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Operation Cost (operation + cost)

Distribution by Scientific Domains
Engineering42%

Selected Abstracts

Maintenance contract assessment for aging systems

QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 5 2008
Anatoly Lisnianski
Abstract This paper considers an aging system, where the system failure rate is known to be an increasing function. After any failure, maintenance is performed by an external repair team. Repair rate and cost of repair are determined by a corresponding maintenance contract with a repair team. There are many different maintenance contracts suggested by the service market to the system owner. In order to choose the best maintenance contract, a total expected cost during a specified time horizon should be evaluated for an aging system. In this paper, a method is suggested based on a piecewise constant approximation for the increasing failure rate function. Two different approximations are used. For both types of approximations, the general approach for building the Markov reward model is suggested in order to assess lower and upper bounds of the total expected cost. Failure and repair rates define the transition matrix of the corresponding Markov process. Operation cost, repair cost and penalty cost for system failures are taken into account by the corresponding reward matrix definition. A numerical example is presented in order to illustrate the approach. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Dynamic operation plan of a combined fuel cell cogeneration, solar module, and geo-thermal heat pump system using Genetic Algorithm

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2007
Shin'ya Obara
Abstract A chromosome model that simulates the operation patterns of an energy system was introduced into a simple Genetic Algorithm, and a method of dynamic optimization was developed. This paper analyses the operation planning of an energy system that uses in combination a solar power module, proton-exchange membrane fuel cell cogeneration (PEMFC-CGS) with methanol steam reforming, a geo-thermal heat pump, heat storage and battery, commercial power, and a kerosene boiler. The hours of operation of each energy device and the rate of the energy output were calculated by having introduced the analysis program developed by this study. Three objective functions: (a) minimization of operation cost; (b) minimization of the error of demand-and-supply balance; and (c) minimization of the amount of greenhouse gas discharge were given to the optimization analysis of the system. Furthermore, the characteristics of the system operation planning under each objective function are described. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Operating schedule of a combined energy network system with fuel cell

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2006
S. ObaraArticle first published online: 16 MAY 200
Abstract The chromosome model showing system operation pattern is applied to GA (genetic algorithm), and the method of optimization operation planning of energy system is developed. The optimization method of this operation planning was applied to the compound system of methanol-steam-reforming-type fuel cell, geothermal heat pump and the electrolysis tank of water. The operation planning was performed for the energy system using the energy demand pattern of the individual residence of Sapporo city. From analysis results, the amount of outputs of a solar module and the relation of the operation cost of the system, which are changed by the weather were clarified. The representation day in February of the ratio of the operation cost in case of (0% of output rates) the rainy weather to the time of fine weather (100% of output rates) is 1.12. And the representation day in July is 1.71. Furthermore, the optimal capacity of accumulation of electricity and thermal storage was estimated, and they are 308 and 23 MJ, respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source]

BCCB preconditioners for systems of BVM-based numerical integrators

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 1 2004
Siu-Long Lei
Abstract Boundary value methods (BVMs) for ordinary differential equations require the solution of non-symmetric, large and sparse linear systems. In this paper, these systems are solved by using the generalized minimal residual (GMRES) method. A block-circulant preconditioner with circulant blocks (BCCB preconditioner) is proposed to speed up the convergence rate of the GMRES method. The BCCB preconditioner is shown to be invertible when the BVM is Ak1,k2 -stable. The spectrum of the preconditioned matrix is clustered and therefore, the preconditioned GMRES method converges fast. Moreover, the operation cost in each iteration of the preconditioned GMRES method by using our BCCB preconditioner is less than that required by using block-circulant preconditioners proposed earlier. In numerical experiments, we compare the number of iterations of various preconditioners. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Economical Advantages of Low-Pressure Plasma Polymerization Coating

PLASMA PROCESSES AND POLYMERS, Issue 6 2005
Hirotsugu Yasuda
Abstract Summary: Low-pressure plasma polymerization coating, as described in this paper, is an ultimately green process that uses a minimum amount of substances and produces a minimum amount of effluent and hence does not require an environmental remediation process. The super-green aspect of the processing entirely changes the equation for the viability of the process in industrial applications. The main hampering factors for the low-pressure processes are 1) psychological fear of vacuum processes, 2) relatively high initial equipment costs, and 3) a lack of adequate cost estimate for the entire process. In many cases, the first two factors are enough for planners to shy away from this promising technology. However, when one examines the overall cost of processing as a whole, the cost of initial equipment often is not the decisive factor. Such cases are presented in the nano-film coating applied in corrosion protection of aluminum alloys, steel, and surface-state modification of contact lenses. The benefits of environmental friendliness, non-hazardous processing and superior performance of products that can be achieved only by low-pressure plasma polymerization coatings are more than enough to compensate the initial cost of the equipment. For nanofilm (20 nm) coatings, the most expensive annual operation cost is for wastewater treatment, which is much more than the initial cost of vacuum plasma polymerization reactor. [source]

Agrarian Transformation and Rural Diversity in Globalizing East Asia

INTERNATIONAL JOURNAL OF JAPANESE SOCIOLOGY, Issue 1 2004
Atsushi Kitahara
Abstract:, In East Asia the rural society is not a society based upon agricultural industry anymore and the peasant society with its long history has been disappearing. The occupation and income sources of rural inhabitants have diversified and among them those who specialized in farming are the minority. There is a shortage of rural labor, which used to be abundant in the past, and presently it is not as easy to hire the farm workers. The reason for the diversification of the rural occupations is, to put it simply, because people cannot live merely on farm income. Indeed the farm operation costs have become more expensive due to labor saving techniques, but the livelihood costs have become more expensive due the new uniform lifestyle standards from globalization. Electric machines and education are the typical of these increased costs. The background of this rural change is industrialization and urbanization in the context of globalization and its strong impact is penetrating into the rural society through the regional urban center as the relay point of the global mechanism. This change is different based upon the location of each rural society. Generally, rural societies around a big urban center enjoy opportunities for the younger generation, but remote areas have serious problems with few employment opportunities and a smaller youth population. To reproduce and sustain the regional society as a whole, it is necessary to attract younger people and make them stay. We should plan to develop a variety of industries and the resultant diversified work opportunities in the broader region beyond the narrowly demarcated village and community. Subsistence and commercial agriculture might merely be a part of such diversity. [source]

Sediment dynamics and pollutant mobility in rivers: An interdisciplinary approach

LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2004
Ulrich Förstner
Abstract Characteristic dynamic features of sediment-related processes in rivers include dramatic effects of stormwater events on particle transport, rapid and far-reaching effects of sulphide oxidation during resuspension, and biological accumulation and potential release of toxic chemicals. Pollutant mobility is the net result of the stabilizing and mobilizing effects in both hydraulic and chemical fields. In practice, emphasis has to be given to fine-grained sediments and suspended matter as these materials exhibit large surface areas and high sorption capacities. Organic materials are highly reactive. Degradation of organic matter will induce oxygen depletion and might enhance formation of flocs and biofilms. Study of variations of sediment and water chemistry should predominantly include changes of pH and redox conditions, competition of dissolved ions and processes such as complexation by organic substances. Major questions relate to the potential reduction of sorption sites on minerals and degradation of organic carrier materials. All these processes will influence solution/solid equilibrium conditions and have to be studied prior to modelling the overall effects of pollutants on the water body and aquatic ecosystems. With respect to handling and remediation of contaminated river sediments, either in-place or excavated, a chemical and biological characterization of the material, of the (disposal) site and of the long-term processes is crucial. Passive techniques (e.g. in situ stabilization, subaqueous capping) provide economic advantages as there are no operation costs following their installation. However, the success of these ecological and geochemical engineering approaches is mainly based on an in-depth knowledge of the underlying processes. [source]