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Innovation in Manufacturing Systems and Technology (IMST)

Mostrando recursos 1 - 20 de 108

  1. Modeling and Analysis of Re-entrant Production Systems

    Jang, Young Jae; Gershwin, Stanley B.
    This paper presents a model and analysis of a re-entrant production line with finite buffers and unreliable machines. Semiconductor device and liquid crystal display (LCD) fabrication processes are characterized as a re-entrant process, in which a similar sequence of processing step is repeated several times. This re-entrant behavior of material flow with the stochastic nature of the system caused by machine failures or demand changes makes the system difficult predict and analyze. The decomposition method analyzes the behavior of the manufacturing systems by decomposing a long transfer line into small analytically tractable components, called two-machine line building blocks. Existing decomposition...

  2. Generation of Dielectrophoretic Force under Uniform Electric Field

    Kua, C.H.; Yang, C.; Goh, S.; Isabel, R.; Youcef-Toumi, Kamal; Lam, Yee Cheong
    Effective dipole moment method has been widely accepted as the de facto technique in predicting the dielectrophoretic force due to the non-uniform electric field. In this method, a finite-particle is modeled as an equivalent point-dipole that would induce a same electric field under the external electric field. This approach is only valid when the particle size is significantly smaller than the characteristic length of interest. This assumption is often violated in a microfluidic device, where the thickness or width of the microchannel can be as small as the particle. It is shown in this numerical study that when the dimensions...

  3. Setting Real Time WIP Levels in Production Lines

    Yang, R.L.; Subramaniam, Velusamy; Gershwin, Stanley B.
    A new algorithm is developed for setting WIP level in production lines. It is a pull policy that determines when to authorize a job to be processed. Dynamic information in the system such as machine failures and repairs, and demand variations are taken into consideration to provide an efficient method to dynamically determine the WIP level. Two types of production lines are examined in this paper. The first is production lines which have few random interruptions and the second production line is exposed to frequent interruptions. Experiment results from these two types of production lines illustrate that the new algorithm...

  4. Performance of a Serial-Batch Processor System with Incompatible Job Families under Simple Control Policies

    Tajan, John Benedict Cheng; Appa Iyer, Sivakumar; Gershwin, Stanley B.
    A typical example of a batch processor is the diffusion furnace used in wafer fabrication facilities (otherwise known as wafer fabs). In diffusion, silicon wafers are placed inside the furnace, and dopant is flown through the wafers via nitrogen gas. The higher the temperature, the faster the dopant penetrates the wafer surface. Then, a thin layer of silicon dioxide is grown, to help the dopant diffuse into the silicon. This operation can take 10 hours or more to finish processing, as compared to one or two hours for other wafer fab operations, according to Uzsoy [8]. Diffusion furnaces typically can...

  5. Multi-Item Single-Vendor-Single-Buyer Problem with Consideration of Transportation Quantity Discount

    Wang, Ye-Xin; Bhatnagar, Rohit; Graves, Stephen C.
    This paper deals with the problem of shipping multiple commodities from a single vendor to a single buyer. Each commodity is assumed to be constantly consumed at the buyer, and periodically replenished from the vendor. Furthermore, these replenishments are restricted to happen at discrete time instants, e.g., a certain time of the day or a certain day of the week. At any such time instant, transportation cost depends on the shipment quantity according to certain discount scheme. Specifically, we consider two transportation quantity discount schemes: LTL (less-than-truckload) incremental discount and TL (truckload) discount. For each case, we develop MIP (mixed...

  6. Modeling and Analysis of Manufacturing Systems with Multiple-Loop Structures

    Zhang, Zhenyu; Gershwin, Stanley B.
    Kanban and Constant Work-In-Process (CONWIP) control methods are designed to impose tight controls over inventory, while providing a satisfactory production rate. This paper generalizes systems with kanban or CONWIP control as assembly/disassembly networks with multiple-loop structures. We present a stochastic mathematical model which integrates the information control flows into material flows. Graph theory is used to analyze the multiple-loop structures. An efficient analytical algorithm is developed for evaluating the expected production rate and inventory levels. The performance of the algorithm is reported in terms of accuracy, reliability and speed.

  7. The Complexity of Safety Stock Placement in General-Network Supply Chains

    Lesnaia, Ekaterina; Vasilescu, Iuliu; Graves, Stephen C.
    We consider the optimization problem of safety stock placement in a supply chain, as formulated in [1]. We prove that this problem is NP-Hard for supply chains modeled as general acyclic networks. Thus, we do not expect to find a polynomial-time algorithm for safety stock placement for a general-network supply chain.

  8. Risk Aversion in Inventory Management

    Chen, Xin; Sim, Melvyn; Simchi-Levi, David; Sun, Peng
    Traditional inventory models focus on risk-neutral decision makers, i.e., characterizing replenishment strategies that maximize expected total profit, or equivalently, minimize expected total cost over a planning horizon. In this paper, we propose a framework for incorporating risk aversion in multi-period inventory models as well as multi-period models that coordinate inventory and pricing strategies. In each case, we characterize the optimal policy for various measures of risk that have been commonly used in the finance literature. In particular, we show that the structure of the optimal policy for a decision maker with exponential utility functions is almost identical to the structure...

  9. Modeling and Analysis of Two-Part Type Manufacturing Systems

    Jang, Young Jae; Gershwin, Stanley B.
    This paper presents a model and analysis of a synchronous tandem flow line that produces different part types on unreliable machines. The machines operate according to a static priority rule, operating on the highest priority part whenever possible, and operating on lower priority parts only when unable to produce those with higher priorities. We develop a new decomposition method to analyze the behavior of the manufacturing system by decomposing the long production line into small analytically tractable components. As a first step in modeling a production line with more than one part type, we restrict ourselves to the case where...

  10. UV Embossed Plastic Chip for Protein Separation and Identification

    Guo, Xun; Chan-Park, Mary Bee-Eng; Yoon, Soon Fatt; Chun, Jung-Hoon; Hua, Lin; Sze, Newman
    This report demonstrates a UV-embossed polymeric chip for protein separation and identification by Capillary Isoelectric Focusing (CIEF) and Matrix Assisted Laser Desportion/Ionization Mass Spectrometry (MALDI-MS). The polymeric chip has been fabricated by UV-embossing technique with high throughput; the issues in the fabrication have been addressed. In order to achieve high sensitivity of mass detection, five different types of UV curable polymer have been used as sample support to perform protein ionization in Mass Spectrometry (MS); the best results is compared to PMMA, which was the commonly used plastic chip for biomolecular separation. Experimental results show that signal from polyester is...

  11. A Two-level Prediction Model for Deep Reactive Ion Etch (DRIE)

    Taylor, Hayden K.; Sun, Hongwei; Hill, Tyrone F.; Schmidt, Martin A.; Boning, Duane S.
    We contribute a quantitative and systematic model to capture etch non-uniformity in deep reactive ion etch of microelectromechanical systems (MEMS) devices. Deep reactive ion etch is commonly used in MEMS fabrication where high-aspect ratio features are to be produced in silicon. It is typical for many supposedly identical devices, perhaps of diameter 10 mm, to be etched simultaneously into one silicon wafer of diameter 150 mm. Etch non-uniformity depends on uneven distributions of ion and neutral species at the wafer level, and on local consumption of those species at the device, or die, level. An ion–neutral synergism model is constructed...

  12. Temporary and Permanent Buyout Prices in Online Auctions

    Gupta, Shobhit; Gallien, Jérémie
    Increasingly used in online auctions, buyout prices allow bidders to instantly purchase the item listed. We distinguish two types: a temporary buyout option disappears if a bid above the reserve price is made; a permanent one remains throughout the auction or until it is exercised. In a model featuring time-sensitive bidders with uniform valuations and Poisson arrivals but endogenous bidding times, we focus on finding temporary and permanent buyout prices maximizing the seller's discounted revenue, and examine the relative benefit of using each type of option in various environments. We characterize equilibrium bidder strategies in both cases and then solve...

  13. Static Pricing for a Network Service Provider

    Caro, Felipe; Simchi-Levi, David
    This article studies the static pricing problem of a network service provider who has a fixed capacity and faces different types of customers (classes). Each type of customers can have its own capacity constraint but it is assumed that all classes have the same resource requirement. The provider must decide a static price for each class. The customer types are characterized by their arrival process, with a price-dependant arrival rate, and the random time they remain in the system. Many real-life situations could fit in this framework, for example an Internet provider or a call center, but originally this problem...

  14. Room-temperature continuous-wave operation of GaInNAs/GaAs quantum dot laser with GaAsN barrier grown by solid source molecular beam epitaxy

    Sun, Z. Z.; Yoon, Soon Fatt; Yew, K. C.; Bo, B. X.; Yan, Du An; Tung, Chih-Hang
    We present the results of GaInNAs/GaAs quantum dot structures with GaAsN barrier layers grown by solid source molecular beam epitaxy. Extension of the emission wavelength of GaInNAs quantum dots by ~170nm was observed in samples with GaAsN barriers in place of GaAs. However, optimization of the GaAsN barrier layer thickness is necessary to avoid degradation in luminescence intensity and structural property of the GaInNAs dots. Lasers with GaInNAs quantum dots as active layer were fabricated and room-temperature continuous-wave lasing was observed for the first time. Lasing occurs via the ground state at ~1.2μm, with threshold current density of 2.1kA/cm[superscript 2]...

  15. Review of bio-particle manipulation using dielectrophoresis

    Kua, C. H.; Lam, Yee Cheong; Yang, C.; Youcef-Toumi, Kamal
    During the last decade, large and costly instruments are being replaced by system based on microfluidic devices. Microfluidic devices hold the promise of combining a small analytical laboratory onto a chip-sized substrate to identify, immobilize, separate, and purify cells, bio-molecules, toxins, and other chemical and biological materials. Compared to conventional instruments, microfluidic devices would perform these tasks faster with higher sensitivity and efficiency, and greater affordability. Dielectrophoresis is one of the enabling technologies for these devices. It exploits the differences in particle dielectric properties to allow manipulation and characterization of particles suspended in a fluidic medium. Particles can be trapped...

  16. Process Variability in Micro-Embossing

    Hardt, David E.; Ganesan, Bala; Dirckx, Matthew; Shoji, Grant; Thaker, Kunal; Qi, Wang
    A promising technique for the large-scale manufacture of micro-fluidic devices and photonic devices is hot embossing of polymers such as PMMA. Micro-embossing is a deformation process where the workpiece material is heated to permit easier material flow and then forced over a planar patterned tool. While there has been considerable, attention paid to process feasibility very little effort has been put into production issues such as process capability and eventual process control. In this paper, we present initial studies aimed at identifying the origins and magnitude of variability for embossing features at the micron scale in PMMA. Test parts with...

  17. Plasma polymerization of C[subscript 4]F[subscript 8] thin film on high aspect ratio silicon molds

    Yeo, L. P.; Poh, S. L.; Lam, Yee Cheong; Chan-Park, Mary Bee-Eng
    High aspect ratio polymeric micro-patterns are ubiquitous in many fields ranging from sensors, actuators, optics, fluidics and medical. Second generation PDMS molds are replicated against first generation silicon molds created by deep reactive ion etching. In order to ensure successful demolding, the silicon molds are coated with a thin layer of C[subscript 4]F[subscript 8] plasma polymer to reduce the adhesion force. Peel force and demolding status are used to determine if delamination is successful. Response surface method is employed to provide insights on how changes in coil power, passivating time and gas flow conditions affect plasma polymerization of C[subscript 4]F[subscript...

  18. Planning and Scheduling Decisions in Supply Chains with Multiple Supply Modes: An Integrated Approach

    Bhatnagar, Rohit; Peeyush, Mehta
    We address the problem of jointly determining shipment planning and scheduling decisions with the presence of multiple shipment modes. We consider long lead time, less expensive sea shipment mode, and short lead time but expensive air shipment modes. Existing research on multiple shipment modes largely address the short term scheduling decisions only. Motivated by an industrial problem where planning decisions are independent of the scheduling decisions, we investigate the benefits of integrating the two sets of decisions. We develop sequence of mathematical models to address the planning and scheduling decisions. Preliminary computational results indicate improved performance of the integrated approach...

  19. Performance-Driven Microfabrication-Oriented Methodology for MEMS Conceptual Design with Application in Microfluidic Device Design

    Deng, Y.-M.; Lu, Wen Feng
    Performance and manufacturability are two important issues that must be taken into account during MEMS design. Existing MEMS design models or systems follow a process-driven design paradigm, that is, design starts from the specification of process sequence or the customization of foundry-ready process template. There has been essentially no methodology or model that supports generic, high-level design synthesis for MEMS conceptual design. As a result, there lacks a basis for specifying the initial process sequences. To address this problem, this paper proposes a performance-driven, microfabrication-oriented methodology for MEMS conceptual design. A unified behaviour representation method is proposed which incorporates information...

  20. Optimizing the Dynamic Distribution of Data-stream for High Speed Communications

    Zhao, Z.W.; Chen, I-Ming
    The performances of high-speed network communications frequently rest with the distribution of data-stream. In this paper, a dynamic data-stream balancing architecture based on link information is introduced and discussed firstly. Then the algorithms for simultaneously acquiring the passing nodes and links of a path between any two source-destination nodes rapidly, as well as a dynamic data-stream distribution planning are proposed. Some related topics such as data fragment disposal, fair service, etc. are further studied and discussed. Besides, the performance and efficiency of proposed algorithms, especially for fair service and convergence, are evaluated through a demonstration with regard to the rate...

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