适用于聚变装置偏滤器部件的高热负荷测试平台真空腔体系统设计

对托卡马克聚变装置偏滤器的高热负荷测试平台真空腔体系统进行了结构设计,其中包括真空室、真空抽气系统、部件调节机构、小型水冷系统和电子枪操作平台,利用Ansys对真空室主体结构的合理性和可靠性进行了验证.模拟结果表明:真空室外壁温度不超过50℃,真空室及其支撑上的最大应力分别为134.49MPa和48.76MPa,满足许...     

间断流函数守恒律方程的高精度有限差分格式

本文研究了具有间断流函数的守恒律方程,借助本质无振荡（ENO）的思想,利用Rankine—Hugoniot关系和全局熵条件设计出一种高精度计算格式;并利用此格式计算出相关情形的Riemann问题,显示了满意的数值解果．     

边界净流条件下的超声速热波

 物质中的辐射热波的行为一直是人们非常关注的问题。但是由于辐射热传导方程具有很强的非线性,其精确的解析解很难求出。利用微扰论推导出了任意边界净流条件下的边界温度的变化行为和热波传播轨迹的理论公式,并与辐射流体力学程序计算的数值结果进行了对比,结果显示理论计算的热波轨迹与数值模拟的结果符合得非常好。     

螺旋形爆磁压缩发生器跳匝现象分析

 分析了螺旋形爆磁压缩发生器的跳匝现象,考虑了膨胀电枢与定子线圈的交线,采用更加精确的计算模型,得出了更为精确的发生器装配公差表达式,通过计算验证了简化模型的结论可以满足设计要求,并对电枢表面和电枢壁厚等的不规则因素,以及圆管爆轰的边缘效应导致跳匝作了深入的分析计算。结果表明：如果电枢的装配公差合适,则可消除由于电枢和定子之间的轴线偏差导致的跳匝现象;圆管爆轰的边缘效应会导致起爆端部分线匝的磁通损失,因而发生器设计时电枢要比定子线圈长一部分;电枢厚度的径向不均匀分布会引起电枢的不对称膨胀,从而导致跳匝发生。     

Synthesis and Structure of Ba7F12Cl2

Crystals of ordered and disordered Ba₇F₁₂Cl₂ were prepared by flux growth and solid state reactions. These new structures were characterized by single crystal and powder X‐ray diffraction. The disordered variant which shows disorder on one of the cation sites was obtained from a BaF₂ + BaCl₂ + NaCl/NaF flux. It has hexagonal space group P6₃/m (176) with one formula unit per unit cell. The lattice constants are a = b = 1059.55(5) pm and c = 420.10(4) pm (at 21 °C). The structure was refined to R(R_w) = 0.026(0.030) for 346 independent reflections and 26 parameters. Slow cooling of a mixture of BaF₂ and LiCl yields the ordered variant. This one crystallizes in the hexagonal space group P6 (174) with one formula per unit cell. Lattice constants at 21 °C are a = b = 1063.46(2) pm and c = 417.52(1) pm. The structure was refined to R(R_w) = 0.017 (0.017) for 638 independent reflections and 45 parameters. The structural arrangement and the interatomic distances of the two variants are mutually similar. The barium atoms have coordination number nine. Propeller‐type arrangements with a chloride ion on the axis and the fluoride ions as blades are observed. These latter ones are interconnected into ‘channels' of tricapped fluoride prisms. Occupation disorder of the barium sites in the channels of the disordered variant makes the main difference between the two. An unexpectedly high X‐ray density obtained for both variants of Ba₇F₁₂Cl₂ can be correlated to the density of other barium fluorohalides having a coordination number of nine for the barium ion.     

α- und β-BaCu2X2 (X ≙ S,Se) – Darstellung von Einkristallen in Kaliumchalkogenocyanat-Schmelzen

α- and β-BaCu₂X₂ (X ≙ S, Se) – Preparation of Single Crystals in Potassium Chalcogenocyanate Fluxes α- and β-BaCu₂S₂, as well as the isotypic selenides, could be obtained in a flux of potassiumthio- or potassiumselenocyanate at 480 °C, respectively. Up to now only the preparation of the golden yellow α-BaCu₂S₂ compound in the form of some crystals is reported [1]. Single crystal four-circle diffractometer data confirm the already known structure of α-BaCu₂S₂ and α-BaCu₂Se₂, and the expected BaZn₂P₂ structure type for the β-modification of the two chalcogenides. β-BaCu₂Se₂ could be prepared for the first time. α-BaCu₂S₂ transforms irreversibly at 540 (±10) °C into the β-modification. The structural relationship between the two structure types is described. α-BaCu₂S₂ is diamagnetic, β-BaCu₂S₂, on the other hand, shows a small, temperature-independent paramagnetism.     

Growth of Neodymium Pentaphosphate Single Crystals by the Flux Seeded Technique

Single crystals of neodymium pentaphosphate, NdP₅O₁₄, were grown by the flux seeded technique. The optimum growth conditions are scribed for obtaining a large crystal having well-developed faces with good quality.     

Flux Growth of KNbO3 Crystals by Pulling-Down Method

The crystals of KNbO₃ have been grown by the micro-pulling-down method. Colorless, transparent, and crack-free crystals were produced from the melts containing excess of K₂O as a flux. Growth of relatively large size (up to 2 mm in diameter and up to 30 mm in length) single crystals was found is possible using the crucibles with corresponding nozzle size (up to 2.0 mm in outer diameter). Second harmonic generation was observed in the crystals irradiated by fundamental beam with wavelength about 860 nm.     

K2O助溶剂提拉法和富锂提拉法生长的近化学计量比LiNbO3晶体性质的比较

分别采用K2O助溶剂提拉法和富锂提拉法生长了近化学计量比LiNbO3晶体.比较了两种方法生长的晶体紫外吸收边和红外吸收谱的差别,光谱结果表明,K2O助溶剂提拉法生长的晶体组成非常均匀,而富锂提拉法生长的晶体组成不均匀,沿晶体生长方向,Li2O含量逐渐增加.另外,两种生长方法中,籽晶表面均看到螺旋状环,分析了其产生原因.     

A bounded convection scheme for the overlapping control volume approach

This paper introduces a flux-limited scheme FLOCV for the overlapping control volume (OCV) approach to 2D steady and unsteady convection–diffusion problems on structured non-orthogonal grids. FLOCV switches from second- to first-order interpolation in the presence of extrema. Smooth switching between the two is ensured by weighted average second- and first-order upwind differencing, with the weights being dynamically determined. Five convective test problems are solved using this scheme and results are compared with known analytical solutions. It is found that FLOCV approximately retains second-order accuracy of the base discretization scheme on uniform grids and smooth non-uniform orthogonal grids. It is also found effective in removing oscillations for problems with discontinuities on both orthogonal and non-orthogonal grids, with little degradation of accuracy. © 1997 John Wiley & Sons, Ltd.