重庆市稻飞虱、稻纵卷叶螟2009年重发生的特点及原因

2009年重庆市"两迁"害虫大发生,其中稻飞虱发生面积是1950年以来的第3个大发生年;稻纵卷叶螟发生面积是1950年以来的历史最高水平.该文总结了重庆市2009年"两迁"害虫发生特点,并分析了其发生原因.     

基于Simscape的塑料-钢螺旋蜗轮蜗杆稳态热分析

为了获得塑料-钢材料的螺旋齿蜗轮蜗杆啮合过程中的热量分布,根据热网络分布原理,利用Simscape仿真软件建立了热网络模型,分析了其啮合时的功率损失,得出其热阻计算模型和系统的稳态温度分布及热流量分布。仿真结果表明,蜗杆的温度远远高于其他节点温度,齿轮主要以蜗杆热传导的方式散热,通过选择热传导系数更大的蜗杆材料或采用减小蜗杆长度的设计可以改善蜗杆端传导散热。     

Development of a shape‐controlled H2S delivery system using epoxide‐functional nanoparticles

Hydrogen sulfide (H₂S), an endogenous modulator of signaling processes, has potential as a therapeutic drug or in combination drug therapies. Due to its broad biological impacts and malodorous nature, there is considerable interest in vehicles capable of delivering H₂S in a controlled manner. Herein, we report postpolymerization modification of polymers incorporating glycidyl methacrylate (GMA) units to form thiol‐triggered macromolecular H₂S donors. By combining this approach with polymerization‐induced self‐assembly, this methodology allows the facile preparation of polymeric nanoparticulate donors with either spherical or worm‐like morphology. The thiol‐reactive epoxide functional groups in poly(GMA) were chemically transformed into acyl‐protected perthiol groups using a three‐step procedure throughout which both morphologies remained intact. The H₂S releasing properties were subsequently studied, with both spherical and worm‐like nanoparticulate donors shown to successfully release H₂S in the presence of the model thiol, l ‐cysteine. In addition, the donor polymers were shown to effectively increase H₂S inside cells, upon exposure to biologically relevant endogenous thiol levels. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1982–1993     

Advancing the computational methodology of rigid rod and semiflexible polymer systems: A new solution to the wormlike chain model with rod‐coil copolymer calculations

A wormlike chain model for rod type blocks in a rod‐coil diblock copolymer is implemented in the self‐consistent field theory (SCFT) formalism. A pseudo‐spectral method is used to solve for the single‐chain partition function of this copolymer system. Orientation degrees of freedom are discretized using Lebedev sphere rules such that orientation integrations are carried out through a Lebedev quadrature, an approach not used previously in tandem with the pseudo‐spectral method. Phase behavior in the rigid‐rod limit as a function of rod segment volume fraction, Flory–Huggins interaction parameter χ , degree of polymerization N , and rod contour length ratio β are examined in detail in one and two dimensions. Examples extending to three dimensions are included. Semiflexible behavior via the rod bending rigidity κ is explored. An approximation is used for rigid‐rods that do not need spherical harmonics leading to increased speed in finding equilibrium morphologies. The results show that standing vertical structures may be more easily produced with rigid‐rod blocks compared to coil‐coil lamellae, an important feature in nanolithographic applications. Suggestions are made for using the model in future molecular orientation studies where the model can be used with inverse search methods to measure the values of the model parameters for the real systems. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 29–39     

对抗P2P蠕虫的邻居选择机制

P2P网络中节点的邻居列表为蠕虫提供了快速传播的途径．网络中节点系统的漏洞情况各异,致使它们抵抗蠕虫的能力不同．无结构P2P网络中节点的位置影响着蠕虫围堵策略的效果,甚至影响整个网络的安全．为了对抗P2P蠕虫,在区分漏洞级别的基础上定义节点之间距离的计算方法,根据节点抵抗蠕虫的能力为其选择邻居,使得P2P网络中的节点分布更利于抵抗蠕虫的攻击;并将这种邻居选择机制应用到无结构P2P网络KaZaA中．实验结果表明,该选择机制明显提高了P2P网络对抗蠕虫的能力．     

环面滚珠蜗杆磨削问题的探讨

本文介绍了一种适合环面滚珠蜗杆的磨削方法以及设计出的相应的磨削装置。根据齿轮啮合原理和滚珠螺旋传动的设计准则可知,采用该方法磨削的环面滚珠蜗杆与滚珠之间可达到或接近滚珠螺旋传动的最佳接触。     

锥面二次包络圆柱蜗杆传动特性分析

以微分几何与空间啮合理论为基础，推导了锥面二次包络圆柱蜗杆幅传动齿面方程和主要啮合性能指标的数学表达式。通过实例计算得出这种蜗杆幅在砂轮半径（r=60-200）一定的变化范围之内，其接触性能和传动啮合性能变化不大，并且分析了砂轮的半锥角变化对于蜗杆齿形的影响。由此得出加工蜗杆时，对砂轮半径要求比较自由，半锥角要求比较严格。同时把它与阿基米德蜗杆副进行了对比分析，找出采用它的优越性。     

滚珠蜗杆传动的研究

提出了一种新型的蜗杆传动装置－－滚珠蜗杆传动。初步研究了它的啮合理论，设计要点，并作了初级工业样机。     

简单巨系统研究及其系统动力学分析

研究大量简单个体依照一定规则相互作用而在宏观上表现出群体智能特性可以用于解决一些复杂的问题.通过对一个实际问题-研究生楼问题的观察和分析,研究了单个个体的行为对整个系统带来的影响.在此基础上,提出了相应的数学模型,并进行了分析,得出了几点有价值的结论.     

误差补偿技术在直廓环面蜗杆高精度加工中的应用

针对如何在普通滚齿机上低成本地提高直廓环面蜗杆加工精度的问题，通过采用三坐标测量机对实际齿面进步坐标测量，由所得的测量结果与理论的蜗杆齿面进行比较分析，找出机床加工参数的调整误差，根据所得机床调整参数误差并基于误差补偿原理修正机床调整参数，从而明显地提高了直廓环面蜗杆的加工精度，同时，在保证有充足测点的条件下，只需沿着工件表面的一条螺旋线进行测量，使可较为准确地诊断出机床加工参数的调整误差，从而提高了蜗杆的检测效率。