多变量因果驱动的系统服役安全状态评估方法

针对传统状态评估侧重于关键生产单元,未考虑监测变量间的因果关系对状态评估精度的影响等问题,提出一种基于多变量因果驱动的复杂机电系统服役安全状态评估方法。从频域角度将广义偏定向相干分析法用于系统变量之间的因果测度分析,建立反映系统实时运行状态的因果网络模型。基于该模型,从多维统计的角度利用网络平均路径长度、聚类系数和网络结构熵提取系统的关键运行特征,并通过融合形成反映系统服役状态的综合指数。选取某化工企业实际运行过程中典型机组的故障数据进行验证,结果表明,相对于单一维度的状态评估指标,融合后形成的综合指数能够更加全面、准确地反映系统服役状态演化。     

基于近似似然的频响函数不确定性模型修正

针对流程工业复杂机电系统状态不断更迭、性能出现漂移等问题，提出了一种基于自组织特征映射网络的系统服役过程动态标记方法。首先，构建多变量间耦合关系网络，并在此基础上提取网络特征；其次，将动态标记过程分为状态主动更新过程和状态主动更新过程两个阶段，状态被动更新过程通过不断训练自组织特征映射网络来适应系统新状态出现及性能漂移等情况，状态主动更新过程可用于消除系统已消亡状态对网络模型产生的影响；最后，通过分析实际化工生产系统监测数据对所提方法进行有效性验证。实验结果表明，该方法可有效标记复杂机电系统服役过程中不断变化的多种状态，并建立符合系统动态演化过程的状态标记知识库，从而为系统状态辨识和预测提供可靠依据。     

复杂机电系统耦合与解耦设计--现代机电系统设计理论的探讨

针对现代大型复杂机电系统的性能与运行状态多物理过程和多参数全局耦合结果的实,提出了对复杂机电系统进行全局耦合分析及合并行设计的基本思想,探讨了全局耦合分析与设计的基本理论框架,以其研究复杂机电系统功能,奇异工况的生成机制,实现,复杂机电系统的全局耦合最优设计。     

面向复杂模块化产品族演化控制的评价方法

针对模块化产品族的演化控制问题,提出面向模块化产品族复杂程度的网络化评价方法。将产品族中的模块描述为节点,模块间的关系描述为边,并将模块化产品族抽象形成产品系统的模块关系网络。借助模块关系网络,从模块、关系和系统三个层次对产品族进行量化描述,形成由模块信息量、信息耦合比、关重度、关系强度和系统信息结构熵5个量化指标组成的评价体系。基于量化指标的工程意义,设计人员可以对产品族系统进行复杂程度评估和演化状态监控。以某轮式装载机铲斗的模块化系统为例,验证了所提方法的可行性。     

基于IDEF的复杂机电系统状态解析

利用功能-行为-状态建模思想,提出了基于IDEF的复杂机电系统状态解析方法。首先利用IDEF0建立复杂机电系统功能结构的形式化表达,然后基于功能-行为映射关系并根据行为之间的时序、逻辑关系利用IDEF3建立复杂机电系统行为过程的形式化表达,最后将系统行为过程形式化表达模型中的行为单元的行为映射为状态,形成复杂机电系统的状态变迁网络。基于状态变迁网络,可以获得复杂机电系统行为过程中的状变迁序列,进而实现复杂机电系统的状态解析。     

VPMCD和模糊熵在转子系统故障诊断中的应用

针对转子系统的故障特征,提出了基于多变量预测模型（variable predictive mode based class discriminate,简称VPMCD）和模糊熵的故障诊断方法。VPMCD方法是根据所提取的全部或部分特征值之间具有的某种内在关系建立预测模型,并以建立的变量预测模型进行模式识别。首先,对转子振动信号进行经验模态分解(empirical mode decomposition,简称EMD),得到若干个内禀模态函数（intrinsic mode function,简称IMF）分量;接着,提取包含主要故障信息的前几个IMF分量的模糊熵组成故障特征向量矩阵;然后,采用VPMCD方法建立预测模型;最后,通过建立的VPMCD预测模型区分转子的工作状态和故障类型。实验分析结果表明,基于VPMCD和模糊熵的故障诊断方法可以准确、有效地识别转子系统的工作状态和故障类型。     

基于最大故障诊断信息量准则的多负荷传感液压系统监测点优化设计

对特种叉车多负荷传感液压系统的监测点进行分析,建立了多负荷传感系统的测试信号有向图和“元部件-监测点”相关性模型。利用信息论中熵的概念,综合评判最大故障诊断信息熵、较短测试时间和较低测试成本以实现故障诊断,建立了最大故障诊断信息量准则,并以此准则对多负荷传感液压系统状态监测点进行优化设计。最后采用分步测试方式画出特种叉车液压系统故障诊断隔离树。     

轧机主传动系统机电振动特性分析及控制措施研究

建立恰当的轧机系统模型,对其动态特性进行正确完备的描述是进行轧机系统设计、控制、状态监测和故障诊断的关键.考虑间隙、摩擦等非线性因素的影响,建立了轧机主传动系统的机械模型,并进一步将控制系统、机械系统和轧制工艺条件等作为一个大系统来考虑,建立了复杂系统的机电耦合模型.用数值方法分析了电流调节器参数、轧制工艺条件、谐波扰动和间隙等因素对轧机系统振动特性的影响,并提出了相应的机电振动控制措施.研究结果表明,建立的机电耦合模型可以方便地分析轧机系统机电耦合动力学规律,为进一步控制轧机振动特性奠定基础.     

高速电主轴电动机—主轴系统的机电耦合动力学建模

针对高速电主轴系统具有复杂机电系统的特点,提出对高速电主轴系统进行机电耦合分析的观点。提炼并归纳了高速电主轴系统中存在的多物理过程、多参数耦合现象,给出高速电主轴系统全局耦合关系的框图。通过分析高速电主轴电动机—主轴子系统的结构及其耦合情况,得到了该子系统的机电耦合关系框图,并建立其物理模型。基于机电系统分析动力学理论,采用变分原理法,应用拉格朗日方程建立电动机—主轴子系统的电压方程和机械运动方程,将两组方程联立得到与该子系统物理模型相对应的数学模型,导出子系统的动力学方程,为进一步研究高速电主轴系统的机电耦合动力学性能提供理论基础。     

神经网络应用于多元变量时间序列的建模研究

自然界复杂系统的动态特性通常包含在多个变量时间序列的演化轨迹中。采用主成分分析与神经网络相结合的方法，进行多元变量时间序列的建模和预测研究。主要思路是首先通过主成分分析法找到一组相互独立的输入变量；再利用神经网络实现多个变量之间以及变量当前状态和未来状态之间的函数映射。多组实例仿真结果证明了该方法进行多元变量预测的可能性和有效性。     

飞行时间质谱仪射频四极杆驱动器的研制

针对自制垂直引入式飞行时间质谱仪（orthogonal extraction time-of-flight mass spectrometer, O-TOFMS）的需要,运用直接数字频率合成 (direct digital frequency synthesis,DDS)技术,研制了射频四极杆的高压射频驱动电路装置。该驱动器频率可调范围为0.5~2 MHz,幅度最高达到1 000 Vp-p。该射频四极杆驱动器（radio frequency quadrupole driver,RFQ Driver）可用于分子离子反应器（molecule ion reactor,MIR）和RFQ驱动,其结构简洁、成本低、性能稳定可靠。     

从光电容积图中提取脉搏率、呼吸率和心率的新方法

光电容积描记图(PPG)是一种利用光学技术无创检测人体心血管脉搏波的方法。PPG信号来源于MIMIC数据库,它含有许多生理信息。本文提出了将集合经验模态分解(EEMD)、倒谱、快速傅里叶变化和过零点检测相结合的方法,从PPG中可靠地估算脉搏率(PR)、心率(HR)和呼吸频率(RR)。首先,将PPG信号通过EEMD分解为有限个固有模态函数(IMF)。因为EEMD有自适应滤波特性,所以估算不同的生理参数时,可以用不同的IMF分量来重构信号。其次,估算脉搏率时,舍去低频含有伪迹的IMF,再通过过零点检测可以得到瞬时脉搏率。然后,估算心率时,用1 Hz~1.67 Hz(60次/分钟~100次/分钟)的IMF来重构信号,再求倒谱,选取反映心脏活动的频带来得到心率。最后,估算呼吸率时,用0.05 Hz~0.75 Hz(3次/分钟~45次/分钟)的IMF来重构信号,然后对呼吸信号求快速傅里叶变化得到频谱图,寻找频谱图中的峰值得到呼吸率。对来自MIMIC数据库的53个成人PPG信号进行了仿真。仿真结果表明使用该综合信号处理方法提取的生理参数与实际生理参数一致,且该方法有运算量小,精确度高的优点(误差不超过1.17%)。     

UPLC-MS/MS测定二苯甲烷二异氰酸酯

建立了二苯甲烷二异氰酸酯（MDI）的超高效液相色谱-串联质谱（UPLC-MS/MS）联用的分析方法。实验用甲醇作衍生试剂,将二苯甲烷二异氰酸酯衍生成二苯甲烷二氨基甲酸甲酯（MDC）,通过测定二苯甲烷二氨基甲酸甲酯来确定二苯甲烷二异氰酸酯的含量。实验采用Waters Acquity BEH C18超高效液相色谱柱,甲醇-0.1%甲酸作为梯度洗脱液,二苯甲烷二氨基甲酸甲酯在1.5 min内与其他化合物进行完全分离,经四极杆质谱选择离子监测模式检测。线性范围为2~100 μg/L,检出限为1 μg/L,相关系数0.999 4。考察了水、甲酸、甲酸铵流动相体系,以及进样量大小对样品的分离效果,发现甲酸流动相体系的分离效果优于其他两种流动相体系,同时发现在进样量大时出现平头峰。并且在优化条件下,对实际样品中游离的二苯甲烷二异氰酸酯进行了测定。     

Rapid one-of-a-kind production

To shorten the product development cycle time and reduce the cost at the same time, which is very critical for the survival of those small and mid-sized one-of-a-kind production (SMOKP) companies, various computer communication, simulation and computer aided engineering and management techniques have been widely used in these SMOKP companies. However, according to our study, the applications of these advanced computer technologies in these SMOKP companies are lack of system integration and synergy, which result in communication errors, reworks, duplications and hence a longer product development lead time and a higher cost. To solve this problem, an inter/intranet based computer aided rapid product development system is presented in this paper. This system consists of a number of inter/intranet based computer models or sub-systems for supporting rapid development of a one-of-a-kind product. It also employs a novel concurrent product development strategy called “prototype based incremental product development strategy” and an integrated product data structure called “product production structure”. Some industrial implementations of the proposed system, product development strategy and product data structure are also reported in the paper.     

Effect of the molecular weight on deformation states of the polystyrene film by AFM single scanning

Nanobundles patterns can be formed on the surface of most thermoplastic polymers when the atomic force microscope (AFM)‐based nanomechanical machining method is employed to scratch their surfaces. Such patterns are reviewed as three‐dimensional sine‐wave structures. In the present study, the single‐line scratch test is used firstly to study different removal states of the polystyrene (PS) polymer with different molecular weights (MWs). Effects of the scratching direction and the scratching velocity on deformation of the PS film and the state of the removed materials are also investigated. Single‐wear box test is then employed to study the possibility of forming bundle structures on PS films with different MWs. The experimental results show that the state between the tip and the sample plays a key role in the nano machining process. If the contact radius between the AFM tip and the polymer surface is larger than the chain end‐to‐end distance, it is designated as the “cutting” state that means the area of both side ridges is less than the area of the groove and materials are removed. If the contact radius is less than the chain end‐to‐end distance, it is designated as the “plowing” state that means the area of both side ridges is larger than the area of the groove and no materials are removed at all. For the perfect bundles formation on the PS film, the plowing state is ideal condition for the larger MW polymers because of the chains’ entanglement. SCANNING 35:308‐315, 2013. © 2012 Wiley Periodicals, Inc.     

汽车ESC系统DIL/HIL仿真平台设计

全面准确地标定与测试是开发车辆电子稳定控制(electronic stability control,ESC)系统的关键环节。车辆控制过程是典型的强非线性系统,建立精确的车辆模型比较困难,驾驶员模型也很难准确模拟紧急工况下驾驶员的真实反应。在仿真系统中将难以精确建模的液压制动系统、ESC压力调节单元、转向及电子节气门装置采用真实硬件,并在试验平台中嵌入真实驾驶员,基于Matlab/Simulink/dSPACE环境和车辆动力学软件veDYNA,开发硬件在环(hardware-in-the-loop,HIL)和驾驶员在环(driver-in-the-loop,DIL)的仿真试验平台,并在此平台上对所设计的ESC系统进行仿真试验研究。试验结果表明,所设计的DIL/HIL仿真平台可以大幅提高ESC系统的开发效率和测试准确性。     

Rapid one-of-a-kind production

To shorten the product development cycle time and reduce the cost at the same time, which is very critical for the survival of those small and mid-sized one-of-a-kind production (SMOKP) companies, various computer communication, simulation and computer aided engineering and management techniques have been widely used in these SMOKP companies. However, according to our study, the applications of these advanced computer technologies in these SMOKP companies are lack of system integration and synergy, which result in communication errors, reworks, duplications and hence a longer product development lead time and a higher cost. To solve this problem, an inter/intranet based computer aided rapid product development system is presented in this paper. This system consists of a number of inter/intranet based computer models or subsystems for supporting rapid development of a one-of-a-kind product. It also employs a novel concurrent product development strategy called “prototype based incremental product development strategy” and an integrated product data structure called “product production structure”. Some industrial implementations of the proposed system, product development strategy and product data structure are also reported in the paper.     

The efficacy of back propagation neural network with delta bar delta learning in predicting the wear of carbide inserts in face milling

Face milling is a process predominantly affected by dynamic variation of cutting forces, thermo-mechanical shocks and vibration leading to catastrophic tool failure along with gradual wear of the inserts. Keeping in view the industrial importance of this process, it is necessary to devise suitable methods to predict in advance the onset of tool failure without grossly impairing the machining set-up and the job. Hence, the applicability of back propagation neural network with delta bar delta learning rule for faster convergence has been studied with the above objective. The multi sensor based tool condition monitoring strategy shows that the learning rate adaptation scheme combined with the selection of suitable process parameters drastically reduces the training time of the artificial neural network without dispensing with the prediction accuracy.     

复合ICA-SVM机械状态模式分类

提出了一种新颖的、基于独立分量分析(ICA)的复合神经网络，用于不同机械状态模式的特征提取。利用支持向量机(SVM)进行最终分类。与通常的基于经验风险最小化(ERM)原理的神经网络方法相比，基于结构风险最小化(SRM)原理的支持向量机分类方法具有更好的推广能力。而借助多个独立分量分析网络，隐藏于多通道振动观测信号中的不变特征得到有效提取，从而实现了支持向量机分类器在分类能力和推广性两者间的合理平衡。     

Effect on crystalline structure of AISI M2 steel using tungsten–thorium electrode through MRR,EWR, and surface finish

To investigate on the crystalline structure of AISI M2 steel by using tungsten–thorium electrode in electrical discharge machining (EDM) process was studied. Furthermore, the investigation were carried out for finding the value of material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR) of tool steel material depending upon three variable input process parameters. On the basis of weight loss, the value of MRR and EWR were calculated at optimized process parameter. Subsequently, surface topography of the processed material were examined through different characterization techniques like scanning electron microscopy (SEM), Optical surface profiler (OSP) and Atomic force microscopy (AFM), respectively. In XRD study, broadening of the peak was observed which confirmed the change in material properties due to the homogeneous dispersion of the particles inside the matrix. Lowest surface roughness and MRR of 0.001208 mg/min was obtained. Minimum surface roughness was obtained 1.12 μm and 2.18427 nm by OSP and AFM study, respectively. Also, minimum EWR was found as 0.013986 mg/min.