From the perspective of village classification, a set of methods for accurately measuring the potential of rural settlement consolidation are proposed. Taking Feicheng in Shandong Province as the research area, combin...From the perspective of village classification, a set of methods for accurately measuring the potential of rural settlement consolidation are proposed. Taking Feicheng in Shandong Province as the research area, combined with the corresponding planning, a classification and evaluation system for rural residential areas was constructed to classify rural residential areas from the four levels of natural resources, economy and society, supporting facilities and livability. The theoretical and practical potential of one type of rural settlements (relocating and merger village) is mainly calculated, and the potential scale, potential level and potential spatial distribution of different regions are analyzed. (Level and spatial distribution are analyzed. The results showed that the 621 rural settlements can be divided into five types: 148 urban-rural integration villages (URIV), 41 historical and cultural villages (HCV), 56 cluster developing villages (CDV), 155 keeping and limiting villages (KLV) and 221 relocating and merger villages (RMV). According to calculations, the theoretical potential of relocating and merger village areas was 1971.47 hm2, accounting for 19.52% of the total scale of Feicheng residential areas;the comprehensive correction coefficient of each region was 0.48 - 0.70, and the revised actual potential is 1082.68 hm2, accounting for the theoretical potential 54.92% of the total. There were large spatial differences in the scale of potential in different regions. In general, the theoretical and practical potential of the central and southern regions was higher than that of the northern regions.展开更多
The nutrient inversion model of apple leaves was established by spectral analysis technology to provide technical support for the fine management of apple trees.In Shuangquan Town,Changqing District,Jinan City,Shandon...The nutrient inversion model of apple leaves was established by spectral analysis technology to provide technical support for the fine management of apple trees.In Shuangquan Town,Changqing District,Jinan City,Shandong Province,the Fuji apple trees with stopping period of spring shoots were taken as research objects.The spectral reflectance and nitrogen content of apple leaves were measured by ASD Field Spec 4 portable ground object spectrometer.Analyzed the correlation between leaf nitrogen content and spectral reflectance.The sensitive wavelengths with high correlation coefficient were select by fractional differential algorithm,and the optimal vegetation index was constructed and screened out.Partial Least Square Regression(PLSR),Support Vector Machine(SVM)and Random Forests(RF)method were used to construct an inversion model of leaf nitrogen content.The results show that the RF model based on fractional differential second-order treatment is the best inversion model for the nitrogen content of leaves during stopping period of spring shoots.The modeling accuracy determination coefficient R2 reached 0.891,RMSE was 0.0841,and RPD was 2.1396.The determination coefficient R2 of the fitting results of the verification set was 0.617,RMSE was 0.1251,and RPD was 1.7105.The inversion model established by RF method is effective in monitoring the nitrogen content in apple leaves,which provides a theoretical basis for monitoring the growth of apple by hyperspectral technology.展开更多
BeiDou-3 navigation satellite system was officially opened in 2020.While bringing high-performance services to people around the world,the navigation system requires well-designed BeiDou antennas.In this paper,we prop...BeiDou-3 navigation satellite system was officially opened in 2020.While bringing high-performance services to people around the world,the navigation system requires well-designed BeiDou antennas.In this paper,we propose a wideband circularly polarized high-performance BeiDou antenna.The antenna realizes wideband circularly polarized radiation through a four-port sequential feed network,and the phase imbalance of the feed network from 1.05 to 1.80 GHz is less than 7°.The manufactured antenna demonstrates a return loss of more than 13 dB and an axial ratio<3 dB over the entire global navigation satellite system(GNSS)frequency band.The right-handed circular polarization(RHCP)gain of the proposed antenna is greater than 4 dB in the GNSS low-frequency band and can reach more than 7.1 dB in the high-frequency band.Dimension of the proposed antenna is 120 mm×120 mm×20 mm,i.e.,0.54λo×0.54λo×0.09λo,whereλo is the wavelength of the center frequency.The proposed antenna connected to a GNSS receiver has tracked 12 BeiDou satellites with C/N0 ratios of GNSS signals greater than 30 dB.Such a high-performance antenna provides a basis for high-quality positioning services.展开更多
文摘From the perspective of village classification, a set of methods for accurately measuring the potential of rural settlement consolidation are proposed. Taking Feicheng in Shandong Province as the research area, combined with the corresponding planning, a classification and evaluation system for rural residential areas was constructed to classify rural residential areas from the four levels of natural resources, economy and society, supporting facilities and livability. The theoretical and practical potential of one type of rural settlements (relocating and merger village) is mainly calculated, and the potential scale, potential level and potential spatial distribution of different regions are analyzed. (Level and spatial distribution are analyzed. The results showed that the 621 rural settlements can be divided into five types: 148 urban-rural integration villages (URIV), 41 historical and cultural villages (HCV), 56 cluster developing villages (CDV), 155 keeping and limiting villages (KLV) and 221 relocating and merger villages (RMV). According to calculations, the theoretical potential of relocating and merger village areas was 1971.47 hm2, accounting for 19.52% of the total scale of Feicheng residential areas;the comprehensive correction coefficient of each region was 0.48 - 0.70, and the revised actual potential is 1082.68 hm2, accounting for the theoretical potential 54.92% of the total. There were large spatial differences in the scale of potential in different regions. In general, the theoretical and practical potential of the central and southern regions was higher than that of the northern regions.
基金This paper was supported by the National Natural Science Foundation of China(41671346)the National Key Research and Development Program of China(2017YFE0122500)+1 种基金Shandong Major Scientific and Technological Innovation Project(2018CXGC0209)the Taishan Scholar Assistance Program from Shandong Provincial Government,Funds of Shandong“Double Tops”Program(SYL2017XTTD02).
文摘The nutrient inversion model of apple leaves was established by spectral analysis technology to provide technical support for the fine management of apple trees.In Shuangquan Town,Changqing District,Jinan City,Shandong Province,the Fuji apple trees with stopping period of spring shoots were taken as research objects.The spectral reflectance and nitrogen content of apple leaves were measured by ASD Field Spec 4 portable ground object spectrometer.Analyzed the correlation between leaf nitrogen content and spectral reflectance.The sensitive wavelengths with high correlation coefficient were select by fractional differential algorithm,and the optimal vegetation index was constructed and screened out.Partial Least Square Regression(PLSR),Support Vector Machine(SVM)and Random Forests(RF)method were used to construct an inversion model of leaf nitrogen content.The results show that the RF model based on fractional differential second-order treatment is the best inversion model for the nitrogen content of leaves during stopping period of spring shoots.The modeling accuracy determination coefficient R2 reached 0.891,RMSE was 0.0841,and RPD was 2.1396.The determination coefficient R2 of the fitting results of the verification set was 0.617,RMSE was 0.1251,and RPD was 1.7105.The inversion model established by RF method is effective in monitoring the nitrogen content in apple leaves,which provides a theoretical basis for monitoring the growth of apple by hyperspectral technology.
文摘BeiDou-3 navigation satellite system was officially opened in 2020.While bringing high-performance services to people around the world,the navigation system requires well-designed BeiDou antennas.In this paper,we propose a wideband circularly polarized high-performance BeiDou antenna.The antenna realizes wideband circularly polarized radiation through a four-port sequential feed network,and the phase imbalance of the feed network from 1.05 to 1.80 GHz is less than 7°.The manufactured antenna demonstrates a return loss of more than 13 dB and an axial ratio<3 dB over the entire global navigation satellite system(GNSS)frequency band.The right-handed circular polarization(RHCP)gain of the proposed antenna is greater than 4 dB in the GNSS low-frequency band and can reach more than 7.1 dB in the high-frequency band.Dimension of the proposed antenna is 120 mm×120 mm×20 mm,i.e.,0.54λo×0.54λo×0.09λo,whereλo is the wavelength of the center frequency.The proposed antenna connected to a GNSS receiver has tracked 12 BeiDou satellites with C/N0 ratios of GNSS signals greater than 30 dB.Such a high-performance antenna provides a basis for high-quality positioning services.
