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991.
992.
993.
通过全三元射流-尾迹流动计算得出定量分析,改善叶轮内流动状态,减少进口冲击和出口尾迹脱流等损失,使水泵效率得以提高,真正达到节能降耗之目的。 相似文献
994.
Mean wind pressure coefficients (Cp) are key input parameters for air infiltration and ventilation studies. However, building energy simulation and stand-alone airflow network programs usually only provide and/or use a limited amount of Cp data, which are based on several assumptions. An important assumption consists of using surface-averaged Cp values instead of local Cp values with a high resolution in space. This paper provides information on the uncertainty in the calculated airflow rate due to the use of surface-averaged Cp data. The study is performed using published empirical data on pressure coefficients obtained from extensive wind tunnel experiments. The uncertainty is assessed based on the comparison of the airflow rate (?) calculated using the surface-averaged Cp values (?AV) and the airflow rate calculated using local Cp values (?LOC). The results indicate that the uncertainty with a confidence interval of 95% is high: 0.23 ?AV < ?LOC < 5.07 ?AV. In cases with the largest surface-averaged ΔCp, the underestimation or overestimation is smaller but not negligible: 0.52 ?AV < ?LOC < 1.42 ?AV. These results provide boundaries for future improvements in Cp data quality, and new developments can be evaluated by comparison with the uncertainty of the current methods. 相似文献
995.
纪念馆兼有文化性和时代性,它既要强调文化传统和当地文脉,又要体现展览建筑的时代特色。建筑设计应注重简洁、朴实和高品格,而不在于材料、装修的豪华及过分做作的造型。该方案设计采用覆土建筑形式,同时与生态、节能联系在一起,充分利用建筑空间,营造宜人的展览氛围。 相似文献
996.
浅谈地源热泵在医院建筑中的应用 总被引:1,自引:0,他引:1
随着人们保健意识的日益提高,人们自然对医疗环境的要求也相应提高,对于现代化医疗建筑建设者来讲,营造生态保健型绿色医院就成为我们的努力方向,在现代医院建筑中引入绿色节能的地源热泵技术,使医院真正成为人类和谐舒适,环境优美,绿色生态的现代化疗养场所。因此,地源热泵系统在现代医院建筑中具有很大的应用价值,它将成为我国医院建筑节能领域重点推广的技术之一。 相似文献
997.
P. NagendraAuthor Vitae Sunita Halder nee DeyAuthor VitaeSubrata PaulAuthor Vitae 《International Journal of Electrical Power & Energy Systems》2011,33(3):737-744
The equivalent two-bus network models currently available are obtained by lumping all the series impedances and shunt admittances of transmission lines within a series equivalent impedance, to assess voltage stability of multi-bus power system. This paper reports the development of an equivalent pi-network model using a new methodology considering series and shunt parts of line loss separately obtained from the operational parameters of optimal power flow solution of the original multi-bus power network, which can be applied to assess the overall voltage stability status of the system accurately by developing the concept of a generalized global voltage stability margin (GVSM). Simulation results for a typical longitudinal power supply (LPS) system and a robust practical (Indian Eastern Grid) system establish that the pi-equivalent model obtained by the proposed method is highly promising for assessing voltage stability of any power system at any operating point in global scenario in a better way as compared to available series equivalent model. Continuation power flow (CPF) method has also been adopted here to verify the potential of the proposed method for voltage stability assessment. In the proposed equivalent network the generators have been modeled more accurately considering optimal operating criteria. 相似文献
998.
Jong-Yul Kim Kyeong-Jun MunHyung-Su Kim June Ho Park 《International Journal of Electrical Power & Energy Systems》2011,33(8):1457-1461
In recent studies, PSO algorithm is applied to solve OPF problem. However, population based optimization method requires higher computing time to find optimal point. This shortcoming is overcome by a straightforward parallelization of PSO algorithm. The developed parallel PSO algorithm is implemented on a PC-cluster system with 8 Intel Pentium IV 2 GHz processors. The proposed approach has been tested on the test systems. The results showed that computing time of parallelized PSO algorithm can be reduced by parallel processing without losing the quality of solution. 相似文献
999.
H. Falaghi C. Singh M.-R. Haghifam M. Ramezani 《International Journal of Electrical Power & Energy Systems》2011,33(8):1489-1497
In this paper, a framework is presented to solve the problem of multistage distribution system expansion planning in which installation and/or reinforcement of substations, feeders and distributed generation units are taken into consideration as possible solutions for system capacity expansion. The proposed formulation considers investment, operation, and outage costs of the system. The expansion methodology is based on pseudo-dynamic procedure. A combined genetic algorithm (GA) and optimal power flow (OPF) is developed as an optimization tool to solve the problem. The performance of the proposed approach is assessed and illustrated by numerical studies on a typical distribution system. 相似文献
1000.
Ruey-Hsun Liang Sheng-Ren TsaiYie-Tone Chen Wan-Tsun Tseng 《Electric Power Systems Research》2011,81(7):1466-1474
This paper presents a fuzzy based hybrid particle swarm optimization (PSO) approach for solving the optimal power flow (OPF) problem with uncertainties. Wind energy systems are being considered in the study power systems. OPF is an optimization problem which minimizes the total thermal unit fuel cost, total emission, and total real power loss while satisfying physical and technical constraints on the network. When performing the OPF problem in conventional methods, the load demand and wind speed must be forecasted to prevent errors. However, actually there are always errors in these forecasted values. A characteristic feature of the proposed fuzzy based hybrid PSO method is that the forecast load demand and wind speed errors can be taken into account using fuzzy sets. Fuzzy set notations in the load demand, wind speed, total fuel cost, total emission, and total real power loss are developed to obtain the optimal setting under an uncertain environment. To demonstrate the effectiveness of the proposed method, the OPF problem is performed on the IEEE 30- and 118-Bus test systems. 相似文献