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Your search keyword '"Cai, Xiaoqiang"' showing total 10 results
Start Over Author "Cai, Xiaoqiang" Topic engineering and manufacturing industries
10 results on '"Cai, Xiaoqiang"'

1. Some results on resource constrained scheduling

Author

Zhang, Guochuan, Cai, Xiaoqiang, and Wong, C.K.

Subjects
Production management, Business, Engineering and manufacturing industries
Abstract

We consider a variant of the resource constrained scheduling problem, which originated from a machine scheduling problem. A number of jobs are to be processed on a single machine with a prespecified capacity. Each job has a size and a processing time, and the machine can process a set of jobs simultaneously as long as the total size of the jobs being processed does not exceed the capacity of the machine. The objective is to find a schedule to minimize the total time (i.e., the makespan) to complete all jobs, subject to the machine capacity constraint. For the problem where the machine is completely available at the starting time, we analyze a previously published algorithm and prove that the worst-case ratio of this algorithm is no more than 7/4, which significantly improves the previous result and thus answers an open question about this algorithm. For the problem where the machine is partially available at the beginning, an algorithm is shown to have a worst-case ratio of no more than two. An on-line algorithm is also presented., 1. Introduction In the past four decades, many papers have been published in the literature on scheduling. Most scheduling literature assumes that a machine can handle exactly one job and [...]

Published
2004

2. The value of processing flexibility in multipurpose machines

Author

Vairaktarakis, George L. and Cai, Xiaoqiang

Subjects
Parallel processing -- Analysis, Parallel processing -- Research, Parallel processing, Business, Engineering and manufacturing industries
Abstract

We study a scheduling problem in a multipurpose machine environment where every job can be processed by a subset of the machines operated in parallel, with the objective of minimizing makespan. We develop lower bounds, heuristic algorithms, and a branch-and-bound procedure. We perform an extensive computational experiment to assess how much flexibility is enough to render the multipurpose machine system equally efficient to an equivalent system of parallel identical machines. We find that very small amounts of flexibility appropriately distributed across processors provide nearly the same makespan performance as a system of fully flexible parallel machines., 1. Introduction Consider a system of m parallel identical machines each of which is capable of executing any job and takes the same processing time as any other machine. Minimizing [...]

Published
2003

3. Optimal on-line algorithms for scheduling on parallel batch processing machines

Author

Zhang, Guochuan, Cai, Xiaoqiang, and Wong, C.K.

Subjects
Scheduling (Management) -- Research, Algorithms -- Analysis, Batch processing -- Methods, Algorithm, Business, Engineering and manufacturing industries
Abstract

We consider the problem of scheduling jobs on-line on parallel batch processing machines with dynamic job arrivals to minimize makespan. We are given m identical batch processing machines, each of [...]

Published
2003

5. Scheduling with multiple-job-on-one-processor pattern

Author

Li, Chung-Lun, Cai, Xiaoqiang, and Lee, Chung-Yee

Subjects
Manufacturing processes -- Methods, Heuristic programming -- Usage, Business, Engineering and manufacturing industries
Abstract

Most scheduling literature considers a 'one-job-on-one-processor' pattern, which assumes that a processor processes exactly one job at a time. In this paper we consider a new scheduling problem with a 'multiple-job-on-one-processor' pattern, where several jobs can be processed by a single processor simultaneously, provided that the total size of the jobs being processed does not exceed the capacity of the processor at any point in time. This problem is motivated by the operation of berth allocation, which is to allocate vessels (jobs) to a berth (processor), where the vessels, if small in dimension, may share the berth with some other vessels for loading/unloading the goods. We consider the problem to minimize the makespan of the schedule. The well-known First-Fit Decreasing heuristic is generalized and applied to several variations of the problem, and the worst-case behavior of the generalized heuristics is studied. Worst-case error bounds are obtained for those models. Computational experiments are conducted to test the heuristics. The results suggest that the heuristics are effective in producing near-optimal solutions., 1. Introduction Scheduling models concern how to optimally allocate the limited resource (processors) to tasks (jobs) over time. It is a decision making process that exists in most production systems, [...]

Published
1998

6. Heuristic genetic algorithm for capacitated production planning problems with batch processing and remanufacturing

Author

Li, Yongjian, Chen, Jian, and Cai, Xiaoqiang

Subjects
Algorithms, Algorithm, Business, Business, international, Engineering and manufacturing industries
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ijpe.2004.11.017 Byline: Yongjian Li (a), Jian Chen (a), Xiaoqiang Cai (b) Abstract: In this paper, we analyze a version of the capacitated dynamic lot-sizing problem with substitutions and return products. Both batch manufacturing and batch remanufacturing are considered within the framework of deterministic time-varying demands in a finite time horizon, where the option of emergency procurement/outsourcing subject to a subcontract is also allowed. Setup costs are taken into account when batch manufacturing or batch remanufacturing takes place. We first apply a genetic algorithm to determine all periods requiring setups for batch manufacturing and batch remanufacturing, then develop a dynamic programming approach to provide the optimal solution to determine how many new products are manufactured or return products are remanufactured in each of these periods. The objective is to minimize the total cost, including batch manufacturing, batch remanufacturing, emergency procurement, holding and setup costs. Numerical examples illustrate the effectiveness of the approach. Author Affiliation: (a) School of Economics and Management, Tsinghua University, Beijing 100084 PR China (b) Department of System Engineering and Engineering Management, The Chinese University of HongKong, Shatin N.T., Hong Kong Article History: Received 28 December 2003; Accepted 2 November 2004

Published
2007

7. Heuristic genetic algorithm for capacitated production planning problems with batch processing and remanufacturing

Author

Li, Yongjian, Chen, Jian, and Cai, Xiaoqiang

Subjects
Genetic algorithms -- Usage, Economic lot size -- Management, Batch processing -- Analysis, Remanufacturing -- Analysis, Substitute products -- Forecasts and trends, Company business management, Market trend/market analysis, Business, Business, international, Engineering and manufacturing industries
Abstract

In this paper, we analyze a version of the capacitated dynamic lot-sizing problem with substitutions and return products. Both batch manufacturing and batch remanufacturing are considered within the framework of deterministic time-varying demands in a finite time horizon, where the option of emergency procurement/outsourcing subject to a subcontract is also allowed. Setup costs are taken into account when batch manufacturing or batch remanufacturing takes place. We first apply a genetic algorithm to determine all periods requiring setups for batch manufacturing and batch remanufacturing, then develop a dynamic programming approach to provide the optimal solution to determine how many new products are manufactured or return products are remanufactured in each of these periods. The objective is to minimize the total cost, including batch manufacturing, batch remanufacturing, emergency procurement, holding and setup costs. Numerical examples illustrate the effectiveness of the approach. Keywords: Dynamic lot-sizing; Inventory; Product substitution; Remanufacturing; Genetic algorithms

Published
2007

8. On optimal payment time for a retailer under permitted delay of payment by the wholesaler

Author

Song, Xiping and Cai, Xiaoqiang

Subjects
Wholesale industry -- Analysis, Logistics -- Analysis, Wholesale dealer/distributor, Business, Business, international, Engineering and manufacturing industries
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ijpe.2005.07.002 Byline: Xiping Song, Xiaoqiang Cai Keywords: Perishable products; Wholesaler-retailer supply chains; Optimal payment time; Optimal order quantity Abstract: Jamal et al. [2000. Optimal payment time for a retailer under permitted delay of payment by the wholesaler. International Journal of Production Economics 66, 59-66] study a wholesaler-retailer supply chain where the retailer is given a permissible credit period to pay back the dues without paying any interest to the wholesaler. The problem is modeled as a cost minimization problem with two decision variables: the payment time P of the retailer and the length of the inventory cycle T. While the model represents, in general, an interesting problem, we show in this note that there are a number of nontrivial flaws contained in the development of their model and therefore the solution they derived is not correct. We give the correct model and derive the corresponding optimal solution. Author Affiliation: Department of Systems Engineering & Engineering Management, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Article History: Received 14 January 2004; Accepted 28 July 2005 Article Note: (footnote) [star] This work has been supported in part by the Research Grant Council of Hong Kong under Earmarked Research Grant No. CUHK 4170/03E, and NSFC Research Fund No. 70329001.

Published
2006

9. On optimal payment time for a retailer under permitted delay of payment by the wholesaler

Author

Song, Xiping and Cai, Xiaoqiang

Subjects
Wholesale industry -- Analysis, Retail industry -- Analysis, Payment -- Methods, Wholesale dealer/distributor, Business, Business, international, Engineering and manufacturing industries
Abstract

Jamal et al. [2000. Optimal payment time for a retailer under permitted delay of payment by the wholesaler. International Journal of Production Economics 66, 59-66] study a wholesaler-retailer supply chain where the retailer is given a permissible credit period to pay back the dues without paying any interest to the wholesaler. The problem is modeled as a cost minimization problem with two decision variables: the payment time P of the retailer and the length of the inventory cycle T. While the model represents, in general, an interesting problem, we show in this note that there are a number of nontrivial flaws contained in the development of their model and therefore the solution they derived is not correct. We give the correct model and derive the corresponding optimal solution. Keywords. Perishable products; Wholesaler-retailer supply chains; Optimal payment time; Optimal order quantity

Published
2006

10. Scheduling one and two-processor tasks on two parallel processors

Author

LEE, CHUNG-YEE and CAI, XIAOQIANG

Subjects
Business, Engineering and manufacturing industries
Abstract

CHUNG-YEE LEE [1] XIAOQIANG CAI [2] In this paper we study a two-processor scheduling problem where some tasks need to be processed by one processor, while the others have to [...]

Published
1999

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