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THE TR-UWB RECEIVER BASED ON SPATIAL DIVERSITY

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Journal of Electronics(China) 2009年第5期26卷 623-630页

作者： wang feng xu chengqi Zhang Yan College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 China

This paper presents a new Transmitted Reference (TR) Ultra-WideBand (UWB) receiver based on Spatial Diversity (SD), which employs Multi-Antenna Technology (MAT) to improve the performance of TR-UWB receiver. According to the amplitude of correlator output of every antenna branch, this paper analyzed the performances of the proposed TR-UWB receiver employing three different kinds of combination strategies, i.e., Maximum Ratio Combination (MRC), Equal Gain Combination (EGC), and Selective Combination (SC), which are different from conventional ones, and theoretically proved that the performance of EGC is better than MRC. Simulation results verify that when EGC is adopted and BER=10-3, increasing three antennas provides Signal to Noise Ratio (SNR) gain of about 3 dB in CM4 channel and SNR gain of about 2 dB in CM2 channel.

关键词： Ultra-WideBand (UWB) Transmitted Reference (TR) Spatial Diversity (SD) Multiple Antenna Technology (MAT) Bit Error Rate (BER)

FIXED-POINT BLIND ADAPTIVE MULTIUSER DETECTION ALGORITHM FOR IR UWB SYSTEMS IN MULTIPATH CHANNEL

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Journal of Electronics(China) 2010年第2期27卷 157-165页

作者： wang feng xu chengqi College of Telecommunications ＆ Information Engineering Nanjing University of Posts ＆ Telecommunications Nanjing 210003 China

Using the hypothesis that data transmitted by different users are statistically independent of each other,this paper proposes a fixed-point blind adaptive multiuser detection algorithm for Time-Hopping (TH) Impulse Radio (IR) Ultra Wide Band (UWB) systems in multipath channel,which is based on Independent Component Analysis (ICA) idea. The proposed algorithm employs maximizing negentropy criterion to separate the data packets of different users. Then the user characteristic se-quences are utilized to identify the data packet order of the desired user. This algorithm only needs the desired user’s characteristic sequence instead of channel information,power information and time-hoping code of any user. Due to using hypothesis of statistical independence among users,the proposed algorithm has the outstanding Bit Error Rate (BER) performance and the excellent ability of near-far resistance. Simulation results demonstrate that this algorithm has the performance close to that of Maximum-Likelihood (ML) algorithm and is a suboptimum blind adaptive multiuser detection algorithm of excellent near-far resistance and low complexity.

关键词： Ultra Wide Band (UWB) MultiUser Detection (MUD) Bind adaptive Fixed-point Multipath channel

A novel method for AFRPs burrs removal:Principle of mechanochemo-induced fiber fracture

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie xu Bo LI Pingfa feng Qiang wang feng feng Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling

Spatial diversion and coordination of flood water for an urban flood control project in Suzhou, China

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Water Science and Engineering 2024年第2期17卷 108-117页

作者： Yu xu You-peng xu Qiang wang Yue-feng wang Chao Gao Department of Geography and Spatial Information Techniques Ningbo UniversityNingbo 315211China State Key Laboratoryof Hydology Water Resources and Hydraulic Enginering Nanjing Hydraulic Research InstitueNanjing 210029China Laboratory of Sustainable Urban Drainage Ningbo UniversityNingbo 31521lChina Schol of Gegraphical and Oceanographic Sciences Nanjing UniversiyNanjing 210023China School of Geography and Tourism Chongqing Normal UniversityChongqing 401331China

Suzhou City,located in the Yangtze River Delta in China,is prone to flooding due to a complex combination of natural factors,including its monsoon climate,low elevation,and tidally influenced position,as well as intensive human *** Large Encirclement Flood Control Project(LEFCP)was launched to cope with serious floods in the urban *** project changed the spatiotemporal pattern of flood processes and caused spatial diversion of floods from the urban area to the outskirts of the ***,this study developed a distributed flood simulation model in order to understand this transition of flood *** results revealed that the LEFCP effectively protected the urban areas from floods,but the present scheduling schemes resulted in the spatial diversion of floods to the outskirts of the *** rainstorm frequencies of 10.0%to 0.5%,the water level differences between two representative water level stations(Miduqiao(MDQ)and fengqiao(FQ))located inside and outside the LEFCP area,ranged from 0.75 m to 0.24 m and from 1.80 m to 1.58 m,*** addition,the flood safety margin at MDQ and the duration with the water level exceeding the warning water level at FQ ranged from 0.95 m to 0.43 m and from 4 h to 22 h,*** scheduling schemes for the hydraulic facilities of the LEFCP in extreme precipitation cases were developed ac-cording to food simulations under seven scheduling *** helps to regulate the spatial flood diversion caused by the LEFCP during extreme precipitation.

关键词： Urban flooding Urban flood control project Rainstorm fregue ncy Flood simulation model Suzhou City

Simulation and analysis of soil homogenization drills based on discrete element method and response surface methodology

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Particuology 2024年第5期88卷 128-148页

作者： Zhipeng wang Tong Zhu Youzhao wang Song Yang feng Ma xu Li Institute of Process Equipment and Environmental Engineering School of Mechanical Engineering and AutomationNortheastern UniversityShenyang110819China Liaoning Coning Testing Co. Ltd.Shenyang110170 China

Currently,rotary drilling is one of the main pieces of equipment used for in-situ remediation of contaminated ***,this equipment has problems such as uneven mixing and low utilization efficiency,which affect the efficiency of in-situ soil *** improve the efficiency of in-situ soil remediation,this paper takes contaminated black soil as the research object,and the structural design of the new three-stage soil remediation auger is carried out based on *** mixing process of soil and heavy metal passivator under different motion and structural parameters was investigated by the discrete element method(DEM)and response surface *** experimental design was based on rotational speed,homogenizing mixing time,crushing section pitch,and homogenizing section pitch as factors,and soil fragmentation ratio,the coefficient of dispersion,and torque as optimization *** kinematic and structural parameters of the three-stage auger drill bit were then optimized using the one-factor method,the orthogonal test,and the response surface methodology,*** test method uses a one-way test to determine the central level value of the orthogonal test and a comprehensive balance method to determine the best combination of parameters for the orthogonal test,which is then used as the central value of the response surface test for parameter *** optimal combinations of kinematic and structural parameters of the three-stage auger drill bit are determined and validated using response surface *** optimum combination of parameters was found to be a speed of 129 rpm,a homogenizing mixing time of 24 s,a pitch of 165 mm in the crushing section,and a pitch of 132 mm in the homogenizing *** error between the optimal value of the predicted model using the response surface method and the actual simulated value under the optimal parameters is 4.2%,4.9%,and 5.3%,*** optimized factor parameters provide a refe

关键词： Black soil Mixing homogeneity Orthogonal method Response surface methodology Discrete element method Soil remediation

Melt flow,heat transfer and solidification in a flexible thin slab continuous casting mold with vertical-combined electromagnetic braking

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Journal of Iron and Steel Research International 2024年第2期31卷 401-415页

作者： Lin xu Ze-feng Han Christian Karcher En-gang wang Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang110819LiaoningChina Key Laboratory of Liaoning Province for Clean Combustion Power Generation and Heating Technology Shenyang Institute of EngineeringShenyang110136LiaoningChina Institute of Thermodynamics and Fluid Mechanics Technische Universität IlmenauIlmenau98684Germany

During continuous casting of steel slabs,the application of electromagnetic braking technology(EMBr)provides an effective tool to influence solidification by controlling the pattern of melt flow in the ***,the quality of the final product can be improved considerably.A new electromagnetic braking(EMBr)method,named vertical-combined electromagnetic braking(VC-EMBr),is proposed to be applied to a flexible thin slab casting(FTSC)*** evaluate the beneficial effects of the VC-EMBr,the melt flow,heat transfer,and solidification processes in the FTSC mold are studied by means of numerical *** detail,a Reynolds-averaged Navier–Stokes turbulence model together with an enthalpy-porosity approach was *** numerical findings are compared with respective simulations using the traditional *** results demonstrate that the application of the VC-EMBr contributes significantly to preventing relative slab *** contrast to the Ruler-EMBr,the additional vertical magnetic poles of the VC-EMBr preferentially suppress the direct impact of jet flow on the narrow face of FSTC mold and considerably diminish the level fluctuation near the meniscus *** instance,by applying a magnetic flux density of 0.3 T,the maximum amplitude of meniscus deflection reduces by about 80%.Moreover,the braking effect of the VC-EMBr effectively improves the homogeneity of temperature distribution in the upper recirculation region and increases the solidified shell thickness along the casting *** this basis,the newly proposed VC-EMBr shows a beneficial effect in preventing relative slab defects for FTSC thin slab continuous casting.

关键词： Electromagnetic braking Mold Melt flow Heat transfer Solidification

A two-step multi-frequency receiver function inversion method for shallow crustal S-wave velocity structure and its application across the basin-mountain range belts in Northeast China

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Science China Earth Sciences 2024年第3期67卷 687-703页

作者： Ruihao YANG xu wang Ling CHEN Mingye feng Qifu CHEN State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

A shallow crustal velocity structure(above 10 km depth) is essential for understanding the crustal structures and deformation and assessing the exploration prospect of natural resources, and also provides priori information for imaging deeper crustal and mantle structure. Passive-source seismic methods are cost-effective and advantageous for regional-scale imaging of shallow crustal structures compared to active-source methods. Among these passive methods, techniques utilizing receiver function waveforms and/or body-wave amplitude ratios have recently gained prominence due to their relatively high spatial resolution. However, in basin regions, reverberations caused by near-surface unconsolidated sedimentary layers often introduce strong non-uniqueness and uncertainty, limiting the applicability of such methods. To address these challenges, we propose a two-step inversion method that uses multi-frequency P-RF waveforms and P-RF horizontal-to-vertical amplitude ratios. Synthetic tests indicate that our two-step inversion method can mitigate the non-uniqueness of the inversion and enhance the stability of the results. Applying this method to teleseismic data from a linear seismic array across the sedimentary basins in Northeast China, we obtain a high-resolution image of the shallow crustal S-wave velocity structure along the array. Our results reveal significant differences between the basins and mountains. The identification of low-velocity anomalies(<2.8 km s^(-1)) at depths less than 1.0 km beneath the Erlian Basin and less than 2.5 km beneath the Songliao Basin suggests the existence of sedimentary layers. Moreover, the high-velocity anomalies(~3.4–3.8 km s^(-1)) occurring at depths greater than 7 km in the Songliao Basin may reflect mafic intrusions emplaced during the Early Cretaceous. Velocity anomaly distribution in our imaging result is consistent with the location of the major faults, uplifts, and sedimentary depressions, as well as active-source seismic res

关键词： Receiver function Frequency dependence Two-step inversion Shallow crustal velocity structures Unconsolidated sedimentary basins

Hybrid Analytical and Data-Driven Model Based Instance-Transfer Method for Power System Online Transient Stability Assessment

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1664-1675页

作者： feng Li Qi wang Yi Tang Yan xu Jie Dang School of Electrical Engineering Southeast UniversityNanjing 210000China Center for Power Engineering(CPE) School of Electrical and Electronic EngineeringNanyang Technological UniversitySingapore 639798Singapore Central China Branch of State Grid Corporation of China Wuhan 430077China

Data-driven methods are widely recognized and generate conducive results for online transient stability ***,the tedious and time-consuming process of sample collection is often *** functioning of power systems involves repetitive sample collection due to the constant variations occurring in the operation mode,thereby highlighting the importance of collection *** a means to achieve high sample collection efficiency following the operation mode change,we propose a novel instance-transfer method based on compression and matching strategy,which facilitates the direct acquisition of useful previous samples,used for creating the new sample ***,we present a hybrid model to ensure rationality in the process of sample similarity comparison and selection,where features of analytical modeling with special significance are introduced into data-driven *** the same time,a data-driven method can also be integrated in the hybrid model to achieve rapid error correction of analytical models,enabling fast and accurate post-disturbance transient stability *** a paradigm,we consider a scheme for online critical clearing time estimation,where integrated extended equal area criterion and extreme learning machine are employed as analytical model part and data-driven error correction model part,*** results validate the credible efficacy of the proposed method.

关键词： Critical clearing time extreme learning machine instance-transfer method transient stability assessment

Forecasting supernova observations with the CSST:*** samples

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 164-177页

作者： chengqi Liu Youhua xu Xianmin Meng Xin Zhang Shi-Yu Li Yuming Fu Xiaofeng wang Shufei Liu Zun Luo Guanghuan wang Hu Zhan Department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Beijing Planetarium Beijing Academy of Science and TechnologyBeijing 100044China Leiden Observatory Leiden UniversityNL-2300 RA LeidenThe Netherlands Kapteyn Astronomical Institute University of GroningenNL-9700 AV GroningenThe Netherlands Physics Department Tsinghua UniversityBeijing 100084China School of Astronomy and Space Science University of ChineseAcademy of SciencesBeijing 100049China

The China Space Station Telescope(CSST,also known as xuntian)is a serviceable two-meter-aperture wide-field telescope operating in the same orbit as the China Space *** CSST plans to survey a sky area of 17,500 deg^(2)of the medium-to-high Galactic latitude to a depth of 25-26 AB mag in at least 6 photometric bands over 255-1,000 *** such a large sky area,slitless spectra will also be taken over the same wavelength range as the imaging *** though the CSST survey is not dedicated to time-domain studies,it would still detect a large number of transients,such as supernovae(SNe).In this paper,we simulate photometric SN observations based on a strawman survey plan using the Sncosmo *** its 10-year survey,the CSST is expected to observe about 5 million SNe of various *** quality cuts,we obtain a“gold”sample that comprises roughly 7,400 SNe Ia,2,200 SNe Ibc,and 6,500 SNeⅡcandidates with correctly classified percentages reaching 91%,63%,and 93%(formally defined as classification precision),*** same survey can also trigger alerts for the detection of about 15,500 SNe Ia(precision 61%)and 2,100 SNeⅡ(precision 49%)candidates at least two days before the light ***,the near-ultraviolet observations of the CSST will be able to catch hundreds of shock-cooling events serendipitously every *** results demonstrate that the CSST can make a potentially significant contribution to SN studies.

关键词： space-based ultraviolet optical and infrared telescopes supernovae data analysis