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排序方式: 共有345条查询结果,搜索用时 15 毫秒
71.
基于传输线原理,构建了均匀分布在单位球表面的入射波用于模拟混响室内"全向辐照"的电磁辐照模型,并利用Agrawal散射电压公式计算双导线传输线模型的终端负载响应电流。研究了均匀分布在球面入射波的入射方向、极化方向以及入射波数量对传输线终端响应的影响,并将数值计算结果与蒙特卡罗方法的计算结果进行对比。结果表明:分布在球面上的电磁波入射角为0~π、极化角度为0~π时,即可满足响应信号的数值完整性;入射电磁波数量达到100时,能够满足混响室内"全向辐照"的要求;理论模型计算结果与蒙特卡罗方法的计算结果吻合较好,该模型可以用于混响室内散射场场线耦合规律计算。 相似文献
72.
In the present study, nonaqueous capillary electrophoretic separation of imatinib mesylate (IM) and related substances, N-(5-amino-2-methylphenyl)-4-(3-pyridyl)-2-pyrimidinamine (PYA), N-(4-methyl-3-(4-(pyridin-3-yl)pyrimidin-2-ylamino)phenyl)-4-((piperazin-1-yl)methyl) benzamide (NDI) and 4-chloromethyl-N-(4-methyl-3-((4-(pyridin-3-yl) pyrimidin-2-yl) amino) phenyl) benzamide (CPB) was developed. The influential factors affecting separation, including type and concentration of the electrolyte, applied voltage, and buffer modifier were investigated. Baseline separation of the studied analytes was obtained using a buffer of 50 mM Tris and 50 mM methanesulfonic acid in methanol at a apparent pH (pH*) of 1.65. To enhance the sensitivity, large-volume sample stacking was employed for online concentration. The strongest analytical signal with a suitable separation was achieved when the injection time was 100 s. The linearity ranges of PYA and NDI were 0.100-2.50 μg mL(-1) , and that of CPB was 0.125-2.50 μg mL(-1) , with good coefficients (r(2) > 0.9948). The relative standard deviations of intra- and interday were satisfactory. Under the optimized conditions, seven batches of the synthesized samples were analyzed and CPB was detected in two batches. Owing to its simplicity, effectiveness, and low price, the developed method is promising for quality control of IM. 相似文献
73.
Pachfule P Chen Y Jiang J Banerjee R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(2):688-694
The synthesis, structure, and gas adsorption properties of three new metal-organic frameworks (MOFs) designed from isonicotinic acid (INA) and its fluorinated analogue 3-fluoroisonicotinic acid (FINA) along with Co(II) as the metal center have been reported. Co-INA-1 ([Co(3)(INA)(4)(O)(C(2)H(5)OH)(3)][NO(3)]·C(2)H(5)OH·3H(2)O; INA=isonicotinic acid) and Co-INA-2 ([Co(INA)(2)]·DMF) are structural isomers as are Co-FINA-1 ([Co(3-)(FINA)(4)(O)(C(2) H(5) OH)(2)]·H(2)O; FINA=3-fluoroisonicotinic acid) and Co-FINA-2 ([Co(FINA)(2)]·H(2)O), but the most important thing to note here is that Co-INA-1 and Co-FINA-1 are isostructural as are Co-INA-2 and Co-FINA-2. The effect of partial introduction of fluorine atoms into the framework on the gas uptake properties of MOFs having similar structures has been analyzed experimentally and computationally in isostructural MOFs. 相似文献
74.
In biochemical reaction systems dominated by delays, the simulation speed of the stochastic simulation algorithm depends on the size of the wait queue. As a result, it is important to control the size of the wait queue to improve the efficiency of the simulation. An improved accelerated delay stochastic simulation algorithm for biochemical reaction systems with delays, termed the improved delay-leaping algorithm, is proposed in this paper. The update method for the wait queue is effective in reducing the size of the queue as well as shortening the storage and access time, thereby accelerating the simulation speed. Numerical simulation on two examples indicates that this method not only obtains a more significant efficiency compared with the existing methods, but also can be widely applied in biochemical reaction systems with delays. 相似文献
75.
Much attention has been paid to construct an applicable knowledge measure or uncertainty measure for Atanassov’s intuitionistic fuzzy set (AIFS). However, many of these measures were developed from intuitionistic fuzzy entropy, which cannot really reflect the knowledge amount associated with an AIFS well. Some knowledge measures were constructed based on the distinction between an AIFS and its complementary set, which may lead to information loss in decision making. In this paper, knowledge amount of an AIFS is quantified by calculating the distance from an AIFS to the AIFS with maximum uncertainty. Axiomatic properties for the definition of knowledge measure are extended to a more general level. Then the new knowledge measure is developed based on an intuitionistic fuzzy distance measure. The properties of the proposed distance-based knowledge measure are investigated based on mathematical analysis and numerical examples. The proposed knowledge measure is finally applied to solve the multi-attribute group decision-making (MAGDM) problem with intuitionistic fuzzy information. The new MAGDM method is used to evaluate the threat level of malicious code. Experimental results in malicious code threat evaluation demonstrate the effectiveness and validity of proposed method. 相似文献
76.
一类线性约束凸规划的内椭球算法 总被引:3,自引:0,他引:3
1引言自从1984年Karmarkar的著名算法——梯度投影算法发表以来,由其理论上的多项式收敛性及实际计算的有效性,使得内点算法成为近十几年来优化界研究的热点([1]).通过中外学者的深入研究,线性规划与凸二次规划的内点算法研究已取得了不少成果([2」、[3〕).这些算法大致可分为四种类型:梯度投影算法、仿射尺度算法、路径跟踪法和势函数减少法吸3]、〔9〕).近来,人们开始着手将这些方法推广到非线性规划中的凸规划问题、线性互补问题和非线性互补问题(【6」、[7」、〔sj、[10」、Ill〕).例如:文[8」对一类凸可分规… 相似文献
77.
提出了一种基于共形网格技术的共形单步交替方向隐式时域有限差分(CLeapfrog ADI-FDTD)方法。与常规FDTD方法相比,此方法能够减小由于目标边界不契合网格划分而引入的阶梯近似误差,提高算法计算不规则目标时的精度;同时算法稳定性更强,计算效率更高。由于引入共形技术后显著降低了原差分法的无条件稳定性,本文利用增长矩阵本征值方法理论分析了算法的稳定性,然后采用了一种改进的共形面积计算方法,在此基础上提出了一种稳定性更高的改进的共形单步交替方向隐式时域有限差分(ICLeapfrog ADI-FDTD)方法。数值算例验证了ICLeapfrog ADI-FDTD是一种具有高稳定性和高精度的高效算法。 相似文献
78.
提出了一种求解传输线方程的高精度龙格-库塔(RK)方法。此方法在空间上采取高阶泰勒展开,提高了对空间微分的近似精度,减少了数值色散所带来的误差。与传统的时域有限差分法(FDTD)方法相比,在每波长采样数相同时,RK方法的计算精度更高。同时,根据Taylor模型,对外界平面波激励源进行离散,成功利用RK方法对外部场激励传输线进行求解,扩大了龙格−库塔方法在求解传输线方程时的应用范围。通过编程对平面波辐照下无限大地平面上的单导体与双导体的算例分别应用FDTD方法与RK方法进行了计算,验证了RK方法的正确性。结果表明同等计算条件下RK方法的计算精度更高。 相似文献
79.
在全球治理危机频现和大国战略竞争加剧的背景下,“国家中心主义”回归引发了人们对经济全球化走势的担忧。本轮国家中心主义回归的逻辑是:此前自由主义全球化的过度发展导致国家功能隐退;而当全球治理状况恶化时,国家的重要性再度凸现,成为各国社会谋求自我体系安全的唯一“阀门”,民族主义、保护主义思潮亦大行其道。从中期看,未来的全球体系重建过程将充满国家中心主义与自由主义两种理性的持续角力,国家与市场的作用都将在“拉锯战”相互影响与重塑。从远期看,新型全球化将是国家与市场关系再平衡的产物,国家仍是兼具服务本民族发展及其外部性的主要工具。国家处理内外发展与治理多重挑战的“灵活度”即为评判其核心竞争力的最终标准。 相似文献
80.
The double-layer penetration electrode structure is proposed to obtain the low-operating voltage blue-phase liquid crystal display (BPLCD) with single electro-optic curve for red-green-blue (RGB) colours in every pixel, which is more suitable for the field-sequential-colour display. The different influences of electrode’s parameters and driving methods on the electro-optical properties of the proposed BPLCD are investigated. The results demonstrate that the operating voltage can be reduced from 53.80 V to 23.00 V for red colour. Besides, the coincident voltage-dependent transmittance curves for RGB colours are obtained by adjusting the applied voltage of sub-electrode. Thus, RGB lights can pass through every pixel with single electro-optic curve, which is good for resolution enhancement and single gamma driving. Besides, the maximum gamma shift of the proposed BPLCD is less than 0.1099 at 60° polar angle for the red colour, and the gamma shift difference between red and blue colours is only 0.0542. If the high dielectric constant material is used as the protrusion, the operating voltage can be further decreased, which is close to that of the BPLCD with wall-shaped electrode structure. 相似文献