基于APDL的ANSYS嵌入式配筋实现

以ANSYS为平台,应用APDL实现钢筋混凝土有限元模型中钢筋单元嵌入混凝土单元的功能.应用该方法可以在ANSYS中方便地建立复杂的钢筋混凝土分离式模型.利用Newton-Raphson方法求解等参数单元的坐标插值函数中被约束节点在自然坐标系下的坐标值,得到自然坐标系下节点对应形函数值,并将对应的形函数值作为约束方程中混凝土单元节点位移的分项因数,从而实现嵌入节点与被嵌入单元位移协调.计算结果与Marc的算例结果吻合良好,说明该方法合理.     

基于Cortex-A8处理器的车牌识别系统设计

随着车辆数量的日益增多,交通管理的压力日趋增大,越来越多的场合需要实时车牌识别。针对此问题,本文设计一种基于Cortex-A8处理器的实时车牌识别系统。该系统以Coretx-A8嵌入式处理器为核心,通过V4L2接口进行视频流的采集,然后运行基于改进的OpenCV车牌识别算法,最后通过MJPG-streamer和Socket编程进行视频流和车牌数据的传输。测试结果表明,该系统具有较强的稳定性和实时性,具有较强的实用价值。     

次氯酸钠氧化法测定聚丙烯酰胺浓度的研究

阐述了次氯酸钠氧化法（浊度法）测定部分水解聚丙烯酰胺浓度的反应机理，研究了聚丙烯酰胺的相对分子质量、次氯酸钠溶液浓度、反应时间对吸光度值的影响，针对大庆油田杏二中三元复合驱采出水中含有碱和表面活性剂、pH值高、黏度大、富集硫化物和亚硫酸根等特点，提出采用过硫酸铵一浊度法检测三元复合驱采出水中聚丙烯酰胺浓度。     

考虑邻近建筑物影响的内撑式排桩基坑支护局部破坏研究

基坑开挖与周围环境相互影响,而邻近建筑物对基坑支护体系局部破坏的影响鲜有研究。通过内撑式排桩支护砂土基坑模型试验,研究了坑外有、无建筑物两种情况下基坑开挖、支撑局部破坏和桩后砂土渗漏对内撑式排桩基坑支护体系受力及变形性能的影响。试验结果表明：受邻近建筑物的影响,随基坑逐渐开挖,平行于邻近建筑物长边的支护桩桩顶水平位移增大,而垂直于邻近建筑物长边的支护桩桩顶水平位移减小,同时基坑中部内支撑轴力明显增大,角撑次之,边撑反而减小;邻近建筑物对平行于建筑物长边的支护桩桩身弯矩及反弯点影响较大,而对垂直于建筑物长边的支护桩桩身弯矩影响较小;局部内支撑破坏引起的坑外地面沉降较小,而内支撑连续破坏导致坑外地面产生显著沉降,影响范围为0.12~0.23倍开挖深度,同时临近的未失效支撑轴力显著增大,易引发连续破坏;邻近建筑物对平行于建筑物长边的支护桩桩身弯矩影响较大,对垂直于建筑物长边的支护桩桩身弯矩影响较小。当桩后砂土出现渗漏时,对平行于邻近建筑物长边的支护桩影响更为明显。     

Electrophoretic deposition of carbon nanotubes

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and characterisation of stable CNT suspensions, and the mechanism of the EPD process; it includes discussion of pure CNT coatings and CNT/nanoparticle composite films. A complete discussion of the EPD parameters is presented, including electrode materials, deposition time, electrode separation, deposition voltage and resultant electric field. The paper highlights potential applications of the resulting CNT and CNT/composite structures, in areas such as field emission devices, fuel cells, and supercapacitors.     

Effect of carbon fiber surface functional groups on the mechanical properties of carbon-carbon composites with HTT

The present investigation describes the quantitative measurement of surface functional groups present on commercially available different PAN based carbon fibers, their effect on the development of interface with resol-type phenol formaldehyde resin matrix and its effect on the physico-mechanical properties of carbon-carbon composites at various stages of heat treatment. An ESCA study of the carbon fibers has revealed that high strength (ST-3) carbon fibers possess almost 10% reactive functional groups as compared to 5.5 and 4.5% in case of intermediate modulus (IM-500) and high modulus (HM-45) carbon fibers, respectively. As a result, ST-3 carbon fibers are in a position to make strong interactions with phenolic resin matrix and HM-45 carbon fibers make weak interactions, while IM-500 carbon fibers make intermediate interactions. This observation is also confirmed from the pyrolysis data (volume shrinkage) of the composites. Bulk density and kerosene density more or less increase in all the composites with heat treatment up to 2600 °C. It is further observed that bulk density is minimum and kerosene density is maximum upon heat treatment at 2600 °C in case of ST-3 based composites compared to HM-45 and IM-500 composites. It has been found for the first time that the deflection temperature (temperature at which the properties of the material start to decrease or increase) of flexural strength as well as interlaminar shear strength is different for the three composites (A, B and C) and is determined by the severity of interactions established at the polymer stage. Above this temperature, flexural strength and interlaminar shear strength increase in all the composites up to 2600 °C. The maximum value of flexural strength at 2600 °C is obtained for HM-45 composites and that of ILSS for ST-3 composites.     

两亲性聚合物多孔微球的制备研究

合成了具有悬挂双键的苯乙烯-二乙烯基苯多孔微球,在悬挂双键处接枝甲基丙烯酸甲酯,制成了一系列不同接枝度的两亲性聚合物多孔微球。考察了悬挂双键数量、反应时间等因素对接枝率的影响以及接枝率对微球形貌的影响。实验中通过观测澄清点,有效地控制了反应后期自加速现象对接枝率的影响。在反应时间25 m in时,制得了平均孔径为50 nm的两亲性多孔微球。将该微球用于对化妆品活性组分的负载,对极性物的负载率比接枝前高出2倍。     

框架结构护岸新技术在城市河道中的应用

好溪堰河是贯穿浙江省丽水市主城区的一条千年古河道,在河道整治过程中,受制于河道周边的密集建筑物,传统的河道护岸技术均难以同时满足水利、市政、交通及景观的多元化要求。在分析其他创新河道护岸技术特点及存在问题的基础上,提出了适用于城市河道的桩柱式、框柱式两种框架结构护岸新技术,这两种护岸在维护河道周边建筑物稳定的同时,均具有不加深河床就可拓宽河道过流断面、不减少河岸用地、保持岸路畅通、改善水质及生态效果、提高亲水性等优点,在丽水好溪堰河水系整治工程中应用较为成功。     

Impact of “Super Acid” like filler on the properties of a PEGDME/LiClO4 system

Composite polymer electrolyte based on a new class of filler added to a PEGDME/LiClO₄ model system has been investigated. “Ceramic super acids” used consist of grafted SO₄²⁻ groups on Al₂O₃ particles surface obtained by calcinations route. Conductivity, DSC and FT-IR measurements performed on such composite electrolytes, when compared to the model PEGDME/LiClO₄ electrolyte, showed only slight improvement of their inner characteristics. In contrary, Li/Li symmetric cells study, by means of impedance spectroscopy, has presented a spectacular decrease of the interfacial resistance compare to the model electrolyte. This result opens a new pathway of investigation to master the lithium metal/polymer electrolyte interface.     

Garbage collection of multi-version indexed data on flash memory

Maintaining a multi-version index on flash memory could generate a lot of updates and invalid pages. It is important to have an efficient garbage collection mechanism to ensure the flash memory has sufficient number of free blocks for storing new data versions and their index structures. In this paper, we study the important performance issues in using the purging-range query to reclaim the blocks, which are storing old data versions and invalid index entries, to be free blocks. To reduce the cost for processing the purging-range query, we propose the physical block labeling (PBL) scheme to provide a better estimation on the purging version number to be used for purging old data versions. To further enhance the performance of the garbage collection process, and at the same time to maximize the deadspans of data versions and balance the wear levels of the blocks, we propose two schemes called, the sequential placement (SQ) and frequency-based placement (FBP), for placing new data versions into free pages. As illustrated in the performance studies, both SQ and FBP can effectively balance the wear levels of the blocks. The deadspans of data versions are longer under FBP than both SQ and RR, and the page reallocation cost is also lower under FBP especially when the size of flash memory allocated for the database is limited. The experimental results also illustrate that PBL can effectively minimize the number of invocations of the purging-range query to be one to reclaim the required number of blocks in each garbage collection.