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Significantly improved near-field co.munication antennas based on novel Ho^(3+)and co.(2+)ions co.doped Ni-Zn ferrites

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Journal of Advanced Ceramics 2024年第3期13卷 293-309页

作者： Pao Yang Zhiqing Liu Hongbin Qi Xiuli Fu Zhijian Peng School of Science China University of GeosciencesBeijing 100083China School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China Kunshan GuoLi electronic technology co. Ltd.Kunshan 215300China

In near-field co.munication(NFC)antennas,soft magnetic ferrites are usually applied as a substrate to reduce eddy current loss and increase magnetic field *** this purpose,the applied ferrites are required to have high permeability and saturation magnetization together with low magnetic loss and dielectric ***,for most soft magnetic ferrites,it is difficult to meet all the *** novel Ni-Zn ferrite ceramics co.doped by Ho^(3+)and co.(2+)ions with chemical formula Ni_(0.5-x)Zn_(0.5)Ho_(0.02)co.(x)Fe_(1.98)O_(4)(x=0-0.2)were designed and prepared to balance these needs on the basis of molten salt synthesis with metal nitrates as raw materials and potassium hydroxide(KOH)as the precipitation agent and molten salt *** the substitution of Ho^(3+),the saturation magnetization and initial permeability decrease,but with further doping of co.(2+),the saturation magnetization gradually increases,while the initial permeability co.tinues to *** x=0.1,the sample will have the lowest dielectric co.stant,magnetic and dielectric loss,as well as the highest Curie temperature(305℃).Moreover,the acquired Ni-Zn ferrites have been applied simulatively in NFC antennas,revealing that the device manufactured with the optimal Ni_(0.4)Zn_(0.5)Ho_(0.02)co.(0.1)Fe_(1.98)O_(4)ferrite ceramics would have significantly improved performance at 13.56 MHz with low leakage and long transmit distance of magnetic ***,the Ni_(0.4)Zn_(0.5)Ho_(0.02)co.(0.1)Fe_(1.98)O_(4)ferrite ceramics would be a good candidate for NFC antenna substrates.

关键词： electromagnetic properties co.doping microstrip antennas Ni-Zn ferrite

Vibration co.trol of the Rail Grinding Vehicle with Abrasive Belt Based on Structural Optimization and Lightweight Design

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 311-337页

作者： Wengang Fan Shuai Zhang Zhiwei Wu Yi Liu Jiangnan Yu School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control TechnologyMinistry of EducationBeijing 100044China China Railway Materials Operation and Maintenance technology co. LtdBeijing 100036China

As a new grinding and maintenance technology,rail belt grinding shows significant advantages in many applications The dynamic characteristics of the rail belt grinding vehicle largely determines its grinding performance and service *** order to explore the vibration co.trol method of the rail grinding vehicle with abrasive belt,the vibration response changes in structural optimization and lightweight design are respectively analyzed through transient response and random vibration simulations in this ***,the transient response simulation analysis of the rail grinding vehicle with abrasive belt is carried out under operating co.ditions and non-operating ***,the vibration co.trol of the grinding vehicle is implemented by setting vibration isolation elements,optimizing the structure,and increasing ***,in order to further explore the dynamic characteristics of the rail grinding vehicle,the random vibration simulation analysis of the grinding vehicle is carried out under the co.dition of the horizontal irregularity of the American AAR6 ***,by replacing the Q235 steel frame material with 7075 aluminum alloy and LA43M magnesium alloy,both vibration co.trol and lightweight design can be achieved *** results of transient dynamic response analysis show that the acceleration of most positions in the two working co.ditions exceeds the standard value in GB/T 17426-1998 *** optimizing the structure of the grinding vehicle in three ways,the average vibration acceleration of the whole car is reduced by about 55.1%from 15.6 m/s^(2) to 7.0 m/s^(2).The results of random vibration analysis show that the grinding vehicle with Q235 steel frame does not meet the safety co.ditions of 3σ.By changing frame material,the maximum vibration stress of the vehicle can be reduced from 240.7 MPa to 160.0 MPa and the weight of the grinding vehicle is reduced by about 21.7%from 1500 kg to 1175 *** modal analysis results indic

关键词： Vibration co.trol Dynamic characteristics Structural optimization Lightweight design Modal analysis

Preparation and Rheological Characterization of Long Chain Branching Polyglyco.ide

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Chinese Journal of Polymer Science 2024年第8期42卷 1177-1184页

作者： Wei-Lin Liu Ming-Fu Lyu Heng-Yuan Zhang Jian-Ye Liu Shi-Jun Zhang beijing University of Chemical technology Beijing 100029China SINOPEC(beijing)Research Institute of Chemical Industry co. Ltd.Beijing 100013China

The long chain branching(LCB)polyglyco.ide(PGA)was successfully prepared by the successive reactions of the terminal hydroxyl groups of PGA with triglycidyl isocyanurate(TGIC)and pyromellitic dianhydride(PMDA).The influence of LCB produced by functional group reaction on rheological and crystallization behavior was studied and discussed through linear rheology,uniaxial elongation and DSC(differential scanning calorimetry).The much higher visco.ity and the more notable strain hardening behavior of modified PGA indicates the LCB with high degree of entanglements are *** melt strength of PGA is finally improved greatly and can make su re that the supercritical co.(2)foaming can be carried out successfully.

关键词： Polyglyco.ide(PGA) Long chain branching(LCB) Rheology

co.tinuous-Time Channel Prediction Based on Tensor Neural Ordinary Differential Equation

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China co.munications 2024年第1期21卷 163-174页

作者： Mingyao Cui Hao Jiang Yuhao Chen Yang Du Linglong Dai The Department of electronic Engineering Tsinghua UniversityBeijing 100084China Huawei technology co. Ltd.Chengdu Research InstituteChengdu 611730China

Channel prediction is critical to address the channel aging issue in mobile *** channel prediction techniques are mainly designed for discrete channel prediction,which can only predict the future channel in a fixed time slot per frame,while the other intra-frame channels are usually reco.ered by ***,these approaches suffer from a serious interpolation loss,especially for mobile millimeter-wave *** solve this challenging problem,we propose a tensor neural ordinary differential equation(TN-ODE)based co.tinuous-time channel prediction scheme to realize the direct prediction of intra-frame ***,inspired by the recently developed co.tinuous mapping model named neural ODE in the field of machine learning,we first utilize the neural ODE model to predict future co.tinuous-time *** improve the channel prediction accuracy and reduce co.putational co.plexity,we then propose the TN-ODE scheme to learn the structural characteristics of the high-dimensional channel by low-dimensional learnable *** results show that the proposed scheme is able to achieve higher intra-frame channel prediction accuracy than existing schemes.

关键词： channel prediction massive multipleinput-multiple-output millimeter-wave co.munications ordinary differential equation

Data and Model Driven Task Offloading Strategy in the Dynamic Mobile Edge co.puting System

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Journal of Systems Science & co.plexity 2024年第1期37卷 351-368页

作者： DONG Hairong WU Wei SONG Haifeng LIU Zhen ZHANG Zixuan School of electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China School of electronic and Information Engineering BeiHang UniversityBeijing 100191China CRSC Research&Design Institute Group co. Ltd.Beijing 100070China

Mobile Edge co.puting(MEC)provides co.munication and co.putational capabilities for the industrial Internet,meeting the demands of latency-sensitive ***,traditional model-driven task offloading strategies face challenges in adapting to situations with unknown network co.munication status and co.putational *** limitation beco.es notably significant in co.plex industrial networks of high-speed *** by these co.siderations,a data and model-driven task offloading problem is proposed in this paper.A redundant co.munication network is designed to adapt to anomalous channel states when tasks are offloaded to edge *** link switching mechanism is executed by the train acco.ding to the attributes of the co.pleted *** task offloading optimization problem is formulated by introducing data-driven prediction of co.munication states into the traditional ***,the optimal strategy is achieved by employing the informer-based prediction algorithm and the quantum particle swarm optimization method,which effectively tackle real-time optimization problems due to their low time *** simulations illustrate that the data and model-driven task offloading strategy can predict the co.munication state in advance,thus reducing the co.t of the system and improving its robustness.

关键词： Data driven model informer mobile edge co.puting quantum particle swarm optimization task offloading.

A Trust Evaluation Mechanism Based on Autoenco.er Clustering Algorithm for Edge Device Access of IoT

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co.puters, Materials & co.tinua 2024年第2期78卷 1881-1895页

作者： Xiao Feng Zheng Yuan Cyber Security Academy Beijing University of Posts and TelecommunicationsBeijing100876China Department of Cyberspace Security Beijing Electronic Science and Technology InstituteBeijing100070China State Grid Info-Teleco. Great Power Science and technology co. Ltd.Beijing102211China

First,we propose a cross-domain authentication architecture based on trust evaluation mechanism,including registration,certificate issuance,and cross-domain authentication processes.A direct trust evaluation mechanism based on the time decay factor is proposed,taking into acco.nt the influence of historical interaction *** weight the time attenuation factor to each historical interaction reco.d for updating and got the new historical reco.d *** refer to the beta distribution to enhance the flexibility and adaptability of the direct trust assessment model to better capture time trends in the historical *** we propose an autoenco.er-based trust clustering *** perform feature extraction based on *** leibler(KL)divergence is used to calculate the reco.struction *** co.structing a co.volutional autoenco.er,we introduce co.volutional neural networks to improve training efficiency and introduce sparse co.straints into the hidden layer of the *** sparse penalty term in the loss function measures the difference through the KL *** clustering is performed based on the density based spatial clustering of applications with noise(DBSCAN)clustering *** the clustering process,edge nodes have a variety of trustworthy attribute *** assign different attribute weights acco.ding to the relative importance of each attribute in the clustering process,and a larger weight means that the attribute occupies a greater weight in the calculation of ***,we introduced adaptive weights to calculate co.prehensive trust *** experiments prove that our trust evaluation mechanism has excellent reliability and accuracy.

关键词： Cross-domain authentication trust evaluation autoenco.er

Dinitrophenyl-oxadiazole co.pounds:Design strategy,synthesis,and properties of a series of new melt-cast explosives

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Defence technology（防务技术） 2024年第5期35卷 100-107页

作者： Bao-long Kuang Ting-wei Wang co.g Li Mou Sun Qamar-un-Nisa Tariq Chao Zhang Zhi-ming Xie Zu-jia Lu Jian-guo Zhang State Key Laboratory of Explosion Science and technology Beijing Institute of TechnologyBeijing100081China China Wuzhou Engineering Group co. LTD.Beijing 100053China

Melt-cast explosives are the most widely used energetic materials in military co.posite explosives,researchers have been unremittingly exploring high-energy and insensitive melt-cast *** this work,a series of dinitrophenyl-oxadiazole co.pounds were designed and *** co.pounds have an ideal low melting point(80-97℃),good detonation performance(detonation velocity D=6455-6971 m/s,detonation pressure P=18-19 GPa)and extreme insensitive nature(impact sensitivity≥60 J,friction sensitivity>360 N).All these co.pounds were well characterized by nuclear magnetic resonance,fourier transform infrared spectrosco.y,elemental *** 2,3 were unambiguously co.firmed by X-ray single crystal diffraction *** a result,their overall properties are superior to traditional melt-cast explosives trinitrotoluene(TNT)and dinitroanisole(DNAN)which may have excellent potential applications in insensitive melt-cast explosives.

关键词： Dinitrophenyl-oxadiazole Melt-cast explosive Low sensitivity

Solidification behaviour and hot cracking susceptibility of a novel Ni-based superalloy

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Journal of Iron and Steel Research International 2024年第4期31卷 956-966页

作者： Yue Chen Shao-min Lv Xing-fei Xie Xiao-can Wen Jng-long Qu Jin-hui Du High-Temperature Materials Institute China Iron and Steel Research Institute Group Co.Ltd.Beijing 100081China beijing GAONA Materials and technology co. Ltd.Beijing 100081China Sichuan CISRI-GAONA Forging co. Ltd.Deyang 610000SichuanChina

A novel Ni-based superalloy GH4151,with a γ′ volume fraction of about 55%and a service temperature capability up to 8oo oC,was *** to the different co.ling co.ditions of various regions during the solidification of ingots,significant co.ling rate variations may lead to the occurrence of hot *** scanning laser microsco.e was utilised to investigate the solidification process and phase precipitation behaviour of the GH4151 under wide range co.ling *** characteristics of L→γ transformation were analysed,and the growth rates of at each stage were *** segregation behaviour was predicted using the Scheil equation,and the predicted results match well with the experimental *** sensitivity co.fficient for hot cracking was modified,and cracking sensitivity co.fficient values for the alloy under different co.ling rates were co.puted,revealing that the alloy is most susceptible to hot cracking at 10℃/min co.ling ***,co.trolling the co.ling rate can reduce the possibility of hot cracking in ingot.

关键词： Ni-based superalloy Solidification behaviour In-situ observation Clyne and Davies's criterion:Hot cracking susceptibility

Occurrence and vertical distribution of aluminum and rare earths in weathered crust elution-deposited rare earth ore:Effect of soil solution pH and clay minerals

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Journal of Rare Earths 2024年第7期42卷 1394-1402,I0007页

作者： Jiaxin Pan Longsheng Zhao Zheng Li Xiaowei Huang Zongyu Feng Jun Chen National Engineering Research Center for Rare Earth China GRINM Group Co.Ltd.Beijing100088China School of Metallurgical and Eco.ogical Engineering University of Science and Technology Beijing(USTB)Beijing100083China GRIREM Hi–Tech co. Ltd.Langfang065201China GRIREM Advanced Materials co. Ltd.Beijing100088China GRIMAT Engineering Institute co. Ltd.Beijing101407China

Weathered crust elution-deposited rare earth ore is crucial source of medium and heavy rare earths,with in-situ leaching being the most co.mon mining *** high co.tents of impurity of aluminum in the leach solution are a significant challenge for the subsequent enrichment process of rare earths.A co.prehensive understanding of the occurrences and vertical distribution of aluminum and rare earths within typical vertical profiles can provide valuable insights into entire design of the in-situ *** paper improves a five-step sequential extraction method to analyze the occurrence and vertical distribution of rare earths and aluminum in vertical profiles from Chongzuo and *** results demonstrate that soil solution pH is the main factor affecting the vertical distribution of ionexchangeable rare *** samples have distinct areas of enrichment for ion-exchangeable rare earths or ***-exchangeable rare earths are primary co.centrated in the middle and lower parts of the ore layer(4-13 m in Chongzuo,14-22 m in Longyan),while the ion-exchangeable aluminum is mainly enriched in the upper part of the ore layer(1-5 m in Chongzuo,and 2-14 m in Longyan).The vertical distribution of inorganic hydroxy aluminum is likely influenced by the micromorphology and particle size of the clay *** inorganic hydroxy aluminum co.centration in Chongzuo samples decreases co.tinuously from 415.65 to 120.95 mg/kg with increasing sampling depth,whereas the co.centration in Longyan samples(110.55-171.27 mg/kg)is almost independence with sampling *** results provide direct guidance for the entire design of the injection well depth and the leaching parameters,thereby inhibiting the leaching of impurity of aluminum and lower the co.sumption of leaching agent.

关键词： Weathered crust elution-deposited rare earth ore Sequential extraction Occurrence Aluminum Rare earth elements