Recently, a new form of organizing, sharing and finding information, named tagging, has gained importance because its results are the product of the combined efforts of the actual users’ opinions of the information. In this paper, we explore the conceptual model of the del.icio.us tagging system in order to investigate the degree to which the tagging system’s conceptual model reflects the human conceptual knowledge structure at both the population level and the individual level. We use datasets extracted from the del.icio.us system from 2003 to 2007 to obtain the strength of connection among tags, and compare that with data for the association of the same concepts by actual human beings. The results show that, overall, the conceptual model for the del.icio.us tagging system captures human’s notion of concept similarity. Several potential applications are mentioned.

Most literature on facility location assumes a fixed set-up cost and a linear variable cost. However, as production volume increases, cost savings are achieved through economies of scale, and then when production exceeds a certain capacity level, congestion occurs and costs start to increase significantly. This leads to an S-shaped cost function that makes the location-allocation decisions challenging. This thesis presents a nonlinear mixed integer programming formulation for the facility location problem with economies of scale and congestion and proposes a Lagrangian solution approach. Testing on a variety of functions and cost settings reveals the efficiency of the proposed approach in finding solutions that are within an average gap of 3.79% from optimal.

We study a two-stage stochastic facility location problem in the context of disaster response network design. The uncertainty inherent in disaster occurrence and impact is captured by defining scenarios to reflect a large spectrum of possible occurrences. In the first stage (pre-event response), planners should decide on locating a set of facilities in strategic regions. In the second stage (post-event response), some of these facilities are to be activated to respond to demand in the disaster affected region. The second-stage decisions depend on disaster occurrence and impact which are highly uncertain. To model this uncertainty, a large number of scenarios are defined to reflect a large spectrum of possible occurrences. In this case, facility activation and demand allocation decisions are made under each scenario. The aim is to minimize the total cost of locating facilities in the first stage plus the expected cost of facility activation and demand allocation under all scenarios in the second stage while satisfying demand subject to facility and arc capacities. We propose a mixed integer programming model with binary facility location variables in the first stage and binary facility activation variables and fractional demand allocation variables in the second stage. We propose two Lagrangian relaxations and several valid cuts to improve the bounds. We experiment with aggregated, disaggregated and hybrid implementations in calculating the Lagrangian bound and develop several Lagrangian heuristics. We perform extensive numerical testing to investigate the effect of valid cuts and disaggregation and to compare the relaxations. The second relaxation proved to provide a tight bound as well as high quality feasible solutions.

Under de senaste sju åren har golfintresset i Sverige stadigt minskat. Denna studie tar upp möjligheten att genom en mer dynamisk prissättning återvinna golfintresset i Sverige och öka golfklubbars intäkter. För att åstadkomma detta utgår studien från att teorier om intäktsmaximering (revenue management), hämtade från besläktade branscher som flyg och hotell, även är applicerbara på golfbranschen. För att undersöka frågeställningen ”Hur kan en modell för ytterligare differentierad prissättning tas fram för den svenska golfmarknaden?” har en kvantitativ undersökning gjorts. Denna utgår i huvudsak från intervjuer med ansvariga på två svenska golfklubbar, två ansvariga för svenska golfklubbars gemensamma IT-stöd GIT (golfens it-system). Resultatet av studien är att teorier om revenue management i viss mån är applicerbara på den svenska golfbranschen i syfte att skapa högre intäkter. Klubbar måste vara noggrannare med att samla information om spelare, när de spelar och hur nöjda de är med upplevelsen, för att kunna erbjuda en mer differentierad prisbild som gör att klubben säljer sina produkter till rätt person, vid rätt tid, till rätt pris.

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Diplomarbeit--Zugl.: Fachhochschulverein Inntal, 2002.

Thesis (Ph.D.)--Oklahoma State University, 2009. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--Oklahoma State University, 2009. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of South Florida, 2002. / Title from PDF of title page. Document formatted into pages; contains 323 pages. Includes bibliographical references.