The demand for lightweight and multifunctional surface structure in high-end equipment is steadily growing.The harmonization between flexibility and electromagnetic tunability has become a significant subject for stea...The demand for lightweight and multifunctional surface structure in high-end equipment is steadily growing.The harmonization between flexibility and electromagnetic tunability has become a significant subject for stealth morphing aircraft.This paper presents a microwave absorbing structure based on the kirigami configuration,aiming at improving the conformality with the negative Poisson’s ratio characteristic and expanding the radar stealth range with tunability.A precise electromagnetic reflectivity model of the impedance surface was established by the inversion method,and an integrated optimization algorithm was employed to optimize the structural parameters based on numerical analysis.Specimens composed of thermoplastic polyurethane elastic colloids and resistive materials were prepared to assess the in-plane mechanical tensile and electromagnetic absorption performances through experimental methods.The results indicate that the original absorption band spans 6.2-11.1 GHz,shifts to 8-18 GHz with stretching at a panel rotation angle of 16°,and remains nearly constant for further stretching.The specimens adhere to complex curved surfaces well in experiments and maintain the electromagnetic absorption performance compared with flat surfaces.This research offers a valuable reference for designing electromagnetic stealth structures that are highly stretchable and adjustable.展开更多
Objective Bronchoscopy has been extensively used in the diagnosis of respiratory diseases, and par- ticularly, malignant diseases. However, endoscopists do not normally perform bronchoscopic biopsy in Case lesions are...Objective Bronchoscopy has been extensively used in the diagnosis of respiratory diseases, and par- ticularly, malignant diseases. However, endoscopists do not normally perform bronchoscopic biopsy in Case lesions are undetected via bronchoscopy. The aim of this study was to evaluate whether performing bron- choscopic biopsy could be established in the diagnosis of lung cancer in case of endobronchial abnormali- ties undetectable to the naked eye. Methods We retrospectively analyzed 109 cases between January 2008 and December 2012. The in- clusion criteria were confirmed lung cancer diagnosis, transbronchial biopsy performed in the absence of visible endobronchial manifestations, brushing, and bronchoalveolar lavage （BAL） according to the images obtained from high-resolution computed tomography （HRCT）. Data regarding age, sex, pathology, tumor stage; the method of diagnosis; location of primary lesion （central, peripheral, or intermediate）; tumor size, mediastinal lymph node metastasis, and the serum carcinoembryonic antigen （CEA） value were collected. The Pearson chi-square test or Fisher＇s exact and McNemar tests were used in the univadate analysis. Results Among the 109 patients, the diagnosis of 37 （33.9%） patients was confirmed through bronchos- copy. Brushing and BAL had higher positive detection rates than biopsy （P = 0.004）. There were no differ- ences in the positive detection rates between the sex, pathology, lesion location, tumor size, lymph node metastasis, and the serum CEA value （P〈 0.05 for all groups）. Conclusion Despite the normal appearance of the endobronchial manifestations, lesions undetectable by bronchoscopy could be indicated. Therefore, we suggest performing bronchoscopic biopsy and that brushing and BAL might increase the positive detection rate of bronchoscepic examination.展开更多
One major constraint in developing a combine harvester cum seed drill(CHCSD)is the limited space available for the attachment of no-till furrow openers.Investigating the straw stubble cutting and furrow opening perfor...One major constraint in developing a combine harvester cum seed drill(CHCSD)is the limited space available for the attachment of no-till furrow openers.Investigating the straw stubble cutting and furrow opening performance of small-sized disc furrow openers is critically important for the development and the optimization of the no-till seeding assemblies.A set of down-scaled sliding knife notch-type disc opener(SKO),modified notch-type disc opener(MNO)and smooth-type disc opener(SDO),with upper size limit of 160 mm,were designed and fabricated for field testing.Experimental results show that for small-sized disc furrow openers of the same type,a larger disc diameter yields a greater furrow depth and width.For small-sized disc furrow openers with an identical diameter,SKOs yield a greater furrow depth and width than MNOs,with SDOs yielding the lowest values.The measured furrow depth and width for an SKO with diameter of 160 mm are 3.52 cm and 3.56 cm,respectively,meeting the no-tillage furrowing requirements for a CHCSD.The highest stubble cover rate of 62.5%is obtained for the SKO with diameter of 160 mm.Therefore,this opener has greater ability to remove stubble from the furrow and seeding band than the other designs.Finally,experimental results of the stubble cutting rates confirm that,for irregularly placed straw and residue,the stubble cutting rate of the SKO with diameter of 160 mm is the highest at 61.7%.展开更多
For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in p...For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in paddy soil.Discrete element simulation was done to develop a 3D DEM model for notched,toothed and double disc furrow openers using EDEM software.Hertz Mindlin contact model with bonding was applied for simulation to fulfill the obligations of the soil moisture and bonding between the cohesive particles.Simulated and field experimental data were compared to determine the applicability in the different working conditions.The results of the simulation validated the applicability of the Hertz-Mindlin contact model with bonding to simulate the no till paddy soil using an extremely narrow tillage tool.The calibrated value of normal and shear stiffness was 5×10^(7)N/m,and the calibrated value of bond normal and shear strength was 3×10^(7)Pa.The relative error(-1.7%to 20.6%)for the double disc furrow opener was lower as compared with that notch typed(29.2%to 44.4%)and toothed type(31.5%to 45.9%)furrow openers.展开更多
An orchard-lifting platform is a type of mechanical equipment to assist growers in fruit picking,fruit tree pruning,flower thinning,and other operations.In its operational processes,the tilting stability directly affe...An orchard-lifting platform is a type of mechanical equipment to assist growers in fruit picking,fruit tree pruning,flower thinning,and other operations.In its operational processes,the tilting stability directly affects the operational safety and adaptability under complex terrain conditions,while critical tilting angle is an important criterion to evaluate the tilting stability.Based on the structure and the operating characteristics of the three degree of freedom(3-DOF)lifting platform for hilly orchards,the tilting stability was analyzed in different parked states,and the theoretical expressions of critical tilting angle were obtained;in the theoretical expressions,the influencing factors on tilting stability were determined as the parked positionβ1,the manned worktable rotary positionβ2,the lifting height h,and the load m.Based on the multi-body dynamics principle,the tilting stability simulation was carried out.The relative error of tilting angles was approximately 4.6%between simulation and tilting verification experiment,which indicated that the results of tilting stability simulation were reliable.Therefore,the multi-body dynamics simulation was used for further clarifying the influencing factors on tilting stability.A virtual orthogonal test was designed,and the results showed that critical tilting angle ranged from 20°to 44°when the factors were at different values,which indicated that the 3-DOF lifting platform for hilly orchards had a high tilting stability performance and could adapt to the operating conditions of hills with slope angles from 5°to 20°.The results of the range analysis and ANOVA showed that the influence intensity of factors on tilting stability wasβ1>h>m>β2;at the same time,β1,h,and m exerted significant effect on tilting stability.The tilting stability first decreased and then either increased or decreased with the increasing lifting height;it gradually decreased with the increasing load.It also showed that the position of the manned worktable along the slope down always had the lowest tilting stability.This research can provide a theoretical basis and reference for the analysis of tilting stability of the lifting machinery for hilly orchards.展开更多
In order to solve the problem of poor traveling stability and excessive pesticide application during plant protection operations in hilly orchards,a novel crawler-type multi-channel air-assisted sprayer that is partic...In order to solve the problem of poor traveling stability and excessive pesticide application during plant protection operations in hilly orchards,a novel crawler-type multi-channel air-assisted sprayer that is particularly appropriate for hilly orchards was designed in this study.Considering anti-rolling requirements and the orchard environment in hilly areas,this study selected limits for uphill and downhill rolling angles as well as the transverse rolling angle as the evaluation indexes for determining both the layout and parameter settings of the sprayer.According to freely submerged jets and the requirements in plant protection operation,a multi-channel air-assisted system was developed.The test results showed that the anti-rolling performance and the designed air-assisted system were adequate.At 2 m from the longitudinal center plane of the sprayer,the airflow exhibited wavy distribution patterns under different parameter combinations since the four streams of the airflow were not thoroughly intersected and mixed.At 3 m from the longitudinal center plane of the sprayer,the jet was ejected at great velocity but underwent rapid attenuation;the airflow velocity in most areas barely satisfied the requirements for plant protection operation.In addition,different air outlet layout schemes led to significant differences in the spatial distribution of the airflow field.Compared with a traditional air-assisted sprayer,using the developed multi-channel air-assisted sprayer enhanced the droplet coverage uniformity by 19.4%,and the mean droplet deposition in the front,middle,and rear of the canopy was enhanced by 32.9%,50.3%,and 78.1%,respectively,while reducing ground deposition and air drift by 26.8%.展开更多
As confusion mounts over RNA isoforms involved in phenotypic plasticity,aberrant CpG methylation-mediated disruption of alternative splicing is increasingly recognized as a driver of intratumor heterogeneity(ITH).Prot...As confusion mounts over RNA isoforms involved in phenotypic plasticity,aberrant CpG methylation-mediated disruption of alternative splicing is increasingly recognized as a driver of intratumor heterogeneity(ITH).Protease serine 3(PRSS3),possessing four splice variants(PRSS3-SVs;PRSS3-V1—V4),is an indispensable trypsin that shows paradoxical effects on cancer development.Here,we found that PRSS3 transcripts and their isoforms were divergently expressed in lung cancer,exhibiting opposing functions and clinical outcomes,namely,oncogenic PRSS3-V1 and PRSS3-V2 versus tumorsuppressive PRSS3-V3,by targeting different downstream genes.We identified an intragenic CpG island(iCpGI)in PRSS3.Hypermethylation of iCpGI was mediated by UHRF1/DNMT1 complex interference with the binding of myeloid zinc finger 1(MZF1)to regulate PRSS3 transcription.The garlic-derived compound diallyl trisulfide cooperated with 5-aza-2'-deoxycytidine to exert antitumor effects in lung adenocarcinoma cells through site-specific iCpGI demethylation specifically allowing MZF1 to upregulate PRSS3-V3 expression.Epigenetic silencing of PRSS3-V3 via i CpGI methylation(iCpGIm)in BALF and tumor tissues was associated with early clinical progression in patients with lung cancer but not in those with squamous cell carcinoma or inflammatory disease.Thus,UHRF1/DNMT1—MZF1 axismodulated site-specific iCpGIm regulates divergent expression of PRSS3-SVs,conferring nongenetic functional ITH,with implications for early detection of lung cancer and targeted therapies.展开更多
Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with hi...Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with high penetration and low drift was developed.The air-assisted system of this equipment was centrosymmetric,and the fan type was cross-flow.The fan outlet width was 138 mm and the air duct’s main body followed a logarithmic spiral profile,based on parallel flow theory.The external diameter of the impeller was 157 mm,which was fixed into a barrel structure by 23 strong forward-curved blades,each being 1 mm thick.The central angle of the blades was 108°,and the ratio of the internal and external diameters was 0.81.The impeller and air duct served as guides to circulate and reciprocate airflow around the crown,forming a tunnel-convective air-assisted to the vine.Using MATLAB interpolation,the airflow trajectory of the air convection circulation in the door-shaped cover was obtained.The velocity field distribution test showed that,in the case of a canopy,there were tunnel-convective circulating airflows with high velocity on both sides and uniform velocity in the middle of the canopy.Due to the tunnel-convective air-assisted spraying technology,the vertical distribution uniformity of spray deposition has been significantly improved,spray penetration has been enhanced,penetrability has been effectively improved,and droplets on the ground and in the air have been significantly reduced.The results of this study can assist in providing further optimization and improvement of plant protection machinery.The new tunnel-convective air-assisted spraying technology may be a more favorable choice for future spray applications and the environment.展开更多
The purpose of this work is to develop a new analysis model for angular-contact,ball-bearing systems on the basis of plate theory instead of commonly known approaches that utilize spring elements.Axial and radial stif...The purpose of this work is to develop a new analysis model for angular-contact,ball-bearing systems on the basis of plate theory instead of commonly known approaches that utilize spring elements.Axial and radial stiffness on an annular plate are developed based on plate,Timoshenko beam,and plasticity theories.The model is developed using theoretical and inductive methods and validated through a numerical simulation with the finite element method.The new analysis model is suitable for static and modal analyses of rotor-bearing systems.Numerical examples are presented to reveal the effectiveness and applicability of the proposed approach.展开更多
基金supported by the National Key Research and Development of China(Grant No.2022YFB4601901)the National Natural Science Foundation of China(Grant Nos.12122202 and 12302078)the Postdoctoral Innovative Talents Support Program of China(Grant No.BX20230470).
文摘The demand for lightweight and multifunctional surface structure in high-end equipment is steadily growing.The harmonization between flexibility and electromagnetic tunability has become a significant subject for stealth morphing aircraft.This paper presents a microwave absorbing structure based on the kirigami configuration,aiming at improving the conformality with the negative Poisson’s ratio characteristic and expanding the radar stealth range with tunability.A precise electromagnetic reflectivity model of the impedance surface was established by the inversion method,and an integrated optimization algorithm was employed to optimize the structural parameters based on numerical analysis.Specimens composed of thermoplastic polyurethane elastic colloids and resistive materials were prepared to assess the in-plane mechanical tensile and electromagnetic absorption performances through experimental methods.The results indicate that the original absorption band spans 6.2-11.1 GHz,shifts to 8-18 GHz with stretching at a panel rotation angle of 16°,and remains nearly constant for further stretching.The specimens adhere to complex curved surfaces well in experiments and maintain the electromagnetic absorption performance compared with flat surfaces.This research offers a valuable reference for designing electromagnetic stealth structures that are highly stretchable and adjustable.
文摘Objective Bronchoscopy has been extensively used in the diagnosis of respiratory diseases, and par- ticularly, malignant diseases. However, endoscopists do not normally perform bronchoscopic biopsy in Case lesions are undetected via bronchoscopy. The aim of this study was to evaluate whether performing bron- choscopic biopsy could be established in the diagnosis of lung cancer in case of endobronchial abnormali- ties undetectable to the naked eye. Methods We retrospectively analyzed 109 cases between January 2008 and December 2012. The in- clusion criteria were confirmed lung cancer diagnosis, transbronchial biopsy performed in the absence of visible endobronchial manifestations, brushing, and bronchoalveolar lavage （BAL） according to the images obtained from high-resolution computed tomography （HRCT）. Data regarding age, sex, pathology, tumor stage; the method of diagnosis; location of primary lesion （central, peripheral, or intermediate）; tumor size, mediastinal lymph node metastasis, and the serum carcinoembryonic antigen （CEA） value were collected. The Pearson chi-square test or Fisher＇s exact and McNemar tests were used in the univadate analysis. Results Among the 109 patients, the diagnosis of 37 （33.9%） patients was confirmed through bronchos- copy. Brushing and BAL had higher positive detection rates than biopsy （P = 0.004）. There were no differ- ences in the positive detection rates between the sex, pathology, lesion location, tumor size, lymph node metastasis, and the serum CEA value （P〈 0.05 for all groups）. Conclusion Despite the normal appearance of the endobronchial manifestations, lesions undetectable by bronchoscopy could be indicated. Therefore, we suggest performing bronchoscopic biopsy and that brushing and BAL might increase the positive detection rate of bronchoscepic examination.
基金The research was financially supported by the National Science and Technology Support Program(No.2013BAD08B04).
文摘One major constraint in developing a combine harvester cum seed drill(CHCSD)is the limited space available for the attachment of no-till furrow openers.Investigating the straw stubble cutting and furrow opening performance of small-sized disc furrow openers is critically important for the development and the optimization of the no-till seeding assemblies.A set of down-scaled sliding knife notch-type disc opener(SKO),modified notch-type disc opener(MNO)and smooth-type disc opener(SDO),with upper size limit of 160 mm,were designed and fabricated for field testing.Experimental results show that for small-sized disc furrow openers of the same type,a larger disc diameter yields a greater furrow depth and width.For small-sized disc furrow openers with an identical diameter,SKOs yield a greater furrow depth and width than MNOs,with SDOs yielding the lowest values.The measured furrow depth and width for an SKO with diameter of 160 mm are 3.52 cm and 3.56 cm,respectively,meeting the no-tillage furrowing requirements for a CHCSD.The highest stubble cover rate of 62.5%is obtained for the SKO with diameter of 160 mm.Therefore,this opener has greater ability to remove stubble from the furrow and seeding band than the other designs.Finally,experimental results of the stubble cutting rates confirm that,for irregularly placed straw and residue,the stubble cutting rate of the SKO with diameter of 160 mm is the highest at 61.7%.
基金The authors are grateful for the support of the Key Research and Development Project(2016YFD0200708)the Key Research and Development Project(Modern Agriculture)of Jiangsu Province,China(BE2017354)National Science and Technology Support Program(2018BAD08B04).
文摘For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in paddy soil.Discrete element simulation was done to develop a 3D DEM model for notched,toothed and double disc furrow openers using EDEM software.Hertz Mindlin contact model with bonding was applied for simulation to fulfill the obligations of the soil moisture and bonding between the cohesive particles.Simulated and field experimental data were compared to determine the applicability in the different working conditions.The results of the simulation validated the applicability of the Hertz-Mindlin contact model with bonding to simulate the no till paddy soil using an extremely narrow tillage tool.The calibrated value of normal and shear stiffness was 5×10^(7)N/m,and the calibrated value of bond normal and shear strength was 3×10^(7)Pa.The relative error(-1.7%to 20.6%)for the double disc furrow opener was lower as compared with that notch typed(29.2%to 44.4%)and toothed type(31.5%to 45.9%)furrow openers.
基金The research was financially supported by Co-Innovation Center of the Intelligent Management and Equipment for Orchard on the Hilly Land in south China(JX2014XCHJ02).
文摘An orchard-lifting platform is a type of mechanical equipment to assist growers in fruit picking,fruit tree pruning,flower thinning,and other operations.In its operational processes,the tilting stability directly affects the operational safety and adaptability under complex terrain conditions,while critical tilting angle is an important criterion to evaluate the tilting stability.Based on the structure and the operating characteristics of the three degree of freedom(3-DOF)lifting platform for hilly orchards,the tilting stability was analyzed in different parked states,and the theoretical expressions of critical tilting angle were obtained;in the theoretical expressions,the influencing factors on tilting stability were determined as the parked positionβ1,the manned worktable rotary positionβ2,the lifting height h,and the load m.Based on the multi-body dynamics principle,the tilting stability simulation was carried out.The relative error of tilting angles was approximately 4.6%between simulation and tilting verification experiment,which indicated that the results of tilting stability simulation were reliable.Therefore,the multi-body dynamics simulation was used for further clarifying the influencing factors on tilting stability.A virtual orthogonal test was designed,and the results showed that critical tilting angle ranged from 20°to 44°when the factors were at different values,which indicated that the 3-DOF lifting platform for hilly orchards had a high tilting stability performance and could adapt to the operating conditions of hills with slope angles from 5°to 20°.The results of the range analysis and ANOVA showed that the influence intensity of factors on tilting stability wasβ1>h>m>β2;at the same time,β1,h,and m exerted significant effect on tilting stability.The tilting stability first decreased and then either increased or decreased with the increasing lifting height;it gradually decreased with the increasing load.It also showed that the position of the manned worktable along the slope down always had the lowest tilting stability.This research can provide a theoretical basis and reference for the analysis of tilting stability of the lifting machinery for hilly orchards.
基金This project was supported by the National Natural Science Foundation of China(Grant No.51805271)Jiangsu Agricultural Science and Technology Innovation Fund(CX181007)and Fundamental Research Funds for the Central Universities(KYYJ201805).
文摘In order to solve the problem of poor traveling stability and excessive pesticide application during plant protection operations in hilly orchards,a novel crawler-type multi-channel air-assisted sprayer that is particularly appropriate for hilly orchards was designed in this study.Considering anti-rolling requirements and the orchard environment in hilly areas,this study selected limits for uphill and downhill rolling angles as well as the transverse rolling angle as the evaluation indexes for determining both the layout and parameter settings of the sprayer.According to freely submerged jets and the requirements in plant protection operation,a multi-channel air-assisted system was developed.The test results showed that the anti-rolling performance and the designed air-assisted system were adequate.At 2 m from the longitudinal center plane of the sprayer,the airflow exhibited wavy distribution patterns under different parameter combinations since the four streams of the airflow were not thoroughly intersected and mixed.At 3 m from the longitudinal center plane of the sprayer,the jet was ejected at great velocity but underwent rapid attenuation;the airflow velocity in most areas barely satisfied the requirements for plant protection operation.In addition,different air outlet layout schemes led to significant differences in the spatial distribution of the airflow field.Compared with a traditional air-assisted sprayer,using the developed multi-channel air-assisted sprayer enhanced the droplet coverage uniformity by 19.4%,and the mean droplet deposition in the front,middle,and rear of the canopy was enhanced by 32.9%,50.3%,and 78.1%,respectively,while reducing ground deposition and air drift by 26.8%.
基金National Natural Science Foundation of China(NSFC grant No.32200462,China)National Natural Science Foundation of China(NSFC grant No.81872021,China)+4 种基金Beijing Municipal Administration of Hospitals Youth Program(grant No.QMS20221603,China)R&D Program of Beijing Municipal Education Commission(grant No.KM202110025004,China)Beijing Natural Science Foundation of China(BJSFC No.7214242,China)Beijing Municipal Administration of Hospitals Incubating Program(grant No.PX2021063,China)Intramural Research Funding Program from Beijing Tuberculosis and Thoracic Tumor Research Institute/Beijing Chest Hospital。
文摘As confusion mounts over RNA isoforms involved in phenotypic plasticity,aberrant CpG methylation-mediated disruption of alternative splicing is increasingly recognized as a driver of intratumor heterogeneity(ITH).Protease serine 3(PRSS3),possessing four splice variants(PRSS3-SVs;PRSS3-V1—V4),is an indispensable trypsin that shows paradoxical effects on cancer development.Here,we found that PRSS3 transcripts and their isoforms were divergently expressed in lung cancer,exhibiting opposing functions and clinical outcomes,namely,oncogenic PRSS3-V1 and PRSS3-V2 versus tumorsuppressive PRSS3-V3,by targeting different downstream genes.We identified an intragenic CpG island(iCpGI)in PRSS3.Hypermethylation of iCpGI was mediated by UHRF1/DNMT1 complex interference with the binding of myeloid zinc finger 1(MZF1)to regulate PRSS3 transcription.The garlic-derived compound diallyl trisulfide cooperated with 5-aza-2'-deoxycytidine to exert antitumor effects in lung adenocarcinoma cells through site-specific iCpGI demethylation specifically allowing MZF1 to upregulate PRSS3-V3 expression.Epigenetic silencing of PRSS3-V3 via i CpGI methylation(iCpGIm)in BALF and tumor tissues was associated with early clinical progression in patients with lung cancer but not in those with squamous cell carcinoma or inflammatory disease.Thus,UHRF1/DNMT1—MZF1 axismodulated site-specific iCpGIm regulates divergent expression of PRSS3-SVs,conferring nongenetic functional ITH,with implications for early detection of lung cancer and targeted therapies.
基金the National Natural Science Foundation of China(Grant No.51805271)Jiangsu Agricultural Science and Technology Innovation Fund(CX203172,CX181007)+1 种基金‘Qinglan Project’of Jiangsu Province(QLGC)the Fundamental Research Funds for the Central Universities(KYXK2021001).
文摘Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with high penetration and low drift was developed.The air-assisted system of this equipment was centrosymmetric,and the fan type was cross-flow.The fan outlet width was 138 mm and the air duct’s main body followed a logarithmic spiral profile,based on parallel flow theory.The external diameter of the impeller was 157 mm,which was fixed into a barrel structure by 23 strong forward-curved blades,each being 1 mm thick.The central angle of the blades was 108°,and the ratio of the internal and external diameters was 0.81.The impeller and air duct served as guides to circulate and reciprocate airflow around the crown,forming a tunnel-convective air-assisted to the vine.Using MATLAB interpolation,the airflow trajectory of the air convection circulation in the door-shaped cover was obtained.The velocity field distribution test showed that,in the case of a canopy,there were tunnel-convective circulating airflows with high velocity on both sides and uniform velocity in the middle of the canopy.Due to the tunnel-convective air-assisted spraying technology,the vertical distribution uniformity of spray deposition has been significantly improved,spray penetration has been enhanced,penetrability has been effectively improved,and droplets on the ground and in the air have been significantly reduced.The results of this study can assist in providing further optimization and improvement of plant protection machinery.The new tunnel-convective air-assisted spraying technology may be a more favorable choice for future spray applications and the environment.
基金The authors would like to thank Professor Hongguang Li of Shanghai Jiao Tong University for his valuable comments on this paper.The authors are grateful for the support of the National Natural Science Foundation of China(Grant Nos.U1637206 and 51705311)the SAST Project(Grant No.SAST2017-079)the State Key Laboratory of Mechanical System and Vibration of Shanghai Jiao Tong University(Grant No.MSVZD201709).
文摘The purpose of this work is to develop a new analysis model for angular-contact,ball-bearing systems on the basis of plate theory instead of commonly known approaches that utilize spring elements.Axial and radial stiffness on an annular plate are developed based on plate,Timoshenko beam,and plasticity theories.The model is developed using theoretical and inductive methods and validated through a numerical simulation with the finite element method.The new analysis model is suitable for static and modal analyses of rotor-bearing systems.Numerical examples are presented to reveal the effectiveness and applicability of the proposed approach.
