Crossover Behavior of Linear and Star Polymers in Good Solvents

Monte Carlo simulation calculations for the mean-square end-to-end distance and second virial coefficient for model linear and star polymers composed of hard spheres with square-well attractions are presented. For these polymers, two types of crossover behavior are observed: (i) crossover from the Gaussian chain to the Kuhnian chain limits and (ii) crossover from the semiflexible chain to the Kuhnian chain limits. A crossover theory for the properties of dilute linear and star polymers under good solvent conditions is presented. This model directly relates the properties of the monomer–monomer interaction to the renormalized parameters of the theory. The predictions of the crossover theory are in good agreement with simulation data. A new equation of state for linear and star polymers in good solvents is presented. The equation of state captures the scaling behavior of polymer solutions in the dilute/semidilute regimes and also performs well in the concentrated regimes, where the details of the monomer–monomer interactions become important. This theory is compared to Monte Carlo simulation data for the volumetric behavior of tangent hard-sphere polymers.     

脲酶抑制剂nBPT对土壤脲酶活性和脲酶产生菌的影响

研究了脲酶抑制剂nBPT对土壤中脲酶活性和细菌、放线菌生长及发酵产酶的影响.结果表明,nBPT用量在0.1%～0.5%之间对土壤脲酶活性影响较小;当浓度达到1%时,抑制作用最为显著.低浓度（0.1 mg/mL）nBPT对细菌、放线菌生长有一定的促进作用;中等浓度和高浓度处理对其生长则表现出抑制作用,且随着nBPT浓度增大而增强.nBPT对细菌、放线菌发酵产酶有明显的抑制作用,最大抑制率分别达55.4%和67.1%.     

大鼠脑海马结构认知机理及其在机器人导航中的应用

为了构建具有类似于人和动物环境认知机理的移动机器人,详细介绍了海马解剖学结构、信息传递回路、环境认知相关细胞空间放电认知机理.将鼠脑海马结构认知机理应用在机器人平台上,并通过介绍一种典型仿鼠脑海马结构认知机理的机器人导航模型来阐述大鼠脑海马结构在机器人导航中的应用.结果表明:机器人进入某一环境时能够自主地探索其所处空间环境,经过不断的探索,最终形成其对所处环境的表征,即成功构建所处空间环境的认知地图,根据认知地图实现机器人在复杂环境中面向目标对象的导航任务.     

高岭土ASP200在轿车胎白胎侧中的应用

通过马尔文激光粒度分析、填料基本配方小配合试验、白胎侧大配合试验及硫化胶物理性能检测,对进口高岭土ASP200和普通高岭土进行对比。结果表明,高岭土ASP200粒径更细,粒径分布更窄;同时ASP200补强性能明显优于普通高岭土,且ASP200在白胎侧配方中具有更好的耐黄性,更适合应用在轿车白胎侧配方中。     

基于EKF的永磁同步电机的无传感器控制研究

基于位置传感器永磁同步电机控制,一方面提高了设计成本,另一方面降低了系统可靠性。对扩展卡尔曼滤波（extended Kalman filter,EKF）原理进行分析研究,将 EKF 优化算法应用到永磁同步电机控制中,对永磁同步电机转子转速、转子位置进行预测估计。最后,基于MATLAB仿真平台,构建扩展卡尔曼滤波( EKF)仿真模型。仿真结果表明,永磁同步电机转子位置、转子转速能够被准确预测估计,表明了基于扩展卡尔曼滤波( EKF)算法仿真模型是有效的,为永磁同步电机控制系统研究提供了坚实理论基础。     

Addition of GeO2 to Reduce the Viscosity of Parent Glasses for Low-Expansion, Transparent Glass–Ceramics Containing High-Quartz Solid Solutions

Parent glasses for fabricating glass–ceramics with nanometer-sized crystals usually have high viscosities, resulting in high processing temperatures. In this study, GeO₂ was added to a transparent, near-zero thermal-expansion Li₂O–Al₂O₃–SiO₂ glass–ceramic to reduce the viscosity of the parent glass. The effects of this compositional modification on the viscosity and crystal-nucleation rate of the parent glasses, and on the crystal size, thermal expansion, and optical transparency of the resulting glass–ceramics were investigated. It was found that addition of GeO₂ was useful in reducing the glass viscosity. Owing to the reduced nucleating rate with the increase in the GeO₂ content, the nucleating times required for reaching the smallest crystal size, the lowest coefficient of thermal expansion, and the highest transparency were all increased. With increasing GeO₂ content, the lowest coefficient of thermal expansion that can be reached for glass–ceramics increased (0.14–2.9 × 10⁻⁶ K⁻¹). The highest transparency of the GeO₂-containing glass–ceramics is almost as good as that of the GeO₂-free glass–ceramic and is almost independent of GeO₂ content when the crystal size is smaller than about 65 nm.     

N-{5-[1-(间氯苯氧)乙基]-1,3,4-噻二唑-2-基}-N''''-芳酰基脲的合成及生物活性

设计合成了12个未见文献报道的含取代1，3，4-噻二唑的芳甲酰基脲类化合物，所有化合物的结构经IR、^1HNMR和元素分析确证。初步生物测试结果表明，部分化合物具有较好的植物生长调节活性。     

地下矿山两相邻矿体开采扰动关系与协同步距分析

对于金属矿床地下开采的两相邻矿体，从根本上弄清两相邻矿体之间的开采扰动关系与回采步距，对于实现矿产资源优化开采与地压安全管理具有重要意义。以往研究主要关注于开采顺序对围岩应力分布状态产生的影响，未从理论上对两相邻矿体间的扰动关系进行详细分析。基于协同开采理念，分析了不同倾角和不同矿层间距条件下两相邻矿体的开采扰动关系，给出了相应的协同步距计算公式，并结合山东会宝岭铁矿两急倾斜相邻矿体和云南斗南锰矿两缓倾斜相邻矿体开展了工程案例分析。研究表明：①水平-缓倾斜两相邻矿体仅存在下层矿体回采对上层矿体扰动关系1种类型，倾斜-急倾斜两相邻矿体存在无扰动关系、单一矿体扰动关系和两矿体相互扰动关系3种类型；②相应的协同步距计算公式由开采方式与矿体相关参数综合决定；③会宝岭铁矿的两急倾斜相邻矿体宜同步回采，云南斗南锰矿两缓倾斜相邻矿体的V8矿层应超前V7a矿层2个矿块回采。研究成果可为地下矿山两相邻矿体安全、高效、绿色、协同开采提供参考。     

High molecular weight polyethylene nanospheres: synthesis, physical and mechanical properties--second harmonic generation

The weak second harmonic light generating from carbon nanotubes are detected. The signal intensity closely related to the density of pi-bonds attributed to the defects in the rolled graphene sheets, which is stimulated to have anharmonic oscillation as strongly affected by the environment. The intensities of SHG are diminished in order of well-aligned multi-wall carbon nanotubes (MWCNTs), randomly-aligned MWCNTs, and then to single-wall CNTs.     

山区避雷针保护范围的简化计算及作图

在山坡地区 ,避雷针保护范围计算及作图可应用避雷针保护直接作图法。根据被保护物的高度和其占地面积的大小 ,查表可选择出避雷针的高度和个数 ,并可进行两方案比较 ,然后直接做出防雷保护范围图。一般情况下 ,可以不再进行保护范围的繁琐计算