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Dynamic Event-Triggered Control of Continuous-Time Systems With Random Impulses

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IEEE/CAA Journal of Automatica Sinica 2023年第12期10卷 2292-2299页

作者： meng Yao Guoliang wei the College of Science University of Shanghai for Science and TechnologyShanghai 200093China the Business School University of Shanghai for Science and TechnologyShanghai 200093China

In this paper,the networked control problem under event-triggered schemes is considered for a class of continuoustime linear systems with random impulses.In order to save communication costs and lighten communication burden,a dynamic event-triggered scheme whose threshold parameter is dynamically adjusted by a given evolutionary rule,is employed to manage the transmission of data packets.Moreover,the evolution of the threshold parameter only depends on the sampled measurement output,and hence eliminates the influence of impulsive signals on the event-triggered mechanism.Then,with the help of a stochastic analysis method and Lyapunov theory,the existence conditions of desired controller gains are received to guarantee the corresponding input-to-state stability of the addressed system.Furthermore,according to the semi-definite programming property,the desired controller gains are calculated by resorting to the solution of three linear matrix inequalities.In the end,the feasibility and validity of the developed control strategy are verified by a simulation example.

关键词： mechanism. desired hence

Applications of thermostatically controlled loads for demand response with the proliferation of variable renewable energy

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Frontiers in Energy 2022年第1期16卷 64-73页

作者： meng SONG wei SUN Jiangsu Provincial Key Laboratory of Smart Grid Technology and Equipment Southeast UniversityNanjing 210096China Department of Electrical and Computer Engineering University of Central FloridaOrlandoFL 32816USA

More flexibility is desirable with the proliferation of variable renewable resources for balancing supply and demand in power systems.Thermostatically controlled loads(TCLs)attract tremendous attentions because of their specific thermal inertia capability in demand response(DR)programs.To effectively manage numerous and distributed TCLs,intermediate coordinators,e.g.,aggregators,as a bridge between end users and dispatch operators are required to model and control TCLs for serving the grid.Specifically,intermediate coordinators get the access to fundamental models and response modes of TCLs,make control strategies,and distribute control signals to TCLs according the requirements of dispatch operators.On the other hand,intermediate coordinators also provide dispatch models that characterize the external characteristics of TCLs to dispatch operators for scheduling different resources.In this paper,the bottom-up key technologies of TCLs in DR programs based on the current research have been reviewed and compared,including fundamental models,response modes,control strategies,dispatch models and dispatch strategies of TCLs,as well as challenges and opportunities in future work.

关键词： thermostatically controlled load demand response renewable energy power system operation

Hypoxic-ischemic encephalopathy induced cognitive decline secondary to upper gastrointestinal bleeding: a case report

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World Journal of Emergency Medicine 2023年第4期14卷 335-337页

作者： Rui wei Danyang Jing Xiangchen meng Hongtao wei Department of International Medical Center Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China Department of Critical Care Medicine Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China Department of Gastroenterology Beijing Friendship HospitalCapital Medical UniversityBeijing 100050China

Hypoxic-ischemic encephalopathy(HIE)occurs more in neonatal and rarely in adults.In adults,HIE is commonly caused by carbon monoxide(CO)poisoning,shock,cardiac arrest,respiratory depression,anesthesia and drug overdose.[1–3]In patients with acute gastrointestinal bleeding,decreased circulating blood supply causes cerebral ischemia and hypoxia,leading to dizziness,syncope and even sudden death.However,these conditions are more common especially in elderly patients with cerebrovascular stenosis,acute massive blood loss,using hemostatic agents,and high-risk factors of cardiovascular and cerebrovascular disease.[4]Here,we reported a middle-aged male patient,who was diagnosed with HIE after upper gastrointestinal bleeding without these high-risk factors.

关键词： gastrointestinal acute bleeding

Influence of different portal vein branches on hepatic encephalopathy during intrahepatic portal shunt via jugular vein

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World Journal of Gastroenterology 2022年第31期28卷 4467-4470页

作者： Xin Yao Sheng He Meng WEI Jian-Ping Qin Department of Gastroenterology General Hospital of Western Theater CommandChengdu 610083Sichuan ProvinceChina

This letter is regarding the study titled‘Targeted puncture of left branch of intrahepatic portal vein in transjugular intrahepatic portosystemic shunt(TIPS)to reduce hepatic encephalopathy’.Prior to the approval of TIPS dedicated stents(Viatorr stents)in China in October 2015,Fluency covered stents were typically used.As Fluency covered stents have a strong support force and axial elastic tension,a‘cap’may form if the stent is located too low at the end of the hepatic vein or too short at the end of the portal vein during surgery,leading to stent dysfunction.Since the blood shunted by the stent is from the main trunk of the portal vein,the correlation between the incidence of postoperative hepatic encephalopathy and the location of the puncture target(left or right portal vein branch)is worth discussion.Notably,no studies in China or foreign countries have proven the occurrence of left and right blood stratification after the accumulation of splenic vein and mesenteric blood flow in the main trunk of the portal vein in patients with cirrhotic portal hypertension.

关键词： Viatorr stent Portosystemic shunt Transjugular intrahepatic Hypertension portal Left and right portal vein branches

Influence of Charging Oil Condition on Torque Converter Cavitation Characteristics

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 236-249页

作者： Cheng Liu meng Guo Qingdong Yan wei wei School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401122China Advanced Technology Research Institute Beijing Institute of TechnologyJinan 250307China

Cavitation inside a torque converter induces noise,vibration and even failure,and these effects have been disregarded in previous torque converter design processes.However,modern torque converter applications require attention to this issue because of its high-speed and high-capacity requirements.Therefore,this study investigated the cavitation effect on a torque converter using both numerical and experimental methods with an emphasis on the influence of the charging oil feed location and charge pressure.Computational fluid dynamics(CFD)models were established to simulate the transient cavitation behaviour in the torque converter using different charging oil pressures and inlet arrangements and testing against a base case to validate the results.The CFD results suggested that cavitating bubbles mainly takes place in the stator of the torque converter.The transient cavitation CFD model yielded good agreement with the experimental data,with an error of 7.6%in the capacity constant and 7.4%in the torque ratio.Both the experimental and numerical studies showed that cavitation induced severe capacity degradation,and that the charge pressure and charging oil configuration significantly affects both the overall hydrodynamic performance and the fluid behaviour inside the torque converter because of cavitation.Increasing the charge pressure and charging the oil from the turbine-stator clearance were found to suppress cavitation development and reduce performance degradation,especially in terms of the capacity constant.This study revealed the fluid field mechanism behind the influence of charging oil conditions on torque converter cavitation behaviour,providing practical guidelines for suppressing cavitation in torque converter.

关键词： Torque converter Cavitation CFD Transient flow

Application of machine learning in predicting the rate-dependent compressive strength of rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1356-1365页

作者： Mingdong wei Wenzhao meng Feng Dai wei Wu School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China

Accurate prediction of compressive strength of rocks relies on the rate-dependent behaviors of rocks, and correlation among the geometrical, physical, and mechanical properties of rocks. However, these properties may not be easy to control in laboratory experiments, particularly in dynamic compression experiments. By training three machine learning models based on the support vector machine(SVM), backpropagation neural network(BPNN), and random forest(RF) algorithms, we isolated different input parameters, such as static compressive strength, P-wave velocity, specimen dimension, grain size, bulk density, and strain rate, to identify their importance in the strength prediction. Our results demonstrated that the RF algorithm shows a better performance than the other two algorithms. The strain rate is a key input parameter influencing the performance of these models, while the others(e.g. static compressive strength and P-wave velocity) are less important as their roles can be compensated by alternative parameters. The results also revealed that the effect of specimen dimension on the rock strength can be overshadowed at high strain rates, while the effect on the dynamic increase factor(i.e. the ratio of dynamic to static compressive strength) becomes significant. The dynamic increase factors for different specimen dimensions bifurcate when the strain rate reaches a relatively high value, a clue to improve our understanding of the transitional behaviors of rocks from low to high strain rates.

关键词： Machine learning Rock dynamics Compressive strength Strain rate

Reinforcement learning-based unknown reference tracking control of HMASs with nonidentical communication delays

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Science China(Information Sciences) 2023年第7期66卷 46-57页

作者： Yong XU Zheng-Guang WU wei-wei CHE Deyuan meng School of Automation Beijing Institute of Technology Institute of Cyber-Systems and Control Zhejiang University College of Mathematics and Computer Science Zhejiang Normal University Department of Automation Qingdao University School of Automation Science and Electrical Engineering Beihang University(BUAA)

This paper focuses on the optimal output synchronization control problem of heterogeneous multiagent systems(HMASs) subject to nonidentical communication delays by a reinforcement learning method.Compared with existing studies assuming that the precise model of the leader is globally or distributively accessible to all or some of the followers, the leader’s precise dynamical model is entirely inaccessible to all the followers in this paper. A data-based learning algorithm is first proposed to reconstruct the leader’s unknown system matrix online. A distributed predictor subject to communication delays is further devised to estimate the leader’s state, where interaction delays are allowed to be nonidentical. Then, a learning-based local controller, together with a discounted performance function, is projected to reach the optimal output synchronization. Bellman equations and game algebraic Riccati equations are constructed to learn the optimal solution by developing a model-based reinforcement learning(RL) algorithm online without solving regulator equations, which is followed by a model-free off-policy RL algorithm to relax the requirement of all agents’ dynamics faced by the model-based RL algorithm. The optimal tracking control of HMASs subject to unknown leader dynamics and communication delays is shown to be solvable under the proposed RL algorithms. Finally, the effectiveness of theoretical analysis is verified by numerical simulations.

关键词： heterogeneous multiagent systems HMAS reinforcement learning RL optimal output synchronization communication delays

A Study on Enhancing Chip Detection Efficiency Using the Lightweight Van-YOLOv8 Network

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Computers, Materials & Continua 2024年第4期79卷 531-547页

作者： meng Huang Honglei wei Xianyi Zhai School of Mechanical Engineering and Automation Dalian Polytechnic UniversityDalian116034China

In pursuit of cost-effective manufacturing,enterprises are increasingly adopting the practice of utilizing recycled semiconductor chips.To ensure consistent chip orientation during packaging,a circular marker on the front side is employed for pin alignment following successful functional testing.However,recycled chips often exhibit substantial surface wear,and the identification of the relatively small marker proves challenging.Moreover,the complexity of generic target detection algorithms hampers seamless deployment.Addressing these issues,this paper introduces a lightweight YOLOv8s-based network tailored for detecting markings on recycled chips,termed Van-YOLOv8.Initially,to alleviate the influence of diminutive,low-resolution markings on the precision of deep learning models,we utilize an upscaling approach for enhanced resolution.This technique relies on the Super-Resolution Generative Adversarial Network with Extended Training(SRGANext)network,facilitating the reconstruction of high-fidelity images that align with input specifications.Subsequently,we replace the original YOLOv8smodel’s backbone feature extraction network with the lightweight VanillaNetwork(VanillaNet),simplifying the branch structure to reduce network parameters.Finally,a Hybrid Attention Mechanism(HAM)is implemented to capture essential details from input images,improving feature representation while concurrently expediting model inference speed.Experimental results demonstrate that the Van-YOLOv8 network outperforms the original YOLOv8s on a recycled chip dataset in various aspects.Significantly,it demonstrates superiority in parameter count,computational intricacy,precision in identifying targets,and speed when compared to certain prevalent algorithms in the current landscape.The proposed approach proves promising for real-time detection of recycled chips in practical factory settings.

关键词： Lightweight neural networks attention mechanisms image super-resolution enhancement feature extraction small object detection

Chiral Dienes: From Ligands to FLP Catalysts

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Chinese Journal of Chemistry 2022年第9期40卷 1109-1116页

作者： Xiangqing Feng wei meng Haifeng Du Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes.This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis.Herein,we willbriefly summarize our studies on the development of chiral diene ligands for transition-metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal-free hydrogenations and hydrosilylations.Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd-catalyzed asymmetric reactions.With these ligands in hand,we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers'borane.These catalysts proved to be highly ffective for asymmetric metal-free hydrogenations and hydrosilylations of imines,ilyl enol ethers,ketones,and aromatic N-heterocycles.

关键词： Asymmetric catalysis Chiral dienes Frustrated Lewis pair Conjugated addition Hydrogenation