CH4检测系统微弱信号处理电路研究

基于光谱吸收原理设计的CH4检测系统,气体吸收的信号比光源的噪声还要小,被淹没在背景噪声中.为改善检测系统的信噪比,针对非常微弱的气体吸收信号,基于微弱信号的锁定检测原理,以锁相放大器为核心,以同步积分器自动跟踪滤波,设计了检测系统的光电信号处理电路.结果表明电路输出电压与CH4体积分数呈线性关系,电路对CH4气体体积分数的检测极限为150×10-6.     

CO气体检测温度自补偿实现及硬件电路设计

提出了基于温度监测法的CO浓度检测软件自补偿方法；设计了检测系统的硬件电路，包括CO气体调理放大电路、STC12C5410AD单片机主控电路、LCD显示电路、温度测量及调理电路、PC机通信及程序下载电路；通过实验，得出了CO浓度测量系统的输入输出特性的线性拟合方程；通过CO测量系统的温度自补偿，误差为未补偿时的58．50％，提高了测量系统的温度稳定性，减小了温度变化带来的温度附加误差。     

基于NDIR技术的红外CO_(2)气体传感器研究北大核心CSCD

传统的CO_(2)检测系统体积大、响应时间长,难以满足工业开采中对CO_(2)气体的检测要求。文中以红外光源、气室、双通道热释电探测器和单片机为核心,设计了一款具有温度补偿功能的高精度红外CO_(2)气体传感器。采用单光路双波长的反射式气室结构,提高了整个系统的紧凑程度。在硬件方面,采用含光源驱动和信号调理电路的一体化模块,降低了电路耦合性,实现了传感器的微型化。在软件方面,采用差比值标定法建立温度补偿模型,消除环境干扰。实验结果表明:该传感器可以在0~30℃的温度下,对体积分数为0~5%的CO_(2)气体检测的最大测量误差小于±0.15%,且检测精度为3%,具有高精度、大量程,微型化、稳定性好等优点,满足工业开采等领域的实时监测要求。     

基于AT89S55单片机的水质监测系统设计

介绍基于AT89S55单片机的一种水质监测系统,该系统可以实现对水体的温度、电导率、溶解氧、浊度、pH值等参量进行连续监测。系统含有键盘和显示电路,可以对监测到的数据进行显示和设定报警限,同时现场监测数据通过通信电路可传递给控制室。     

高精密三通道微弱信号处理电路的设计

微弱信号的处理是智能检测与控制领域的难题,文中针对高精密气体传感器应用场景,设计完成了高精密三通道微弱信号处理电路。该电路主要应用于高精度非分光红外气体浓度检测,能同时进行氢浓度、二氧化碳(或一氧化碳)浓度、二氧化硫浓度的检测;根据应用场合,设计采用LTC1151CSW运放,经过严格的参数计算、逐级精密放大和滤波,设计了三通道微弱信号处理电路,经过仿真测试,电路信噪比高,总谐波失真(THD)为0,选频特性好,具有最佳平坦特性。通过实验测试,将该电路应用在非分光红外低硫检测系统,实现了1 ppm级别的信号检测。     

温室多点温度检测系统的设计及其仿真

为了改善西红柿温室温度检测的准确性,文章采用Proteus软件作为虚拟实验仿真平台,以AT89C52单片机、可编程分辨率的1-Wire数字温度传感器DS18B20和LCD1602液晶显示屏等为核心控制器件,设计了一款改进温室多点温度检测系统。该系统将4个DS18B20温度传感器与单片机之间采用单总线协议通信,并在总线上增加了10kΩ上拉电阻,以提高电平稳定性,还添加了电压探针和图表虚拟仪器,用于检测单片机与各个器件的通信情况,而且设计了友好的人机交互电路,可以实现手动设置阈值、多个温度数据采集及显示以及超出阈值范围报警等功能。仿真及其分析表明,该系统不仅实现了多点温度检测,而且具有检测精度高、稳定性强、显示直观、操作方便、实时监测等优点,对西红柿温室实时控制在最佳生长温度范围具有一定的参考价值。     

超低功耗水质pH检测仪设计

针对目前pH检测仪体积大,检测精度低、成本高等问题,文中设计了基于超低功耗单片机的pH检测仪。硬件电路分为pH值采集、温度采集、显示、通信及其电源组成,软件部分实现pH值在线温度补偿,MODBUS通信及其2,3点标定等功能,并开发了相应的标定监控软件实现在线仪表的标定和pH值监测,通过标准溶液测量实验可知该检测仪具有测量精度高、超低功耗、体积小等功能。     

基于STC89S52的花卉自动浇水系统设计

本系统设计实现一种基于STC89S52单片机控制的花卉自动浇水系统。该系统利用土壤湿度传感器、温度传感器、光敏传感器对土壤的湿度、温度和光照进行监测,并将其土壤湿度、温度、光照实时显示在LCD显示屏上。若超过设定的土壤湿度范围,便对花卉进行适时、适量的浇水。该系统主要包括硬件电路部分和软件模块。硬件电路部分主要由单片机最小系统、土壤湿度、温度和光敏传感器的信号调理电路、LCD显示电路、缺水报警电路、电机驱动电路等;软件部分主要选用C51语言编程,由信号采集模块、显示模块、报警模块和控制模块构成。经测试,系统运行良好,达到了所需功能。     

氯气检测报警器的设计

提出了一种以LM3S1138 Cortex-M3处理器为核心的氯气检测报警器的软硬件设计.采用恒电位电解式氯气传感器对空气中的氯气浓度进行测量.设计了恒电位电路、信号调理电路、人机接口电路和报警电路,同时采用软件温湿度补偿策略,实现温湿度自动补偿.该报警器测量氯气浓度范围为0～20 ppm,(1 ppm=10-6)测量精度达到0.1 ppm,响应时间＜60 s.具有时间显示,一、二阶报警和报警锁存等功能.可广泛应用于石油化工、造纸、纺织、水处理等场合.     

基于嵌入式油品含水率检测系统的设计

文中设计了一种基于嵌入式的油品含水率检测系统。该系统硬件部分设计了电容-电压转换电路、温度测量电路、串口通信电路以及单片机最小系统电路等。通过设计的电容传感器来检测油中的含水量,把含水量的多少转换为电容传感器电容值的变化,最后根据相应关系计算出含水率。经实验研究表明,该系统含水率检测精度达到了0.01级,测量精度高、稳定性好。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.