CO催化氧化的实验与Monte Carlo模拟

主要对CO在Pt表面催化氧化反应的实验做了具体描述,介绍以ZGB模型为基础的MC模拟方法,得到一系列与实验较接近的模拟结果.在模拟中,重点考察重构表面的诱导相变和反应物的脱附等因素对反应的影响.     

中国通信设备与制药产业创新系统比较研究

通信设备产业和医药产业都是中国重点支持发展的高新技术产业,但两个产业的差异也显而易见:通信设备产业具备较强的创新能力,无论是企业竞争力还是企业创新成果都从最初的毫无国际影响发展到处于国际领先水平。本文运用产业创新系统框架,对两个产业进行了比较分析。研究认为,产业知识基础(如技术机会)、行为人和网络(如市场需求、研发合作、政府支持等)和制度基础(如知识产权制度)三个方面能够一定程度的说明两个产业创新能力产生差异的原因。     

兰州市幼儿体质现状调查的必要性及意义

幼儿体质的好坏直接影响着他们今后的生活、学习、工作质量以及心理反应。论文结合实际,深入分析了兰州市开展幼儿体质状况调查的必要性和意义。     

对大学生自杀意念影响因素的梳理

目的:探讨大学生自杀意念产生的影响因素,从而为更好地预防大学生自杀事件的发生提供帮助。方法:在维普数据库中,以大学生、自杀意念作为关键词,搜索相关文献,进行文献综述。结果:判断自杀意念的标准不一致,测查自杀意念的时间段存在区别;自杀意念的影响因素包括:抑郁、人格特征、心理健康、应激等;自杀意念相关影响因素的研究欠缺,各因素之间交互作用的探讨等。     

A fast and versatile cross-linking strategy via o-phthalaldehyde condensation for mechanically strengthened and functional hydrogels

Fast and catalyst-free cross-linking strategy is of great significance for construction of covalently cross-linked hydrogels. Here, we report the condensation reaction between o-phthalaldehyde (OPA) and N-nucleophiles (primary amine, hydrazide and aminooxy) for hydrogel formation for the first time. When four-arm poly(ethylene glycol) (4aPEG) capped with OPA was mixed with various N-nucleophile-terminated 4aPEG as building blocks, hydrogels were formed with superfast gelation rate, higher mechanical strength and markedly lower critical gelation concentrations, compared to benzaldehyde-based counterparts. Small molecule model reactions indicate the key to these cross-links is the fast formation of heterocycle phthalimidine product or isoindole (bis)hemiaminal intermediates, depending on the N-nucleophiles. The second-order rate constant for the formation of phthalimidine linkage (4.3 M⁻¹ s⁻¹) is over 3000 times and 200 times higher than those for acylhydrazone and oxime formation from benzaldehyde, respectively, and comparable to many cycloaddition click reactions. Based on the versatile OPA chemistry, various hydrogels can be readily prepared from naturally derived polysaccharides, proteins or synthetic polymers without complicated chemical modification. Moreover, biofunctionality is facilely imparted to the hydrogels by introducing amine-bearing peptides via the reaction between OPA and amino group.     

图书馆大数据服务背景下用户隐私权危机的治理策略

大数据在图书馆创新服务模式的同时也导致用户的隐私权危机。如何化解用户隐私权危机,保障用户隐私安全问题成为图书馆开展大数据服务的一个重要课题。本文通过梳理国内外用户隐私泄露案例和图书馆用户隐私权侵权状况,从大数据基础设施、管理方式和应用误区3个方面分析图书馆用户隐私泄露的原因。以此为基础,从构建国家立法监督、行业规范管理、技术研发保障和个人维权意识4个角度阐述图书馆用户隐私权危机的治理策略。     

实名SNS社交网络与微博的特征分析——以人人网与新浪微博为例

以人人网和新浪微博为例,通过SPSS统计软件分析比较实名SNS社交网络与微博的功能特征与用户行为特点。研究认为人人网用户活跃度与用户本身隐私保护意识有一定联系;新浪微博用户活跃度与用户的学历存在一定联系。人人网与新浪微博同时存在用户被动接收推送广告信息问题,影响了用户的体验度。探讨了人人网与新浪微博的商业化运营趋势,为实名社交网站和微博的完善与差别化发展提供了理论依据。     

Fractional order sliding mode control of a pneumatic position servo system

Gas flow has fractional order dynamics; therefore, it is reasonable to assume that the pneumatic systems with a proportional valve to regulate gas flow have fractional order dynamics as well. There is a hypothesis that the fractional order control has better control performance for this inherent fractional order system, although the model used for fractional controller design is integer order. To test this hypothesis, a fractional order sliding mode controller is proposed to control the pneumatic position servo system, which is based on the exponential reaching law. In this method, the fractional order derivative is introduced into the sliding mode surface. The stability of the controller is proven using Lyapunov theorem. Since the pressure sensor is not required, the control system configuration is simple and inexpensive. The experimental results presented indicate the proposed method has better control performance than the fractional order proportional integral derivative (FPID) controller and some conventional integral order control methods. Points to be noticed here are that the fractional order sliding mode control is superior to the integral order sliding mode counterpart, and the FPID is superior to the corresponding integral order PID, both with optimal parameters. Among all the methods compared, the proposed method achieves the highest tracking accuracy. Moreover, the proposed controller has less chattering in the manipulated variable, the energy consumption of the controller is therefore substantially reduced.     

抽油机减速箱缺油保护系统的研制

抽油机减速箱损坏的主要原因是减速箱润滑油不足造成的,而目前抽油机减速箱内的油量情况难于实时发现并采取措施,减速箱缺油后,抽油机不能立即停机,而减速箱继续在缺油状态下长期运转,在大多数情况下将造成齿轮、轴承的损坏,甚至报废。为解决这一问题,我们研制了一种实时报警装置,当油量少于设定最小值时,它可以在现场发出报警信号,并对抽油机按要求采取强制停机等措施。     

基于ASP.Net应用系统的网络安全研究与设计

介绍了基于ASP.Net平台B/S架构的应用系统网络安全的设计,分析了B/S三层网络架构的安全机制,给出了通过身份验证、权限控制、数据加密、存储过程访问数据库等手段实现系统的安全性的技术要点。