基于振动信号EMD和ICA的刀具破损识别

针对多齿铣削过程中振动信号的特点,提出了一种基于经验模态分解(EMD)和独立分量分析(ICA)相结合的方法,对混叠在振动信号中的铣刀破损信号进行分离。对振动信号进行经验模态分解提取出信号中的所有本征模函数,然后应用fastICA对所提取出的本征模函数进行独立分量分析。利用该方法对铣削加速度振动数据进行了分析,试验表明,该方法可以提取出混合信号中与刀具破损状态相关的故障特征频率成分。     

以工作流驱动的PDM与ERP集成方法研究

为了保证从设计到生产整个过程的数据一致性,在分析了现有的产品数据管理与企业资源规划集成方法的基面上,提出了一类由产品数据管理中的工程变更单对象组织设计评审后的结果数据,通过工作流中的特定节点触发数据发布,经过中间件将数据传输到企业资源规划系统的集成方法.从集成方法的构思、体系架构、数据发布过程和集成方法建模等几个方面进行了系统研究,并通过一个应用实例说明了该方法的具体运用.     

土壤中铜铅测定中的电热板消解方法研究

该实验采用3种不同的消解方法对土壤标准物质和实际样品进行前处理,用电感耦合等离子体质谱仪(ICP-MS)测定其中铜(Cu)和铅(Pb)的含量。结果表明:(1)四酸加热消解法对土壤中Cu和Pb这两种金属元素的提取更充分;(2)王水加热消解法和硝酸-硫酸加热消解法对土壤中铜和铅的检测结果偏低,但所用酸种类和用量更少;(3)王水加热消解法和硝酸-硫酸加热消解法的能耗相对四酸加热消解法较小,当土壤中铅和铜的含量较高,3种前处理方法检测结果差别较小。     

A boundary element model for acoustic responses in the ear canal and its statistical validation and updating

A boundary element method (BEM) model for acoustic responses in individual ear canals was developed, and its validity was assessed and updated using a statistical approach. The BEM model was developed using high resolution computed tomography (CT) scanning from a healthy male adult. The BEM model, which was discretized adaptively for a frequency band of up to 22 kHz, included the head, pinna, ear canals, and tympanic membranes. The variability of the BEM model due to the uncertain acoustic boundary conditions and measurement locations was predicted using the eigenvector dimension reduction (EDR) method. Then, the likelihood function estimation approach was introduced in order to measure the agreement between the acoustic responses of the simulation model and experimental results. In order to enhance the simulation model performance, the acoustic boundary conditions of the BEM model were updated using a statistical calibration approach that maximizes the likelihood function value between the calculated probability density functions (PDFs) of the simulation model and the measurement data. The results of the validation and calibration procedures applied to the BEM model demonstrated that the proposed method provides a very effective method of verifying the model validity and enhancing the performance of the simulation model.     

面向产品全生命周期管理系统的增量式聚合开发实施方法研究

为提高产品全生命周期管理系统开发实施的客户满意度,提出了一种增量式聚合开发实施方法.首先建立过程模型,并进行了形式化描述,给出了该方法的核心--集成产品元模型,定义了信息组织的框架.面向增量式聚合的元模型体现了业务特性和软件系统特性,为实现其二维特性的统一,给出了相应的模型层次结构.最后,结合某企业具体系统的开发实施,初步验证了该方法的可行性.     

家用轿车全生命周期成本特征分析与成本估算

面向成本的设计(design for cost,DFC)是从设计的角度降低全生命周期成本(life cyc le cost,LCC)的设计方法。从DFC的角度,通过分析得到家用轿车的设计特征主要有外形尺寸、发动机功率、排量等参数,采用基于特征的神经网络方法通过实例计算表明在概念设计阶段就可以估算其LCC,为降低其LCC奠定了重要基础。Levenberg-M arquardt(LM)方法训练BP神经网络得到的LCC结果是最好的。     

采用互扫描法自动标定工作空间定位系统

针对工作空间定位系统(wMPS)现有标定技术效率低,标定程序复杂且须依赖外部测量设备等问题,本文在在研究wMPS测量原理的基础上提出了一种采用互扫描技术的自动标定方法。该方法结合该系统的扫描激光平面测量原理及使用特点,通过在基站上安装已知坐标的接收传感器,采用互扫描技术完成自动标定。文中以两台基站为基础,详细阐述了该方法的数学原理,并给出了基于几何约束的平差模型及其迭代解法。依托天津大学研发的wMPS实验平台对本方法进行了验证,并与基准尺标定法进行了比对。实验结果显示,采用本方法可以实现系统的自动标定,在距离基站5m内的测量空间内可获得0.6mm的坐标测量精度。该方法在保证系统测量精度的同时大大提高了系统的测量效率。     

HPLC-MS/MS同时测定大鼠血浆中烟碱、可替宁对映体及其药代动力学研究

建立了高效液相色谱-串联质谱法(HPLC-MS/MS)同时测定大鼠血浆中烟碱、可替宁对映异构体,并开展药代动力学研究.样品用甲醇进行蛋白沉淀,Chiralpak IG-3手性色谱柱(250 mm×4.6 mm×3μm)分离,流动相为0.2％ 甲酸铵-甲醇溶液,流速1.2 mL/min,内标法定量.结果表明,烟碱、可替宁...     

Non-linear multivariate and multiscale monitoring and signal denoising strategy using Kernel Principal Component Analysis combined with Ensemble Empirical Mode Decomposition method

The article presents a novel non-linear multivariate and multiscale statistical process monitoring and signal denoising method which combines the strengths of the Kernel Principal Component Analysis (KPCA) non-linear multivariate monitoring approach with the benefits of Ensemble Empirical Mode Decomposition (EEMD) to handle multiscale system dynamics. The proposed method which enables us to cope with complex even severe non-linear systems with a wide dynamic range was named the EEMD-based multiscale KPCA (EEMD-MSKPCA). The method is quite general in nature and could be used in different areas for various tasks even without any really deep understanding of the nature of the system under consideration. Its efficiency was first demonstrated by an illustrative example, after which the applicability for the task of bearing fault detection, diagnosis and signal denosing was tested on simulated as well as actual vibration and acoustic emission (AE) signals measured on purpose-built large-size low-speed bearing test stand. The positive results obtained indicate that the proposed EEMD-MSKPCA method provides a promising tool for tackling non-linear multiscale data which present a convolved picture of many events occupying different regions in the time-frequency plane.     

液相色谱-串联质谱法同时测定牛奶和奶粉中5种非蛋白含氮化合物

建立了液相色谱-串联质谱（LC-MS/MS）测定牛奶和奶粉中地昔尼尔、双氰胺、缩二脲、环丙氨嗪和三聚氰胺 5种非蛋白含氮化合物的方法。样品经乙腈沉淀蛋白并提取,正己烷脱脂,HLB固相萃取柱净化,LC-MS/MS法检测,同位素稀释内标法或外标法定量分析。结果表明：地昔尼尔、双氰胺、缩二脲、环丙氨嗪和三聚氰胺在牛奶样品中的定量限（S/N=10）分别为0.5、2.5、20、5、15 μg/kg,在奶粉样品中的定量限（S/N=10）分别为8、35、50、40、50 μg/kg;方法的线性关系良好,线性相关系数R²大于0.991;回收率为72.4%～102.8%,相对标准偏差（RSD）为1.3%～12.3%。采用该方法检测55批次牛奶和奶粉样品中5种化合物的残留情况,其中阳性样品的测定结果与国家标准方法的测定结果一致,验证了方法的可靠性。该方法简便、快捷,定量限可满足目前国内外最大残留限量的要求,可作为乳制品中相关化合物残留量的测定方法。