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Scheduling Policy (scheduling + policy)
Selected AbstractsParallel bandwidth characteristics calculations for thin avalanche photodiodes on a SGI Origin 2000 supercomputerCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2004Yi Pan Abstract An important factor for high-speed optical communication is the availability of ultrafast and low-noise photodetectors. Among the semiconductor photodetectors that are commonly used in today's long-haul and metro-area fiber-optic systems, avalanche photodiodes (APDs) are often preferred over p - i - n photodiodes due to their internal gain, which significantly improves the receiver sensitivity and alleviates the need for optical pre-amplification. Unfortunately, the random nature of the very process of carrier impact ionization, which generates the gain, is inherently noisy and results in fluctuations not only in the gain but also in the time response. Recently, a theory characterizing the autocorrelation function of APDs has been developed by us which incorporates the dead-space effect, an effect that is very significant in thin, high-performance APDs. The research extends the time-domain analysis of the dead-space multiplication model to compute the autocorrelation function of the APD impulse response. However, the computation requires a large amount of memory space and is very time consuming. In this research, we describe our experiences in parallelizing the code in MPI and OpenMP using CAPTools. Several array partitioning schemes and scheduling policies are implemented and tested. Our results show that the code is scalable up to 64 processors on a SGI Origin 2000 machine and has small average errors. Copyright © 2004 John Wiley & Sons, Ltd. [source] The Value of Production Schedule Integration in Supply ChainsDECISION SCIENCES, Issue 4 2001Lee Krajewski Abstract This study explores the value of integrated production schedules for reducing the negative effects of schedule revisions in supply chains involving buyer and supplier firms. A stochastic cost model is developed to evaluate the total supply chain cost with integrated purchasing and scheduling policies. The model minimizes the costs associated with assembly rate adjustment, safety stock, and schedule changes for all supply chain members. Through experimentation, the paper examines the impact of several environmental factors on the value of schedule integration. This study finds that schedule integration can lead to overall cost savings in a supply chain, but some firms may have to absorb costs in excess of those they would incur with independent scheduling. Environments with high inventory holding costs and long supplier lead times may not find it beneficial to adopt an integrated schedule. Forecast effectiveness plays a critical role in realizing the benefits of schedule integration. The paper concludes with suggestions for future research. [source] Optimizing Service Attributes: The Seller's Utility Problem,DECISION SCIENCES, Issue 2 2001Fred F. Easton Abstract Service designers predict market share and sales for their new designs by estimating consumer utilities. The service's technical features (for example, overnight parcel delivery), its price, and the nature of consumer interactions with the service delivery system influence those utilities. Price and the service's technical features are usually quite objective and readily ascertained by the consumer. However, consumer perceptions about their interactions with the service delivery system are usually far more subjective. Furthermore, service designers can only hope to influence those perceptions indirectly through their decisions about nonlinear processes such as employee recruiting, training, and scheduling policies. Like the service's technical features, these process choices affect quality perceptions, market share, revenues, costs, and profits. We propose a heuristic for the NP-hard service design problem that integrates realistic service delivery cost models with conjoint analysis. The resulting seller's utility function links expected profits to the intensity of a service's influential attributes and also reveals an ideal setting or level for each service attribute. In tests with simulated service design problems, our proposed configurations compare quite favorably with the designs suggested by other normative service design heuristics. [source] Stochastic scheduling problem with varying weight for each jobASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Manzhan Gu Abstract This paper studies the preemptive stochastic online scheduling problem, which is a simple combination of online and stochastic scheduling. The processing times of jobs are assumed to be subject to independent probability distributions, and we assume that jobs arrive overtime, which means there is no knowledge about the jobs that arrive in the future. We particularly consider the preemptive setting where a job is allowed to be interrupted during its processing. The weight (holding cost ratio) associated with each job may change during its processing, and the objective is to minimize the expected value of total holding cost for all jobs. For the single and m identical machine problems, we propose scheduling policies, SPGS [semi-preemptive Gittins Index Priority Policy (GIPP) on single machine] and SPGI (semi-preemptive GIPP on identical machines), respectively, both of which are proved to be constant-factor approximation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Combined fair packet scheduling policy and multi-class adaptive CAC scheme for QoS provisioning in multimedia cellular networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2006Tarek Bejaoui Abstract In this paper, we propose a combined multi-class adaptive connection admission control algorithm and a new fair packet scheduling policy, based on an enhanced weighted fair queuing algorithm. It takes into account a realistic behaviour of traffic while considering the spatial variation of the system characterizing both the user mobility and the signal propagation impairments due to the surrounding effects. The proposed allocation scheme provides enhanced traffic performance in heterogeneous environments and achieves a good level of capacity gain. The new adaptive quality of service (QoS) oriented connection admission control (CAC) function is proposed to meet the rapidly increasing demand for providing multimedia services with diversified quality requirements. It decides whether the connection request is to be admitted into the system, on the basis of the generated interference level and the waiting time before access. This CAC scheme, based on service class differentiation, aims at maximizing the use of available radio resource and meeting the QoS requirement of higher priority users as much as possible while maintaining the minimum requirements of lower priority users, especially when the system suffers from congestion. The results indicate that significantly increased traffic performance can be achieved in comparison with other conventional investigated policies. Copyright © 2006 John Wiley & Sons, Ltd. [source] Dynamic scheduling of network resources with advance reservations in optical gridsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2008Savera Tanwir Advance reservation of lightpaths in grid environments is necessary to guarantee QoS and reliability. In this paper, we have evaluated and compared several algorithms for dynamic scheduling of lightpaths using a flexible advance reservation model. The main aim is to find the best scheduling policy for a grid network resource manager that improves network utilization and minimizes blocking. The scheduling of lightpaths involves both routing and wavelength assignment. Our simulation results show that minimum-cost adaptive routing where link costs are determined by the current and future usage of the link provides the minimum blocking. For wavelength assignment, we have used a scheme that reduces fragmentation by minimizing unused gaps. We have also analyzed approaches for failure recovery and resource optimization. Copyright © 2008 John Wiley & Sons, Ltd. [source] Economic Lot Scheduling Problem with ReturnsPRODUCTION AND OPERATIONS MANAGEMENT, Issue 4 2006Ou Tang Motivated by a case study of a company that produces car parts, we study the multi-product economic lot scheduling problem for a hybrid production line with manufacturing of new products and remanufacturing of returned products. For this economic lot scheduling problem with returns (ELSPR), we consider policies with a common cycle time for all products, and with one manufacturing lot and one remanufacturing lot for each product during a cycle. For a given cycle time, the problem is formulated as a mixed integer linear programming (MIP) problem, which provides the basis for an exact solution. The application of this model for one of the core products of the case study company indicates a 16% reduction in cost compared to the current lot scheduling policy. [source] Antibiotic prophylaxis in elective colorectal surgeryANZ JOURNAL OF SURGERY, Issue 4 2002Yunus A. Gul Background: Antibiotics are often administered in elective colorectal surgery to prevent wound infection. The tendency for surgeons to prolong the administration of prophylactic antibiotic therapy in the postoperative period is a well-known fact. The aim of this study was to elucidate the pattern of prophylactic antibiotic utilization in elective colorectal surgery and to determine if evidence-based medicine is employed in relation to this practice. Methods: A cross-sectional study encompassing general surgeons performing elective colorectal surgery was performed. Questionnaires were distributed to 144 surgeons (national, academic and private health care). Questions pertaining to the type, timing and duration of antibiotic administration were asked. The prevalence of wound infection audit rate and whether or not there were specific guidelines related to antibiotic administration were also determined. Results: The response rate obtained was 67% (n = 96). Although evidence from the current medical literature and recommended national guidelines support the use of single-dose prophylactic antibiotics, 72% of the respondents used more than a single dose. Forty surgeons (42%) claimed that their prescribing practice was supported by the medical literature, 31 respondents (32%) based their practice on hospital guidelines and personal preference was cited as a reason by 21 surgeons (22%). The remaining four respondents (4%) used a similar scheduling policy to that practiced by their colleagues in relation to antibiotic administration. There was no significant difference in antibiotic dose scheduling between national, private and university academic institutions (P = 0.85). Conclusions: These results suggest that a significant proportion of surgeons administer excessive and unnecessary doses of antibiotics in elective colorectal surgery. Further studies are required to uncover the reasons but lack of appropriate guidelines and failure to exercise evidence-based medicine are major factors that account for this practice. [source] | |||||||||||||