典型光学加工中边缘效应仿真分析

为分析光学加工中边缘效应对元件最终面形精度的影响,建立了数控小磨头行星式抛光去除函数模型和射流式工具加工的去除函数模型.通过对抛光过程中磨料载体的微观状态的研究,探讨并仿真了两种抛光方式在不同区域抛光速度分布、抛光压力分布和抛光中Preston系数的变化.通过对比分析这些参数的变化对材料去除影响,表明光学加工过程中磨料载体中分子间的作用力对边缘效应产生的影响不可忽略.     

连续进动气囊抛光材料去除特性研究

为提高和调控模具自由曲面的加工效率与质量,提出了机器人辅助连续进动气囊抛光方法;运用运动学原理,推导了行切法加工方式下的切向速度数学模型;基于Preston方程,建立了连续进动气囊抛光材料去除模型;通过MATLAB仿真技术,分析了其它工艺参数一定的条件下,进给速度和叠加次数对气囊抛光切削方向分布和材料去除特性的影响;以材料快速均匀去除为目标,获得了优化进给速度v=0.7mm/s和叠加次数n=3.最后,通过机器人辅助气囊抛光系统,进行了试验对比验证,与仿真结果吻合,证实了连续进动气囊抛光方法应用于模具自由曲面抛光的有效性.     

气囊抛光曲面光学零件工艺参数对抛光区特征影响的研究

首先介绍了气囊抛光的原理,然后在自行研制的气囊抛光实验样机上,对曲面光学零件进行了抛光实验,研究了进动角、气囊压缩量、气囊内部压力、气囊转速以及工件的曲率半径几个重要的工艺参数对球面光学玻璃抛光区影响情况,总结了各工艺参数对抛光区的影响规律,给出了曲面光学零件工艺参数合理的抛光区取值范围.     

多丸片固着磨料研磨高精密光学元件的参数优化

为了增强固结磨料研磨去除的可控性和确定性,提高光学元件的研磨加工精度和效率,以高精度光学元件为研究对象,分析了行星转动加工方式的多丸片固结磨料研磨的去除特性及参数优化。首先基于Preston方程分析了在研磨接触区域的相对速度、接触时间,并在利用ANSYS求得应力分布规律的基础上建立了多丸片固结磨料研磨的材料去除函数模型;引入趋近因子概念,通过对比去除函数归一化图形,对6种抛光盘模型的运动偏心比和速度比参数进行了优化,获得了多丸片固结磨料抛光盘的最大去除深度和去除量。     

环形抛光盘几何参数对去除函数的影响

为获得与理想去除函数更为接近的去除函数,采用中心开孔的环形抛光盘作为抛光工具,推导环形抛光盘在行星运动方式下的去除函数模型,探究环形抛光盘偏心率m及中心孔径r1对去除函数形状及误差修正能力的影响。研究表明:当0<06时,去除函数的中心区域出现较大程度的“凹陷”,不具备理想去除函数特性;中心开孔孔径r1主要影响去除函数的峰值区域大小及边缘去除量,随着r1增大,去除函数中心峰值区域越窄,边缘去除量减小,去除函数呈现出“脉冲特性”,有利于中频误差的修正;与应用较为广泛的圆形抛光盘去除函数相比,在相同偏心率m下,环形抛光盘的中频误差控制能力优于圆形抛光盘。>     

换能器阵列型超声抛光机理及声场仿真和实验研究

为了提高工件表面抛光质量和抛光效率,对传统非接触式超声振动抛光进行了改进,将单个换能器换成换能器阵列,同时加入料筐的旋转运动,设计了实验样机。分析了超声抛光的材料去除机理,推导出单颗磨粒去除材料体积和磨粒振动速度的表达式。利用COMSOL对样机抛光槽内液体进行声场仿真,研究了换能器个数、换能器布置间距、换能器输入电压对抛光液声场分布的影响,优化了抛光槽底部换能器的布置方式,仿真结果显示,换能器个数为4个、布置间距为55mm时,抛光槽中心区域声压分布更加均匀。实验探究了样机料筐转速、抛光时间、换能器输入电压对工件表面抛光质量的影响规律,确定了工件表面抛光效果最佳时的工艺参数组合,结果表明:料筐转速为50r/min、抛光时间为80min、换能器输入电压为150V时,抛光效果最好,此时工件表面粗糙度减小量为0.019μm,表面粗糙度变化率为33.33%。     

电极形状对介电泳抛光影响的仿真研究

为了解决平面抛光加工中提高精度和效率的难题,根据中性微粒在非均匀电场中可以产生介电泳效应,提出了一种可以提高抛光均匀性和效率的介电泳抛光方法.讨论了介电泳理论及抛光原理,运用COMSOL软件仿真分析了不同电极的电场线分布.仿真结果表明:圆环70~90mm电极形状的电场线分布最不均匀.进行了相应电极的加工试验,试验结果表明:使用圆环70~90mm电极时材料去除率最大,达到0.573mg/min,相比传统CMP提升了19.9%.使用圆Φ60mm电极形状,工件材料去除最均匀、抛光效率最高,2.5h可以将Φ76.2mm硅片全部抛亮,比传统CMP提高了3.6倍,且最终表面粗糙度为0.97nm.在实际加工中,圆Φ60mm电极形状最适合Φ76.2mm硅片的介电泳抛光.     

硬质合金麻花钻的剪切增稠抛光试验研究

针对硬质合金钻削刀具曲面加工效率低的问题,提出了用剪切增稠抛光（Shear Thickening Polishing, STP）方法实现硬质合金钻削刀具的复杂双螺旋曲面的低成本、高效率整体高质量抛光加工. 配制具备剪切增稠特性的非牛顿抛光流体,使用MCR302旋转流变仪测试其流变特性. 基于剪切增稠抛光液的流变特性,对硬质合金麻花钻的刃背、刃带和螺旋槽曲面进行整体抛光. 采用控制变量法分析抛光槽转速和工件转速对硬质合金麻花钻表面粗糙度与材料去除率的影响规律. 试验结果表明,加工后的麻花钻整体表面粗糙度随抛光槽转速的增大先减小再增大,在抛光槽转速为90 r/min时,加工效果最好. 随着工件转速的增加,其整体表面粗糙度先减小后基本不变或略有增加,在工件转速为3 500 r/min时,加工效果最好. 麻花钻材料去除率与抛光槽转速及工件转速呈正相关. 在较优加工参数抛光槽转速90 r/min、工件转速3 500 r/min下,麻花钻经STP 60 min后,其刃背、刃带和螺旋槽表面粗糙度分别从原始的310 nm、450 nm、270 nm降低至10 nm、243 nm、15 nm,刃背和螺旋槽磨削痕迹几乎消失,螺旋槽刃口处缺陷明显减少.     

基于平均压强一致性原则的大尺寸气囊工具头优化设计

根据超大口径光学元件的加工需求,设计一种适应1～2m口径光学元件抛光的气囊工具头.建立了气囊工具头受载的有限元仿真模型,并以常用的球冠半径为80 m m的气囊工具头的静态加载实验验证了仿真模型的可靠性.基于平均压强一致性原则和仿真模型设计了球冠半径为320 m m的大尺寸气囊工具头,优化设计得到球冠内外橡胶层厚度分别为...     

等温压缩空气储能系统喷水量研究

为了揭示等温压缩空气储能系统中不同参数对喷水量的影响,提出了利用多变指数接近1的多变压缩来研究近等温压缩,将压缩终态的气态水、液态水、空气视为理想混合物,分析了压缩能量的分布状况,并运用饱和水蒸气分压公式、道尔顿分压定律和组分热力学参数,研究了不同状态参数下所需喷水量。研究表明,适当增大压比或降低终温(喷水量增大)可使得传热量比例增大,当压比为10、转速为100r/min时,喷水量由5.73kg/s提高至8.68kg/s,传热量比例提高了5%;压比、传热效率、终温均对空气与水质量之比有影响;其他条件一定时,转速对空气与水质量之比没有影响,当压比为10,传热效率为95%,终温为50℃,转速分别为60、100、150r/min时,空气与水质量之比均为0.86;较低压强(压比小于10)不利水储热的进行。     

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)

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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.