We propose and demonstrate a synchronously pumped mode-locked Tm-doped fiber（TDF） laser without any extra mode-locking elements. Pumped by a 1.56 μm pulse fiber laser, the TDF laser generates 1.17 ps pulses with a ...We propose and demonstrate a synchronously pumped mode-locked Tm-doped fiber（TDF） laser without any extra mode-locking elements. Pumped by a 1.56 μm pulse fiber laser, the TDF laser generates 1.17 ps pulses with a spectral width of 9.7 nm and a repetition rate of 9.33 MHz. The emission wavelength is tunable along with the cavity length detuning in a wide range of 3 mm. The high detuning toleration is beneficial to achieve high temperature and vibration stability in all-fiber configuration lasers.展开更多
A novel high-energy picosecond optical parametric oscillator(OPO)was realized by placing an OPO in a secondharmonic(SH)cavity.In a proof-of-principle experiment,we demonstrated excellent burst energy of 45μJ for the ...A novel high-energy picosecond optical parametric oscillator(OPO)was realized by placing an OPO in a secondharmonic(SH)cavity.In a proof-of-principle experiment,we demonstrated excellent burst energy of 45μJ for the OPO signal at 900 nm that operates at a pulse repetition rate of 10 k Hz and a pulse width of 46.8 ps.The beam quality was measured as M_(x)^(2)=1.44 and M_(y)^(2)=1.40 in the orthogonal directions,corresponding to an average beam factor M^(2)=1.42.So far,this study is the first to investigate high-energy ps OPO synchronously pumped in a second-harmonic cavity.展开更多
With the continuous progress and development of current industrial civilization,energy crisis and envi-ronmental pollution are serious problems that threaten human beings need to be solved.Photocatalytic technolo-gies...With the continuous progress and development of current industrial civilization,energy crisis and envi-ronmental pollution are serious problems that threaten human beings need to be solved.Photocatalytic technolo-gies that can use clean solar light energy to manufacture clean H2 fuel and high value chemicals provide a feasibility to solve the above problem.However,traditional photo-catalytic water splitting mainly focused on the utilization of photogenerated electrons to produce H_(2) which leads to the waste of the holes.It is vital to develop photocatalysts capable of synchronously utilizing photogenerated elec-trons and holes for the future practical application.In this paper,the latest progress of photocatalytic system with collaborative photooxidation-reduction application has been summarized,and water splitting for H_(2) production combining different organic synchronous reaction process has been clarified.Finally,the prospect of photocatalysts capable of synchronously utilizing photogenerated elec-trons and holes are proposed.展开更多
A femtosecond optical parametric oscillator synchronously pumped by a Ti:Sapphire oscillator is reported.By the cavity length tuning,the signal wavelength is continuously tuned from 1000 to 1200 nm.The average output ...A femtosecond optical parametric oscillator synchronously pumped by a Ti:Sapphire oscillator is reported.By the cavity length tuning,the signal wavelength is continuously tuned from 1000 to 1200 nm.The average output power of 32 mW is obtained at 1053 nm.The pulse width is measured to be 342 fs by intensity autocorrelation method.In addition,we observed bichromatic emission during the cavity length tuning process.展开更多
As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impeda...As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.展开更多
This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,includin...This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.展开更多
BACKGROUND The incidence of malignant gastrointestinal(GI)tumors is increasing,and advancements in medical care have significantly improved patient survival rates.As a result,the number of cases involving multiple pri...BACKGROUND The incidence of malignant gastrointestinal(GI)tumors is increasing,and advancements in medical care have significantly improved patient survival rates.As a result,the number of cases involving multiple primary cancers(MPC)has also increased.The rarity of MPC and the absence of sensitive and specific dia-gnostic markers often lead to missed or incorrect diagnoses.It is,therefore,of vital importance to improve the vigilance of clinicians and the accurate diagnosis of this disease.Patients with GI malignancies face a higher relative risk of deve-loping additional primary malignant tumors compared to those with other systemic tumors.Vigilant monitoring and follow-up are crucial,especially for high-risk groups,which include older adults,men,those with addictions to alcohol and tobacco,those with a family history of tumors,and those who have undergone radiotherapy.CASE SUMMARY In this article,we report three cases of MPC,each involving malignant tumors of the GI tract as the initial primary carcinoma,offering insights that may aid in effectively managing similar cases.CONCLUSION Patients with GI malignancies face a higher MPC risk.Developing screening and follow-up protocols may enhance detection and treatment outcomes.展开更多
Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical...Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.展开更多
Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and ev...Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.展开更多
Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot ...Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.展开更多
A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 and1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166...A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 and1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166 m W and a repetition rate of 85 MHz. The pulse duration was measured to be 16.8 ps by assuming a sech2 pulse shape. The recorded autocorrelation trace showed frequency beating signals with an interval of 3.8 ps and a full width at half-maximum duration of 2 ps, corresponding to an ultrahigh beating frequency of about0.26 THz, which agrees well with the frequency difference of the emitted two spectral peaks. The results indicated that such a kind of dual-wavelength mode-locked Tm:YAlO3 laser could be potentially used for generating terahertz radiations.展开更多
This paper propose a comprehensive data-driven prediction framework based on machine learning methods to investigate the lag synchronization phenomenon in coupled chaotic systems,particularly in cases where accurate m...This paper propose a comprehensive data-driven prediction framework based on machine learning methods to investigate the lag synchronization phenomenon in coupled chaotic systems,particularly in cases where accurate mathematical models are challenging to establish or where system equations remain unknown.The Long Short-Term Memory(LSTM)neural network is trained using time series acquired from the desynchronization system states,subsequently predicting the lag synchronization transition.In the experiments,we focus on the Lorenz system with time-varying delayed coupling,studying the effects of coupling coefficients and time delays on lag synchronization,respectively.The results indicate that with appropriate training,the machine learning model can adeptly predict the lag synchronization occurrence and transition.This study not only enhances our comprehension of complex network synchronization behaviors but also underscores the potential and practical applications of machine learning in exploring nonlinear dynamic systems.展开更多
Dear Editor,This letter proposes a deep synchronization control(DSC) method to synchronize grid-forming converters with power grids. The method involves constructing a novel controller for grid-forming converters base...Dear Editor,This letter proposes a deep synchronization control(DSC) method to synchronize grid-forming converters with power grids. The method involves constructing a novel controller for grid-forming converters based on the stable deep dynamics model. To enhance the performance of the controller, the dynamics model is optimized within the deep reinforcement learning(DRL) framework. Simulation results verify that the proposed method can reduce frequency deviation and improve active power responses.展开更多
This article briefly reviews the topic of complex network synchronization,with its graph-theoretic criterion,showing that the homogeneous and symmetrical network structures are essential for optimal synchronization.Fu...This article briefly reviews the topic of complex network synchronization,with its graph-theoretic criterion,showing that the homogeneous and symmetrical network structures are essential for optimal synchronization.Furthermore,it briefly reviews the notion of higher-order network topologies and shows their promising potential in application to evaluating the optimality of network synchronizability.展开更多
The information exchange among satellites is crucial for the implementation of cluster satellite cooperative missions.However,achieving fast perception,rapid networking,and highprecision time synchronization among nod...The information exchange among satellites is crucial for the implementation of cluster satellite cooperative missions.However,achieving fast perception,rapid networking,and highprecision time synchronization among nodes without the support of the Global Navigation Satellite System(GNSS)and other prior information remains a formidable challenge to real-time wireless networks design.Therefore,a self-organizing network methodology based on multi-agent negotiation is proposed,which autonomously determines the master node through collaborative negotiation and competitive elections.On this basis,a real-time network protocol design is carried out and a high-precision time synchronization method with motion compensation is proposed.Simulation results demonstrate that the proposed method enables rapid networking with the capability of selfdiscovery,self-organization,and self-healing.For a cluster of 8 satellites,the networking time and the reorganization time are less than 4 s.The time synchronization accuracy exceeds 10-10s with motion compensation,demonstrating excellent real-time performance and stability.The research presented in this paper provides a valuable reference for the design and application of spacebased self-organizing networks for satellite cluster.展开更多
Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,th...Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,the Mathieu equation plays the most fundamental role for us to understand the stability and instability of a single ion.In this work,we investigate the dynamics of trapped ions with the Coulomb interaction based on the Hamiltonian equation.We show that the many-body interaction will not influence the phase diagram for instability.Then,the dynamics of this model in the large damping limit will also be analytically calculated using few trapped ions.Furthermore,we find that in the presence of modulation,synchronization dynamics can be observed,showing an exchange of velocities between distant ions on the left side and on the right side of the trap.These dynamics resemble that of the exchange of velocities in Newton's cradle for the collision of balls at the same time.These dynamics are independent of their initial conditions and the number of ions.As a unique feature of the interacting Mathieu equation,we hope this behavior,which leads to a quasi-periodic solution,can be measured in current experimental systems.Finally,we have also discussed the effect of anharmonic trapping potential,showing the desynchronization during the collision process.It is hoped that the dynamics in this many-body Mathieu equation with damping may find applications in quantum simulations.This model may also find interesting applications in dynamics systems as a pure mathematical problem,which may be beyond the results in the Floquet theorem.展开更多
Mechanical snap-through instability of bi-stable structures may find many practical applications such as state switching and energy transforming.Although there exist diverse bi-stable structures capable of snap-throug...Mechanical snap-through instability of bi-stable structures may find many practical applications such as state switching and energy transforming.Although there exist diverse bi-stable structures capable of snap-through instability,it is still difficult for a structure with high slenderness to undergo the axial snap-through instability with a large stroke.Here,an elastic structure with high slenderness is simply constructed by a finite number of identical,conventional bi-stable units with relatively low slenderness in series connection.For realizing the axial snap-through instability with a large stroke,common scissors mechanisms are further introduced as rigid constraints to guarantee the synchronous snap-through instability of these bi-stable units.The global feature of the large-stroke snap-through instability realized here is robust and even insusceptible to the local out-of-synchronization of individual units.The present design provides a simple and feasible way to achieve the large-stroke snap-through instability of slender structures,which is expected to be particularly useful for state switching and energy transforming in narrow spaces.展开更多
The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits...The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits effectiveness in complex vision processing tasks,necessitating supplementary visual information.However,to date,no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network(SNN).In this paper,we present a novel spike-based sensor with digitized pixels,which integrates the event detection structure with the pulse frequency modulation(PFM)circuit.This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information.Fabricated in 180 nm process,the proposed sensor achieves a resolution of 128×128,a maximum event rate of 960 Meps,a grayscale frame rate of 117.1 kfps,and a measured power consumption of 60.1 mW,which is suited for high-speed,low-latency,edge SNNbased vision computing systems.展开更多
This paper investigates modified fixed-time synchronization(FxTS)of complex networks(CNs)with time-varying delays based on continuous and discontinuous controllers.First,for the sake of making the settling time(ST)of ...This paper investigates modified fixed-time synchronization(FxTS)of complex networks(CNs)with time-varying delays based on continuous and discontinuous controllers.First,for the sake of making the settling time(ST)of FxTS is independent of the initial values and parameters of the CNs,a modified fixed-time(FxT)stability theorem is proposed,where the ST is determined by an arbitrary positive number given in advance.Then,continuous controller and discontinuous controller are designed to realize the modified FxTS target of CNs.In addition,based on the designed controllers,CNs can achieve synchronization at any given time,or even earlier.And control strategies effectively solve the problem of ST related to the parameters of CNs.Finally,an appropriate simulation example is conducted to examine the effectiveness of the designed control strategies.展开更多
Optical wireless(OW)communication systems face significant challenges such as signal attenuation due to atmospheric absorption,scattering,and noise from hardware components,which degrade detection sensitivity.To addre...Optical wireless(OW)communication systems face significant challenges such as signal attenuation due to atmospheric absorption,scattering,and noise from hardware components,which degrade detection sensitivity.To address these challenges,we propose a digital processing algorithm that combines finite impulse response filtering with dynamic synchronization based on pulse addition and subtraction.Unlike conventional methods,which typically rely solely on hardware optimization or basic thresholding techniques,the proposed approach integrates filtering and synchronization to improve weak signal detection and reduce noise-induced errors.The proposed algorithm was implemented and verified using a field-programmable gate array.Experiments conducted in an indoor OW communication environment demonstrate that the proposed algorithm significantly improves detection sensitivity by approximately 6 dB and 5 dB at communication rates of 3.5 Mbps and 5.0 Mbps,respectively.Specifically,under darkroom conditions and a bit error rate of 1×10^(-7),the detection sensitivity was improved from-38.56 dBm to-44.77 dBm at 3.5 Mbps and from-37.12 dBm to-42.29 dBm at 5 Mbps.The proposed algorithm is crucial for future capture and tracking of signals at large dispersion angles and in underwater and long-distance communication scenarios.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61675188 and 61875052the Open Fund of Key Laboratory Pulse Power Laser Technology of China under Grant No SKL2016KF03
文摘We propose and demonstrate a synchronously pumped mode-locked Tm-doped fiber（TDF） laser without any extra mode-locking elements. Pumped by a 1.56 μm pulse fiber laser, the TDF laser generates 1.17 ps pulses with a spectral width of 9.7 nm and a repetition rate of 9.33 MHz. The emission wavelength is tunable along with the cavity length detuning in a wide range of 3 mm. The high detuning toleration is beneficial to achieve high temperature and vibration stability in all-fiber configuration lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.62005215)。
文摘A novel high-energy picosecond optical parametric oscillator(OPO)was realized by placing an OPO in a secondharmonic(SH)cavity.In a proof-of-principle experiment,we demonstrated excellent burst energy of 45μJ for the OPO signal at 900 nm that operates at a pulse repetition rate of 10 k Hz and a pulse width of 46.8 ps.The beam quality was measured as M_(x)^(2)=1.44 and M_(y)^(2)=1.40 in the orthogonal directions,corresponding to an average beam factor M^(2)=1.42.So far,this study is the first to investigate high-energy ps OPO synchronously pumped in a second-harmonic cavity.
基金financially supported by the National Natural Science Foundation of China (Nos. 21975110 and 21972058)Taishan Youth Scholar Program of Shandong Province
文摘With the continuous progress and development of current industrial civilization,energy crisis and envi-ronmental pollution are serious problems that threaten human beings need to be solved.Photocatalytic technolo-gies that can use clean solar light energy to manufacture clean H2 fuel and high value chemicals provide a feasibility to solve the above problem.However,traditional photo-catalytic water splitting mainly focused on the utilization of photogenerated electrons to produce H_(2) which leads to the waste of the holes.It is vital to develop photocatalysts capable of synchronously utilizing photogenerated elec-trons and holes for the future practical application.In this paper,the latest progress of photocatalytic system with collaborative photooxidation-reduction application has been summarized,and water splitting for H_(2) production combining different organic synchronous reaction process has been clarified.Finally,the prospect of photocatalysts capable of synchronously utilizing photogenerated elec-trons and holes are proposed.
基金Supported by the National High Technology Program Research and Development Program of Chinathe National Natural Science Foundation of China (Grant Nos. 60490280 and 10804128)the National Basic Research Program of China (Grant No. 2007CB815104)
文摘A femtosecond optical parametric oscillator synchronously pumped by a Ti:Sapphire oscillator is reported.By the cavity length tuning,the signal wavelength is continuously tuned from 1000 to 1200 nm.The average output power of 32 mW is obtained at 1053 nm.The pulse width is measured to be 342 fs by intensity autocorrelation method.In addition,we observed bichromatic emission during the cavity length tuning process.
基金supported by theMajor Science and Technology Projects of China Southern Power Grid(Grant number CGYKJXM20210328).
文摘As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.
文摘This paper presents a high-fidelity lumpedparameter(LP)thermal model(HF-LPTM)for permanent magnet synchronous machines(PMSMs)in electric vehicle(EV)applications,where various cooling techniques are considered,including frame forced air/liquid cooling,oil jet cooling for endwinding,and rotor shaft cooling.To address the temperature misestimation in the LP thermal modelling due to assumptions of concentrated loss input and uniform heat flows,the developed HF-LPTM introduces two compensation thermal resistances for the winding and PM components,which are analytically derived from the multi-dimensional heat transfer equations and are robust against different load/thermal conditions.As validated by the finite element analysis method and experiments,the conventional LPTMs exhibit significant winding temperature deviations,while the proposed HF-LPTM can accurately predict both the midpoint and average temperatures.The developed HFLPTM is further used to assess the effectiveness of various cooling techniques under different scenarios,i.e.,steady-state thermal states under the rated load condition,and transient temperature profiles under city,freeway,and hybrid(city+freeway)driving cycles.Results indicate that no single cooling technique can maintain both winding and PM temperatures within safety limits.The combination of frame liquid cooling and oil jet cooling for end winding can sufficiently mitigate PMSM thermal stress in EV applications.
基金Supported by Gansu Provincial Natural Science Foundation,No.21JR1RA010In-Hospital Research Fund of Gansu Provincial Hospital,No.23GSSYD-5.
文摘BACKGROUND The incidence of malignant gastrointestinal(GI)tumors is increasing,and advancements in medical care have significantly improved patient survival rates.As a result,the number of cases involving multiple primary cancers(MPC)has also increased.The rarity of MPC and the absence of sensitive and specific dia-gnostic markers often lead to missed or incorrect diagnoses.It is,therefore,of vital importance to improve the vigilance of clinicians and the accurate diagnosis of this disease.Patients with GI malignancies face a higher relative risk of deve-loping additional primary malignant tumors compared to those with other systemic tumors.Vigilant monitoring and follow-up are crucial,especially for high-risk groups,which include older adults,men,those with addictions to alcohol and tobacco,those with a family history of tumors,and those who have undergone radiotherapy.CASE SUMMARY In this article,we report three cases of MPC,each involving malignant tumors of the GI tract as the initial primary carcinoma,offering insights that may aid in effectively managing similar cases.CONCLUSION Patients with GI malignancies face a higher MPC risk.Developing screening and follow-up protocols may enhance detection and treatment outcomes.
基金supported by the National Natural Science Foundation of China(Nos.52177059 and 52407064).
文摘Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.
基金Supported by the National Natural Science Foundation of China (11161027)。
文摘Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.
文摘Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61475088,61378022,61605100,and 61422511)the Key Research and Development Program of Shandong Province(No.2018GGX101006)+1 种基金the Shenzhen Science and Technology Research and Development Funds(No.JCYJ20180305163932273)the Young Scholars Program of Shandong University(No.2015WLJH38)
文摘A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 and1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166 m W and a repetition rate of 85 MHz. The pulse duration was measured to be 16.8 ps by assuming a sech2 pulse shape. The recorded autocorrelation trace showed frequency beating signals with an interval of 3.8 ps and a full width at half-maximum duration of 2 ps, corresponding to an ultrahigh beating frequency of about0.26 THz, which agrees well with the frequency difference of the emitted two spectral peaks. The results indicated that such a kind of dual-wavelength mode-locked Tm:YAlO3 laser could be potentially used for generating terahertz radiations.
基金supported by the National Natural Science Foundation of China(No.52174184)。
文摘This paper propose a comprehensive data-driven prediction framework based on machine learning methods to investigate the lag synchronization phenomenon in coupled chaotic systems,particularly in cases where accurate mathematical models are challenging to establish or where system equations remain unknown.The Long Short-Term Memory(LSTM)neural network is trained using time series acquired from the desynchronization system states,subsequently predicting the lag synchronization transition.In the experiments,we focus on the Lorenz system with time-varying delayed coupling,studying the effects of coupling coefficients and time delays on lag synchronization,respectively.The results indicate that with appropriate training,the machine learning model can adeptly predict the lag synchronization occurrence and transition.This study not only enhances our comprehension of complex network synchronization behaviors but also underscores the potential and practical applications of machine learning in exploring nonlinear dynamic systems.
基金supported in part by the National Natural Science Foundation of China(62033005,62273270)the Natural Science Foundation of Shaanxi Province(2023JC-XJ17)
文摘Dear Editor,This letter proposes a deep synchronization control(DSC) method to synchronize grid-forming converters with power grids. The method involves constructing a novel controller for grid-forming converters based on the stable deep dynamics model. To enhance the performance of the controller, the dynamics model is optimized within the deep reinforcement learning(DRL) framework. Simulation results verify that the proposed method can reduce frequency deviation and improve active power responses.
基金Hong Kong Research Grants Council under the GRF(9043664).
文摘This article briefly reviews the topic of complex network synchronization,with its graph-theoretic criterion,showing that the homogeneous and symmetrical network structures are essential for optimal synchronization.Furthermore,it briefly reviews the notion of higher-order network topologies and shows their promising potential in application to evaluating the optimality of network synchronizability.
基金supported by the National Natural Science Foundation of China(No.62401597)the Natural Science Foundation of Hunan Province,China(No.2024JJ6469)the Scientific Research Project of National University of Defense Technology,China(No.ZK22-02)。
文摘The information exchange among satellites is crucial for the implementation of cluster satellite cooperative missions.However,achieving fast perception,rapid networking,and highprecision time synchronization among nodes without the support of the Global Navigation Satellite System(GNSS)and other prior information remains a formidable challenge to real-time wireless networks design.Therefore,a self-organizing network methodology based on multi-agent negotiation is proposed,which autonomously determines the master node through collaborative negotiation and competitive elections.On this basis,a real-time network protocol design is carried out and a high-precision time synchronization method with motion compensation is proposed.Simulation results demonstrate that the proposed method enables rapid networking with the capability of selfdiscovery,self-organization,and self-healing.For a cluster of 8 satellites,the networking time and the reorganization time are less than 4 s.The time synchronization accuracy exceeds 10-10s with motion compensation,demonstrating excellent real-time performance and stability.The research presented in this paper provides a valuable reference for the design and application of spacebased self-organizing networks for satellite cluster.
基金supported by the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301200,2021ZD0303200,and 2021ZD0301500)the Alliance of International Science Organizations(ANSO)。
文摘Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,the Mathieu equation plays the most fundamental role for us to understand the stability and instability of a single ion.In this work,we investigate the dynamics of trapped ions with the Coulomb interaction based on the Hamiltonian equation.We show that the many-body interaction will not influence the phase diagram for instability.Then,the dynamics of this model in the large damping limit will also be analytically calculated using few trapped ions.Furthermore,we find that in the presence of modulation,synchronization dynamics can be observed,showing an exchange of velocities between distant ions on the left side and on the right side of the trap.These dynamics resemble that of the exchange of velocities in Newton's cradle for the collision of balls at the same time.These dynamics are independent of their initial conditions and the number of ions.As a unique feature of the interacting Mathieu equation,we hope this behavior,which leads to a quasi-periodic solution,can be measured in current experimental systems.Finally,we have also discussed the effect of anharmonic trapping potential,showing the desynchronization during the collision process.It is hoped that the dynamics in this many-body Mathieu equation with damping may find applications in quantum simulations.This model may also find interesting applications in dynamics systems as a pure mathematical problem,which may be beyond the results in the Floquet theorem.
基金supported by the National Natural Science Foundation of China(Grant Nos.11972027,12472093,and 11772272)the New Interdisciplinary Cultivation Fund of Southwest Jiaotong University(Grant No.2682022JX001)+1 种基金the Frontier Science and Technology Cultivation Project of Southwest Jiaotong University(Grant No.2682022KJ048)the Laboratory of Flexible Electronics Technology at Tsinghua University.
文摘Mechanical snap-through instability of bi-stable structures may find many practical applications such as state switching and energy transforming.Although there exist diverse bi-stable structures capable of snap-through instability,it is still difficult for a structure with high slenderness to undergo the axial snap-through instability with a large stroke.Here,an elastic structure with high slenderness is simply constructed by a finite number of identical,conventional bi-stable units with relatively low slenderness in series connection.For realizing the axial snap-through instability with a large stroke,common scissors mechanisms are further introduced as rigid constraints to guarantee the synchronous snap-through instability of these bi-stable units.The global feature of the large-stroke snap-through instability realized here is robust and even insusceptible to the local out-of-synchronization of individual units.The present design provides a simple and feasible way to achieve the large-stroke snap-through instability of slender structures,which is expected to be particularly useful for state switching and energy transforming in narrow spaces.
基金supported in part by the National Key Research and Development Program of China(Grant No.2022YFB2804401)the National Natural Science Foundation of China(Grant Nos.62334008,62134004,62404218)+1 种基金the Beijing Natural Science Foundation(Grant No.Z220005)Chinese Academy of Sciences(Grant No.ZDBS-LY-JSC008).
文摘The event-based vision sensor(EVS),which can generate efficient spiking data streams by exclusively detecting motion,exemplifies neuromorphic vision methodologies.Generally,its inherent lack of texture features limits effectiveness in complex vision processing tasks,necessitating supplementary visual information.However,to date,no event-based hybrid vision solution has been developed that preserves the characteristics of complete spike data streams to support synchronous computation architectures based on spiking neural network(SNN).In this paper,we present a novel spike-based sensor with digitized pixels,which integrates the event detection structure with the pulse frequency modulation(PFM)circuit.This design enables the simultaneous output of spiking data that encodes both temporal changes and texture information.Fabricated in 180 nm process,the proposed sensor achieves a resolution of 128×128,a maximum event rate of 960 Meps,a grayscale frame rate of 117.1 kfps,and a measured power consumption of 60.1 mW,which is suited for high-speed,low-latency,edge SNNbased vision computing systems.
基金Supported by the National Natural Science Foundation of China(62476082)。
文摘This paper investigates modified fixed-time synchronization(FxTS)of complex networks(CNs)with time-varying delays based on continuous and discontinuous controllers.First,for the sake of making the settling time(ST)of FxTS is independent of the initial values and parameters of the CNs,a modified fixed-time(FxT)stability theorem is proposed,where the ST is determined by an arbitrary positive number given in advance.Then,continuous controller and discontinuous controller are designed to realize the modified FxTS target of CNs.In addition,based on the designed controllers,CNs can achieve synchronization at any given time,or even earlier.And control strategies effectively solve the problem of ST related to the parameters of CNs.Finally,an appropriate simulation example is conducted to examine the effectiveness of the designed control strategies.
基金supported by National Key R&D Program of China under Grants No.2022YFB3902500,No.2022YFB2903402,and No.2021YFA0718804Natural Science Foundation of Jilin Province under Grant No.222621JC010297013Education Department of Jilin Province under Grant No.JJKH20220745KJ.
文摘Optical wireless(OW)communication systems face significant challenges such as signal attenuation due to atmospheric absorption,scattering,and noise from hardware components,which degrade detection sensitivity.To address these challenges,we propose a digital processing algorithm that combines finite impulse response filtering with dynamic synchronization based on pulse addition and subtraction.Unlike conventional methods,which typically rely solely on hardware optimization or basic thresholding techniques,the proposed approach integrates filtering and synchronization to improve weak signal detection and reduce noise-induced errors.The proposed algorithm was implemented and verified using a field-programmable gate array.Experiments conducted in an indoor OW communication environment demonstrate that the proposed algorithm significantly improves detection sensitivity by approximately 6 dB and 5 dB at communication rates of 3.5 Mbps and 5.0 Mbps,respectively.Specifically,under darkroom conditions and a bit error rate of 1×10^(-7),the detection sensitivity was improved from-38.56 dBm to-44.77 dBm at 3.5 Mbps and from-37.12 dBm to-42.29 dBm at 5 Mbps.The proposed algorithm is crucial for future capture and tracking of signals at large dispersion angles and in underwater and long-distance communication scenarios.
