并联机器人的一种鲁棒最优控制结构

为消除负载变化及耦合干扰对系统响应特性的影响，对并联机器人控制系统提出一种鲁棒最优控制器，理论分析和实验结果表明，采用该鲁棒最优控制器并结合力补偿器，可明显改善机器人的操作精度。     

基于LMI的4WS-4WD车辆H_∞鲁棒控制器设计

基于线性矩阵不等式(LMI)设计了H_∞鲁棒最优控制器以及H_∞鲁棒非脆弱控制器.通过两自由度(2-DOF)车辆模型推导并建立H_∞鲁棒控制系统,此外,定义系统摄动并对摄动矩阵进行分解,进而利用线性矩阵不等式求解控制器.仿真结果表明,H_∞鲁棒最优控制器对侧偏角及横摆角速度的控制效果显著优于LQR控制器.同时,在控制器存在摄动及对侧偏角及横摆角速度进行控制的情况下,H_∞鲁棒非脆弱控制器的鲁棒性能显著优于普通鲁棒H_∞控制器.因此,H_∞鲁棒最优控制器解决了普通鲁棒H_∞控制器控制性能差的问题,H_∞鲁棒非脆弱控制器则解决了普通H_∞鲁棒控制器对参数变化敏感的问题.     

全局稳定的机器人鲁棒自适应分散跟踪控制

提出一种全局稳定的鲁棒自适应分散控制策略,用于不确定性机器人的轨迹跟踪．该控制器由一个线性ＰＤ 分散反馈＋ 补偿不确定动力学的非线性自适应分散反馈构成．仅需要了解各关节输出的位置及速度状态,就能够克服通常难于建模的摩擦力和外部扰动影响,保证全局的渐近稳定．二自由度机器人的仿真证明了该法的有效性．     

基于输入有界机器人鲁棒自适应控制策略研究

本文针对常规机器人的鲁棒控制器设计的保守性和实际中执行机构输出的有界性产生矛盾，设计出一种新型输入有界的机器人鲁棒自适应控制器，解决了力矩受限情况下机器人控制器的设计问题，为机器人向小型化、节能型等特殊要求领域发展，提供了一条新的途径。     

外骨骼机器人手指鲁棒跟踪控制

基于外骨骼机器人手指系统动力学,提出了机器人鲁棒μ控制器的设计方法。分析了系统模型的不确定性,将负载动力学作为系统的反馈不确定,建立了合理的被控对象标称模型。基于高速DSP实现鲁棒控制器的数字化,在μ控制器设计和数字实现过程中考虑了机器人系统的计算延时。通过实验评估采样延时对机器人控制器鲁棒性能的影响。实验结果表明,μ控制器能够抑制干扰和模型不确定对机器人系统的影响,系统具有很好的鲁棒稳定性和鲁棒性能。     

机器人的鲁棒自适应轨迹跟踪控制

针对存在参数不确定和外界扰动的机器人系统,提出了一种基于模糊控制的鲁棒自适应跟踪控制器设计方法.该方法基于Lyapunov稳定性理论,整个闭环系统渐近稳定.通过二自由度机械臂系统的计算机仿真结果验证了该方法的有效性,可用于不确定性机器人系统轨迹跟踪鲁棒控制.     

一种前馈补偿和模糊滑模相结合的柔性机械臂控制

针对柔性关节机器人控制系统中存在的扰动力、摩擦力、参数变化以及建模误差等问题,将扰动力分为确定性扰动和不确定性扰动、摩擦力分为线性和非线性部分,并在此基础上提出了一种前馈补偿和模糊滑模相结合的鲁棒控制器.机器人自身结构的相关量、确定性扰动以及摩擦力的线性部分,可以通过控制器的计算力矩和前馈补偿部分进行有效控制,并通过模糊滑模控制器来克服外界的不确定性扰动、摩擦力的非线性部分、参数变化以及建模误差等.在HIT四自由度柔性机械臂上进行了控制器的相关实验,实验结果表明,该控制器具有良好的位置跟踪性能和较强的抗干扰能力.     

基于时延估计和鲁棒H_∞控制的工业机器人跟踪控制

针对六自由度工业机器人系统,结合时延估计控制和鲁棒H∞控制的优点,提出了一种鲁棒H∞时延估计跟踪控制算法.该算法不需要机器人的复杂动力学模型,避免了机器人逆动力学的在线实时计算;采用时延估计在线获得机器人系统的未知动力学和外界干扰,并对控制过程加以补偿;通过引入L2增益控制,可实现对时延估计误差的L2干扰抑制,从而进一步提高了系统的鲁棒性.同时,利用Lyapunov函数和Riccati不等式保证了闭环系统的渐近稳定性和H∞鲁棒性能.该算法计算简单,结构固定,鲁棒性强,易于实现.文中还通过二自由度机器人的仿真实验证明了该算法是有效的.     

广义离散不确定线性系统状态反馈鲁棒H∞控制器设计

研究一类具有范数有界参数不确定性广义离散线性系统的鲁棒H∞控制问题．基于矩阵不等式，导出状态反馈鲁棒H∞控制器存在的一个充分条件，并利用矩阵不等式的解给出鲁棒H∞控制器的一种设计方法．     

具有清晰暂态性能的机器人鲁棒自适应跟踪控制

基于不确定性机器人的轨迹跟踪问题 ,提出一种保证系统具有清晰暂态性能的鲁棒自适应控制策略 .控制器由一个简单的线性 PD反馈 非线性阻尼 标量不确定性补偿控制器构成 ,不需传统的回归矩阵计算 ,能够有效地克服通常难于建模的摩擦力和外部扰动影响 .只需了解系统的阶数和输出的位置及速度状态 ,保证全局的指数稳定或全局一致最后有界 .二自由度机器人的仿真证明了该法的有效性     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

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.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

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。     

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.     

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

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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     

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