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1
Shah, Aditya Arunkumar. "Combining mathematical programming and SysML for component sizing as applied to hydraulic systems." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33890.
Повний текст джерелаАнотація:
In this research, the focus is on improving a designer's capability to determine near-optimal sizes of components for a given system architecture. Component sizing is a hard problem to solve because of the presence of competing objectives, requirements from multiple disciplines, and the need for finding a solution quickly for the architecture being considered. In current approaches, designers rely on heuristics and iterate over the multiple objectives and requirements until a satisfactory solution is found. To improve on this state of practice, this research introduces advances in the following two areas: a.) Formulating a component sizing problem in a manner that is convenient to designers and b.) Solving the component sizing problem in an efficient manner so that all of the imposed requirements are satisfied simultaneously and the solution obtained is mathematically optimal.
In particular, an acausal, algebraic, equation-based, declarative modeling approach is taken to solve component sizing problems efficiently. This is because global optimization algorithms exist for algebraic models and the computation time is considerably less as compared to the optimization of dynamic simulations. In this thesis, the mathematical programming language known as GAMS (General Algebraic Modeling System) and its associated global optimization solvers are used to solve component sizing problems efficiently.
Mathematical programming languages such as GAMS are not convenient for formulating component sizing problems and therefore the Systems Modeling Language developed by the Object Management Group (OMG SysML ) is used to formally capture and organize models related to component sizing into libraries that can be reused to compose new models quickly by connecting them together. Model-transformations are then used to generate low-level mathematical programming models in GAMS that can be solved using commercial off-the-shelf solvers such as BARON (Branch and Reduce Optimization Navigator) to determine the component sizes that satisfy the requirements and objectives imposed on the system. This framework is illustrated by applying it to an example application for sizing a hydraulic log splitter.
2
Karamalis, Constantinos. "Data perturbation analyses for linear programming." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6709.
Повний текст джерелаАнотація:
This thesis focuses on several aspects of data perturbation for Linear Programming. Classical questions of degeneracy and post-optimal analysis are given a unified presentation, in a view of new interior point methods of linear programming. The performance of these methods is compared to the simplex algorithm; interior point methods are shown to alleviate some difficulties of representation and solution of linear programs. An affine scaling algorithm is implemented in conjunction with a simple rounding heuristic to asses the benefit of interior point trajectories to provide approximate solutions of linear integer programming.
3
Feldman, Jon 1975. "Decoding error-correcting codes via linear programming." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/42831.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.<br>Includes bibliographical references (p. 147-151).<br>Error-correcting codes are fundamental tools used to transmit digital information over unreliable channels. Their study goes back to the work of Hamming [Ham50] and Shannon [Sha48], who used them as the basis for the field of information theory. The problem of decoding the original information up to the full error-correcting potential of the system is often very complex, especially for modern codes that approach the theoretical limits of the communication channel. In this thesis we investigate the application of linear programming (LP) relaxation to the problem of decoding an error-correcting code. Linear programming relaxation is a standard technique in approximation algorithms and operations research, and is central to the study of efficient algorithms to find good (albeit suboptimal) solutions to very difficult optimization problems. Our new "LP decoders" have tight combinatorial characterizations of decoding success that can be used to analyze error-correcting performance. Furthermore, LP decoders have the desirable (and rare) property that whenever they output a result, it is guaranteed to be the optimal result: the most likely (ML) information sent over the channel. We refer to this property as the ML certificate property. We provide specific LP decoders for two major families of codes: turbo codes and low-density parity-check (LDPC) codes. These codes have received a great deal of attention recently due to their unprecedented error-correcting performance.<br>(cont.) Our decoder is particularly attractive for analysis of these codes because the standard message-passing algorithms used for decoding are often difficult to analyze. For turbo codes, we give a relaxation very close to min-cost flow, and show that the success of the decoder depends on the costs in a certain residual graph. For the case of rate-1/2 repeat-accumulate codes (a certain type of turbo code), we give an inverse polynomial upper bound on the probability of decoding failure. For LDPC codes (or any binary linear code), we give a relaxation based on the factor graph representation of the code. We introduce the concept of fractional distance, which is a function of the relaxation, and show that LP decoding always corrects a number of errors up to half the fractional distance. We show that the fractional distance is exponential in the girth of the factor graph. Furthermore, we give an efficient algorithm to compute this fractional distance. We provide experiments showing that the performance of our decoders are comparable to the standard message-passing decoders. We also give new provably convergent message-passing decoders based on linear programming duality that have the ML certificate property.<br>by Jon Feldman.<br>Ph.D.
4
KRUTZ, JILL E. "DESIGN OF A HYDRAULIC ACTUATOR TEST STAND FOR NON-LINEAR ANALYSIS OF HYDRAULIC ACTUATOR SYSTEM." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990813095.
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5
Heybroek, Kim. "On Energy Efficient Mobile Hydraulic Systems : with Focus on Linear Actuation." Doctoral thesis, Linköpings universitet, Fluida och mekatroniska system, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-142326.
Повний текст джерелаАнотація:
In this dissertation, energy efficient hydraulic systems are studied. The research focuses on solutions for linear actuators in mobile applications, with emphasis on construction machines. Alongside the aspect of energy efficiency, the thesis deals with competing aspects in hydraulic system design found in the development of construction machines. Simulation models and controls for different concepts are developed, taking the whole machine into account. In line with this work, several proof of concept demonstrators are developed. First, pump controlled systems are studied and a novel concept based on an open-circuit pump configuration is conceived. Special consideration is paid to multi-mode capabilities that allow for a broadened operating range and potential downsizing of components. Simulation models and controls are developed and the system is experimentally validated in a wheel loader application. Second, the possibility for energy recuperation in valve controlled systems is investigated. In such solutions, a hydraulic motor, added to the meter-out port, is used for energy recovery during load lowering and in multi-function operation. Recuperated energy is either be used momentarily or is stored in a hydraulic accumulator. The proposed solution means an incremental improvement to conventional systems, which is sometimes attractive to machine manufacturers due to fewer uncertainties in reliability, safety and development cost. The energy recovery system is studied on a conceptual level where several alternative systems are proposed and a concept based on a two-machine hydraulic pressure transformer is selected for a deeper control study followed by experimental validation. Third, so-called `common pressure rail' systems are suggested. This technique is well established for rotary drives, at least for the industrial sector. However, in applying this technique to mobile hydraulics, feasible solutions for linear actuators are needed. In this dissertation, two approaches to this problem are presented. The first one is the hydraulic pressure transformer, studied in simulation as the key-component of a `series hybrid' topology for wheel loaders. In the second approach variable displacement linear actuators (VDLA) based on a 4-chamber cylinder and multi-mode control is applied. In a theoretical study a model predictive control approach is suggested and new insights to the trade-off between controllability and energy efficiency of a multi-chamber cylinder are presented. Finally, a fullscale hydraulic hybrid system based on secondary controlled hydraulic motors and VDLAs is designed and experimentally validated on a large excavator.
6
Hochwallner, Martin. "On Motion Control of Linear Incremental Hydraulic Actuators." Doctoral thesis, Linköpings universitet, Industriell Produktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-142264.
Повний текст джерелаАнотація:
Linear Incremental Hydraulic Actuators combine one or more short-stroke cylinders, and two or more engaging/disengaging mechanisms into one actuator with long, medium, or even unlimited stroke length. The motion of each single short-stroke actuator concatenated by the engaging/disengaging mechanisms forms the motion of the linear incremental hydraulic actuator. The patterns of how these motions are concatenated form the gaits of a specific linear incremental hydraulic actuator. Linear incremental hydraulic actuators may have more than one gait. In an application, the gaits may be combined to achieve optimal performance at various operating points. The distinguishing characteristic of linear incremental hydraulic actuators is the incremental motion. The term incremental actuator is seen as analogous to the incremental versus absolute position sensor. Incremental actuators realize naturally relative positioning. Incremental motion means also that the behavior does not depend on an absolute position but only on the relative position within a cycle or step. Incremental actuators may realize discrete incremental or continuous incremental motion. Discrete incremental actuators can only approach discrete positions, whereby stepper drives are one prominent example. In contrast, continuous incremental actuators may approach any position. Linear electric motors are one example of continuous incremental actuators. The actuator has no inherent limitation in stroke length, as every step or cycle adds only to the state at the beginning of the step or cycle and does not depend on the absolute position. This led to the alternative working title Hydraulic Infinite Linear Actuator. Linear incremental hydraulic actuator provides long stroke, high force, and linear motion and has the potential to decrease the necessary resource usage, minimize environmental impact, e.g. from potential oil spillage, extend the range of feasible products: longer, stiffer, better, etc. This thesis presents an analysis of the characteristics and properties of linear incremental hydraulic actuators as well as the gaits and possible realizations of some gaits. The gait for continuous, smooth motion with two cylinders is comprehensively studied and a control concept for the tracking problem is proposed. The control concept encapsulates the complexity of the linear incremental hydraulic actuator so that an application does not have to deal with it. One other gait, the ballistic gait, which realizes fast, energy-efficient motion, enabling energy recuperation is studied.
7
Kelner, Jonathan 1980. "New geometric techniques for linear programming and graph partitioning." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38295.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.<br>Includes bibliographical references (leaves 79-82).<br>In this thesis, we advance a collection of new geometric techniques for the analysis of combinatorial algorithms. Using these techniques, we resolve several longstanding questions in the theory of linear programming, polytope theory, spectral graph theory, and graph partitioning. The thesis consists of two main parts. In the first part, which is joint work with Daniel Spielman, we present the first randomized polynomial-time simplex algorithm for linear programming, answering a question that has been open for over fifty years. Like the other known polynomial-time algorithms for linear programming, its running time depends polynomially on the number of bits used to represent its input. To do this, we begin by reducing the input linear program to a special form in which we merely need to certify boundedness of the linear program. As boundedness does not depend upon the right-hand-side vector, we run a modified version of the shadow-vertex simplex method in which we start with a random right-hand-side vector and then modify this vector during the course of the algorithm. This allows us to avoid bounding the diameter of the original polytope.<br>(cont.) Our analysis rests on a geometric statement of independent interest: given a polytope ... in isotropic position, if one makes a polynomially small perturbation to b then the number of edges of the projection of the perturbed polytope onto a random 2-dimensional subspace is expected to be polynomial. In the second part of the thesis, we address two long-open questions about finding good separators in graphs of bounded genus and degree: 1. It is a classical result of Gilbert, Hutchinson, and Tarjan [25] that one can find asymptotically optimal separators on these graphs if he is given both the graph and an embedding of it onto a low genus surface. Does there exist a simple, efficient algorithm to find these separators given only the graph and not the embedding? 2. In practice, spectral partitioning heuristics work extremely well on these graphs. Is there a theoretical reason why this should be the case? We resolve these two questions by showing that a simple spectral algorithm finds separators of cut ratio O( g/n) and vertex bisectors of size O(Vng) in these graphs, both of which are optimal. As our main technical lemma, we prove an O(g/n) bound on the second smallest eigenvalue of the Laplacian of such graphs and show that this is tight, thereby resolving a conjecture of Spielman and Teng.<br>(cont.) While this lemma is essentially combinatorial in nature, its proof comes from continuous mathematics, drawing on the theory of circle packings and the geometry of compact Riemann surfaces. While the questions addressed in the two parts of the thesis are quite different, we show that a common methodology runs through their solutions. We believe that this methodology provides a powerful approach to the analysis of algorithms that will prove useful in a variety of broader contexts.<br>by Jonathan A. Kelner.<br>Ph.D.
8
SARAVANAN, SHANKAR. "EVALUATION OF SPHERICITY USING MODIFIED SEQUENTIAL LINEAR PROGRAMMING." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1132343760.
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9
Ukritchon, Boonchai 1970. "Evaluation of numerical limit analyses by finte elements and linear programming." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11199.
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10
Tiessen, Meinard. "Predicting the development of crescentic bed patterns : a comparison of linear stability model results with field observations." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11028/.
Повний текст джерелаАнотація:
Large scale patterns in the seabed often occur in the nearshore zone of sandy beaches. A widely occurring bed pattern is the crescentic bar. These bed patterns develop under moderate wave conditions, and form a lunate shaped alongshore pattern in front of a coast. Over recent years, knowledge concerning the development, occurrence, and characteristics of these bed patterns has been significantly expanded through field studies and modelling attempts. An example of such a model is the linear stability analysis, which describes the initial development of crescentic bed patterns along an undisturbed beach. To date, comparisons between field measurements and modelling results have been general in nature. The purpose of this research is to investigate whether a linear stability analysis, which is useful for understanding the physics of emerging bed-forms, can be used to make quantitative predictions in the field. To this end a morphodynamical linear stability model (Morfo60, [Calvete et al., 2005]) is used to describe the development of crescentic bed patterns at the coast at the USACE Field Research Facility in Duck, North Carolina, USA. Wave, tide and bathymetry data recorded at Duck over a two month period in 1998 are used to model the development of these morphodynamical patterns. The model predictions are compared with field observations made at Duck, over the same two month period, reported by van Enckevort et al. [2004]. A direct comparison shows that predicted length scales of crescentic bed patterns are similar to those observed. However, the model predictions show more fluctuations than are observed in the field. This is because the model describes the development of crescentic bed patterns starting from an alongshore constant bed, whereas in reality bed patterns already exist in most situations. An algorithm is developed to overcome these fluctuations and identifies the more physically significant model predictions based on large growth rates and consistency in length scales. The moments at which physically significant model predictions occur correspond better with field observations than the original model predictions. The effects of pre-existing bed-forms on the development of crescentic bed patterns are investigated using a non-linear model (Morfo55, [Garnier, 2006]). Results show that pre-existing bed patterns can have significant effects, however, the finally dominant length scale, the linear growth and decay rates, and the migration rate can be accurately described by a linear stability model. Pre-existing length scales that exhibit significant linear growth will remain and undergo further development, whereas length scales that are outside the linear growth rate curve decay and give rise to a bed pattern with a bigger linear growth rate. The conclusions drawn from the research concerning pre-existing bed patterns are applied to improve predictions linear stability model. This results in considerable improvements in the comparison of model predictions with field observations, for certain periods of time.
11
Trimarchi, Daniele. "Analysis of downwind sail structures using non-linear shell finite elements : wrinkle development and fluid interaction effects." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/348893/.
Повний текст джерелаАнотація:
Downwind yacht sails are subjected to fluid structure interaction effects which can slightly change the initial design shape, with a direct impact on the overall performances. The turbulent flow acting on downwind sails is separated for the larger part of the device, with large vortices and recirculating regions. The sail is made of a thin fabric, the deformation of which is affected by wrinkling, which produces out-of-plane oscillations of the surface of the fabric, and locally changes the stress/strain distribution. Because of the interactions of these fluid and structural phenomena, the detailed analysis of downwind sails requires sophisticated approaches able to capture the structural deformations, the generation of the wrinkles and the unsteady fluid structure interactions. This is not achieved in conventional sail analysis, the state of the art of which consist, for the most advanced applications, in steady fluid structure analysis adopting membrane structural elements, which are unable to reproduce the wrinkling. The turbulent flow is here analysed with a Reynolds Averaged Navier Stokes method implemented in the finite volume solver OpenFOAM, and case studies are presented regarding the detailed description of the flow/wrinkle interactions, as well as the flow generation on full 3D sail-type devices. This approach is a good compromise between accuracy and computational expense, allowing the investigation of unsteady fluid structure interactions. The work presented here in fact primarily concentrates on the structural response and its influence on the fluid flow rather than the analysis of the fine details of an isolated unsteady flow. Shell finite elements of the Mixed Interpolation Tensorial Components (MITC) family are used for simulating the fabric. The use of these sophisticated Finite Elements allows for capturing the greater detail of the structural behaviour and the generation of the wrinkles. Comparisons are presented between the results obtained with the shells and the membrane finite elements, traditionally adopted for the structural analysis of fabrics. The performances of the method are demonstrated with simplified validation test cases and applications are shown for realistic 3D devices. Unsteady fluid structure interaction analysis is performed using the Arbitrary Lagrangian Eulerian (ALE) framework, providing a conservative environment. Validation test cases are compared with reference solutions and the inflation of a sail-type device is analysed. The flow development is accurately captured, and the presence of wrinkles on the cross-flow determine a substantial decrease of the lift and an increase in the drag. Inducing unsteadiness in the flow produces a general increase of the performances of the device. Using shell elements the wrinkling can be directly reproduced, while using membrane models require additional wrinkling models. The prediction performances of the MITC shells are substantially higher than those of the Constant Strain Triangles (CST) membranes, traditionally adopted for simulating the sail fabric. Unsteady fluid structure interaction analysis are validated against reference solutions with good agreement. When applying the method to yacht-sail type geometries, results are coherent and consistent with the sailing practise.
12
Sidford, Aaron Daniel. "Iterative methods, combinatorial optimization, and linear programming beyond the universal barrier." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99848.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 256-266).<br>In this thesis we consider fundamental problems in continuous and combinatorial optimization that occur pervasively in practice and show how to improve upon the best known theoretical running times for solving these problems across a broad range of parameters. Using and improving techniques from diverse disciplines including spectral graph theory, numerical analysis, data structures, and convex optimization we provide the first theoretical improvements in decades for multiple classic problems ranging from linear programming to linear system solving to maximum flow. Key results in this thesis include the following: -- Linear Programming: We provide the first general improvement to both the running time and convergence rate of polynomial time algorithms for solving linear programs in over 15 years. For a linear program with constraint matrix A, with z nonzero entries, and bit complexity L our algorithm runs in time [mathematical formula] -- Directed Maximum Flow: We provide an [mathematical formula] time algorithm for solving the-maximum flow problem on directed graphs with m edges, n vertices, and capacity ratio U improving upon the running time of [mathematical formula] achieved over 15 years ago by Goldberg and Rao. -- Undirected Approximate Flow: We provide one of the first almost linear time algorithms for approximately solving undirected maximum flow improving upon the previous fastest running time by a factor of [mathematical formula] for graphs with n vertices. -- Laplacian System Solvers: We improve upon the previous best known algorithms for solving Laplacian systems in standard unit cost RAM model, achieving a running time of [mathematical formula] for solving a Laplacian system of equations. -- Linear System Solvers: We obtain a faster asymptotic running time than conjugate gradient for solving a broad class of symmetric positive definite systems of equations. * More: We improve the running time for multiple problems including regression, generalized lossy flow, multicommodity flow, and more.<br>by Aaron Sidford.<br>Ph. D.
13
KOWTA, SRINIVAS. "ROBUST STABILITY ANALYSIS OF SERVO-HYDRAULIC SYSTEM IN PARAMETER SPACE." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060970575.
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Bevis, Stanley G. "Lingraf: The design of an interactive teaching aid for linear programming." Ohio University / OhioLINK, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1183749162.
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15
Sahin, Deniz. "Mixed Integer Linear Programming for Time-Optimal Cyclic Scheduling of High Throughput Screening Systems." Thesis, Southern Illinois University at Edwardsville, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10808099.
Повний текст джерелаАнотація:
<p> High Throughput Screening (HTS) systems are highly technological and fully automated plants which are used for the analysis of thousands of biochemical substances to provide basis for the drug discovery process. As the operation of these systems is remarkably expensive, the scheduling for the processes of such complex systems is critical to the HTS companies. Since the processing time affects the throughput and the efficiency of the system, a time-optimal schedule must be developed for the system which can yield high throughputs. In this thesis, a Mixed Integer Programming model is presented, minimizing the overall processing time and therefore maximizing the throughput of the system. To generate the mathematical model, the principles of Job-Shop Scheduling and Cyclic Scheduling are utilized. The results of the study are supported by an experiment conducted at the High Throughput Screening plant at Washington University in St. Louis. As a conclusion, the model has generated a time-optimal cyclic schedule which improves the total processing time of the system by 3 minutes for 25 batches. The projection of the model for experiments that run with hundreds of batches is interpreted to generate greater improvements for the overall processing time of the system.</p><p>
16
Fawzi, Hamza. "Power and limitations of convex formulations via linear and semidefinite programming lifts." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107331.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 155-162).<br>Convex relaxation methods play an important role in mathematical optimization to tackle hard nonconvex problems, and have been applied successfully in many areas of science and engineering. At the heart of such methods lies the question of obtaining a tractable description of the convex hull of a set. In this thesis we focus on the question of finding tractable representations of convex sets via the method of lifting, whereby the "hard" convex set is expressed as the projection of a simpler one living in higher-dimensional space. We derive new results and insights on the power and limitations of such liftings. In the first part of the thesis we study limitations of the lifting method and develop lower bounds on the sizes of linear programming (LP) and semidefinite programming (SDP) lifts of polytopes. For LP lifts the bound we develop applies generally for the nonnegative rank of matrices and we compare our method with existing combinatorial and non-combinatorial techniques. For SDP lifts we focus on so-called equivariant lifts that respect symmetry, and obtain lower bounds on the size of such lifts for certain combinatorial polytopes by exploiting the connection with the sum-of-squares method. In the second part of the thesis, we study the power of the lifting procedure and show how to obtain small semidefinite lifts for certain classes of polytopes via the idea of sparse sums of squares. We develop a graph-theoretic method to construct such lifts and use it to resolve a conjecture of Laurent from 2003 on the cut polytope, and to give an explicit sequence of polytopes with a gap between LP and SDP lifts. Finally we depart from the specific question of constructing lifts and consider the general problem of certifying nonnegativity of functions. We study a class of certificates rooted in convex duality and show that they encompass many existing methods for proving nonnegativity based on convex optimization. In particular we propose a new proof system to certify nonnegativity of entropy-like functions, which we illustrate on the problem of computing the logarithmic Sobolev constant of finite Markov chains.<br>by Hamza Fawzi.<br>Ph. D.
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Yoon, Jongyun. "QUASI-LINEAR DYNAMIC MODELS OF HYDRAULIC ENGINE MOUNT WITH FOCUS ON INTERFACIAL FORCE ESTIMATION." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1281366966.
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Van, Der Merwe Carel Wagener. "A peridynamic model for sleeved hydraulic fracture." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95993.
Повний текст джерелаАнотація:
Thesis (MEng)--Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: Current numerical methods in the eld of hydraulic fracturing are based mainly on
continuum methods, such as the Finite Element Method (FEM) and the Boundary Element
Method (BEM). These methods are governed by Linear Elastic Fracture Mechanics
(LEFM) criteria, which su er from the inherent
aw of a non-physical stress representation
at the fracture tip. In response to this, a non-local method is proposed, namely
the peridynamic theory, to model sleeved hydraulic fracture. A 2D implicit quasi-static
ordinary state based peridynamic formulation is implemented on various benchmark
problems, to verify the ability to capture constitutive behaviour in a linear elastic solid,
as well as, the quanti cation of adverse e ects on the accuracy of the displacement solution,
due to the nature of the non-local theory. Benchmark tests consist of a plate in
tension, where convergence to the classical displacement solution, non-uniform re nement
and varying cell sizes are tested, as well as, a thick walled cylinder with internal
pressure, where three di erent loading techniques are tested. The most accurate loading
technique is applied to the sleeved fracture model, in order to simulate fracture initiation
and propagation. This model is then veri ed and validated by using the Rummel &
Winter hydraulic fracturing model and experimental results, respectively. Displacement
error minimisation methods are implemented and as a result, the displacement solutions
for a plate in tension converges to the analytical solution, while the thick walled cylinder
solutions su er from inaccuracies due to an applied load on an irregularly discretized
region. The fracture initiation test captures the fracture tip behaviour of the Rummel
& Winter model and the fracture propagation test show good correlation with experimental
results. This research shows that the peridynamic approach to sleeved hydraulic
fracture can yield a realistic representation of fracture initiation and propagation, however,
further research is needed in the area of a pressure load application on a solid using
the peridynamic approach.<br>AFRIKAANSE OPSOMMING: Huidige numeriese metodes in die veld van hidrouliese breking is hoofsaaklik gebaseer
op kontinuum metodes, soos die Eindige Element Metode (EEM) en die Rand Element
Metode (REM). Hierdie metodes word beheer deur Linie^ere Elastiese Breukmeganika
(LEB) kriteria, wat ly aan die inherente gebrek van 'n nie- siese voorstelling van die
spanning by die fraktuur punt. Om hierdie probleme aan te spreek, word 'n nie-lokale
metode voorgestel, naamlik die peridinamiese teorie, om gehulsde hidrouliese breking
te modelleer. 'n 2D implisiete kwasi-statiese ordin^ere toestand gebaseerde peridinamika
formulering word ge mplimenteer op verskeie norm probleme, om te veri eer of dit oor
die vermo e beskik om die konstitutiewe gedrag van 'n linie^ere elastiese soliede materiaal
te modeleer, asook die kwanti sering van nadelige e ekte op die verplasings oplossing as
gevolg van die natuur van die nie-lokale teorie. Normtoetse bestaan uit 'n plaat in trek
spanning, waar konvergensie na die klassieke verplasings oplossing, nie-uniforme verfyning
en vari^eerende sel groottes getoets word, asook 'n dikwandige silinder onder interne
druk, waar drie verskillende belasting aanwendingstegnieke getoets word. Die mees akkurate
belasting aanwendingstegniek word dan gebruik in die gehulsde hidrouliese breking
model, om fraktuur aanvangs en uitbreiding na te boots. Die model word dan geveri-
eer deur die Rummel & Winter hidrouliese breking model en eksperimentele resultate,
onderskeidelik. Fout minimering metodes word toegepas en as 'n resultaat, konvergeer
die verplasing oplossing vir die plaat na die analitiese oplossing, terwyl die oplossing
van die dikwandige silinder onakuraathede toon as gevolg van 'n toegepaste belasting
op 'n onre elmatig gediskretiseerde gebied. Die modellering van die fraktuur inisi ering
by die fraktuur punt, stem goed ooreen met die Rummel en Winter voorspelling en die
fraktuur uitbreiding stem goed ooreen met eksperimentele resultate. Hierdie navorsing
toon dat die peridinamiese benadering tot gehulsde hidrouliese breking wel die fraktuur
inisi ering en uitbreiding realisties kan modelleer, maar nog navorsing word wel benodig
in die area waar 'n druk belasting op 'n peridinamiese soliede model toegepas word.
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Humphreys, Linda A. "LPVAX - A three-dimensional linear programming graphics package on the intergraph-vax system." Ohio University / OhioLINK, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1183132775.
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Lundmark, Olle. "Evaluation of mixed integer linear programming solvers when applied to a biogas reactor system model." Thesis, Umeå universitet, Institutionen för datavetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-155344.
Повний текст джерелаАнотація:
Optimization of a biogas reactor system, to maximize its profits, is a natural step to become a more competitive electricity source. This is done by first formulating mixed integer linear program (MILP), of an abstract biogas reactorsystem, which is then implemented with parameters to simulate a real biogas reactor system. Then to solve a MILP problem, a solver is used. Depending on what solver is used to solve the problem, the run-time and solution may differ a lot. That is the reason why FarmBioTech AB is interested in the evaluation of the solvers Cplex, Gurobi, Glpk, and Cbc when applied to a biogas reactor system model. The solvers are evaluated by checking if they manage to find feasible solutions that are at most 1% from the optimal solution within a run-time limit of one hour. Both Gurobi and Cplex managed to find quality solutions within the given run-time limit, while Glpk and Cbc did not.
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Ceranic, Boris. "Optimum design of reinforced concrete skeletal systems using non-linear programming techniques." Thesis, University of Derby, 2000. http://hdl.handle.net/10545/583616.
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Burton, Scott H. "Coping with the Curse of Dimensionality by Combining Linear Programming and Reinforcement Learning." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/559.
Повний текст джерелаАнотація:
Reinforcement learning techniques offer a very powerful method of finding solutions in unpredictable problem environments where human supervision is not possible. However, in many real world situations, the state space needed to represent the solutions becomes so large that using these methods becomes infeasible. Often the vast majority of these states are not valuable in finding the optimal solution. This work introduces a novel method of using linear programming to identify and represent the small area of the state space that is most likely to lead to a near-optimal solution, significantly reducing the memory requirements and time needed to arrive at a solution. An empirical study is provided to show the validity of this method with respect to a specific problem in vehicle dispatching. This study demonstrates that, in problems that are too large for a traditional reinforcement learning agent, this new approach yields solutions that are a significant improvement over other nonlearning methods. In addition, this new method is shown to be robust to changing conditions both during training and execution. Finally, some areas of future work are outlined to introduce how this new approach might be applied to additional problems and environments.
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Gutierrez, Cristian Joel. "Development and application of a linear programming model to optimize production and distribution of a manufacturing company." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10855.
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Cheng, Chao. "Application of Artificial Neural Networks in the Power Split Controller For a Series Hydraulic Hybrid Vehicle." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1278610645.
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Bliss, Michael A. "Procedures to Perform Dam Rehabilitation Analysis in Aging Dams." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33157.
Повний текст джерелаАнотація:
There are hundreds of existing dams within the State of Virginia, and even thousands more specifically within the United States. A large portion of these dams do not meet the current safety standard of passing the Probable Maximum Flood. Likewise, many of the dams have reached or surpassed the original design lives, and are in need of rehabilitation. A standard protocol will assist dam owners in completing a dam rehabilitation analysis. The protocol provides the methods to complete the hydrologic, hydraulic, and economic analysis. Additionally, alternative augmentation techniques are discussed including the integration of GIS applications and linear programming optimization techniques. The standard protocol and alternative techniques are applied to a case study. The case study includes a set of flood control dams located in the headwaters of the South River watershed in Augusta County, VA. The downstream impacts of the flood control dams on the city of Waynesboro are demonstrated through the hydrologic and hydraulic analysis.<br>Master of Science
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Rush, Andrew J. "Partial Destination Resolution in Multicast Elastic Optical Networks: A Mixed-Integer Linear Programming Approach." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470324185.
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Al, Reeshi Mohammad Ahmad. "Industrial engineering applications in metrology : job scheduling, calibration interval and average outgoing quality." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/7610.
Повний текст джерелаАнотація:
This research deals with the optimization of metrology and calibration problems. The optimization involved here is the application scientifically sound operations research techniques to help in solving the problem intended optimally or semi-optimally with a practical time frame. The research starts by exploring the subject of measurement science known as metrology. This involves defining all the constituents of metrology facilities along with their various components. The definitions include the SI units’ history and structure as well as their characteristics. After that, a comprehensive description of most of the operations and parameters encountered in metrology is presented. This involves all sources of uncertainties in most of the parameters that affect the measurements. From the background presented and using all the information within it; an identification of the most important and critical general problems is attempted. In this treatment a number of potential optimization problems are identified along with their description, problem statement definition, impact on the system and possible treatment method. After that, a detailed treatment of the scheduling problem, the calibration interval determination problem and the average outgoing quality problem is presented. The scheduling problem is formulated and modelled as a mixed integer program then solved using LINGO program. A heuristic algorithm is then developed to solve the problem near optimally but in much quicker time, and solution is packaged in a computer program. The calibration interval problem treatment deals with the determination of the optimal CI. Four methods are developed to deal with different cases. The cases considered are the reliability target case, the CI with call cost and failure cost of both first failure and all failures and the case of large number of similar TMDEs. The average out going quality (AOQ) treatment involves the development two methods to assess the AOQ of a calibration facility that uses a certain multistage inspection policy. The two methods are mathematically derived and verified using a simulation model that compares them with an actual failure rate of a virtual calibration facility.
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Spence, William G. "An Optimization Approach To Employee Scheduling Using Fuzzy Logic." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/618.
Повний текст джерелаАнотація:
An Optimization Approach to Employee Scheduling Using Fuzzy Logic
William G. Spence
Selection of sales employees is critical because the sales employees represent the company’s image, competitive advantage, technology, and values. In many service systems the majority of consumer contact is with the sales department. Since there are different types of customers, scheduling quality salespersons who can adequately help consumers may affect revenue.
This thesis proposes a new methodology for the scheduling of employees in a service system. The methodology uses Fuzzy Logic to calculate possible sales and Linear Programming to create an optimal schedule. This approach enables the rating of sales employees with respect to three customer’s types (Lookie Lou, Price Shopper and Buyer). The salesperson rating, along with customer arrival distribution is then used to optimize sale person scheduling, with the objective of revenue maximization. The uniqueness of this thesis lies in the combination of Fuzzy Logic and Linear Programming. The combination of these two disciplines provides an adaptive tool that can be used to optimize employee scheduling based on personality traits.
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Harihara, Ramachandra Sharma. "Modeling of Scheduling Algorithms with Alternative Process Plans in an Optimization Programming Language." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108045192.
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Alqattan, Nael Abdulhameed. "A Multi-Period Mixed Integer Linear Programming Model for Desalination and Electricity Co-generation in Kuwait." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5167.
Повний текст джерелаАнотація:
Water is the root of life and the engine that drives agriculture, industry, economy and services. The demand for water often necessitates desalination, particularly in arid coastal environments where there are several desalination technologies in use today such as Multi-Effect Distillation (MED) and Reverse Osmosis (RO). The key utility requirement for technologies such as desalination and population in general include energy in one form or another. Therefore, desalination and co-generation are often integrated. Another key utility is electricity which is generated from either renewable or non-renewable sources. The demands for water and electricity change over time and are subject to uncertainty. In this dissertation, a country-wide large-scale energy and water cogeneration planning model for Kuwait was proposed and solved. Five different plant technologies where the planning horizon used was set to 37 years starting in year 2014 and until 2050. A Mixed Integer Mathematical programming model was proposed and formulated using General Algebraic Modeling System (GAMS), the resulting model was solved using the CPLEX solver engine. In this research obtained detailed data on the consumption on water and energy in Kuwait and performed time series analysis of the population growth and individual behavior of water and energy consumption and novel method to represent cogeneration plants was implemented in the proposed mathematical programming model.
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A modeling framework that involves a data spreadsheet and a proprietary model was implemented. The data spreadsheet and the model were formulated as a template that can receive data from different applications. In addition, automation using Visual Basic for Application (VBA) was made to the data spreadsheets such that the data is sent to the model template, Gams-Cylix, and are written back to the spreadsheet. An analysis was made between oil-based plants, natural gas (NG) plants, and solar-based plants for co-generation. It was found that for water production solar-based plants can supply 50 percent or more of the demand during after period 2020 and after implementation and for electric power generation solar plants are limited. The results indicate the preferred technology for energy generation was NG-RO. With the implementation of solar based plants the electric power load is distributed among the technologies. NG-RO plants are more scalable and therefore were expanded to cope with the future demand.
The percentage of the electric power supplied by solar plant was below 35 percent across the planning horizon. By the end of the planning horizon the percentage of electric power supplied by solar base plants was nearly 20 percent. Near 70 percent of the electric power was supplied by NG RO by period 2050. Other technologies had a representation of less than 10 percent by the end of the planning horizon.
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Beal, Logan Daniel. "Large-Scale Non-Linear Dynamic Optimization For Combining Applications of Optimal Scheduling and Control." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7021.
Повний текст джерелаАнотація:
Optimization has enabled automated applications in chemical manufacturing such as advanced control and scheduling. These applications have demonstrated enormous benefit over the last few decades and continue to be researched and refined. However, these applications have been developed separately with uncoordinated objectives. This dissertation investigates the unification of scheduling and control optimization schemes. The current practice is compared to early-concept, light integrations, and deeper integrations. This quantitative comparison of economic impacts encourages further investigation and tighter integration. A novel approach combines scheduling and control into a single application that can be used online. This approach implements the discrete-time paradigm from the scheduling community, which matches the approach of the control community. The application is restricted to quadratic form, and is intended as a replacement for systems with linear control. A novel approach to linear time-scaling is introduced to demonstrate the value of including scaled production rates, even with simplified equation forms. The approach successfully demonstrates significant benefit. Finally, the modeling constraints are lifted from the discrete-time approach. Time dependent constraints and parameters (like time-of-day energy pricing) are introduced, enabled by the discrete-time approach, and demonstrate even greater economic value. The more difficult problem calls for further exploration into the relaxation of integer variables and initialization techniques for faster, more reliable solutions. These applications are also capable of replacing both scheduling and control simultaneously. A generic CSTR application is used throughout as a case study on which the integrated optimization schemes are implemented. CSTRs are a common model for applications in most chemical engineering industries, from food and beverage, to petroleum and pharmaceuticals. In the included case study results, segregated control and scheduling schemes are shown to be 30+% less profitable than fully unified approaches during operational periods around severe disturbances. Further, inclusion of time-dependent parameters and constraints improved the open-loop profitability by an additional 13%.
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Fagundez, Fabio Dias. "Modelos não-lineares continuos para logística de petróleo em portos e refinarias." reponame:Repositório Institucional do BNDES, 2010. https://web.bndes.gov.br/bib/jspui/handle/1408/10275.
Повний текст джерелаАнотація:
Empresas da indústria de petróleo operam em um mercado altamente competitivo, sob pressão contínua por menores custos e processos mais eficientes. Nesta pesquisa de doutorado, abordamos problemas de scheduling de petróleo e derivados em portos e refinarias, o qual tem sido tratado com frequência sob a forma de modelos misto-inteiros lineares (MILP) e não-lineares (MINLP). Esta tese introduz uma abordagem nova e original de programação não-linear, cuja principal idéia é a de considerar a programação de produção (schedule) como um sistema dinâmico que deve ser operado sob certas restrições. Operações de transferência são executadas por vazões de equipamentos de origem para equipamentos de destino, as quais são mapeadas como variáveis de controle, enquanto os conteúdos dos equipamentos são mapeados como variáveis de estado. Decisões do tipo sim-não são modelados com restrição de complementaridade, portanto possibilitando modelos contínuos não-lineares, equivalentes a modelos MIP (MILP ou MINLP, dependendo do conjunto de restrições adotado), de modo que um ponto viável no NLP possa ser mapeado diretamente a um ponto viável no modelo misto-inteiro. Essa abordagem é ilustrado com exemplos computacionais, obtendo ótimos locais.<br>Companies from the petroleum industry operate in a highly competitive market, under constant pressure for lower costs and e cient processes. In this doctorate research, we study the scheduling of crude oil and derivatives in ports and re neries, which has been frequently studied in the literature with mixed-integer models, both linear (MILP) and nonlinear (MINLP). The main idea presented in this thesis is that the schedule is a dynamic system which must operate under certain constraints. Transfer operations are carried out by flows from a source equipment to a destination equipment. Such flows are mapped as control variables, whereas equipment contents are mapped as state variables. Yes-No decisions are modeled with complementarity constraints, thus allowing a continuous nonlinear models, equivalents to MIP models (MILP or MINLP, depending on the chosen set of constraints), in such a way that a NLP-feasible point can be directly mapped to a MIP-feasible point. We illustrate this approach with computational examples, which were solved to local optimality.<br>Tese (doutorado) - Universidade Federal do Rio de Janeiro, Rio de Janeiro, 2010.<br>Bibliografia: p. 74-84.
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Silva, Daniele Costa 1984. "Detecção de linhas redundantes em problemas de programação linear de grande porte." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/306747.
Повний текст джерелаАнотація:
Orientador: Aurelio Ribeiro Leite de Oliveira<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica<br>Made available in DSpace on 2018-08-16T01:36:50Z (GMT). No. of bitstreams: 1
Silva_DanieleCosta_M.pdf: 1303714 bytes, checksum: 5b7f038f6b0f53fca9601f7784ec02d1 (MD5)
Previous issue date: 2010<br>Resumo: A presença de linhas redundantes na matriz de restrições não é incomum em problemas reais de grande porte. A existência de tais linhas deve ser levada em consideração na solução destes problemas. Se o método de solução adotado for o método simplex, existem procedimentos eficientes e de fácil implementação que contornam este problema. O mesmo se aplica quando métodos de pontos interiores são adotados e os sistemas lineares resultantes são resolvidos por métodos diretos. No entanto, existem problemas de grande porte cuja única forma possível de solução é resolver os sistemas lineares por métodos iterativos. Nesta situação as linhas redundantes representam uma dificuldade considerável, pois geram uma matriz singular e os métodos iterativos não convergem. A única alternativa viável consiste em detectar tais linhas e eliminá-las antes da aplicação dos métodos de pontos interiores. Este trabalho propõe uma implementação eficiente de um procedimento de detecção de linhas redundantes, que incluímos em uma adaptação própria do PCx que resolve os sistemas lineares por métodos iterativos<br>Abstract: The presence of dependent rows in the constraint matrix is frequent in real large-scale problems. If the method of solution adopted is the simplex method, there are efficient procedures easy to implement that circumvent this problem. The same applies when interior point methods are adopted and the resulting linear systems are solved for directed methods. However, there are large-scale problems whose only possible solution is to solve linear systems by iterative methods. In this situation, the dependent rows create a singular matrix and the iterative method does not converge. The only viable alternative is to find and remove these rows before applying the method. This dissertation proposes an efficient implementation of a procedure for detection dependent rows, include in a PCx modification that solves linear systems by iterative methods<br>Mestrado<br>Programação Linear<br>Mestre em Matemática Aplicada
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Olofsson, Emil. "Improved algorithm for weighted matching of employees." Thesis, Linköpings universitet, Databas och informationsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122763.
Повний текст джерелаАнотація:
This report gives the reader a detailed description of a computer engineering master thesis work done at the company Netlight Consulting AB. Netlight Consulting AB is a growing IT consulting company based in Stockholm with offices in major cities across Europe. One of their key success factors is their focus on personal and professional development amongst all employees. An essential part of this development program consist of reoccurring evaluation periods, where every employee receives written constructive feedback from some of their co-workers. This thesis’ focus lies in improving the algorithm that organizes which employee should evaluate who. The original algorithm turned out to harbor a number of flaws, e.g. it was not always able to deliver a satisfactory matching where every participant received the minimum number of evaluations. In this thesis a new matching algorithm has been implemented that is platform independent and that facilitates future modifications with accessible source code written in Java. The input data for the matching algorithm, i.e. the set of all potential evaluation pairs, is of importance to obtain satisfactory matching results. The number of potential evaluation pairs determines the number of possible matching combinations, which in turn increases the probability to find a satisfactory matching. In this thesis the input data has been extended by utilizing a data mining technique known as SONAR. Two different data mining sources were evaluated, and one of them is shown to extend the number of potential evaluation pairs in the matching input by 20%. Finally, a new feature to support assignment of different evaluation sizes was added to the matching algorithm.
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Knisely, Nathan C. L. "Cyber-physical acquisition strategy for COTS-based agility-driven engineering." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55007.
Повний текст джерелаАнотація:
The rising cost of military aircraft has driven the DoD to increase the utilization of commercial off-the-shelf (COTS) components in new acquisitions. Despite several demonstrated advantages of COTS-based systems, challenges relating to obsolescence arise when attempting to design and sustain such systems using traditional acquisition processes. This research addresses these challenges through the creation of an Agile Systems Engineering framework that is specifically aimed at COTS-based systems. This framework, known as the Cyber-physical Acquisition Strategy for COTS-based Agility-Driven Engineering (CASCADE), amends the traditional systems engineering process through the addition of an "identification phase" during which requirements are balanced against the capabilities of commercially-available components.
The CASCADE framework motivates the creation of a new Mixed Integer Linear Programming (MILP) formulation which enables the creation of optimum obsolescence mitigation plans. Using this CASCADE MILP formulation, two sets of experiments are carried out: First, verification experiments demonstrate that the CASCADE MILP conforms to expected trends and agrees with existing results. Next, the CASCADE MILP is applied to a representative set of COTS-based systems in order to determine the appropriate level of obsolescence forecast accuracy, and to uncover new system-level cost-vs-reliability trends associated with COTS component modification.
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Allen, Roderick Lee. "The applicability of microcomputers to local water management." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3417.
Повний текст джерелаАнотація:
Historically, hydrologic models have been available only on mainframe computers and have therefore not been used by local water managers to support daily decisions. The development of the microcomputer presents an opportunity for that to change.
Mathematical models of soil moisture and river routing are selected, developed and tested for use on a microcomputer as an aid to local water management. The models are then integrated with an appropriate data base in a computer program written for a microcomputer. The result is a Decision Support System for local water managers.
In order to evaluate the feasibility of using the Decision Support System, an application of the program to a small hypothetical river and irrigation system is carried out. The speed of execution indicates that the use of the Decision Support System on this class of computer under the present configuration may be possible if software or hardware changes can reduce data transfer times to and from disk.
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Krause, Jonas. "Programação matemática e evolução diferencial para a otimização de redes de dutos." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/752.
Повний текст джерелаАнотація:
A otimização de uma rede de transporte de derivados de petróleo é um problema complexo e abordado na literatura atual. A modelagem matemática deste problema proposta neste trabalho cria um problema de otimização combinatorial. Métodos de resolução deste problema através da programação linear inteira mista e de algoritmos heurísticos de evolução diferencial (Evolução Diferencial Binária e Evolução Diferencial Discretizada) são propostos utilizando variáveis binárias. Os resultados encontrados com a programação linear apresentam valores ótimos para os benchmarks com pequenos espaços de busca e valores sub-ótimos para grandes. Resultados utilizando a evolução diferencial também são apresentados como uma alternativa de baixo esforço computacional. A aplicação destes métodos proporciona alternativas para o transporte de diferentes produtos em um horizonte de tempo definido e compara os métodos heurísticos com codificações binárias e contínuas. Tais resultados incentivam a utilização de algoritmos heurísticos com codificação contínua e apontam os métodos de discretização como alternativas eficazes para a resolução de problemas discretos.<br>The optimization of an pipeline network is a complex problem and addressed in the current literature. The mathematical modeling of this problem proposed in this paper creates a problem of combinatorial optimization. Methods for solving this problem using linear mixed integer programming and heuristic algorithms of differential evolution (Binary Differential Evolution and Discretized Differential Evolution) are proposed using binary variables. The results obtained with the linear programming have optimal values for the benchmarks with small search spaces and sub-optimal for large values. Results using the differential evolution are also presented as an alternative low computational effort. The application of these methods provides alternatives for transporting different products in a defined time horizon and compare heuristic methods with continuous and binary encodings. Such results encourage the use of heuristic algorithms with continuous coding and the point discretization methods as effective for solving problems discrete alternatives.
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Thorin, Kristoffer. "Optimal Speed Controller in the Presence of Traffic Lights." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325352.
Повний текст джерелаАнотація:
This report presents an approach on how to utilize information on future states of traffic lights to reduce the energy consumption and trip time for a Heavy Duty Vehicle. Model Predictive Control is proposed as a solution to handle the optimisation on-line and the concept is tested for various prediction horizons in which information can be received. Further on, it is investigated if the implemented controller is robust enough to execute the same task in a scenario where only the current state is known and future states are predicted. Comparison with a reference vehicle demonstrates improved fuel economy as well as reduced trip time when the information is given. It is shown that the results are improved as the prediction horizon is extended, but converges after 400-500 meters. As the phases of the traffic lights are predicted, fuel economy can be improved, but it comes at a price from being non-robust with drastic braking and increased trip time as predictions might be inaccurate.
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Berzins, Louise, and Josefine Sohlman. "Linjär blandningsoptimering för skrotanvändning i aluminiumproduktion." Thesis, KTH, Hållbar produktionsutveckling (ML), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254223.
Повний текст джерелаАнотація:
Målet har varit att öka andelen skrotanvändning i omsmältan med hjälp av linjärprogrammering som en optimering vid en aluminiumindustri, vilket uppnåddes. Det har gjorts en nulägesanalys om hur aluminium används, hur produktionen fungerar samt var det faller ut skrot. Följande har en teoretisk referensram upprättats med källor från tidigare problem som lösts med linjärprogrammering, en beskrivning av linjärprogrammering och en matematisk uppställning. Det har också beskrivits hur problemet ställts upp, vilka infallsvinklar som använts och de resultat som optimeringen gett. Det har även gjorts arbete kring den måluppfyllande optimeringen som presenterats efter resultatet, vilket följs av en diskussion och slutsats med rekommendationer för framtida arbete inom ämnet. Optimeringen är gjord både mot volym som målfunktion, vilket ger en ökad användning av skrotet, och med pris som målfunktion, som bidrar till en minskad kapitalbindning i skrotet som finns kvar. Dagslägets användning av skrot uppgår till cirka 30 % per år medan optimeringsmodellen gjord på endast 17 av 72 recept skulle kunna få i så mycket som 90 % av hela årets producerade skrot. En optimering på endast ett recept visar också på att det är möjligt att smälta om och producera gjutlegeringar bestående av hög andel enbart skrot.<br>The aim with this project was to increase the amount of used scrap in the remelt of aluminum alloys by using linear programming, which was successfully done. A status analysis about the average use and characteristics of aluminum has been described, as well as a mapping of the todays industry within the company. This is followed by a theoretical chapter containing references from previous work solved with linear programming, and a description of LP including the mathematical model. The attempt to solve this problem is carefully shown in the forthcoming chapters together with the different approaches that were used. The results are presented with analysis of each optimization, followed by a discussion and a conclusion including future recommendations. The model is used with two different objective functions to get perspective, volume to maximize the amount of used scrap and price to increase use of high valued alloys in order to decrease capital accumulation within the non-used scrap. The remelt process of today consumes about 30 % of the total scrap produced during one year. This model shows that it is possible, by having 17 out of 72 recipes, to use 90 % of all scrap. One optimization for a single recipe also proved that it is possible to produce an alloy consisting of basically scrap.
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Feng, Cong. "Projection Algorithm for Improved Corridor Signal Coordination." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1257370852.
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Wang, Shuo. "Development and Implementation of a Network-Level Pavement Optimization Model." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321624751.
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Wang, Yue. "Performance and Power Optimization of GPU Architectures for General-purpose Computing." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5325.
Повний текст джерелаАнотація:
Power-performance efficiency has become a central focus that is challenging in heterogeneous processing platforms as the power constraints have to be established without hindering the high performance. In this dissertation, a framework for optimizing the power and performance of GPUs in the context of general-purpose computing in GPUs (GPGPU) is proposed. To optimize the leakage power of caches in GPUs, we dynamically switch the L1 and L2 caches into low power modes during periods of inactivity to reduce leakage power. The L1 cache can be put into a low-leakage (sleep) state when a processing unit is stalled due to no ready threads to be scheduled and the L2 can be put into sleep state during its idle period when there is no memory request. The sleep mode is state-retentive, which obviates the necessity to flush the caches after they are woken up, thereby, avoiding any performance degradation. Experimental results indicate that this technique can reduce the leakage power by 52% on average. Further, to improve performance, we redistribute the GPGPU workload across the computing units of the GPU during application execution. The fundamental idea is to monitor the workload on each multi-processing unit and redistribute it by having a portion of its unfinished threads executed in a neighboring multi-processing unit. Experimental results show this technique improves the performance of the GPGPU workload by 15.7%. Finally, to improve both performance and dynamic power of GPUs, we propose two dynamic frequency scaling (DFS) techniques implemented on CPU host threads, one of which is motivated by the significance of the pipeline stalls during GPGPU execution. It applies a feedback controlling algorithm, Proportional-Integral-Derivative (PID), to regulate the frequency of parallel processors and memory channels based on the occupancy of the memory buffering queues. The other technique targets on maximizing the average throughput of all parallel processors under the dynamic power constraints. We formalize this target as a linear programming problem and solve it on the runtime. According to the simulation results, the first technique achieves more than 22% power savings with a 4% improvement in performance and the second technique saves 11% power consumption with 9% performance improvement. The contributions of this dissertation represent a significant advancement in the quest for improving performance and reducing energy consumption of GPGPU.
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Ribas, Paulo Cesar. "Otimização do scheduling de movimentações de um duto com uma origem e vários destinos." Universidade Tecnológica Federal do Paraná, 2012. http://repositorio.utfpr.edu.br/jspui/handle/1/400.
Повний текст джерелаАнотація:
O presente trabalho desenvolve um modelo de apoio à tomada de decisão de atividades de scheduling em um sistema de dutos sequenciais, com uma origem e vários destinos. Esse modelo foi inserido em uma ferramenta computacional que possibilita a realização de estudos de caso em um duto real denominado OSBRA, que a partir da maior refinaria brasileira, a REPLAN, abastece cinco órgãos localizados em quatro unidades da federação diferentes. O sistema proposto baseia seu método na execução iterativa de um modelo de programação linear inteira mista, com o horizonte de tempo sendo deslocado com o intuito de se atingir uma programação para um período de no mínimo um mês. São consideradas no modelo as principais características operacionais do OSBRA, como variação da vazão em função da entrada ou saída de sangrias de recebimento, sempre respeitando os limites de vazão tanto dos trechos de dutos quanto das sangrias. Outras características do sistema real contempladas no modelo são o recebimento por parte das bases intermediárias exclusivamente por sangria, ou seja, apenas uma parte da batelada é recebida evitando, desta forma, a parada dos trechos de duto a jusante; variação diária de demanda e utilização de bateladas selo para evitar a contaminação entre produtos adjacentes. Dezoito cenários do sistema OSBRA, com diferentes características sazonais, foram submetidos ao modelo, que obteve soluções de grande qualidade, atingindo-se um nível de serviço satisfatório na grande maioria dos cenários.<br>This thesis presents a model to support decision making of scheduling activities in a sequential pipeline system, composed by one refinery source and multiple destinations. This model is inserted into a system and used to develop a case study in the real world pipeline system called OSBRA that links the largest refinery in Brazil, REPLAN, to five terminals located in four different states. The proposed system relies its method in the iterative execution of a model of mixed integer linear programming, with the time horizon being moved in order to achieve a schedule for a period of at least one month. The main operational features and restrictions of OSBRA are considered in this model, as the flow variation due to the entry or exit of bleeding receiving, always within the limits of both the flow sections of pipelines as of bleeding. Others features of the real system contemplated in the model are the receiving by the intermediate bases exclusively by bleeding, meaning that only part of the batch is received thus, avoiding downstream stretches from the pipeline to stop, daily variance in the demand and the use of stamp batches to prevent contamination between adjacent derivatives. Eighteen scenarios of OSBRA’s system were submitted to the model and high quality solutions were obtained, reaching a satisfactory level of service in most scenarios.
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Koker, Ezgi. "Chance Constrained Optimization Of Booster Disinfection In Water Distribution Networks." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613640/index.pdf.
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Quality of municipal water is sustained by addition of disinfectant, generally chlorine, to the water distribution network. Because of health problems, chlorine concentration in the network is limited between maximum and minimum limits. Cancerogenic disinfectant by-products start to occur at high concentrations so it is desired to have minimum amount of chlorine without violating the limit. In addition to the health issues, minimum injection amount is favorable concerning cost. Hence, an optimization model is necessary which covers all of these considerations. However, there are uncertain factors as chlorine is reactive and decays both over time and space. Thus, probabilistic approach is necessary to obtain reliable and realistic results from the model. In this study, a linear programming model is developed for the chance constrained optimization of the water distribution network. The objective is to obtain minimum amount of injection mass subjected to maintaining more uniformly distributed chlorine concentrations within the limits while considering the randomness of chlorine concentration by probability distributions. Network hydraulics and chlorine concentration computations are done by the network simulation software, EPANET.
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Elius, Ian M. "Re-engineering graduate medical education an analysis of the contribution of residents to teaching hospitals utilizing a model of an internal medicine residency program /." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001258.
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Bueno, Lucas. "Otimização do scheduling do transporte de derivados escuros de petróleo em uma malha dutoviária." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1893.
Повний текст джерелаАнотація:
Apresenta-se neste trabalho uma abordagem para a otimização do scheduling do transporte de derivados escuros de petróleo, em uma malha dutoviária. A malha em questão possui 4 refinarias, 3 nós intermediários e um terminal marítimo. A movimentação dos derivados é influenciada por necessidades e restrições políticas e operacionais, o que torna o problema de scheduling complexo e motiva o desenvolvimento desta dissertação. Algumas características deste problema devem ser notadas, como a necessidade da realização de trocas de produtos nos tanques durante um horizonte de programação e da realização de misturas de dois produtos para obtenção de um terceiro. Descreve-se uma abordagem onde se contempla o tratamento de grupos de produtos com o estoque unificado. Onde também, no modelo de planejamento, o balanço de inventário é o fator determinante na otimização e se manipulam diferentes períodos devido a existência da troca de produtos nos tanques, manutenção nos tanques e períodos em que os dutos ficam sem movimentação. Onde também é tratada de forma mais precisa do que trabalhos anteriores a questão do parque de tancagem e onde são tratadas as restrições de aquecimento e misturas. Utiliza-se uma decomposição do problema e modelos de Programação Linear Inteira Mista (PLIM) e heurísticas para solução destes subproblemas em um tempo computacional aceitável (menos de 1 minuto). Utilizam-se dados reais de operação desta malha para experimentação. Conclui-se com a análise dos resultados que a abordagem aqui descrita para resolução do problema apresentado é viável em termos computacionais e que os resultados obtidos podem auxiliar os especialistas da rede no processo de tomada de decisões.<br>In this work it is presented an approach to the optimization of the scheduling of heavy oil derivatives transportation in a pipeline network. There are four refineries in this network, three intermediate nodes and one maritime terminal. The derivatives transport is influenced by practical constraints and political needs, and so the scheduling problem is complex, which encourages the development of the current work. Some characteristics of this problem should be noticed, like the necessity of products exchanges on tanks during a scheduling horizon and the necessity of products blends. It is described an approach in which groups of products with unified inventory are treated. An approach in which, on the planning model, the main objective to optimize is the balance of the inventory and different periods are handled due the existence of products exchange on tanks, maintenance of tanks and periods in which the pipelines should not be used due heating constraints. The tanking park problem is also addressed in a more precise way than previous works. Heating constraints and blends of products are also treated. To solve this problem in a reasonable computational time (less than 1 minute) it is utilized a decomposition approach and Mixed Integer Linear Programming (MILP) models and heuristics to solve these sub-problems. It is also used real operational data of this pipeline network for experimentation purposes. With the analysis of the results it is concluded that the approach here described for the solution of the presented problem is viable in computational times terms and that the obtained results can assist the specialists of the network in the decision-making process.
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Felizari, Luiz Carlos. "Programação das operações de transporte de derivados de petróleo em redes de dutos." Universidade Tecnológica Federal do Paraná, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/121.
Повний текст джерелаАнотація:
Este trabalho desenvolve uma estrutura de otimização que auxilia a tarefa de escalonamento das atividades de transporte de derivados de petróleo em uma rede de dutos. A malha dutoviária em estudo é utilizada para o transporte de derivados leves de petróleo com alto valor agregrado, sendo composta por 9 áreas (3 refinarias, 1 porto e 5 terminais). dentro deste cenário, a busca por resultados práticos considerando uma carga computacional aceitável torna-se um grande desafio. A abordagem adotada baseia-se na decomposição do problema, onde é investigada a aplicação de um modelo de programação linear inteira mista (Mixed Integer Linear Programming - MILP) com domínio de tempo contínuo para determinar o escalonamento das operações de curto-prazo da rede de dutos. Em função da abordagem hierárquica proposta, a etapa de ordenação da lista de bateladas utilizada na fase de temporização foi inicialmente desenvolvida através de heur´siticas construtivas que falham em situações particulares. Neste sentido, o problema de ordenação é reformulado através do emprego de estruturas de alto nível presentes em técnicas de programação lógica por restrições (Constraint Logic Programming - CLP). Na forma como é apresentada, a estrutura desenvolvida vem sendo extensivamente testada em cenários reais envolvendo mais de 100 bateladas para o horizonte de aproximadamente um mês. A partir desta ferramenta, novas programações de curto-prazo serão propostas, programações existentes serão validadas e informações de diagnóstico da rede serão obtidas de forma a auxiliar o processo de tomada de decisão operacional.<br>This work addresses an optimisation structure to support the operational decision-making of scheduling activities in a real world pipeline network. The used scenario to transport petroleum derivaties involves 9 areas (3 refineries, 1 harbour, and 5 distribution centres). Thus, the computational burden for determining a short-term scheduling within the considered scenario is a relevant issue. A decomposition approach is proposed to address such real-world problem. A continuous-time mixed integer linear programming model (MILP) is studied and used to determine the operational short-term scheduling. In this context of multilevel hierarchical structure, sequencing of activities are carried out by a heuristic algorithm which can fail for some particular cases. Thus, we propose to reformulate the sequencing problem by using high-level constructs of Constraint Logic Programming (CLP). The optimisation structure has been extensively tested in typical operational scenarios which, involve in general more than 100 batches. The scheduling horizon is considered to be about 1 month. Many insights have been derived from the obtained solutions, and the proposed approach can support the decision-making process.
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Carnal, David D. "An enhanced implementation of models for electric power grid interdiction." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FCarnal.pdf.
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He, Jincan, and Sundhanva Bhatt. "Mission Optimized Speed Control." Thesis, KTH, Fordonsdynamik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-223334.
Повний текст джерелаАнотація:
Transportation underlines the vehicle industry's critical role in a country's economic future.The amount of goods moved, specically by trucks, is only expected to increase inthe near future. This work attempts to tackle the problem of optimizing fuel consumptionin Volvo trucks, when there are hard constraints on the delivery time and speed limits.Knowledge of the truck such as position, state, conguration etc., along with the completeroute information of the transport mission is used for fuel optimization.Advancements in computation, storage, and communication on cloud based systems, hasmade it possible to easily incorporate such systems in assisting modern eet. In this work,an algorithm is developed in a cloud based system to compute a speed plan for the completemission for achieving fuel minimization. This computation is decoupled from thelocal control operations on the truck such as prediction control, safety, cruise control, etc.;and serves as a guide to the truck driver to reach the destination on time by consumingminimum fuel.To achieve fuel minimization under hard constraints on delivery (or arrival) time andspeed limits, a non-linear optimization problem is formulated for the high delity modelestimated from real-time drive cycles. This optimization problem is solved using a Nonlinearprogramming solver in Matlab.The optimal policy was tested on two drive cycles provided by Volvo. The policy wascompared with two dierent scenarios, where the mission demands hard constraints ontravel time and the speed limits in addition to no trac uncertainties (deterministic). with a cruise controller running at a constant set speed throughout the mission. Itis observed that there is no signicant fuel savings. with maximum possible fuel consumption; achieved without the help of optimalspeed plan (worst case). It is seen that there is a notable improvement in fuelsaving.In a real world scenario, a transport mission is interrupted by uncertainties such as trac ow, road blocks, re-routing, etc. To this end, a stochastic optimization algorithm is proposedto deal with the uncertainties modeled using historical trac ow data. Possiblesolution methodologies are suggested to tackle this stochastic optimization problem.
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Suryasaputra, Robert, and rsuryasaputra@gmail com. "Congestion Removal in the Next Generation Internet." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080521.114723.
Повний текст джерелаАнотація:
The ongoing development of new and demanding Internet applications requires the Internet to deliver better service levels that are significantly better than the best effort service that the Internet currently provides and was built for. These improved service levels include guaranteed delays, jitter and bandwidth. Through extensive research into Quality of Service and Differentiated Service (DiffServ) it has become possible to provide guaranteed services, however this turns out to be inadequate without the application of Traffic Engineering methodologies and principles. Traffic Engineering is an integral part of network operation. Its major goal is to deliver the best performance from an existing service provider's network resources and, at the same time, to enhance a customers' view of network performance. In this thesis, several different traffic engineering methods for optimising the operation of native IP and IP networks employing MPLS are proposed. A feature of these new methods is their fast run times and this opens the way to making them suitable for application in an online traffic engineering environment. For native IP networks running shortest path based routing protocols, we show that an LP-based optimisation based on the well known multi-commodity flow problem can be effective in removing network congestion. Having realised that Internet service providers are now moving towards migrating their networks to the use of MPLS, we have also formulated optimisation methods to traffic engineer MPLS networks by selecting suitable routing paths and utilising the feature of explicit routing contained in MPLS. Although MPLS is capable of delivering traffic engineering across different classes of traffic, network operators still prefer to rely on the proven and simple IP based routing protocols for best effort traffic and only use MPLS to route traffic requiring special forwarding treatment. Based on this fact, we propose a method that optimises the routing patterns applicable to different classes of traffic based on their bandwidth requirements. A traffic engineering comparison study that evaluates the performance of a neural network-based method for MPLS networks and LP-based weight setting approach for shortest path based networks has been performed using a well-known open source network simulator, called ns2. The comparative evaluation is based upon the packet loss probability. The final chapter of the thesis describes the software development of a network management application called OptiFlow which integrates techniques described in earlier chapters including the LP-based weight setting optimisation methodology; it also uses traffic matrix estimation techniques that are required as input to the weight setting models that have been devised. The motivation for developing OptiFlow was to provide a prototype set of tools that meet the congestion management needs of networking industries (ISPs and telecommunications companies - telcos).