11,626 research outputs found
Coordination in a single-retailer two-supplier supply chain under random demand and random supply with disruption
No full textThis paper studies the coordination issue of a supply chain consisting of one retailer and two suppliers, a main supplier and a backup supplier. The main supplier’s yield is subject to disruption and the retailer faces a random demand. We determine the retailer’s optimal ordering policy and the main supplier’s production quantity that maximize expected profit of the centralized supply chain. We also analyze the decentralized scenario, and a combination of overproduction risk sharing and buy-back contracts with a side payment from/to the backup supplier is provided to coordinate the supply chain. Numerical examples are given to gain some qualitative insights.Fei Hu, Cheng-Chew Lim, Zudi Lu, and Xiaochen Su
Shape-shifting honeycomb metamaterials with thermally-adaptive Poisson’s ratio signs (Draft 1)
No full textO-Type and X-Type rectangular-cell metamaterial honeycombs with computed thermal strains, coefficients of thermal expansions (CTE) and Poisson's ratio
Development of two matheuristics for production-inventory-distribution routing problem / Dicky Lim Teik Kyee
No full textProduction, inventory and distribution are amongst the most important components of a supply chain network. Integrating production, inventory and distribution decisions is a challenging problem for manufacturers trying to optimize their supply chain. In general, the problem of optimally coordinating production, inventory and transportation is called the production-inventory-distribution routing problem (PIDRP). The PIDRP model considered in this study includes a finite planning horizon, a single production facility, a set of customers with deterministic and time-varying demand, and a fleet of homogeneous capacitated vehicles. The aim of solving the model is to construct a production plan and delivery schedule which minimizes the overall costs while fulfilling customers’ demand over the planning horizon. We propose an optimization algorithm designed by the interpolation of metaheuristics and mathematical programming techniques, known as MatHeuristics algorithm, to solve the model. In this study, we develop two different two-phase approaches within a MatHeuristic framework, namely MatHeuristic1 and MatHeuristic2. In MatHeuristic1, Phase 1 solves a mixed integer programming (MIP) model which includes all the constraints in the original model except the routing aspects. The routing constraints are replaced by an approximated routing cost in the objective function. A variable neighborhood search (VNS) is proposed in Phase 2. The VNS is employed to improve the solution and it incorporates some aspects of Tabu search to escape from local optima. Whilst in MatHeuristic2, we adopt a slightly different approach. The algorithm starts with the pre-processing stage where the routes are determined to act as input to the MIP in Phase 1. Phase 2 uses VNS and we utilize both phases in an interactive manner. The models in both approaches are solved by using Concert Technology of CPLEX 12.5 Optimizers with Microsoft Visual C++ 2010. Both algorithms are tested on a set of 90 benchmark instances with 50, 100 and 200 customers and 20 periods and the results are competitive when compared to the Memetic Algorithm with Population Management (MA|PM), Reactive Tabu Search (RTS) and Scatter Search (SS). MatHeuristic1 performs well in large instances when compared to other metaheuristics but MatHeuristic2 performs well in smaller cases
Tracking mobile robot in indoor wireless sensor networks
No full textThis work addresses the problem of tracking mobile robots in indoor wireless sensor networks (WSNs). Our approach is based on a localization scheme with RSSI (received signal strength indication) which is used widely in WSN. The developed tracking system is designed for continuous estimation of the robot’s trajectory. A WSN, which is composed of many very simple and cheap wireless sensor nodes, is deployed at a specific region of interest. The wireless sensor nodes collect RSSI information sent by mobile robots. A range-based data fusion scheme is used to estimate the robot’s trajectory. Moreover, a Kalman filter is designed to improve tracking accuracy. Experiments are provided to assess the performance of the proposed scheme.Liping Zhang, Cheng-Chew Lim, Yiping Chen, and Hamid Reza Karim
Oreochromis aureus
No full textOreochromis aureus (Steindachner) (AF) References. Welcomme, 1988; Lim & Ng, 1990; Ng et al., 1993; Lever, 1996; Ng & Lim, 1997b; Jaafar et al., 2012. Distribution. Not known. Remarks. This species is regarded as an escapee from aquaculture (Ng & Lim, 1997b).Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 179, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/534398
Fig. 59. Pterygoplichthys joselimaianus, 270 in The non-native freshwater fishes of Singapore: an annotated compilation
No full textFig. 59. Pterygoplichthys joselimaianus, 270 mm SL, Pangsua Pond (dorsal, lateral, and ventral views).Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 168, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/534398
Fig. 115. Trichogaster lalius, 43.1 in The non-native freshwater fishes of Singapore: an annotated compilation
No full textFig. 115. Trichogaster lalius, 43.1 mm SL male, trade material.Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 184, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/534398
Fig. 14. Barbonymus gonionotus, 140.0 in The non-native freshwater fishes of Singapore: an annotated compilation
No full textFig. 14. Barbonymus gonionotus, 140.0 mm SL, trade material (specimen with aberrant body scale pattern).Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 157, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/534398
Fig. 106. Red Tilapia, 132.0 in The non-native freshwater fishes of Singapore: an annotated compilation
No full textFig. 106. Red Tilapia, 132.0 mm SL, Pangsua Pond.Published as part of Hui, Tan Heok, Peng, Kelvin Lim Kok, Huan, Liew Jia, Wei, Low Bi, Hing, Rayson Lim Bock, Beng, Jeffrey Kwik Teik & Yeo, Darren C. J., 2020, The non-native freshwater fishes of Singapore: an annotated compilation, pp. 150-195 in Raffles Bulletin of Zoology 68 on page 182, DOI: 10.26107/RBZ-2020-0016, http://zenodo.org/record/534398
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