Linear Dispersion Relation of Asymmetric Modes in the Axisymmetric Slow-Wave Structure

The linear dispersion relation of asymmetric electromagnetic modes in the corrugated-wall waveguide is derived and calculated numerically. The numerical analyses indicate that the effects of lower asymmetric modes on the main interaction mode TM_m must be considered and mode selection also must be solved in order to realize the single asymmetric mode operation of the oversized structures.     

带负摩阻力基桩的静载检测评析

分析了负摩阻力发生的条件 ,比较了基桩荷载长期作用的实际工作状态与静载试验条件下荷载短时间作用的工作性状之间的差异 .分析表明在静载试验条件下基桩的负摩阻力是不可能发生的 ,指出常规的静载试验对于带负摩阻力基桩的评价是偏于不安全的 .通过一个实例说明了带负摩阻力基桩承载力的正确评价方法 ,并提出了设计与检测中的建议     

非均匀平板波导的色散方程

利用转移矩阵理论分析了任意折射率分布平板波导的传输特性，导出了非均匀平板波导的近似解析色散方程，并指出了ＷＫＢ近似的局限性，数值比较的结果表明，文中所得公式的精确度优于传统的ＷＫＢ方法和其它近似方法。     

THE WEINSTEIN CONJECTURE ON C~1-SMOOTH HYPERSURFACE OF CONTACT TYPE

In this note a symplectic capacity of Hofer-Zehnder type that is only invariant under C1-symplectomorphisms is defined and all computation formulae for Hofer-Zehnder symplectic capacity obtained at present are proved still holding for it. As a consequence some results on Weinstein conjecture are generalized to C1-smooth hypersurface of contact type.     

Modulated‐temperature differential scanning calorimetry study of temperature‐induced mixing and demixing in poly(vinylmethylether)/water

The heat capacity or reversing heat flow signal from modulated‐temperature differential scanning calorimetry can be used to measure the onset of phase separation in a poly(vinylmethylether)/water mixture, clearly showing the special type III lower critical solution temperature demixing behavior. Characteristic of this demixing behavior is a three‐phase region, which is detected in the nonreversing heat flow signal. Stepwise quasi‐isothermal measurements through the phase transition show large excess contributions in the (apparent) heat capacity signal, caused by demixing/remixing heat effects on the timescale of the modulation (fast process). These excess contributions and their time‐dependent evolutions (slow process) are useful in understanding the kinetics of phase separation and the morphology (interphase) development. Care has to be taken, however, in interpreting the heat capacity signal derived from the amplitude of the modulated heat flow because nonlinear effects lead to the occurrence of higher harmonics. Therefore, the raw heat flow signal for quasi‐isothermal demixing and remixing measurements is also examined in the time domain. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1824–1836, 2003     

热磨处理对秸秆原料酸碱性和表面自由基的影响

热磨处理不仅改变了秸秆原料的形态，而且改变了秸秆原料的化学组成、酸碱性与表面特性，有利于改善脲醛树脂对秸秆的胶合性能。笔对比分析了热磨前后稻草与麦秸原料的pH、缓冲容量以及表面自由基浓度。结果表明：稻草与麦秸秸秆原料呈弱碱性，缓冲容量远高于普通木材；热磨处理获得的稻草与麦秸秆纤维呈弱酸性，其缓冲容量比稻草与麦秸秸秆有一定幅度的下降，不过仍高于一般材料；稻草与麦秸秸秆的表面自由基浓度只有普通木材原料的1／10；热磨处理所得秸秆纤维的表面自由基浓度比处理前增加了约4－7倍，效果非常显。     

网架结构的优化设计及极限分析

本文编制了网架结构优化设计和极限分析的计算程序．并对网架结构进行了分析。通过实例．将结构的优化设计和极限分析有机地结合起来，从而提高了网架结构的极限承载能力。     

水流速对测定金属导热系数的影响

用流体换热法测金属的导热系数时，在其它条件相同的情况下，水流速度大小对测值有一定影响，作者通过多次实验及分析实验结果找到了较适当的水流速度，对指导课堂教学及有关课题的研究具有一定意义．     

Dispersion and stability analyses of the linearized two‐dimensional shallow water equations in boundary‐fitted co‐ordinates

In the present investigation, a Fourier analysis is used to study the phase and group speeds of a linearized, two‐dimensional shallow water equations, in a non‐orthogonal boundary‐fitted co‐ordinate system. The phase and group speeds for the spatially discretized equations, using the second‐order scheme in an Arakawa C grid, are calculated for grids with varying degrees of non‐orthogonality and compared with those obtained from the continuous case. The spatially discrete system is seen to be slightly dispersive, with the degree of dispersivity increasing with an decrease in the grid non‐orthogonality angle or decrease in grid resolution and this is in agreement with the conclusions reached by Sankaranarayanan and Spaulding (J. Comput. Phys., 2003; 184 : 299–320). The stability condition for the non‐orthogonal case is satisfied even when the grid non‐orthogonality angle, is as low as 30° for the Crank Nicolson and three‐time level schemes. A two‐dimensional wave deformation analysis, based on complex propagation factor developed by Leendertse (Report RM‐5294‐PR, The Rand Corp., Santa Monica, CA, 1967), is used to estimate the amplitude and phase errors of the two‐time level Crank–Nicolson scheme. There is no dissipation in the amplitude of the solution. However, the phase error is found to increase, as the grid angle decreases for a constant Courant number, and increases as Courant number increases. Copyright © 2003 John Wiley & Sons, Ltd.