The research initiatives addressed in this thesis are geared towards improving the performance of passive optical networks (PONs) through the development of advanced dynamic bandwidth allocation (DBA) protocols. In particular, the aim of the research undertaken is to enhance the quality of service (QoS) offered by standard PONs by means of providing subscribers with service level agreement (SLA) to fulfil applications and associated bandwidth requirements on demand. To accomplish the research objectives, a novel service and bandwidth focused DBA protocol is developed for standard time division multiplexing (TDM), gigabit-capable PONs (GPONs) by flexibly assigning a guaranteed minimum bandwidth to each optical network unit (ONU),terminated at subscribers premises. Modelling and simulation of the developed algorithms have displayed a tenfold enhancement in network performance, showing a superior performance to other published DBA protocols, in terms of mean packet delay. To accomplish protocol optimisation, the ONU upstream transmission properties of TDM-PONs have been further analysed and subsequently the ONU data transfer order in each communication cycle has been dynamically configured to increase the network upstream throughput by overlapping the upstream transmission period with parts of the bandwidth request-allocation process between OLT and ONUs. In addition, with the objective of extending the application of the developed protocol to long-reach PONs by means of reducing the augmented propagation delays due to the network’s extensive reach, the concept of virtual communication cycles has been incorporated into the optimised DBA algorithm. This approach demonstrates comparable transmission efficiency in the context of subscriber throughput and packet delay as in a standard PON but at much longer distances from the network exchange. To overcome the inevitably limited communication capacity of single wavelength TDM protocols and with the transportation of the ever increasing, time-sensitive, multi-media services in mind, a novel multi-wavelength DBA protocol is then developed to be applied to a wavelength division multiplexing–PON. With this protocol, both the downstream and upstream network capacity is dynamically adjusted according to subscribers’ service level and bandwidth demand in each polling cycle as opposed to a fixed upstream network capacity in TDM-PONs. It therefore also demonstrates improved upstream transmission efficiency.

Made available in DSpace on 2016-03-15T19:37:41Z (GMT). No. of bitstreams: 1 Jair Fiuza - EE2006.pdf: 870543 bytes, checksum: 939198dd0585c5cbae3d86adf6c858cc (MD5) Previous issue date: 2006-08-29 / The performance of a distributed Raman amplifier at S - Band using the TrueWave® Reach Low Water Peak fiber in a 100km span is analyzed through numerical simulations. The manufacturer, the OFS Fitel Denmark Ap, has experimentally characterized the physical parameters of the fiber, such as, attenuation, dispersion and Raman gain efficiency at Band - S. The low fiber attenuation around pump wavelength region, around 0,34dB/km at 1370nm, allow the achievement of approximately 10dB over 70nm in the S - Band − using 4 (four) pump lasers with pump power on the order of tenth of mWatts . / O desempenho de um amplificador Raman distribuído na Banda - S utilizando a fibra óptica TrueWave® Reach Low Water Peak em um enlace de 100km é analisado através de simulações numéricas. O fabricante, a OFS Fitel Denmark Ap, caracterizou experimentalmente os parâmetros físicos da fibra óptica, tais como atenuação, dispersão, e eficiência de ganho Raman na Banda - S. A baixa absorção dessa fibra óptica na região espectral onde se localizam os lasers de bombeamento, em torno de 0,34dB/km, para 1370nm, permite a utilização de 4 lasers de bombeamento com potências da ordem de dezenas de mWatts, para garantir um ganho on-off da ordem de 10dB em 70nm (1460 a 1530nm) na Banda - S.

Le règlement REACH vise à améliorer la sécurité des produits chimiques quicirculent au sein de l’Union européenne par une généralisation et un approfondissement del’évaluation et de la gestion du risque chimique. Cet objectif d’amélioration de la sécurité desproduits chimiques est censé être atteint grâce à l’instauration de quatre procéduresprincipales (enregistrement, évaluation, autorisation et restriction) et par celle d’uneobligation générale d’information relative à ces produits chimiques. Ces quatre procédures ontvocation à s’appliquer aux activités de toutes les entreprises, membres de la chaîned’approvisionnement, qui fabriquent, importent ou utilisent des produits chimiques sur le soleuropéen. De plus, ces entreprises sont soumises à une obligation générale d’information,principalement à travers la Fiche de données de sécurité, qui contient des informationsrelatives aux risques environnementaux et sanitaires des produits chimiques.Or, ces quatre procédures principales et cette obligation générale d’information représententun risque juridique pour ces entreprises compte tenu, principalement, des insuffisancesconstatées au sein des dispositions du règlement REACH. Ce risque juridique est susceptiblede porter atteinte à leur compétitivité, voire à leur survie.Toutefois, les effets dommageables de ce risque juridique peuvent être gérés par une méthodede traitement inspirée de la normalisation. Par une étape ultime de cette méthode de gestiondu risque juridique, les entreprises peuvent même espérer tirer un avantage concurrentiel de lamise en application du règlement REACH. / REACH regulation aims at increasing the safety of chemical products thatcirculate in European Union by generalizing and detailing the assessment and management ofchemical risks. This generalization relies on four leading procedures (registration, evaluation,authorization and restriction) and on a disclosure obligation. The four leading procedures areopposable to any firm in a supply chain, so that this firm can manufacture, import or usechemical products in the European Union. Firm are also subject to the total disclosureobligation, mainly enforced through the Safety Data Sheet that publishes information relativeto the health and environmental risks of involved chemicals products. Both theimplementation of the procedures and the total disclosure obligation may represent a legal riskdue to several inadequacies in the REACH regulation. For a firm, this legal risk may hamperits competitiveness and consequently its survival. However, the damaging effect of this legalrisk may be circumvented using a methodology of legal risk treatments inspired bynormalization. In the last step of such a methodology, firms may eventually find economicaladvantages when implementing the REACH regulation.

Die Hautsensibilisierung (Typ 4 Hautallergie) nimmt in der Toxizitätsbewertung einen wichtigen Stellenwert ein, was u.a. daran zu sehen ist, dass sie unter dem europäischen Chemikaliengesetz REACH schon sehr früh, d.h. ab einer Jahrestonne, abgeprüft werden soll. Die Dissertation untersucht, ob die derzeit im Tierversuch stattfindende Toxizitätsprüfung durch computerchemische Methoden ersetzt werden kann. Dazu wurde eine Datenbank aus über 2000 Stoffen erstellt, aus der wichtige Unterschiede zwischen den eingesetzten Tiermodellen herausgelesen werden konnten. In den Untersuchungen trat auch zu Tage, dass – entgegen vorheriger Annahmen – die Bioverfügbarkeit, d.h. die Aufnahme von Substanzen über die Haut, im Tierversuch nur eine untergeordnete Rolle spielt. Zudem ist eine Abschätzung des hautsensibilisierenden Effekts von Stoffen anhand eines Read-across (Interpolation aus strukturähnlichen Verbindungen) und von Strukturalarmen (Substruktur­elemente als Indikatoren für einen bestimmten Effekt) möglich. Wenn beide Ansätze im Rahmen einer Konsens­modellierung miteinander verschränkt werden, ergibt sich sogar eine gute Vorhersagestatistik. / Skin sensitisation (type 4 skin allergy) is an important parameter in the toxicity assessment of chemicals, which is underlined by the fact that it is evaluated even at the lowest tonnage (1 t/a), which can be registered under the european chemicals regulation (REACH). In this thesis it was investigated if the currently used animal models can be replace or refined with computational (in silico toxicological) methods. In this regard a data base consisting of about 2000 substances was build. With its data important differences between the currently applied animal tests could be derived. Furthermore, the investigation found that – in contrast to previous assumptions – the bioavailability of a chemical compound, i.e. the uptake via the skin, has only a minor impact on the test result of the evaluated animal models. Moreover, it was demonstated that the skin sensitising potential of chemicals can be predicted by read-across (interpolation with structurally similar substances) and with structural alerts (substructural elements which indicate a particular effect). Combining both prediction methods with consensus modelling lead to a good prediction regarding the question whether a particular chemical compound is a sensitiser or not.

With the development of advanced driving assistance systems, the amount of data that needs to be transmitted within a car has increased tremendously. Traditional communication bus based systems are unable to meet today’s requirements; hence automotive Ethernet is being developed and standardized. Ethernet has for many years been the de facto standard in interconnecting computers. In that time several vulnerabilities of the networking protocol stack implementations and even the protocols themselves have been discovered. The knowledge from exploiting computer networks can be applied to the automotive domain. Additionally, vehicle manufacturers tend to implement their own stacks, due to copyleft reasons; hence the chances of implementation faults increases as opposed to using well-tested open source solutions. Since the line between security and safety in cars is almost nonexistent, security has to be properly addressed. This thesis investigates the security of automotive Ethernet and its accompanying protocols. It starts with an introduction to computer and automotive networking and protocols. After a solid foundation is laid, it investigates what makes up automotive Ethernet, its application in the field, and the automotive specific components relying on it. After looking at related work, a data network security audit and analysis as defined by the open-source security testing methodology is performed. The system is graded with risk assessment values. Weak points are identified and improvements suggested. The impact of the proposed improvements is shown by reevaluating the system and recalculating the risk assessment values. These efforts further the ultimate goal of achieving increased safety of all traffic participants. / Med utvecklingen av avancerade körningsassisterande system har mängden data som behöver sändas inom en bil ökat enormt. Traditionella kommunikationsbussbaserade system kan inte uppfylla dagens krav. Därmed utvecklas och standardiseras Ethernet för fordon. Ethernet har i många år varit de facto-standarden i sammankopplandet mellan datorer. Under den tiden har flera sårbarheter hos nätverksprotokolls implementeringar och protokoll själva upptäckts. Det finns anledning att tro att kunskapen från att utnyttja datanätverk kan tillämpas på fordonsdomänen. Att tillägga är att fordonstillverkare tenderar att genomföra sina egna staplar. På grund av copyleft skäl, ökar chanserna för implementeringsfel i motsats till att använda testade open source-lösningar. Eftersom människors säkerhet hos bilar är extremt viktigt, måste även dess system hanteras ordentligt. Denna avhandling undersöker säkerheten för Ethernet och kompletterande protokoll hos bilar. Den börjar med en introduktion till datorers och bilars nätverk och protokoll. Efter en stabil grund fastställts, undersöker den vad som utgör Ethernet hos bilar, dess tillämpning inom fältet, och de bilspecifika komponenterna den beror av. Efter att ha tittat på relaterat arbete utförs en säkerhetsgranskning och analys av datanätverk som definieras av säkerhetsmetoden för open-source. Systemet värderas med riskbedömningsvärden. Svaga punkter identifieras och förbättringar föreslås. Effekten av de föreslagna förbättringarna framgår utav omvärdering av systemet och omräkning av riskbedömningsvärdena. Dessa bedömningar leder till det yttersta målet för ökad säkerhet för alla trafikanter.

Purpose – The purpose of this master thesis is to explore how an e-tailer selling bulky items can use a multiple criteria ABC analysis to make its purchasing process more effective, while balancing richness and reach, with the performance measurements of profitability, total asset turnover and inventory turnover. The purpose will be accomplished through a single case study on an e-tailer active on the Swedish furniture and home furnishing market. Methodology – This thesis applies a multiple criteria ABC-analysis to a single case study. The approach is semi-deductive as theory is combined with interviews on how to match and adapt theory about inventory control and purchasing with the specific requirements of an e-tailer selling bulky items. Findings – This thesis has resulted in a set of recommendations that aim to make the purchasing process of an e-tailer more effective. That is, capital and inventory space will be better allocated to the e-tailer’s more profitable items. Among other things, this thesis shows how dead articles can be identified and how a purchaser can prioritize more profitable articles over less profitable ones when making procurement decisions. The other recommendations are for the e-tailer to investigate the possibilities of decoupling the supply chain by keeping stock at the suppliers’ premises, to match the supplier reliability with their importance in the supply chain, and lastly to explore possibilities of drop shipment. Further, the main finding is that a comparison between the A-, B-, and C-classes and the reliability of the suppliers, highlights a gap and a possible risk. Put differently, the importance of a specific item for the business should be reflected in the choice of supplier and the multiple criteria ABC analysis is the tool to illustrate the importance. Keywords – E-commerce, E-tailer, richness, reach, transaction cost, ABC analysis, multiple criteria ABC, MCABC, inventory turnover ratio, supplier selection, purchasing Paper type – Masters thesis / Syfte – Syftet med detta examensarbete är att undersöka hur en e-handelsdetaljist som säljer skrymmande artiklar kan använda en flerdimensionell ABC-analys för att göra sin inköpsprocess mer effektiv och balansera richness och reach, med mätetal som lönsamhet, kapitalomsättningshastighet och lageromsättningshastighet. Syftet kommer att uppfyllas genom en fallstudie på en e-handelsdetaljist verksam på den svenska möbel- och heminredningsmarknaden. Metod – Denna fallstudie använder sig av en flerdimensionell ABC-analys. Tillvägagångssättet är semi-deduktivt då intervjuer och teori om hur lagerstyrning och inköp kan matchas och anpassas till ett företags specifika behov. Resultat – Den här uppsatsen har resulterat i en rad åtgärder som syftar till att göra en ehandlares inköpsprocess mer effektiv. På så vis att kapital och lageryta bättre allokeras till ehandlarens lönsamma artiklar. Bland annat visar den här uppsatsen hur döda artiklar kan identifieras och hur inköparen kan prioritera mer lönsamma artiklar över olönsamma vid inköp. De andra åtgärdena handlar om att undersöka möjligheter att frikoppla försörjningskedjan genom att lagra produkter hos leverantören, att matcha leverantörernas pålitlighet och deras betydelse i försörjningskedjan, och slutligen att utforska möjligheter att utöka drop shipment. Det främsta bidraget är att eventuella felprioriteringar och risker blir tydliga genom en jämförelse mellan A-, B- och C-klasserna och leverantörernas pålitlighet. Med andra ord bör den affärsmässiga inverkan som respektive artikel har på e-handlarens resultat avspegla sig i valet av leverantör. En flerdimensionell ABC-analys kan användas för att påvisa respektive artikels affärsmässiga inverkan. Publikationstyp – Examensarbete för utbildning till civilingenjör (masteruppsats).

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近年來因網際網路盛行，各行各業皆面臨了全球國際化的競爭，於是虛擬平台的經營便成為大家努力的方向，如何提高虛擬平台的網路流量已成為平台經營者所重視的議題。 拜網際網路應用的成熟，不動產業雖然很傳統，但也不得不開始運用網際網路提供服務，並且這些服務越來越多元化，提供物件資訊、透過討論區討論物件內容、讓經紀人以社群方式存在，在平台上提共買賣不動產的相關知識，消費者可透過平台買賣物件，尋找物件。故研究如何增加虛擬平台的流量，將是未來平台經營者在提升平台品質上有效的方法。本研究將提出影響網站流量策略的研究架構，根據Alexa網站提供覆蓋數（Reach）與頁面瀏覽數（Pageview），以五個不動產個案公司的網站流量進行分析。 本研究流量分析的架構如下：首先就文獻資料了解影響網站流量的因素，對照個案公司在這些影響網站流量的因素上的表現，進而了解何種因素是確實影響網站流量。 經分析結果顯示，目前為了使網站流量表現良好，各家個案公司，都會使用搜尋引擎、關鍵字、SEO操作等工具，所以在工具上各家個案公司表現差異不大，惟廣告行銷的投入，對整體網站流量實際上才是重要的影響，另外，許多專家或者是文獻，認為免費的商業模式是網際網路平台經營時重要的方式，但研究發現卻是平台業者收取一點費用是客戶可以接受的，平台的內容與服務，實際會提升虛擬平台的網站流量；經分析顯示，外部網站結盟有助於提升虛擬平台網站流量，希望藉由本研究的分析結果提供給不動產虛擬平台經營者在網站流量策略上的參考建議。 / In the internet era, the most significant issue for platform operators is how to design and manage the virtual platform to increase the web traffic flow. The diversity of online services that offer information and discussion through Internet forum allows real estate agents to provide product knowledge through different kinds of virtual community. Consumers can search, purchase and sell real estate items through these virtual platforms. Consequently, virtual service providers endeavor to enhance platform operation and service quality to attract visitors. This research proposes a research framework to investigate determinants of web traffic. Based on literature review and related researches this study analyzed the causes and effects of web traffic. A few traffic-affecting factors were identified. These factors include: content management, marketing strategies, promotion strategies, and business models. Next, five different types of web sites in the real estates industry in Taiwan were selected for multiple case studies. The cross case analysis revealed that all companies have applied search engine, keywords, and SEO (xxx) to enhance users’ access to the web sites. The impact of technology use and system functionality on users’ intention to participate is of no great concern. However, the advertising effort seems to be the key determinant for boosting website traffic. Further, although several researches consider free-of-charge as a winning business model the analysis results reveal that well-managed contents can bring in customers who are willing to pay for the services. The results also demonstrate that external alliance of websites can assist the growth of the traffic flow on a virtual platform. Since Internet is widely used these decades, various industries have been occurred the global competitions. The most significant issues for platform operators are how to conduct virtual platform well and how to increase web flow rate of virtual platform. The mature usage of Internet initiates the real estate industry to offer services through Internet. The diversity of online services that offer information and discussion through Internet forum allow real estate agents to provide real estate related knowledge through community websites. Consumers can also search, purchase and sell real estate items through the virtual platform. Consequently, the research of how to increase virtual platform flow will enhance platform operators efficiently advance service quality of platforms. This research proposes a research framework to investigate what determinants effect web traffic strategy and analyze web traffic of five real estate companies by collecting Reach and Pageview from Alexa website. The Framework of this research is as follows. First, we analyze the causes and effects of web traffic based on literature. Next, we compare the effects of web traffic among selected cases to recognize which determinants influence web traffic. The analytical results reveal that all companies use search engine, keywords, and SEO to enhance the performance of web traffic. The difference of all tools among cases is insignificant. However, the advertising effort is the key determinant for whole website traffic. In addition, many researchers and literature consider free is the major business model for platform operators. Nevertheless, this research discovers the consumers accept for charging few fees and the content and service of the platform increase the traffic. The results also demonstrate that external alliance of websites assists the increment of traffic for virtual platform. Finally, this study aims to provide strategic suggestions to companies in virtual estimate industry.

The demand for energy from developed and developing economies of the world is driving the search for energy resources to more challenging environments. The exploration and exploitation of hydrocarbons now requires the drillbit to hit pay zones from drillships or platforms that are located on water surfaces below which is, possibly, in excess of ten thousand feet of water above the sea bed. From Brazil, to the Gulf of Mexico and the Gulf of Guinea on the western coast of Africa, hitherto unfamiliar, but now common, concepts in the drilling parlance such as ultra-deep drilling (UDD), ultraextended- reach drilling (uERD) and slimhole drilling, are employed to reach and produce reservoirs which a few decades ago would seem technologically impossible to produce. This is expected to exert tremendous demands on the physical and mechanical properties of the drillstring components. Limiting factors for reaching and producing oil and gas resources hidden very deep in the subsurface are both the capacity of the drilling rig to support the weight of the drillstring, which in some instances can be several kilometres long, and the bending, tensile and impact stresses the string has to withstand in well trajectories that are getting both longer and more tortuous. Associated with this increased well depths and complex well trajectories is the prohibitive cost penalty of a failed drillstring. The in-service failure of drillstrings has always been an issue in the industry long before the wells become this deep and complex. The global oil and gas industry estimates the cost of string failure to be in excess of quarter of a billion dollars annually. Researchers are continuously looking for ways to design against string failure and improve the level of confidence in drillstrings. Defect-tolerant design, tooljoint geometry modification and surface coldworking are just a few of the ideas that have gained mileage in this effort. Others that are now in consideration are the use of nonconventional materials such as aluminium and titanium alloys for drillstring components. More novel, still, is the use of a combination of two materials - one ‘softer’ than the other to form a hybrid string of two materials of unequal moduli of elasticity. This is done to make the string lighter, reduce stress concentration factor at the connections and place fatigue resistant materials in areas of high well bore curvature.In this work a computational technique in the form of two-dimensional finite element analysis is used to develop a robust model of a drillstring connection and to analyse the stresses on the model of a threaded connection of standard drillstring tooljoint made from alloy steel. Further comparative analyses were undertaken on models of drillstrings made from a newly developed drillstring material for ultra-deep drilling, the UD-165, aluminium and titanium alloys and, finally, on hybrid drillstrings made from two different materials of unequal moduli of elasticity. The aim is not only to develop and validate a better method of computational drillstring analysis but also to use the model to investigate and suggest areas of optimisation that will benefit industry especially in the areas hybrid strings.

[pt] Recentemente, grande interesse tem se voltado na robótica para o conceito de manipuladores flexíveis. Estes dispositivos apresentam uma coluna vertebral deformável continuamente, em oposição aos tradicionais manipuladores robóticos elo/junta/elo com elos rígidos. Sistemas flexíveis oferecem um aumento em potencial da capacidade de interação com o ambiente, estando aptos a se ajustarem às limitações do meio através de sua deformação. Robôs flexíveis oferecem possibilidades atrativas para o uso em diversas aplicações, como em posicionamento em ambientes complexos com obstáculos, endoscópios ativos, e manuseamento de materiais frágeis. O uso de polímeros, em particular elastômeros, tem sido explorado nestes manipuladores para promover simplicidade de operação e menor rigidez, necessária para uma interação homemmáquina com maior segurança. Usufruindo-se destes conceitos, esta dissertação aborda o desenvolvimento de um manipulador pneumático flexível de longo alcance. O manipulador é composto por uma estrutura modular, formada por vários elos ligados serialmente, permitindo que em sua extremidade sejam acopladas ferramentas que auxiliem a execução de diferentes tarefas. O sistema é baseado em um atuador pneumático denominado Músculo Artificial Pneumático (Pneumatic Artificial Muscles, PAM). Ao serem pressurizados, estes dispositivos se contraem, exercendo uma força em sua extremidade proporcional à pressão aplicada. A movimentação do manipulador desenvolvido é obtida a partir da diferença de pressão entre câmaras independentes localizadas em seu interior. Modelos analíticos dos sistemas desenvolvidos foram elaborados. O controle do manipulador é feito a partir de servoválvulas pneumáticas controladas por computador. Experimentos foram realizados para verificar os modelos desenvolvidos. O sistema desenvolvido pode ser aplicado à tarefa de inspeção interna de reservatórios de combustíveis. Inspeções internas atualmente requerem um completo esvaziamento do reservatório, se tornando muito trabalhosas e resultando em altos custos. Uma versão do manipulador é adaptada para executar esta tarefa sem a necessidade de esvaziar os tanques, devido à segurança intrínseca do sistema pneumático. / [en] Recently, the concept of flexible manipulators has attract great interest. These devices present a continuously deforming vertebral column, in opposition to the traditional robotic manipulators link/joint/link with rigid links. Flexible systems offer a potential increase in the capacity of interaction with the environment, being apt to adjust itself to the constrants through its deformation. Flexible robots offer attractive possibilities for usage in many applications, as complex environments positioning with active obstacles, endoscopies, and manipulating fragile materials. Polymers, specially elastomers, have been explored in these manipulators to guarantee simple operation and minor rigidity, necessary for a higher security man-machine interaction. Making a good use of these conceptions, this dissertation presents the development of a long-reach flexible pneumatic manipulator. The manipulator is composed of a modular structure, formed by links attached serially, allowing tools to be connected in its end-point for assistence in different tasks. The system is based on a pneumatic actuator called Pneumatic Artificial Muscle (PAM). When pressurized, these devices contract themselves, exerting a proportional force in its end-points proportional to the applied pressure. The manipulator´s motion is obtained from the pressure difference between the independent chambers located in its interior. Developed systems analytical models have been elaborated. Pneumatic valves, commanded by computer, control the manipulator. Experiments have been carried through to test the developed models. The developed system can be applied to internal inspection of fuel tanks. Internal inspections currently require a complete tank ullage, becoming very laborious and resulting in high costs. A manipulator´s version is adapted to execute this task in a full fueled tank, due to intrinsic security of the pneumatic system.