欠驱动单机械臂的运动学研究

本文以平面内转动关节连接的单机械臂为研究对象,针对其运动学以及单臂的控制原理进行研究.首先利用机器人数学基础,推导出单臂机器人的运动学递推方程,讨论了其正运动学变化矩阵以及求解雅克比矩阵.然后,以单臂3R欠驱动机械臂为研究对象,对其位置控制进行研究,提出了一种分阶段控制欠驱动机械臂的新方法.控制目的为实现操作臂末端点到达目标位置,由此实现了平面内3自由度欠驱动机械臂的位置控制.     

基于RBF神经网络的弧焊机器人轨迹跟踪控制方法

针对目前弧焊机器人的控制算法大多是基于关节空间的算法,而这种算法无法实现对机械臂末端位置的直接控制的问题,提出了基于笛卡尔空间的轨迹跟踪控制算法.首先运用RBF(radical basis function)神经网络技术对实际机械臂数学模型的建模误差和参数不确定性进行补偿,接着定义Lyapunov函数并运用HJI(Hamilton-Jacobi inequality)定理设计基于笛卡尔空间的机器人鲁棒控制器.在此基础上以二自由度机械臂为被控对象进行仿真研究,仿真结果表明,基于笛卡尔空间算法的轨迹跟踪控制算法误差小于基于关节空间的控制算法,在基于笛卡尔空间的控制算法的仿真中末端轨迹跟踪误差小于0.08 mm,神经网络能够有效地在线学习机器人的建模误差和参数不确定性.     

二杆机械臂运动参数的灰色控制系统

控制算法的好坏直接影响到机器人机械臂执行指令的效果.灰色预测控制因不需要被控对象精确的数学模型,且自适应能力强,超调适中,参数调整方便,具有更好的动、静态特性,较常规的PID控制有更多的优越性,适用于很多系统的自动控制.将灰色预测控制理论与PID控制理论有机地融合在一起形成了一套灰色预测控制系统并将其运用于二杆机械臂的控制中,通过MATLAB/Simulink环境仿真分析.     

基于粒子群优化算法的分数阶PID控制器设计

分数阶PID控制器具有可变的微分和积分阶次,通过调整控制器参数可以获得更好的控制性能。本文基于粒子群优化算法设计分数阶PID控制器。首先介绍分数阶PID和粒子群优化算法,然后给出分数阶PID控制系统结构、分数阶微积分算子的近似算法和分数阶PID控制器设计的仿真流程,最后通过MATLAB/Simulink对算例进行控制器设计仿真。仿真结果表明,通过粒子群寻优能够获得满意的分数阶PID控制器参数,满足对控制性能的要求。     

基于HPSO的PID算法在汽油机怠速控制中的应用

在怠速控制系统中,PID控制器的参数整定直接影响到控制效果;介于标准粒子群算法的不足,采用混合粒子群算法对PID控制器的参数进行离线整定,并基于MATLAB软件进行仿真实验;实验结果表明：混合粒子群的寻优精度优于遗传算法和标准粒子群算法,且具有良好的收敛速度.     

基于粒子群算法的逆变电路PID控制

针对逆变控制系统中PID控制器参数整定困难的问题,提出了基于粒子群算法的逆变电路PID控制器设计方法.通过推导逆变电路模型得到逆变电路传递函数,以该传递函数作为PID控制对象,利用粒子群算法搜索PID参数.MATLAB仿真结果证明了该方法的可行性和优越性.与采用遗传算法相比较,该粒子群算法能更快的获得合适的PID控制参数,所需迭代次数更少.     

基于多目标优化的救援机械臂结构参数设计

为了综合优化双臂救援机器人双臂协同工作空间、机械臂负载能力以及机械臂末端运动速度,研究了基于多目标函数综合优化的救援机器人双臂结构参数设计方法. 由于双机械臂的协同工作空间难以进行数学描述,提出了一种基于三重积分的描述方法. 针对所建立的双臂协同工作空间、机械臂末端运动速度以及机械臂负载能力三个目标函数的综合优化问题,通过模糊层次分析法,计算每个目标函数的权重从而进行线性加权以得到综合的多目标优化函数. 基于该综合优化函数,通过粒子群算法进行多目标函数最优值求解,得到一组机械臂结构优化参数,使双臂救援机器人的综合性能达到最优. 实验结果表明所提出的双臂救援机器人性能指标的优化方法是可行的.      

四旋翼飞行器PID优化控制

针对四旋翼飞行器具有非线性,强耦合性,多输入的欠驱动系统的特点,研制出既能精确控制飞行器姿态,又具有较强抗干扰和环境自适应能力的控制器。为了达到更好的飞行效果,采用了传统的PID控制算法,但实际应用中需要对PID参数进行优化,提出改进的PSO算法和遗传算法相结合的优化控制方法。为了优化PID参数,首先对飞行器进行动力性建模,再利用改进的PSO算法和遗传算法作PID参数优化。仿真和飞行实践的数据表明,相对于标准的PSO算法,飞行器有更好的鲁棒性和控制效果。     

基于改进粒子群优化算法的船舶航向控制

通过船舶响应型数学模型、舵机伺服系统、海浪干扰模型和PID控制器来设计船舶航向控制,并且将粒子群优化算法(PSO)加入到航向控制中,获得最优PID参数值。考虑到粒子群迭代次数和搜索过程中目标函数对PID参数值有一定的影响,主要研究改变迭代次数和目标函数来比较对应的PID参数,根据不同PID参数对应不同的控制效果,继而得出最优控制效果。结果表明:在迭代次数90时,能得到控制效果较好的PID控制参数,目标函数的改变对PID参数值的影响较大。     

粒子群优化BP神经网络PID控制注塑机液压系统

注塑机液压系统是一个时变、非线性和高耦合的复杂系统,传统PID控制参数不易整定,超调量大,对注塑机液压系统控制效果欠佳,现提出一种粒子群优化BP神经网络算法改良PID控制。BP神经网络算法存在收敛速度慢和容易陷入局部最小值的缺陷,利用粒子群算法的全局最优和收敛速度快的特性改良BP神经网络,然后利用粒子群优化BP神经网络对PID的3个参数进行在线调整。仿真结果表明,经过粒子群优化后的BP神经网络对PID3个参数的整定效果要比BP网络要好,同时粒子群优化BP神经网络PID控制效果明显优于传统PID控制,可以有效提高注塑机液压系统的精度和响应速度,优化注塑过程。     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.     

A computer generator for randomly layered structures

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