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The spatial correlation and Anisotropy of β-(AlxGa1-x)2O3 Single Crystal

MATERIALS 2023年第12期16卷 4269-4269页

作者： Li, Liuyan Wan, Lingyu Xia, Changtai Sai, Qinglin Talwar, Devki N. Feng, Zhe Chuan Liu, Haoyue Jiang, Jiang Li, Ping Guangxi Univ Ctr Nanoenergy Res Guangxi Coll & Univ Key Lab Blue Energy & Syst Int Carbon Peak & Neutral Sci & Technol Dev InstSch P Nanning 530004 Peoples R China State Key Lab Featured Met Mat & Life Cycle Safety Nanning 530004 Peoples R China Chinese Acad Sci Shanghai Inst Opt & Fine Mech Key Lab Mat High Power Laser Shanghai 201800 Peoples R China Univ North Florida Dept Phys Jacksonville FL 32224 USA Kennesaw State Univ Marietta Southern Polytech Coll Engn & Engn Technol Dept Elect & Comp Engn Marietta GA 30060 USA Hangzhou Inst Opt & Fine Mech Hangzhou 311421 Peoples R China

The long-range crystallographic order and anisotropy in & beta;-(AlxGa1-x)(2)O-3 (x = 0.0, 0.06, 0.11, 0.17, 0.26) crystals, prepared by optical floating zone method with different Al composition, is systematically studied by spatial correlation model and using an angle-resolved polarized Raman spectroscopy. Alloying with aluminum is seen as causing Raman peaks to blue shift while their full widths at half maxima broadened. As x increased, the correlation length (CL) of the Raman modes decreased. By changing x, the CL is more strongly affected for low-frequency phonons than the modes in the high-frequency region. For each Raman mode, the CL is decreased by increasing temperature. The results of angle-resolved polarized Raman spectroscopy have revealed that the intensities of & beta;-(AlxGa1-x)(2)O-3 peaks are highly polarization dependent, with significant effects on the anisotropy with alloying. As the Al composition increased, the anisotropy of Raman tensor elements was enhanced for the two strongest phonon modes in the low-frequency range, while the anisotropy of the sharpest Raman phonon modes in the high-frequency region decreased. Our comprehensive study has provided meaningful results for comprehending the long-range orderliness and anisotropy in technologically important & beta;-(AlxGa1-x)(2)O-3 crystals.

关键词： aluminum gallium oxide Raman scattering spectroscopy spatial correlation model anisotropy of phonon modes

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spatial relationship between ecosystem health and urbanization in coastal mountain city, Qingdao, China

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ECOLOGICAL INFORMATICS 2024年 79卷

作者： Wang, Xingyu Yao, Wenfei Luo, Qingzi Yun, Jiayue Qingdao Univ Technol Coll Architecture & Urban Planning Dept Landscape Architecture Qingdao 266000 Shandong Peoples R China

Rapid urbanization and population growth have significantly impacted air and water quality, exerting adverse effects on both the natural environment and human health. While ecosystem health assessment is a crucial aspect of ecosystem management, the smaller-scale implications of urban development have often been overlooked. This paper addresses this gap by examining the relationship between ecosystem health and urbanization in Qingdao over the period 2000-2019. Utilizing the Vigor-Organization-Resilience-Service (VORS) model, we evaluated ecosystem health (ESH) while measuring the extent of urbanization through population dynamics, economic factors, and land size. Our findings indicate a declining trend in ESH over the studied period, particularly in Chengyang District and Huangdao District. Ecosystem vigor experienced the most significant decline, dropping from 0.730 to 0.639, followed by a decrease in ecosystem resilience from 0.422 to 0.394. Concurrently, the urbanization rate in Qingdao exhibited a steady increase, with high levels observed in Shinan District, Shibei District and Licang District. Our analysis reveals a negative impact of urbanization on ecosystem health, with population growth being the predominant factor from 2000 to 2005. Post-2005, the expansion of construction land emerged as a major contributing factor. Addressing ecological and environmental concerns and the effective management of urban ecosystems all depend on understanding and mitigating the negative impacts of urbanization on ecosystem health. These findings hold crucial implications for government departments tasked with managing the delicate balance between population growth and land expansion.

关键词： Ecosystem health Urbanization VORS spatial correlation model Qingdao city

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spatial change, time tendency and projection to HIV/AIDS incidence in an eastern province of China

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SCIENTIFIC REPORTS 2025年第1期15卷 1-11页

作者： Li, Yiwei Yuan, Shijia Zhao, Yang Yang, Xingguang Li, Hongyu Lv, Yanlin Gao, Wenhui Zhao, Surong Liu, Ronghang Han, Chunlei Binzhou Med Univ Hosp Binzhou 256600 Shandong Peoples R China Shanxi Med Univ Sch Publ Hlth Taiyuan 030607 Shanxi Peoples R China Binzhou Med Univ Sch Hlth Management Yantai 264003 Peoples R China Univ New South Wales George Inst Global Hlth Sydney NSW Australia Natl Univ Singapore Hlth Serv Res Inst Duke NUS Med Sch Hlth Serv & Syst Res Programme Singapore 169857 Singapore Shandong Ctr Dis Control & Prevent Jinan 250013 Shandong Peoples R China Ningxia Med Univ Sch Publ Hlth Yinchuan 750004 Gansu Peoples R China

ObjectivesAs the second most populous province in China, it would have public implications to analyze spatial change, time tendency and prediction analysis of the acquired immunodeficiency syndrome (AIDS) epidemic in Shandong Province. Statistical projection study. spatial autocorrelation model and spatiotemporal scanning analysis were used to describe the spatial and temporal distribution of HIV/AIDS incidence in Shandong Province from 2012 to 2022, and geographical weighted regression model and geographic detector model were used to analyze the influencing factors. The annual incidence rate of AIDS in Shandong Province from 2023 to 2030 was predicted by using the fitted Autoregressive Integrated Moving Average model (ARIMA). From 2012 to 2022, the incidence of AIDS in Shandong Province grows from 1/10 thousand to 2.48/10 thousand. spatial regressions showed that the tertiary sector GDP ratio is the factor with the highest intensity of influence. AIDS incidence shows an overall decreasing trend from east to west across Shandong Province. It is predicted that the AIDS incidence rate in Shandong province will continue to rise from 2023 to 2030, with a projected rate of 6.33/10 thousand in 2030. From 2012 to 2022, the incidence of AIDS in Shandong Province increased and then decreased, and regional differences were revealed as well. It is predicted that the incidence of AIDS in Shandong Province would have an increasing trend from 2023 to 2030.

关键词： AIDS prediction spatial correlation model Spatiotemporal scanning analysis ARIMA model Shandong province China

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Lattice deformation in epitaxial Fe3O4 films on MgO substrates studied by polarized Raman spectroscopy

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Chinese Physics B 2020年第8期29卷 234-238页

作者： Yang Yang Qiang Zhang Wenbo Mi Xixiang Zhang Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China PSE Division King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology School of ScienceTianjin UniversityTianjin 300354China

The lattice structures of epitaxial Fe3O4 films deposited on MgO were studied systematically using polarized Raman spectroscopy as a function of film thickness,where interesting phenomena were ***,the spectral conflict to the Raman selection rules(RSRs)was observed under cross-sectional configuration,which can be attributed to the tetragonal deformation in the growth direction due to the lattice mismatch between Fe3O4 and ***,the blue shift and broadening of Raman peaks evidenced the decrease of the tensile strain in Fe3O4 films with decreasing ***,distinct from the other Raman modes,the lowest T2g mode exhibited asymmetric lineshape,which can be interpreted using the spatial correlation *** increased correlation length introduced in the model can well explain the enhanced peak asymmetry feature with decreasing *** results provide useful information for understanding the lattice structure of epitaxial Fe3O4 film.

关键词： polarized Raman scattering Fe3O4 film tetragonal deformation spatial correlation model

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Offline social interactions and online shopping demand: Does the degree of social interactions matter?

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JOURNAL OF BUSINESS RESEARCH 2019年 99卷 373-381页

作者： Kim, Jeeyeon Kim, Mingyung Choi, Jeonghye Trivedi, Minakshi Yonsei Univ Sch Business Seoul 03722 South Korea Univ Penn Wharton Sch Philadelphia PA 19104 USA Texas Christian Univ Neeley Sch Business Ft Worth TX 76109 USA

Offline social interactions and online shopping each have been studied extensively. Despite the importance of each construct, little is known about the effects of offline social interactions on online shopping. This study examines three research questions: (1) how offline social interactions affect online shopping in general, (2) how active and passive offline social interactions exert different influences on online shopping, and (3) how online shopping preferences moderate the influences from the two types of offline social interactions. Our empirical analyses provide three substantive findings. First, overall offline social interactions have a positive impact on online shopping demand. Second, while active offline social interactions have a positive informational influence on online shopping demand, passive offline social interactions have a negative normative influence on it. Third, online shopping preferences weaken both the positive informational and negative normative influences from both of offline social interactions. We also discuss theoretical and managerial implications.

关键词： Offline social interactions Active offline social interactions Passive offline social interactions Online shopping demand Online shopping preferences spatial correlation model

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Short-term wind power predidion based on spatial model

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RENEWABLE ENERGY 2017年 101卷 1067-1074页

作者： Ye, Lin Zhao, Yongning Zeng, Cheng Zhang, Cihang China Agr Univ Coll Informat & Elect Engn Dept Elect Power Syst POB 210 Beijing 100083 Peoples R China

Large-scale integration of wind energy into power systems may cause operational problems due to the stochastic nature of wind. A short-term wind power prediction model based on physical approach and spatial correlation is proposed to characterize the uncertainty and dependence structure of wind turbines' outputs in the wind farm. Firstly, continuous partial differential equation of each wind turbine has been developed according to its specific spatial location and the layout of its neighboring correlated wind turbines. Then, spatial correlation matrix of wind speed is derived by discretizing differential equation at each wind turbine using a finite volume method (FVM). Wind speed at each turbine is acquired by solving the relevant differential equation under given boundary conditions. Finally, the wind speed is converted to wind power production via a practical power curve model. Prediction results showed that the spatial correlation model can accurately characterize the correlations among outputs of wind turbines and reduce the error of short-term wind power prediction. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Wind farm Power prediction spatial correlation model Wake effect Finite volume method (FVM)

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A New Chessboard Placement and Sizing Method for Capacitors in a Charge-Scaling DAC by Worst-Case Analysis of Nonlinearity

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IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS 2016年第9期35卷 1397-1410页

作者： Burcea, Florin Habal, Husni Graeb, Helmut E. Tech Univ Munich Inst Elect Design Automat D-80333 Munich Germany

Charge scaling data converters include a binary-weighted capacitor array in their structure. New methods for the placement and sizing of capacitor arrays with increased ratio accuracy and improved converter linearity are presented in this paper. A new model of statistical variation is used, which takes into account both spatial correlation between devices and device area. This is combined with a novel analytical model for the linearity metrics of a charge scaling digital-to-analog converter. Minimizing the variance of the linearity metrics directs a new chessboard placement method for the capacitor array. Chessboard placement is shown to be superior to the state of the art in consideration of both random and systematic mismatch. The new analytical model is then used to develop a flow for capacitor array sizing.

关键词： Capacitor matching charge-scaling digital-to-analog converter (DAC) placement optimization spatial correlation model worst-case analysis

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Switching between co-located and distributed transmit diversity

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IET COMMUNICATIONS 2016年第13期10卷 1614-1622页

作者： Amini, Sahar Choi, Kwonhue Yeungnam Univ Dept Informat & Commun Engn Gyungsan Si 712740 South Korea

The authors propose a dual mode transmit diversity (TD) scheme switching between co-located TD (CTD) and distributed TD (DTD) based on the quasi-static channel parameters. The authors first compare CTD and DTD according to spatial correlation coefficient (SCC) of CTD and distributed mean channel gain (MCG) of DTD. By using asymptotic bit error rate (BER) formula, the authors derive a compact and very accurate border equation of DTD-preferred and CTD-preferred regions in MCG ratio and SCC space. Based on the derived border, the authors propose a dual mode TD scheme switching between CTD and DTD according to MCG ratio and SCC. It is shown that the signal-to-noise ratio (SNR) gain contours and the border line for TD switching are irrespective of SNR and modulation scheme. The results show that the proposed dual mode scheme outperforms the single modes not only in the location-specific performance but also in the averaged performance over the cell area. In the averaged BER over the entire cell area, performance improvement of the dual mode scheme over CTD is significant if SCC is roughly larger than 0.6 irrespective of cell shape, spatial correlation model of CTD, path loss exponent and shadowing model.

关键词： diversity reception error statistics telecommunication channels transmitting antennas modulation distributed transmit diversity dual mode transmit diversity quasi-static channel parameters base station asymptotic bit error rate BER formula signal-to-noise ratio SNR gain modulation scheme spatial correlation model path loss exponent shadowing model

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A spatial correlation model for Shadow Fading in Indoor Multipath Propagation

A Spatial Correlation Model for Shadow Fading in Indoor Mult...

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IEEE 72nd Vehicular Technology Conference Fall 2010

作者： Jeon, Nam-Ryul Kim, Kyung-Hoe Choi, Jung-Hwan Kim, Seong-Cheol Seoul Natl Univ Dept Elect Engn Seoul South Korea

ISBN: (纸本)9781424435746

In this paper, shadow fading (SF) in an indoor multipath environment is measured and the spatial correlation of SF is modeled statistically. To effectively extract SF from the measured field strength, we use frequency averaging (FA) method instead of spatial averaging (SA) method which has generally been used. SF is modeled as a random variable with a log-normal distribution. The spatial correlation model for SF is expressed by an exponential decay function with convergence to non-zero value.

关键词： spatial correlation model shadow fading indoor channel measurement

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Simulation for Surveillance Radar Ground Clutter at Low Grazing Angle

Simulation for Surveillance Radar Ground Clutter at Low Graz...

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4th International Conference on Image Analysis and Signal Processing (IASP)

作者： Wang, Xiaojun Wang, Helei Yan, Shusheng Li, Lianhua Meng, Cangzeng Air Force Early Warning Acad Early Warning Simulat & Training Ctr Wuhan Hubei Peoples R China

ISBN: (纸本)9781467325455

In order to simulate the radar ground clutter at a low grazing angle and in middle or even low range resolution conditions, this paper summarizes a description of major electromagnetic mechanisms contributing to ground clutter, and presents detailed principles and simulation processes. First, we generate a radar cross section from a point target model. Then, a map with four types of terrain relief including deserts, farms, hills and towns are designed, through which the distributed ground clutter is obtained by empirical scattering coefficients given under each landcover. Finally, we generate the ground distributed clutter by back scattering coefficients spatial correlation model, in which the clutter amplitude is Rayleigh distribution and the power spectrum density obeys the Gaussian model. The clutter average Doppler shifting parameter in Gaussian distribution can be set and adjusted according to the realistic wind speed affecting the terrain area. Through the procedure of simulation, the experiment results show that in each type terrain of all four kinds of landscapes, the clutter amplitude distribution actually obeys Rayleigh model.

关键词： radar simulation ground clutter low grazing angle spatial correlation model Rayleigh Distribution

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