https://hdl.handle.net/1721.1/35733 2026-04-04T15:44:51Z 2026-04-04T15:44:51Z Chhaochharia, Pallav Graves, Stephen C. https://hdl.handle.net/1721.1/35826 2019-04-10T09:58:52Z 2007-01-01T00:00:00Z

Performance Analysis of Order Fulfillment for Low Demand Items in E-tailing Chhaochharia, Pallav; Graves, Stephen C. We study inventory allocation and order fulfillment policies among warehouses for low-demand SKUs at an online retailer. A large e-tailer strategically stocks inventory for SKUs with low demand. The motivations are to provide a wide range of selections and faster customer fulfillment service. We assume the e-tailer has the technological capability to manage and control the inventory globally: all warehouses act as one to serve the global demand simultaneously. The e-tailer will utilize its entire inventory, regardless of location, to serve demand. Thus, given the global demand and an order fulfillment policy, there are trade-offs involving inventory holding costs, transshipment costs, and backordering costs in determining the optimal system inventory level and allocation of inventory to warehouses. For the case of Poisson demand and constant lead time, we develop methods to approximate the key system performance metrics like transshipment, backorders and average system inventory. We then use these results to develop guidelines for inventory stocking and order fulfillment policies for online retailers.

2007-01-01T00:00:00Z Kua, C.H. Lam, Yee Cheong Rodriguez, I. Youcef-Toumi, Kamal Yang, C. https://hdl.handle.net/1721.1/35815 2019-04-12T08:35:43Z 2007-01-01T00:00:00Z

Particle Transportation Using Programmable Electrode Arrays Kua, C.H.; Lam, Yee Cheong; Rodriguez, I.; Youcef-Toumi, Kamal; Yang, C. This study presents a technique to manipulate particles in microchannels using arrays of individually excitable electrodes. These electrodes were energized sequentially to form a non-uniform electric field that moved along the microchannel. The non-uniform electric field caused dielectrophoresis to make polarized particles move. This technique was demonstrated using viable yeast cells in a suspending medium with different conductivities. The viable yeast cells experienced positive dielectrophoresis and negative dielectrophoresis in medium conductivity of 21.5 μS/cm and 966 μS/cm respectively. The experimental results indicate that the cells can be transported in either condition using the proposed technique.

2007-01-01T00:00:00Z Loke, Y.W. Tor, Shu Beng Chun, Jung-Hoon Loh, N.H. Hardt, David E. https://hdl.handle.net/1721.1/35813 2019-04-12T08:35:10Z 2007-01-01T00:00:00Z

Micro Injection-Molding of Cyclic Olefin Copolymer Using Metallic Glass Insert Loke, Y.W.; Tor, Shu Beng; Chun, Jung-Hoon; Loh, N.H.; Hardt, David E. There is shift in trend towards the use of high quality polymers as the base material in manufacturing microfluidic chips. In this paper, an amorphous metallic alloy mold insert was used in a micro injection-molding process to fabricate microfluidic features onto cyclic-olefin-copolymer (COC) material. The insert and fabricated samples were compared in terms of the geometry and surface roughness attained. Findings indicate that replication, in general, was possible but the microfeatures formed had significant flashing and tearing at the edges.

2007-01-01T00:00:00Z Fu, G. Reading, I. Li, S.G. Chaturvedi, P. Tor, Shu Beng Yoon, Soon Fatt Fang, Z.P. Youcef-Toumi, Kamal https://hdl.handle.net/1721.1/35811 2019-04-09T16:44:50Z 2007-01-01T00:00:00Z

Investigation of the Dimensional Variation of Microstructures Through the μMIM Process Fu, G.; Reading, I.; Li, S.G.; Chaturvedi, P.; Tor, Shu Beng; Yoon, Soon Fatt; Fang, Z.P.; Youcef-Toumi, Kamal The mass production of components with dimensions in the micron and sub-micron range is anticipated to be one of the leading technology areas for the present century and to be of high market potential. Micro metal injection molding (μMIM) has the potential to be an important contributor to this industry as it can produce precise metallic microstructures in large quantities at a relatively low production cost. The μMIM process is a miniaturization of metal injection molding (MIM) methods. The process comprises of four main steps: mixing, injection molding, debinding and sintering. A metallic powder is mixed with a binder system to form the feedstock. The feedstock is then injection molded into the required shape and the binder removed via thermal or other means. The final microstructures are obtained by sintering the remaining powder in a controlled environment. In this work, the dimensional variation of the microstructures, in particular the warpage, roughness and volume variation, at each stage of the μMIM process was quantified and compared. The results of a preliminary study of the sensitivity of warpage of the microstructures to the packing pressure are also reported.

2007-01-01T00:00:00Z Tor, Shu Beng Loh, N.H. Fu, G. Tay, B.Y. https://hdl.handle.net/1721.1/35810 2019-04-12T08:35:09Z 2007-01-01T00:00:00Z

Experimental Study on the Demolding Force in Micro Metal Injection Molding Tor, Shu Beng; Loh, N.H.; Fu, G.; Tay, B.Y. In this paper experimental study on the demolding force needed to eject micro structures in Micro Metal Injection Molding (μMIM) is conducted. Injection molding is done on a variotherm mold mounted on a Battenfeld injection molding machine and demolding force measurement is done on an Instron tensile testing machine. Green part is a round disc of φ16 mm and thickness 1.5 mm with an array of φ100 μm × height 200 μm micro structures at the center. The experimental results are in good accordance with the previous analysis results.

2007-01-01T00:00:00Z Tajan, John Benedict Cheng Sivakumar, Appa Iyer Gershwin, Stanley B. https://hdl.handle.net/1721.1/35809 2019-04-10T09:58:41Z 2007-01-01T00:00:00Z

Control of Job Arrivals with Processing Time Windows into Batch Processor Buffer Tajan, John Benedict Cheng; Sivakumar, Appa Iyer; Gershwin, Stanley B. Consider a two-stage manufacturing system composed of a batch processor and its upstream feeder processor. Jobs exit the feeder processor and join a queue in front of the batch processor, where they wait to be processed. The batch processor has a finite capacity Q, and the processing time is independent of the number of jobs loaded into the batch processor. In certain manufacturing systems (including semiconductor wafer fabrication), a processing time window exists from the time the job exits the feeder processor till the time it enters the batch processor. If the batch processor has not started processing a job within the job’s processing time window, the job cannot proceed without undergoing rework or validation by process engineers. We generalize this scenario by assigning a reward R for each successfully processed job by the feeder processor, and a cost C for each job that exceeds its processing time window without being processed by the batch processor. We examine a problem where the feeder processor has a deterministic processing time and the batch processor has stochastic processing time, and determine that the optimal control policy at the feeder processor is insensitive to whether the batch processor is under no-idling or full-batch policy.

2007-01-01T00:00:00Z