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31.
由圆柱三孔型二元复合测压管的测速原理出发,提出用一孔测压管通过旋转实现平面气流速度大小与方向的自动测量,建立了相应的测试系统.通过大量实验,研究了该系统的性能.在多种回流和旋流流场测量中进行了应用.结果表明该系统测量原理正确,重复性好,精度高  相似文献   
32.
锥形轴对称微管道内流动特性实验研究   总被引:1,自引:0,他引:1  
介绍了生物转基因显微注射的应用和存在的问题。针对显微注射所用的锥形轴对称微管道,进行了流动过程理论分析,并在微流动实验平台上对这种管道内流动进行了流量与压力特性参数的连续观测实验,详尽介绍了实验装置和实验过程,并给出了尖端直径为4~15μm的锥形管道流动实验结果。  相似文献   
33.
A mesh-free method based on local Petrov-Galerkin formulation is presented to solve dynamic impact problems of hyperelastic material.In the present method,a simple Heaviside test function is chosen for simplifying domain integrals.Trial function is constructed by using a radial basis function(RBF)coupled with a polynomial basis function,in which the shape function possesses the kronecker delta function property.So,additional treatment is not required for imposing essential boundary conditions.Governing equations of impact problems are established and solved node by node by using an explicit time integration algorithm in a local domain,which is very similar to that of the collocation method except that numerical integration can be implemented over local domain in the present method.Numerical results for several examples show that the present method performs well in dealing with the dynamic impact problem of hyperelastic material.  相似文献   
34.
为了解决身管内壁检测系统数据量大,数据处理环节复杂导致身管参数信息获取困难的问题,提出了火炮身管内壁检测系统的数据处理方法。在完成火炮身管检测系统搭建的基础上,针对身管的特殊结构以及激光位移传感器采集数据的特点,提出了身管内壁轮廓还原方法和膛线数据分离方法,基于最小二乘法获取身管内壁参数,并且对系统存在的误差进行了分析和校正,提高了系统的精度。实验结果证明:系统的径向误差小于0.01 mm,异常数据修正的误差小于0.01 mm,数据处理方法正确,有效解决了获取火炮身管内壁参数的问题。  相似文献   
35.
A new arsenomolybdate compound [Cu(imi)2]5Na[(AsO4)Mo9O27(AsO3)]·5H2O(imi = imidazole) 1, has been prepared by hydrothermal method and structurally characterized by elemental analysis, IR, XRD, TG analysis and single-crystal X-ray diffraction analysis. Compound 1 represents the first example of monocapped trivacant Keggin [AsIIIAsVMo9O34]6? subunit as polydentate ligand bonded to five [Cu(imi)2] complexes through one covalent bond and four weak Cu···O bonds. The electrochemical behavior of 1-modified carbon paste electrode has been studied in detail. In addition, photoluminescence and photocatalysis properties of 1 have been investigated.  相似文献   
36.
Gai H  Li Y  Silber-Li Z  Ma Y  Lin B 《Lab on a chip》2005,5(4):443-449
A laser-induced fluorescence imaging method was developed to simultaneously measure flow velocities in the middle and near wall of a channel with particles or single molecules, by selectively switching from the wide field excitation mode to the evanescent wave excitation mode. Fluorescent microbeads with a diameter of 175 nm were used to calibrate the system, and the collisions of microbeads with channel walls were directly observed. The 175 nm microbeads velocities in the main flow and at 275 nm from the bottom of the channel were measured. The measured velocities of particles or single molecules in two positions in a microchannel were consistent with the calculated value based on Poiseuille flow theory when the diameter of a microbead was considered. The errors caused by Brownian diffusion in our measurement were negligible compared to the flow velocity. Single lambda DNA molecules were then used as a flowing tracer to measure the velocities. The velocity can be obtained at a distance of 309.0 +/- 82.6 nm away from bottom surface of the channel. The technique may be potentially useful for studying molecular transportation both in the center and at the bottom of the channel, and interactions between molecules and microchannel surfaces. It is especially important that the technique can be permitted to measure both velocities in the same experiment to eliminate possible experimental inconsistencies.  相似文献   
37.
变折射率介质中光线追迹通用算法的研究   总被引:10,自引:2,他引:8  
基于几何光学的光线折射和反射原理提出了变折射率介质中的光线追迹算法,给出了在光线追迹过程中进行递推的反射光线和折射光线的方向余弦方程;解决了空间中法线的确定和光线回转等问题。最后通过对多种不同的存在解析解的特殊折射率分布的数值解值和解析解值的比较,验证了算法的正确性,并且讨论了应用算法时应该注意的问题和算法中还有待解决的问题。该算法不但具有广泛的适用性,基本不受折射率分布的制约,而且其数值解精度达10^-5。该算法在变折射率介质的光学设计和空间成像补偿等方面有着广阔的应用前景。  相似文献   
38.
针对跑车试验时油气弹簧中节流阀片受冲击失效的现象,提出了研究阻尼阀水击压强的必要性,建立了带有环形节流阀片的阻尼阀物理模型. 运用水击理论及解偏微分方程的特征线法,创造性地对给定阻尼阀结构进行了水击建模计算. 编程分析节流阀片失效的原因,系统研究了常通孔结构参数变化对阻尼阀所受瞬态冲击及其阻力值的影响规律,提出需从屈服和疲劳强度两个方面入手对阀门可靠性进行校核,并给出计算实例,完善了现有阀系设计的算法. 所得结论可以作为可靠性研究的参考,同时避免了阀片断裂的再次发生.   相似文献   
39.
A new linear chain compound, [Cu(en)2][Cu(en)2(H2O)1.5][Cu(en)2(H2O)2]0.5[{Cu(en)2}5{HP2Mo5O23}3] · 6.5H2O ( 1 ) (en = ethylenediamine), has been synthesized under mild hydrothermal conditions, and characterized by elemental analysis, IR, thermogravimetric analyses, magnetic susceptibility measurements and single‐crystal X‐ray diffraction. The crystals are monoclinic, C2/c, a = 42.509(2) Å, b = 25.542(2) Å, c =22.1011(14) Å, β = 102.5940(10)º, V = 23419(3) Å3, Z = 8. The crystal structure of 1 features Cu‐bearing cations that are both free as well as being coordinated to the poly(oxomolybdophosphate) groups formed a linear chain that runs along the b axis. Magnetic studies show that the complex is antiferromagnetic. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
40.
ComparisonStudyofTwoMehodsforRealizingReal-timeHigh-efficiencyJTCGEBaozhen;QINYuwen;ZHANGYimo;HUANGZhanhua;ZHANGHong(Institut...  相似文献   
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