Many fishes use undulatory fin to propel themselves in the underwater environment. These locomotor mechanisms have a popular interest to many researchers. In the present study, we perform a three-dimensional unsteady ...Many fishes use undulatory fin to propel themselves in the underwater environment. These locomotor mechanisms have a popular interest to many researchers. In the present study, we perform a three-dimensional unsteady computation of an undulatory mechanical fin that is driven by Shape Memory Alloy （SMA）. The objective of the computation is to investigate the fluid dynamics of force production associated with the undulatory mechanical fin. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing is used to compute the unsteady flow around the fin through five complete cycles. The pressure distribution on fin surface is computed and integrated to provide fin forces which are decomposed into lift and thrust. The velocity field is also computed throughout the swimming cycle. Finally, a comparison is conducted to reveal the dynamics of force generation according to the kinematic parameters of the undulatory fin （amplitude, frequency and wavelength）.展开更多
Paraconsistent logic (PL) is a non-classical logic that accepts contradiction in its foundations. It can be represented in the form of paraconsistent annotated logic with annotation of two values (PAL2v). When used to...Paraconsistent logic (PL) is a non-classical logic that accepts contradiction in its foundations. It can be represented in the form of paraconsistent annotated logic with annotation of two values (PAL2v). When used to model quantum phenomena, PAL2v is called paraquantum logic (PQL). In this work, the concept of PQL is applied to create a logical model presenting the fundamental principles of quantum mechanics that support particle-wave theory. This study uses the well-known Young’s double-slit experiment, wherein quantum phenomena appear when a monochromatic light beam passes through the two slits. We focused on a reference point located between the slits, where we observed the effects of two types of wave interferences in a region defined as a two-wave region (2W region). Considering that the effect in this 2W region is very similar to that studied by Huygens, we adopt a paraquantum logical model in which a particle (or quantum) is represented by two wave functions. The two wave functions result in four State Vectors (Ket, Bra,,) in the PQL Lattice that express the symmetry and the entanglement of Quantum Mechanics. The constructed model adapts well to the quantum phenomena, is strongly consistent, and can be considered as an innovative form of analysis in the field of quantum mechanics. Based on this model, we present in two parts (Part I and Part II) the comparative analysis of values found in SchrÖdinger’s equation and probabilistic models of wave-particle theory using Bonferroni inequality.展开更多
Stingrays can undulate their wide pectoral fins to thrust themselves and swim freely underwater.Many researchers have used bionics to directly imitate their undulating mechanism and manufacture undulatory underwater r...Stingrays can undulate their wide pectoral fins to thrust themselves and swim freely underwater.Many researchers have used bionics to directly imitate their undulating mechanism and manufacture undulatory underwater robots.Based on the limitations of the existing undulatory underwater robots,this paper proposes a novel undulatory propulsion strategy,which aims to use the stingray undulating mechanism more thoroughly.First,the mathematical models of both traditional and novel structures are established to accurately describe their undulating mechanism.Then,based on the dynamic mesh technology,the flow field vortex structure they generated is analyzed through fluid-structure interaction simulation,and the thrust force and lateral force generated by them are calculated,which verified that this novel propulsion strategy is indeed more effective.Finally,a prototype robot based on the improved propulsion strategy is manufactured.Compared with the existing stingray robots,the prototype has obvious advantages,thus verifying the accuracy of the simulation results.展开更多
The propulsion mechanisms of biomimetic underwater vehicles using bionic undulatory fins have been extensively studied for their potential to enhance efficiency and maneuverability in underwater environments.However,t...The propulsion mechanisms of biomimetic underwater vehicles using bionic undulatory fins have been extensively studied for their potential to enhance efficiency and maneuverability in underwater environments.However,the hydrodynamic interactions between the vehicle body,robotic manipulator,and fluctuating motion remain less explored,particularly in turbulent conditions.In this work,a Biomimetic Underwater Vehicle-Manipulator System(BUVMS)propelled using bionic undulatory fins is considered.The propulsion mechanism and hydrodynamic performance of fluctuating motion are analyzed by numerical simulation.The drag coefficients of the BUVMS at different Reynolds numbers are calculated,and the investigation of vortex generation during the motion of the BUVMS reveals that vortex binding and shedding are the key factors for propulsion generation.Various moving modes of the BUVMS are developed in conjunction with the pro-pulsion mechanism.The hydrodynamic loads during the motion of the underwater robotic arm in a turbulent environment are analyzed.A simple motion strategy is proposed to reduce the effect of water drag on the manipulation of the robotic arm and on the overall stability of the BUVMS.The results of the hydrodynamic analysis offer systematic guidance for controlling underwater operations of the BUVMS.展开更多
Flow over a fish-like airfoil is numerically investigated to elaborate the hydrodynamics of the undulatory braking locomotion for an elongated eel-like body or long-based fin. For undulation with low frequency, we fin...Flow over a fish-like airfoil is numerically investigated to elaborate the hydrodynamics of the undulatory braking locomotion for an elongated eel-like body or long-based fin. For undulation with low frequency, we find that boundary layer separation occurs in a parameter region with wakes in which two vortex pairs are formed per undulatory period. The physical mechanism of separation is governed by the slip(the ratio of swimming-to-body-wave speed), and the critical value of the slip in an inertial flow regime is approximately 4/3 rather than 1, which is independent of steepness(or amplitude). The relationship between pressure drag and relative velocity(between phase speed and free stream velocity) changes from linear to quadratic, corresponding to two different flow structures;this happens due to boundary layer separation, and the piecewise scaling relationship between pressure drag and relative velocity is explicitly clarified. Considering the viscosity effects, the separation criterion and the scaling relationship in the case of an undulatory brake are both synthetically modified using the Reynolds number, with all the required parameters clearly expressed. The results of this study provide physical insight into understanding the flow structures and hydrodynamics of the undulatory braking locomotion, which has instructional significance to brake design.展开更多
In this paper,we propose a new gait planning method for a multi-legged robot which has only 1 degree-of-freedom in each leg and has a passive body joint between two body segments.We firstly introduce the Finite State ...In this paper,we propose a new gait planning method for a multi-legged robot which has only 1 degree-of-freedom in each leg and has a passive body joint between two body segments.We firstly introduce the Finite State Machine(FSM)to the undulatory gait planning method of the 2n-legged robot.Then,the undulatory gait sequence for straight line motion is achieved by undulations motion.The idea that legged locomotion is achievable by less actuation of 2n-legged robot as well as the gait planning methods are verified finally by simulations and experiments.展开更多
Continuous observation data from 24 GPS stations are selected in the area （33.0°N-41.0°N, 95.0°E-105.0°E） for this study （the period is from Jan. 1, 2015 to Jan. 20, 2016）. Three components, NS...Continuous observation data from 24 GPS stations are selected in the area （33.0°N-41.0°N, 95.0°E-105.0°E） for this study （the period is from Jan. 1, 2015 to Jan. 20, 2016）. Three components, NS, EW and UD, of the daily solutions are filtered by the Hilbert-Huang transform （HHT） with frequency band of 5.787×10^-7-7.716 ×10^-8 Hz （20-150 days in period）. And short-term dynamic characteristics of micro displacement before Menyuan M6.4 earthquake are studied by using the temporal dependencies and cross spectrum analysis. The results show that before the earthquake the horizontal undulatory motions are higher than the average level in the series data which indicate the disturbance feature of regional stress before the earthquake. Three GPS stations on Qinghai-Tibet Plateau with their setting perpendicular to the seismogenic fault have consistent movement. The increase of amplitude of the horizontal micro motion observed before the quake is conducive to the earthquake occurrence. However, we could not be sure if the undulatory motion triggered the earthquake. It is quite necessary to build more GPS continuous observation stations and optimize the monitoring network so as to improve the understanding of the shortterm dynamic crustal variation before earthquake.展开更多
In addition to forward undulatory swimming, Gymnarchus niloticus can swim via undulations of the dorsal fin while the body axis remains straight; furthermore, it swims forward and backward in a similar way, which indi...In addition to forward undulatory swimming, Gymnarchus niloticus can swim via undulations of the dorsal fin while the body axis remains straight; furthermore, it swims forward and backward in a similar way, which indicates that the undulation of the dorsal fin can simultaneously provide bidirectional propulsive and maneuvering forces with the help of the tail fin. A high-resolution Charge-Coupled Device （CCD） imaging camera system is used to record kinematics of steady swimming as well as maneuvering in G. niloticus. Based on experimental data, this paper discusses the kinematics （cruising speed, wave speed, cycle frequency, amplitude, lateral displacement） of forward as well as backward swimming and maneuvering. During forward swimming, the propulsive force is generated mainly by undulations of the dorsal fin while the body axis remains straight. The kinematic parameters （wave speed, wavelength, cycle frequency, amplitude） have statistically significant correlations with cruising speed. In addition, the yaw at the head is minimal during steady swimming. From experimental data, the maximal lateral displacement of head is not more than 1% of the body length, while the maximal lateral displacement of the whole body is not more than 5% of the body length. Another important feature is that G. niloticus swims backwards using an undulatory mechanism that resembles the forward undulatory swimming mechanism. In backward swimming, the increase of lateral displacement of the head is comparatively significant; the amplitude profiles of the propulsive wave along the dorsal fin are significantly different from those in forward swimming. When G. niloticus does fast maneuvering, its body is first bent into either a C shape or an S shape, then it is rapidly unwound in a travelling wave fashion. It rarely maneuvers without the help of the tail fin and body bending.展开更多
A dynamic model for undulatory locomotion was proposed to study the swimming mechanism of a developed bionic robot tuna. On the basis of inviscid hydrodynamics and rigid-body dynamics, the momentum and propulsive forc...A dynamic model for undulatory locomotion was proposed to study the swimming mechanism of a developed bionic robot tuna. On the basis of inviscid hydrodynamics and rigid-body dynamics, the momentum and propulsive force required for propelling the swimming robot tuna＇s flexible body was calculated. By solving the established dynamic equations and efficiency formula, the swimming velocity and propulsive efficiency of the bionic robot tuna were obtained. The relationship between the kinematic parameters of the robot tuna＇s body curve and the hydrodynamic performances was established and discussed after hydrodynamic simulations. The results presented in this article can be used to increase the swimming speed, propulsive thrust, and the efficiency of underwater vehicles effectively.展开更多
文摘Many fishes use undulatory fin to propel themselves in the underwater environment. These locomotor mechanisms have a popular interest to many researchers. In the present study, we perform a three-dimensional unsteady computation of an undulatory mechanical fin that is driven by Shape Memory Alloy （SMA）. The objective of the computation is to investigate the fluid dynamics of force production associated with the undulatory mechanical fin. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing is used to compute the unsteady flow around the fin through five complete cycles. The pressure distribution on fin surface is computed and integrated to provide fin forces which are decomposed into lift and thrust. The velocity field is also computed throughout the swimming cycle. Finally, a comparison is conducted to reveal the dynamics of force generation according to the kinematic parameters of the undulatory fin （amplitude, frequency and wavelength）.
文摘Paraconsistent logic (PL) is a non-classical logic that accepts contradiction in its foundations. It can be represented in the form of paraconsistent annotated logic with annotation of two values (PAL2v). When used to model quantum phenomena, PAL2v is called paraquantum logic (PQL). In this work, the concept of PQL is applied to create a logical model presenting the fundamental principles of quantum mechanics that support particle-wave theory. This study uses the well-known Young’s double-slit experiment, wherein quantum phenomena appear when a monochromatic light beam passes through the two slits. We focused on a reference point located between the slits, where we observed the effects of two types of wave interferences in a region defined as a two-wave region (2W region). Considering that the effect in this 2W region is very similar to that studied by Huygens, we adopt a paraquantum logical model in which a particle (or quantum) is represented by two wave functions. The two wave functions result in four State Vectors (Ket, Bra,,) in the PQL Lattice that express the symmetry and the entanglement of Quantum Mechanics. The constructed model adapts well to the quantum phenomena, is strongly consistent, and can be considered as an innovative form of analysis in the field of quantum mechanics. Based on this model, we present in two parts (Part I and Part II) the comparative analysis of values found in SchrÖdinger’s equation and probabilistic models of wave-particle theory using Bonferroni inequality.
基金This work is supported by the National Science Foundation of China(No.91748123)the Natural Science Foundation of Shaanxi Province(Grant No.2019JM-145).
文摘Stingrays can undulate their wide pectoral fins to thrust themselves and swim freely underwater.Many researchers have used bionics to directly imitate their undulating mechanism and manufacture undulatory underwater robots.Based on the limitations of the existing undulatory underwater robots,this paper proposes a novel undulatory propulsion strategy,which aims to use the stingray undulating mechanism more thoroughly.First,the mathematical models of both traditional and novel structures are established to accurately describe their undulating mechanism.Then,based on the dynamic mesh technology,the flow field vortex structure they generated is analyzed through fluid-structure interaction simulation,and the thrust force and lateral force generated by them are calculated,which verified that this novel propulsion strategy is indeed more effective.Finally,a prototype robot based on the improved propulsion strategy is manufactured.Compared with the existing stingray robots,the prototype has obvious advantages,thus verifying the accuracy of the simulation results.
基金supported in part by the National Key Research and Development Program of China under Grant 2023YFB4707000,in part by the National Natural Science Foundation of China under Grant U24A20282,Grant U24A20281,Grant U23A20343,Grant U23B2038in part by the Youth Innovation Promotion Association CAS under Grant Y2022053in part by Beijing Natural Science Foundation under Grant 4222055。
文摘The propulsion mechanisms of biomimetic underwater vehicles using bionic undulatory fins have been extensively studied for their potential to enhance efficiency and maneuverability in underwater environments.However,the hydrodynamic interactions between the vehicle body,robotic manipulator,and fluctuating motion remain less explored,particularly in turbulent conditions.In this work,a Biomimetic Underwater Vehicle-Manipulator System(BUVMS)propelled using bionic undulatory fins is considered.The propulsion mechanism and hydrodynamic performance of fluctuating motion are analyzed by numerical simulation.The drag coefficients of the BUVMS at different Reynolds numbers are calculated,and the investigation of vortex generation during the motion of the BUVMS reveals that vortex binding and shedding are the key factors for propulsion generation.Various moving modes of the BUVMS are developed in conjunction with the pro-pulsion mechanism.The hydrodynamic loads during the motion of the underwater robotic arm in a turbulent environment are analyzed.A simple motion strategy is proposed to reduce the effect of water drag on the manipulation of the robotic arm and on the overall stability of the BUVMS.The results of the hydrodynamic analysis offer systematic guidance for controlling underwater operations of the BUVMS.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11672291, and 11372310)the Chinese Academy of Sciences (Grant No. QYZDB-SSW-SYS002)。
文摘Flow over a fish-like airfoil is numerically investigated to elaborate the hydrodynamics of the undulatory braking locomotion for an elongated eel-like body or long-based fin. For undulation with low frequency, we find that boundary layer separation occurs in a parameter region with wakes in which two vortex pairs are formed per undulatory period. The physical mechanism of separation is governed by the slip(the ratio of swimming-to-body-wave speed), and the critical value of the slip in an inertial flow regime is approximately 4/3 rather than 1, which is independent of steepness(or amplitude). The relationship between pressure drag and relative velocity(between phase speed and free stream velocity) changes from linear to quadratic, corresponding to two different flow structures;this happens due to boundary layer separation, and the piecewise scaling relationship between pressure drag and relative velocity is explicitly clarified. Considering the viscosity effects, the separation criterion and the scaling relationship in the case of an undulatory brake are both synthetically modified using the Reynolds number, with all the required parameters clearly expressed. The results of this study provide physical insight into understanding the flow structures and hydrodynamics of the undulatory braking locomotion, which has instructional significance to brake design.
文摘In this paper,we propose a new gait planning method for a multi-legged robot which has only 1 degree-of-freedom in each leg and has a passive body joint between two body segments.We firstly introduce the Finite State Machine(FSM)to the undulatory gait planning method of the 2n-legged robot.Then,the undulatory gait sequence for straight line motion is achieved by undulations motion.The idea that legged locomotion is achievable by less actuation of 2n-legged robot as well as the gait planning methods are verified finally by simulations and experiments.
基金funded by the Project of National Natural Science Foundation of China,based on GPS and leveling data simulation and study on the state of seismogenic deformation field and its mechanical characteristics(41274008)the Basic Research Project of Institute the Earthquake Science,China Earthquake Administration,crustal deformation observation experiment and dynamic process simulation research(2014IES010201)
文摘Continuous observation data from 24 GPS stations are selected in the area （33.0°N-41.0°N, 95.0°E-105.0°E） for this study （the period is from Jan. 1, 2015 to Jan. 20, 2016）. Three components, NS, EW and UD, of the daily solutions are filtered by the Hilbert-Huang transform （HHT） with frequency band of 5.787×10^-7-7.716 ×10^-8 Hz （20-150 days in period）. And short-term dynamic characteristics of micro displacement before Menyuan M6.4 earthquake are studied by using the temporal dependencies and cross spectrum analysis. The results show that before the earthquake the horizontal undulatory motions are higher than the average level in the series data which indicate the disturbance feature of regional stress before the earthquake. Three GPS stations on Qinghai-Tibet Plateau with their setting perpendicular to the seismogenic fault have consistent movement. The increase of amplitude of the horizontal micro motion observed before the quake is conducive to the earthquake occurrence. However, we could not be sure if the undulatory motion triggered the earthquake. It is quite necessary to build more GPS continuous observation stations and optimize the monitoring network so as to improve the understanding of the shortterm dynamic crustal variation before earthquake.
文摘In addition to forward undulatory swimming, Gymnarchus niloticus can swim via undulations of the dorsal fin while the body axis remains straight; furthermore, it swims forward and backward in a similar way, which indicates that the undulation of the dorsal fin can simultaneously provide bidirectional propulsive and maneuvering forces with the help of the tail fin. A high-resolution Charge-Coupled Device （CCD） imaging camera system is used to record kinematics of steady swimming as well as maneuvering in G. niloticus. Based on experimental data, this paper discusses the kinematics （cruising speed, wave speed, cycle frequency, amplitude, lateral displacement） of forward as well as backward swimming and maneuvering. During forward swimming, the propulsive force is generated mainly by undulations of the dorsal fin while the body axis remains straight. The kinematic parameters （wave speed, wavelength, cycle frequency, amplitude） have statistically significant correlations with cruising speed. In addition, the yaw at the head is minimal during steady swimming. From experimental data, the maximal lateral displacement of head is not more than 1% of the body length, while the maximal lateral displacement of the whole body is not more than 5% of the body length. Another important feature is that G. niloticus swims backwards using an undulatory mechanism that resembles the forward undulatory swimming mechanism. In backward swimming, the increase of lateral displacement of the head is comparatively significant; the amplitude profiles of the propulsive wave along the dorsal fin are significantly different from those in forward swimming. When G. niloticus does fast maneuvering, its body is first bent into either a C shape or an S shape, then it is rapidly unwound in a travelling wave fashion. It rarely maneuvers without the help of the tail fin and body bending.
基金the National Natural Science Foundation of China (Grant No. 10332040).
文摘A dynamic model for undulatory locomotion was proposed to study the swimming mechanism of a developed bionic robot tuna. On the basis of inviscid hydrodynamics and rigid-body dynamics, the momentum and propulsive force required for propelling the swimming robot tuna＇s flexible body was calculated. By solving the established dynamic equations and efficiency formula, the swimming velocity and propulsive efficiency of the bionic robot tuna were obtained. The relationship between the kinematic parameters of the robot tuna＇s body curve and the hydrodynamic performances was established and discussed after hydrodynamic simulations. The results presented in this article can be used to increase the swimming speed, propulsive thrust, and the efficiency of underwater vehicles effectively.
