The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to r...The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to reveal DOF characteristics.The method draws on the superposition mechanism of the deformation characteristics of the sarcomere in the skeletal muscles of living organisms.Firstly,the multi-DOF deformation characteristics of the soft actuator are discretized into superimposed combinations of single-DOF micro-units.Then,the soft actuator was determined to contain deformation characteristics such as extension-contraction,bending,and twisting.Eighteen types of micro-units with basic deforma-tion characteristics were obtained depending on the axis and orientation.Further,the mapping relationship between the combination of micro-units and the motion characteristics of the soft actuator based on the GF set theory was established.Finally,an active-passive DOF co-structured soft actuator(APCSA)was developed.The graphical approach analyzes the experimental results,and it can be concluded that active and passive DOFs can coexist in the composite deformation of the soft actuator.展开更多
The study of capture mechanisms with high capture adaptability is the key to improving the efficiency of autonomous underwater vehicle(AUV)retrieval and release.This study aims to develop a capture mechanism for the l...The study of capture mechanisms with high capture adaptability is the key to improving the efficiency of autonomous underwater vehicle(AUV)retrieval and release.This study aims to develop a capture mechanism for the launch and recovery of AUV and elucidate its kinematic characteristics.Initially,based on the principles of deployment and retraction for AUV capture movements,a design scheme for a novel foldable and deployable capture mechanism is proposed.Subsequently,a detailed analysis of the Degrees of Freedom(DoFs)for enveloping and grasping movements is conducted according to screw theory.Additionally,the structural design of the actuation units for the capture mechanism is thoroughly discussed.Motion screw topology diagram is utilized to construct the kinematic model.On this basis,kinematic simulation verification of the capture mechanism is performed.The theoretical analysis revealed that the DoF for enveloping and grasping movements are 6 and 2,respectively.By appropriately configuring the actuation mechanism,enveloping and grasping movements can be achieved with a single actuation.The displacement and velocity curves of the capture mechanism were smooth,with no interference occurring.Vibration test results validate the reliability of the capture mechanism.The research work provides a valuable reference for the development of novel capture equipment for AUVs.展开更多
The Wenchuan earthquake has altered the crustal motion characteristics in the eastern margin of the Tibetan Plateau and adjacent regions.Using discontinuous GPS survey data for 2008–2012, the velocity field for the E...The Wenchuan earthquake has altered the crustal motion characteristics in the eastern margin of the Tibetan Plateau and adjacent regions.Using discontinuous GPS survey data for 2008–2012, the velocity field for the Eurasia reference framework has been obtained, and the general trend of contemporary crustal motion after the occurrence of the Wenchuan earthquake has been studied.In addition, using the velocity field, the block movement velocity has been estimated by least-squares fitting.Furthermore, the properties and displacement rates of main faults have been obtained from the differences in velocity vectors of the blocks on both sides of the faults.The results reveal that there are no obvious changes in the general characteristics of crustal motion in this area after the Wenchuan earthquake.The earthquake mainly changed the rate of the movement of the Chuan-Qing block and caused variation in the movement direction of the South China block.The effect of the earthquake on faults is mainly reflected in variations in fault displacement velocity; there is no fundamental change in the properties of fault activity.The displacement rates of the Xianshuihe fault decreased by 3–4 mm/a, the Longmenshan fault increased by 9–10 mm/a, and the northern segment of the Anninghe fault increased by approximately 9 mm/a.Furthermore, the displacement rates of the Minjiang, Xueshan, Huya, Longquanshan, and Xinjin faults increased by 2–3 mm/a.This implies that the effects of the Wenchuan earthquake on crustal movement can mainly be observed in the Chuan-Qing, South China, and N-Chuan-Dian blocks and their internal faults, as well as the Xianshuihe and Longmenshan faults and the northern section of the Anninghe fault.The reason for this is that the Wenchuan earthquake disturbed the kinematic and dynamic balance in the region.展开更多
Biomimetic micro-robot technology based on non-contact and cable-free magnetic actuation has become one of the crucial focuses of future biomedical research and micro-industrial development.Inspired by the motion char...Biomimetic micro-robot technology based on non-contact and cable-free magnetic actuation has become one of the crucial focuses of future biomedical research and micro-industrial development.Inspired by the motion characteristics of ray fish,this article proposes a micro-robot with magnetic controlled bionic ray structure.The micro-robot is made of soft elastic materials such as poly dimethyl siloxane(PDMS),Ethylene-Propylene-Diene Monomer(EPDM),and magnetic material Neodymium Iron Boron(NdFeB)nanoparticles.The external driving magnetic field is a periodic oscillating magnetic field generated by a Helmholtz coil.In order to verify the feasibility of the ray-inspired micro-robot,the motion principle was analyzed and several experiments were carried out.Experimental results demonstrated that the ray-inspired micro-robot can excellently mimic the crucial swimming characteristics of rays under the driving force of a oscillating magnetic field with an intensity of 5 mT and a frequency of 5 Hz,the swimming speed of the biomimetic micro-robot can reach nearly 2 body lengths per second.Analysis shows that the speed and stability of the micro-robot primarily depends not only on the amplitude and frequency of the vertical oscillating magnetic field,but also on the magnitude of the horizontal uniform magnetic field.This article demonstrates that the designed biomimetic micro-robot has the potential application of remotely performing specialized tasks in confined,complex environments such as microchannel-based scenarios.展开更多
The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economic...The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economically.On the basis of analyzing the basic structure and working principle of the air valve,this article mainly studies the motion characteristics of the suction valve plate.Based on fluid structure coupling mechanics and using ADINA software as a platform,numerical simulation analysis was conducted on the suction valve of a certain compressor model.Studying the stress of the valve plate and the variation of its upper and lower surface pressure with the opening and closing of the valve plate during the suction process of the compressor provides theoretical guidance for the rationality of the design of the air valve and related components,thereby improving the service life of the air valve and the working efficiency of the compressor.展开更多
The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen,and it is easy to accumulate in the front of the screen,which leads to the decrease of sc...The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen,and it is easy to accumulate in the front of the screen,which leads to the decrease of screening efficiency.Based on the reverse engineering technology,using the wavy geometry formed during the earthworm(Pheretima guillelmi)moving as a bionic prototype,a bionic screen was designed to make the maize mixture migrate backward rapidly in the front of the screen.The contour curve of earthworm’s head in an axial contracted state was extracted and fitted to obtain its equation.Based on the difference of concave position of the lower surface’s wavy geometry during the earthworm moving,the motion of the bionic screen was divided into four postures,and the conversion between different postures of the bionic screen was realized by the cam drive mechanism.The kinematics simulation of the bionic screen was carried out through ADAMS,and the displacement and velocity of the bionic screen were analyzed.When the feeding mass of the maize mixture was set at 5 kg/s,6 kg/s and 7 kg/s,the test results showed that the time of the maize mixture migrated(TOMMM)in the front of the bionic screen was shortened by 0.18 s,0.71 s,and 1.36 s,respectively,compared with that of planar reciprocating vibrating screen.The total screening time(TST)of the bionic screen was shortened by 1.28 s,1.33 s,and 1.53 s,respectively.The ability of the maize mixture to be migrated backward was improved.This study can provide a reference for the innovative design of the cleaning screen.展开更多
Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during highintensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched ...Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during highintensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched marine equipment in low-temperature ice-prone waters.A computational fluid dynamics-finite element method(CFD-FEM) coupled framework was established to simulate bidirectional fluid-structure interactions during the water-exit process of a ventilated vehicle impacting ice in brash environments.Distinct evolution characteristics were revealed by comparatively analyzing the cavity,flow fields,hydrodynamic loading,structural deformation,and trajectory stability across three scenarios:ice-free,single-ice,and multi-ice.Furthermore,the position-dependent impact effects were characterized.The findings reveal that the impact,friction,and compression effects of ice induce bending and wrinkling of the shoulder cavity,aggravating its collapse and increasing the wetting of the vehicle,resulting in a substantial expansion of the high-velocity and vortex-dominated regions within the flow field,accompanied by more obvious water splashes.The impact of ice notably increases the kinetic energy dissipation of the vehicle during the cross-water stage and diminishes its motion stability.In the center-symmetric layout,the vehicle collides with ice only once,with high stress confined to the head.Conversely,the radial-offset layout causes secondary or even multiple collisions,resulting in high-stress areas on the shoulder of the vehicle,making it deflect and ultimately causing the tail cavity to tilt and become destabilized.The design of new vehicles suitable for ice-prone environments should focus on enhancing the impact toughness of the head structure and optimizing the surface shape design to improve the adaptability to low-temperature complex environments.展开更多
Research has been conducted on dry coal selection technology to achieve efficient and clean utilization of coal and reduce water resource waste.To investigate the effective separation of 6-1 mm fine coal using this ap...Research has been conducted on dry coal selection technology to achieve efficient and clean utilization of coal and reduce water resource waste.To investigate the effective separation of 6-1 mm fine coal using this approach,the vibrating cascade sorter was examined,with particular attention given to its dynamic characteristics and motion behavior.Dry coal vibrating cascade sorter motion simulation experiments were carried out and the mechanical system motion characteristics of the vibrating cascade sorter were simulated and analyzed using multi-body dynamics software ADAMS,including the motion curve and spatial trajectory of the sorter body.Theoretical calculations of the sorter body’s motion characteristics,including displacement amplitude,velocity amplitude,and acceleration amplitude,were compared with simulation results derived from multi-body dynamics.The comparison revealed a strong agreement between the computational model and analytical predictions,with a maximum deviation of less than 3.75%.The dynamic behavior of the vibrating cascade sorter at various rotational speeds was evaluated and contrasted against predictive models,with the highest discrepancy between the observed and predicted outcomes being less than 7.6%.展开更多
Offshore observation platforms are required to have great ability to resist waves when they are operating at sea. Investigation on the motion characteristics of the platforms in the sea can provide significant referen...Offshore observation platforms are required to have great ability to resist waves when they are operating at sea. Investigation on the motion characteristics of the platforms in the sea can provide significant reference values during the platform design procedure. In this paper, a series of numerical simulation on the interaction of a triple-hulled offshore observation platform with different incident waves is carried out. All of the simulations are implemented utilizing our own solver naoe-FOAM-SJTU, which is based and developed on the open source tools of OpenFOAM. Duration curves of motion characteristics and loads acting on the platform are obtained, and a comparison between the results of the amplitude in different incident waves is presented. The results show that the solver is competent in the simulation of motion response of platforms in waves.展开更多
The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness.A new vibrating screen with variable elliptical trace was proposed.An...The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness.A new vibrating screen with variable elliptical trace was proposed.An accurate mechanical model was constructed according to the required structural motion features.Applying multi-degree-of-freedom vibration theory,characteristics of the vibrating screen was analyzed.Kinematics parameters of the vibrating screen which motion traces were linear,circular or elliptical were obtained.The stable solutions of the dynamic equations gave the motions of the vibrating screen by means of computer simulations.Technological parameters,including amplitude,movement velocity and throwing index,of five specific points along the screen surface were gained by theoretical calculation.The results show that the traces of the new designed vibrating screen follow the ideal screening motion.The screening efficiency and processing capacity may thus be effectively improved.展开更多
Internal solitary waves(ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation ...Internal solitary waves(ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation model for the interaction of solitary waves with submersibles at a large scale has been developed. The Miyata-ChoiCamassa(MCC) equation serves as the basis for generating ISWs. The impacts of the submergence depth, wave amplitude, and advancing velocity on the motion response and load characteristics of the submersible are examined in detail. This study elucidates the governing laws and mechanisms underlying the impact of ISWs on submersibles.The research findings indicate that shorter distances to the undisturbed surface, higher wave amplitudes, and fasteradvancing speeds result in greater effects on submersibles. For a submersible operating in the lower layer, both the alteration in density near the wave interface and the dynamic pressure induced by ISWs can reduce its lift, potentially resulting in a rapid descent. It is imperative to pay considerable attention to the impact of ISWs, as they have the potential to precipitate a loss of control of the submersible.展开更多
A supercavitating vehicle is a complex high-speed underwater body that is exposed to extreme operating conditions due to its speed.To successfully control the depth and attitude,it is necessary to study the motion cha...A supercavitating vehicle is a complex high-speed underwater body that is exposed to extreme operating conditions due to its speed.To successfully control the depth and attitude,it is necessary to study the motion characteristics of the vehicles on a vertical plane.This study investigates the motion model on the vertical plane and analyzes the dynamic characteristics of supercavitating vehicles.Then,a fixed-depth control method is developed.For validating the designed control-algorithm,related simulation and experiments have been carried out for the control system.Analytical results show that the proposed control system accomplishes precise depth control of the supercavitating vehicles,providing a necessary theoretical basis for further study of the dynamic control problem for underwater supercavitating vehicles.展开更多
Rockfall poses a great threat to buildings and personal security. To understand the dynamic characteristics of rockfalls is a prerequisite for disaster prevention and assessment. Models for rockfalls in different form...Rockfall poses a great threat to buildings and personal security. To understand the dynamic characteristics of rockfalls is a prerequisite for disaster prevention and assessment. Models for rockfalls in different forms are established based on the theory of rigid body motion. The equivalent velocity considering the rotational effect is determined by the energy ratio. Besides, considering plastic deformation and nonlinear hardening, the maximum impact force is estimated based on the Hertz contact theory. Then, a case study is carried out to illustrate the applicability of the model and sensitive analyses on some affecting parameters are also made. Calculation results show that the maximum impact force increases with the increasing of incident velocity, angle and slope gradient reflected by the changing of energy ratio. Moreover, the model for the estimation of maximum impact force is validated by two different scales of experiments and compared with other theoretical models. Simulated maximum impact forces agree well with the experiments.展开更多
A launch and recovery system for a seafloor drill was studied using a dynamic model that considered the influences of seawater resistance and the elastic deformation of the cable based on the lumped mass method.The in...A launch and recovery system for a seafloor drill was studied using a dynamic model that considered the influences of seawater resistance and the elastic deformation of the cable based on the lumped mass method.The influence of wave direction angle on heave,roll,and pitch motions of the ship was analyzed,and those motion characteristics were then used to assess the tension response of the armored umbilical cable at the lifting point under different wave direction angles.By analyzing the different wave direction angles we found that,when a ship experiences longitudinal waves it will express longitudinal movement.When a ship encounters transverse waves,it will have transverse movement.Under oblique waves from bow or stern,a ship will have both longitudinal and transverse movement,exhibiting obvious heave and pitch movements.Oblique waves,in this study,produced the most obvious impact on armored umbilical cable tension.However,the tension of the armored umbilical cable will change based on the weight of the armored umbilical cable and the seafloor drill in the water.This analysis has provided a useful reference for the study of heave compensation and the constant tension automatic control.展开更多
The grinding sphere is the main ultra-fine grinding medium for the vertical spiral stirred mill, and its motion characteristics have a significant impact on grinding efficiency. A DEM-CFD model of an experimental mill...The grinding sphere is the main ultra-fine grinding medium for the vertical spiral stirred mill, and its motion characteristics have a significant impact on grinding efficiency. A DEM-CFD model of an experimental mill was established, and the accuracy was verified through experiment. The motion characteristics of grinding spheres were systematically analyzed from four aspects: motion trajectory, velocity, force and energy. The results showed that the motion trajectories of the grinding spheres at the cylinder bottom are the shortest, which can be defined as the inert spheres. The trajectory length increases continuously as the height increases in the cylinder, while it increases first and then decreases with the increase of the radial distance. The velocity of grinding spheres near the agitator blade is the highest, while it is lowest at the cylinder wall. By comparing the total, radial, tangential and axial velocities, it was found that its motion mode is mainly tangential motion around the axis, and the axial and radial velocities are very small. The kinetic energy distribution of the grinding spheres is basically the same as the total velocity. The normal collision force of the grinding sphere is 6 times of the tangential collision force, but the tangential collision energy is about 1.4 times of the normal collision energy. Last, five grinding zones were established to characterize the contribution of grinding spheres inside the cylinder to the grinding efficiency. These results will help to understand the grinding mechanism and provide theoretical guidance for the structural design.展开更多
A novel compliant mechanism with RPR degrees of freedom(DOF)is proposed where R and P represent rotation and translation DOFs,respectively.The proposed compliant mechanism is obtained from dimension synthesizing a 2-R...A novel compliant mechanism with RPR degrees of freedom(DOF)is proposed where R and P represent rotation and translation DOFs,respectively.The proposed compliant mechanism is obtained from dimension synthesizing a 2-RPU-UPR rigid parallel mechanism with the method of optimization of motion/force transfer characteristic.R,P and U represent rotation,translation and universal pairs,respectively.Firstly,inverse kinematics and Jacobian matrix are analyzed for the dimensional synthesis.Then,output transmission indexes of branches in the parallel mechanism are given.Dimensional synthesis is completed based on the normalized design parameter.And optimization of flexure joints based on constrained energy is carried out.Afterwards,the novel compliant mechanism is obtained by direct replacing method.Mechanical model of the compliant mechanism including static stiffness and input stiffness is built based on the pseudo-rigid body modeling method and virtual work principle.Finally,FEA simulation by Ansys Workbench is carried out to verify DOF,effectiveness of the dimension synthesis,and compliant model.Optimization of motion/force transfer characteristic is first applied for the design of compliant mechanisms to suppress drift of rotation axis in the paper.展开更多
In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspe...In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.展开更多
This paper is an extension of the author's paper (Xie,1982) to the spherical earth.It is found that the simi- lar results are obtained under the assumption of isotropic distribution of horizontal kinetic energy al...This paper is an extension of the author's paper (Xie,1982) to the spherical earth.It is found that the simi- lar results are obtained under the assumption of isotropic distribution of horizontal kinetic energy along the zonal and meridional directions.It points out the limitation of the results already obtained and paves the path for the approach of anisotropie semi-eddy or quasi-eddy motion of the atmosphere.展开更多
Abstract：With the application background of 16 inch industrial fan blades＇ scribing process, a simple and prac tical 2DOF parallel plane scribing device is proposed to replace the traditional manual scribing. The di...Abstract：With the application background of 16 inch industrial fan blades＇ scribing process, a simple and prac tical 2DOF parallel plane scribing device is proposed to replace the traditional manual scribing. The direct and inverse kinematics solutions, workspace and singular configuration of the mechanism are analyzed and solved. Some contour curve equations are fitted based on the data points which are measured by a three coordinate meas uring machine. According to the blade＇s contour curve, each input link＇s motion characteristic is obtained by u sing MATLAB, which provides a new way to realize blades＇ automatic scribing process technology.展开更多
基金The Central Government Guides Local Foundation for Science and Technology Development(Grant No.YDZJSX2024B004).
文摘The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to reveal DOF characteristics.The method draws on the superposition mechanism of the deformation characteristics of the sarcomere in the skeletal muscles of living organisms.Firstly,the multi-DOF deformation characteristics of the soft actuator are discretized into superimposed combinations of single-DOF micro-units.Then,the soft actuator was determined to contain deformation characteristics such as extension-contraction,bending,and twisting.Eighteen types of micro-units with basic deforma-tion characteristics were obtained depending on the axis and orientation.Further,the mapping relationship between the combination of micro-units and the motion characteristics of the soft actuator based on the GF set theory was established.Finally,an active-passive DOF co-structured soft actuator(APCSA)was developed.The graphical approach analyzes the experimental results,and it can be concluded that active and passive DOFs can coexist in the composite deformation of the soft actuator.
基金Supported by Jiangsu Provincial Natural Science Foundation(Grant No.BK20220649)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.23KJB460010)+2 种基金Provincial Key Laboratory of High-end Deepsea Machinery Equipment(Grant Nos.SYH2024003 and SYH2025001)the Jiangsu Provincial Key R&D Project(Grant No.BE2022062)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.SJCX25_2526).
文摘The study of capture mechanisms with high capture adaptability is the key to improving the efficiency of autonomous underwater vehicle(AUV)retrieval and release.This study aims to develop a capture mechanism for the launch and recovery of AUV and elucidate its kinematic characteristics.Initially,based on the principles of deployment and retraction for AUV capture movements,a design scheme for a novel foldable and deployable capture mechanism is proposed.Subsequently,a detailed analysis of the Degrees of Freedom(DoFs)for enveloping and grasping movements is conducted according to screw theory.Additionally,the structural design of the actuation units for the capture mechanism is thoroughly discussed.Motion screw topology diagram is utilized to construct the kinematic model.On this basis,kinematic simulation verification of the capture mechanism is performed.The theoretical analysis revealed that the DoF for enveloping and grasping movements are 6 and 2,respectively.By appropriately configuring the actuation mechanism,enveloping and grasping movements can be achieved with a single actuation.The displacement and velocity curves of the capture mechanism were smooth,with no interference occurring.Vibration test results validate the reliability of the capture mechanism.The research work provides a valuable reference for the development of novel capture equipment for AUVs.
基金supported by a geological survey project of the China Geological Survey (No.1212011140013, No.12120113009800)
文摘The Wenchuan earthquake has altered the crustal motion characteristics in the eastern margin of the Tibetan Plateau and adjacent regions.Using discontinuous GPS survey data for 2008–2012, the velocity field for the Eurasia reference framework has been obtained, and the general trend of contemporary crustal motion after the occurrence of the Wenchuan earthquake has been studied.In addition, using the velocity field, the block movement velocity has been estimated by least-squares fitting.Furthermore, the properties and displacement rates of main faults have been obtained from the differences in velocity vectors of the blocks on both sides of the faults.The results reveal that there are no obvious changes in the general characteristics of crustal motion in this area after the Wenchuan earthquake.The earthquake mainly changed the rate of the movement of the Chuan-Qing block and caused variation in the movement direction of the South China block.The effect of the earthquake on faults is mainly reflected in variations in fault displacement velocity; there is no fundamental change in the properties of fault activity.The displacement rates of the Xianshuihe fault decreased by 3–4 mm/a, the Longmenshan fault increased by 9–10 mm/a, and the northern segment of the Anninghe fault increased by approximately 9 mm/a.Furthermore, the displacement rates of the Minjiang, Xueshan, Huya, Longquanshan, and Xinjin faults increased by 2–3 mm/a.This implies that the effects of the Wenchuan earthquake on crustal movement can mainly be observed in the Chuan-Qing, South China, and N-Chuan-Dian blocks and their internal faults, as well as the Xianshuihe and Longmenshan faults and the northern section of the Anninghe fault.The reason for this is that the Wenchuan earthquake disturbed the kinematic and dynamic balance in the region.
基金supported by the National Natural Science Foundation of China(No.52005116)the Guangzhou Science and Technology Plan Project(No.SL2024A03J00589)+2 种基金the Guangdong Province Ordinary University Characteristic Innovation Project(No.2023KTSCX100)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515111176 and No.2023A1515011791)the Guangzhou University Graduate Innovation Research Project,(No.2022GDJC-M20)。
文摘Biomimetic micro-robot technology based on non-contact and cable-free magnetic actuation has become one of the crucial focuses of future biomedical research and micro-industrial development.Inspired by the motion characteristics of ray fish,this article proposes a micro-robot with magnetic controlled bionic ray structure.The micro-robot is made of soft elastic materials such as poly dimethyl siloxane(PDMS),Ethylene-Propylene-Diene Monomer(EPDM),and magnetic material Neodymium Iron Boron(NdFeB)nanoparticles.The external driving magnetic field is a periodic oscillating magnetic field generated by a Helmholtz coil.In order to verify the feasibility of the ray-inspired micro-robot,the motion principle was analyzed and several experiments were carried out.Experimental results demonstrated that the ray-inspired micro-robot can excellently mimic the crucial swimming characteristics of rays under the driving force of a oscillating magnetic field with an intensity of 5 mT and a frequency of 5 Hz,the swimming speed of the biomimetic micro-robot can reach nearly 2 body lengths per second.Analysis shows that the speed and stability of the micro-robot primarily depends not only on the amplitude and frequency of the vertical oscillating magnetic field,but also on the magnitude of the horizontal uniform magnetic field.This article demonstrates that the designed biomimetic micro-robot has the potential application of remotely performing specialized tasks in confined,complex environments such as microchannel-based scenarios.
文摘The air valve is the core component of the cyclic operation of the compressor cylinder,and its structure and performance largely determine whether the reciprocating compressor can operate more efficiently and economically.On the basis of analyzing the basic structure and working principle of the air valve,this article mainly studies the motion characteristics of the suction valve plate.Based on fluid structure coupling mechanics and using ADINA software as a platform,numerical simulation analysis was conducted on the suction valve of a certain compressor model.Studying the stress of the valve plate and the variation of its upper and lower surface pressure with the opening and closing of the valve plate during the suction process of the compressor provides theoretical guidance for the rationality of the design of the air valve and related components,thereby improving the service life of the air valve and the working efficiency of the compressor.
基金This work was supported by the National Natural Science Foundation of China(Grant No.52075091,51475090)the Heilongjiang Provincial Natural Science Foundation of China(Grant No.E2017004).
文摘The maize mixture feeding with a large mass cannot be migrated backward rapidly along the planar reciprocating vibrating screen,and it is easy to accumulate in the front of the screen,which leads to the decrease of screening efficiency.Based on the reverse engineering technology,using the wavy geometry formed during the earthworm(Pheretima guillelmi)moving as a bionic prototype,a bionic screen was designed to make the maize mixture migrate backward rapidly in the front of the screen.The contour curve of earthworm’s head in an axial contracted state was extracted and fitted to obtain its equation.Based on the difference of concave position of the lower surface’s wavy geometry during the earthworm moving,the motion of the bionic screen was divided into four postures,and the conversion between different postures of the bionic screen was realized by the cam drive mechanism.The kinematics simulation of the bionic screen was carried out through ADAMS,and the displacement and velocity of the bionic screen were analyzed.When the feeding mass of the maize mixture was set at 5 kg/s,6 kg/s and 7 kg/s,the test results showed that the time of the maize mixture migrated(TOMMM)in the front of the bionic screen was shortened by 0.18 s,0.71 s,and 1.36 s,respectively,compared with that of planar reciprocating vibrating screen.The total screening time(TST)of the bionic screen was shortened by 1.28 s,1.33 s,and 1.53 s,respectively.The ability of the maize mixture to be migrated backward was improved.This study can provide a reference for the innovative design of the cleaning screen.
文摘Understanding the evolution mechanisms of water-exit cavities and flow fields evolve during highintensity interactions between vehicles and floating ice is critical for advancing the application of submarine-launched marine equipment in low-temperature ice-prone waters.A computational fluid dynamics-finite element method(CFD-FEM) coupled framework was established to simulate bidirectional fluid-structure interactions during the water-exit process of a ventilated vehicle impacting ice in brash environments.Distinct evolution characteristics were revealed by comparatively analyzing the cavity,flow fields,hydrodynamic loading,structural deformation,and trajectory stability across three scenarios:ice-free,single-ice,and multi-ice.Furthermore,the position-dependent impact effects were characterized.The findings reveal that the impact,friction,and compression effects of ice induce bending and wrinkling of the shoulder cavity,aggravating its collapse and increasing the wetting of the vehicle,resulting in a substantial expansion of the high-velocity and vortex-dominated regions within the flow field,accompanied by more obvious water splashes.The impact of ice notably increases the kinetic energy dissipation of the vehicle during the cross-water stage and diminishes its motion stability.In the center-symmetric layout,the vehicle collides with ice only once,with high stress confined to the head.Conversely,the radial-offset layout causes secondary or even multiple collisions,resulting in high-stress areas on the shoulder of the vehicle,making it deflect and ultimately causing the tail cavity to tilt and become destabilized.The design of new vehicles suitable for ice-prone environments should focus on enhancing the impact toughness of the head structure and optimizing the surface shape design to improve the adaptability to low-temperature complex environments.
文摘Research has been conducted on dry coal selection technology to achieve efficient and clean utilization of coal and reduce water resource waste.To investigate the effective separation of 6-1 mm fine coal using this approach,the vibrating cascade sorter was examined,with particular attention given to its dynamic characteristics and motion behavior.Dry coal vibrating cascade sorter motion simulation experiments were carried out and the mechanical system motion characteristics of the vibrating cascade sorter were simulated and analyzed using multi-body dynamics software ADAMS,including the motion curve and spatial trajectory of the sorter body.Theoretical calculations of the sorter body’s motion characteristics,including displacement amplitude,velocity amplitude,and acceleration amplitude,were compared with simulation results derived from multi-body dynamics.The comparison revealed a strong agreement between the computational model and analytical predictions,with a maximum deviation of less than 3.75%.The dynamic behavior of the vibrating cascade sorter at various rotational speeds was evaluated and contrasted against predictive models,with the highest discrepancy between the observed and predicted outcomes being less than 7.6%.
基金Supported by the National Natural Science Foundation of China （Grant No. 50739004 and 11072154） Foundation of State Key Laboratory of Ocean Engineering of China （GKZD010059）+1 种基金 the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning （2008007） The Lloyd＇s Register Educational Trust （The LRET）
文摘Offshore observation platforms are required to have great ability to resist waves when they are operating at sea. Investigation on the motion characteristics of the platforms in the sea can provide significant reference values during the platform design procedure. In this paper, a series of numerical simulation on the interaction of a triple-hulled offshore observation platform with different incident waves is carried out. All of the simulations are implemented utilizing our own solver naoe-FOAM-SJTU, which is based and developed on the open source tools of OpenFOAM. Duration curves of motion characteristics and loads acting on the platform are obtained, and a comparison between the results of the amplitude in different incident waves is presented. The results show that the solver is competent in the simulation of motion response of platforms in waves.
基金Projects 50574091 and 50774084 supported by the National Natural Science Foundation of China
文摘The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness.A new vibrating screen with variable elliptical trace was proposed.An accurate mechanical model was constructed according to the required structural motion features.Applying multi-degree-of-freedom vibration theory,characteristics of the vibrating screen was analyzed.Kinematics parameters of the vibrating screen which motion traces were linear,circular or elliptical were obtained.The stable solutions of the dynamic equations gave the motions of the vibrating screen by means of computer simulations.Technological parameters,including amplitude,movement velocity and throwing index,of five specific points along the screen surface were gained by theoretical calculation.The results show that the traces of the new designed vibrating screen follow the ideal screening motion.The screening efficiency and processing capacity may thus be effectively improved.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52201380)Fundamental Research Funds for the Central Universities (Grant No. D5000230080)+2 种基金Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (Grant Nos. CX 2024049 and CX2023006)the Chunhui Program of Ministry of Education of China (Grant No. HZKY20220538)the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University (Grant No. PF2023057)。
文摘Internal solitary waves(ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation model for the interaction of solitary waves with submersibles at a large scale has been developed. The Miyata-ChoiCamassa(MCC) equation serves as the basis for generating ISWs. The impacts of the submergence depth, wave amplitude, and advancing velocity on the motion response and load characteristics of the submersible are examined in detail. This study elucidates the governing laws and mechanisms underlying the impact of ISWs on submersibles.The research findings indicate that shorter distances to the undisturbed surface, higher wave amplitudes, and fasteradvancing speeds result in greater effects on submersibles. For a submersible operating in the lower layer, both the alteration in density near the wave interface and the dynamic pressure induced by ISWs can reduce its lift, potentially resulting in a rapid descent. It is imperative to pay considerable attention to the impact of ISWs, as they have the potential to precipitate a loss of control of the submersible.
文摘A supercavitating vehicle is a complex high-speed underwater body that is exposed to extreme operating conditions due to its speed.To successfully control the depth and attitude,it is necessary to study the motion characteristics of the vehicles on a vertical plane.This study investigates the motion model on the vertical plane and analyzes the dynamic characteristics of supercavitating vehicles.Then,a fixed-depth control method is developed.For validating the designed control-algorithm,related simulation and experiments have been carried out for the control system.Analytical results show that the proposed control system accomplishes precise depth control of the supercavitating vehicles,providing a necessary theoretical basis for further study of the dynamic control problem for underwater supercavitating vehicles.
基金supported by the National Natural Science Foundation of China (41472272)the Youth Science and Technology Fund of Sichuan Province (2016JQ0011)
文摘Rockfall poses a great threat to buildings and personal security. To understand the dynamic characteristics of rockfalls is a prerequisite for disaster prevention and assessment. Models for rockfalls in different forms are established based on the theory of rigid body motion. The equivalent velocity considering the rotational effect is determined by the energy ratio. Besides, considering plastic deformation and nonlinear hardening, the maximum impact force is estimated based on the Hertz contact theory. Then, a case study is carried out to illustrate the applicability of the model and sensitive analyses on some affecting parameters are also made. Calculation results show that the maximum impact force increases with the increasing of incident velocity, angle and slope gradient reflected by the changing of energy ratio. Moreover, the model for the estimation of maximum impact force is validated by two different scales of experiments and compared with other theoretical models. Simulated maximum impact forces agree well with the experiments.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51705145 and 51779092)the special funding support for the construction of innovative provinces in Hunan Province (Grant Nos. 2020GK1021, 2019SK2271, and 2019GK1012)
文摘A launch and recovery system for a seafloor drill was studied using a dynamic model that considered the influences of seawater resistance and the elastic deformation of the cable based on the lumped mass method.The influence of wave direction angle on heave,roll,and pitch motions of the ship was analyzed,and those motion characteristics were then used to assess the tension response of the armored umbilical cable at the lifting point under different wave direction angles.By analyzing the different wave direction angles we found that,when a ship experiences longitudinal waves it will express longitudinal movement.When a ship encounters transverse waves,it will have transverse movement.Under oblique waves from bow or stern,a ship will have both longitudinal and transverse movement,exhibiting obvious heave and pitch movements.Oblique waves,in this study,produced the most obvious impact on armored umbilical cable tension.However,the tension of the armored umbilical cable will change based on the weight of the armored umbilical cable and the seafloor drill in the water.This analysis has provided a useful reference for the study of heave compensation and the constant tension automatic control.
基金supported by Technological Innovation Talent Team Special Plan of Shanxi Province(grant No.202204051002002)Outstanding Doctoral Award Fund in Shanxi Province(grant No.20222126).
文摘The grinding sphere is the main ultra-fine grinding medium for the vertical spiral stirred mill, and its motion characteristics have a significant impact on grinding efficiency. A DEM-CFD model of an experimental mill was established, and the accuracy was verified through experiment. The motion characteristics of grinding spheres were systematically analyzed from four aspects: motion trajectory, velocity, force and energy. The results showed that the motion trajectories of the grinding spheres at the cylinder bottom are the shortest, which can be defined as the inert spheres. The trajectory length increases continuously as the height increases in the cylinder, while it increases first and then decreases with the increase of the radial distance. The velocity of grinding spheres near the agitator blade is the highest, while it is lowest at the cylinder wall. By comparing the total, radial, tangential and axial velocities, it was found that its motion mode is mainly tangential motion around the axis, and the axial and radial velocities are very small. The kinetic energy distribution of the grinding spheres is basically the same as the total velocity. The normal collision force of the grinding sphere is 6 times of the tangential collision force, but the tangential collision energy is about 1.4 times of the normal collision energy. Last, five grinding zones were established to characterize the contribution of grinding spheres inside the cylinder to the grinding efficiency. These results will help to understand the grinding mechanism and provide theoretical guidance for the structural design.
基金National Natural Science Foundation of China(Grant No.51975007).
文摘A novel compliant mechanism with RPR degrees of freedom(DOF)is proposed where R and P represent rotation and translation DOFs,respectively.The proposed compliant mechanism is obtained from dimension synthesizing a 2-RPU-UPR rigid parallel mechanism with the method of optimization of motion/force transfer characteristic.R,P and U represent rotation,translation and universal pairs,respectively.Firstly,inverse kinematics and Jacobian matrix are analyzed for the dimensional synthesis.Then,output transmission indexes of branches in the parallel mechanism are given.Dimensional synthesis is completed based on the normalized design parameter.And optimization of flexure joints based on constrained energy is carried out.Afterwards,the novel compliant mechanism is obtained by direct replacing method.Mechanical model of the compliant mechanism including static stiffness and input stiffness is built based on the pseudo-rigid body modeling method and virtual work principle.Finally,FEA simulation by Ansys Workbench is carried out to verify DOF,effectiveness of the dimension synthesis,and compliant model.Optimization of motion/force transfer characteristic is first applied for the design of compliant mechanisms to suppress drift of rotation axis in the paper.
基金National Natural Science Foundation of China (50538050, 50608024)
文摘In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.
文摘This paper is an extension of the author's paper (Xie,1982) to the spherical earth.It is found that the simi- lar results are obtained under the assumption of isotropic distribution of horizontal kinetic energy along the zonal and meridional directions.It points out the limitation of the results already obtained and paves the path for the approach of anisotropie semi-eddy or quasi-eddy motion of the atmosphere.
文摘Abstract：With the application background of 16 inch industrial fan blades＇ scribing process, a simple and prac tical 2DOF parallel plane scribing device is proposed to replace the traditional manual scribing. The direct and inverse kinematics solutions, workspace and singular configuration of the mechanism are analyzed and solved. Some contour curve equations are fitted based on the data points which are measured by a three coordinate meas uring machine. According to the blade＇s contour curve, each input link＇s motion characteristic is obtained by u sing MATLAB, which provides a new way to realize blades＇ automatic scribing process technology.
