【作者】 周小蓉；

【导师】 施生锦；

【作者基本信息】 中国农业大学 ， 气象学， 2004， 硕士

【摘要】 为了方便、有效地测定植物的蒸散，为水分利用研究提供价廉物美、简单易用的仪器，本研究利用国产的集成电阻应变式称重传感器，采用AT89C52单片机作为控制单元，结合运算放大、模数转换、实时时钟、液晶显示、数据存储、串行通信等外围接口电路，研制了小型自动称重式蒸散仪。该仪器通过实时时钟芯片实现间隔采集动作的触发及时间、日期的计数；利用液晶显示器(LCD)进行显示；使用它能在无人监管的工作环境下，定时进行蒸散测量并将测得数据自动保存到32K数据存储器中；再通过RS232串行通讯接口将数据传送到PC机进行进一步处理。 通过大量室内实验对仪器进行测试及应用，结果表明该蒸散仪性能稳定、重复性好、精度较高，最大绝对误差为±13g，最大相对误差为0.4％，能满足实际应用要求。其测定值能较好地反映植物在短吋段内的蒸散变化情况，是一种比较方便实用的测定盆栽植物蒸散的仪器。 本文分别就仪器的中央控制、数据采集处理、人机对话、与PC机通讯四个主要功能模块，详细介绍了元器件的选取、相关硬件电路的设计及相应的软件工作流程。并就数据的处理方法及抗干扰措施、仪器的误差来源及其改进方法进行了分析和讨论，最后对仪器的进一步改进和完善提出了一些建议和设想。更多还原

【Abstract】 Using domestic strained integrated resistor as weighing sensor, AT89C52 single chip as control unit, combined with arithmetical magnification, analogtodigital conversion (A/D), real time clock, liquid crystal display (LCD), and series communication interface, a minitype automatic weighing lysimeter is developed. That made measurement of evapotranspiration become conveniently and effectively in studying on water use of crops. The developed apparatus can automatically measure evapotranspiration at setting up interval and memory the data through a 32 KiloByte Data Storage Memory. Measured data can be transmitted to personal computer by RS232 series communication interface. Apparatus will be trigged at measurement time by a real time chip set in it. And users can see measurement parameters, measuring date and time etc through LCD of apparatus.Testing and application of developed apparatus in laboratory time after time, We found that its stability, reproducibility and precision meet practical application completely. Its maximum absolute error is about ?3g and maximum relative error is only about 0.4%. Evapotranspiration of tomato Measured by our apparatus in Laboratory during a consecutive period presents very well its change in reality. For its minitype, the apparatus can specially used for comparison test in potted crop breeding or experiment of watersaving culture in laboratory.Element selecting, electric circuit design of hardware, software development of the apparatus, method of data processing and measures of anti interference are introduced respectively in the paper. Source of apparatus’s errors and improve method are also analyzed and discussed. In the end of the paper, the speculation of the further improvement and perfectness of the apparatus are put forward.更多还原