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Zhenyu Xiao,Lin Bai,Jinho Choi IEEE 2014 IEEE communications letters Vol.18 No.5
<P>In millimeter-wave communications (MMWC), in order to compensate for high propagation attenuation, phased arrays are favored to achieve array gain by beamforming, where transmitting and receiving antenna arrays need to be jointly trained to obtain appropriate antenna weight vectors (AWVs). Since the amplitude of each element of the AWV is usually constraint constant to simplify the design of phased arrays in MMWC, the existing singular vector based beamforming training scheme cannot be used for such devices. Thus, in this letter, a steering vector based iterative beamforming training scheme, which exploits the directional feature of MMWC channels, is proposed for devices with constant-amplitude phased arrays. Performance evaluations show that the proposed scheme achieves a fast convergence rate as well as a near optimal array gain.</P>
Novel Coronavirus Pneumonia Outbreak in 2019: Computed Tomographic Findings in Two Cases
Xiaoqi Lin,Zhenyu Gong,Zuke Xiao,Jingliang Xiong,Bing Fan,Jiaqi Liu 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.3
Since the 2019 novel coronavirus (2019-nCoV or officially named by the World Health Organization as COVID-19) outbreak in Wuhan, Hubei Province, China in 2019, there have been a few reports of its imaging findings. Here, we report two confirmed cases of 2019-nCoV pneumonia with chest computed tomography findings of multiple regions of patchy consolidation and ground-glass opacities in both lungs. These findings were characteristically located along the bronchial bundle or subpleural lungs.
Behavior of mercury release during thermal decomposition of coals
Shaoqing Guo,Yong Xiao,Jianli Yang,Zhenyu Liu 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.2
The mercury release behavior during thermal decomposition of three Chinese coals with different types was studied under nitrogen, carbon dioxide and air at temperatures of 800, 900, 1,000 and 1,100℃. The thermal treatment experiments were carried out in a quartz tube reactor. Results showed that the release ratio of total mercury during thermal decomposition of coals increases with the increasing temperature. The order of the amount of mercury released under the three atmospheres is nitrogen<carbon dioxide<air for all three coals during thermal decomposition. This indicates that air and carbon dioxide can promote the mercury release due to their reactivity with coal. However, the order of amount of elemental mercury released under the three atmospheres is nitrogen>carbon dioxide>air for all three coals. The release behavior of the total mercury under air is independent of the coal type. Under the other two atmospheres the release behavior is distinguished by the coal type.
New Construction Method for Quaternary Aperiodic, Periodic, and Z-Complementary Sequence Sets
Fanxin Zeng,Xiaoping Zeng,Zhenyu Zhang,Xiangyong Zeng,Guixin Xuan,Lingna Xiao 한국통신학회 2012 Journal of communications and networks Vol.14 No.3
Based on the known binary sequence sets and Gray mapping,a new method for constructing quaternary sequence sets is presented and the resulting sequence sets’ properties are investigated. As three direct applications of the proposed method, when we choose the binary aperiodic, periodic, and Z-complementary sequence sets as the known binary sequence sets, the resultant quaternary sequence sets are the quaternary aperiodic, periodic, and Z-complementary sequence sets, respectively. In comparison with themethod proposed by Jang et al., the new method can cope with either both the aperiodic and periodic cases or both even and odd lengths of sub-sequences, whereas the former is only fit for the periodic case with even length of sub-sequences. As a consequence,by both our and Jang et al.’s methods, an arbitrary binary aperiodic,periodic, or Z-complementary sequence set can be transformed into a quaternary one no matter its length of sub-sequences is odd or even. Finally, a table on the existing quaternary periodic complementary sequence sets is given as well.
Adaptive Fuzzy Output Regulation for Unmanned Surface Vehicles with Prescribed Performance
Shaobao Li,Tingting Ma,Xiao-yuan Luo,Zhenyu Yang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2
Dynamics of an unmanned surface vehicle (USV) is usually hard to be modeled accurately due to system uncertainties and disturbances, which can significantly reduce system control performance. To guarantee a satisfied control performance under modeling uncertainties and disturbances, a novel control scheme combining adaptive fuzzy output regulation control and prescribed performance control is proposed in this paper. The unknown nonlinear dynamics of the USV is firstly approximated by a fuzzy logic system, and then an adaptive output regulation control law is developed using backstepping approach for the USV to track a reference system while rejecting disturbances and approximation errors induced by the fuzzy logic system. Meanwhile, the prescribed performance control technique is combined to the adaptive output regulation control design to reach a desired control performance in spite of the unknown system dynamics and disturbances. A simulation study is finally provided to demonstrate the effectiveness of the proposed approach.
Zeng, Fanxin,Zeng, Xiaoping,Xiao, Lingna,Zhang, Zhenyu,Xuan, Guixin The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.6
Based on an interleaving technique and quadriphase periodic complementary sequence (CS) mates, this paper presents a method for constructing a family of 16-quadrature amplitude modulation (QAM) periodic CS mates. The resulting mates arise from the conversion of quadriphase periodic CS mates, and the period of the former is twice as long as that of the latter. In addition, based on the existing binary periodic CS mates, a table on the existence of the proposed 16-QAM periodic CS mates is given. Furthermore, the proposed method can also transform a mutually orthogonal (MO) quadriphase CS set into an MO 16-QAM CS set. Finally, three examples are given to demonstrate the validity of the proposed method.
Fanxin Zeng,Xiaoping Zeng,Lingna Xiao,Zhenyu Zhang,Guixin Xuan 한국통신학회 2013 Journal of communications and networks Vol.15 No.6
Based on an interleaving technique and quadriphase periodiccomplementary sequence (CS) mates, this paper presents amethod for constructing a family of 16-quadrature amplitudemodulation(QAM) periodic CS mates. The resulting mates arise fromthe conversion of quadriphase periodic CS mates, and the period ofthe former is twice as long as that of the latter. In addition, basedon the existing binary periodic CS mates, a table on the existenceof the proposed 16-QAM periodic CS mates is given. Furthermore,the proposed method can also transform a mutually orthogonal(MO) quadriphase CS set into an MO 16-QAM CS set. Finally,three examples are given to demonstrate the validity of the proposedmethod.
New Construction Method for Quaternary Aperiodic, Periodic, and Z-Complementary Sequence Sets
Zeng, Fanxin,Zeng, Xiaoping,Zhang, Zhenyu,Zeng, Xiangyong,Xuan, Guixin,Xiao, Lingna The Korea Institute of Information and Commucation 2012 Journal of communications and networks Vol.14 No.3
Based on the known binary sequence sets and Gray mapping, a new method for constructing quaternary sequence sets is presented and the resulting sequence sets' properties are investigated. As three direct applications of the proposed method, when we choose the binary aperiodic, periodic, and Z-complementary sequence sets as the known binary sequence sets, the resultant quaternary sequence sets are the quaternary aperiodic, periodic, and Z-complementary sequence sets, respectively. In comparison with themethod proposed by Jang et al., the new method can cope with either both the aperiodic and periodic cases or both even and odd lengths of sub-sequences, whereas the former is only fit for the periodic case with even length of sub-sequences. As a consequence, by both our and Jang et al.'s methods, an arbitrary binary aperiodic, periodic, or Z-complementary sequence set can be transformed into a quaternary one no matter its length of sub-sequences is odd or even. Finally, a table on the existing quaternary periodic complementary sequence sets is given as well.
Nian Cheng,Weiwei Li,Menghan Zhang,Hangjuan Wu,Shujie Sun,Zhiqiang Zhao,Zhenyu Xiao,Zhuzhu Sun,Wei Zi,Liang Fang 한국물리학회 2019 Current Applied Physics Vol.19 No.1
Employing additive to regulate the morphology of perovskite film is an effective method to enhance both the power conversion efficiency and long term stability of organic-inorganic hybrid perovskite solar cells. Here, we demonstrate that guanidinium thiocyanate (GuSCN) is a suitable additive for methylammonium lead iodide (MAPbI3) perovskite materials. Addition of GuSCN into MAPbI3 can simultaneously enhance the crystallinity, enlarge the crystal size, and reduce the trap density of the perovskite films. As a result, the MAPbI3 perovskite with 10% GuSCN exhibits superior power conversion efficiency of 16.70% compared to the pristine MAPbI3 perovskite solar cell (15.57%). At the same time, the MAPbI3 perovskite solar cell with GuSCN additive shows better stability, power conversion efficiency retains ∼90% of its initial value compared to only ∼60% for pristine MAPbI3 perovskite solar cells after being stored for 15 days without encapsulation