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排序方式: 共有169条查询结果,搜索用时 15 毫秒
1.
This paper presents a fast distance relay for series compensated transmission lines based on the R–L differential-equation algorithm using the theory of equal transfer process of transmission lines. The measuring distances based on the proposed algorithm can fast approach the actual value of fault distance when a fault occurs in front of the series capacitor. When a fault occurs behind of the series capacitor, the fault loop, including the series capacitor, does not match the R–L transmission line model, so the measuring distances fluctuate severely. Based on this, the relative position of the fault with respect to the series capacitor can be judged effectively according to the fluctuation range of the measuring distances, and the accurate fault location can be obtained fast. A variety of PSCAD/EMTDC simulation tests show that the new relay has fast operating speed and high accuracy when applied to the long series compensated transmission lines. 相似文献
2.
《Journal of the European Ceramic Society》2006,26(9):1701-1706
In present study, dense CaSiO3 (CS) ceramics have been fabricated through spark plasma sintering (SPS) technique using β-CS powder prepared by chemical precipitation method. The β-CS ceramic sintered at 950 °C has a relative density of about 95% and shows a fine microstructure with an average grain size of 0.6 μm, thus expresses good bending strength of about 294 MPa. The simulated body fluid (SBF) immersion tests show that the dense β-CS ceramic has a high hydroxyapatite (HAp) formation rate on its surface. The HAp layer formed on the CS ceramic surface has a granular structure consisting of silkworm-like HAp grains, and the thickness of HAp and Si-rich layer are 70 and 120 μm, respectively. 相似文献
3.
Meysar Zeinali Amir Khajepour 《Engineering Applications of Artificial Intelligence》2010,23(8):1408-1419
The precision, performance, and robustness of model-based controllers depend, to a large extent, on the accuracy of the inverse dynamic model which is incorporated in the design of the controller. Due to complex nature of the laser cladding process and presence of time-varying uncertainties, derivation of an accurate mathematical inverse dynamic model of the process is very difficult, and involves many unknown parameters. The inverse dynamic model of the complex nonlinear laser cladding process, which is difficult to be described mathematically, can be described by a fuzzy logic-based inverse dynamic model constructed form input–output data. In this paper, the development of an adaptive fuzzy inverse dynamic model of the laser cladding process, using a systematic fuzzy modelling approach is presented. In a closed-loop laser cladding process, the scanning speed of the substrate is required to produce a clad with desired geometry and quality. In this paper, a fuzzy inverse dynamic model that describes the scanning speed as a function of the cladding parameters in particular the clad height is developed. The developed fuzzy model is validated by comparing the model output with experimental data. The results are very promising and show that fuzzy models can accurately describe the process dynamics. 相似文献
4.
将图像形态学处理和计算机辅助诊断方法应用于无线内窥镜出血图像检测。在对无线内窥镜图像进行形态学处理和超像素分割的基础上,提出红色纯度特征,应用最小二乘支持向量机分类器对分割后的图像进行分类。试验结果表明,该方法能够有效地检测无线内窥镜图像中的出血区域,敏感性、特异性和准确率分别达到了99%、94%和95%,可以作为临床医生的辅助诊断工具。 相似文献
5.
The use of lubricant is the key of warm compaction technology. Because of admixed different lubricants, the optimal parameters of warm compaction process were also different. This paper investigated the effect of two kind of lubricants (zinc stearate and polystyrene) on the parameters of warm compaction process by compared properties of Cu-based composite. It was shown that with the rise of compacting pressure, the density and hardness of the Cu-based composite increased, but the resistivity and gaining weight reduced. With increasing compacting temperature, the density and hardness first increased and then decreased, but the trend of resistivity and gaining weight just reversed. For the samples admixed zinc stearate (ZS), the optimal admixed concentration was 0.4 wt%, and the sample prepared at 120 °C and 650 MPa had the highest density and hardness, the lowest resistivity and gaining weight. For the samples admixed polystyrene (PS), these parameters were 0.7 wt%, 140 °C and 650 MPa, respectively. The properties of samples admixed PS were superior to that of admixed ZS. 相似文献
6.
A multi-factor comprehensive risk assessment method of karst tunnels and its engineering application
Bulletin of Engineering Geology and the Environment - The tunnel collapse, a large deformation of surrounding rock, water and mud inrush are the main geological disasters in the process of tunnel... 相似文献
7.
《Ceramics International》2017,43(16):13089-13093
A series of CaF2:xEu3+ (x = 0.01–0.05) phosphors were synthesized by coprecipitation and high temperature solid-state method. Three different F--Eu3+ charge transfer (CT) bands in CaF2:xEu3+ (x = 0.01–0.05) were detected through the PL spectra. Three local crystal environments (deformed Oh octahedron, C3V, C4V) were proposed in Eu3+ doped CaF2. The broad peak at 277 nm is F- → Eu3+ CT peak, in which Eu3+ ions located deformed Oh octahedron sites, the broad peak at 312 nm is due to Eu3+ ions situating at C4v sites, also, Eu3+ ions with C3v sites can make the F- → Eu3+ CT produce a 38-nm redshift to 315 nm. Density functional theory (DFT) was performed to calculate the energy band gap(Eg) according to the three models. The calculation results consist with the experiment. The excitation peaks can be tuned in the same host through changing the local structure of Eu3+. 相似文献
8.
This work assesses the participation of wind power plants in primary frequency control support. To participate in frequency control-related tasks, the wind power plants have to maintain a certain level of power reserves. In this article, the wind power plant is equipped with a flywheel-based storage system to fulfil the power reserve requirements set by the network operator. The article focuses on two main aspects: the definition of the control strategy to derate the wind turbines to provide a part of the required power reserves; and the coordinated regulation of the power reserves of the wind turbines and the flywheels while participating in primary frequency control. This coordinated regulation enables the wind power plant to maintain the net level of power reserves set by the network operator while alleviating the need of deloading the wind turbines. The performance of the proposed control schemes are shown by simulation. 相似文献
9.
10.
近年来,电石渣在燃煤电厂干法脱硫工艺的应用中取得了较多进展,但在湿法脱硫的应用中仍存在消溶特性差、亚硫酸钙氧化率低、石膏脱水困难等诸多问题,导致其难以大规模推广。本文从电石渣的理化性质出发,分析了孔隙结构、反应温度、Ca/S摩尔比对脱硫效率的影响,并探讨了电石渣作为脱硫剂对循环流化床锅炉效率及运行的影响,结合电石渣的消溶特性、浆液氧化特性及石膏脱水特性,分析了电石渣在湿法脱硫工艺应用中存在的问题,提出了一种以电石渣为原料,利用燃煤机组再生水深度处理系统生产石灰石浆液的工艺路线,并在2×660MW超超临界燃煤机组再生水深度处理系统中进行了可行性试验,当Ca(OH)2纯度≥95%时,合理的污泥掺配比例区间为50%~70%,所产石膏达到了二级石膏的品质要求。 相似文献