In the three main sections of this thesis (chapters II, III, and IV; chapter I consists of definitions) we explore three methods of studying Alexander polynomials of links which are alternatives to Fox' free differential calculus. In chapter II we work directly with a presentation of the link group and show how to obtain a presentation for the Alexander invariant. From this we deduce that the order ideal of the Alexander invariant is principal for links of two or three components (the case of one component is well known) but nonprincipal in general for links of four or more components. In any event we show that only one determinant is needed to obtain the Alexander polynomial. In chapter III we use surgery techniques to characterize Alexander invariants of links of two components in terms of their presentation matrices. We then use this to show that the Torres conditions characterize link polynomials when the linking number of the two components is zero or both components are unknotted and the linking number is two. Chapter IV uses Seifert surfaces to prove a generalization of a theorem of Kidwell which relates the individual degrees of the Alexander polynomial to the linking complexity, to present an algorithm for calculating the Alexander polynomial of a two-bridge link from a two-bridge diagram and to prove a conjecture of Kidwell in the special case of two-bridge links. These results are then used to generate link polynomials from allowable pairs (a concept introduced in chapter III) and these results in turn are used to produce methods of generating allowable pairs. / Science, Faculty of / Mathematics, Department of / Graduate

PVC are extensively applied in many fields, such as cables, pipes, vehicles, shoes, toys and infusion bags. Generally, plasticizers are blended with PVC to improve the ability of process in industrial production; however, the toxic plasticizers will gradually migrate to the surface of products and such a leakage results in brittleness of plasticized PVC and environmental pollution. In other words, humans are frequently exposed to the potential risks. According to previous researches, cross-linked PVC was proved that it was able to hinder the migration of plasticizer. Thus, in this research, we selected some commercially used cross-linking agents and employed six different tests based on mechanical, tribological and microscopy analysis in order to seek the best solution against plasticizer migration. Thus, we expected to develop a cross-linked flexible PVC which performed improved long-term performance and extended lifetime.

The goal of this paper is to find the Homfly polynomial for each knot in a specific family of knots. This family of knots is generated from placing the Whitehead link into a solid torus, slicing the torus at a spot where the Whitehead has no crossings and then twisting the torus 360 degrees in either direction an integral number of times. Let L(n) denote the knot obtained by twisting the torus 360 degrees, n times. Note that n is an integer. Let the twists be towards the center of the torus for positive n and away from the center for negative n. Through the obtained Homfly polynomials, it will be determined that each of the knots in this family are distinct and non-trivial (excepting the Whitehead link).

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Seismic-resistant steel eccentrically braced frames (EBFs) are designed so that that yielding during earthquake loading is restricted primarily to the ductile links. To achieve this behavior, all members other than the link are designed to be stronger than the link, i.e. to develop the capacity of the link. However, satisfying these capacity design requirements for the beam segment outside of the link can be difficult in the overall design process of an EBF. In some cases, it may be necessary to make significant changes to the configuration of the EBF in order to satisfy beam design requirements. If this discovery is made late in the design process, such changes can be costly. The overall goal of this research was to develop guidelines for preliminary design of EBFs that will result in configurations where the beam is likely to satisfy capacity design requirements. Simplified approximate equations were developed to predict the axial force and moment in the beam segment outside of the link when link ultimate strength is developed. These equations, although approximate, provided significant insight into variables that affect capacity design of the beam. These equations were then used to conduct an extensive series of parametric studies on a wide variety of EBF configurations. The results of these studies show that the most important variables affecting beam design are 1) the nondimensional link length, 2) the ratio of web area to total area for the wide flange section used for the beam and link, 3) the angle between the brace and the beam, and 4) the flexural stiffness of the brace relative to the beam. Recommendations are provided for selection of values for these variables in preliminary design. / text

This thesis is concerned with development of a navigation algorithm primarily for the aircraft fighter SAAB JAS 39 Gripen, in swarms of other units. The algorithm uses information from conventional navigation systems and additional information from a radio data link as aiding information, relative range measurements. As the GPS can get jammed, this group tracking solution can provide an increased navigation performance in these conditions. For simplicity, simplified characteristics are used in the simulations where simple generated trajectories and measurements are used. This measurement information can then be fused by using filter theory applied from the sensor fusionarea with statistical approaches. By using the radio data link and the external information sources, i.e. other aircraft and different types of landmarks with often good performance, navigation is aided when the GPS is not usable, at e.g. hostile GPS conditions. A number of scenarios with operative sense of reality were simulated for verifying and studying these conditions, to give results with conclusions. / Det här examensarbetet syftar till utveckling av en algoritm för navigering, primärt för stridsflygplanet SAAB JAS 39 Gripen, i svärmar av andra enheter. Algoritmen använder information från konventionella navigeringssystem och ytterligare information från en radiodatalänk som ger understödjande information, relativa avståndsmätningar. Då den förlitade GPS:en kan störas ut, kan denna gruppspårande lösning öka navigeringsprestandan i dessa förhållanden. För enkelhetens skull, används förenklade karaktäristiker i simuleringarna där enkla genererade trajektorier och mätningar används. Denna mätinformation kan sedan ihopviktas genom att använda filterteori från statistisk sensorfusion. Genom att använda radiodatalänkar och den tillförda informationen från externa informationskällor, således andra flygplan och olika typer av landmärken som väldigt ofta har god prestanda, är navigeringen understödd när GPS inte är användbar, t.ex. i GPS-fientliga miljöer. Ett antal scenarion med operativ verklighetsanknytning simulerades för att verifiera och studera dessa förhållanden, för att ge resultat med slutsatser. / © Daniel Magnusson.

To contribute to the field of research of Projects as Social Processes, this research study will investigate the various aspects of social processes in the project environment. The study will be qualitative in nature and will use a case study methodology investigating the social processes experienced by the project managers of the various subsystems of Bombardier Transportation, as part of the Bombela Concession Company, in the delivery of the Gautrain Rapid Rail Link project. Project Managers were interviewed to understand how they experience the social processes taking place in the project environment as well as how they handle and approach these social interactions. The above methodology used in this exploratory case study is specifically used to develop a justification for enlarging the existing methodological Project Management Bodies of Knowledge (PMBOK) and the Life Cycle processes applicable to System Engineering to include Social processes.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The terrestrial microwave telemetry links show limitation due their inherent features concerning bandwidth availability, frequency allocation and range. Also it supports only one aircraft per test and the data acquisition capacity can be enhanced. Following the flight tests trends, it proposes a telemetry link based on satellite communications deployed by off the shelf equipments allowing advantages as bandwidth availability, multiple aircrafts telemetry and almost global range into the reliability standards. By simple equations and typical flight tests data it demonstrates the feasibility of the telemetry system proposed for time and costs reduction to optimize flight tests programs.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The need to allow remote access to telemetry data from closed networks has long existed. To ensure the correct engineers are available for anomaly resolution, NOAA developed the Secure Remote Access Server (SRAS) to allow transfer of satellite telemetry to an external secure server. SRAS uses one-way links to protect the ground system and secure communications for all communications with the user. After the SRAS was developed, a similar system was developed to support file transfers. This paper provides an overview of these systems and lessons learned in the development of one-way fiber systems.