红外探测型香菇大棚煤气语音报警系统

应用传感器和电子技术提出了一款红外探测型香菇大棚煤气语音报警系统的设计方案.该检测系统采用半导体气敏传感器MQ-7检测环境中的煤气浓度;通过测量电路把煤气的浓度变化转换为相应的电压信号,由信号处理电路进行信号处理及浓度高低显示,一旦超过设定的煤气安全浓度值,当种植人员进入大棚时,红外探测电路控制报警电路发出语音报警信号,提醒种植人员采取安全措施.经实践证明,该系统具有工作可靠、灵敏度高等优点,效果良好.     

Grain separation loss monitoring system in combine harvester

Based on laboratory experimental results obtained with an axial threshing test-rig with tangential feeding, cumulative distribution functions of separated grain in axial and radial directions of threshing rotor were built. Based on the analysis of the relationship between grain separation loss and grain separation flux in an area under the concave, an indirect grain separation loss monitoring method is presented in this paper.Piezo-electric polyvinylidene fluoride (PVDF) film was selected as sensitive material to design a grain flux sensor. While grain and material-other-than-grain (MOG) separated in the monitoring area impact on piezo-electric PVDF films, different electric charges are generated. After signal progressing with a charge amplifier, frequency discrimination and wave shaping, the number of grain can be counted by a microcontroller (MCU) and the grain separation loss of combine harvester can be measured in real-time.Field test results indicated that the measurement errors of grain separation loss recorded by the monitoring system relative to the loss checked manually were less than 12%.     

水果分选台单片机测控系统的研究

在现有电子称重式水果分选台的基础上，对其测控系统进行了重新研制，将原有的PC机控制替代为单片机控制。在保持原有测控功能的前提下。操作更加灵活、简便，降低了设备成本。该单片机测控系统以AT89C51为核心。配以信号调理电路、A／D转换单元、信号输出电路和键盘／显示单元等几个部分。工作时，通过压敏式压力传感器采集水果重量产生的电压模拟信号，信号经放大、滤波、模数转换后，进入单片机进行运算处理，最终实现对水果的动态称重和实时分选控制。试验结果表明，该测控系统设计方案合理可行，操作简便灵活；能够预先设置分选等级。实现多种水果的分选。具有较好的通用性和灵活性。     

Laboratory Measurement of Mowing Machine Material Feed Rate

The main objective of this research was to evaluate two possibilities of material feed rate measurement of modern mowing machines equipped with conditioner. The machines are commonly used for harvest of grasses (Lolium multiflorum, Dactylus glomerata, Phleum pratense, etc.), clover (Trifolium pratense, etc.), alfalfa (Medicago sativa) etc.A mowing machine with finger conditioner was equipped with an electronic measuring unit for the purpose of our measurements. The mowing machine's conditioner shaft was supplied with strain gauges placed on a torque-meter and with a RPM optical sensor counter. Together with torque-meter the mowing machine was equipped with a curved impact plate mounted on the machine's material output.It was decided to arrange a laboratory measurement to obtain information about the dependence of conditioner power input and signals from the impact plate on material mass flow. A mixture of grass and alfalfa was used for our measurement.The measurements carried out proved that a very good linear relationship existed between the conditioner's power input, output frequency of the apparatus measuring impact force by means of the impact plate, and material feed rate through the mowing machine. The calculated coefficients of correlation were about 0.95. It is possible to differentiate a material feed rate difference of 0.5kgs^–1 using both methods. This accuracy should be sufficient for practical utilisation such as creating yield maps.     

猪舍NH3和H2S浓度自动控制系统的设计

应用传感器和电子技术,设计了猪舍NH3和H2S浓度自动控制系统。该控制系统采用半导体气敏传感器MQ-137和MQ-136检测猪舍内的NH3和H2S浓度;通过测量电路把NH3和H2S的浓度变化转换为相应的电压信号,由信号处理电路进行信号处理,一旦超过设定的NH3和H2S的安全浓度值,控制电路发出控制信号进行排气。该控制系统具有工作可靠、灵敏度高等优点,效果良好。     

联合收割机实时测产系统的抗振动干扰设计

收割机上的振动严重影响了测产的精度,研究联合收割机车身振动信号特征及其对测产传感器的影响,找出一套新的减振方法.分析了车上振动信号的特征,在此基础上,从谷物称重方式、传感器安装、电子硬件电路、经典算法滤波等方面进行了抗振动干扰的设计.经试验验证系统硬件可靠,软件算法滤波合理,动态测量误差可达到±5%以内,基本上满足了联...     

压电智能传感器力学模型的建立及数值模拟

以单片压电陶瓷（如锆钛酸铅,简称PZT）晶体、粘贴式和埋入式压电传感器为研究对象,从压电本构方程和结构动力学的振动原理出发,采用集总质量法推导出PZT传感器正压电效应的电荷表达式及等效刚度表达式,建立粘贴式和埋入式PZT传感器的简化力学模型,得到考虑多参数影响的电荷表达式。考虑黏结胶层阻尼吸收能量的作用,建立了胶层阻尼效应影响的传感模型,并求得压电传感器的电压表达式。数值模拟结果表明：在PZT传感模型中,利用压电方程和振动方程联合求解可以快速得到PZT的传感信号,而且PZT片的电压输出特性与作用力的大小及黏结胶层有关。通过测量和分析PZT传感器输出电信号峰值与频率的变化,并与数值分析结果进行对比,证明了运用所建立的传感模型能够有效地模拟检测PZT的正压电规律。     

压电振动发电机理论建模与发电性能研究

为了促进农业生产的现代化和智能化,研究环境信息采集设备—无线传感器网络新的供能方式。以压电方程为基础,结合比能特性,建立了悬臂压电梁发电能力数学模型,分析对比了单晶、双晶串联和双晶并联压电梁输出电压、电荷与电能,最后通过有限元仿真验证,分析结果表明:外力激励环境中,应尽量增加悬臂压电梁长度,减少宽度,同时为了获得较大的输出电压及电能,应优先选用双晶串联压电梁。     

光电比色实验电路调整及传感器的使用

通过试验，对常用电路进行了改进与调整，并适当选择和使用传感器，提高了测量的精度并使误差减小。本文在介绍常用电路与传感器性能的基础上，指出了通常测量中易出现的问题和原因，给出了解决实际问题的方法和措施。     

基于霍尔效应的微小压强测量装置的设计与实现

针对化工液体的微小压强测量中所存在的测量复杂、精度低的问题，设计一种基于霍尔效应的测量流体微小压强变化的装置。该测量装置通过前端受力装置来承受液体压强的变化而产生一定的位移，并转换成霍尔电动势，经放大调理电路，最后接电压表显示相应的电压值。根据输出电压与液体压强之间的关系即可得到相应深度的压强大小。在实验中，电压表精确到1mV，最小可测量到0.792Pa的压强变化，其测量精度较高。该装置体积小、通用性强，具有较好的应用前景。     

Improving the accuracy of estimating grain weight by discriminating each grain impact on the yield sensor

This study was aimed at accurately estimating total weight of harvested grain on a combine by simply attaching a small yield sensor in the grain tank and by processing the output of the sensor. The yield sensor was first installed in a grain tank of a 1.2 m-swath Japanese-style (head-feeding or jidatsu) combine, and the weight was estimated from individual impulses received at each rotation of a grain-releasing device i.e. an auger blade. A non-linear relation was assumed between the weight of grain released and the impulse received, and the parameters of the non-linear model were optimized to minimize the sum of squares between the estimated and actual weight of grain accumulated at each run of the combine. A threshold for the output discriminated between actual release and no release of the grain from the auger blade. The appropriate range of the threshold was 4–6 times the root-mean squared output of the sensor without throughput (F _rms ) of grain. The aim was to enhance the accuracy of the estimation of grain weight by disregarding signals that did not relate to the accumulation of grain in the tank. Two methods of calculating the impulses were proposed after the discrimination: “successive addition” and “interval addition”, and two non-linear models of converting impulses into the weight of grain: “odd function model” and “positive function model”. The use of the odd function model with the impulse calculated by the interval addition was the most robust, and root-mean squared relative errors of calibration and validation were both stable and around 2.5 % at a threshold of 5F _rms . In the confirmatory experiment with a larger 1.8 m-swath Japanese-style grain combine equipped with the same sensor, the odd function model with the interval addition achieved root-mean squared relative error of 3.6 % at calibration and 4.4 % at validation at a threshold of 5F _rms .     

SJ—1型数字粮食水分计的研制

Sj—1型数字粮食水分计采用平行板电容器作为传感器,较通用的圆柱形电容传感器性能稳定。测量电路及显示电路均采用数字电路。非电量经A/D转换后,通过EPROM查表的方法,实现了数据的线性化,测量精度高。     

管输原油含水率超标指示与报警

介绍了一种管输原油含水率超标（≥２．５％）指示与报警仪器的工作原理与结构,由发射天线和相应输油管壳组成的敏感探头的电容量随原油含水率的变化而改变,并作为谐振电路的调谐电容,谐振电路通过电感耦合,从稳定的晶体振荡器获取振荡电压,当敏感探头电容改变时,谐振电路的阻抗发生变化,即振荡电压发生变化,这个变化经检波电路转换为直流电压变化输出并显示。     

水稻谷粒考种参数自动提取装置及试验

【目的】传统考种方法测量精度和效率难以满足现代水稻育种研究的需求,设计一种水稻谷粒图像与质量信息同步采集装置,实现水稻谷粒考种参数的自动提取。【方法】采用掩膜法自动提取稻谷区域图像,根据稻谷投影面积、数量规律获取稻谷总粒数;根据空粒、实粒颖壳轮廓差异识别空粒;基于角点间距均值标定法,结合轮廓最小外接矩形法获取粒长、粒宽,结合链码法获取粒周长;采用正方形面积均值标定法结合像素累加法获取粒面积。分析摄像头高度、谷粒数量、谷粒种类、规则图形类型对谷粒性状参数提取精度的影响。【结果】摄像头高度对稻谷总数、空粒数、长、宽测量精度有明显影响,稻谷种类对宽度测量精度有明显影响,规则图形类型对周长和面积测量精度有明显影响。采用本文提出方法测量总粒数、空粒数、粒长、粒宽、粒周长、粒面积的决定系数(R²)分别为0.998 30、0.987 80、0.996 10、0.782 90、0.995 10和0.999 98,测量的平均精度分别为99.47%、87.17%、96.55%、96.36%、98.00%和95.86%,测量效率为16.52粒/s。【结论】本文所采用的稻谷谷粒考种参数自...     

半导体温差发电器发电电气特性试验研究

文章根据塞贝克效应(Seebeck effect)、珀尔帖效应(Peltier effect)、汤姆逊效应(Thomson effect)原理,制作了半导体温差发电器系统,通过试验测试获得了在不同温度等级下的电气特性。结果表明,开路电压和负载电压随温度升高呈线性上升趋势。当温度一定时,电流随负载变化呈几何对数增长,并找到了电压越低输出功率越大的功率特性。     

溴甲烷质量浓度检测系统的设计及试验研究

针对熏蒸处理中检测溴甲烷质量浓度时,基于单个通用型热导式传感器TCS208F检测结果易受容器内温度、相对湿度及CO_2条件干扰的问题,设计研发了溴甲烷质量浓度检测系统,系统包括热导式传感器TCS208F、数字化温湿度传感器和红外CO_2传感器,采用多元线性回归方法研究了容器内温度、相对湿度、CO_2及溴甲烷对TCS208F模块输出电压的影响,建立了溴甲烷质量浓度估计值与TCS208F模块输出电压、温度、相对湿度及CO_2体积分数检测结果之间关系的数学模型。试验结果表明:使用该溴甲烷质量浓度检测系统检测溴甲烷质量浓度时,系统将自动采集容器内温度、相对湿度、CO_2及TCS208F模块输出电压值,经数学模型处理后系统所得的溴甲烷质量浓度估计值与经安捷伦网络气相色谱仪6890N的检测结果偏差不超过1.1g/m3。在检验检疫口岸熏蒸处理中使用该检测系统检测溴甲烷质量浓度具有实用性。     

基于PVDF双压电薄膜的油菜播种监测系统的设计与试验

针对苏南地区油菜播种一体机作业过程中种子监测困难的问题,设计了一种基于PVDF双压电薄膜的油菜单粒精密播种机播种性能监测系统。系统通过播种机安装在测速轮上的编码器采集机具作业速度,结合设定的目标播量,得到理论排种间距,采用聚偏二氟乙烯(PVDF)压电薄膜监测装置,采集油菜种子落粒数。为了滤除机器振动信号干扰,设置参照压电薄膜,通过逻辑运算模块降低振动干扰,采用施密特电路迟滞原理消除比较器抖动干扰。系统采用STM32F103VBT6单片机作为中央处理器,结合设定的理论株距、相邻脉冲电压信号的时间间隔与播种机前进速度,计算得出播种量、排种速度、漏播率与重播率等性能指标。试验台试验表明,在26.5~42.2 r/min排种轴转速下,系统对排种量的检测精度不低于96.4%,漏播检测精度高于95.8%,重播检测精度高于98.4%;振动频率8~16 Hz条件下,系统播量检测精度高于95.2%。     

Evaluation of a UAV-mounted consumer grade camera with different spectral modifications and two handheld spectral sensors for rapeseed growth monitoring: performance and influencing factors

The objective of this study was to evaluate the crop monitoring performance of a consumer-grade camera with non-modified and modified spectral ranges which are commonly used in low-altitude unmanned aerial vehicle (UAV) platforms. The camera was fixed sequentially with seven types of filters for collecting visible images and near-infrared (NIR) images with different center band locations and bandwidths. Meanwhile, field-based hyperspectral data and normalized difference vegetation index (NDVI) measured by a GreenSeeker handheld crop sensor (GS-NDVI) were collected to examine the accuracy of rapeseed growth monitoring in terms of vegetation indices (VIs) derived from UAV images. Results showed that the UAV-based RGB-VIs and optimal NIR-VIs had similar accuracy for predicting GS-NDVI. Moreover, similar results were achieved based on the hyperspectral data, indicating the importance of spectral characteristics for GS-NDVI estimation. However, the UAV-based results also indicated that the performance of VIs derived from the band combinations containing longer NIR center wavelengths and narrower bandwidths was obviously poorer than that of the RGB-VIs. The image quality of the NIR band was also found to be inferior to the visible band based on quantitative analysis, which also revealed that image quality had great impact on UAV-based results. Image quality was then related to the effects of camera exposure, spectral sensitivity, soil background and dark areas. The results from this study provide useful information for camera modifications by selecting appropriate filters that not only are sensitive to crop growth, but also ensure image quality.

     

Development of a yield monitoring system for citrus mechanical harvesting machines

A load cell based yield monitoring system was developed for the Oxbo citrus mechanical harvesting machines. The yield monitoring system consisted of a GPS receiver, a mass flow sensor and data processing and storage units. The mass flow sensor consisted of four load cells attached to a carbon-fiber plate which sensed the impact force created by the oranges hitting the plate. A mathematical model was developed to relate the impact force to fruit mass. Laboratory tests were conducted on a test rig that replicated the flow of oranges to measure the accuracy of the system under a controlled environment. The system performed very well under laboratory conditions (R ² = 0.99 and an average error of 3.3%). In addition, a field test was conducted in a citrus orchard in Florida to evaluate the performance of the system under field conditions. Of the 72 rows used in the field test, the first 10 rows were used to calibrate the computed weight. A correlation of R ² = 0.97 between the actual weight and the computed weight was found from the field data with an average error of 7.81%.     

磨削自适应控制中在线测量尺寸和圆度的精度分析

本文用富里哀分析的方法,建立了磨削自适应控制系统中在线测量圆度的数学模型,分析了传感器静动态特性及工艺因素对在线测量尺寸和圆度的精度影响。通过大量对比实验,建立了传感器在线测量和圆度仪离线测量圆度之间的函数关系。