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Influence of introducing Zr,Ti,Nb and Ce elements on externally solidified crystals and mechanical properties of high-pressure die-casting Al–Si alloy

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 147-153页

作者： Junjie Li Wenbo Yu Zhenyu Sun Weichen Zheng Liangwei Zhang Yanling Xue Wenning Liu Shoumei Xiong Center of Materials Science and engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Traffic&Transportation engineering Central South UniversityChangsha 410075China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China School of Materials Science and engineering Tsinghua UniversityBeijing 100084China

High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile *** can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated ***,the development of non-heat treatment Al alloys is becoming the hot *** addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of *** achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and *** influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic *** results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased ***,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical *** introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

关键词： aluminium alloy high-pressure die-casting externally solidified crystals non-heat treatment

Operating-Point Identification from Dimensions of Alternating Signal Based on Incremental Iterative Mapping Mechanism for Analyzing Dynamics of AC Systems

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CSEE Journal of Power and Energy Systems 2025年第1期11卷 163-172页

作者： Xiaoming Yuan Sicheng Wang School of Electrical and electronic engineering Huazhong University of Science and TechnologyWuhan430074China

Increasing occurrences of oscillations of unknown mechanisms in today's power systems ask for recalling the first principle of *** systems in general work with all units of supplies and loads to build up internal voltage of a certain amplitude/frequency,ensuring transferring and balancing of power in the system while subjected to varied *** dynamics following are therefore closed-loop iterations between power balancing-internal voltage relations in units and internal voltage-power relations in *** points and small disturbances associated will then have to be defined from such iterative processes with nonlinear relations among the increments that can be approximated at the initial period of disturbance,so linear system mathematics will be applicable for dynamic *** methodologies from varied fields are unfortunately not rooted from first principle physics and are therefore especially not suited for today's new scenario with increasing penetration of *** a small disturbance dynamic process of a converter interfaced system as an example,this paper thus aims to propose an operating-point identification methodology from dimensions of AC signal by first revealing the incremental iterative mapping mechanism from the first principle of operating,and by then clarifying the self-consistency of the relevant electrical variables,as well as relations among them during *** is recognized that during a certain time period following the disturbance,amplitude/frequency of internal voltage in the converter and active/reactive current at the network interface evolve in the form of the complex exponential,among which we can see linearizable weak-nonlinear relations,and thus should be defined as operating *** on the above operating points and relevant increments of the internal-voltage amplitude/frequency and active/reactive current,fundamental steps and challenges linearizing AC systems are finally su

关键词： AC systems linearization operating points self-consistency signal dimensions small disturbance dynamics.

Terahertz transmitter demonstration of the simultaneous transmission of optical and electrical terahertz band signals at 1 Tb/s bit rate and 50 m wireless delivery

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Science China Technological Sciences 2025年第3期68卷 384-386页

作者： Kaihui WANG Jianjun YU Chengzhen BIAN Junjie DING Jiao ZHANG Min ZHU Xiongwei YANG Weiping LI Yi WEI Mingxu WANG Qiutong ZHANG Ying WU Bo LIU Wen ZHOU Yuancheng CAI Bingchang HUA Mingzheng LEI Yucong ZOU Jianguo YU Feng ZHAO State Key Laboratory of ASIC and System Fudan University Purple Mountain Laboratories School of electronic engineering Beijing University of Posts and Telecommunications School of electronic engineering Xi'an University of Posts and Telecommunications

In recent years, free space optical communication (FSO) has been a hot topic in satellite-to-ground communications, inter-satellite communications,and wireless access networks [1–4]. It has the advantages of rich spectrum resources, no need for spectrum authorization, high spectrum efficiency verified by experiments, narrow beam angle, and low space loss under good weather. In point-to-point communications, the beam angle makes the FSO almost immune to multipath effects, and low-complexity Digital Signal Processing (DSP) algorithms can be used for recovery demodulation.

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An Effective Intrusion Detection System Based on the FSA-BGRU Hybrid Model

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China Communications 2025年第2期22卷 188-198页

作者： Deng Zaihui Li Zihang Guo Jianzhong Gan Guangming Kong Dejin School of electronic and Electrical engineering Wuhan Textile UniversityWuhan 430200China School of Computer Science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China School of Physics and electronic Information engineering Hubei Engineering UniversityXiaogan 432000China

Intrusion detection systems play a vital role in cyberspace *** this study,a network intrusion detection method based on the feature selection algorithm(FSA)and a deep learning model is developed using a fusion of a recursive feature elimination(RFE)algorithm and a bidirectional gated recurrent unit(BGRU).Particularly,the RFE algorithm is employed to select features from high-dimensional data to reduce weak correlations between features and remove redundant features in the numerical feature ***,a neural network that combines the BGRU and multilayer perceptron(MLP)is adopted to extract deep intrusion behavior ***,a support vector machine(SVM)classifier is used to classify intrusion *** proposed model is verified by experiments on the NSL-KDD *** results indicate that the proposed model achieves a 90.25%accuracy and a 97.51%detection rate in binary classification and outperforms other machine learning and deep learning models in intrusion *** proposed method can provide new insight into network intrusion detection.

关键词： bidirectional GRU feature selection intrusion detection system multilayer perceptron recursive feature elimination support vector machine

Differential-geometry-based multi-dimensional joint position-velocity estimation using Crab pulsar profile distortion

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Chinese Journal of Aeronautics 2025年第1期38卷 551-567页

作者： Jin LIU Huanzi ZHANG Xiaolin NING Xin MA School of electronic Information Wuhan University of Science and TechnologyWuhan 430081China School of Instrumentation and Optoelectronic engineering Beihang UniversityBeijing 100191China Hefei National Laboratory Hefei 230088China

The traditional orbit determination method based on pulsar profile distortion can determine the six elements of the ***,the estimation accuracies of these methods are limited and the computational load of a six-dimensional search is *** solve this problem,the differential-geometry-based Multi-dimensional Joint Position-Velocity Estimation(MJPVE)using Crab pulsar profile distortion is proposed in this ***,through theoretical analysis,it is found that the pulsar profile distortion caused by the initial state error in some joint positionvelocity directions is very *** other words,the accuracies of estimation in these directions are very ***,the search dimension can be reduced,which in turn greatly reduces the computational ***,we construct the chi-squared function of the pulsar profile with respect to the estimation error in joint position-velocity direction and use differential geometry to find the joint position-velocity directions corresponding to different degrees of ***,we utilize the grid search based on directory folding in these joint position-velocity directions corresponding to large degrees of distortion to obtain the joint position-velocity *** experimental results show that compared with the grouping bi-chi-squared inversion method,MJPVE has high precision and extensive navigation information.

关键词： Joint Position-Velocity Estimation Pulsars Profile Distortion Orbit Determination Differential Geometry

Thermo-Hydraulic Performances of Microchannel Heat Sinks with Different Types of Perforated Rectangular Blocks

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Fluid Dynamics & Materials Processing 2025年第1期21卷 87-105页

作者： Heng Zhao Honghua Ma Hui Liu Xiang Yan Huaqing Yu Yongjun Xiao Xiao Xiao School of Physics and electronic Information engineering Hubei Engineering UniversityXiaogan432000China Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and TechnologyWuhan430074China Institute of engineering and Technology Hubei University of Science and TechnologyXianning437100China

The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical *** geometrical configurations areexamined,particularly,the combinations of rectangular solid and perforated blocks,used to create a disturbancein the *** analysis focuses on several key aspects and related metrics,including the temperature distribution,the mean Fanning friction factor,the pressure drop,the Nusselt number,and the overall heat transfer coefficientacross a range of Reynolds numbers(80–870).It is shown that the introduction of such blocks significantlyenhances the heat transfer performances of the MCHS compared to the straight-through flow ***,a case is found where the Nusselt number increases by 2.3 times relative to the reference *** integrationof perforated blocks facilitates the generation of vorticity within the channel,promoting the mixing of coldand hot ***,MCHS incorporating perforated rectangular blocks exhibit more pronounced heat transferbenefits at Reynolds numbers smaller than 400.

关键词： Micro-channel heat sink(MCHS) perforated rectangular blocks thermal performance convection heat transfer

Anchoring 1T-MoS_(2)petals on N-doped reduced graphene oxide for exceptional electromagnetic wave absorption

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International Journal of Minerals,Metallurgy and Materials 2025年第3期32卷 619-630页

作者： Jia Zhao Haoran Lai Ming Li College of Chemistry and Materials engineering Bohai UniversityJinzhou 121013China Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou 313001China College of Chemistry and Chemical engineering Jishou UniversityJishou 416000China

The effective construction of electromagnetic(EM)wave absorption materials with thin matching thickness,broad bandwidth,and remarkable absorption is a great solution to EM pollution,which is a hot topic in current environmental *** this study,N-doped reduced graphene oxide(N-rGO)was first prepared using a facile hydrothermal ***,high-purity 1T-MoS_(2)petals were homogeneously anchored to the wrinkled surface of N-rGO to fabricate 1T-MoS_(2)@N-rGO *** numerous electric di-poles and profuse heterointerfaces in 1T-MoS_(2)@N-rGO would induced the multiple reflection and scattering of EM waves in a distinct-ive multidimensional structure formed by two-dimensional N-rGO and 1T-MoS_(2)microspheres with plentiful thin nanosheets,remarkable conduction loss derived from the migration of massive electrons in a well-constructed conductive network formed by 1T-MoS_(2)@N-rGO,and abundant polarization loss(including dipolar polarization loss and interfacial polarization loss).All of these gave the 1T-MoS_(2)@N-rGO nanocomposites superior EM wave absorption *** effective absorption bandwidth of 1T-MoS_(2)@N-rGO reached 6.48 GHz with a relatively thin matching thickness of 1.84 mm,and a minimum reflection loss of-52.24 dB was achieved at 3.84 ***,the radar scattering cross-section reduction value of 1T-MoS_(2)@N-rGO was up to 35.42 dB·m^(2) at 0°,which further verified the huge potential of our fabricated 1T-MoS_(2)@N-rGO nanocomposites in practical applications.

关键词： 1T-MoS_(2)@N-rGO nanocomposites conduction loss polarization loss ultrathin matching thickness electromagnetic wave absorption

Recent development in electrode design for wide-temperature supercapacitors

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Science China Chemistry 2025年第1期68卷 96-117页

作者： Jianhong Liu Qiang Zhou Yuxiao Lin Xinsheng Zhao Guangmin Zhou Xiaoxiao Li School of Physics and electronic engineering Jiangsu Normal UniversityXuzhou 221116China Tsinghua-Berkeley Shenzhen Institute&Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

An ever-increasing market demand has stimulated the soaring enthusiasm of researchers to develop wide-temperature supercapacitors(SCs).The active electrode is one of the most important parts of SC,which is directly related to the energy density,power transmission and long-term cyclability of the device in the wide-temperature *** with the SC electrodes aimed for room-temperature application,the SC electrodes for operating at wide-temperature scene often face greater *** this review,the main challenges of SC electrodes under various temperature conditions,including low,high and cross-fade temperatures,are *** relevant performance decay and failure mechanisms of wide-temperature SC electrodes are *** addition,this review deals with the recent studies and developments in robust wide-temperature SC electrodes with respect to the rational design of electrode structures and the exploitation of advanced active ***,the future directions for exploring reliable wide-temperature SCs are also proposed.

关键词： supercapacitor wide-temperature electrode design active materials

Distributed optimal consensus control for multiagent systems based on event-triggered and prioritized experience replay strategies

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Science China(Information Sciences) 2025年第1期68卷 306-321页

作者： Cuijuan ZHANG Lianghao JI Shasha YANG Xing GUO Huaqing LI Chongqing Key Laboratory of Image Cognition Chongqing University of Posts and Telecommunications Key Laboratory of Intelligent Perception and Computing of Anhui Province Anqing Normal University College of electronic and Information engineering Southwest University

This study uses event-triggered(ET) and reinforcement learning methods to investigate the optimal consensus control problem for cooperative-competitive multiagent systems. It proposes a novel distributed ET control strategy, which relies on a prioritized experience replay(PER) policy. This strategy not only conserves communication resources but also ensures acceptable system performance. To implement the proposed method, actor-critic(AC) dual-structured neural networks(NNs) are used to approximate the value function and control policy. In the AC NNs, the weight estimates for the NNs are updated at the moment of event triggering, resulting in a nonperiodic weight adjustment pattern. This approach decreases the computational cost in comparison with the traditional ET mechanism. The PER-based ET mechanism makes full use of valid historical data and effectively establishes a balance between system performance and communication resource ***, it does not require the following two conditions in most existing studies:(1) requirement of the system dynamics model to be known, and(2) persistent excitation. In addition, Zeno behavior is excluded from this study. Finally, a simulation is conducted to confirm the validity of the suggested approach.

关键词： multiagent systems event-triggered mechanism prioritized experience replay dual-structured neural networks optimal consensus control