This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational ...This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.展开更多
The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integr...The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integrates a triboelectric nanogenerator(TENG)and an electromagnetic generator(EMG).TENG is a new technology that can capture mechanical energy from the environment and convert it into electrical energy,and is particularly suitable for common natural or man-made power sources such as human movement,wind power,and water flow.EMG is a device that converts mechanical energy into electrical energy through the principle of electromagnetic induction and can usually provide stable power output.The composite design leverages the complementary advantages of both technologies to efficiently capture and convert marine wave energy.By combining the TENG’s high energy conversion efficiency,lowcost,lightweight structure,and simple designwith the EMG’s capabilities,the systemprovides a sustainable solution for marine energy development.Experimental results demonstrate that at a rotational speed of 3.0 r/s,the TENG component of the WWR-TENG achieves an open-circuit voltage of approximately 280 V and a shortcircuit current of 20μA.At the same time,the EMG unit exhibits an open-circuit voltage of 14 V and a short-circuit current of 14 mA.Furthermore,when integrated with a power management circuit,the WWR-TENG charges a 680μF capacitor to 3 V within 10 s at a rotational speed of 3.0 r/s.A simulated wave environment platform was established,enabling the WWR-TENG to maintain the thermo-hygrometer in normal operation under simulated wave conditions.These findings validate the hybrid system’s effectiveness in harnessing and storingwave energy,highlighting its potential for practical marine energy applications.展开更多
We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground...We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground state(0^(+))energy of ^(6)He and the excited state(0^(+))energy of 6 Li calculated with various random distributions and manually selected generation coordinates,we found that the heavy tail characteristic of the logistic distribution better describes the features of the halo nuclei.Subsequently,the Adam algorithm from machine learning was applied to optimize the basis wave functions,indicating that a limited number of basis wave functions can approximate the converged values.These results offer some empirical insights for selecting basis wave functions and contribute to the broader application of machine learning methods in predicting effective basis wave functions.展开更多
In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Be...In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.展开更多
In this paper, the design, construction and ocean testing of a wave energy conversion system are studied. Based on the motion characteristics of double buoys in ocean waves, a wave energy conversion system with perman...In this paper, the design, construction and ocean testing of a wave energy conversion system are studied. Based on the motion characteristics of double buoys in ocean waves, a wave energy conversion system with permanent magnet tubular linear generator （PMTLG） is proposed to convert ocean wave energy into electricity. The wave energy conversion system was installed in the Yellow Sea near Lianyungang, China. The ocean test re- suits indicate that it had dynamic and static performance, and obtained an expected amount of electricity. The calcu- lation result indicates the average output power was about 1 000 W, and the conversion efficiency from wave en- ergy into electricity was 1.4%. In addition, the wireless data communication, mechanics and oceanography were also discussed.展开更多
Plane wave generators(PWGs) are used to accelerate flyer plates to high velocities with their generated plane waves,which are widely used in the test of dynamic properties of materials.The traditional PWG is composed ...Plane wave generators(PWGs) are used to accelerate flyer plates to high velocities with their generated plane waves,which are widely used in the test of dynamic properties of materials.The traditional PWG is composed of two explosives with different detonation velocities.It is difficult to implement the related fabrication processes and control the generated waves due to its complicated structures.A simple plane wave generator is presented in this paper,which is composed of two identical cylindrical high explosive(HE) charges and an air-metal barrier.A theoretical model was established based on two different paths of the propagation of detonation waves,based on which the size of air-metal barrier was calculated for a given charge.The corresponding numerical simulations were also carried out by AUTODYN-2D based on the calculated results,which were used to compare with the theoretical calculations.A detonation wave with a flatness of 0.039 μs within the range of 70-percent diameter of the main charge was obtained through the simulations.展开更多
New renewable energy exploitation technologies in offshore structures are vital for future energy production systems.Offshore hybrid wind-wave power generation(HWWPG)systems face increased component failure rates beca...New renewable energy exploitation technologies in offshore structures are vital for future energy production systems.Offshore hybrid wind-wave power generation(HWWPG)systems face increased component failure rates because of harsh weather,significantly affecting the maintenance procedures and reliability.Different types of failure rates of the wind turbine(WT)and wave energy converter(WEC),e.g.,the degradation and failure rates during regular wind speed fluctuation,the degradation and failure rates during intense wind speed fluctuation are considered.By incorporating both WT and WEC,the HWWPG system is designed to enhance the overall amount of electrical energy produced by the system over a given period under varying weather conditions.The universal generating function technique is used to calculate the HWWPG system dependability measures in a structured and efficient manner.This research highlights that intense weather conditions increase the failure rates of both WT and WEC,resulting in higher maintenance costs and more frequent downtimes,thus impacting the HWWPG system’s reliability.Although the HWWPG system can meet the energy demands in the presence of high failure rates,the reliance of the hybrid system on both WT and WEC helps maintain a relatively stable demand satisfaction during periods of high energy demand despite adverse weather conditions.To confirm the added value and applicability of the developed model,a case study of an offshore hybrid platform is conducted.The findings underscore the system’s robustness in maintaining energy production under varied weather conditions,though higher failure rates and maintenance costs arise in intense scenarios.展开更多
This paper explores the applicability of the generalized wave impedance hypothesis in split Hopkinson pressure bar(SHPB)experiments,particularly under non-ideal conditions.The study investigates the effects of changes...This paper explores the applicability of the generalized wave impedance hypothesis in split Hopkinson pressure bar(SHPB)experiments,particularly under non-ideal conditions.The study investigates the effects of changes in wave impedance ratio and cross-sectional area ratio on the dynamic response of materials at high strain rates.Through theoretical analysis and numerical simulation,the impact of different wave impedance and cross-sectional area ratios on stress wave propagation characteristics is discussed in detail.It is found that when the cross-sections of two bars differ,shear strain occurs at the abrupt cross-section,leading to waveform distortion in the transmitted and reflected waves.The force balance condition does not always align with the momentum conservation theorem,and only when the three waveforms and wavelengths are completely consistent do they align.The research shows that when the wave impedance ratio and cross-sectional area ratio are within a specific range,the generalized wave impedance hypothesis can accurately predict changes in Young’s modulus and density.Additionally,the study extends the exploration to key factors such as wave impedance ratio,wave speed,Young’s modulus,density,and area ratio.展开更多
A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The p...A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The proposed method,based on the optimized multi-index modulation, does not limit the number of signals in the first and second constellations and abandons the concept of limiting the number of signals in different constellations. It successfully increases the spectrum efficiency of the system while expanding the number of modulation symbol combinations and the index dimension of PSWFs signals. The proposed method outperforms the PSWFs multi-carrier index modulation method based on optimized multiple indexes in terms of spectrum efficiency, but at the expense of system computational complexity and bit error performance. For example, with n=10 subcarriers and a bit error rate of 1×10^(-5),spectral efficiency can be raised by roughly 12.4%.展开更多
The new three phase VFVA sine wave generator is presented in this paper. A new sampling holding three phase VFVA sine wave generator’s principle, circuit and experimentation waveform are introduced. The principle of ...The new three phase VFVA sine wave generator is presented in this paper. A new sampling holding three phase VFVA sine wave generator’s principle, circuit and experimentation waveform are introduced. The principle of this sampling holding circuit is simple and the realization of har’dware circuit is easy. Here we describe the three phase reference sine wave which is produced by this generator’s circuit and is required by PWM inverter is described in this paper, and also introduced the speed control and harmonir analysis of PWM inverter variable frequency.展开更多
This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator producing high power millimeter waves, which has been investigated with a two and onehalf dimensional electromagnetic relativistic Par...This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator producing high power millimeter waves, which has been investigated with a two and onehalf dimensional electromagnetic relativistic Particle-in-Cell (PIC) plasma simulation code. Themodified device can operate in a lower diode-voltage regime with much higher radiation efficiencyand slight downshift of operation frequency. There exist the optima for the permittivity of thedielectric liner and for the magnitude of the guiding magnetic field. The required intensity of theguiding field is reduced by the introduction of the liner. The enhanced propagation of the electronbeam is studied in the presence of the liner.展开更多
A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head stra...A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head strage water tank and a current generator to mainly reproduce long waves like tsunami and storm surge. The paper desribes several experimental series to predict the applicability of the generator to model tests. The three operating sysemes are capable to be controlled in one operating sysytem and start time is contorolled separately according with the target tsunami and storm surge profiles. A sharp tsunami profile is reproduced in adjusting the start timing of piston type wave maker and opening gates of head storage tunk. Any type of tsunami waves are reproduced in the generator and it becomes a storong tool to predict the effective of＂resiliency＂ of hardwares.展开更多
Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performan...Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.展开更多
In this paper, based on hyperbolic tanh-function method and homogeneous balance method, and auxiliary equation method, some new exact solitary solutions to the generalized mKdV equation and generalized Zakharov-Kuzent...In this paper, based on hyperbolic tanh-function method and homogeneous balance method, and auxiliary equation method, some new exact solitary solutions to the generalized mKdV equation and generalized Zakharov-Kuzentsov equation are constructed by the method of auxiliary equation with function transformation with aid of symbolic computation system Mathematica. The method is of important significance in seeking new exact solutions to the evolution equation with arbitrary nonlinear term.展开更多
In this paper, we study the higher dimensional nonlinear Rossby waves under the generalized beta effect.Using methods of the multiple scales and weak nonlinear perturbation expansions [Q. S. Liu, et al., Phys. Lett. A...In this paper, we study the higher dimensional nonlinear Rossby waves under the generalized beta effect.Using methods of the multiple scales and weak nonlinear perturbation expansions [Q. S. Liu, et al., Phys. Lett. A383(2019) 514], we derive a new(2 + 1)-dimensional generalized Boussinesq equation from the barotropic potential vorticity equation. Based on bifurcation theory of planar dynamical systems and the qualitative theory of ordinary differential equations, the dynamical analysis and exact traveling wave solutions of the new generalized Boussinesq equation are obtained. Moreover, we provide the numerical simulations of these exact solutions under some conditions of all parameters. The numerical results show that these traveling wave solutions are all the Rossby solitary waves.展开更多
In this paper, the generalized Dodd-Bullough-Mikhailov equation is studied. The existence of periodic wave and unbounded wave solutions is proved by using the method of bifurcation theory of dynamical systems. Under d...In this paper, the generalized Dodd-Bullough-Mikhailov equation is studied. The existence of periodic wave and unbounded wave solutions is proved by using the method of bifurcation theory of dynamical systems. Under different parametric conditions, various sufficient conditions to guarantee the existence of the above solutions are given.Some exact explicit parametric representations of the above travelling solutions are obtained.展开更多
In this paper,the generalized Boussinesq wave equation u tt-uxx+a(um) xx+buxxxx=0 is investigated by using the bifurcation theory and the method of phase portraits analysis.Under the different parameter conditions,the...In this paper,the generalized Boussinesq wave equation u tt-uxx+a(um) xx+buxxxx=0 is investigated by using the bifurcation theory and the method of phase portraits analysis.Under the different parameter conditions,the exact explicit parametric representations for solitary wave solutions and periodic wave solutions are obtained.展开更多
Tool waves, also named collar waves, propagating along the drill collars in acoustic logging while drilling （ALWD）, strongly interfere with the needed P- and S-waves of a penetrated formation, which is a key issue i...Tool waves, also named collar waves, propagating along the drill collars in acoustic logging while drilling （ALWD）, strongly interfere with the needed P- and S-waves of a penetrated formation, which is a key issue in picking up formation P- and S-wave velocities. Previous studies on physical insulation for the collar waves designed on the collar between the source and the receiver sections did not bring to a satisfactory solution. In this paper, we investigate the propagation features of collar waves in different models. It is confirmed that there exists an indirect collar wave in the synthetic full waves due to the coupling between the drill collar and the borehole, even there is a perfect isolator between the source and the receiver. The direct collar waves propagating all along the tool and the indirect ones produced by echoes from the borehole wall are summarized as the generalized collar waves. Further analyses show that the indirect collar waves could be relatively strong in the full wave data. This is why the collar waves cannot be eliminated with satisfactory effect in many cases by designing the physical isolators carved on the tool.展开更多
文摘This review paper examines the various types of electrical generators used to convert wave energy into electrical energy.The focus is on both linear and rotary generators,including their design principles,operational efficiencies,and technological advancements.Linear generators,such as Induction,permanent magnet synchronous,and switched reluctance types,are highlighted for their direct conversion capability,eliminating the need for mechanical gearboxes.Rotary Induction generators,permanent magnet synchronous generators,and doubly-fed Induction generators are evaluated for their established engineering principles and integration with existing grid infrastructure.The paper discusses the historical development,environmental benefits,and ongoing advancements in wave energy technologies,emphasizing the increasing feasibility and scalability of wave energy as a renewable source.Through a comprehensive analysis,this review provides insights into the current state and future prospects of electrical generators in wave energy conversion,underscoring their potential to significantly reduce reliance on fossil fuels and mitigate environmental impacts.
文摘The ocean,as one of Earth’s largest natural resources,covers over 70% of the planet’s surface and holds vast water energy potential.Building on this context,this study designs a hybrid generator(WWR-TENG)that integrates a triboelectric nanogenerator(TENG)and an electromagnetic generator(EMG).TENG is a new technology that can capture mechanical energy from the environment and convert it into electrical energy,and is particularly suitable for common natural or man-made power sources such as human movement,wind power,and water flow.EMG is a device that converts mechanical energy into electrical energy through the principle of electromagnetic induction and can usually provide stable power output.The composite design leverages the complementary advantages of both technologies to efficiently capture and convert marine wave energy.By combining the TENG’s high energy conversion efficiency,lowcost,lightweight structure,and simple designwith the EMG’s capabilities,the systemprovides a sustainable solution for marine energy development.Experimental results demonstrate that at a rotational speed of 3.0 r/s,the TENG component of the WWR-TENG achieves an open-circuit voltage of approximately 280 V and a shortcircuit current of 20μA.At the same time,the EMG unit exhibits an open-circuit voltage of 14 V and a short-circuit current of 14 mA.Furthermore,when integrated with a power management circuit,the WWR-TENG charges a 680μF capacitor to 3 V within 10 s at a rotational speed of 3.0 r/s.A simulated wave environment platform was established,enabling the WWR-TENG to maintain the thermo-hygrometer in normal operation under simulated wave conditions.These findings validate the hybrid system’s effectiveness in harnessing and storingwave energy,highlighting its potential for practical marine energy applications.
基金supported by the National Key R&D Program of China(No.2023YFA1606701)the National Natural Science Foundation of China(Nos.12175042,11890710,11890714,12047514,12147101,and 12347106)+1 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)China National Key R&D Program(No.2022YFA1602402).
文摘We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground state(0^(+))energy of ^(6)He and the excited state(0^(+))energy of 6 Li calculated with various random distributions and manually selected generation coordinates,we found that the heavy tail characteristic of the logistic distribution better describes the features of the halo nuclei.Subsequently,the Adam algorithm from machine learning was applied to optimize the basis wave functions,indicating that a limited number of basis wave functions can approximate the converged values.These results offer some empirical insights for selecting basis wave functions and contribute to the broader application of machine learning methods in predicting effective basis wave functions.
基金Supported by the National Natural Science Foundation of China(No.51577124)Tianjin Research Program of Application Foundation and Advanced Technology(No.15JCZDJC32100)
文摘In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.
基金Supported by the National Natural Science Foundation of China(No.41076054)Special Foundation for State Oceanic Administration of China(No.GHME2011GD02)Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ1416)
文摘In this paper, the design, construction and ocean testing of a wave energy conversion system are studied. Based on the motion characteristics of double buoys in ocean waves, a wave energy conversion system with permanent magnet tubular linear generator （PMTLG） is proposed to convert ocean wave energy into electricity. The wave energy conversion system was installed in the Yellow Sea near Lianyungang, China. The ocean test re- suits indicate that it had dynamic and static performance, and obtained an expected amount of electricity. The calcu- lation result indicates the average output power was about 1 000 W, and the conversion efficiency from wave en- ergy into electricity was 1.4%. In addition, the wireless data communication, mechanics and oceanography were also discussed.
基金sponsored by the National Natural Science Foundation of China(NSFC10902053)the Zijin Intelligent Program,Nanjing University of Science and Technology (2013_ZJ_0101)+1 种基金Qing Lan Project of Jiangsu province and the Fundamental Research Funds for the Central Universities (No.2012XQTR006)the State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology)(KFJJ15-07M) for their great support on the research work presented in this paper
文摘Plane wave generators(PWGs) are used to accelerate flyer plates to high velocities with their generated plane waves,which are widely used in the test of dynamic properties of materials.The traditional PWG is composed of two explosives with different detonation velocities.It is difficult to implement the related fabrication processes and control the generated waves due to its complicated structures.A simple plane wave generator is presented in this paper,which is composed of two identical cylindrical high explosive(HE) charges and an air-metal barrier.A theoretical model was established based on two different paths of the propagation of detonation waves,based on which the size of air-metal barrier was calculated for a given charge.The corresponding numerical simulations were also carried out by AUTODYN-2D based on the calculated results,which were used to compare with the theoretical calculations.A detonation wave with a flatness of 0.039 μs within the range of 70-percent diameter of the main charge was obtained through the simulations.
文摘New renewable energy exploitation technologies in offshore structures are vital for future energy production systems.Offshore hybrid wind-wave power generation(HWWPG)systems face increased component failure rates because of harsh weather,significantly affecting the maintenance procedures and reliability.Different types of failure rates of the wind turbine(WT)and wave energy converter(WEC),e.g.,the degradation and failure rates during regular wind speed fluctuation,the degradation and failure rates during intense wind speed fluctuation are considered.By incorporating both WT and WEC,the HWWPG system is designed to enhance the overall amount of electrical energy produced by the system over a given period under varying weather conditions.The universal generating function technique is used to calculate the HWWPG system dependability measures in a structured and efficient manner.This research highlights that intense weather conditions increase the failure rates of both WT and WEC,resulting in higher maintenance costs and more frequent downtimes,thus impacting the HWWPG system’s reliability.Although the HWWPG system can meet the energy demands in the presence of high failure rates,the reliance of the hybrid system on both WT and WEC helps maintain a relatively stable demand satisfaction during periods of high energy demand despite adverse weather conditions.To confirm the added value and applicability of the developed model,a case study of an offshore hybrid platform is conducted.The findings underscore the system’s robustness in maintaining energy production under varied weather conditions,though higher failure rates and maintenance costs arise in intense scenarios.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2341244,12172179,11772160,and 12202207)China Postdoctoral Science Foundation(Grant No.2022M711623)+3 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20220968)Open Funds for Key Laboratory of Impact and Safety Engineering(Ningbo University)Ministry of Education(Grant No.CJ202201)Open Funds for Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province(Grant No.22kfgk03).
文摘This paper explores the applicability of the generalized wave impedance hypothesis in split Hopkinson pressure bar(SHPB)experiments,particularly under non-ideal conditions.The study investigates the effects of changes in wave impedance ratio and cross-sectional area ratio on the dynamic response of materials at high strain rates.Through theoretical analysis and numerical simulation,the impact of different wave impedance and cross-sectional area ratios on stress wave propagation characteristics is discussed in detail.It is found that when the cross-sections of two bars differ,shear strain occurs at the abrupt cross-section,leading to waveform distortion in the transmitted and reflected waves.The force balance condition does not always align with the momentum conservation theorem,and only when the three waveforms and wavelengths are completely consistent do they align.The research shows that when the wave impedance ratio and cross-sectional area ratio are within a specific range,the generalized wave impedance hypothesis can accurately predict changes in Young’s modulus and density.Additionally,the study extends the exploration to key factors such as wave impedance ratio,wave speed,Young’s modulus,density,and area ratio.
基金supported by the China National Postdoctoral Program for Innovative Talents(BX20200039)the Special Fund Project of“Mount Taishan Scholars”Construction Project in Shandong Province(ts20081130).
文摘A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The proposed method,based on the optimized multi-index modulation, does not limit the number of signals in the first and second constellations and abandons the concept of limiting the number of signals in different constellations. It successfully increases the spectrum efficiency of the system while expanding the number of modulation symbol combinations and the index dimension of PSWFs signals. The proposed method outperforms the PSWFs multi-carrier index modulation method based on optimized multiple indexes in terms of spectrum efficiency, but at the expense of system computational complexity and bit error performance. For example, with n=10 subcarriers and a bit error rate of 1×10^(-5),spectral efficiency can be raised by roughly 12.4%.
文摘The new three phase VFVA sine wave generator is presented in this paper. A new sampling holding three phase VFVA sine wave generator’s principle, circuit and experimentation waveform are introduced. The principle of this sampling holding circuit is simple and the realization of har’dware circuit is easy. Here we describe the three phase reference sine wave which is produced by this generator’s circuit and is required by PWM inverter is described in this paper, and also introduced the speed control and harmonir analysis of PWM inverter variable frequency.
文摘This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator producing high power millimeter waves, which has been investigated with a two and onehalf dimensional electromagnetic relativistic Particle-in-Cell (PIC) plasma simulation code. Themodified device can operate in a lower diode-voltage regime with much higher radiation efficiencyand slight downshift of operation frequency. There exist the optima for the permittivity of thedielectric liner and for the magnitude of the guiding magnetic field. The required intensity of theguiding field is reduced by the introduction of the liner. The enhanced propagation of the electronbeam is studied in the presence of the liner.
文摘A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head strage water tank and a current generator to mainly reproduce long waves like tsunami and storm surge. The paper desribes several experimental series to predict the applicability of the generator to model tests. The three operating sysemes are capable to be controlled in one operating sysytem and start time is contorolled separately according with the target tsunami and storm surge profiles. A sharp tsunami profile is reproduced in adjusting the start timing of piston type wave maker and opening gates of head storage tunk. Any type of tsunami waves are reproduced in the generator and it becomes a storong tool to predict the effective of＂resiliency＂ of hardwares.
基金supported by The Swedish Energy AgencyThe Gothenburg Energy Research Foundation,The Goran Gustavsson Research Foundation,Angpanneforeningen’s Foundation for Research and Development,The Olle Engkvist Foundation,The J.Gust.Richert Foundation,CF Environmental Fund,Vargons Research Foundation,The Swedish Research Council grant No.621-2009-3417 and the Wallenius Foundation.
文摘Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.
基金Project supported by the National Natural Science Foundation of China （Grant No 10461006）, the High Education Science Research Program （Grant No NJ02035） of Inner Mongolia Autonomous Region, Natural Science Foundation of Inner Mongolia Autonomous Region （Grant No 2004080201103） and the Youth Research Program of Inner Mongolia Normal University （Grant No QN005023）.
文摘In this paper, based on hyperbolic tanh-function method and homogeneous balance method, and auxiliary equation method, some new exact solitary solutions to the generalized mKdV equation and generalized Zakharov-Kuzentsov equation are constructed by the method of auxiliary equation with function transformation with aid of symbolic computation system Mathematica. The method is of important significance in seeking new exact solutions to the evolution equation with arbitrary nonlinear term.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11562014,11762011,11671101,71471020,51839002the Natural Science Foundation of Inner Mongolia under Grant No.2017MS0108+4 种基金Hunan Provincial Natural Science Foundation of China under Grant No.2016JJ2061the Scientific Research Fund of Hunan Provincial Education Department under Grant No.18A325the Construct Program of the Key Discipline in Hunan Province under Grant No.201176the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province under Grant No.2014207Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering of Changsha University of Science and Technology under Grant No.018MMAEZD191
文摘In this paper, we study the higher dimensional nonlinear Rossby waves under the generalized beta effect.Using methods of the multiple scales and weak nonlinear perturbation expansions [Q. S. Liu, et al., Phys. Lett. A383(2019) 514], we derive a new(2 + 1)-dimensional generalized Boussinesq equation from the barotropic potential vorticity equation. Based on bifurcation theory of planar dynamical systems and the qualitative theory of ordinary differential equations, the dynamical analysis and exact traveling wave solutions of the new generalized Boussinesq equation are obtained. Moreover, we provide the numerical simulations of these exact solutions under some conditions of all parameters. The numerical results show that these traveling wave solutions are all the Rossby solitary waves.
基金Supported by the NNSF of China(60464001) Guangxi Science Foundation(0575092).
文摘In this paper, the generalized Dodd-Bullough-Mikhailov equation is studied. The existence of periodic wave and unbounded wave solutions is proved by using the method of bifurcation theory of dynamical systems. Under different parametric conditions, various sufficient conditions to guarantee the existence of the above solutions are given.Some exact explicit parametric representations of the above travelling solutions are obtained.
基金Supported by the National Natural Science Foundation of China under Grant No. 10974160the Scientific Research Foundation of the Education Department of Sichuan Province of China under Grant No. 10ZA004
文摘In this paper,the generalized Boussinesq wave equation u tt-uxx+a(um) xx+buxxxx=0 is investigated by using the bifurcation theory and the method of phase portraits analysis.Under the different parameter conditions,the exact explicit parametric representations for solitary wave solutions and periodic wave solutions are obtained.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11134011 and 11374322)the Foresight Research Project,Institute of Acoustics,Chinese Academy of Sciences
文摘Tool waves, also named collar waves, propagating along the drill collars in acoustic logging while drilling （ALWD）, strongly interfere with the needed P- and S-waves of a penetrated formation, which is a key issue in picking up formation P- and S-wave velocities. Previous studies on physical insulation for the collar waves designed on the collar between the source and the receiver sections did not bring to a satisfactory solution. In this paper, we investigate the propagation features of collar waves in different models. It is confirmed that there exists an indirect collar wave in the synthetic full waves due to the coupling between the drill collar and the borehole, even there is a perfect isolator between the source and the receiver. The direct collar waves propagating all along the tool and the indirect ones produced by echoes from the borehole wall are summarized as the generalized collar waves. Further analyses show that the indirect collar waves could be relatively strong in the full wave data. This is why the collar waves cannot be eliminated with satisfactory effect in many cases by designing the physical isolators carved on the tool.
