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31.
32.
集合风险模型的可分解性 总被引:1,自引:0,他引:1
本文讨论了集合风险模型中 ,在复合二项分布和复合负二项分布两种情况下的可分解性问题 ,得到了同复合泊松分布情况下类似的结果 相似文献
33.
CO_2气体保护焊接是一种高效、节能和低成本的焊接方法,在钢结构焊接生产中得到了广泛的应用。但也存在着诸如:金属飞溅、焊缝成形较差等问题,要解决这些问题,必须首先对CO_2焊接过程的电弧形态以及熔滴变化情况从理论上深入分析研究。本文以高速摄影与光线示波器同步进行拍摄,记录了CO_2悍接短路过渡中熔滴的长大、缩颈、脱落的全过程以及相对应的电流电压波形。利用影片数据分析处理系统对所得影片及记录波形进行了分析处理,得到了熔滴过渡形成金属液桥爆断瞬间的最大电流值及所受合力的大小。从理论上更进一步研究了短路过渡的机理,建立了短路过渡的模型,这对正确调节焊接工艺规范,保证焊接质量具有重大的指导意义,研究结果表明:在常规短路过渡CO_2焊接中,抑制飞溅是提高CO_2焊接质量的关键,利用焊接规范来调节短路频率和短路峰值电流是抑制飞溅的主要途径。 相似文献
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大变位热弹性扁壳的一种边值模型 总被引:1,自引:0,他引:1
本文给出了正则形式基本方程及广义变分原理,并给出了关于应力函数、挠度、温度三种变量的一种边值模型。 相似文献
36.
The purpose of this paper is to investigate the dynamic behaviour of saddle form cable-suspended roofs under vertical excitation action. The governing equations of this problem are system of nonlinear partial differential and integral equations. We first establish a spectral equation, and then consider a model with one coefficient, i.e., a perturbed Duffing equation. The analytical solution is derived for the Duffing equation. Successive approximation solutions can be obtained in likely way for each time to only one new unknown function of time. Numerical results are given for our analytical solution. By using the Melnikov method, it is shown that the spectral system has chaotic solutions and subharmonic solutions under determined parametric conditions. 相似文献
37.
Many real life problems can be stated as a minimax optimization problem, such as the problems in economics, finance, management, engineering and other fields. In this paper, we present an algorithm with nonmonotone strategy and second-order correction technique for minimax optimization problems. Using this scheme, the new algorithm can overcome the difficulties of the Maratos effect occurred in the nonsmooth optimization, and the global and superlinear convergence of the algorithm can be achieved accordingly. Numerical experiments indicate some advantages of this scheme. 相似文献
38.
Yu M Ding Z Jiang F Ding X Sun J Chen S Lv G 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,83(1):453-460
The interaction between bovine serum albumin (BSA) and pegylated puerarin (Pur) in aqueous solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy and circular dichroism spectra (CD), as well as dynamic light scattering (DLS). The fluorescence of BSA was strongly quenched by the binding of pegylated Pur to BSA. The binding constants and the number of binding sites of mPEG(5000)-Pur with BSA were 2.67±0.12 and 1.37±0.05 folds larger after pegylating, which were calculated from the data obtained from fluorescence quenching experiments. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be 4.09 kJ mol(-1) and 20.01 J mol(-1) K(-1), respectively, according to Van't Hoff equation, indicating that the hydrophobic force plays a main role in the binding interaction between pegylated Pur and BSA. In addition, the negative sign for Gibbs free energy change (ΔG) implies that the interaction process is spontaneous. Moreover, the results of synchronous fluorescence and CD spectra demonstrated that the microenvironment and the secondary conformation of BSA were changed. Comparing with Pur, all our data collected indicated that pegylated Pur interacted with BSA in the same way as that of Pur, but docked into the hydrophobic pocket of BSA with more accessibility and stronger binding force. DLS measurements showed monomethoxy polyethylene glycol (mPEG) have an effect on BSA conformation, and revealed that changes in BSA size might be due to increases in binding constant and the absolute values of ΔG after Pur pegylation. 相似文献
39.
40.
Controlled Incorporation of Ni(OH)2 Nanoplates Into Flowerlike MoS2 Nanosheets for Flexible All‐Solid‐State Supercapacitors
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Chunxue Hao Fusheng Wen Jianyong Xiang Limin Wang Hang Hou Zhibin Su Wentao Hu Zhongyuan Liu 《Advanced functional materials》2014,24(42):6700-6707
In this work, self‐supporting three‐dimensional hierarchical nanostructured MoS2@Ni(OH)2 nanocomposites are synthesized via a facile single‐mode microwave hydrothermal technique. The fabricated MoS2@Ni(OH)2 nanocomposites for supercapacitors in aqueous electrolyte exhibit higher specific capacitance and better cyclic stability than those of MoS2 and Ni(OH)2 due to the pronounced synergistic effect between MoS2 and Ni(OH)2. Further, the flexible all‐solid‐state supercapcitor is readily constructed by composing the PVA/KOH gel electrolyte in between two MoS2@Ni(OH)2 electrodes on the flexible PET substrates. The resulting supercapacitors can operate at high rate up to 1000 V/s, have excellent long‐life cycling stability, retaining 94.2% of the initial capacitance after 9000 cycles, and mechanical flexibility during extreme bending, respectively. Thereby, the MoS2@Ni(OH)2 nanocomposites are a promising electrode materials for flexible long‐life cycling all‐solid‐sate supercapacitors. 相似文献