机械结构因素对光电跟踪伺服系统性能的影响

为克服机械结构因素对光电跟踪伺服系统性能的不良影响,分析了转动惯量、结构谐振频率、摩擦力矩等伺服机械结构因素与伺服系统性能的关系,包括分析转动惯量与伺服系统性能的关系、结构谐振频率与伺服系统性能的关系、摩擦力矩与伺服系统性能的关系,探讨了消除或减小机械谐振的措施.该分析方法可应用于设计和制造响应速度快、跟踪精度高的光电跟踪伺服系统.     

CO（ a）+ NO（X）传能体系中的新传能通道

在相对碰撞平动能为 0 .0 5eV的分子束实验条件下 ,研究了亚稳态CO(a) +NO(X)的E E传能通道 .通过测量和分析交碰区的传能发射光谱 ,在 780和 860nm处观测到了NO(b -a)跃迁Ogawa带的△v =+ 4和△v =+ 3序的发射光谱 .从而首次在实验上直接证实了传能过程中第四通道的存在 (CO (a) +NO(X)→CO (X) +NO(b) ) .这一通道的发现解释了前人测量到的在CO(a)与NO(X)碰撞传能过程中CO(a)的猝灭速率远大于NO(A ,B)生成速率的实验结果 ,并进一步证实了这一“经典”E E传能体系为电子交换机理的传能观点     

Formation of metallic NbSe2 nanotubes and nanofibers

We succeed in synthesizing NbSe₂ nanotubes along with nanofibers by chemical vapor transportation. They are stable crystalline systems and can be synthesized reproducibly in a nearly equilibrium reacting process. We have investigated these nanosize structures of NbSe₂ by transmission electron microscopy and electron diffraction. Both of the structures have a similar size of 100–200 nm in diameter. While nanotubes consist of rolled-up NbSe₂ layers, nanofibers are a pile of thin flat layers. We propose a mechanism of the formation of NbSe₂ nanotubes and nanofibers on the basis of deseleniditive transition from a NbSe₃ fiber-shaped crystal. We also measured electrical resistance of the nanofibers with conductive atomic force microscopy and demonstrated that the material show metallic behavior at room temperature.     

掺Perylene的PVK薄膜荧光谱及发光机理

用高荧光效率的有机染料芘(perylene)掺杂聚乙烯咔唑(PVK),其荧光光谱与芘的发射光谱基本一致,而且亮度比纯芘发光提高十多倍,说明发光主要来自芘分子,并在PVK和perylene之间存在十分有效的能量传递或电荷转移过程,荧光谱强度随掺杂浓度的变化关系说明存在一个最佳的掺杂浓度比.分析PVK和perylene之间可能发生的能量转移过程,认为从PVK到perylene这种能量转移与实验不符;分析PVK和perylene薄膜的光致发光过程,认为从(PVK+)→(perylene+)和从(PVK-)→(p     

2006年7月3日宁阳县大暴雨过程分析

分析了2006年7月3日山东省宁阳县大暴雨的形成过程,对这次大暴雨的形成机制进行了探讨。     

关于加强企业制度建设的几点思考

分析了企业在制度建设工作中存在的问题,提出了加强企业制度建设的建议。     

用经济学观点探讨城市苗木基地建设和管理

论述了如何运用市场机制和宏观调控等经济学观点对苗木基地的生产、管理和规划进行科学的指导。     

Quantum-Chemical Study of the Profiles of Reactions that Form Pyrrole Anion N-Adducts with CS<Subscript>2</Subscript> and CO<Subscript>2</Subscript>

The profiles of reactions leading to pyrrole anion N-adducts with CO₂ and CS₂ have been studied by the ab initio (RHF/6-31+G*, MP2/6-31+G*) and density functional (B3LYP/6-31+G*) methods. Addition of the pyrrole anion to the carbon disulfide molecule is accompanied by the appearance of a minimum corresponding to a pre-reaction complex. The transformation of the complex to the N-pyrrolyldithiocarboxylate anion occurs via a low activation barrier, which is due to repolarization of the C=S bonds. The profile of the reaction leading to the pyrrole anion N-adduct with CO₂ does not contain any intermediate stationary points throughout the whole route from reagents to products.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, I. L. Zaitseva, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 990–993, November–December, 2004.     

A Digital Right Management Model for Distribution of Digital Audiovisual Content

0 IntroductionDue to the success of Internet technology and the emer-gence of wide band network,downloading encoded dig-ital audiovisual content files via HTTP,FTP,etc ,had gainedfavor amongInternet users because of thei mmediate access todesired content . Digital Right Management (DRM) system,can satisfy the content provider by encrypting digital audiovi-sual content andli miting access to onlythose people who haveacquired a proper license to play backthe content[1].DRMas defined bythe …     

论地理信息系统的发展机理与发展趋势

从地理信息系统（ＧＩＳ）的发展渊源出发，总结了地理信息系统发展的４个阶段：６０年代起步阶段；７０年代发展阶段；８０年代应用阶段；９０年代成熟阶段．提出了地理信息系统的４个发展趋势：体系结构日臻完善；向多用途综合化方向发展；向智能型辅助决策方向发展；向实用型产业化方向发展