单原子材料的制备、表征及其在气敏传感器中的应用进展

气敏传感器技术的发展对于人类社会发展具有积极的作用。近年来的研究显示,原子级分散的材料具有超高的活性、独特的电子结构和量子尺寸效应等,故将某些单原子负载在一定的气敏材料上,将会显著提高气敏材料的气敏性能。本文综述了近些年来国内外单原子材料的制备和表征技术及其在气敏传感器中的研究进展,分析了单原子材料的性能优势、单原子负载策略、分析方法、气敏性能、气敏机理等,同时探讨了存在的问题以及单原子材料气敏传感器在未来的发展趋势,最后对单原子材料在气敏传感器中的应用发展提出了相关的一些看法。     

纳米ZnO气敏传感器研究进展

半导体金属氧化物气敏传感器被广泛应用于有毒性气体、可燃性气体等的检测.ZnO是一种重要的半导体气敏材料,特别是纳米ZnO,由于其粒子尺寸小,比表面积大,成为被广泛研究的气敏响应材料之一.简要介绍了纳米ZnO气敏传感器的气敏机理、主要特性,综述了通过新型纳米形貌、结构制备以及元素掺杂改性提升纳米ZnO气敏性能等方面的研究进展,并进一步指出了纳米ZnO气敏传感器研究中存在的问题和未来的研究方向.     

氧化锌掺杂改性研究进展

氧化锌半导体材料既是优良的压电材料,也是性能优异的多功能材料,在太阳能电池、显示器件和气体传感器等电子元器件领域以及光催化降解有机污染物领域的应用受到重视。综述了不同掺杂元素对氧化锌材料的光、电、磁、气敏以及变阻等特性的影响,针对氧化锌掺杂的研究现状,提出了今后的研究方向:研究掺杂原子的选择定则;加强掺杂氧化锌材料的应用研究;深入研究氧化锌掺杂引起半导体特性改变的机理。     

SnO_2复合薄膜甲烷气敏传感器研究进展

甲烷是具有稳定四面体分子结构的碳氢化合物,其键能大、分解困难且活性低,是煤矿安全生产的主要障碍及一种温室气体。SnO2半导体薄膜制备工艺简单、成本低廉、性能稳定,是甲烷传感器研发的主流气敏材料。科技人员进行了很多相关研究以提高传感器的性能,如新气敏材料的研究、催化剂/添加剂的使用、气敏机理的探索、传感器结构改进及气敏膜的表面修饰改性等。本文从气敏膜制备与改性、传感器结构设计及气敏机理研究三个方面,综述了近年来SnO2复合薄膜甲烷传感器的研究进展,结果表明:①应开发复合型金属氧化物半导体及高分子气敏材料,以提高灵敏度、选择性与稳定性;②研发微型智能传感器是未来发展的主要方向,而自组装技术应可用于制备金属氧化物半导体薄膜气体传感器微纳阵列;③气敏机理应与实验测试、材料设计及器件制备进行对照研究。     

铁氧化物薄膜气敏材料的制备及性能研究评述

本文综合介绍近年来在铁氧化物薄膜气敏材料制备方法、性能方面的研究新进展 ,探讨了各种方法的特点。提出了今后铁氧化物气敏传感器的研究及改进方向     

苯系物(BTEX)检测气敏材料研究进展

金属氧化物半导体传感器因具有体积小、成本低廉、使用方便等优点,越来越受到研究者的关注并被用于有毒有害气体的监测。传感材料是气敏传感器的核心,本文综述了近年来氧化物半导体BTEX气敏传感材料的研究进展,对传感材料的微结构、负载/掺杂改性、气敏性能、气敏机理及存在的问题进行了分析,并探讨了其下一步发展趋势。     

高性能金属氧化物基气敏材料研究及应用

金属氧化物基气敏材料是新型气体传感器的核心组成部分,近年来发展迅速。围绕金属氧化物基气敏材料的作用机理、特征参数、性能强化及工业应用进行了阐述和展望。重点分析了金属掺杂、结构薄膜化以及多元复合技术在强化金属氧化物基气敏材料性能方面的研究。在此基础上,对今后的研究方向和趋势作了展望。     

丙酮气敏传感材料的研究进展

丙酮是一种有毒有害的有机气体,广泛存在于工业生产及家居生活中,同时也是糖尿病的诊断物之一,因此准确实时的丙酮检测手段是安全生产和人体健康所迫切需要的。金属氧化物半导体气体传感器具有灵敏度高、成本低、可靠性高等优点,在有毒有害气体检测领域应用广泛。本文综述了近年来丙酮气敏传感材料的研究进展,对气敏材料的结构与形貌、气敏机理与改性手段等方面进行了介绍,分析了其研究现状以及未来的发展趋势。     

纳米ZnO的固相合成及其气敏特性

以草酸为原料,与醋酸锌进行固相反应制得前驱化合物,进而热分解得到气敏材料氧化锌。将稀土元素中的镧和钕的氧化物以固相及液相两种合成方法添加到ＺｎＯ气敏材料中,并对材料的粒径、气敏性质进行了测定和表征．实验结果表明,用这种方法制备的氧化锌在低的工作温度下对乙醇气体的灵敏度较高,而且选择性较好,具有一定的应用前景．     

基于磁控溅射的金属氧化物气敏薄膜的研究进展

气体传感器的应用越来越广泛,对气敏材料的研究也越来越深入。磁控溅射法是生产气敏薄膜的一种主要方法,本文重点介绍了用磁控溅射法制备的几种金属氧化物薄膜(SnO2、WO3、ZnO、TiO2、In2O3和NiO等)的气敏性能及其研究进展,对其它薄膜做了简要概述,并提出了目前在气敏薄膜研究中存在的问题。     

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.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.