Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° ...Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that： the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.展开更多
China is one of the world's largest agricultural countries, planting a variety of crops, and maize is one of which has a relatively large planting area and is an important food and commercial crop. With the develo...China is one of the world's largest agricultural countries, planting a variety of crops, and maize is one of which has a relatively large planting area and is an important food and commercial crop. With the development of agricultural modernization, the high-yield planting technology of maize has been in continuous research and development, among which many advanced technologies have been applied. Wide-narrow row alternate planting is one of the more representative ones, and its application scope is very wide. Almost all planting areas of maize are adopting it, which has made an important contribution to the improvement of high-yield and quality of maize. In this paper, the application of maize's wide and narrow row alternate planting technology is analyzed in depth.展开更多
Paddy field management is complicated and labor intensive.Correct row detection is important to automatically track rice rows.In this study,a novel method was proposed for accurate rice row recognition in paddy field ...Paddy field management is complicated and labor intensive.Correct row detection is important to automatically track rice rows.In this study,a novel method was proposed for accurate rice row recognition in paddy field transplanted by machine before the disappearance of row information.Firstly,Bayesian decision theory based on the minimum error was used to classify the period of collected images into three periods(T1:0-7 d;T2:7-28 d;T3:28-45 d),and resulting in the correct recognition rate was 97.03%.Moreover,secondary clustering of feature points was proposed,which can solve some problems such as row breaking and tilting.Then,the robust regression least squares method(RRLSM)for linear fitting was proposed to fit rice rows to effectively eliminate interference by outliers.Finally,a credibility analysis of connected region markers was proposed to evaluate the accuracy of fitting lines.When the threshold of credibility was set at 40%,the correct recognition rate of fitting lines was 96.32%.The result showed that the method can effectively solve the problems caused by the presence of duckweed,high-density inter-row weeds,broken rows,tilting(±60°),wind and overlap.展开更多
Crop rows detection in maize fields remains a challenging problem due to variation in illumination and weeds interference under field conditions.This study proposed an algorithm for detecting crop rows based on adapti...Crop rows detection in maize fields remains a challenging problem due to variation in illumination and weeds interference under field conditions.This study proposed an algorithm for detecting crop rows based on adaptive multi-region of interest(multi-ROI).First,the image was segmented into crop and soil and divided into several horizontally labeled strips.Feature points were located in the first image strip and initial ROI was determined.Then,the ROI window was shifted upward.For the next image strip,the operations for the previous strip were repeated until multiple ROIs were obtained.Finally,the least square method was carried out to extract navigation lines and detection lines in multi-ROI.The detection accuracy of the method was 95.3%.The average computation time was 240.8 ms.The results suggest that the proposed method has generally favorable performance and can meet the real-time and accuracy requirements for field navigation.展开更多
Sugarcane planting is an important and growing activity in Brazil.Thereupon,several techniques have been developed over the years to maximize crop productivity and profit,amongst them,processing of sugarcane field ima...Sugarcane planting is an important and growing activity in Brazil.Thereupon,several techniques have been developed over the years to maximize crop productivity and profit,amongst them,processing of sugarcane field images.In this sense,this research aims to identify and analyze crop rows and measure their gaps from aerial images of sugarcane fields.For this,a small Remotely Piloted Aircraft captured the images,generating orthomosaics of the areas for analysis.Then,each orthomosaic is classified with the K-Nearest Neighbor algorithm to segment regions of interest.Planting row orientation is estimated using the RGB gradient filter.Morphological operations and computational geometry models are then used to detect and map rows and gaps along the planting row segment.To evaluate the results,crop rows are mapped and compared to manually taken measurements.Our technique obtained an error smaller than 2%when compared to gap length in crop rows from an orthomosaic with the area of 8.05 ha(ha).The proposed approach can map the positioning of the automatically generated row segments appropriately onto manually created segments.Moreover,our method also achieved similar results when confronted with a manual technique for differing growth stages(40 and 80 days after harvest)of the sugarcane crop.The proposed method presents a great potential to be adopted in sugarcane planting monitoring。展开更多
This paper describes the numerical simulation of three-dimensional viscous flows in fir-cooled turbine blade rows with the effects of coolant ejection. A TVD Navier-Stokes flow solver incorporated with Baldwin-Lomax t...This paper describes the numerical simulation of three-dimensional viscous flows in fir-cooled turbine blade rows with the effects of coolant ejection. A TVD Navier-Stokes flow solver incorporated with Baldwin-Lomax turbulence model and multi-grid convergence acceleration algorithm are used for the simulation. The influences of coolant ejection on the main flow are accounted by volumetric coolant source terms. Numerical results for a four-stage turbine are presented and discussed.展开更多
Using a split plot design, super high-yielding early rice ＆quot;Zhongjiazao 17＆quot;and ＆quot;Ganxin 203＆quot; and super high-yielding late rice ＆quot;Ganxin 688＆quot; and ＆quot;Wufengy-ouT025＆quot; were taken...Using a split plot design, super high-yielding early rice ＆quot;Zhongjiazao 17＆quot;and ＆quot;Ganxin 203＆quot; and super high-yielding late rice ＆quot;Ganxin 688＆quot; and ＆quot;Wufengy-ouT025＆quot; were taken as materials with planting density the same at 312 000 hil s/hm2, to explore the effects of RS/IS （Ratio of row spacing to intrarow row spacing） on yield, top three leaves morphological features and its relationship of them in 2011 and 2012. The results showed that, whether early or late rice, biomass, accumula-tion and apparent utilizing rate of nitrogen were lower in RS/IS5.0 （40.0 cm ＆#215;8.0 cm） treatment, but yield of rice was higher in RS/IS2.0 （25.0 cm ＆#215;12.8 cm） treatment;grain numbers per spike of rice was more in RS/IS2.8 （30.0 cm＆#215;10.7 cm） treatment, and thousand-grain weight of rice was higher in RS/IS1.3 （20.0 cm＆#215;16.0 cm） treat-ment. For 4 varieties of early or late rice aforementioned, basal angle, opening an-gle and leaf area of 2nd leaf from top were larger in RS/IS5.0 treatment, and basal angle and opening angle were smal er in RS/IS2.0 treatment and leaf area smal er in RS/IS1.3 treatment.展开更多
Rice leaf morphology is of great significance in the breeding of an ideal plant type and high photosynthetic efficiency.A forward genetics approach was employed to locate a novel gene,NRL9(NARROW AND ROLLED LEAF 9).NR...Rice leaf morphology is of great significance in the breeding of an ideal plant type and high photosynthetic efficiency.A forward genetics approach was employed to locate a novel gene,NRL9(NARROW AND ROLLED LEAF 9).NRL9 encodes a 20S proteasome β1 subunit and is involved in regulating leaf morphology and grain size.Compared with the wild type(WT),the nrl9 mutant exhibited a significant decrease in leaf width,and a significant increase in leaf rolling index(LRI),while also displaying increased grain length and decreased grain width.展开更多
How would you move an entire 7,500‐tonne,4,030‐square‐meter,and 100‐year‐old Shikumen brick building complex so that you could build a multi‐level underground shopping center,parking lot and subway connections u...How would you move an entire 7,500‐tonne,4,030‐square‐meter,and 100‐year‐old Shikumen brick building complex so that you could build a multi‐level underground shopping center,parking lot and subway connections under it?The answer is robots.That's exactly what engineers did in Shanghai.The Huayanli Shikumen complex—a mix of Western row houses and Chinese courtyards,which stands as Shanghai's largest and best‐preserved Shikumen complexes—was built in the 1920s and 1930s.It had to be moved temporarily to make space for the 53,000‐square‐meter underground project.展开更多
[Objectives]To provide a reference for the promotion of appropriate row spacing configuration modes for cotton planting in the Bortala Mongol Autonomous Prefecture of Xinjiang.[Methods]Xinluzao 63 was employed as the ...[Objectives]To provide a reference for the promotion of appropriate row spacing configuration modes for cotton planting in the Bortala Mongol Autonomous Prefecture of Xinjiang.[Methods]Xinluzao 63 was employed as the research subject to examine the effects of three different configuration modes:three rows with one film,four rows with one film,and six rows with one film,on the growth and development of cotton,as well as on yield and the amount of residual film in the field.[Results]In comparison to the configuration modes of four rows with one film and six rows with one film,the development process in the row spacing configuration mode of three rows with one film was accelerated by 1-4 d.This configuration mode exhibited variability in several agronomic traits,particularly in plant height,the number of fruiting branches per plant,and the number of leaves per plant,with the observed trend indicating T3>T2>T1.Conversely,the height of the first fruiting branch node displayed an inverse trend.In terms of yield composition,no significant differences were observed in boll weight and yield among various configuration modes.However,T3 exhibited the highest boll weight at 5.68 g and a yield of 462.67 kg/667 m 2.Additionally,significant differences were noted in harvesting density and the number of bolls per plant.T3 demonstrated the lowest harvesting density at 1.11×104 plants/666.7 m 2,the highest number of bolls per plant at 8.63,and the highest boll opening rate at 97.48%.Furthermore,T3 also resulted in the least amount of agricultural film residue during the current season.[Conclusions]Among the three planting configuration modes examined,the low-density planting configuration mode consisting of three rows and one film demonstrated a significant advantage at the individual plant level.This approach yielded results comparable to those of the high density planting configuration mode while also reducing costs.Furthermore,low density planting positively influenced the cotton boll opening rate,leading to a decreased amount of residual film and promoting ecological health within the agricultural land.展开更多
[Objective] This study was conducted to investigate the effects of different plant spacing on tobacco grade structure, growth stages, agronomic traits, yield and chemical composition under fixed row spacing. [Method] ...[Objective] This study was conducted to investigate the effects of different plant spacing on tobacco grade structure, growth stages, agronomic traits, yield and chemical composition under fixed row spacing. [Method] Under fixed row spacing （120 cm）, 4 treatments were designed （40, 50, 60 and 45 cm）. The growth stages, agronomic traits, economic traits and chemical composition of flue-cured tobacco leaves were compared and analyzed. [Result] with the increase of plant spacing, there were no significant differences in the emergence time of growth stages be- tween different treatment groups before resettling stage, and the resettling stage ap- peared 1-2 d in advance. At different tobacco growth stages, the changing trends of tobacco agronomic traits with the change of plant spacing were different. [Conclusion] With the increase of plant spacing, the planting density of tobacco de- creased, and the nicotine content increased; and the yield of tobacco decreased continuously, while the quality was improved, but when the plant spacing was im- proved to certain degree, the quality of tobacco also decreased, and at the plant spacing of 50 cm, the output value of tobacco was the highest.展开更多
基金supported by the National Natural Science Foundation of China (No. 51206008)
文摘Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that： the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.
文摘China is one of the world's largest agricultural countries, planting a variety of crops, and maize is one of which has a relatively large planting area and is an important food and commercial crop. With the development of agricultural modernization, the high-yield planting technology of maize has been in continuous research and development, among which many advanced technologies have been applied. Wide-narrow row alternate planting is one of the more representative ones, and its application scope is very wide. Almost all planting areas of maize are adopting it, which has made an important contribution to the improvement of high-yield and quality of maize. In this paper, the application of maize's wide and narrow row alternate planting technology is analyzed in depth.
基金This work was financially supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2019B020221002)and the National Key Research and Development Program of China(Grant No.2017YFD0701105)The authors also acknowledge the anonymous reviewers for their critical comments and suggestions for improving the manuscript.
文摘Paddy field management is complicated and labor intensive.Correct row detection is important to automatically track rice rows.In this study,a novel method was proposed for accurate rice row recognition in paddy field transplanted by machine before the disappearance of row information.Firstly,Bayesian decision theory based on the minimum error was used to classify the period of collected images into three periods(T1:0-7 d;T2:7-28 d;T3:28-45 d),and resulting in the correct recognition rate was 97.03%.Moreover,secondary clustering of feature points was proposed,which can solve some problems such as row breaking and tilting.Then,the robust regression least squares method(RRLSM)for linear fitting was proposed to fit rice rows to effectively eliminate interference by outliers.Finally,a credibility analysis of connected region markers was proposed to evaluate the accuracy of fitting lines.When the threshold of credibility was set at 40%,the correct recognition rate of fitting lines was 96.32%.The result showed that the method can effectively solve the problems caused by the presence of duckweed,high-density inter-row weeds,broken rows,tilting(±60°),wind and overlap.
基金The authors acknowledge that the research was financially supported by the National Key Research and Development Program of China(Grant No.2017YFD0700902)the University Synergy Innovation Program of Anhui Province(Grant No.GXXT-2020-011).
文摘Crop rows detection in maize fields remains a challenging problem due to variation in illumination and weeds interference under field conditions.This study proposed an algorithm for detecting crop rows based on adaptive multi-region of interest(multi-ROI).First,the image was segmented into crop and soil and divided into several horizontally labeled strips.Feature points were located in the first image strip and initial ROI was determined.Then,the ROI window was shifted upward.For the next image strip,the operations for the previous strip were repeated until multiple ROIs were obtained.Finally,the least square method was carried out to extract navigation lines and detection lines in multi-ROI.The detection accuracy of the method was 95.3%.The average computation time was 240.8 ms.The results suggest that the proposed method has generally favorable performance and can meet the real-time and accuracy requirements for field navigation.
基金Sao Paulo Research Founda-tion(FAPESP grant#2017/12646-3)National Council for Scien-tific and Technological Development(CNPq grant#309330/2018-1)Coordination for the Improvement of Higher Education Personnel(CAPES Finance Code#001)for their financial support.
文摘Sugarcane planting is an important and growing activity in Brazil.Thereupon,several techniques have been developed over the years to maximize crop productivity and profit,amongst them,processing of sugarcane field images.In this sense,this research aims to identify and analyze crop rows and measure their gaps from aerial images of sugarcane fields.For this,a small Remotely Piloted Aircraft captured the images,generating orthomosaics of the areas for analysis.Then,each orthomosaic is classified with the K-Nearest Neighbor algorithm to segment regions of interest.Planting row orientation is estimated using the RGB gradient filter.Morphological operations and computational geometry models are then used to detect and map rows and gaps along the planting row segment.To evaluate the results,crop rows are mapped and compared to manually taken measurements.Our technique obtained an error smaller than 2%when compared to gap length in crop rows from an orthomosaic with the area of 8.05 ha(ha).The proposed approach can map the positioning of the automatically generated row segments appropriately onto manually created segments.Moreover,our method also achieved similar results when confronted with a manual technique for differing growth stages(40 and 80 days after harvest)of the sugarcane crop.The proposed method presents a great potential to be adopted in sugarcane planting monitoring。
基金the National High Technology Research and Development Program of China through grant number 2002AA503010
文摘This paper describes the numerical simulation of three-dimensional viscous flows in fir-cooled turbine blade rows with the effects of coolant ejection. A TVD Navier-Stokes flow solver incorporated with Baldwin-Lomax turbulence model and multi-grid convergence acceleration algorithm are used for the simulation. The influences of coolant ejection on the main flow are accounted by volumetric coolant source terms. Numerical results for a four-stage turbine are presented and discussed.
基金Supported by National Key Technology Research and Development Program of China(2012BAD15B03)the Youth Innovation Fund of Jiangxi Academy of Agricultural Sciences(2010-CQN004)~~
文摘Using a split plot design, super high-yielding early rice ＆quot;Zhongjiazao 17＆quot;and ＆quot;Ganxin 203＆quot; and super high-yielding late rice ＆quot;Ganxin 688＆quot; and ＆quot;Wufengy-ouT025＆quot; were taken as materials with planting density the same at 312 000 hil s/hm2, to explore the effects of RS/IS （Ratio of row spacing to intrarow row spacing） on yield, top three leaves morphological features and its relationship of them in 2011 and 2012. The results showed that, whether early or late rice, biomass, accumula-tion and apparent utilizing rate of nitrogen were lower in RS/IS5.0 （40.0 cm ＆#215;8.0 cm） treatment, but yield of rice was higher in RS/IS2.0 （25.0 cm ＆#215;12.8 cm） treatment;grain numbers per spike of rice was more in RS/IS2.8 （30.0 cm＆#215;10.7 cm） treatment, and thousand-grain weight of rice was higher in RS/IS1.3 （20.0 cm＆#215;16.0 cm） treat-ment. For 4 varieties of early or late rice aforementioned, basal angle, opening an-gle and leaf area of 2nd leaf from top were larger in RS/IS5.0 treatment, and basal angle and opening angle were smal er in RS/IS2.0 treatment and leaf area smal er in RS/IS1.3 treatment.
基金supported by the National Major Science and Technology Program on New Genetically Modified Organism Variety Breeding,China(Grant No.2016ZX08001-001).
文摘Rice leaf morphology is of great significance in the breeding of an ideal plant type and high photosynthetic efficiency.A forward genetics approach was employed to locate a novel gene,NRL9(NARROW AND ROLLED LEAF 9).NRL9 encodes a 20S proteasome β1 subunit and is involved in regulating leaf morphology and grain size.Compared with the wild type(WT),the nrl9 mutant exhibited a significant decrease in leaf width,and a significant increase in leaf rolling index(LRI),while also displaying increased grain length and decreased grain width.
文摘How would you move an entire 7,500‐tonne,4,030‐square‐meter,and 100‐year‐old Shikumen brick building complex so that you could build a multi‐level underground shopping center,parking lot and subway connections under it?The answer is robots.That's exactly what engineers did in Shanghai.The Huayanli Shikumen complex—a mix of Western row houses and Chinese courtyards,which stands as Shanghai's largest and best‐preserved Shikumen complexes—was built in the 1920s and 1930s.It had to be moved temporarily to make space for the 53,000‐square‐meter underground project.
基金Supported by China Agriculture(Cotton)Research System(CARS-15-46)Intellectual Aid Xinjiang Innovation and Expansion Talent Program of Xinjiang Uygur Autonomous Region(2024500207).
文摘[Objectives]To provide a reference for the promotion of appropriate row spacing configuration modes for cotton planting in the Bortala Mongol Autonomous Prefecture of Xinjiang.[Methods]Xinluzao 63 was employed as the research subject to examine the effects of three different configuration modes:three rows with one film,four rows with one film,and six rows with one film,on the growth and development of cotton,as well as on yield and the amount of residual film in the field.[Results]In comparison to the configuration modes of four rows with one film and six rows with one film,the development process in the row spacing configuration mode of three rows with one film was accelerated by 1-4 d.This configuration mode exhibited variability in several agronomic traits,particularly in plant height,the number of fruiting branches per plant,and the number of leaves per plant,with the observed trend indicating T3>T2>T1.Conversely,the height of the first fruiting branch node displayed an inverse trend.In terms of yield composition,no significant differences were observed in boll weight and yield among various configuration modes.However,T3 exhibited the highest boll weight at 5.68 g and a yield of 462.67 kg/667 m 2.Additionally,significant differences were noted in harvesting density and the number of bolls per plant.T3 demonstrated the lowest harvesting density at 1.11×104 plants/666.7 m 2,the highest number of bolls per plant at 8.63,and the highest boll opening rate at 97.48%.Furthermore,T3 also resulted in the least amount of agricultural film residue during the current season.[Conclusions]Among the three planting configuration modes examined,the low-density planting configuration mode consisting of three rows and one film demonstrated a significant advantage at the individual plant level.This approach yielded results comparable to those of the high density planting configuration mode while also reducing costs.Furthermore,low density planting positively influenced the cotton boll opening rate,leading to a decreased amount of residual film and promoting ecological health within the agricultural land.
基金Supported by Project of Luzhou Branch Company of Sicuan Tobacco Company:Application of Integrated Technique for Improving Tobacco Grade Structure~~
文摘[Objective] This study was conducted to investigate the effects of different plant spacing on tobacco grade structure, growth stages, agronomic traits, yield and chemical composition under fixed row spacing. [Method] Under fixed row spacing （120 cm）, 4 treatments were designed （40, 50, 60 and 45 cm）. The growth stages, agronomic traits, economic traits and chemical composition of flue-cured tobacco leaves were compared and analyzed. [Result] with the increase of plant spacing, there were no significant differences in the emergence time of growth stages be- tween different treatment groups before resettling stage, and the resettling stage ap- peared 1-2 d in advance. At different tobacco growth stages, the changing trends of tobacco agronomic traits with the change of plant spacing were different. [Conclusion] With the increase of plant spacing, the planting density of tobacco de- creased, and the nicotine content increased; and the yield of tobacco decreased continuously, while the quality was improved, but when the plant spacing was im- proved to certain degree, the quality of tobacco also decreased, and at the plant spacing of 50 cm, the output value of tobacco was the highest.
