Uncertainty analysis and ANOVA for the measurement reliability estimation of altitude engine test

The altitude engine test is carried out to measure the performance of the engine of flight vehicle at the high altitude environment prior to the flight test. During the test, The measured pressures and temperatures at various positions, air flow rate, fuel flow rate, thrust of the engine are measured. These measured values are used to calculate the representative performance values such as the net thrust and the specific fuel consumption. Hence each of the measured parameter has effects on the total uncertainly of the performance values. In this paper, the combined standard uncertainties of the net thrust and the specific fuel consumption were estimated from the uncertainties of the various measured values. Also, by estimating the repeatability and the reproducibility, the confidence levels of the altitude engine test were validated by the analysis of variation on the repeated test data by different tester groups.     

一种改进的变网格模板数字图像快速拼接算法

针对工程上需要对大量序列图像拼接,并实时显示的要求,提出了一种改进的基于变网格模板匹配的快速拼接算 法(VGMA),该算法将网格模板在匹配过程中不断调整尺寸,克服了原有网格匹配算法的缺点。在保证拼接速度的情况 下,可以大幅度提高拼接精度,适用于大量序列图像的快速拼接。     

计算机辅助加工顺序优化

建立了制造单元加工过程的Petri网模型,采用关联矩阵来表征Petri网模型结构,并由之获得可达标识并进而得到由初始标识到最终的不同的变迁序列,根据变迁序列和加工过程的对应关系得到优化的加工顺序。     

基于.net技术的自动化立体仓库管理与控制系统的研究与实现

研究并开发了基于.net的自动化立体仓库管理与控制系统。该系统运行于微软.net平台,采用ASP.NET技术和ADO.NET技术,实现了仓库所需的各项业务操作并具有界面友好、便于维护、信息共享性及扩展性好等许多优点,为实现仓储物资可视化提供了一个有价值的解决方案。     

低位余热动力回收方案的拟订方法

本文探讨了合理评价低位余热动力回收方案经济性的指标问题,建议采用“净收益”M、并适当兼顾“资金回收期”τ。本文提出院以动力工质加热过程的予热段吸热量与总吸热量之比值a作为筛选动力工质的判据。应选用a值较高的低沸点工质。本文还进一步分析了动力工质的蒸发温度t 3、冷凝温度t 4、冷却水出口温度t 8、以及换热器中节点温差△t p的影响,发现：t 3、t 4和t 8都存在各自的最佳区;在技术条件允许的情况,减小△t p是有利的,因而要求研究小温差传热强化的有效途径与研制相应的高效换热器,并开展其他有关的基础研究,作好科学储备。     

一种新的面向用户的工作流模型

为满足企业用户对工作流模型的描述能力和分析能力的要求,提出了一种新的面向用户的工作流描述模型——工作流描述网。该描述网可直接支持所有的工作流模式,特别是多实例、取消、高级同步等绝大多数工作流模型不直接支持的模式;通过提供多实例任务、取消任务、带传递变迁的任务等高级组件,直接支持工作流模式中几个主要复杂模式,每一个高级组件都对应一定结构的工作流描述网,并具有形式化的语义,在分析时按照一定的规则展开;基于Petri网,通过增加控制变量,及其与变迁间的通信机制来弥补Petri网无法处理复杂数据结构的缺陷。最后,通过实例说明了如何对各种复杂流程进行建模和分析。     

Formability evaluation of dimple forming process based on numerical and experimental approach

Exhaust gas recirculation (EGR) cooler consists of a number of heat transfer tubes that have relatively larger net area than that of flat type tubes. The surface of the tubes is made up with lots of grooves and protrusions for enlarging the net heat transfer area. Most tubes are manufactured through forming processes, such as bending, spinning, roll forming, stamping and so on. Therefore, a series of fracture or defect can occur during the various forming processes. In this study, the manufacturing process of a dimple-type rectangular heat transfer tube used for an EGR cooler system is investigated based on the numerical simulation and the experimental approach. A prototype of the tube is designed and modified to a newly designed tube considering the conservation of the net heat transfer area based on the numerical and analytical approach. Formability evaluation of the tube sheet is carried out by using forming limit curves based on the plastic instability conditions. Strain- and stress-based forming limit curves are utilized to ensure the strain path independence. The newly designed tube having a number of dimples on the both sides are manufactured by the press forming process. Thickness distributions for the principal cross-sections are observed from both the simulation and the experiment and compared each other. From the results, it is confirmed that the forming process is robust to manufacture the dimple type rectangular tubes with the comparison of thickness, and application of the forming limit curves.     

制造/再制造物流系统集成分区-选址-运输问题研究

在综合考虑制造/再制造物流系统的分区,选址和运输问题,以及运输和设施建设成本的规模经济效应的基础上,建立了两阶段规划模型,用来确定客户分区,选址方案,配送、回收的物流分配和运输路径,使运营周期内的净收益最大.最后通过一个算例验证了模型和算法的有效性.     

Surface activation of carbon film supports for biological electron microscopy

The effect of glow-discharging on maked carbon-filmed grids has been evaluated. The effect of different locations of the grids within a DC discharge, operated in the normal glow, was analyzed by applying various biological specimens to the grids. Two locations were found to give consistent results: (a) in Crookes dark space, particulate specimens, negatively stained, spread evenly — suggesting a net negative surface charge of the support; (b) below the anode, nucleic acids, selectively (positively) stained, appeared as well spread filaments, indicating a net positive surface charge.     

一种基于时间Petri网的航空项目数据管理模型

为了提高项目对数据冲突和动态综合管理的能力，提出了一种基于时间Petri网的航空项目数据管理模型。该模型利用库所包含项目的所有共享数据，在资源约束的条件下，进行时间、资源、成本等数据的综合管理。讨论了对资源冲突与均衡控制的调控方法。以某航空产品的制造装配为例，表明利用该模型，可以较好地处理项目运行过程中产生的资源冲突等问题，使各种资源的利用达到最优化，从而实现对资源的最大利用率。     

Three-dimensional reconstruction from images of tilted specimens: the paramyosin filament

The three-dimensional structure of the paramyosin filament has been reconstructed from images obtained when the specimen is tilted at different angles about its long axis. The micrographs were correlated spatially using gold marker beads and digitized. The different views contained in each micrograph were combined using a computational technique involving Fouri***er transforms and the resulting three-dimensional images are presented as various sets of serial sections. The results confirm that the Bear-Selby (1956) net can be seen at all levels in the specimen.     

面向复杂产品的问题流网络构建及求解过程模型

针对经典TRIZ理论工具解决复杂产品中多冲突问题具有的局限性,强势思维一般理论（General theory of powerful thinking,OTSM）主要解决复杂跨学科创新性问题并进行一般化的表达,但没有明确给出消除多冲突及寻求最优解决路径的一般方法。通过对复杂产品构建问题流网,从中选取关键问题,进而转化成冲突网,然后对其中的关键冲突进行判别并转化成参数网,应用TRIZ工具进行冲突解决并提出解决方案,提出了关键问题的判别方法和关键冲突网到参数网的转化规则,给出了问题流网、冲突网及参数网的构建过程,最终建立了面向复杂产品的问题流网络构建与求解过程模型。以工程机械900吨架桥机作为实例进行创新设计,验证了该过程模型的有效性。     

利用转子故障耦合动力学系统模型识别油膜涡动下的碰摩故障

转子碰摩故障通常为不平衡、不对中以及油膜涡动等故障引发的二次故障,其信号通常具有周期、拟周期和混沌这3种复杂的非线性特征。本文针对油膜涡动下的转子碰摩故障诊断问题,建立了含不平衡、油膜涡动以及碰摩故障耦合动力学模型,利用数值仿真研究了转子系统在油膜涡动下的碰摩故障频谱特征,提取了反映耦合故障的特征信息。为了准确的对碰摩故障进行诊断,通过不断改变系统参数获取了包括各种状态下的耦合故障样本。最后构造了结构自适应神经网络,利用一半样本对神经网络进行训练,再用另一半样本对训练好的神经网络进行测试,识别率达到了94%以上。计算结果充分表明了本文方法对于识别油膜涡动和碰摩耦合故障的有效性。     

Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics

We present a critical review of methods for defining the chemical environment during liquid cell electron microscopy investigation of electron beam induced nanomaterial growth and degradation. We draw from the radiation chemistry and liquid cell electron microscopy literature to present solution chemistry and electron beam–based methods for selecting the radiolysis products formed and their relative amount during electron irradiation of liquid media in a transmission electron microscope. We outline various methods for establishing net oxidizing or net reducing reaction environments and propose solvents with minimal overall production of radicals under the electron beam. Exemplary liquid cell electron microscopy experiments in the fields of nanoparticle nucleation, growth, and degradation along with recommendations for best practices and experimental parameters are reported. We expect this review will provide researchers with a useful toolkit for designing general chemistry and materials science liquid cell electron microscopy experiments by ‘directing’ the effect of the electron beam to understand fundamental mechanisms of dynamic nanoscale processes as well as minimizing radiation damage to samples.     

基于几何约束的Doo-Sabin细分曲面修改算法

给出了Doo-Sabin细分曲面在奇异面的极限位置和法矢计算公式,定义了正则网格带的局部等参数线。通过建立局部坐标系对曲面上所有点进行局部参数化,把曲面上点的位置、法向量及局部等参数线等约束转化为所有待调整控制顶点的约束,得到线性系统,从而可以在满足上述多种不同类型的几何约束时修改曲面的形状。从控制网格扰动量最小和能量优化的角度给出两种修改算法,并利用广义逆矩阵求得显式解。约束的线性关系表明,两种方法都存在逆过程,修改的结果与过程无关,便于实际操作与控制。     

基于C++的电力电子装置仿真方法研究

基于电路理论、皮特里网络和面向对象程序设计方法,建立了电力电子元件的仿真模型,基于这些具体的元件模型,将电力电子装置仿真中开关状态变化检测工作和兼容性检测工作编程成通用子程序。运用阶段分析法对具体的三相桥式整流电路进行仿真。     

电视节目非线性编辑网拓扑结构异同与安全性辩析

电视节目非线性编辑与传统线性编辑相比有许多无法比拟的优势.非线性编辑网在我国各级电视台的应用越来越广泛,网络安全问题日益突出,本文介绍了几种常用的非线性编网络拓扑结构,并分析了在网络拓扑结构在安全性方面的特点.     

基于 Petri 网的企业 CIM 系统建模方法研究

介绍了ＣＩＭＯＳＡ建模方法，指出Ｐｅｔｒｉ网是帮助企业建立正确和优化模型的有效方法。提出了一种扩展的有色Ｐｅｔｒｉ网方法——控制和集成网方法，并给出它的定义和符号表示形式，在此基础上研究了ＣＩＭＯＳＡ模型的Ｐｅｔｒｉ网表示法。     

Synthesis of feedback control elements for discrete event systems using Petri net models and theory of regions

This paper describes a method for constructing a Petri-net-based controller for a discrete event system (DES) modelled by a Petri net. Assuming that an uncontrolled Petri net model of the DES and a set of forbidden state specifications are given, feedback control elements, i.e. a set of places and related transitions, with initial marking, are computed using the theory of regions, which is a formal synthesis technique for deriving Petri nets from automaton-based models. When feedback control elements are added to the uncontrolled Petri net model, the controlled (closed-loop) Petri net model of the system is obtained. The controlled Petri net model obtained is maximally permissive while guaranteeing that forbidden states do not occur. The proposed method is computationally efficient and does not suffer from the state explosion problem. Two examples are provided to show the applicability of the proposed method.     

一种基于Elman神经网络的液压泵故障诊断技术

针对传统BP网络进行液压泵故障诊断时，网络学习具有收敛速度慢和学习、记忆不稳定的缺陷，提出将Elman神经网络应用于液压泵故障诊断，建立Elman神经网络的结构模型，介绍了该网络的训练算法，阐明了液压泵故障诊断的实现过程。通过试验验证了该神经网络收敛速度快，学习记忆稳定，具有很好的学习功能；测试结果表明该诊断方法具有高可靠性，达到了预期的结果，可以用于液压泵故障诊断。