2,701 research outputs found

    A simple state-based prognostic model for filter clogging

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    In today's maintenance planning, fuel filters are replaced or cleaned on a regular basis. Monitoring and implementation of prognostics on filtration system have the potential to avoid costs and increase safety. Prognostics is a fundamental technology within Integrated Vehicle Health Management (IVHM). Prognostic models can be categorised into three major categories: 1) Physics-based models 2) Data-driven models 3) Experience-based models. One of the challenges in the progression of the clogging filter failure is the inability to observe the natural clogging filter failure due to time constraint. This paper presents a simple solution to collect data for a clogging filter failure. Also, it represents a simple state-based prognostic with duration information (SSPD) method that aims to detect and forecast clogging of filter in a laboratory based fuel rig system. The progression of the clogging filter failure is created unnaturally. The degradation level is divided into several groups. Each group is defined as a state in the failure progression of clogging filter. Then, the data is collected to create the clogging filter progression states unnaturally. The SSPD method consists of three steps: clustering, clustering evaluation, and remaining useful life (RUL) estimation. Prognosis results show that the SSPD method is able to predicate the RUL of the clogging filter accurately

    Fiscal Policy, Default and Emerging Market Business Cycles

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    Developing country fiscal policy outcomes documented in data point to stark differences compared with developed ones. Most prominent difference is the excessive volatility of government consumption and transfer payments and their positive correlation relative to output. This seemingly non-optimal behavior is puzzling since it is in contrast with standard theory prescriptions and likely to contribute to aggregate volatility. To study the possible roots of this I build a model by incorporating a detailed explicit fiscal sector to what is otherwise a standard sovereign default setup. The environment I define is one of incomplete markets that resembles small open developing economies with respect to existence of short-maturity non-state contingent defaultable debt as the only tradable asset for the sovereign government and financial frictions on private sector. I use this model to identify the contribution of market incompleteness due to the commitment problem of the sovereign. The findings point that the endogenous state-contingent borrowing constraints that sovereigns face as a result of commitment problem in debt repayment is a major factor in accounting for the pro-cyclicality of transfer payments and excessive relative volatility of transfers and government consumption in these countries. The effect of financial frictions of the type defined as working capital constraint on an imported input combined with debt sensitive private borrowing cost is increased volatility of fiscal policy due to debt loosing its buffer-stock property in smoothing out shocks to fiscal revenues

    Surface morphological evolutions on single crystal films by strong anisotropic drift-diffusion under the capillary and electromigration forces

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    The morphological evolution of voids at the unpassivated surfaces and the sidewalls of the single crystal metallic films are investigated via computer simulations by using the novel mathematical model developed by Ogurtani relying on the fundamental postulates of irreversible thermodynamics. The effects of the drift-diffusion anisotropy on the development of the surface morphological scenarios are fully explored under the action of the electromigration (EM) and capillary forces (CF), utilizing numerous combination of the surface textures and the directions of the applied electric field. The interconnect failure time due to the EM induced wedge shape internal voids and the incubation time of the oscillatory surface waves, under the severe instability regimes, are deduced by the novel renormalization procedures applied on the outputs of the computer simulation experiments.Comment: 41 pages, 18 figures. related simulation movies utilizing numerous combination of the surface texture, see http://www.csl.mete.metu.edu.tr/aytac/thesis/movies/index.ht

    Recent Advances in Photovoltaic-Trombe Wall System: A Review

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    Management of energy consumption for building’s air conditioning is a vital issue for resource saving and environmental protection. The use of solar energy to generate electricity by solar cells is essential nowadays. However, the disadvantage of solar panels is the elevated temperature in work, especially in the hot sunny climate that leads to efficiency decline. Also, there is a problem with heating during the night and cloudy days. For the last 20 years, there has been a rapid development in the field of integrated solar technologies. A hybrid PV/Trombe wall (PV/TW) system suggested being an efficient and durable conversion system of solar energy. The design of the PV/TW system considered one of the focusing areas of the present research to make it more economically feasible. The idea of building the photovoltaic-Trombe wall has appeared as one of the green technologies. Several published works at that time are included for integrating PV/TW system. This chapter devoted to reviewing the theoretical and practical studies conducted on this system for developing and improving electrical and thermal performance

    Managing Service-Heterogeneity using Osmotic Computing

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    Computational resource provisioning that is closer to a user is becoming increasingly important, with a rise in the number of devices making continuous service requests and with the significant recent take up of latency-sensitive applications, such as streaming and real-time data processing. Fog computing provides a solution to such types of applications by bridging the gap between the user and public/private cloud infrastructure via the inclusion of a "fog" layer. Such approach is capable of reducing the overall processing latency, but the issues of redundancy, cost-effectiveness in utilizing such computing infrastructure and handling services on the basis of a difference in their characteristics remain. This difference in characteristics of services because of variations in the requirement of computational resources and processes is termed as service heterogeneity. A potential solution to these issues is the use of Osmotic Computing -- a recently introduced paradigm that allows division of services on the basis of their resource usage, based on parameters such as energy, load, processing time on a data center vs. a network edge resource. Service provisioning can then be divided across different layers of a computational infrastructure, from edge devices, in-transit nodes, and a data center, and supported through an Osmotic software layer. In this paper, a fitness-based Osmosis algorithm is proposed to provide support for osmotic computing by making more effective use of existing Fog server resources. The proposed approach is capable of efficiently distributing and allocating services by following the principle of osmosis. The results are presented using numerical simulations demonstrating gains in terms of lower allocation time and a higher probability of services being handled with high resource utilization.Comment: 7 pages, 4 Figures, International Conference on Communication, Management and Information Technology (ICCMIT 2017), At Warsaw, Poland, 3-5 April 2017, http://www.iccmit.net/ (Best Paper Award

    Coming into the Anthropocene

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    This essay reviews Professor Jonathan Cannon’s Environment in the Balance. Cannon’s book admirably analyzes the Supreme Court’s uptake of, or refusal of, the key commitments of the environmental-law revolution of the early 1970s. In some areas the Court has adapted old doctrines, such as Standing and Commerce, to accommodate ecological insights; in other areas, such as Property, it has used older doctrines to restrain the transformative effects of environmental law. After surveying Cannon’s argument, this review diagnoses the historical moment that has made the ideological division that Cannon surveys especially salient: a time of stalled legislation, political deadlock, and highly contested regulatory and judicial interpretation. This analysis, however, does not limit the interest of Cannon’s analysis to this political moment. Rather, Cannon’s integration of legal and cultural analysis has great promise for the Anthropocene, the dawning era when human decisions and values will be among the most important forces shaping the planet. In the future, it will be necessary to think of environmental law as both reflecting and producing ideas of the value and meaning of the natural world. Cannon’s analysis is an excellent starting point for an Anthropocene approach

    Cost Analysis of Multimodal Freight Transportation: A Case of Iskenderun

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    In this study from Iskenderun to the other Turkey's 80 cities to unimodal and multimodal freight transportation scenarios are being developed. Filter material which is widely used in Ä°skenderun is chosen for the freight. Highway, maritime and railway transport types are used in route scenarios. The costs of the route scenarios are calculated. Cost calculations are based on 5, 10 and 14 freight tonnage. For the value of the 5 ton freight is 40 000 TL, for the value of the 10 ton freight is 145 000 TL and for the value of the 14 ton freight is 250 000 TL. After the cost analysis is done, the most appropriate route for each province is selected and entered into the geographic information system (GIS). Thus, for freight from Iskenderun, the cheapest mode of transportation can be chosen. It is seen that railway and multimodal transport is widespread in general when the cheapest routes are examined. Thus, along with the shift of freight transport to rail and multimodal transport, traffic density on the highway can be reduced

    A Literature Review of Numerical Modeling Techniques for Vapor Compression Systems with Focus on Heat Exchanger Modeling

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    Vapor compression systems are the most widely used system type in heating, ventilation, air-conditioning, and refrigeration (HVAC&R) applications. Experimental and numerical modeling techniques are used to analyze the performance of the vapor compression systems. With the introduction of high-performance computers, numerical modeling techniques are used extensively to develop cost-effective and efficient HVAC&R equipment. Experimental iterations on the design of vapor compression systems are costly; however, numerical techniques can reduce the number of experimental iterations, substantially decreasing the development cost and time. Because of the benefits associated with the numerical simulation, many researchers working in the HVAC&R field have attempted to develop efficient, robust, and accurate simulation models. This paper provides an in-depth review of heat exchanger modeling techniques as well as integration strategies to develop holistic system models

    Feasibility of Controlling Heat and Enthalpy Wheel Effectiveness to Achieve Optimal Closed DOAS Operation

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    Dedicated outdoor air systems (DOAS) make use of the sensible and latent capacity of the return (exhaust) air to cool and dehumidify the supply (outside) air. “Closed DAOS” is an advanced form of typical DOAS with desuperheater and evaporatively cooled condenser in the return air stream. The air entering the condenser in Closed DOAS is in the fully saturated state. In order to fully saturate the return air, it needs to be sprayed by water. Sufficient amounts of water is required for fully saturating the air and keeping the coils of the condenser wet during the process. This water is obtained internally as a result of condensation on the evaporator fins, not requiring additional water use at the buildings site. Closed packaged configuration requires to have a water balance of water obtained in evaporator to that required for saturating the air and wetting the condenser coil. This water balance can be achieved under most conditions by an optimal control of enthalpy wheel and heat wheel (run around heat exchanger) effectiveness to control the amount of water obtained in the evaporator. The optimal control of heat and enthalpy wheel effectiveness is not only important for making the necessary water balance but also to keep the latent load as low as possible. This paper discusses the Closed DAOS configuration with psychrometrics and water balance analyses
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