太阳能热泵热水系统循环水流量控制仿真

设计了一套新的太阳能热泵热水系统,介绍了该系统的工作原理和特点,分析表明,该系统既具有普通太阳能热泵的优点,又能够实现供暖、供冷、全年供应生活热水等多种功能。采用机理建模的方法建立了房间冷负荷、风机盘管、执行器、传感器和循环水系统的传递函数模型。设计了太阳能热泵热水系统的循环水系统PID控制、模糊控制和模糊自适应PID控制三种控制方案,并针对设计的三种控制方案对系统进行了控制仿真。结果表明,从调节时间、超调量和阶跃响应等几个方面综合考虑,由于模糊自适应PID控制能够在线调整控制系统的特性参数,随时适应系统的运行变化,在太阳能热泵热水系统的循环水系统运行控制上具有明显的优势。     

基于STAMP的航空管制空中危险目标识别方法研究

为了保证航空管制中航空器的完整性,提高航空器的使用寿命,并且可以最大限度的保障航空乘客和其他航空人员的人身安全,需要对航空管制空中危险目标进行识别。但采用当前目标识别方法对空中危险目标识别时,识别系统对空中危险目标无法稳定识别,存在空中危险目标识别精度低的问题。为此,提出一种基于STAMP的航空管制空中危险目标识别方法。该方法先利用STAMP模型对航空管制空中危险目标识别系统各组成部分进行任务分配,然后采用Harris法对空中危险目标进行特征选择和提取,依据Mean-Shift法的Bhattacharyya系数,描述候选空中危险目标和空中目标的危险概率分布相似度,随着Bhattacharyya系数的不断增加,候选空中危险目标和空中危险目标的相似度越大,使危险目标跟踪系统朝着空中目标危险密度增大的位置移动,在最优位置收敛,从而实现空中危险目标跟踪,最后利用D-S理论对跟踪结果进行识别,通过引入空中目标危险性基本概率赋值函数获得空中目标危险基本概率,采用Dempster组合规则对空中目标危险证据进行合成,依据空中危险目标证据融合结果完成对航空管制空中危险目标的识别。实验仿真证明,所提方法增强了航空管制空中危险目标识别的效果,提高了航空管制空中危险目标识别的精度。     

基于Matlab/Simulink的电压型超导储能功率调节控制仿真

本文首先对电压型超导储能（Voltage-Superconducting-Magnet-Energy-Storage,简称VSMES）功率调节系统（Power-Conditioning-System,简称PCS）的原理进行介绍,并运用Matlab/Simulink仿真分析软件,针对三相电压型超导储能功率调节系统的控制过...     

New Spectrophotometric Method for Azithromycin Determination

Abstract

Azithromycin (AZT), an antibiotic belonging to the family of macrolides, can be analyzed by a new spectrophotometric method based on the formation of an ion pair between this drug and an inorganic complex of (Mo(V)–thiocyanate) followed by its extraction with dichloroethane. This ion‐association complex shows an orange color and exhibits a maximum absorbance at 469 nm. The experimental conditions of the reaction were studied and optimized. The calibration graph was linear (r=0.9996) over the range 10^?6 M–10^?5 M of AZT. This simple and validated method has been successfully applied to the determination of azithromycin in pharmaceutical formulations with a mean relative standard deviation of 1.07% and mean recovery of 99.66%. The common excipients present in azithromycin formulations did not interfere in its determination. This new spectophotometric method has been applied successfully to illustrate the dissolution profiles of original tablets and generic compounds; hence, it could be employed in routine quality control of azithromycin in pharmaceutical dosage forms.     

A cone programming approach to the bilinear matrix inequality problem and its geometry

We discuss an approach for solving the Bilinear Matrix Inequality (BMI) based on its connections with certain problems defined over matrix cones. These problems are, among others, the cone generalization of the linear programming (LP) and the linear complementarity problem (LCP) (referred to as the Cone-LP and the Cone-LCP, respectively). Specifically, we show that solving a given BMI is equivalent to examining the solution set of a suitably constructed Cone-LP or Cone-LCP. This approach facilitates our understanding of the geometry of the BMI and opens up new avenues for the development of the computational procedures for its solution. Research supported in part by the National Science Foundation under Grant CCR-9222734.     

Fabrication and characteristics of self‐aggregation nanoparticles used for conformance control treatment

In order to alleviate the contradiction between injectability of the profile control agent and its profile control performance, a novel core‐shell heterogeneous structure colloidal particles (CSA) were synthesized, and the mechanism of self‐aggregation plugging was proposed. Cross‐linking inside the nanoparticles and chain‐growth polymerization via capturing acrylamide in the aqueous phase result in the formation of core‐shell heterogeneous structures as proved by TEM observation and XPS analysis. Moreover, CSA nanoparticles exhibit good hydrophilic properties, outstanding thermal stability and limited expansion capacity. Effects of different metal cations and surface group on the self‐aggregation time of CSA nanoparticles were systematically studied. Results showed that divalent cations contributed to more significant aggregation of CSA nanoparticles in comparison to monovalent cations. The increasing cations concentration and valency decreased the thickness of electric double layer, which lead to a decrease in the zeta potential. Core flooding test shows that the injection of nanoparticles which diameter is much smaller that of pore‐throats into the target reservoir can not only successfully enter the depth of porous media, but also effectively block the high permeability areas by the formation of self‐aggregation particle clusters. This study provides a new method for the equilibrium between nanoparticles injectivity and in‐depth profile control of nanoparticles.     

A Globally Convergent and Efficient Method for Unconstrained Discrete-Time Optimal Control

Shift schemes are commonly used in non-convex situations when solving unconstrained discrete-time optimal control problems by the differential dynamic programming (DDP) method. However, the existing shift schemes are inefficient when the shift becomes too large. In this paper, a new method of combining the DDP method with a shift scheme and the steepest descent method is proposed to cope with non-convex situations. Under certain assumptions, the proposed method is globally convergent and has q-quadratic local conve rgence. Extensive numerical experiments on many test problems in the literature are reported. These numerical results illustrate the robustness and efficiency of the proposed method.     

基于超高速相机的数字图像相关性全场应变分析在SHTB实验中的应用

基于超高速相机和数字图像相关性全场应变分析方法对传统的分离式Hopkinson拉杆(SHTB)实验系统进行改进,获得尼龙和铝合金材料的动态拉伸应力应变曲线,验证了数字图像相关性全场应变分析在SHTB实验中的有效性。实验结果显示:该方法测量的平均应变与应变片测量结果一致性很好, 而传统的SHTB实验原理计算的应变结果则明显偏大,需要对试件原始标距进行修正后才能获得有效的试件应变,并且在试件的材料和几何尺寸不变的条件下标距修正不依赖于应变率。基于数字图像相关性全场应变测量,讨论了应变均匀性问题:脆性的尼龙试件在标距范围内应变均匀性良好,而韧性的铝合金试件表现出比较严重的应变不均匀性,归因于颈缩变形的影响。     

一类关节型机器人操作手的迭代学习控制

针对一类机器人操作手，提出了一种设计机器人操作手迭代学习控制的新方法，与其它现有的迭代学习控制方法相比较，当折合到机器人操作手关节轴上的驱动装置惯量足够大时，可以用驱动装置的动力学特性参数确定学习增益，克服了传统迭代学习控制方法由多次尝试选取学习增益的缺点，增强了实用性。在实际机器人操作手上的实验结果充分表明了新提出方法可获得较高学习速度和控制精度的优越性。     

数字图像相关的噪声导致系统误差及散斑质量评价标准

数字图像相关中散斑质量评价标准应该综合考虑系统误差和随机误差的作用。之前的工作考虑了无图像噪声情况下插值引起的系统误差,本文则进一步研究了有图像噪声情况的系统误差,并与随机误差综合考虑提出了完善的散斑质量评价参数。本文推导了有噪声情况下系统误差的解析形式,揭示了噪声引入系统误差产生的内在本质在于插值引起噪声不确定性对亚像素位置的依赖。依据理论分析,插值噪声耦合函数的概念被引入,它由插值基函数平移平方和的斜率决定,表征了噪声引入系统误差随亚像素位置的变化。插值耦合函数将之前的研究成果纳入统一的理论体系,并从本质上解释了高阶B-样条插值对应的噪声引起系统误差较小的现象。数值模拟与本文的理论分析显示一致,在真实的亚像素平移实验验证中,本文将公式推广到非均匀噪声情况,并与实验结果获得了较好的吻合。基于对系统误差的理论分析,综合考虑系统误差和随机误差影响,提出了两种计算误差评估参数:总误差的最大值和平方平均值,并提出了快速估计算法且通过数值模拟进行了验证。计算误差评估参数实际也是一种散斑质量评价参数,提出的评估参数弥补了现存散斑质量评价参数未足够考虑插值影响的缺陷,是更完善的散斑质量评价标准。本文应用新提出的散斑评价参数对一些常见散斑图进行了评价,并将其用于对模拟散斑图的优化。