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Effect of cognitive training on brain dynamics

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Chinese Physics B 2024年第2期33卷 529-536页

作者：吕贵阳徐天勇陈飞燕朱萍王淼何国光 School of Physics Zhejiang UniversityHangzhou 310027China

The human brain is highly *** training is usually used to modify functional connectivity of brain ***,the structures of brain networks may determine its dynamic behavior which is related to human cognitive *** study the effect of functional connectivity on the brain dynamics,the dynamic model based on functional connections of the brain and the Hindmarsh–Rose model is utilized in this *** resting-state fMRI data from the experimental group undergoing abacus-based mental calculation(AMC)training and from the control group are used to construct the functional brain *** dynamic behavior of brain at the resting and task states for the AMC group and the control group are simulated with the above-mentioned dynamic *** the resting state,there are the differences of brain activation between the AMC group and the control group,and more brain regions are inspired in the AMC group.A stimulus with sinusoidal signals to brain networks is introduced to simulate the brain dynamics in the task *** dynamic characteristics are extracted by the excitation rates,the response intensities and the state *** change in the functional connectivity of brain networks with the AMC training would in turn improve the brain response to external stimulus,and make the brain more efficient in processing tasks.

关键词： brian dynamics functional brain networks cognitive training abacus-based mental calculation

Game-theoretical Model for Dynamic Defense Resource Allocation in Cyber-physical Power Systems Under Distributed Denial of Service Attacks

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 41-51页

作者： Bingjing Yan Pengchao Yao Tao Yang Boyang Zhou Qiang Yang the College of Electrical Engineering Zhejiang UniversityHangzhou 310027China zhejiang Lab Hangzhou 311100China

Electric power grids are evolving into complex cyber-physical power systems(CPPSs)that integrate advanced information and communication technologies(ICTs)but face increasing cyberspace threats and *** study considers CPPS cyberspace security under distributed denial of service(DDoS)attacks and proposes a nonzero-sum game-theoretical model with incomplete information for appropriate allocation of defense resources based on the availability of limited *** time delay is applied to quantify the expected utility as CPPSs have high time requirements and incur massive damage DDoS *** resource allocation strategies are adopted by attackers and defenders under the three cases of attack-free,failed attack,and successful attack,which lead to a corresponding consumption of resources.A multidimensional node value analysis is designed to introduce physical and cybersecurity *** experiments and numerical results demonstrate the effectiveness of the proposed model for the appropriate allocation of defense resources in CPPSs under limited resource availability.

关键词： Game theory complex cyber-physical power system(CPPS) multidimensional evaluation distributed denial of service(DDoS)attack

Magneto-optical isotope enrichment of potassium-40 with transverse cooling

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Chinese Optics Letters 2024年第7期22卷 1-5页

作者： Shangjin Li Zixuan Zeng Bo Yan School of Physics Zhejiang UniversityHangzhou 310027China

Isotope shifts among different isotopes can be effectively addressed using narrow-linewidth lasers,facilitating laser isotope separation and achieving significant enrichment at a single *** separation of potassium isotopes,employing optical pumping and magnetic deflection,has proven to be *** further improve the enrichment of ^(40)K,we introduce 2D transverse cooling to minimize the divergence *** this modification,we demonstrate enrichment of ^(40)K,elevating it from 0.012%to 12%–20%.This represents an enrichment increase by three orders of magnitude,surpassing our previous result by one *** method is particularly well-suited for isotope enrichment of elements with extremely low abundance.

关键词： isotope separation potassium isotopes two-dimensional transverse cooling.

Experimental study on spray characteristics of aviation kerosene RP-3 in a radial rotary atomizer

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Acta Mechanica Sinica 2024年第7期40卷 66-79页

作者： Jing Hou Zhixin Zhu Chengbiao Ma Gaogfeng Wang Elsayed Barakat School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027China

In this work,the spray behaviors of a rotary atomizer with round-shaped injection orifices are experimentally investigated to study the breakup mechanism and spray characteristics using RP-3 as the liquid *** breakup process of the liquid is visualized by the backlight shadow imaging method,which also provides the measurements of liquid breakup length and penetration *** injection mode of the liquid film is observed using the front-light illumination *** droplet size and distribution are measured using the laser particle size analyzer at various radial *** typical breakup modes are identified:the ligament breakup mode,bag breakup mode,and shear breakup *** Weber number(Wed)and momentum flux ratio(q)are used to elaborate the liquid breakup *** of droplet sizing indicate that the Sauter mean diameter decreases with a higher rotational speed and slightly varies with the volume flow rate.A correlation between liquid breakup modes and non-dimensional droplet size is established based on Wed and *** study presents some significance for understanding the impacts of the rotational speed and volume flow rates on the spray performance of actual aviation fuels in rotary atomizers.

关键词： Rotary atomizer Breakup mode Breakup length Droplet sizing

Analysis of piezoelectric semiconductor fibers under gradient temperature changes

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 311-320页

作者： Shuangpeng LI Ruoran CHENG Nannan MA Chunli ZHANG Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China

Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor *** fiber-like structures have wide applications in multi-functional semiconductor *** this paper,a one-dimensional(1D)theoretical model is established to describe the piezotronic responses of a PS fiber under gradient temperature *** theoretical model aims to explain the mechanism behind the resistance change caused by such gradient temperature *** results demonstrate that a gradient temperature change significantly affects the physical fields within the PS fiber,and can induce changes in its surface *** provides important theoretical guidance on the development of piezotronic devices that are sensitive to temperature effects.

关键词： piezoelectric semiconductor(PS)fiber one-dimensional(1D)model piezotronic effect gradient temperature change

Study of the topological quantities of lattice QCD using a modified DCGAN frame

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Chinese Physics C 2024年第5期48卷 151-159页

作者：高璘应和平张剑波 School of Physics Zhejiang UniversityHangzhou 310027China

A modified deep convolutional generative adversarial network(M-DCGAN)frame is proposed to study the N-dimensional(ND)topological quantities in lattice QCD based on Monte Carlo(MC)*** construct a new scaling structure including fully connected layers to support the generation of high-quality high-dimensional images for the *** results suggest that the M-DCGAN scheme of machine learning will help to more efficiently calculate the 1D distribution of topological charge and the 4D topological charge density compared with MC simulation alone.

关键词： lattice QCD generative adversarial network topological charge density Wilson flow

Imitation Learning Based Real-time Decision-making of Microgrid Economic Dispatch Under Multiple Uncertainties

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1183-1193页

作者： Wei Dong Fan Zhang Meng Li Xiaolun Fang Qiang Yang School of Automation Hangzhou Dianzi UniversityHangzhou 310018China College of Electrical Engineering Zhejiang UniversityHangzhou 310027China

The intermittency of renewable energy generation,variability of load demand,and stochasticity of market price bring about direct challenges to optimal energy management of *** cope with these different forms of operation un-certainties,an imitation learning based real-time decision-mak-ing solution for microgrid economic dispatch is *** this solution,the optimal dispatch trajectories obtained by solv-ing the optimal problem using historical deterministic operation patterns are demonstrated as the expert samples for imitation *** improve the generalization performance of imita-tion learning and the expressive ability of uncertain variables,a hybrid model combining the unsupervised and supervised learn-ing is *** denoising autoencoder based unsupervised learning model is adopted to enhance the feature extraction of operation ***,the long short-term memory network based supervised learning model is used to efficiently characterize the mapping between the input space composed of the extracted operation patterns and system state variables and the output space composed of the optimal dispatch *** numerical simulation results demonstrate that under vari-ous operation uncertainties,the operation cost achieved by the proposed solution is close to the minimum theoretical *** with the traditional model predictive control method and basic clone imitation learning method,the operation cost of the proposed solution is reduced by 6.3%and 2.8%,respective-ly,overa test period of three months.

关键词： Energy management imitation learning datadriven decision economic dispatch

A learning-based control pipeline for generic motor skills for quadruped robots

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Journal of zhejiang university-Science A(Applied Physics & Engineering) 2024年第6期25卷 443-454页

作者： Yecheng SHAO Yongbin JIN Zhilong HUANG Hongtao WANG Wei YANG Center for X-Mechanics Zhejiang UniversityHangzhou310027China ZJU-hangzhou Global Scientific and Technological Innovation Center Hangzhou311200China State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang UniversityHangzhou310058China Institute of Applied Mechanics Zhejiang UniversityHangzhou310027China

Performing diverse motor skills with a universal controller has been a longstanding challenge for legged *** motion imitation-based reinforcement learning(RL)has shown remarkable performance in reproducing designed motor skills,the trained controller is only suitable for one specific type of *** synthesis has been well developed to generate a variety of different motions for character animation,but those motions only contain kinematic information and cannot be used for *** this study,we introduce a control pipeline combining motion synthesis and motion imitation-based RL for generic motor *** design an animation state machine to synthesize motion from various sources and feed the generated kinematic reference trajectory to the RL controller as part of the *** the proposed method,we show that a single policy is able to learn various motor skills ***,we notice the ability of the policy to uncover the correlations lurking behind the reference motions to improve control *** analyze this ability based on the predictability of the reference trajectory and use the quantified measurements to optimize the design of the *** demonstrate the effectiveness of our method,we deploy the trained policy on hardware and,with a single control policy,the quadruped robot can perform various learned skills,including automatic gait transitions,high kick,and forward jump.

关键词： Quadruped robot Reinforcement learning(RL) Motion synthesis Control

Distributed Event-triggered Control for Frequency Restoration in Islanded Microgrids with Reduced Trigger Condition Checking

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2156-2165页

作者： Yulin Chen Donglian Qi Zhenming Li Zhenyu Wang Xinyi Yang Jianliang Zhang College of Electrical Engineering Zhejiang UniversityHangzhou 310027China

For islanded microgrids(MGs),distributed control is regarded as a preferred alternative to centralized control for the frequency restoration of ***,distributed control with successive communication restricts the efficiency and resilience of the control *** address this issue,this paper proposes a distributed event-triggered control strategy for the frequency secondary control in islanded *** proposed event-triggered control is Zeno behavior free and enables each DG to update and propagate its state to neighboring DGs only when a specific“event”occurs,which significantly reduces the communication *** with the existing event-triggered control,a trigger condition checking period of the proposed event-triggered control is provided to reduce the computation burden when checking the trigger ***,using the aperiodicity and intermittent properties of the communication,a simple detection principle is proposed to detect and isolate the compromised communication links in a timely and economic fashion,which improves the resilience of the system against FDI ***,the control effectiveness of the proposed control scheme is validated by the simulation results of the tests on an MG with 4 DGs.

关键词： Distributed control event-triggered control islanded microgrid secondary control