Floating facilities have been studied based on the static analysis of mooring cables over the past decades. To analyze the floating system of a spherical buoy moored by a cable with a higher accuracy than before, the ...Floating facilities have been studied based on the static analysis of mooring cables over the past decades. To analyze the floating system of a spherical buoy moored by a cable with a higher accuracy than before, the dynamics of the cables are considered in the construction of the numerical modeling. The cable modeling is established based on a new element frame through which the hydrodynamic loads are expressed efficiently. The accuracy of the cable modeling is verified with an experiment that is conducted by a catenary chain moving in a water tank. In addition, the modeling of a spherical buoy is established with respect to a spherical coordinate in three dimensions, which can suffers the gravity, the variable buoyancy and Froude-Krylov loads. Finally, the numerical modeling for the system of a spherical buoy moored by a cable is established, and a virtual simulation is proceeded with the X- and Y-directional linear waves and the X-directional current. The comparison with the commercial simulation code Proteus DS indicates that the system is accurately analyzed by the numerical modeling. The tensions within the cable, the motions of the system, and the relationship between the motions and waves are illustrated according to the defined sea state. The dynamics of the cables should be considered in analyzing the floating system of a spherical buoy moored by a cable.展开更多
Transcranial Hall-effect stimulation(THS) is a new stimulation method in which an ultrasonic wave in a static magnetic field generates an electric field in an area of interest such as in the brain to modulate neuron...Transcranial Hall-effect stimulation(THS) is a new stimulation method in which an ultrasonic wave in a static magnetic field generates an electric field in an area of interest such as in the brain to modulate neuronal activities. However, the biophysical basis of simulating the neurons remains unknown. To address this problem, we perform a theoretical analysis based on a passive cable model to investigate the THS mechanism of neurons. Nerve tissues are conductive; an ultrasonic wave can move ions embedded in the tissue in a static magnetic field to generate an electric field(due to Lorentz force).In this study, a simulation model for an ultrasonically induced electric field in a static magnetic field is derived. Then,based on the passive cable model, the analytical solution for the voltage distribution in a nerve tissue is determined. The simulation results showthat THS can generate a voltage to stimulate neurons. Because the THS method possesses a higher spatial resolution and a deeper penetration depth, it shows promise as a tool for treating or rehabilitating neuropsychiatric disorders.展开更多
This paper proposes a geometrically exact formulation for three-dimensional static and dynamic analyses of the umbilical cable in a deep-sea remotely operated vehicle(ROV) system. The presented formulation takes acc...This paper proposes a geometrically exact formulation for three-dimensional static and dynamic analyses of the umbilical cable in a deep-sea remotely operated vehicle(ROV) system. The presented formulation takes account of the geometric nonlinearities of large displacement, effects of axial load and bending stiffness for modeling of slack cables. The resulting nonlinear second-order governing equations are discretized spatially by the finite element method and solved temporally by the generalized-a implicit time integration algorithm, which is adapted to the case of varying coefficient matrices. The ability to consider three-dimensional union action of ocean current and ship heave motion upon the umbilical cable is the key feature of this analysis. The presented formulation is firstly validated, and then three numerical examples for the umbilical cable in a deep-sea ROV system are demonstrated and discussed, including the steady configurations only under the action of depth-dependent ocean current, the dynamic responses in the case of the only ship heave motion, and in the case of the combined action of the ship heave motion and ocean current.展开更多
A frequency-domain algorithm is presented for the dynamic analysis of guyed masts. By introducing a four-degrees-of-freedom model of a suspended cable, guyed masts are simpli?ed as an equivalent cable-beam model. Th...A frequency-domain algorithm is presented for the dynamic analysis of guyed masts. By introducing a four-degrees-of-freedom model of a suspended cable, guyed masts are simpli?ed as an equivalent cable-beam model. Then, based on the discrete random vibration theory, recurrence formulas for the statistical moments of the wind-induced behavior of guyed masts are developed with the wind load treated as ?ltered white noise excitation. The dynamic analysis of a two-level guyed mast has been illustrated. Finally, results from a wind-tunnel experiment of guyed mast are used to testify the theory developed in this paper.展开更多
基金Supported by Human Resources Development Program of Korea Institute of Energy Technology Evaluation and Planning(KETEP),Ministry of Trade,Industry and Energy of Korea(Grant No.20134030200290)
文摘Floating facilities have been studied based on the static analysis of mooring cables over the past decades. To analyze the floating system of a spherical buoy moored by a cable with a higher accuracy than before, the dynamics of the cables are considered in the construction of the numerical modeling. The cable modeling is established based on a new element frame through which the hydrodynamic loads are expressed efficiently. The accuracy of the cable modeling is verified with an experiment that is conducted by a catenary chain moving in a water tank. In addition, the modeling of a spherical buoy is established with respect to a spherical coordinate in three dimensions, which can suffers the gravity, the variable buoyancy and Froude-Krylov loads. Finally, the numerical modeling for the system of a spherical buoy moored by a cable is established, and a virtual simulation is proceeded with the X- and Y-directional linear waves and the X-directional current. The comparison with the commercial simulation code Proteus DS indicates that the system is accurately analyzed by the numerical modeling. The tensions within the cable, the motions of the system, and the relationship between the motions and waves are illustrated according to the defined sea state. The dynamics of the cables should be considered in analyzing the floating system of a spherical buoy moored by a cable.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61273063 and 61503321)the China Postdoctoral Science Foundation(Grant No.2013M540215)+1 种基金the Natural Science Foundation of Hebei Province,China(Grant No.F2014203161)the Youth Research Program of Yanshan University,China(Grant No.02000134)
文摘Transcranial Hall-effect stimulation(THS) is a new stimulation method in which an ultrasonic wave in a static magnetic field generates an electric field in an area of interest such as in the brain to modulate neuronal activities. However, the biophysical basis of simulating the neurons remains unknown. To address this problem, we perform a theoretical analysis based on a passive cable model to investigate the THS mechanism of neurons. Nerve tissues are conductive; an ultrasonic wave can move ions embedded in the tissue in a static magnetic field to generate an electric field(due to Lorentz force).In this study, a simulation model for an ultrasonically induced electric field in a static magnetic field is derived. Then,based on the passive cable model, the analytical solution for the voltage distribution in a nerve tissue is determined. The simulation results showthat THS can generate a voltage to stimulate neurons. Because the THS method possesses a higher spatial resolution and a deeper penetration depth, it shows promise as a tool for treating or rehabilitating neuropsychiatric disorders.
基金financially supported by the National High Technology Research and Development Program of China(863 Program,Grant No.2008AA09Z201)
文摘This paper proposes a geometrically exact formulation for three-dimensional static and dynamic analyses of the umbilical cable in a deep-sea remotely operated vehicle(ROV) system. The presented formulation takes account of the geometric nonlinearities of large displacement, effects of axial load and bending stiffness for modeling of slack cables. The resulting nonlinear second-order governing equations are discretized spatially by the finite element method and solved temporally by the generalized-a implicit time integration algorithm, which is adapted to the case of varying coefficient matrices. The ability to consider three-dimensional union action of ocean current and ship heave motion upon the umbilical cable is the key feature of this analysis. The presented formulation is firstly validated, and then three numerical examples for the umbilical cable in a deep-sea ROV system are demonstrated and discussed, including the steady configurations only under the action of depth-dependent ocean current, the dynamic responses in the case of the only ship heave motion, and in the case of the combined action of the ship heave motion and ocean current.
基金Project supported by the National Natural Science Foundation of China (No. 59778030).
文摘A frequency-domain algorithm is presented for the dynamic analysis of guyed masts. By introducing a four-degrees-of-freedom model of a suspended cable, guyed masts are simpli?ed as an equivalent cable-beam model. Then, based on the discrete random vibration theory, recurrence formulas for the statistical moments of the wind-induced behavior of guyed masts are developed with the wind load treated as ?ltered white noise excitation. The dynamic analysis of a two-level guyed mast has been illustrated. Finally, results from a wind-tunnel experiment of guyed mast are used to testify the theory developed in this paper.