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A fast method to diagnose phase transition from amorphous to microcrystalline silicon

Science China(Physics,Mechanics & Astronomy) 2007年第6期50卷 731-736页

作者： HOU GuoFu1,2,3,XUE JunMing1,2,3,YUAN YuJie1,2,3,SUN Jian1,2,3,ZHAO Ying1,2,3 & GENG XinHua1,2,3 1 Institute of Photoelectronics,Nankai University,Tianjin 300071,China 2 Tianjin Key Laboratory of Photoelectronic Thin Film Devices and Technique,Tianjin 300071,China 3 Key Laboratory of Optoelectronic Information Science and Technology of Ministry of Education of China,Tianjin 300071,China Institute of Photoelectronics Nankai University Tianjin China Tianjin Key Laboratory of Photoelectronic Thin Film Devices and Technique Tianjin China Key Laboratory of Optoelectronic Information Science and Technology of Ministry of Education of China Tianjin China

A series of hydrogenated silicon thin films were prepared by the radio frequency plasma enhanced chemical vapor deposition method (RF-PECVD) with various si-lane concentrations. The influence of silane concentration on structural and elec-trical characteristics of these films was investigated to study the phase transition region from amorphous to microcrystalline phase. At the same time,optical emis-sion spectra (OES) from the plasma during the deposition process were monitored to get information about the plasma properties,Raman spectra were measured to study the structural characteristics of the deposited films. The combinatorial analysis of OES and Raman spectra results demonstrated that the OES can be used as a fast method to diagnose phase transition from amorphous to microcrystalline silicon. At last the physical mechanism,why both OES and Raman can be used to diagnose the phase transition,was analyzed theoretically.

关键词： amorphous silicon, microcrystalline silicon, phase transition, optical emission spectroscopy A series of hydrogenated silicon thin films were prepared by the radio frequency plasma enhanced chemical vapor deposition method (RF-PECVD) with various silane concentrations. The influence of silane concentration on structural and electrical characteristics of these films was investigated to study the phase transition region from amorphous to microcrystalline phase. At the same time, optical emission spectra (OES) from the plasma during the deposition process were monitored to get information about the plasma properties, Raman spectra were measured to study the structural characteristics of the deposited films. The combinatorial analysis of OES and Raman spectra results demonstrated that the OES can be used as a fast method to diagnose phase transition from amorphous to microcrystalline silicon. At last the physical mechanism, why both OES and Raman can be used to diagnose the phase transition, was analyzed theoretically.……

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Energy Efficient Constrained Shortest Path First-Based Joint Resource Allocation and Route Selection for Multi-Hop CRNs

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China Communications 2017年第12期14卷 72-86页

作者： Qianbin Chen Ling Wang Yuanpeng Gao Rong Chai Xiaoge Huang Key Lab of Mobile Communication Technology Chongqing University of Posts and Telecommunications Chongqing 400065 China

Cognitive radio networks(CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users(SUs) to opportunistically access the licensed spectrum of primary users(PUs).In CRNs,source and destination SUs may achieve information interaction in an ad hoc manner.In the case that no direct transmission link between the SU transmission pairs is available,multi-hop relay SUs can be applied to forward information for the source and destination SUs,resulting in multi-hop CRNs.In this paper,we consider a multi-hop CRN consisting of multiple PUs,SU transmission pairs and relay SUs.Stressing the importance of transmission hops and the tradeoff between data rate and power consumption,we propose an energy efficient constrained shortest path first(CSPF)-based joint resource allocation and route selection algorithm,which consists of two sub-algorithms,i.e.,CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm.More specifically,we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes(SCRs) between the SU pair under the transmission constraints.Then,an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method.Simu-lation results demonstrate the effectiveness of the proposed algorithm.

关键词： cognitive radio network multi-hop relay resource allocation route selection energy efficiency

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利用电光FM调制抑制零级中心频带——实现超高频radio over Fiber通信

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光子学报 2008年第10期37卷 1966-1969页

作者：李广黄旭光华南师范大学光子信息技术广东省高校重点实验室广州510006

提出了一种有效抑制零级中心频带方案,并证实了该方案的可行性,给出了基于该方案的单工radioover Fiber(RoF)通信系统.通过光通信系统软件Optisystem5.0仿真模拟结果显示:光源发送功率为5dBm,途中无光放大,24GHz的超高频微波信号在色散... 详细信息

提出了一种有效抑制零级中心频带方案,并证实了该方案的可行性,给出了基于该方案的单工radioover Fiber(RoF)通信系统.通过光通信系统软件Optisystem5.0仿真模拟结果显示:光源发送功率为5dBm,途中无光放大,24GHz的超高频微波信号在色散系数为20ps/nm/km、衰减系数为0.25dB/km的单模光纤中传输,系统码元传输速率可达5Gbit/s、传输距离15km以上.

关键词：电光频率调制零级中心频带 radio over Fiber 光纤通信系统无线通信网络超高频(UHF)无线通信

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6G Visions:Mobile Ultra-Broadband,Super Internet-of-Things,and Artificial Intelligence

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China Communications 2019年第8期16卷 1-14页

作者： Lin Zhang Ying-Chang Liang Dusit Niyato University of Electronic Science and Technology of China Chengdu 611731China Nanyang Technological University 639798Singapore

With a ten-year horizon from concept to reality, it is time now to start thinking about what will the sixth-generation(6G) mobile communications be on the eve of the fifth-generation(5G) deployment. To pave the way for the development of 6G and beyond, we provide 6G visions in this paper. We first introduce the state-of-the-art technologies in 5G and indicate the necessity to study 6G. By taking the current and emerging development of wireless communications into consideration, we envision 6G to include three major aspects, namely, mobile ultra-broadband, super Internet-of-Things(IoT), and artificial intelligence(AI). Then, we review key technologies to realize each aspect. In particular, teraherz(THz) communications can be used to support mobile ultra-broadband, symbiotic radio and satellite-assisted communications can be used to achieve super IoT, and machine learning techniques are promising candidates for AI. For each technology, we provide the basic principle, key challenges, and state-of-the-art approaches and solutions.

关键词： 6G visions THz communications symbiotic radio satellite-assisted communications artificial intelligence machine learning

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Large System Analysis of Downlink C-RAN with Phase Noise and Fronthaul Compression

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China Communications 2019年第8期16卷 58-71页

作者： Yishi Xue Jun Zhang Shi Jin Gan Zheng Hongbo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China Engineering Research Center of Health Service System Based on Ubiquitous Wireless Networks Ministry of EducationNanjing University of Posts and TelecommunicationsNanjing 210003China National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Wolfson School of Mechanical Electrical and Manufacturing EngineeringLoughborough UniversityLoughboroughLE11 3TUUK

This paper studies the effect of phase noise and fronthaul compression on a downlink cloud radio access network(C-RAN), where several remote radio heads(RRHs) are coordinated to communicate with users by a baseband unit(BBU) on the cloud server. In the system, the baseband signals are precoded at BBU, and then compressed before being transmitted to RRHs through capacity-limited fronthaul links which results in the compressive quantization noise. We assume the regularized zero-forcing precoding is performed with an imperfect channel state information and a compression strategy is applied at BBU. The effect of phase noise arising from nonideal local oscillators both at RRHs and users is considered. We propose an approximate expression for the downlink ergodic sum-rate of considered C-RAN utilizing large dimensional random matrix theory in the large-system regime. From simulation results, the accuracy of the approximate expression is validated, and the effect of phase noise and fronthaul compression can be analyzed theoretically based on the approximate expression.

关键词： cloud radio access network phase noise capacity-limited fronthaul links large dimensional random matrix theory

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The Effect of Solar Cycle on Climate of Northeast Asia

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Journal of Meteorological Research 2019年第5期33卷 885-894页

作者： Yan SONG Zhicai LI Yu GU Kuo-Nan LIOU Xiaoxin ZHANG Ziniu XIAO Training Center China Meteorological AdministrationBeijing 100081China Shanxi Climate Center Taiyuan 030006China University of California Los AngelesCA 90095USA University of California Los Angeles Institute for Technology AdvancementSuzhou Industrial Park(UCLA ITA–SIP)Suzhou 215123China Key Laboratory of Space Weather National Center for Space WeatherChina Meteorological AdministrationBeijing 100081China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China

The impact of solar activity on climate system is spatiotemporally selective and usually more significant on the regional scale. Using statistical methods and solar radio flux(SRF) data, this paper investigates the impact of the solar11-yr cycle on regional climate of Northeast Asia in recent decades. Significant differences in winter temperature,precipitation, and the atmospheric circulation over Northeast Asia are found between peak and valley solar activity years. In peak years, temperature is higher over vast areas of the Eurasian continent in middle and high latitudes, and prone to producing anomalous high pressure there. Northeast Asia is located to the south of the anomalous high pressure, where the easterlies prevail and transport moisture from the western Pacific Ocean to the inland of East Asia and intensify precipitation there. In valley years, temperature is lower over the Eurasian continent and northern Pacific Ocean in middle and high latitudes, and there maintain anomalous low pressure systems in the two regions. Over the Northeast Asian continent, north winds prevail, which transport cold and dry air mass from the high latitude to Northeast Asia and reduce precipitation there. The correlation coefficient of winter precipitation in Northeast China and SRF reaches 0.4, and is statistically significant at the 99% confidence level based on the Student's t-test. The latent heat flux anomalies over the Pacific Ocean caused by solar cycle could explain the spatial pattern of abnormal winter precipitation of China, suggesting that the solar activity may change the climate of Northeast Asia through air–sea interaction.

关键词： solar cycle solar radio flux(SRF) climate anomalies Northeast Asia

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LoSI: Large Scale Location Inference Through FM Signal Integration and Estimation

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Big Data Mining and Analytics 2019年第4期2卷 319-348页

作者： Tathagata Mukherjee Piyush Kumar Debdeep Pati Erik Blasch Eduardo Pasiliao Liqin Xu Department of Computer Science University of Alabama in HuntsvilleHuntsvilleAL 35806USA CompGeom Inc. TallahasseeFL 32311USA Department of Statistics Texas A&M UniversityCollege StationTX 77843USA Air Force Research Laboratory RomeNY 13441USA Air Force Research Laboratory ShalimarFL 32579USA CompGeom Inc. TallahasseeFL 32579USA

In this paper we present a large scale, passive positioning system that can be used for approximate localization in Global Positioning System(GPS) denied/spoofed environments. This system can be used for detecting GPS spoofing as well as for initial position estimation for input to other GPS free positioning and navigation systems like Terrain Contour Matching(TERCOM). Our Location inference through Frequency Modulation(FM)Signal Integration and estimation(LoSI) system is based on broadcast FM radio signals and uses Received Signal Strength Indicator(RSSI) obtained using a Software Defined radio(SDR). The RSSI thus obtained is used for indexing into an estimated model of expected FM spectrum for the entire United States. We show that with the hardware for data acquisition, a single point resolution of around 3 miles and associated algorithms, we are capable of positioning with errors as low as a single pixel(more precisely around 0.12 mile). The algorithm uses a largescale model estimation phase that computes the expected FM spectrum in small rectangular cells(realized using geohashes) across the Contiguous United States(CONUS). We define and use Dominant Channel Descriptor(DCD) features, which can be used for positioning using time varying models. Finally we use an algorithm based on Euclidean nearest neighbors in the DCD feature space for position estimation. The system first runs a DCD feature detector on the observed spectrum and then solves a subset query formulation to find Inference Candidates(IC).Finally, it uses a simple Euclidean nearest neighbor search on the ICs to localize the observation. We report results on 1500 points across Florida using data and model estimates from 2015 and 2017. We also provide a Bayesian decision theoretic justification for the nearest neighbor search.

关键词： Global Positioning System(GPS)-free positioning Frequency Modulation(FM) radio signals of opportunity nearest neighbor search

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Cooperative Relay Based on Exploiting Hybrid ARQ

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China Communications 2019年第9期16卷 187-200页

作者： Mingxuan Li Jie Lin Liang Zhong Mengting Wang Wei Lv China University of Geosciences School of Mechanical Engineering and Electronic Information Department of Electronics and Information EngineeringWuhan 430074China Air Force Early Warning Academy Wuhan 430010China

In order to compensate the primary performance degradation,which is caused by the co-existing secondary communications or the heavy fading of primary link,a cooperative relay scheme is proposed in cognitive radio systems by taking advantage of the opportunities that are arisen by the primary ARQ(Automatic Repeat-reQuest)retransmission.With the help of this scheme,nontrivial relay assistances for the primary retransmission are achieved without initialization phase.The cooperation among secondary users provides additional spatial diversity to facilitate the primary transmission.This can be accomplished with an oblivious primary system and without assuming any non-causal information about the primary data.The scheme are further extended to the scenarios where multiple cognitive pairs exist.Performance analyses of the schemes are devised and the effectiveness is verified via simulations.

关键词： cognitive radio cooperative relay ARQ coexistence outage probability

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A Statistical Study of XBLs,RBLs and FSRQs at 1.5 GHz

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 629-638页

作者： Ji-Liang Zhou Jun-Hui Fan Juan Li Yi Liu Center for Astrophysics Guangzhou University Guangzhou 510006 Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030

BL Lac objects are similar to the fiat spectrum radio quasars in many aspects except regarding the emission lines. In order to study their relationship, we selected 56 BL Lacertae objects （33 X-ray-selected, 23 radio-selected） and 45 flat spectrum radio quasars, analyzed their radio luminosities and core-dominance parameters. We found that the radio luminosities of the radio selected BL Lac objects located in between the X-ray selected BL Lac objects and the flat spectrum radio quasars. However, this intermediate position does not hold for the core-dominance parameter; the RBLs have the largest core-dominance parameters. This suggests that the core-dominance parameter can not be taken as a sequencing criterion. We also investigated the correlation between the luminosity and the core-dominance parameter for the three subclasses. We concluded that, here, the sequence XBL-RBL FSRQ still exists.

关键词： techniques statistical studies -- blazars general -- luminosity radio

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Design and Implementation of a TDD-Based 128-Antenna Massive MIMO Prototype System

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China Communications 2017年第12期14卷 162-187页

作者： Xi Yang Wenjun Lu Ning Wang Karl Nieman Chao-Kai Wen Chuan Zhang Shi Jin Xiaomin Mu Ian Wong Yongming Huang Xiaohu You National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing 210003 China School of Information Engineering Zhengzhou University Zhengzhou 450001 China National Instruments Austin 78759 Texas USA Institute of Communications Engineering National Sun Yat-sen University Kaohsiung 804 Taiwan China

Owing to the dramatic mobile IP growth,the emerging Internet of Things,and cloud-based applications,wireless networking is witnessing a paradigm shift.By fully exploiting spatial degrees of freedom,massive multiple-input-multiple-output(MIMO) systems promise significant gains in data rates and link reliability.Although the research community has recognized the theoretical benefits of these systems,building the hardware of such complex systems is a challenge in practice.This paper presents a time division duplex(TDD)-based 128-antenna massive MIMO prototype system from theory to reality.First,an analytical signal model is provided to facilitate the setup of a feasible massive MIMO prototype system.Second,a link-level simulation consistent with practical TDDbased massive MIMO systems is conducted to guide and validate the massive MIMO system design.We design and implement the TDDbased 128-antenna massive MIMO prototype system with the guidelines obtained from the link-level simulation.Uplink real-time video transmission and downlink data transmission under the configuration of multiple single-antenna users are achieved.Comparisons withstate-of-the-art prototypes demonstrate the advantages of the proposed system in terms of antenna number,bandwidth,latency,and throughput.The proposed system is also equipped with scalability,which makes the system applicable to a wide range of massive scenarios.

关键词： massive MIMO prototyping sys-tem software defined radio TDD

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