电容法测量湿型砂水分的非线性分析和校正.pdfVIP

学兔兔 Oct．2015 Vo1．64 NO．1O ·985· ● ● ■、 — ● 叫 ；检测技术{ ’ ●、■■ ■ p●^，■^●’ “ 电容法测量湿型砂水分的非线性分析和校正 石德全，康凯娇，李大勇，刘成前 (哈尔滨理工大学材料科学与工程学院，黑龙江哈尔滨150040) 摘要：在简要介绍电容法测定型砂含水量的基础上，从理论上分析了该测量方法中产生非线性的原因。当湿型砂在 交流激励电场激励下，湿型砂试样中除基波电流外，存在的三次、五次和更高次的谐波电流是产生非线性的根本原 因。从被测湿型砂试样、传感器的结构与制造工艺、砂样漏电阻、环境和机械不稳定性方面分析了影响电容法测量 湿型砂含水量非线性的宏观因素，极性分子的介质极化和损耗是影响非线性的主要因素。为了降低非线性的影响， 根据最小二乘法原理，给出了一种反非线性校正的实现方法。试验结果显示：经反非线性校正后，传感器的输入输 出间具有很好的线性度，其相对误差小于0．2％。 关键词：非线性分析；校正；电容法；湿型砂；水分 中图分类号：TG274．53；TG249 文献标识码：A 文章编号：1001—4977(2015)10—0985—04 Nonlinearity Analysis and Rectification of Measuring Moisture Content of Green Sand by Capacitance Method SHI De-quan，KANG Kai-jiao，LI Da—yong，LIU Chen—qian (School ofMaterials Science and Engineering，Harbin University ofScience and Technology， Harbin 1 50040，Heilongjiang，China) Abstract：On the basis ofbriefly introducing the principal ofmeasuring the moisture content by the capacitance method the reasons ofleading to the nonlinearity were analyzed theoretically．纬 en the green sand was excited by the altemative current field,the three．five and higher order harmonic currents are the primary cause of the nonlinearitV．The macro factors of impacting the nonlinearity were analyzed from the aspects of green sand sample，sensor structure and manufacturing process，sample leakage resistance，environment and mechanical instability．And the dielectric polarization and loss of polar molecules iS the main influence factor．In order to decrease the nonlinearity,an implementation method ofthe inverse nonlinear correction was given according to the least square principa1．The experi