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Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： tian Jing ZHANG wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

Simulation of Cement Hydration and Porous Structures by the Hydration-Pixel Probability Model

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Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1044-1055页

作者： tian Cong wei Xiaosheng School of Civil Engineering Architecture&The EnvironmentHubei University of TechnologyWuhan 430072China School of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430072China

This research proposes a new pixel-based model called the hydration-pixel probability model which aims to simplify cement hydration as a probability *** hydration capacity of cement,the solution within pores,and the difiusion of solid particles are represented by three probability functions derived from experimental data obtained through electrical resistivity and hydration heat *** principle of the model is relatively simple,and the parameters have clear physical *** this research,the porous structures of difierent cement pastes with w/c ratios of 0.3,0.4,and 0.5 are *** results indicate that the porosity of the cement paste decreases during the first few hours,followed by a rapid decline,and eventually reaches a steady *** porosity of the paste decreases as w/c ratio decreases,and the rate of decrease is more rapid in the early *** to the porosity curves,the average degree of hydration and depth of hydration can be *** simulation results show that the hydration degree of paste composed of irregular particles is higher than that of the paste composed of round *** trend in the development of the average hydration depth is similar to that of the average hydration *** analyzing the average growth rate of the hydration depth,it is observed that there are two peaks in the curves,which correspond to the three characteristic points in the electrical resistivity test.

关键词： cement hydration model porosity hydration degree simulation

Highly luminescent zero-dimensional lead-free manganese halides forβ-ray scintillation

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Nano Research 2022年第9期15卷 8486-8492页

作者： Linyuan Lian wei qi Huaiyi Ding Hao tian qi Ye Yong-Biao Zhao Long Zhao Jianbo Gao Daoli Zhang Jianbing Zhang School of Optical and Electronic Information Huazhong University of Science and Technology1037 Luoyu RoadWuhan 430074China Hubei Key Laboratory of Bioinorganic Chemistry&Materia Medica School of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China Key Laboratory of Yunnan Provincial Higher Education Institutions for Optoelectronics Device Engineering School of Physics and AstronomyYunnan UniversityKunming 650504China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China Department of Physics and Astronomy Ultrafast Photophysics of Quantum Devices LaboratoryClemson UniversityClemsonSC 29634USA Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Shenzhen Huazhong University of Science and Technology Research Institute Shenzhen 518057China

Because of their moderate penetration power,β-rays(high-energy electrons)are a useful signal for evaluating the surface contamination of nuclear ***,the development ofβ-ray scintillators,which convert the absorbed high-energy electrons into visible photons,is hindered by the limitations of materials ***,we report two highly luminescent zerodimensional(0D)organic-inorganic lead-free metal halide hybrids,(C_(13)H_(30)N)_(2)MnBr_(4)and(C_(19)H_(34)N)_(2)MnBr_(4),as scintillators exhibiting efficientβ-ray *** hybrid scintillators combine the superior properties of organic and inorganic *** example,organic components that contain light elements C,H,and N enhance the capturing efficiency ofβparticles;isolated inorganic[MnBr_(4)]2−tetrahedrons serve as highly localized emitting centers to emit intense radioluminescence(RL)underβ-ray *** hybrids show a narrow-band green emission peaked at 518 nm with photoluminescence quantum efficiencies(PLQEs)of 81.3%for(C_(13)H_(30)N)_(2)MnBr_(4)and 86.4%for(C_(19)H_(34)N)_(2)MnBr_(4),*** enable the solution processing of this promising metal halide hybrid,we successfully synthesized(C_(13)H_(30)N)_(2)MnBr_(4)colloidal nanocrystals for the first *** excited byβ-rays,(C_(13)H_(30)N)_(2)MnBr_(4)scintillators show a linear response toβ-ray dose rate over a broad range from 400 to 2,800 Gy·s^(−1),and also display robust radiation resistance that 80%of the initial RL intensity can be maintained after an ultrahigh accumulated radiation dose of 240 *** work will open up a new route for the development ofβ-ray scintillators.

关键词： zero-dimensional metal halide hybrids radiation sterilization β-ray scintillation nanocrystals

Predictive methods for density and refractive index of naphthenic lubricating oils during solvent extraction process

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Petroleum Science 2023年第3期20卷 1934-1946页

作者： Xiao-Ling Xu tian-qi Wang Guang-Huai Chen Jun-wei Hou Yan-Sheng Liu State Key Laboratory of Heavy Oil Processing China University of Petroleum(Bejing)at KaramayKaramayXinjiang834000China State Key Laboratory of Heavy oil Processing China University of Petroleum(Bejing)Bejing102200China

Lubricating oils are usually produced by solvent extraction to separate aromatics in order to achieve the desired specifications and better quality *** the different properties of lubricating oils,density and refractive index are some of the most important properties which can both be used for petroleum fluid *** of density and refractive index for naphthenic oils during solvent extraction by DMSO obtained by the pseudo-component approach and the quadratic correlation were both *** pseudo-component approach is a method to predict density and refractive index from composition while the latter merely relates density to refractive *** indicated that the predictions yielded by the pseudo-component method were in good agreement with experimental data for naphthenic *** the use of a function of refractive index(FRI_(20))as a pseudo-component property remarkably improved n_(20)predictions for the naphthenic ***,the density and refractive index predictions obtained by the quadratic correlation exhibited significantly higher de-viations for naphthenic oils than those for paraffinic *** a new modified correlation of the same functional form was proposed for naphthenic *** modification significantly improved predictions for naphthenic oils,which presented similar accuracy as the pseudo-component *** the previous correlation was still used for paraffinic ***,effect of temperature on density and refractive index of naphthenic oils was *** showed that the modified quadratic correlation was accurate for describing the relationship between density and refractive index of naphthenic oils at 20-90℃.The temperature dependence of density and refractive index for the raffinates and the extracts could be accurately described by the thermal coefficients for saturates and aromatics,*** the refractive index variation of the extracts with temperature,the

关键词： Density Refractive index Pseudo-components Paraffinic lubricating oils Naphthenic lubricating oils Solvent extraction

A novel stochastic collocation method for uncertainty propagation in complex mechanical systems

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Science China(Physics,Mechanics & Astronomy) 2015年第2期58卷 47-54页

作者： qi WuChao tian SuMei qiU ZhiPing Faculty of Aerospace Engineering Shenyang Aerospace University Institute of Solid Mechanics Beijing University of Aeronautics and Astronautics

This paper presents a novel stochastic collocation method based on the equivalent weak form of multivariate function integral to quantify and manage uncertainties in complex mechanical systems. The proposed method, which combines the advantages of the response surface method and the traditional stochastic collocation method, only sets integral points at the guide lines of the response surface. The statistics, in an engineering problem with many uncertain parameters, are then transformed into a linear combination of simple functions' statistics. Furthermore, the issue of determining a simple method to solve the weight-factor sets is discussed in detail. The weight-factor sets of two commonly used probabilistic distribution types are given in table form. Studies on the computational accuracy and efforts show that a good balance in computer capacity is achieved at present. It should be noted that it's a non-gradient and non-intrusive algorithm with strong portability. For the sake of validating the procedure, three numerical examples concerning a mathematical function with analytical expression, structural design of a straight wing, and flutter analysis of a composite wing are used to show the effectiveness of the guided stochastic collocation method.

关键词： uncertainty propagation stochastic collocation method equivalent weak form guided surface statistics

Review of research on high-speed railway aerodynamics in China

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Transportation Safety and Environment 2019年第1期1卷 1-21页

作者： Hong-qi tian Key Laboratory of Traffic Safety on Track of Ministry of Education Central South UniversityChangshaHunan 410075China Joint International Research Laboratory of Key Technology for Rail Traffic Safety ChangshaHunan 410075China School of Traffic&Transportation Engineering Central South UniversityChangshaHunan 410075China

High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway *** paper systematically summarizes the aerodynamic research relating to China’s high-speed railway *** key research advances are comprehensively discussed,including train aerodynamic drag-reduction technology,train aerodynamic noise-reduction technology,train ventilation technology,train crossing aerodynamics,train/tunnel aerodynamics,train/climate environment aerodynamics,and train/human body *** types of railway aerodynamic test platform built by Central South University are *** major systems for a high-speed railway network—the aerodynamics theoretical system,the aerodynamic shape(train,tunnel,and so on)design system,the aerodynamics evaluation system,the 3D protection system for operational safety of the high-speed railway network,and the high-speed railway aerodynamic test/computation/analysis platform system—are also ***,eight future development directions for the field of railway aerodynamics are *** over 30 years,railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network,which has also promoted the development of high-speed railway aerodynamics throughout the world.

关键词： aerodynamics high-speed railway drag reduction noise reduction train ventilation train crossing aerodynamics train/tunnel aerodynamics train/climate environment aerodynamics train/human body aerodynamics aerodynamic test platforms

Streptavidin-Biotin Complexes as Tools for Modulating an Important DNA Episgenetic Modification

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Chinese Journal of Chemistry 2024年第18期42卷 2166-2172页

作者： Yongjie Liu Xinyan Xu Xingyu Liu wei Xiong qianqian qi Yuanyuan Zhang Jinxuan Hou tian tian Xiang Zhoua Key Laboratory of Biomedical Polymers of Ministry of Education College of Chemistry and Molecular SciencesHubei Province Key Laboratory of Allergyand ImmunologyWuhan UniversityWuhanHubei 430072China Department of Thyroid&Breast Surgery Zhongnan Hospital of Wuhan UniversityWuhan UniversityWuhanHubei 430072China

DNA 5-formylcytosine(5fC)is a prominent epigenetic modification within biological *** investigations have shed light on its pivotal role in governing cell fate,gene expression,and disease ***,our comprehension of the precise control of the 5f site structure to influence its functionality remains *** this study,we have successfully achieved precise control over 5fc activity by harnessing the interaction between streptavidin and *** research underscores the potential application of interactions between biomacromolecules and small molecules in advancing the field of DNA epigenetic functional regulation.

关键词： Epigenetic modification Biotin Streptavidin Selectivity Regulation

Hydrogen embrittlement of X80 pipeline steel in H2S environment: Effect of hydrogen charging time, hydrogen-trapped state and hydrogen charging–releasing–recharging cycles

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International Journal of Minerals,Metallurgy and Materials 2020年第1期27卷 63-73页

作者： Peng-peng Bai Jie Zhou Bing-wei Luo Shu-qi Zheng Peng-yan Wang Yu tian State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China JAC Volkswagen Automotive Co. Ltd.Hefei 230601China SINOPEC Tenth Construction Company Ltd.Qingdao 266555China

This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S *** fracture strain of the steel samples decreased with increasing hydrogen pre-charging time;this steel degradation could almost be recovered after diffusible hydrogen was removed when the hydrogen pre-charging time was<8 ***,unrecoverable degeneration occurred when the hydrogen pre-charging time extended to 16–30 ***,nanovoid formation meant that the hydrogen damage to the steel under intermittent hydrogen pre-charging–releasing–recharging conditions was more serious than that under continuous hydrogen pre-charging *** study illustrated that the mechanical degradation of steel is inevitable in an H2S environment even if diffusible hydrogen is removed or visible hydrogen-induced cracking is ***,the steel samples showed premature fractures and exhibited a hydrogen fatigue effect because the repeated entry and release of diffusible hydrogen promoted the formation of vacancies that aggregated into *** results provide valuable information on the mechanical degradation of steel in an H2S environment,regarding the change rules of steel mechanical properties under different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles.

关键词： high-strength steel hydrogen embrittlement corrosion hydrogen diffusion

Effects of nitrogen application rates and irrigation regimes on grain yield and water use efficiency of maize under alternate partial rootzone irrigation

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Journal of Integrative Agriculture 2020年第11期19卷 2792-2806页

作者： qi Dong-liang HU tian-tian SONG Xue Engineering Research Center of Ecology and Agricultural Use of Wetland Ministry of EducationYangtze UniversityJingzhou 434025P.R.China Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education Northwest A&F UniversityYangling 712100P.R.China

Faced with the scarcity of water resources and irrational fertilizer use,it is critical to supply plants with water and fertilizer in a coordinated pattern to improve yield with high water use efficiency(WUE).One such method,alternate partial root-zone irrigation(APRI),has been practiced worldwide,but there is limited information on the performance of different irrigation regimes and nitrogen(N)rates under *** objectives of this study were to investigate the effects of varying irrigation regimes and N rates on shoot growth,grain yield and WUE of maize(Zea mays L.)grown under APRI in the Hexi Corridor area of Northwest China in 2014 and *** three N rates were 100,200 and 300 kg N ha–1,designated N1,N2 and N3,*** three irrigation regimes of 45–50%,60–65%and 75–80%field capacity(FC)throughout the maize growing season,designated W1,W2 and W3,respectively,were applied in combination with each N *** results showed that W2 and W3 significantly increased the plant height,stem diameter,crop growth rate,chlorophyll SPAD value,net photosynthetic rate(Pn),biomass,grain yield,ears per ha,kernels per cob,1000-kernel weight,harvest index,evapotranspiration and leaf area index(LAI)compared to W1 at each N *** N2 and N3 treatments increased those parameters compared to N1 in each irrigation *** the N rate from the N2 to N3 resulted in increased biomass and grain yield under W3 while it had no impact on those under the W1 and W2 *** W3 N3 and W2 N2 and W2 N3 treatments achieved the greatest and the second-greatest biomass and grain yield,*** the N rate significantly enhanced the maximum LAI(LAI at the silking stage)and Pn under W3,suggesting that the interaction of irrigation and fertilizer N management can effectively improve leaf growth and development,and consequently provide high biomass and grain yield of *** W2 N2,W2 N3 and W3 N3 treatments attained the greatest WUE among all the treatments.T

关键词： deficit irrigation nitrogen fertilization leaf area index net photosynthetic rate harvest index Zea mays