Direct drive servovalves are mostly restricted to low flow rate and low bandwidth applications due to the considerable flow forces.Current studies mainly focus on enhancing the driving force,which in turn is limited t...Direct drive servovalves are mostly restricted to low flow rate and low bandwidth applications due to the considerable flow forces.Current studies mainly focus on enhancing the driving force,which in turn is limited to the development of the magnetic material.Aiming at reducing the flow forces,a novel rotary direct drive servovalve（RDDV）is introduced in this paper.This RDDV servovalve is designed in a rotating structure and its axially symmetric spool rotates within a certain angle range in the valve chamber.The servovalve orifices are formed by the matching between the square wave shaped land on the spool and the rectangular ports on the sleeve.In order to study the RDDV servovalve performance,flow rate model and mechanical model are established,wherein flow rates and flow induced torques at different spool rotation angles or spool radiuses are obtained.The model analysis shows that the driving torque can be alleviated due to the proposed valve structure.Computational fluid dynamics（CFD）analysis using ANSYS/FLUENT is applied to evaluate and validate the theoretical analysis.In addition,experiments on the flow rate and the mechanical characteristic of the RDDV servovalve are carried out.Both simulation and experimental results conform to the results of the theoretical model analysis,which proves that this novel and innovative structure for direct drive servovalves can reduce the flow force on the spool and improve valve frequency response characteristics.This research proposes a novel rotary direct drive servovalve,which can reduce the flow forces effectively.展开更多
Along with laser-indirect(X-ray)-drive and magnetic-drive target concepts,laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion.In the United States,a national program...Along with laser-indirect(X-ray)-drive and magnetic-drive target concepts,laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion.In the United States,a national program has been established to demonstrate and understand the physics of laser direct drive.The program utilizes the Omega Laser Facility to conduct implosion and coupling physics at the nominally 30-kJ scale and lasereplasma interaction and coupling physics at the MJ scale at the National Ignition Facility.This article will discuss the motivation and challenges for laser direct drive and the broad-based program presently underway in the United States.展开更多
Optimum laser configurations are presented to achieve high illumination uniformity with directly driven inertial confinement fusion targets.Assuming axisymmetric absorption pattern of individual laser beams,theoretica...Optimum laser configurations are presented to achieve high illumination uniformity with directly driven inertial confinement fusion targets.Assuming axisymmetric absorption pattern of individual laser beams,theoretical models are reviewed in terms of the number of laser beams,system imperfection,and laser beam patterns.Utilizing a self-organizing system of charged particles on a sphere,a simple numerical model is provided to give an optimal configuration for an arbitrary number of laser beams.As a result,such new configurations as“M48”and“M60”are found to show substantially higher illumination uniformity than any other existing direct drive systems.A new polar direct-drive scheme is proposed with the laser axes keeping off the target center,which can be applied to laser configurations designed for indirectly driven inertial fusion.展开更多
The direct drive electro-hydraulic servo system is a new approach hydraulic system. It is much smaller and easier controlled than traditional systems and is a perfect energy saver. This paper will briefly introduce th...The direct drive electro-hydraulic servo system is a new approach hydraulic system. It is much smaller and easier controlled than traditional systems and is a perfect energy saver. This paper will briefly introduce the popular nonlinearities in the electro-hydraulic system and analyse the effect of nonlinearities in direct drive electro-hydraulic position servo system by means of simulation research. Some valuable conclusions are given.展开更多
A direct drive actuator （DDA） with direct drive valves （DDVs） as the control device is an ideal solution for a flight actuation system. This paper presents a novel triple-redundant voice coil motor （TRVCM） used ...A direct drive actuator （DDA） with direct drive valves （DDVs） as the control device is an ideal solution for a flight actuation system. This paper presents a novel triple-redundant voice coil motor （TRVCM） used for redundant DDVs. The TRVCM features electrical/mechanical hybrid triple-redundancy by securing three stators along with three moving coils in the same frame. A permanent magnet （PM） Halbach array is employed in each redundant VCM to simplify the system structure. A back-to-back design between neighborly redundancies is adopted to decouple the magnetic flux linkage. The particle swarm optimization （PSO） method is implemented to optimize design parameters based on the analytical magnetic circuit model. The optimization objective function is defined as the acceleration capacity of the motor to achieve high dynamic performance. The optimal geometric parameters are verified with 3D magnetic field finite element analysis （FEA）. A research prototype has been developed for experimental purpose. The experimental results of magnetic field density and force output show that the proposed TRVCM has great potential of applications in DDA systems.展开更多
The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In o...The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.展开更多
A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems,and it has the advantages of high neutron yield,ultrashort fusion time,micro fusion zone,isotropic and...A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems,and it has the advantages of high neutron yield,ultrashort fusion time,micro fusion zone,isotropic and monoenergetic neutron.Some analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser,whereas they are imperfect for a 0.35 μm laser implosion experiment.When using the 0.35 μm laser,the shell is ablated and accelerated to high implosion velocity governed by Newton’s law,ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target.The new analytical model scales bang time,ion temperature and neutron yield for large variations in laser power,target radius,shell thickness,and fuel pressure.The predicted results of the analytical model are in agreement with experimental data on the ShenguangIII prototype laser facility,100 kJ laser facility,Omega,and NIF,it demonstrates that the analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.展开更多
At this exhibition,as global expert in jacquard weaving solutions,Jiangsu S&S Intelligent Science And Technology Co.,Ltd.focuses on launching the SLX cam series jacquard machines.This equipment adopts servo direct...At this exhibition,as global expert in jacquard weaving solutions,Jiangsu S&S Intelligent Science And Technology Co.,Ltd.focuses on launching the SLX cam series jacquard machines.This equipment adopts servo direct-drive technology,which can reduce energy consumption by over 20%compared with traditional motor systems,and achieves highprecision control,efficient energy utilization,intelligent control.Precision process design The SLX cam jacquard machine adopts optimized shedding cam curve,featuring long effective shedding time and more stable operation.The low-center-of-gravity design minimizes the vibration and noise of the machine frame,while the camshaft box body formed by one-time processing ensures extremely high mounting accuracy of the conjugate cam.The equipment adopts a fully sealed design,which has good dust-proof effect and attractive appearance.The easily adjustable sensor disc assembly facilitates maintenance.These design details reflect S&S's pursuit of exquisite product quality.展开更多
Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show ...Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show that collective SRS in the plasma produced by ablating a polyimide film is detected for the ID beams,but is suppressed by adding a toe before the main pulse of the ID beams.The toe also strongly influences SRS of both the ID and DD beams excited in the plasma generated in the hohlraum.When a toe is used,the SRS spectra of the DD beams show that SRS tends to be excited in lower plasma density,which will result in a lower risk of super-hot electrons.Measurements of hot electrons support this conclusion.This research will help us produce a better pulse design for this new ignition path.展开更多
In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instabi...In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instability,with undesirable effects.However,the evolution of this instability remains insufficiently studied,and the effects of high-Z dopant on this instability remain unclear.In this paper,we develop a theoretical model to calculate the feedout seeds and describe this instability.Our theory suggests that the feedout seeds are determined by the ablation pressure and the adiabatic index,while the subsequent growth depends mainly on the ablation velocity.Two-dimensional radiation hydrodynamic simulations confirm our theory.It is shown that targets with high-Z dopant in the outer ablator exhibit more severe feedout seeds,because of their higher ionization compared with undoped targets.The X-ray pre-ablation in high-Z doped targets significantly suppresses subsequent growth,leading to suppression of short-wavelength perturbations.However,for long-wavelength perturbations,this suppression is weakened,resulting in increased instability in high-Z doped targets.The results are helpful for understanding the innerinterface-initiated instability and the influence of high-Z dopant on it,providing valuable insights for target design and instability control in ICF.展开更多
Linear switch reluctance machine(LSRM)has been tried to act as an alternative generator for direct drive linear wave energy converter(WEC).Many researchers have proposed new topologies of LSRM to improve the power den...Linear switch reluctance machine(LSRM)has been tried to act as an alternative generator for direct drive linear wave energy converter(WEC).Many researchers have proposed new topologies of LSRM to improve the power density,efficiency and reliability.However,the control methods for LSRM applied in direct drive WEC have been paid little attention,especially control methods considering the wave energy generator operating characteristics.In this paper,according to the generator control requirements of the direct drive WEC,force control algorithm for LSRM operating in four quadrants without a speed closed loop is put forward.The force ripple of LSRM is suppressed using force sharing function method.The four-quadrant control is easy to realize requiring only phase currents information.Simulation results validate the proposed method and indicate that LSRM is able to be used as the generator for direct drive WEC.展开更多
Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping unit...Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.展开更多
A new-style direct drive motor with double-stator structure is proposed. The structure and principle of the permanent-magnet (PM) brushless motor are discussed. On the basis of numerical calculation, the cogging torqu...A new-style direct drive motor with double-stator structure is proposed. The structure and principle of the permanent-magnet (PM) brushless motor are discussed. On the basis of numerical calculation, the cogging torque waveforms of the prototype motor when staggering two stators are analyzed. The method that can reduce torque ripple making use of the structure features of this motor is investigated. The results of numerical calculation and experiment indicate that designing motor with this kind of structure is a good scheme for increasing the power density.展开更多
There has been some good news, and some bad news in the controlled fusion community recently. The good news is that the Lawrence Livermore National Laboratory (LLNL) has recently produced a burning plasma. It succeede...There has been some good news, and some bad news in the controlled fusion community recently. The good news is that the Lawrence Livermore National Laboratory (LLNL) has recently produced a burning plasma. It succeeded on several of its shots where ~1.5 - 2 megajoules from its laser (National Ignition Facility, or NIF) has generated ~1.3 - 3 megajoules of fusion products. The highest ratio of fusion energy to laser energy it achieved, defined as its Q, was 1.5 at the time of this writing. While LLNL is sponsored by nuclear stockpile stewardship, this author sees a likely path from their result to fusion for energy for the world, a path using a very different laser and a very different target configuration. The bad news is that the International Tokamak Experimental Reactor (ITER) has continued to stumble on more and more delays and cost overruns, as its capital cost has mushroomed from ~$5 billion to ~ $25 B. This paper argues that the American fusion effort, for energy for the civilian economy, should switch its emphasis not only from magnetic fusion to inertial fusion but should also take much more seriously fusion breeding. Over the next few decades, the world might well be setting up more and more thermal nuclear reactors, and these might need fuel which only fusion breeders can supply. In other words, fusion should begin to color outside the lines.展开更多
One of the requirements for modem production machine is versatility and easy reconfiguration to produce new products. The production machines use fixed gearing and mechanical cams in history. The cams were used for sp...One of the requirements for modem production machine is versatility and easy reconfiguration to produce new products. The production machines use fixed gearing and mechanical cams in history. The cams were used for specific stokes and cam switches were used for commissioning of technological process. This solution has disadvantages in lower production speed and no flexibility of production. This article summaries practical steps for machine modernization and highlight practical problems in modernization of older production machine. The electronic cam with direct linear drive was used for traversal motion with high peak acceleration. This paper discusses cam stoke curve design, redesign and fitting.展开更多
Dynamic characteristics of large permanent magnet direct‐drive generators(PMDGs)considering electromagnetic–structural coupling effects are analyzed in this study.Using the conformal mapping method,the scalar magnet...Dynamic characteristics of large permanent magnet direct‐drive generators(PMDGs)considering electromagnetic–structural coupling effects are analyzed in this study.Using the conformal mapping method,the scalar magnetic potential of the air gap magnetic field considering the slot effect is calculated.On the basis of the discrete current element and magnetic equivalent circuit model,the local magnetic saturation effect of the stator and rotor is quantitatively simulated and the air gap magnetic field intensity distribution is obtained via numerical simulation.A series of uniformly distributed equivalent electromagnetic springs are introduced to develop an electromagnetic–structural coupling finite element PMDG model.The proposed air gap field analysis method is verified by the finite element analysis results.On the basis of the test platform for the Goldwind 1.5MW PMDG,both modal and dynamic response tests for the stator/rotor coupling system are conducted,and the results are compared with the natural frequencies,mode shapes,and vibration responses obtained using the numerical model.The effects of the air gap length and rotor speed on the natural frequencies of the coupling system are analyzed.The proposed model has the potential to accurately evaluate the PMDG vibration energy,avoiding resonance points,and maintaining stable operations of the unit.展开更多
Laser-driven inertial confinement fusion(ICF)diagnostics play a crucial role in understanding the complex physical processes governing ICF and enabling ignition.During the ICF process,the interaction between the high-...Laser-driven inertial confinement fusion(ICF)diagnostics play a crucial role in understanding the complex physical processes governing ICF and enabling ignition.During the ICF process,the interaction between the high-power laser and ablation material leads to the formation of a plasma critical surface,which reflects a significant portion of the driving laser,reducing the efficiency of laser energy conversion into implosive kinetic energy.Effective diagnostic methods for the critical surface remain elusive.In this work,we propose a novel optical diagnostic approach to investigate the plasma critical surface.This method has been experimentally validated,providing new insights into the critical surface morphology and dynamics.This advancement represents a significant step forward in ICF diagnostic capabilities,with the potential to inform strategies for enhancing the uniformity of the driving laser and target surface,ultimately improving the efficiency of converting laser energy into implosion kinetic energy and enabling ignition.展开更多
A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented...A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented based on our previous research. The entire press control system is constructed to realize various flexible forming processes. The control system scheme is determined in accordance with the mathematical model of PPMLM, and active disturbance rejection control is implemented in the servo controller. Field-circuit coupling simulation is applied to estimate the system’s performance. Then, a press prototype with 6 kN nominal force is fabricated, and the hardware platform of the control system is constructed for experimental study. Punch strokes with 0.06 m displacement are implemented at trapezoidal speeds of 0.1 and 0.2 m/s;the dynamic position tracking errors are less than 0.45 and 0.82 mm, respectively. Afterward, continuous reciprocating strokes are performed, and the positioning errors at the bottom dead center are less than 0.015 mm. Complex pulse trajectories are also achieved. The proposed PPMLM drive press exhibits a fast dynamic response and favorable tracking precision and is suitable for various forming processes.展开更多
Energy conservation and emissions reduction have become increasingly significant for automobiles due to the severity of the current energy situation.Hybrid electric vehicle(HEV)technology is one of the most promising ...Energy conservation and emissions reduction have become increasingly significant for automobiles due to the severity of the current energy situation.Hybrid electric vehicle(HEV)technology is one of the most promising solutions.This study investigated the total efficiency of a HEV powertrain.To improve the total efficiency,the engine should be regulated to work at its highest efficiency and drive the wheels directly as much as possible.To accomplish this,we developed an energy management strategy based on the direct drive area(DDA)of the engine’s efficiency map.Several typical HEV models were built to compare the fuel consumption using DDA and rule-based strategies.Furthermore,the function of the HEV transmission system with DDA was considered.The transmission in a HEV should regulate the engine to work at its highest efficiency as much as possible,which is rather different than the regulation in an internal combustion engine vehicle.The functional change may lead to transmission systems with fewer gears but optimal gear ratios.If this trend is realized,the manufacturing cost of HEVs could be largely reduced.展开更多
Due to the large torque density of magnetic gears(MGs),magnetic-geared permanent magnet machines(MGPMs)have become promising competitors in the family of direct-drive machines.According to the deployment of armature s...Due to the large torque density of magnetic gears(MGs),magnetic-geared permanent magnet machines(MGPMs)have become promising competitors in the family of direct-drive machines.According to the deployment of armature stators,MGPMs can be generally classified into three types,viz.,MGPM with inner armature stator(MGPM-IAS),MGPM with outer armature stator(MGPM-OAS),and MGPM with sandwiched armature stator(MGPM-SAS).Our investigation finds out that the MGPM-SAS can achieve parallel-path power flows better than the MGPM-OAS,while the MGPM-IAS is with serial power flow paths.Therefore,the torque capability of MGPM-IAS is limited by the torque transmission capability of its integrated MG.However,the MGPM-SAS has the possibility to offer even higher output torque than its integrated MG.This paper focuses on the MGPM-SAS.And three typical MGPMs and their power flow paths are introduced;the interaction of electromagnetic fields in MGPM-SAS is analyzed;simulation calculation and experimental verification are conducted to demonstrate the validity of the theoretical analysis.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51375363)Xi’an Municipal Science and Technology Planning Project of China(Grant No.CX12504)Guangdong Provincial Key Technology Project on Emerging Industries of Strategic Importance of China(Grant No.2012A090100010)
文摘Direct drive servovalves are mostly restricted to low flow rate and low bandwidth applications due to the considerable flow forces.Current studies mainly focus on enhancing the driving force,which in turn is limited to the development of the magnetic material.Aiming at reducing the flow forces,a novel rotary direct drive servovalve（RDDV）is introduced in this paper.This RDDV servovalve is designed in a rotating structure and its axially symmetric spool rotates within a certain angle range in the valve chamber.The servovalve orifices are formed by the matching between the square wave shaped land on the spool and the rectangular ports on the sleeve.In order to study the RDDV servovalve performance,flow rate model and mechanical model are established,wherein flow rates and flow induced torques at different spool rotation angles or spool radiuses are obtained.The model analysis shows that the driving torque can be alleviated due to the proposed valve structure.Computational fluid dynamics（CFD）analysis using ANSYS/FLUENT is applied to evaluate and validate the theoretical analysis.In addition,experiments on the flow rate and the mechanical characteristic of the RDDV servovalve are carried out.Both simulation and experimental results conform to the results of the theoretical model analysis,which proves that this novel and innovative structure for direct drive servovalves can reduce the flow force on the spool and improve valve frequency response characteristics.This research proposes a novel rotary direct drive servovalve,which can reduce the flow forces effectively.
文摘Along with laser-indirect(X-ray)-drive and magnetic-drive target concepts,laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion.In the United States,a national program has been established to demonstrate and understand the physics of laser direct drive.The program utilizes the Omega Laser Facility to conduct implosion and coupling physics at the nominally 30-kJ scale and lasereplasma interaction and coupling physics at the MJ scale at the National Ignition Facility.This article will discuss the motivation and challenges for laser direct drive and the broad-based program presently underway in the United States.
基金This work was supported by the Japan Society for the Promotion of Science(JSPS).
文摘Optimum laser configurations are presented to achieve high illumination uniformity with directly driven inertial confinement fusion targets.Assuming axisymmetric absorption pattern of individual laser beams,theoretical models are reviewed in terms of the number of laser beams,system imperfection,and laser beam patterns.Utilizing a self-organizing system of charged particles on a sphere,a simple numerical model is provided to give an optimal configuration for an arbitrary number of laser beams.As a result,such new configurations as“M48”and“M60”are found to show substantially higher illumination uniformity than any other existing direct drive systems.A new polar direct-drive scheme is proposed with the laser axes keeping off the target center,which can be applied to laser configurations designed for indirectly driven inertial fusion.
文摘The direct drive electro-hydraulic servo system is a new approach hydraulic system. It is much smaller and easier controlled than traditional systems and is a perfect energy saver. This paper will briefly introduce the popular nonlinearities in the electro-hydraulic system and analyse the effect of nonlinearities in direct drive electro-hydraulic position servo system by means of simulation research. Some valuable conclusions are given.
基金supported by National Science Foundation for Distinguished Young Scholars of China(No.50825502)National Natural Science Foundation of China(No.51105016)
文摘A direct drive actuator （DDA） with direct drive valves （DDVs） as the control device is an ideal solution for a flight actuation system. This paper presents a novel triple-redundant voice coil motor （TRVCM） used for redundant DDVs. The TRVCM features electrical/mechanical hybrid triple-redundancy by securing three stators along with three moving coils in the same frame. A permanent magnet （PM） Halbach array is employed in each redundant VCM to simplify the system structure. A back-to-back design between neighborly redundancies is adopted to decouple the magnetic flux linkage. The particle swarm optimization （PSO） method is implemented to optimize design parameters based on the analytical magnetic circuit model. The optimization objective function is defined as the acceleration capacity of the motor to achieve high dynamic performance. The optimal geometric parameters are verified with 3D magnetic field finite element analysis （FEA）. A research prototype has been developed for experimental purpose. The experimental results of magnetic field density and force output show that the proposed TRVCM has great potential of applications in DDA systems.
基金Supported by National Natural Science Foundation of China(Grant No.51335009)Major National Science and Technology Project of China(Grant No.2011ZX04001-011)
文摘The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775203 and 12075219)the Innovation and Development Fund of China Academy of Engineering Physics(Grant No.CX20210019)。
文摘A high-neutron yield platform imploded by a thin shell target is generally built to probe nuclear science problems,and it has the advantages of high neutron yield,ultrashort fusion time,micro fusion zone,isotropic and monoenergetic neutron.Some analytical models have been proposed to interpret exploding-pusher target implosion driven by a long wavelength laser,whereas they are imperfect for a 0.35 μm laser implosion experiment.When using the 0.35 μm laser,the shell is ablated and accelerated to high implosion velocity governed by Newton’s law,ablation acceleration and quasi-adiabatic compression models are suitable to explain the implosion of a laser direct-drive thin shell target.The new analytical model scales bang time,ion temperature and neutron yield for large variations in laser power,target radius,shell thickness,and fuel pressure.The predicted results of the analytical model are in agreement with experimental data on the ShenguangIII prototype laser facility,100 kJ laser facility,Omega,and NIF,it demonstrates that the analytical model benefits the understanding of experiment performance and optimizing the target design of high neutron yield implosion.
文摘At this exhibition,as global expert in jacquard weaving solutions,Jiangsu S&S Intelligent Science And Technology Co.,Ltd.focuses on launching the SLX cam series jacquard machines.This equipment adopts servo direct-drive technology,which can reduce energy consumption by over 20%compared with traditional motor systems,and achieves highprecision control,efficient energy utilization,intelligent control.Precision process design The SLX cam jacquard machine adopts optimized shedding cam curve,featuring long effective shedding time and more stable operation.The low-center-of-gravity design minimizes the vibration and noise of the machine frame,while the camshaft box body formed by one-time processing ensures extremely high mounting accuracy of the conjugate cam.The equipment adopts a fully sealed design,which has good dust-proof effect and attractive appearance.The easily adjustable sensor disc assembly facilitates maintenance.These design details reflect S&S's pursuit of exquisite product quality.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205274,12275251,12105270,12205272,12305262,and 12035002)the National Key Laboratory of Plasma Physics(Grant No.JCKYS2024212803)+2 种基金the Fund of the National Key Laboratory of Plasma Physics(Grant No.6142A04230103)the National Key R&D Program of China(Grant No.2023YFA1608400)the National Security Academic Fund(Grant No.U2430207).
文摘Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show that collective SRS in the plasma produced by ablating a polyimide film is detected for the ID beams,but is suppressed by adding a toe before the main pulse of the ID beams.The toe also strongly influences SRS of both the ID and DD beams excited in the plasma generated in the hohlraum.When a toe is used,the SRS spectra of the DD beams show that SRS tends to be excited in lower plasma density,which will result in a lower risk of super-hot electrons.Measurements of hot electrons support this conclusion.This research will help us produce a better pulse design for this new ignition path.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Science(Grant Nos.XDA25050200 and XDA25010100)the National Natural Science Foundation of China(Grant Nos.12175309,12475252,and 12275356)+2 种基金the Defense Industrial Technology Development Program(Grant No.JCKYS2023212807)the Natural Science Foundation of Hunan Province,China(Grant No.2025JJ20007)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(Grant No.CX20230005).
文摘In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instability,with undesirable effects.However,the evolution of this instability remains insufficiently studied,and the effects of high-Z dopant on this instability remain unclear.In this paper,we develop a theoretical model to calculate the feedout seeds and describe this instability.Our theory suggests that the feedout seeds are determined by the ablation pressure and the adiabatic index,while the subsequent growth depends mainly on the ablation velocity.Two-dimensional radiation hydrodynamic simulations confirm our theory.It is shown that targets with high-Z dopant in the outer ablator exhibit more severe feedout seeds,because of their higher ionization compared with undoped targets.The X-ray pre-ablation in high-Z doped targets significantly suppresses subsequent growth,leading to suppression of short-wavelength perturbations.However,for long-wavelength perturbations,this suppression is weakened,resulting in increased instability in high-Z doped targets.The results are helpful for understanding the innerinterface-initiated instability and the influence of high-Z dopant on it,providing valuable insights for target design and instability control in ICF.
基金This work was supported in part by the National Natural Science Foundation of China under Grant U1806224,61733010in part by the Guangdong Key Research and Development Program under Grant 2019B090917001.
文摘Linear switch reluctance machine(LSRM)has been tried to act as an alternative generator for direct drive linear wave energy converter(WEC).Many researchers have proposed new topologies of LSRM to improve the power density,efficiency and reliability.However,the control methods for LSRM applied in direct drive WEC have been paid little attention,especially control methods considering the wave energy generator operating characteristics.In this paper,according to the generator control requirements of the direct drive WEC,force control algorithm for LSRM operating in four quadrants without a speed closed loop is put forward.The force ripple of LSRM is suppressed using force sharing function method.The four-quadrant control is easy to realize requiring only phase currents information.Simulation results validate the proposed method and indicate that LSRM is able to be used as the generator for direct drive WEC.
文摘Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.
文摘A new-style direct drive motor with double-stator structure is proposed. The structure and principle of the permanent-magnet (PM) brushless motor are discussed. On the basis of numerical calculation, the cogging torque waveforms of the prototype motor when staggering two stators are analyzed. The method that can reduce torque ripple making use of the structure features of this motor is investigated. The results of numerical calculation and experiment indicate that designing motor with this kind of structure is a good scheme for increasing the power density.
文摘There has been some good news, and some bad news in the controlled fusion community recently. The good news is that the Lawrence Livermore National Laboratory (LLNL) has recently produced a burning plasma. It succeeded on several of its shots where ~1.5 - 2 megajoules from its laser (National Ignition Facility, or NIF) has generated ~1.3 - 3 megajoules of fusion products. The highest ratio of fusion energy to laser energy it achieved, defined as its Q, was 1.5 at the time of this writing. While LLNL is sponsored by nuclear stockpile stewardship, this author sees a likely path from their result to fusion for energy for the world, a path using a very different laser and a very different target configuration. The bad news is that the International Tokamak Experimental Reactor (ITER) has continued to stumble on more and more delays and cost overruns, as its capital cost has mushroomed from ~$5 billion to ~ $25 B. This paper argues that the American fusion effort, for energy for the civilian economy, should switch its emphasis not only from magnetic fusion to inertial fusion but should also take much more seriously fusion breeding. Over the next few decades, the world might well be setting up more and more thermal nuclear reactors, and these might need fuel which only fusion breeders can supply. In other words, fusion should begin to color outside the lines.
文摘One of the requirements for modem production machine is versatility and easy reconfiguration to produce new products. The production machines use fixed gearing and mechanical cams in history. The cams were used for specific stokes and cam switches were used for commissioning of technological process. This solution has disadvantages in lower production speed and no flexibility of production. This article summaries practical steps for machine modernization and highlight practical problems in modernization of older production machine. The electronic cam with direct linear drive was used for traversal motion with high peak acceleration. This paper discusses cam stoke curve design, redesign and fitting.
基金National Natural Science Foundation of China,Grant/Award Numbers:11872222,11902173State Key Laboratory of Tribology,Grant/Award Number:SKLT2021D11。
文摘Dynamic characteristics of large permanent magnet direct‐drive generators(PMDGs)considering electromagnetic–structural coupling effects are analyzed in this study.Using the conformal mapping method,the scalar magnetic potential of the air gap magnetic field considering the slot effect is calculated.On the basis of the discrete current element and magnetic equivalent circuit model,the local magnetic saturation effect of the stator and rotor is quantitatively simulated and the air gap magnetic field intensity distribution is obtained via numerical simulation.A series of uniformly distributed equivalent electromagnetic springs are introduced to develop an electromagnetic–structural coupling finite element PMDG model.The proposed air gap field analysis method is verified by the finite element analysis results.On the basis of the test platform for the Goldwind 1.5MW PMDG,both modal and dynamic response tests for the stator/rotor coupling system are conducted,and the results are compared with the natural frequencies,mode shapes,and vibration responses obtained using the numerical model.The effects of the air gap length and rotor speed on the natural frequencies of the coupling system are analyzed.The proposed model has the potential to accurately evaluate the PMDG vibration energy,avoiding resonance points,and maintaining stable operations of the unit.
基金supported by the National Natural Science Foundation of China(NSFC)(12074399,12204500 and 12004403)the Key Projects of Intergovernmental International Scientific and Technological Innovation Cooperation(2021YFE0116700)+1 种基金the Shanghai Natural Science Foundation(20ZR1464400)the Shanghai Sailing Program(22YF1455300).
文摘Laser-driven inertial confinement fusion(ICF)diagnostics play a crucial role in understanding the complex physical processes governing ICF and enabling ignition.During the ICF process,the interaction between the high-power laser and ablation material leads to the formation of a plasma critical surface,which reflects a significant portion of the driving laser,reducing the efficiency of laser energy conversion into implosive kinetic energy.Effective diagnostic methods for the critical surface remain elusive.In this work,we propose a novel optical diagnostic approach to investigate the plasma critical surface.This method has been experimentally validated,providing new insights into the critical surface morphology and dynamics.This advancement represents a significant step forward in ICF diagnostic capabilities,with the potential to inform strategies for enhancing the uniformity of the driving laser and target surface,ultimately improving the efficiency of converting laser energy into implosion kinetic energy and enabling ignition.
基金This research was financially supported by the National Natural Science Foundation of China(Grant No.51605363)China Postdoctoral Science Foundation(Grant No.2016M590922)Shaanxi Postdoctoral Research Project Funding.
文摘A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented based on our previous research. The entire press control system is constructed to realize various flexible forming processes. The control system scheme is determined in accordance with the mathematical model of PPMLM, and active disturbance rejection control is implemented in the servo controller. Field-circuit coupling simulation is applied to estimate the system’s performance. Then, a press prototype with 6 kN nominal force is fabricated, and the hardware platform of the control system is constructed for experimental study. Punch strokes with 0.06 m displacement are implemented at trapezoidal speeds of 0.1 and 0.2 m/s;the dynamic position tracking errors are less than 0.45 and 0.82 mm, respectively. Afterward, continuous reciprocating strokes are performed, and the positioning errors at the bottom dead center are less than 0.015 mm. Complex pulse trajectories are also achieved. The proposed PPMLM drive press exhibits a fast dynamic response and favorable tracking precision and is suitable for various forming processes.
基金the National Natural Science Foundation of China(71403142,71774100,71690241)Young Elite Scientists Sponsorship Program of the Chinese Association for Science andTechnology(YESS20160140)BeijingNatural Science Foundation(9162008).
文摘Energy conservation and emissions reduction have become increasingly significant for automobiles due to the severity of the current energy situation.Hybrid electric vehicle(HEV)technology is one of the most promising solutions.This study investigated the total efficiency of a HEV powertrain.To improve the total efficiency,the engine should be regulated to work at its highest efficiency and drive the wheels directly as much as possible.To accomplish this,we developed an energy management strategy based on the direct drive area(DDA)of the engine’s efficiency map.Several typical HEV models were built to compare the fuel consumption using DDA and rule-based strategies.Furthermore,the function of the HEV transmission system with DDA was considered.The transmission in a HEV should regulate the engine to work at its highest efficiency as much as possible,which is rather different than the regulation in an internal combustion engine vehicle.The functional change may lead to transmission systems with fewer gears but optimal gear ratios.If this trend is realized,the manufacturing cost of HEVs could be largely reduced.
基金Supported in part by the National Natural Science Foundation of China under Grant 51377158by the Natural Science Foundation of Guangdong Province under Project 2014A030306034,2015TQ01N332by the Science and Technology Innovation Committee of Shenzhen under Projects ZDSYS201604291912175,and JCYJ20150529152146473.
文摘Due to the large torque density of magnetic gears(MGs),magnetic-geared permanent magnet machines(MGPMs)have become promising competitors in the family of direct-drive machines.According to the deployment of armature stators,MGPMs can be generally classified into three types,viz.,MGPM with inner armature stator(MGPM-IAS),MGPM with outer armature stator(MGPM-OAS),and MGPM with sandwiched armature stator(MGPM-SAS).Our investigation finds out that the MGPM-SAS can achieve parallel-path power flows better than the MGPM-OAS,while the MGPM-IAS is with serial power flow paths.Therefore,the torque capability of MGPM-IAS is limited by the torque transmission capability of its integrated MG.However,the MGPM-SAS has the possibility to offer even higher output torque than its integrated MG.This paper focuses on the MGPM-SAS.And three typical MGPMs and their power flow paths are introduced;the interaction of electromagnetic fields in MGPM-SAS is analyzed;simulation calculation and experimental verification are conducted to demonstrate the validity of the theoretical analysis.
