PLC在磁场压力机中的应用

提出一种采用PLC控制的压制钕铁硼(Nd-Fe-B)磁性材料的机电一体系统，并介绍了系统重要组成部分：压机主体和电控箱，给出了电控箱中各控制部分的电路及工作原理。实验证明本系统具有结构紧凑、操作方便、控制性能好等优点。     

一类广义Bent型S-Box的构造

S-box是密码理论与实践中十分重要的一种装置 ,它的密码性能由其分量函数所决定 .于是 ,选择适当的分量函数来构造 S-box就成了一个重要的研究课题 .在一定意义上 ,Bent函数是最优良的密码函数 .本文通过函数序列半群和置换群来构造其任何非零线性组合为 Bent函数与线性函数之和的函数组 ,从而可由 Bent函数构造出具有高度非线性度和其他良好性状的 S-box     

Computing Aviation Sparing Policies: Solving a Large Nonlinear Integer Program

Deployed US Navy aircraft carriers must stock a large number of spare parts to support the various types of aircraft embarked on the ship. The sparing policy determines the spares that will be stocked on the ship to keep the embarked aircraft ready to fly. Given a fleet of ten or more aircraft carriers and a cost of approximately 50 million dollars per carrier plus the cost of spares maintained in warehouses in the United States, the sparing problem constitutes a significant portion of the Navy’s resources. The objective of this work is to find a minimum-cost sparing policy that meets the readiness requirements of the embarked aircraft. This is a very large, nonlinear, integer optimization problem. The cost function is piecewise linear and convex while the constraint mapping is highly nonlinear. The distinguishing characteristics of this problem from an optimization viewpoint are that a large number of decision variables are required to be integer and that the nonlinear constraint functions are essentially “black box” functions; that is, they are very difficult (and expensive) to evaluate and their derivatives are not available. Moreover, they are not convex. Integer programming problems with a large number of variables are difficult to solve in general and most successful approaches to solving nonlinear integer problems have involved linear approximation and relaxation techniques that, because of the complexity of the constraint functions, are inappropriate for attacking this problem. We instead employ a pattern search method to each iteration of an interior point-type algorithm to solve the relaxed version of the problem. From the solution found by the pattern search on each interior point iteration, we begin another pattern search on the integer lattice to find a good integer solution. The best integer solution found across all interations is returned as the optimal solution. The pattern searches are distributed across a local area network of non-dedicated, heterogeneous computers in an office environment, thus, drastically reducing the time required to find the solution.     

细支纱摩擦纺初探——尘笼胆结构及其安装角α对纺纱的影响

本文以细支纱摩擦纺为研究对象,利用实验测试手段研究了尘笼胆结构对吸口轴向负压和尘笼胆安装角α对加捻区轴向负压和流速分布的影响。最后,基于类似于控制论中的“黑箱”原理,采用二次正交回归设计在实验室自制单头机上进行了32支纱的纺纱试验,建立了加捻辊加稔效率、纱线品质指标及CV值与尘笼胆几何尺寸、尘笼胆安装角α、摩擦辊转速及纺纱速度间的关系,并作了分析,由此得到选取α=0°、S=6毫米左右较好的结果。     

预应力混凝土箱梁爆炸损伤评估及公式拟合

对预应力混凝土箱梁进行爆炸损伤评估研究。首先,对矩形梁进行爆炸数值分析,结合现场试验结果验证了爆炸数值模型的准确性、可靠性。其次,基于箱梁剩余承载力,建立了箱梁爆后损伤评估准则。通过对预应力混凝土箱梁在不同爆炸工况下的爆后剩余承载力计算,建立箱梁各损伤程度下P?I（超压?冲量）曲线。研究发现,混凝土强度对箱梁超压和冲量临界值影响较大,钢筋屈服强度对超压和冲量临界值影响较小。随着结构损伤等级的增大,各参数对箱梁P?I曲线的影响幅度各不相同。最后,对不同混凝土强度箱梁中各损伤等级P?I曲线进行公式拟合,并对拟合参数β进行分析。     

考虑横向变形的薄壁箱梁计算

在符拉索夫的虚功法的理论基础上,对符氏虚功方程进行扩充,讨论多箱带悬壁的薄壁箱梁在截面横向可变形及悬臂转动情况下,截面纵向、横向位移和应力计算方法。通过算例,分析虚功方程的计算结果。     

量子盒的弹道电导

应用量子力学波函数阻抗匹配方法,作者研究了准一维无相互作用电子气通过量子盒的弹道传播。在通过量子盒时,电子除受到盒边界的弹性散射外是自由的。作者计算了量子盒电导作为盒长度和宽度的函数。计算结果表明,当长度较短时,电导显示带有规则脉冲振荡的确定的量子化台阶;随着长度的增加,电导曲线逐渐趋于无规振荡的图样。     

Quasi‐random integration in quantum chemistry: Efficiency,stability, and application to the study of small atoms and molecules constrained in spherical boxes

This project consists of two parts. In the first part, a series of test calculations is performed to verify that the integrals involved in the determination of atomic and molecular properties by standard self‐consistent field (SCF) methods can be obtained through Halton, Korobov, or Hammersley quasi‐random integration procedures. Through these calculations, we confirm that all three methods lead to results that meet the levels of precision required for their use in the calculation of properties of small atoms or molecules at least at a Hartree–Fock level. Moreover, we have ensured that the efficiency of quasi‐random integration methods that we have tested is Halton=Korobov>Hammersley?pseudo‐random. We also find that these results are comparable to those yielded by ordinary Monte Carlo (pseudo‐random) integration, with a calculation effort of two orders of smaller magnitude. The second part, which would not have been possible without the integration method previously analyzed, contains a first study of atoms constrained in spherical boxes through SCF calculations with basis functions adapted to the features of the problem: Slater‐type orbitals (STOs) trimmed by multiplying them by a function that yields 1 for 0 < r < (R‐δ), polynomial values for (R‐δ) < r < R and null for r > R, R being the radius of the box and δ a variationally determined interval. As a result, we obtain a equation of state for electrons of small systems, valid just in the limit of low temperatures, but fairly simple. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Structural and mechanistic studies on ion insertion into the molecular box {[CpCo(CN)3]4[Cp*Ru]4}

The molecular box [CpCo(CN)₃]₄[Cp*Ru]₄ (Co₄Ru₄) reacts readily with a variety of monocations to form M⊂Co₄Ru₄⁺ (M=K⁺, Cs⁺, Rb⁺). Ion competition experiments, monitored by ESI-MS, show that the molecular box binds the smaller K⁺ more rapidly than Cs⁺, but that thermodynamically Co₄Ru₄ prefers the larger ion. The rates of ion-insertion for K⁺ and Cs⁺ into Co₄Ru₄ were found to qualitatively follow second order kinetics with K⁺, 300 M⁻¹ s⁻¹ and Cs⁺, 36 M⁻¹ s⁻¹. The ratio k_K/k_Cs qualitatively matched the ESI-MS results from ion competition experiments. The rates of ion-insertion into Co₄Ru₄ were found to depend on the counter anions. In particular, RbBF₄ reacted with Co₄Ru₄ more slowly than did RbOTf. The slower rates allowed us to establish second order kinetics. ¹H NMR studies reveal that the Cp signal for Co₄Ru₄ is very sensitive to the presence of entering ions, e.g., Rb⁺, whereas the corresponding Cp signal for Rb⊂Co₄Ru₄⁺ was insensitive to the presence of Rb⁺. The molecular structures of [Co₄Ru₄] · 6MeCN, [K⊂Co₄Ru₄]BF₄ · 7MeCN, [Cs⊂Co₄Ru₄]BF₄ · 6MeCN and [Tl⊂Co₄Ru₄]BF₄ · 6MeCN, determined by X-ray diffraction, showed that although the compounds crystallized in the same space group I23, a correlation exists between the Ru-N/Co-C bond distances and the size of the interstitial ion.