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Optical transparent metamaterial structure for microwave-infrared-compatible camouflage based on indium tin oxide

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Science China(Technological Sciences) 2023年第10期66卷 2850-2861页

作者： LUO Hui XIONG Yao CHENG YongZhi CHEN Fu li xiangcheng School of Information Science and Engineering Wuhan University of Science and TechnologyWuhan 430081China State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China

A visible transparent metamaterial absorber was designed and fabricated with ultrabroadband microwave absorption and low infrared emissivity to meet the increasing demand for multispectral compatible camouflage. The absorber was fabricated with a low-infrared emissive layer at the top, a microwave-absorbing layer in the middle, and a reflective layer at the bottom, which were separated by polymethyl methacrylate plates. The absorber showed an average visible transmittance of 55%, infrared emissivity of ~0.37, and effective microwave absorption bandwidth of 32.1 GHz with a total thickness of 3.0 mm. Furthermore,microwave absorption exhibited wide-angle stability and polarization insensitivity characteristics. The mechanism of microwave attenuation was further explored through effective electromagnetic parameters as well as surface current, electric field, magnetic field, and energy loss density distributions. The experimental results were consistent with those of the simulations and calculations, indicating the potential of the designed metamaterial absorber for future applications in multispectral compatible camouflage.

关键词： optical transparent microwave absorption metamaterial low infrared emissivity indium tin oxide

Two-Stage Constructions for the Rate-Compatible Shortened Polar Codes

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Tsinghua Science and Technology 2023年第2期28卷 269-282页

作者： Chunjie li Haiqiang Chen Zelin Wang Youming Sun xiangcheng li Tuanfa Qin School of Computer Electronics and Information and Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information ProcessingGuangxi UniversityNanning 530004China Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education Guangxi UniversityNanning 530004China

In this paper,we propose the two-stage constructions for the rate-compatible shortened polar(RCSP)*** the Stage-I construction,the shortening pattern and the frozen bit are jointly designed to make the shortened bits be completely known by the ***,a distance-greedy algorithm is presented to improve the minimum Hamming distance of the *** design the remaining Stage-II frozen bits,three different construction algorithms are further presented,called the Reed-Muller(RM)construction,the Gaussian Approximation(GA)construction,and the RM-GA *** we give the row weight distribution numerical results of the generator matrix after the Stage-I and Stage-II constructions,which shows that the proposed constructions can efficiently increase the minimum Hamming *** results show that the proposed RCSP codes have excellent frame error rate(FER)performances at different code lengths and code *** specifically,the RM-GA construction performs best and can achieve at most 0.8 dB gain compared to the Wang14 and the quasi-uniform puncturing(QUP)*** RM construction is designed completely by the distance-constraint without channel evaluation thus has the simplest ***,it still has better FER performance than the existing shortening/puncturing schemes,especially at high signal noise ratio(SNR)region.

关键词： polar codes rate-compatibility Reed-Muller codes Hamming distance shortening

An Iterative Detection/Decoding Algorithm of Correlated Sources for the LDPC-Based Relay Systems

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China Communications 2017年第9期14卷 190-198页

作者： Haiqiang Chen Hang Cao xiangcheng li Youming Sun Haibin Wan Tuanfa Qin The School of Computer and Electronic Information Guangxi University Guangxi Key Laboratory of Multimedia Communications and Network Technology Guangxi University Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information Processing Guangxi University

An iterative detection/decoding algorithm of correlated sources for the LDPC-based relay systems is presented. The signal from the source-destination(S-D) link is formulated as a highly correlated counterpart from the relay-destination(R-D) link. A special XOR vector is defined using the correlated hard decision information blocks from two decoders and the extrinsic information exchanged between the two decoders is derived by the log-likelihood ratio(LLR) associated with the XOR vector. Such the decoding scheme is different from the traditional turbo-like detection/decoding algorithm, where the extrinsic information is computed by the side information and the soft decoder outputs. Simulations show that the presented algorithm has a slightly better performance than the traditional turbo-like algorithm(Taking the(255,175) EG-LDPC code as an example, it achieves about 0.1 dB performance gains aroundBLER=10^(-4)). Furthermore, the presented algorithm requires fewer computing operations per iteration and has faster convergence rate. For example, the average iteration of the presented algorithm is 33 at SNR=1.8 dB, which is about twice faster than that of the turbo-like algorithm, when decoding the(961,721) QC-LDPC code. Therefore, the presented decoding algorithm of correlated sources provides an alternative decoding solution for the LDPC-based relay systems.

关键词： correlated sources iterative de-coding LDPC codes relay channel

Corrosion Behavior of Slags with Different Basicities to Alumina Magnesia Castables

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China's Refractories 2012年第4期21卷 17-21页

作者： ZHANG Qiaoyan ZHU Boquan li xiangcheng The Key State Laboratory Breeding Base of Refractories and Ceramics Wuhan University of Science and Technology

Alumina magnesia castable crucible specimens were prepared using tabular corundum （ ≤ 5 mm ）, fused magnesia powder （ ≤0. 088 mm ） , fused spinel powder （ ≤0. 044 mm ） , and α-Al2O3. micropowder （d50 ≤0. 7 μm ） as main starting materials, batching, mixing, shaping, and drying. Slag resistance was determined by static crucible method at 1 600℃ for 3 h adopting two ladle slags with different basicities （3. 40 and 1.03 ）. The corrosion and penetration indexes and microstructure characteristics of the specimens after slag resistance test were analyzed to study the corrosion behaviors of the two slags to alumina magnesia castables. The results show that the corrosion of the low basicity slag to alumina magnesia custables is much more serious than that of the high basicity slag for that their reactions with castables form different products;for the low basicity slab,, the multi-phase coexistence of CA6 and compounds of CaO - Al2O3 -SiO2 in the materials together with volume expansion caused by the formation of CA6 intensify the slag corrosion and penetration ; for the high basicity slag, the reaction between slag and castables generates a CA2 dense layer and a large amount of in-situ MA in the interface, reducing the slag corrosion to the materials effectively.

关键词： basicity slag resistance alumina magnesia castables

Effects of Magnesia Fines Addition and Spinel with Different Compositions on Thermal Expansion Behavior of Alumina Magnesia Castables

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China's Refractories 2012年第2期21卷 23-27页

作者： ZHANG Qiaoyan ZHU Boquan li xiangcheng The Key State Laboratory Breeding Base of Refractories and Ceramics Wuhan University of Science and Technology Wuhan 430081 China

Effects of magnesia fines addition （ 4%, 6% and 8% in mass ） and spinel with different compositions （alumina-rich, magnesia-rich and stoichiometric spi-nel） on thermal expansion behavior of alumina magne-sia castables were researched using tabular corundum, magnesia fines, spinel fines, p-A12O3, Secar-71 cement and SiO2 fume as main starting materials. The results show that：（1） thermal expansion coefficients of speci- mens with 4 mass% and 6 mass% magnesia fines have the similar change tendency, increasing slightly with temperature rising ; when magnesia addition is 8 mass% , the thermal expansion coefficient increases ob-viously at Ⅰ 050 ℃ and reaches the peak at 1 350 ℃ ; （2） when MgO content is the same, the specimen with magnesia-rich spinel has the lowest thermal expansion coefficient; （3） for the castables specimens with the same MgO content, the specimen with magnesia has higher thermal expansion coefficient than that with pre-synthesized spin, el, which is related with the secondary spinelization dttriag the heating process.

关键词： magnesia spinel castables thermal ex-pansion

Synthesis of FER Zeolite Using 4-(Aminomethyl)pyridine as Structure-directing Agent

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Chemical Research in Chinese Universities 2022年第1期38卷 243-249页

作者： liANG Jun FU Wenhua liU Chuang li xiangcheng WANG Yu MA Duozheng li Yuekun WANG Zhendong YANG Weimin School of Chemical Engineering East China University of Science and TechnologyShanghai 200237P.R.China State Key Laboratory of Green Chemical Engineering and Industrial Catalysis Sinopec Shanghai Research Institute of Petrochemical TechnologyShanghai 201208P.R.China

This paper describes the synthesis of FER zeolite using commercially available 4-(aminomethyl)pyridine as organic structure-directing agent(OSDA). FER zeolites were prepared in mixtures with SiO2/Al2O3 molar ratios in a narrow range and the resultant products possessed a typical flake-shaped morphology. The crystallization of FER zeolite was tracked in order to better understand the formation mechanism and the products obtained at different crystallization time were systematically characterized using multiple techniques. It showed that a majority of Si atoms and nearly all the Al atoms transformed into the solid phase during the hydrothermal synthesis. The rearrangement of inorganic species gave rise to zeolitic 5-membered rings(5-MRs) and 6-membered rings(6-MRs). Consequently, FER zeolite crystals were formed by the consumption of amorphous bulky gel/solid matrix. Tracking the synthesis process of FER can help.

关键词： FER zeolite 4-(Aminomethyl)pyridine Crystal growth

Polar codes: Encoding/decoding and rate-compatible jointly design for HARQ system

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Intelligent and Converged Networks 2021年第4期2卷 334-346页

作者： Qiaoli Zeng Quan Zhou Xiangkun He Youming Sun xiangcheng li Haiqiang Chen School of Computer Electronics and Information and Guangxi Colleges and Universities Key Laboratory of Multimedia Communications and Information ProcessingGuangxi UniversityNanning 530004China Department of Mechanical and Aerospace Engineering Nanyang Technological UniversitySingapore 999002Singapore

Polar coding are the first class of provable capacity-achieving coding techniques for a wide range of *** an ideal recursive structure and many elegant mathematical properties,polar codes are inherently implemented with low complexity encoding and decoding *** the block length of the original polar construction is limited to powers of two,rate-compatible polar codes(RCPC)are presented to meet the flexible length/rate transmission requirements in *** RCPC codes are well-conditioned to combine with the hybrid automatic repeat request(HARQ)system,providing high throughput efficiency and such RCPC-HAPQ scheme is commonly used in delay-insensitive communication *** paper first gives a survey of both the classical and state-of-the-art encoding/decoding algorithms for polar *** the RCPC construction methods are discussed,including the puncturing,shortening,multi-kernel construction,***,we investigate several RCPC-HARQ jointly design systems and discuss their encoding gain and re-transmission diversity gain.

关键词： polar code rate compatible hybrid automatic re-transmission request polar coding/decoding

Carbonization of Ni-doped Phenol Resin Under Various Conditions

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China's Refractories 2017年第2期26卷 25-30页

作者： WEI Guoping ZHU Boquan li xiangcheng MA Zheng Zhejiang Zili Co. Ltd. The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology

Ni-doped phenol resin was prepared with 1∶100 mass ratio of Ni（ NO_3）_2·6H_2O to thermosetting phenol resin to optimize the structure and properties of pyrolytic carbon derived from phenol resin and increase its carbon yield. The specimens were cured at 200 ℃ and carbonized under different atmospheres（ carbon-embedded atmosphere and Ar atmosphere） and at different temperatures（ 600,800,1000 and 1200 ℃） for3 h,respectively. The carbon yield was measured. Thermal decomposition characteristics of Ni-doped phenol resin,and the oxidation resistance,phase composition and microstructure of pyrolytic carbon were characterized by differential scanning calorimetry,X-ray diffraction,energy dispersive spectroscopy, scanning electron microscopy and transmission electron microscopy. The results show that the carbon yield of Ni-doped phenol resin carbonized at800 or 1 000 ℃ is increased significantly,compared with that without any dopants. The graphitization degree of pyrolytic carbon structure derived from Ni-doped phenol resin increases with the increase of carbonization temperature. The massive multi-wall carbon nanotubes of 50-100 nm in diameter and of micrometre scale in length are generated at 1000 ℃. Compared with the carbonembedded atmosphere,carbon nanotubes can be more easily generated in Ar atmosphere,resulting in higher carbon yield and degree of crystallinity of the pyrolyticcarbon derived from Ni-doped phenol resin. The oxidation resistance of the pyrolytic carbon derived from Ni-doped phenol resin at 1200 ℃ is improved significantly and its highest oxidation temperature is increased by about 84℃,compared with that from Ni free phenol resin.

关键词： phenol resin nickel-doping carboniza-tion pyrolytic carbon carbon nanotubes oxidation re-sistance

Influences of Al and Si Powders on Microstructure and Hot Mechanical Properties of Al_2O_3-C Slide Plates

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China's Refractories 2014年第3期23卷 31-34页

作者： ZHAO Fei ZHU Boquan li xiangcheng ZHU Yuenan The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology

The basic formulation of Al2O3- C slide plates was65%（ in mass,the same hereinafter） white fused corundum particles,25% white fused corundum fines,6% active α-Al2O3 micropowder,4% carbon black and flake graphite, and additional 4% phenolic *** on this formulation,3% Al powder,3% Si powder,and 3% Al ＋ 3% Si powder were used to substitute equivalent white corundum fines to improve the hot mechanical properties of Al2O3- C slide plates. The specimens with dimensions of 140 mm × 25 mm × 25 mm were pressed at 150 MPa,dried at 200 ℃ for 24 h,and hot treated at 1 400 ℃ for 3 h in carbon embedded condition. Then hot modulus of rupture and thermal shock resistance of the specimens were tested and the phase compositions and microstructure were analyzed. The results show that specimen with 3% Al powder has the higher hot modulus of rupture but lower residual modulus of rupture after thermal shock than the specimen with3% Si powder; the specimen with 3% Al ＋ 3% Si powders exhibits the highest hot modulus of rupture and the best thermal shock resistance; the change of mechanical property is closely related with the in-situ formed nonoxides： AlN in the form of bars is formed in specimens with Al powder; fibrous SiC whiskers are formed in specimens with Si powder; in the specimens with both Al and Sipowders,besides AlN and SiC whiskers,hexagonal tabular SiAlON is in-situ synthesized,which interlocks with each other.

关键词： aluminum powder silicon powder alumi-na - carbon slide plate hot mechanical property mi-crostructure