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该文,使用变分方法,研究了一类如下双相问题正解的存在性■其中N≥2,1
1∈Ls1、(Ω),V2∈Ls2(Ω)是权函数且V1允许变号的,V2是非负的. 相似文献
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为深入研究内爆加载下岩土类材料的破坏机理,提出了一种新的爆炸裂纹检测算法,采用数字图像相关方法测量表面位移场和应变场,建立了裂纹扩展和扩张模型,并通过混凝土内爆试验观测裂纹扩展过程,研究了裂纹长度扩展与宽度扩张规律。结果表明,裂纹长度扩展是应力波和爆生气体共同作用的结果,裂纹最大扩展速度为225.95 m/s,平均速度为122.27 m/s,裂纹总长159.92 mm,长度扩展止于1.75 ms;裂纹的张开由气体主导,最大宽度1.59 mm,作用时间长达4.5 ms;拉应变集中区先于裂纹出现,其形状决定了裂纹的走向和趋势,爆炸加载下断裂过程区长度为骨料粒径的8~9倍。 相似文献
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以甲基丙烯酸甲酯(MMA)为原料,螺噁嗪(SPO)为光致变色染料,经悬浮聚合法制备了光致变色微球(PMMA SPO),其结构经红外光谱、扫描电镜和差热分析表征。研究了SPO浓度对微球转化率和环境温度对光致变色开环体热稳定性的影响。结果表明:在SPO的空间位阻效影响下,微球的玻璃化转变温度由82.4 ℃升高至85.3 ℃,随着SPO浓度下降,微球转化率由89%降低至15%,光致变色开环体的热稳定性随环境温度增大而增强,微球在淡粉色和黄绿色之间可逆转化20次以上未见明显的疲劳现象。 相似文献
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介绍了计算机辅助的分子模型设计和理论计算方法,综述了近十年来该方法在液相色谱手性分离机理研究中的应用,主要集中在Pirkle类型和环糊精类型的手性固定相的研究上,随着计算机软件与硬件的发展,这种方法在手性识别机理研究中的应用会更加广泛。 相似文献
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Effects of Fractal Size Distributions on Velocity Distributions and Correlations of a Polydisperse Granular Gas 下载免费PDF全文
By the Monte Carlo method, the effect of dispersion of disc size distribution on the velocity distributions and correlations of a polydisperse granular gas with fractal size distribution is investigated in the same inelasticity. The dispersion can be described by a fractal dimension D, and the smooth hard discs are engaged in a two- dimensional horizontal rectangular box, colliding inelastically with each other and driven by a homogeneous heat bath. In the steady state, the tails of the velocity distribution functions rise more significantly above a Gaussian as D increases, but the non-Gaussian velocity distribution functions do not demonstrate any apparent universal form for any value of D. The spatial velocity correlations are apparently stronger with the increase of D. The perpendicular correlations are about half the parallel correlations, and the two correlations are a power-law decay function of dimensionless distance and are of a long range. Moreover, the parallel velocity correlations of postcollisional state at contact are more than twice as large as the precollisional correlations, and both of them show almost linear behaviour of the fractal dimension D. 相似文献
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Direct Monte Carlo simulations are employed to investigate the granular pressures in granular materials with a power-law particle size distribution. Specifically, smooth circular discs of uniform material density are engaged in a two-dimensional rectangular box, colliding inelastically with each other and driven by a homogeneous heat bath at zero gravity. The resulting pressures are found to decrease as the widths of particle size distribution are increased. Moreover, the granular pressures in power-law systems are found to be unequally distributed among the various sizes of particles, with large particles possessing more pressure than their smaller counterparts. The width-dependent nature of the total pressures is induced by the more dispersion of smaller particles in the system as the particle size distribution is widened. 相似文献
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空间太阳望远镜主镜支撑结构的优化设计 总被引:3,自引:0,他引:3
空间太阳望远镜主镜是有效口径为1m的抛物面镜,工作状态需要达到衍射极限,因此光学系统要求主镜面形误差小于λ/40(RMS),精度主要靠主镜支撑结构来保证。主镜支撑结构应满足地面调试、在轨及发射状态的需要。支撑结构试验样机已经加工完成,地面调试结果表明主镜的镜面变形满足整个光学系统的要求。试验样机强度和刚度还有较大余量,结构本身比较复杂。用有限元分析方法进行优化设计,优化后的主镜支撑结构满足地面调试、在轨及发射状态的需要,也能保证主镜的面形满足整个光学系统的要求,有效减轻仪器重量、简化支撑结构的同时,提高了整个仪器的可靠性。 相似文献