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51.
针对反射体布拉格光栅谱组束中缺乏精密控制仪器的实验条件,采用透镜作为光束入射角和准直控制器件,设计了一种结构简单的谱组束系统。基于衍射效率方程,得到了光栅最佳设计参数;基于像差理论,得到了透镜最佳设计参数。针对该设计系统,对影响组束效果的因素进行了分析,并对组束效果进行了预测。结果表明:当激光束的谱宽小于1.5 nm时,设计系统的组束效率能超过90%;而当光束的谱宽达到2.1 nm时,设计系统也能获得超过88.7%的组束效率。  相似文献   
52.
This work deals with the global existence of weak solutions for a Kazhikhov–Smagulov type system with a density which may or not vanish. Our model is formally equivalent to the physical compressible model with Fick’s law, in contrast to those in previous works. This model may be used for addressing environmental problems such as propagation of pollutants and avalanche modelling. We also explain why this system may be seen as a physical regularization of the standard nonhomogeneous incompressible Navier–Stokes equations and we give an existence result with an initial density less regular but away from the vacuum.  相似文献   
53.
从力敏传感器测力的原理出发,总结了用力敏传感器测量液体表面张力系数实验的诸多优点,并阐述了这个实验的现实意义.  相似文献   
54.
Viscosity measurements on two commercial thermotropic liquid crystalline polymers (LCPs) (a copolyester and a polyesteramide) were performed using both capillary and slit die methods. The results are in agreement with those presented in the literature for the same LCPs, when the measurements are carried out with a L/D = 30 die; these results are affected more by Bagley corrections for the polyesteramide than for the copolyester. For both LCPs, viscosities measured in the slit die are lower than those obtained by capillary rheometry. Nevertheless, the difference is much bigger in the case of the polyesteramide, for which a reduction by a factor of 3 is observed. This is not due to the preshear or thermal history, since the same piston-barrel system and thermal treatment were applied in both types of measurements. Depending on the polymer sample and temperature, concave and convex curvatures were observed in the pressure profiles during the slit flow. From these curvatures, the pressure coefficient α of viscosity was evaluated. However, in the case of the polyesteramide the convex curvature leads to a negative coefficient (the viscosity decreases with pressure, instead of increasing). This result may be explained by envisaging a change in the structure of the melt along the slit length. © 1993 John Wiley & Sons, Inc.  相似文献   
55.
Let A be a symmetric expansive matrix and Hp(Rn) be the anisotropic Hardy space associated with A. For a function m in L∞(Rn), an appropriately chosen function η in Cc∞(Rn) and j ∈ Z define mj(ξ) = m(Ajξ)η(ξ). The authors show that if 0 < p < 1 and (m)j belongs to the anisotropic nonhomogeneous Herz space K11/p-1,p(Rn), then m is a Fourier multiplier from Hp(Rn) to Lp(Rn). For p = 1, a similar result is obtained if the space K10,1(Rn) is replaced by a slightly smaller space K(w).Moreover, the authors show that if 0 < p ≤ 1 and if the sequence {(mj)V} belongs to a certain mixednorm space, depending on p, then m is also a Fourier multiplier from Hp(Rn) to Lp(Rn).  相似文献   
56.
The authors consider a model of ferromagnetic material subject to an electric current, and prove the local in time existence of very regular solutions for this model in the scale of Hk spaces. In particular, they describe in detail the compatibility conditions at the boundary for the initial data.  相似文献   
57.
We study the solvability of the quasilinear elliptic problem of parameter s
  相似文献   
58.
New sufficient conditions are given for the existence of solutions of a Henig proper generalized vector quasiequilibrium problem with moving cones. They are established by a new scalarizing approach, which is based on a suitable nonlinear scalarization function, proposed recently for set-valued maps in Sach and Tuan (J. Optim. Theory Appl. 157:347–364 (2013)). Examples are given to illustrate our main results.  相似文献   
59.
碳富勒烯在水中的运动阻力特性   总被引:3,自引:1,他引:2  
采用分子动力学(MD)方法,模拟了Cn(n=60,180,240,540)以及C60@C240富勒烯在水中的速度衰减过程,得到了它们的阻力一速度与阻力,雷诺(Re)数关系曲线;进而将MD模拟的阻力结果和低Re数宏观流体力学中球的Stokes阻力解进行了对比,研究表明,低Re数下,富勒烯在水中的阻力要比传统流体力学中球的Stoke解高两个数量级;富勒烯在水中的阻力可通过Stokes解乘以(110.38-1.48/Re)近似估算.  相似文献   
60.
概述宁波大学地基处理中心自成立以来紧密结合宁波市工程建设中的需要,在地基处理、桩基工程质量检测等方面开展的科研开发工作,和取得的成果,这些成果在工程中的应用已取得了良好的经济和社会效益。  相似文献   
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