Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 396-419). Also available on the Internet.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 105-114.

Includes bibliographical references (p. 46-48).

Thesis (M.B.A.)--University of Hong Kong, 1984.

Integer multicommodity network flow (MCNF) models have applications in various areas like logistics, freight transportation, telecommunication and manufacturing. In this thesis we study an extension of the integer MCNF problem (MCNF-FIFO) where commodities are handled (processed) in a first-in-first-out (FIFO) order at each transshipment location and resource capacities are shared across arcs in the network. The objective of the MCNF-FIFO model is to find feasible routes for all commodities from their origins to destinations while minimizing the total transportation and holding cost or the sum of delivery times. We formulate the MCNF-FIFO problem on a time-space network and develop three different integer-programming (IP) formulations for the FIFO constraints, and two IP formulations for the flow conservations requirements. Since these formulations have a very large number of variables and constraints, we develop various algorithmic strategies to obtain good quality solutions quickly. The first strategy is to reduce the problem size by using properties of the optimal solution. We develop novel problem reduction and decomposition techniques that eliminate variables and constraints, and decompose the problem into smaller components. To further reduce the problem size, we classify the FIFO constraints into different categories by utilizing the relationships between different commodities, and provide specialized formulations for each of these categories so as to reduce the number of FIFO constraints significantly. The second strategy is to develop heuristic algorithms that provide near-optimal solutions to the MCNF-FIFO problem. Our first algorithm is an optimization-based heuristic that solves a relaxed MCNF-FIFO model with a limited number of FIFO constraints. Then, it removes the remaining infeasibilities in the solution of the relaxed MCNF-FIFO model using a repair heuristic to obtain a feasible solution. We develop two other heuristic algorithms that are stand-alone construction heuristics that build a feasible solution from scratch. To assess the effectiveness of the modeling and algorithmic enhancements, we implement the methods and apply them to three real life test instances. Our tests show that the problem reduction techniques are very effective in reducing the solution times. Among the heuristic algorithms, the optimization-based heuristic performs the best to find near-optimal solutions quickly. / text

A Command and Data Handling (C&DH) system is being developed as part of a series of CubeSat missions being built at The University of Texas at Austin’s Texas Spacecraft Laboratory (TSL). With concurrent development of four missions, and with more missions planned for the future, the C&DH team is developing a system architecture that can support many mission requirements. The presented research aims to establish itself as a reference for the development of the C&DH system architecture so that it can be reused for future university missions. The C&DH system is designed using a centralized architecture with one main flight computer controlling the actions and the state of the satellite. A Commercial Off-The-Shelf (COTS) system-on-module embedded computer running a Linux environment hosted on a custom interface board is used as the platform for the mission software. This design choice and the implementation details of the flight software are described in detail in this report. The design of the flight software and the associated hardware are integral components of the spacecraft for the current missions in the TSL which, when flown, will be some of the most operationally complex CubeSat missions attempted to date. / text

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

Not available / text

Vehicle behaviour near the limit of adhesion is studied using linear optimal . control techniques and relatively simple vehicle models. Both time-invariant and time-varying approaches are used. Controllability is applied as a post-processing tool to analyse the resultant vehicle behaviour. First, a 4WS controller is developed using a linear time-invariant method, with a reference model control structure. Two handling objectives are defined, which are thought to provide predictable dynamics. Advantages of using a reference model control are clearly shown. With a developed control structure, it is shown that the prescribed target dynamics is achieved, provided tyre forces are available. It is also found that the controller is robust to small changes in the various vehicle parameter values. As a next step, time-varying modelling approach was used in order to better represent the vehicle operating conditions through the various dynamic range, including the limit of adhesion. An iterative vehicle path optimisation problem is formulated using a linear time-varying control approach. The validity of the optimisation method is studied against the steady-state simulation result at the limit of adhesion. It is shown that the method is capable of finding a trajectory in the vicinity of the friction limit, where the front tyres are used fully whilst retaining some margin at the rears. However, a couple of Issues are discovered. First, due to the quadratic nature of the road geometry cost function, the trajectory could get locked if the vehicle runs very close to the edge of the road. Hence, the . optimisation needs to be formulated such that the level of "optimality" on the trajectory remains consistent throughout the manoeuvre at each iteration. Secondly, it is found that inappropriate control demands are produced if the system matrix becomes poorly conditioned near the limit. This results in optimisation failure. In order to understand the mechanism of this failure, controllability of linear timevarying system was analysed and its properties were discussed in detail. First, the calculation methods of the controllability gramian matrix are investigated and some practical limitations are found. The gramian matrix is then used to define an open loop control sequence. It is found that the damping of the system has a significant influence on the control strategy. Subsequently, "the moving controllability window of a fixed time period" is found to provide the most relevant information of changing dynamics through the time. The study showed that the failure of the optimisation in the vicinity of the friction limit was indeed due to lack of controllability and the optimisation method itself was functioning correctly. The vehicle path optimisation problem is then extended to include longitudinal dynamics, enabling simulation of more general manoeuvres. The single corner simulation showed that the optimisation converges to an "out-in-out" path, with iterative solution improving continuously in a first order manner. Simulations with various controller settings showed that the strategy is reasonably robust provided that the changes in parameter settings are kept within a reasonable magnitude. It is also confirmed that the optimisation is able to drive a vehicle close to the limit under different types of operations required, i.e. braking, cornering and acceleration. The study was then performed with slightly more complex road geometry in order to investigate if the· optimisation is capable of prioritising certain· part of the manoeuvre in order to achieve better overall result. Unfortunately, this problem could not be solved successfully. The optimisation concentrated on the latter part of the manoeuvre as it had higher sensitivity to the final cost. This resulted in clearly sub-optimal overall performance. Finally, relatively simple study is conducted to investigate the correlation between various vehicle settings and optimisation results. Using the path optimisation problem formulation, iris found that the more oversteer vehicles are able to achieve better· result with more margin left in rear tyre force capacity. The handling objective functions used for the 4 WS controller is also calculated for the resultant trajectories. It is found that the neutral steer cost had a strong correlation, whereas the linearity cost showed no noticeable correlation. The controllability analysis was applied on the various vehicle settings using step steer simulation. It showed that more understeering vehicle retains higher controllability throughout the dynamics range. It is also found that higher inertia gives better controllability near the limit, however, it gives less controllability at more moderate operating conditions.

Då taxeringsrevision är en relativt ingripande åtgärd för den enskilde företagaren, bör denna ha möjligheten att skydda känsliga handlingar. Skatteverket har vid taxeringsrevision rätt att ta del av samtliga handlingar som rör verksamheten. Det finns dock möjligheter att undanta handlingar från revisionen, men det är då främst för de grupper som berörs av 36 kap. 5 § RB, exempelvis advokater, läkare och tandläkare. Vad det gäller revisorer så omfattas inte de av 36 kap. 5 § RB och har därmed inte den möjligheten till undantag, utan de kan enbart åberopa 3 kap. 13 § 1st 2 TL om de vill få handling undantagen vid revision. Syftet med uppsatsen är att se om det borde finnas fler yrkesgrupper som ska kunna åberopa 27 kap. 2 § RB och 36 kap. 5 § RB vid undantag av handling. Och då på grund av sekretess förbindelser genom andra lagar eller regler, till exempel tystnadsplikten för revisorer i 9 kap. 41 § ABL. Vi har valt att jämföra revisorer med advokater då båda dessa yrkesgrupper omfattas av lagreglerad tystnadsplikt, med tanke på detta så anser vi att även revisorer bör omfattas av möjligheten till undantag i likhet med det som finns i 27 kap. 2 § RB. När vi studerat de rättsfall vi tagit upp i uppsatsen så framkom det att advokater inte med självklarhet kan få en handling undantagen, utan de måste åberopa speciella skäl för den specifika handlingen. Enligt en dom i Högsta domstolen, NJA 1990 s 537, så bör bevisbördan för dessa ligga på en låg nivå för att få handlingen undantagen till skillnad från revisorer som det ställs högre krav på. Vad man kan se så finns det inte någon klar bild på hur domstolarna dömer i denna typ av mål, då de olika instanserna flera gånger kommer till olika domslut i samma mål. Detta gäller både mellan länsrätt – kammarrätt, som kammarrätt – Regeringsrätt, vilket inte är bra för förutsebarheten och rättsäkerheten för den skattskyldige. Vi kom fram till den slutsatsen, för att skydda revisorernas klienter bör det till en lagändring, i och med denna kommer sekretess gälla för hela skatteprocessen. Det blir då bara parterna i målet som har rätt att ta del av materialet, och det finns då ingen risk att utomstående kan få del av känsligt material efter domen. Med denna lagändring skulle inte bara skyddet stärkas för revisorns klienter utan även för advokatens.