定形相变材料蓄热地板电采暖系统热性能

蓄热式电采暖系统可以利用夜间廉价电供热.建立了分析定形相变材料蓄热地板电采暖系统热性能的理论模型,通过与实验结果比较,验证了此模型和程序的正确性.藉此模型分析了系统各因素对其热性能的影响,及该类系统在不同气候地区的应用可行性和整个冬季的电加热控制方法.结果显示,在保证相变材料用量足够时,可通过改变相变温度和空气层厚度,设计或控制此系统热性能; 在不同热负荷建筑中,通过合理设计,此蓄热采暖系统可取得较好效果; 应用控制地板加热面积的方法,可使整个采暖季的室温基本保持在人的热舒适范围内.     

相变混凝土的制备与性能研究综述

综述了相变材料的分类及特点、相变材料的定形与封装技术、相变混凝土的配合比设计与性能等3个方面的研究成果,对固-液相变材料的热物理参数、应用现状及多元复合相变体系进行了研究,归纳整理了相变材料的定形与封装技术,重点讨论了多孔基体吸附法,对比分析了相变混凝土的设计原理、力学性能与热物特性变化规律,并对相变混凝土研究方向进行了展望.结果表明:石蜡、脂酸和醇类等3种相变材料更适合于工程建筑环境的应用;相变材料不宜与混凝土集料直接混合;通常采用多孔基体材料吸附液体相变材料来制备相变骨料;相变混凝土的导热系数受相变骨料掺量影响明显,比热容会随掺量增加而提高,强度往往大幅降低.     

相变蓄能建筑墙体研究进展

对相变材料在墙体中的封装方式(直接混合、宏观封装、微观封装和定形相变材料封装)、相变材料的种类和物性等方面的研究进行了归纳总结.从实验和模拟2个方面,对相变材料位于墙体表面和墙体内部影响室内环境和建筑能耗的研究进行了综述和评价.分析表明,微观封装和定形相变材料的封装效果较好;墙体用相变材料的相变温度一般在20~30℃范围内;相变材料层在墙体中的安装位置可分为墙体表面和墙体内部2种,但相变材料层在墙体内的最优位置并不固定,受相变材料物性、墙体材料以及室内外环境工况的影响.通过相变材料与墙体合理高效的结合,可充分发挥相变材料的高蓄热特性,提高墙体的热性能,达到调节室内环境温度、降低建筑能耗的目的.     

高温套管式熔融盐相变蓄热器蓄热性能实验研究

为揭示高温熔融盐相变蓄热器的蓄放热特性,并进一步提高其蓄热性能,搭建了高温梯级熔融盐相变蓄热实验台(最高蓄热温度可达800℃),对高温套管式熔融盐相变蓄热器开展了蓄/放热性能实验研究。首先选择蓄热性能优良的二元碳酸盐作为高温相变蓄热材料,测试了其热物性;其次实验研究了高温套管式熔融盐相变蓄热器的总蓄/放热时间、平均蓄/放热速率以及蓄热效率等蓄/放热性能。结果显示:相变蓄热材料的熔化过程存在着非均匀性;在放热过程中,位于不同位置的相变蓄热材料存在着不同程度的过冷现象。最后,实验研究了在熔融盐侧添加环形肋片对高温熔融盐相变蓄热器的蓄/放热性能的强化效果,以及空气温度、质量流量等运行参数分别对光管和肋片管相变蓄热器总蓄/放热量、平均蓄/放热速率以及蓄热效率的影响。结果显示,在添加肋片后,相变蓄热材料温度分布更加均匀,蓄热过程结束时相变蓄热材料的最大温差由51.1℃下降到43.2℃,下降了15.4%,高温相变蓄热器的平均蓄热速率与平均放热速率分别增加了6.8%和9.1%。实验结果可为后续高温梯级熔融盐相变蓄热器的性能研究以及实际应用提供参考。     

海绵状氧化石墨烯/聚乙二醇单甲醚相变材料的制备及性能

以海绵状氧化石墨烯(spongy graphene oxide,SG)为载体材料,聚乙二醇单甲醚(methoxy polyethylene glycol,MPEG)为相变物质,通过物理浸渍法制备了定形相变材料。采用X射线衍射、傅里叶变换红外光谱、差示扫描量热法、热失重和热台等方法对定形相变材料的结构、相变性能、热稳定性和定形能力进行表征和分析。结果表明,当SG质量分数为8%时,样品焓值最大且定形效果最好,结晶温度和熔融温度分别为18.7和30.7℃,焓值达到140.3 J/g,当温度达到250℃时,无任何泄漏发生,且热稳定性良好。该定形相变材料有望在聚丙烯相变纤维中实现应用。     

太阳能热发电复合相变蓄热材料的实验研究

针对相变材料无机盐KNO3/NaNO3(摩尔比50/50)导热系数低,影响了蓄热系统充放热过程传热效率,制备了适用于太阳能热发电系统的无机盐/膨胀石墨复合相变材料,对复合相变材料的微观结构和热物性进行了分析,并搭建充放热测试平台对相变材料分别进行了热性能研究。结果表明:复合相变材料中的无机盐均匀分布在膨胀石墨中,其相变潜热与基于复合材料中无机盐质量分数的计算值相当,添加膨胀石墨后相变材料的导热系数得到了改善;在充热过程中纯无机盐的换热方式以自然对流为主,同一蓄热单元内沿轴向上下位置温差较大,不同蓄热单元内相同位置完成充热过程所需时间从上到下依次增加,而对于无机盐/膨胀石墨复合相变材料(质量比90/10)充热过程以导热为主;与纯无机盐不同,同一蓄热单元内沿轴向上下位置温度变化趋势基本一致,不同蓄热单元相同位置完成充热过程所需时间几乎没有差别。添加膨胀石墨后,相变材料的充热过程所需时间减少较小,而放热过程所需时间减少约45%,传热介质流量的变化对复合相变材料充/放热过程影响较小。     

太阳能热发电用高温相变蓄热器的数值模拟

对采用单级相变材料(PCM)蓄热的太阳能热发电用高温相变蓄热器的蓄热过程进行了数值模拟。得到了采用单级蓄热时熔化过程中PCM温度和液相率随时间的变化曲线及不同时刻液相率的分布云图。通过对曲线和云图的分析,在保证蓄热量的前提下,提出了采用3种PCM级联蓄热的高温相变蓄热器的设计方案,并对其蓄热性能进行了模拟。结果表明,采用级联蓄热的方案减小了蓄热的总时间,且有效地降低了单级蓄热末期"死区"对蓄热性能的影响,使PCM的液相率分布更加均匀,为太阳能热发电用高温相变蓄热器的优化设计提供了理论依据。     

相变蓄热水箱蓄热性能数值模拟研究

在封闭静止的蓄热水箱中添加相变材料可以增加水箱热容量、延长水箱升温时间。分别建立了有、无相变单元蓄热水箱的物理模型，利用有限体积分析法对蓄热水箱加热过程进行数值模拟，探讨了封闭水箱加热过程中相变单元的熔化规律和相变单元对水箱温升的影响规律。研究结果表明相对于纯水蓄热水箱，当蓄热水箱中加入占水箱容积9.05%（体积分数）的相变单元、其平均温升29 K时，蓄热水箱的整体热容量提高了25.58%，加热时间延长了1 100 s；蓄热水箱内只在垂直方向上存在热分层，导致含有相变单元的蓄热水箱较高位置处的相变单元先熔化，降低了较高位置处水的温升速率，使得相变蓄热水箱和纯水蓄热水箱的热分层剧烈程度存在差别；以最大温差值作为判断水箱热分层剧烈程度的依据，不同加热功率下相变蓄热水箱的热分层特征变化规律大致相同，但加热功率越大，热分层现象越剧烈。     

碳纤维导热型低温相变材料蓄热电暖器蓄放热性能实验研究

使用膨胀石墨、碳纤维与石蜡研制出复合型相变蓄能材料,利用膨胀石墨、碳纤维作为高导热材料与结构支撑材料;通过物性参数遴选、结构参数优化设计方法,搭建高导热性能的复合相变材料蓄热电暖器实验台;研究不同蓄放热运行工况下该装置的蓄放热性能。研究结果显示,与日间主动式放热工况相比,日间被动式放热工况放热速率衰减较慢,被动式放热工况的最低放热速率比主动式放热工况最低放热速率高24. 7%。该装置可以利用主/被动放热方式调节蓄放热速率,满足不同房间的供热需求。在夜间蓄热、日间放热的运行工况下,该相变蓄热电暖器所在房间温度波动较小,具有较好热舒适性。该蓄热电暖器蓄热效率达67%,能充分利用夜间低谷电蓄热,实现降低运行费用的目的。     

基于分形的多孔介质复合相变材料的储热特性

本文利用膨胀石墨和纳米颗粒来强化相变储热系统的传热性能。在膨胀石墨基体中填充含纳米颗粒的相变材料,用焓-孔隙度法模拟材料的相变过程。针对不规则的膨胀石墨孔隙结构,用三维W-M分形函数修正膨胀石墨孔隙率波动,以研究不同的孔隙率和有效导热系数比对固态显热蓄热阶段相变材料熔融速率的影响。在液态显热蓄热阶段时探讨膨胀石墨孔隙率以及纳米颗粒体积分数对相变储热系统中对流传热的影响。研究结果表明,分形分布的孔隙结构能有效地抑制纳米颗粒的自由运动从而降低了纳米颗粒的局部团聚的可能性,所以利用三维W-M分形函数修正的膨胀石墨比采用平均孔隙率能更好地模拟相变材料的熔融速率。在固态显热蓄热阶段,膨胀石墨孔隙率为0.8的相变材料熔融速率比孔隙率为0.85和0.9显著增加,另外,膨胀石墨与纳米颗粒-相变材料的有效导热系数比为100的熔融速率也明显比有效导热系数比为80和60的快。当相变材料处于液态显热蓄热阶段时,其在膨胀石墨孔隙中产生对流,对流传热速率随着膨胀石墨的孔隙率增大而增大,纳米颗粒体积分数的增加也会提高对流传热速率。     

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.     

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.     

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.