热喷涂工艺制备铝基非晶态合金材料研究进展

传统的铝基非晶态合金的制备方法有急冷法和机械合金化法.急冷法使用方便,冷却速率快,可获得非晶,可实现连续生产;机械合金化法具有设备简单,操作方便,易工业化,合金成分范围相对较宽等优点.但是这两种方法只限于制备非晶条带、薄片或粉末,而且生产制备周期较长,生产效率较低.热喷涂技术作为一种新兴的制备工艺,可获得非晶涂层,实现...     

镁合金板材的生产历史与研究现状

近年来,来自节能和环保的压力大大促进了镁合金产业的发展,具有高技术含量的镁合金板材的制备技术愈来愈受到人们关注。介绍了国内外镁合金板材的生产历史及其制备技术的研究现状,并讨论了传统制备技术和近来发展起来的几种新型轧制制备技术的特点、基本原理、研究现状及应用,对我国镁合金板材生产的发展状况进行了阐述,并提出了我国镁合金板材的发展方向。     

国产第一套漂白二氧化氯制备系统的生产工艺、方法及钛材管道焊接要点

本文从日照华泰纸业有限公司清洁生产治污节能技术改造项目,配套建设的8t/d二氧化氯制备系统实际工程为例,简单阐述二氧化氯制备工段的生产主要生产设备、原材料、工艺流程、工艺方法及钛材管道焊接安装工作要点。     

高纯钛的应用及其生产方法

详细介绍了高纯钛的应用现状,并对高纯钛的主要生产方法--克劳尔法、碘化法、熔盐电解法、电子束熔炼精炼法等进行了综述,指出只有几种方法结合才能获得纯度要求非常高的高纯钛;研发新的制备方法,克服传统制备工艺的复杂性,提高生产效率,降低生产成本,是高纯钛制备研究的发展方向.     

防冻液生产控制站与纯水制备装置PLC通讯的实现

纯水制备装置是防冻液生产过程中的独立设备,其S7-200PLC控制系统需要并到基于S7-300PLC和WinCC的防冻液生产控制系统中去。文章主要介绍防冻液生产PLC控制站与纯水制备装置控制系统通过EM277模块实现的PROFIBUS现场总线通信进行数据交换,实现WinCC对纯水制备装置的远程监控与操作,实现防冻液生产控制系统的集成。     

中国科大碳纳米纤维组装体的宏量制备及应用研究获进展

最近,中国科学技术大学俞书宏教授领导的研究小组在以往宏量制备纳米线三维材料实验的启发下,利用可吨级生产的廉价的细菌纤维素纳米纤维凝胶为原料,经过冷冻干燥及煅烧后,成功制备出超轻、柔性及抗火性能极好的碳纳米纤维气凝胶,在国际上率先实现了利用工业化大规模生产的生物质材料来制备三维碳纳米材料。     

六氟化硫的制备方法

本发明是关于六氟化硫(SF6)的制备方法，特别是关于容易大量生产高纯度、低成本SF6的制备方法。     

利用工业废渣制备软土固化剂的可行性探讨

就如何高附加值地利用工业废渣制备软土固化剂进行了技术效果、经济效益及生产方式等方面的可行性探讨。基于固化土结构形成过程的特点及其对固化剂组成的特殊需求,提出了利用工业废渣制备固化剂的设计思想,给出了固化剂配比实例,与水泥进行了性价比对比分析,并初步探讨了利用工业废渣产业化生产固化剂宜采取的生产经营方式。认为只要能根据形成固化土结构对固化剂组成材料的特殊需求针对性地选择适当的工业废渣,就能够制备出高性价比的软土固化剂;宜根据拟加固土的性质个性化设计制备固化剂,采用多组分组配式生产方式以及设计、生产、销售一体化的经营模式。     

TiO2光催化剂的制备与改性研究进展

综述了TiO2光催化剂的制备和改性研究进展,提出:①在光催化剂的制备方面,还应该开展一些新型的制备技术和产物性能方面的深入研究;②为了获得高性能、低成本的改性光催化剂,还应该深入开展把光催化剂的制备和改性直接结合起来的易于实现商业生产的技术研究.     

六氟磷酸锂概述及制备工艺研究

概述六氟磷酸锂的性质、用途、市场前景和生产现状,开展制备工艺研究。     

Research on Hydraulic System of Hydraulic Driven Garden Pulverizer Based on AMESim Simulation

To analyze a certain type of trees crusher working condition,to consider the limitation of electric,the motor driven pulverizer can only work in a fixed place. Therefore,a set of hydraulic system is used to replace the motor. So it can get rid of electricity,and move conveniently,applying to the suburbs,parks,roadsides,which means expanding the range of application. Secondly,in view of the pulverizer speed higher than the motor speed,it is necessary to add the auxiliary speed regulating device. Besides, to adjust speed is more troublesome,and the hydraulic motor can directly drive the pulverizer. Therefore to adjust the flow of the hydraulic motor can change the speed of the pulverizer. In addition,base on the characteristics of work start,and stop,with a long time,big moment of inertia for Pulverizer,and it is the growth process of the motor driving pulverizer. The rotary inertia equivalent to the motor end will increase the square of the reduce ratio,and the load of the machine obviously. Driving by hydraulic motor straightly,and this problem will be avoided. Finally,in the light of the large start-up torque,and the high speed at working time of the pulverizer,the constant power pumps is choosed to meet the work demand. Constant power pumps can adjust the flow and pressure according to the different load automatically,thus more energy are saved. Hydraulic system simulation model is established based on the AMESim simulation,which verify the scheme is feasible.     

Computer simulation of chemisorption on strained metals

On the basis of the results of quantum-chemical calculations according to the method of complete neglect of differential overlap, we substantiate the choice of aluminum, iron, nickel, and copper clusters used in the investigation of the chemisorption of atoms and molecules of simple gases on metal surfaces. By using the modified method of incomplete neglect of differential overlap, we discovered the effect of a significant increase in the heats of hydrogen, nitrogen, oxygen, and carbon monoxide chemisorption on strained Al, Fe, Ni, and Cu clusters.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 6, pp. 7–15, November–December, 1993.     

Liquid-phase deposition and the properties of thin zirconium dioxide films on different substrates

In recent years, the interest of the researchers to the methods of synthesis of inorganic thin oxide films from low-temperature liquid solutions permanently increases. This is explained by the recent achievements in the technology of deposition of the films, including, in particular, chemical deposition, sputtering, laser ablation, and evaporation. The liquid-phase deposition is an aqueous procedure of deposition of oxide films. In our investigation, we try to improve the adhesion and stability of zirconium-oxide coatings on polymers. Ceramic coatings (ZrO₂) protect the surface of the substrate against reactions with acids and oxidation. The deposition of ceramic coatings on polymers is connected with serious problems due to the sensitivity of polymers to the action of chemical reagents and high temperature. We make an attempt to explain the role of the substrate in the process of deposition of zirconium-oxide films from the liquid phase on the Kapton polymeric material with different types of surface treatment. It is shown that even insignificant variations of the pH value, temperature, and composition of the solution can noticeably affect the crystalline film, adhesion, and growth rate. Thin films are very smooth, homogeneous, and characterized by the presence of an insignificant number of cracks. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 2, pp. 53–56, March–April, 2008.     

头戴式耳机耳垫材质舒适性评价指标体系研究

目的 基于服装材质舒适性研究,建立头戴式耳机耳垫材质舒适性指标评价体系。方法 通过桌面研究的方法,分析服装材质的相关文献,提取服装材质舒适性的各项性能,并根据服装材质的各项性能,分析各项性能的相关指标。首先通过层次分析法,构建基于材质基本性能的头戴式耳机耳垫材质舒适性递阶层次结构模型,通过比较判断矩阵同一层次各指标的相对重要性,进行指标权重分析,得到各个指标的权重。其次通过桌面研究的方法,将耳垫材质进行分类,并总结性能指标的最优测量方法。将耳垫的测量数据进行数据标准化处理,通过Min-max标准化方法,得到所有耳垫材质测量值的标准化数值,将各个指标的权重与每个材质的标准化数值相乘后求和,得到每个材质的舒适性得分。最后对耳垫材质舒适性评价指标体系进行效度分析。结论 通过构建头戴式耳机耳垫材质舒适性指标评价体系,确定了8个耳垫材质舒适性指标,得到了各个指标的权重,并系统地总结了各个指标的测量方法和耳垫材质的分类,最后根据Min-max标准化方法进行数据归一化,通过加权得到耳垫材质舒适性的评分,对该评价体系进行验证,验证结果具有有效性。该指标体系能够为头戴式耳机整体舒适性提供材质选择的参考标...     

Computation of probabilistic stability measures for a controlled distributed parameter system

Parameter uncertainty can degrade the performance of an otherwise well-designed control system, sometimes leading to system instability. In the context of structural control, performance degradation and instability imply excessive vibration and even structural failure. The ability of a controller to maintain the stability of a system in spite of parameter uncertainty is measured by its robustness, which can be viewed as a probability measure, wherein the joint distribution is of dimension equal to the number of uncertain parameters and the failure hypersurface is defined by the onset of instability in the eigenspace. This observation has led to some recent analyses employing FORM/SORM methods and Monte Carlo simulation.The extension of these concepts to distributed parameter systems is, unfortunately, not immediate. The mere fact that these systems are infinite dimensional precludes the use of much of the machinery available for discrete systems, unless the distributed system is first discretized, which itself introduces error into the analysis, or is represented by an eigenfunction expansion, which requires truncation after some finite number of modes, also a potential source of error. In fact, the system will behave as one with an infinite number of subsystems with highly dependent failure modes in series.In Bergman and Hall, Effect of controller uncertainty on the stability of a distributed parameter system, Structural Safety and Reliability, eds. Schuëller, Shinozuka and Yao, Balkema, Rotterdam, 1993, pp. 210–220, root locus analysis was employed to assess the reliability of the system, requiring the repetitive solution of a transcendental characteristic equation over a range of the parameter under investigation. The loci then provide a mapping from the probability distribution of the random parameter to the probability distribution of the system eigenvalues. This approach was utilized over 30 years ago by Boyce, Random vibration of strings and bars, Proc. of the Fourth US National Congress of Applied Mechanics, Berkeley, 18–21 June, 1962, pp. 77–85, who examined eigenvalue distributions for undamped taut strings and Euler-Bernoulli beams, each subjected to the action of a single point actuator. He demonstrated that, for the case of uncertainty in the actuator gain alone, a simple, closed form mapping leading to the distributions of the eigenvalues of the system could be determined directly from the distribution of the actuator gain, and for uncertainty in the remaining parameters, approximate distributions could be obtained through the application of perturbation methods.In the current paper, the FORM/SORM approach is applied to the taut string problem, where the distributed nature of the system is maintained throughout the analysis. Uncertain parameters, in this case the proportional gain and time delay, are characterized by probability distributions with known mean and variance. Each is transformed to a standard normal variate via Rosenblatt transformations, and the most likely failure point in the parameter space is found using a constrained optimization procedure. The effect of distribution is shown through parameter studies, and verification is provided by Monte Carlo simulation. As expected, time delay is shown to have a pronounced effect upon system robustness.     

A new features on S-waves propagation in a nonhomogeneous anisotropic incompressible medium under influence of gravity field and initial stress with and without electromagnetic field and rotation

The present article is concerned with the investigation of the propagation of shear waves in a nonhomogeneous anisotropic incompressible medium under the effect of the electromagnetic field, gravity field, rotation, and initial stress taking into account a comparison between presence and absence of magnetic field, initial stress, and rotation. Analytical analysis reveals that the velocity of propagation of the shear waves depends upon the direction of propagation, the anisotropy, magnetic field, rotation, gravity field, nonhomogeneity of the medium, and the initial stress. The frequency equation that determines the velocity of the shear waves has been obtained. Some special cases are also deduced from the present investigation. In fact, these equations are an agreement with the corresponding classical results when the medium is isotropic. Numerical results have been given and illustrated graphically in each case considered. The results indicate that the effects of gravity field, initial stress, magnetic field, electric field, anisotropy, and rotation are very pronounced. Also, the absence of initial stress, magnetic field, and rotation tends to increasing of the S-waves velocity compared with presence of them.     

The influence of elastic-dissipative coupling parameters on resonant vibrations of systems with violated cyclic symmetry

This paper deals with the regularities of the influence of the variation of the elastic-dissipative coupling parameters of subsystems on the formation of resonant vibrations of systems with a violated cyclic symmetry, like shrouded blade assemblies, and gives the results of numerical calculations. The formation of the amplitude-frequency characteristics and the distribution of resonant vibration amplitudes of the systems under study is shown to depend on the relationship between elastic and dissipative characteristics of coupling of the subsystems. When the elastic coupling is stiff, which provides localization of vibrations of the elastically-coupled system, the introduction of dissipative coupling does not cause any changes in the behavior of the amplitude-frequency characteristics, and the degree of localization is almost independent of the dissipative properties of the coupling. As the stiffness of the elastic-dissipative coupling grows, the localization of vibrations shows up only at certain values of the dissipative characteristics of the coupling. Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 1, pp. 102–115, January–February, 1999.     

The normal shock waves of real gases and the generalized isentropic exponents

When a supersonic gas flow is choked or otherwise disturbed, a shock wave appears. When this shock wave is perpendicular to the direction of the one-dimensional flow, a normal shock wave transforms the flow to a subsonic one. The thermodynamic variables involved are five, i.e. the pressure, the specific volume, the temperature, the enthalpy and the velocity of the flow. To determine their values after the normal Shock, five relations are used namely the equation of state, the enthalpy equation, the laws of conservation of impulse and energy, and the continuity of mass. For the simple case of a perfect gas, these relations are explicit and allow a straightforward solution of the system of the five equations. In the case of a real gas flow the system is solved numerically. The present work considers two other possibilities, i.e. the use of perfect gas like equations describing the phenomenon or the use of the Redlich-Kwong equation of state. Perfect gas like equations may be used now, to describe the phenomenon, after it has been shown that there exist three isentropic exponents, instead of the one used until now, and after it has been observed that the mathematical form of the perfect gas equations fit the real gas isentropic expansion when suitable numerical values of the corresponding constants and exponents are used. The other possibility, the use of the Redlich-Kwong equation of state, allows the calculation of the state variables after the normal shock when only the two constants of this equation and the specific heat of the corresponding perfect gas state (pressure approaching zero) are available. Both methods presented here require the numerical solution of a onevariable equation. In the first method the variable is the Mach number while in the second the specific volume.     

半导体制冷研究综述

半导体制冷主要是帕尔帖效应在制冷方面的应用,半导体制冷的主要优点是:制冷迅速,操作简单,可靠性强,容易实现高精度的温度控制,无污染等.尤其适用于制冷量不大,又要求装置小型化的场合.目前,广泛应用于国防、科研、工农业、气象、医疗卫生等领域,实现对仪器仪表、电子元件、药品、疫苗等的冷却、加热和恒温.本文通过半导体制冷与机械制冷比较说明半导体制冷的优点和特点.针对半导体制冷的特点和应用现状,通过研究国内外的相关文献,从影响半导体制冷效率的主要方面:理论、材料、结构方式、传热方式四个方面进行综述,从中总结了半导体制冷研究的热点和成就,归纳出当前半导体制冷研究存在的问题,提出影响半导体制冷的主要因素即:高优值系数材料,复杂的多参数工况以及冷热端散热方式与设计.为今后进行深入研究半导体制冷提供了可供借鉴的研究方向和方法.     

Networks of scientific journals: An exploration of Chinese patent data

We apply social network analysis to display the characteristics of the networks resulting from bibliographic coupling of journals by the Chinese patent data of United States Patent and Trademark Office (USPTO) between 1995 and 2002. The networks of journals in all fields, the three strongly science-based fields (i.e. Biotechnology, Pharmaceuticals, and Organic Fine Chemistry), and the three weakly science-based fields (i.e. Optics, Telecommunications, and Consumer Electronics), have been analyzed from the global and the ego views, respectively. We study a variety of statistical properties of our networks, including number of actors, number of edges, size of the giant component, density, mean degree, clustering coefficient and the centralization measures of the network. We also highlight some apparent differences in the network structure between the subjects studied. Besides, we use the three centrality measures, i.e. degree, closeness, and betweenness, to identify the important journals in the network of all fields and those strongly science-based networks.