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Scheduling for Service Stability and Supply Chain CoordinationChen, Yuerong 01 August 2009 (has links)
This dissertation studies scheduling for service stability and for supply chain coordination as well. The scheduling problems for service stability are studied from the single perspective of a firm itself, while the scheduling problems for supply chain coordination are investigated from the perspective of a supply chain. Both the studies have broad applications in real life.
In the first study, several job scheduling problems are addressed, with the measure of performance being job completion time variance (CTV). CTV minimization is used to represent service stability, since it means that jobs are completed in a relative concentrated period of time. CTV minimization also conforms to the Just-in-time philosophy. Two scheduling problems are studied on multiple identical parallel machines. The one problem does not restrict the idle times of machines before their job processing, while the other does. For these two scheduling problems, desirable properties are explored and heuristic algorithms are proposed. Computational results show the excellent performances of the proposed algorithms. The third scheduling problem in the first study is considered on a single machine and from the users’ perspective rather than the system’s perspective. The performance measure is thus class-based completion time variance (CB-CTV). This problem is shown to be able to be transformed into multiple CTV problems. Therefore, the well-developed desirable properties of the CTV problem can be applied to solve the CB-CTV problem. The tradeoff between the CB-CTV problem and the CTV problem is also investigated.
The second study deals with scheduling coordination in a supply chain, since supply chain coordination is increasingly critical in recent years. Usually, different standpoints prevent decision makers in a supply chain from having agreement on a certain scheduling decision. Therefore conflicts arise. In pursuit of excellent performance of the whole supply chain, coordination among decision makers is needed. In this study, the scheduling conflicts are measured and analyzed from different perspectives of decision makers, and cooperation mechanisms are proposed based on different scenarios of the relative bargaining power among decision makers. The cooperation savings are examined as well.
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QoS Provision for Wireless Sensor NetworksYang, Dengfeng 01 August 2009 (has links)
Wireless sensor network is a fast growing area of research, receiving attention not only within the computer science and electrical engineering communities, but also in relation to network optimization, scheduling, risk and reliability analysis within industrial and system engineering. The availability of micro-sensors and low-power wireless communications will enable the deployment of densely distributed sensor/actuator networks. And an integration of such system plays critical roles in many facets of human life ranging from intelligent assistants in hospitals to manufacturing process, to rescue agents in large scale disaster response, to sensor networks tracking environment phenomena, and others.
The sensor nodes will perform significant signal processing, computation, and network self-configuration to achieve scalable, secure, robust and long-lived networks. More specifically, sensor nodes will do local processing to reduce energy costs, and key exchanges to ensure robust communications. These requirements pose interesting challenges for networking research. The most important technical challenge arises from the development of an integrated system which is 1)energy efficient because the system must be long-lived and operate without manual intervention, 2)reliable for data communication and robust to attackers because information security and system robustness are important in sensitive applications, such as military.
Based on the above challenges, this dissertation provides Quality of Service (QoS) implementation and evaluation for the wireless sensor networks. It includes the following 3 modules, 1) energy-efficient routing, 2) energy-efficient coverage, 3). communication security. Energy-efficient routing combines the features of minimum energy consumption routing protocols with minimum computational cost routing protocols. Energy-efficient coverage provides on-demand sensing and measurement. Information security needs a security key exchange scheme to ensure reliable and robust communication links. QoS evaluation metrics and results are presented based on the above requirements.
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Yield and Reliability Analysis for NanoelectronicsYuan, Tao 01 December 2007 (has links)
As technology has continued to advance and more break-through emerge, semiconductor devices with dimensions in nanometers have entered into all spheres of our lives. Accordingly, high reliability and high yield are very much a central concern to guarantee the advancement and utilization of nanoelectronic products. However, there appear to be some major challenges related to nanoelectronics in regard to the field of reliability: identification of the failure mechanisms, enhancement of the low yields of nano products, and management of the scarcity and secrecy of available data [34]. Therefore, this dissertation investigates four issues related to the yield and reliability of nanoelectronics.
Yield and reliability of nanoelectronics are affected by defects generated in the manufacturing processes. An automatic method using model-based clustering has been developed to detect the defect clusters and identify their patterns where the distribution of the clustered defects is modeled by a new mixture distribution of multivariate normal distributions and principal curves. The new mixture model is capable of modeling defect clusters with amorphous, curvilinear, and linear patterns. We evaluate the proposed method using both simulated and experimental data and promising results have been obtained.
Yield is one of the most important performance indexes for measuring the success of nano fabrication and manufacturing. Accurate yield estimation and prediction is essential for evaluating productivity and estimating production cost. This research studies advanced yield modeling approaches which consider the spatial variations of defects or defect counts. Results from real wafer map data show that the new yield models provide significant improvement in yield estimation compared to the traditional Poisson model and negative binomial model.
The ultra-thin SiO2 is a major factor limiting the scaling of semiconductor devices. High-k gate dielectric materials such as HfO2 will replace SiO2 in future generations of MOS devices. This study investigates the two-step breakdown mechanisms and breakdown sequences of double-layered high-k gate stacks by monitoring the relaxation of the dielectric films.
The hazard rate is a widely used metric for measuring the reliability of electronic products. This dissertation studies the hazard rate function of gate dielectrics breakdown. A physically feasible failure time distribution is used to model the time-to-breakdown data and a Bayesian approach is adopted in the statistical analysis.
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Demand Estimation at Manufacturer-Retailer Duo: A Macro-Micro ApproachSaripalli, Sirisha 01 May 2008 (has links)
This dissertation is divided into two phases. The main objective of this phase is to use Bayesian MCMC technique, to attain (1) estimates, (2) predictions and (3) posterior probability of sales greater than certain amount for sampled regions and any random region selected from the population or sample. These regions are served by a single product manufacturer who is considered to be similar to newsvendor. The optimal estimates, predictions and posterior probabilities are obtained in presence of advertising expenditure set by the manufacturer, past historical sales data that contains both censored and exact observations and finally stochastic regional effects that cannot be quantified but are believed to strongly influence future demand. Knowledge of these optimal values is useful in eliminating stock-out and excess inventory holding situations while increasing the profitability across the entire supply chain.
Subsequently, the second phase, examines the impact of Cournot and Stackelberg games in a supply-chain on shelf space allocation and pricing decisions. In particular, we consider two scenarios: (1) two manufacturers competing for shelf space allocation at a single retailer, and (2) two manufacturers competing for shelf space allocation at two competing retailers, whose pricing decisions influence their demand which in turn influences their shelf-space allocation. We obtain the optimal pricing and shelf-space allocation in these two scenarios by optimizing the profit functions for each of the players in the game. Our numerical results indicate that (1) Cournot games to be the most profitable along the whole supply chain whereas Stackelberg games and mixed games turn out to be least profitable, and (2) higher the shelf space elasticity, lower the wholesale price of the product; conversely, lower the retail price of the product, greater the shelf space allocated for that product.
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Heuristic Procedures to Solve Sequencing and Scheduling Problems in Automobile IndustryHe, Jingxu 01 May 2008 (has links)
With the growing trend for greater product variety, mixed-model assembly nowadays is commonly employed in many industries, which can enable just-in-time production for a production system with high variety. Efficient production scheduling and sequencing is important to achieve the overall material supply, production, and distribution efficiency around the mixed-model assembly line. This research addresses production scheduling and sequencing on a mixed-model assembly line for products with multiple product options, considering multiple objectives with regard to material supply, manufacturing, and product distribution. This research also addresses plant assignment for a product with multiple product options as a prior step to scheduling and sequencing for a mixed-model assembly line. This dissertation is organized into three parts based on three papers.
Introduction and literature review
Part 1. In an automobile assembly plant many product options often need to be considered in sequencing an assembly line with which multiple objectives often need to be considered. A general heuristic procedure is developed for sequencing automobile assembly lines considering multiple options. The procedure uses the construction, swapping, and re-sequencing steps, and a limited search for sequencing automobile assembly lines considering multiple options.
Part 2. In a supply chain, production scheduling and finished goods distribution have been increasingly considered in an integrated manner to achieve an overall best efficiency. This research presents a heuristic procedure to achieve an integrated consideration of production scheduling and product distribution with production smoothing for the automobile just-in-time production assembly line. A meta-heuristic procedure is also developed for improving the heuristic solution.
Part 3. For a product that can be manufactured in multiple facilities, assigning orders to the facility is a common problem faced by industry considering production, material constraints, and other supply-chain related constraints. This paper addresses products with multiple product options for plant assignment with regard to multiple constraints at individual plants in order to minimize transportation costs and costs of assignment infeasibility. A series of binary- and mixed-integer programming models are presented, and a decision support tool based on optimization models is presented with a case study.
Summary and conclusions
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Reliability Analysis of Hafnium Oxide Dielectric Based NanoelectronicsWan, Rui 01 December 2008 (has links)
With the physical dimensions ever scaling down, the increasing level of sophistication in nano-electronics requires a comprehensive and multidisciplinary reliability investigation. A kind of nano-devices, HfO2-based high-k dielectric films, are studied in the statistical aspect of reliability as well as electrical and physical aspects of reliability characterization, including charge trapping and degradation mechanisms, breakdown modes and bathtub failure rate estimation.
This research characterizes charge trapping and investigates degradation mechanisms in high-k dielectrics. Positive charges trapped in both bulk and interface contribute to the interface state generation and flat band voltage shift when electrons are injected from the gate under a negative gate bias condition.A negligible number of defects are generated until the stress voltage increases to a certain level. As results of hot electrons and positive charges trapped in the interface region, the difference in the breakdown sequence is attributed to the physical thickness of the bulk high-k layer and the structure of the interface layer.
Time-to-breakdown data collected in the accelerated life tests are modeled with a bathtub failure rate curve by a 3-step Bayesian approach. Rather than individually considering each stress level in accelerating life tests (ALT), this approach derives the change point and the priors for Bayesian analysis from the time-to-failure data under neighborhood stresses, based on the relationship between the lifetime and stress voltage. This method can provide a fast and reliable estimation of failure rate for burn-in optimization when only a small sample of data is available.
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Essays on Timing of Firm Actions in Industrial EconomicsLi, Youping 01 August 2011 (has links)
The timing of actions by firms plays an important role in industrial economics. It is key to strategic advantage in oligopoly models whether firms compete on quantity or on price. In a vertical relationship between input suppliers and final-good manufacturers, a firm which chooses a strategy first will take into account the response by those firms moving second and different sequence of play leads to different market outcomes. In my dissertation, I study the determinants and implications of the timing of firm actions in a variety of scenarios. In my first two essays, I examine how market leadership may arise endogenously in oligopoly models and focus on the effect of information about uncertain market demand. My first essay studies a quantity game and I identify the circumstance under which a perishable information asymmetry regarding stochastic demand causes market leadership. In an information acquisition game, I show that Stackelberg equilibrium in the full game is supported only when firms have different costs of information. My second essay considers a duopoly in which firms supply a differentiated product and compete on price. I find that different equilibrium outcomes arise under different information structures. Under asymmetric information, a firm’s information advantage leads to a strategic disadvantage of leading in the price game. The time value of information may well be negative, contrasting with results in the first essay. In my third essay, I consider a vertical relationship in which a supplier sets the price of an input and the firm that produces the final good must choose how much to invest in some complementary input or process. Two models with different sequence of firm actions are studied and yield different pricing strategies for the upstream monopolist. Interestingly, a change of the sequence from one model (the upstream firm commits to input prices first) to the other (the upstream firm sets input prices after investments are made) benefits all parties including the upstream monopolist, the downstream firms and the consumers.
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Demand Forecasting Model for Emergent ManufacturingAhmed, Naveed Ahmed Nasar 01 May 2008 (has links)
Emergence of outsourcing and global partnerships has driven the need for emergent manufacturing. Emergent manufacturing is a concept and mechanism that allows manufacturing based organizations to mitigate the risk of outsourcing their manufacturing functions. The implementation of emergent manufacturing is on a rise and yet many industrial facilities have to decide when to switch to emergent manufacturing.
To achieve a strategic fit of emergent manufacturing with the existing manufacturing facilities is the current need of the Industry. There is a strong need to develop a body of literature and models specifically for this task.
This thesis aims to develop a model to better forecast the demand of emergent manufacturing. This is achieved by designing mathematical, simulation and statistical models to predict the demand of emergent manufacturing. This new proposed model would develop a guide line to implement, manage and sustain emergent manufacturing in today‟s aggressively outsourcing world, where manufacturing facilities are rapidly being downsized to cut down operational costs.
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Path Forward to Design and Implement an On-going Engineering Management HandbookKring, Robert B 01 May 2008 (has links)
The purpose of this thesis was to determine a path forward to design and implement an on-going Engineering Management Handbook. A review was performed to establish a definition of Engineering Management, the history of Engineering Management, how this history has impacted the Body of Knowledge in Engineering Management over the years, and the current state of the Engineering Management Handbook. Two surveys were performed to discover how users perceive the Handbook. It was found that there was a desire for a useful on-line EM Handbook. This research allows for decisions to be made in the future as the Handbook is updated by showing what subjects and features are most important to users, as well as the need for structure development from the beginning. The features and structure of the Handbook are proposed, along with submission guidelines. The functionality is presented through a series of examples to illustrate the use of the new Engineering Management Handbook.
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The Impact of Organizational Attributes on Project Performance as Measured by On-Time Delivery and BudgetEl-Akkad, Zeid 01 August 2007 (has links)
Before we determine what lean tools are suitable for an office environment and how to modify those tools to make them more suitable and in order to develop a lean office, it is important to understand the different processes and aspects within an office. For this reason, better understanding of office processes and aspects helps facilitate the deployment and implementation and modification of different lean techniques to better suit the office environment. The purpose of this paper is to identify seven different factors to compare against one another and against project performance in terms of on-time delivery and budget. The seven factors are as follows: business sector, size of the organization, office layout, information processing, data flow, location, and interaction or lack of interaction among various departments within an organization. A hypothesis will be developed regarding each of these factors, and subsequently a survey will be created and conducted. A statistical analysis of this survey will be done using primarily a Chi Square test to determine whether our hypotheses can be validated by the data.
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