Growth-related traits,such as aboveground biomass and leaf area,are critical indicators to characterize the growth of greenhouse lettuce.Currently,nondestructive methods for estimating growth-related traits are subjec...Growth-related traits,such as aboveground biomass and leaf area,are critical indicators to characterize the growth of greenhouse lettuce.Currently,nondestructive methods for estimating growth-related traits are subject to limitations in that the methods are susceptible to noise and heavily rely on manually designed features.In this study,a method for monitoring the growth of greenhouse lettuce was proposed by using digital images and a convolutional neural network(CNN).Taking lettuce images as the input,a CNN model was trained to learn the relationship between images and the corresponding growth-related traits,i.e.,leaf fresh weight(LFW),leaf dry weight(LDW),and leaf area(LA).To compare the results of the CNN model,widely adopted methods were also used.The results showed that the values estimated by CNN had good agreement with the actual measurements,with R^(2) values of 0.8938,0.8910,and 0.9156 and normalized root mean square error(NRMSE)values of 26.00,22.07,and 19.94%,outperforming the compared methods for all three growth-related traits.The obtained results showed that the CNN demonstrated superior estimation performance for the flat-type cultivars of Flandria and Tiberius compared with the curled-type cultivar of Locarno.Generalization tests were conducted by using images of Tiberius from another growing season.The results showed that the CNN was still capable of achieving accurate estimation of the growth-related traits,with R2 values of 0.9277,0.9126,and 0.9251 and NRMSE values of 22.96,37.29,and 27.60%.The results indicated that a CNN with digital images is a robust tool for the monitoring of the growth of greenhouse lettuce.展开更多
Effect of the particle number density on the dispersion properties of longitudinal and transverse lattice waves in a two-dimensional Yukawa charged-dust system is investigated using molecular dynamics simulation. The ...Effect of the particle number density on the dispersion properties of longitudinal and transverse lattice waves in a two-dimensional Yukawa charged-dust system is investigated using molecular dynamics simulation. The dispersion relations for the waves are obtained. It is found that the frequencies of both the longitudinal and transverse dust waves increase with the density and when the density is sufficiently high a cutoff region appears at the short wavelength. With the increase of the particle number density, the common frequency tends to increase, and the sound speed of the longitudinal wave also increases, but that of the transverse wave remains low.展开更多
In recent years,the scale of greenhouse grows rapidly and steadily in China,which promotes the development of greenhouse technology and the demand for standardized technology.However,the standardization process of gre...In recent years,the scale of greenhouse grows rapidly and steadily in China,which promotes the development of greenhouse technology and the demand for standardized technology.However,the standardization process of greenhouse industry in China has been facing with the problem of unbalanced development with the practical standard system for many years.To solve these problems,the most characteristic greenhouse designs used in China contributing to this work are presented in detail.And the development of standard system and the standardization efforts of them are summarized and analyzed in relationship to the data presented in this paper.In this way the origin of greenhouse standard system in China and context of the system development and standardization of greenhouse structure are clarified.It was also found that the development and iterative update of greenhouse standard system are under the influences of enterprises which as the participation of standard constitutors were proved to play an important role in promoting the standardization development of greenhouse.The outcome of this work may be utilized to perfect the greenhouse standardization system and improve the greenhouse standardization efficiency that dominate the facility agriculture in China.展开更多
Rapid and accurate detection of pathogen spores is an important step to achieve early diagnosis of diseases in precision agriculture.Traditional detection methods are time-consuming,laborious,and subjective,and image ...Rapid and accurate detection of pathogen spores is an important step to achieve early diagnosis of diseases in precision agriculture.Traditional detection methods are time-consuming,laborious,and subjective,and image processing methods mainly rely on manually designed features that are difficult to cope with pathogen spore detection in complex scenes.Therefore,an MG-YOLO detection algorithm(Multi-head self-attention and Ghost-optimized YOLO)is proposed to detect gray mold spores rapidly.Firstly,Multi-head self-attention is introduced in the backbone to capture the global information of the pathogen spores.Secondly,we combine weighted Bidirectional Feature Pyramid Network(BiFPN)to fuse multiscale features of different layers.Then,a lightweight network is used to construct GhostCSP to optimize the neck part.Cucumber gray mold spores are used as the study object.The experimental results show that the improved MG-YOLO model achieves an accuracy of 0.983 for detecting gray mold spores and takes 0.009 s per image,which is significantly better than the state-of-the-art model.The visualization of the detection results shows that MG-YOLO effectively solves the detection of spores in blurred,small targets,multimorphology,and high-density scenes.Meanwhile,compared with the YOLOv5 model,the detection accuracy of the improved model is improved by 6.8%.It can meet the demand for high-precision detection of spores and provides a novel method to enhance the objectivity of pathogen spore detection.展开更多
The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is...The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is characterized by the scattering laser intensity and fractal dimension. The comparisons of dust particles and scattering laser intensity obtained at different rf powers are presented. The three-dimensional distribution of dust particles is also given. These results provide an experimental basis for dust growth investigation.展开更多
At present,the attitude control method of plant protection UAV is the classical PID control,but there are some imperfections in the PID control,such as the contradiction between speediness and overshoot,the weak anti-...At present,the attitude control method of plant protection UAV is the classical PID control,but there are some imperfections in the PID control,such as the contradiction between speediness and overshoot,the weak anti-jamming ability and adaptability.The physical parameters of plant protection UAV are time-varying,and the airflow also interferes with it.The control ability of classical PID is limited,and its control parameters are fixed,and its anti-jamming ability and adaptability are not strong.Therefore,a fuzzy adaptive PID controller is proposed in this paper.Fuzzy logic control is used to optimize the control parameters of PID in order to improve the dynamic and static performance and adaptability of attitude control of plant protection UAV.In the process of research,the mathematical model of UAV is established firstly,then the fuzzy adaptive PID is designed,and then the simulation is carried out in Simulink.The simulation results show that the fuzzy adaptive PID controller has better dynamic and static control performance and adaptability than the traditional PID controller.Therefore,the proposed control method has excellent application value in the attitude of plant protection UAV.展开更多
A new type of roof structure was developed for the shade room in a double-slope greenhouse used for mushroom-vegetable planting.A simulation model was developed to evaluate the thermal performance of the new roof with...A new type of roof structure was developed for the shade room in a double-slope greenhouse used for mushroom-vegetable planting.A simulation model was developed to evaluate the thermal performance of the new roof with an insulation thickness of 0.12 m in Beijing,China.The results showed that(1)the indoor air temperature of the shade room with the newly implemented shade roof was 2.7℃-4.9℃ higher than that of an ordinary shade room during the winter months;(2)The indoor air temperature of the solar room adjacent to the shade room with the new roof was higher than that of the ordinary solar room and the minimum indoor air temperature of the solar room was increased 1.9℃ at winter night;(3)the indoor temperature of the shade room with the new roof design was 2℃-4℃ lower than that of the ordinary shade room during the summer months;(4)Under factory production conditions,which were conducted in a controlled environment to promote the annual growth of the edible fungus,the heating energy consumption of the shade room after the implementation of the new roof structure was reduced by 69.3%,the amounted to total energy savings of 61.3% per year.The new roof structure provided a significant improvement in the thermal environment compared to an ordinary shade room,improved the vegetable growth in the winter,and also significantly reduced the energy consumption and production costs.展开更多
China is the largest producer and consumer of vegetables,its vegetable industry is playing an important role in the domestic agricultural sector and global vegetable export market.It is important to promote the long-t...China is the largest producer and consumer of vegetables,its vegetable industry is playing an important role in the domestic agricultural sector and global vegetable export market.It is important to promote the long-term sustainable development of Chinese vegetable industry for food security and quality of people’s lives.To find out the intrinsic way to promote the development of Chinese vegetable industry,this paper analyzed the influencing factors of Chinese vegetable production by utilizing the LMDI method and demonstrated the spatial-temporal characteristics of vegetable production through application of the Arc-GIS spatial autocorrelation analysis method.The results showed that the influencing factors of vegetable production were the cultivated land area,multiple cropping index,vegetable planting proportion and vegetable yield per hectare in China.The major driving factor had changed from vegetable planting proportion to vegetable yield per hectare.The influencing degrees of factors on vegetable production are different in different regions,regionalization is therefore a major feature of Chinese vegetable production.The government should take production technology,regionalization-driven effect,and marketing integration into consideration to promote the development of Chinese vegetable industry.展开更多
A novel power-on-reset(POR) circuit with simple architecture, small values of capacitances, ultralower power consumption, and self-adjustable delay time of reset pulse for passive UHF RFID tags is presented in this pa...A novel power-on-reset(POR) circuit with simple architecture, small values of capacitances, ultralower power consumption, and self-adjustable delay time of reset pulse for passive UHF RFID tags is presented in this paper. A proposed delay element was adopted for the features of small capacitances and wide power supply rise time range. An inverter was used as a two-inputs logic device to simplify the architecture of the circuit. The technology used for design and simulation is SMIC 0.18 μm RF. Simulation results show that the circuit functions well under different process corners with different power supply rise time, and is able to generate a POR signal after the power supply is briefly powered off. The static power consumption is less than 30 pA. Moreover, the circuit operates properly along with other modules of analog front-end.展开更多
With the increasing demand for food worldwide,it has attracted increasing attention how to improve the agricultural production efficiency.This paper aims to develop a technical efficiency evaluation system for vegetab...With the increasing demand for food worldwide,it has attracted increasing attention how to improve the agricultural production efficiency.This paper aims to develop a technical efficiency evaluation system for vegetable production to provided decisions for the practice of precision agriculture.The paper analyses the system-needs and business processes,and proposes a system framework which has three tiers architectures,based on B/S model.The stochastic frontier analysis(SFA)algorithm model which is the incorporated into the system is established.The system was tested and evaluated by real business data,which were from Beijing from 2003 to 2011 to test system performance based on the temporal perspective and China during 2011 and 2012 to test system performance based on the spatial characteristics.The results shows that the system achieves the business requirements with an intelligent tool for data management and technical efficiency evaluation for vegetable production to improve automation,efficiency and convenience.展开更多
基金supported by the Beijing Leafy Vegetables Innovation Team of Modern Agro-industry Technology Research System(BAIC07-2020)the National Key Research and Development Project of Shandong(2017CXGC0201).
文摘Growth-related traits,such as aboveground biomass and leaf area,are critical indicators to characterize the growth of greenhouse lettuce.Currently,nondestructive methods for estimating growth-related traits are subject to limitations in that the methods are susceptible to noise and heavily rely on manually designed features.In this study,a method for monitoring the growth of greenhouse lettuce was proposed by using digital images and a convolutional neural network(CNN).Taking lettuce images as the input,a CNN model was trained to learn the relationship between images and the corresponding growth-related traits,i.e.,leaf fresh weight(LFW),leaf dry weight(LDW),and leaf area(LA).To compare the results of the CNN model,widely adopted methods were also used.The results showed that the values estimated by CNN had good agreement with the actual measurements,with R^(2) values of 0.8938,0.8910,and 0.9156 and normalized root mean square error(NRMSE)values of 26.00,22.07,and 19.94%,outperforming the compared methods for all three growth-related traits.The obtained results showed that the CNN demonstrated superior estimation performance for the flat-type cultivars of Flandria and Tiberius compared with the curled-type cultivar of Locarno.Generalization tests were conducted by using images of Tiberius from another growing season.The results showed that the CNN was still capable of achieving accurate estimation of the growth-related traits,with R2 values of 0.9277,0.9126,and 0.9251 and NRMSE values of 22.96,37.29,and 27.60%.The results indicated that a CNN with digital images is a robust tool for the monitoring of the growth of greenhouse lettuce.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11675261 and 21403297the Scientific Research Foundation of Ludong University under Grant No LY2014010
文摘Effect of the particle number density on the dispersion properties of longitudinal and transverse lattice waves in a two-dimensional Yukawa charged-dust system is investigated using molecular dynamics simulation. The dispersion relations for the waves are obtained. It is found that the frequencies of both the longitudinal and transverse dust waves increase with the density and when the density is sufficiently high a cutoff region appears at the short wavelength. With the increase of the particle number density, the common frequency tends to increase, and the sound speed of the longitudinal wave also increases, but that of the transverse wave remains low.
基金This work was supported by National Key Technology R&D Program of China during the 12th Five-Year Plan Period(Grant No.2012BAD35B02).
文摘In recent years,the scale of greenhouse grows rapidly and steadily in China,which promotes the development of greenhouse technology and the demand for standardized technology.However,the standardization process of greenhouse industry in China has been facing with the problem of unbalanced development with the practical standard system for many years.To solve these problems,the most characteristic greenhouse designs used in China contributing to this work are presented in detail.And the development of standard system and the standardization efforts of them are summarized and analyzed in relationship to the data presented in this paper.In this way the origin of greenhouse standard system in China and context of the system development and standardization of greenhouse structure are clarified.It was also found that the development and iterative update of greenhouse standard system are under the influences of enterprises which as the participation of standard constitutors were proved to play an important role in promoting the standardization development of greenhouse.The outcome of this work may be utilized to perfect the greenhouse standardization system and improve the greenhouse standardization efficiency that dominate the facility agriculture in China.
基金the financial support of the National Natural Science Foundation of China(no.62176261).
文摘Rapid and accurate detection of pathogen spores is an important step to achieve early diagnosis of diseases in precision agriculture.Traditional detection methods are time-consuming,laborious,and subjective,and image processing methods mainly rely on manually designed features that are difficult to cope with pathogen spore detection in complex scenes.Therefore,an MG-YOLO detection algorithm(Multi-head self-attention and Ghost-optimized YOLO)is proposed to detect gray mold spores rapidly.Firstly,Multi-head self-attention is introduced in the backbone to capture the global information of the pathogen spores.Secondly,we combine weighted Bidirectional Feature Pyramid Network(BiFPN)to fuse multiscale features of different layers.Then,a lightweight network is used to construct GhostCSP to optimize the neck part.Cucumber gray mold spores are used as the study object.The experimental results show that the improved MG-YOLO model achieves an accuracy of 0.983 for detecting gray mold spores and takes 0.009 s per image,which is significantly better than the state-of-the-art model.The visualization of the detection results shows that MG-YOLO effectively solves the detection of spores in blurred,small targets,multimorphology,and high-density scenes.Meanwhile,compared with the YOLOv5 model,the detection accuracy of the improved model is improved by 6.8%.It can meet the demand for high-precision detection of spores and provides a novel method to enhance the objectivity of pathogen spore detection.
基金Supported by the National Natural Science Foundation of China under Grant No 11675261
文摘The coagulation and growth process of dust particles is investigated through laboratory experiment in a plasma system. A large number of dust particles with different sizes and shapes are formed. The growth process is characterized by the scattering laser intensity and fractal dimension. The comparisons of dust particles and scattering laser intensity obtained at different rf powers are presented. The three-dimensional distribution of dust particles is also given. These results provide an experimental basis for dust growth investigation.
基金This research work was supported by Project of Scientific Operating Expenses from Ministry of Education of China(2017PT19)National Natural Science Foundation of China(31761133019).
文摘At present,the attitude control method of plant protection UAV is the classical PID control,but there are some imperfections in the PID control,such as the contradiction between speediness and overshoot,the weak anti-jamming ability and adaptability.The physical parameters of plant protection UAV are time-varying,and the airflow also interferes with it.The control ability of classical PID is limited,and its control parameters are fixed,and its anti-jamming ability and adaptability are not strong.Therefore,a fuzzy adaptive PID controller is proposed in this paper.Fuzzy logic control is used to optimize the control parameters of PID in order to improve the dynamic and static performance and adaptability of attitude control of plant protection UAV.In the process of research,the mathematical model of UAV is established firstly,then the fuzzy adaptive PID is designed,and then the simulation is carried out in Simulink.The simulation results show that the fuzzy adaptive PID controller has better dynamic and static control performance and adaptability than the traditional PID controller.Therefore,the proposed control method has excellent application value in the attitude of plant protection UAV.
基金This research was made possible through financial support from the Beijing Leafy Vegetables Innovation Team of Modern Agro-industry Technology Research System(BAIC07-2019)Yantai Science and Technology Development Project(2013ZH083).
文摘A new type of roof structure was developed for the shade room in a double-slope greenhouse used for mushroom-vegetable planting.A simulation model was developed to evaluate the thermal performance of the new roof with an insulation thickness of 0.12 m in Beijing,China.The results showed that(1)the indoor air temperature of the shade room with the newly implemented shade roof was 2.7℃-4.9℃ higher than that of an ordinary shade room during the winter months;(2)The indoor air temperature of the solar room adjacent to the shade room with the new roof was higher than that of the ordinary solar room and the minimum indoor air temperature of the solar room was increased 1.9℃ at winter night;(3)the indoor temperature of the shade room with the new roof design was 2℃-4℃ lower than that of the ordinary shade room during the summer months;(4)Under factory production conditions,which were conducted in a controlled environment to promote the annual growth of the edible fungus,the heating energy consumption of the shade room after the implementation of the new roof structure was reduced by 69.3%,the amounted to total energy savings of 61.3% per year.The new roof structure provided a significant improvement in the thermal environment compared to an ordinary shade room,improved the vegetable growth in the winter,and also significantly reduced the energy consumption and production costs.
基金the financial support from Beijing Social Science Foundation(16YJA007)the earmarked fund for Beijing Innovation Consortium of Agriculture Research System(BAIC07-2013).
文摘China is the largest producer and consumer of vegetables,its vegetable industry is playing an important role in the domestic agricultural sector and global vegetable export market.It is important to promote the long-term sustainable development of Chinese vegetable industry for food security and quality of people’s lives.To find out the intrinsic way to promote the development of Chinese vegetable industry,this paper analyzed the influencing factors of Chinese vegetable production by utilizing the LMDI method and demonstrated the spatial-temporal characteristics of vegetable production through application of the Arc-GIS spatial autocorrelation analysis method.The results showed that the influencing factors of vegetable production were the cultivated land area,multiple cropping index,vegetable planting proportion and vegetable yield per hectare in China.The major driving factor had changed from vegetable planting proportion to vegetable yield per hectare.The influencing degrees of factors on vegetable production are different in different regions,regionalization is therefore a major feature of Chinese vegetable production.The government should take production technology,regionalization-driven effect,and marketing integration into consideration to promote the development of Chinese vegetable industry.
基金Project supported by the Key Laboratory of Agricultural Informatization Standardization,Ministry of Agriculture and Rural Affairs
文摘A novel power-on-reset(POR) circuit with simple architecture, small values of capacitances, ultralower power consumption, and self-adjustable delay time of reset pulse for passive UHF RFID tags is presented in this paper. A proposed delay element was adopted for the features of small capacitances and wide power supply rise time range. An inverter was used as a two-inputs logic device to simplify the architecture of the circuit. The technology used for design and simulation is SMIC 0.18 μm RF. Simulation results show that the circuit functions well under different process corners with different power supply rise time, and is able to generate a POR signal after the power supply is briefly powered off. The static power consumption is less than 30 pA. Moreover, the circuit operates properly along with other modules of analog front-end.
基金support from Beijing Social Science Foundation(16YJA007)the earmarked fund for Beijing Innovation Consortium of Agriculture Research System(BAIC07-20).
文摘With the increasing demand for food worldwide,it has attracted increasing attention how to improve the agricultural production efficiency.This paper aims to develop a technical efficiency evaluation system for vegetable production to provided decisions for the practice of precision agriculture.The paper analyses the system-needs and business processes,and proposes a system framework which has three tiers architectures,based on B/S model.The stochastic frontier analysis(SFA)algorithm model which is the incorporated into the system is established.The system was tested and evaluated by real business data,which were from Beijing from 2003 to 2011 to test system performance based on the temporal perspective and China during 2011 and 2012 to test system performance based on the spatial characteristics.The results shows that the system achieves the business requirements with an intelligent tool for data management and technical efficiency evaluation for vegetable production to improve automation,efficiency and convenience.
