索承式桥梁吊索钢丝腐蚀疲劳寿命评估

根据吊索镀锌钢丝腐蚀疲劳破坏特点,把镀锌钢丝腐蚀疲劳纹形成和扩展过程分解成镀锌层腐蚀失效、蚀坑萌生、蚀坑形成、短裂纹扩展、长裂纹扩展和断裂破坏等阶段,建立各阶段时间表达式,得到镀锌钢丝疲劳寿命表达式,提出基于断裂力学的吊索钢丝腐蚀疲劳寿命评估研究结果方法。通过算例分析复杂运营条件下腐蚀环境和应力幅等因素对吊索钢丝腐蚀疲劳寿命的影响,研究结果表明：吊索钢丝腐蚀疲劳寿命主要由钢丝镀锌层腐蚀、蚀坑发展和短裂纹扩展等3个阶段组成,为了准确地评估吊索腐蚀疲劳寿命,需要掌握大桥的运营环境和交通荷载。     

基于加权平滑l_0范数的单快拍波达方向估计

针对现有基于压缩感知的DOA估计算法估计精度不高的问题,提出一种基于加权平滑l0范数的单快拍DOA估计算法。所提算法采用一种新的加权方式,在构造一个恰当的平滑连续函数后,根据接收数据的初始解确定一个合适的递减的{σ}序列[σ_1,σ_2,?,σ_J],并对每一个σ值,用最速下降法来求解l0范数的逼近函数H_σ(S)的最小值;然后将该σ值作为下一次迭代的初始值,并在每次迭代开始时更新权值,通过多次的迭代获得逼近函数的最小解,即逼近的最小l0范数。通过仿真实验表明所提算法可对DOA进行有效估计,且容易实现、精度较高,与未加权的改进平滑l_0范数DOA估计方法相比具有更好的估计性能。     

U型65Mn钢板限位器扭转性能研究

通过对U型65Mn钢板限位器的扭转性能研究,推导其弹性扭转刚度及屈服荷载的理论计算公式,给出公式的适用范围.设计制作平直段长度L、宽度b、及钢板厚度t不同的40种限位器,进行静力加载试验.结果表明,限位器扭转位移主要由圆弧段扭转引起,钢板厚度t对限位器扭转刚度影响最大,增加板厚能够有效地增大刚度;板宽与刚度K近似呈一次正比关系;平直段长度越大,限位器扭转刚度越小.利用实验数据对理论公式进行修正,得到公式的修正系数.修正后的理论公式与实验数据吻合较好.     

作战任务协同过程形式化表达方法

为实现联合作战条件下诸军兵种和各作战层级对作战任务的一致理解,更好组织和实施作战协同,从本体属性、相互间关系和所属行动3个方面对作战任务进行了形式化表达。基于形式化表达,提出了一种作战协同过程描述方法,该方法能够促进各级指挥员形成一致理解,有利于作战行动的组织实施。最后以美军伊拉克战争中的"5个同时攻击"为例,对作战任务协同过程形式化表达方法进行说明,验证了该方法的可行性和合理性。     

Low capacitance and highly reliable blind through-silicon-vias (TSVs) with vacuum-assisted spin coating of polyimide dielectric liners

Low-k and high aspect ratio blind through-silicon-vias(TSVs) to be applied in "via-last/backside via" 3-D integration paradigm were fabricated with polyimide dielectric liners formed by vacuum-assisted spin coating technique. MIS trench capacitors with diameter of ~6 μm and depth of ~54 μm were successfully fabricated with polyimide insulator step coverage better than 30%. C-V characteristics and leakage current properties of the MIS trench capacitor were evaluated under thermal treatment. Experimental results show that, the minimum capacitance density is around 4.82 n F/cm~2, and the leakage current density after 30 cycles of thermal chock tests becomes stable and it is around 30 n A/cm2 under bias voltage of 20 V. It also shows that, the polyimide dielectric liner is with an excellent capability in constraining copper ion diffusion and mobile charges even under test temperature as high as 125°C. Finite element analysis results show that TSVs with polyimide dielectric liner are with lower risks in Si O_2 interlayer dielectric(ILD) fracture and interfacial delamination along dielectric-silicon interface, thus, higher thermo-mechanical reliability can be expected.     

新时期高职院校辅导员队伍建设现状调查与分析——基于4所高职院校的调查评估

通过对浙江省内4所高职院校的辅导员队伍建设现状进行实证研究,分析了当前高职院校辅导员队伍的工作现状和特点。分别从学校和辅导员自身的角度出发,尝试提出改进和完善高校辅导员队伍建设的对策和建议。     

PAC投加对絮体破碎后再絮凝特性和颗粒去除的影响

为改善絮体破碎后的再絮凝能力,提高颗粒的去除效率,以西宁地区低温低浊水为研究对象,通过光学检测仪器及数学拟合方式,分析补投聚合氯化铝(PAC)对破碎后絮体粒径与分布、生长速率变化的影响,描述颗粒及浊度的去除效果.结果表明:随PAC补投量的升高,絮体粒径和生长速率均先增大后减小,各自达到峰值所需补投药量分别为4和6 mg/L;剩余浊度和颗粒数先降低后升高,最低时可分别降至0.79 NTU、90个·m L-1.补投2 mg/L药剂后,280~630μm絮体颗粒体积分数由22.85%增大到46.36%,4~35μm絮体颗粒体积分数由1.21%减小至0.19%,再絮凝后絮体平均粒径为400μm,大于未破碎前的370μm,粒径增长率为8.11%,絮体生长速率为77.26μm/min.补投PAC可促进絮体破碎后的再絮凝,提高浊度及颗粒数的去除效果,可有效改善实际工程絮凝工艺效果.     

云南核桃（Juglans sigillata Dode）对流干燥传质模拟

在菲克定律与质量守恒定律的基础上建立了模拟云南核桃干燥过程的一维非稳态传质数学模型．通过边界条件的处理,结合云南核桃热风干燥试验,对其干燥过程中内部各层水分分布进行了模拟预测．将含水率的预测值与试验值对比可知该模型与试验数据吻合得很好,试验条件下云南核桃的有效水分扩散系数变化范围为1.14×10－9～1.73×10－9 m2／s．干燥初期云南核桃表层的含水率下降速度比内层快得多,之后内层含水率下降速度比表层要快,最终各层含水率稳步下降;从表层到中心,湿度梯度随着干燥时间的增加逐渐减小．分析表明在核桃的干燥过程中,外壳是影响水分扩散的主要阻力之一．该模型有助于云南核桃干燥过程传热传质耦合的研究以及复杂模型的建立．     

城市不透水面扩张对地表径流量的影响

城市不透水面的扩张对地表径流量有显著影响。以哈尔滨市松花江沿岸的6个中心城区为例,运用线性光谱分解技术和L-THIA模型,模拟小雨、中雨、大雨和暴雨4种日降雨量情景和枯、丰水年情境下,不同年份由于不透水面的扩张所引起的日径流量和年径流量变化。结果表明:日径流量在小雨情境下所受不透水面的影响最为明显,随着雨量增加,影响显著减小;年径流量在枯水年受不透水面扩张的影响大于丰水年。运用L-THIA模型模拟不透水面扩张导致的径流量变化,所需参数少,操作简单快捷,模拟结果可为城市的排涝减灾、规划管理等提供参考。     

Evaluation of apatite-coated chitosan microspheres for bone regeneration

The apatite-coated chitosan microspheres were fabricated by incubating chitosan in five times simulated body fluid. The apatite deposited on the microspheres was similar to natural bone mineral, as demonstrated by scanning electron microscopy, X-ray diffraction spectra and Fourier transformed-infrared spectroscopy analyses. Rat bone marrow-derived mesenchymal stem cells （BMSCs） were seeded on apatite- coated microspheres to investigate the effect of this scaffold on cell proliferation and differentiation. BMSCs seeded on uncoated microspheres were served as a control. In vivo experiment was evaluated by transplanting the microspheres loaded with or without BMSCs in 5-mm cranial defects of Wistar rats. Bone regeneration was investigated via micro-CT and histological analysis. It was found that apatite-coated chitosan microspheres could significantly promote the proliferation and alkaline phosphatase activity of BMSCs compared with uncoated microspheres. Histological slices and Micro-CT images at 8 weeks revealed much better regeneration of bone in the apatite-coated microspheres loaded with BMSCs than the control. In addition, the defect filled with pure microspheres induced little new bone formation. Our findings suggest that the apatite-coated chitosan microspheres scaffold is a promising carrier of stem cells for cranial bone tissue engineering.