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Science China Earth Sciences 2017年第2期60卷 315-327页

作者： yue jian MENG ZhiYong Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Beij'ing 100871 China

This study explores for the first time the impact of assimilating radial velocity(Vr)observations from a single or multiple Taiwan's coastal radars on tropical cyclone(TC)forecasting after landfall in the Chinese mainland by using a Weather Research and Forecasting model(WRF)-based ensemble Kalman filter(EnKF)data assimilation *** Morakot(2009),which caused widespread damage in the southeastern coastal regions of the mainland after devastating Taiwan,was chosen as a case *** results showed that assimilating Taiwan's radar Vr data improved environmental field and steering flow and produced a more realistic TC position and structure in the final EnKF cycling ***,the subsequent TC track and rainfall forecasts in southeastern China were *** addition,better observations of the TC inner core by Taiwan's radar was a primary factor in improving TC rainfall forecast in the Chinese mainland.

关键词： Radial velocity EnKF TC track forecast Rainfall forecast Chinese mainland

The Maximum Lagrangian of 5-uniform Hypergraphs without Containing Two Edges Intersecting at a Vertex

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Acta Mathematica Sinica,English Series 2022年第5期38卷 877-889页

作者： Biao WU yue jian PENG MOE-LCSM School of Mathematics and StatisticsHu’nan Normal UniversityChangsha 410081P.R.China School of Mathematics Hu’nan UniversityChangsha 410082P.R.China

Obtaining Turán densities of hypergraph through determining Lagrangian densities have been studied *** showed that the Lagrangian density of an r-uniform hypergraph equals the Turán density of the extension of this ***,Lagrangian density and Turán density are the same for a large class of hypergraphs such as hypergraphs covering *** Pr,sbe the r-uniform hypergraph with two edges intersecting at s *** determined the Lagrangian densities of Pr,sfor r=3 and s=1 or 2,or r=4 and s=2 or *** and Keevash determined for r=3 and s=0,and Bene Watts,Norin and Yepremyan determined for r≥4 and s=*** cases r=5 and s=4 or r=6 and s=5 were determined by Norin and *** showed for r=5,6 or 7,and s=3,4 or 5 *** cases r=4 and s=1 or r=5 and s=2 were determined by jiang,Peng and Wu,and Hu,Peng and Wu *** r=5,the only remaining case is s=*** this paper,we determine for this case.

关键词： Hypergraph Lagrangian Turán number

Multicolored Bipartite Ramsey Numbers of Large Cycles

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 347-357页

作者： Shao-qiang LIU yue-jian PENG College of Mathematics and Statistics Hanshan Normal UniversityChaozhou 521041China School of Mathematics Hunan UniversityChangsha 410082China

For an integer r≥2 and bipartite graphs Hi,where 1≤i≤r,the bipartite Ramsey number br(H1,H2,…,Hr)is the minimum integer N such that any r-edge coloring of the complete bipartite graph KN;N contains a monochromatic subgraph isomorphic to Hi in color i for some 1≤i≤*** show that if r≥3;α1,α2>0,αj+2≥[(j+2)!-1]Σi=1^(j+1)α1 for j=1,2…r-2,then br(C2[α1n],C2[α2n],…,C2[αrn]=(Σ=j=1^(r)a j+o(1))n.

关键词： ramsey number bipartite ramsey number regularity lemma

Connection Between Continuous Optimization and Turán Densities of Non-uniform Hypergraphs

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Acta Mathematicae Applicatae Sinica 2021年第4期37卷 858-866页

作者： Xiao-bing GUO yue-jian PENG School of Mathematics Hunan UniversityChangsha410082China

A classical result of Motzkin and Straus established the connection between the Lagrangian of a graph and its maximum *** it,they gave a new proof of Turán’s *** aroused the interests in studying the connection between continuous optimization and extremal problems in *** 2009,*** Bulòand *** extended the result of Motzkin-Straus to r-uniform ***,Johnston and Lu initiated the study of the Turán density of a non-uniform *** optimization problems related to several types of non-uniform hypergraphs and its applications on Turán densities have also been *** this paper,we obtain a Motzkin-Straus type of results for all non-uniform *** it,we give an upper bound of the Turán density of a complete non-uniform hypergraph.

关键词： hypergrapli maximum clique polynomial optimization

Maximum Cliques of Hypergraphs and Polynomial Optimization

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 842-855页

作者： Yan-ming CHANG yue-jian PENG College of Mathematics Hunan University Changsha 410082 China Institute of Mathematics Hunan University Changsha 410082 China

A remarkable connection between the clique number and the Lagrangian of a graph was established by Motzkin and Straus. Later, Rota Bul′o and Pelillo extended the theorem of Motzkin-Straus to r-uniform hypergraphs by studying the relation of local（global） minimizers of a homogeneous polynomial function of degree r and the maximal（maximum） cliques of an r-uniform hypergraph. In this paper, we study polynomial optimization problems for non-uniform hypergraphs with four different types of edges and apply it to get an upper bound of Tur′an densities of complete non-uniform hypergraphs.

关键词： hypergraph maximum clique polynomial optimization

A 2-step GPS carrier tracking loop for urban vehicle applications

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Journal of Systems Engineering and Electronics 2017年第5期28卷 817-826页

作者： Hongyang Zhang Luping Xu yue jian Xiaochen Ma School of Aerospace Science and Technology Xidian University Xi'an Flight Automatic Control Research Institute Aviation Industry Corporation of China Xi'an Aeronautics Computing Technique Research Institute Aviation Industry Corporation of China

Global positioning system (GPS) for vehicle applications in the urban area is challenged by low signal intensity. The carrier loop based on fast Fourier transform (FFT) can obtain a high signal to noise ratio (SNR) gain by increasing the observation time. However, this leads to a major problem that the acceleration cannot be ignored. The performance of the FFT-based loop will decline with the acceleration increasing. This paper discusses the effect of the dynamic on FFT first. Then a high performance carrier tracking loop for weak GPS L5 signals is proposed. It combines discrete chirp-Fourier transform (DCFT) and the phase fitting method to estimate Doppler frequency and Doppler rate simultaneously. First, a sequence of integration results is used to perform DCFT to estimate coarse Doppler frequency and Doppler rate. Second, the phase of the sequence is calculated and used to perform linear fitting. By the phase fitting method, the fine Doppler frequency and Doppler rate can be estimated. The computation cost is small because the integration results are used and the phase fitting method needs only coarse estimates of Doppler frequency and Doppler rate. Compared with FFT and DCFT, the precision of the phase fitting method is not limited by the resolution. Thus the proposed loop can get high precision and low carrier to noise ratio (C/N-0) tracking threshold. Simulation results show this loop has a great improvement than conventional loops for urban weak-signal applications.

关键词： satellite navigation receiver signal processing frequency lock loop

Long term integration of radar signals with unknown Doppler shift for ubiquitous radar

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Journal of Systems Engineering and Electronics 2011年第2期22卷 219-227页

作者： Qinglong Bao Zengping Chen yue Zhang jian Yang ATR National Defense Science and Technology Key Lab National University of Defense Technology Changsha 410073 P. R. China

Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in ＂pop-up＂ targets in clutter to long-range targets impacts selection of waveform parameters. The coherent processing interval （CPI） must be long enough to achieve a certain signal-to-noise ratio （SNR） that ensures the efficiency of detection. The condition of detection in the case of low SNR is analyzed, and three different cases that would occur during integration are discussed and a method to determine the CPI is presented. The simulation results show that targets detection with SNR as low as -26 dB in the experimental system can possibly determine the CPI.

关键词： ubiquitous radar low signal-to-noise ratio (SNR),coherent processing interval (CPI) coherent integration non-coherent integration.

Efficiently Improving Ensemble Forecasts of Warm-Sector Heavy Rainfall over Coastal Southern China: Targeted Assimilation to Reduce the Critical Initial Field Errors

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Journal of Meteorological Research 2023年第4期37卷 486-507页

作者： Xinghua BAO Rudi XIA Yali LUO jian yue State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences(CAMS)China Meteorological Administration(CMA)Beijing 100081 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD) Nanjing University of Information Science&TechnologyNanjing 210044 CMA Earth System Modeling and Prediction Centre China Meteorological AdministrationBeijing 100081

Warm-sector heavy rainfall events over southern China are difficult to accurately forecast, due in part to inaccurate initial fields in numerical weather prediction models. In order to determine an efficient way of reducing the critical initial field errors, this study conducts and compares two sets of 60-member ensemble forecast experiments of a warm-sector heavy rainfall event over coastal southern China without data assimilation(NODA) and with radar radial velocity data assimilation(RadarDA). Yangjiang radar data, which can provide offshore high-resolution wind field information, were assimilated by using a Weather Research and Forecasting(WRF)-based ensemble Kalman filter(EnKF) system. The results show that the speed and direction errors of the southeasterly airflow in the marine boundary layer over the northern South China Sea may primarily be responsible for the forecast errors in rainfall and convection evolution. Targeted assimilation of radial velocity data from the Yangjiang radar can reduce the critical initial field errors of most members, resulting in improvements to the ensemble forecast. Specifically, RadarDA simulations indicate that radial-velocity data assimilation(VrDA) can directly reduce the initial field errors in wind speed and direction, and indirectly and slightly adjust the initial moisture fields in most members, thereby improving the evolution features of moisture transport during the subsequent forecast period. Therefore, these RadarDA members can better capture the initiation and development of convection and have higher forecast skill for the convection evolution and rainfall. The improvement in the deterministic forecasts of most members results in an improved overall ensemble forecast performance. However, VrDA sometimes results in inappropriate adjustment of the initial wind field,so the forecast skill of a few members decreases rather than increases after VrDA. This suggests that a degree of uncertainty remains about the effect of

关键词： ensemble forecast targeted assimilation warm-sector heavy rainfall

Preliminary studies on the large-scale geomorphic patterns of the complex longitudinal sand ridge zone in the Taklimakan Desert

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Chinese Science Bulletin 2008年第S2期53卷 177-189页

作者： yue jian LEI JiaQiang MU GuiJin Xinjiang Institute of Ecology and Geography Chinese Academy of SciencesUrumqi 830011China Graduate University of Chinese Academy of Sciences Beijing 100049China

Through analysis of satellite images from Google Earth, this article expounds the characteristics of large-scale geomorphic patterns of the complex longitudinal sand ridge zone in the Taklimakan Desert, and reduces the large-scale geomorphic patterns to six types: parallel pattern, "日"character-shaped and "乡" character-shaped pattern, comb-shaped pattern, fork-shaped pattern, toe-shaped pattern and miscellaneous pattern. And according to the large-scale geomorphic pattern type (or composition of pattern types) as well as some other factors, the article divides the complex longitudinal sand ridge zone into 55 subzones. Lastly, aiming at the genetic problems of the large-scale geomorphic patterns, the article suggests three connective types of the sand ridges in the complex longitudinal sand ridge zone, i.e., connecting or intersecting after natural elongation, connecting in a narrow place and connecting with the aid of intermediary.

关键词： Taklimakan Desert complex longitudinal sand ridges large-scale geomorphic pattern subzone Google Earth

Prospect of radiotherapy technology development in the era of immunotherapy

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Journal of the National Cancer Center 2022年第2期2卷 106-112页

作者： jian-yue Jin Radiation Oncology Seidman Cancer CenterUniversity HospitalsCase Western Reserve UniversityClevelandUnited States

Radiotherapy(RT)is one of the important modalities for cancer *** evidence suggests that the host immune system is involved in the tumor cell killing during RT,and future RT technology development should aim to minimize radiation dose to the immune system while maintaining a sufficient dose to the tumor.A brief history of RT technology development is first *** RT technologies,namely FLASH RT,proton therapy,and spatially fractionated RT(SFRT),are singled out for the era of *** the technical aspects,the mechanism of FLASH effect is discussed,which is likely the combined results of the recombination effect,oxygen depletion effect and immune sparing *** proton therapy should have the advantage of causing much less immune damage in comparison to X-ray based RT due to the Bragg ***,the relative biological effectiveness(RBE)uncertainty and range uncertainty may hinder the translation of this advantage into clinical *** approaches to overcome these two technical hurdles are *** SFRT approaches and their application are *** approaches are categorized as single-field 1D/2D SFRT,multi-field 3D SFRT and quasi-3D SFRT techniques.A 3D SFRT approach,which is achieved by placing the Bragg peak of a proton 2D SFRT field in discrete depths,may have special potential because all 3 technologies(FLASH RT,proton therapy and SFRT)may be used in this approach.

关键词： Radiotherapy technology Immune sparing technique Proton therapy FLASH radiotherapy Spatially fractionated radiotherapy