Theoretical and Experimental Analysis of Bending Behavior of Composite Beam with Notched Web

A new kind of steel-concrete composite beam with notched web is proposed, and the bend and shear behaviors of this composite beam are investigated. First of all, the constitution, bearing characteristics and merits of the steel-concrete composite beam with notched web are introduced; then, a group of formulas about the bending capacity, slip between the steel beam and the concrete flange, and the deflection are introduced; after that, the bending behavior, slip effect and bearing characteristic of the steel-concrete composite beam with notched web are studied on 4 specimens, which are tested by applying two concreted vertical loads on the top of concrete flange. And the finite element model is adopted to analyze the results of the 4 specimens; finally, the reliabilities of the formulas are verified by comparing the results of theoretical formulas, the results of tests and that of finite element analysis. Study shows that the bend behavior and shear behavior are fine, and the popularization of this new kind of composite beam which can be broadly used in building engineering will save the consumption of steel.     

Analysis of Inverted Asphalt Pavement Structure Based on Cross -Anisotropy

Based on the established cross-anisotropic layered elastic theory,the effect of inverted asphalt pavement structure by granular cross-anisotropy is analyzed.The result shows that,with the decrease of granular horizontal elastic modulus,the pavement surface deflection and tensile strain at bottom of AC are increased,but the tensile stress at bottom of semi-rigid base and compressive strain at top of subgrade are decreased.The thickness of AC has significant effect on the pavement surface deflection,tensile strain at bottom of AC and compressive strain at top of subgrade,while the granular cross-anisotropy has little effect on the critical inverted pavement responses for the thicker AC.     

积分方法用于校定逆转型土壤盐渍剖面的磁感式电导

Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity （ECa） and soil electrical conductivity of a saturated soil paste extract （ECe） or a 1：5 soil water extract （EC1：5） using an electromagnetic induction instrument （EM38）. The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1：5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1：5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1：5 continuously with depth.     

斜拉倒虹吸跨径及桥型选择

针对在又宽又深、冲刷严重、环境及气候恶劣的内陆河流上修建跨河输水建筑物存在许多技术难题，提出了多种可供选择的跨径和桥型，指出方案选定中着重考虑的因素，并作了深入细致的分析探讨。特别强调了结构的受力特征和抗风、抗冲刷能力及防洪安全。     

南水北调倒虹弯管局部阻力设计方法研究

首先论述了倒虹弯管局部阻力产生的机理 ,其次对弯管局部阻力进行了深入系统的分析和试验研究 ,最后得出如下结论 :对于缓弯管 ,以 R/ D=2为宜 ;在弯转角不大时折弯局部水头损失并不比缓弯大 ,并通过模型试验对这一结论进行了验证。结论对南水北调中线工程和平原地区的低水头大流量倒虹工程弯管设计具有重要的应用价值。     

压缩空气泡沫产生系统及泡沫流变学性能的实验研究(英文)

该文介绍了一种压缩式空气泡沫灭火系统 ,该系统将压缩空气通入到有压混合液中 ,产生尺寸均匀 ,出口动量大的泡沫 .结果表明 ,泡沫的粘性、润湿性均显著提高 .试验采用了一种特殊设计的钟摆式测试装置 ,证明了泡沫屈服应力的存在 ,试验结果显示屈服应力随气体百分比和泡沫尺寸的提高而增大     

Impact of moisture content on dynamic mechanical properties and transition temperatures of wood

The dynamic shear modulus and the loss modulus of Betula alba, Ulmus parvifolia, Quercus robur, Acer platanoides, Tilia cordata, Fraxinus excelsior and Pinus sylvestris wood were measured using an inverted torsion pendulum within a wide temperature range. The glass transition temperature of the lignin–carbohydrate complex and the decomposition temperature of the wood cellulose were estimated. The temperature band from 170°C to 240°С shows the transition of the lignin–cellulose complex from the glassy to the rubbery state. Mechanical properties of different types of wood are affected by moisture and anatomical differences, but glass transition and decomposition temperatures are the same. More than 5% of moisture in the wood stored at normal conditions were found. After drying, the increase of dynamic shear modulus of wood over the entire region of the glassy state was observed. The intensity of maximum peak of dynamic loss modulus is also increased due to activation of the segmental motion of macromolecules of the ligno-carbon complex. The decomposition temperature of the cellulose crystallites was unchanged for specimens containing moisture and for dried specimens.     

小麦叶片逆向衰老过程中叶绿素含量及光合特性的变化

【目的】研究小麦叶片逆向衰老过程中旗叶和倒二叶叶绿素含量、净光合速率、蒸腾速率和气孔导度的变化规律,为进一步揭示叶片逆向衰老的生理机制提供研究思路和理论指导。【方法】以逆向衰老小麦‘温麦19’和‘兰考矮早8’为试验材料,在小麦扬花后6,12,18,24,30和36d,分别采用CCM-200手持式叶绿素仪和LI-6400XT型便携式光合测定系统,在田间测定旗叶和倒二叶的叶绿素含量、净光合速率、蒸腾速率和气孔导度。【结果】‘温麦19’和‘兰考矮早8’在灌浆结实后期(花后18～36d)均出现倒二叶叶绿素含量高于旗叶的现象,即叶片逆向衰老的现象;‘温麦19’较‘兰考矮早8’叶片逆向衰老现象出现早。在灌浆后期,‘温麦19’旗叶的光合速率、蒸腾速率和气孔导度均低于倒二叶,而‘兰考矮早8’旗叶的光合速率低于倒二叶,蒸腾速率和气孔导度仍高于倒二叶。【结论】在逆向衰老过程中,随着小麦旗叶和倒二叶叶绿素含量的变化,其净光合速率、蒸腾速率和气孔导度也发生相应的变化,且品种之间存在较大差异。     

MEMS固体化学微推进阵列的微冲量测试技术

为了评价MEMS(Micro Electro Mechanical Systems)固体化学微推进阵列的推进性能,对其单元微冲量的精确测试显得尤为重要。在传统冲击摆的基础上,考虑微推进器推力和燃气射流冲击力之间的比例关系,设计了一套适用于MEMS固体化学微推进阵列单元微冲量的间接测试装置,并成功用于6×6规格(单元集成度为36个/cm²)微推进阵列的实际测试中。结果表明:典型实验数据下的待测微冲量为2.5442×10-4Ns,相对误差小于5%;实测8个单元的微冲量平均值为2.5574×10-4 N·s,相对偏差较小,具有很好的重复性。 