对称荷载作用下半圆盘的应力分析

本文应用双极坐标系中的弹性力学相容方程,获得了受对称荷载作用且τξη=0情况下半圆盘的应力解答。运用所得公式,分析了预应力钢丝缠绕式压机中半圆盘形梁等实例。     

带工件相容约束的单机分批排序问题

The single machine parallel batch problem with job compatibility is considered to minimize makespan,where the job compatibility constraints are represented by a graph G.This problem is proved to be NP-hard.And when the graph G is limited to be a general bipartite,a complete bipartite and a complete m-partite graph,these problems are solved in polynomial time respectively.     

无限可分商品在线反向拍卖的风险策略研究

对网络环境下一个买家多个卖家的反向拍卖,研究了供应商在不同时间到达并投标而采购商接到每个投标后需要立即做出决策的在线反向拍卖的风险策略。对于无限可分商品,在资金一定前提下,首先对采购商无风险行为情形给出了基于标价上涨威胁的在线反向拍卖策略,通过竞争分析得到了其最优竞争比及整体需要曲线;其次引入采购商的风险容忍度概念,建立了激励相容在线反向拍卖的风险回报框架,并对风险忍耐策略进行了竞争分析。     

基于演化博弈论的装配式建筑创新激励政策研究

我国在推广装配式建筑过程中,一直面临构件制造、安装成本高,推广效果不理想等问题.运用演化博弈理论来研究政府激励和企业进行技术创新之间的关系,构建了政府和企业的演化博弈模型并进行数值仿真,发现在不同的初始比例下,政府激励政策的效果有显著差别.在数值分析的基础上,进一步讨论了补贴额度对双方策略选择的影响,并对政府的政策制定提供建议.     

Design of Serum Compatible Tetrary Complexes for Gene Delivery

A novel gene delivery system, called PoSC, consisting of PEI, PSP, and HA is described. In contrast to the DNA/PEI/HA ternary system whose transfection efficiency decreases significantly with increasing serum concentration, PoSC exhibits a high transfection efficiency of about 51 and 87% for NIH3T3 and HCT116 cells, respectively, at 50% serum concentration. Furthermore, PoSC shows no cytotoxic effect at its working concentration. The overall results suggest that HA adsorption on cationic complexes enhances the transfection efficiency, while PSP is essential for high transfection efficiency at higher serum concentration.

     

中国高考招生匹配市场中的算法设计及公平激励机制

用匹配博弈的方法,研究中国高考招生市场的算法设计及公平激励机制.基于高考招生程序,构建高考招生匹配算法,证明该算法的可行性.证明一个稳定匹配,可以由一个纳什均衡策略经高考招生算法生成,但反之不一定成立.证明一个稳定匹配一定是公平的,反之不一定成立.构建拒绝-接受算法,证明该算法是一个稳定的、策略防御的匹配机制,因而是一个公平的激励机制.     

基于辅助电介质层的棱镜表面等离子体共振效应研究

研究了一种基于棱镜基底-辅助电介质层-金膜-待测介质四层结构的表面等离子体共振(surface plasmon resonance,SPR)效应激励模型.采用薄膜光学与波导理论,探索了由辅助电介质层与金膜复合而成共振薄膜对SPR效应的激励机理与调制特性.借助时域有限差分方法,数值模拟得到辅助电介质层属性与共振能量传输特性关系.在此基础上,构建了波长调制型棱镜辅助电介质层结构SPR激励系统.研究结果表明,当待测介质折射率相同时,相较基于棱镜基底-金膜-待测介质三层结构的Kretschmann激励模型,辅助电介质层激励模型共振光谱整体向长波方向偏移且半波宽度出现显著展宽效应.而当待测介质折射率增大时,辅助电介质层型激励模型的共振光谱不仅会向长波方向偏移,而且折射率响应灵敏度比棱镜Kretschmann三层激励模型高出75%.因此该模型能够为诸如高灵敏度检测、新型光学滤波与调制器件设计等领域的研究应用提供理论与实践储备.     

贯通导体及其电路对金属腔体内部电磁场的影响

为研究贯通导体及其负载电路对金属腔体内部电磁场的影响,建立了不同贯通导体端接负载模型,使用电磁仿真软件CST进行仿真,利用GTEM室、矢量网络分析仪、功率放大器、ETS电场探头组建实验测试系统,验证了仿真结果的正确性,揭示了贯通导体及其电路对金属腔体内部电磁场的影响规律。研究结果表明:腔体内部电磁场同时受到贯通导体与腔体谐振的影响,在谐振频点干扰场强取得极大值,屏蔽效能取得极小值甚至为负值。贯通导体端接负载不接地与贯通导体两端开路情形相似,贯通导体端接负载直接接地时内部场显著降低,谐振频点降低,贯通导体端接负载浮点接地时内部场变化规律低频时与开路模型相似,高频时与直接接地模型相似。贯通导体端接负载的电阻值、电容值也会影响腔体的内部场。     

Preparation and Characterization of Two Types of Cyanate Ester-epoxy Resin Interpenetrating Network Matrix/Butadiene-acrylonitrile Rubber Composites

Two types of butadiene-acrylonitrile rubbers (i.e., carboxyl randomized butadiene-acrylonitrile rubber (CRBN) and hydroxyl terminated butadiene-acrylonitrile rubber (HTBN)) have been used for modifying an interpenetrating network of cyanate ester (CE)/epoxy resin (EP) (70/30). The toughness of the matrix can be improved effectively with addition of rubbers. The values of impact strength (11.6 KJ/m²) show a maximum for the CE/EP/HTBN (70/30/8) blend. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that CRBN and HTBN have a different dispersion state in the CE/EP matrix. CRBN aggregates to form regular spheres with a size of about 1 μm. HTBN disperse homogeneously with its size of the nano-level (about 10 nm). Fourier transform infrared spectrum (FTIR) and differential scanning calorimetric (DSC) analysis shows that the CRBN has higher reactivity than HTBN. The thermal gravimetric analysis (TGA) results shows that T ₁₀ (temperature of 10% weight loss) of the CE/EP system decreases with the addition of rubbers. For the CE/EP/CRBN system, both T ₃₀ (temperature of 30% weight loss) and T ₅₀ (temperature of 50% weight loss) are lower than neat CE/EP. However, for the CE/EP/HTBN system, both T ₃₀ and T ₅₀ are near to neat CE/EP. Different reactivity and compatibility between the rubbers and CE/EP matrix is the main determining factor for the thermal stability of the blends.     

Preparation and Compatibility of EVM/TPU Blend

The preparation of EVM (ethylene‐vinyl acetate copolymer rubber)/TPU (thermoplastic polyurethane) blends with various ratios and their compatibility were investigated. The influence of mixing technology, filler type and content, the VA content in EVM (40 and 70 wt.%) and the addition of compatibilizers on the mechanical properties and the compatibility of the EVM/TPU blends were systematically studied.

The test results showed that in preparation of the blend, fillers should be added to the blend to improve the processability and that among the fillers used, silica showed the best reinforcing effect on the blends. The best parameters for blending EVM and TPU in a HAAKE rheometer was: mixing temperature 160°C, rotor speed 45 rpm and mixing time 15 min. The test results also showed that the compatibility of EVM 700 (VA=70%) with TPU was better than that of EVM400 (VA=40%). The addition of a compatibilizer EVM‐g‐MAH and EVM‐g‐FME improved the processability of the blends. The addition of EVM‐g‐MAH also improved the compatibility of EVM 700/TPU blend; both the mechanical properties and hot‐air aging properties of the blends were improved. However, the addition of EVM‐g‐FME did not improve the compatibility of EVM/TPU blends.