新型金属蜂窝板燃烧器的高效燃烧现象分析

新型金属蜂窝板燃烧器是通过采用双层或多层金属薄片制成,能有效地解决普通燃气灶具燃烧器存在的不足,使产品结构更加合理完善,性能更加稳定可靠,能效更加优越。本文以红外燃气灶具的核心部件—新型金属蜂窝板燃烧器为研究对象,利用红外摄像仪对红外燃气灶具和普通燃气灶具进行了对比研究。结果表明,红外燃气灶的火焰集中,温度分布均匀,燃烧效率比普通燃气灶高12.7%。     

用多极理论分析圆桩对称微波谐振腔

用多极理论计算具有复杂几何形状、圆柱对称微波腔的谐振频率,推导出用多极理论计算圆柱对称微波腔谐振频率的本征值方程。三个工程实例的计算结果表明,用多极理论计算圆柱对称微波腔谐振频率,不仅具有较高的计算精度,而且可以很方便地应用于复杂几何形状圆柱对称微波腔工程问题的设计与计算,多极理论是计算圆柱对称微波腔谐振频率的一种有效方法。     

激光标线的原理和实验

根据几何光学知识分析了激光标线原理.理论和实验表明:激光标线长度与激光光束形状、光学元件形状及材料折射率有关.并讨论了激光标线向两侧扩展的原因.     

Calculation of the spectral response of an arrayed-waveguide gating demultiplexer with a wide-angle beam propagation method in a cylindrical coordinate system

The spectral response of an arrayed-waveguide grating (AWG) demultiplexer is calculated by simulating the field propagation in the output section of an AWG with a wide-angle beam propagation method (BPM) in a cylindrical coordinate system. As in a practical design of an AWG demultiplexer, each output waveguide consists of two straight sections connected by a bending section. The spectral response obtained by the present algorithm is more accurate than those obtained with two popular approximate methods, namely, the conventional overlapped integral method and the standard BPM for radially straight and infinitely long output waveguides. With the present algorithm, the dependence of the spectral response on the parameters of the output section is analyzed. The channel crosstalk and the 3 dB passband width of the spectral response depend mainly on the length of the first straight section, the end separation and the angular separation of the output waveguides. The bending section results in an asymmetrical spectral response with remarkable sidelobes which can be reduced by increasing the bending radius.     

对柱对称电流分布磁矢势问题的讨论

采用柱对称性和叠加原理讨论了均匀载流圆环、圆筒、圆盘的矢势问题．     

Elastoplastic stress analysis for cylindrical shell with flat strip imperfection

Based on unequidistant B-spline function, generalized spline subdomain displacement mode of rotational shell is obtained by taking double-direction interpolation of spline. The elastoplastic constitutive equation of shells is established by using the endochronic theory.According to the initial deflection theory of shells, the elastoplastic stress analysis of cylindrical shells with flat strip geometrical imperfection is studied. Numerical results show that the geometrical imperfection has a great effect on the stress distribution of shells.     

变厚度圆柱壳的轴对称弯曲问题

本文详细地研究了厚度h=h_0ξ~的圆柱壳的轴对称弯曲问题.文中通过引入一个位移函数H(ξ),将该问题的方程组化成一个关于H(ξ)的6阶常微分方程,用广义超几何函数给出问题的精确解.     

Biocomposites based on ramie fibers and poly(L‐lactic acid) (PLLA): morphology and properties

We herein report effects of morphology of PLLA and natural fiber on combination properties of biocomposites based on PLLA and ramie fibers. For this purpose, short ramie fiber (FIB), ramie fabric (FAB), PLLA film (FPLLA), and PLLA powder (PPLLA) were used to investigate the structure–property relationship of PLLA biocomposites with 30 wt% ramie fiber prepared by hot compression molding. It is revealed that mechanical properties of biocomposites are strongly dependent on the morphology of PLLA and FAB. DMA test shows that the improved storage modulus was due to the better dispersion of FIB. DSC and POM tests show that PLLA/FIB biocomposites have the highest spherulite growth rate. TGA test shows that char residue at high temperature is affected by the dispersion of PLLA and ramie fiber. SEM images exhibit the different interfacial adhesion character of FIB and FAB in the PLLA matrix after the ramie fiber treated with alkali and silane. PLLA/FAB biocomposites have not only better anti‐dripping properties when burning but also better aging resistance in UV‐irradiation hydrothermal aging, and which can be attributed to fiber bundle and laminated PLLA biocomposites structure. Copyright © 2010 John Wiley & Sons, Ltd.     

Structure of Polymer Brushes in Cylindrical Tubes: A Molecular Dynamics Simulation

Summary: Molecular dynamics simulations of a coarse‐grained bead‐spring model of flexible macromolecules tethered with one end to the surface of a cylindrical pore are presented. Chain length N and grafting density σ are varied over a wide range and the crossover from “mushroom” to “brush” behavior is studied for three pore diameters. The monomer density profile and the distribution of the free chain ends are computed and compared to the corresponding model of polymer brushes at flat substrates. It is found that there exists a regime of N and σ for large enough pore diameter where the brush height in the pore exceeds the brush height on the flat substrate, while for large enough N and σ (and small enough pore diameters) the opposite behavior occurs, i.e. the brush is compressed by confinement. These findings are used to discuss the corresponding theories on polymer brushes at concave substrates.

Snapshot picture of a brush grafted inside of a cylinder, for , , displaying different chains in distinct colors in order to be able to distinguish them. Top shows a side view of the cylinder, and the lower part a view of the cross‐section. Note that the particles forming the cylindrical wall are not displayed.     

Rod‐Like Nano‐Light Harvester

Imitating the natural “energy cascade” architecture, we present a single‐molecular rod‐like nano‐light harvester (NLH) based on a cylindrical polymer brush. Block copolymer side chains carrying (9,9‐diethylfluoren‐2‐yl)methyl methacrylate units as light absorbing antennae (energy donors) are tethered to a linear polymer backbone containing 9‐anthracenemethyl methacrylate units as emitting groups (energy acceptors). These NLHs exhibit very efficient energy absorption and transfer. Moreover, we manipulate the energy transfer by tuning the donor–acceptor distance.