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| 1 | A Precise Calibration Method on Phase Center of Uplink Antenna Array Considering Its Actual Pointing显示文摘With regard to the inferior techniques and low accuracy of phase center calibration of an antenna array, this paper proposes a new calibration method considering the actual antenna pointing by introducing a precise engineering surveying technique to measure the real state of antennas. First, an industrial photogrammetric system is utilized to obtain the coordinates of points on antenna panels in different postures, and the actual pointing of the mechanical axis is obtained via least-squares fitting. Then, based on this, the coordinates of antenna rotation center are obtained by seeking the intersection of mechanical axes via using the matrix method. Finally, the mechanical axis in arbitrary postures is estimated based on the inverse-angle weighting interpolation method, and the reliable phase center is obtained by moving a fixed length from the projective center along the mechanical axis. An uplink antenna array including three ? 3 m antennas is taken as experimental object, and all photogrammetric coordinate systems are unified by the engineering control network, with each antenna phase center precisely calibrated via the proposed method. The results of electrical signal synthesis indicate that this method can effectively overcome the influence of gravity deformation and mechanical installation error, and enhance the synthetic signal magnitude of the uplink antenna array. | Zongchun LI Zhiyong LU Guanyu ZHANG Bo LIU Qiqiang FENG Yinggang GUO Hua HE | 2020 | Journal of Geodesy and Geoinformation Science2020，3，1： | 2 |
| 2 | Randomized trial of autologous bone marrow mesenchymal stem cells transplantation for hepatitis B virus cirrhosis: Regulation of T reg/ T h17 cells显示文摘 | Lanman Xu Yuewen Gong Benfu Wang Keqing Shi Yijun Hou Liping Wang Zuo Lin Yixiang Han Lu Lu Dazhi Chen Xiuli Lin Qiqiang Zeng Wenke Feng Yongping Chen | 2014 | J Gastroenterol Hepatol2014，，8： | 1 |
| 3 | Synthesis and property characterization of ternary laminar Zr_(2)SB ceramic显示文摘In this paper,Zr_(2)SB ceramic with purity of 82.95 wt%(containing 8.96 wt%ZrB_(2)and 8.09 wt%zirconium)and high relative density(99.03%)was successfully synthesized from ZrH_(2),sublimated sulfur,and boron powders by spark plasma sintering(SPS)at 1300℃.The reaction process,microstructure,and physical and mechanical properties of Zr_(2)SB ceramic were systematically studied.The results show that the optimum molar ratio to synthesize Zr_(2)SB is n(ZrH_(2)):n(S):n(B)=1.4:1.6:0.7.The average grain size of Zr_(2)SB is 12.46μm in length and 5.12μm in width,and the mean grain sizes of ZrB2 and zirconium impurities are about 300 nm.In terms of physical properties,the measured thermal expansion coefficient(TEC)is 7.64×10^(-6) K^(-1) from room temperature to 1200℃,and the thermal capacity and thermal conductivity at room temperature are 0.39 J·g^(-1)·K^(-1)and 12.01 W·m^(-1)·K^(-1),respectively.The room temperature electrical conductivity of Zr_(2)SB ceramic is measured to be 1.74×10^(6)Ω^(-1)·m^(-1).In terms of mechanical properties,Vickers hardness is 9.86±0.63 GPa under 200 N load,and the measured flexural strength,fracture toughness,and compressive strength are 269±12.7 MPa,3.94±0.63 MPa·m1/2,and 2166.74±291.34 MPa,respectively. | Qiqiang ZHANG Shuai FU Detian WAN Yiwang BAO Qingguo FENG Salvatore GRASSO Chunfeng HU | 2022 | Journal of Advanced Ceramics2022，11，5： | 1 |
| 4 | Synthesis and characterization of high entropy(TiVNbTaM)_(2)AlC(M=Zr,Hf)ceramics显示文摘The high-entropy design of MAX phases is expected to confer superior properties,but its study was hindered by the complex synthesis method and limited purity of samples.In this work,two noteworthy types of high-entropy MAX phase structural ceramics,high-entropy(TiVNbTaM)_(2)AlC(M=Zr,Hf),were designed and prepared by the in-situ synthesis using spark plasma sintering(SPS).The microstructure and lattice parameters of sintered samples were determined.Compared with the single-component MAX phases,the highly pure high-entropy(TiVNbTaZr)_(2)AlC sample had good physical and mechanical properties,including electrical conductivity of 0.96×106Ω^(-1)·m^(-1),thermal expansion coefficient of 3.65×10^(-6) K^(-1),thermal conductivity of 8.98 W·m^(-1)·K^(-1),Vickers hardness of 9.80 GPa,flexural strength of 507 MPa,fracture toughness of 5.62 MPa·m^(1/2),and compressive strength of 1364 MPa,which exhibited the remarkable hardening-strengthening effect. | Lei Cao Qiqiang Zhang Lijing Du Shuai Fu Detian Wan Yiwang Bao Qingguo Feng Chunfeng Hu | 2024 | Journal of Advanced Ceramics2024，13，2： | 0 |
| 5 | Road Damage Detection and Classification Using Mask R-CNN with DenseNet Backbone显示文摘Automatic road damage detection using image processing is an important aspect of road maintenance.It is also a challenging problem due to the inhomogeneity of road damage and complicated background in the road images.In recent years,deep convolutional neural network based methods have been used to address the challenges of road damage detection and classification.In this paper,we propose a new approach to address those challenges.This approach uses densely connected convolution networks as the backbone of the Mask R-CNN to effectively extract image feature,a feature pyramid network for combining multiple scales features,a region proposal network to generate the road damage region,and a fully convolutional neural network to classify the road damage region and refine the region bounding box.This method can not only detect and classify the road damage,but also create a mask of the road damage.Experimental results show that the proposed approach can achieve better results compared with other existing methods. | Qiqiang Chen Xinxin Gan Wei Huang Jingjing Feng H.Shim | 2020 | Computers, Materials & Continua2020，，12： | 0 |
| 6 | Chemistry of marine resources-XIX. The molecule design and synthesis of crow-link type Alkyd resin and its enrichment behaviour For potassium ion in sea water显示文摘Chemistryofmarineresources-XIX.Themoleculedesignandsynthesisofcrow-linktypealkydresinanditsenrichmentbehaviourforpotassiumion... | Sun Yushan Feng Fei Sun Hanzhang Peng Qiqiang Xia Zongfeng and Wang Wei(Department of Marine Chemistry, Ocean University of Qingdao, Qingdao 266003, China) | 1994 | Acta Oceanologica Sinica1994，13，3： | 0 |
| 7 | Zr_(2)SeB and Hf_(2)SeB:Two new MAB phase compounds with the Cr_(2)AlC-type MAX phase(211 phase)crystal structures显示文摘The ternary or quaternary layered compounds called MAB phases are frequently mentioned recently together with the well-known MAX phases.However,MAB phases are generally referred to layered transition metal borides,while MAX phases are layered transition metal carbides and nitrides with different types of crystal structure although they share the common nano-laminated structure characteristics.In order to prove that MAB phases can share the same type of crystal structure with MAX phases and extend the composition window of MAX phases from carbides and nitrides to borides,two new MAB phase compounds Zr_(2)SeB and Hf_(2)SeB with the Cr_(2)AlC-type MAX phase(211 phase)crystal structure were discovered by a combination of first-principles calculations and experimental verification in this work.First-principles calculations predicted the stability and lattice parameters of the two new MAB phase compounds Zr_(2)SeB and Hf_(2)SeB.Then they were successfully synthesized by using a thermal explosion method in a spark plasma sintering(SPS)furnace.The crystal structures of Zr_(2)SeB and Hf_(2)SeB were determined by a combination of the X-ray diffraction(XRD),scanning electron microscopy(SEM),and high-resolution transmission electron microscopy(HRTEM).The lattice parameters of Zr_(2)SeB and Hf_(2)SeB are a=3.64398Å,c=12.63223Åand a=3.52280Å,c=12.47804Å,respectively.And the atomic positions are M at 4f(1/3,2/3,0.60288[Zr]or 0.59889[Hf]),Se at 2c(1/3,2/3,1/4),and B at 2a(0,0,0).And the atomic stacking sequences follow those of the Cr_(2)AlC-type MAX phases.This work opens up the composition window for the MAB phases and MAX phases and will trigger the interests of material scientists and physicists to explore new compounds and properties in this new family of materials. | Qiqiang ZHANG Yanchun ZHOU Xingyuan SAN Wenbo LI Yiwang BAO Qingguo FENG Salvatore GRASSO Chunfeng HU | 2022 | Journal of Advanced Ceramics2022，11，11： | 0 |
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