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Dissertations / Theses on the topic 'Collision optimization'
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Lithgow, Anthony R. "Collision-free trajectory optimization for multiple robotic manipulators." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0004/MQ32490.pdf.
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Morris, Bradford Shepherd J. E. Shepherd J. E. "Charge-exchange collision dynamics and ion engine grid geometry optimization /." Diss., Pasadena, Calif. : California Institute of Technology, 2007. http://resolver.caltech.edu/CaltechETD:etd-02282007-154751.
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Lepird, John R. "Multi-objective optimization of next-generation aircraft collision avoidance software." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98566.
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Thesis: S.M., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"June 2015." Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 85-90).
Developed in the 1970's and 1980's, the Traffic Alert and Collision Avoidance System (TCAS) is the last safety net to prevent an aircraft mid-air collision. Although TCAS has been historically very effective, TCAS logic must adapt to meet the new challenges of our increasingly busy modern airspace. Numerous studies have shown that formulating collision avoidance as a partially-observable Markov decision process (POMDP) can dramatically increase system performance. However, the POMDP formulation relies on a number of design parameters modifying these parameters can dramatically alter system behavior. Prior work tunes these design parameters with respect to a single performance metric. This thesis extends existing work to handle more than one performance metric. We introduce an algorithm for preference elicitation that allows the designer to meaningfully define a utility function. We also discuss and implement a genetic algorithm that can perform multi-objective optimization directly. By appropriately applying these two methods, we show that we are able to tune the POMDP design parameters more effectively than existing work.
by John R. Lepird.
S.M.
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Degenhardt, Richard Kennedy III. "Self-collision avoidance through keyframe interpolation and optimization-based posture prediction." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1446.
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Simulating realistic human behavior on a virtual avatar presents a difficult task. Because the simulated environment does not adhere to the same scientific principles that we do in the existent world, the avatar becomes capable of achieving infeasible postures. In an attempt to obtain realistic human simulation, real world constraints are imposed onto the non-sentient being. One such constraint, and the topic of this thesis, is self-collision avoidance. For the purposes of this topic, a posture will be defined solely as a collection of angles formed by each joint on the avatar. The goal of self-collision avoidance is to eliminate the formation of any posture where multiple body parts are attempting to occupy the exact same space. My work necessitates an extension of this definition to also include collision avoidance with objects attached to the body, such as a backpack or armor. In order to prevent these collisions from occurring, I have implemented an effort-based approach for correcting afflicted postures. This technique specifically pertains to postures that are sequenced together with the objective of animating the avatar. As such, the animation's coherence and defining characteristics must be preserved. My approach to this problem is unique in that it strategically blends the concept of keyframe interpolation with an optimization-based strategy for posture prediction. Although there has been considerable work done with methods for keyframe interpolation, there has been minimal progress towards integrating a realistic collision response strategy. Additionally, I will test this optimization-based approach through the use of a complex kinematic human model and investigate the use of the results as input to an existing dynamic motion prediction system.
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Woerner, Kyle. "COLREGS-Compliant Autonomous Collision Avoidance Using Multi-Objective Optimization with Interval Programming." Thesis, Monterey, California. Naval Postgraduate School, 2014. http://hdl.handle.net/10945/43076.
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CIVINSHigh contact density environments are becoming ubiquitous in autonomous marine vehicle (AMV) operations. Safely managing these environments and their mission greatly taxes platforms. AMV collisions will likely increase as contact density in- creases. In situations where AMVs are not performing a collaborative mission but are using shared physical space such as multiple vehicles in the same harbor, a high demand exists for safe and e cient operation to minimize mission track deviations while preserving the safety and integrity of mission platforms. With no existing pro- tocol for collision avoidance of AMVs, much e ort to date has focused on individual ad hoc collision avoidance approaches that are self-serving, lack the uniformity of eet-distributed protocols, and disregard the overall eet e ciency when scaled to being in a contact-dense environment. This research shows that by applying interval programming and a collision avoidance protocol such as the International Regulations for Prevention of Collisions at Sea (COLREGS) to a eet of AMVs operating in the same geographic area, the eet achieves nearly identical e ciency concurrent with signi cant reductions in the collisions observed. A basic collision avoidance protocol was analyzed against a COLREGS-based algorithm while parameters key to collision avoidance were studied using Monte Carlo methods and regression analysis of both real-world and simulated statistical data. A testing metric was proposed for declaring AMVs as \COLREGS-compliant" for at-sea operations. This work tested ve AMVs simultaneously with COLREGS collision avoidance{the largest test known to date.
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Smith, Kyle A. (Kyle Alexander). "Collision avoidance system optimization for closely spaced parallel operations through surrogate modeling." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82491.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
"June 2013." Cataloged from department-submitted PDF version of thesis
Includes bibliographical references (p. 103-106).
The Traffic Alert and Collision Avoidance System (TCAS) is mandated worldwide to protect against aircraft mid-air collisions. One drawback of the current TCAS design is limited support for certain closely spaced parallel runway operations. TCAS alerts too frequently, leading pilots to often inhibit Resolution Advisories during approach. Research is underway on the Airborne Collision Avoidance System X (ACAS X), a next-generation collision avoidance system that will support new surveillance systems and air traffic control procedures. ACAS X has been shown to outperform TCAS for enroute encounter scenarios. However, the design parameters that are tuned for the enroute environment are not appropriate for closely spaced parallel operations (CSPO). One concept to enhance the safety of CSPO is a procedure-specific mode of the logic that minimizes nuisance alerts while still providing collision protection. This thesis describes the application of surrogate modeling and automated search for the purpose of tuning ACAS X for parallel operations. The performance of the tuned system is assessed using a data-driven blunder model and an operational performance model. Although collision avoidance system development normally relies on human judgment and expertise to achieve ideal behavior, surrogate modeling is efficient and effective in tuning ACAS X for CSPO as the tuned logic outperforms TCAS in terms of both safety and operational suitability
by Kyle A. Smith.
S.M.
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Gonzalez-Carrascosa, Partida Ricardo. "Optimizing manoeuvres for long collision avoidance active system of a car." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-8502.
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This project presents the development of a collision avoidance active system for cars.There is a large interest in developing avoidance system in the automotive industry since the accidents are of such nature that can be avoided if the system works as desirable e.g., in animal crossing or having the car in front stopping without the driver noticing. A control system is designed to avoid collisions by acting on the steer and brakes of a car. An algorithm is developed to optimize a fuzzy logic controller which actuates on the steer and brakes of the car. The algorithm optimizes the inputs of the car, i.e. steer and brake, to avoid the collision with the object. The optimization of the trajectory implies that the car returns to the original lane and it is the minimum time possible inthe other lane. The object is situated at different distances and the initial speed of the car also varies depending on the situations. The results are obtained by using a car model that is developed in this project in conjunction with the tyre model, [1]. Simulations show that it performs collision avoidance manoeuvres in different conditions. Furthermore, improvements of the present work are suggested that are believed to further enhance the presented algorithm.
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Han, Kyung Min. "Collision free path planning algorithms for robot navigation problem." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5021.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 29, 2008) Includes bibliographical references.
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Spencer, John Edward. "ION MOTION AND AN OPTIMIZATION OF TANDEM MASS SPECTROMETRY." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/211.
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Quadrupole ion trap(QIT) mass spectrometry has become one of the most widelyused tools in the analysis of the structure of small molecules. The motion of the ionsstored in the quadrupole ion trap is extremely important. This ion motion within thequadrupole ion trap is controlled by several factors including the m/z ratio and thecollisional cross section of the ion. Investigation of ion motion within the QIT has thepotential to elucidate a new way to separate ions based on these factors. DC tomographyexperiments allow for the trajectory of the ion motion to be measured withoutmodifications to the ion trap. The ability to use DC tomography for separation ofisomeric ions on a commercial GC/MS system was investigated.Investigation of the mass range within the ion trap is necessary for the analysis ofa wide range of molecules. The ability of the quadrupole ion trap to perform MS/MSanalyses can provide insight into the structural information of many compounds.However, there exists a low mass cut-off (LMC) within the quadrupole ion trap and thusinformation about the low m/z fragments from a parent ion is lost. Schwartz and coworkerspresented a new technique labeled pulsed q dissociation (PQD) at the 53rdAnnual ASMS Conference in San Antonio TX in 2005. PQD eliminates the LMC byperforming CID at a qz of 0.4 but, then immediately lowering the q level before the massscan in a linear ion trap. By operating the quadrupole ion trap in this same manner, lowm/z product ions can be detected. This technique and elucidation of the energetic processcontained within PQD were explored further using a modified commercial quadrupoleion trap and the results discussed in this work.
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Bishnoi, Abhiraj. "GPU-Assisted Collision Avoidance for Trajectory Optimization : Parallelization of Lookup Table Computations for Robotic Motion Planners Based on Optimal Control." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290587.
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One of the biggest challenges associated with optimization based methods forrobotic motion planning is their extreme sensitivity to a good initial guess,especially in the presence of local minima in the cost function landscape.Additional challenges may also arise due to operational constraints, robotcontrollers sometimes have very little time to plan a trajectory to perform adesired function. To work around these limitations, a common solution is tosplit the motion planner into an offline phase and an online phase. The offlinephase entails computing reference trajectories for varying parameterizationsof the task space in the form of a lookup table. During the online phase,a stripped down version of the optimizer is supplied with a suitable initialguess from the lookup table using the current state estimate of the robot andits surrounding bodies. This method helps in alleviating problems related toboth local minima and operational time constraints, by seeding the optimizerwith a suitable initial guess that allows it to converge to the global minimummuch faster.The problem however, shifts to the computational complexity of computinga lookup table of reference trajectories for a fine enough discreti- zation ofthe input state space. For many robotic scenarios of interest, it is oftenimpractical and sometimes computationally infeasible to compute a look uptable using a serial, single core implementation of the offline phase of a motionplanner. The main contribution of this work is to develop and evaluate amethod for reducing the time spent on computing a lookup table of referencetrajectories during the offline phase of motion planners based on optimalcontrol. We implement a method to offload the computation of collisionavoidance constraints during trajectory optimization on a Graphics ProcessingUnit (GPU), while simultaneously benefiting from a task based approach todistribute lookup table computations for independent subsets of the input statespace across multiple processes on a cluster of machines. We demonstrate theefficacy of the proposed method in a practical setting by implementing andevaluating it within a representative motion planner based on optimal control.We observe that the implemented method is 115x faster than the originalserial version of the planner, using 86 processes on 5 machines with standardserver grade hardware and 5 Graphics Processing Units in total. Additionally,we observe that the implemented method results in solutions identical to theoriginal serial version in 96.6% of cases, lending credibility for its use inrobotic motion planning.En av de största utmaningarna med optimeringsbaserade metoder för rörelseplaneringinom robotik är deras extrema känslighet för en bra initial gissning,särskilt i närvaro av lokala minima i kostnadsfunktionslandskapet. Ytterligareutmaningar kan också uppstå på grund av operativa begränsningar. Robotkontrollerhar ibland väldigt lite tid att planera en väg för att utföra en önskadfunktion. För att kringgå dessa begränsningar är en vanlig lösning att dela upprörelseplaneraren i en offline-fas och en online-fas. Offlinefasen inkluderarberäkning av referensvägar för olika punkter i ingångstillståndsutrymmet iform av en uppslagstabell. Under online-fasen levereras en avskalad versionav optimeraren med en lämplig initial gissning från uppslagstabellen medden aktuella uppskattningen av roboten och dess omgivande kroppar. Dennametod hjälper till att lindra problem relaterade till både lokala minima ochdriftstidsbegränsningar genom att sådd optimeraren med en lämplig initialgissning som gör att den kan konvergera till det globala minimumet mycketsnabbare.Problemet flyttas emellertid nu till beräkningskomplexiteten för att beräknaen uppslagstabell över referensvägar för ett tillräckligt fint utrymme för ingångstillståndsutrymmet.För många robotscenarier av intresse är det ofta opraktisktoch ibland beräkningsmässigt omöjligt att beräkna en uppslagstabell med hjälpav en seriell, enda kärnimplementering av offline-fasen i en rörelseplanner.Huvudbidraget till detta arbete är att utveckla och utvärdera en metod för attminska tiden som används för att beräkna en uppslagstabell över referensvägarunder offline-fasen för rörelsesplanerare baserat på optimal kontroll. Vi implementeraren metod för att utföra en kollision undvika en grafikbehandlingsenhet(GPU), medan du använder en uppgiftsbaserad metod för att distribuerauppslagningsberäkningar för oberoende delmängder av inmatningsutrymmeöver flera processer i ett kluster av maskiner. Vi demonstrerar effektivitetenav den föreslagna metoden i en praktisk miljö genom att implementeraoch utvärdera den inom en representativ rörelseplanner baserat på optimalkontroll. Vi noterar att den implementerade metoden är 115 gånger snabbareän den ursprungliga serieversionen av schemaläggaren, med 86 processer på 5maskiner med standardhårdvara och totalt 5 GPU: er. Dessutom observerarvi att den implementerade metoden resulterar i lösningar som är identiskamed den ursprungliga serieversionen i mer än 96,6 % av fallen, vilket gertrovärdighet för dess användning i robotrörelse planering.
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Serra, Romain. "Opérations de proximité en orbite : évaluation du risque de collision et calcul de manoeuvres optimales pour l'évitement et le rendez-vous." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0035/document.
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Cette thèse traite de l'évitement de collision entre un engin spatial opérationnel, appelé objet primaire, et un débris orbital, dit secondaire. Ces travaux concernent aussi bien la question de l'estimation du risque pour une paire d'objets sphériques que celle du calcul d'un plan de manoeuvres d'évitement pour le primaire. Pour ce qui est du premier point, sous certaines hypothèses, la probabilité de collision s'exprime comme l'intégrale d'une fonction gaussienne sur une boule euclidienne, en dimension deux ou trois. On en propose ici une nouvelle méthode de calcul, basée sur les théories de la transformée de Laplace et des fonctions holonomes. En ce qui concerne le calcul de manoeuvres de propulsion, différentes méthodes sont développées en fonction du modèle considéré. En toute généralité, le problème peut être formulé dans le cadre de l'optimisation sous contrainte probabiliste et s'avère difficile à résoudre. Dans le cas d'un mouvement considéré comme relatif rectiligne, l'approche par scénarios se prête bien au problème et permet d'obtenir des solutions admissibles. Concernant les rapprochements lents, une linéarisation de la dynamique des objets et un recouvrement polyédral de l'objet combiné sont à la base de la construction d'un problème de substitution. Deux approches sont proposées pour sa résolution : une première directe et une seconde par sélection du risque. Enfin, la question du calcul de manoeuvres de proximité en consommation optimale et temps fixé, sans contrainte d'évitement, est abordée. Par l'intermédiaire de la théorie du vecteur efficacité, la solution analytique est obtenue pour la partie hors-plan de la dynamique képlérienne linéariséeThis thesis is about collision avoidance for a pair of spherical orbiting objects. The primary object - the operational satellite - is active in the sense that it can use its thrusters to change its trajectory, while the secondary object is a space debris that cannot be controlled in any way. Onground radars or other means allow to foresee a conjunction involving an operational space craft,leading in the production of a collision alert. The latter contains statistical data on the position and velocity of the two objects, enabling for the construction of a probabilistic collision model.The work is divided in two parts : the computation of collision probabilities and the design of maneuvers to lower the collision risk. In the first part, two kinds of probabilities - that can be written as integrals of a Gaussian distribution over an Euclidean ball in 2 and 3 dimensions -are expanded in convergent power series with positive terms. It is done using the theories of Laplace transform and Definite functions. In the second part, the question of collision avoidance is formulated as a chance-constrained optimization problem. Depending on the collision model, namely short or long-term encounters, it is respectively tackled via the scenario approach or relaxed using polyhedral collision sets. For the latter, two methods are proposed. The first one directly tackles the joint chance constraints while the second uses another relaxation called risk selection to obtain a mixed-integer program. Additionaly, the solution to the problem of fixed-time fuel minimizing out-of-plane proximity maneuvers is derived. This optimal control problem is solved via the primer vector theory
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Thantulage, Gishantha I. F. "Ant colony optimization based simulation of 3d automatic hose/pipe routing." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4282.
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This thesis focuses on applying one of the rapidly growing non-deterministic optimization algorithms, the ant colony algorithm, for simulating automatic hose/pipe routing with several conflicting objectives. Within the thesis, methods have been developed and applied to single objective hose routing, multi-objective hose routing and multi-hose routing. The use of simulation and optimization in engineering design has been widely applied in all fields of engineering as the computational capabilities of computers has increased and improved. As a result of this, the application of non-deterministic optimization techniques such as genetic algorithms, simulated annealing algorithms, ant colony algorithms, etc. has increased dramatically resulting in vast improvements in the design process. Initially, two versions of ant colony algorithms have been developed based on, respectively, a random network and a grid network for a single objective (minimizing the length of the hoses) and avoiding obstacles in the CAD model. While applying ant colony algorithms for the simulation of hose routing, two modifications have been proposed for reducing the size of the search space and avoiding the stagnation problem. Hose routing problems often consist of several conflicting or trade-off objectives. In classical approaches, in many cases, multiple objectives are aggregated into one single objective function and optimization is then treated as a single-objective optimization problem. In this thesis two versions of ant colony algorithms are presented for multihose routing with two conflicting objectives: minimizing the total length of the hoses and maximizing the total shared length (bundle length). In this case the two objectives are aggregated into a single objective. The current state-of-the-art approach for handling multi-objective design problems is to employ the concept of Pareto optimality. Within this thesis a new Pareto-based general purpose ant colony algorithm (PSACO) is proposed and applied to a multi-objective hose routing problem that consists of the following objectives: total length of the hoses between the start and the end locations, number of bends, and angles of bends. The proposed method is capable of handling any number of objectives and uses a single pheromone matrix for all the objectives. The domination concept is used for updating the pheromone matrix. Among the currently available multi-objective ant colony optimization (MOACO) algorithms, P-ACO generates very good solutions in the central part of the Pareto front and hence the proposed algorithm is compared with P-ACO. A new term is added to the random proportional rule of both of the algorithms (PSACO and P-ACO) to attract ants towards edges that make angles close to the pre-specified angles of bends. A refinement algorithm is also suggested for searching an acceptable solution after the completion of searching the entire search space. For all of the simulations, the STL format (tessellated format) for the obstacles is used in the algorithm instead of the original shapes of the obstacles. This STL format is passed to the C++ library RAPID for collision detection. As a result of using this format, the algorithms can handle freeform obstacles and the algorithms are not restricted to a particular software package.
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Yucel, Gizem. "A Reactionary Obstacle Avoidance Algorithm For Autonomous Vehicles." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614480/index.pdf.
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This thesis focuses on the development of guidance algorithms in order to avoid a
prescribed obstacle primarily using the Collision Cone Method (CCM). The
Collision Cone Method is a geometric approach to obstacle avoidance, which forms
an avoidance zone around the obstacles for the vehicle to pass the obstacle around
this zone. The method is reactive as it helps to avoid the pop-up obstacles as well as
the known obstacles and local as it passes the obstacles and continue to the
prescribed trajectory. The algorithm is first developed for a 2D (planar) avoidance
in 3D environment and then extended for 3D scenarios. The algorithm is formed for
the optimized CCM as well. The avoidance zone radius and velocity are optimized
using constraint optimization, Lagrange multipliers with Karush-Kuhn-Tucker
conditions and direct experimentation.
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Fraga, Tatiana Balbi. "Proposição e análise de modelos híbridos para o problema de escalonamento de produção em oficina de máquinas." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3803.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNas últimas décadas, o problema de escalonamento da produção em oficina de máquinas, na literatura referido como JSSP (do inglês Job Shop Scheduling Problem), tem recebido grande destaque por parte de pesquisadores do mundo inteiro. Uma das razões que justificam tamanho interesse está em sua alta complexidade. O JSSP é um problema de análise combinatória classificado como NP-Difícil e, apesar de existir uma grande variedade de métodos e heurísticas que são capazes de resolvê-lo, ainda não existe hoje nenhum método ou heurística capaz de encontrar soluções ótimas para todos os problemas testes apresentados na literatura. A outra razão basea-se no fato de que esse problema encontra-se presente no diaa- dia das indústrias de transformação de vários segmento e, uma vez que a otimização do escalonamento pode gerar uma redução significativa no tempo de produção e, consequentemente, um melhor aproveitamento dos recursos de produção, ele pode gerar um forte impacto no lucro dessas indústrias, principalmente nos casos em que o setor de produção é responsável por grande parte dos seus custos totais. Entre as heurísticas que podem ser aplicadas à solução deste problema, o Busca Tabu e o Multidão de Partículas apresentam uma boa performance para a maioria dos problemas testes encontrados na literatura. Geralmente, a heurística Busca Tabu apresenta uma boa e rápida convergência para pontos ótimos ou subótimos, contudo esta convergência é frequentemente interrompida por processos cíclicos e a performance do método depende fortemente da solução inicial e do ajuste de seus parâmetros. A heurística Multidão de Partículas tende a convergir para pontos ótimos, ao custo de um grande esforço computacional, sendo que sua performance também apresenta uma grande sensibilidade ao ajuste de seus parâmetros. Como as diferentes heurísticas aplicadas ao problema apresentam pontos positivos e negativos, atualmente alguns pesquisadores começam a concentrar seus esforços na hibridização das heurísticas existentes no intuito de gerar novas heurísticas híbridas que reúnam as qualidades de suas heurísticas de base, buscando desta forma diminuir ou mesmo eliminar seus aspectos negativos. Neste trabalho, em um primeiro momento, são apresentados três modelos de hibridização baseados no esquema geral das Heurísticas de Busca Local, os quais são testados com as heurísticas Busca Tabu e Multidão de Partículas. Posteriormente é apresentada uma adaptação do método Colisão de Partículas, originalmente desenvolvido para problemas contínuos, onde o método Busca Tabu é utilizado como operador de exploração local e operadores de mutação são utilizados para perturbação da solução. Como resultado, este trabalho mostra que, no caso dos modelos híbridos, a natureza complementar e diferente dos métodos Busca Tabu e Multidão de Partículas, na forma como são aqui apresentados, da origem à algoritmos robustos capazes de gerar solução ótimas ou muito boas e muito menos sensíveis ao ajuste dos parâmetros de cada um dos métodos de origem. No caso do método Colisão de Partículas, o novo algorítimo é capaz de atenuar a sensibilidade ao ajuste dos parâmetros e de evitar os processos cíclicos do método Busca Tabu, produzindo assim melhores resultados.
In recent decades, the Job Shop Scheduling Ploblem (JSSP) has received great attention of researchers worldwide. One of the reasons for such interest is its high complexity. The JSSP is a combinatorial optimization problem classified as NP-Hard and, although there is a variety of methods and heuristics that are able to solve it, even today no method or heuristic is able to find optimal solutions for all benchmarcks presented in the literature. The other reason builds on noted fact that this problem is present in day-to-day of industries of various segments and, since the optimal scheduling may cause a significant reduction in production time and thus a better utilization of manufacturing resources, it can generate a strong impact on the gain of these industries, especially in cases where the production sector is responsible for most of their total costs. Among the heuristics that can be applied to the solution of this problem, the Tabu Search and the Particle Swarm Optimization show good performance for most benchmarcks found in the literature. Usually, the Taboo Search heuristic presents a good and fast convergence to the optimal or sub-optimal points, but this convergence is frequently interrupted by cyclical processes, offset, the Particle Swarm Optimization heuristic tends towards a convergence by means of a lot of computational time, and the performance of both heuristics strongly depends on the adjusting of its parameters. This thesis presents four different hybridization models to solve the classical Job Shop Scheduling Problem, three of which based on the general schema of Local Search Heuristics and the fourth based on the method Particle Collision. These models are analyzed with these two heuristics, Taboo Search and Particle Swarm Optimization, and the elements of this heuristics, showing what aspects must be considered in order to achieve a best solution of the one obtained by the original heuristics in a considerable computational time. As results this thesis demonstrates that the four models are able to improve the robustness of the original heuristics and the results found by Taboo Search.
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Horký, Aleš. "Systém pro pokročilé plánování." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234893.
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This master thesis deals with the automatic design of examinations and courses scheduling. The design is adapted to the specific requirements of the Faculty of Information Technology of Brno University of Technology. A genetic algorithm and a heuristic algorithm are employed to solve this task. The genetic algorithm is used to specify the sequence of the examinations (or the courses) and then the heuristic algorithm spread them out into a timetable. An implementation (written in Python 3) provides a fast parallel processing calculation which can generate satisfactory schedules in tens of minutes. Performed experiments show approximately 13% better results in all considered criteria in comparison with utilized examination schedules in the past. The development was periodically consulted with persons responsible for the schedule processing at the faculty. The program will be used while designing of examination schedules for the academic year 2015/2016.
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Tan, Jonathan S. "Compiler Optimization Effects on Register Collisions." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1841.
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We often want a compiler to generate executable code that runs as fast as possible. One consideration toward this goal is to keep values in fast registers to limit the number of slower memory accesses that occur. When there are not enough physical registers available for use, values are ``spilled'' to the runtime stack. The need for spills is discovered during register allocation wherein values in use are mapped to physical registers. One factor in the efficacy of register allocation is the number of values in use at one time (register collisions). Register collision is affected by compiler optimizations that take place before register allocation. Though the main purpose of compiler optimizations is to make the overall code better and faster, some optimizations can actually increase register collisions. This may force the register allocation process to spill. This thesis studies the effects of different compiler optimizations on register collisions.
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Giftsun, Nirmal. "Handling uncertainty and variability in robot control." Thesis, Toulouse, INSA, 2017. http://www.theses.fr/2017ISAT0028/document.
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Parmi les nombreuses recherches en matière de planification et de contrôle des mouvements pour des applications robotiques, l'humanité n'a jamais atteint un point où les robots seraient parfaitement fonctionnels et autonomes dans des environnements dynamiques. Bien qu'il soit controversé de discuter de la nécessité de ces robots, il est très important d'aborder les problèmes qui nous empêchent de réaliser un tel niveau d'autonomie. Ce travail de recherche tente de résoudre ces problèmes qui séparent ces deux modes de fonctionnement avec un accent particulier sur les incertitudes. Les impossibilités pratiques de capacités de détection précises entraînent une variété d'incertitudes dans les scénarios où le robot est mobile ou l'environnement est dynamique. Ce travail se concentre sur le développement de stratégies intelligentes pour améliorer la capacité de gérer les incertitudes de manière robuste dans les robots humanoïdes et industriels. Premièrement, nous nous concentrerons sur un cadre dynamique d'évitement d'obstacles proposé pour les robots industriels équipés de capteurs de peau pour la réactivité. La planification des chemins et le contrôle des mouvements sont généralement formalisés en tant que problèmes distincts de la robotique, bien qu'ils traitent fondamentalement du même problème. Les espaces de configuration à grande dimension, l'environnement changeant et les incertitudes ne permettent pas la planification en temps réel de mouvement exécutable. L'incapacité fondamentale d'unifier ces deux problèmes nous a amené à gérer la trajectoire planifiée en présence de perturbations et d'obstacles imprévus à l'aide de différents mécanismes d'exécution et de déformation de trajectoire. Le cadre proposé utilise «Stack of Tasks», un contrôleur hiérarchique utilisant des informations de proximité, grâce à un planificateur de chemin réactif utilisant un nuage de points pour éviter les obstacles. Les expériences sont effectuées avec les robots PR2 et UR5 pour vérifier la validité du procédé à la fois en simulation et in-situ. Deuxièmement, nous nous concentrons sur une stratégie pour modéliser les incertitudes des paramètres inertiels d'un robot humanoïde dans des scénarios de tâches d'équilibre. Le contrôle basé modèles est devenu de plus en plus populaire dans la communauté des robots à jambes au cours des dix dernières années. L'idée clé est d'exploiter un modèle du système pour calculer les commandes précises du moteur qui entraînent le mouvement désiré. Cela permet d'améliorer la qualité du suivi du mouvement, tout en utilisant des gains de rétroaction plus faibles, ce qui conduit à une conformité plus élevée. Cependant, le principal défaut de cette approche est généralement le manque de robustesse aux erreurs de modélisation. Dans ce manuscrit, nous nous concentrons sur la robustesse du contrôle de la dynamique inverse à des paramètres inertiels erronés. Nous supposons que ces paramètres sont connus, mais seulement avec une certaine précision. Nous proposons ensuite un contrôleur basé optimisation, rapide d'exécution, qui assure l'équilibre du robot malgré ces incertitudes. Nous avons utilisé ce contrôleur en simulation pour effectuer différentes tâches d'atteinte avec le robot humanoïde HRP-2, en présence de diverses erreurs de modélisation. Les comparaisons avec un contrôleur de dynamique inverse classique à travers des centaines de simulations montrent la supériorité du contrôleur proposé pour assurer l'équilibre du robotAmidst a lot of research in motion planning and control in concern with robotic applications, the mankind has never reached a point yet, where the robots are perfectly functional and autonomous in dynamic settings. Though it is controversial to discuss about the necessity of such robots, it is very important to address the issues that stop us from achieving such a level of autonomy. Industrial robots have evolved to be very reliable and highly productive with more than 1.5 million operational robots in a variety of industries. These robots work in static settings and they literally do what they are programmed for specific usecases, though the robots are flexible enough to be programmed for a variety of tasks. This research work makes an attempt to address these issues that separate both these settings in a profound way with special focus on uncertainties. Practical impossibilities of precise sensing abilities lead to a variety of uncertainties in scenarios where the robot is mobile or the environment is dynamic. This work focuses on developing smart strategies to improve the ability to handle uncertainties robustly in humanoid and industrial robots. First, we focus on a dynamical obstacle avoidance framework proposed for industrial robots equipped with skin sensors for reactivity. Path planning and motion control are usually formalized as separate problems in robotics. High dimensional configuration spaces, changing environment and uncertainties do not allow to plan real-time motion ahead of time requiring a controller to execute the planned trajectory. The fundamental inability to unify both these problems has led to handle the planned trajectory amidst perturbations and unforeseen obstacles using various trajectory execution and deformation mechanisms. The proposed framework uses ’Stack of Tasks’, a hierarchical controller using proximity information to avoid obstacles. Experiments are performed on a UR5 robot to check the validity of the framework and its potential use for collaborative robot applications. Second, we focus on a strategy to model inertial parameters uncertainties in a balance controller for legged robots. Model-based control has become more and more popular in the legged robots community in the last ten years. The key idea is to exploit a model of the system to compute precise motor commands that result in the desired motion. This allows to improve the quality of the motion tracking, while using lower feedback gains, leading so to higher compliance. However, the main flaw of this approach is typically its lack of robustness to modeling errors. In this paper we focus on the robustness of inverse-dynamics control to errors in the inertial parameters of the robot. We assume these parameters to be known, but only with a certain accuracy. We then propose a computationally-efficient optimization-based controller that ensures the balance of the robot despite these uncertainties. We used the proposed controller in simulation to perform different reaching tasks with the HRP-2 humanoid robot, in the presence of various modeling errors. Comparisons against a standard inverse-dynamics controller through hundreds of simulations show the superiority of the proposed controller in ensuring the robot balance
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Sarfraz, Hassan. "Kinematics and Optimal Control of a Mobile Parallel Robot for Inspection of Pipe-like Environments." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30486.
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The objective of this thesis is to analyze the kinematics of a mobile parallel robot with contribution that pertain to the singularity analysis, the optimization of geometric parameters and the optimal control to avoid singularities when navigating across singular
geometric configurations. The analysis of the workspace and singularities is performed in a prescribed reference workspace regions using discretization method. Serial and parallel singularities are analytically analyzed and all possible singular configurations are presented. Kinematic conditioning index is used to determine the robot’s proximity to a singular configuration. A method for the determination of a continuous and singularity-free workspace is detailed.
The geometric parameters of the system are optimized in various types of pipe-like
structures with respect to a suitable singularity index, in order to avoid singularities during the navigation across elbows. The optimization problem is formulated with an objective to maximize the reachable workspace and minimize the singularities. The objective function is also subjected to constraints such as collision avoidance, singularity avoidance, workspace continuity and contact constraints imposed between the boundaries and the wheels of the robot. A parametric variation method is used as a technique to optimize the design parameters. The optimal design parameters found are normalized
with respect to the width of the pipe-like structures and therefore the results are
generalized to be used in the development phase of the robot.
An optimal control to generate singularity-free trajectories when the robotic device has to cross a geometric singularity in a sharp 90◦ elbow is proposed. Such geometric singularity inherently leads to singularities in the Jacobian of the system, and therefore a modified device with augmented number of degrees of freedom is introduced to be able to generate non-singular trajectories.
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Gigan, Daniel. "Modélisation des comportements d'un pilote expert en situation de collision en vol vers une nouvelle technologie "voir et éviter" pour les drones : Pour un fonctionnalisme holistique à vocation intégrative." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0022.
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Le principe du “Voir et Eviter” est un principe essentiel pour la sécurité de l'espace aérienet nécessaire pour l'insertion des drones dans la Circulation Aérienne Générale (CAG). Lessolutions actuelles ne permettent pas toujours d'appliquer le principe du "Voir et Eviter" etn'assurent pas, par leurs actions d'évitements, une cohabitation sans risques des drones et desavions pilotés dans la CAG. Ces mêmes solutions ne permettent pas, avec un seul capteurpassif, la détermination, à tout moment, du temps restant avant collision. Ce temps estessentiel pour qualifier la dangerosité de la situation de collision et adapter, en conséquencede cette dangerosité, le comportement d'évitement. Aussi, pouvoir faire appliquer à unemachine le principe du "Voir et Eviter" tout en permettant une cohabitation sans risquesimplique un paradigme de conception basé sur la modélisation de l'être humain expert del'espace aérien, le pilote. Un tel paradigme s'applique d'ailleurs à toute problématiquenécessitant une cohabitation homme machine sans risque.Aussi, l'objectif de cette thèse est la modélisation des comportements d'un pilote expert ensituation de collision en vol. Cette modélisation permet de poser les premières basestechnologiques pour l'élaboration d'un nouveau système “Voir et Eviter” répondant auproblème d'intégration des machines dans la CAG.La modélisation proposée, résultat d'une démarche intégrative, s'appuie sur unedescription des processus cognitifs et des processus de traitement de l'information ainsi quesur l'organisation des unités ou systèmes qui encapsulent ces traitements. L'ensemble des cessystèmes et processus permet la résolution de problèmes et amène au comportementobservable qui est la solution du ou des problèmes posés par ou au travers de l'environnement.Cela a permis, notamment, la construction d'un modèle générique du processus cognitif etsensoriel d'identification par catégorisation et/ou classification d'objets. Cette modélisations'appuie mathématiquement sur les théories de régression non linéaire et sur l'utilisation desméthodes numériques pour la résolution de problèmes d'optimisation.Le nouveau système "Voir et Eviter" issu de cette modélisation, construit à partir d'unsimple capteur optique passif, émule, par des algorithmes simples, les processus de détection,de reconnaissance et de sélection d'une action amenant au comportement d'évitement dans unesituation de collision face à face avec un mobile protagoniste. Grâce au modèle générique decatégorisation et/ou de classification, le principal résultat technologique de cette thèse, qui estaussi la principale qualité de ce nouveau système "Voir et Eviter" proposé, est sa capacité àdéterminer, à tout moment, le temps restant avant la collision, avec un seul capteur passif. Deplus, par sa conception (bio et psycho mimétique), ce nouveau système pourrait bien poser lespremières bases d'une démarche de certification type Equivalent Level Of Safety (ELOS).Celle-ci permettrait alors une validation sécuritaire d'un système "Voir et Eviter" parcomparaison avec les pilotes de la CAG qui sont, par ailleurs, les véritables éléments desécurité de dernier recours de l'espace aérien actuelThe aim of this doctoral thesis is the modeling of expert pilot behaviors in flight collisions. This modeling gives the first echnologic steps to elaborate a new "sense and avoid" system allowing the future integration of Unmanned Air Vehicles in eneral air traffic. The proposed modeling is the result of global and holistic way and describes the cognitive process and he architecture of systems allowing the expression of these cognitive processes. This model allows solving the collision problem thanks to an observable and adapted piloted behavior. Besides a generic modeling of cognitive process of ategorization has been built and based on non linear regression theory and numeric methods for the resolution of ptimization problems.hanks to this global modeling, this new "sense and avoid" system is made of a simple passive optic sensor and it emulates he detection process, the recognition process and the and the actions selection process allowing the resolution of collision problem by a adapted piloted behavior. Thanks to the generic categorization modeling, the main technologic result is to be ble to determinate the Time To Collision (ITC) with a passive sensor. The determination of the TTC is essential for the 'sense and avoid" systems to get the level safety certification required to integrate drones in general air traffic
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Liang, Yan. "Reduction of collisions in Bloom filters during distributed query optimization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0013/MQ52744.pdf.
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Nolte, Rainer. "Warum Bewegungsdesign wichtig ist." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21531.
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In der mechanischen Konstruktion wissen die Maschinenentwickler seit Jahrzehnten, dass Maschinen schneller, ruhiger und verlässlicher laufen, wenn man sich mit der Gestaltung der Bewegungen Mühe gibt und im Hinblick auf die Dynamik optimiert. Seit etlichen Jahren ersetzen mehr und mehr Servoantriebe die mechanischen Kurven, und die Verantwortung für die Bewegungsgestaltung geht auf SPS-Programmierer bzw. E-Techniker über. An Hand von Beispielen wird aufgezeigt, warum es auch bei flexiblen Antriebskonzepten mit Servomotoren wichtig ist, sich mit Bewegungsdesign jenseits des beliebten Polynoms 5. Grades zu beschäftigen, und was man durch Bewegungsdesign für die Maschinen erreichen kann.
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Nikolajevic, Konstanca. "Système décisionnel dynamique et autonome pour le pilotage d'un hélicoptère dans une situation d'urgence." Thesis, Valenciennes, 2016. http://www.theses.fr/2016VALE0008/document.
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Dans un contexte industriel aéronautique où les problématiques de sécurité constituent un facteur différentiateur clé, l’objectif de cette thèse est de répondre à la problématique ambitieuse de la réduction des accidents de type opérationnel. Les travaux de recherche s’inscrivent dans le domaine des systèmes d’alarmes pour l’évitement de collision qui ne font pas une analyse approfondie des solutions d’évitement par rapport à la situation de danger. En effet, les situations d’urgence en vol ne bénéficient pas à ce jour d’une représentation et d’un guide des solutions associées formels. Bien que certains systèmes d’assistance existent et qu’une partie de la connaissance associée aux situations d’urgence ait pu être identifiée, la génération dynamique d’une séquence de manœuvres sous fortes contraintes de temps et dans un environnement non connu à l’avance représente une voie d’exploration nouvelle. Afin de répondre à cette question et de rendre objective la notion de danger, les travaux de recherche présentés dans cette thèse mettent en confrontation la capacité d’évolution d’un aéronef dans son environnement immédiat avec une enveloppe physique devenant contraignante. Afin de mesurer ce danger, les travaux de recherche ont conduit à construire un module de trajectoires capable d’explorer l’espace en 3D. Cela a permis de tirer des enseignements en terme de flexibilité des manœuvres d’évitement possibles à l’approche du sol. De plus l’elicitation des connaissances des pilotes et des experts d’Airbus Helicopters (ancien Eurocopter) mis en situation d’urgence dans le cas d’accidents reconstitués en simulation a conduit à un ensemble de paramètres pour l’utilisation de la méthode multicritère PROMETHEE II dans le processus de prise de décision relatif au choix de la meilleure trajectoire d’évitement et par conséquent à la génération d’alarmes anti-collisionIn the aeronautics industrial context, the issues related to the safety constitute a highly differentiating factor. This PhD thesis addresses the challenge of operational type accident reduction. The research works are positioned and considered within the context of existing alerting equipments for collision avoidance, who don’t report a thorough analysis of the avoidance manoeuvres with respect to a possible threat. Indeed, in-flight emergency situations are various and do not all have a formal representation of escape procedures to fall back on. Much of operational accident scenarios are related to human mistakes. Even if systems providing assistance already exist, the dynamic generation of a sequence of manoeuvres under high constraints in an unknown environment remain a news research axis, and a key development perspective. In order to address this problematic and make the notion of danger objective, the research works presented in this thesis confront the capabilities of evolution of an aircraft in its immediate environment with possible physical constraints. For that purpose, the study has conducted to generate a module for trajectory generation in the 3D space frame, capable of partitioning and exploring the space ahead and around the aircraft. This has allowed to draw conclusions in terms of flexibility of escape manoeuvres on approach to the terrain. Besides, the elicitation of the Airbus Helicopters (former Eurocopter) experts knowledge put in emergency situations, for reconstituted accident scenarios in simulation, have permitted to derive a certain number of criteria and rules for parametrising the multicriteria method PROMETHEE II in the process for the relative decision-making of the best avoidance trajectory solution. This has given clues for the generation of new alerting rules to prevent the collisions
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Hosack, Michael G. "Optimization of particle tracking for experiment E683 at Fermi National Laboratory." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941370.
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The subject of this thesis is the improvement of particle tracking through the identification and correction of small systematic errors in particle "hit" locations due to positioning of tracking detectors. These errors call be as large or larger than the statistical spatial resolution of tracking detectors themselves, and therefore must be corrected. The focus is on identification and correction of errors due to rotations and beam axis translations.An algorithm is developed for use with proportional wire chamber and drift chamber detectors in experiment E683 at the Wideband facility of Fermi National Laboratory. In this experiment, high energy (tens of GeV) particles, primarily mesons, were produced when photons with energies of 40-400 GeV struck a metal or liquid target.At the present time, the method and code developed for this thesis has not been applied to real data, although an analysis of its effectiveness as a function of detector resolution has been investigated with Monte-Carlo simulations.Department of Physics and Astronomy
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Higgs, Jessica Marie. "Ion Trajectory Simulations and Design Optimization of Toroidal Ion Trap Mass Spectrometers." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6652.
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Ion traps can easily be miniaturized to become portable mass spectrometers. Trapped ions can be ejected by adjusting voltage settings of the radiofrequency (RF) signal applied to the electrodes. Several ion trap designs include the quadrupole ion trap (QIT), cylindrical ion trap (CIT), linear ion trap (LIT), rectilinear ion trap (RIT), toroidal ion trap, and cylindrical toroidal ion trap. Although toroidal ion traps are being used more widely in miniaturized mass spectrometers, there is a lack of fundamental understanding of how the toroidal electric field affects ion motion, and therefore, the ion trap's performance as a mass analyzer. Simulation programs can be used to discover how traps with toroidal geometry can be optimized. Potential mapping, field calculations, and simulations of ion motion were used to compare three types of toroidal ion traps: a symmetric and an asymmetric trap made using hyperbolic electrodes, and a simplified trap made using cylindrical electrodes. Toroidal harmonics, which represent solutions to the Laplace equation in a toroidal coordinate system, may be useful to understand toroidal ion traps. Ion trapping and ion motion simulations were performed in a time-varying electric potential representing the symmetric, second-order toroidal harmonic of the second kind—the solution most analogous to the conventional, Cartesian quadrupole. This potential distribution, which we call the toroidal quadrupole, demonstrated non-ideal features in the stability diagram of the toroidal quadrupole which were similar to that for conventional ion traps with higher-order field contributions. To eliminate or reduce these non-ideal features, other solutions to the Laplace equation can be added to the toroidal quadrupole, namely the toroidal dipole, toroidal hexapole, toroidal octopole, and toroidal decapole. The addition of a toroidal hexapole component to the toroidal quadrupole provides improvement in ion trapping, and is expected to play an important role in optimizing the performance of all types of toroidal ion trap mass spectrometers.The cylindrical toroidal ion trap has been miniaturized for a portable mass spectrometer. The first miniaturized version (r0 and z0 reduced by 1/3) used the same central electrode and alignment sleeve as the original design, but it had too high of capacitance for the desired RF frequency. The second miniaturized version (R, r0, and z0 reduced by 1/3) was designed with much less capacitance, but several issues including electrode alignment and sample pressure control caused the mass spectra to have poor resolution. The third miniaturized design used a different alignment method, and its efficiency still needs to be improved.
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Fronze, Gabriele Gaetano. "Study of quarkonium production in ultra-relativistic nuclear collisions with ALICE at the LHC : and optimization of the muon identification algorithm." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2019. http://www.theses.fr/2019IMTA0132/document.
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ALICE est dédié à l'étude d'un état de la matière nucléaire dans lequel les quarks et les gluons ne sont plus confinés dans les hadrons, qui est appelé Quark Gluon Plasma (QGP). La production de bottomonia (états liés beauté antibeauté) est sensible au QGP parce-que les états du bottomonium sont formés avant la formation du QGP et traversent le plasma pendant son évolution. L'objectif principal de cette thèse est la mesure des modification des mésons Upsilon dans le canal de désintégration en deux muons en collisions Pb-Pb à √SNN = 5.02 TeV. En outre, un nouveau framework pour l'analyse des performances des détecteurs utilisés pour l'identification des muons a été réalisé et utilisé pour l'analyse des données du RUN1 et RUN2 du LHC. Enfin, et avec l’objectif d’optimiser des résultats de l’analyse, un nouvel algorithme d’identification de muons a été développé. Cet algorithme deviendra nécessaire pour faire face aux nouvelles conditions de prise de données du RUN3, pendant lequel une reconstitution quasi-en ligne du détecteur est prévueALICE is devoted to the study of a deconfined state of nuclear matter called Quark Gluon Plasma (QGP), in which quarks and gluons behave as free particles. The bottomonium (bound states of beauty-anti beauty quark) production is affected by the presence of the QGP, since bottomonium states are produced sooner than the QGP and witness the whole evolution of the plasma. In this analysis the data coming from Pb-Pb collisions have been analysed in order to detect possible modifications of the production rates in the dimuon decay channel, with respect to the rates observed in proton-proton collisions. Furthermore, the performances of the detectors involved in the muon identification during the LHC RUN1 and RUN2 has been tested using a new analysis framework implemented as part of this thesis. Finally, in order to optimize the results of future analyses, a new muon identification algorithm has been developed and tested. This algorithm will become necessary in the LHC RUN3 running conditions, when the much higher luminosity will require a quasi online reconstruction of data
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Rosenblatt, Nicolas. "Contribution à la conception robuste de véhicules en choc frontal : détection de défaillances en crash." Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0014/document.
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Ce mémoire s’intéresse à la conception robuste de systèmes complexes dans le cadre de l’ingénierie système et de la méthode First Design. Ces travaux s’appliquent plus particulièrement aux prestations en choc frontal de véhicules de la gamme Renault. L’objectif principal de ces travaux est de proposer une méthode de conception robuste basée sur la modélisation numérique des prestations crash du véhicule. Cette stratégie vise à assurer la robustesse du produit dès la phase de conception, afin d’éviter des modifications de conception tardives et coûteuses, conséquences d’apparition de problèmes durant le cycle de validation ou la vie série du véhicule. Les spécificités du crash sont le coût important des simulations, la forte non linéarité du phénomène, ainsi que les bifurcations de comportement. Ces particularités rendent les méthodes classiques de conception robuste peu efficaces ou très couteuses. Afin de répondre à ce problème, nous développons une méthode originale, baptisée détection de défaillances, permettant d’identifier les problèmes de robustesse en crash, afin de les corriger dès le cycle de conception. Cette méthode est basée sur l’utilisation des techniques d’optimisation par les plans d’expériences. La méthode développée vise aussi à intégrer l’expertise des concepteurs crash afin de localiser rapidement les défaillances, ce qui permet de limiter le nombre de simulations nécessaires. La contrepartie d’une méthode de conception robuste reposant sur la simulation numérique est la nécessité d’avoir un bon niveau de confiance dans les résultats du modèle. On propose donc dans ce mémoire des améliorations des modèles éléments finis des véhicules Renault, afin d’améliorer la qualité de la simulation. Ces travaux vont dans le sens d’un remplacement des prototypes physiques par des prototypes numériques dans l’industrie, enjeu majeur permettant la réduction des coûts et des délais de développement. Cet enjeu est particulièrement important dans un secteur automobile très concurrentiel, où la survie d’un constructeur dépend de ses coûts et de sa réactivité face au marchéThis PhD thesis deals with robust design of complex products, within the framework of system engineering methods, such as First Design. This work focuses on frontal crashworthiness of Renault vehicles. The main goal of this PhD is to develop a robust design method based on crashworthiness numerical simulation. This method aims at ensuring the robustness of a vehicle crashworthiness right from the design stage of the product, in order to avoid costly design modifications, necessary when problems are found during the validation cycle or the life cycle of the product. Characteristics of crashworthiness phenomena are a high cost of numerical simulation, highly non-linear and bifurcative behaviour. Due to this behaviour, classic robust design methods would be unefficient or very expensive to use. In order to face this problem, we develop an original robust design method, based on optimization using design of experiments method. The goal of this method is to identify crash failures as soon as possible in the design stage, in order to correct them. This method also aims at integrating knowledge from the crash engineers, in order to find crash failures quickly, using as few simulations as possible. A challenge we meet when using numerical simulation of the crashworthiness is the need to trust the results of the model. This thesis also deals with improvements in the crash models at Renault. This work is well suited for a very competitive industry such as the automotive, where car manufacturers need to replace physical prototypes with numerical ones, in order to reduce design costs and be more reactive
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Genest, Laurent. "Optimisation de forme par gradient en dynamique rapide." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC022/document.
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Afin de faire face aux nouveaux challenges de l’industrie automobile, les ingénieurs souhaitent appliquer des méthodes d’optimisation à chaque étape du processus de conception. En élargissant l’espace de conception aux paramètres de forme, en augmentant leur nombre et en étendant les plages de variation, de nouveaux verrous sont apparus. C’est le cas de la résistance aux chocs. Avec les temps de calcul long, la non-linéarité, l’instabilité et la dispersion numérique de ce problème de dynamique rapide, la méthode usuellement employée, l’optimisation par plan d’expériences et surfaces de réponse, devient trop coûteuse pour être utilisée industriellement. Se pose alors la problématique suivante : Comment faire de l’optimisation de forme en dynamique rapide avec un nombre élevé de paramètres ?. Pour y répondre, les méthodes d’optimisation par gradient s’avèrent être les plus judicieuses. Le nombre de paramètres a une influence réduite sur le coût de l’optimisation. Elles permettent donc l’optimisation de problèmes ayant de nombreux paramètres. Cependant, les méthodes classiques de calcul du gradient sont peu pertinentes en dynamique rapide : le coût en nombre de simulations et le bruit empêchent l’utilisation des différences finies et le calcul du gradient en dérivant les équations de dynamique rapide n’est pas encore disponible et serait très intrusif vis-à-vis des logiciels. Au lieu de déterminer le gradient, au sens classique du terme, des problèmes de crash, nous avons cherché à l’estimer. L’Equivalent Static Loads Method est une méthode permettant l’optimisation à moindre coût basée sur la construction d’un problème statique linéaire équivalent au problème de dynamique rapide. En utilisant la dérivée du problème équivalent comme estimation du gradient, il nous a été possible d’optimiser des problèmes de dynamique rapide ayant des épaisseurs comme variables d’optimisation. De plus, si l’on construit les équations du problème équivalent avec la matrice de rigidité sécante, l’approximation du gradient n’en est que meilleure. De cette manière, il est aussi possible d’estimer le gradient par rapport à la position des nœuds du modèle de calcul. Comme il est plus courant de travailler avec des paramètres CAO, il faut déterminer la dérivée de la position des nœuds par rapport à ces paramètres. Nous pouvons le faire de manière analytique si nous utilisons une surface paramétrique pour définir la forme et ses points de contrôle comme variables d’optimisation. Grâce à l’estimation du gradient et à ce lien entre nœuds et paramètres de forme, l’optimisation de forme avec un nombre important de paramètres est désormais possible à moindre coût. La méthode a été développée pour deux familles de critères issues du crash automobile. La première est liée au déplacement d’un nœud, objectif important lorsqu’il faut préserver l’intégrité de l’habitacle du véhicule. La seconde est liée à l’énergie de déformation. Elle permet d’assurer un bon comportement de la structure lors du chocIn order to face their new industrial challenges, automotive constructors wish to apply optimization methods in every step of the design process. By including shape parameters in the design space, increasing their number and their variation range, new problematics appeared. It is the case of crashworthiness. With the high computational time, the nonlinearity, the instability and the numerical dispersion of this rapid dynamics problem, metamodeling techniques become to heavy for the standardization of those optimization methods. We face this problematic: ”How can we carry out shape optimization in rapid dynamics with a high number of parameters ?”. Gradient methods are the most likely to solve this problematic. Because the number of parameters has a reduced effect on the optimization cost, they allow optimization with a high number of parameters. However, conventional methods used to calculate gradients are ineffective: the computation cost and the numerical noise prevent the use of finite differences and the calculation of a gradient by deriving the rapid dynamics equations is not currently available and would be really intrusive towards the software. Instead of determining the real gradient, we decided to estimate it. The Equivalent Static Loads Method is an optimization method based on the construction of a linear static problem equivalent to the rapid dynamic problem. By using the sensitivity of the equivalent problem as the estimated gradient, we have optimized rapid dynamic problems with thickness parameters. It is also possible to approximate the derivative with respect to the position of the nodes of the CAE model. But it is more common to use CAD parameters in shape optimization studies. So it is needed to have the sensitivity of the nodes position with these CAD parameters. It is possible to obtain it analytically by using parametric surface for the shape and its poles as parameters. With this link between nodes and CAD parameters, we can do shape optimization studies with a large number of parameters and this with a low optimization cost. The method has been developed for two kinds of crashworthiness objective functions. The first family of criterions is linked to a nodal displacement. This category contains objectives like the minimization of the intrusion inside the passenger compartment. The second one is linked to the absorbed energy. It is used to ensure a good behavior of the structure during the crash
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Jeffery, Stacey. "Collision Finding with Many Classical or Quantum Processors." Thesis, 2011. http://hdl.handle.net/10012/6200.
Full textAbstract:
In this thesis, we investigate the cost of finding collisions in a black-box function, a problem that is of fundamental importance in cryptanalysis. Inspired by the excellent performance of the heuristic rho method of collision finding, we define several new models of complexity that take into account the cost of moving information across a large space, and lay the groundwork for studying the performance of classical and quantum algorithms in these models.
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Morris, Bradford S. "Charge-Exchange Collision Dynamics and Ion Engine Grid Geometry Optimization." Thesis, 2007. https://thesis.library.caltech.edu/807/1/thesis_main.pdf.
Full textAbstract:
The development of a new three-dimensional model for determining the absolute energy distribution of ions at points corresponding to spacecraft surfaces to the side of an ion engine is presented. The ions resulting from elastic collisions, both charge-exchange (CEX) and direct, between energetic primary ions and thermal neutral xenon atoms are accounted for. Highly resolved energy distributions of CEX ions are found by integration over contributions from all points in space within the main beam formed by the primary ions.
The sputtering rate due to impingement of these ions on a surface is calculated. The CEX ions that obtain significant energy (10 eV or more) in the collision are responsible for the majority of the sputtering, though this can depend on the specific material being sputtered. In the case of a molybdenum surface located 60 cm to the side of a 30 cm diameter grid, nearly 90% of the sputtering is due to the 5% of ions with the highest collision exit energies. Previous models that do not model collision energetics cannot predict this. The present results agree with other models and predict that the majority of the ion density is due to collisions where little to no energy is transferred.
The sputtering model is combined with a grid-structure model in an optimization procedure where the sputtering rate at specified locations is minimized by adjustment of parameters defining the physical shape of the engine grids. Constraints are imposed that require that the deflection of the grid under a specified load does not exceed a maximum value, in order to ensure survivability of the grids during launch. To faciliate faster execution of the calculations, simplifications based on the predicted behavior of the CEX ions are implemented. For diametrically opposed sputtering locations, a rounded barrel-vault shape reduces the expected sputtering rate by up to 30% in comparison to an NSTAR-shaped grid.
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Lu, Yu-Chih, and 盧昱志. "System Integration and Optimization for 6D-Vision Vehicle Collision-Avoidance." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/46987557460840313991.
Full textAbstract:
碩士國立中興大學
電機工程學系所
102
Our main purpose is to identify the object''s distance and direction by using the dual-lens camera which can handle the stereo environment. The images are presented in 1920 × 1080 resolution in the paper, so the computing time is large. The computing time to perform disparity generation is the most critical by using ARM DS-5 analysis. Therefore, the resolution reduction and the Sobel edge detection are used to reduce computation time. Then, the value of the disparity will be obtained by our proposed "diamond census adaptive support weight". Later, the value of disparity can be converted to depth information of the object''s distance. Also, with the depth information, the distance of moving object can be detected by experimenting an object''s self-moving. Our proposed methods are implemented and optimized on embedded system platform, so we use a lot of system optimization techniques such as parallel processing, simplified loop, induction variable elimination, memory allocation management and so on. With these achievements above, the function requirements can be achieved. In order to make use of the embedded platform device in the car, an embedded platform is needed to display the image handled by collision avoidance system. The embedded platform is built with a Linux system called Qt creator. The result of the collision avoidance system can be displayed based on the connecting signals and slots of objects. The driver can easily recognize the obstacles on the road due to the dynamic update of the image display system.
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CHEN, JIN-SHAN, and 陳金山. "A study of collision-free techniques and path optimization of two robot arms." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/44994601312152987344.
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Yao, Jia-Sheng, and 姚嘉昇. "Beam Angle Optimization with Patient-Specific Collision Detection for External Beam Radiation Therapy." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3gc8w3.
Full textAbstract:
碩士國立臺灣大學
資訊工程學研究所
107
Beam angle optimization is a critical issue for modern RT, and this could be challenging under non-coplanar settings. Non-coplanar radiation therapy techniques have potential dosimetry advantages but with the increase in the risk of collision. Collision detection is important in external beam radiation therapy to help eliminate the needed time to confirm the usability of selected beam angles and prevent patient machine collisions. Our goal is to establish a platform which is patient-specific to calculate the collision space before treatment planning, prevent hardware damage, and improve patient safety to help physicians choose the safe and applicable beam angles wisely for enhancing dosimetric distributions. Two different models were built and validated. Compared with our application prediction, the collision angles were predicted within the different range of 7 degrees. The confusion matrix was applied for two different linear accelerators models, and the accuracy was 0.989 (0.989 and 0.973 respectively). True positive rate (TPR) and true negative rate (TNR) were 0.978 (0.978 and 0.969) and 0.998 (0.998 and 0.980) respectively. Our application is a simple, effective, and convenient tool to simulate the collision detection without the extra equipment and further help radiation therapy treatment planning smarty for the beam angle optimization.
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Wu, Tianyang. "Ion Mobility Spectrometry : Optimization of Parameters in Collision Cross Sections and Trace Detection of Explosives." Thesis, 2018. http://hdl.handle.net/1805/17956.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.
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(5931161), Tianyang Wu. "Ion Mobility Spectrometry: Optimization of Parameters in Collision Cross Sections and Trace Detection of Explosives." Thesis, 2019.
Find full textAbstract:
Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.
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Lu, I.-Chi, and 盧意淇. "Optimization of Preparation Condition for Glabridin Nanoemulsion by Collision-High Pressure Homogenization using Response Surface Methodology." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/78811636154536213950.
Full textAbstract:
碩士大葉大學
生物產業科技學系
98
Nanoemulsion droplets size is in the range of 10-100 nm. Nanoemulsion was stable and easily absorbed through skin due to its miniaturized size. High pressure homogenization may be applicable to manufacture nanoemulsion products by providing great energy in a short time with a homogeneous flow to decrease particle size. In this study, the effects of oil (2-6%, w/w), surfactant (3-7%, w/w), and the homogenization pressure (70-130 MPa) on the particle size of emulsion were investigated using response surface methodology (RSM) with 3-factor-3-level Box-Behnken design. Based on the analysis of canonical, the effect of the number of passes of homogenization on particle size to obtain emulsion with low particle size and high stability was determined.Then, glabridin was added to the nanoemulsion as a functional ingredient, and effectiveness of the product was evaluated. Results showed that a good nanoemulsion was obtained by mixing oil 3.65% with emulsifier 5.3% and then homogenized at 129 MPa. The actual minimum particle size (58 nm) was closed to the predicted value (40.4 nm). Homogenization pressure was the key factor affecting particle size from the analysis of variance for joint test (p < 0.005). The particle size was proportionally reduced as the pressure increased. Moreover, the number of passes of homogenization could also affect the particle size, and stable particle size at about 28 nm was resulted after 3 passes of homogenization. Glabridin had a high DPPH radical scavenging activity (80%) of 1 mg/mL. Activity of tyrosinase was inhibited by 80% using 1 μg/mL of glabridin. The nanoemulsion containing glabridin retained tyrosinase inhibitory activity even after high pressure homogenization. The cumulative amount (0.086 g/mL) for the product was better than that that of non-high pressure homogenization (0.057 mg/mL) after transdermal diffusion for 24 hours. Furthermore, the glabridin nanoemulsion did not cause any irritation or allergy during the safety and stability test. In conclusion, this study showed that an optimal condition was developed for the preparation of a stable nanoemulsion, and glabridin is a highly valuable active ingredient for whitening the skin. Results also showed that the miniaturized particle of this product could be absorbed without irritation and allergy through skin while providing an effective high value skin care.
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Mott, Alexander Robert. "Search for Higgs Boson Production Beyond the Standard Model Using the Razor Kinematic Variables in pp Collisions at √s=8 TeV and Optimization of Higgs Boson Identification Using a Quantum Annealer." Thesis, 2015. https://thesis.library.caltech.edu/8845/1/AMott_PhDThesis_SubmissionVersion1.pdf.
Full textAbstract:
In the first part of this thesis we search for beyond the Standard Model physics through the search for anomalous production of the Higgs boson using the razor kinematic variables. We search for anomalous Higgs boson production using proton-proton collisions at center of mass energy √s=8 TeV collected by the Compact Muon Solenoid experiment at the Large Hadron Collider corresponding to an integrated luminosity of 19.8 fb-1.
In the second part we present a novel method for using a quantum annealer to train a classifier to recognize events containing a Higgs boson decaying to two photons. We train that classifier using simulated proton-proton collisions at √s=8 TeV producing either a Standard Model Higgs boson decaying to two photons or a non-resonant Standard Model process that produces a two photon final state.
The production mechanisms of the Higgs boson are precisely predicted by the Standard Model based on its association with the mechanism of electroweak symmetry breaking. We measure the yield of Higgs bosons decaying to two photons in kinematic regions predicted to have very little contribution from a Standard Model Higgs boson and search for an excess of events, which would be evidence of either non-standard production or non-standard properties of the Higgs boson. We divide the events into disjoint categories based on kinematic properties and the presence of additional b-quarks produced in the collisions. In each of these disjoint categories, we use the razor kinematic variables to characterize events with topological configurations incompatible with typical configurations found from standard model production of the Higgs boson.
We observe an excess of events with di-photon invariant mass compatible with the Higgs boson mass and localized in a small region of the razor plane. We observe 5 events with a predicted background of 0.54 ± 0.28, which observation has a p-value of 10-3 and a local significance of 3.35σ. This background prediction comes from 0.48 predicted non-resonant background events and 0.07 predicted SM higgs boson events. We proceed to investigate the properties of this excess, finding that it provides a very compelling peak in the di-photon invariant mass distribution and is physically separated in the razor plane from predicted background. Using another method of measuring the background and significance of the excess, we find a 2.5σ deviation from the Standard Model hypothesis over a broader range of the razor plane.
In the second part of the thesis we transform the problem of training a classifier to distinguish events with a Higgs boson decaying to two photons from events with other sources of photon pairs into the Hamiltonian of a spin system, the ground state of which is the best classifier. We then use a quantum annealer to find the ground state of this Hamiltonian and train the classifier. We find that we are able to do this successfully in less than 400 annealing runs for a problem of median difficulty at the largest problem size considered. The networks trained in this manner exhibit good classification performance, competitive with the more complicated machine learning techniques, and are highly resistant to overtraining. We also find that the nature of the training gives access to additional solutions that can be used to improve the classification performance by up to 1.2% in some regions.