双模态颗粒声凝并微观行为的数值模拟

考虑颗粒间多种相互作用机理及颗粒碰撞后的凝并与反弹机制，建立声凝并微观动力学模型，对大粒径外加颗粒及两个邻近的亚微米细颗粒之间的声凝并微观行为进行数值模拟研究。结果表明，双模态颗粒声凝并行为主要表现为外加颗粒仅与一个细颗粒发生凝并，以及外加颗粒先后与两个细颗粒发生凝并，声尾流效应、重力沉降作用是双模态颗粒声凝并的重要机理。随着外加颗粒初始位置与波节间距的增大，外加颗粒与较近细颗粒的平均凝并时间变化很小，两者形成的团聚体与较远细颗粒的平均凝并时间显著缩短；外加颗粒距离波节很近时，其仍能与较近的细颗粒发生凝并。对于外加颗粒与较近细颗粒以及两者形成的团聚体与较远细颗粒的凝并，随着外加颗粒直径的增加，平均凝并时间显著缩短，凝并概率先增加而后趋于恒定。     

沉淀过程中超细颗粒的凝并与生长模型

建立了适合于高源速率沉淀过程的凝并生长动力学模型,系统地考察了操作参数对超细颗粒粒径及其分布的影响规律。研究表明,随着反应物浓度的增加,凝并生长速率加快,粒径及分布均呈单调增大趋势;生长速率对温度变化不敏感,在较高过饱和度之下,温度对合成粒子粒径影响很小;随着反应时间的延长,粒径变大,分布变宽,并趋于“自保”形式。提出了液相化学合成法制备超细颗粒过程中颗粒性能的控制策略。     

钢铁过程细微颗粒物凝并性能研究

为寻求一种收集钢铁冶炼过程中产生的气溶胶颗粒的方法,研究了EAF粉尘颗粒物的性质.采用Zn蒸汽氧化产生的ZnO模拟气溶胶颗粒进行凝并实验研究,另采用熏香烟雾在不同的搅拌速度下进行气溶胶凝并实验,并将实验结果与理论计算进行比较.同时,采用一种考虑颗粒间相互作用的气溶胶凝并模型估算反应范德华力作用的Hamaker常数.实验结果表明,在搅拌条件下,对于气溶胶的凝并应考虑微细颗粒间的相互作用.     

收缩扩张喷管中稀疏颗粒加速运动及喉道优化

直升机、运输机在简易场地起降过程中,发动机可吸入的二氧化硅等微小颗粒,对叶片造成冲击磨损,冲击速度可达200m/s以上。冲蚀试验常采用直喷管加速固体颗粒,在入口总压为0.6 MPa时,颗粒速度难以达到200m/s。为更有效地加速颗粒,采用超音速收缩-扩张喷管,通过数值模拟研究了该喷管对稀疏二氧化硅颗粒的加速运动,并利用实验验证了数值模拟的准确性。在此基础上,对喉道尺寸进行优化以提高喷管对颗粒的加速性能。结果表明:收缩-扩张喷管对颗粒的加速主要发生在扩张段,管内激波不会引起颗粒速度的震荡,颗粒的加速度与气流、颗粒之间的相对速度以及气流的密度有关;在入口总压为0.6 MPa的条件下复现5级砂尘环境,喉道半径为0.001 6m的喷管加速效果最佳,可获得的颗粒速度达到218m/s。     

亚微米颗粒物的沉积与凝并的模拟与实验研究

建立了一个带有粒径高分辨率的亚微米颗粒物的动力学模型,应用高精密仪器SMPS做了系列实验以对模型进行验证.结果表明:采用该模型能够比较准确地预测亚微米颗粒物的粒径谱演变,同时模型显示了对不同峰值形态粒径谱的适应性;表面沉积效应对超细微粒的影响更为明显,凝并与浓度值有着密切的关系;通过亚微米颗粒物的数量浓度和CMD(Count Median Diameter)的变化可以反映凝并的动态特征.     

双极预荷电装置凝并特性实验研究

为提高对微细颗粒物的捕集效率,基于横向双极静电除尘技术,开发出一种线-管式双极预荷电装置。借助多物理场耦合软件,采用电晕放电模块耦合湍流模块,研究其电流体动力学分布规律;搭建实验装置,测试其凝并特性。数值模拟结果表明：双极预荷电装置内同时存在生正、负电晕和产生正、负电荷,具有良好的湍流混合和凝并效果。对中位粒径为1.7 μm硅微粉的凝并实验结果表明：经过预荷电装置后粉尘的粒径分布呈现明显的双峰分布;在平均场强为4~6 kV/cm区间,凝并效率随着外加电压的增加而提高;当外加电压超过11 kV,所有粒径区间粉尘的凝并效率均超过95%。研究结果有助于拓展横向双极静电除尘技术的应用范围,为双极静电技术的推广及工业应用提供参考。     

电除尘器中粉尘粒子的凝并

应用电流体力学和外力场输运理论,分析了电收尘器中带电粉尘粒子的凝并现象。在一定的简化条件下建立了粒子凝并速率计算式,并通过实验进一步探讨了带电粉尘粒子凝并的机理。研究结果表明,电场中带电粉尘粒子的凝并受粒子表面电荷分布和电荷量、粒径、粒子所带电荷的极性以及中性电荷粒子的影响。无论单极或双极电晕,带电的粉尘粒子都发生凝并,但带正、负电荷粒子的凝并受限于某一作用范围。     

交变电场频率对荷电微细粉尘凝并影响的实验研究

高流场中气体粒子动量大,有助于提高其输运项和等离子体浓度,使高流场中微细粉尘凝并成为可行.为此进行高流场中交变电场频率对微细粉尘凝并的实验研究.结果表明:凝并电场强度峰值为590 V/cm,频率在80-100 Hz时,0.3～0.5μm范围内的粉尘粒数占有率降低25%左右;大于1μm范围的粉尘粒数占有率提高35%左右.从实验数据可知,高流场中微细烟尘凝并最佳频率为80～100 Hz.本实验研究结果表明,在不增加电除尘器的体积和不改变其原有运行参数的条件下进行电凝并收尘,有望解决电除尘器对微细粉尘捕集效率低的问题.     

基于正交设计的微细颗粒复合凝并建模及仿真

为了研究微细颗粒凝并效率影响因素的敏感性,将颗粒群平衡模型与欧拉多相流模型进行耦合,通过用户自定义函数分别引入布朗凝并、湍流凝并与声波凝并的复合凝并核函数和颗粒凝结增长速率函数,建立了一种适合不同凝并方式特点的复合凝并模型.采用正交设计对微细颗粒的凝并过程进行数值模拟,研究了初始蒸汽饱和度、停留时间、声压级和声频对复合凝并过程的影响程度的主次关系.结果表明,该复合凝并模型能有效地表征PM_(2.5)颗粒凝并效率.通过PM_(10)和PM_(2.5)凝并效率正交模拟试验进一步得出,复合凝并作用下各参数的影响程度均为:声压级停留时间初始蒸汽饱和度声频.声压级、停留时间和初始蒸汽饱和度的增大有利于凝并效率的提高,而声频则存在一个最佳值使得凝并效率达到最高,且PM_(2.5)凝并效率的最佳频率比PM_(10)高.该模型的建立对研究微细颗粒物复合凝并相关因素的影响程度具有重要作用.     

考虑车辆性能差异的高速路施工区层级限速措施

为提高高速公路施工区的通行能力,降低交通冲突率,本文结合不同车辆的动力特性、运行速度、加速度等参数,对鹅公岌隧道上盖工程施工期间的拟建施工疏散道路提出5种速度管理措施,利用Vissim软件进行仿真模拟和对比分析,并结合仿真数据对拟建施工疏散道路的设计和速度管理方案进行了评价和改进。改进方案中将原来的三车道并在一起,转弯半径由15m增大至100m,弯道限速值由20 km/h增大至40 km/h。结果表明：对施工区道路采取层级限速措施可有效降低车辆在施工路段的行程时间、延误、排队长度和冲突率;采用三级限速措施可使拟建疏散道路两个行驶方向的冲突率均降低0.6次.米^-1;改进方案中80%以上的车入口弯道之前将车速控制在40km/h左右。可见,针对不同车型采用不同的限速值可以缩短车辆在施工路段的行程时间,并有效减少车辆的平均延误。     

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).     

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.     

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.