汽车尾气检测用Mg_Co_Ni_O 氧传感器材料的研制 氧传感器材料的研制

本文介绍了汽车检浏用一一一氧敏材料发现的掺入可提高材料的 稳定性及电导激活能, 扩宽材料检测的氧压范围等且当。时, 材 料具有最好的氧敏特性米用高温多次预烧的工艺可获得晶粒尺寸均匀、气孔率适当的 瓷休     

汽车用氧敏新材料-Pt修饰La掺杂的SrSnO3的研究

为了有效地利用“三效”汽车尾气净化催化剂达到减少汽车排气污染的目的,必须力求汽车发动机在空气和燃料接近化学计量比的条件下工作。本文开发了一种可用于监测汽车发动机在化学计量空燃比附近工作的氧敏新材料—Pt 修饰和 La 掺杂的 SrSnO_3。我们发现 La 的掺杂可明显提高 SrSnO_3材料的氧敏性能,其中 La_(0.2)Sr_(0.9)SnO_3在800℃具有最好的氧敏特性。除 La 掺杂外,Pt 的修饰对材料氧敏性能的改善也起到了显著的作用。在低氧分压操作区域,由于 Pt 的引入使材料的氧敏性能与温度的依赖关系大大减小,其中 Pt/La_(0.2)Sr_(0.9)SnO_3样品的氧敏响应几乎与温度无关,因此用这种材料做成的“λ”氧传感器不需要加温度补偿,这样使传感器的结构更简单,价格更便宜.我们借助于程序升温吸脱附等方法研究了样品上的可活动氧与氧敏性能的关系,因此阐明了 Pt 的修饰和 La 的掺杂的作用.     

汽车用氧敏新材料—Mg掺杂的SrTiO3的研究

本文研究了控制汽车发动机在燃料稀薄燃烧区域工作的氧敏新材料—Mg 掺杂的SrTiO_3。在空气和丙烷燃烧排出的废气中测量了样品对废气中氧的敏感及应答特性。在燃料稀薄燃烧区域(10~2Pa相似文献   

TiO_2制备方法对气敏性能的影响

使用sol—gel法和TiCl_4水解法制备TiO_2,研究了不同方法合成的TiO_2对乙醇、丁烷、石油气,一氧化碳和氢气的气敏效应。一、引言近年来,TiO_2作为一种多功能材料,日益得到重视。它可用于氧敏材料,也可用于检测可燃气体和湿度等。TiO_2的电导率可能是由于在晶格中出现氧空位或是填隙     

1993年嗅敏文献(摘译自美国工程索引)

载论文125篇,包括气敏、电极材料 安培敏、生物敏、湿敏、氧敏、触媒气敏、SAW器、蒸所检测器、化学检测用表面胞质团共振、压电、电化学敏、嗅敏系统、电位敏、氨敏、臭氧敏、光纤传感器、毒敏、离子     

α—Fe_2O_3基气敏材料的催化性能研究

一、前言气敏现象是一个涉及面较广的复杂现象,它与半导体物理、表面科学和催化效应等密切相关。现已发现催化效应在气敏半导体陶瓷材料检测气体方面有重要作用,材料的气敏效应与催化效应之间有平行关系。氧化铁系气敏机制,目前多从体效应角度来描述:r-Fe_2O_3与还原性气体作用,生成r-Fe_2O_3与Fe_3O_4组成的低电阻体固溶结构     

汽车空燃比控制用的TiO2 系厚膜氧传感器

本文介绍了掺五价金属氧化物(M_2O_5)对TiO_2氧敏材料电阻率的影响,测定了半导化后的TiO_2材料不同温度下的氧敏特性,并讨论了其敏感机理.     

PCVD法超微粒α—Fe2O3的敏感特性

普通的α—Fe_2O_3,由于其所具有的高稳定性,对气体是不够敏感的。由于加入了SO_4~(2-)和 M~(4+)(M=Sn,Ti,Zr)使其微细化后成了具有实用价值的气敏材料。通常被用于检测烷烃等可燃性气体。在此基础上,用超微粒 Au 敏化的 Ti—α—Fe_2O_3材料实现了对 CO 的选择性检测。研制超微粒化、薄膜化和复合化的α—Fe_2O_3新型材料是当前气敏材料研究领域的一个重要课题。一、实验方法利用文献的方法合成超微粒氧化铁,并制成管状气敏元件,经热处理获得所需气敏元件。采用外加热动态脉冲法测试其气敏性能,用 Ra/Rg 表示气敏元件的灵敏度。     

TiO_2系薄膜型氧敏材料的研究与发展综述

介绍了TiO2薄膜型氧敏材料的特性、氧敏机理及发展优势。就TiO2薄膜型氧敏材料的制备新方法和几种新型TiO2系薄膜以及相应的氧敏性能等重要方面进行了探讨,并对今后的研究与发展方向提出几点建议。     

TiO_2—Nb_2O_5系复合氧化物半导体的氧敏特性

简要介绍TiO_2—Nb_2O_5复合氧化物半导体的氧敏特性,指出作为理论空燃比(A/F)检测用氧敏材料TiO_2 80mol％以及Nb_2O_595mol％的组成要比单一的TiO_2和Nb_2O_5具有更高的灵敏度和更好的温度稳定性。结构分析指出它们分别是掺Ti的Nb_2O_5的固溶体以及掺Nb的TiO_2固溶体与复合氧化TiNb_2O_7的混合体,并作简要的讨论。     

挥发性有机物污染的水质化学计量学研究

选择不同的样间距与类间距度量方法，对30种水样所含的挥发性有机物(VOCs)进行聚类分析研究。结果显示16种河水可分为3或4类；14种自来水、瓶装饮用水分为4类。通过比较描述性统计量及聚类结果，该数值分类方法还提供了一种水质定量分级评价结果：16种河水按VOCs含量高低分级评价为三个等级：严重污染、中等污染、轻微污染；另14种饮用水样也评为三个等级：较差、中等、较好。化学计量学方法可对不同水样所含VOCs污染情况做有效的分类与量化分级评价。     

Study on fabrication of high aspect ratio MEMS microparts using a compact SR beamline

 A compact beamline dedicated to hard x-ray deep lithography for fabrication of high aspect ratio MEMS microparts has been developed. The exposure stage was only 3 meters away from the synchrotron radiation (SR) source so that a relatively high photon flux could be achieved with a compact super-conducting SR source. The deep lithography using PMMA resist could be as deep as 1000 μm and the maximum aspect ratio achieved was about 50. The throughout for the 200 μm-deep lithography was found to be on the order of 5 cm²/h using the membrane-free mask under the routine SR conditions. Templates with the high aspect ratio microstructures have been made of the PMMA resist based on conducting substrates and applied further to electroforming to create metallic microstructures. In order to fabricate microparts for the MEMS applications, we have concentrated on development of masks for the hard x-ray deep lithography. The masks now can be made to have the 8 μm-thick gold absorber on the 2 μm-thick SiC membrane. Received: 25 August 1997/Accepted: 3 September 1997     

基于FPGA的程控滤波器设计与实现

设计一个由现场可编程门阵列(FPGA)控制的滤波器。该滤波器主要由3个模块组成:前置放大、滤波电路、FPGA显示与控制电路等利用FPGA作为放大器及程控滤波器电路中继电器组的控制模块,实现了可编程放大参数的设置以及低通和高通滤波截止频率的数字控制。基于FPGA技术,使得该系统具有抗干扰能力强,可靠性好等优点。对系统进行了测试,结果表明符合设计要求。     

一种新型金属复合氧化物半导体气敏材料体系

用ＮＨ４）２ＣＯ３作沉淀剂制得Ｃｄ：Ｓｎ＝１：１的粉料，经７５０℃、１５ｈ热处理可得单相钛铁矿型β－ＣｄＳｎＯ３。元件的电导－温度（Ｇ－ｔ）特征表明β－ＣｄＳｎＯ３为典型的表面电阻控制型气敏材料，无需掺贵金属催化剂就对还原性气体响很高的灵敏度。因此，β－ＣｄＳｎＯ３很有希望作为一种新型的气敏材料体系。     

An ergonomic study of work methods and physical disorders among professional butchers

Butchers considered that the back and the upper extremities were subjected to high loads from their work. Of the 92% with reported physical disorders, 80% had pains or complaints from more than one body area. Most frequent were disorders of the back and shoulders. 50% of the butchers had been on sick leave due to their disorders. By ergonomic analysis of the work, several work tasks which caused high loads on those body parts in which disorders had occurred were identified. The high loads were found to have the following main causes, which occurred together in many work situations: (1) Exertion of high forces when cutting the meat. (2) Frequent and heavy manual materials handling. (3) Inappropriate working postures. It appeared from the study that the workload on the butchers was unnecessarily high and that it could be the main reason for the high frequency of disorders amongst them. The strain on them was to a large extent caused by bad working postures, which could be improved by introducing improved equipment. The equipment should be such that the working-height may be adjusted both to the individual and for the task performed.     

改进的红外图像行人检测和交叠率算法

行人越界入侵报警是十分普遍的应用场景,尤其是在安保领域.本文设计了一种改进的红外图像行人检测和交叠率算法,两者结合可以实现对行人的越界报警.本方法主要由三部分组成：红外图像行人检测算法、目标分类算法、交叠率算法与报警逻辑.红外图像是为了尽量克服环境影响,并且在夜间也具有良好的显示与图像采集功能;行人检测是通过YOLOv3算法和基于方向梯度直方图（HOG）特征的多层感知器（MLP）二分类来实现;报警算法与逻辑是计算目标的候选框与报警区域的交叠率,再进行逻辑判断.实验表明,本方法准确性高,报警准确率可达91%,有良好的应用价值.     

An order-reduction method for extraction of eigenvalues of dynamic systems

An order-reduction method is proposed by means of which a part of the eigenvalues of a given large system in n-D space can be solved conveniently. They may be: (1) the lowest r eigenvalues; or (2) the highest r eigenvalues; or (3) a few eigenvalues nearest to a simplified value by their norms. The algorithm associated with this method is applicable to many kinds of practical problems due to its simplicity and high accuracy. It will be seen that with this algorithm the problem in the original n-D space is reduced into one in much lower r-D subspace, from which the required eigenvalues of the original system can be extracted easily and accurately from the reduced model. This method could also be used conveniently in a structural elastic buckling problem.     

An electromyography study in three high risk poultry processing jobs

This paper presents the results of a muscle load study of poultry processing operators performing three different jobs: basket packing, cutting/packing and trimming. Eighteen operators participated in this study. Surface electromyography (EMG) was recorded from bilateral upper trapezius, right forearm flexor and extensor muscles during the job performance. Results showed high muscle loads of the forearm flexor and extensor muscles for the operators conducting all three jobs. The static loading for both trapezius muscles was low (<1% MVC). However, the peak load could be up to 24% MVC on the upper trapezius muscles in some individuals. The job of cutter/packer had significantly higher trapezius loads, while trimmer operators had significantly higher peak forearm flexor and median extensor loads than the other jobs. Lack of ergonomic consideration of workstation designs may be one of the reasons causing the high trapezius loads for some of the cutting/packing operators and basket packers. Repetitive pinching operations and the frequent use of knives in cutting may be a major contributing factors causing high forearm muscle loads. An efficient knife sharpening program or alternative cutting methods (mechanical knives or scissors), modified processing procedures in order to reduce the pinching effort, and properly adjusted workstation may be able to improve the muscle loading conditions for the high risk poultry processing jobs.

Relevance to industry

Detailed quantitative information on the muscle loading of poultry processing operators provides insight to the risk factors causing musculoskeletal disorders and may be used to help evaluate ergonomic intervention measures for reducing these risk factors.     

大功率低成本新型混合型有源滤波器的电流检测方法*

提出一种逆变器采用三相四开关结构的大功率新型混合型有源滤波器,这种结构的滤波器适用于中高压系统的无功补偿和谐波抑制。给出了系统的拓扑结构,对三相四开关逆变器的结构原理进行了分析。提出了一种单相电流的谐波检测方法和基于能量平衡的直流侧电流的检测方法,这种检测方法计算时间显著减少,系统只需检测两相电流和控制四个开关元件。将基于三相四开关逆变器的新型混合型APF进行仿真实验,仿真结果表明,提出的滤波装置具有良好的谐波波抑制和无功补偿性能,直流侧电压平衡稳定,而且大大降低了整个装置的成本和功耗。     

基于局部指纹曲面片的点云三维物体识别

提出一种新的基于局部描述符的点云物体识别算法。算法根据点云的位置信息提取出邻域以及曲率信息,进而得到形状索引信息。根据形状索引提取到特征点,在每个特征点根据样条拟合原理得到测地距离和矢量夹角分割曲面得到曲面片集。每个曲面片的等距测地线构成了曲面片指纹,通过矢量和半径的变化描述,可以把每个模型物体得到的曲面片集描述存入数据库。对于给定的一个物体,根据上面步骤同样得到其曲面片集描述,通过和数据库中模型物体曲面片集的比对,得到初始识别结果。对每对初始识别结果进行对应滤波后,通过最近点迭代方法得到最终的识别结果。最后通过具体的实验说明了算法的有效性和高效性。