Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-10-20T17:39:38Z No. of bitstreams: 2 Dissertação - Fernanda Neiva Mesquita - 2015.pdf: 2481424 bytes, checksum: 2263ae4d21d732d49ebd0e6d2e2763c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-10-21T19:23:42Z (GMT) No. of bitstreams: 2 Dissertação - Fernanda Neiva Mesquita - 2015.pdf: 2481424 bytes, checksum: 2263ae4d21d732d49ebd0e6d2e2763c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-21T19:23:42Z (GMT). No. of bitstreams: 2 Dissertação - Fernanda Neiva Mesquita - 2015.pdf: 2481424 bytes, checksum: 2263ae4d21d732d49ebd0e6d2e2763c6 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-12-15 / This study deals with problems of parallel machines with independent setup times, different dates of release and minimizing the makespan. The production environment is common in the auto industry that there may be jobs through the production line, they are added new machines or equal equipment to expand productive capacity. Any production process requires effective management by the Production Planning and Control (PCP). This activity includes the planning of production, so the allocation of resources for task execution on a time basis. The programming activity is one of the most complex tasks in the management of production because the need to deal with several different types of resources and concurrent activities. Furthermore, the number of solutions grows exponentially in several dimensions, according to the number of tasks, operations or machines, thereby generating a combinatorial nature of the problem. The environment treated in this work each task has the same processing time on any machine. Considering only the restriction independently of the task setup time waiting for processing and the presence of release dates different from zero very practical characteristics in industries. As were found in the literature work that deals of this work environment, even less that used the meta-heuristic Simulated Anneling, so we developed the method to the problem, along with the initial solution their disturbance schemes and the setting of lower bounds for the makespan. / Este estudo trata de problemas de máquinas paralelas com tempos de setup independentes, diferentes datas de liberação e minimização do makespan. Este ambiente de produção é comum na indústria automobilística que pode haver postos de trabalho em meio à linha de produção, em que são adicionadas novas máquinas ou equipamentos iguais para ampliar a capacidade produtiva. Qualquer processo produtivo requer um gerenciamento eficaz por meio do Planejamento e Controle da Produção (PCP). Esta atividade inclui a programação da produção, ou seja, a alocação de recursos para execução de tarefas em uma base de tempo. A atividade de programação é uma das tarefas mais complexas no gerenciamento da produção, pois a necessidade de lidar com diversos tipos diferentes de recursos e atividades simultâneas. Além disso, o número de soluções cresce exponencialmente em várias dimensões, de acordo com a quantidade de tarefas, operações ou máquinas, gerando assim uma natureza combinatória ao problema. O ambiente tratado neste trabalho cada tarefa tem o mesmo tempo de processamento em qualquer máquina. Considerando a restrição de tempos de setup independente apenas da tarefa que espera por processamento e a presença de datas de liberação diferentes de zero características muito práticas nas indústrias. Como não foram encontrados na literatura trabalho que tratasse desse ambiente de trabalho, ainda menos que utilizasse a meta-heurística Simulated Anneling, então foi desenvolvido o método para o problema, juntamente com a solução inicial os respectivos esquemas de perturbação e a definição de limitantes inferiores para o makespan.

Konfigurationsprotokollet Wi-Fi protected setup (WPS) har vissa brister idess design gällande hur autentiseringen av den PIN-kod som används för attansluta en enhet till ett trådlöst nätverk är implementerad. Dessa brister kanutnyttjas av en attackerare för att utföra en bruteforce-attack som på enrelativt kort tid kan identifiera den korrekta koden. Detta arbete har tagit frammetoder för att motverka eller fördröja attacker mot WPS-protokollet sommed relativt enkla medel kan implementeras i befintliga nätverk. Genomutförda praktiska experiment där en fristående server upptäckt en attack ochgenomfört olika försvarsmetoder har de mekanismer som presenterats utvärderats. Slutsatsen är att den effektivaste metoden för att avbryta en bruteforce-attackmot protokollet är att automatiskt byta ut PIN-koden då en attack upptäcks. / Wi-Fi protected setup (WPS), a protocol used to configure wireless clients, isflawed in regard to the design of the authentication procedure for the PIN-code used to connect a new device. This flaw can be exploited by an attackerto perform a brute force attack to identify the code. This report presentsmethods to counteract brute force attacks performed against the WPS-protocol. The study has been performed by practical experiments where thecountermeasures have been evaluated and their performance has beenmeasured. With simple means, such as a third party acting on the routersbehalf in implementing countermeasures against the attacker, the attack canbe counteracted. The conclusion is that the most effective way of countering the WPS-bruteforce attack presented is to automatically replace the PIN-code with arandomly generated one when an attack is detected.

Wireless Protected Setup (WPS) är ett säkerhetsprotokoll för trådlösa nätverk. Dess design medför en allvarlig säkerhetsbrist som kan möjliggöra att obehöriga kan få åtkomst till ett lösenordskyddat trådlöst nätverk. Vid attack finns det olika verktyg tillgängliga att använda. I denna rapport jämförs mjukvaruverktygen Reaver och Bully i attack mot WiFi’s WPS-protokoll, där Bullys prestanda tidigare har påvisats vara mer effektiv och förutsätts snabbare utföra brute-forceattack jämfört med Reaver. Ett praktiskt laborationsexperiment har utförts för att undersöka vilken skillnad i hastighet som kan ses mellan verktygen Reaver och Bully i en brute-forceattack. Experimentet utfördes genom att mäta tiden det tog för de två verktygen att testa 100 PIN-nycklar mot en router utan skyddsmekanismer hos WPS. Resultatet visar att Bully utför en brute-forceattack i högre hastighet jämfört med Reaver. Dock, med den högre attackhastigheten som Bully innehar, kan stabilitetsproblem vid attack medföras, vilket öppnar upp för framtida diskussion om högre hastighet bör prioriteras över stabilitet för lyckade attacker. / Wireless Protected Setup (WPS) is a security protocol for wireless networks. Its design contains a serious security flaw that could allow an attacker access to a password-protected wireless network. An attack can be executed using various tools available. In this report, the software-tools Reaver and Bully are compared in performance against WiFi’s WPS-protocol, where Bully previously has been shown to be more effective and predicted faster to execute a bruteforce-attack. A practical laboration has been executed in order to determine differences in speed that can be seen between the tools Reaver and Bully in a bruteforce-attack. The experiment was done by measuring the time it took both tools to test 100 PIN-numbers against a router without protection for WPS. The result shows that Bully performs a bruteforce-attack in higher speed compared to Reaver. However, with the higher attack-speed that Bully uses, some stability issues may follow, opening the topic of future discussion regarding priorities of speed vs. stability for successful attacks.

This dissertation is devoted to the modeling, analysis and development of solution approaches for some optimization-related problems encountered in industrial and manufacturing settings. We begin by introducing a special type of traveling salesman problem called "High Multiplicity Asymmetric Traveling Salesman Problem" (HMATSP). We propose a new formulation for this problem, which embraces a flow-based subtour elimination structure, and establish its validity for this problem. The model is, then, incorporated as a substructure in our formulation for a lot-sizing problem involving parallel machines and sequence-dependent setup costs, also known as the "Chesapeake Problem". Computational results are presented to demonstrate the efficacy of our modeling approach for both the generic HMATSP and its application within the context of the Chesapeake Problem. Next, we investigate an integrated lot-sizing and scheduling problem that is encountered in the primary manufacturing facility of pharmaceutical manufacturing. This problem entails determination of production lot sizes of multiple products and sequence in which to process the products on machines, which can process lots (batches) of a fixed size (due to limited capacity of containers) in the presence of sequence-dependent setup times/costs. We approach this problem via a two-stage optimization procedure. The lot-sizing decision is considered at stage 1 followed by the sequencing of production lots at stage 2. Our aim for the stage 1 problem is to allocate batches of products to time-periods in order to minimize the sum of the inventory and backordering costs subject to the available capacity in each period. The consideration of batches of final products, in addition to those for intermediate products, which comprise a final product, further complicates the lot-sizing problem. The objective for the stage 2 problem is to minimize sequence-dependent setup costs. We present a novel unifying model and a column generation-based optimization approach for this class of lot-sizing and sequencing problems. Computational experience is first provided by using randomly generated data sets to test the performances of several variants of our proposed approach. The efficacy of the best of these variants is further demonstrated by applying it to the real-life data collected with the collaboration of a pharmaceutical manufacturing company. Then, we address a single-lot, lot streaming problem for a two-stage assembly system. This assembly system is different from the traditional flow shop configuration. It consists of m parallel subassembly machines at stage 1, each of which is devoted to the production of a component. A single assembly machine at stage 2, then, assembles products after components (one each from the subassembly machines at the first stage) have been completed. Lot-detached setups are encountered on the machines at the first and second stages. Given a fixed number of transfer batches (or sublots) from each of the subassembly machines at stage 1 to the assembly machine at stage 2, our problem is to find sublot sizes so as to minimize the makespan. We develop optimality conditions to determine sublot sizes for the general problem, and present polynomial-time algorithms to determine optimal sublot sizes for the assembly system with two and three subassembly machines at stage 1. Finally, we extend the above single-lot, lot streaming problem for the two-stage assembly system to multiple lots, but still, for the objective of minimizing the makespan. Due to the presence of multiple lots, we need to address the issue of the sequencing of the lots along with lot-splitting, a fact which adds complexity to the problem. Some results derived for the single-lot version of this problem have successfully been generalized for this case. We develop a branch-and-bound-based methodology for this problem. It relies on effective lower bounds and dominance properties, which are also derived. Finally, we present results of computational experimentation to demonstrate the effectiveness of our branch-and-bound-based methodology. Because of the tightness of our upper and lower bounds, a vast majority of the problems can be solved to optimality at root node itself, while for others, the average gap between the upper and lower bounds computed at node zero is within 0.0001%. For a majority of these problems, our dominance properties, then, effectively truncate the branch-and-bound tree, and obtain optimal solution within 500 seconds. / Ph. D.

The group scheduling problem commonly arises in cellular manufacturing systems, where parts are grouped into part families. It is characterized by a sequencing task on two levels: on the one hand, a sequence of jobs within each part family has to be identified while, on the other hand, a family sequence has to be determined. In order to solve this NP-hard problem usually heuristic solution approaches are used. In this thesis different aspects of group scheduling are discussed and problem specific heuristics are developed to solve group scheduling problems efficiently. Thereby, particularly characteristic properties of flowshop group scheduling problems, such as the structure of a group schedule or missing operations, are identified and exploited. In a simulation study for job shop manufacturing cells several novel dispatching rules are analyzed. Furthermore, a comprehensive review of the existing group scheduling literature is presented, identifying fruitful directions for future research.

A flexible workforce or a versatile machine is employed to perform various types of operations. Often these resources are associated with setups. Whenever a worker or machine switches from processing one type of operation to another a setup time may be required although several operations of a same type can be processed in succession after a single setup. The presence of setups gives rise to the problem of choosing batch sizes that are neither too large nor too small. In the last one and a half decade, many researchers have addressed the problem of scheduling with batching. A majority of articles assumes that there is only one type of scarce resource, which is typically machine. Often there can be two scarce resources such as a worker and a machine or a machine and a tool. We propose a resource constrained scheduling model with a single operator and two or more machines. Whenever the operator changes machine, a setup time is required that may be sequence dependent or sequence independent. We consider the two cases of an open shop and a flow shop. In the open shop case, the order in which a job visits the machines is unrestricted. In the flow shop case, every job must visit the machines in the same order. We consider various scheduling objectives. For variable number of machines, many cases are intractable. We discuss some dominance properties that narrow down the search for an optimal schedule. We present a dynamic programming approach which solves a large number of cases. The running time of the dynamic program is polynomial for a fixed number of machines. For the case of two machines, we show that the dominance properties have a nice interpretation. We develop some algorithms and justify their use by establishing running times, comparing the running times with those of the existing algorithms, and testing the performance of the algorithms.

External-beam radiotherapy is one of the primary methods for treating cancer. Typically a radiotherapy treatment course consists of radiation delivered to the patient in multiple daily treatment fractions over 6-8 weeks. Each fraction requires the patient to be aligned with the image acquired before the treatment course used in treatment planning. Unfortunately, patient alignment is not perfect and results in residual errors in patient setup. The standard technique for dealing with errors in patient setup is to expand the volume of the target by some margin to ensure the target receives the planned dose in the presence of setup errors. This work develops an alternative to margins for accommodating setup errors in the treatment planning process by directly including patient setup uncertainty in IMRT plan optimization. This probabilistic treatment planning (PTP) operates directly on the planning structure and develops a dose distribution robust to variations in the patient position. Two methods are presented. The first method includes only random setup uncertainty in the planning process by convolving the fluence of each beam with a Gaussian model of the distribution of random setup errors. The second method builds upon this by adding systematic uncertainty to optimization by way of a joint optimization over multiple probable patient positions. To assess the benefit of PTP methods, a PTP plan and a margin-based plan are developed for each of the 28 patients used in this study. Comparisons of plans show that PTP plans generally reduce the dose to normal tissues while maintaining a similar dose to the target structure when compared to margin-based plans. Physician assessment indicates that PTP plans are generally preferred over margin-based plans. PTP methods shows potential for improving patient outcome due to reduced complications associated with treatment.

Problemas de sequenciamento são muito comuns, eles existem sempre que há uma escolha sobre a ordem em que várias tarefas podem ser realizadas. Seja o negócio uma companhia aérea, um hotel, um fabricante de computadores ou uma universidade, esses problemas fazem parte do cotidiano. A aplicação das técnicas de sequenciamento permite, por exemplo, a redução dos custos e o aumento na agilidade da cadeia de suprimentos, afetando as operações no inicio e no fim da cadeia de suprimentos pelo mundo inteiro. Este trabalho parte da intenção de abordar os princípios e as técnicas de Scheduling, com a finalidade de propor um modelo de sequenciamento para a solução de um problema em sistemas produtivos do tipo job shop com n tarefas e m máquinas, considerando os tempos de setup dependentes da sequência e tendo como horizonte de planejamento o curto prazo. O objetivo é o de minimizar a perda dos tempos não produtivos. Neste contexto, a pesquisa apresenta um enfoque tanto exploratório, quanto aplicado. Pode ser considerado exploratório, uma vez que a revisão da literatura é referência central para o desenvolvimento do modelo matemático. É aplicado considerando-se o desenvolvimento do modelo e avaliação de sua aplicabilidade. Sendo assim, a partir da definição do problema e desenvolvimento do modelo por meio do uso de técnicas matemáticas e abordagens da pesquisa operacional constatou-se que as conclusões tiradas podem inferir decisões para o problema real. Sendo que, as considerações aqui feitas têm por finalidade relatar os fatos constatados nos experimentos realizados, visando contribuir com futuras pesquisas na área. / Sequencing problems are very common, they happen every time there is a choice regarding the order in which several tasks can be performed. The business can be an airline, a hotel, a computer manufacturer or a university; these issues are part of their routine. The application of the sequencing techniques allows, for example, reducing the costs and fastening the supply chain all over the world. This work has an approach to Scheduling principles and techniques, with the objective of proposing a sequencing model for the solution of a problem in productive systems such as job shop with n tasks and m machines, considering setup times dependent on the sequence and adopting a short term planning. The goal is to minimize the waste of unproductive time. In this context, the research presents an approach both exploratory and applied. It can be considered exploratory, once that the literature review is a main reference to the development of a mathematical model. It is applied when we consider the development of the model and evaluation of its applicability. Thus, from the problem definition and the model development by the use of mathematical techniques and approaches of the operational research, we found that the conclusions drawn from the model might infer decisions for a real problem. The considerations shown here aim to report the facts given in the conducted experiments, intending to contribute to future researches in the area.

Les travaux présentés dans cette thèse portent sur l’ordonnancement d’applications multi-tâches linéaires de type workflow sur des plateformes distribuées. La particularité du système étudié est que le nombre de machines composant la plateforme est plus petit que le nombre de tâches à effectuer. Dans ce cas les machines sont supposées être capables d’effectuer toutes les tâches de l’application moyennant une reconfiguration, sachant que toute reconfiguration demande un temps donné dépendant ou non des tâches. Le problème posé est de maximiser le débit de l’application,c’est à dire le nombre moyen de sorties par unité de temps, ou de minimiser la période, c’est à dire le temps moyen entre deux sorties. Par conséquent le problème se décompose en deux sous problèmes: l’assignation des tâches sur les machines de la plateforme (une ou plusieurs tâches par machine), et l’ordonnancement de ces tâches au sein d’une même machine étant donné les temps de reconfiguration. Pour ce faire la plateforme dispose d’espaces appelés buffers, allouables ou imposés, pour stocker des résultats de production temporaires et ainsi éviter d’avoir à reconfigurer les machines après chaque tâche. Si les buffers ne sont pas pré-affectés nous devons également résoudre le problème de l’allocation de l’espace disponible en buffers afin d’optimiser l’exécution de l’ordonnancement au sein de chaque machine. Ce document est une étude exhaustive des différents problèmes associés à l’hétérogénéité de l’application ; en effet si la résolution des problèmes est triviale avec des temps de reconfiguration et des buffers homogènes, elle devient bien plus complexe si ceux-ci sont hétérogènes. Nous proposons ainsi d’étudier nos trois problèmes majeurs pour différents degrés d’hétérogénéité de l’application. Nous proposons des heuristiques pour traiter ces problèmes lorsqu’il n’est pas possible de trouver une solution algorithmique optimale. / In this document we tackle scheduling problems of multitask linear workflow applications ondistributed platforms. In our particular problem the number of available machines on the platformis lower than the number of stages within the pipeline. The machines are then assumed to be able toperform any kind of task on the application given the appropriate reconfiguration (or setup), the catchbeing that any reconfiguration is time consuming. The problem that we try to solve is to maximizethe throughput of such applications, i.e., the mean amount of outputs per unit of time, or to minimizeits period, i.e., the average time between two outputs. As a result this problem is split into two subproblems:mapping tasks onto different machines of the platform (most machines will likely handleseveral tasks), and find an optimal schedule within a machine while taking setup times into account.To solve this we introduce buffers, which are spaces available for each machine to store temporaryproduction results and avoid reconfiguring after each task execution, and which may or may notbe already allocated for each stage. If those buffers are not already allocated to each task then athird problem must be solved to properly allocate the available space onto each buffer, as differentbuffer configurations have a huge impact on the scheduling of a machine. This document presentsan exhaustive coverage of the different problems that are associated with the heterogeneity of theapplication; the problems with homogeneous buffer capacities and setup times are rather simple tosolve, but they get a lot more complex as heterogeneity increases. We study the three main subproblemsfor each heterogeneity combination, and offer heuristic solution to solve them when anoptimal solution cannot be reasonably found.

La présence de buée sur des surfaces transparentes altère la transmission de la lumière. La buée est un ensemble de gouttes condensées sur une surface froide. Ces gouttes absorbent, réfléchissent et diffractent la lumière, réduisant la transparence de la surface sur laquelle elles se sont formées. Ce phénomène peut, en fonction des applications, causer des problèmes esthétiques et de sécurité. Une solution répandue dans le secteur industriel est l’utilisation de revêtements chimiques. Mais cette approche à un coût ; elle oblige à ajouter une nouvelle étape sur la chaine de production. Une autre solution, celle choisie durant ce doctorat, est l’approche topographique. En contrôlant la topographie par texturation de surface, les propriétés de mouillage peuvent être pilotées. Ainsi, des surfaces antibuées peuvent être développées. En fonction de la surface initiale, deux mécanismes sont possibles. Sur des surfaces hydrophiles, la création d’un film liquide uniforme remplaçant les gouttes d’eau est à privilégier. Avec ce type de film, la surface conserve de bonnes propriétés de transparence. Si la surface est plutôt hydrophobe, l’idée est de favoriser le déperlement des gouttes et ainsi d’évacuer l’eau le plus rapidement possible. Les travaux de ce doctorat portent sur le développement d’un traitement de surface topographique par injection plastique. Ce traitement vise à supprimer l’impact optique de la buée sur les surfaces en polycarbonate transparent des phares automobiles. L’une des contraintes majeures de ces travaux est de concevoir des texturations de surfaces facilement industrialisables. Les moyens de texturations doivent être adaptés. / The presence of dew on transparent pieces impairs light transmission. Dew is a group of droplets condensed on cold surfaces. These droplets absorb, reflect and diffract light, reducing condensation surface transparency. This can cause aesthetic or security issues. The most widely used method currently for improving transparency of surfaces covered with dew is to apply anti-fog chemical coatings. These coatings suppress the whitish opaque layer caused by condensation by reducing the surface tension of water droplets, causing them to disperse into a thin liquid sheet. However, this solution is expensive. It is adding a step in the production line. Surface texturing offers a viable alternative to the use of chemicals. Controlling the surface topography by modifying textured allows wetting property management. This approach, chosen during this PhD thesis, allows the design of anti-fog surfaces. Depending on the surface, two droplets suppression mechanisms are possible. On hydrophilic surfaces, liquid sheet formation replacing droplets has to be favored. If the surface is hydrophobic, droplets sliding off should be increased, thus water evacuation will be faster. Our work consists in the development of a topographical surface treatment by molding injection. The aim is to limit the optical impact of the dew on transparent polycarbonate surfaces of car headlights. The major constraint of this work is to design easy industrialized textured surfaces. Production means must be adapted.