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141.
Sami Karaki Mithqal Sartawi Anan Hamdan Najah Al-Hafi 《Electric Power Systems Research》1985,9(2):133-139
The Interactive Power Transmission Planning (IPTP) package developed at the Kuwait Institute for Scientific Research comprises a security assessment program so the network planning engineer can test the technical feasibility of a given network and a sensitivity analysis program that indicates to the planner the best line to reinforce. These basic computational planning facilities are presented to the engineer through special software using interactive computing and computer graphics. The package is devised so that it can be used by engineers with limited computer programming and numerical analysis skills. 相似文献
142.
In this paper, we propose a method of analytically calculating an impedance of a thyristor‐controlled series capacitor (TCSC). The TCSC consists of a thyristor‐controlled reactor (TCR) and a capacitor. If a small voltage component of frequency f superimposes the TCSC voltage of frequency fo, then current components of frequency (nfo ± f) flow through the TCR, where n takes even numbers. We derive theoretical equations for them. In the derivation, we consider an influence of odd harmonics in the TCSC voltage. We also consider deviations in its zero‐crossing times due to the superimposed voltage. The current components flow through the capacitor and the transmission line, and produce new voltage components of frequency (nfo ± f). In order to count their influence, we introduce admittance matrices for the TCR, the capacitor, and the transmission line. By solving a network equation consisting of the matrices, we can obtain the distribution of the voltage and current components. We define the impedance of TCSC as a ratio of the voltage component of frequency f to the current one of the same frequency. The impedance analytically obtained corresponds well with that obtained by simulations. Its frequency responses vary with the firing method of thyristors. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 35–44, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.1158 相似文献
143.
M Macchia F Salvetti S Barontini F Calvani M Gesi M Hamdan A Lucacchini A Pellegrini P Soldani C Martini 《Canadian Metallurgical Quarterly》1998,8(22):3223-3228
New fluorescent ligands for adenosine receptors are described; these compounds were obtained by the insertion, in the N6 position of NECA (a potent adenosine agonist), of dansylaminoalkyl moieties with alkyl spacers of increasing carbon chain length (from 3 to 12). Among them, the compound with a C6 alkyl spacer proved to be the most interesting one, showing a marked selectivity for the A1 receptor subtype; furthermore, in fluorescence microscopy assays it proved to be able to visualize and localize this receptor subtype at the level of the molecular layer of the rate cerebellar cortex. 相似文献
144.
The superconductor thermal stability is investigated under the effect of the dual-phase-lag heat conduction model. Two types of superconductors are considered, Types I and II. It is found that the dual-phase-lag model predicts a wider stable region as compared to the predictions of the parabolic and the hyperbolic heat conduction models. Also, the superconductor thermal stability under the effect of different design, geometrical and operating conditions is studied. 相似文献
145.
The thyristor‐controlled series capacitor (TCSC) is being developed to improve the transmission capability of power systems. The TCSC is thought to compensate transmission line reactance without causing subsynchronous resonance (SSR). However, in order to evaluate its effect quantitatively, we must calculate the frequency response of the generator damping torque. Simulations need a long computing time, and it is hard to choose the frequency freely. In this paper, we propose a method of analytically calculating the damping torque. First, when a generator rotor oscillates at some frequency, two voltage components appear. We analytically calculate the damping torque from small current variations due to the voltage components. The damping characteristic changes depending on the method of firing thyristors. The best characteristic is obtained when triggering with reference to the fundamental wave of TCSC voltage or current is used. By choosing an appropriate firing angle, we can drastically reduce negative damping by the TCSC. The damping characteristic is closely related to the system impedance. The fact that the TCSC has large resistance in the 0 to 60 Hz range helps significantly in improving the characteristic. Lastly, numerical simulations of SSR are used to examine the validity of our investigation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 39–49, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10068 相似文献
146.
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148.
Diversity and antifungal susceptibility of yeasts from tropical freshwater environments in Southeastern Brazil 总被引:1,自引:0,他引:1
Medeiros AO Kohler LM Hamdan JS Missagia BS Barbosa FA Rosa CA 《Water research》2008,42(14):3921-3929
Yeast communities were isolated from water and sediment samples of two unpolluted natural lakes, located inside Rio Doce State Park, and two rivers located outside of this Park in Southeastern Brazil. A total of 134 yeast isolates were obtained and identified as belonging to 36 species. The numbers of fecal coliforms and yeast species were higher in rivers than in lakes. The genus Candida had the highest number of species with the presence of opportunistic pathogens such as Candida krusei, C. tropicalis, C. guilliermondii and C. parapsilosis. Yeasts able to grow at 37 degrees C were tested in relation to their susceptibility to common used antifungal drugs. Yeast isolates (13%) were susceptible to ketoconazole, 79% to fluconazole, 31% to terbinafine and 78% of the strains were susceptible to amphotericin B. Seven isolates from different Candida species were resistant to all antifungals tested. The high number of fecal coliforms found in these aquatic environments and the presence of resistant yeast strains to common used antifungal drugs suggest that these environments can pose potential health risks for people utilizing the contaminated waters. 相似文献
149.
针对传统小差比率制动系数校验方法存在校验结果可能不准确的问题,从固定相位调节幅值校验方法出发,得到了其简化的等价模型,并根据校验需满足的条件,提出了一种小差比率制动系数校验新方法。该方法能保证校验过程中所测小差比率系数是母差差动动作所需满足条件中最后一个满足的条件,从而保证测得的小差比率系数必定是装置实际的小差比率制动系数门槛值。通过对常规比率差动的RCS-915AB装置和复式比率差动的BP-2CS装置的现场调试和校验,验证了所提方法的有效性和正确性。 相似文献
150.
T. V. Aksenova M. V. Anan’ev L. Ya. Gavrilova V. A. Cherepanov 《Inorganic Materials》2007,43(3):296-300
The composition region and structure of La1?x Sr x Co1?y Fe y O3?δ solid solutions are determined by x-ray powder diffraction using the Rietveld profile analysis method. The solid solutions based on lanthanum cobaltite, LaCoO3?δ, have a rhombohedrally distorted perovskite-like structure (sp. gr. R \(\bar 3\) c), and those based on lanthanum ferrite, LaFeO3?δ, have an orthorhombically distorted structure (sp. gr. Pbnm). The rhombohedral distortion decreases with increasing strontium content, and the solid solutions with x ≥ 0.5 have an ideal cubic structure (sp. gr. Pm3m). The composition dependences of lattice parameters for the La1?x Sr x Co1?y Fe y O3?δ solid solutions are presented, and the 1100°C isotherm of the LaCoO3?δ-SrCoO2.5±δ-SrFeO3?δ-LaFeO3?δ system in air is constructed. 相似文献