冬小麦拔节期叶绿素状况估算对于冬小麦营养诊断非常重要。本文利用无人机遥感平台获取冬小麦拔节期长势遥感信息,提取多光谱植被指数、RGB影像纹理特征及覆盖度信息,基于多元线性回归(Multivariate linear regression,MLR)、随机森林回...冬小麦拔节期叶绿素状况估算对于冬小麦营养诊断非常重要。本文利用无人机遥感平台获取冬小麦拔节期长势遥感信息,提取多光谱植被指数、RGB影像纹理特征及覆盖度信息,基于多元线性回归(Multivariate linear regression,MLR)、随机森林回归(Random forest regression,RFR)构建了冬小麦SPAD值估算模型。分析多光谱植被指数、纹理特征和覆盖度信息,以及相互结合对于冬小麦SPAD值估算的影响。结果表明:多光谱植被指数、纹理特征、覆盖度的结合(2种类型或3种类型参数结合)可以用于冬小麦拔节期SPAD值的估算,而且相较于单类型参数或两类型参数结合,更多类型参数结合提高了冬小麦拔节期SPAD值的估算精度。而基于相同参数利用随机森林构建的冬小麦拔节期SPAD值估算模型精度均高于多元线性回归构建的模型精度。其中,基于3种类型参数构建的冬小麦SPAD值估算模型精度最高,R^(2)为0.78,RMSE为2.08。各类型参数对冬小麦拔节期SPAD值估算精度的影响由大到小依次为多光谱植被指数、纹理特征、覆盖度。其中,多光谱植被指数构建的模型精度与纹理特征构建的模型精度相近(R^(2)和RMSE分别为0.71、2.36及0.70、2.45)。覆盖度虽然对于SPAD值的估算精度提升最小,但结合其他特征可提高冬小麦SPAD值估算精度(对于RFR模型,R^(2)提高0.02~0.03)。多光谱植被指数、纹理特征、覆盖度的结合提高了模型估算精度,为冬小麦拔节期SPAD值快速估算提供了技术参考。展开更多
Thermal performance was the most important factor in the development of borehole heat exchanger utilizing geothermal energy. The thermal performance was affected by many different design parameters, such as configurat...Thermal performance was the most important factor in the development of borehole heat exchanger utilizing geothermal energy. The thermal performance was affected by many different design parameters, such as configuration type and borehole size of geothermal heat exchanger. These eventually determined the operation and cost efficiency of the geothermal heat exchanger system. The main purpose of this work was to assess the thermal performance of geother^nal heat exchanger with variation of borehole sizes and numbers of U-tubes inside a borehole. For this, a thermal response test rig was established with line-source theory. The thermal response test was performed with in-line variable input heat source. Effective thermal conductivity and thermal resistance were obtained from the measured data. From the measurement, the effective thermal conductivity is found to have similar values for two- pair type （4 U-tubes） and three-pair type （6 U-tubes） borehole heat exchanger systems indicating similar heat transfer ability. Meanwhile, the thermal resistance shows lower value for the three-pair type compared to the two-pair type. Measured data based resistance have lower value compared to computed result from design programs. Overall comparison finds better thermal performance for the three-pair type, however, fluctuating temperature variation indicates complex flow behavior inside the borehole and requires further study on flow characteristics.展开更多
文摘冬小麦拔节期叶绿素状况估算对于冬小麦营养诊断非常重要。本文利用无人机遥感平台获取冬小麦拔节期长势遥感信息,提取多光谱植被指数、RGB影像纹理特征及覆盖度信息,基于多元线性回归(Multivariate linear regression,MLR)、随机森林回归(Random forest regression,RFR)构建了冬小麦SPAD值估算模型。分析多光谱植被指数、纹理特征和覆盖度信息,以及相互结合对于冬小麦SPAD值估算的影响。结果表明:多光谱植被指数、纹理特征、覆盖度的结合(2种类型或3种类型参数结合)可以用于冬小麦拔节期SPAD值的估算,而且相较于单类型参数或两类型参数结合,更多类型参数结合提高了冬小麦拔节期SPAD值的估算精度。而基于相同参数利用随机森林构建的冬小麦拔节期SPAD值估算模型精度均高于多元线性回归构建的模型精度。其中,基于3种类型参数构建的冬小麦SPAD值估算模型精度最高,R^(2)为0.78,RMSE为2.08。各类型参数对冬小麦拔节期SPAD值估算精度的影响由大到小依次为多光谱植被指数、纹理特征、覆盖度。其中,多光谱植被指数构建的模型精度与纹理特征构建的模型精度相近(R^(2)和RMSE分别为0.71、2.36及0.70、2.45)。覆盖度虽然对于SPAD值的估算精度提升最小,但结合其他特征可提高冬小麦SPAD值估算精度(对于RFR模型,R^(2)提高0.02~0.03)。多光谱植被指数、纹理特征、覆盖度的结合提高了模型估算精度,为冬小麦拔节期SPAD值快速估算提供了技术参考。
基金Project financially supported by the Second Stage of Brain Korea 21 Projects and Changwon National University,Korea
文摘Thermal performance was the most important factor in the development of borehole heat exchanger utilizing geothermal energy. The thermal performance was affected by many different design parameters, such as configuration type and borehole size of geothermal heat exchanger. These eventually determined the operation and cost efficiency of the geothermal heat exchanger system. The main purpose of this work was to assess the thermal performance of geother^nal heat exchanger with variation of borehole sizes and numbers of U-tubes inside a borehole. For this, a thermal response test rig was established with line-source theory. The thermal response test was performed with in-line variable input heat source. Effective thermal conductivity and thermal resistance were obtained from the measured data. From the measurement, the effective thermal conductivity is found to have similar values for two- pair type （4 U-tubes） and three-pair type （6 U-tubes） borehole heat exchanger systems indicating similar heat transfer ability. Meanwhile, the thermal resistance shows lower value for the three-pair type compared to the two-pair type. Measured data based resistance have lower value compared to computed result from design programs. Overall comparison finds better thermal performance for the three-pair type, however, fluctuating temperature variation indicates complex flow behavior inside the borehole and requires further study on flow characteristics.
