无限大正交加筋层合板的隔声性能分析

基于经典层合板理论,计及加强筋弯曲及扭转运动影响,建立无限大正交加筋层合板传声损失的理论模型.采用空间谐波展开和虚功原理的方法,推导出正交加筋层合板的传声损失计算公式,并将计算结果与简化模型和板梁组合模型的计算结果进行对比,结果吻合良好,验证了所建模型的有效性及广适性.最后,数值分析了层合板铺设方式、铺设角度、刚度、材料损耗因子和加筋间距等参数对结构隔声性能的影响.     

双层微穿孔管消声器传声损失理论计算与分析

基于一维平面波理论和微穿孔结构吸声理论,推导双层微穿孔管消声器传声损失理论模型,并将理论计算值与三维有限元声学仿真结果进行对比,利用消声器传声损失理论公式,对比双层和单层微穿孔管消声器的传声损失,分析内外层膨胀腔厚度对双层微穿孔管消声器声学特性的影响。研究结果表明:双层微穿孔管消声器在中低频的传声损失要大于单层微穿孔管消声器;增加内外层膨胀腔的厚度,可以提高双层微穿孔管消声器的消声特性;当双层膨胀腔总厚度固定,外层膨胀腔厚度大时,消声器在中低频的声学性能更好。     

锈蚀和疲劳耦合下RC梁损伤演变分析和承载力评定

为了对钢筋混凝土(RC)梁的承载力进行准确快速评估，考虑锈蚀和疲劳耦合作用，对RC梁的静刚度进行了敏感性分析，给出了静刚度简化计算方法。以一钢筋混凝土简支T梁为例，计算了锈蚀和疲劳耦合作用下其承载力和刚度的退化情况，对比了不同刚度计算方法的差异，研究了钢筋面积对开裂截面刚度的影响，明晰了刚度与承载力的内在关联，根据承载力损失系数与刚度损失系数之间的关系，给出了基于频率的承载力计算公式。研究结果表明：锈蚀和疲劳耦合作用会加速桥梁承载力和刚度的退化过程；锈蚀对承载力和刚度影响主要体现在钢筋面积减小方面，锈蚀导致的钢筋与混凝土间粘结性能的降低对刚度影响不大；传统刚度计算公式中参数取值不易确定，会影响计算精度。本研究提出的刚度简化计算公式参数少、取值方便、计算结果较准确；对于开裂钢筋混凝土梁，承载力与刚度之间可以通过受拉钢筋面积相关联；承载力损失系数与动刚度损失系数有良好的相关性，可以采用文中给出的基于频率的承载力计算公式对薄弱截面位于跨中附近的开裂RC梁进行承载力评估。     

青海湖地区空气密度年变化分析

对《风电场工程建设手册》中给出的空气密度计算方法进行了合理推演变形。根据气压、温度、相对湿度3个参数,计算青海湖地区空气密度并得出了该地区空气密度变化规律。为该地区风电场建设以及相关工作者提供了可借鉴的理论依据。     

高海拔对低压电器产品的影响与对应措施

根据高海拔地区气压低、气温低、空气密度低的气候特点,通过高海拔地区低压电器产品使用情况的试验研究及分析,得出高海拔对低压电器产品性能的影响主要体现在温升、绝缘性能、接通能力和分断能力及对产品的动作特性上,提出低压电器产品在高海拔地区使用时的几点对应措施。     

不同海拔对车用散热器性能的影响分析

为了研究不同海拔对车用散热器性能的影响,采用Fluent软件建立车用散热器仿真模型.由于散热器结构复杂,直接建模仿真计算量较大,将散热器翅片部分视作多孔介质模型,多孔介质参数通过对散热器单元仿真得到.结果表明:空气密度的下降是影响散热器传热性能的主要原因,随着海拔的升高,大气压力逐渐降低,空气密度随之减小,导致气体雷诺数相应减小,同时对流换热系数和散热量呈现下降趋势.海拔每升高1000 m,换热系数下降4.72％,散热量下降6.58％.     

多孔纤维吸声材料填充蜂窝结构的声学性能

本文理论研究了多孔纤维吸声材料填充矩形蜂窝结构的声学特性.假设周期蜂窝结构将多孔纤维吸声材料划分为独立周期子空间,理论建模中选取单个蜂窝胞元进行分析.蜂窝结构内部的多孔纤维吸声材料采用等效流体模型进行模拟,斜入射的声波在各个子空间呈驻波分布,由声场的声压和速度可积分得到通过蜂窝结构入射平面和透射平面的能量流,从而得到多孔纤维吸声材料填充蜂窝结构的吸声及传声损失性能.与单一多孔纤维材料声学性能的对比发现,多孔纤维吸声材料填充蜂窝结构的吸声性能得到了有效提高.基于理论模型,进一步分析了结构参数对多孔纤维吸声材料填充蜂窝结构吸声/传声损失性能的影响.     

云凝结核数浓度观测影响因子的实验室研究

气溶胶的云滴活化能力影响云的微物理特性, 还表征气溶胶吸湿性的强弱。活化气溶胶(即云凝结核, Cloud Condensation Nuclei, CCN)的观测研究中的重要方法是CCN计数器(CCN Counter, CCNC)的应用。针对CCNC观测的影响因子进行了实验室研究。实验结果表明, CCNC所处的气压和设置的流量会对过饱和比产生等比例的影响, 而进气温度可能导致非线性的影响。实验中发现当气压差超过300 hPa时, CCNC气压调节装置会导致气溶胶的损失, 且损失的比例随着压差的增大而增大。在气溶胶浓度超过10000个/cm³、过饱和比低于0.2%时, 会出现对CCN数浓度的低估, 可能是由于水汽消耗导致CCN无法全部活化而不能被CCNC观测。研究结果及给出的建议对CCN的观测有指导意义, 同时有利于CCN数据的质量控制和分析工作。     

对边简支加筋三明治板隔声性能研究

针对加筋三明治板声学特性的研究主要集中于无限大结构、很少考虑边界条件影响的问题,结合脉冲函数的使用,提出了对边简支、层芯为平行筋板的三明治板的动态响应力学模型,利用模态函数法推导了结构的传声损失计算公式.将理论和模拟结果进行了对比,二者吻合较好,验证了模型的有效性.所提出的计算方法相对于有限元数值方法具有更高的计算效率,能在较宽的频段范围内给出精确的结果,且便于分析结构传声的物理机制和结构参数对传声性能的影响.研究结果表明:简支边界在隔声曲线上引入了结构的共振隔声波谷;加筋三明治板结构中同样存在明显的吻合共振效应;随着入射声波频率的提高,筋板惯性效应的影响越发明显.     

钢筋锈蚀作用下盾构隧道结构损伤劣化性能

在长期的水土荷载和侵蚀性物质联合作用下，盾构隧道钢筋混凝土衬砌结构会经历腐蚀-损伤-劣化过程而逐渐失效，导致服役性能大幅降低。本文引入内聚力模型（CZM）及混凝土塑性损伤模型（CDP），建立考虑钢筋混凝土间粘结滑移的盾构隧道衬砌锈蚀三维数值模型。综合考虑钢筋锈蚀引起的自身力学劣化、混凝土有效截面损失及钢筋混凝土粘结性能退化等因素，分析了围岩水土荷载和钢筋锈蚀耦合作用下衬砌结构形变、损伤演变规律和整体结构劣化特征。研究表明：1）锈蚀作用导致衬砌结构刚度降低，大大加深了衬砌结构的变形程度。锈蚀造成衬砌结构不同部位的刚度损失不同，反映了锈蚀作用下衬砌结构损伤的差异性。2）衬砌结构的围岩侧与临空侧损伤差异较大。相同锈蚀率下，衬砌受压侧受到挤压作用，限制裂缝的发展，导致受压侧损伤很小。3）在锈蚀过程中隧道衬砌结构拱顶弯矩不断减小，拱顶损伤不断加深，损伤区域逐渐扩展，截面刚度损伤最显著。4）衬砌结构自身性能不断劣化，出现内力重分布。衬砌结构的裂缝多出现在围岩侧。研究成果可为隧道衬砌结构服役性能的评估提供参考。     

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.