Active disturbance rejection control(ADRC)exhibits notable resilience against both internal and external disturbances.Its straightforward implementation further enhances its appeal for controlling a diverse class of s...Active disturbance rejection control(ADRC)exhibits notable resilience against both internal and external disturbances.Its straightforward implementation further enhances its appeal for controlling a diverse class of systems.However,the high-gain nature of the extended state observer,which is the core of ADRC,may degrade performance when faced with high-frequency sensing noise—a common challenge in real-world settings.This article addresses this issue through a specifically placed and particularly designed low-pass filterwhile preserving the ease of implementation characteristic of ADRC.This article proposes a simple tuning method for the filter-controller structure to improve the scheme’s design process.Theoretical results simplify the design process based on the Routh–Hurwitz criterion such that the additional low-pass filter does not affect the closedloop stability.The maximum power point tracking task on a wind turbine—a nonlinear system requiring the measurement of inherently noisy signals,such as electrical currents—is addressed to illustrate the design process of the proposed approach.Real-time experiments on a laboratory platform emulating a Permanent Magnet Synchronous Generator-based wind turbine endorse the enhanced scheme’s effectiveness in mitigating high-frequency sensing noise.展开更多
With the rapid development of the medical industry,ensuring patient safety and improving medical quality have led to the development of a very important aspect:hospital infection control.This paper intends to evaluate...With the rapid development of the medical industry,ensuring patient safety and improving medical quality have led to the development of a very important aspect:hospital infection control.This paper intends to evaluate the job competencies of infection prevention and control personnel in Chinese medicine hospitals through an analysis of the necessity of such competencies,the establishment of criteria for evaluation,and the exploration of methods for implementation.This paper proposes an effective evaluation system on the basis of recent research findings and some recommendations for how to improve infection management in these hospitals.This study provides suggestions for the training and management of staff in infection prevention and control through a review of the relevant literature within the context of Chinese medicine hospitals.展开更多
Objective:To investigate the association between diagnosis delays and mortality in patients with haemorrhagic fever in Upper Southern Thailand.Methods:A hospital-based case control study was conducted between December...Objective:To investigate the association between diagnosis delays and mortality in patients with haemorrhagic fever in Upper Southern Thailand.Methods:A hospital-based case control study was conducted between December 2019 and January 2020.Cases were defined as patients who had been diagnosed with haemorrhagic fever and died during hospitalization,while controls were patients with similar conditions who survived.Medical records were retrospectively reviewed,with the primary variable being a diagnosis delay of more than three days after the onset of illness.The outcome of interest was mortality during hospitalization.Data analysis involved descriptive statistics and multiple logistic regression.Results:A total of 38815 haemorrhagic fever cases were reported from 2014 to 2019.The case-to-control ratio was 1:3,comprising 66 cases and 198 controls.Among 66 cases and 198 controls,the median(IQR)time from illness onset to diagnosis was 4(4)days in cases vs.1(0)day in controls.Diagnosis delays significantly increased mortality risk[adjusted OR(aOR)5.60,95%CI 2.74-11.46].Other risk factors for mortality included age≤5 years(aOR 16.15,95%CI 3.70-70.42)and overweight status(aOR 3.43,95%CI 1.57-7.52).Conclusions:Delayed diagnosis in patients with haemorrhagic fever was strongly associated with higher mortality rates.These findings highlight the critical importance of early diagnosis to reduce mortality in haemorrhagic fever cases.展开更多
Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate ...Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.展开更多
We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-ba...We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.展开更多
A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient condit...A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient conditions are presented on the stabilization of NCSs. Stabilizing state/output feedback controllers can be constructed by using the feasible solutions of some linear matrix inequalities （LMIs）. The merit of our proposed approach is that the behavior of the NCSs can be studied by considering switched system without augmenting the system. A simulation example is worked out to illustrate the effectiveness of the proposed approach.展开更多
With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and ...With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.展开更多
Many physical processes have nonlinear behavior which can be well represented by a polynomial NARX or NARMAX model. The identification of such models has been widely explored in literature. The majority of these appro...Many physical processes have nonlinear behavior which can be well represented by a polynomial NARX or NARMAX model. The identification of such models has been widely explored in literature. The majority of these approaches are for the open-loop identification. However, for reasons such as safety and production restrictions, open-loop identification cannot always be done. In such cases, closed-loop identification is necessary. This paper presents a two-step approach to closed-loop identification of the polynomial NARX/NARMAX systems with variable structure control （VSC）. First, a genetic algorithm （GA） is used to maximize the similarity of VSC signal to white noise by tuning the switching function parameters. Second, the system is simulated again and its parameters are estimated by an algorithm of the least square （LS） family. Finally, simulation examples are given to show the validity of the proposed approach.展开更多
A multi-loop constrained model predictive control scheme based on autoregressive exogenous-partial least squares(ARX-PLS) framework is proposed to tackle the high dimension, coupled and constraints problems in industr...A multi-loop constrained model predictive control scheme based on autoregressive exogenous-partial least squares(ARX-PLS) framework is proposed to tackle the high dimension, coupled and constraints problems in industry processes due to safety limitation, environmental regulations, consumer specifications and physical restriction. ARX-PLS decoupling character enables to turn the multivariable model predictive control(MPC) controller design in original space into the multi-loop single input single output(SISO) MPC controllers design in latent space.An idea of iterative method is applied to decouple the constraints latent variables in PLS framework and recursive least square is introduced to identify ARX-PLS model. This algorithm is applied to a non-square simulation system and a stirred reactor for ethylene polymerizations comparing with adaptive internal model control(IMC) method based on ARX-PLS framework. Its application has shown that this method outperforms adaptive IMC method based on ARX-PLS framework to some extent.展开更多
In order to improve the brake performance of a dual independent electric drive tracked vehicle,a dynamic model for braking situation was established.Then,a sliding model controller(SMC)with an auxiliary system was des...In order to improve the brake performance of a dual independent electric drive tracked vehicle,a dynamic model for braking situation was established.Then,a sliding model controller(SMC)with an auxiliary system was designed to control the slip and its effectiveness was proved.A hardware-in-loop simulation through MATLAB/XPC was compared with the normal SMC and normal integral sliding mode controller(ISMC),the results show that SMC with the auxiliary system has a better performance:a smaller overshoot and steady state error.The disturbance is suppressed effectively.In the initial speed of 65.km/h,the brake distance was shortened by 3.4%and 6.8%compared with the other two methods,respectively.Finally,initial speeds of 30-36.km/h tests was carried out on a flat soil road.Compared with a no-control brake,the displacement was shortened by 1.8.m.It demonstrates the effectiveness of the slip-control strategy.In the same situation,the error between the simulation and test is 18.1%,which validates the accuracy of models.展开更多
In the railway industry, re-adhesion control plays an important role in attenuating the slip occurrence due to the low adhesion condition in the wheel-rail inter- action. Braking and traction forces depend on the norm...In the railway industry, re-adhesion control plays an important role in attenuating the slip occurrence due to the low adhesion condition in the wheel-rail inter- action. Braking and traction forces depend on the normal force and adhesion coefficient at the wheel-rail contact area. Due to the restrictions on controlling normal force, the only way to increase the tractive or braking effect is to maximize the adhesion coefficient. Through efficient uti- lization of adhesion, it is also possible to avoid wheel-rail wear and minimize the energy consumption. The adhesion between wheel and rail is a highly nonlinear function of many parameters like environmental conditions, railway vehicle speed and slip velocity. To estimate these unknown parameters accurately is a very hard and competitive challenge. The robust adaptive control strategy presented in this paper is not only able to suppress the wheel slip in time, but also maximize the adhesion utilization perfor- mance after re-adhesion process even if the wheel-rail contact mechanism exhibits significant adhesion uncer- tainties and/or nonlinearities. Using an optimal slip velocity seeking algorithm, the proposed strategy provides a satisfactory slip velocity tracking ability, which was demonstrated able to realize the desired slip velocity without experiencing any instability problem. The control torque of the traction motor was regulated continuously to drive the railway vehicle in the neighborhood of the opti- mal adhesion point and guarantee the best traction capacity after re-adhesion process by making the railway vehicle operate away from the unstable region. The results obtained from the adaptive approach based on the second- order sliding mode observer have been confirmed through theoretical analysis and numerical simulation conducted in MATLAB and Simulink with a full traction model under various wheel-rail conditions.展开更多
Due to the special features of great inertia, pure lag and non-linearity provided with wind turbine, coupled with complex and variable working condition, it is difficult to achieve satisfactory control results simply ...Due to the special features of great inertia, pure lag and non-linearity provided with wind turbine, coupled with complex and variable working condition, it is difficult to achieve satisfactory control results simply by employing traditional PID, which has the drawbacks such as adjustment inconvenience, poor anti-interference, and large overshoot, and prolonged adjust span. This paper puts forward one type of improved controller combining Fuzzy Control with PID Control. With larger speed deviation, the controller emphasizes Fuzzy Control to speed system response;with less speed deviation, the controller emphasizes PID Control to improve control accuracy. Simulation Test directing at the algorithm is based on the Bladed software, with the positive result of improved dynamic and static performance of wind turbine under large disturbance.展开更多
High power conversion efficiency(PCE)flexible perovskite solar cells(FPSCs)are highly desired power sources for aerospace crafts and flexible electronics.However,their PCEs still lag far behind their rigid counterpart...High power conversion efficiency(PCE)flexible perovskite solar cells(FPSCs)are highly desired power sources for aerospace crafts and flexible electronics.However,their PCEs still lag far behind their rigid counterparts.Herein,we report a high PCE FPSC by controllable growth of a SnO_(2)electron transport layer through constant pH chemical bath deposition(CBD).The application of SnSO_(4)as tin source enables us to perform CBD without strong acid,which in turn makes it applicable to acid-sensitive flexible indium tin oxide.Furthermore,a mild and controllable growth environment leads to uniform particle growth and dense SnO_(2)deposition with full coverage and reproducibility,resulting in a record PCE of up to 25.09%(certified 24.90%)for FPSCs to date.The as-fabricated FPSCs exhibited high durability,maintaining over 90% of their initial PCE after 10000 bending cycles.展开更多
This paper presents a comparative study of different decoupling control schemes for a two-input, two-output(TITO) binary distillation column via proportional-integral(PI)controller. The key idea behind this paper is d...This paper presents a comparative study of different decoupling control schemes for a two-input, two-output(TITO) binary distillation column via proportional-integral(PI)controller. The key idea behind this paper is designing two novel fuzzy decoupling schemes that depend on human knowledge,instead of the system mathematical model used in conventional decoupling schemes. Based on conventional and inverted decoupling schemes, fuzzy and inverted fuzzy decoupling schemes are developed. The control effect is compared using simulation results for the proposed two schemes with conventional decoupling and inverted decoupling. The proposed fuzzy decoupling schemes are easy to realize and simple to design, besides they have a good decoupling capability. Two methods are used to prove asymptotic stability of each loop and the entire closed-loop system by applying the proposed fuzzy decoupling-based PI controller.The Wood and Berry model of a binary distillation column is used to illustrate the applicability of the proposed schemes.展开更多
In this work, the objectives were to provide a scientific basis for environmental governance and to ensure staff health by real-time monitoring of indoor air quality of the pathology department. Using eagle eye enviro...In this work, the objectives were to provide a scientific basis for environmental governance and to ensure staff health by real-time monitoring of indoor air quality of the pathology department. Using eagle eye environment monitor to make a real-time dynamic monitoring of the air quality of the pathological technical room for 30 days, the paper records the monitoring data of PM 2.5, PM 10, formaldehyde, CO2, total volatile organic compounds (TVOC) every day at Beijing time 3 a.m, 10 am, 1 pm, 4 pm, and 10 pm, and makes a summarization and analysis. The average value of CO2 concentration of the 5 time points is (0.05 ± 0.01)%, and each time point concentration are different (P 0.05);the average TVOC concentration of the 5 time points is (0.08 + 0.31) mg/m3. They are all different between the concentration at each time point (P 2 and NO are not checked out. Through the real-time online monitoring of the pathology room, we find that the formaldehyde concentration of different time periods is far more than the safety value standard, and the concentration of formaldehyde, CO2, PM 2.5, PM 10 and total volatile organic compound (TVOC) is different at different time periods, and the concentrations at working time are higher than the non-working time. We must take effective measures to control the concentration of harmful gases in order to ensure the staff’s health.展开更多
The problem of adaptive generalized predictive control which consists of output prediction errors for a class of switched systems is studied.The switching law is determined by the output predictive errors of a finite ...The problem of adaptive generalized predictive control which consists of output prediction errors for a class of switched systems is studied.The switching law is determined by the output predictive errors of a finite number of subsystems.For the single subsystem and multiple subsystems cases,it is proved that the given direct algorithm of generalized predictive control guarantees the global convergence of the system.This algorithm overcomes the inherent drawbacks of the slow convergence and large transient errors for the conventional adaptive control.展开更多
The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed meth...The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed method of evaluation is based on the statistical significance of the analytical response differences during atomic emission spectroscopy of solid specimens taken from one sample before and after heat treatment using the instruments AtomComp 81 and ARL 4460 with a high-voltage spark excitation. For calculations, the ratio of the line intensity of the analyzed element to the line intensity of the main sample component (in our case Ni<sub>2254</sub>) was used. The difference confidence estimation was made by the averages comparison method in a variance analysis. The study results are presented on the effect of material structure on analytical response during atomic emission spectroscopy of solid specimens. It was proved that the samples before and after heat treatment give statistically differing results while analyzed.展开更多
Background:This study uses a literature review and the Delphi expert consultation method to construct a competency evaluation model for infection control personnel in traditional Chinese medicine(TCM)hospitals.The aim...Background:This study uses a literature review and the Delphi expert consultation method to construct a competency evaluation model for infection control personnel in traditional Chinese medicine(TCM)hospitals.The aim is to strengthen infection control management in TCM hospitals,assess the competency of infection control personnel in their positions,and assist them in identifying the competencies that need improvement.Methods:Based on the literature research method and the Delphi expert consultation method,a competency model for the position was constructed through two rounds of expert consultations,analyzing the relationships between various factors and establishing a hierarchical structure model.Pairwise comparisons were made among the elements at the same level to construct a judgment matrix.Through the analytic hierarchy process,the weight coefficients of the indicators at each level in the competency model were obtained.Results:This study conducted a comprehensive assessment of various capabilities and practices related to hospital infection control.The survey results indicate that participants excelled in multiple areas,with a high overall satisfaction rate.95.28%of participants were able to develop hospital infection monitoring plans based on national infection control policies,demonstrating a good understanding and execution of these policies.94.09%of participants were familiar with high-risk populations and key departments in the hospital.91.73%of participants were able to establish monitoring scopes based on the trends of multidrug-resistant bacteria and conduct information monitoring,reflecting strong response capabilities.92.91%of participants were able to collaborate with relevant departments to conduct bacterial resistance monitoring,showing a good team spirit.94.49%of participants were able to perform targeted monitoring,including surgical site infections,indicating that they have effective monitoring strategies.91.34%of participants were able to collect and organize monitoring data and establish a systematic database,demonstrating good data management skills.90.16%of participants were able to interpret laws and regulations related to hospital infection management,indicating a high level of legal knowledge.89.37%of participants generally possessed good communication skills.92.52%of participants were able to guide medical staff on occupational safety and protective knowledge,showing an emphasis on occupational health.Participants demonstrated a strong desire to learn and innovate,with 87.01%actively participating in continuing education and research activities,reflecting a pursuit of professional development.Conclusion:Based on the results of the two rounds of expert consultations,a competency evaluation model for infection control personnel in TCM hospitals was formed.Through the analytic hierarchy process,the weight coefficients of various indicators at different levels in the model were obtained,and the research results have good scientific validity and reliability.展开更多
Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide coope...Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.展开更多
In this work,iron-doped carbon dots(Fe-CDs)with strong peroxidase-mimicking activity were synthesized for tumor-specific therapy.Their intrinsic red fluorescence enabled high-contrast cellular imaging,revealing prefer...In this work,iron-doped carbon dots(Fe-CDs)with strong peroxidase-mimicking activity were synthesized for tumor-specific therapy.Their intrinsic red fluorescence enabled high-contrast cellular imaging,revealing preferen⁃tial mitochondrial accumulation.In the acidic and hydrogen peroxide(H_(2)O_(2))-rich tumor microenvironment,Fe-CDs catalyzed hydroxyl radical(·OH)generation,inducing oxidative stress and lipid peroxidation,ultimately triggering ferroptosis.In vitro and in vivo studies demonstrated potent tumor inhibition.Furthermore,Fe-CDs exhibited excel⁃lent biocompatibility with no significant systemic toxicity.By integrating fluorescence imaging and catalytic therapy,this study presents a promising nanoplatform for tumor treatment and ferroptosis research.展开更多
文摘Active disturbance rejection control(ADRC)exhibits notable resilience against both internal and external disturbances.Its straightforward implementation further enhances its appeal for controlling a diverse class of systems.However,the high-gain nature of the extended state observer,which is the core of ADRC,may degrade performance when faced with high-frequency sensing noise—a common challenge in real-world settings.This article addresses this issue through a specifically placed and particularly designed low-pass filterwhile preserving the ease of implementation characteristic of ADRC.This article proposes a simple tuning method for the filter-controller structure to improve the scheme’s design process.Theoretical results simplify the design process based on the Routh–Hurwitz criterion such that the additional low-pass filter does not affect the closedloop stability.The maximum power point tracking task on a wind turbine—a nonlinear system requiring the measurement of inherently noisy signals,such as electrical currents—is addressed to illustrate the design process of the proposed approach.Real-time experiments on a laboratory platform emulating a Permanent Magnet Synchronous Generator-based wind turbine endorse the enhanced scheme’s effectiveness in mitigating high-frequency sensing noise.
基金supported by Weifang Science and Technology Development Plan Project(Soft Science,2022RKX054)Shenzhen Elite Talent Project(JY2024-2).
文摘With the rapid development of the medical industry,ensuring patient safety and improving medical quality have led to the development of a very important aspect:hospital infection control.This paper intends to evaluate the job competencies of infection prevention and control personnel in Chinese medicine hospitals through an analysis of the necessity of such competencies,the establishment of criteria for evaluation,and the exploration of methods for implementation.This paper proposes an effective evaluation system on the basis of recent research findings and some recommendations for how to improve infection management in these hospitals.This study provides suggestions for the training and management of staff in infection prevention and control through a review of the relevant literature within the context of Chinese medicine hospitals.
文摘Objective:To investigate the association between diagnosis delays and mortality in patients with haemorrhagic fever in Upper Southern Thailand.Methods:A hospital-based case control study was conducted between December 2019 and January 2020.Cases were defined as patients who had been diagnosed with haemorrhagic fever and died during hospitalization,while controls were patients with similar conditions who survived.Medical records were retrospectively reviewed,with the primary variable being a diagnosis delay of more than three days after the onset of illness.The outcome of interest was mortality during hospitalization.Data analysis involved descriptive statistics and multiple logistic regression.Results:A total of 38815 haemorrhagic fever cases were reported from 2014 to 2019.The case-to-control ratio was 1:3,comprising 66 cases and 198 controls.Among 66 cases and 198 controls,the median(IQR)time from illness onset to diagnosis was 4(4)days in cases vs.1(0)day in controls.Diagnosis delays significantly increased mortality risk[adjusted OR(aOR)5.60,95%CI 2.74-11.46].Other risk factors for mortality included age≤5 years(aOR 16.15,95%CI 3.70-70.42)and overweight status(aOR 3.43,95%CI 1.57-7.52).Conclusions:Delayed diagnosis in patients with haemorrhagic fever was strongly associated with higher mortality rates.These findings highlight the critical importance of early diagnosis to reduce mortality in haemorrhagic fever cases.
基金financial support provided by the Natural Science Foundation of Hebei Province,China(No.E2024105036)the Tangshan Talent Funding Project,China(Nos.B202302007 and A2021110015)+1 种基金the National Natural Science Foundation of China(No.52264042)the Australian Research Council(No.IH230100010)。
文摘Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.
基金Project supported by the National Natural Science Foundation of China(Nos.10772159 and 10802030)the Research Fund for Doctoral Program of Higher Education of China(No.20060335125)
文摘We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.
基金This work is supported by the National Natural Science Foundation of China (No. 60528007, 10372002, 60274001, 60304003), the National KeyBasic Research and Development Program (No. 2002CB312200).
文摘A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient conditions are presented on the stabilization of NCSs. Stabilizing state/output feedback controllers can be constructed by using the feasible solutions of some linear matrix inequalities （LMIs）. The merit of our proposed approach is that the behavior of the NCSs can be studied by considering switched system without augmenting the system. A simulation example is worked out to illustrate the effectiveness of the proposed approach.
文摘With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.
文摘Many physical processes have nonlinear behavior which can be well represented by a polynomial NARX or NARMAX model. The identification of such models has been widely explored in literature. The majority of these approaches are for the open-loop identification. However, for reasons such as safety and production restrictions, open-loop identification cannot always be done. In such cases, closed-loop identification is necessary. This paper presents a two-step approach to closed-loop identification of the polynomial NARX/NARMAX systems with variable structure control （VSC）. First, a genetic algorithm （GA） is used to maximize the similarity of VSC signal to white noise by tuning the switching function parameters. Second, the system is simulated again and its parameters are estimated by an algorithm of the least square （LS） family. Finally, simulation examples are given to show the validity of the proposed approach.
基金Supported by the National Natural Science Foundation of China （61174114, 60574047）, the National High Technology Re-search and Development Program of China （2007AA04Z168） and the Research Fund for the Doctoral Program of Higher Education of China （20120101130016）.
文摘A multi-loop constrained model predictive control scheme based on autoregressive exogenous-partial least squares(ARX-PLS) framework is proposed to tackle the high dimension, coupled and constraints problems in industry processes due to safety limitation, environmental regulations, consumer specifications and physical restriction. ARX-PLS decoupling character enables to turn the multivariable model predictive control(MPC) controller design in original space into the multi-loop single input single output(SISO) MPC controllers design in latent space.An idea of iterative method is applied to decouple the constraints latent variables in PLS framework and recursive least square is introduced to identify ARX-PLS model. This algorithm is applied to a non-square simulation system and a stirred reactor for ethylene polymerizations comparing with adaptive internal model control(IMC) method based on ARX-PLS framework. Its application has shown that this method outperforms adaptive IMC method based on ARX-PLS framework to some extent.
文摘In order to improve the brake performance of a dual independent electric drive tracked vehicle,a dynamic model for braking situation was established.Then,a sliding model controller(SMC)with an auxiliary system was designed to control the slip and its effectiveness was proved.A hardware-in-loop simulation through MATLAB/XPC was compared with the normal SMC and normal integral sliding mode controller(ISMC),the results show that SMC with the auxiliary system has a better performance:a smaller overshoot and steady state error.The disturbance is suppressed effectively.In the initial speed of 65.km/h,the brake distance was shortened by 3.4%and 6.8%compared with the other two methods,respectively.Finally,initial speeds of 30-36.km/h tests was carried out on a flat soil road.Compared with a no-control brake,the displacement was shortened by 1.8.m.It demonstrates the effectiveness of the slip-control strategy.In the same situation,the error between the simulation and test is 18.1%,which validates the accuracy of models.
文摘In the railway industry, re-adhesion control plays an important role in attenuating the slip occurrence due to the low adhesion condition in the wheel-rail inter- action. Braking and traction forces depend on the normal force and adhesion coefficient at the wheel-rail contact area. Due to the restrictions on controlling normal force, the only way to increase the tractive or braking effect is to maximize the adhesion coefficient. Through efficient uti- lization of adhesion, it is also possible to avoid wheel-rail wear and minimize the energy consumption. The adhesion between wheel and rail is a highly nonlinear function of many parameters like environmental conditions, railway vehicle speed and slip velocity. To estimate these unknown parameters accurately is a very hard and competitive challenge. The robust adaptive control strategy presented in this paper is not only able to suppress the wheel slip in time, but also maximize the adhesion utilization perfor- mance after re-adhesion process even if the wheel-rail contact mechanism exhibits significant adhesion uncer- tainties and/or nonlinearities. Using an optimal slip velocity seeking algorithm, the proposed strategy provides a satisfactory slip velocity tracking ability, which was demonstrated able to realize the desired slip velocity without experiencing any instability problem. The control torque of the traction motor was regulated continuously to drive the railway vehicle in the neighborhood of the opti- mal adhesion point and guarantee the best traction capacity after re-adhesion process by making the railway vehicle operate away from the unstable region. The results obtained from the adaptive approach based on the second- order sliding mode observer have been confirmed through theoretical analysis and numerical simulation conducted in MATLAB and Simulink with a full traction model under various wheel-rail conditions.
文摘Due to the special features of great inertia, pure lag and non-linearity provided with wind turbine, coupled with complex and variable working condition, it is difficult to achieve satisfactory control results simply by employing traditional PID, which has the drawbacks such as adjustment inconvenience, poor anti-interference, and large overshoot, and prolonged adjust span. This paper puts forward one type of improved controller combining Fuzzy Control with PID Control. With larger speed deviation, the controller emphasizes Fuzzy Control to speed system response;with less speed deviation, the controller emphasizes PID Control to improve control accuracy. Simulation Test directing at the algorithm is based on the Bladed software, with the positive result of improved dynamic and static performance of wind turbine under large disturbance.
基金financially supported by the National Key Research and Development Program of China(2022YFB3803304)National Natural Science Foundation of China(U23B20153,U23A20138)+5 种基金Tsinghua University Initiative Scientific Research Program(20221080065,20223080044)Independent Innovative Research Program(ZK20230101)Department of Electrical Engineering,Tsinghua University,State Key Laboratory of Power System and Generation Equipment(Nos.SKLD21Z03 and SKLD20M03)China Postdoctoral Science Foundation(2023M741888)The Chinese Thousand Talents Program for Young ProfessionalsState Grid Corporation of China,National Bio Energy Co.Ltd.,grant no.52789922000D.
文摘High power conversion efficiency(PCE)flexible perovskite solar cells(FPSCs)are highly desired power sources for aerospace crafts and flexible electronics.However,their PCEs still lag far behind their rigid counterparts.Herein,we report a high PCE FPSC by controllable growth of a SnO_(2)electron transport layer through constant pH chemical bath deposition(CBD).The application of SnSO_(4)as tin source enables us to perform CBD without strong acid,which in turn makes it applicable to acid-sensitive flexible indium tin oxide.Furthermore,a mild and controllable growth environment leads to uniform particle growth and dense SnO_(2)deposition with full coverage and reproducibility,resulting in a record PCE of up to 25.09%(certified 24.90%)for FPSCs to date.The as-fabricated FPSCs exhibited high durability,maintaining over 90% of their initial PCE after 10000 bending cycles.
文摘This paper presents a comparative study of different decoupling control schemes for a two-input, two-output(TITO) binary distillation column via proportional-integral(PI)controller. The key idea behind this paper is designing two novel fuzzy decoupling schemes that depend on human knowledge,instead of the system mathematical model used in conventional decoupling schemes. Based on conventional and inverted decoupling schemes, fuzzy and inverted fuzzy decoupling schemes are developed. The control effect is compared using simulation results for the proposed two schemes with conventional decoupling and inverted decoupling. The proposed fuzzy decoupling schemes are easy to realize and simple to design, besides they have a good decoupling capability. Two methods are used to prove asymptotic stability of each loop and the entire closed-loop system by applying the proposed fuzzy decoupling-based PI controller.The Wood and Berry model of a binary distillation column is used to illustrate the applicability of the proposed schemes.
文摘In this work, the objectives were to provide a scientific basis for environmental governance and to ensure staff health by real-time monitoring of indoor air quality of the pathology department. Using eagle eye environment monitor to make a real-time dynamic monitoring of the air quality of the pathological technical room for 30 days, the paper records the monitoring data of PM 2.5, PM 10, formaldehyde, CO2, total volatile organic compounds (TVOC) every day at Beijing time 3 a.m, 10 am, 1 pm, 4 pm, and 10 pm, and makes a summarization and analysis. The average value of CO2 concentration of the 5 time points is (0.05 ± 0.01)%, and each time point concentration are different (P 0.05);the average TVOC concentration of the 5 time points is (0.08 + 0.31) mg/m3. They are all different between the concentration at each time point (P 2 and NO are not checked out. Through the real-time online monitoring of the pathology room, we find that the formaldehyde concentration of different time periods is far more than the safety value standard, and the concentration of formaldehyde, CO2, PM 2.5, PM 10 and total volatile organic compound (TVOC) is different at different time periods, and the concentrations at working time are higher than the non-working time. We must take effective measures to control the concentration of harmful gases in order to ensure the staff’s health.
文摘The problem of adaptive generalized predictive control which consists of output prediction errors for a class of switched systems is studied.The switching law is determined by the output predictive errors of a finite number of subsystems.For the single subsystem and multiple subsystems cases,it is proved that the given direct algorithm of generalized predictive control guarantees the global convergence of the system.This algorithm overcomes the inherent drawbacks of the slow convergence and large transient errors for the conventional adaptive control.
文摘The aim of the work was the assessment of capability for the change control in the structure of a compact material of pelletized heatproof nickel alloy grade EP741NP using the atomic emission method. The proposed method of evaluation is based on the statistical significance of the analytical response differences during atomic emission spectroscopy of solid specimens taken from one sample before and after heat treatment using the instruments AtomComp 81 and ARL 4460 with a high-voltage spark excitation. For calculations, the ratio of the line intensity of the analyzed element to the line intensity of the main sample component (in our case Ni<sub>2254</sub>) was used. The difference confidence estimation was made by the averages comparison method in a variance analysis. The study results are presented on the effect of material structure on analytical response during atomic emission spectroscopy of solid specimens. It was proved that the samples before and after heat treatment give statistically differing results while analyzed.
基金supported by Weifang Science and Technology Development Plan Project(Soft Science,2022RKX054)Shenzhen Elite Talent Project(JY2024-2).
文摘Background:This study uses a literature review and the Delphi expert consultation method to construct a competency evaluation model for infection control personnel in traditional Chinese medicine(TCM)hospitals.The aim is to strengthen infection control management in TCM hospitals,assess the competency of infection control personnel in their positions,and assist them in identifying the competencies that need improvement.Methods:Based on the literature research method and the Delphi expert consultation method,a competency model for the position was constructed through two rounds of expert consultations,analyzing the relationships between various factors and establishing a hierarchical structure model.Pairwise comparisons were made among the elements at the same level to construct a judgment matrix.Through the analytic hierarchy process,the weight coefficients of the indicators at each level in the competency model were obtained.Results:This study conducted a comprehensive assessment of various capabilities and practices related to hospital infection control.The survey results indicate that participants excelled in multiple areas,with a high overall satisfaction rate.95.28%of participants were able to develop hospital infection monitoring plans based on national infection control policies,demonstrating a good understanding and execution of these policies.94.09%of participants were familiar with high-risk populations and key departments in the hospital.91.73%of participants were able to establish monitoring scopes based on the trends of multidrug-resistant bacteria and conduct information monitoring,reflecting strong response capabilities.92.91%of participants were able to collaborate with relevant departments to conduct bacterial resistance monitoring,showing a good team spirit.94.49%of participants were able to perform targeted monitoring,including surgical site infections,indicating that they have effective monitoring strategies.91.34%of participants were able to collect and organize monitoring data and establish a systematic database,demonstrating good data management skills.90.16%of participants were able to interpret laws and regulations related to hospital infection management,indicating a high level of legal knowledge.89.37%of participants generally possessed good communication skills.92.52%of participants were able to guide medical staff on occupational safety and protective knowledge,showing an emphasis on occupational health.Participants demonstrated a strong desire to learn and innovate,with 87.01%actively participating in continuing education and research activities,reflecting a pursuit of professional development.Conclusion:Based on the results of the two rounds of expert consultations,a competency evaluation model for infection control personnel in TCM hospitals was formed.Through the analytic hierarchy process,the weight coefficients of various indicators at different levels in the model were obtained,and the research results have good scientific validity and reliability.
基金supported by the National Natural Science Foundation of China under Grant 52277190the Major Science and Technology Projects of China Railway Electrification Engineering Group Co.,LTD.(20192001148).
文摘Continuous co-phase traction power system is an effective method to eliminate neutral sections and provide high quality power for both the public grid and the catenary.The substations have the ability to provide cooperative support to each other to reduce capacity and improve system reliability.A fast power control method for substations is needed due to rapid load changes and low overload capability of the system.This paper proposes a fast power control method based on high-speed communication between substations,with additional transient power control to significantly improve the dynamic response of the system.
文摘In this work,iron-doped carbon dots(Fe-CDs)with strong peroxidase-mimicking activity were synthesized for tumor-specific therapy.Their intrinsic red fluorescence enabled high-contrast cellular imaging,revealing preferen⁃tial mitochondrial accumulation.In the acidic and hydrogen peroxide(H_(2)O_(2))-rich tumor microenvironment,Fe-CDs catalyzed hydroxyl radical(·OH)generation,inducing oxidative stress and lipid peroxidation,ultimately triggering ferroptosis.In vitro and in vivo studies demonstrated potent tumor inhibition.Furthermore,Fe-CDs exhibited excel⁃lent biocompatibility with no significant systemic toxicity.By integrating fluorescence imaging and catalytic therapy,this study presents a promising nanoplatform for tumor treatment and ferroptosis research.
