressor under test. An equivalent fluid model modeling the wave behavior both upstream and downstream, as well as within the suppressor, was created to predict suppressor transmission loss.
Optimal configurations are found for a set of system pressures, charge pressures and duty cycles. Analysis of the results shows the time weighting has a more significant impact on the optimum charge pressure than the frequency weighting, as shown by duty cycles considered in this thesis. In addition, all charge pressures selected as optimal for either single suppressor optimizations or double suppressor optimizations, exhibit the highest transmission loss for a single system pressure in the pressure duty cycle for a simulated machine.
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Hwang, Yong Goo. "Optimal configuration of digital communication network." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA243041.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 1990.<br>Thesis Advisor(s): Suh, Myung W. Second Reader: Hamming, Richard W. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Program Listings, Lagrangian Relaxation. Author(s) subject terms: Network, Langrangian Relaxation, Subgradient Optimization. Includes bibliographical references (p. 66-67). Also available in print.
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Khattab, M. I. A. "Optimum rotor blade configurations for minimum oscillatory root bending moment." Thesis, City University London, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353959.
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Depret-Guillaume, James Serge. "Optimal Point Sets With Few Distinct Triangles." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/91425.
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In this thesis we consider the maximum number of points in $mathbb{R}^d$ which form exactly $t$ distinct triangles, which we denote by $F_d(t)$. We determine the values of $F_d(1)$ for all $dgeq3$, as well as determining $F_3(2)$. It was known from the work of Epstein et al. cite{Epstein} that $F_2(1) = 4$. Here we show somewhat surprisingly that $F_3(1) = 4$ and $F_d(1) = d + 1$, whenever $d geq 3$, and characterize the optimal point configurations. We also show that $F_3(2) = 6$ and give one such optimal point configuration. This is a higher dimensional extension of a variant of the distinct distance problem put forward by ErdH{o}s and Fishburn cite{ErdosFishburn}.<br>Master of Science<br>In this thesis we consider the following question: Given a number of triangles, t, where each of these triangles are different, we ask what is the maximum number of points that can be placed in d-dimensional space, such that every triplets of these points form the vertices of only the t allowable triangles. We answer this for every dimension, d when the number of triangles is t = 1, as well as show that when t = 2 triangle are in d = 3-dimensional space. This set of questions rises from considering the work of Erd˝os and Fishburn in higher dimensional space [EF].
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Low, Kian Huat. "Optimal configuration, design and operation of batch distillation processes." Thesis, University College London (University of London), 2003. http://discovery.ucl.ac.uk/1383525/.
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The overall objective of this thesis is to study the optimal configuration. design and operating policy of batch distillation processes in different separation scenarios. In so doing, this work also aims to provide conceptual insights and compare the performance of the traditional regular column against unconventional columns. In the first part of the thesis, the optimal operation of extractive batch distillation is investigated. A rigorous dynamic optimisation approach based on a detailed model is employed. In addition to the regular column, the optimal operation of the process in the unconventional middle vessel column is examined. The liquid and vapour stream configurations at the middle section of the column is explored for the first time, resulting in improved process performance. The performance of both columns are compared and the results show how their relative performances are affected by different feed compositions. The second part of the thesis is concerned with the simultaneous design and operation of batch distillation processes. The thesis proposes a stochastic optimisation methodology based on genetic algorithm and penalty function. Using the proposed methodology, the simultaneous optimal designs and operations of the regular column for different design scenarios are investigated using rigorous models. Furthermore, the optimal design of the unconventional multivessel column for multicomponent separation is studied for the first time. The effect of different factors such as objective function, feed composition, relative volatility, product specification and number of components on the optimal design of the multivessel system is investigated. A comparison of the performance of the multivessel system with the regular column is also presented. In the final part of the thesis, the feasibility of the genetic algorithm-penalty function approach in tackling simultaneous configuration selection, column sizing and operation is explored. In the case of binary mixture separation, the regular column was found to be more profitable for feeds with a high fraction of the light component whilst the inverted column is optimal for heavier feeds. There exists a flip point, the location of which is case study specific. For the multicomponent separation case study, the multivessel system is found to be superior to both the regular and inverted configurations
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Mason, Barry S. "The ergonomics of wheelchair configuration for optimal sport performance." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8486.
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Huang, Haidong. "Optimal design of a flying-wing aircraft inner wing structure configuration." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7439.
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Flying-wing aircraft are considered to have great advantages and potentials in
aerodynamic performance and weight saving. However, they also have many
challenges in design. One of the biggest challenges is the structural design of
the inner wing (fuselage). Unlike the conventional fuselage of a tube
configuration, the flying-wing aircraft inner wing cross section is limited to a
noncircular shape, which is not structurally efficient to resist the internal
pressure load. In order to solve this problem, a number of configurations have
been proposed by other designers such as Multi Bubble Fuselage (MBF),
Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS), Vaulted Shell
Honeycomb Core (VLHC), Flat Sandwich Shell Honeycomb Core (FLHC), Y
Braced Box Fuselage and the modified fuselage designed with Y brace
replaced by vaulted shell configurations. However all these configurations still
inevitably have structural weight penalty compared with optimal tube fuselage
layout. This current study intends to focus on finding an optimal configuration
with minimum structural weight penalty for a flying-wing concept in a preliminary
design stage.
A new possible inner wing configuration, in terms of aerodynamic shape and
structural layout, was proposed by the author, and it might be referred as
‘Wave-Section Configuration’. The methodologies of how to obtain a structurally
efficient curvature of the shape, as well as how to conduct the initial sizing were
incorporated.
A theoretical analysis of load transmission indicated that the Wave-Section
Configuration is feasible, and this was further proved as being practical by FE
analysis. Moreover, initial FE analysis and comparison of the Wave-Section
Configuration with two other typical configurations, Multi Bubble Fuselage and
Conventional Wing, suggested that the Wave-Section Configuration is an
optimal design in terms of weight saving. However, due to limitations of the
author’s research area, influences on aerodynamic performances have not yet
been taken into account.
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Nordbø, Henrik. "Optimal configuration of supply logistics for remote oil and gas fields." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22333.
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The objective of this thesis has been to compare alternatives to improve the supply service for remote locations offshore. First the alternative of running a conventional supply service has been assessed, where the platform supply vessels (PSVs) sailed directly from a land depot to supply the installations with commodities. The alternative to the conventional supply service was to have two converted cargo ships in use as storage units located at the oil and gas field which deliver cargo to the PSVs. For the alternative with the storage units the ships switch position, when one is in operation the other one goes to shore and stock up on supplies. PSVs are expensive and if one can reduce the number of ships in operation it will grant great savings for the operator of the oil and gas field. Having storage units located in the proximity of the installations offshore will reduce the sailing distance of the PSVs to a fraction of the original sailing distance from a land depot. While the cost of the PSVs will be reduced one has a cost increase due to the storage units. Finding the point at which the storage units can become profitable has been the essence of this thesis. A case study has been made to compare the two different setups for oil and gas activities outside Jan Mayen. It was expected a maximum activity level with three installations in operation. The case study has been made more general by adding up to five additional installations to get a better look at the savings of having the storage units with more installations to service. To minimize the costs of each setup it was made a mathematical formulation for each of them. For the regular setup the minimum cost of routing the supply vessels was found from a land depot, given a required supply frequency of the installations. The port in Kristiansund has been chosen as a suitable land depot for this case study. In the setup with storage units the routing from the storage units with PSVs are considered in addition to the cost of the storage units. To minimize the routing cost from the storage units the mathematical model had to consider different locations of the units. Both of the setups have the same input data as a basis to get a good comparison. The models are solved for a weekly planning period. Some basic design characteristics of the storage units have been made. It was concluded that open hatch bulk carriers would be most suited for the operation. The vessels to be converted should have a deadweight capacity of around 57 300 tons. It is estimated here that the cost of one storage unit will be 53 000 USD per day. This price may not be very accurate and is based on many assumptions due to lack of assessable cost information, but it has been tried to make a conservative estimate. The mathematical formulations of the models have been solved with the optimization software Xpress. For the regular supply service from land the total cost of the supply service ranged from 590 000 USD per week for three installations and up to 1 550 000 USD for eight installations. The results showed that there was a linear increase in cost when increasing the number of installations to supply. Compared to the setup with the converted cargo ships the total costs ranged from 916 000 USD per week for three installations to 1 137 000 USD per week for eight installations. In this case the cost per installation gets lower with the number of installations to supply. When solving the model for the supply service from land one gets larger ships in operation which can visit as many installations as possible on a route as they can only make one trip per week. Compared to the case with the storage units one gets a few smaller PSVs in operation which can sail many routes per week. It has been found that the concept with the storage units would be profitable with 6 installations or more to service in this case. With less than 6 installations to service it would be more expensive to have storage units than running a regular supply service from land. Generally it can be concluded that having the storage units could be profitable if there is enough installations to service. The other factor with the biggest effect on the problem is the distance to shore, however, finding at what distance from shore the storage unit becomes profitable was not included in this study. The final conclusion of the work here is that the use of storage units could reduce the cost of the supply service, and is an interesting concept that should be studied further.
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Emelogu, Adindu Ahurueze. "Optimal supply chain configuration for the additive manufacturing of biomedical implants." Thesis, Mississippi State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10244178.
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<p> In this dissertation, we study two important problems related to additive manufacturing (AM). In the first part, we investigate the economic feasibility of using AM to fabricate biomedical implants at the sites of hospitals AM versus traditional manufacturing (TM). We propose a cost model to quantify the supply-chain level costs associated with the production of biomedical implants using AM technology, and formulate the problem as a two-stage stochastic programming model, which determines the number of AM facilities to be established and volume of product flow between manufacturing facilities and hospitals at a minimum cost. We use the sample average approximation (SAA) approach to obtain solutions to the problem for a real-world case study of hospitals in the state of Mississippi. We find that the ratio between the unit production costs of AM and TM (ATR), demand and product lead time are key cost parameters that determine the economic feasibility of AM.</p><p> In the second part, we investigate the AM facility deployment approaches which affect both the supply chain network cost and the extent of benefits derived from AM. We formulate the supply chain network cost as a continuous approximation model and use optimization algorithms to determine how centralized or distributed the AM facilities should be and how much raw materials these facilities should order so that the total network cost is minimized. We apply the cost model to a real-world case study of hospitals in 12 states of southeastern USA. We find that the demand for biomedical implants in the region, fixed investment cost of AM machines, personnel cost of operating the machines and transportation cost are the major factors that determine the optimal AM facility deployment configuration.</p><p> In the last part, we propose an enhanced sample average approximation (eSAA) technique that improves the basic SAA method. The eSAA technique uses clustering and statistical techniques to overcome the sample size issue inherent in basic SAA. Our results from extensive numerical experiments indicate that the eSAA can perform up to 699% faster than the basic SAA, thereby making it a competitive solution approach of choice in large scale stochastic optimization problems.</p>
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Abdesalam, Mosa Aboabdalla. "Non-Uniform 3D Antenna Array Optimal Configuration via Extremum Seeking Control." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1480723557369506.
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Minko, Stanislav. "Optimal configuration of the mechanical structure and flap actuator for hydrofoils." Thesis, KTH, Maskinkonstruktion (Avd.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263032.
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Hydrofoil vessels are becoming more popular and driving marine development forward. Since the water friction is greatly reduced, they allow achieving higher speeds and electrification of the boats. FoilCart is a full electric active controlled hydrofoil boat designed as a research project at KTH. The small version of this boat is considered to be designed in this thesis and an optimal configuration for the mast and rudder of the boat is studied. The study is prone to be used as a basis for hydrofoil wing and flap design and includes research on small electromagnets. The design and dynamics of the hydrofoils are adapted from aeronautics. An idea of a morphing airplane wing has been successfully tested and now evaluated for the hydrofoil application. An electromagnetic actuator is proposed for the actuation of the rudder as competitor to typically used once. This study finds the optimal combination of an actuator and mechanical structure comparing classical actuator (servo) with electromagnetic actuator and classical structure (hingetype) with morphing structure. Those four configurations are evaluated with respect to energy usage, response time, volume of the solution and maximal rudder force. Workflow of the thesis is divided to four main parts: calculations of the hydrodynamic forces to realize the peak torque that the rudder will need to withstand in water, CAD design of each evaluated configuration (including material and actuator studies), prototype manufacturing for the verifications, summary of the information and presentation according to evaluation parameters. The study is concluded with an optimal choice of the configuration with respect to different factors. Servo actuator in combination with hinge-typed structure is most optimal in terms of energy efficiency. The most compact configuration is electromagnetic actuator in combination with hinge-type structure. Maximal rudder force is supplied by the servo meanwhile fastest response is achieved by electromagnetic actuator. Due to better hydrodynamic characteristics, maximal rudder force and compact volume, a configuration of morphing structure and servo actuator is recommended for implementation for miniaturized version of FoilCart vessel. Implementation means a first step to apply morphing structures into marine applications. Each configuration has its own strength and weakness and therefore all four are to be carefully studied before choosing an actuator / structure according to the application.<br>Bärplansfartyg blir mer och mer populära och driver marinutvecklingen framåt. Bärplan tillåter högre hastigheter att nås och elektrifiering av båtar eftersom friktionen minskar kraftigt. FoilCart är en elektrisk aktivt kontrollerad bärplansbåt som är framtagen av ett forskningsprojekt på KTH. En mindre version av fartyget är under utveckling och den här studien undersöker valet av optimal design för mast och roderkonstruktionen. Rapporten kan också användas som underlag för bärplans vingdesign och för projekt där små elektromagneter är inblandade. Designen och dynamiken av bärplan kommer ursprungligen från flygplansbranschen. Idén av en böjlig, morfande vinge har redan implementerats på flygplan och ska nu testas i vatten. Förutom detta evalueras även ett föreslaget elektromagnetiskt ställdon för aktueringen av rodret. Studien hittar den mest optimala konfigurationen av en mekanisk struktur och ett ställdon. Klassisk struktur (gångjärnstypen) jämförs med den morfande strukturen och det klassiska servot jämförs med den elektromagnetiska aktuatorn. I kombination med varandra formar de två strukturerna och två aktuatorerna fyra konfigurationer som evalueras med avseende på responstid, energiförbrukningen, volymen av lösningen och den maximala roderkraften. Arbetsprocessen är uppdelad i fyra huvuddelar. Hydrodynamiska beräkningar för att få ut momentet som rodret behöver motstå. CAD design av varje konfiguration, inkluderande strukturella- och aktuatorstudier. Tillverkning av prototyper för att verifiera teoretiska resultat. Summering och presentation av informationen med avseende på evalueringsparametrar. Slutsatserna av studien visar optimal konfiguration mot respektive evalueringsparameter. Servo i kombination med den klassiska gångjärnsstrukturen är mest energieffektiv. Den elektromagnetiska aktuatorn tillsammans med gångjärnsstrukturen har minst volym. Servo tillför den maximala roderkraften och den elektromagnetiska aktuatorn har snabbast responstid. Författaren rekommenderar kombinationen av servot och den mofrande strukturen för implementering vid utveckling av det mindre FoilCart fartyget. Kombinationen har stora hydrodynamiska fördelar, högst maximal roderkraft och liten volym. Implementeringen skulle innebära ett första steg för utvecklingen av morfande struktur inom bärplan. Varje konfiguration har sina för- och nackdelar och därför ska noga undersökas vid val av struktur / aktuator i andra applikationer.
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Algarp, Caroline, and Astrid Svanfeldt. "Optimal configuration for a bio-solar-wind polygeneration system in Klintehamn." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264532.
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This project concentrates on the energy flows of Klintehamn and examines if it is possible for Klintehamn to be self-sufficient in the future. To reach this goal, the energy flows in Klintehamn must be analyzed. Subsequently, a new improved energy flow has been designed, where other renewable energy sources are included. Klintehamn is an urban area on the Swedish island of Gotland. An industrial park is established in the harbour of Klintehamn, and currently a sawmill, a fodder production facility and a few wind turbines are located in the area. A program, Program Klintehamn 2030, outlines opportunities to develop Klintehamn in many areas. The goals for Klintehamn are to increase the use of renewable energy sources and decrease greenhouse gas emissions. More specifically, this includes building a biogas plant by evolving the already established sewage treatment plant, and increasing the use of renewable energy sources such as wind and solar energy. Models of the Current Energy System and the Improved Energy System have been designed during the project. Calculations of the Current Energy System have been made and for the Improved Energy System, seven scenarios have been constructed. The calculations program, Matlab, has been used for all calculations. The following scenarios have been modeled in this project: • Scenario 1 - Development of biogas • Scenario 2 - Increased wind power • Scenario 3 - Development of solar park • Scenario 4 - Development of solar panels • Scenario 5 - Combination 1, scenario 1-4 added into one system • Scenario 6 - Combination 2, 100% renewable energy • Scenario 7 - Combination 3, development of Scenario 5, with more renewable energy In the Current Energy System, the total yearly energy demand is 3.423 TWh, where 3.405 TWh is electricity and 18.2 GWh is heat. The future demand of electricity and heat will be 3.407 TWh and 265 GWh per year, respectively. Scenario 5 is the first combined scenario, where the current energy and all renewable energy sources are included. The generated electricity in that scenario is not enough to satisfy the electricity demand. Scenario 6 consists of 100% renewable energy sources. To achieve the energy demand of Klintehamn all the renewable energy sources have been maximized in order to become self-sufficient. It generated an absurd result, which was far from realistic. Scenario 7 is an expansion of Scenario 5 but with more renewable energy. All energy sources have been expanded and Scenario 7 generates 108 GWh of electricity. Scenario 5 and Scenario 7 are two reasonable scenarios with reasonable amounts of renewable energy installed, but with different levels of ambition. The conclusion of the project is that, it is possible to improve the current energy system. The energy system can become more sustainable and fossil energy sources can be removed and replaced by renewable energy sources. In order for Klintehamn to be self-sufficient, more energy sources must be included, for example wave power.<br>Det här projektet handlar om energiflödet i Klintehamn och hur Klintehamn i framtiden ska kunna bli självförsörjande. För att kunna göra detta måste dagslägets energiflöde i Klintehamn utvärderas. Därefter har ett nytt förbättrat energiflöde konstruerats, där andra förnybara energikällor är inkluderade. Klintehamn är en tätort på den svenska ön Gotland. En industripark är etablerad i Klintehamns hamnområde, och för närvarande är ett sågverk, en foderproduktionsanläggning samt ett fåtal vindkraftverk befintliga i området. Ett program, Program Klintehamn 2030, har tagits fram, då det finns möjligheter att utveckla Klintehamn på många områden. Mål, för att Klintehamn ska ¨oka användande av förnyelsebar energi och sänka sina koldioxidutsläpp i framtiden, har utvecklats. Några specifika mål är att det ska byggas en biogasanläggning i anknytning till det befintliga reningsverket, samt att utöka användningen av förnybara energikällor så som vind och solenergi. Modeller på dagens energisystem och ett utvecklat energisystem i framtiden har konstruerats under projektets gång. Därefter har beräkningar av dagens energisystem gjorts och för framtida systemet har ett antal scenarion byggts upp och beräknats på. Alla beräkningar har gjorts med hjälp av beräkningsprogramet Matlab. Scenariona i detta projekt är följande: • Scenario 1 - Utveckling av biogas • Scanario 2 - Utökning av vindkraften • Scenario 3 - Utveckling av solpark • Scenario 4 - Utveckling av solpaneler • Scenario 5 - Kombination 1, scenario 1-4 adderat till ett system • Scenario 6 - Kombination 2, 100% förnybar energi • Scenario 7 - Kombination 3, utveckling av Scenario 5, med mer förnyelsebar energi I det nuvarande energisystemet är den totala årliga efterfrågan av energi 3.423 TWh, varav 3.405 TWh ¨ar elektricitet och 18.2 GWh är värme. Den framtida efterfrågan av electricitet och värme kommer vara 3.407 TWh respektive 265 GWh per år. Scenario 5 är det första kombinerade scenariot, där alla förnybara energikällor är inkluderade. Den genererade elektriciteten i det scenariot är inte tillräcklig för att nå efterfrågan. Scenario 6 består av 100% förnybara energikällor. För att uppnå Klintehamns energibehov har alla förnybara energikällor maximerats för att kunna bli självförsörjande. Det genererade ett absurt resultat, som var långt från rimligt. Scenario 7 är en påbyggnad av Scenario 5, med ännu mer förnyelsebar energi. Alla energikällor har utökats och Scenario 7 genererar 108 GWh elektricitet. Scenario 5 och Scenario 7 är två rimliga scenarion med rimliga mängder förnybara energikällor installerade, men med olika ambitionsnivåer. Så slutsatsen av projektet är att det går att förbättra det nuvarande energisystemet. Energisystemet kan bli mer hållbart och fossila energikällor kan fasas ut och i stor utsträckning ersättas med förnybara energikällor. För att Klintehamn ska kunna bli självförsörjande måste fler energikällor inkluderas, till exempel vågkraft.
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Brookes, Christopher J. "A genetic algorithm for designing optimal patch configurations in GIS." Thesis, University College London (University of London), 1998. http://discovery.ucl.ac.uk/1348850/.
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Geographical Information Systems (GIS) are used for several types of spatial planning but so far they have not been used for optimal patch design. Optimal patch design is a generic spatial problem in which the objective is to design spatially explicit landuse maps when both the composition and configuration of patches are important criteria. There are many applications in conservation, forestry management, watershed management and the management of large military estates. This thesis describes a new autonomous computer program, the genetic algorithm for optimal patch design (GAPD). GAPD combines four components: a genetic search algorithm, a parameterised region growing (PRG) program, raster GIS measurement functions and multi-criteria decision-making methods. The key component is the PRG which translates between the aspatial domain of the search algorithm and the spatial domain of the GIS. GAPD generates landuse maps that optimise the configuration and composition of patches to meet multiple objectives for a given set of input maps and criteria. The theories of landscape ecology are used to establish a framework for formulating optimal patch design problems. The thesis describes the conceptual design of GAPD and its implementation and test, first as a prototype for solving single patch problems and then as a fully functional system for solving multi-objective multi-patch problems. The feasibility of GAPD was established by investigations of issues concerning the representation and measurement of configuration in raster data structures and by testing the efficiency and effectiveness of GAPD with simple problems. GAPD was further evaluated in five hypothetical problems designed to cover a range of different scenarios. The results are promising and show that GAPD has potential as a decision support tool. The final section recommends a number of topics for further research covering technical developments of GAPD, the application of GAPD to real problems and investigations of general issues of optimal patch design.
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Nebaeus, Tobias. "Optimal Scaling Configurations for Microservice-Oriented Architectures Using Genetic Algorithms." Thesis, Umeå universitet, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-164765.
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Genetic algorithms (GAs) are a powerful tool for solving multi-objective optimization problems. Resource allocation and scaling of cloud systems typically involve multiple conflicting objectives, such as high through putin the presence of failures, cost, and reduced latency. Microservice-based architectures introduce additional complexities since the underlying services respond differently to different workloads. In this work, the performance of two multi-objective GAs is compared on the problem of finding efficient scaling configurations of a microservice-based architecture. Results show that while the use of GAs is effective at finding efficient configurations, GAs can not be used for larger systems involving many microservices or for systems that make use of caching.
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Wei, Quantum Jichi. "Two-stage reverse osmosis : optimal element configuration and flux distribution, energy savings." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111900.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 57-59).<br>In a two-stage reverse osmosis (RO) system of finite size, there are two degrees of freedom not present in a single-stage RO system: distribution of RO elements between the two stages (system design), and feed pressures (system operation). In this study, we investigate the optimal system design and operation of a two-stage RO system with a mass-balance model and establish a lower bound for the energy savings achieved by the optimized two-stage system compared to a single-stage system. A two-stage RO system may consume more or less energy than a single-stage RO system of the same size and freshwater productivity, depending on the first-stage feed pressure and second-stage feed pressure. To minimize energy consumption, feed pressures should be chosen to minimize spatial variance in flux. The optimal element configuration places at least half the elements in the first stage; the exact configuration depends on feed salinity, recovery ratio, and membrane permeability. The greatest energy savings are achieved with a two-stage RO system that has both optimal element configuration and feed pressures. More energy can be saved by adding a stage when the thermodynamic least work of separation is larger. For a given feed salinity, energy savings from adding a second stage grow as recovery ratio increases. Brackish water feeds must be taken to high recovery ratios to achieve substantial energy savings; comparable savings can be achieved at lower recovery ratios for higher salinity feeds. We find that significant energy can be saved with the simplest two-stage RO design, at a system flux similar to today's RO plants and accounting for the effects of concentration polarization.<br>by Quantum J. Wei.<br>S.M.
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Sixt, Pierre. "Étude et réalisation de capteurs à fibre optique en configuration Fabry-Pérot." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0064.
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La première partie de ce travail concerne l'étude et la réalisation de microstructures sur verre de type fabry-perot, en extrêmité de fibre optique. Nous rappelons tout d'abord le fonctionnement théorique des cavités, et les différents facteurs pouvant affecter les performances d'un résonateur de bas ordre, et nous décrivons le système de référençage spectral choisi ; nous présentons ensuite les résultats obtenus avec différentes méthodes d'assemblage des cavités: fixation organique, thermocompression, anodic bonding, cette dernière methode ayant donné le plus de succès. Dans une seconde partie, nous nous intéressons à des cavités fabry-perot radiofréquence, utilisant une modulation en bande de base de la porteuse optique ; deux formalismes de calcul de ces cavités sont décrits, leur utilisation pour la mesure de déphasages optiques est abordée, enfin nous présentons les résultats expérimentaux obtenus sur le référençage de capteurs de distance et de pression en extrêmité de fibre
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Channoufi, Malèk. "Modélisation et optimisation de la couche optique de réseaux sur puce." Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0692/document.
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Dans le cadre du développement de SoC (Systems-on-Chip) complexes, l'interconnexion des différent IP matériels (Intellectual Property), très distants à l'échelle d'un circuit intégré (typiquement quelques centimètres) et devant s'échanger des volumes de données parfois important, incite, pour des raisons de débit, de latence, de pertes et de consommation, l'adoption d'une méthodologie de conception adéquate pour réaliser des systèmes de plus en plus flexibles. Afin de répondre à ces nouvelles difficultés de conception, de nombreuses recherches ont fait émerger le concept de réseau optique sur puce (Optical Network-on-Chip ou ONoC).Dans cette thèse une étude détaillée d'une nouvelle architecture d'un réseau optique sur puce a été faite. La conception de ce réseau repose sur 2 paradigmes d'interconnexion: concevoir l'architecture dans le cadre d'une puce en 3D et l'empilement en plusieurs niveaux des guides d'onde optique dans la couche réseau optique sur puce. L'élément clef de cette architecture est un microrésonateur à plusieurs niveaux de guide d'onde (Si/SiO2). De ce fait, une étude détaillée sur le comportement optique de ce composant avec des modèles mathématiques et des simulations FEM a été faite dans le but d'optimiser la perte de puissance optique, le nombre des niveaux des guides d'onde empilés et la consommation d'énergie.Après avoir détaillé le fonctionnement de réseau multi-niveaux sur puce proposé "OMNoC", son protocole de routage a été étudié avec le simulateur NS-2, puis optimisé, rédiger et étudier avec C++ et l'outil Parsec Benchmark. Enfin et en tenant compte des études faites sur le comportement optique des guides d'onde et le protocole de routage, une étude desperformances comparatives avec des autres architectures a été élaborée montrant ainsi les avantages et les limites d'une telle méthodologie d'interconnexion<br>The developing of complex System on Chip "SoC" interconnecting different cores IP distant in micrometer chip scale, needs important data bandwidth , low latency and the best compromise between optical power loss and crosstalk. According to that, finding new methodology design is necessary to cope to those challenges.Using centric communication becomes the mainly solution to improve communication performance in system on chip and recently many researches are focusing on Optical Network on Chip 'ONoC'.In this thesis, a novel architecture of an optical network on chip is proposed, this architecture is reposed on 2 design paradigms: ONoC based 3D chip and multilevel waveguides based ONoC. The key element of this architecture is the multilevel microresonator (Si/SiO2) which is the optical switch of the network. Optical wave behavior in different geometries have been studied using FEM method in order to find compromise between optical power loss and crosstalk. Operation mode of this ONoC called "OMNoC" is explained, routing protocol is studied using NS-2 simulator too, then optimized and developed using C++ and Benchmark tool. After that and by using FEM results and adopted routing strategy, OMNoC performances are studied and compared with other network architectures proposed in ONoC literature. In conclusion and according to performances analysis and comparisons, OMNoC could be considered as a promising network architecture which offer scalability and give a compromise between optical power loss and crosstalk
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Herry, Ronan. "Contributions to functional inequalities and limit theorems on the configuration space." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1134/document.
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Nous présentons des inégalités fonctionnelles pour les processus ponctuels. Nous prouvons une inégalité de Sobolev logarithmique modifiée, une inégalité de Stein et un théorème du moment quatrième sans terme de reste pour une classe de processus ponctuels qui contient les processus binomiaux et les processus de Poisson. Les preuves reposent sur des techniques inspirées de l'approche de Malliavin-Stein et du calcul avec l'opérateur $Gamma$ de Bakry-Émery. Pour mettre en œuvre ces techniques nous développons une analyse stochastique pour les processus ponctuels. Plus généralement, nous mettons au point une théorie d'analyse stochastique sans hypothèse de diffusion. Dans le cadre des processus de Poisson ponctuels, l'inégalité de Stein est généralisée pour étudier la convergence stable vers des limites conditionnellement gaussiennes. Nous appliquons ces résultats pour approcher des processus Gaussiens par des processus de Poisson composés et pour étudier des graphes aléatoires. Nous discutons d'inégalités de transport et de leur conséquence en termes de concentration de la mesure pour les processus binomiaux dont la taille de l'échantillon est aléatoire. Sur un espace métrique mesuré quelconque, nous présentons un développement de la concentration de la mesure qui prend en compte l'agrandissement parallèle d'ensembles disjoints. Cette concentration améliorée donne un contrôle de toutes les valeurs propres du Laplacien métrique. Nous discutons des liens de cette nouvelle notion avec une version de la courbure de Ricci qui fait intervenir le transport à plusieurs marginales<br>We present functional inequalities and limit theorems for point processes. We prove a modified logarithmic Sobolev inequalities, a Stein inequality and a exact fourth moment theorem for a large class of point processes including mixed binomial processes and Poisson point processes. The proofs of these inequalities are inspired by the Malliavin-Stein approach and the $Gamma$-calculus of Bakry-Emery. The implementation of these techniques requires a development of a stochastic analysis for point processes. As point processes are essentially discrete, we design a theory to study non-diffusive random objects. For Poisson point processes, we extend the Stein inequality to study stable convergence with respect to limits that are conditionally Gaussian. Applications to Poisson approximations of Gaussian processes and random geometry are given. We discuss transport inequalities for mixed binomial processes and their consequences in terms of concentration of measure. On a generic metric measured space, we present a refinement of the notion of concentration of measure that takes into account the parallel enlargement of distinct sets. We link this notion of improved concentration with the eigenvalues of the metric Laplacian and with a version of the Ricci curvature based on multi-marginal optimal transport
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Tokić, Grgur. "Optimal configuration of large arrays of floating bodies for ocean wave energy extraction." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104198.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 257-263).<br>Ocean wave energy is a large, and mostly untapped potential source of renewable energy worldwide. The scope of engineering solutions for harvesting wave energy is vast, ranging from wave-induced oscillating bodies, to overtopping devices and oscillating water columns. One particularly interesting approach to energy harvesting is to use arrays of oscillating bodies. The advantage of such a solution lies in potential amplification of the wave field through the interactions of waves that are diffracted and radiated by the bodies. Recent examples from other fields of physics (e.g. photonics crystals) show that by carefully engineering the configuration of the array, it is possible to greatly improve its performance. This thesis studies the performance of large arrays of axisymmetric bodies through the use of multiple scattering formulation of wave interactions. The focus is on the energy extraction characteristics in particular, but the effects on mean drift force are also studied. The multiple scattering (MS) formulation for Wave Energy Converter (WEC) arrays is extended in three areas. First, the dynamical behavior of a body in an array is decoupled from the dynamics of the array as a whole. This allows for the dynamical characteristics of a body to be completely determined in isolation, and then used in an array setting through newly-formed dynamical transfer matrices. This approach is especially beneficial in optimization studies, where the changes in the spatial array configuration do not require the recalculation of the hydrodynamic characteristics of an array. Second, the non-linear mean drift force on an array is expressed in terms of newly-formed non-linear drift transfer matrices. Lastly, a theoretical formulation is developed for periodic arrays with closely-spaced rows of bodies so that they can be analyzed in an exact manner within the MS formulation. Based on these extensions, a fast computational algorithm is developed that is capable of handling large arrays (0(100) bodies) of different configurations (general finite-size arrays, periodic arrays, periodic arrays of subarrays). The algorithm imposes no constraints on the body-size-to-wavelength ratio or on the inter-body spacings. Using this algorithm, a series of systematic studies of energy extraction characteristics by different array configurations is performed (as a function of wavenumber and wave incoming angle). These array configurations can be described with at most two parameters. In particular, the study of periodic and uniformly spaced line arrays reveals that large gains occur before new scattering orders appear (at Rayleigh wavelength). The gains are particularly large for super-resonant wavenumbers where there is still significant energy extraction. The studies of rectangularly arranged arrays show that, while still related to Rayleigh wavelengths, the optimal spacing is governed by the emergence of higher scattering orders. In all cases, arrays arranged in the direction of array propagation (attenuator arrays) perform poorly, except for sub-resonant wavenumbers. The effect or spacing irregularity (linear, quadratic and random) is studied on terminator arrays. The performance of irregularly spaced arrays as a function of wavenumber is more uniform, without high peaks in performance, and it indicates that there is a trade-off between high array gain and broad-bandedness of array gain. Finally, optimization of spatial configuration of a series of large arrays (up to 200 bodies) is performed. The array configuration is parameterized such that it can be described by a small number of variables, but that still allows a large number of different configuration types (irregularities in body spacings). Gradients of objective functions (extracted energy, array gain, drift force) are obtained using the adjoint method that, by also employing matrix-free matrix-vector multiplications, leads to a fast, memory-efficient gradient-based optimization algorithm. The optimization is performed for regular and irregular seas. The optimized rectangular arrays lead to high array gains, especially for mildly super-resonant wavenumbers where it reaches values of over 4. Surprisingly, uniformly spaced rectangular arrays perform better than the irregularly spaced ones in both regular and irregular seas. For many optimized arrays, the array capture width (extraction cross-section) is equal to the geometrical extent (cross-section) of the array, indicating that these arrays harvest all the energy of a particular frequency incoming on the spatial area they occupy. The optimal configurations are analyzed from a physical standpoint and compared to other structured arrays in physics. The results overall provide guidelines on the possible future design of WEC arrays.<br>by Grgur Tokić.<br>Ph. D.
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DUPONT, DE DINECHIN PAUL. "Design of a methodology to identify optimum PV configurations for small-scale modular solutions for tropical conditions." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280469.
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The development of small-scale solar photovoltaic (PV) power plants is accelerating in most isolated regions, such as the Caribbean. Indeed, they offer a beneficial, ecological and modular alternative to reduce the important fossil fuel dependency of these countries. However, since modules are facing a harsh environment in these areas, the PV project configuration cannot follow the same rules as in a “classical” PV project: the project specifications and design techniques are different as more constraints must be taken into consideration. Therefore, designing PV configurations for such projects requires a specific methodology adapted to the tropical and cyclonic conditions. This thesis work aims to design such a methodology for a 100 kWc solar shed: using the available literature on PV modules’ behavior under tropical conditions, a set of adapted specifications is defined, and several technical components are selected followingly. A cost analysis is undertaken and assesses the total CAPEX (∼220,000 €) and the OPEX (5,650 €/year) of the project. In order to select the module that fits best the customer’s requirements, an economical and ecological grading system is used, this choice is followed by the PV field design. The project performance is assessed using PVSyst, and the results are used to compute the different economic indicators using a MATLAB program. This methodology is tested on a real case study, the main outputs are total yield of 166.0 MWh, capacity factor of 0.19, project LCOE of 147.93€/MWh, IRR of 5.35% and a potential annual rent to the customer equal to 2,900€/year. Several sensitivity analyses are conducted to judge and explore the potential enhancements to this methodology, it appears that the ecological grading index definition should be modified, and that orientation and inverter choice optimization could be added to the methodology as long as they don’t add too much complexity.<br>Utvecklingen av småskaliga solceller (PV) kraftverk accelererar i de flesta isolerade regioner, till exempel Karibien. De erbjuder faktiskt ett fördelaktigt, ekologiskt och modulärt alternativ för att minska det viktiga fossilbränsleberoendei dessa länder. Men eftersom moduler står inför en hård miljö inom dessa områden kan inte PV-projektkonfigurationen följa de samma reglerna som i ett ”klassiskt” PV-projekt: projektspecifikationerna och designteknikerna är olika eftersom fler tryck måste beaktas. Därför krävers en specifik metod anpassad till de tropiska och cykloniska förhållandena för att utforma PV-konfigurationer för sådana projekt. Detta master uppsats syftar till att utforma en sådan metod för en 100 kWc solskjul: med hjälp av tillgänglig litteratur om PV-modulers beteende under tropiska förhållanden definieras en uppsättning anpassade specifikationer och flera tekniska komponenter väljs därefter. En kostnadsanalys genomförs och utvärderar projektets totala CAPEX (∼220 000 €) och OPEX (5 650 € / år). För att välja den modul som passar bäst kundens krav används ett ekonomiskt och ekologiskt betygssystem; PV-fältdesignen väljs sedan. Projektets prestanda bedöms med hjälp av PVSyst, och resultaten används för att beräkna de olika ekonomiska indikatorerna med ett MATLAB-program. Denna metod testas på en riktig fallstudie, huvudutgångarna är: totalavkastning på 166,0 MWh, kapacitetsfaktor 0,19, projekts LCOE på 147,93 € / MWh, IRR på 5,35% och en potentiell årlig hyra till kunden på 2 900 € /år. Flera känslighetsanalyser genomförs för att bedöma och utforska de potentiella förbättringarna av denna metod, det verkar som att den ekologiska graderingsindexdefinitionen bör ändras, och att orientering och växelriktaresvaloptimering skulle kunna läggas till metoden så länge de inte komplicerar den för mycket.
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Babalola, Olusola. "OPTIMAL CONFIGURATION FOR NODES IN MIXED CELLULAR AND MOBILE AD HOC NETWORK FOR INET." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604404.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada<br>As part of Morgan’s iNET development, the Mixed Cellular and Mobile Ad hoc Network (MCMN) architecture has been 1proposed to provide coverage to over-the horizon test articles. Nodes in MCMN are assigned to one of three possible modes- Ad hoc, Cellular or Gateway. We present architecture for the proposed MCMN and some performance analysis to characterize the network. The problem of organizing nodes in this mixed network with optimal configuration is significant. This configuration gives nodes ability to know the best mode to operate and communicate with other nodes. Node organization is critical to the performance of the mixed network and to improve communication. The configuration of nodes required to optimally organize nodes in MCMN is demonstrated. The problem of evaluating configuration parameters for nodes in a mixed network is a nonlinear and complex one. This is due to the various components like the number of nodes, geographical location, signal strength, mobility, connectivity and others that are involved. Clustering techniques and algorithms have been used in literature to partition networks into clusters to support routing and network management. A clustering technique is employed to dynamically partition the aggregate network into Cluster Cells (CCs). A gateway node is selected for each CC which relays traffic from the cellular to the Ad hoc and vice versa. A trade-off analysis of the cellular boundary is presented using the maximum of the minimum data rate in the network. Numerical analysis and experiments are provided to show that the coverage can be extended to test articles in over-the-horizon region. It is also shown that, when the network is well organized, performance is improved.
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Karamzadeh, Toularoud Nasim [Verfasser], Torsten [Akademischer Betreuer] Dahm, and Frank [Akademischer Betreuer] Krüger. "Earthquake source and receiver array optimal configuration / Nasim Karamzadeh Toularoud ; Torsten Dahm, Frank Krüger." Potsdam : Universität Potsdam, 2020. http://d-nb.info/1218795271/34.
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Wallace-Finney, Sheena R. "Determining the Optimal Aisle-Width for Order Picking in Distribution Centers." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1312569054.
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Anthony, Ikenna O., Geev Mokryani, Rana H. A. Zubo, and O. A. Ezechukwu. "Distribution Network Reconfiguration Considering Security-Constraint and Multi-DG Configurations." IEEE, 2020. http://hdl.handle.net/10454/18492.
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Yes<br>This paper proposes a novel method for distribution network reconfiguration considering security-constraints and multi-configuration of renewable distributed generators (DG). The objective of the proposed method is to minimize the total operational cost using security constrained optimal power flow (SCOPF). The impact of multi-configuration of renewable DGs in a meshed network is investigated. In this work, lines were added to the radial distribution network to analyse the network power flow in different network configurations. The added lines were connected to the closest generator bus which offered least operating cost. A 16-bus UK generic distribution system (UKGDS) was used to model the efficiency of the proposed method. The obtained results in multi-DG configuration ensure the security of the network in N-1 contingency criteria.
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Li, Ming Jun. "Génération de deuxième harmonique en configuration "Cerenkov" dans les guides d'ondes réalisés par échange protonique dans le niobate de lithium." Nice, 1988. http://www.theses.fr/1988NICE4210.
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Description d'un nouveau procédé de fabrication de guides d'ondes en niobate de lithium (LiNbO indice 3) le double échange protonique qui permet d'obtenir des guides de meilleure qualité. Modélisation de l'interaction non linéaire d'une onde fondamentale guidée et d'une onde harmonique rayonnée, baptisée configuration "Cerenkov", pour le calcul du champ harmonique et du rendement de conversion
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Kuntz-Sliwa, Laure. "Optimisation de la configuration multicapteurs donnée : fusion pixel." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT023H.
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L'amelioration de la perception passe par la prise en compte d'un plus grand nombre d'informations. Cette these a pour objet de montrer comment les regrouper au mieux. Une methode analytique est proposee pour fusionner les informations issues de plusieurs capteurs afin d'ameliorer les performances de la detection d'une cible sur un fond. Nous proposons generalement de maximiser le critere de fisher a partir des statistiques du premier et du deuxieme ordre des signatures spectrales de la cible et du fond. Une analyse de la robustesse de notre methode est developpee a partir de la physique de la mesure. Deux applications aux images multispectrales spot et aviris montrent les performances de notre methode et son aptitude a detecter des cibles sub-pixels
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Papagiannakis, Konstantinos. "Optimal artificial boundary condition configurations for sensitivity-based model updating and damage detection." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5143.
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Approved for public release; distribution is unlimited<br>Frequently, in structural system identification (model updating or damage detection), the available set of data is incomplete, both spatially and in modal content. This incompleteness leads to the solution of underdetermined linear systems. In order to improve the identification, additional independent measured data must be found. In the past, it has been shown that such data can be easily obtained from the application of Artificial Boundary Conditions (ABC), imposed on both the baseline FE models and the measured frequency response data. This can be accomplished without any physical modifications to the experiment and, hence, no additional expense on different systems, or more than once, in order to get the modal data needed for the analysis. In this thesis, the procedure of sensitivity-based structural system identification, using ABCs, and enhanced by parameter grouping/clustering, is examined. It is shown that the optimal sensitivity matrix is a square and diagonal dominant one, which can be used with quite accurate results both for localization of parameter errors, and the determination of the magnitude of parameter error. The numerous ABC configurations available, even from a small measured data set, allow an optimal sensitivity matrix to be found for many parameters. These concepts are demonstrated using simulated measurements along with finite element models.
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Timmermann, Barth. "Residential development opportunities in New Braunfels, Texas : optimal development densities and unit configurations." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/70299.
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Vernon, Russell A. "Discovering optimal unit cell configurations when designing for additive manufacturing using lattice structures." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10108174.
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<p> According to Wohlers Report 2014, the worldwide 3D printing industry is now expected to grow from $3.07B in revenue in 2013 to $12.8B by 2018, and exceed $21B in worldwide revenue by 2020. With 3D printing rapidly evolving from a prototype commodity to a means to produce full production items, lattice structures are becoming of great interest due to their superior structural characteristics and lightweight nature. Within design, lattice structures have typically been defined by preset beam configurations within a cube. Certain configurations have been proven analytically to be optimal for certain load functions, but never has there been optimization performed to discover or verify the optimal lattice shapes and sizes within a predefined cubic space. By performing optimization on these cubic cells, a design guideline can be created for designers of lattice structures. In this thesis, several lattice configurations are analyzed both from a micro level (single unit cell) as well as a macro level (a simple series of unit cells). Optimization is performed with respect to stiffness and compliance to identify strategic configurations for bending, torsion, compression and tension. Only cubic base cells are analyzed (i.e. no hexagonal). Knowing optimal lattice configurations from a structural standpoint enables designers to further reduce weight and increase structural efficiencies when designing for additive manufacturing. The results of this study yield a well-defined guideline for design engineers to utilize when lattice structures are incorporated in a structural design. With this design guideline information available to design engineers, further utilization of lattice structures can be exploited by efficiently applying strategic unit cell configurations to the overall design.</p>
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Bonnand, Romain. "Le détecteur d'ondes gravitationnelles Advanced Virgo : Étude de la configuration optique et développement des miroirs." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00797350.
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Les ondes gravitationnelles ont été prédites par Einstein dans sa théorie de la Relativité Générale. Elles sont des perturbations de l'espace-temps que l'on essaie de mettre en évidence par interférométrie laser. Les détecteurs sont des interféromètres de Michelson de plusieurs km de long combinés avec des cavités Fabry- Perot afin d'augmenter la sensibilité de l'instrument. La première génération de détecteurs (Virgo, LIGO, GEO) n'a pas permis d'obtenir une détection directe malgré plusieurs phases d'observations en coïncidence à la sensibilité prévue. Une seconde génération de détecteurs est actuellement en préparation avec notamment le projet européen Advanced Virgo qui devrait avoir une sensibilité améliorée d'un ordre de grandeur. Cette thèse s'intéresse dans un premier temps aux effets de lentille thermique due à la haute puissance contenue dans les cavités Fabry-Perot pour différentes configurations optiques de l'interféromètre. Par la suite, nous nous intéresserons aux miroirs qui composent les cavités Fabry-Perot depuis la définition des besoins en termes de planéité à la réalisation de cette planéité et à sa mesure. La planéité de ces miroirs doit être sub-nanométrique de façon à limiter les pertes optiques dans les cavités Fabry-Perot et ainsi réduire les effets du bruit de photons et de la lumière diffusée. Nous verrons la réalisation de la correction de la planéité des substrats par la technique dite du traitement correctif. Nous étudierons aussi l'uniformité du dépôt des couches minces diélectriques nécessaires à l'obtention de surface hautement réfléchissante avec en particulier l'étude du mouvement planétaire des substrats dans la machine de dépôts.
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Proffitt, Donnie E. II. "EXPERIMENTAL INVESTIGATION TO INFORM OPTIMAL CONFIGURATIONS FOR DYNAMIC NEAR-FIELD PASSIVE UHF RFID SYSTEMS." UKnowledge, 2013. http://uknowledge.uky.edu/me_etds/29.
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RFID has been characterized as a “disruptive technology” that has the potential to revolutionize numerous key sectors. A key advantage of passive RFID applications is the ability to wirelessly transmit automatic identification and related information using very little power. This paper presents an experimental investigation to inform the optimal configuration for programming passive ultra-high frequency (UHF) RFID media in dynamic applications. Dynamic programming solutions must be designed around the tag’s functionality, the physical programming configuration and environment. In this investigation, we present a methodology to determine an optimal configuration to maximize the systems programming efficiency for dynamic applications.
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Dieulangard, Anthony. "Nouvelles configurations d'interaction pour l'optimisation conjointe des performances des composants acouto-optiques." Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0027/document.
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Une description des différentes configurations d’interaction ayant lieu dans les matériaux usuellement employés dans le domaine acousto-optique est proposée. Un exemple d’application illustre les caractéristiques déterminantes propres à chaque fonction que permet l’interaction acousto-optique, à savoir la modulation, la déviation, le décalage en fréquence et le filtrage d’un faisceau optique. Cette thèse est plus particulièrement consacrée aux interactions acousto-optiques anisotropes dans le cristal de Paratellurite, matériau majoritairement employé pour les applications de déflexion et de filtrage de par ses qualités photo-élastiques remarquables et son large domaine de transparence optique. Ces propriétés optiques, acoustiques et acousto-optiques sont décrites en détail. Nous nous intéressons plus particulièrement aux caractéristiques de l’interaction NPM (Narrow Phase Mismatch) et TPM (Tangent Phase Mismatch), respectivement employées pour le filtrage et la déflexion. Ceci nous conduit à l’étude de la bande passante spectrale d’un déflecteur et de sa potentielle application en tant que réseau de diffraction à bande passante et périodicité spatiale modulable. Ensuite nous proposons la mise en cascade d’un déflecteur et d’un filtre dans le but de concevoir un décaleur de fréquence variable à faible décalage. Enfin, nous proposons une configuration originale pour répondre aux contraintes d’utilisation rencontrées avec l’interaction NPM pour les applications de filtrage. La conception et la réalisation d’un composant multiélectrodes à interaction double est alors présentée dans la gamme spectrale [400; 650 nm]. La configuration proposée permet à la fois de réduire de 50% l’intensité des lobes secondaires tout en homogénéisant la bande passante optique du filtre sur sa bande spectrale de travail<br>The different configurations of acousto-optic interactions taking place in usual employed materials are presented. For each function (modulation, deflection, shifting and filtering), an exemple of application highlights the decisive characteristics of the component. This thesis is particularly devoted to the anisotropic interactions occuring in Paratellurite crystal. Such material is widely used for filtering and deflection applications due to its high figure of merit and also for its large optical transparency domain, from Ultra-Violet to Infra-Red. Optical, acoustical and acoustooptical properties of Paratellurite cristal are detailed. More precisely, we are interested in anisotropic interactions, in particular NPM (Narrow Phase Mismatch) and TPM (Tangent Phase Mismatch), respectively employed for Acousto-Optic Tunable Filters (AOTF) and Acousto-Optic Deflectors (AOD). This leads to the study of the optical bandwidth of a deflector with a potential application as a tunable transmissive grating beam splitter for multiple laser line separation. Then, we propose to cascade an AOTF with an AOD in order to get a wide bandwidth tunable optical low frequency shifter. Finally, we present the design and fabrication of a multi-transducer component based on dual anisotropic interaction in the visble spectral range, from 400 to 650 nm. A significative reduction of sides lobes is observed (-50%) with an homogenisation of the optical bandwidth of the filter on its spectral working range
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Guo, Chuanliang. "Effects of turbulence modelling on the analysis and optimisation of high-lift configurations." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7220.
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Due to the significant effects on the performance and competitiveness of aircraft, high lift devices are of extreme importance in aircraft design. The flow physics of high lift devices is so complex, that traditional one pass and multi-pass design approaches can’t reach the most optimised concept and multi-objective design optimisation (MDO) methods are increasingly explored in relation to this design task.
The accuracy of the optimisation, however, depends on the accuracy of the underlying Computational Fluid Dynamics (CFD) solver. The complexity of the flow around high-lift configuration, namely transition and separation effects leads to a substantial uncertainty associated with CFD results. Particularly, the uncertainty related to the turbulence modelling aspect of the CFD becomes important. Furthermore, employing full viscous flow solvers within MDO puts severe limitations on the density of computational meshes in order to achieve a computationally feasible solution, thereby adding to the uncertainty of the outcome. This thesis explores the effect of uncertainties in CFD modelling when detailed aerodynamic analysis is required in computational design of aircraft configurations. For the purposes of this work, we select the benchmark NLR7301 multi-element airfoil (main wing and flap). This flow around this airfoil features all challenges typical for the high-lift configurations, while at the same time there is a wealth of experimental and computational data available in the literature for this case.
A benchmark shape bi-objective optimization problem is formed, by trying to reveal the trade-off between lift and drag coefficients at near stall conditions. Following a detailed validation and grid convergence study, three widely used turbulence models are applied within Reynolds-Averaged Navier-Stokes (RANS) approach. K- Realizable, K- SST and Spalart-Allmaras. The results show that different turbulent models behave differently in the optimisation environment, and yield substantially different optimised shapes, while maintaining the overall optimisation trends (e.g. tendency to maximise camber for the increased lift). The differences between the models however exhibit systemic trends irrespective of the criteria for the selection of the target configuration in the Pareto front. A-posteriori error analysis is also conducted for a wide range of configurations of interest resulting from the optimisation process. Whereas Spalart-Allmaras exhibits best accuracy for the datum airfoil, the overall arrangement of the results obtained with different models in the (Lift, Drag) plane is consistent for all optimisation scenarios leading to increased confidence in the MDO/RANS CFD coupling.
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Ottman, M. J., and P. Andrade-Sanchez. "Determination of Optimal Planting Configuration of Low Input and Organic Barley and Wheat Production in Arizona, 2012." College of Agriculture, University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/211137.
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Markets for organic barley and wheat are expanding. A major problem growing organic barley and wheat is controlling the weeds. Organic barley and wheat were grown in conventional 6-inch drill spacing but also in 30 inch spacing so weeds could be cultivated in a study at the Larry Hart Farm near Maricopa. The weed pressure was moderate and the weed biomass was about 16 to 26% of the crop biomass near maturity. The primary weed was canarygrass and the secondary weed was malva. Grain yields of the wheat (durum) were similar regardless of row spacing, but the barley grain yields were 4327 lbs/acre in the 6 inch spacing and 3330 lbs/acre in the 30 inch spacing.
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Alsulaiman, Mohamad, and Najmeh Mohammadi. "Optimal Pitch Distance and Tilt Angleof PV Power Plant for Different Climate." Thesis, Högskolan Dalarna, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:du-35528.
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Finding the optimum inter-row spacing and installation tilt for tilted or ground mounted PV systems is a big issue in designing the large-scale PV systems. Increasing the array spacing leads to higher annual generated energy because of the reduced impact of row-shading, but on the other hand, it increases costs of land purchase/lease and wiring costs. Many compromises between performance and cost should be done to design an optimum large-scaled solar plant. One of the criteria in designing of solar power plants is reducing of LCOE, which reflects the cost of every unit of generated energy. Site locations have large impacts on the optimal design of pitch distance and title angles, but such impacts have not been studied extensively in the existing studies, so it is going to bridge this research gap in this thesis. The main purpose of this research is to investigate the impact of climate conditions on the pitch distance and tilt angle for large-scale PV plant and finding the optimal pitch distance and tilt according to the least cost of production. The impact of climate and meteorological data on the self-shading loss and yield of energy are investigated through a simulation tool, which is PVsyst software here, in different tilt angles and distances between rows. The different climates can be considered by choosing site locations in different latitudes to cover all climate zones. Six cities in temperate climate, three cities in tropic climate and one city in polar climate have been selected. LCOE minimizing is a measure in finding the optimum tilt and pitch distance for a 1 MW solar system installed in different latitudes. In this study the type, size and cost of components have been assumed constant in different climate conditions. There is a wide range of variability in some economic indicators like interest rate and discount rate as well as the cost of land in different climates or even countries in the same climate; then to highlight the impacts of climate conditions on the optimal tilt and pitch distance, these parameters were assumed to be constant in this study. The results show the optimal tilt of angles increases with getting far of equator in a range between 0° and 40° to capture more direct sunlight, and the optimal raw spacing grows in further locations to equator in a range between 4 m to 11 m to reduce self- shading loss. Moreover, the best module configuration for PV arrays (portrait or landscape) can be different in different climates.
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Hatami, Farhad. "Configurations of Wardrop's equilibrium and application to traffic analysis." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/565891.
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This thesis consists of two parts, and the connection between them is the so-called Wardrop's
equilibrium. In the rst part of this thesis, which is the theoretical part, we study the congested
transport dynamics arising from a non-autonomous tra c optimization problem. In this setting, we
prove one can nd an optimal tra c strategy with support on the trajectories of a DiPerna-Lions
ow.
The proof follows the scheme introduced by Brasco, Carlier and Santambrogio in the autonomous
setting, applied to the case of supercritical Sobolev dependence in the spatial variable. This requires
both Lipschitz and weighted Sobolev apriori bounds for the minimizers of a class of integral functionals
whose ellipticity bounds are satis ed only away from a ball of the gradient variable. We are then able
to nd the con guration of Wardrop's equilibrium.
In the second part of this thesis, which is the practical part, we use the established Wardrop's equi-
librium in the theoretical section, in order to optimize the tra c problem in rel-life application. New
OD demand problem formulation is explored which allows the modeler to de ne structural similarity
between the historical and estimated OD matrix while ensuring computationally fast and tractable
solution. Shrinkage regression methods, such as Ridge and Lasso regression, are proposed to de ne
distance function between historical and estimated OD matrix, in order to minimize estimation vari-
ance, and ensure the estimated OD matrix is close to true value. The presented OD estimation models
reduce dimensionality of the OD demand vector, which is crucial when the dimensionality of OD ma-
trix is high, due to high level of zoning system. A new solution approach based on the well-known
gradient descent algorithm is applied to solve the proposed models. Finally, results are tested out on
a real life-size network.
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Jarman, Ben. "Essays in optimal auction design." University of Sydney, 2008. http://hdl.handle.net/2123/4627.
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Doctor of Philosophy (Economics)<br>Auctions are an ancient economic institution. Since Vickrey (1961), the development of auction theory has lead to an extremely detailed description of the often desirable characteristics of these simple selling procedures, in the process explaining their enduring popularity. Given the pervasiveness of auctions, the question of how a seller should engineer the rules of these mechanisms to maximize her own profits is a central issue in the organization of markets. The seminal paper of Myerson (1981) shows that when facing buyers with Independent Private Values (IPVs) a standard auction with a specifically selected reserve price (or prices) is optimal, that is, maximizes a seller's expected profits among all conceivable selling mechanisms. In this model, it is assumed that the buyers have perfect information as to the existence of gains from trade. We shall argue that the consequences of this assumption for the design of the optimal auction are not well understood, which motivates our analysis. The three essays of this thesis relax the `known seller valuation' assumption by examining the optimal auction program when the seller (and principal) holds private information representing her reservation value for the good. In the first essay we provide an original technique for comparing ex ante expected profits across mechanisms for a seller facing N>1 potential buyers when all traders hold private information. Our technique addresses mechanisms that cannot be ranked point-by-point through their allocation rules using the Revenue Equivalence Theorem. We find conditions such that the seller's expected profits increase in the slope of each buyer's allocation probability function. This provides new intuition for the fact that a principal does not benefit from holding private information under risk neutrality. Monopoly pricing induces steep probability functions so the seller/principal benefits from announcing a fixed price, and implicitly her private information. An application is presented for the well known k double auction of the bilateral trade literature. In the second and third essays of this thesis, we extend the above framework to allow for informational externalities. Specifically, we allow for the situation in which the seller's private information represents a common value component in buyers' valuations. Thus the seller's private information (say regarding the quality of the good) is of interest to bidders independently of any strategic effects. In recent work Cai, Riley and Ye (2007) have demonstrated that a seller who holds private information about the quality of a good faces an extra consideration in designing an auction; the reserve price signals information to bidders. In a separating equilibrium signalling is costly in the sense that reserves are higher than would be optimal under complete information. We examine the returns to the seller in an English auction from using different types of secret reserve regimes. We find that immediate disclosure of a reserve is preferable to announcement after the auction in the form of a take-it-or-leave-it offer to the winning bidder. Sale occurs less often during the auction for a given reserve price strategy under secret reserve regimes, which increases the incentive for the seller to report more favourable information though the reserve price offer. Separating equilibria involving later announcement therefore generate even lower expected profits to the seller (signalling is more costly) than under immediate disclosure. In the third essay we compare the benchmark signalling equilibrium of immediate disclosure to a screening regime which we call the Right of Refusal. In this extreme form of a secret reserve the seller never announces the reserve price, she simply accepts or rejects the auction price. We find that the Right of Refusal dominates immediate disclosure if the seller's valuation is a sufficient statistic for the private information of interest. Thus a seller with market-relevant private preference information can benefit from not exercising monopoly price setting power. The result also provides conditions under which a competitive screening equilibrium is more efficient than a signalling mechanism. Broadly speaking, screening is better when the common value aspect in the preferences of the informed and uninformed parties are `aligned', and potential gains from trade to the uninformed party are significant. We believe this conclusion to be of particular interest to the design of privatization schemes.
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Crassous, Jeanne. "Synthèse des énantiomères du bromochlorofluorométhane et détermination de leur configuration absolue par modélisation moléculaire et activité optique Raman." Lyon, École normale supérieure (sciences), 1996. http://www.theses.fr/1996ENSL0036.
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Les enantiomeres (+) et (-) du bromochlorofluoromethane (chfclbr) ont ete synthetises par decarboxylation des enantiomeres de meme signe de l'acide bromochlorofluoroacetique (brclfcco#2h). Cet acide a lui meme ete dedouble par cristallisation de ses sels diastereoisomeres avec la strychnine, et sa configuration absolue s-(+) a ete etablie par rayons x. Puis la question de la configuration absolue de chfclbr a ete etudiee a l'aide des spectres d'activite optique raman (theoriques et experimentaux) et par modelisation moleculaire. La configuration absolue s-(+) de cet haloforme a ainsi ete etablie. Il est ainsi demontre que la decarboxylation de l'acide (+) brclfcco#2h en (+) chfclbr procede avec retention de configuration
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Vilamot, Raphaël. "Optimisation de la configuration magnétique d'un propulseur à effet Hall par résolution du problème magnétostatique inverse." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/14668/1/vilamot.pdf.
Full textAbstract:
Les travaux effectués lors de cette thèse portent sur l'optimisation de la configuration magnétique des propulseurs à effet Hall. Ceci regroupe deux objectifs: d'une part la réalisation d'un propulseur à effet Hall dont la topologie magnétique est entièrement paramétrable, ce qui constituera un outil précieux pour l'étude de l'impact du champ magnétique sur le fonctionnement du propulseur et d'autre part, l'étude de moyen de conception rationalisée de circuits magnétiques pour ces mêmes propulseurs. Le premier sujet a conduit à la réalisation du PPS-Flex, un propulseur proposant une structure de circuit magnétique innovante offrant un grand nombre de degrés de liberté en termes de réglage du champ magnétique produit. La deuxième thématique a quant à elle été abordée en s'appuyant sur des méthodes d'optimisation (paramétrique et topologique) permettant d'aboutir à un circuit magnétique optimal pour un ou plusieurs critères de conception (fidélité du champ magnétique généré, minimisation de la masse, du volume total, etc.)
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Chien, Chih-Hao. "POTENTIAL OPTIMAL GAIT PERFORMANCE OF MAUCH S-N-S PROSTHETIC KNEE CONFIGURATIONS AS PREDICTED BY DYNAMIC MODELING." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1417068842.
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SAGE, FRANCOISE. "Pompage optique du niveau metastable **(3)p : :(o) de la premiere configuration excitee des isotopes impairs des gaz rares." Caen, 1985. http://www.theses.fr/1985CAEN2039.
Full textAbstract:
Etude experimentale de ce pompage optique sur les isotopes **(21)ne, **(83)kr, **(129)xe et **(131)xe afin de mesurer le facteur de lande g(**(3)po) par des experiences de resonance magnetique en phase vapeur (**(21)ne) ou son faisceau atomique, les atomes etant portes dans l'etat metastable a l'aide d'une decharge haute frequence et pompes optiquement par un laser a colorant continu accordable, avec une precision superieure a celle des calculs a partir de la structure hyperfine