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D. P. PAPADOPOULOS M. HAMED H. YASIN 《International journal of systems science》2013,44(11):2187-2197
This paper presents a mathematical model (algorithm) suitable for calculating the transfer function of a practical power network. For this network the steady-slate stability limits are derived and the non-linear characteristics of the transfer function are considered. The computational results obtained by using the proposed model differ from the corresponding ones obtained previously by approximate methods, whereas they are in close agreement with similar results obtained from experimental measurements. The oscillation coefficients of first- and second-order derivatives of the generator current highly characterize the performance of the locus diagram of the generator transfer function. The proposed accurate technique is applied to a part of the Egyptian power system consisting of a power station, a substation and a 500 kV double circuit transmission line. 相似文献
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MUSTAFA MOHAMMED NAJM MOHAMMED NAJM ABDULLAH AYA A. ALMUKHTAR BELAL AHMED HAMIDA MOH YASIN SULAIMAN WADI HARUN 《光电子快报》2023,19(11):681-685
This paper demonstrated a Q-switched erbium-doped fiber laser (EDFL) using an organic saturable absorber (SA) based on 8-HQCdCl2H2O material. The organic thin film was prepared using the casting process. The proposed Q-switched EDFL has a maximum repetition rate of 143 kHz, minimum pulse duration of 1.85 µs and the highest pulse energy of 167 nJ. The Q-switched peak laser was at a central wavelength of 1 531 nm with a 3 dB bandwidth of 3.52 nm and power intensity of 2.64 dBm. 相似文献
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Kinetical, morphological, crystallographical and thermal characteristics of thermally induced martensite in an Fe–30%Ni–1%Pd alloy has been studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction method. Kinetics of transformation was found to be as athermal. SEM and TEM observations and X-ray method revealed α′ (bcc) martensite formation in the austenite phase of alloy by thermal effect. The crystallographic orientation relationship between austenite and α′ (bcc) martensite was found to be having Kurdjumov–Sachs (K–S) type relationship. In addition, the lattice parameters of austenite and martensite phases were calculated from X-ray diffraction patterns. 相似文献
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砂土应力路径不相关的修正塑性功硬化 参量与函数 总被引:4,自引:1,他引:3
砂土的变形强度特性明显存在着应力路径效应,因此在砂土的弹塑性本构建模时硬化参数和函数的选取并不是一个简单的事情.针对砂土的这一特性,用密实砂土进行一系列多应力路径的平面应变压缩试验.试验结果表明,所有的应变增量(例如轴向、横向、剪切以及体积应变等增量)及塑性功增量都与应力路径具有较大的相关性,因而在传统的砂土弹塑性分析中利用以上任何一个状态量作为硬化参数并假设其与应力路径不相关是不合理的.基于广泛的多应力路径平面应变压缩试验结果以及细致的数据处理分析,发现一个特殊的修正塑性功参量以及相关的函数,它们与应力路径不相关,因此在砂土的弹塑性解析中假定它们作为硬化参量和函数是与理论假设一致的.理论计算结果与室内试验相比较表明,利用提出的修正塑性功作为硬化参数和硬化函数所构成的砂土的弹塑性模型可以很好地模拟砂土材料变形及强度的应力路径效应. 相似文献
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A rapid Fourier transform infrared (FTIR) spectroscopic technique coupled with fixed NaCl cell (1 mm pathlength) was developed to measure peroxide value (PV) in crude palm oil (CPO) and crude palm kernel oil (CPKO). Calibration standards were prepared by oxidizing CPO in a fermentor at 60C over a period of 24 h. A partial least squares (PLS) calibration model for predicting PV was developed based on the 3710–3210 cm-1 spectral region with reference to a single-point baseline at 3710 cm-1 . The optimization of calibration factors was guided by the predicted residual error sum of squares (PRESS) test. The standard deviation (SD) of the calibration obtained was 0.46 PV over the range of 0.51–17.82 PV and the correlation coefficient (R2) was 0.998. The model was validated with an independent set of samples consisting of both laboratory and field samples. The overall SD for the validation set was sligthly higher (SD = 1.46 PV) with R2 of 0.989. Thus, it was demonstrated that PV measured by FTIR techniques was comparable to that obtained by the chemical method. The FTIR method has the 相似文献
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BACTERICIDAL EFFECT OF FREEZING WITH CHEMICAL AGENTS 总被引:2,自引:0,他引:2
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采用溶胶-凝胶方法和表面分子印迹技术,以二氧化硅为载体,鞣花酸为模板分子,3-氨丙基三乙氧基硅烷为功能单体,四乙氧基硅烷为交联剂,在室温下合成鞣花酸分子印迹聚合物(MIPs)。通过扫描电镜表征了MIP的表面形貌。通过静态吸附实验评价了MIP对鞣花酸的吸附行为。结果显示,MIP对鞣花酸可在40 min内达到吸附平衡,印迹因子为2.68,饱和吸附容量可达70 mg/g;与非印迹聚合物相比,MIP对鞣花酸具有高选择性和特异识别性。对吸附数据进行非线性拟合结果显示,MIP对鞣花酸的吸附动力学较好地符合准二级动力学模型,MIP对鞣花酸的吸附等温线较好地符合Langmuir等温方程。另外,该材料在经过5次循环利用之后,对鞣花酸的吸附容量仍能保持在90%以上,表现了较好的重复利用性能。所合成的MIP能够作为一种良好的选择性吸附鞣花酸的功能材料,有望应用于复杂基质中鞣花酸的分离和纯化。 相似文献
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针对现有的水凝胶类堵剂无法满足塔河缝洞型油藏孔隙结构复杂、裂缝尺寸不均一、超高温及超高矿化度等极端环境和条件的情况,以硫磺和棉籽油为基本原料制备了密度、硬度可调的高温可自黏橡胶堵剂,研究了其耐温性、黏结性、油溶性、强度以及堵水性能。结果表明,其密度和硬度分别可在1.10数1.30 g/cm^3和17数40度间调控;该橡胶能溶于原油、甲苯而与地层水分层不互溶,具有误堵油层时可解封堵性;裂缝型油藏物理模型测试结果表明,在110℃时,当颗粒粒径和裂缝宽度之比为1∶2.5的时候其堵水效果最佳,堵水率达94.9%。本工作为硫磺副产物的利用以及密度可调、柔性颗粒类堵水剂的设计和制备提供新思路。图8表2参11。 相似文献