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Search Results: 1 - 10 of 4212 matches for " Transmission Bottleneck "
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Hydro and Wind Power Integration: A Case Study of Dargai Station in Pakistan  [PDF]
Shahbaz Awan, Muhammad Ali, Muhammad Asif, Amjad Ullah
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.44028
Abstract: Pakistan is facing acute energy crises since last few years. Due to shortage of fuel oil and its sky touching prices, it seems very uneconomical to generate electricity from fuel oil. In order to generate cheap electricity we have to rely on renewable energy resources. To address these challenges, wind power generation is among the popular options in the world which is now being considered in Pakistan as well. However unremitting change in wind speed from calm to stormy introduces real challenges. Storing wind energy in batteries during the periods of low demand seems an expensive option, especially when dealing with large scale power generation. Due to incessantly varying nature of wind speed, it is not feasible to rely only on wind power for cheap power production. Also, it is not thriftily possible to construct separate transmission line. However if we integrate wind power with hydro power, we can utilize the maximum possible transmission capacity. Existing hydro power station operating in that area or pumped storage scheme can be used. This paper is an attempt to analyze coordination of wind generation with hydro power in those areas of Pakistan where both wind and hydro power sources exist. In this paper, different issues have been analyzed taking case study of Dargai. This paper is first attempt in Pakistan about integration of wind and hydro power to draw some general conclusions and to point out some areas in which further research can be done.
Discourse about Linear Programming and Lean Manufacturing: Two Different Approaches with a Similar, Converging Rational  [PDF]
Bruno G. Rüttimann
Journal of Service Science and Management (JSSM) , 2015, DOI: 10.4236/jssm.2015.81010
Abstract: In recent years, the Toyota Production System has also assumed in western manufacturing plants a predominant position. Lean Manufacturing, as it is usually called in the occidental world, aims at a “Single-piece-flow” job handling and has its advantages compared to the classic “Batch and Queue” job handling. On the other hand, mathematical Linear Programming optimization techniques have passed into oblivion, having obtained the feel to be inappropriate for production planning. Although the two approaches have different aims and application, they give particular attention to scarce resources. The concepts of “bottleneck” in Lean Manufacturing and “shadow price” in Linear Programming are complementary. The paper shows the different focus of the two approaches and crystallizes their synergic values.
高速公路瓶颈区域可变限速阶梯控制方法
Stair-Like Control Strategies of Variable Speed Limit for Bottleneck Regions on Freeway

杨庆芳, 马明辉, 梁士栋, 李志林
YANG Qingfang
, MA Minghui, LIANG Shidong, LI Zhilin

- , 2015,
Abstract: 摘要: 针对高流量条件下高速公路主线瓶颈路段交通流运行态势恶劣导致通行效率降低的问题,从高速公路瓶颈路段交通流时空特性出发,对元胞传输模型进行扩展,使其能够对瓶颈路段和可变限速条件下交通流运行情况进行描述;在此基础上,构建可变限速控制模型,并采用阶梯限速控制方法对主线交通流进行控制,防止限速路段车辆排队上溯影响上游匝道车辆的正常通行.算例仿真结果表明:本文提出的瓶颈区域可变限速阶梯控制方法能够有效缩短车辆行程时间,在可变限速条件下,与无控制和仅单路段主线控制相比,车均延误分别减少了13.78%和1.60%.
Abstract: The traffic flow operation at bottleneck sections on freeway mainlines is usually deteriorated by heavy traffic load, resulting in an increase in travel time and a decrease in traffic efficiency. By analyzing the space-time characteristics of the traffic flow at bottleneck sections on freeway mainlines, the cell transmission model was expanded to describe the traffic flow in the bottleneck area under variable speed limit (VSL) control. On this basis, a VSL control model for bottleneck region was established, and stair-like strategies were proposed to prevent the long queue from interrupting the vehicles operation at upstream on-and off-ramps. The proposed methods were tested through a case study, and the results demonstrate that the proposed stair-like strategies for VSLs can effectively reduce the travel time and decrease the average delay. Compared with no control and the strategy of using mainline control on single sections, the proposed strategies can reduce the average delay by about 13.78% and 1.60%, respectively
INFLASI DI INDONESIA : SUMBER-SUMBER PENYEBAB DAN PENGENDALIANNYA
Adwin Surja Atmadja
Jurnal Akuntansi dan Keuangan , 1999,
Abstract: The monetary crisis that happens among the ASEAN countries including Indonesia has cause the broken of the national economical aspects. The monetary crisis causes the imported inflation, which is the result of the sharp depreciation of rupiah exchange rate toward the foreign exchange rate. This condition can cause the heavy inflation pressure for Indonesia. The inflation phenomenon in Indonesia actually is not the short-term phenomena. That is only happens incidentally. In fact, the same general problem also happens in others developing countries. The inflation problem in Indonesia is the kind of long-term inflation that caused by the structural of economic obstacles that still occur in Indonesia. As the result, the reconstruction of inflation problem in Indonesia is not enough to be accomplished only with monetary instruments, which usually tend to be in short-term. Therefore, the reconstruction in the real sector with the main target to eliminate the nation structural economic obstacles also needed in order to improve the national economy of Indonesia. Abstract in Bahasa Indonesia : Krisis moneter yang melanda negara-negara ASEAN, termasuk Indonesia, telah menyebabkan rusaknya sendi-sendi perekonomian nasional. Krisis moneter menyebabkan terjadinya imported inflation sebagai akibat dari terdepresiasinya secara tajam nilai tukar rupiah terhadap mata uang asing, yang selanjutnya mengakibatkan tekanan inflasi yang berat bagi Indonesia. Fenomena inflasi di Indonesia sebenarnya semata-mata bukan merupakan suatu fenomena jangka pendek saja dan yang terjadi secara situasional, tetapi seperti halnya yang umum terjadi pada negara-negara yang sedang berkembang lainnya, masalah inflasi di Indonesia lebih pada masalah inflasi jangka panjang karena masih terdapatnya hambatan-hambatan struktural dalam perekonomian negara. Dengan demikian, maka pembenahan masalah inflasi di Indonesia tidak cukup dilakukan dengan menggunakan instrumen-instrumen moneter saja, yang umumnya bersifat jangka pendek, tetapi juga dengan melakukan pembenahan di sektor riil, yaitu dengan target utama mengeliminasi hambatan-hambatan struktural yang ada dalam perekonomian nasional. Kata kunci : inflasi, structural bottleneck.
Improvability of assembly systems I: Problem formulation and performance evaluation
Chiang S.-Y.,Kuo C.-T.,Lim J.-T.,Meerkov S. M.
Mathematical Problems in Engineering , 2000,
Abstract: This work develops improvability theory for assembly systems. It consists of two parts.Part I includes the problem formulation and the analysis technique. Part II presents the so-called improvability indicators and a case study. Improvability theory addresses the questions of improving performance in production systems with unreliable machines. We consider both constrained and unconstrained improvability. In the constrained case, the problem consists of determining if there exists a re-distribution of resources (inventory and workforce), which leads to an increase in the system's production rate. In the unconstrained case, the problem consists of identifying a machine and a buffer, which impede the system performance in the strongest manner. The investigation of the improvability properties requires an expression for the system performance measures as functions of the machine and buffer parameters. This paper presents a method for evaluating these functions and illustrates their practical utility using a case study at an automotive components plant. Part II uses the method developed here to establish conditions of improvability and to describe additional results of the case study.
Improvability of assembly systems II: Improvability indicators and case study
Chiang S.-Y.,Kuo C.-T.,Lim J.-T.,Meerkov S. M.
Mathematical Problems in Engineering , 2000,
Abstract: Based on the performance analysis technique developed in Part I, this paper presents improvability indicators for assembly lines with unreliable machines. In particular, it shows that assembly lines are unimprovable with respect to workforce re-distribution if each buffer is, on the average, close to being half full. These lines are unimprovable with respect to buffer capacity re-distribution if each machine is starved and blocked with almost equal frequency. In addition, the paper provides indicators for identification of bottleneck machines and bottleneck buffers. Finally, the paper reports on an application of these improvability indicators in a case study at an automotive components plant.
Coordinator MPC for maximizing plant throughput
Elvira M.B. Aske,Stig Strand,Sigurd Skogestad
Modeling, Identification and Control , 2008, DOI: 10.4173/mic.2008.3.3
Abstract: In many cases economic optimal operation is the same as maximum plant throughput, which is the same as maximum flow through the bottleneck(s). This insight may greatly simplify implementation. In this paper, we consider the case where the bottlenecks may move, with parallel flows that give rise to multiple bottlenecks and with crossover flows as extra degrees of freedom. With the assumption that the flow through the network is represented by a set of units with linear flow connections, the maximum throughput problem is then a linear programming (LP) problem. We propose to implement maximum throughput by using a coordinator model predictive controller (MPC). Use of MPC to solve the LP has the benefit of allowing for a coordinated dynamic implementation. The constraints for the coordinator MPC are the maximum flows through the individual units. These may change with time and a key idea is that they can be obtained with almost no extra effort using the models in the existing local MPCs. The coordinator MPC has been tested on a dynamic simulator for parts of the K rst gas plant and performs well for the simulated challenges.
Makespan Algorithms and Heuristic for Internet-Based Collaborative Manufacturing Process Using Bottleneck Approach  [PDF]
Salleh Ahmad BAREDUAN, Sulaiman HASAN
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.31011
Abstract: This paper presents makespan algorithms and scheduling heuristic for an Internet-based collaborative design and manufacturing process using bottleneck approach. The collaborative manufacturing process resembles a permutation re-entrant flow shop environment with four machines executing the process routing of M1,M2,M3,M4,M3,M4 in which the combination of the last three processes of M4,M3,M4 has high tendency of exhibiting dominant machine character-istic. It was shown that using bottleneck-based analysis, effective makespan algorithms and constructive heuristic can be developed to solve for near-optimal scheduling sequence. At strong machine dominance level and medium to large job numbers, this heuristic shows better makespan performance compared to the NEH.
A New Job Shop Heuristic Algorithm for Machine Scheduling Problems  [PDF]
Maryam Ehsaei, Duc T. Nguyen
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.511177
Abstract: The purpose of this research is to present a straightforward and relatively efficient method for solving scheduling problems. A new heuristic algorithm, with the objective of minimizing the makespan, is developed and presented in this paper for job shop scheduling problems (JSP). This method determines jobs’ orders for each machine. The assessment is based on the combination of dispatching rules e.g. the “Shortest Processing Time” of each operation, the “Earliest Due Date” of each job, the “Least Tardiness” of the operations in each sequence and the “First come First Serve” idea. Also, unlike most of the heuristic algorithms, due date for each job, prescribed by the user, is considered in finding the optimum schedule. A multitude of JSP problems with different features are scheduled based on this proposed algorithm. The models are also solved with Shifting Bottleneck algorithm, known as one of the most common and reliable heuristic methods. The result of comparison between the outcomes shows that when the number of jobs are less than or equal to the number of machines, the proposed algorithm concludes smaller, and better, makespan in a significantly lower computational time, which shows the superiority of the suggested algorithm. In addition, for a category when the number of jobs are greater than the number of machines, the suggested algorithm generates more efficient results when the ratio of the number of jobs to the number of machines is less than 2.1. However, in this category for the mentioned ratio to be higher than 2.1, the smaller makespan could be generated by either of the methods, and the results do not follow any particular trend, hence, no general conclusions can be made for this case.
A Simulation Model for Sexual and Vectorial Transmission of Zika Virus (ZIKV)  [PDF]
Oscar Arias Manrique, Dalia M. Mu?oz Pizza, Anibal Mu?oz Loaiza, Julian A. Olarte García, Carlos A. Abello Mu?oz, Steven Raigosa Osorio, Angie Johanna Osorio, Hans Meyer Contreras, John F. Arredondo Montoya
Open Journal of Modelling and Simulation (OJMSi) , 2017, DOI: 10.4236/ojmsi.2017.51006
Abstract: Nowadays the Zika virus (ZIKV) has been one of the most studied vector-borne diseases due to the considerable outbreaks that have generated around the world as well as due to the new transmission mechanisms and health complications originated. According to statistics of the INS-Colombia for July 2016, 68% of the population infected by ZIKV (confirmed cases) are pregnant women. Furthermore, the Quindío department belongs to the states with more than 50% of the total infected persons being pregnant women. Taking into account those characteristics, a theoretical model is proposed and analyzed to describe the population dynamics considering the sexual and vectorial transmission of ZIKV, with special emphasis in the consequences of the non-vectorial transmission in the population. The obtained results with simulations through the beta parameter indicate that the probability of sexual transmission between susceptible women and infected men points out the importance of campaigns to inculcate prevention measures for the safe sexual relationships between ZIKV infected population.
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