计算机病毒的预防的思考

计算机病毒随着计算机的普及也渗透到信息化办公的各个领域,带给计算机操作系统难以防范的困扰。为使计算机信息安全有保障,研讨计算机的病毒的防范措施迫在眉睫。针对计算机病毒如何预防进行探究,并分析应对措施。     

基于FPGA的单片机的系统的设计

本文在阐述可编程逻辑器件特点及其发展趋势的基础上,利用EDA的硬件和软件技术,研究和设计了基于FPGA的8051单片机的片上系统。本文采用VHDL语言,应用先进的自顶向下的设计方法,在Active—HDL5．1编程环境下,应用层次化的设计思路,模块化的设计方法进行设计。     

行走的空间 当代的游牧

当“游牧”这个词之于人们已渐行渐远,一所“行走住房”（Walking House）正从德国慢慢走在返回丹麦的路上。“行走住房”呈横向的六角柱体形,柱体形状隐含了一种趋动的姿态,而六个硬朗的棱角似乎又暗示着游走和远行从来并非轻易。实际上“行走住房”的移动不是靠柱体本身的滚动,而是依赖底部六个支架——六只“脚”——以拟人化的方式前进。对比常见的交通工具,例如汽车、火车和轨道交通,因为这一组“脚”,“行走住房”显示出一种同人类本身更紧密的亲缘关系。     

山里的小学山里的孩子山里的老师

秦岭七十二道峪,其中一峪为“秀龙峪”,是传说中汉朝皇帝刘秀避难之地。该峪有一下峪村,村里的四组有一所当年部队驻扎时拥建的小学。     

基于gtkmm的linux下的图形界面开发的研究

目前,在linux环境下开发图形化界面已受到广泛关注,先简要介绍一下GTK,GTK+与gtkmm的区别,然后重点介绍gtkmm与glade相结合来开发C++图形界面应用程序。     

营林工作的可持续发展的探讨

森林以其独特的性质特点,使自身既可为人类社会的当代发展享用,又可以为人类的后代存续造福。然而,若森林得不到有效的维护,那么以上两种利处就无法得到实现。所以,我们要加大对森林可持续发展的认识程度,使森林成为改善人类福利的重要保证。这本身也体现了林业的可持续发展理念。我国政府对生态建设和林业建设给予了很高的注视程度。在相关的法律、政策上都有明确的规定,以保障林业的健康发展。同时,在资金的投入上,也相对有力,从而取得了可喜的治理成果。然而,由于长期以来存在的一些制度上的问题．我国的林业可持续发展也受到了一定的影响。     

韩国国内的半导体的投资

过去十年问,韩国的投资稳步增长,尤其是存储市场方面三星和现代频具实力。自从2002年开始,300mm硅片的生产能力迅速增长,目前预计2011年300mm硅片生产能力增     

艺术的都市人 都市人的艺术

<正>自古以来,城市不仅是人类财富与权利的中心,更是人类智慧与文明的汇集地。一代又一代的都市人不仅创造着物质财富,更在城市文化的熏陶下,创造了属于自己的灿烂精神文明。艺术是人类文明创造出的一朵奇葩,自城市诞生以来,它就一直伴随着都市人。从古代城市的辉煌遗迹到现代都市的热闹繁华,虽然都市人和艺术都经历着时代的变迁和发展,但是,都市人与艺术之间的密切关系却未曾改变。都市人创造了属于他们自己的艺术,而艺术也带给了     

工业光纤的更好的经济效益

当美国国家航空航天局（NASA）兰利研究中心的研究人员观察电磁干扰如何潜在影响飞行导航和通信系统时,得到了一些惊人的结果。举个例子,来自一些超宽带信号的干扰可能会在没有预警的情况下突然消除飞机无线电。电磁干扰（EMI）也可能会导致无线电导航系统给出错误的读数。电磁干扰也可以影响距离测量设备,在某些情况下,读出的距离可能远离一整个海里。也许最令人担忧的是,严重的电磁干扰会中断空中防撞系统显示屏上的飞机图像。     

测量光谱发射率的数学模型的建立

作者建立了一套测量300～500 ℃温度区间物体表面法向红外光谱发射率测量装置.在全面了解光电器件、电测设备原理基础上,从发射率定义出发,建立了与装置相对应的测量物体表面光谱发射率的数学(物理)模型,为实验数据的整理和不确定度评估打下了理论基础.     

Shrinkage compensation approach proposed for ABS material in FDM process

Dimensional accuracy of parts manufactured by Fused Deposition Modelling (FDM) greatly suffers from the shrinkage problems of the available polymer materials. This paper proposes a constructive idea for resolving the shrinkage issues and explains how shrinkage could be managed by interior geometry of the artifacts fabricated on desktop 3D printers. The main principle for preventing the deterioration on dimensional accuracy of the holes/slots is to utilize the auxiliary lines located from the hole’s perimeter to the outer boundaries of the artifact. Thus, the shrinkage of these auxiliary line segments simply helps to pull the original hole backward, acting against the predicted contraction. In this paper, the proposed approach will be examined using a finite element analysis tool to predict the shrinkage behavior of the fabricated samples along with necessary measurements taken on the Coordinate Measuring Machine. Additionally, an analytical framework for modeling the shrinkage behavior of ABS is to be elaborated. The coherence of the simulations and the measurements are to be analyzed regarding the effect of the geometry and material color on the shrinkage behavior. The discussion involves the improvement on the dimensional accuracy of 3D printed features.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Ice formation process by cooling water–oil emulsion with stirring in a vessel

An emulsion, which was a mixture of silanol-aqueous solution and silicone oil, was investigated as a heat storage material for a dynamic type ice storage system. The emulsion was poured into a vessel, which was immersed into a constant temperature bath at a low temperature, and frozen with stirring. Using stainless steel vessels coated with PFA resin and PTFE vessels with different thickness, the experiments were carried out under various conditions of temperature. Measuring the temperature history in the vessel, overall heat transfer coefficients before the start of freezing and during the ice formation were obtained. The effects of the material of the cooling surface and the thermal resistance of the wall on the ice formation process were clarified. If the heat flux of the wall was less than a critical value, slurry ice was formed without adhesion to the cooling surface. The results obtained under the same condition of the thermal resistance proved that it was effective against ice adhesion to coat PFA resin inside the vessel. It was found by the experiments in which the PTFE vessels were used that the critical value of the heat flux was nearly constant regardless of the thermal resistance.     

Tribologische Kennwerte für Reibwerkstoffe

Tribology parameters for friction materials The tribology parameters of the friction materials are currently the coefficient of friction and the wear coefficient. They are determined depending on the material, the surface pressure and the frictional speed. These two parameters are not sufficient for an evaluation of the friction materials on the basis of a wear theory. Their validity is therefore limited. It is proposed to evaluate the friction materials on the basis of the energetic wear theory. The parameters are then the wear energy density, the shear stress of friction and the linear wear intensity. These values can be shown in a diagram and allow for the direct comparison of widely varying friction materials. The reference coefficient of friction is being introduced as a new wear parameter. The determination of the proposed parameters is made on a flywheel test rig, combined with the laser‐optical online measurement of the wear particles. It was possible to demonstrate that the parameters correctly describe the practice‐relevant requirements using two proven friction materials.     

Parametric optimization of a new combined refrigeration cycle – active thermal potentiostatting system

The active thermal potentiostatting system proposed by Martinovskii and Tsirlin is directly generalized to a more practical case, in which one intermediate chamber, besides a thermal potentiostatting chamber, and two irreversible refrigeration cycles are included and the influence of the thermal resistance between the working fluid and the reservoirs, the heat leakages from the environment to the intermediate chamber and from the intermediate chamber to the potentiostatting chamber are taken into account. Expressions for the main parameters of the system are derived. By using the optimal control theory, the minimum total power input of the system with non-zero cooling rates is calculated and the temperatures of the working fluid in the isothermal processes of the refrigeration cycles are optimized. The optimal allocation of the heat-transfer areas of the heat-exchangers in the refrigeration cycles is discussed in detail. The results obtained here are more general and useful than the relevant results in literature and can provide some valuable guidance for the optimal design and operation of real active thermal potentiostatting systems.     

Verbesserung des Eigenspannungszustands beim Kaltfließpressen durch den aktiven Einsatz eines gesteuerten Gegenstempels

By using an active counter punch during cold extrusion, the residual stress of the component can significantly be improved, which can increase its fatigue strength. In general, the workpieces produced through full‐forward extrusion are characterized by a strongly unfavourable stress state: The resulting high axial tensile residual stresses on the surface as well as the steep stress gradient accelerate the formation and the growth of cracks during cyclic loading. A system developed by the authors, consisting of a counter punch actively employed during the forming process allows improving the residual stress state of the final product. This result is obtained through a homogenization of the deformations in the samples during the cold extrusion. Therefore, a finite element simulation of the process was developed in Simufact Forming®. The simulation was experimentally validated by using the two austenitic steels 1.4307 and 1.4404. Another focus is the development of suitable measuring strategies for the X‐ray residual stress analysis with the sin²Ψ‐method to ensure the quality of the measurement results despite coarse‐grained and anisotropic microstructures. The results of the simulations and the experiments show that his technique has a considerable potential to increase the product quality without modifying the process time.     

An experimental study on minimizing frost deposition on a cold surface under natural convection conditions by use of a novel anti-frosting paint. Part II. Long-term performance, frost layer observation and mechanism analysis

In this part of study, the comparative observations of the structure and the surface temperature of the frost layer of both the coated and uncoated surfaces ware carried out and a preliminary analysis was presented. A series of the repeated cycling tests were completed that lasted for more than 2 months, and the influences of the coating thickness were also investigated. The results show that the frost layer deposited on the coating surface has a very fragile structure and can be removed easily by external force. The coating thickness has an important effect on the anti-frosting performance of the paint. The results also show that the coating of the paint on the copper surface is durable and presents a very good repeated cycling performance.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.     

Two-phase split of refrigerants at a T-junction

The present study experimentally investigated the two-phase flow split of refrigerants at a T-junction. As geometric parameters, the direction of the inlet or branch tube and the tube diameter ratio of branch to inlet tube were chosen. As inlet flow parameters, the inlet mass flux and quality were varied from 100 to 700 kg m⁻² s⁻¹ and from 0.1 to 0.9, respectively, for the condition of distribution header of a multi-pass evaporator in the general refrigeration system. All experiments were performed for R-22, R-134a, and R-410A. The measured data were compared with the values predicted by the models developed for air–water or steam–water mixture in the literature. We propose a modified model for application to the reduced T-junction and vertical orientation of tubes. Among the geometric parameters, the branch tube direction showed the largest sensitivity to the mass flow rate ratio for the gas phase, while the inlet quality showed the largest sensitivity to the mass flow rate ratio among the inlet flow parameters.