Pb_n微团簇(n=20～30)及铅晶体表面过程的计算机模拟

基于Murrell等提出的有效正体加三体展开势能函数对铅微团簇Pbn (n =2～ 3 0 )的结构及面心立方晶体铅的表面行为进行了计算机模拟。发现Pbn 微团簇的结构衍生规律为 :依次增加一个三配位的表面原子 ,分子表面为三元环所覆盖 ,整个分子为畸变的四面体的密堆积 ;f (c)铅晶体的表面层原子间内压缩最为严重 (最大达 8% ) ,从第三层开始层间距的伸缩率已经很小 ( <1 % )。     

计算机视觉系统框架的新构思

计算机视觉是人类视觉的模拟。计算机视觉四十多年的发展既取得了成绩也存在不足。在计算机视觉发展过程中,相继提出了三个主要的理论框架：计算视觉理论,基于知识的视觉理论和主动视觉理论。该文对这三个理论框架及其存在的问题进行了讨论,并提出了一个完善和通用的计算机视觉的系统框架。     

Reconfigurable computing: design methodology and hardware tasks scheduling for real-time image processing

Technology evolution makes possible the integration of heterogeneous components as programmable elements (processors), hardware dedicated blocks, hierarchical memories and buses. Furthermore, an optimized reconfigurable logic core embedded within a System-on-Chip will associate the performances of dedicated architecture and the flexibility of programmable ones. In order to increase performances, some of the applications are carried out in hardware, using dynamically reconfigurable logic, rather than software, using programmable elements. This approach offers a suitable hardware support to design malleable systems able to adapt themselves to a specific application. This article makes a synthesis of the Ardoise project. The first objective of Ardoise project was to design and to produce a dynamically reconfigurable platform based on commercial FPGAs. The concept of dynamically reconfigurable architecture depends partially on new design methodologies elaboration as well as on the programming environment. The platform architecture was designed to be suitable for real-time image processing. The article outlines mainly the Ardoise tools aspect: development environment and real-time management of the hardware tasks. The proposed methodology is based on a dynamic management of tasks according to an application scenario written using C++ language.

ATMS在计算机辅助中医诊断中的应用*

计算机辅助诊断是当前人工智能和信息技术研究的热点之一。针对计算机辅助中医诊断的特殊性,结合ATMS这一人工智能推理系统,以脾虚证的计算机辅助诊断研究为契机,讨论了运用ATMS进行中医辅助诊断规则的表示、挖掘、查询和更新的问题。     

不确定线性组合系统的鲁棒H_∞性能的判定

针对一类线性组合不确定系统的结构特征提出了分散鲁棒 H∞ 性能的概念。它充分利用组合系统的互联结构 ,为研究大系统 H∞ 性能提供了新途径。给出了大系统具有分散鲁棒 H∞ 性能的条件 ,以及利用分散鲁棒 H∞ 性能判断大系统的整个鲁棒 H∞ 性能的方法。结果表明 ,大系统的 H∞ 性能与子系统H∞ 性能密切相关。只要每个子系统具有鲁棒 H∞ 性能 ,则在同样的控制条件下 ,大系统也具有鲁棒 H∞性能 ,只是性能指标弱一些。     

一类相似广义互联系统的导数-输出反馈鲁棒控制器设计

以广义系统中受限系统等价概念和导数反馈- 输出反馈为基础,定义了一类广义互联系统的相似结构,提出了相似性研究的新方向.这类系 统具有不满足匹配条件的非线性不确定互联项.设计了导数-输出反馈鲁棒分散控制器,使互 联系统在平衡点处渐近稳定.由于控制器本身也具有相似结构,因此易于工程实现.     

Correlation between acidic properties of nickel sulfate supported on TiO2-ZrO2 and catalytic activity for ethylene dimerization

A series of catalysts, NiSO₄/TiO₂-ZrO₂, for ethylene dimerization was prepared by the impregnation method using an aqueous solution of nickel sulfate. For NiSO₄/TiO₂ -ZrO₂ sample, no diffraction line of nickel sulfate was observed up to 30 wt%, indicating good dispersion of nickel sulfate on the surface of TiO₂-ZrO₂. The addition of nickel sulfate to TiO₂-ZrO₂ shifted the phase transition of TiZrO₄ from amorphous to orthorhombic to a higher temperature because of the interaction between nickel sulfate and TiO₂-ZrO₂. The number of acid sites of NiSO₄/TiO₂-ZrO₂ increased in proportion to the nickel sulfate content up to 20 wt% of NiSO₄. Nickel sulfate supported on TiO₂-ZrO₂ was found to be very active even at room temperature, giving a maximum in both activity and acidity when the catalyst containing 20% NiSO₄ was calcined and evacuated at 500°C The asymmetric stretching frequency of the S=O bonds for NiSO₄/TiO₂-ZrO₂ samples was related to the acidic properties and catalytic activity. That is, the higher the frequency, the higher both the number of acid sites and the catalytic activity for ethylene dimerization.     

Effect of nanopore size on poly(dT)30 translocation through silicon nitride membrane

The nanopore size effect on translocation of poly(dT)30through Si3N4 membrane is investigated.In this paper,we report that the speed of the poly(dT)30 transport through Si3N4 nanopores can be slowed down by half through increasing the nanopore diameter from 4.8 nm to 10.8 nm.The results are consistent with our simulation results.Besides,the current blockage induced by DNA passing through the nanopore is less obvious as pore diameter is larger,which is in good agreement with the theoretical prediction.The conclusion about DNA transport through nanopores is beneficial for the design of DNA sequencing devices.     

Preparation and mechanical behavior of Mg-based bulk metallic glasses and their matrix composite

Mg87-xCuxDy13(x=22,27,32) bulk metallic glasses (BGMs) with a diameter of 6-8 mm and in-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite with a diameter of 3 mm have been prepared by copper mould casting. The glass forming ability (GFA) of Mg-Cu-Dy alloys have been investigated by differential scanning calorimetry (DSC) and X-Ray diffraction (XRD) and tne mechanical properties have been measured. Results show that Mg87-xCuxDy13(x=22,27,32) alloys in the Mg-Cu-Dy alloy system exhibit excellent GFA, and Mg60Cu27Dy13 alloy has the largest GFA among these alloys. And In-situ Mg phase reinforced Mg70Cu17Dy13 BMG matrix composite exhibits some work hardening and a high fracture compressive strength of 702.38 MPa and some plastic strain of 0.81%. The improvement of the mechanical properties is attributed to the fact that the Mg phase distributed in the amorphous matrix of the alloy has some effective load bearing and plastic deformation ability to restrict the expanding of shear bands and cracks and produce its own plastic deformation.     

黄河流域实施水功能区限制纳污红线管理的整体构想与初步实践

水功能区限制纳污红线管理是实行最严格水资源管理制度的核心内涵之一。黄河流域水安全问题是中国水安全问题的缩影,探索构建行之有效且具有黄河流域特色的纳污红线管理制度体系和工作格局,对于提高黄河流域水安全保障能力意义重大。针对黄河流域的水资源质量状况,探索建立流域与区域相结合、水利与环保相联合的黄河水资源保护管理体系,构建流域水功能区划及水资源保护规划体系,依法强化以入河排污口为重点的水功能区管理,积极探索水生态系统保护与修复,加强水质监测网络体系建设等一系列措施,为黄河流域实施纳污红线管理提供了良好的工作基础和能力支撑,并在此基础上阐述了黄河流域实施纳污红线管理的整体构想与初步实践。