考虑延误时间成本的最优路边停车策略研究

本文研究了延误时间成本作用下,出行者面对路边停车空位随机分布的寻位策略选择.出行者将做出提前多久出发和提前多远寻位的组合决策,其成本不但包括确定的路上行驶成本,还包括依赖于实时变化路边停车空位分布的延误时间成本和期望寻车成本.依据出行者到达目的地可能的延误状态,区分了三种不同的寻位策略,其中"不早到"策略被证明不可能成为最优选择,而"早停早到"策略和"早停迟到"策略则在不同条件下可能成为最优选择,尤其是单位迟到时间成本小于单位早到时间成本时,"早停迟到"策略是最优停车策略.算例结果支持了模型分析的结论.

基于免疫算法的高温超导故障限流器Pareto多目标优化配置

针对高温超导故障限流器(high temperature superconductor-fault current limiter,HTS-FCL)的全网优化配置问题,提出了一种基于免疫算法的高温超导故障限流器Pareto多目标优化配置新方法。该方法综合考虑了限流器的成本和限流效果这2个优化目标。首先介绍了HTS-FCL的基本结构和原理,分析了安装高温超导故障限流器对原系统自阻抗的影响,提出了一种基于短路电流变化率的灵敏度计算方法,该方法可以缩小搜索空间,提高算法效率。然后分别建立了限流器成本评价子函数、限流效果评价子函数和多目标评价函数,制定了基于免疫算法的多目标Pareto优化算法流程,并在传统免疫算法的基础上提出了一种改进型的等成本倒位算子,通过仿真验证表明该算子较常规的免疫算法,能更好地收敛到最优解。最后以IEEE 39标准节点系统为例,实现了HTS-FCL的全网优化配置,验证了新方法的有效性,并求得了在综合考虑限流器成本和限流效果下的Pareto最优解集,设计者可以根据自己的意愿和实际情况在所求得的Pareto最优解集中选择合适的最优方案。

Effect of copper slag recovery on hydrometallurgical cut-off grades considering environmental aspects

Determining the hydrometallurgical cut-off grades specifies the destination of low grade materials and this is subjected to more benefits in mining. Copper production rate is considered as one of the fundamental issues in hydrometallurgical cut-off grades determination. Slags are remarked as one of the main sources of copper. It is not only regarded as a waste but also identified as another resource extracting base metals. Slags are characterized by copper high grade. Thus, slag copper recovery can be led to different cut-off grades and net present value(NPV). The current research scrutinizes the effect of slag recovery by both flotation and hydrometallurgical methods on the hydrometallurgical cut-off grades. For this purpose, the optimum cut-off grade algorithms of hydrometallurgical methods are developed by considering associated environmental parameters, incomes and also the costs. Then, their optimum amounts are calculated with NPV maximization as an objective function. The results indicate that considering slag copper recovery in the hydrometallurgical cut-off grade algorithms reduces the environmental costs caused by slag dumping and leads to more NPV by 9%.

The Use of Hydrogen as a Fuel for Inland Waterway Units

Escalating apprehension about the harmful effects of widespread use of conventional fossil fuels in the marine field and in internal combustion engines in general, has led to a vast amount of efforts and the directing of large capital investment towards research and development of sustainable alternative energy sources. One of the most promising and abundant of these sources is hydrogen. Firstly, the use of current fossil fuels is. discussed focusing on the emissions and economic sides to emphasize the need for a new, cleaner and renewable fuel with particular reference to hydrogen as a suitable possible alternative. Hydrogen properties, production and storage methods are then reviewed along with its suitability from the economical point of view. Finally, a cost analysis for the use of hydrogen in internal combustion engines is carried out to illustrate the benefits of its use as a replacement for diesel. The outcome of this cost analysis shows that 98% of the capital expenditure is consumed by the equipment, and 68.3% of the total cost of the equipment is spent on the solar photovoltaic cells. The hydrogen plant is classified as a large investment project because of its high initial cost which is about 1 billion US$; but this is justified because hydrogen is produced in a totally green way. When hydrogen is used as a fuel, no harmful emissions are obtained.

（Dis）Economies of Scale in Business Software Systems Development and Enhancement Projects

In the software engineering literature, it is commonly believed that economies of scale do not occur in case of software Development and Enhancement Projects （D＆EP）. Their per-unit cost does not decrease but increase with the growth of such projects product size. Thus this is diseconomies of scale that occur in them. The significance of this phenomenon results from the fact that it is commonly considered to be one of the fundamental objective causes of their low effectiveness. This is of particular significance with regard to Business Software Systems （BSS） D＆EP characterized by exceptionally low effectiveness comparing to other software D＆EP. Thus the paper aims at answering the following two questions： （1） Do economies of scale really not occur in BSS D＆EP？ （2） If economies of scale may occur in BSS D＆EP, what factors are then promoting them？ These issues classify into economics problems of software engineering research and practice.

Localization of Small Mobile Robot by Low-Cost GPS Receiver

This article deals with a problem of the robot localization in the outdoor environment by using the GPS （global positioning system） data. In order to navigate the robot, it is necessary to transform the global position into the local map in the form of two-dimensional Cartesian coordinate system. The transformation is based on the model of the Earth-WGS 84 reference ellipsoid. The aim of this article is to experimentally evaluate a set of low-cost GPS receivers applicable as position sensors for small outdoor mobile robots. The evaluation is based on series of measurements executed in different times and places. The measured data is processed by given procedure and acquired positions are transformed into the local coordinate system. Accordingly the accuracy of the measured positions is statistically evaluated. The evaluation of used GPS receivers is done by comparison with data acquired by high-end geodetic GPS system Leica 1200, which is used as a reference GPS system.

Modeling of a Demethanizer Tower Using Statistical Tools

Monitoring of industrial plant performance and detection on flaws is important to the successful operation on industrial production units. Malfunctioning equipment can greatly impact plant performance by reducing the efficiency and increasing the production cost. Phenomenological equations cannot properly describe industrial processes. Thus, it is necessary to develop new equations for model industrial operations. The purpose of this study is to develop an empirical model for industrial demethanizer tower which is malfunctioning due to an error in the design in one of its plates. A nonlinear statistical model was designed to predict the pressure variation in the column, and consequently, the flooding conditions. This model was validated using industrial data to predict the maximum loads in the column.

Linear Programs in Cost Accounting： A Linear Cost Model

This paper aims to find unit cost of a product for firms. It establishes a linear cost model to find unit cost. Linear goal programs assume a direct relationship between independent variable and dependent variable. Dependent variable of linear model is unit cost. Independent variables are cost accounting variables. They are supply cost, labor cost, and administration cost. This study assumes a direct relationship between supply-labor-administration costs and unit cost. Therefore, it establishes a linear cost model. The major research question of this study is to apply linear goal programming to cost accounting. The goal of this linear program is to find unit cost of product. This study uses quantitative method and human capital method. The main research result is linear costing model itself.

Learning by Doing Effect in North South Trade under the Global Value Chains： An Empirical Analysis of Various Industries in the U.S.

This paper studies the division of labor and economic development under global value chains in North South trade by mainly investigating the changes of production hours and cost per unit along with more and more output and increasing trade value in several industries in the U.S., because the U. S. is at the leading position in the division of labor by global value chains. The empirical evidence reveals that more international outsourcing, there will be more detailed division of labor, and the industry unit production time and production cost will show more declining trend year by year. This is consistent with that the global value chains and the outsourcing play more and more important roles in the international division of labor and economic growth in both developed and developing countries, and helps explain the integration of workforce across countries in the global value chains.

Flotation studies on low grade graphite ore from eastern India

A low grade graphite ore from eastern India was beneficiated by flotation to improve its quality. The ore was composed of 87.80%ash and 8.59%fixed carbon. Primary coarse wet grinding （d80：186 μm） followed by rougher flotation in Denver flotation cell using diesel as collector and pine oil as frother yielded a rougher concentrate. Regrinding （d80：144 μm） of this rougher concentrate was opted for further libera-tion of graphite. It was followed by cleaning in laboratory flotation column. This combined process of relatively coarse primary grinding followed by regrinding and cleaning in flotation column resulted in final concentrate of 7.44% yield with 89.65% fixed carbon and 6.00% ash. This approach of two-stage grinding to recover the flake graphite at the coarsest possible grind can help to minimize grinding energy costs. A conceptual flow sheet which is cost effective was developed based on this methodology.

Development of a Low-Cost Weather Station to Measure in Situ Essential Climate Variables

A weather station is proposed especially designed for developing countries, and to meet the standards of the international scientific community making research on the earth system. The station would measure in situ several ECV （essential climate variables）. These data may enable an agricultural breakthrough in countries lacking meteorological infrastructure, help in climate change monitoring, and facilitate diffusion of wind energy. A pre-feasibility analysis is presented. It appears interesting that the station is supplied by a social enterprise. A research to establish the best shelter design using computational fluid dynamics is also reported. The criterion is the accuracy with which the surface air temperature is reproduced inside the shelter. A design following recommendations by the WMO （World Meteorological Organization）, a smaller design with identical geometry, and two alternative small designs are analyzed. All four designs are simulated in PVC, natural rubber and wood, with and without white paint coating. The smaller shelters perform better. The influence of the material, dimensions and design is smaller than that of the white paint. Shelters made of PVC or rubber, and/or in alternative designs, may be more interesting if other criteria are considered, like whether logistics, manufacturing, etc. are more sustainable, easier and/or cheaper.

A K-Median Facility Location Agent for Low-Cost Service Selection in Digital Community Network

With the increasing number of web services, it becomes a difficult task for an ordinary user to select an appropriate service. Hence, it is conventional that users in a digital community network take part in a collaborative mechanism for the purpose of service selection. The participation usually brings unnecessary burdens for users, such as giving opinions, storing service information. Extra communication overhead hinders the performance of the network. Thus, the community administrators are facing a problem of how to obtain an overall service selection result for the whole community readily and effectively. To address this problem, we present a k-median facility location agent model. The model analyzes the procedure of service selection through five entities and six types of messages. Two algorithms are elaborated in pursuit of a global optimization concerning connection costs between users and facilities where services are deployed. To evaluate our model, we conduct extensive simulations and present a detailed analysis of the simulation results.

Kit of Self-Moving Units for Automatic Inspection of Marine Structures and Plants： Low Cost Unit for Inspection of Holds

All vessels and offshore units require regular inspections to prevent structural or functional damages. Periodical inspections are based on classification society＇s requirements and include both visual surveys and non-destructive test interventions, to look for structural damage, pitting, corrosion, thickness measurement, usually documented by measurements or images. Different approaches of inspection can be proposed for underwater and for dry areas, using unmanned vehicles or service robots able to improve traditional inspection methods. Several excellent proposals are today available： nevertheless, reasons of costs, operation complexity and impossibility to cover all types of inspection with a unique autonomous unit limit and conditions the applicability of automatic inspection systems. The paper is the first of a series describing the main results of a wide research activity carried out at DREAMS Lab （Laboratory of Drives and Experimental Automation for Marine Systems） of the University of Genoa. The studies are oriented to the realization of a kit of low cost and unsophisticated self-moving units, devoted to support some recursive inspections in dry areas of ships and on offshore plants as bulkheads, holds, double bottoms and ducts. The paper describes the design and prototyping of a pneumatronic unit oriented to inspection and maintenance of ship holds. Conceived to realize a portable and user-friendly tool which could take part of an ＂inspection kit＂ for the use of inspectors, able to simplify and speed up the inspection visits with and automatic generation of survey reports.

Phytotherapic Potentials of Xylopia aethiopica Dried Fruits （Grains of Selim） as Additive in Broiler Production

Xylopia aethiopica dried fruits （gains of selim） as an additive in starter broilers production was investigated. For this purpose, a total of 195-day old broiler chicks （Arbor acres） were randomly allocated into five treatments groups with 39 chicks and three replicates of 13 chicks in each. Blended grains of selim was given through drinking water on treatments T2, T3, T4 and T5 at concentrations of 0.4, 0.6, 0.8 and 1,0 g/L, while chicks on treatment T1 （control） received antibiotics （Doxy-gen 20/20 WSP： Doxycycline hyclate 200 mg and Gentamicine sulfate 200 mg） at 0.3 g/L of water. All the experimental chicks were fed ad libitum with diet containing 23% crude protein and 2,851.55 kcal/kg metabolizable energy for 28 d. The results revealed that there were similarities （P 〉 0.05） in final body weight, total weight gain, daily weight gain, total feed intake, daily feed intake and feed conversion ratio among the treatments. There were significant （P 〈 0.05） differences in the microbial count of faeces before the birds received antibiotics and grains of selim, but count were similar （P 〉 0.05） after grains of selim and antibiotics were administered. Cost of total feed consumed, cost of per kg feed and cost of per kg weight were significantly （P 〈 0.05） higher in treatment T1, but cost differential and relative cost benefit were similar （P 〉 0.05）. Results indicate that grains of selim have antimicrobial and anthelminthic properties, and promote growth in broiler chickens.

WLAN indoor location method based on artificial neural networkt

WLAN mdoor location method based on artificial neural network （ANN） is analyzed. A three layer feed-forward ANN model offers the benefits of reducing time cost of the layout of an indoor location system, saving storage cost of the radio map establishment and enhancing real-time capacity in the on-line phase. According to the analysis of SNR distributions of recorded beacon signal samples and discussion about the multi-mode phenomenon, the one map method is proposed for the purpose of simplifying ANN input values and increasing location performances. Based on the simulations and comparison analysis with other two typical indoor location methods, K-nearest neighbor （KNN） and probability, the feasibility and effectiveness of ANN-based indoor location method are verified with average location error of 2.37m and location accuracy of 78.6% in 3m.

Single-Seed Casting Large-Size Monocrystalline Silicon for High-Efflciency and Low-Cost Solar Cells

To grow high-quality and large-size monocrystalline silicon at low cost, we proposed a single-seed casting technique. To realize this technique, two challenges—polycrystalline nucleation on the crucible wall and dislocation multiplication inside the crystal—needed to be addressed. Numerical analysis was used to develop solutions for these challenges. Based on an optimized furnace structure and operating conditions from numerical analysis, experiments were performed to grow monocrystalline silicon using the single-seed casting technique. The results revealed that this technique is highly superior to the popular high-performance multicrystalline and multiseed casting mono-like techniques.

Development of an Anaerobic Digestion Unit for Biogas Production from Cow Dung Substrate

An anaerobic digestion unit for producing biogas from cow dung in the rural communities was designed, fabricated and tested for performance, durability and throughput. The major components of the digester included the substrate holding tank, tank cover, agitator, debris collector, inlet and outlet pipes, gas reception tank, hose and heat source. The digester is a vertical cylindrical tank with an inlet pipe for the introduction of substrate and an outlet pipe to collect the digested substrate. An agitator is incorporated inside the digester to break scum on the substrate and create uniform temperature profile in the digester while a pressure gauge was fitted to the gas outlet valve to measure the gas pressure in the tank. The agitator shaft is extended outside to be driven by an electric motor through belt and pulley system. The criteria considered in the design of the digester included air tightness of the system, mesophilic and thermophilic temperature, nature and type of substrate used, substrate retention period, number of crank turns per minute and volumetric capacity of the digestion tank. Other considerations included the desire to make the digestion tank and gas reception tank of galvanized steel to ensure good quality of the product and the need for a strong structural support to ensure structural stability of the system. After construction and assembly, the biogas digestion unit was tested with 40 kg of cow dung diluted with 80 kg of water and subjected to a retention period to make a substrate （slurry） of 10 % total solid （TS）. Daily gas yield was determined; gas pressure in the tank was measured by the pressure gauge, while the ambient temperature was taken at five hours interval. Results showed that a cumulative gas yield of 0.415 litres after 22 d retention period at average substrate temperature and pH of 29 ℃ and 6.2, respectively. The digester has a substrate holding capacity of 330.8 litres and a production cost of $375 with all the construction materials being available locally.

Cost of Production at Business Unit in Aquaculture Industry： Study at Aquafarm Nusantara Company

Types of industry are manifold, patterns used in the determination of the cost of production can also vary. Elements of the cost of production are raw materials, direct labor, and factory overhead. Value of raw materials used in aquaculture industry in particular needs to calculate the cost of feed consumed by fish, thus greatly affect the price of fish feed cost of production. The calculation of the value of raw materials in fish production cost element to consider is the calculation of the value of raw material components, namely, （1） biomass of harvestable fish as the basic multiplication cost of production per kilogram or per fish harvested fish; （2） the ratio of fish feed intake by the amount of fish produced or often called the Feed Conversion Ratio （FCR）; and （3） the average purchase price of feed on fish harvest period is used as the basis for calculating the cost of production as well. This research is applied research that uses data archive aquaculture companies. The results in the observed period, the value FCR is 0.80, which means to fish have been consumed as much as 0.80 kg of fish feed. Biomass of fish that are harvested at 47,399.95 kg or 1,869,647 individuals. The average purchase price of fish feed on the observation period amounted to IDR 4,855.79. So the price of raw materials contained in harvested fish in the observation period calculates the value of multiplying all the components of raw materials （i.e., IDR 184,131,362.57）. Method of calculating the cost of production companies is process method and charging method used is the full costing method.

Clusters as a Way of Penetration of International Market

The global financial and economic crisis has negatively affected all business units. Tough fight for the market position results in effort to create efficient methods to maintain company＇s competitiveness. Some of small and medium entrepreneurs have started to search the business allies. As an example of such possibility of cooperation the formation of clusters should be mention. The main intention of this paper is to demonstrate possibility for small and medium-sized enterprises （SMEs） to cooperatively penetrate new markets. Attention is focused mainly on a real export-oriented cluster. Ambition is to use costs and benefits analysis to test ability of the cluster to improve chances of companies to penetrate new markets. In order to link this analysis to real life as much as possible, existing cluster was used and on its accomplishments and failures costs and benefits of clustering are demonstrated.