1,428 research outputs found
OPTIMIZATION OF TEST/DIAGNOSIS/REWORK LOCATION(S) AND CHARACTERISTICS IN ELECTRONIC SYSTEMS ASSEMBLY
ABSTRACT
Title of Dissertation: OPTIMIZATION OF TEST/DIAGNOSIS/REWORK LOCATION(S) AND CHARACTERISTICS IN ELECTRONIC SYSTEMS ASSEMBLY
Zhen Shi, Doctor of Philosophy, 2004
Dissertation directed by: Associate Professor Peter A. Sandborn
Department of Mechanical Engineering
For electronic systems it is not uncommon for 60% or more of the recurring cost to be associated with testing. Performing tradeoffs associated with where in a process to test and what level of test, diagnosis and rework to perform are key to optimizing the cost and yield of an electronic system's assembly. In this dissertation, a methodology that uses a real-coded genetic algorithm has been developed to minimize the yielded cost of electronic products by optimizing the locations of test, diagnosis and rework operations and their characteristics.
This dissertation presents a test, diagnosis, and rework analysis model for use in electronic systems assembly. The approach includes a model of functional test operations characterized by fault coverage, false positives, and defects introduced in test; in addition, rework and diagnosis operations (diagnostic test) have variable success rates and their own defect introduction mechanisms. The model accommodates multiple rework attempts on a product instance. For use in practical assembly processes, the model has been extended by defining a general form of the relationship between test cost and fault coverage.
The model is applied within a framework for optimizing the location(s) and characteristics (fault coverage/test cost and rework attempts) of Test/Diagnosis/Rework (TDR) operations in a general assembly process. A new search algorithm called Waiting Sequence Search (WSS) is applied to traverse a general process flow to perform the cumulative calculation of a yielded cost objective function. Real-Coded Genetic Algorithms (RCGAs) are used to perform a multi-variable optimization that minimizes yielded cost. Several simple cases are analyzed for validation and general complex process flows are used to demonstrate the applicability of the algorithm. A real multichip module (MCM) manufacturing and assembly process is used to demonstrate that the optimization methodology developed in this dissertation can find test and rework solutions that have lower yielded cost than solutions calculated by manually choosing the test strategies and characteristics. The optimization methodology with Monte Carlo methods included for the process flow under uncertain inputs is also addressed in this dissertation.
It is anticipated that this research will improve the ability of manufacturing engineers to place TDR operations in a process flow. The ability to optimize the TDR operations can also be used as a feedback to a Design for Test (DFT) analysis of the electronic systems showing which portion of the system should be redesigned to accommodate testing for a higher level of fault coverage, and where there is less need for test
Optimal Configuration of Inspection and Rework Stations in a Multistage Flexible Flowline
Inspection and rework are two important issues of quality control. In this research, an N-stage flowline is considered to make decisions on these two issues. When defective items are detected at the inspection station the items are either scrapped or reworked. A reworkable item may be repaired at the regular defect-creating workstation or at a dedicated off-line rework station. Two problems (end-of-line and multistage inspections) are considered here to deal with this situation. The end-of-line inspection (ELI) problem considers an inspection station located at the end of the line while the multistage inspection (MSI) problem deals with multiple in-line inspection stations that partition the flowline into multiple flexible lines. Models for unit cost of production are developed for both problems. The ELI problem is formulated for determining the best decision among alternative policies for dealing with defective items. For an MSI problem a unit cost function is developed for determining the number and locations of in-line inspection stations along with the alternative decisions on each type of defects. Both of the problems are formulated as fractional mixed-integer nonlinear programming (f-MINLP) to minimize the unit cost of production. After several transformations the f-MINLP becomes a mixed-integer linear programming (MILP) problem. A construction heuristic, coined as Inspection Station Assignment (ISA) heuristic is developed to determine a sub-optimal location of inspection and rework stations in order to achieve minimum unit cost of production. A hybrid of Ant-Colony Optimization-based metaheuristic (ACOR) and ISA is devised to efficiently solve large instances of MSI problems. Numerical examples are presented to show the solution procedure of ELI problems with branch and bound (B&B) method. Empirical studies on a production line with large number of workstations are presented to show the quality and efficiency of the solution processes involved in both ELI and MSI problems. Computational results present that the hybrid heuristic ISA+ACOR shows better performance in terms of solution quality and efficiency. These approaches are applicable to many discrete product manufacturing systems including garments industry
Electronic Part Total Cost Of Ownership And Sourcing Decisions For Long Life Cycle Products
The manufacture and support of long life cycle products rely on the availability of suitable parts from competent suppliers which, over long periods of time, leaves parts susceptible to a number of possible long-term supply chain disruptions. Potential supply chain failures can be supplier-related (e.g., bankruptcy, changes in manufacturing process, non-compliance), parts-related (e.g., obsolescence, reliability, design changes), logistical (e.g., transportation mishaps, natural disasters, accidental occurrences) and political/legislative (e.g., trade regulations, embargo, national conflict). Solutions to mitigating the risk of supply chain failure include the strategic formulation of suitable part sourcing strategies. Sourcing strategies refer to the selection of a set of suppliers from which to purchase parts; sourcing strategies include sole, single, dual, second and multi-sourcing. Utilizing various sourcing strategies offer one way of offsetting or avoiding the risk of part unavailability (and its associated penalties) as well as possible benefits from competitive pricing.
Although supply chain risks and sourcing strategies have been extensively studied for high-volume, short life cycle products, the applicability of existing work to long life cycle products is unknown. Existing methods used to study part sourcing decisions in high-volume consumer oriented applications are procurement-centric where cost tradeoffs on the part level focus on part pricing, negotiation practices and purchase volumes. These studies are commonplace for strategic part management for short life cycle products; however, conventional procurement approaches offer only a limited view for parts used in long life cycle products. Procurement-driven decision making provides little to no insight into the accumulation of life cycle cost (attributed to the adoption, use and support of the part), which can be significantly larger than procurement costs in long life cycle products.
This dissertation defines the sourcing constraints imposed by the shortage of suppliers as a part becomes obsolete or is subject to other long-term supply chain disruptions. A life cycle approach is presented to compare the total cost of ownership of introducing and supporting a set of suppliers, for electronic parts in long life cycle products, against the benefit of reduced long-term supply chain disruption risk. The estimation of risk combines the likelihood or probability of long-term supply chain disruptions (throughout the part's procurement and support life within an OEM's product portfolio) with the consequence of the disruption (impact on the part's total cost of ownership) to determine the "expected cost" associated with a particular sourcing strategy. This dissertation focuses on comparing sourcing strategies used in long life cycle systems and provides application-specific insight into the cost benefits of sourcing strategies towards proactively mitigating DMSMS type part obsolescence
A Hierarchical, Fuzzy Inference Approach to Data Filtration and Feature Prioritization in the Connected Manufacturing Enterprise
The current big data landscape is one such that the technology and capability to capture and storage of data has preceded and outpaced the corresponding capability to analyze and interpret it. This has led naturally to the development of elegant and powerful algorithms for data mining, machine learning, and artificial intelligence to harness the potential of the big data environment. A competing reality, however, is that limitations exist in how and to what extent human beings can process complex information. The convergence of these realities is a tension between the technical sophistication or elegance of a solution and its transparency or interpretability by the human data scientist or decision maker. This dissertation, contextualized in the connected manufacturing enterprise, presents an original Fuzzy Approach to Feature Reduction and Prioritization (FAFRAP) approach that is designed to assist the data scientist in filtering and prioritizing data for inclusion in supervised machine learning models. A set of sequential filters reduces the initial set of independent variables, and a fuzzy inference system outputs a crisp numeric value associated with each feature to rank order and prioritize for inclusion in model training. Additionally, the fuzzy inference system outputs a descriptive label to assist in the interpretation of the feature’s usefulness with respect to the problem of interest. Model testing is performed using three publicly available datasets from an online machine learning data repository and later applied to a case study in electronic assembly manufacture. Consistency of model results is experimentally verified using Fisher’s Exact Test, and results of filtered models are compared to results obtained by the unfiltered sets of features using a proposed novel metric of performance-size ratio (PSR)
A Hierarchical Core Reference Ontology for New Technology Insertion Design in Long Life Cycle, Complex Mission Critical Systems
Organizations, including government, commercial and others, face numerous challenges in maintaining and upgrading long life-cycle, complex, mission critical systems. Maintaining and upgrading these systems requires the insertion and integration of new technology to avoid obsolescence of hardware software, and human skills, to improve performance, to maintain and improve security, and to extend useful life. This is particularly true of information technology (IT) intensive systems. The lack of a coherent body of knowledge to organize new technology insertion theory and practice is a significant contributor to this difficulty. This research organized the existing design, technology road mapping, obsolescence, and sustainability literature into an ontology of theory and application as the foundation for a technology design and technology insertion design hierarchical core reference ontology and laid the foundation for body of knowledge that better integrates the new technology insertion problem into the technology design architecture
An improved powertrain attributes development process with the use of design structure matrix
Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, 2004.Includes bibliographical references (p. 131).Automobiles are becoming increasingly complicated and are creating more of a challenge for the engineering teams working on them. This thesis focuses on improving the methods of managing powertrain attributes and the interactions between them. We are concentrating on the particular attributes of Shift Quality, Performance Feel, Driveability, and Trailer Towing. Engineering work to achieve specific attributes is currently handled attribute by attribute and the system is brought together later. This lack of a more holistic view results in a large amount of engineering rework as attributes are balanced. Reducing or eliminating this rework is the goal. A Design Structure Matrix (DSM) was used to document interactions between the powertrain attributes, sub-attributes and design parameters. Research on various reporting formats was done to determine the best method to communicate the interactions. DSM experts were interviewed about the benefits and pitfalls of using a DSM for reference. Several surveys were done to determine engineering's familiarity with various methods of displaying system interactions and their preferences for reporting the interactions. We also compared the interactions to existing CAE capability to determine the current state of attributes management. The DSM showed numerous interactions between powertrain attributes, other vehicle attributes and design parameters. The analysis of existing CAE tools showed a significant percentage of interactions are not currently being modeled. The responses to survey questions on output methods indicated that a DSM, while being an excellent tool for capturing the interactions, might not be the best tool for displaying the interactions to engineers. The surveys revealed that(cont.) engineers are looking for more information than a DSM or any systems interactions model contain, such as probability that an interaction exists, expected direction and levels of the interaction, and quick and simple methods for better understanding of these potential interactions. This desired level of detail highlights the need to share Lessons Learned, develop a corporate knowledge base and develop best practices. A review of the organizational structure and engineering focus indicated that increased focus is needed on powertrain attributes to better match customer expectations. Additionally, organizational structure changes are recommended to increase visibility of powertrain attributes.by Daniel J. Rinkevich [and] Frederick P. Samson.S.M
NASA Tech Briefs, August 2000
Topics include: Simulation/Virtual Reality; Test and Measurement; Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Medical Design
Modeling and analysis of performance of the steering angle sensor development project
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, 2000.Also available online at the MIT Theses Online homepage .Includes bibliographical references (leaf 83).In the highly competitive automotive industry, OEM and tier-I suppliers face the problem of determining costs and creating accurate and rapid schedules for current and future product developments. Successful companies in this industry are those that are able to forecast and meet important deadlines, satisfy performance requirements and reduce costs to keep development within budget. But frequently one or two factors are achieved at the expense of the others. Sometimes, for example, suppliers are able to cut costs, but only at the expense of quality. Or they can increase quality at expense of costs. Both scenarios are of concern, especially when competitors are attempting to capture market share. Engineers and program managers require powerful techniques to have better estimates of completion time versus expenditures. Unfortunately, though, there are not yet such tools available that are capable of incorporating both dimensions of product quality and cost. Moreover, it would be desirable to incorporate product performance with those two dimensions in order to obtain a broad perspective of the entire design. The main goal of this thesis is the investigation, evaluation and application of the research reported in the Ph.D. thesis "Modeling and Analyzing Cost, Schedule, and Performance in Complex System Product Development" (Browning 1998) in two product platforms of Valeo, Electronics. The two product platforms selected for this purpose were the steering angle sensor (SAS) and the ultrasonic park assist sensor (UPAS). The research for this project was conducted at Valeo, Electronics, located in Bietigheim-Bissingen, Germany. First, data were collected concerning development costs, timing and performance of the steering angle sensor. Second, the software was modified and applied to obtain a joint probability distribution of cost and schedule for this platform. Third, the model was tracked and validated. The tracking of the model was performed within the same platform by running the software at various times. The validation of the model consisted of applying the same methodology for the UPAS and other areas of the SAS. Monte Carlo simulation, optimization, design structure matrices, feedback among activities, and concurrency in product development systems, along with three software tools (Visual Basic, Excel and MATLAB) were used extensively in this work. Finally, the model and the results were presented to the company, with recommendations for future applications.by Miguel A. Hurtado.S.M
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