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121.
122.
On the Linearized Darboux Equation Arising in Isometric Embedding of the Alexandrov Positive Annulus
Chunhe LI 《数学年刊B辑(英文版)》2013,34(3):435-454
In the present paper, the solvability condition of the linearized Gauss-Codazzi system and the solutions to the homogenous system are given. In the meantime, the solvability of a relevant linearized Darboux equation is given. The equations are arising in a geometric problem which is concerned with the realization of the Alexandrov’s positive annulus in ?3. 相似文献
123.
航电设备主控制系统通过ARINC429接口周期性地接收分系统的工作状态信息,利用低温性能较好且价格低廉的MCS-51单片机对数据进行处理,再通过USB接口将包含工作状态的信息写入U盘,使航电设备工作时的参数和状态能够随时用U盘读出,实现对设备工作状态的监控。介绍了单片机控制USB接口芯片SL811HS作为USB主机的硬件设计和底层驱动的编写。ARINC429接口采用HS3282作为接口芯片,以锁存器作为虚拟总线,解决了MCS-51单片机与429接口芯片HS3282总线宽度不匹配的问题,给出了接口的硬件和软件设计方案。 相似文献
124.
激光二极管阵列侧面对称抽运薄片激光器 总被引:9,自引:4,他引:5
对激光二极管(LD)阵列5向侧面对称抽运Nd∶YAG薄片激光器进行了实验和模拟研究。薄片激光器的耦合系统由消像差透镜组和空心光波导组成,采用15mm×1.5mm的Nd∶YAG薄片进行初步实验,实验得到薄片激光器的激光输出平均功率为65.7W,光-光转换效率为10.5%,同时增益介质内具有较理想的荧光分布。同时考虑激光二极管在快轴和慢轴方向的发散特性及增益介质侧面的散射特性,采用光线追迹法,模拟并分析了增益介质内抽运光分布,模拟结果表明耦合系统具有88.3%的耦合效率,同时增益介质内具有较理想的抽运光分布,且与实验结果相吻合。 相似文献
125.
Free vibration of polar orthotropic circular plates with elastic growth stresses and drying stresses
This study was performed to analyze effect of transverse growth stresses and drying stresses on natural frequencies of transverse free vibration of thin tree disk with free boundary condition. Using Rayleigh-Ritz method and finite element method, explicit closed form expression was derived for homogeneous orthotropic circular plates with internal stresses, which enables to predict both the effects of growth stresses, drying stresses, and combined growth and drying stresses on the natural frequency changes. This model can be used for predicting growth stresses from known natural frequencies. The same approach can also be undertaken to validate models visco-elastic drying stresses. 相似文献
126.
The dynamic response of submerged and confined disk-like structures is of interest in engineering applications, such as in hydraulic turbine runners. This response is difficult to be estimated with accuracy due to the strong influence of the boundary conditions. Small radial gaps as well as short axial distances to rigid surfaces greatly modify the dynamic response because of the added mass and damping effects.In this paper, the influence of the axial nearby rigid distance on the dynamic response of a submerged disk is evaluated when the radial gap is very small. Moreover, the effects of the fluid depth and fluid viscosity on the natural frequencies and damping ratio of the submerged disk are studied. The study has been performed experimentally and numerically using structural–acoustic simulations.For the experimental investigation a test rig has been developed. It consists of a disk attached to a shaft and confined with a small radial gap inside a cylindrical container full of water. The disk can be moved up and down along the shaft to vary the axial distance to the nearby rigid surface. Piezoelectric patches are used to excite the disk and the response is measured with submersible accelerometers. Several excitation patterns can be used due to the disposition of these piezoelectric patches. For each configuration tested, the dynamic response of the structure is studied analyzing the natural frequencies and damping ratio of the disk attached to the shaft. The numerical results have been compared with the experimental results. 相似文献
127.
This work deals with the guidance and control of a system which is composed of a rolling disk and a controlled slender rod that is pivoted, through its center of mass, about the disk center. There are given N points P
i, i=1, ..., N, in the horizontal plane, a set of angles 2i
, i=1, ..., N, a finite-time interval [0, t
f], and a sequence of times 1=0<2<...<
N
=t
f. Using the concept of path controllability, a closed-loop control law is derived to steer the system in such a manner that the disk center and the rod angle of rotation 2 will pass through (P
i, 2i
) at the times
i
, i=1,...,N, respectively. This system serves as a model for the motion of a simple mobile robot. 相似文献
128.
John D. Lorch 《Proceedings of the American Mathematical Society》1998,126(12):3755-3762
Inner product structures are given for realizations of the positive spin ladder representations over the generalized unit disk . This is accomplished by combining previous results of the author with the construction of a family of holomorphic polynomials on . These polynomials, which play a crucial role in the present work, are shown to be orthogonal with respect to Lebesgue measure, and their norms are computed. The orthogonal family is then used to invert a certain integral transform, giving the desired inner product structures.
129.
为了增强量子点的定向发光强度,提出了一种由硅柱二聚体和二氧化钛圆盘组成的复合纳米天线结构。利用时域有限差分方法系统研究了硅柱二聚体的轴参数、截面类型以及复合纳米天线结构对量子点定向发光增强的影响。结果表明,对于中心波长为600nm的量子点,硅柱二聚体的轴参数对量子点的发光影响不大,椭圆形截面的硅柱二聚体可以实现较大的量子点发光增强。此外,在复合纳米天线的作用下,不仅可以获得较大的量子效率增强,还可以实现量子点高度定向的发射效果,量子效率增强约6倍,定向收集效率可以达到50%。 相似文献
130.
分别选取抛物线型限定势阱和高斯函数型限定势阱描写盘状量子点中电子的横向限定势和纵向限定势,采用Pekar类型变分法推导出了电子的基态和激发态能量,并基于费米黄金规则讨论了在磁场作用下电子的跃迁几率。结果表明,高斯函数型限定势阱比抛物线型限定势阱更能精准反映量子点中真实的限定势;量子点的厚度对电子跃迁几率的影响显著;电声耦合强度α、磁场的回旋频率ω_c、抛物线型限定势阱范围R_0、高斯函数型限定势阱的阱深V_0和阱宽L等对电子跃迁几率Q的影响的量度和变化规律方面差异较大。 相似文献