Heat treatment behavior of can-forged titanium aluminide alloy in ( α + γ ) region

The effect of initial microstructures on the heat treatment behavior of can-forged titanium aluminide alloy has been studied. Optical microscopy and EDX analyses results show that different initial microstructures, including difference in dislocation density, phase distribution and morphology, have inherent effects on the final heat treatment microstructure although at the same heat treatment temperature. An almost full lamellar (NFL) microstructure with an average α ₂/γ colony size of 20 μm was obtained through adjusting initial microstructure. Project supported by the “863” High Tech Program and the National Natural Science Foundation of China Synopsis of the first author Liu Yong, Doctoral student, born in April 1973. Specializing in powder metallurgy of ceramics, intermetallics and metal: 1) Ca/P based bioceramics; 2) TiAl based intermetallics; 3) Fe, Cu materials.     

嵌入式系统μC/OS-II在PC机上的实验与研究

μC/OS-II是源码公开的实时内核.主要介绍了μC/OS-II在PC机上的调试开发方法及其详细过程,介绍了*.MAK和*.BAT文件的设计和编写方法.实验证明该方法简单、可行.     

基于反向学习的自适应α约束病毒种群搜索算法

为了提高该算法求解约束优化问题的能力,提出一种新的约束病毒种群搜索算法。首先,提出自适应α-level比较策略,以在算法的不同阶段充分利用可行个体与不可行个体的有效信息;其次,为了进一步提高算法求解约束优化问题的收敛速度和搜索精度,针对算法的病毒扩散行为,提出了结合反向学习机制的搜索方程,以提高种群多样性并加速全局收敛。对CEC2006中13个约束优化函数的对比仿真结果表明,本文算法在搜索精度、收敛速度以及稳定性方面,相比于αSimplex算法、粒子群遗传算法算法、交叉人工蜂群算法算法以及约束改进差分进化算法算法具有明显优势。同时将该算法应用于无人机协同实时航迹规划约束优化问题中,通过仿真实验并与利用约束改进差分进化算法对这一问题进行求解的方法进行对比,验证了本文算法在规划效率、规避威胁等方面的优越性。     

鲁棒多目标优化问题ε - 拟弱有效解的最优性条件

研究了约束函数带有不确定因素的多目标鲁棒优化问题的最优性条件.首先,利用变分分析的工具(最大值函数的次微分、中值不等式、极限次微分的和规则等)建立不确定多目标优化问题的鲁棒ε- 拟弱有效解的最优性必要条件; 然后,在伪拟广义凸性的假设下,给出了该问题的最优性充分条件; 最后,用实例证明了相关结论的正确性.     

Adsorption of NO and NH3 over CuO/γ-Al2O3 catalyst

The selective catalytic reduction reaction belongs to the gas-solid multiphase reaction, and the adsorption of NH₃ and NO on CuO/γ-Al₂O₃ catalysts plays an important role in the reaction. Performance of the CuO/γ-Al₂O₃ catalysts was explored in a fixed bed adsorption system. The catalysts maintain nearly 100% NO conversion efficiency at 350 °C. Comprehensive tests were carried out to study the adsorption behavior of NH₃ and NO over the catalysts. The desorption experiments prove that NH₃ and NO are adsorbed on CuO/γ-Al₂O₃ catalysts. The adsorption behaviors of NH₃ and NO were also studied with the in-situ diffusion reflectance infrared Fourier transform spectroscopy methods. The results show that NH₃ could be strongly adsorbed on the catalysts, resulting in coordinated NH₃ and NH₄⁺ NO adsorption leads to the formation of bridging bidentate nitrate, chelating bidentate nitrate, and chelating nitro. The interaction of NH₃ and NO molecules with the Cu²⁺ present on the CuAl₂O₄ (100) surface was investigated by using a periodic density functional theory. The results show that the adsorption of all the molecules on the Cu²⁺ site is energetically favorable, whereas NO bound is stronger than that of NH₃ with the adsorption site, and key information about the structural and energetic properties was also addressed.     

Microscopic phase-field simulation for coarsening behavior of L12 and DO22 phases of Ni75Cr x Al25? x alloy

Based on the microscopic phase-field dynamic model and the microelasticity theory, the coarsening behavior of L1₂ and DO₂₂ phases in Ni₇₅Cr _x Al_25−x alloy was simulated. The results show that the initial irregular shaped, randomly distributed L1₂ and DO₂₂ phases are gradually transformed into cuboidal shape with round corner, regularly aligned along directions [100] and [001], and highly preferential selected microstructure is formed during the later stage of precipitation. The elastic field produced by the lattice mismatch between the coherent precipitates and the matrix has a strong influence on the coarsening kinetics, and there is no linear relationship between the cube of the average size of precipitates and the aging time, which does not agree with the results predicted by the classical Lifshitz-Slyozov-Wagner. The coarsening processes of L1₂ and DO₂₂ phases are retarded in elastically constrained system. In the concurrent system of L1₂ and DO₂₂ phases, there are two types of coarsening modes: the migration of antiphase domain boundaries and the interphase Ostwald ripening. Foundation item: Project(50671084) supported by the National Natural Science Foundation of China; Project(20070420218) supported by China Postdoctoral Science Foundation     

负载型γ-Al2O3三维粒子电极的制备及其对氯霉素的降解

以γ-Al₂O₃为载体,将Ti和Sn两种元素进行负载制备负载型γ-Al₂O₃粒子电极,采用X射线衍射（XRD）、扫描电镜（SEM）、X射线荧光光谱（XRF）、红外光谱（IR）对γ-Al₂O₃和负载型γ-Al₂O₃粒子电极进行表征。研究了电解时间对三维粒子电极法电催化氧化氯霉素的影响。采用初始浓度100 mg/L的CAP模拟废水,持续电解3 h后,制备的粒子电极通过三维电解对CAP去除率为72.8%,对TOC去除率低于3.7%,说明负载型γ-Al₂O₃粒子电极对氯霉素矿化作用较小。三维粒子电极对氯霉素的降解过程近似符合一级动力学方程,CAP初始浓度对去除率影响较小。粒子电极电催化氧化CAP的关键因素之一为·OH,外加叔丁醇对·OH进行清洗,相同条件下,氯霉素去除率降低至30%左右,表明氯霉素的降解是由阳极氧化和·OH间接氧化两种途径协同作用的。     

剪切变形对基桩P-Δ效应的影响

给出了小剪切变形下的基桩P-Δ效应和大剪切变形下支座P-Δ效应计算的杆单元刚度矩阵方程。假定杆单元弯曲变形位移函数为三次幂函数,剪切变形函数为线性函数,根据有限元法一般原理,推导了一种同时计入竖向力径向剪切分力剪切变形和水平力剪切变形的P-Δ效应杆单元刚度方程,推导了一种仅计入竖向力径向剪切分力剪切变形而忽略水平力剪切变形的P-Δ效应杆单元刚度方程,推导了一种仅计入水平力剪切变形而忽略竖向力径向剪切分力剪切变形的P-Δ效应杆单元刚度方程。计入水平力剪切变形而忽略竖向力径向剪切分力剪切变形的P-Δ效应杆单元可良好的模拟支座在大剪切变形下的偏心工作特性,能实时计入其偏心弯矩影响,为实时计入支座偏心特性的结构动静力分析提供了理论支撑。最后通过自编MATLAB程序进行算例分析,结果表明,计入支座大剪切变下的P-Δ效应后,基桩内力位移和地基土压力均显著增大。基桩自身剪切变形对桩身内力位移和地基土压力影响较小,可以忽略。     

一类非线性中立型随机延迟微分方程的截断型θ-EM方法

本文考虑了一类非线性中立型随机延迟微分方程,其漂移项系数和扩散项系数均是超线性增长的,且中立项满足压缩映射条件.本文建立了这类方程的截断型θ-EM算法,并得到了其收敛率.最后,给出一个例子验证了理论结果.     

基于μC/OS-Ⅱ的嵌入式μC/IP协议研究

传统的Internet应用以PC为中心，未来的Internet应用将转向以嵌入式设备为中心。据网络专家的预测，将来在Internet上传输的信息中将有70％的信息来自于小型嵌入式系统。本文提出了嵌入式设备网络化的一种方法：操作系统 嵌入式TCP／IP协议栈。介绍了实时嵌入式操作系统μC／OS-Ⅱ，给出了嵌入式TCP／IP协议栈μC／IP在μC／OS-Ⅱ上的实现方法，详细论述了系统的结构、工作原理及基本设计原则，并提出了改进方案。     

直线电机悬浮平台的μ-Η∞鲁棒控制

针对直线电机悬浮平台系统采用直接驱动方式易受参数变化、负载扰动、端部效应和齿槽效应等不确定性因素影响的问题,在系统模型反馈线性化的基础上,结合鲁棒控制器的设计方法和μ综合D-K迭代法,分别对悬浮平台系统的水平方向和竖直方向设计μ-Η_∞速度控制器.与速度控制器相比,该控制器具有更好的鲁棒性和快速性.仿真结果表明,采用了μ-Η_∞控制策略的系统对不确定性因素的影响有很好的抑制能力,实现了悬浮平台系统对定位精度、快速性和鲁棒性的要求.     

Promoting effect of licorice extract on induction of β-glucuronidase in Penicillium purpurogenum Li-3

Penicillium purpurogenum Li-3,a fungus producingβ-glucuronidase(PGUS),can convert glycyrrhizin(GL)to glycyrrhetinic acid monoglucuronide(GAMG)when grown in medium with GL as the sole carbon source.In order to improve the conversion rate of GL and the yield of GAMG,licorice extract(LE)was added as an inducer to enhance the production of GAMG by the PGUS.In this work,the influence of LE on the conversion rate of GL to GAMG was studied.When the Penicillium purpurogenum Li-3was grown in the medium containing LE and GL(concentration ratio of LE to GL was 2∶3),the conversion rate of GL was 84.12% with 38.18%increase and the yield of GAMG was 80.47% with 37.18%increase,comparing with to the medium only containing GL at 48h.The enzyme activity ofβ-glucuronidase was also enhanced from 22.4U/mL to 82.3U/mL,which increased up to about 3.67fold.The results showed that LE could significantly improve the induced expression level of PGUS.     

Delay-independent decentralized H ∞ control for multi-channel discrete-time systems with uncertainties

A robust decentralized H∞ control problem was considered for uncertain multi-channel discrete-time systems with time-delay. The uncertainties were assumed to be time-invariant, norm-bounded, and exist in the system, the time-delay and the output matrices. Dynamic output feedback was focused on. A sufficient condition for the multi-channel uncertain discrete time-delay system to be robustly stabilizable with a specified disturbance attenuation level was derived based on the theorem of Lyapunov stability theory. By setting the Lyapunov matrix as block diagonal appropriately according to the desired order of the controller, the problem was reduced to a linear matrix inequality （LMI） which is sufficient to existence condition but much more tractable. An example was given to show the efficiency of this method.     

基于α-DDTW算法与功率波形相似度的馈线OP互联匹配

OP互联是指供电企业内部对电力调度系统（OMS）及设备（资产）运维精益管理系统（PMS）中维护的台账数据进行有效关联。针对中压配电网10 kV馈线OP互联流程复杂、效率低下,且缺乏有效校验机制等问题,提出了一种基于配电网多源量测数据与系统台账信息的馈线OP数据校核与匹配方法。首先,从OMS和PMS中提取功率、设备参数等信息,并对台账及功率进行预处理,形成功率时间序列矩阵;然后,基于α-DDTW距离评估两侧馈线功率波形近似度,实现馈线OP数据的校核与关联匹配;最后,对华东某市电力公司的系统数据进行算例分析,验证了所提方法的有效性与实际工程应用价值。     

Effects of Polymers on Phase Transition of ε-CL-20 and CL-20-Based PBXs

The powder X-ray diffraction technique is applied to investigate phase transitions ofε-CL-20 coated with additives(polymers and wax)and ofε-CL-20 heated in petroleum ester at different temperature points.First,CL-20-based plastic-bonded explosives(PBXs)were prepared by mechanical kneading.Characteristics of different polymer binders were measured and the relationship between polymer properties and sensitivity of CL-20-based PBXs was analyzed.The results indicated thatε-CL-20 coated with or without additives both showed high stability in the crystal phases at different temperature in petroleum ether.Compared with thermal conductivity,friction efficient and specific heat capacity,hardness of polymers has the most dominant effect on the sensitivity of CL-20-based PBXs.Butadiene rubber(BR)showed the best desensitizing effect among the chosen binders.Combination of EPDM and other several polymers(C-EPDM)as the polymer binder has higher press density and a lower expansion rate.     

μPD7810/11反汇编程序

μPD7810/11反汇编程序是一个标准的反汇编程序,它可以把μPD7810/11单片机的机器码翻译成汇编语句,便于用户阅读和分析。在反汇编中采用了分类、链标志、对分查找、语句组合等方法,从而使反汇编过程能够准确迅速地进行。反汇编程序向用户提供了一种十分重要的软件开发手段。     

信息率失真率函数R(D)的预估-校正计算法

在精度不是很高的情况下先估计出S的近似值,然后调整精度校正S值,再计算信息率失真函数R(D)的近似值.     

基于ARM9和μC/OS-Ⅱ的μC/TCP-IP协议栈移植

以Samsung公司的S3C2410A芯片为核心处理器,建立一个基于ARM的硬件开发平台,说明如何在嵌入式实时操作系统μC/OS-Ⅱ上移植并且实现μC/TCP-IP这套TCP/IP协议栈,使μC/OS-Ⅱ成为支持网络的RTOS。并详细分析了μC/TCP-IP协议栈的任务模型以及接收以太网包与发送以太网包的过程。     

μC/OS-Ⅱ内核分析

嵌入式系统在目前的应用中越来越广泛,嵌入式实时操作系统也成为操作系统研究领域的一个新方向,与其他实时操作系统相比,μC/OS-Ⅱ以其内核小巧、源码开放、可裁剪、占用空间小、可移植性强等多种特性在嵌入式实时操作系统中占有很重要的地位,该论文就μC/OS-Ⅱ的内核进行了分析,为做移植提供了技术支持。     

μC/OS-Ⅱ内核分析

嵌入式系统在目前的应用中越来越广泛,嵌入式实时操作系统也成为操作系统研究领域的一个新方向,与其他实时操作系统相比.μC/OS-Ⅱ以其内核小巧、源码开放、可裁剪、占用空间小、可移植性强等多种特性在嵌入式实时操作系统中占有很重要的地位,该论文就μC/OS-Ⅱ的内核进行了分析,为做移植提供了技术支持.