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Bydraes tot die oplossing van die veralgemeende knapsakprobleemVenter, Geertien 06 February 2013 (has links)
Text in Afikaans / In this thesis contributions to the solution of the generalised knapsack problem are given and discussed.
Attention is given to problems with functions that are calculable but not necessarily in a closed form.
Algorithms and test problems can be used for problems with closed-form functions as well.
The focus is on the development of good heuristics and not on exact algorithms. Heuristics must be
investigated and good test problems must be designed. A measure of convexity for convex functions
is developed and adapted for concave functions. A test problem generator makes use of this measure
of convexity to create challenging test problems for the concave, convex and mixed knapsack problems.
Four easy-to-interpret characteristics of an S-function are used to create test problems for the S-shaped
as well as the generalised knapsack problem.
The in
uence of the size of the problem and the funding ratio on the speed and the accuracy of the
algorithms are investigated. When applicable, the in
uence of the interval length ratio and the ratio of
concave functions to the total number of functions is also investigated.
The Karush-Kuhn-Tucker conditions play an important role in the development of the algorithms. Suf-
cient conditions for optimality for the convex knapsack problem with xed interval lengths is given
and proved. For the general convex knapsack problem, the key theorem, which contains the stronger
necessary conditions, is given and proved. This proof is so powerful that it can be used to proof the
adapted key theorems for the mixed, S-shaped and the generalised knapsack problems as well.
The exact search-lambda algorithm is developed for the concave knapsack problem with functions that
are not in a closed form. This algorithm is used in the algorithms to solve the mixed and S-shaped
knapsack problems. The exact one-step algorithm is developed for the convex knapsack problem with
xed interval length. This algorithm is O(n). The general convex knapsack problem is solved by using
the pivot algorithm which is O(n2). Optimality cannot be proven but in all cases the optimal solution
was found and for all practical reasons this problem will be considered as being concluded. A good heuristic is developed for the mixed knapsack problem. Further research can be done on this
heuristic as well as on the S-shaped and generalised knapsack problems. / Mathematical Sciences / D. Phil. (Operasionele Navorsing)
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Integration and Simulation of a Bitumen Upgrading Facility and an IGCC Process with Carbon CaptureEl Gemayel, Gemayel January 2012 (has links)
Hydrocracking and hydrotreating are bitumen upgrading technologies designed to enhance fuel quality by decreasing its density, viscosity, boiling point and heteroatom content via hydrogen addition. The aim of this thesis is to model and simulate an upgrading and integrated gasification combined cycle then to evaluate the feasibility of integrating slurry hydrocracking, trickle-bed hydrotreating and residue gasification using the Aspen HYSYS® simulation software. The close-coupling of the bitumen upgrading facilities with gasification should lead to a hydrogen, steam and power self-sufficient upgrading facility with CO2 capture. Hydrocracker residue is first withdrawn from a 100,000 BPD Athabasca bitumen upgrading facility, characterized via ultimate analysis and then fed to a gasification unit where it produces hydrogen that is partially recycled to the hydrocracker and hydrotreaters and partially burned for power production in a high hydrogen combined cycle unit. The integrated design is simulated for a base case of 90% carbon capture utilizing a monoethanolamine (MEA) solvent, and compared to 65% and no carbon capture scenarios. The hydrogen production of the gasification process is evaluated in terms of hydrocracker residue and auxiliary petroleum coke feeds. The power production is determined for various carbon capture cases and for an optimal hydrocracking operation. Hence, the feasibility of the integration of the upgrading process and the IGCC resides in meeting the hydrogen demand of the upgrading facility while producing enough steam and electricity for a power and energy self-sufficient operation, regardless of the extent of carbon capture.
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Necessary and Sufficient Conditions on State Transformations That Preserve the Causal Structure of LTI Dynamical NetworksLeung, Chi Ho 01 May 2019 (has links)
Linear time-invariant (LTI) dynamic networks are described by their dynamical structure function, and generally, they have many possible state space realizations. This work characterizes the necessary and sufficient conditions on a state transformation that preserves the dynamical structure function, thereby generating the entire set of realizations of a given order for a specific dynamic network.
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Tvorba konceptu energeticky soběstačných obytných budov / Formation of the Concept of energy self-sufficient of residential buildingsHlavsa, Tomáš Unknown Date (has links)
Creating the concept of buildings is the primary task of architects, designers in the field of architecture and engineering. Although the basic requirements remain the same across time , possibilities of their solution are constantly evolving and changing. In addition, with the increasing globalization, in context of the housing and the architecture is expected new requirements go beyond the horizons of the interests of bouth investor and designer. Global view of each project and the evaluation of its traces left in our environment and society, although is much discussed but rarely taken into account or even just considered. In this context, we are witnessing the development of new trends of the concepts of buildings, consisting in the use of natural materials, in reducing the environmental burden of a surroundings, in reducing energy demands, or even in an effort to achieve energy independence thus trends, whose common denominator is sustainable construction, hence sustainable development in general. Feasibility of the creation of the concept of energy self-sufficient building doesn´t consist only in the precise solution of the assigned task from the perspective of the designer or investor, but also in finding such a solution which, even with using new trends and principles, will not go against the initial idea itself. The present instrument processed and presented in this dissertation has the ambition to move global view of the project into the perspective of a particular individual design process and in small way contribute to the creation of better projects from the perspective of sustainable development The term of energy self-sufficient buildings are not clearly defined. To work with them it was necessary to determine their basic definition that describes their diverse conceptual variations and allows precisely define the solution area. To correctly select the optimal solution in terms of sustainable development is necessary the assessment and mutual comparison since the beginning. As a basic tool for this assessment was used and partially modified SBTool, which is built on three basic pillars of sustainable development - SOCIAL - ENVIRONMENTAL - ECONOMIC. SBTool tries to determine the degree of left traces of the approach from the perspectives of these three aspects and evaluate the effectiveness of the selected solution. This tool allow to compare the different concepts for the same project among themselves, their parts but also various projects among each other. All of course with regard to the development of various aspects in the time.
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MORAVSKÉ VINAŘSKÉ CENTRUM / Moravian Wine CenterFűlőpová, Andrea January 2018 (has links)
Modern winery complex hotel Hrůdek is situated on the north part of village Velké Pavlovice, in the heart of south Moravia the Czech Republic. Its significant placement on the south hillside offers beautiful views to the vineyards and apricot plantations. The architectural form of the building is inspired by the regularity and rhythm of vineyard lines, significant horizontal landscape around and rounded contour lines. Embedding of the building into the slope reacts to the topography of the terrain and refers to the traditional principle of local two-storey wine press houses. From the upper part is the entrance to the accommodation part and from the lover part of the slope is entrance to the wine cellar – the gallery of wine. Hotel offers 4-stars class accommodation, two congress halls, restaurant, wellness and gallery of the wine. Project integrates energetic eco-friendly concepts and its proposed as the self-sufficient building.
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Necessary and Sufficient Conditions on State Transformations That Preserve the Causal Structure of LTI Dynamical NetworksLeung, Chi Ho 01 May 2019 (has links)
Linear time-invariant (LTI) dynamic networks are described by their dynamical structure function, and generally, they have many possible state space realizations. This work characterizes the necessary and sufficient conditions on a state transformation that preserves the dynamical structure function, thereby generating the entire set of realizations of a given order for a specific dynamic network.
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Necessary and Sufficient Conditions on State Transformations That Preserve the Causal Structure of LTI Dynamical NetworksLeung, Chi Ho 01 May 2019 (has links)
Linear time-invariant (LTI) dynamic networks are described by their dynamical structure function, and generally, they have many possible state space realizations. This work characterizes the necessary and sufficient conditions on a state transformation that preserves the dynamical structure function, thereby generating the entire set of realizations of a given order for a specific dynamic network.
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Exploring off-grid electricity production in Sweden: Benefits vs costs / Undersöker off-grid elproduktion i Sverige: Fördelar mot kostnaderBjörkman, Jesper, Lundqvist, Simon January 2020 (has links)
Over the past decade, technologies that facilitate household electricity production and storage have seen a rapid development along with a significant cost reduction. Research points to an increased share of household-produced electricity within the existing national grids across the globe. In some cases, self-sufficiency is possible where households are able to decouple from the grid and become independent on their electricity, in other words, go off-grid. Furthermore, this change puts additional pressure on how the electricity system is set up, which, challenges prevailing incumbents to adapt. Depending on the geographical location, circumstances for selfsufficiency varies. Sweden is a country with high seasonal variations with its Northern position, which raises the question of how off-grid households are feasible and, how they can receive traction. To investigate possible changes within large technical systems such as the electricity system, which is a vital part of the society, theories within socio-technical systems have shown much promise. However, these theories often lack the more techno-economic aspect of concrete and future investment costs from a consumer perspective, suggesting an existing research gap. Hence, the purpose of this study is to provide further knowledge regarding off-grid applications in the Swedish Context. This is done by investigating what circumstances could trigger existing electricity consumers to go off-grid. The research process and structure of the report can be interpreted as indiscriminate, however, the study has focused on combining theories surrounding socio-technical changes whilst applying techno-economic modelling to strengthen the work, similar to a dual paper study. Data was collected in the form of a literature review and interviews to provide a holistic representation of off-grid and its nexus to the electricity system. In addition to this, complementing modelling of grid-connected-, prosumer-, and off-grid households were performed. Results point towards a scene where off-grid reaches grid parity within the coming two decades, which, will increase the economic rationale of investing in an off-grid. Opposingly, there is currently no economic rationale in off-grid applications considering the relatively low electricity costs in Sweden as of today. Moreover, conditions show promise if the adopters see beyond economics and, possesses a strong will towards independence. However, implications suggest that the high reliability and low costs of the Swedish electricity grid impedes the ability of new radical innovations to receive traction. Furthermore, this study has contributed by filling the research gap between socio-technical changes and techno-economic projects in regards to electricity systems. Consequently, contributing to the academic field of socio-technical change, it has been shown that the combination of socio-technical change and techno-economic projections is applicable and beneficial. Additionally, it can be argued that the results of this study highlight that the consumer have a greater role in the development of off-grid applications than what the theories suggest. Lastly, the electricity system is a complex mechanism and, to further strengthen the perception of how a relatively new application, as in the case of off-grid, will impact the system, appurtenant suggestions for possible future research within the area are proposed. / Under det senaste decenniet har teknik som underlättar hushållens elproduktion och lagring haft en hastig utveckling tillsammans med en betydande kostnadsminskning. Forskning pekar på en ökad andel hushållsproducerad el inom de befintliga nationella elnäten över hela världen. I vissa fall är självförsörjning möjligt där hushållen kan koppla bort sig från nätet och bli oberoende av sin elförsörjning, med andra ord gå off-grid. Vidare leder en potentiell förändring mot offgrid till ytterligare påtryckningar på hur elsystemet är uppbyggt, vilket utmanar många aktörers sätt att agera. Beroende på geografisk plats så varierar förutsättningarna för självförsörjning. Sverige är ett land med stora säsongsvariationer i och med sin nordliga position, vilket väcker frågan om off-grid hushåll är genomförbara i Sverige och hur de kan skulle kunna etableras. För att undersöka möjliga förändringar inom stora tekniska system som elsystemet, som är en viktig del av samhället, har teorier inom socio-tekniska system visat vara till stor nytta. Däremot saknar dessa teorier emellertid den mer tekno-ekonomiska aspekten av konkreta och framtida investeringskostnader ur ett konsumentperspektiv, vilket antyder ett befintligt forskningsgap. Följaktligen är syftet med den här studien att ge ytterligare inblick om off-grid-applikationer i svenska sammanhang. Vilket har gjorts genom att undersöka vilka omständigheter som kan leda till att befintliga elkonsumenter går off-grid. Forskningsprocessen och strukturen i rapporten kan vara svårtolkat, men studien har fokuserat på att kombinera teorier kring socio-tekniska förändringar samtidigt som man använder teknoekonomisk modellering för att stärka arbetet. Data samlades in i form av en litteraturstudie och intervjuer för att ge en holistisk representation av off-grid och dess koppling till elsystemet. Utöver litteraturstudie utfördes kompletterande modellering av hushållsanslutna, prosumeroch off-gridhushåll. Resultaten pekar mot scenarion där off-grid når nätparitet under de kommande två decennierna, vilket kommer att öka den ekonomiska rationaliteten för att investera i ett off-grid. Det finns det för närvarande inga ekonomiska skäl till att investera off-grid-applikationer med tanke på de relativt låga elkostnaderna i Sverige idag. Förhållandena visar dessutom löfte om att potentiella användare ser förbi ekonomin och har istället en stark vilja mot självständighet. Implikationer tyder emellertid på att det svenska elnätets höga tillförlitlighet och låga pris hindrar nya radikala innovationers förmåga att ta få fäste. Det är argumenterbart att den här studien har bidragit med att fylla forskningsgapet mellan socio-tekniska förändringar och tekno-ekonomiska projektioner inom elsystem. Samtidigt har studien bidragit till det vetenskapliga området kring socio-tekniska visat på möjligheten och fördelen i att kombinera teorier kring socio-teknisk förändring och tekno-ekonomiska förändringar. Dessutom kan det hävdas att resultaten av den här studie visar att konsumenten har en större roll i utvecklingen av applikationer utanför nätet än vad teorierna föreslår. Slutligen är elsystemet en komplex mekanism, och för att ytterligare stärka uppfattningen om hur en relativt ny applikation, som i fallet utanför nätet, kommer att påverka systemet föreslås lämpliga förslag för eventuell framtida forskning inom området.
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Statistical InferenceChou, Pei-Hsin 26 June 2008 (has links)
In this paper, we will investigate the important properties of three major parts of statistical inference: point estimation, interval estimation and hypothesis testing. For point estimation, we consider the two methods of finding estimators: moment estimators and maximum likelihood estimators, and three methods of evaluating estimators: mean squared error, best unbiased estimators and sufficiency and unbiasedness. For interval estimation, we consider the the general confidence interval, confidence interval in one sample, confidence interval in two samples, sample sizes and finite population correction factors. In hypothesis testing, we consider the theory of testing of hypotheses, testing in one sample, testing in two samples, and the three methods of finding tests: uniformly most powerful test, likelihood ratio test and goodness of fit test. Many examples are used to illustrate their applications.
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Colombia: Postured for Failure, a Lesson in Counterinsurgency StrategyBrodie, Abdullah 01 January 2009 (has links)
There is little solid research that explores counterinsurgency practices against the Revolutionary Armed Forces of Colombia (FARC), not only from the standpoint of what is being done, but, rather, what should be done based on past COIN successes. Notable works on counterinsurgency in Colombia include the research of Tom Marks, who focused on operational strategy and tactics; Kevin Self, who professes the importance of controlling territory in defeating the FARC, by addressing the social and institutional ills within Colombia itself; and Dennis Rempe, who notes US involvement in shaping Colombia's COIN strategy. Using a comparative case study model, this thesis provides an analysis of Colombia?s counterinsurgency (COIN) strategies and tactics through the lens of successful and unsuccessful COIN operations in Iraq, Algeria, Malaya, South Vietnam, Thailand, Algeria and El Salvador over the course of the 20th and early 21st centuries. After all, no matter how successful a COIN force is militarily, their accomplishments will ultimately be fruitless if the conditions which fuel insurgency remains present. This paper begins by providing the historical context for the conditions which shaped the Colombian social order, which led to the revolutionary movement. It then follows the growth of the FARC, examining that organization?s strengths and weaknesses. The FARC is contrasted by outlining recent COIN transformation efforts within the Colombian government, to include little acknowledged failures and successes, strengths and weaknesses. An important focus is placed on Colombian President Alvaro Uribe Velez? Democratic Security Policy as the model for Colombia?s current COIN efforts. After next examining various ongoing factors contributing to the Colombian insurgency?to include institutional failures, illicit funding and the problem of paramilitary groups?this thesis examines past COIN efforts by other governments. Finally, after applying lessons learned from thee past COIN efforts?cross-referencing historically successful and unsuccessful tactics with tactics used and not used by Bogota in its fight against the FARC?I provide recommendations to the government of Colombia (GOC) on how to improve its COIN efforts. Although it is important to look at this problem set from an external standpoint, we must still factor in internal factors that have limited Colombia?s ability to emerge victorious, such as allowing porous borders, airspace and coastlines; placing a priority on killing or capturing the enemy and not on engaging the population; and the primacy of military direction of counterinsurgency; disregard of basic human rights; an insufficient judiciary structure; failure to halt financial support mechanisms; and the lack of an outlet for political inclusion . From this vantage point, we will be able to see that these elements?when properly implemented?have proven successful over time and may enhance GOC success and ultimately result in victory over the insurgency that has plagued their country for 40+ years
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