基于虚拟仪器的粮食水分检测系统神经网络温度补偿

在进行粮食水分检测过程中发现,温度变化对系统的输出值影响很大,从而影响系统性能和测量准确度。为消除温度对水分测量值的影响,在虚拟仪器软件平台上采用人工神经网络法对水分检测系统进行温度补偿,即通过对神经网络建模达到消除温度的影响。     

微波水分检测仪在原烟烟包含水率快速检测中的应用

为实现原烟烟包含水率的快速检测,引进了MW-T微波水分检测仪及配套的检测系统,并采用Cgk评价法对微波水分检测仪进行效果能力评定,确定了微波水分检测仪模型建立的方法。结果表明:建立的微波水分检测模型的R2为0.845;微波水分检测仪Cg和Cgk值分别为1.76和1.55;烟包排列方式与密度对于微波水分检测仪检验烟包含水率无影响;微波水分检测仪检验烟包含水率与行业标准烘箱法检验水分差值绝对值平均值为0.38%,测试样本中,96.25%的样本差值分布在±0.75%之内。     

粮食水分测量技术与高性能电子水分仪

1　粮食水分测量技术发展状况作为经典的物料水分测量技术 -烘干称重法 ,至今仍在世界各国作为粮食水分检测的标准方法(以下称“标准法”)。由于它按照水分值的定义安排检测工序 ,对各种不同类型物料都按统一规范操作 ,其缺点在于测量周期太长。随着科技的不断发展 ,早在上世纪 4 0年代就出现了大量新型的快速检测技术。概括起来可分为电子法 (利用介电、电导、介质损耗等物料电特性 )、核磁共振法、微波法、双色及三色红外法、磁参量法、静电法、声学法、放射线法、物化反应法等等。到了 80年代中期 ,国外开发研制了高性能的电子水分仪。例…     

利用扩频技术进行粮食水分测试的双通道微波技术

本文是将扩频码发射和接收技术应用到粮食水分检测装置中,通过直接测量伪码信号的相位和功率值,获得高精度的微波信号延迟量和功率衰减值,从而得到粮食的含水量。该方案避免了传统微波测量,需利用射线测容重对含水量进行修正的缺点,提高了测量的准确度,降低了测量的难度。     

粮食水分检测装置设计

开发了一套对射式微波水分检测装置。以STC89C52芯片为主处理器,控制各部件执行顺序。为保证物料装载的一致性,采用光电开关控制装载量;为消除温度影响,实时采集样本料温,建立温度补偿模型;为避免微波产生热效应,采用时序控制采集温度及微波信号,以实现粮食水分的准确测量。经实验验证,物料实际水分与微波检测水分之间的相关系数0.96,满足实际检测要求。     

微波烟支密度分布检测仪测量特性分析

为了分析微波烟支密度分布检测仪的测量特性,研究接装纸类型、宽度、位置以及滤棒填充长度对检测结果的影响,提出一种能够有效降低测量误差的样品制作方法,建立密度测量值与填充长度关系模型,并指出减小微波谐振腔的厚度理论上能够提高检测精度,为烟支密度分布检测设备的进一步优化提供了参考依据。     

微波水分检测及其在小麦着水装置中的应用

从微波水分测量的功率衰减模型出发，分析得出了微波衰减和移相双参量方法的水分测量模型，该模型实现了与小麦密度不相关测量，将其应用于小麦着水系统中作为着水量的实时检测单元具有比传统单参量方法更好的性态。同时给出了小麦着水水分测量单元的原理、系统构成和若干关键技术分析。     

基于微波的大米水分快速检测研究

设计了一套基于微波的大米水分检测系统,研究样品温度、装载高度、微波电压输出值与实测含水量之间的规律性,试验数据表明大米温度及装载高度对输出电压的影响高度显著,且各呈二次曲线关系。在此基础上以装载高度为优化对象,通过对比不同装载高度下所建模型,确定装载高度为50 mm的条件下所建立微波电压值、大米温度值与粮食水分含率之间的回归模型具有较高的预测精度,对于不同温度、不同含水率的独立样品的预测相关系数(Rp)和预测均方根误差(RMSEP)分别为0.9899和0.1939。研究表明,该装置可实现大米水分的快速、无损检测。     

快速粮食水分检测仪的改进设计

粮食品质的检测 ,水分是必不可少的项目。在粮食收购中 ,水分是检测工作量最多的项目之一。因此快速水分检测仪成为粮食检测工作中必不可少的工具。其准确性、稳定性必须可靠无误。目前使用的国内生产的快速水分检测仪 ,从工作原理上分 ,主要有电阻式、电容式等 ,但由于技术设计的原因 ,都不同程度的存在误差大、稳定性不好的问题。在粮食收购工作中 ,快速水分检测数据仅作参考 ,不能作为判定的依据。影响了入库粮食质量和收购进度。针对快速水分检测仪存在的问题 ,特提出改进设计的思路。1　影响粮食水分测量的主要因素1.1　样品重量即测量…     

试论粮食水分检验的常用方法

粮食在收购、存储、运输和加工的过程中,水分的检测和控制非常重要,现对目前的粮食水分检测方案进行收集和综合分析,并系统地阐述了国內现有的各种粮食水分的测量的常用方法、原理及其测量特性。     

A density-independent microwave moisture meter for heterogeneous foodstuffs

Experiments on unground fish meal have been performed using a prototype microwave moisture meter: This device, which was claimed to be density-independent for loose materials such as fibres and powders, measures two microwave parameters simultaneously. A full examination of its performance over a wide range of density and moisture content whilst not entirely justifying this claim shows that it is considerably better than any instrument based on single parameter measurement. For very heterogeneous materials the moisture content could be determined to within ±0·6% moisture content or better-depending on the range of density variation experienced in practice.     

粮食水分快速测定仪多次采样的统计确定

粮食水分快速测定仪是粮食质量检验的主要工具 ,提高其准确性与重复性具有重要意义。文章分析了粮食水分采样结果的统计特性 ,建立了粮食水分快速测定随机过程的数学模型 ,提出了以多次采样算术平均值为仪器测量结果示值的测量结果表示方法 ,确定了采样次数。在此基础上研制的粮食水分快速测定仪具有测量准确、重复性好等特点 ,已在我国粮油行业普及使用     

Non-destructive evaluation of grain angle, moisture content and density of spruce with microwaves

Non-destructive evaluation of the physical properties of wood is a key task in modern wood manufacturing processes. Due to a rapidly increasing production speed, fast, non-contacting, reliable and robust measurement systems are demanded by the wood industry. Common moisture meters are able to reasonably cope with industrial needs. However, modern detection of wood grain angle deviation remains an unresolved issue. Microwave technology features the ability to simultaneously identify grain angle, density and moisture content of wood by measuring attenuation, phase shift, and depolarization of transmitted signals. This paper reports on series of microwave measurements revealing the desired physical properties for spruce. Samples were tested at different frequencies in the range from 8 to 12 GHz. For each frequency the grain angles were identified with standard errors of maximum 0.15° (measuring range from ?90° to +90°). Standard errors in the determination of moisture density were less or equal 1.8 kg/m³ (measuring range from 27 to 56 kg/m³). Standard errors determining moisture content were maximum 0.47 % (measuring range from 7.6 to 14 %), and standard errors for dry density were maximum 11.3 kg/m³ (measuring range from 284 to 492 kg/m³).     

Measurement of wood grain angle, moisture content and density using microwaves

In many wood products manufacturing processes, it is important to ensure that the physical properties of the raw material lie within acceptable ranges and are measured reliably. It is also important for practical use that the measurement process is robust, low-maintenance, fast and preferably non-contacting. This paper describes the development and demonstration of a microwave system for simultaneously identifying wood grain angle, moisture and density. The method involves propagating a microwave beam through the wood and measuring the resulting depolarization, attenuation and phase shift. The wood physical properties can then be identified from these measurements. In a series of measurements, the prototype microwave system successfully identified wood grain angles for hemlock and Douglas fir respectively with standard errors of 0.9° and 2.5° (measured range = -90° to +90°), moisture content 1.2% and 1.9% (measured range = 7–28%), moisture density 3.7 kg/m³ and 7.9 kg/m³ (measured range = 40–150 kg/m³, and dry density 16 kg/m³ and 30 kg/m³ (measured range = 325–625 kg/m³).     

Assessing mineral composition and morpho-physiological properties of de-hulled einkorn wheat during storage at different moisture levels

In this study were investigated the effects of different moisture levels (4.8, 9.5, 13, 16.7 and 20%, w.b.) during the storage at 10 °C for three months on some mineral compositions and morpho-physiological properties as dimensional (length, width, thickness, arithmetic mean diameter, geometric mean diameter, surface area and volume, sphericity), gravimetric (thousand grain weight, bulk and true densities) and the seed (colour measurement and electrical conductivity) of de-hulled einkorn wheat seeds. Mineral composition of wheat seeds changed with increasing moisture level. In particular, decreases in mineral composition were observed above 16.7% moisture level. Dimensional properties showed increases depending on increased moisture level. It was found that thousand grain weight and true density values increased with increase in moisture level. However, bulk density values were found to decrease with increase in moisture level. The seed colour properties as L*, a*, b*, Chroma, hue angle and Browning index did not change statistically at the end of three months storage with increase at moisture level. The results showed that mineral compositions and functional properties of seeds at moisture level of 9.5% is more suitable than other moisture levels. As a result, high moisture levels during storage can cause degradation of seed quality.     

Dielectric and ultrasonic properties of rubber wood. Effect of moisture content grain direction and frequency

Dielectric properties of rubber wood have been studied at low and microwave frequencies with different moisture content and grain direction. The ultrasonic properties were studied with pulsed longitudinal waves of frequency 45 kHz, Two anisotropic directions have been considered for this study — parallel and perpendicular to grain. The low frequencies were of 0.01, 0.1, L0, 10 and 100 Hz and microwave frequencies were of 1, 2.45, 6, 8, 10, 14 and 17 GHz. The moisture content affected the dielectric constant and dielectric loss factor both at low and microwave frequencies? The moisture content above 30% showed little influence on dielectric properties whereas it increases linearly from 0 to 30% in both the grain directions at low frequencies. A continuous increase of dielectric properties was obtained with the increase of moisture content at microwave frequencies and the trend becomes concave upward. Dielectric properties increase as the frequencies increase except dielectric loss factor at microwave frequencies where reverse trends were observed. Little change of dielectric loss factor was obtained at frequencies above 6 GHz. The parallel to grain direction showed higher dielectric constant and dielectric loss factor compared to perpendicular to grain direction. This dielectric anisotropy of wood may be attributed due to the microscopic, macroscopic molecular as well as chemical constituents of wood. Ultrasonic properties were also affected considerably by the moisture content and grain direction. The dried wood showed higher ultrasonic velocity and elastic stiffness constant compared to green wood. The parallel to grain direction exhibits higher ultrasonic velocity and elastic stiffness constant than perpendicular to grain.     

A new method to rapidly detect rusty grain beetle,Cryptolestes ferrugineus (Stephens), in stored grain

Information on insect infestation inside stored grain bulks is required for safe grain storage. A new method to rapidly detect both adults and larvae of Cryptolestes ferrugineus (Stephens) in grain was developed based on the principle of microwave heating and insect behaviour under elevated temperature. The designed apparatus and processing procedure were tested to extract both the adults and larvae inside wheat with 14%, 16% and 18% moisture contents by using a domestic microwave oven (referred to as the microwave method). The recovery percentage of the introduced insects associated with the microwave method was compared with that of the Berlese funnel method (810 cm³ wheat in a funnel under an incandescent light bulb). The microwave method recovered 97.8% of introduced adults, while 90.6% of adults were recovered by the Berlese funnel method. The recovery percentage of the larvae inside marked wheat kernels was 83.3 ± 3.3% with the microwave method and less than 27% with the Berlese funnel method. There was no significant difference in extraction percentage between old and young larvae when the microwave method was used. The moisture content of the treated grain did not significantly influence the extraction percentage of the pest insect. The total processing time of the microwave method was less than 30 min compared to 6 h required for the Berlese funnel method.     

Geometric and Mechanical Properties of Mung Bean (Vigna Radiata L.) Grain: Effect of Moisture

In this research, selected geometric and mechanical properties of mung bean grain were evaluated as a function of moisture content. Five levels of moisture content ranging from 7.28 to 17.77% d.b. (dry basis) were used. The average length, width, thickness, arithmetic and geometric mean diameters, sphericity, thousand grain mass and angle of repose ranged from 5.145 to 6.199 mm, 3.760 to 4.474 mm, 3.537 to 4.223 mm, 4.147 to 4.965 mm, 4.090 to 4.893 mm, 0.795 to 0.789, 52.3 to 64.6 g, and 25.87 to 29.38° as the moisture content increased from 7.28 to 17.77% d.b., respectively. The bulk density was found to be decreased from 821.3 to 745.2 kg/m³, whereas the grain volume, true density, porosity, terminal velocity, and projected area were found to be increased from 27.88 to 47.33 mm³, 1230.0 to 1456.7 kg/m³, 30.43 to 46.57%, 4.86 to 5.29 m/s, and 17.48 to 19.26 mm², respectively. There is a 43% increase in surface area from grain moisture content of 7.28 to 17.77% d.b. The static coefficient of friction on various surfaces increased linearly with the increase in moisture content. The rubber as a surface for sliding offered the maximum friction followed by galvanised iron, medium density fibreboard, stainless steel, aluminium and glass sheet. As moisture content increased from 7.28 to 17.77%, the rupture forces values ranged from 67.39 to 39.44 N; 63.86 to 42.18 N, and 53.96 to 41.79 N for thickness (Z axis), length (Y-axis) and width (X-axis), respectively.     

基于微带微波传感器的谷物含水率便携式检测装置的开发和应用

目的 开发一种基于微带微波传感器的谷物含水率便携式测量装置。方法 该装置由微波电路模块和实时测量模块组成, 可实时显示含水率测量结果。选择水稻样品的厚度和环境温度来优化设备参数。采用随机森林、决策树、K-最近邻和支持向量机4种算法预测水稻的含水率。结果 选择微波衰减、相移和温度作为随机森林算法模型的输入时, 预测结果显示出最好的准确性和稳定性, 最大平均绝对误差为0.55%, 最大标准偏差为0.41%。结论 该仪器结构简单、操作方便、成本低。有望为其他农产品的实时测量提供重要参考, 对智能农业装备的发展具有重要意义。