Matching Items (32)

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Stochastic Optimization of Product-Machine Qualification in a Semiconductor Back-End Facility

Description

In order to process a product in a semiconductor back-end facility, a machine needs to be qualified, first by having product-specific software installed and then running test wafers through it to verify that the machine is capable of performing the

In order to process a product in a semiconductor back-end facility, a machine needs to be qualified, first by having product-specific software installed and then running test wafers through it to verify that the machine is capable of performing the process correctly. In general, not all machines are qualified to process all products due to the high machine qualification cost and tool set availability. The machine qualification decision affects future capacity allocation in the facility and subsequently affects daily production schedules. To balance the tradeoff between current machine qualification costs and future potential backorder costs due to not enough machines qualified with uncertain demand, a stochastic product–machine qualification optimization model is proposed in this article. The L-shaped method and acceleration techniques are proposed to solve the stochastic model. Computational results are provided to show the necessity of the stochastic model and the performance of different solution methods.

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2015-07-03

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Field Vehicle Fleet Management in a Humanitarian Setting

Description

The purpose of this honors thesis is to discover ways for a large humanitarian organization to more cost effectively manage its fleet of vehicles. The first phase of work involved cleaning the large data set provided by the organization. Next,

The purpose of this honors thesis is to discover ways for a large humanitarian organization to more cost effectively manage its fleet of vehicles. The first phase of work involved cleaning the large data set provided by the organization. Next, we used the program STATA to run a Seemingly Unrelated Regression (SUR) to see which variables have the largest effect on the percentage of price decline and total mileage of each vehicle. The SUR model indicated that price decline is most influenced by cumulative minor repairs, total accessories, age, percentage of paved roads, and number of accidents. In addition, total mileage was most affected by percentage of paved roads, cumulative minor repairs, all wheel drive, and age. The final step of the project involved providing recommendations to the humanitarian organization based on the above results. We recommend several changes to their fleet management, including: driver training programs, increasing the amount of preventative maintenance performed on vehicles, and increasing the amount of accessories purchased for each vehicle. Implementing these changes could potentially save the organization millions of dollars due to the scope of its operation.

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2015-12

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A New Balanced Scorecard: Supplier Metrics Measuring Supplier Performance in the Automotive Industry

Description

This paper will explore how suppliers are being evaluated. It will focus on the automotive industry and the state of supplier relations in two major automotive manufacturers in the United States. A literature review will reveal common supplier metrics across

This paper will explore how suppliers are being evaluated. It will focus on the automotive industry and the state of supplier relations in two major automotive manufacturers in the United States. A literature review will reveal common supplier metrics across industries and what they attempt to measure. Further exploration into the structure and problems at one automotive manufacturer will reveal areas of improvement. Finally, a new balanced scorecard system will be proposed to better measure supplier performance.

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2015-05

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The Impact and Consequences of the COVID-19 Pandemic on the Food Supply Chain and Food Insecurity

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My project focuses on the problems created by the COVID-19 pandemic that impacted the food supply chain in the United States and how they contributed to food insecurity. I identified the three key problems, the shift in demand from the

My project focuses on the problems created by the COVID-19 pandemic that impacted the food supply chain in the United States and how they contributed to food insecurity. I identified the three key problems, the shift in demand from the commercial to the retail market, the discarding of raw food and produce, and consumer panic buying. I used the analysis of these problems to then formulate a set of solutions that would work to solve these problems.

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2021-05

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Analysis of the Implementation of the Emergency Food Bag Program and Operations at United Food Bank

Description

The following report is an analysis of the decision to change food distribution at United Food Bank and an analysis on the transition. In order to distribute the best food items in a standard quantity, United Food Bank has come

The following report is an analysis of the decision to change food distribution at United Food Bank and an analysis on the transition. In order to distribute the best food items in a standard quantity, United Food Bank has come up with the idea of Emergency Food Bags (EFB). Packed into reusable bags are a fruit product, a vegetable product, a protein, and a starch meal item. The intention is for the EFB to serve as a grocery supplement and products are intentionally picked so recipients can create meals. With this transition, there are many factors to consider such as production levels and government assistance. This report will address all aspects and give recommendations to United Food Bank.

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2019-05

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Finding the Best Fit to Maximize Responsiveness in Humanitarian Logistics: An Information Processing Perspective

Description

Within humanitarian logistics, there has been a growing trend of adopting information systems to enhance the responsiveness of aid delivery. By utilizing such technology, organizations are able to take advantage of information sharing and its benefits, including improved coordination and

Within humanitarian logistics, there has been a growing trend of adopting information systems to enhance the responsiveness of aid delivery. By utilizing such technology, organizations are able to take advantage of information sharing and its benefits, including improved coordination and reduced uncertainty. This paper seeks to explore this phenomenon using organizational information processing theory. Drawing from complexity literature, we argue that demand complexity should have a positive relationship with information sharing. Moreover, higher levels of information sharing should generate higher responsiveness. Lastly, we examine the effects of organizational structure on the relationship between information sharing and responsiveness. We posit that the degree of centralization will have a positive moderation effect on the aforementioned relationship. The paper then describes the methodology planned to test these hypotheses. We will design a case-based simulation that will incorporate current disaster situations and parameters experienced by Community Preparedness Exercise and Fair (COMPEF), which acts as a broker for the City of Tempe and various humanitarian groups. With the case-based simulation data, we will draw theoretical and managerial implications for the field of humanitarian logistics.

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2013-05

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Efficient routing and resource sharing mechanisms for hybrid optical-wireless access networks

Description

The integration of passive optical networks (PONs) and wireless mesh networks (WMNs) into Fiber-Wireless (FiWi) networks has recently emerged as a promising strategy for

providing flexible network services at relative high transmission rates. This work investigates the effectiveness of localized routing

The integration of passive optical networks (PONs) and wireless mesh networks (WMNs) into Fiber-Wireless (FiWi) networks has recently emerged as a promising strategy for

providing flexible network services at relative high transmission rates. This work investigates the effectiveness of localized routing that prioritizes transmissions over the local gateway to the optical network and avoids wireless packet transmissions in radio zones that do not contain the packet source or destination. Existing routing schemes for FiWi networks consider mainly hop-count and delay metrics over a flat WMN node topology and do not specifically prioritize the local network structure. The combination of clustered and localized routing (CluLoR) performs better in terms of throughput-delay compared to routing schemes that are based on minimum hop-count which do not consider traffic localization. Subsequently, this work also investigates the packet delays when relatively low-rate traffic that has traversed a wireless network is mixed with conventional high-rate PON-only traffic. A range of different FiWi network architectures with different dynamic bandwidth allocation (DBA) mechanisms is considered. The grouping of the optical network units (ONUs) in the double-phase polling (DPP) DBA mechanism in long-range (order of 100~Km) FiWi networks is closely examined, and a novel grouping by cycle length (GCL) strategy that achieves favorable packet delay performance is introduced. At the end, this work proposes a novel backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations (e.g., LTE eNBs) and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateway (S/P-GW). The Sm-GW accommodates flexible number of small cells while reducing the infrastructure requirements at the S-GW of LTE backhaul. In contrast to existing methods, the proposed Sm-GW incorporates the scheduling mechanisms to achieve the network fairness while sharing the resources among all the connected small cells base stations.

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Date Created
2016

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Harm during hospitalizations for heart failure: adverse events as a reliability measure of hospital policies and procedures

Description

For more than twenty years, clinical researchers have been publishing data regarding incidence and risk of adverse events (AEs) incurred during hospitalizations. Hospitals have standard operating policies and procedures (SOPP) to protect patients from AE. The AE specifics (rates, SOPP

For more than twenty years, clinical researchers have been publishing data regarding incidence and risk of adverse events (AEs) incurred during hospitalizations. Hospitals have standard operating policies and procedures (SOPP) to protect patients from AE. The AE specifics (rates, SOPP failures, timing and risk factors) during heart failure (HF) hospitalizations are unknown. There were 1,722 patients discharged with a primary diagnosis of HF from an academic hospital between January 2005 and December 2007. Three hundred eighty-one patients experienced 566 AEs, classified into four categories: medication (43.9%), infection (18.9%), patient care (26.3%), or procedural (10.9%). Three distinct analyses were performed: 1) patient's perspective of SOPP reliability including cumulative distribution and hazard functions of time to AEs; 2) Cox proportional hazards model to determine independent patient-specific risk factors for AEs; and 3) hospital administration's perspective of SOPP reliability through three years of the study including cumulative distribution and hazard functions of time between AEs and moving range statistical process control (SPC) charts for days between failures of each type. This is the first study, to our knowledge, to consider reliability of SOPP from both the patient's and hospital administration's perspective. AE rates in hospitalized patients are similar to other recently published reports and did not improve during the study period. Operations research methodologies will be necessary to improve reliability of care delivered to hospitalized patients.

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2012

Ethernet passive optical network dynamic bandwidth allocation study

Description

Fiber-Wireless (FiWi) network is the future network configuration that uses optical fiber as backbone transmission media and enables wireless network for the end user. Our study focuses on the Dynamic Bandwidth Allocation (DBA) algorithm for EPON upstream transmission. DBA, if

Fiber-Wireless (FiWi) network is the future network configuration that uses optical fiber as backbone transmission media and enables wireless network for the end user. Our study focuses on the Dynamic Bandwidth Allocation (DBA) algorithm for EPON upstream transmission. DBA, if designed properly, can dramatically improve the packet transmission delay and overall bandwidth utilization. With new DBA components coming out in research, a comprehensive study of DBA is conducted in this thesis, adding in Double Phase Polling coupled with novel Limited with Share credits Excess distribution method. By conducting a series simulation of DBAs using different components, we found out that grant sizing has the strongest impact on average packet delay and grant scheduling also has a significant impact on the average packet delay; grant scheduling has the strongest impact on the stability limit or maximum achievable channel utilization. Whereas the grant sizing only has a modest impact on the stability limit; the SPD grant scheduling policy in the Double Phase Polling scheduling framework coupled with Limited with Share credits Excess distribution grant sizing produced both the lowest average packet delay and the highest stability limit.

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2011

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Single machine scheduling: comparison of MIP formulations and heuristics for interfering job sets

Description

This research by studies the computational performance of four different mixed integer programming (MIP) formulations for single machine scheduling problems with varying complexity. These formulations are based on (1) start and completion time variables, (2) time index variables, (3) linear

This research by studies the computational performance of four different mixed integer programming (MIP) formulations for single machine scheduling problems with varying complexity. These formulations are based on (1) start and completion time variables, (2) time index variables, (3) linear ordering variables and (4) assignment and positional date variables. The objective functions that are studied in this paper are total weighted completion time, maximum lateness, number of tardy jobs and total weighted tardiness. Based on the computational results, discussion and recommendations are made on which MIP formulation might work best for these problems. The performances of these formulations very much depend on the objective function, number of jobs and the sum of the processing times of all the jobs. Two sets of inequalities are presented that can be used to improve the performance of the formulation with assignment and positional date variables. Further, this research is extend to single machine bicriteria scheduling problems in which jobs belong to either of two different disjoint sets, each set having its own performance measure. These problems have been referred to as interfering job sets in the scheduling literature and also been called multi-agent scheduling where each agent's objective function is to be minimized. In the first single machine interfering problem (P1), the criteria of minimizing total completion time and number of tardy jobs for the two sets of jobs is studied. A Forward SPT-EDD heuristic is presented that attempts to generate set of non-dominated solutions. The complexity of this specific problem is NP-hard. The computational efficiency of the heuristic is compared against the pseudo-polynomial algorithm proposed by Ng et al. [2006]. In the second single machine interfering job sets problem (P2), the criteria of minimizing total weighted completion time and maximum lateness is studied. This is an established NP-hard problem for which a Forward WSPT-EDD heuristic is presented that attempts to generate set of supported points and the solution quality is compared with MIP formulations. For both of these problems, all jobs are available at time zero and the jobs are not allowed to be preempted.

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2012