Water consumption of the early-age paste and the determination of “time-zero” of self-desiccation shrinkage

Self-desiccation shrinkage (SDS) is closely related to the interior water consumption and the relative humidity (IRH) drop in the cement paste. Substantial self-desiccation shrinkage has been observed at very early-age for high performance concrete. However, it is difficult to investigate the IRH by conventional method of hygrometer at this time because the materials are still in the superhygroscopic range. In this paper, an automatically measuring system of meniscus depression is developed on the base of the mechanism of tensiometer and Laplace formula. The interior water consumption and the IRH changing within the paste could be automatically monitored at the very early-age (here specially refers to the stage from the beginning of casting till several hours after final setting). By using this system, the effects of water to binder ratio and replacement of cement by fly ash and ground granulated blast furnace slag on the self-desiccation were investigated for the very early-age cement paste. Experimental results could potentially explain the mechanism of the SDS at very early-age as well as determine the “time-zero” of SDS corresponding to its definition.     

Separation of particles from hot gases using metallic foams

One of the most complicated tasks in the field of hot gas cleaning is the removal of particles from a complex mixture of degradation products formed during thermal treatment. A robust and completely reliable technology is still to be developed to achieve high efficiencies. In the past few years, significant improvements have been brought to gas cleaning technologies. Nevertheless, none of the existing processes has proved fully successful.The aim of this work is to perform the filtration of particles generated in fluidized bed gasification experiments using metallic foams. The gasified material used is dried sewage sludge. Nickel–chromium metallic foams are likely to have inherent properties that would make them suitable for use in structures where strength, high temperature-resistance and corrosion resistance are required. Moreover, metallic foams are characterized structurally by their cell topology, relative density, high porosity (? = 0.95) and cell size. In hot gas filtration, high temperature-resistance and low pressure drop to specific area ratio are essential characteristics. In the present work, several experimental operating conditions (heating time, temperature, washing method and metallic foam thickness) are investigated. The pressure drops in the metallic foams during filtration are calculated. The experimental results obtained are compared with numerical simulation results and a good agreement is obtained. The metallic foams are simulated from tomography results and a model is created.     

Segment-based coding of color images

Based on the idea of second generation image coding, a novel scheme for coding still images is presented. At first, an image was partitioned with a pulse-coupled neural network; and then an improved chain code and the 2D discrete cosine transform was adopted to encode the shape and the color of its edges respectively. To code its smooth and texture regions, an improved zero-trees strategy based on the 2nd generation wavelet was chosen. After that, the zero-tree chart was selected to rearrange quantified coefficients. And finally some regulations were given according to psychology of various users. Experiments under noiseless channels demonstrate that the proposed method performs better than those of the current one, such as JPEG, CMP, EZW and JPEG2000. Supported by the Senior University Technology Innovation Essential Project Cultivation Fund Project (Grant No. 706028) and the Natural Science Fund of Jiangsu Province (Grant No. BK2007103)     

Electrical properties of different types of carbon fiber reinforced plastics (CFRPs) and hybrid CFRPs

The electrical resistance (ER)–time, current–voltage and ER–temperature behaviors of carbon fiber reinforced plastics (CFRPs) reinforced with high strength (HS), medium modulus (MM), and high modulus (HM) carbon fibers were studied. At the same time, the electrical properties of hybrid CFRPs (HCFRPs) reinforced with more than one type of carbon fibers were also studied. It was shown that the value of the current influences the electrical stability and the ER measurement accuracy. In order to obtain an accurate ER measurement, the current should be larger than 1.5 mA. All the CFRPs and HCFRPs are characterized by linear current–voltage and Ohmic behaviors. A negative temperature coefficient (NTC) behavior is exhibited for all types of specimens. The NTCs of the CFRPs reinforced with HS, MM and HM carbon fibers are 0.038, 0.033 and 0.094, respectively. For the specimens of HCFRPs containing HM carbon fibers, the NTC becomes larger with increasing the volume fraction of HM carbon fibers. The good linear and reversible relationship between the change in ER and temperature indicates that the CFRPs and HCFRPs may be used as temperature sensors.     

甲氧基吲哚-3-甲醛-(4''''-硝基)苯腙的合成

报道了标题化合物的合成方法.甲氧基吲哚-3-甲醛和4-硝基苯肼进行缩合反应得到系列苯腙产物,其结构经IR、1HNMR、MS和元素分析得到确证,纯度＞99.0%.     

泡沫铝/聚氨酯复合材料摩擦阻尼器性能试验研究

基于泡沫铝/聚氨酯复合材料（aluminum foam/polyurethane,简称AF/PU）是一种同时具有铝材料的摩擦性能和聚氨酯的黏弹性的复合材料,由此研制出一种能够发挥黏弹性阻尼器和摩擦阻尼器各自耗能特点的泡沫铝/聚氨酯复合材料摩擦阻尼器（AF/PU摩擦阻尼器）,并对该阻尼器进行位移幅值、频率等相关性的性能试验和疲劳性能试验。以最大输出力、刚度和阻尼比为指标,研究该阻尼器的性能规律,采用修正的Bouc-Wen计算模型模拟其滞回曲线,并对比模拟结果和试验结果。研究结果表明：AF/PU摩擦阻尼器的滞回曲线饱满,具有较高且稳定的阻尼比。该阻尼器的力学性能随位移幅值和循环次数的增加而呈现分阶段性,但是加载频率的影响却较小,该阻尼器是一种典型位移幅值相关的变刚度摩擦阻尼器。修正的Bouc-Wen模型的模拟结果与试验结果二者吻合良好。     

新型混合装配式混凝土剪力墙抗震性能试验研究及有限元分析

预应力筋面积、预应力筋张拉应力、浆锚钢筋无黏结长度及轴压比是新型混合装配式混凝土剪力墙的重要设计参数。在前期试验基础上,开展考虑不同预应力筋面积的新型混合装配式混凝土剪力墙低周反复荷载试验,并采用Abaqus进行有限元参数分析。试验结果表明：相较现浇对比试件,新型混合装配式剪力墙试件抗裂性能、承载力、刚度均明显提高,位移延性性能及耗能能力接近,在预拉力不变的条件下,预应力筋面积变化对试件性能影响较小;有限元参数分析结果表明,预应力筋张拉应力与轴压比的变化将明显影响新型混合装配式混凝土剪力墙的强度与刚度,且均呈正相关关系,而预应力筋面积、浆锚钢筋无黏结长度影响则不够明显。综合分析认为,对于试验涉及的新型混合装配式混凝土剪力墙,建议预应力筋根数取3根,初始张拉力宜为416.6kN,浆锚钢筋无黏结长度宜为150mm。     

污染场地测试评价与处理技术

针对中国工业污染场地开发利用的岩土工程关键问题,全面总结了笔者及其课题组多年来的研究成果。主要包括5个方面:(1)污染场地土体工程性质变化基本规律和污染场地分类评价方法,阐明了重金属污染土和有机污染土的基本物理力学特性,在总结国内外已有污染场地风险评价和工程分类的基础上,提出了基于层次分析原理的污染场地指数分类法;(2)基于多功能孔压静力触探(CPTU)的污染场地原位测试方法,包括污染土的电阻率基本特征,基于电阻率CPTU的污染场地原位测试方法,基于CPTU的污染场地水力传导参数测试评价方法;(3)重金属污染场地固化/稳定化处理技术,揭示了重金属污染土固化/稳定化机理,阐明了水泥系固化剂固化/稳定重金属污染土的有效性与不足,提出了磷酸盐系固化剂和碱激发矿渣固化剂固化/稳定高浓度重金属污染土的方法,从工程与环境安全二方面提出了固化/稳定法的施工工艺;(4)有机污染场地曝气法处理技术,采用研发的一维二维曝气模拟装置,揭示了曝气法修复有机污染场地的气相运动规律、修复机理与效果,建立了基于集总参数的污染物去除效果评价方法,提出了曝气法工艺设计方法;(5)污染场地竖向隔离技术,提出了土–膨润土系竖向隔离墙材料设计关键参数确定方法,揭示了土–膨润土系竖向隔离墙的长期防渗防污性能和化学相容性特征,比较了隔离施工技术的特点,对SMC工法的效果进行了分析评价。研究成果对中国污染场地再开发利用和城市可持续发展具有重要意义。     

隧道岩溶管道型突涌水动态演化特征及涌水量综合预测

建立了隧道岩溶管道型突涌水模型,进行了突涌水过程中动态演化特征分析,结果表明揭露岩溶管道型突涌水的动态演化无明显的时间效应,但空间特征呈现阶段演化的规律,突涌水区域可分为三种典型流速演化区域:管道内部的近似高速稳定区,隧道与岩溶管道临界面附近的流速升高区以及隧道内部灾害水体的衰减–低速稳定区。基于管道内部区域流速动态衰减规律,提出了基于数值分析法和极限(离散)解析法的涌水量综合预测方法,形成揭露岩溶管道型突涌水的涌水量预测体系,并设计了相应的模型试验,进行了涌水量的实时监测,监测结果验证了涌水量综合预测方法的合理性。     

不同直径盾构隧道地层损失率的对比研究

地层损失率是引起地面沉降最主要的因素之一。因此,收集了国内盾构隧道地面最大沉降实测数据,利用Peck公式反推得到地层损失率的取值,研究大直径(D10m)与中小直径盾构隧道地层损失率的分布规律及主要影响因素。结果表明:(1)中小直径、大直径盾构隧道施工引起的地层损失率分别有93.19%在0%～2.0%、近70%在0%～0.5%之间,大直径盾构隧道施工引起的地层损失率数值更小,分布更集中;(2)中小直径、大直径盾构隧道引起的地层损失率分别随着地层条件变好、地层渗透性的变小而减小;(3)两种直径盾构隧道的地面最大沉降与地层损失率均具有一定的线性相关性;(4)隧道覆土深度比与地层损失率的相关性较弱;(5)中小直径盾构隧道引起的地层损失率随着地层黏聚力、内摩擦角以及弹性模量的增大而逐渐减小。研究成果可为今后相关地区类似隧道工程施工诱发的地面沉降预测和施工控制提供科学参考。