共查询到20条相似文献,搜索用时 78 毫秒
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研究了环腔中的非线性周期结构介质的光学双稳态和光限现象,建立了输入光强与输出光强关系的表达式。理论上给出了临界入射光强低达10^7W/cm^2的光学双的条件和非常有效的限光作用的条件。 相似文献
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用多变量频域稳定性判据,分析了自适应激光谐振腔系统的稳定性,针对千瓦级CO2激光非稳腔和五通道弱关联自适应光学系统的计算机模拟结果表明,多变量频域法研究自适应光学动力学系统的稳定性是有效的。 相似文献
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本文应用矩阵范数及奇异值分解的理论,研究不确定动力学系统的稳定性分析方法.文中给出了一个稳定性判据及一个计算实例. 相似文献
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We consider the inverse problem of thermoelasticity for an isotropic medium containing a cavity of unknown shape and subjected
to the action of mechanical and thermal loads. Nonlinear equations are deduced for the geometric parameters of an ellipsoidal
equistressed cavity. Similar relations for mechanical loads obtained by the other authors follow from the constructed equations
as special cases. The numerical analysis is performed and the relationship between the values of the loads and the parameters
of the cavity is investigated. The stresses on the equistressed surface of the cavity are found and the influence of temperature
on the relationship between the parameters of loads and the geometric characteristics of the equistressed cavity is analyzed.
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Translated from Problemy Prochnosti, No. 1, pp. 121–131, January–February, 2007. 相似文献
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Bidyut B. Gogoi 《International Journal for Computational Methods in Engineering Science and Mechanics》2016,17(4):253-273
We have recently analyzed the global two-dimensional (2D) stability of the staggered lid-driven cavity (LDC) flow with a higher order compact (HOC) approach. In the analysis, critical parameters are determined for both the parallel and anti-parallel motion of the lids and a detailed analysis has been carried out on either side of the critical values.In this article, we carry out an investigation of flow stabilities inside a two-sided cross lid-driven cavity with a pair of opposite lids moving in both parallel and anti-parallel directions. On discretization, the governing 2D Navier–Stokes (N–S) equations describing the steady flow and flow perturbations results in a generalized eigenvalue problem which is solved for determining the critical parameters on four different grids. Elaborate computation is performed for a wide range of Reynolds numbers (Re) on either side of the critical values in the range 200 ? Re ? 10000. For flows below the critical Reynolds number Rec, our numerical results are compared with established steady-state results and excellent agreement is obtained in all the cases. For Reynolds numbers above Rec, phase plane and spectral density analysis confirmed the existence of periodic, quasi-periodic, and stable flow patterns. 相似文献
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Dragan Poljak Choy Yoong Tham Niksa Kovac 《Engineering Analysis with Boundary Elements》2003,27(10):657-1007
Analysis of the human body exposed to low frequency and high frequency electromagnetic fields is presented in this work. The formulation of the problem is based on a simplified thick wire model of the human body. The current distribution induced in the body is determined by solving the Pocklington integral equation for a straight thick wire via the Galerkin–Bubnov boundary element method. Once the axial current along the equivalent antenna of the body is obtained, one may calculate the induced current density, electric field, specific absorption rate, and the total absorbed power in the human body. Several realistic exposure examples are given. 相似文献
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孔腔流动发声是气动声学研究领域重要的课题,基于大涡模拟和Lighthill声类比方法,探讨了气体在孔腔流动的流激噪声的发声特性。模拟结果表明,孔腔边界层出口剪切涡、边棱处涡街和腔体内反馈涡的运动诱导了孔腔发声,具有明显的偶极子特性,在高频段腔体内激发了声学驻波模态。通过模拟与实验对比分析了不同流量下噪声量级以及频谱分布规律,研究结果表明:24 kHz以下的声频谱会表现出波峰小范围迁移;24 kHz以上频率对应的声压级随流量增大而增大;腔体长度和特征频率近似满足Strouher公式,即声频特征频率随腔体长度的增大而减小。上述研究结果为下一步设计在线监测安全阀泄漏的报警超声波发声器提供了理论依据。 相似文献
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高压富水充填溶腔具有水量大、水压高、规模范围大、充填介质复杂的特征,工程施工风险极高,采用传统的注浆法进行处理,受地层的不均一性、材料选择、技术水平的影响,难免会出现注浆盲区,施工中一旦注浆盲区被高压水击穿,将会发生大规模突水突泥,造成灾害。针对宜万铁路所遇到的高压富水充填溶腔,通过科技攻关,提出采取释能降压新技术进行处治。经现场实践,安全、经济、可靠,并取得了成功。释能降压技术是针对高压富水充填溶腔采取有计划、有目的的精确爆破揭示,从而释放溶腔所存储的能量,降低施工及运营过程中水土压力对隧道形成影响,之后,通过配套处治措施完成溶腔治理。 相似文献
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本项目利用循环化工基地的工艺循环水输送至分布首站,换出一次水,通过一次管网输送到用户侧,由双级永磁同步变频离心式热泵机组对区域住宅实现供热,从而实现了对工业余热的有效利用. 相似文献
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针对柱状药包爆炸冲击荷载下炮孔周边岩体介质扩腔体积和能耗占比问题,采用爆破破岩和断裂力学理论,结合爆炸具有瞬时、高温、高压等极端态特性,构建了仅以单轴动态抗压为主要依据的过度粉碎区岩石破碎能耗的简易计算公式,并开展了模型试验研究。该研究结果表明:随着最小抵抗线由120 mm增加到200 mm,扩腔半径由炮孔半径的2.6倍增加到4.6倍,扩腔体积增加了3.56倍,呈现明显的指数增长趋势;能耗由524 J增加到1870 J,能耗占比由5.93%上升到21.13%,与现有的研究成果基本一致,验证了计算公式的可行性。该研究结果能够为光面爆破、预裂爆破等控制爆破技术的设计和施工提供理论依据。 相似文献
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《Advanced Powder Technology》2014,25(1):226-235
Barium sulfate nanoparticles were produced by nanomilling in stirred media mill using sodium salt of polyacrylic acid (PAA-Na) as a dispersant. The particles sizes of the ground product obtained in the grinding mill were determined by dynamic light scattering (DLS), Brunauer–Emmet–Teller (BET) nitrogen gas adsorption method, and transmission electron microscopy (TEM). The mean particle size calculated with various methods yielded different values due to the different characterization techniques. The stability of BaSO4 nanoparticles produced was analyzed by zeta potential measurement and Turbiscan. The stability of barium sulfate nanoparticles was high in presence of dispersant PAA-Na and higher pH values. Further, the changes in microstructural properties, caused by wet grinding and adsorption of PAA-Na on BaSO4 nanoparticles, were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The surface activation and amorphization of BaSO4 nanoparticles were observed due to increased stresses exerted on the particles during wet grinding. 相似文献