音圈电机驱动的柔性定位平台设计与控制

设计了一种二自由度柔性微定位平台,该平台主要由音圈电机和柔性铰链机构等组成.采用直角柔性铰链组成的双平行四杆机构对称安置,以实现平台的大行程和运动解耦,工作行程可达2,mm以上,定位精度可达纳米级.设计空间支撑机构保证其承载能力.对微定位平台进行了结构设计和承载能力等特性分析.考虑到该定位平台动态行为的特点,采用遗传算法优化的BP神经网络组合辨识方法对系统模型进行了辨识,克服了神经网络对复杂系统动态行为辨识存在的缺陷.基于神经网络PID复合逆控制方法对微定位平台进行控制,通过实验对辨识和控制方法进行了验证,结果表明遗传算法优化的神经网络辨识方法与神经网络PID复合逆控制方法适用于该音圈电机驱动的柔性微定位平台系统的实际应用.     

基于BP神经网络的静液压变速器控制研究

静液压变速器(HST)的操控性是农用车辆性能提升的关键,采用一种基于BP(back propagation)神经网络的新型控制策略,对HST马达输出转速的动态特性进行研究.基于变量泵—定量马达静液压传动系统的数学模型,首先对比研究了传统PID控制、模糊控制以及BP神经网络控制3种方法的控制效果,结果表明:与传统PID控制和模糊控制相比,BP神经网络控制能有效抑制系统超调量并降低马达转速波动,减小系统达到稳态的调节时间,具有良好的鲁棒性.基于此,提出采用BP神经网络控制方法对具有更大马达转速变化范围的变量泵—变量马达传动系统进行调查,研究结果表明,在对变量泵、变量马达分段控制中,该方法能实现较稳定的切换效果;在不同的负载等效转动惯量下,马达转速均能达到稳定状态,且由负载引起的转速波动也得到降低.研究结果表明,BP神经网络控制方法对变量泵—变量马达传动系统具有潜在的控制优势.     

基于BP神经网络的船舶航向智能PID控制研究

针对船舶航向控制非线性的特性,以船舶航向运动一阶KT模型为研究对象,设计了基于BP神经网络的自整定PID算法航向控制器。将传统PID与BP神经网络结合,对被控对象由BP神经网络进行辨识,给出PID控制参数,由PID控制算法进行控制并优化收敛速度。根据真实渡轮船舶特征参数,利用MATLAB/Simulink仿真软件建立船舶航向运动控制系统模型。仿真结果表明,基于BP神经网络的PID控制系统超调小、鲁棒性好,可长时间稳定工作,几乎无稳态误差,控制算法的实用性以及动态控制系统的优越性得到验证。     

基于BP神经网络PID的交叉耦合轮廓控制研究

文章以基于直线电机的数控机床X-Y平台为实验平台,进行轮廓误差控制技术的研究,设计了BP神经网络交叉耦合控制(back propagation neural network cross-coupling control,BPNN-CCC)器。在交叉耦合控制(cross-coupling control,CCC)的基础上,分析了BP神经网络的理论,并与PID控制相结合,设计了BP神经网络PID控制器,将其应用在单轴控制与CCC上,在Matlab中搭建了BPNN-CCC的仿真模型。实验结果表明,该控制器有效减小了系统的轮廓误差,并体现了自学习、自适应的能力。     

挖掘机器人负载工况下的力与位姿控制

文章分析了智能挖掘技术的研究现状,给出了试验挖掘机器人运动学模型及负载工况下动态特性方程;为实现典型挖掘工况下工作装置位姿及液压驱动力的控制,设计了一种基于BP(back propagation)神经网络PID(proportion-integral-derivative)控制算法的控制器;并以山河智能SWE-17E挖掘机器人为平台进行试验验证。试验结果表明,采用BP神经网络PID控制算法得到的工作装置末端轨迹跟踪误差均方差小于10cm,驱动力跟踪也达到了较高精度,证明了BP神经网络PID控制算法对于挖掘机器人力与位姿控制的可行性和有效性。     

双容水箱的神经PID控制

利用神经网络自学习的特性,结合常规PID(比例-积分-微分)控制理论,提出基于BP(back propaga-tion)神经网络进行PID参数整定的控制策略.该方案能实现控制器参数的自动调整,以及在线调节参数Kp,Ki,Kd,适应被控过程的时变性,提高控制的性能和可靠性.仿真结果表明:相对于传统的PID控制方法,神经网络PID控制系统取得更满意的控制效果.     

基于BP神经网络的球杆控制算法设计

针对球杆系统定位控制问题,基于BP神经网络设计了BP神经网络控制器和BP神经网络PID参数自整定两种智能控制器.完成了两种控制器的网络结构与实现方法,并在Simulink环境中仿真.仿真结果显示出BP神经网络PID参数自整定控制器的稳定性优于BP神经网络控制器,将BP神经网络PID参数自整定控制器算法移植到GBB1004球杆系统,实现了对该系统的控制.实验结果显示,该控制器响应快,有一定的抗干扰能力,获得系统调节时间小于16s,稳态误差小于1cm.     

基于附加惯性项BP神经网络的四旋翼无人机姿态控制研究

针对传统PID控制不能实时更新整定的K_p、K_i、K_d参数,以及控制精度不高等缺点,在结合四旋翼无人机自身特性的基础上,本文提出一种附加惯性项的BP神经网络与PID控制结合的姿态控制方法,并对惯性系数进行修改,来实现无人机在受干扰情况下飞行过程的姿态控制。仿真实验分析表明:与BP神经网络参数自整定PID控制和传统PID控制相比,该控制方法提高了系统的抗扰性、鲁棒性和动态性能,从而对于提高无人机的姿态控制具有较好的实际参考价值。     

光栅刻划机超精密定位系统定位控制研究

对光栅刻划机超精密定位系统的定位控制以及实验进行探索研究.鉴于控制模型和实验分析验证出光栅刻划机超精密定位系统具有较强的非线性和时变性,提出将基于BP神经网络的PID控制方法用于光栅刻划机定位系统控制,利用神经网络的自学习实时调节PID控制参数,实现精密定位的自适应控制.通过控制实验,稳定地获得了5nm以内的定位精度.     

永磁同步电机的神经网络模型参考自适应控制研究

本文介绍了一种基于BP神经网络的正弦波永磁同步电机(PMSM)智能控制方法。同传统的PID控制相比较,基于神经网络的智能控制具有自学习、适应环境变化等优点。将BP神经网络模型参考自适应控制应用于PMSM,其仿真结果表明这种智能控制具有很强的鲁棒性、良好的动态和稳态特性。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

正~~     

An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.