Ag2O超级电容器的研究

用固相合成法制备Ag2O作为超级电容器材料,通过循环伏安与恒流充放电等测试手段对Ag2O电极及与作为负极的活性炭电极组成的电容进行分析.结果表明,在7mol·L-1KOH电解液中,Ag2O电极在0.15～0.35V(相对于Hg/HgO)的电压范围内表现出了法拉第电容特性.在不同电流密度下,电极比容量达427.3～554.9F·g-1,Ag2O/活性炭单体电容器比电容为42.5～61.65F·g-1.同时还对正极中Ag2O的含量及导电剂对Ag2O/活性炭单体电容器性能的影响进行了研究.     

凝胶聚合物电解质MnO2/AC电容器的研究

采用液相氧化法制备了MnO2超级电容器电极材料,以MnO2为正极材料,活性炭(AC)为负极材料,丙烯腈作聚合物单体,碳酸二甲酯(DMC)与碳酸乙烯酯(EC)的混和液作增塑剂,高氯酸锂为支持电解质,采用内聚合法制备PAN基凝胶聚合物电解质MnO2/AC混合电容器.通过循环伏安、交流阻抗、恒流充放电等测试方法对混合电容器的电化学性能进行了测试.结果表明:混合电容器的工作电压为2.5 V,比容量为27.3 F/g(i=0.5 mA/cm2),比同电解质体系的AC/AC电容器提高约48.21%.     

掺钴锰酸锂的合成及在水系电解液中的赝电容性能

采用尿素辅助溶胶凝胶法合成了尖晶石型掺钴锰酸锂(L iMn2-xCoxO4,0≤x≤0.3)纳米颗粒.以L iMn2-xCoxO4电极为正极,活性炭(AC)电极为负极,在1 mol.L-1L i2SO4水系电解液中组装成模拟非对称超级电容器AC/L iMn2-xCoxO4,通过循环伏安和恒流充放电法研究其赝电容性能.电化学测试结果表明,随着钴掺杂量的增加,AC/L iMn2-xCoxO4电容器的比电容呈下降趋势,但循环性能得到改善;其中AC/L iMn1.9Co0.1O4电容器展现出较大的比电容和较好的循环性能.在L i2SO4水系电解液中,当工作电压为(0-1.4)V、电流密度为100 mA.g-1时,AC/L iMn1.9Co0.1O4电容器的初始比电容为42.6 F.g-1;经1 000次循环后比电容为40.8 F.g-1,比电容保持率为95.8%.     

活性炭比表面积对双电层电容特性的影响

用KOH活化活性炭作为电极材料制作双电层电容器,用接触角测定其润湿性,用恒流充放电、循环伏安等方法研究活性炭的电化学性能.结果显示,炭膜浸润时间最短约为90 min,双电层电容器的比电容随比表面积增加而增大.比表面积为1932m2·g-1的炭样在1mol·L-1 的H2SO4电解液(677mA·g-1)中充放电最大比电容为167F·g-1.     

CoO@ Ni-Co-S无粘结剂电极材料非对称型超级电容器性能研究

采用水热法和电化学沉积法在泡沫镍上制备了CoO@ Ni-Co-S电极材料,并对其进行了SEM、XRD、XPS表征和电化学性能测试.结果表明:本材料具有较高的电化学性能,在电流密度为1 A/g时,比电容为1 352 F/g;电流密度为10 A/g时,比电容仍能达到1 055 F/g;进一步通过稳定性测试研究发现,在电流密度为2 A/g下充放电2 000次,电容保留率为87%.以CoO@ Ni-Co-S复合材料作为正极,活性炭作为负极构筑非对称型超级电容器,该装置在电流密度为1 A/g时,比电容为209 F/g,操作电压窗口为1. 7 V,功率密度为2. 99 k W/kg时,能量密度可达39. 7 Wh/kg.     

弱结晶二氧化锰超级电容器充放电分析

以等物质的量的高锰酸钾和乙酸锰为原料,采用机械化学法制备出弱结晶型α-MnO2超级电容器电极材料.在1.2V电压内,200mA·g-1电流密度下对对称型超级电容器进行恒流充放电测试.采用XRD法、循环伏安及交流阻抗法对充放电前后电极材料的结构以及电化学性能进行表征,首次采用求斜率法对充放电曲线分析.结果表明:超级电容器表现出法拉第电容与双电层电容的双重特征;在循环过程中,电化学惰性物质Mn3O4生成,循环伏安图中氧化还原峰逐渐消失;充放电曲线的法拉第电容特征逐渐消失而接近双电层电容理想曲线;超级电容器的比容量、等效串联电阻发生了对应的变化,其最大电极比容量达到416F·g-1,经过近500次循环后,比容量为220F·g-1.     

麦穗状MnO_2的制备及其超电容特性

超声条件下,利用KMnO4为氧化剂来氧化聚乙二醇-20000(PEG-20000)来制备超级电容器电极材料MnO2.XRD测试表明,合成的MnO2为α-MnO2和γ-MnO2的混合相.TEM测试表明,由于PEG-20000的软模板作用,所制备MnO2呈现出由许多纳米粒子组成的的麦穗状结构.电化学测试表明,麦穗状MnO2在1MK2SO4水溶液中具有良好的超电容特性,其比电容可达到310F.g-1,经过1000次循环后,电极容量仍保持在92%以上.     

1.7V活性炭基K_2SO_4水系超级电容器

1种以K2SO4水溶液作为电解液的高电压对称型活性炭基超级电容器.采用循环伏安法、恒电流充电/放电、电化学阻抗谱和循环稳定性等电化学方法研究了其电化学性能.结果表明,该电容器的工作电压为1.7V,在电流密度为0.25A·g-1时,单电极比电容高达156F·g-1,在功率密度为213 W·kg-1时能量密度达到38Wh·kg-1(以正负极活性物质的总质量计),等效串联电阻为1.92Ω,3 600s后的漏电流是0.36mA,在400次充放电循环中库伦效率接近100%.该研究结果表明中性的K2SO4水系电解液对探索一种新型高能量密度的超级电容器提供了一种新的可能.     

铜离子掺杂钒基配位聚合物的制备及其超级电容器性能

通过两步微波和离子交换的方法得到一种直径约为 1.5 μm 的微球形貌铜离子掺杂钒基配位聚合物 (V-Cu-HHTP). 聚合物中部分取代的 Cu$^{2+}$提高了配位聚合物的导电性和结构稳定性, 并提供 V、Cu 的协同效应, 在用于超级电容器电极材料时表现出良好的电化学性能. 在 1 A$\cdot$g$^{-1}$ 的电流密度下, V-Cu-HHTP 表现出 287 F$\cdot$g$^{-1}$ 的比容量, 在 10 A$\cdot$g$^{-1}$ 的大电流密度下循环 3 000 圈后, V-Cu-HHTP 的电容保持率仍有 98.6%, 比相同测试条件下未掺杂的 V-HHTP 电极表现优异 (比容量为 227 F$\cdot$g$^{-1}$, 电容保持率为 94.2%). 选取 V-Cu-HHTP 作为正极, 活性炭 (activated carbon, AC) 作为负极, 组装非对称超级电容器 V-Cu-HHTP//AC, 电压窗口达到 1.6 V. V-Cu-HHTP//AC 在功率密度为 795.0 W$\cdot$Kg$^{-1}$ 时, 最大能量密度为44.1 Wh$\cdot$Kg$^{-1}$, 优于许多钒基超级电容器. 优异的电化学性能归因于: 双金属配位聚合物的设计为体系提供了优异的协同效应, 提高了结构稳定性; Cu 离子掺杂提高了导电性; V-Cu-HHTP 的多孔特征为体系暴露更多活性位点, 提供优异的双电层电容特性.     

聚苯胺修饰活性炭电极的电化学性能

有机体系下,采用循环伏安法(CV)在活性炭电极表面电聚合聚苯胺制备聚苯胺/活性炭复合电极,通过循环伏安、恒流充放电和电化学交流阻抗谱(EIS)测试了电极的电化学特性,结果表明,聚苯胺/活性炭复合电极具有良好的电容行为,在-1.0～1.5V参比极为Ag/AgCl,测试区间内具有较大的电化学容量,电极比电容高达276F·g-1,较活性炭电极的比电容92F·g-1有了很大提高.并且交流阻抗法测得活性炭电极的电荷转移电阻Rct为4.9Ω,而复合电极Rct仅2.4Ω.1000次充放电测试后,复合电极比电容仅衰减15.7%.由此表明,在有机体系下聚苯胺/活性炭复合电极是一种具有良好循环寿命和高比电容的复合电极材料.     

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.     

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…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

<正>~~     

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。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

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