Electrical resistance behavior of vinylester composites filled with glass-carbon hybrid fibers

Vinylester (bismethacryloxy derivative of a bisphenol-A type EP resin, VE) composites with glass-carbon hybrid fibers (CF-GF) weight fraction of 50%, were prepared by the compress molding method. The distribution of carbon fiber in the hybrids was observed by stereomicroscope. The electrical resistance behavior of the composites filled with different carbon fiber (CF) weight contents (0.5% to 20%) was studied. The experimental results show that the electrical resistance behaviors of CF-GF/VE composites are different with those of CF/VE composites because carbon fibers’ conducting networks are broken by the glass fibers in the CF-GF/VE composites. The carbon fibers distribute uniformly in the networks of glass fibers (GF) like single silk and form the semi-continuous conducting networks. Composite filled with GF-CF hybrid has a higher percolation threshold than that filled with pure CF. At that time, the resistivity of CF-GF/VE composites varies little with the temperature increasing. The temperature coefficient of resistivity in GF-CF/VE composite is less than 317 ppm and the variation of the resistivity after ten thermal cycles from 20 °C to 240 °C is less than 1.96%. Funded by the Natural Science Foundation of Hubei Province (No. 2007ABA028)     

提高混合实时任务确定性的两级调度算法

为提高混合实时任务的确定性,提出了一种两级调度算法。先给出了调度算法的架构,通过增加一个调度模块实现周期性实时任务调度,非周期性实时任务则由系统内核调度。然后建立了任务模型,并对调度算法、任务集可调度性和抖动等进行深入研究。将提出的调度算法应用到基于Windows CE.NET的液压机控制系统中,分析了控制系统的硬件平台和任务划分。最后对调度算法进行验证,结果表明,该算法能保证混合实时任务的确定性,减小抖动,从而提高控制系统的精度。     

有机染料在SiO_2凝胶玻璃基质中的荧光谱线位移机制

研究探明了有机染料的荧光发射波长的位移机制 .R6G和 RB染料随掺杂浓度的提高而出现的谱线红移是由于二聚物的形成导致的 ,而凝胶玻璃中 C12 0染料的红移是由溶剂效应引起的 .同时 ,Si O2凝胶玻璃中 RB的谱线红移也可能由酯化反应所导致 ,这种红移在热处理至 3 0 0℃时可由 RB的内酯化产物形成而降低     

混合动力客车的排放污染物测量及分析

参考国内外现有的车辆排放污染物测量方法,在整车试验转鼓上使用车载尾气排放仪,在国内首次对混合动力客车和传统客车进行排放对比测量试验,验证了混合动力客车可以减少车辆污染物排放,并取得了一些大型车辆排放污染物的测量经验。     

Flexural Fatigue Behavior of Layered Hybrid Fiber Reinforced Concrete

In order to obtain the fatigue life of layered hybrid fiber reinforced concrete （LHFRC） at different stress levels, flexural fatigue tests were carried out on specimens. The relation between fatigue lives and stress levels was simulated using the two-parameter Weibull distribution. Furthermore, both single- logarithmic and double-logarithmic regressive equations of various reliabilities were derived. It is evident that LHFRC gets the advantage of longer fatigue life over common concrete.     

Hydrothermal Synthesis and Characterization of a Novel Organic Inorganic Hybrid Compound [Co(dien)_2](dienH_3)(H_3O)_7[P_2Mo_5O_(23)]_2·14H_2O

A new compound,[Co(dien)2](dienH3)(H3O)7[P2Mo5O23]2·14H2O, has been hydrothermallly synthesized by using Na2MoO4,CoCl2, H3PO4 and dien, and structurally characterized by elemental analysis, X-ray powder diffraction analysis, SEM, IR and TG analysis. The results show that the compound is composed of a polyanion [P2Mo5O23]212- , complex [Co(dien)2]2 cation, protonated [dienH3]3 , and forteen crystallization water molecule.     

自适应ARQ系统中基于跨层设计的优化方法

针对IEEE 802.16e系统中的混合自动重传请求（HARQ）协议,将数据链路层的子包传输机制与物理层的自适应调制编码技术（AMC）有效地结合,提出一种基于跨层设计的自适应参数优化选择方法,该方法以最大化系统吞吐量为目的,研究了HARQ子包数目和调制编码方式的联合最优解.同时,还给出了考虑链路层HARQ协议的AMC切换门限准则.仿真结果表明,该参数优化方案能够更好地匹配信道的时变特性,在增加少量复杂度为代价的前提下,实现了系统吞吐量的进一步提高.     

核芯筒厚度对钢-混凝土混合结构抗震性能的影响

目的为了分析核芯筒厚度对结构抗震性能的影响.方法利用同济大学MTS多高层钢结构设计系统,根据钢-混凝土混合结构抗震概念设计原理,采用沈阳地区经济效益较好的住宅平面布置形式,建立H型钢框架-混凝土核芯筒多层住宅结构模型,并计算模型在四类场地土和设防烈度为七、八、九度时的最大层间位移及顶部最大位移.结果绘出了模型的最大层间位移及顶部最大位移随核芯筒厚度变化的曲线.结论提出了混合结构的高宽比最好不大于相应混凝土结构的高宽比限值;最大层间位移和顶部最大位移在小震作用的弹性阶段取混凝土结构的限值等建议.得出了在七度区和八度区一类场地土条件下,合理布置混凝土核芯筒可以充分发挥其抗侧刚度,能够很好地控制结构的位移和变形等结论.     

一种新的交叉粒子群算法

针对标准粒子群优化算法（SPSO）在处理高维复杂问题极易陷入局部最优的不足,文章在研究标准粒子群优化算法理论基础上,提出了一种带交叉因子的改进粒子群优化算法（MyPSO）,减小了算法陷入局部极值的可能。仿真实验表明,该算法（MyPSO）提高了全局搜索能力,但同时增加了搜索时间。     

混合钢梁及其极限承载力研究

为全面了解混合钢梁的力学性能,作者采用数值分析的方法,研究了混合钢梁的受力过程、抗弯和抗剪极限承载力;分析了腹板屈服强度的影响,得到合理的腹板、翼缘板屈服强度比;推导出弹塑性变形计算公式;用量纲为一的坐标系统分析弯扭屈曲临界弯矩,确定了弹塑性区段的回归方程和起终点相对长细比界限值,解决了混合钢梁弯扭屈曲的计算问题;指出混合钢梁腹板抗剪利用屈曲后强度的可行性,对比了试验资料与现行各抗剪算法,推荐采用AASHTO 2004方法计算抗剪承载力,并对AASHTO 2004端腹板段抗剪计算提出了考虑腹板宽高比影响的修正计算式;通过有限元数值分析,提出了适用于混合钢梁的计入弯矩影响的剪力计算式.基本解决了混合钢梁设计中涉及的计算问题.