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Navigation Finsler metrics on a gradient Ricci soliton

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 266-275页

作者： LI Ying mo Xiao-huan WANG Xiao-yang Department of Applied Mathematics Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Pure and Applied Mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China school of Mathematics and statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a class of Finsler metrics defined by a vector field on a gradient Ricci *** obtain a necessary and sufficient condition for these Finsler metrics on a compact gradient Ricci soliton to be of isotropic s-curvature by establishing a new integral *** we determine the Ricci curvature of navigation Finsler metrics of isotropic s-curvature on a gradient Ricci soliton generalizing result only known in the case when such soliton is of Einstein *** its application,we obtain the Ricci curvature of all navigation Finsler metrics of isotropic s-curvature on Gaussian shrinking soliton.

关键词： gradient Ricci soliton navigation Finsler metric isotropic s-curvature Ricci curvature Gaussian shrinking soliton

Giant low-field reversible magnetocaloric effect at liquid helium temperature of niobium and iron co-substituted EuTiO_(3) compounds

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Journal of Rare Earths 2024年第4期42卷 710-715页

作者： Zhihong Hao Quanyi Liu Huicai Xie Yan Zhang Zhaojun mo school of Rare Earth and New Materials Engineering Ganzhou Innovation Center of Rare Earth Permanent Magnet Material Advanced Manufacturing and Intelligent Equipment TechnologyGannan University of Science and TechnologyGanzhou341000China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou34119China school of Materials science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China

Giant magnetocaloric effect(MCE)materials in the liquid helium temperature region have attracted a lot of attention in the field of low-temperature magnetic refrigeration(MR).In this study,a series of niobium(Nb)and iron(Fe)co-substituted EuTiO_(3) perovskites with cubic structure(space group pm3m)was successfully fabricated,and their magnetic properties as well as cryogenic magnetocaloric effects were investigated in *** expected,the introduction of Nb and Fe can significantly modulate the magnetic phase transition and magnetocaloric effect of the EuTiO_(3) *** increasing Fe concentration,two local minima corresponding to the AFM-FM magnetic phase transition near 5.0 K and FM-PM transition near 10 K with no hysteresis in the thermomagnetic curves are observed,which is attributed to an enhancement of FM *** the same time,the gradually widened-ΔsM-T curves and the two peaks with a broad shoulder lead to considerable refrigeration capacity(RC).With the field change ofΔH=2 T,the calculated values of-Δs_(M)^(max) for the EuTi_(0.9375-x)Nb_(0.0625)Fe_(x)O_(3)(x=0.075,0.1,0.125,0.15)compounds are 24.2,17.6,14.5 and 14.0 J/(kg·K),*** corresponding RC values were calculated to be 144.6,138.3,151.2 and 159 J/kg,***,the values of-Δs_(M)^(max) for EuTi_(0.8625)Nb_(0.0625)Fe_(0.075)O_(3) are 8.6 and 15.1 J/(kg·K)under low field changes of 0.5 and 1 T,*** giant low-field reversible magnetocaloric effect makes them attractive candidates for magnetic refrigeration in the liquid helium temperature region.

关键词： Magnetocaloric effect Refrigeration capacity Magnetic entropy change Rareearths

Using neural network modeling to improve the detection accuracy of land subsidence due to groundwater withdrawal

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Journal of mountain science 2024年第7期21卷 2320-2333页

作者： ali M.RAJABI ali EDALAT Yasaman ABOLGHAsEMI Mahdi KHODAPARAsT Department of Engineering Geology University of TehranTehran ***Iran Department of Civil Engineering University of QomQom ***Iran

Despite the high efficiency of remote sensing methods for rapid and large-scale detection of subsidence phenomena,this technique has limitations such as atmospheric impact and temporal and spatial decorrelation that affect the accuracy of the *** paper proposes a method based on an artificial neural network to improve the results of monitoring land subsidence due to groundwater overexploitation by radar interferometry in the aliabad plain(Central Iran).In this regard,vertical ground deformations were monitored over 18 months using the sentinel-1A sAR *** model the land subsidence by a multilayer perceptron(MLP)artificial neural network,four parameters,including groundwater level,alluvial thickness,elastic modulus,and transmissivity have been *** model's generalizability was assessed using data derived for 144 *** to the results,the neural network estimates the land subsidence at each ground point with an accuracy of 6.8 mm.A comparison between the predicted and actual values indicated a significant *** MLP model can be used to improve the results of subsidence detection in the study area or other areas with similar characteristics.

关键词： DInsAR Land subsidence Groundwater withdrawal aliabad plain Artificial neural network

Performance of Text-Independent Automatic speaker Recognition on a Multicore system

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Tsinghua science and Technology 2024年第2期29卷 447-456页

作者： Rand Kouatly Talha ali Khan Faculty of Tech and software Engineering University of Europe for Applied SciencesPotsdam 14469Germany

This paper studies a high-speed text-independent Automatic speaker Recognition(AsR)algorithm based on a multicore system's Gaussian Mixture model(GMM).The high speech is achieved using parallel implementation of the feature's extraction and aggregation methods during training and testing *** memory parallel programming techniques using both OpenMP and PThreads libraries are developed to accelerate the code and improve the performance of the AsR *** experimental results show speed-up improvements of around 3.2 on a personal laptop with Intel i5-6300HQ(2.3 GHz,four cores without hyper-threading,and 8 GB of RAM).In addition,a remarkable 100%speaker recognition accuracy is achieved.

关键词： Automatic speaker Recognition(AsR) Gaussian Mixture model(GMM) shared memory parallel programming PThreads OpenMP

A high aspect ratio surface micromachined accelerometer based on a siC-CNT composite material

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Microsystems & Nanoengineering 2024年第2期10卷 219-230页

作者： Jiarui mo shreyas shankar Roberto Pezone Guoqi Zhang sten Vollebregt Laboratory of Electronic Components Technology and Materials(ECTM)Department of MicroelectronicsDelft University of TechnologyDelftThe Netherlands

silicon carbide(siC)is recognized as an excellent material for microelectromechanical systems(MEMs),especially those operating in challenging environments,such as high temperature,high radiation,and corrosive ***,siC bulk micromachining is still a challenge,which hinders the development of complex siC *** address this problem,we present the use of a carbon nanotube(CNT)array coated with amorphous siC(a-siC)as an alternative composite material to enable high aspect ratio(HAR)surface *** using a prepatterned catalyst layer,a HAR CNT array can be grown as a structural template and then densified by uniformly filling the CNT bundle with LPCVD *** electrical properties of the resulting siC-CNT composite were characterized,and the results indicated that the electrical resistivity was dominated by the *** demonstrate the use of this composite in MEMs applications,a capacitive accelerometer was designed,fabricated,and *** fabrication results showed that the composite is fully compatible with the manufacturing of surface micromachining *** Young’s modulus of the composite was extracted from the measured spring constant,and the results show a great improvement in the mechanical properties of the CNTs after coating with *** accelerometer was electrically characterized,and its functionality was confirmed using a mechanical shaker.

关键词： composite surface electrical

The Immense Impact of Reverse Edges on Large Hierarchical Networks

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Engineering 2024年第5期36卷 240-249页

作者： Haosen Cao Bin-Bin Hu Xiaoyu mo Duxin Chen Jianxi Gao Ye Yuan Guanrong Chen Tamás Vicsek Xiaohong Guan Hai-Tao Zhang moE Engineering Research Center of Autonomous Intelligent Unmanned systems State Key Laboratory of Intelligent Manufacturing Equipment and TechnologySchool of Artificial Intelligence and AutomationHuazhong University of Science and TechnologyWuhan 430074China school of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 639798Singapore Jiangsu Key Laboratory of Networked Collective Intelligence School of MathematicsSoutheast UniversityNanjing 210096China Department of Computer science Rensselaer Polytechnic InstituteTroyNY 12180USA Department of Electronic Engineering City University of Hong KongHong Kong 999077China Department of Biological Physics Eötvös UniversityBudapest 1117Hungary moE Key Laboratory for Intelligent Networks and Network security School of Automation Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China

Hierarchical networks are frequently encountered in animal groups,gene networks,and artificial engineering systems such as multiple robots,unmanned vehicle systems,smart grids,wind farm networks,and so *** structure of a large directed hierarchical network is often strongly influenced by reverse edges from lower-to higher-level nodes,such as lagging birds’howl in a flock or the opinions of lowerlevel individuals feeding back to higher-level ones in a social *** study reveals that,for most large-scale real hierarchical networks,the majority of the reverse edges do not affect the synchronization process of the entire network;the synchronization process is influenced only by a small part of these reverse edges along specific *** surprisingly,a single effective reverse edge can slow down the synchronization of a huge hierarchical network by over 60%.The effect of such edges depends not on the network size but only on the average in-degree of the involved *** overwhelming majority of active reverse edges turn out to have some kind of“bunching”effect on the information flows of hierarchical networks,which slows down synchronization *** finding refines the current understanding of the role of reverse edges in many natural,social,and engineering hierarchical networks,which might be beneficial for precisely tuning the synchronization rhythms of these *** study also proposes an effective way to attack a hierarchical network by adding a malicious reverse edge to it and provides some guidance for protecting a network by screening out the specific small proportion of vulnerable nodes.

关键词： synchronizability Large hierarchical networks Reverse edges Information flows Complex networks

A Comprehensive Review on Charging Topologies and Power Electronic Converter solutions for Electric Vehicles

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Journal of modern Power systems and Clean Energy 2024年第3期12卷 675-694页

作者： Abdelfatah ali Hossam H.H.mousa mostafa F.shaaban Maher A.Azzouz Ahmed s.A.Awad the Department of Electrical Engineering American University of Sharjah26666 SharjahUnited Arab Emirates the Department of Electrical Engineering South Valley University83523 QenaEgypt the Department of Electrical and Computer Engineering University of WindsorWindsorON N9B 3P4 Canada Electrical Engineering Department Qatar UniversityDoha 2713Qatar Department of Electrical and Computer Engineering Sultan Qaboos UniversityMuscat123Oman

Electric vehicles(EVs)are becoming more popular worldwide due to environmental concerns,fuel security,and price *** performance of EVs relies on the energy stored in their batteries,which can be charged using either AC(slow)or DC(fast)***,EVs can also be used as mobile power storage devices using vehicle-to-grid(V2G)*** electronic converters(PECs)have a constructive role in EV applications,both in charging EVs and in ***,this paper comprehensively investigates the state of the art of EV charging topologies and PEC solutions for EV *** examines PECs from the point of view of their classifications,configurations,control approaches,and future research prospects and their impacts on power *** can be classified into various topologies:DC-DC converters,AC-DC converters,DC-AC converters,and AC-AC *** address the limitations of traditional DC-DC converters such as switching losses,size,and high-electromagnetic interference(EMI),resonant converters and multiport converters are being used in high-voltage EV ***,power-train converters have been modified for high-efficiency and reliability in EV *** paper offers an overview of charging topologies,PECs,challenges with solutions,and future trends in the field of the EV charging station applications.

关键词： Charging station charging topology electric vehicle power electronic converter vehicle-to-grid

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

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Defence Technology（防务技术） 2024年第1期31卷 387-399页

作者： Binghui Duan Hongchang mo Bojun Tan Xianming Lu Bozhou Wang Ning Liu Xi'an modern Chemistry Research Institute Xi'an710065People's Republic of China state Key Laboratory of Fluorine&Nitrogen Chemicals Xi'an710065People's Republic of China

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the *** types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)*** morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was *** grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)*** to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,***,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted *** findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

关键词： HMX crystals Polyalcohol bonding agent Energetic polymer Core-shell structure Interfacial reinforcement

Discourse analysis of knowledge-based live streaming:a case study of East Buy streamer Dong Yuhui

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Language and semiotic studies 2024年第2期10卷 222-244页

作者： Yehui song Junhua mo Korean Department Soochow UniversitySuzhou215006China English Department Soochow UniversitySuzhouChina

Live streaming e-commerce is not only an important part of China’s digital economy but also the preferred way of purchase for many Chinese,especially the *** 2022,a new model initiated by East Buy has emerged,quickly becoming known as knowledge-based live *** most famous streamer from this novel type of live streaming is Dong Yuhui,a former English teacher of the New Oriental *** a top Internet influencer with millions of followers,Dong Yuhui has become a conspicuous social sign of the rising China that is undergoing fast technological,economic,and cultural *** study thus takes Dong Yuhui as an example to examine the typical discourses of the knowledge-based live *** a triangulation of case study,discourse analysis,and sentiment analysis,it finds that Dong Yuhui mainly employs the strategies of disseminating encyclopedic knowledge,telling intriguing stories,and using poetic language in his live streaming *** unique discourse has the main function of fulfilling customers’intellectual,emotional,and psychological *** such,it is warmly received by customers,whose comments are centered on the talents of the streamer rather than the attributes of the commodity.

关键词： knowledge-based live streaming Dong Yuhui typical discourses major strategies main functions customer comments