基于温室微灌的双湿度自动测控系统设计与研究

以AT89C51单片机为核心的温室微灌双湿度(土壤湿度和空气湿度)自动测控系统,能够实现多路采集输入和多路输出控制功能,通过传感器实现自动闭环和开环等湿度调控模式,并具有系统故障报警和参数越限报警功能.系统具有较高的可靠性,可进行二次开发.     

湿度计的检验方法

一、检验中所需的湿度标准 在检验湿度计时必须具备一定湿度的环境气体和能够校准环境气体湿度的标准湿度计。 具有一定湿度的环境气体的调制方法有如下几种: (1) 改变潮湿空气的压力和温度; (2) 分别测量乾燥空气和被水蒸气饱     

基于89C2051单片机的土壤湿度控制电路

不用湿度传感器 ,根据湿度的变化输入给单片机一个信号 ,单片机根据信号电平的高低输出控制信号 ,控制电磁阈的断通 ,以决定是否给土壤喷水 ,从而实现对土壤湿度的控制     

基于MSP430单片机的手持式CO检测仪设计

文章基于MSP430系列单片机设计实现了一款手持式一氧化碳(化学式:CO)检测仪。检测仪选用电化学式CO传感器作为气体浓度采集装置,将其采集的浓度信号以电信号输出,并通过4位数码管实时显示CO气体浓度值,测量精度可达到1PPM。同时可根据需要修改报警值,当浓度值超过报警值时,检测仪发出报警信号。     

燃气泄露检测的CO-CH4气体变送器

以MSP430F149单片机为核心,研制了1台应用于燃气泄漏检测的CO-CH4气体变送器,实现对应CO气体0～200×10-6、CH4气体0～5 000×10-6的0～3 V线性电压输出,分辨率分别为20×10-6和500×10-6.详细叙述了气体传感器的采样时序产生电路,放大电路以及线性化模拟电压的输出方法.     

浅谈高温气冷堆核电站气体湿度监控装置设计

本文描述了高温气冷堆核电站气体湿度监控装置的设计,该装置的组成包括：用于将一回路高温取样气体冷却至一定温度范围内的冷却控制单元;对冷却后的气体进行取样的取样单元;对取样单元内气体湿度进行检测的湿度探测单元。该装置的湿度探测单元包括感湿元件和用于将感湿元件输出信号转为反应堆保护系统可识别信号的信号转换电路,采用纯硬件结构实现湿度信号的采集和转换,满足了安全级设备的可靠性要求,响应速度快且实现放射性气体零排放。     

基于冷镜式露点仪的湿度标准装置测量不确定度评定

高精度露点仪是一种高准确度的湿度测量仪器是国家湿度量值传递和国际比对通用的传递标准。而双压法湿度发生器能够连续输出恒湿气体,也是传递湿度量值的标准设备。本文讨论了高精度露点仪与双压法湿度发生器配套使用时,标准装置产生测量不确定度的多种因素。从双压法湿度发生器的工作原理出发,建立数学模型,并统一采用露点温度的形式,对本湿度标准装置的测量不确定度进行了评定。     

基于DDS的数字波形发生器设计与实现

研究基于直接数字合成(DDS)技术的任意波形发生器(AWG)系统设计。以DDS技术为核心,采用AT89C51单片机作为系统控制部件,利用软件编程实现电压输出的频率预置、步进,输出标准波形。整个系统运用C语言编写相应内部程序,结构紧凑,电路简单,输出波形稳定性好,系统可扩展性强。使用数字信号,克服了模拟信号冗余量大不易处理的缺陷,操作实践表明该系统能可靠运行。     

智能湿度计

本文介绍了一种以8031单片机为核心的智能化湿度计。该仪器根据干、湿泡法测湿原理,利用标准铂电阻测温的精确性,实现高精度测湿,以代替常规的湿度传感器或AD590干、湿度泡法测湿。     

电容式信号线性转换电压输出的应用电路CAV444

文中介绍一个电容式信号测量并输出线性的电压信号的应用电路CAV444.在19～2 200pF的很大的电容变化范围内,输出线性的差分电压信号,工作电压5 V,非常适合后级的信号再处理电路比如AD转换或单片机采集或者直接变送4～20 mA输出.应用于电容式液位物位的测量、湿度传感器、物质的含水量等.     

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...     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.