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排序方式: 共有681条查询结果,搜索用时 15 毫秒
51.
This paper describes the formulation of a model for optimized crop and water planning decisions in an irrigation system in Thailand. It facilitates consultation in which representatives of stakeholders, officials, farmers, and researchers can contribute to the decision making. Linear programming and the analytical hierarchy process are the principal modeling tools to optimize the collective system objectives: productivity, equity, and security. The results of the model are compared with observed events of one dry season. The optimized policy generated by the model suggested a diversified cropping pattern, which would decrease the water requirement by 16.4% and enhance net benefit per cubic meter of water used by 39.9%. The erratic water availability from the reservoir and the operational procedures inside the system are reviewed, analyzing historical data in terms of reliability, resiliency, and vulnerability. These include lack of proper assessment of available water, effective farmer organization, and prompt data processing and communication. Furthermore, for the effective implementation of an optimized irrigation policy, a water release pattern of the storage reservoir has been suggested. 相似文献
52.
A lecture theatre with dimension 16 m × 8.4 m × 3.6 m located at Roorkee (28.58°N, 77.20°E) in the northern region of India, is selected to calculate the monthly and annual cooling load (kWh) and cooling capacity of air conditioning system by a computer simulation. The paper also presents the results of a study investigating the effect of different glazing systems on windows and the reduction in building cooling load. DesignBuilder software has been used for the computer simulation for calculating the cooling load. The paper aims to investigate the reduction in thermal gains and cooling load requirements by varying the U-values of different glazing types, insulating the ceiling, providing cool roofs, interior and exterior insulation on walls, and replacing the conventional fluorescent tube lamp (FTL) by energy efficient compact fluorescent lamp (CFL). Installation of false ceiling, wall insulation, different glazing types and lighting systems are cost effective with normalized annual saving ranging from 17% to 19.8% from this retrofitting project. Furthermore, the study also highlights the potential of reducing the emission of CO2 and equivalent carbon credit. Retrofitting techniques strongly influence the level of energy saving, although the payback period is generally quite long of order 8 years. 相似文献
53.
In this paper we consider the problem of distributed fault diagnosis in Wireless Sensor Networks (WSNs). The proposed Fault Diagnosis Algorithm (FDA) aims to handle both permanent and intermittent faults. The sensor nodes with permanent communication faults can be diagnosed by using the conventional time-out mechanism. In contrast, it is difficult to detect intermittent faults due to their inherent unpredictable behavior. The FDA is based on the comparison of sensor measurements and residual energy values of neighboring sensor nodes, exploiting their spatial correlations. To handle intermittent faults, the comparisons are made for \(r\) rounds. Two special cases of intermittent faults are considered: one, when an intermittently faulty node sends similar sensor measurement and similar residual energy value to some of its neighbors in all \(r\) rounds; another, when it sends these values, either or both of which deviates significantly from that of some neighbors in all \(r\) rounds. Through extensive simulation and analysis, the proposed scheme is proved to be correct, complete, and efficient to handle intermittent faults and hence, well suited for WSNs. 相似文献
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Dichalcogenides with the common formula MX(2) are layered materials with electrical properties that range from semiconducting to superconducting. Here, we describe optimal imaging conditions for the optical detection of ultrathin, two-dimensional dichalcogenide nanocrystals containing single, double and triple layers of MoS(2), WSe(2) and NbSe(2). A simple optical model is used to calculate the contrast for nanolayers deposited on wafers with varying thicknesses of SiO(2). The model is extended for imaging using the green channel of a video camera. Using AFM and optical imaging we confirm that single layers of MoS(2) and WSe(2) can be detected on 90 and 270 nm SiO(2) using optical means. By measuring contrast under broadband green illumination we are also able to distinguish between nanostructures containing single, double and triple layers of MoS(2) and WSe(2.) We observe and discuss discrepancies in the case of NbSe(2). 相似文献
56.
R. Sahoo 《Particulate Science and Technology》2005,23(3):285-296
Single-particle breakage tests of South Blackwater and Ensham coal from the Bowen Basin area in Queensland were conducted by a computer-monitored twin-pendulum device to measure the energy utilization pattern of the breakage particles. Three particle sizes (-16.0 + 13.2 mm, -13.2 + 11.2 mm, -11.2 + 9.5 mm) of each coal were tested by a pendulum device at five input energy levels to measure the specific comminution energy. When particles were tested at constant input energy, the variation of comminution energy between the same size broken particles of Ensham coal was minimal, because Ensham coal is a softer and higher friability coal, which absorbs more input energy than harder coal during breakage tests. For different particle sizes, the specific comminution energy increases linearly with the input energy and the fineness of the breakage products increases with the specific comminution energy.The size distribution graphs are curved but approach linearity in the finer region. At a constant input energy, the twin pendulum breakage product results show that the fineness of the products increases with decrease in particle size and South Blackwater coal produced finer products than the Ensham coal. The t-curves are the family of size distribution curves, which can describe the product size distribution of the breakage particles during single-particle breakage tests. 相似文献
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Graft copolymerization of methyl methacrylate (MMA) onto cotton–cellulose has been carried out using hexavalent chromium Cr(VI) as initiator. Aqueous-methanolic solution of perchloric acid has been chosen as the reaction medium. The effect of monomer, initiator, acid, reaction medium, and temperature on the graft percentage has been found out. The reactions have also been carried out in the presence of polymerization, inhibitors, and retarders, such as hydroquinone and transition metal salts like CuSO4, FeCl3, etc. The grafted samples, after exhaustive separation of homopolymers and purification, were subjected to various chemical, mechanical, and thermal testings. The results of various analyses have been compared with the reference, and the improvement in the graft has been evaluated. A suitable mechanism for the grafting processes has been suggested, in accordance with the experimental results. 相似文献
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