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Thesis (M.S.)--Mississippi State University. Department of Industrial Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Kentucky, 2001. / Title from document title page. Document formatted into pages; contains vii, 75 p. : ill. Includes abstract. Includes bibliographical references (p. 70-72).

Thesis (Ph. D.)--School of Aerospace Engineering, Georgia Institute of Technology, 2004. Directed by Dewey H. Hodges. / Vita. Includes bibliographical references (leaves 162-176).

Bakgrund: Ett lager är en viktig del av de flesta värdekedjor. Stora ansträngningar har därför under de senaste åren gjorts för att finna optimala strategier för planering och kontroll av lagersystem. För att uppnå en ökad produktion krävs det att kapacitetsutnyttjandet förbättras. Genom att planera sin kapacitet kan företag reducera kapacitetsbegräsningar, så kallade flaskhalsar, som är nyckeln till att förbättra produktionens kapacitetsutnyttjande. Syfte: Syftet med studien är att beskriva Staples nuvarande kapacitetsutnyttjande i påfyllnads- och plockprocessen. Vidare avser studien att identifiera kapacitetsbegränsningar inom dessa processer. Därefter ämnar studien att finna de bakomliggande orsakerna till dessa kapacitetsbegränsningar samt hur de kan förbättras. Metod: Det har genomförts ostrukturerade intervjuer, semi-strukturerade intervjuer, deltagande observationer samt insamling av kvantitativ data. Inledningsvis genomfördes en processkartläggning i syfte som ett verktyg för resterande delar av studien. Vidare utfördes beräkningar för att finna flaskhalsar i produktionen och intervjuer för att identifiera störningsmoment inom flaskhalsarna. Slutligen presenterades ett antal förbättringsförslag. Slutsatser: Efter genomförda beräkningar framgick att Staples idag inte utnyttjar sin kapacitet maximalt, dock är maximal kapacitet är en nivå som inte anses vara rimlig. Det framgick att Staples har ett kapacitetsbortfall på grund av att det finns en differens mellan nominell kapacitet och bruttokapacitet. Slutsatsen drogs att följande tre aktiviteter utgör flaskhalsar i Staples verksamhet; godsmottagning, plock ZtZ (plock av framförallt tyngre och otympliga artiklar) och plock PTS (detaljplock). Inom dessa flaskhalsar påträffades ett antal störningsmoment som till stor del har grund inom deiiiteoretiska områdena som Stevenson (2009), Slack et al. (2012) och Bergman och Klefsjö (2012) benämner som anläggning och teknik samt metod. Vidare fastslogs att en svårighet finns i att ge kortsiktiga förbättringsförslag för dessa störningsmoment. Detta på grund av studiens tidsram samt att det berör ämnen utanför studiens omfattning. Det presenteras dock tre scenarier för att hitta en fördelaktig fördelning av kapacitet mellan PTS och ZtZ. Dessa scenarier bygger på tre tidsintervaller för hur produktionen är igång samt två plockhastigheter. Baserat på att PTS:en innehar en större andel aktiva arbetstimmar och en högre plockhastighet är scenario 3 mest fördelaktigt eftersom det krävs att ZtZ är minst verksam. / Background: A warehouse is an important part of most value chains. Great effort has in recent years been made to find optimal strategies for planning and control of storage system. In order to achieve a higher production it requires the capacity utilization to be improved. By planning its capacity, companies can reduce capacity constraints, so-called bottlenecks, which is the key to improving the production’s capacity utilization. Purpose: The aim of this study is to describe Staples current capacity utilization in the filling and picking process. Furthermore, the study aim to identify capacity constraints in these processes. Then, the study intends to find the causes of these capacity constraints and how they can be improved. Method: There have been unstructured interviews, semi-structured interviews, participant observation and collection of quantitative data. Initially there was a process mapping in purpose of a tool for the remaining study. Further calculations were performed to find bottlenecks in the production and interviews to identify disturbances in the bottlenecks. Finally, a number of suggestions for improvement where presented. Conclusions: Calculations revealed that Staples is currently not using their capacity to the maximum, altough this is not a level considered reasonable. It appeared that the company has a capacity shortfall when there was a difference between the nominal capacity and gross capacity. It was concluded that the following three activities constituted bottlenecks in Staples; receiving, picking ZtZ (picking of particularly heavy and bulky items) and picking PTS (detail picking). Within these bottlenecks, there was a number of disturbances found that largely had their basis in the teoratical areas Stevenson (2009), Slack et al. (2012) and Bergman and Klefsjö (2012) terms as facility and technology and method. Furthermore, it was established a difficulty in providingvshort-term improvement suggestions to these disturbances. This’s because of the study's time frame and that it reach subjects outside the scope of the study. However, three scenarios are presented to find a favorable allocation of capacity between PTS and ZTZ. These scenarios are based on three time intervals for how production is running and two picking speeds. Based on that the PTS holds a higher proportion of active working hours and a faster pick-speed scenario 3 is the most beneficial because it requires that ZTZ is least active.

Monitoring of user-defined constraints on time-varying data is a fundamental functionality in various sensor-based real-time applications such as environmental monitoring, process control, location-based surveillance, etc. In general, these applications track real-world objects and constantly evaluate the constraints over the object trace to take a timely reaction upon their violation or satisfaction. While it is ideal that all the constraints are evaluated accurately in real-time, data streams often contain incomplete and delayed information, rendering the evaluation results of the constraints uncertain to some degree. In this dissertation, we provide a comprehensive approach to the problem of monitoring constraint-based queries over data streams for which the data or timestamp values are inherently uncertain. First, we propose a generic framework, namely Ptmon, for monitoring timing constraints and detecting their violation early, based on the notion of probabilistic violation time. In doing so, we provide a systemic approach for deriving a set of necessary timing constraints at compilation time. Our work is innovative in that the framework is formulated to be modular with respect to the probability distributions on timestamp values. We demonstrate the applicability of the framework for different timestamp models. Second, we present a probabilistic timing join operator, namely Ptjoin, as an extended functionality of Ptmon, which performs stream join operations based on temporal proximity as well as temporal uncertainty. To efficiently check the Ptjoin condition upon event arrivals, we introduce the stream-partitioning technique that delimits the probing range tightly. Third, we address the problem of monitoring value-based constraints that are in the form of range predicates on uncertain data values with confidence thresholds. A new monitoring scheme Spmon that can reduce the amount of data transmission and thus expedite the processing of uncertain data streams is introduced. The similarity concept that was originally intended for real-time databases is extended for our probabilistic data stream model where each data value is given by a probability distribution. In particular, for uniform and gaussian distributions, we show how we derive a set of constraints on distribution parameters as a metric of similarity distances, exploiting the semantics of probabilistic queries being monitored. The derived constraints enable us to formulate the probabilistic similarity region that suppresses unnecessary data transmission in a monitoring system. / text

In this thesis we propose a new class of Linearly Constrained Convex Optimization methods based on the use of a generalization of Shepard's interpolation formula. We prove the properties of the surface such as the interpolation property at the boundary of the feasible region and the convergence of the gradient to the null space of the constraints at the boundary. We explore several descent techniques such as steepest descent, two quasi-Newton methods and the Newton's method. Moreover, we implement in the Matlab language several versions of the method, particularly for the case of Quadratic Programming with bounded variables. Finally, we carry out performance tests against Matab Optimization Toolbox methods for convex optimization and implementations of the standard log-barrier and active-set methods. We conclude that the steepest descent technique seems to be the best choice so far for our method and that it is competitive with other standard methods both in performance and empirical growth order.

In this work, we present a new method for seismic waveform characterization, which is aimed at extracting detailed litho-stratigraphical information from seismic data. We attempt to estimate the lithological attributes from seismic data according to our parametric representation of stratigraphical horizons, where the parameter values provide us with a direct link to nature of lithological transitions. We test our method on a seismic dataset with a strong diagenetic transition (opal-A to opal-CT transition). Given some information from cutting samples of well, we use a percolation-based model to construct the elastic profile of lithological transitions. Our goal is to match parametric representation for the diagenetic transition in both real data and synthetic data given by these elastic profiles. This match may be interpreted as a well-seismic tie, which reveals lithological information about stratigraphical horizons.

Integrity constraints comprise an urgent part of conceptual models. For this reason, they must be structured and represented in orderly manner. The purpose of this work is to solve the problems inherent in creation, storage and retrieval of centralized data integrity constraints. This paper analyses the methods for implementation of data integrity constraints and describes a Oracle RDBMS-based technique that enables for impeccable functionality of information system and protection from invalid data. After analysis of system requirements and currently available software solutions, UML models of system architecture, data and database were proposed. Suitable means were chosen for developing a system for centralist management of data integrity constraints. The Constraint Editor geared towards designing, implementing and maintaining of procedures, integrity constraints throughout their lifecycle was developed. A simple, functional and intuitive graphical user interface makes data integrity constraints easy to story, manage and retrieve. The created software makes optimal use of RDBVS resources while performing ETL processes with multi – table insertions. The ability to insert data into multiple tables ensures further possibilities of supplying standard statistical analysis software with correct data and better performance than a procedure to perform multiple insertions using "IF..THEN" syntax. Furthermore, the software verifies SQL DML functions system widethus protecting... [to full text]

Chinese international students are the largest group among international students in Canada. They play an important role in Canadian universities as well as in leisure research. The current study aims to reveal Chinese international students’ leisure experience, and to explore their leisure constraints and negotiation strategies in their everyday lives. The framework of leisure constraints negotiation (Jackson, 1993) was employed. Eight interviews with Chinese international students from the University of Manitoba were conducted to hear the stories about their leisure experiences. The constant comparative method was used to analyze the data. Chinese international students were found to be constrained intrapersonally, interpersonally, structurally, and culturally in their leisure. However, they were trying to be active by applying some negotiation strategies. The results of this study can not only benefit this group but also other international student groups by identifying their leisure preferences and constraints, and help leisure service providers to facilitate leisure activities on campus.