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Chinese Geographical Science 2022年第1期32卷 16-30页

作者： zhang yiqun zhang Jingxiang School of Architecture and Urban Planning Nanjing UniversityNanjing 210093China

As the leading urban agglomeration in China,the Yangtze River Delta(YRD)is experiencing a factor-driven to innovationdriven ***,the dynamics of regional innovation growth are not yet fully *** paper combines the complex network methodology with spatial econometrics to disentangle the contributions of innovation endowments,innovation network flows,and innovation network positions to regional innovation growth,as well as their spatial spillover *** primary findings suggest that regional innovation growth results from the networked agglomeration economies,which is shaped by the interactions between agglomeration factors and network ***,agglomeration factors play a fundamental role in regional innovation *** contrast,network factors,such as the network flows and network positions,may contribute to new path creation by promoting access to external innovation ***,the institutional factors show multiplexity in fostering regional innovation *** findings indicate that the YRD region should shift the innovation growth pattern from competitive involution to mutually beneficial cooperation to reduce regional *** this regard,the institutional capacity of organizing network flows and fostering reciprocal inter-city partnerships has become increasingly critical for promoting sustainable innovation and regional development.

关键词： network positions innovation network regional growth Yangtze River Delta(YRD) China

Erroneous pixel prediction for semantic image segmentation

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Computational Visual Media 2022年第1期8卷 165-175页

作者： Lixue Gong yiqun zhang Yunke zhang Yin Yang Weiwei Xu State Key Lab of CAD&CG Zhejiang UniversityHangzhou 310058China School of Computing Clemson University South Carolina29634USA

We consider semantic image *** method is inspired by Bayesian deep learning which improves image segmentation accuracy by modeling the uncertainty of the network *** contrast to uncertainty,our method directly learns to predict the erroneous pixels of a segmentation network,which is modeled as a binary classification *** can speed up training comparing to the Monte Carlo integration often used in Bayesian deep *** also allows us to train a branch to correct the labels of erroneous *** method consists of three stages:(i)predict pixel-wise error probability of the initial result,(ii)redetermine new labels for pixels with high error probability,and(iii)fuse the initial result and the redetermined result with respect to the error *** formulate the error-pixel prediction problem as a classification task and employ an error-prediction branch in the network to predict pixel-wise error *** also introduce a detail branch to focus the training process on the erroneous *** have experimentally validated our method on the Cityscapes and ADE20K *** model can be easily added to various advanced segmentation networks to improve their *** DeepLabv3+as an example,our network can achieve 82.88%of mloU on Cityscapes testing dataset and 45.73%on ADE20K validation dataset,improving corresponding DeepLabv3+results by 0.74%and 0.13%respectively.

关键词： erroneous pixel prediction image segmentation deep learning

Optimal Design of Aperture Illuminations for Microwave Power Transmission with Annular Collection Areas

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Engineering 2023年第11期30卷 63-74页

作者： Xun Li Baoyan Duan yiqun zhang Yongxin Guo Shaanxi Key Laboratory of Space Solar Power Station System Xidian UniversityXi’an 710071China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117576Singapore

This work presents an optimal design method of antenna aperture illumination for microwave power transmission with an annular collection *** objective is to maximize the ratio of the power radiated on the annular collection area to the total transmitted *** formulating the aperture amplitude distribution through a summation of a special set of series,the optimal design problem can be reduced to finding the maximum ratio of two real quadratic *** on the theory of matrices,the solution to the formulated optimization problem is to determine the largest characteristic value and its associated characteristic *** meet security requirements,the peak radiation levels outside the receiving area are considered to be extra constraints.A hybrid grey wolf optimizer and Nelder–Mead simplex method is developed to deal with this constrained optimization *** order to demonstrate the effectiveness of the proposed method,numerical experiments on continuous apertures are conducted;then,discrete arrays of isotropic elements are employed to validate the correctness of the optimized ***,patch arrays are adopted to further verify the validity of the proposed method.

关键词： Microwave power transmission Beam collection efficiency Ring-shaped beam Annular collection area Grey wolf optimizer Nelder-Mead simplex method

Influence and experiment of cable-net manufacturing errors on surface accuracy of mesh reflector antennas

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Chinese Journal of Aeronautics 2023年第2期36卷 363-376页

作者： Zihan SUN Baoyan DUAN yiqun zhang Dongwu YANG School of Electromechanical Engineering Xidian UniversityXi'an 710071China

Cable-net structures are of substantial importance in the construction of large mesh reflector *** to the inevitable errors in their manufacturing process,the reflector surface accuracy *** study makes a comprehensive investigation of random manufacturing errors during constructing the mesh reflector antennas,and analyze its influence on reflector surface ***,the sensitivity of reflector surface accuracy with respect to the random errors of the unstressed cable length is mathematically ***,a non-button connecting method is proposed and analyzed to reduce manufacturing ***,two physical experiment models based on 2.62-meter mesh reflector antenna are ***,numerical examples and experimental tests are given to demonstrate the effectiveness of the proposed *** with the traditional method,the proposed method can effectively reduce the influence of the manufacturing errors on the reflector surface ***,the reduction in the sizes of the nodes also reduces the risk of entanglement of the mesh reflector antenna during the deployment process,and thereby improves the deployment reliability.

关键词： Error analysis Experimental tests Manufacturing methods Reflector antenna Surface accuracy

Distributed power conditioning unit of large-scale space solar power station

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Chinese Journal of Aeronautics 2024年第8期37卷 421-434页

作者： Xintong LI Jianwei MI yiqun zhang Guanheng FAN Jie DU School of Mechano-electronic Engineering Xidian UniversityXi’an 710071China Shaanxi Key Laboratory of Space Solar Power Station System Xidian UniversityXi’an 710071China Academy of Advanced Interdisciplinary Research Xidian UniversityXi’an 710071China

In this paper,a multi-bus distributed Power Conditioning Unit(PCU)is proposed for the Space Solar Power Station with large scale photovoltaic(PV)array and power levels reaching MW *** this unit,there are multiple independent PV *** each PV array,there are multiple independent PV *** this paper,a V-P droop control method with adaptive droop coefficient is proposed,which modifies the droop intercept based on the bus voltage deviation and the power per unit value of the PV *** method ensures the accuracy of bus voltage and achieves proportional distribution of power between PV arrays based on the proposed topology structure in this *** the load changes or the output power of the PV array fluctuates,this method can ensure that power is distributed *** principle and control method of the proposed droop control method is analyzed in this *** effectiveness of the method is verified through MATLAB/Simulink simulation and *** and experimental results show that the proposed method can achieve power distributed proportionally when load changes and PV output power fluctuates,reduce bus voltage error caused by line impedance and differences in rated power of different PV arrays,and improve the performance of PV power generation system applied to space.

关键词： Space Solar Power Station Photovoltaics Droop control DC confluence Power conditioning unit

Effect of operational condition of rotational subsystem on attitude control for space solar power station

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Chinese Journal of Aeronautics 2021年第5期34卷 289-297页

作者： Xiangfei JI Baoyan DUAN yiqun zhang Guanheng FAN Meng LI Yang YANG Shaanxi Key Laboratory of Space Solar Power Station System Xidian UniversityXi'an 710071China Key Laboratory of Electronic Equipment Structure Design Ministry of Education Xidian UniversityXi'an 710071China Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China School of Chemical Engineering Northwest UniversityXi'an 710071China

Space Solar Power Station(SSPS)is a giant spacecraft to collect space solar energy and transmit electric energy to the ground by using the wireless transmission *** a concentrated space solar power station,SSPS via the Orb-shape Membrane Energy Gathering Array(OMEGA)system is comprised of the concentrator subsystem,the photovoltaic array subsystem and the transmitting antenna *** this manuscript,the comprehensive study on the coordinate kinematic among subsystems is carried ***,kinematic analysis and dynamic analysis are ***,under the condition of ideal attitude,the influence of the moving condition of the Photovoltaic(PV)array on the overall system is ***,the control ability for the deviation attitude caused by the acceleration process of the photovoltaic array is *** simulation results demonstrate the serious influence of the angular acceleration of the photovoltaic array on the system’s attitude and the validity of the designed attitude control system.

关键词： Space solar power station SSPS-OMEGA Kinematic analysis Dynamic analysis Attitude control system

Evidence of constraint in the 3D genome for trans-splicing in human cells

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Science China(Life Sciences) 2020年第9期63卷 1380-1393页

作者： Cong Liu yiqun zhang Xiaoli Li Yan Jia Feifei Li Jing Li Zhihua zhang CAS Key Laboratory of Genome Sciences and Information Beijing Institute of Genomicsand China National Center for BioinformationChinese Academy of SciencesBeijing 100101China School of Life Science University of Chinese Academy of SciencesBeijing 100049China

Fusion transcripts are commonly found in eukaryotes, and many aberrant fusions are associated with severe diseases, including cancer. One class of fusion transcripts is generated by joining separate transcripts through trans-splicing. However, the mechanism of trans-splicing in mammals remains largely elusive. Here we showed evidence to support an intuitive hypothesis that attributes trans-splicing to the spatial proximity between premature transcripts. A novel trans-splicing detection tool(TSD) was developed to reliably identify intra-chromosomal trans-splicing events(i TSEs) from RNA-seq data. TSD can maintain a remarkable balance between sensitivity and accuracy, thus distinguishing it from most state-of-the-art tools. The accuracy of TSD was experimentally demonstrated by excluding potential false discovery from mosaic genome or template switching during PCR. We showed that i TSEs identified by TSD were frequently found between genomic regulatory elements, which are known to be more prone to interact with each other. Moreover, i TSE sites may be more physically adjacent to each other than random control in the tested human lymphoblastoid cell line according to Hi-C data. Our results suggest that trans-splicing and 3 D genome architecture may be coupled in mammals and that our pipeline, TSD, may facilitate investigations of trans-splicing on a systematic and accurate level previously thought impossible.

关键词： trans-splicing chromatin interaction 3D genome spatial clustering

Enhanced damping capacity of ferromagnetic Fe-Ga alloys by introducing structural defects

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Journal of Materials Science & Technology 2021年第25期84卷 173-181页

作者： Ruihua Qiao Junming Gou Tianzi Yang yiqun zhang Feng Liu Shanshan Hu Tianyu Ma Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of Materialsand MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterXi’an Jiaotong UniversityXi’an710049China State Key Laboratory of Solidification Processing and Analytical&Testing Center Northwestern Polytechnical UniversityXi'an710072China School of Materials Science and Engineering Zhejiang UniversityHangzhou310027China

The irreversible motion of magnetic domain walls in ferromagnets can dissipate a large portion of the elastic energy,and the associated damping capacity is proportional to the magnetostriction *** contrast,here we found that the damping capacity of the large magnetostriction Fe-Ga alloys can be enhanced by 2-3 times through introducing structural defects including interfacial dislocations and stacking faults,despite that these defects deteriorate the *** structural defects were introduced by aging the BCC(body-centered-cubic)solution-treated precursor,for which the formation of mechanically harder FCT(face-centered-tetragonal)and/or FCC(face-centered-cubic)phases can result in high-density partial dislocations at the semi-coherent phase interfaces and quasi-periodically stacked nano-layer substructure inside the FCC *** structural defects act as extra damping sources besides the magnetic domain walls because the structural accommodation of the semi-coherent phase interfaces between BCC and FCT/FCC nanoprecipitates with different elastic moduli and the nano-layer substructure towards long-range ordered periodical stacking can dissipate a large portion of mechanical *** findings suggest that introducing structural defects provides fresh freedom to design high damping ferromagnetic materials.

关键词： Ferromagnets Damping capacity Defects Magnetostriction Fe-Ga alloy

Parallel generation of low-correlation wideband complex chaotic signals using CW laser and external-cavity laser with self-phase-modulated injection

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Opto-Electronic Advances 2022年第5期5卷 49-56页

作者： Anke Zhao Ning Jiang Jiafa Peng Shiqin Liu yiqun zhang Kun Qiu School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China.

A novel scheme for generating optical chaos is proposed and experimentally demonstrated,which supports to simultaneously produce two low-correlation chaotic signals with wideband spectrum and suppressed time-delay-signature(TDS).In the proposed scheme,we use the output of an external-cavity semiconductor laser(ECSL)as the driving signal of a phase modulator to modulate the output of a CW *** the phase-modulated continuous-wave(CW)light is split into two parts,one is injected back into the ECSL that outputs one chaotic signal,while the other part is passed through a dispersion module for generating another chaotic signal *** experimental results prove that the proposed scheme has three ***,it can improve the bandwidth of ECSL-based chaos by several times,and simultaneously generate another wideband flat-spectrum chaotic ***,the undesired TDS characteristics of the simultaneously-generated chaotic signals can be efficiently suppressed to an indistinguishable level within a wide parameter range,as such the complexities of the chaotic signals are considerably ***,the correlation coefficient between these two simultaneously-generated chaotic signals is smaller than *** proposed scheme provides an attractive solution for parallel multiple chaos generation,and shows great potential for multiple channel chaos communications and multiple random bit generations.

关键词： optical chaos optical feedback semiconductor laser electro-optic phase modulation

Impact of coal power generation on the characteristics and risk of heavy metal pollution in nearby soil

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Ecosystem Health and Sustainability 2020年第1期6卷 412-423,411页

作者： yiqun zhang Di Wu Chenxing Wang Xiao Fu Gang Wu State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Institute of Architecture Design and Research Chinese Academy of SciencesBeijingChina

Introduction:The development of coal power base(CPB)poses a severe challenge to the *** conducted a soil survey in Xilinhot CPB,to evaluate and analyze the pollution characteristics,potential ecological risk,and sources of six heavy metals(As,Pb,Cu,Zn,Mn,and Cd)in soil by using Geo-accumulation index,revised Nemerow integrated pollution index(RNIPI),and potential ecological risk index(RI).Outcomes/other:The results showed that the pollution of Cd and As were *** mean of Cd and As were 1.11 mg·kg^(-1) and 25.13 mg·kg^(-1),which were 42.55 times and 4.41 times higher than its local background *** Geo-accumulation indices showed the contamination degree of Cd was strong and As was moderate,and the status of Cu,Pb,Zn,and Mn were *** was strongly contaminated based on its RNIPI and RI ***:The accumulations of As,Pb,and Cd were mainly associated with anthropogenic sources,including coal mining and combustion,and industrial exhaust ***,Mn,and Zn were primarily originated from the parent material(natural sources).Conclusion:This study provides scientific basis and effective countermeasures for the prevention and control of soil pollution in surrounding areas of CPB.

关键词： Soil pollution heavy metal contamination potential ecological risk sustainability coal power base Xilinhot