直接甲醇燃料电池运行参数的研究

以载量均为4 mg/cm2的Pt-Ru黑和Pt黑分别为阳极、阴极催化剂,以碳布为扩散层,以Nafion115为质子交换膜,制备膜电极,组装直接甲醇燃料电池并通过恒电位法和交流阻抗法分别测试性能和阻抗. 研究考察了各种工艺参数对电池电化学性能的影响,得出55 ℃下最佳工艺参数为:甲醇浓度为1.5 mol/L、流量为1.5mL/min时阳极反应达到最优,氧气压力在0.3 MPa、流量在800 mL/min时阴极反应达到最佳.     

直接甲醇燃料电池管状阴极的制备与性能

以管状金属钛网为支撑体,采用浸涂工艺在其外表面依次制备了气体扩散层、Pt/C催化层和Nafion 膜,制得管状阴极,并分析了影响电池性能的因素.研究结果表明,采用浆液浸涂工艺制备的阴极气体扩散层与催化层,均具有有利于气体传质和电化学反应的多孔结构.随着阴极催化剂载量的增加,单电池的性能也逐渐提高.当Pt载量为4.3 mg/cm2时,常温下以空气作为氧化剂,电池功率密度峰值约为12.3 mW/cm2,而同样的电池,在60 ℃下以氧气作为氧化剂,则可以达到40.0 mW/cm2,这表明温度和氧化剂种类与催化剂载量一样,是影响电池性能的重要因素.电池经约100 h工作时间后进行的等电压放电试验结果表明,该管状Ti基阴极的电化学稳定性优良.     

直接甲醇燃料电池的单电池实验测试及性能优化

以新型阻醇材料Na2Ti3O7/Nafion复合膜为质子交换膜,利用热压法制备膜电极(MEA),对直接甲醇单电池进行测试.考察了电池温度、阴极加湿温度、甲醇浓度、甲醇流速和空气流速5个参数对直接甲醇燃料电池极化曲线性能的影响.实验结果表明,电池温度对电池性能的影响较为明显,提高电池温度有利于得到较好的电池性能.甲醇浓度对电池性能影响也比较明显,较低甲醇浓度有利于提高电池性能.甲醇流速和空气流速对电池性能的影响较小,阴极加湿温度对电池性能几乎没有影响.通过分析优化,该直接甲醇燃料电池的电池性能最佳工作条件是在80℃情况下,低电流密度工作区采用较低浓度甲醇溶液,高电流密度工作区采用高浓度甲醇溶液.     

Pt-SnO2/C电催化剂异型直接乙醇燃料电池的性能

以掺杂石墨粉的中间相碳微球(MCMB/G)烧结管为阴极支撑体,采用浸涂工艺分别制备了扩散层和催化层,通过在其外表面包裹Nafion 117膜制得管状异型阴极并组装成异型直接乙醇燃料电池,采用水热乙二醇制备了适用于直接乙醇燃料电池的阳极电催化剂,并通过XRD,TEM和EDS等技术对其进行了表征.采用线性循环伏安曲线、交流阻抗等测试手段,对Pt-SnO2/C电催化剂异型直接乙醇燃料电池进行了性能测试,并考察了温度、氧气流量等对电池极化性能的影响.结果表明:异型电池阻抗大于传统的平板电池,但其活化后电池阻抗明显下降;较高的氧气流量和较高的工作温度有利于提高电池性能;60℃条件下,Pt-SnO2/C电催化剂异型直接乙醇燃料电池功率密度达到8.5 mW·cm-2.     

扩散层与催化层对直接甲醇燃料电池性能影响的数值研究

为了考察直接液体甲醇燃料电池(DMFC)中扩散层和催化层的结构参数对电池性能的影响,建立了二维、单相、全电池模型.模型中综合考虑了电化学动力学、水动力学、化学反应和各种组分传递的耦合过程以及甲醇窜流在阴极形成的寄生电流,对阳极催化层和阴极催化层传质过程引入了团聚块模型进行修正.利用此模型,通过自主开发的计算程序,计算了扩散层、催化层的厚度和孔隙率对电池输出性能及甲醇窜流的影响.计算结果表明:相对于催化层而言,电池性能在更大程度上依赖于扩散层的参数.在不同的电池输出电流密度下,扩散层厚度对电池输出性能有不同的影响趋势,应在考虑其他参数的基础上选择合适的扩散层厚度,以获得较优的电池输出性能.大的孔隙率可减小传质阻力,但在提高电池输出性能的同时会加重甲醇窜流.     

1 kW自呼吸PEMFC堆控制因素试验

自呼吸质子交换膜燃料电池(PEMFC)阴极侧湿度和温度耦合严重,且空气流量对湿度和温度影响不同,从而使得对电池输出电压的控制变得复杂.以氢气压力和提供阴极空气流量的风扇转速为影响因素,对相应的工作点集进行了正交试验研究.分析结果表明,风扇转速高于极值电压转速时,空气会带走更多的水分,从而使得质子交换膜逐渐干燥,阻抗增大,电池性能衰减;风扇转速低于极值电压转速时,空气流量带走的热量减少,使得阴极表面温度升高,阴极端相对湿度迅速减低,从而导致质子交换膜迅速干燥,电池性能衰减迅速.因此,每个工作点存在一个使电池电压最高的风扇转速值.     

直接甲醇燃料电池用Co-N-C电催化剂的制备及性能

以三聚氰胺甲醛树脂和硝酸钴为前驱体,在Ar保护下采用高温碳化方法制备用于直接甲醇燃料电池(DMFC)阴极的含氮碳载钴(Co-N-C)氧还原电催化剂.利用热重与红外光谱联用、X射线衍射分析、元素分析等方法表征了催化剂的制备过程和结构,采用旋转圆盘电极测试考察了不同碳化温度对Co-N-C电催化剂氧还原催化活性的影响及电催化剂的耐醇性能,并采用该催化剂为阴极催化剂进行DMFC单电池测试.结果表明:Co-N-C电催化剂具有较高的电催化活性和较好的耐醇性能;其氧还原起始电位在0.5V(vs.SCE)左右;700℃碳化温度下制备的Co-N-C电催化剂具有最高的氧还原催化活性.     

直接甲醇燃料电池的数学建模与神经网络辨识建模

针对直接甲醇燃料电池(DMFC)非线性系统建模问题,提出了两种不同的建模方法(1)采用电化学、流体动力学、热力学等理论,建立了DMFC电池性能数学模型;(2)利用改进型BP神经网络建立DMFC电池性能辨识模型.结合DMFC实验数据进行仿真测试,结果表明这两种建模方法均合理、有效,建立的模型精度较高,从而为设计DMFC在线控制器奠定了基础.     

基于钛网基膜电极组件的被动式直接甲醇燃料电池

基于钛网基膜电极组件（membrane electrode assembly,MEA）设计并制作被动式直接甲醇燃料电池（directmethanol fuel cell,DMFC）．钛网基MEA以钛金属网作为电极支撑体基底材料,Nafionll7作为质子交换膜．PtRU／XC-72R作为阳极催化剂,Pt／XC-72R作为阴极催化剂．被动式DMFC壳体采用有机玻璃材料制作．密封元件采用硅胶片制作．紧固件选用标准件．在室温空气自呼吸条件下,选取不同甲醇浓度的电解液．测试了基于钛网基MEA的被动式DMFC极化性能．结果表明：当电解液中甲醇浓度从0．5mol／L经过1．0mol／L增大到1．5mol／L时．基于钛网基MEA的被动式DMFC的功率密度峰值呈现先增大、后减小的规律;当甲醇浓度为1．0mol／L。电池功率密度峰值为3．91mW/cm2．     

单室直接微生物燃料电池性能影响因素分析

利用构建的单室微生物燃料电池,进行了阴极板中铁离子浓度、阳极底物、底物浓度及阳极板面积对单室直接微生物燃料电池性能影响的研究.结果表明:在其它条件相同的情况下,随着阴极电极板中Fe3 含量的增加,电池负载输出电压随之提高;不同底物的阳极反应,随着产生的电子和质子数的提高,电量随之增大;输出电压亦随底物浓度的增加而提高,但底物葡萄糖的浓度饱和值为0.72g/L;增加阳极板数量加大阳极比表面积,更多的微生物吸附在阳极电极上传递电子,电池输出电压与阳极板数量不成倍数关系.此研究为单室微生物燃料电池的应用提供了理论依据.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

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。     

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.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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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