单自由度冲压机构优化设计及其运动仿真

在冲压机构上定义坐标系,对冲压机构的运动学进行分析,推导出冲压机构滑块的位移、速度及加速度公式.导槽轮廓设计选择n阶贝塞尔曲线,采取优化方法得出冲压机构连杆及驱动杆的最佳尺寸.结合具体实例,在三维建模软件SolidWorks中构建冲压机构实体模型.采用ADAMS软件对其进行运动仿真,得到滑块的运动特性曲线.同时,与传统冲压机构的仿真结果进行对比分析.仿真结果显示:单自由度冲压机构滑块速度和加速度(每个周期滑块大约位于0.3~0.7 s的位置处)比传统冲压机构平稳,能够很好地满足深冲压模具的要求.     

RPR-RPP六杆机构的动力学仿真

为了研究RPR-RPP六杆机构的工作过程,便于RPR-RPP六杆机构的设计、改进和使用,在ADAMS中建立了RPR-RPP六杆机构的三维工作模型,对ADAMS中模型的各部分进行了设置,对RPR-RPP六杆机构工作过程进行了仿真分析,对RPR-RPP六杆机构结构参数进行了优化研究。     

插齿机主传动机构的运动学仿真与优化设计

应用虚拟样机技术和机械系统动力学仿真分析软件ADAMS建立了两种插齿机（瓦特型六杆机构）主传动机构的模型，对两者进行了运动学仿真，以插齿刀在工作区间速度平稳性为目标，分别对两个模型进行了优化设计，阐明了ADAMS对插齿机主传动机构进行运动学仿真及优化的优点，并分析和比较了两种模型的性能特点．     

应用杆组法和CAD技术实现刨床六杆机构的运动分析和仿真

以牛头刨床平面六杆机构为例,运用杆组法建立其数学模型,结合参数化设计方法和CAD二次开发技术,对机构进行了运动分析和仿真。用此方法可快速、准确地计算出连杆上各位置点的运动参数,并直观地演示机构的三维动画,提高了机构设计的效率。此方法还可用于同类机构的设计。     

基于四杆机构对仿生蜻蜓扑翼飞行器的设计优化与仿真

本文基于四连杆机构提出了一种齿轮连杆运动机构设计方案,用于模仿蜻蜓翅翼的运动,并研究了扑翼机构各参数变化对机构运动轨迹的影响,归纳总结出一些规律,从而为选择出合适的机构参数提供了依据。采用基于优化的机构设计方法对仿生微扑翼机构进行优化设计,确定出各杆件参数和运动参数。然后利用CATIA来对扑翼机构进行运动仿真分析,模拟机构的运动过程,仿真结果与设计要求基本吻合,验证了机构的可行性。     

基于Simulink的连杆压力机机构运动仿真分析

以连杆压力机机构为研究对象，对其运动学参数建立数学模型，并利用MATLAB／Simulink强大的计算功能进行仿真，得出了压力机冲头滑块的位置、速度、加速度变化曲线，为连杆压力机的设计提供参考和依据．     

一种研究球面机构运动学的新方法——Ⅱ球面六杆机构的运动学研究

本文继续研究多种球面六杆机构的运动学问题,导出了几种球面六杆机构以输入转角为参数的连杆曲线方程,得到了连杆点位置及连杆方向的显性表达式,将这些表达式用于球面六杆再现轨迹和刚体导引机构的运动分析与优化综合,优点显著。     

机械设计基础课设中压力机运动分析及设计

为培养学生的设计分析能力,在课程设计中对六杆肘杆式压力机机构的运动分析和优化设计进行研究。为提升六杆肘杆式压力机机构在工作段内运动的稳定性,选择滑块运动至下死点位置时的状态为初始状态,首先用复数矢量法对机构进行运动学建模,推导出滑块的运动学方程;其次建立压力机机构的优化模型,以杆件长度为设计变量,确定优化目标和约束条件,并运用MATLAB遗传算法对压力机机构进行求解。优化设计后,机构的运动学性能得到了明显的改善,使冲压产品的质量得到提高。     

消防多功能抢险车油缸连杆机构的优化

针对某消防多功能抢险车油缸连杆变幅机构变形失效问题，采用Creo、Adams与Ansys软件建立油缸连杆机构和履带车力学模型，仿真分析履带车运动过程中连杆各铰点受力情况。结果表明:连杆变形失效的主要原因是其多处位置强度超过材料许用应力。以最大力为边界条件，利用有限元方法对抢险车油缸连杆进行强度分析，并以油缸连杆铰点最大受力值为优化目标，采用灵敏度分析、优化设计的方法对油缸连杆各铰点进行优化。仿真结果表明:优化后连杆各铰点受力峰值降低50%，最大应力值为20814 MPa，比优化前降低513%，小于材料的许用应力，产品未发生变形失效，优化方案有效。     

基于有限元法与田口法的V形件冲压仿真参数稳健设计

提出了一种有效的冲压仿真参数稳健设计方法，该方法将有限元分析方法和田口法有效结合．以V形件冲压过程为对象，首先分析各建模参数对稳健性仿真实验设计的影响，并就各因子的水平选择进行了研究，寻求有利于提高稳健性的建模参数组合．利用有限元软件ABAQUS建立了V形冲压件的有限元仿真模型，得到仿真实验设计结果．运用田口分析方法，进行了V形件冲压加工建模参数的稳健性设计分析，给出了实物试验结果，对仿真实验结果进行了验证分析．本研究为有效进行稳健设计提供了一种简单、实用的方法．     

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…     

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.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.