CNC系统路径遍历的时间最优控制算法

针对计算机数控(CNC)系统给定路径的遍历问题,给出了一种加减速控制算法,使CNC系统的路径遍历时间最小.由于CNC系统的优化变量(加速度)为线性的存在于时间最优指标和约束条件中,且沿坐标方向加速度有界.因此通常这类时间最小路径遍历问题具有Bang-bang的控制结构,即任意时刻至少有一个坐标方向存在最大加/减速度.针对一类参数化路径,推导了沿坐标方向加速度与曲线局部特性间的关系.保证系统在Bang-bang控制情况下,实现路径精确遍历.1/4和1/2圆弧最短时间遍历问题的仿真结果,验证算法的有效性.     

PREPARATION OF CHITOSAN COATED METAL AFFINITY CHROMATOGRAPHY ADSORBENT

1NTRODUCTIONImmobilizedmetalionaffinitychromatography(IMAC)hasattractedconsiderableattentioninthepurificationofproteinssincePorathfirstlyuseditin1975Llj.IMAChassomeadvantagescomparingtootheraffinitychromatography.Forexample,IMACcanbeoperatedatanhighionstrengthandtheligandsuchasC.2 ischeapandstable.TheconventionalIMACadsorbentswereproducedbyreactingiminodiaceticacid(IDA)withpolysaccharidesuchasagaroseandthentheaffinityligandC.2 waschelatedtothe.d...b..t[2].Thepreparationwasexpensi…     

集成光学声光频谱分析器的制作技术

本文给出了集成光学声光频谱分析器的基本结构与工作原理.给出了集成光学芯片上各种集成光学元件和导波声光调制器的制作技术,并给出了组装一体化样机的结构工艺要点.     

STRONG LIMIT POINT FOR LINEAR HAMILTONIAN DIFFERENCE SYSTEM

The definition of strong limit-point for singular Hamiltonian difference expressions with complex coefficients are given, and some strong limit-point criteria are established.     

Synthesis,Characterization, and Photocatalytic Activity of N‐Doped TiO2 Nanotubes

N‐doped TiO₂ nanotubes with high photocatalytic activity were prepared by the combination of sol‐gel process with hydrothermal treatment. The prepared materials are characterized with transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), x‐ray diffraction (XRD), x‐ray photoelectron spectra (XPS), and UV‐vis spectra. Photocatalytic performance of the N‐doped TiO₂ nanotubes is studied by testing the degradation rate of methyl orange under UV irradiation. Obtained results indicate that N‐doped TiO₂ nanotubes have high catalytic activity for photocatalytic oxidation.     

Mixed Boundary Value Problems for a Class of Fractional Differential Equations with Impulses

We investigate a class of mixed boundary value problem of nonlinear impulsive fractional differential equations with a parameter. The uniqueness of this problem is proved by applying Banach fixed point theorem.     

非贵金属催化剂上CO氧化的研究与进展

非贵金属催化剂催化CO氧化反应研究,不仅拓展了非贵金属的应用,而且为探求可替代贵金属催化CO氧化反应的催化剂提供了新机遇,成为当前催化研究中的热点课题之一。本文综述了近年来铜、钴等非贵金属催化剂体系催化CO氧化反应的研究进展。     

光纤水听器灵敏度测试研究

研制了一套简单可行的光纤水听器灵敏度校准装置,提出了一种简便的测量方法——比对法:将标准压电水听器探头和光纤水听器探头置于同一声场中，并将两探头的输出同时接到数字示波器上进行比对测量.研究表明,振动系统中的盛水容器具有一定的壁厚（>10 mm或1/10桶的外径）时，可将振动系统的谐振峰移出工作频段范围（3~1000 Hz）外.利用此装置结合比对法,校准系统简单，校准速度快,实验的误差小于0.5 dB,能满足一般光纤水听器灵敏度的校准需求.     

The Glazman-Krein-Naimark theory for a class of discrete Hamiltonian systems

In this paper, the Glazman-Krein-Naimark theory for a class of discrete Hamiltonian systems is developed. A minimal and a maximal operators, GKN-sets, and a boundary space for the system are introduced. Algebraic characterizations of the domains of self-adjoint extensions of the minimal operator are given. A close relationship between the domains of self-adjoint extensions and the GKN-sets is established. It is shown that there exist one-to-one correspondences among the set of all the self-adjoint extensions, the set of all the d-dimensional Lagrangian subspaces of the boundary space, and the set of all the complete Lagrangian subspaces of the boundary space.     

Curing kinetics,thermal, mechanical,and dielectric properties based on o‐cresol formaldehyde epoxy resin with polyhedral oligomeric (N‐aminoethyl‐γ‐amino propyl)silsesquioxane

The curing reaction and kinetics of o‐cresol formaldehyde epoxy resin (o‐CFER) with polyhedral oligomeric silsesquioxane of N‐aminoethyl‐γ‐amino propyl group (AEAP‐POSS) were investigated by differential scanning calorimetry (DSC). The thermal, mechanical, and dielectric properties of o‐CFER/AEAP‐POSS nanocomposites were investigated with thermogravimetric analysis (TGA), torsional braid analysis (TBA), tensile tester, impact tester, and electric analyzer, respectively. The results show that the activation energy (E) of curing reaction is 58.08 kJ/mol, and the curing reaction well followed the ?esták‐Berggren (S‐B) autocatalytic model. The glass transition temperature (T_g) increases with the increase in AEAP‐POSS content, and reaches the maximum, 107°C, when the molar ratio (N_s) of amino group to epoxy group is 0.5. The nanocomposites containing a higher percentage of AEAP‐POSS exhibited a higher thermostability. The AEAP‐POSS can effectively increase the mechanical properties of epoxy resin, and the tensile and impact strengths are 2.84 MPa and 143.25 kJ m^?2, respectively, when N_s is 0.5. The dielectric constant (ε), dielectric loss factor (tan δ), volume resistivity (ρ_v), and surface resistivity (ρ_s) are 4.98, 3.11 × 10^?4, 3.17 × 10¹² Ω cm³, and 1.41 × 10¹² Ω cm², respectively, similarly at N_s 0.5. Copyright © 2009 John Wiley & Sons, Ltd.