一类MIMO非线性系统的自适应模糊输出反馈控制

针对一类MIMO非线性状态不可测系统,提出了一种稳定的基于观测器的自适应模糊控制方法.该方法不需要系统状态可测的条件,而是通过设计模糊观测器来估计系统的状态.证明了所提出的控制方法可保证闭环系统的稳定性和跟踪误差的收敛性.仿真结果进一步验证了该控制方法的实用性和有效性.     

单纯形法中进基变量的选择

对通常用的单纯形法进行了深入讨论，对进基变量的选择作了改进，避免在一次迭代中刚进入基变量的变量在紧接着的下一次迭代中立即被替换出来，从而加快了迭代速度，还举例说明了改进后的单纯形法的解题步骤．     

高分子反应Markov过程的渐近性质分析

以存在凝胶化现象的高分子反应模型为背景,定义了高分子反应所对应的可逆M arkov过程,给出了过程的稳定分布及配分函数,推导出了分子间协方差的表达式.通过对该过程在下临界、临界、上临界状态下的渐近性质的分析,证明了仅在临界状态下系统存在长程相关性.     

函数列一致连续和一致收敛及等度连续的关系

连续、一致连续、一致收敛和等度连续是函数或函数列非常重要的性质．针对收敛的函数列，探讨了一致连续、一致收敛和等度连续两两之间的关系，并在有界区间上给出了一致连续、一致收敛和等度连续的等价关系．     

使用Mathematica研究KDV方程的一类孤立子解

使用简化的KDV方程的解析孤立子解,借助于Mathematica软件,展示了孤立子解的物理特点,并完成了双孤子碰撞过程的动画仿真,形象地展示了孤立子的准粒子性.     

采用虚拟时钟的多时钟域电路模型检测

随着系统规模的扩大和复杂性的增加,设计验证已成为集成电路设计中最大的挑战。符号模型检测(Formal model check)的验证方法由于可以解决验证的完备性问题,正受到越来越多的重视。在多时钟域设计已成为大规模集成电路设计热门领域的今天,原来的符号模型检测方法无法直接进行多时钟域的验证。通过建立一个虚拟时钟来代替原来的多个时钟,并对原电路以及CTL(Computation Tree Logic)进行适当改写,使之能直接用符号模型检测的方法进行验证,并对改写的电路进行了复杂度分析。     

Characteristics of mechanical alloyed Ni-Al powder for sintering

Mechanical alloying was employed to obtain high-activity Ni-AI powder. The effects of mechanical alloying on the microstructure and characteristics of milled powder with a normal composition of Ni-22.89 at.% AI-0.5 at.% B were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that a solution Ni （AI） was obtained after milling. During mechanical alloying, the milled powder obtains extra surface energy and crystalline energy because the crystallite size becomes free and the lattice strain increases with the milling time prolonging. Furthermore, about 0.5 mol% oxide in the particles were formed after milling, and this kind of dis- persed oxide is effective to improve the properties of the sintered alloy by dispersion strengthening. It is confirmed that Ni3AI alloy with outstanding properties has been prepared with mechanical alloyed powders.     

Magic angles (Lebed''s and others), and the phase diagram of the Bechgaard Salts

We present transport data on the metallic and Field Induced Spin Density Wave phases of the Bechgaard Salts (TMTSF)₂PF₆ and (TMTSF)₂ClO₄. The a and c axis resistivities (ρ_XX and ρ_ZZ) of these compounds have been measured for magnetic field rotations in the b-c planes (Lebed geometry) and striking resistance dips are observed at magic angles. We examine the differences between the two materials and the status of our understanding of the Lebed resonances. We then investigate the resistivities for magnetic fields rotated in the a-c plane. In this case we find a new set of resonances which for the first time allow direct measurements of the Fermi surface parameters of quasi-one- dimensional metals. Extending ρ_XX and ρ_ZZ measurements to 30 Tesla we have found that the phase boundary for the FISDW in (TMTSF)₂ClO₄ is most easily investigated by temperature dependent studies of ρ_ZZ at high field. We find a new phase below a nearly temperature independent and we discuss some of the properties of this phase.     

Pulsed laser deposition of antifriction thin-film MoSex coatings at the different vacuum conditions

MoSe_x coatings were obtained by pulsed laser deposition in vacuum at the pressure of background Ar gas up to 10 Pa. The deposition temperature was 200 °С. The films were studied by means of X-ray diffraction, scanning and transmission electron spectroscopy, X-ray photoelectron spectroscopy, and Rutherford backscattering spectroscopy of helium ions. The tribological properties of thin-film coatings were investigated by pin-on-disk testing in air with 50% relative humidity. In addition, wear tracks were studied by micro-Raman spectroscopy. Chemical composition, structure, and tribological properties of the coatings were found to be sensitive to the presence of the inert gas. Thus, increasing the gas pressure from 10^− 4 to 10 Pa changes the chemical composition, so that the ratio of the atomic concentrations of Se and Mo (x = Se/Mo) increases from 1.5 to 2.4 in the principal deposition zone. The changing of the structure concerns the accumulation of distortions in the lattice of MoSe_x nano-crystals as increasing the distance between the basal planes and intensive formation of nano-sized inclusions of the amorphous phase and Mo nano-crystals in the volume of the coatings. At the optimal gas pressure (∼ 2 Pa), the composition of the coating was close to the stoichiometric one, and the layer adjacent to the substrate consisted of MoSe_x nano-crystals with the basal planes parallel to the substrate surface or oriented at small angles to the surface. The thickness of the oriented layer in such coatings was greater than the thickness of the similar layer in the coatings deposited in vacuum (10^− 4 Pa). The tribological properties of MoSe_x coatings deposited on substrates of stainless steel type 95 × 18 (18 at.% Cr) depend on the gas pressure. The friction coefficient in air decreases from 0.08 for deposition at the background pressure of 10^− 4 Pa to 0.04 for deposition at the optimal pressure. This change in the deposition conditions has only a marginal effect on the coating durability. Means to increase the durability are also considered.     

Precipitation in long term thermally aged high copper,high nickel model RPV steel welds

Copper precipitation in irradiated RPV steels is well known to have a deleterious effect on mechanical properties. In order to understand the contribution of thermal ageing to RPV embrittlement a high copper (0.44 at.%), high nickel (1.6 at.%) model RPV weld was thermally aged at 365 °C for times up to 90,000 h. Atom Probe Tomography (APT) was employed to study the precipitation of solutes, primarily copper, nickel, manganese and silicon within the matrix and at grain boundaries. As expected, a high number density of 1–4 nm radius copper rich precipitates was observed. Nickel, manganese and silicon were found at the precipitate matrix interface, and the evolution of the composition of this interface was investigated with ageing time. Segregation of solutes to grain boundaries particularly P, Mo and C was observed, along with enrichments of Ni, Mn and Si, which have not previously been reported in long term thermally aged RPV steels. Preliminary results on several large (>10 nm) Ni–Mn–Si rich features observed at a grain boundary are also presented. These features are rich in Ni (∼30%), Mn (∼15%) and Si (∼12%) and are virtually copper-free.