The production of Lycium barbarum L.is a labor-intensive industry.Multiple manual harvests are required during the harvesting season,which contributes to the high harvesting costs.The cultivation conditions of L.barba...The production of Lycium barbarum L.is a labor-intensive industry.Multiple manual harvests are required during the harvesting season,which contributes to the high harvesting costs.The cultivation conditions of L.barbarum were investigated to increase efficiency and mitigate harvesting damage.A torsion harvester was designed according to the characteristic of infinite inflorescence and the distribution of detachment force,and the kinematics model of the harvester was established.The vibration responses of ripe and unripe fruit were obtained through ADAMS simulation of the branch model,and the influencing factors and value range of the torsion harvester were also determined.The mathematical models of ripe fruit harvesting rate,unripe fruit harvesting rate,ripe fruit damage rate and torsion angle,vibration rods distance,and vibration frequency were established by the Box-Behnken test.The influences of various factors on ripe fruit harvesting rate,unripe fruit harvesting rate,and ripe fruit damage rate were analyzed,and the best parameter combination was obtained:torsion angle 73.66°,vibration rods distance 35.51 mm and vibration frequency 19.12 Hz.Field experiment showed that the harvesting rate of ripe fruit is 95.67%,the harvesting rate of unripe fruit is 4.68%,and the damage rate of ripe fruit is 3.70%.The research results can promote the mechanization process of L.barbarum harvest,and provide a reference for vibration harvest of berries.展开更多
Using five-story shear models, the inelastic torsional coupled response of eccentric buildings to different earthquake intensity was studied. Results show that the torsional couple degree is closely related to the str...Using five-story shear models, the inelastic torsional coupled response of eccentric buildings to different earthquake intensity was studied. Results show that the torsional couple degree is closely related to the strength distribution of the resisting elements. Generally, the building designed by spectral modal analysis method has a tendency to move translationally as the earthquake intensity increases. The building designed by proportion rigidity method, will rotate heavily to moderate earthquake, but when it is intensively excited into the inelastic phase, the coupling would decrease slightly, but could not be neglected.展开更多
Various theories and analytical formulations were implemented and exploited in the 1980s and 1990s for the design of bridge beams or decks curved in the horizontal plane and subjected to out-of-plane loads. Nowadays, ...Various theories and analytical formulations were implemented and exploited in the 1980s and 1990s for the design of bridge beams or decks curved in the horizontal plane and subjected to out-of-plane loads. Nowadays, the Finite Element Method (FEM) is a valid tool for the analysis of structures with complex geometries and, therefore, the development of sophisticated analytical formulations is not needed anymore. However, they are still useful for the validation of FE models. This paper presents the case study of an existing viaduct built in North Italy, aiming to compare analytical approaches and numerical modelling. The bridge is characterized by an axis curved in two directions and a rectilinear segment. The global analysis of the viaduct is carried out with special attention to the attributes that cause torque action and bending moment. The theoretical developments focus on a deeper understanding of the torsional response under different constraint and loading conditions and aspire to raise awareness of the mutual interaction of flexural and torsional behaviour, that are always present in these complex curved systems. The examination of the case study is also obtained by comparing the response of isostatic and hyperstatic curvilinear steel box-girders.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.32272001)Key Research and Development Program of Ningxia Hui Autonomous Region(Grant No.2022BBF01002).
文摘The production of Lycium barbarum L.is a labor-intensive industry.Multiple manual harvests are required during the harvesting season,which contributes to the high harvesting costs.The cultivation conditions of L.barbarum were investigated to increase efficiency and mitigate harvesting damage.A torsion harvester was designed according to the characteristic of infinite inflorescence and the distribution of detachment force,and the kinematics model of the harvester was established.The vibration responses of ripe and unripe fruit were obtained through ADAMS simulation of the branch model,and the influencing factors and value range of the torsion harvester were also determined.The mathematical models of ripe fruit harvesting rate,unripe fruit harvesting rate,ripe fruit damage rate and torsion angle,vibration rods distance,and vibration frequency were established by the Box-Behnken test.The influences of various factors on ripe fruit harvesting rate,unripe fruit harvesting rate,and ripe fruit damage rate were analyzed,and the best parameter combination was obtained:torsion angle 73.66°,vibration rods distance 35.51 mm and vibration frequency 19.12 Hz.Field experiment showed that the harvesting rate of ripe fruit is 95.67%,the harvesting rate of unripe fruit is 4.68%,and the damage rate of ripe fruit is 3.70%.The research results can promote the mechanization process of L.barbarum harvest,and provide a reference for vibration harvest of berries.
文摘Using five-story shear models, the inelastic torsional coupled response of eccentric buildings to different earthquake intensity was studied. Results show that the torsional couple degree is closely related to the strength distribution of the resisting elements. Generally, the building designed by spectral modal analysis method has a tendency to move translationally as the earthquake intensity increases. The building designed by proportion rigidity method, will rotate heavily to moderate earthquake, but when it is intensively excited into the inelastic phase, the coupling would decrease slightly, but could not be neglected.
文摘Various theories and analytical formulations were implemented and exploited in the 1980s and 1990s for the design of bridge beams or decks curved in the horizontal plane and subjected to out-of-plane loads. Nowadays, the Finite Element Method (FEM) is a valid tool for the analysis of structures with complex geometries and, therefore, the development of sophisticated analytical formulations is not needed anymore. However, they are still useful for the validation of FE models. This paper presents the case study of an existing viaduct built in North Italy, aiming to compare analytical approaches and numerical modelling. The bridge is characterized by an axis curved in two directions and a rectilinear segment. The global analysis of the viaduct is carried out with special attention to the attributes that cause torque action and bending moment. The theoretical developments focus on a deeper understanding of the torsional response under different constraint and loading conditions and aspire to raise awareness of the mutual interaction of flexural and torsional behaviour, that are always present in these complex curved systems. The examination of the case study is also obtained by comparing the response of isostatic and hyperstatic curvilinear steel box-girders.
