A Study on Comprehensive Modeling for Errors in on-line Measuring System of Machining Center

Based on the theory of multi-body system (MBS), bine’s and huston’s methods are applied to an on-line measuring system of machining center in this paper. Through the study on modeling technique, the comprehensive model for errors calculation in an on-line measuring System of machining center have been built for the first time. Using this model, the errors can be compensated by soft.ware and the measuring accuracy can be enhanced without any more inveSt. This model can be used in all kinds of machining center.

Modeling of Microstructure Evolution and Mechanical Properties of Steel Plates Produced by Thermo-Mechanical Control Process and Its On-line Application

An integrated metallurgical model was developed to predict microstructure evolution and mechanical properties of low-carbon steel plates produced by TMCP. The metallurgical phenomena occurring during TMCP and mechanical properties were predicted for different process parameters. In the later passes full recrystallization becomes difficult to occur and higher residual strain remains in austenite after rolling. For the reasonable temperature and cooling schedule, yield strength of 30 mm plain carbon steel plate can reach 310 MPa. The first on-line application of prediction and control of microstructure and properties (PCMP) in the medium plate production was achieved. The predictions of the system are in good agreement with measurements.

On-line Estimation in Fed-batch Fermentation Process Using State Space Model and Unscented Kalman Filter

On-line estimation of unmeasurable biological variables is important in fermentation processes,directly influencing the optimal control performance of the fermentation system as well as the quality and yield of the targeted product.In this study,a novel strategy for state estimation of fed-batch fermentation process is proposed.By combining a simple and reliable mechanistic dynamic model with the sample-based regressive measurement model,a state space model is developed.An improved algorithm,swarm energy conservation particle swarm optimization(SECPSO) ,is presented for the parameter identification in the mechanistic model,and the support vector machines(SVM) method is adopted to establish the nonlinear measurement model.The unscented Kalman filter(UKF) is designed for the state space model to reduce the disturbances of the noises in the fermentation process.The proposed on-line estimation method is demonstrated by the simulation experiments of a penicillin fed-batch fermentation process.

Neural network modeling for dynamic pulsed GTAW process with wire filler based on MATLAB

Double-sided weld pool shapes were determined by multiple welding parameters and wire feed parameters during pulsed GTAW with wire filler. Aiming at such a system with multiple inputs and outputs, an effective modeling method, consisting of the impulse signal design, model structure and parameter identification and verification, was developed based on MATLAB software. Then, dynamic neural network models, TDNNM (Topside dynamic neural network model) and BHDNNM (Backside width and topside height dynamic neural network model), were established to predict double-sided shape parameters of the weld pool. The characteristic relationship of the welding process was simulated and analyzed with the models.

On-Line Structural Breaks Estimation for Non-stationary Time Series Models

Non-stationary time series could be divided into piecewise stationary stochastic signal. However, the number and locations of breakpoints, as well as the approximation function of the respective segment signal are unknown. To solve this problem, a novel on-line structural breaks estimation algorithm based on piecewise autoregressive processes is proposed. In order to find the "best" combination of the number, lengths, and orders of the piecewise autoregressive (AR) processes, the Akaikes Information Criterion (AIC) and Yule-Walker equations are applied to estimate an AR model fit to the data. Numerical results demonstrate that the proposed estimation algorithm is suitable for different data series. Furthermore, the algorithm is used in a clinical study of electroencephalogram (EEG) with satisfactory results, and the ability to deal with real-time data is the most outstanding characteristic of on-line structural breaks estimation algorithm proposed.

Dynamic Fault Model for On-Line Evaluation of Yarn End Breakage during Ring Spinning

In this paper, a dynamic fault model is proposed to predict yarn end breakage in the spinning procedure through investigation of fault characteristics. In view of the principle that uniformity bad in raw material causes iustable yarn formation, the investigation focuses on the fault characteristic existing in the dynamic tension. Analyzing the dynamic spinning system, the phenomenon of over random shock in a spinning triangle is discovered to be the main physical event prior to yarn end breakage. The fault characteristic is further confirmed by dynamic tests and signal processing, and can be used to make an approach to predicting yarn end breakage. A relative energy feature is defined for evaluating the tendency of yarn end breakage, and its effectiveness is verified by on.line monitoring tests in the laboratory. The research results show that the proposed dynamic fault model has not only an advantage in indicating the presence of fault characteristics, but also great potentials in quantitating fault in online spinning monitoring.

填料性质对催化裂化油浆静电分离效率影响冷模试验研究

为分析静电分离法脱除催化裂化油浆中固含量影响因素,采用自制静电分离器试验装置,研究填料直径和材质对催化油浆中催化剂固体颗粒脱除效率影响规律。结合数值模拟,分析填料直径和材质对其接触点处电场强度变化的影响。结果表明,油浆中固体颗粒分离效率随填料直径增大而降低,氧化锆填料的分离效率最高,玻璃填料的分离效果最差。随填料直径和填料相对介电常数增大,填料接触点处的电场强度增大。在不同材质填料物化参数中,填料相对介电常数对油浆中固体颗粒静电分离影响过程起主要作用。

考虑含水率变化的路基压实填料介电特性试验研究

研究介电特性是路基电磁法无损检测技术的基础,为分析路基填料介电特性及其与含水率关系,采用TDR测试砂土、黏性土、改良土、盐渍土等6种典型填料在不同压实度、含水率状态下的介电常数。结果表明:压实填料的介电常数主要受含盐量、含水率、土质类型、压实度等影响;一般路基填料的介电常数主要受控于含水率,压实度在90.0%~96.0%变化时对填料的介电常数影响不显著;一般黏性土、砂性土、改良土的含水率-介电常数关系采用Alharathi模型拟合可满足工程应用精度要求;不同压实度下的Alharathi模型参数较为接近,a=0.100~0.140、b=-0.270~-0.140;掺灰改良土不同压实度的拟合参数差别较大,实际应用中应考虑掺灰比及压实度对介电常数-含水率关系模型的影响。

导热胶导热性能的研究进展与探讨

随着消费电子产品的迅速普及和技术的不断进步,导热胶市场需求不断增加,发展潜力巨大。但在小型化、集成化和便携性电子产品快速发展的同时,也对导热胶的导热性能提出了更高的要求。为此,本文介绍了填充型导热胶的导热机理,论述了传统导热模型的应用范围及有限元模拟预测导热系数的方法。综述了近年来导热胶胶体的研究成果,并着重论述了导热胶填料的种类、形状、粒径、改性及导热填料的混合使用对导热胶导热系数的影响规律,总结了提升导热胶导热系数的方法。

基于Hole-Filler模型的XML流数据剪切分片技术

对基于Hole-Filler模型的XML流数据剪切分片问题,首先利用XML文档的Document Object Model(DOM)结构,根据节点扇出度提出了基于DOM的XML流数据剪切分片策略及其算法.然后,在此基础上,对标签结构进行剪切以确定文档的剪切点,提出了基于标签的XML流数据剪切分片算法,有效地减少了节点扇出度与阈值的比较次数.最后,提出了优化的剪切策略,根据阈值与节点扇出度的比值对XML子树加以整合,以减少碎片的产生.实验结果表明,XML剪切算法在剪切时间、分片粒度等方面都有较好的性能.

基于Hole-Filler模型的XML数据流上的SLCA算法

与传统数据库对XML数据的处理不同,对XML数据流的处理不仅受实时性的约束,还受存储空间的限制.在XML片段无序传送的广播模型中,考虑在XML数据流上进行高效的关键字查询,进而首次提出近似SLCA算法.SLCA算法利用结构Hash表和LCA表对关键字进行匹配并计算SLCA,从而避免冗余操作.同时,SLCA算法可以对匹配结果立即输出而不必等到数据流传输结束.实验结果表明,基于Hole-Filler模型的XML数据流上的SLCA算法在节省时间和空间开销方面均表现出较好的性能.

考虑颗粒破碎的固化泥粒-砂土混合填料压缩特性研究

固化泥粒与砂土的混合填料为废弃工程泥浆的资源化处置提供了理想解决方案,而填方工程的压缩特性与混合填料的强度特性及颗粒破碎特征密切相关。该文通过开展不同颗粒级配的混合填料大尺寸压缩试验,建立考虑颗粒破碎的固化泥粒‒砂土混合填料的侧限压缩试验离散元(DEM)模型,探究了压实过程中混合填料压缩模量变化和固化土颗粒破碎量,重点分析了固化泥粒掺入比与初始孔隙比等因素对混合填料的压缩特性和应力‒应变关系的影响规律,并论证了混合填料用于填方工程的可行性。结果显示:密实条件下固化泥粒‒砂土混合填料的压缩性与泥粒掺入比呈正相关,而与泥粒强度呈负相关,并且一定固化泥粒的掺入可有效降低松砂在低应力水平下的压缩性,而高应力水平下受泥粒破碎的影响导致混合填料压缩性稍有提升;混合填料在压缩过程中,其颗粒破碎度随泥粒掺入比和砂土初始孔隙比的增加而提高,且在压缩终态破碎率均趋近于80%。

Permanent deformation and prediction model of construction and demolition waste under repeated loading

This study aims to reveal the macroscopic permanent deformation(PD)behavior and the internal structural evolution of construction and demolition waste(CDW)under loading.Firstly,the initial matric suction of CDW was measured by the filter paper method.Secondly,the PD of CDW with different humidity and stress states was investigated by repeated load triaxial tests,and a comprehensive prediction model was established.Finally,the discrete element method was performed to analyze the internal structural evolution of CDW during deformation.These results showed that the VAN-GENUCHTEN model could describe the soil-water characteristic curve of CDW well.The PD increases with the increase of the deviator stress and the number of cyclic loading,but the opposite trend was observed when the initial matric suction and confining pressure increased.The proposed model in this study provides a satisfactory prediction of PD.The discrete element method could accurately simulate the macroscopic PD of CDW,and the shear force,interlock force and sliding content increase with the increase of deviator stress during the deformation.The research could provide useful reference for the deformation stability analysis of CDW under cyclic loading.

Online model identification of lithium-ion battery for electric vehicles

In order to characterize the voltage behavior of a lithium-ion battery for on-board electric vehicle battery management and control applications,a battery model with a moderate complexity was established.The battery open circuit voltage (OCV) as a function of state of charge (SOC) was depicted by the Nernst equation.An equivalent circuit network was adopted to describe the polarization effect of the lithium-ion battery.A linear identifiable formulation of the battery model was derived by discretizing the frequent-domain description of the battery model.The recursive least square algorithm with forgetting was applied to implement the on-line parameter calibration.The validation results show that the on-line calibrated model can accurately predict the dynamic voltage behavior of the lithium-ion battery.The maximum and mean relative errors are 1.666% and 0.01%,respectively,in a hybrid pulse test,while 1.933% and 0.062%,respectively,in a transient power test.The on-line parameter calibration method thereby can ensure that the model possesses an acceptable robustness to varied battery loading profiles.

Mathematical Model of Dynamic Operation and Optimum Control of Billet Reheating Furnace

This paper provides a mathematical model for the billet reheating process in furnace.A new optimum method is brought up that the objective function is the integral value of enthalpy increasing process of a billet.Different delays are simulated and calculated,some proper delay strategies are ob- tained.The on-line computer control model is de- veloped.The real production conditions simulated, the temperature deviation of drop out billet from the target temperature is kept within±15℃.

红层泥岩填料物化特性试验与归一化模型

红层泥岩填料易软化崩解、强度低、蠕变特性显著且具有膨胀性,诱发了大量工程地质灾害,准确掌握红层泥岩物化特性及力学行为对揭示灾害诱因至关重要.以兰州红层泥岩填料为研究对象,采用室内土工试验、扫描电镜、X射线分析及三轴剪切试验,先测试红层泥岩填料的物理力学指标,再分析红层泥岩矿物成分及微观结构机理,最后基于Duncan-Chang模型探究符合红层泥岩填料最佳归一化因子并验证归一化模型.结论表明:兰州红层泥岩填料为肉眼可分辨的红色沉积岩,属于CL,有明显的压缩回弹特性,矿物成分含有大量的亲水性物质,微观结构为层状和层-链状的面-面接触或点-面接触结构.红层泥岩应力-应变曲线呈三阶段发展,随着围压增加应力-应变曲线由应变稳定型过渡为应变硬化型,当归一化因子选用(σ1-σ3)ult时,Duncan-Chang模型预测结果与试验结果吻合度较好,归一化效果最佳.

基于橡胶沥青粘弹试验测定模型参数优化研究

为了准确分析水泥混凝土路面接缝填缝料的受力状态,基于粘弹试验测定了橡胶沥青填缝料的松弛蠕变曲线与松弛模量曲线,通过非线性拟合方法求得有限元软件ANSYS中用于描述粘弹类材料粘弹性质的广义Maxwell模型和Prony级数的两种表达方式所需的参数。并结合粘弹性材料时温等效性质,回归了主曲线函数力学参数,为建立接缝有限元动态分析模型,研究移动荷载与温度荷载作用下此类型水泥路面接缝填缝料的粘弹性力学响应分析提供了方法和基础。

梯形轨枕空吊对轨道结构力学特性的影响及其整治技术研究

为研究垫板空吊对梯形轨枕服役性能的影响,建立考虑细观混凝土损伤的梯形轨枕轨道结构塑性损伤分析模型,结合现场实测数据计算分析不同轨枕空吊状态下轨道结构的变形与损伤规律。在此基础上,通过分析填充材料不同性能对该病害修复效果的影响及现场试验结果,得到材料的性能指标,并开展填充材料和病害整治技术的研究。研究结果表明:当梯形轨枕中间3块垫板出现大面积空吊时应予以重点关注,此时轨枕在列车荷载下将发生明显的变形,与正常工况相比,位移最大值将增加约60%,轨枕底部易出现受拉损伤并产生裂纹。对于空吊的修复,建议填充材料的弹性模量应不低于5.0 GPa。通过调整填充材料中填料和交联剂的用量可以在满足弹性模量要求的同时,保证粘接强度和黏度分别不低于5.0 MPa和500 mPa·s。采用研发的填充材料进行空吊修复后,轨枕变形明显减小,其结果与理论分析结果基本一致。

Model predictive control with an on-line identification model of a supply chain unit

A model predictive controller was designed in this study for a single supply chain unit.A demand model was described using an autoregressive integrated moving average(ARIMA) model,one that is identified on-line to forecast the future demand.Feedback was used to modify the demand prediction,and profit was chosen as the control objective.To imitate reality,the purchase price was assumed to be a piecewise linear form,whereby the control objective became a nonlinear problem.In addition,a genetic algorithm was introduced to solve the problem.Constraints were put on the predictive inventory to control the inventory fluctuation,that is,the bullwhip effect was controllable.The model predictive control(MPC) method was compared with the order-up-to-level(OUL) method in simulations.The results revealed that using the MPC method can result in more profit and make the bullwhip effect controllable.

Force-reflecting teleoperation of robots based on on-line correction of a virtual model

Virtual reality is an effective method to eliminate the influence of time delay.However,it depends on the precision of the virtual model.In this paper,we introduce a method that corrects the virtual model on-line to establish a more precise model.The geometric errors of the virtual model were corrected on-line by overlapping the graphics over the images and also by syncretizing the position and force information from the remote.Then the sliding average least squares(SALS)method was adopted to determine the mass,damp,and stiffness of the remote environment and use this information to amend the dynamic model of the environment.Experimental results demonstrate that the on-line correction method we proposed can effectively reduce the impact caused by time delay,and improve the operational performance of the teleoperation system.