Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state ...Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state of dynamic load and factor of dynamic load of thegearing, the changing situation of dynamic load and dynamic load factor vs some affecting factorssuch as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions areobtained: ①With the increasing in the values of gear width, the dynamic load factor appears slowdecreasing tendency in most region of gear width. ②When the accuracy grades of the gearing areimproved, the values of dynamic load factor decrease. ③The value of dynamic load factor appears adecreasing tendency with the increasing of value of helix angle at the same ratio of criticalrotational speed.展开更多
Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.T...Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.展开更多
To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to...To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to above system.In order to reduce leakage and aerodynamic force influence,a new type high-pressure solenoid valve was proposed.The simulation model which included electromagnetic model,aerodynamic force model was established by means of the nonlinear mathematic models.Using the software MATLAB/Simulink for simulation,the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation(PWM)input control signals.Results show that,first of all,the new type of high-pressure solenoid valve can meet the switch requirement.Secondly,the opening movement and closing movement of the spool lags the PWM rising signal,and the coil current fluctuates significantly during the movement of the spool.Lastly,on/off status of high-pressure valve cannot be represented by the duty cycle.This research can be referred in the design of the high-pressure solenoid valve..展开更多
Many difficult (often NP-complete) optimization problems can be solved efficiently on graphs of small tree-width with a given tree-decomposition.In this paper,it is discussed how to solve the minimum feedback vertex s...Many difficult (often NP-complete) optimization problems can be solved efficiently on graphs of small tree-width with a given tree-decomposition.In this paper,it is discussed how to solve the minimum feedback vertex set problem and the minimum vertex feedback edge set problem efficiently by using dynamic programming on a tree-decomposition.展开更多
This study aims to gain insight into the DNA-specific recognition mechanism of c-Myb transcription factor during the regulation of cell early differentiation and proliferation.Therefore,we chose the chicken myeloid ge...This study aims to gain insight into the DNA-specific recognition mechanism of c-Myb transcription factor during the regulation of cell early differentiation and proliferation.Therefore,we chose the chicken myeloid gene,mitochondrial import protein 1(mim-1),as a target to study the binding specificity between potential dual-Myb-binding sites.The c-Myb-binding site in mim-1 is a pseudo-palindromic sequence AACGGTT,which contains two AACNG consensuses.Simulation studies in different biological scenarios revealed that c-Myb binding with mim-1 in the forward strand(complex F)is more stable than that in the reverse strand(complex R).The principal component analysis(PCA)dynamics trajectory analyses suggested an opening motion of the recognition helices of R2 and R3(R2R3),resulting in the dissociation of DNA from c-Myb in complex R at 330 K,triggered by the reduced electrostatic potential on the surface of R2R3.Furthermore,the DNA confirmation and hydrogen-bond interaction analyses indicated that the major groove width of DNA increased in complex R,which affected on the hydrogenbond formation ability between R2R3 and DNA,and directly resulted in the dissociation of DNA from R2R3.The steered molecular dynamics(SMD)simulation studies also suggested that the electrostatic potential,major groove width,and hydrogen bonds made major contribution to the DNA-specific recognition.In vitro trials confirmed the simulation results that c-Myb specifically bound to mim-1 in the forward strand.This study indicates that the three-dimensional(3D)structure features play an important role in the DNA-specific recognition mechanism by c-Myb besides the AACNG consensuses,which is beneficial to understanding the cell early differentiation and proliferation regulated by c-Myb,as well as the prediction of novel c-Myb-binding motifs in tumorigenesis.展开更多
The millimeter wave(mm Wave)is a potential solution for high data rate communication due to its availability of large bandwidth.However,it is challenging to perform beam tracking in vehicular mm Wave communication sys...The millimeter wave(mm Wave)is a potential solution for high data rate communication due to its availability of large bandwidth.However,it is challenging to perform beam tracking in vehicular mm Wave communication systems due to high mobility and narrow beams.In this paper,an adaptive beam tracking algorithm is proposed to improve the network throughput performance while reducing the training signal overhead.In particular,based on the mobility prediction at base station(BS),a novel frame structure with dynamic bundled timeslot is designed.Moreover,an actor-critic reinforcement learning based algorithm is proposed to obtain the joint optimization of both beam width and the number of bundled timeslots,which makes the beam tracking adapt to the changing environment.Simulation results demonstrate that,compared with the traditional full scan and Kalman filter based beam tracking algorithms,our proposed algorithm can improve the time-averaged throughput by 11.34%and 24.86%respectively.With the newly designed frame structure,it also outperforms beam tracking with conventional frame structure,especially in scenarios with large range of vehicle speeds.展开更多
Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrad...Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrade the performance of the MMC. To improve the harmonic characteristic in the low modulation index, the carrier dynamic overlapping switching frequency optimal pulse width modulation(CDOSFOPWM) method is proposed for the MMC here. The whole modulation index region is divided into three regions: high modulation index region, middle modulation index region, and low modulation index region. The carrier amplitude, carrier overlap ratio, and frequency of triangular carriers are chosen dynamically according to the modulation index region of the modulation signals, to achieve the optimal harmonic characteristic in the whole modulation index region and maintain the switching loss. The number of on-state submodules(SMs) can be calculated by CDOSFOPWM, and the selection of SMs is performed by a reducing switching frequency voltage balancing algorithm. Finally, the proposed method is verified by simulation and experimental results.展开更多
基金This project is supported by Science and Technology Developing Foundation of Tianjin Higher Education (No.20030703).
文摘Based on theory of mechanical dynamics, meshing characteristic as well as thedynamic model of double circular arc helical gearing, an analysis approach and a computer programhave been developed for studying the state of dynamic load and factor of dynamic load of thegearing, the changing situation of dynamic load and dynamic load factor vs some affecting factorssuch as gear width, helix angle and accuracy grade etc are investigated. A series of conclusions areobtained: ①With the increasing in the values of gear width, the dynamic load factor appears slowdecreasing tendency in most region of gear width. ②When the accuracy grades of the gearing areimproved, the values of dynamic load factor decrease. ③The value of dynamic load factor appears adecreasing tendency with the increasing of value of helix angle at the same ratio of criticalrotational speed.
基金The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through Large Groups Project under grant number(RGP.2/111/43).
文摘Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.
基金The research work presented in this paper is financially supported by a grant(NJZZ18139)from the scientific research project of Universities in Inner Mongoliaa grant(2018BS05003)from the Natural Science Foundation of Inner Mongoliaa grant(2017QDL-B07)from Inner Mongolia University of Science and Technology Innovation Fund Project.
文摘To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to above system.In order to reduce leakage and aerodynamic force influence,a new type high-pressure solenoid valve was proposed.The simulation model which included electromagnetic model,aerodynamic force model was established by means of the nonlinear mathematic models.Using the software MATLAB/Simulink for simulation,the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation(PWM)input control signals.Results show that,first of all,the new type of high-pressure solenoid valve can meet the switch requirement.Secondly,the opening movement and closing movement of the spool lags the PWM rising signal,and the coil current fluctuates significantly during the movement of the spool.Lastly,on/off status of high-pressure valve cannot be represented by the duty cycle.This research can be referred in the design of the high-pressure solenoid valve..
基金Partially supported by the National Natural Science Foundation of China( 1 0 2 71 0 65
文摘Many difficult (often NP-complete) optimization problems can be solved efficiently on graphs of small tree-width with a given tree-decomposition.In this paper,it is discussed how to solve the minimum feedback vertex set problem and the minimum vertex feedback edge set problem efficiently by using dynamic programming on a tree-decomposition.
基金supported by the National Key Research and Development Program of China(Nos.2022YFC2402900 and 2022YFC2402901)the Fundamental Research Funds for the Central Universities(No.226-2022-00213)the Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(No.LHDMD23H300001).
文摘This study aims to gain insight into the DNA-specific recognition mechanism of c-Myb transcription factor during the regulation of cell early differentiation and proliferation.Therefore,we chose the chicken myeloid gene,mitochondrial import protein 1(mim-1),as a target to study the binding specificity between potential dual-Myb-binding sites.The c-Myb-binding site in mim-1 is a pseudo-palindromic sequence AACGGTT,which contains two AACNG consensuses.Simulation studies in different biological scenarios revealed that c-Myb binding with mim-1 in the forward strand(complex F)is more stable than that in the reverse strand(complex R).The principal component analysis(PCA)dynamics trajectory analyses suggested an opening motion of the recognition helices of R2 and R3(R2R3),resulting in the dissociation of DNA from c-Myb in complex R at 330 K,triggered by the reduced electrostatic potential on the surface of R2R3.Furthermore,the DNA confirmation and hydrogen-bond interaction analyses indicated that the major groove width of DNA increased in complex R,which affected on the hydrogenbond formation ability between R2R3 and DNA,and directly resulted in the dissociation of DNA from R2R3.The steered molecular dynamics(SMD)simulation studies also suggested that the electrostatic potential,major groove width,and hydrogen bonds made major contribution to the DNA-specific recognition.In vitro trials confirmed the simulation results that c-Myb specifically bound to mim-1 in the forward strand.This study indicates that the three-dimensional(3D)structure features play an important role in the DNA-specific recognition mechanism by c-Myb besides the AACNG consensuses,which is beneficial to understanding the cell early differentiation and proliferation regulated by c-Myb,as well as the prediction of novel c-Myb-binding motifs in tumorigenesis.
基金supported by the National Key R&D Program of China(2020YFB1807204)Beijing Natural Science Foundation(L212003)。
文摘The millimeter wave(mm Wave)is a potential solution for high data rate communication due to its availability of large bandwidth.However,it is challenging to perform beam tracking in vehicular mm Wave communication systems due to high mobility and narrow beams.In this paper,an adaptive beam tracking algorithm is proposed to improve the network throughput performance while reducing the training signal overhead.In particular,based on the mobility prediction at base station(BS),a novel frame structure with dynamic bundled timeslot is designed.Moreover,an actor-critic reinforcement learning based algorithm is proposed to obtain the joint optimization of both beam width and the number of bundled timeslots,which makes the beam tracking adapt to the changing environment.Simulation results demonstrate that,compared with the traditional full scan and Kalman filter based beam tracking algorithms,our proposed algorithm can improve the time-averaged throughput by 11.34%and 24.86%respectively.With the newly designed frame structure,it also outperforms beam tracking with conventional frame structure,especially in scenarios with large range of vehicle speeds.
基金supported by National Natural Science Foundation of China(No.51477045)
文摘Modular multilevel converters(MMCs) operate in the low modulation index region in many applications.However, when utilized at the low modulation index region, large harmonics appear in the output voltage, which degrade the performance of the MMC. To improve the harmonic characteristic in the low modulation index, the carrier dynamic overlapping switching frequency optimal pulse width modulation(CDOSFOPWM) method is proposed for the MMC here. The whole modulation index region is divided into three regions: high modulation index region, middle modulation index region, and low modulation index region. The carrier amplitude, carrier overlap ratio, and frequency of triangular carriers are chosen dynamically according to the modulation index region of the modulation signals, to achieve the optimal harmonic characteristic in the whole modulation index region and maintain the switching loss. The number of on-state submodules(SMs) can be calculated by CDOSFOPWM, and the selection of SMs is performed by a reducing switching frequency voltage balancing algorithm. Finally, the proposed method is verified by simulation and experimental results.
