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Blindness-free beam scanning antenna with array of array architecture: principle,design,and experiment

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Science China(Information Sciences) 2024年第3期67卷 209-224页

作者： Jianxu SUN Yujian cheng School of Electronic Science and Engineering University of Electronic Science and Technology of China

This paper presents a 66–76-GHz sparsely-excited phased array antenna with the array of array(Ao A) architecture for eliminating the blindness and suppressing the grating lobe when scanning. For the array antennas printed on the thick dielectric layers with high relative permittivity, scanning blindness appears and seriously impacts the radiation performance. To address this issue, the Ao A topology is developed first. It finds that the scanning blindness appears due to the coupling of the radiating Floquet modes to the non-radiating surface wave(SW) modes. Therefore, the array is divided into two types of domino *** inner-phase distributions are introduced into the domino subarrays to break the one-to-one relationship between the Floquet mode and the SW mode. Then, the blindness inside ±60° scanning volume is eliminated by the aperiodic subarrays. Meanwhile, the aperiodic inner-phase distributions enhance the aperiodicity of the array and contribute to suppressing the grating lobe when scanning. Next, the meta-surface-based dipole with the shorted post is chosen as the unit cell for the proposed aperiodic array. Based on these methods,the array achieves the wide-scanning performance of ±60° in the E-plane and ±30° in the H-plane, without the blindness and the grating lobe. Finally, the 16×16 array is built and simulated with the dimension of32 mm × 32 mm. At the highest operating frequency, the simulated gains are 28.42, 25.17, and 24.01 d Bi when scanning to the broadside, 50° in the E-plane, and 30° in the H-plane, respectively. Compared to the ideal gain, it shows that the simulated radiation efficiency is about 84.13%, 62.08%, and 35.23% when scanning to the broadside, 50° in the E-plane, and 30° in the H-plane, respectively. The worst transmission coefficient, i.e., the worst isolation, is-11.97 d B between the central element and its two adjacent elements in the E-plane. The array prototypes are fabricated, and the experiments are carried out to ver

关键词： 6G communication systems phased array AoA aperiodic subarray wideband wide-scanning surface-wave scanning blindness grating lobe

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Hydrolysis of Aluminum Ions in Kaolinite and Oxisol Suspensions as Influenced by Organic Anions

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Pedosphere 2007年第1期17卷 90-96页

作者： XU Ren-Kou XIAO Shuang-cheng LI Jiu-Yu d. TIWARI JI Guo-Liang State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China） Graduate University of Chinese Academy of Sciences Beijing 100039 （China） department of Chemistry National Institute of Technology Jamshedpur-831 014 （India）

To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.

关键词： aluminum hydrolysis kaolinite organic anion Oxisol

Effects of Chordwise Flexibility on the Aerodynamic Performance of a 3d Flapping Wing

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Journal of Bionic Engineering 2015年第3期12卷 432-442页

作者： Xin cheng Shilong Lan Ministry-of-Education Key Laboratory of Fluid Mechanics Beijing University of Aeronautics & Astronautics Beijing China

Previous studies on chordwise flexibility of flexible wings generally relied on simplified two-dimensional （2d） models. In the present study, we constructed a simplified three-dimensional （3d） model and identified the role of the chordwise flexibility in full flapping motion. This paper includes two parts, the first part discusses the aerodynamic effects of the chordwise flexibility in a typical hovering-flight case; the second part introduces a parametric study of four key parameters. The primary findings are as follows. Flexibility generally degrades the lift performance of the flexible wings. However, in two special cases, i.e. when stroke amplitude is low or pitch rotation is delayed, the flexible wings outperform their rigid counterparts in lift generation. Moreover, flexibility reduces the power consumption of the flexible wings. A wing with small flexibility generally achieves a marginally higher flapping efficiency than its rigid counterpart. Furthermore, reducing stroke amplitude can effectively improve the lift performance of the very flexible wings. Aerodynamic performances of the flexible wings are not as sensitive as the rigid wing to phase difference and mid-stroke angle of attaek. The effects of Re are the same for the flexible and rigid wings.

关键词： flapping wing chordwise flexibility aerodynamic performances parametric study

Seed-hoarding of Edward＇s long-tailed rats Leopoldamys edwardsi in response to weevil infestation in cork oak Quer- cus variabilis

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Current Zoology 2011年第1期57卷 50-55页

作者： Jinrui cheng Hongmao ZHANG State Key Laboratory of Integrated Management of Pest Insects and Rodents in Agriculture Institute of Zoology the Chinese Academy of Sciences Datun Road Chaoyang District Beijing 100101 China Laboratory of Ecology and Evolutionary Biology College of Life Science Huazhong Normal University 152 Luoyu Avenue Wuhan 430079 China

Seed hoarders show different hoarding and eating responses towards insect-infested seeds that can affect the fitness of both the seeds and insects. It remains unclear how seed hoarders adopt different strategies in eating and hoarding infested seeds with and without larvae concealed inside. Here we investigated hoarding and eating responses of Edward＇s long-tailed rats Leo- poldamys edwardsi （scatter hoarders） to weevil infestation of cork oak Quercus variabilis seeds within outdoor enclosures. We provided sound seeds, larvae-emerged seeds, （infested seeds where larvae have emerged） and larvae-concealed seeds （infested seeds with larvae concealed inside） to subjects independently （each seed type presented separately） and in pairwise combina- tions （sound and larvae-emerged seeds; sound and larvae-concealed seeds）. We found that L. edwardsi removed, scatter hoarded and ate fewer larvae-emerged seeds than sound seeds. No difference was found between sound seeds and larvae-concealed seeds. These results suggest that sound and larvae-concealed seeds are more favored by L. edwardsi than larvae-emerged seeds. We posit that not only plants but also insects may benefit from the behavioral responses of hoarders to seed infestation under natural conditions

关键词： Larvae survival Seed discrimination Seed-hoarding Seed dispersal Weevil infestation

Genetic Variation Among the Geographic Population of the Grain Aphid, Sitobion avenae (Hemiptera: Aphididae) in China Inferred from Mitochondrial COI Gene Sequence

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Agricultural Sciences in China 2011年第7期10卷 1041-1048页

作者： XU Zhao-huan CHEN Ju-lian cheng deng-fa LIU Yong Frédéric Francis College of Plant Protection Shandong Agricultural University Tai＇an 271018 P.R.China State Key Laboratory for Biology of Plant disease and Insect Pests Institute of Plant Protection Chinese Academy of Agricultural Sciences Beijing 100193 P.R.China Functional and Evolutionary Entomology Gembloux Agro-Bio Tech University of Liege Passage des Déportés 2 Gembloux B-5030 Belgium

In order to characterize the genetic relationship of the geographic populations of Sitobion avenae （Hemiptera： Aphididae） in China, a 588 bp region of the mitochondrial cytochrome oxidase subunit I （mtdNA-COI） gene was sequenced and analyzed among the different geographic populations. 269 individuals were collected from 17 localities in different wheat-growing areas in China that covered most of the range reported for this species. Within the sequence among these geographic populations, 15 polymorphic sites defined 16 distinct haplotypes, ranging in sequence divergence from 0.2% （one nucleotide） to 1.7% （10 nucleotides）. Of the 15 variable sites, 12 were transitional substitutions, 2 were transversional substitutions and 1 was transitional and transversional substitution. Phylogenetic analysis showed that all haplotypes were highly interconnected with each other, in absence of phylogeographic structing. Each of 8 haplotypes was found only at one locality, and the other haplotypes were the widespread distributed in the different localities. The higher genetic diversity was found in the northern China populations than that in the southern China populations. The low genetic differentiation （FST=-0.06945-0.69857） and high migration rate （Nm=0.21575-infinite） of Chinese populations suggest that dispersal over long distance is a major factor in the demography of S. avenae.

关键词： Sitobion avenae insect pest mitochondrial dNA mtdNA-COI gene geographic variation

Permeability measurement of the fracture-matrix system with 3d embedded discrete fracture model

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Petroleum Science 2022年第4期19卷 1757-1765页

作者： Bao Jia cheng-Gang Xian State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Bejing)Beijing 102249China Unconventional Petroleum Research Institute China University of Petroleum(Bejing)Bejing 102249China

In this work, we performed the pulse-decay experiment on a fractured shale core and applied the 3 d embedded discrete fracture model(EdFM) to simulate the experiment process. The irregularly rough fracture surface was depicted in detail using a 3 d scanner. Then the fracture surface profile was imported in the discrete fracture network model to simulate the flow process in the fracture-matrix system realistically. History matching was efficiently performed to simultaneously obtain porosity and permeability for the matrix and fracture. Gas properties after applying nanopore confinement were obtained by modifying Sutton's viscosity correlation with sensitivity analysis on the pore diameter ranging from 2 to50 nm. Nanopore confinement results in low matched permeability due to viscosity reduction in the matrix-only porous media. The fracture-matrix system complicates the interpretation of nanopore confinement impact on flow behavior in shale reservoirs. different scenarios of the highly fractured and matrix-dominated systems were discussed in detail by constructing the digital twin model.

关键词： Permeability Fracture Pulse-decay Shale Viscosity

Application of material-mesh algebraic collapsing acceleration technique in method of characteristics——based neutron transport code

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Nuclear Science and Techniques 2021年第8期32卷 95-109页

作者： Ming dai Mao-Song cheng Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China CAS Innovative Academies in TMSR Energy System Chinese Academy of SciencesShanghai 201800China

The algebraic collapsing acceleration(ACA)technique maximizes the use of geometric flexibility of the method of characteristics(MOC).The spatial grids for loworder ACA are the same as the high-order transport,which makes the numerical solution of ACA equations costly,especially for large-size *** speed-up the MOC transport iterations effectively for general geometry,a coarse-mesh ACA method that involves selectively merging fine-mesh cells with identical materials,called material-mesh ACA(MMACA),is *** energy group batching(EGB)strategy in the tracing process is proposed to increase the parallel efficiency for microscopic crosssection *** and macroscopic crosssection benchmark problems are used to validate and analyse the accuracy and efficiency of the MMACA *** maximum errors in the multiplication factor and pin power distributions are from the VERA-4 B-2 d case with silver-indium-cadmium(AIC)control rods inserted and are 104 pcm and 1.97%,*** with the single-thread ACA solution,the maximum speed-up ratio reached 25 on 12 CPU cores for microscopic cross-section VERA-4-2 d *** the C5 G7-2 d and LRA-2 d benchmarks,the MMACA method can reduce the computation time by approximately one *** present work proposes the MMACA method and demonstrates its ability to effectively accelerate MOC transport iterations.

关键词： Algebraic collapsing acceleration Material-mesh ACA Method of characteristics OpenMP Arbitrary geometry

Fabrication and characteristics of nitrogen-doped nanocrystalline diamond/p-type silicon heterojunction

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Nano-Micro Letters 2010年第1期2卷 56-59页

作者： d.Lu H.d.Li S.H.cheng J.J.Yuan X.Y.Lv State Key Laboratory of Superhard Materials Jilin University

Nitrogen-doped nanocrystalline diamond films(N-NdFs)have been deposited on p-type silicon(Si)by microwave plasma chemical vapor *** reaction gases are methane,hydrogen,and nitrogen without the conventional argon(Ar).The N-NdFs were characterized by X-ray diffraction,Raman spectroscopy,and scanning electron *** grain sizes are of 8~10 nm in *** N-NdF shows n-type behavior and the corresponding N-NdF/p-Si heterojunction diodes are realized with a high rectification ratio of 102 at^7.8 V,and the current density reaches to1.35 A/cm2 at forward voltage of 8.5 *** findings suggest that fabricated by CH_4/H_2/N_2 without Ar,the N-NdFs and the related rectifying diodes are favorable for achieving high performance diamond-based optoelectronic devices.

关键词： Nanocrystalline diamond film Chemical vapor deposition Nitrogen doped Heterojunction diodes Current-voltage characteristics

SIMULATION OF FLUId-SOLId INTERACTION ON WATER dITCHING OF AN AIRPLANE BY ALE METHOd

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Journal of Hydrodynamics 2011年第5期23卷 637-642页

作者： HUA cheng FANG Chao cheng Jin department of Mechanics and Engineering Science Fudan University Shanghai 200433 China School of Mathematical Sciences Fudan University Shanghai 200433 China

ditching is considered as one of the important aspects of safety performances of airplanes. It is related primarily with the fluid-solid interaction, whose studies mainly depend on experiments at the present time. Numerical and analytical methods for fluid-solid interaction by using 3-d full scale airplane＇s model will reduce the dependence on the expensive model tests. Numerical studies can be used to estimate the safety of ditching and provide a reference for the crashworthiness design. This article proposes a 3-d dynamical structural model after the real shape of an airplane and an Arbitrary Lagrange-Euler （ALE） fluid-field model, to simulate the fluid-solid interactions caused by low speed ditching. The simulation is based on interaction computational methods, within LS-dYNA nonlinear finite-element code. The results of pressure distributions and accelerating time histories of the airplane＇s subfloor are discussed in the context of the safety of ditching, and the simulation results and the analytical methods are verified.

关键词： ditching fluid structure interaction Arbitrary Lagrange-Euler (ALE) finite element method