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
Antibody-mediated rejection(AMR)represents a major challenge in kidney transplantation,significantly contributing to tissue injury and graft failure.AMR is primarily driven by donor-specific alloantibodies(DSAs),which...Antibody-mediated rejection(AMR)represents a major challenge in kidney transplantation,significantly contributing to tissue injury and graft failure.AMR is primarily driven by donor-specific alloantibodies(DSAs),which recognize and bind to specific target antigens present within the transplanted kidney tissue.Upon binding,these DSAs commonly initiate activation of the complement system within the graft.The activation of the complement cascade sets off a powerful inflammatory response characterized by the recruitment and activation of immune cells,endothelial damage,and subsequent tissue injury.This inflammation underlies many clinical and histological manifestations of AMR,making complement activation a critical player in the disease process.Advancements in our understanding of how complement pathways contribute to kidney graft injury have opened new avenues for therapeutic intervention.Recent research has facilitated the development and application of novel therapies specifically designed to inhibit complement activation.Such targeted complement-inhibitory strategies have shown promise in improving graft outcomes by inhibiting complement-mediated damage and extending graft survival.This review comprehensively discusses the critical role of complement activation in inducing kidney graft injury with a focus on its role in AMR.By elucidating the detailed mechanisms and contributions of complement pathways,the review seeks to enhance the understanding necessary for developing targeted therapeutic interventions to prevent or treat AMR effectively.展开更多
BACKGROUND The Luminex platform,where beads are coated with single human leukocyte antigens(HLA),detects HLA antibodies with higher sensitivity and specificity compared to complement-dependent cytotoxicity(CDC)assay a...BACKGROUND The Luminex platform,where beads are coated with single human leukocyte antigens(HLA),detects HLA antibodies with higher sensitivity and specificity compared to complement-dependent cytotoxicity(CDC)assay and flow crossmatch(FCXM).The clinical significance of donor-specific antibodies(DSAs)detected by this method is still under investigation.AIM To report the impact of low-level pretransplant DSAs detected by the Luminex platform on the rates of acute rejection(AR),allograft function,and long-term graft survival.METHODS This retrospective study was conducted at the Immunology Department of Sindh Institute of Urology and Transplantation,Karachi,Pakistan between January 2013 and December 2022.During this period 2714 patients were transplanted.Out of these patients 78(2.9%)patients had low-level DSAs detected by the Luminex flow beads method and were negative by CDC and FCXM with their donors.All recipients received ABO-compatible live-related kidney transplants.All patients had a minimum follow-up of 1 year.Graft rejection rates,graft function,and patient and graft survival were analyzed.The estimated glomerular filtration rate was calculated by the full CKD-EPI formula.RESULTS The mean age of all recipients was 29.57±10.11 years and 34.53±9.09 years for the donors.In 48(61.5%)patients,the cause of end-stage kidney disease was unknown.DSA against HLA class I was detected in 36(46.1%)patients,class II in 35(44.8%)patients,and both class I and II in 7(8.9%)patients.AR episodes were encountered in 8(10.3%)cases.Seven(87.5%)had T cell mediated rejection(type IA)and one acute antibody-mediated rejection.Antibody status was re-evaluated at the time of biopsy-proven ARs.Five(62.5%)patients lost their DSAs,while three(37.5%)had persistent DSAs.The mean estimated glomerular filtration rate at 1 year was 80.56±27.48 mL/min/1.73 m2 and at the last follow-up 73.41±28.80 mL/min/1.73 m2.The 1-year and 10-year patient and graft survival rates were 99%and 79%and 95%and 75%,respectively.During the follow-up period,10(12.8%)patients died,8 patients had a functioning graft,and 2 patients had failed grafts.Eight patients died due to cardiopulmonary arrest,and two died due to sepsis with failed grafts.CONCLUSION Patients with pretransplant low-level DSAs on Luminex without CDC and FCXM reactivity had good allograft outcomes at 1 year and 10 years as long as they are induced with biological agents and given potent maintenance immunosuppressants.展开更多
BACKGROUND Advancements in immunosuppressive therapies have improved graft survival by enhancing graft tolerance and preventing organ rejection.However,the risk of malignancy associated with prolonged immunosuppressio...BACKGROUND Advancements in immunosuppressive therapies have improved graft survival by enhancing graft tolerance and preventing organ rejection.However,the risk of malignancy associated with prolonged immunosuppression remains a concern,as it can adversely affect recipients’quality of life and survival.While the link be-tween immunosuppression and increased cancer risk is well-documented,the specific interactions between graft rejection and post-transplant malignancy(PTM)remain poorly understood.Addressing this knowledge gap is crucial for devising immunosuppressive strategies that balance rejection prevention with cancer risk reduction.AIM To investigate whether immunosuppression in PTM reduces rejection risk,while immune activation during rejection protects against malignancy.METHODS We analyzed data from the United Network for Organ Sharing’s Organ Procurewith no prior history of malignancy(in donors or recipients).Landmark analyses at 1,2,3,5,10,15,and 20 years post-transplant,Kaplan–Meier analyses,and time-dependent Cox proportional hazards regression models,each incorporating the temporal dimension of outcomes,assessed the association between rejection-induced graft failure(RGF)and PTM.Multivariate models were adjusted for clinical and immunological factors,including immunosuppression regimens.RESULTS The cohort included 579905 recipients(kidney:386878;liver:108390;heart:45046;lung:37643;pancreas:1948)with a mean follow-up of 7.3 years and a median age of 50.6±13.2 years.RGF was associated with a reduction in PTM risk across all time points[hazard ratio(HR)=0.07-0.20,P<0.001],even after excluding mortality cases.Kidney transplant recipients exhibited the most pronounced reduction(HR=0.22,P<0.001).Conversely,among recipients with PTM,RGF risk decreased across all time points up to 15 years after excluding mortality cases(HR=0.49–0.80,P<0.001).This risk reduction was observed in kidney,liver,heart,and lung transplants(HRs=0.90,0.21,0.21,and 0.18,respectively;P<0.001)but not in pancreas transplants.CONCLUSION RGF reduces PTM risk,particularly in kidney transplants,while PTM decreases RGF risk in kidney,liver,heart,and lung transplants.展开更多
Organ transplantation has long been recognized as an effective treatment for endstage organ failure,metabolic diseases,and malignant tumors.However,graft rejection caused by major histocompatibility complex mismatch r...Organ transplantation has long been recognized as an effective treatment for endstage organ failure,metabolic diseases,and malignant tumors.However,graft rejection caused by major histocompatibility complex mismatch remains a significant challenge.While modern immunosuppressants have made significant strides in reducing the incidence and risk of rejection,they have not been able to eliminate it completely.The intricate mechanisms underlying transplant rejection have been the subject of intense investigation by transplant immunologists.Among these factors,autophagy has emerged as a key player.Autophagy is an evolutionarily conserved mechanism in eukaryotic cells that mediates autophagocytosis and cellular protection.This process is regulated by autophagy-related genes and their encoded protein families,which maintain the material and energetic balance within cells.Additionally,autophagy has been reported to play crucial roles in the development,maturation,differentiation,and responses of immune cells.In the complex immune environment following transplantation,the role and mechanisms of autophagy are gradually being revealed.In this review,we aim to explore the current understanding of the role of autophagy in solid organ rejection after transplantation.Furthermore,we delve into the therapeutic advancements achieved by targeting autophagy involved in the rejection process.展开更多
BACKGROUND Malabsorptive bariatric surgery,including Roux-en-Y gastric bypass and duodenal switch,are known to be more metabolically effective than restrictive surgery.However,the permanent alteration of gastrointesti...BACKGROUND Malabsorptive bariatric surgery,including Roux-en-Y gastric bypass and duodenal switch,are known to be more metabolically effective than restrictive surgery.However,the permanent alteration of gastrointestinal anatomy from these operations has been shown to alter the kinetics of drug absorption and may make subsequent surgeries more technically challenging.AIM To evaluate perioperative liver transplant outcomes and rates of acute cellular rejection in recipients with prior malabsorptive bariatric surgery.METHODS Patients who underwent liver transplantation at a single institution between 2005-2024 with a history of malabsorptive bariatric surgery were identified.Matched controls were selected based on age,sex,listing model for end-stage liver disease(MELD),and primary liver diagnosis.RESULTS A total of 12 liver transplant patients with prior malabsorptive surgery and 25 controls were included.The mean age in the malabsorptive group was 50.5 years at the time of transplant and 92%were female.The mean MELD at the time of transplant was 27.6 and mean body mass index was 28.There were no significant differences in length of stay,post operative complications,or 1 year survival between the controls and malabsorptive patients.However,the malabsorptive group was significantly more likely to experience biopsy-proven and clinically treated acute cellular rejection than the controls(24%vs 66.7%,P=0.012),more frequent rejection episodes(0.28±0.53 vs 1.0±0.91,P=0.006),and earlier time to first rejection episode(P=0.002).CONCLUSION Previous malabsorptive bariatric surgery in liver transplant recipients did not increase the risk of perioperative complications or mortality but significantly increased the rate and frequency of acute cellular rejection.展开更多
BACKGROUND The pathophysiology behind gastroesophageal reflux disease and its association with poor outcomes after lung transplantation is incompletely understood.The physiologic impact of lung transplantation on pulm...BACKGROUND The pathophysiology behind gastroesophageal reflux disease and its association with poor outcomes after lung transplantation is incompletely understood.The physiologic impact of lung transplantation on pulmonary function,intrathoracic pressures,and vagal innervation may affect esophageal motility,bolus clearance and reflux risk.However,the effect of changes in esophageal function after lung transplantation on the risk of poor post-transplant outcomes remains unclear.AIM To evaluate the association between change in esophageal motility pre-/post-lung transplantation and rejection outcome.METHODS This was a retrospective cohort study of lung transplant recipients who underwent both pre-and post-transplant esophageal testing including high resolution manometry(HRM)at a tertiary center.Acute cellular rejection(ACR)was defined histologically per International Society for Heart and Lung Transplantation criteria.Univariate analyses were performed using student’s t-test,χ2 test,and Spearman’s correlation where appropriate.Multivariable time-to-event analysis using Cox proportional hazards model was applied.Subjects not meeting ACR outcome were censored at death or date of last clinic visit.RESULTS 55 subjects(65%men,mean age:61,median follow-up:840 days)were included,with 17 (31%) experiencing ACR. Increase in failed swallows correlated with lower baseline total lung capacity(TLC) (R = -0.32, P = 0.05) and decreased post-transplant esophageal bolus clearance (R = -0.45, P = 0.004). Onmultivariable analysis, post-transplant hypomotility independently predicted increased ACR (HR: 3.62, 95%CI:1.11-11.8;P = 0.03). Kaplan-Meier analysis demonstrated increased ACR for subjects with increased vs unchangedfailed swallows post-transplant (P = 0.048). On Cox regression, a 20% elevated risk of ACR was found for every10% increase in failed swallows, after controlling for confounders including reflux severityCONCLUSIONEsophageal hypomotility, specifically an increase in failed swallows on HRM, from pre- to post-lungtransplantation was independently associated with ACR. Additionally, lower baseline TLC correlated with increasein failed swallows, suggesting restrictive lung disease may be associated with post-transplant esophagealhypomotility. Lung transplantation may affect esophageal function and contribute to rejection outcomes. Routineesophageal function testing may help identify patients at higher risk for poor lung transplantation outcomes.展开更多
The study of Mecanum mobile robots typically assumes motion on planar surfaces,while the challenges posed by inclined terrains remain largely unexplored,leaving a significant gap in control applications for such scena...The study of Mecanum mobile robots typically assumes motion on planar surfaces,while the challenges posed by inclined terrains remain largely unexplored,leaving a significant gap in control applications for such scenarios.In this context,two critical issues emerge:the gravitational pull caused by adding a potential energy term in the robot dynamics,which drives the vehicle downhill,and several positioning errors due to vibrations and slippage of the Mecanum wheel.To address these challenges,this work presents an Active Disturbance Rejection Control(ADRC)-based framework designed to enable accurate tracking on inclined surfaces,despite the compounded effects of gravitational forces and slippage.Unlike conventional controllers,the proposed method requires minimal model knowledge while actively compensates for unknown dynamics and external disturbances in real time.A complete theoretical formulation is provided,supported by numerical simulations and comprehensive experimental validation.Results demonstrate that the ADRC structure significantly outperforms not only the traditional proportional-integral-derivative(PID)control but also a robust variant of PID combined with a Quasi-Sliding Mode control(PID-QSMC)strategy,achieving superior tracking.Notably,this study offers an important experimental validation of ADRC for Mecanum-wheeled robots operating on inclined surfaces.It contributes a practical and scalable solution to extend their operational capabilities beyond flat environments.展开更多
With the growing adoption of artificial intelligence algorithms and neural networks,online learning and adaptive methods for updating the bandwidth have become increasingly prevalent.However,the conditions required to...With the growing adoption of artificial intelligence algorithms and neural networks,online learning and adaptive methods for updating the bandwidth have become increasingly prevalent.However,the conditions required to ensure closed-loop stability when employing a time-varying bandwidth,as well as the supporting mathematical foundations,remain insufficiently studied.This paper investigates the stability condition for active disturbance rejection control(ADRC)with a time-varying bandwidth extended state observer(ESO).A new stability condition is derived,which means that the upper bound of rate of change for ESO bandwidth should be restricted.Moreover,under the proposed condition,the closed-loop stability of ADRC with a time-varying bandwidth observer is rigorously proved for nonlinear uncertainties.In simulations,the necessity of the proposed condition is illustrated,demonstrating that the rate of change of ESO bandwidth is crucial for closed-loop stability.展开更多
The objective of this paper is to present a robust safety-critical control system based on the active disturbance rejection control approach, designed to guarantee safety even in the presence of model inaccuracies, un...The objective of this paper is to present a robust safety-critical control system based on the active disturbance rejection control approach, designed to guarantee safety even in the presence of model inaccuracies, unknown dynamics, and external disturbances. The proposed method combines control barrier functions and control Lyapunov functions with a nonlinear extended state observer to produce a robust and safe control strategy for dynamic systems subject to uncertainties and disturbances. This control strategy employs an optimization-based control, supported by the disturbance estimation from a nonlinear extended state observer. Using a quadratic programming algorithm, the controller computes an optimal, stable, and safe control action at each sampling instant. The effectiveness of the proposed approach is demonstrated through numerical simulations of a safety-critical interconnected adaptive cruise control system.展开更多
With the increasing penetration of renewable energy resources in power systems,conventional timescale separated load frequency control(LFC)and economic dispatch may degrade frequency performance and reduce economic ef...With the increasing penetration of renewable energy resources in power systems,conventional timescale separated load frequency control(LFC)and economic dispatch may degrade frequency performance and reduce economic efficiency.This paper proposes a novel data-driven adaptive distributed optimal disturbance rejection control(DODRC)method for real-time economic LFC problem in nonlinear power systems.Firstly,a basic DODRC method is proposed by integrating the active disturbance rejection control method and the partial primal–dual algorithm.Then,to deal with the tie-line power flow constraints,the logarithmic barrier function is employed to reconstruct the Lagrange function to obtain the constrained DODRC method.By analyzing the sensitivity of the uncertain parameters of power systems,a data-driven adaptive DODRC method is finally proposed with a neural network.The effectiveness of the proposed method is demonstrated by experimental results using real-time equipment.展开更多
During the startup of the hydraulic turbine generators,the hybrid magnetic bearing support system exhibits displacement fluctuations,and the nonlinearity and strong coupling characteristics of the magnetic bearings li...During the startup of the hydraulic turbine generators,the hybrid magnetic bearing support system exhibits displacement fluctuations,and the nonlinearity and strong coupling characteristics of the magnetic bearings limit the accuracy of rotor modeling,making traditional control methods difficult to adapt to parameter variations.To suppress startup disturbances and achieve a control strategy with low computational complexity and high precision,this paper proposes a five-degree-of-freedom hybrid magnetic bearing control strategy based on an improved cascaded reduced-order linear active disturbance rejection controller(CRLADRC).The front-stage reduced-order linear extended state observer(FRLESO)reduces the system’s computational complexity,enabling the system to maintain stability during motor startup disturbances.The second-stage reduced-order linear extended state observer(SRLESO)further enhances the system’s disturbance estimation accuracy while maintaining low computational complexity.Furthermore,the disturbance rejection and noise suppression capabilities are analyzed in the frequency domain and the stability of the proposed control method is proven using Lyapunov theory.Experimental results indicate that the proposed strategy effectively reduces displacement fluctuations in the hybrid magnetic bearing support system during motor startup,significantly enhancing the system’s robustness.展开更多
An enhanced least mean square(LMS)error identification algorithm integrated with Kalman filtering is proposed to resolve accuracy degradation induced by nonlinear dynamics and parameter uncertainties in continuous rot...An enhanced least mean square(LMS)error identification algorithm integrated with Kalman filtering is proposed to resolve accuracy degradation induced by nonlinear dynamics and parameter uncertainties in continuous rotary electro-hydraulic servo systems.This enhancement accelerates convergence and improves accuracy compared with traditional LMS.A fifth-order identification mod-el is developed based on valve-controlled hydraulic motors,with parameters identified using Kalman filter state estimation and gradient smoothing.The results indicate that the improved LMS effectively enhances parameter identification.An advanced disturbance rejection controller(ADRC)is de-signed,and its performance is compared with an optimal proportional integral derivative(PID)con-troller through Simulink simulations.The results show that the ADRC fulfills the control specifications and expands the system’s operational bandwidth.展开更多
This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial...This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.展开更多
This paper aims to fuse two well-established and,at the same time,opposed control techniques,namely,model predictive control(MPC)and active disturbance rejection control(ADRC),to develop a dynamic motion controller fo...This paper aims to fuse two well-established and,at the same time,opposed control techniques,namely,model predictive control(MPC)and active disturbance rejection control(ADRC),to develop a dynamic motion controller for a laser beam steering system.The proposed technique uses the ADRC philosophy to lump disturbances and model uncertainties into a total disturbance.Then,the total disturbance is estimated via a discrete extended state disturbance observer(ESO),and it is used to(1)handle the system constraints in a quadratic optimization problem and(2)injected as a feedforward term to the plant to reject the total disturbance,together with the feedback term obtained by the MPC.The main advantage of the proposed approach is that the MPC is designed based on a straightforward integrator-chain model such that a simple convex optimization problem is performed.Several experiments show the real-time closed-loop performance regarding trajectory tracking and disturbance rejection.Owing to simplicity,the self-contained approach MPC+ESO becomes a Frugal MPC,which is computationally economical,adaptable,efficient,resilient,and suitable for applications where on-board computational resources are limited.展开更多
Brood parasitic birds lay eggs in the nests of other birds,and the parasitized hosts can reduce the cost of raising unrelated offspring through the recognition of parasitic eggs.Hosts can adopt vision-based cognitive ...Brood parasitic birds lay eggs in the nests of other birds,and the parasitized hosts can reduce the cost of raising unrelated offspring through the recognition of parasitic eggs.Hosts can adopt vision-based cognitive mechanisms to recognize foreign eggs by comparing the colors of foreign and host eggs.However,there is currently no uniform conclusion as to whether this comparison involves the single or multiple threshold decision rules.In this study,we tested both hypotheses by adding model eggs of different colors to the nests of Barn Swallows(Hirundo rustica)of two geographical populations breeding in Hainan and Heilongjiang Provinces in China.Results showed that Barn Swallows rejected more white model eggs(moderate mimetic to their own eggs)and blue model eggs(highly non-mimetic eggs with shorter reflectance spectrum)than red model eggs(highly nonmimetic eggs with longer reflectance spectrum).There was no difference in the rejection rate of model eggs between the two populations of Barn Swallows,and clutch size was not a factor affecting egg recognition.Our results are consistent with the single rejection threshold model.This study provides strong experimental evidence that the color of model eggs can has an important effect on egg recognition in Barn Swallows,opening up new avenues to uncover the evolution of cuckoo egg mimicry and explore the cognitive mechanisms underlying the visual recognition of foreign eggs by hosts.展开更多
In this paper, the attitude tracking and load relief control problems against wind disturbances and uncertain aerodynamics as well as the engine thrust of launch vehicles are studied.Firstly, a framework of Compensate...In this paper, the attitude tracking and load relief control problems against wind disturbances and uncertain aerodynamics as well as the engine thrust of launch vehicles are studied.Firstly, a framework of Compensated Acceleration Feedback based Active Disturbance Rejection Control(CAF-ADRC) is established to achieve both desired attitude tracking and load relief performances. In particular, the total disturbance that includes the effects caused by both aerocoefficient perturbations and disturbances is estimated by constructing an Extended State Observer(ESO) to achieve attitude tracking. Furthermore, combined with the normal acceleration due to the engine thrust, the accelerometer measurement is also compensated to enhance the load relief effect.Secondly, the quantitative analysis of ESO and the entire closed-loop system are studied. It can be concluded that the desired attitude tracking and load relief performances can be achieved simultaneously under the proposed approach. Besides, tuning laws of the proposed approach are systematically given, which are divided into ESO, Proportional Derivative(PD) and Compensated Acceleration Feedback(CAF) modules. Moreover, the performances under CAF-ADRC approach can be better than those under CAF based PD(CAF-PD) approach by tuning load relief gain.Finally, the approach presented is applied to a typical control problem of launch vehicles with wind disturbances and parameter uncertainties.展开更多
Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturba...Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturbance suppression and have poor performance in suppressing complex nonlinear disturbances.In order to address these issues,this paper proposes an improved two-degree-of-freedom LADRC(TDOF-LADRC)strategy,which can enhance the disturbance rejection performance of the system while decoupling entirely the system's dynamic and anti-disturbance performance to boost the system robustness and simplify controller parameter tuning.PMSM models that consider total disturbances are developed to design the TDOF-LADRC speed controller accurately.Moreover,to evaluate the control performance of the TDOF-LADRC strategy,its stability is proven,and the influence of each controller parameter on the system control performance is analyzed.Based on it,a comparison is made between the disturbance observation ability and anti-disturbance performance of TDOF-LADRC and CLADRC to prove the superiority of TDOF-LADRC in rejecting disturbances.Finally,experiments are performed on a 750 W PMSM experimental platform,and the results demonstrate that the proposed TDOF-LADRC exhibits the properties of two degrees of freedom and improves the disturbance rejection performance of the PMSM system.展开更多
The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution.Avian brood parasitism reduces the reproductive success of hosts,and thus,hosts ...The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution.Avian brood parasitism reduces the reproductive success of hosts,and thus,hosts have evolved anti-parasitic strategies,such as rejecting parasitic eggs and adopting aggressive nest defense strategies,to avoid the cost brought on by brood parasitism.To test whether host anti-parasitic strategies are adjusted with the risk of being parasitized when the breeding seasons of brood parasites and hosts are not synchronous,we conducted a field experiment assessing nest defense and egg recognition behaviors of the Isabelline Shrike(Lanius isabellinus),a host of the Common Cuckoo(Cuculus canorus).In the local area,the host Isabelline Shrike begins to breed in April,whereas the summer migratory Common Cuckoo migrates to the local area in May and begins to lay parasitic eggs.Results showed that nest defense behaviors of the Isabelline Shrike increases significantly after cuckoo arrival,showing higher aggressiveness to cuckoo dummies,with no significant difference in attack rates among cuckoo,sparrowhawk and dove dummies,but their egg rejection did not change significantly.These results imply that Isabelline Shrikes may adjust their nest defense behavior,but not egg rejection behavior,with seasonality.展开更多
The virtual synchronous generator(VSG)technology has been proposed to address the problem of system frequency and active power oscillation caused by grid-connected new energy power sources.However,the traditional volt...The virtual synchronous generator(VSG)technology has been proposed to address the problem of system frequency and active power oscillation caused by grid-connected new energy power sources.However,the traditional voltage-current double-closed-loop control used in VSG has the disadvantages of poor disturbance immunity and insufficient dynamic response.In light of the issues above,a virtual synchronous generator voltage outer-loop control strategy based on improved linear autonomous disturbance rejection control(ILADRC)is put forth for consideration.Firstly,an improved first-order linear self-immunity control structure is established for the characteristics of the voltage outer loop;then,the effects of two key control parameters-observer bandwidthω_(0)and controller bandwidthω_(c)on the control system are analyzed,and the key parameters of ILADRC are optimally tuned online using improved gray wolf optimizer-radial basis function(IGWO-RBF)neural network.A simulationmodel is developed using MATLAB to simulate,analyze,and compare the method introduced in this paper.Simulations are performed with the traditional control strategy for comparison,and the results demonstrate that the proposed control method offers superior anti-interference performance.It effectively addresses power and frequency oscillation issues and enhances the stability of the VSG during grid-connected operation.展开更多
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.
文摘Antibody-mediated rejection(AMR)represents a major challenge in kidney transplantation,significantly contributing to tissue injury and graft failure.AMR is primarily driven by donor-specific alloantibodies(DSAs),which recognize and bind to specific target antigens present within the transplanted kidney tissue.Upon binding,these DSAs commonly initiate activation of the complement system within the graft.The activation of the complement cascade sets off a powerful inflammatory response characterized by the recruitment and activation of immune cells,endothelial damage,and subsequent tissue injury.This inflammation underlies many clinical and histological manifestations of AMR,making complement activation a critical player in the disease process.Advancements in our understanding of how complement pathways contribute to kidney graft injury have opened new avenues for therapeutic intervention.Recent research has facilitated the development and application of novel therapies specifically designed to inhibit complement activation.Such targeted complement-inhibitory strategies have shown promise in improving graft outcomes by inhibiting complement-mediated damage and extending graft survival.This review comprehensively discusses the critical role of complement activation in inducing kidney graft injury with a focus on its role in AMR.By elucidating the detailed mechanisms and contributions of complement pathways,the review seeks to enhance the understanding necessary for developing targeted therapeutic interventions to prevent or treat AMR effectively.
文摘BACKGROUND The Luminex platform,where beads are coated with single human leukocyte antigens(HLA),detects HLA antibodies with higher sensitivity and specificity compared to complement-dependent cytotoxicity(CDC)assay and flow crossmatch(FCXM).The clinical significance of donor-specific antibodies(DSAs)detected by this method is still under investigation.AIM To report the impact of low-level pretransplant DSAs detected by the Luminex platform on the rates of acute rejection(AR),allograft function,and long-term graft survival.METHODS This retrospective study was conducted at the Immunology Department of Sindh Institute of Urology and Transplantation,Karachi,Pakistan between January 2013 and December 2022.During this period 2714 patients were transplanted.Out of these patients 78(2.9%)patients had low-level DSAs detected by the Luminex flow beads method and were negative by CDC and FCXM with their donors.All recipients received ABO-compatible live-related kidney transplants.All patients had a minimum follow-up of 1 year.Graft rejection rates,graft function,and patient and graft survival were analyzed.The estimated glomerular filtration rate was calculated by the full CKD-EPI formula.RESULTS The mean age of all recipients was 29.57±10.11 years and 34.53±9.09 years for the donors.In 48(61.5%)patients,the cause of end-stage kidney disease was unknown.DSA against HLA class I was detected in 36(46.1%)patients,class II in 35(44.8%)patients,and both class I and II in 7(8.9%)patients.AR episodes were encountered in 8(10.3%)cases.Seven(87.5%)had T cell mediated rejection(type IA)and one acute antibody-mediated rejection.Antibody status was re-evaluated at the time of biopsy-proven ARs.Five(62.5%)patients lost their DSAs,while three(37.5%)had persistent DSAs.The mean estimated glomerular filtration rate at 1 year was 80.56±27.48 mL/min/1.73 m2 and at the last follow-up 73.41±28.80 mL/min/1.73 m2.The 1-year and 10-year patient and graft survival rates were 99%and 79%and 95%and 75%,respectively.During the follow-up period,10(12.8%)patients died,8 patients had a functioning graft,and 2 patients had failed grafts.Eight patients died due to cardiopulmonary arrest,and two died due to sepsis with failed grafts.CONCLUSION Patients with pretransplant low-level DSAs on Luminex without CDC and FCXM reactivity had good allograft outcomes at 1 year and 10 years as long as they are induced with biological agents and given potent maintenance immunosuppressants.
文摘BACKGROUND Advancements in immunosuppressive therapies have improved graft survival by enhancing graft tolerance and preventing organ rejection.However,the risk of malignancy associated with prolonged immunosuppression remains a concern,as it can adversely affect recipients’quality of life and survival.While the link be-tween immunosuppression and increased cancer risk is well-documented,the specific interactions between graft rejection and post-transplant malignancy(PTM)remain poorly understood.Addressing this knowledge gap is crucial for devising immunosuppressive strategies that balance rejection prevention with cancer risk reduction.AIM To investigate whether immunosuppression in PTM reduces rejection risk,while immune activation during rejection protects against malignancy.METHODS We analyzed data from the United Network for Organ Sharing’s Organ Procurewith no prior history of malignancy(in donors or recipients).Landmark analyses at 1,2,3,5,10,15,and 20 years post-transplant,Kaplan–Meier analyses,and time-dependent Cox proportional hazards regression models,each incorporating the temporal dimension of outcomes,assessed the association between rejection-induced graft failure(RGF)and PTM.Multivariate models were adjusted for clinical and immunological factors,including immunosuppression regimens.RESULTS The cohort included 579905 recipients(kidney:386878;liver:108390;heart:45046;lung:37643;pancreas:1948)with a mean follow-up of 7.3 years and a median age of 50.6±13.2 years.RGF was associated with a reduction in PTM risk across all time points[hazard ratio(HR)=0.07-0.20,P<0.001],even after excluding mortality cases.Kidney transplant recipients exhibited the most pronounced reduction(HR=0.22,P<0.001).Conversely,among recipients with PTM,RGF risk decreased across all time points up to 15 years after excluding mortality cases(HR=0.49–0.80,P<0.001).This risk reduction was observed in kidney,liver,heart,and lung transplants(HRs=0.90,0.21,0.21,and 0.18,respectively;P<0.001)but not in pancreas transplants.CONCLUSION RGF reduces PTM risk,particularly in kidney transplants,while PTM decreases RGF risk in kidney,liver,heart,and lung transplants.
基金Supported by the National Natural Science Foundation of China,No.82100691China Postdoctoral Science Foundation,No.2021M693631.
文摘Organ transplantation has long been recognized as an effective treatment for endstage organ failure,metabolic diseases,and malignant tumors.However,graft rejection caused by major histocompatibility complex mismatch remains a significant challenge.While modern immunosuppressants have made significant strides in reducing the incidence and risk of rejection,they have not been able to eliminate it completely.The intricate mechanisms underlying transplant rejection have been the subject of intense investigation by transplant immunologists.Among these factors,autophagy has emerged as a key player.Autophagy is an evolutionarily conserved mechanism in eukaryotic cells that mediates autophagocytosis and cellular protection.This process is regulated by autophagy-related genes and their encoded protein families,which maintain the material and energetic balance within cells.Additionally,autophagy has been reported to play crucial roles in the development,maturation,differentiation,and responses of immune cells.In the complex immune environment following transplantation,the role and mechanisms of autophagy are gradually being revealed.In this review,we aim to explore the current understanding of the role of autophagy in solid organ rejection after transplantation.Furthermore,we delve into the therapeutic advancements achieved by targeting autophagy involved in the rejection process.
文摘BACKGROUND Malabsorptive bariatric surgery,including Roux-en-Y gastric bypass and duodenal switch,are known to be more metabolically effective than restrictive surgery.However,the permanent alteration of gastrointestinal anatomy from these operations has been shown to alter the kinetics of drug absorption and may make subsequent surgeries more technically challenging.AIM To evaluate perioperative liver transplant outcomes and rates of acute cellular rejection in recipients with prior malabsorptive bariatric surgery.METHODS Patients who underwent liver transplantation at a single institution between 2005-2024 with a history of malabsorptive bariatric surgery were identified.Matched controls were selected based on age,sex,listing model for end-stage liver disease(MELD),and primary liver diagnosis.RESULTS A total of 12 liver transplant patients with prior malabsorptive surgery and 25 controls were included.The mean age in the malabsorptive group was 50.5 years at the time of transplant and 92%were female.The mean MELD at the time of transplant was 27.6 and mean body mass index was 28.There were no significant differences in length of stay,post operative complications,or 1 year survival between the controls and malabsorptive patients.However,the malabsorptive group was significantly more likely to experience biopsy-proven and clinically treated acute cellular rejection than the controls(24%vs 66.7%,P=0.012),more frequent rejection episodes(0.28±0.53 vs 1.0±0.91,P=0.006),and earlier time to first rejection episode(P=0.002).CONCLUSION Previous malabsorptive bariatric surgery in liver transplant recipients did not increase the risk of perioperative complications or mortality but significantly increased the rate and frequency of acute cellular rejection.
文摘BACKGROUND The pathophysiology behind gastroesophageal reflux disease and its association with poor outcomes after lung transplantation is incompletely understood.The physiologic impact of lung transplantation on pulmonary function,intrathoracic pressures,and vagal innervation may affect esophageal motility,bolus clearance and reflux risk.However,the effect of changes in esophageal function after lung transplantation on the risk of poor post-transplant outcomes remains unclear.AIM To evaluate the association between change in esophageal motility pre-/post-lung transplantation and rejection outcome.METHODS This was a retrospective cohort study of lung transplant recipients who underwent both pre-and post-transplant esophageal testing including high resolution manometry(HRM)at a tertiary center.Acute cellular rejection(ACR)was defined histologically per International Society for Heart and Lung Transplantation criteria.Univariate analyses were performed using student’s t-test,χ2 test,and Spearman’s correlation where appropriate.Multivariable time-to-event analysis using Cox proportional hazards model was applied.Subjects not meeting ACR outcome were censored at death or date of last clinic visit.RESULTS 55 subjects(65%men,mean age:61,median follow-up:840 days)were included,with 17 (31%) experiencing ACR. Increase in failed swallows correlated with lower baseline total lung capacity(TLC) (R = -0.32, P = 0.05) and decreased post-transplant esophageal bolus clearance (R = -0.45, P = 0.004). Onmultivariable analysis, post-transplant hypomotility independently predicted increased ACR (HR: 3.62, 95%CI:1.11-11.8;P = 0.03). Kaplan-Meier analysis demonstrated increased ACR for subjects with increased vs unchangedfailed swallows post-transplant (P = 0.048). On Cox regression, a 20% elevated risk of ACR was found for every10% increase in failed swallows, after controlling for confounders including reflux severityCONCLUSIONEsophageal hypomotility, specifically an increase in failed swallows on HRM, from pre- to post-lungtransplantation was independently associated with ACR. Additionally, lower baseline TLC correlated with increasein failed swallows, suggesting restrictive lung disease may be associated with post-transplant esophagealhypomotility. Lung transplantation may affect esophageal function and contribute to rejection outcomes. Routineesophageal function testing may help identify patients at higher risk for poor lung transplantation outcomes.
文摘The study of Mecanum mobile robots typically assumes motion on planar surfaces,while the challenges posed by inclined terrains remain largely unexplored,leaving a significant gap in control applications for such scenarios.In this context,two critical issues emerge:the gravitational pull caused by adding a potential energy term in the robot dynamics,which drives the vehicle downhill,and several positioning errors due to vibrations and slippage of the Mecanum wheel.To address these challenges,this work presents an Active Disturbance Rejection Control(ADRC)-based framework designed to enable accurate tracking on inclined surfaces,despite the compounded effects of gravitational forces and slippage.Unlike conventional controllers,the proposed method requires minimal model knowledge while actively compensates for unknown dynamics and external disturbances in real time.A complete theoretical formulation is provided,supported by numerical simulations and comprehensive experimental validation.Results demonstrate that the ADRC structure significantly outperforms not only the traditional proportional-integral-derivative(PID)control but also a robust variant of PID combined with a Quasi-Sliding Mode control(PID-QSMC)strategy,achieving superior tracking.Notably,this study offers an important experimental validation of ADRC for Mecanum-wheeled robots operating on inclined surfaces.It contributes a practical and scalable solution to extend their operational capabilities beyond flat environments.
基金supported partially by the National Natural Science Foundation(No.62473344)the T-Flight Laboratory in ShanXi Provincial(No.GSFC2024NBKY05)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2025JC-YBQN-035)the National Natural Science Foundation of China(Grant No.92471204).
文摘With the growing adoption of artificial intelligence algorithms and neural networks,online learning and adaptive methods for updating the bandwidth have become increasingly prevalent.However,the conditions required to ensure closed-loop stability when employing a time-varying bandwidth,as well as the supporting mathematical foundations,remain insufficiently studied.This paper investigates the stability condition for active disturbance rejection control(ADRC)with a time-varying bandwidth extended state observer(ESO).A new stability condition is derived,which means that the upper bound of rate of change for ESO bandwidth should be restricted.Moreover,under the proposed condition,the closed-loop stability of ADRC with a time-varying bandwidth observer is rigorously proved for nonlinear uncertainties.In simulations,the necessity of the proposed condition is illustrated,demonstrating that the rate of change of ESO bandwidth is crucial for closed-loop stability.
基金supported by the Fondo para el Primer Proyecto of the Comitépara el Desarrollo de la Investigación(CODI)at the Universidad de Antioquia(Grant Number PRV2024-78509)。
文摘The objective of this paper is to present a robust safety-critical control system based on the active disturbance rejection control approach, designed to guarantee safety even in the presence of model inaccuracies, unknown dynamics, and external disturbances. The proposed method combines control barrier functions and control Lyapunov functions with a nonlinear extended state observer to produce a robust and safe control strategy for dynamic systems subject to uncertainties and disturbances. This control strategy employs an optimization-based control, supported by the disturbance estimation from a nonlinear extended state observer. Using a quadratic programming algorithm, the controller computes an optimal, stable, and safe control action at each sampling instant. The effectiveness of the proposed approach is demonstrated through numerical simulations of a safety-critical interconnected adaptive cruise control system.
基金supported in part by the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources under Grant LAPS24009in part by the Guangdong Basic and Applied Basic Research Foundation under Grant 2021A1515110016in part by the National Natural Science Foundation of China under Grant 52206009.
文摘With the increasing penetration of renewable energy resources in power systems,conventional timescale separated load frequency control(LFC)and economic dispatch may degrade frequency performance and reduce economic efficiency.This paper proposes a novel data-driven adaptive distributed optimal disturbance rejection control(DODRC)method for real-time economic LFC problem in nonlinear power systems.Firstly,a basic DODRC method is proposed by integrating the active disturbance rejection control method and the partial primal–dual algorithm.Then,to deal with the tie-line power flow constraints,the logarithmic barrier function is employed to reconstruct the Lagrange function to obtain the constrained DODRC method.By analyzing the sensitivity of the uncertain parameters of power systems,a data-driven adaptive DODRC method is finally proposed with a neural network.The effectiveness of the proposed method is demonstrated by experimental results using real-time equipment.
基金supported by the National Natural Science Foundation of China under Grant 52302458the CAS Project for Young Scientists in Basic Research,Grant No.YSBR-045.
文摘During the startup of the hydraulic turbine generators,the hybrid magnetic bearing support system exhibits displacement fluctuations,and the nonlinearity and strong coupling characteristics of the magnetic bearings limit the accuracy of rotor modeling,making traditional control methods difficult to adapt to parameter variations.To suppress startup disturbances and achieve a control strategy with low computational complexity and high precision,this paper proposes a five-degree-of-freedom hybrid magnetic bearing control strategy based on an improved cascaded reduced-order linear active disturbance rejection controller(CRLADRC).The front-stage reduced-order linear extended state observer(FRLESO)reduces the system’s computational complexity,enabling the system to maintain stability during motor startup disturbances.The second-stage reduced-order linear extended state observer(SRLESO)further enhances the system’s disturbance estimation accuracy while maintaining low computational complexity.Furthermore,the disturbance rejection and noise suppression capabilities are analyzed in the frequency domain and the stability of the proposed control method is proven using Lyapunov theory.Experimental results indicate that the proposed strategy effectively reduces displacement fluctuations in the hybrid magnetic bearing support system during motor startup,significantly enhancing the system’s robustness.
基金Supported by the National Natural Science Foundation of China(No.52375037)the Outstanding Youth of Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(No.GDRC 20220801)+1 种基金the Graduate Innovation Fund Project of Beijing University of Civil Engineering and Architecture(No.PG2025160)the Special Fund for Cultivation Projects of Beijing University of Civil Engineering and Architecture(No.X24026).
文摘An enhanced least mean square(LMS)error identification algorithm integrated with Kalman filtering is proposed to resolve accuracy degradation induced by nonlinear dynamics and parameter uncertainties in continuous rotary electro-hydraulic servo systems.This enhancement accelerates convergence and improves accuracy compared with traditional LMS.A fifth-order identification mod-el is developed based on valve-controlled hydraulic motors,with parameters identified using Kalman filter state estimation and gradient smoothing.The results indicate that the improved LMS effectively enhances parameter identification.An advanced disturbance rejection controller(ADRC)is de-signed,and its performance is compared with an optimal proportional integral derivative(PID)con-troller through Simulink simulations.The results show that the ADRC fulfills the control specifications and expands the system’s operational bandwidth.
文摘This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.
基金support through his Master scholarshipThe Vicerrectoría de Investigación y Estudios de Posgrado(VIEP-BUAP)partially funded this work under grant number 00593-PV/2025.
文摘This paper aims to fuse two well-established and,at the same time,opposed control techniques,namely,model predictive control(MPC)and active disturbance rejection control(ADRC),to develop a dynamic motion controller for a laser beam steering system.The proposed technique uses the ADRC philosophy to lump disturbances and model uncertainties into a total disturbance.Then,the total disturbance is estimated via a discrete extended state disturbance observer(ESO),and it is used to(1)handle the system constraints in a quadratic optimization problem and(2)injected as a feedforward term to the plant to reject the total disturbance,together with the feedback term obtained by the MPC.The main advantage of the proposed approach is that the MPC is designed based on a straightforward integrator-chain model such that a simple convex optimization problem is performed.Several experiments show the real-time closed-loop performance regarding trajectory tracking and disturbance rejection.Owing to simplicity,the self-contained approach MPC+ESO becomes a Frugal MPC,which is computationally economical,adaptable,efficient,resilient,and suitable for applications where on-board computational resources are limited.
基金supported by the National Natural Science Foundation of China(Nos.31970427 and 32270526 to W.L.)。
文摘Brood parasitic birds lay eggs in the nests of other birds,and the parasitized hosts can reduce the cost of raising unrelated offspring through the recognition of parasitic eggs.Hosts can adopt vision-based cognitive mechanisms to recognize foreign eggs by comparing the colors of foreign and host eggs.However,there is currently no uniform conclusion as to whether this comparison involves the single or multiple threshold decision rules.In this study,we tested both hypotheses by adding model eggs of different colors to the nests of Barn Swallows(Hirundo rustica)of two geographical populations breeding in Hainan and Heilongjiang Provinces in China.Results showed that Barn Swallows rejected more white model eggs(moderate mimetic to their own eggs)and blue model eggs(highly non-mimetic eggs with shorter reflectance spectrum)than red model eggs(highly nonmimetic eggs with longer reflectance spectrum).There was no difference in the rejection rate of model eggs between the two populations of Barn Swallows,and clutch size was not a factor affecting egg recognition.Our results are consistent with the single rejection threshold model.This study provides strong experimental evidence that the color of model eggs can has an important effect on egg recognition in Barn Swallows,opening up new avenues to uncover the evolution of cuckoo egg mimicry and explore the cognitive mechanisms underlying the visual recognition of foreign eggs by hosts.
基金supported by the National Key R&D Program of China (No. 2022YFA1004703)the National Natural Science Foundation of China (Nos. 62122083 and 62103014)Chinese Academy of Sciences Youth Innovation Promotion Association (No. 2021003)。
文摘In this paper, the attitude tracking and load relief control problems against wind disturbances and uncertain aerodynamics as well as the engine thrust of launch vehicles are studied.Firstly, a framework of Compensated Acceleration Feedback based Active Disturbance Rejection Control(CAF-ADRC) is established to achieve both desired attitude tracking and load relief performances. In particular, the total disturbance that includes the effects caused by both aerocoefficient perturbations and disturbances is estimated by constructing an Extended State Observer(ESO) to achieve attitude tracking. Furthermore, combined with the normal acceleration due to the engine thrust, the accelerometer measurement is also compensated to enhance the load relief effect.Secondly, the quantitative analysis of ESO and the entire closed-loop system are studied. It can be concluded that the desired attitude tracking and load relief performances can be achieved simultaneously under the proposed approach. Besides, tuning laws of the proposed approach are systematically given, which are divided into ESO, Proportional Derivative(PD) and Compensated Acceleration Feedback(CAF) modules. Moreover, the performances under CAF-ADRC approach can be better than those under CAF based PD(CAF-PD) approach by tuning load relief gain.Finally, the approach presented is applied to a typical control problem of launch vehicles with wind disturbances and parameter uncertainties.
文摘Permanent magnet synchronous motor(PMSM)speed control systems with conventional linear active disturbance rejection control(CLADRC)strategy encounter issues regarding the coupling between dynamic response and disturbance suppression and have poor performance in suppressing complex nonlinear disturbances.In order to address these issues,this paper proposes an improved two-degree-of-freedom LADRC(TDOF-LADRC)strategy,which can enhance the disturbance rejection performance of the system while decoupling entirely the system's dynamic and anti-disturbance performance to boost the system robustness and simplify controller parameter tuning.PMSM models that consider total disturbances are developed to design the TDOF-LADRC speed controller accurately.Moreover,to evaluate the control performance of the TDOF-LADRC strategy,its stability is proven,and the influence of each controller parameter on the system control performance is analyzed.Based on it,a comparison is made between the disturbance observation ability and anti-disturbance performance of TDOF-LADRC and CLADRC to prove the superiority of TDOF-LADRC in rejecting disturbances.Finally,experiments are performed on a 750 W PMSM experimental platform,and the results demonstrate that the proposed TDOF-LADRC exhibits the properties of two degrees of freedom and improves the disturbance rejection performance of the PMSM system.
基金funded by the National Natural Science Foundation of China (Nos. 31970427 and 32270526 to WL)。
文摘The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution.Avian brood parasitism reduces the reproductive success of hosts,and thus,hosts have evolved anti-parasitic strategies,such as rejecting parasitic eggs and adopting aggressive nest defense strategies,to avoid the cost brought on by brood parasitism.To test whether host anti-parasitic strategies are adjusted with the risk of being parasitized when the breeding seasons of brood parasites and hosts are not synchronous,we conducted a field experiment assessing nest defense and egg recognition behaviors of the Isabelline Shrike(Lanius isabellinus),a host of the Common Cuckoo(Cuculus canorus).In the local area,the host Isabelline Shrike begins to breed in April,whereas the summer migratory Common Cuckoo migrates to the local area in May and begins to lay parasitic eggs.Results showed that nest defense behaviors of the Isabelline Shrike increases significantly after cuckoo arrival,showing higher aggressiveness to cuckoo dummies,with no significant difference in attack rates among cuckoo,sparrowhawk and dove dummies,but their egg rejection did not change significantly.These results imply that Isabelline Shrikes may adjust their nest defense behavior,but not egg rejection behavior,with seasonality.
基金supported by the Lanzhou Jiaotong University-Southwest Jiaotong University Joint Innovation Fund(LH2024027).
文摘The virtual synchronous generator(VSG)technology has been proposed to address the problem of system frequency and active power oscillation caused by grid-connected new energy power sources.However,the traditional voltage-current double-closed-loop control used in VSG has the disadvantages of poor disturbance immunity and insufficient dynamic response.In light of the issues above,a virtual synchronous generator voltage outer-loop control strategy based on improved linear autonomous disturbance rejection control(ILADRC)is put forth for consideration.Firstly,an improved first-order linear self-immunity control structure is established for the characteristics of the voltage outer loop;then,the effects of two key control parameters-observer bandwidthω_(0)and controller bandwidthω_(c)on the control system are analyzed,and the key parameters of ILADRC are optimally tuned online using improved gray wolf optimizer-radial basis function(IGWO-RBF)neural network.A simulationmodel is developed using MATLAB to simulate,analyze,and compare the method introduced in this paper.Simulations are performed with the traditional control strategy for comparison,and the results demonstrate that the proposed control method offers superior anti-interference performance.It effectively addresses power and frequency oscillation issues and enhances the stability of the VSG during grid-connected operation.
