An analytical approach was developed to design a single uniformly sloping lateral in the micro-irrigation systems.Emission uniformity was used as the water application uniformity criterion.Energy relations based on th...An analytical approach was developed to design a single uniformly sloping lateral in the micro-irrigation systems.Emission uniformity was used as the water application uniformity criterion.Energy relations based on the energy-gradient-line approach were revamped to account for the spatial variance of emitter outflow and the emitter connections local energy losses.Four pressure head grade line profiles were distinguished:uphill,horizontal,gentle downhill and steep downhill.Analytical expressions of emission uniformity by hydraulic variation for each pressure profile were developed based on the design variables:length and diameter of lateral,emitter spacing,emitter flow equation parameters,equivalent length characterizing local losses and ground slope.The design conditions for selecting emitter type,the number of emitters per plant and designing the diameter of the uphill and steep downhill laterals were also developed.The nonlinear equations for determining lateral diameter and lateral length were solved iteratively by using the built-in root-finding function of(Tools>Goal Seek…)in the calculation spreadsheet of Microsoft Excel.The procedures also provide the options to fix the design lateral diameter with the commercial standard size or fix the design lateral length based on the field size.The operating inlet pressure and maximum amplitude of the pressure head throughout the lateral could also be determined easily by the procedure.Two numerical applications with various slope combinations indicate that the proposed analytical approach produces results close to the accurate stepwise numerical solutions.In comparison with Keller method,the proposed approach could produce more appropriate designs.展开更多
Normalized Difference Vegetation Index(NDVI)has been found to have good correlations with many physical properties of soybean surfaces.Due to the factors of air temperature,humidity,solar radiation,soil moisture,etc.,...Normalized Difference Vegetation Index(NDVI)has been found to have good correlations with many physical properties of soybean surfaces.Due to the factors of air temperature,humidity,solar radiation,soil moisture,etc.,NDVI of soybean varies dynamically in a day.The establishment of the soybean NDVI prediction model at different times in a day can effectively modify this variation.The soybean NDVI values are continuously monitored in hours during soybean seeding,flowering&podding and maturating stages by way of Green Seeker.Results show that the trend of NDVI change every day in the three stages is taken on as a reverse parabola.The NDVI value reaches to the maximum at 8 am or 9 am and decreases to its minimum at 2 pm before a moderate rise.A model for intraday and long-term NDVI change for soybean is built.The test of the model with independent data indicates that the precision meets the demands,with the root mean square error(RMSE)of each day being 3.95,5.45 and 2.86 for the seeding stage,the bean podding stage and the maturation period,respectively.The prediction RMSEs of the soybean NDVI model for soybeans of the three stages for the fifth day are 5.75,2.65 and 5.51,respectively and the prediction RMSEs for the sixth day are 9.74,2.82 and 14.04,respectively according to the data from the first four days.展开更多
In order to improve the level of multi-functional and automatic observation of crop root system growth,a soil column monitoring system was designed to facilitate in situ dynamic monitoring of root growth and water con...In order to improve the level of multi-functional and automatic observation of crop root system growth,a soil column monitoring system was designed to facilitate in situ dynamic monitoring of root growth and water consumption.The system consists of 20 plastic tubular backfill soil columns,each with an inner diameter of 32 cm and height of 300 cm.The crops were planted at the top of the soil column with the surrounding leveled with the ground surface and the site is in a greenhouse.The underground portion of the soil column contains small round windows on the tube through which root growth can be monitored,roots can be pruned and soil samples can be obtained.A multiport serial weighing system was designed and placed at the base of the soil column.Twenty electronic balances were connected to the personal computer through three CP-168U multiport serial cards and RS-232 serial cables.The host software was developed on the browser/server(Browser/Server),and data collection and remote data transmission and data sharing were implemented using the Java programming language and applying Internet data transmission technology and Web application technology.System tests showed a relatively good stability and real-time capability,and with accuracy up to 50 g and the evapotranspiration of each soil column was 0.25-0.65 kg per day.The root-system observation system developed in this study surpassed the traditional method of root-digging sampling and thus provided an alternative that could be used to automatically monitor the root system growth status.展开更多
基金supported by the Special Foundation of National Science & Technology Supporting Plan( 2011BAD29B02)the "111" Project (B12007)
文摘An analytical approach was developed to design a single uniformly sloping lateral in the micro-irrigation systems.Emission uniformity was used as the water application uniformity criterion.Energy relations based on the energy-gradient-line approach were revamped to account for the spatial variance of emitter outflow and the emitter connections local energy losses.Four pressure head grade line profiles were distinguished:uphill,horizontal,gentle downhill and steep downhill.Analytical expressions of emission uniformity by hydraulic variation for each pressure profile were developed based on the design variables:length and diameter of lateral,emitter spacing,emitter flow equation parameters,equivalent length characterizing local losses and ground slope.The design conditions for selecting emitter type,the number of emitters per plant and designing the diameter of the uphill and steep downhill laterals were also developed.The nonlinear equations for determining lateral diameter and lateral length were solved iteratively by using the built-in root-finding function of(Tools>Goal Seek…)in the calculation spreadsheet of Microsoft Excel.The procedures also provide the options to fix the design lateral diameter with the commercial standard size or fix the design lateral length based on the field size.The operating inlet pressure and maximum amplitude of the pressure head throughout the lateral could also be determined easily by the procedure.Two numerical applications with various slope combinations indicate that the proposed analytical approach produces results close to the accurate stepwise numerical solutions.In comparison with Keller method,the proposed approach could produce more appropriate designs.
基金supported by Governmental Public Industry Research Special Funds for Projects(201301016)National Key Technology R&D Program of the Ministry of Science and Technology(2012BAH29B04-02)+1 种基金Chinese Universities Scientific Fund,Northwest A&F University(QN2011132)the Introduction of Intelligence from Abroad Project for Innovation in Academic Schools,China(B12007).
文摘Normalized Difference Vegetation Index(NDVI)has been found to have good correlations with many physical properties of soybean surfaces.Due to the factors of air temperature,humidity,solar radiation,soil moisture,etc.,NDVI of soybean varies dynamically in a day.The establishment of the soybean NDVI prediction model at different times in a day can effectively modify this variation.The soybean NDVI values are continuously monitored in hours during soybean seeding,flowering&podding and maturating stages by way of Green Seeker.Results show that the trend of NDVI change every day in the three stages is taken on as a reverse parabola.The NDVI value reaches to the maximum at 8 am or 9 am and decreases to its minimum at 2 pm before a moderate rise.A model for intraday and long-term NDVI change for soybean is built.The test of the model with independent data indicates that the precision meets the demands,with the root mean square error(RMSE)of each day being 3.95,5.45 and 2.86 for the seeding stage,the bean podding stage and the maturation period,respectively.The prediction RMSEs of the soybean NDVI model for soybeans of the three stages for the fifth day are 5.75,2.65 and 5.51,respectively and the prediction RMSEs for the sixth day are 9.74,2.82 and 14.04,respectively according to the data from the first four days.
基金the National Science&Technology Supporting Plan(2011BAD29B08,2012BAH29B04-02)the“111”Project(B12007).
文摘In order to improve the level of multi-functional and automatic observation of crop root system growth,a soil column monitoring system was designed to facilitate in situ dynamic monitoring of root growth and water consumption.The system consists of 20 plastic tubular backfill soil columns,each with an inner diameter of 32 cm and height of 300 cm.The crops were planted at the top of the soil column with the surrounding leveled with the ground surface and the site is in a greenhouse.The underground portion of the soil column contains small round windows on the tube through which root growth can be monitored,roots can be pruned and soil samples can be obtained.A multiport serial weighing system was designed and placed at the base of the soil column.Twenty electronic balances were connected to the personal computer through three CP-168U multiport serial cards and RS-232 serial cables.The host software was developed on the browser/server(Browser/Server),and data collection and remote data transmission and data sharing were implemented using the Java programming language and applying Internet data transmission technology and Web application technology.System tests showed a relatively good stability and real-time capability,and with accuracy up to 50 g and the evapotranspiration of each soil column was 0.25-0.65 kg per day.The root-system observation system developed in this study surpassed the traditional method of root-digging sampling and thus provided an alternative that could be used to automatically monitor the root system growth status.
