The impact of non-bottleneck variation in a manufacturing cell

Protective capacity is the 'extra' capacity placed at non-bottleneck resources to absorb random disruptions in planned levels of performance so that the bottleneck resource continues to be effectively utilized. A full factorial experiment with a simulation model was conducted to explore issues associated with the quantity and location of processing variance in a five-station manufacturing cell. The cell's performance was measured using both mean flow time ( MFT ) and bottleneck shiftiness ( SHIFT ) for 3 patterns of variance for the non-bottlenecks at 5 different levels of variation. In order to investigate the importance of the quantity of added capacity on the variation both a low level of protective capacity (10%) and a high level (50%) were considered. The results indicate that having the higher variation work centres close to the bottleneck provides reduced MFT and SHIFT . The performance measures improved at both the low and high setting of protective capacity.     

消除农业信息瓶颈促进农民增收

增加农民收入是中央政府工作重点。农民在生产经营过程中 ,面临着严重的信息制约 ,农业信息问题已经成为制约农民增收的瓶颈 ,发展农村经济 ,增加农民收入 ,有必要消除农业信息瓶颈。     

Line balancing techniques as used for just-in-time ( JIT) product line optimization

This paper looks at the optimization of a production line similar to a just-in-time ( JIT) production flow line. It discusses the planning process, the types of products that can be ff e ectively processed on a JIT line, and the presently available procedures that should be followed when trying to optimize the production line. The article discusses the shortcomings of these techniques, then, based on research investigations, proceeds to recommend a process that will help assure optimization of a JIT process.     

The effectiveness of input control based on aggregate versus bottleneck work loads

This study compares input control based on aggregate shop loads with that based on bottleneck resource loads. Two appropriate release mechanisms are developed and compared in flow and job shops that have various levels of a bottleneck constraint. Simulation results show that both the level of bottleneck and the flow pattern influence the effectiveness of the strategies. Release based on aggregate loads works well when shop loads are balanced or when there is a bottleneck but the flow is highly structured, as in a flow shop. Release based on bottleneck loads works best when flow patterns are less structured, as in a job shop.     

Asymptotic Throughput in Discrete‐Time Cyclic Networks with Queue‐Length‐Dependent Service Rates

Abstract

For a discrete‐time closed cyclic network of single server queues whose service rates are non‐decreasing in the queue length, we compute the queue‐length distribution at each node in terms of throughputs of related networks. For the asymptotic analysis, we consider sequences of networks where the number of nodes grows to infinity, service rates are taken only from a fixed finite set of non‐decreasing sequences, the ratio of customers to nodes has a limit, and the proportion of nodes for each possible service‐rate sequence has a limit. Under these assumptions, the asymptotic throughput exists and is calculated explicitly. Furthermore, the asymptotic queue‐length distribution at any node can be obtained in terms of the asymptotic throughput. The asymptotic throughput, regarded as a function of the limiting customer‐to‐node ratio, is strictly increasing for ratios up to a threshold value (possibly infinite) and is constant thereafter. For ratios less than the threshold, the asymptotic queue‐length distribution at each node has finite moments of all orders. However, at or above the threshold, bottlenecks (nodes with asymptotically‐infinite mean queue length) do occur, and we completely characterize such nodes.     

Assessing population differentiation and isolation from single-nucleotide polymorphism data

Summary. We introduce a new, hierarchical, model for single-nucleotide polymorphism allele frequencies in a structured population, which is naturally fitted via Markov chain Monte Carlo methods. There is one parameter for each population, closely analogous to a population-specific version of Wright's F _ST , which can be interpreted as measuring how isolated the relevant population has been. Our model includes the effects of single-nucleotide polymorphism ascertainment and is motivated by population genetics considerations, explicitly in the transient setting after divergence of populations, rather than as the equilibrium of a stochastic model, as is traditionally the case. For the sizes of data set that we consider the method provides good parameter estimates and considerably outperforms estimation methods analogous to those currently used in practice. We apply the method to one new and one existing human data set, each with rather different characteristics—the first consisting of three rather close European populations; the second of four populations taken from across the globe. A novelty of our framework is that the fit of the underlying model can be assessed easily, and these results are encouraging for both data sets analysed. Our analysis suggests that Iceland is more differentiated than the other two European populations (France and Utah), a finding which is consistent with the historical record, but not obvious from comparisons of simple summary statistics.     

Bottleneck management: theory and practice

Advocates of TOC believe that bottleneck resource restricts an operation's ability to make money, and the best way to maximise income is to fully exploit the bottleneck resource. Almost all TOC literature focuses on situations where 100% bottleneck utilisation is applied. Based on the implementation experience, the finding is that the optimal level of bottleneck utilisation should be less than 100% and any attempt to increase utilisation beyond the optimal level brings disastrous results for a door manufacturing plant. In order to improve and maintain the performance of the plant effective bottleneck management is critical. The experience provides a deeper understanding of how to design such plants, which could be beneficial for practising managers and academics working with TOC concepts.     

社会管理视野中社会工作人才队伍建设的十大瓶颈

目前我国社会正处于一个空前变革时期,各种社会矛盾集中凸显,社会问题大量涌现,迫切需要建设一支高素质的社会工作人才队伍。但在我国社会工作人才队伍建设的过程中,存在着制度、价值、认同、岗位、教育、本土化、供需、管理、考评、激励等十个方面的瓶颈。如何突破瓶颈,是培养和造就一支职业化、专业化社会工作人才队伍必须解决的课题。     

论家本位观念对中国社会公益事业的制约

中国传统的家本位观念至今仍在影响着中国人,中国社会公益事业要想取得更好发展,需要提高国人的社会观念。然而家庭在中国社会所扮演的角色以及所承担的责任与任务决定了中国人有着很强的家庭观念——家本位观念,而家本位观念是不利于中国社会公益事业的发展的,家本位观念是制约中国社会公益事业发展的瓶颈。发展中国社会公益事业需要政府、企业和个人共同努力,需要发展中国的经济,同时还需要注重中国社会的和谐发展与进步,要将现有资源进行合理有效分配,防止社会问题出现和扩大化,注重社会的科学发展,尽最大可能减少社会问题,使社会和谐健康发展。     

Bottleneck analysis and strategic planning using Tanahashi model for childhood diarrhea management in Gujarat,Western India

In spite of continued efforts, India is still lagging behind in achieving its MDG goals. The objectives of this study were to identify stake-holders who have a role to play in childhood diarrhea management, to identify gaps in childhood diarrhea management and to propose strategic options for relieving these gaps. Bottleneck analysis exercise was carried out based on the Tanahashi model in six High Priority Districts (HPDs) of Gujarat in period between July–November 2013. The major bottlenecks identified for Childhood Diarrhea management were poor demand generation, unsafe drinking water, poor access to improved sanitation facility and lack of equitable distribution and replenishment mechanisms for Oral Rehydration Solution (ORS) packets and Zinc tablets till the front-line worker level. The main strategic options that were suggested for relieving these bottlenecks were Zinc-ORS roll out in scale-up districts, develop Information Education Communication/Behaviour Change Communication (IEC/BCC) plan for childhood diarrhea management at state/district level, use of Drug Logistics Information Management System (DLIMS) software for supply chain management of Zinc-ORS, strengthening of chlorination activity at household level, monitoring implementation of Nirmal Bharat Abhiyaan (NBA) for constructing improved sanitation facilities at household level and to develop an IEC/BCC plan for hygiene promotion and usage of sanitary latrines. Use of Zinc tablets need to be intensified through an effective scale-up. Adequate demand generation activity is needed. There is need to address safe drinking water and improved sanitation measures at household levels. Multi-sectoral engagements and ownership of Zinc-ORS program is the need of the hour.