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Multi-wavelength erbium-doped fiber laser using four-wave mixing effect in doped fiber 被引量:3
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作者 N. S. Shahabuddin Z. Yusoff +1 位作者 H. Ahmad S. W. Harun 《Chinese Optics Letters》 SCIE EI CAS CSCD 2011年第6期80-81,共2页
We demonstrate a multi-wavelength erbium-doped fiber laser (EDFL) using erbium gain and four-wave mixing (FWM) effect in a piece of erbium-doped fiber (EDF) with high erbium ion concentration. The EDF has a pump... We demonstrate a multi-wavelength erbium-doped fiber laser (EDFL) using erbium gain and four-wave mixing (FWM) effect in a piece of erbium-doped fiber (EDF) with high erbium ion concentration. The EDF has a pump absorption rate of 24.6 dB/m at 979 nm and is bi-directionally pumped by 980-nm laser diodes. FWM effect redistributes the energy of different oscillating lines and causes multi-wavelength operation. The laser generates more than 22 lines of optical comb with a line spacing of approximately 0.10 nm at the 1569-nm region using only 1.5-m-long EDF. 展开更多
关键词 EDF FWM Multi-wavelength erbium-doped fiber laser using four-wave mixing effect in doped fiber LENGTH WAVE
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Canonical logic units using bidirectional four-wave mixing in highly nonlinear fiber
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作者 W.C.Dong J.Hou +2 位作者 Y.S.Kadhim S.K.Tawfeeq X.L.Zhang 《Photonics Research》 SCIE EI 2015年第4期164-167,共4页
All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing(FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are s... All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing(FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones. The numerical simulations are made to analyze the relationship between the FWM efficiency and the position of two interactional signals. 展开更多
关键词 FWM line Canonical logic units using bidirectional four-wave mixing in highly nonlinear fiber DPSK wave
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Enhancement of phase conjugation degenerate four-wave mixing using a Bessel beam
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作者 QIAN ZHANG XUEMEI CHENG +4 位作者 HAOWEI CHEN Bo HE ZHAOYU REN YING ZHANG JINTAO BAI 《Photonics Research》 SCIE EI 2018年第3期162-167,共6页
We report on the enhancement of phase conjugation degenerate four-wave mixing(DFWM) in hot atomic Rb vapor by using a Bessel beam as the probe beam. The Bessel beam was generated using cross-phase modulation based on ... We report on the enhancement of phase conjugation degenerate four-wave mixing(DFWM) in hot atomic Rb vapor by using a Bessel beam as the probe beam. The Bessel beam was generated using cross-phase modulation based on the thermal nonlinear optical effect. Our results demonstrated that the DFWM signal generated by the Bessel beam is about twice as large as that generated by the Gaussian beam, which can be attributed to the extended depth and tight focusing features of the Bessel beam. We also found that a DFWM signal with reasonable intensity can be detected even when the Bessel beam encounters an obstruction on its way, thanks to the selfhealing property of the Bessel beam. This work not only indicates that DFWM using a Bessel beam would be of great potential in the fields of high-fidelity communication, adaptive optics, and so on, but also suggests that a Bessel beam would be of significance to enhance the nonlinear process, especially in thick and scattering media. 展开更多
关键词 Enhancement of phase conjugation degenerate four-wave mixing using a Bessel beam
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Monitoring of non-point source pollutants load from a mixed forest land use 被引量:6
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作者 Sung Wan Yoon Se Woong Chung +1 位作者 Dong Geun Oh Jae Woon Lee 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2010年第6期801-805,共5页
The aim of this study was to determine the unit load of NPS (non-point source) pollutants including organic variables such as BOD (biochemical oxygen demand), COD (chemical oxygen demand) and DOC (dissolved org... The aim of this study was to determine the unit load of NPS (non-point source) pollutants including organic variables such as BOD (biochemical oxygen demand), COD (chemical oxygen demand) and DOC (dissolved organic carbon), nitrogen and phosphorus constituents, and suspended solids (SS) and their event mean concentration (EMC) of runoff flows from a water-shed of mixed forest land use by intensive field experiments. Field monitoring for continuous measurements of rainfall, flow, and water quality was conducted over 12 storm events during 2008-2009 using automated and manual sampling methods. The EMCs of individual runoff event were estimated for each water quality constituent based on the flow rate and concentration data of runoff discharge. The average EMCs of BOD, COD, DOC, SS, TN (total nitrogen), NH4^+-N, NO3^--N, TP (total phosphorus), PO4^3-P from the mixed forest land were 1.794, 3.498, 1.462, 10.269, 0.862, 0.044, 0.634, 0.034, and 0.005 mg/L, respectively. The annual unit loads of BOD, COD, DOC, SS, TN, NH4^+-N, NO3^--N, TP and PO4^3--P were estimated as 66.9, 133.2, 55.5, 429.8, 36.5, 1.6, 26.9, 1.3 and 0.1 kg/(ha·yr), respectively. In addition, affecting parameters on the EMCs were investigated by statistic analysis of the field data. As a result, significant correlations with precipitation, rainfall intensity, and total runoff flows were found in most constituents. 展开更多
关键词 event mean concentration mixed forest land use non-point source pollutant load unit load
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A framework for mixed-use decomposition based on temporal activity signatures extracted from big geo-data 被引量:3
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作者 Lun Wu Ximeng Cheng +3 位作者 Chaogui Kang Di Zhu Zhou Huang Yu Liu 《International Journal of Digital Earth》 SCIE 2020年第6期708-726,共19页
Mixed use has been extensively applied as an urban planning principle and hinders the study of single urban functions.To address this problem,it is worth decomposing the mixed use.Inspired by the concept of spectral u... Mixed use has been extensively applied as an urban planning principle and hinders the study of single urban functions.To address this problem,it is worth decomposing the mixed use.Inspired by the concept of spectral unmixing in remote sensing applications,this paper proposes a framework for mixed-use decomposition based on big geo-data.Mixeduse decomposition in terms of human activities differs from traditional land use research,and it is more reasonable to infer the actual urban function of land.The framework consists of four steps,namely temporal activity signature extraction,urban function base curve extraction,mixeduse decomposition,and result validation.First,the temporal activity signatures(TASs)of each zone are extracted as the proxy of human activity patterns.Second,the diurnal TASs of routine activities are extracted as urban function base curves(i.e.endmembers).Third,a linear decomposition model is used to decompose the mixed use and obtain multiple results(urban function composition,dynamic activity proportions,and the mixing index).Finally,result validation strategies are concluded.This framework offers method extensibility and has few requirements for the input data.It is validated by means of a case study of Beijing,based on a social media check-in dataset. 展开更多
关键词 mixed use spatial–temporal pattern urban function human activity big geo-data
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A Comparative Study on the Measurement Methods of Urban Mixed Land Use
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作者 Zhao Guangying Song Jusheng +2 位作者 Liu Shujuan Qian Fang(Translated) Tang Yan(Proofread) 《China City Planning Review》 CSCD 2022年第3期58-71,共14页
The study aims at exploring the applicability and limitations of domestic and foreign methods for measuring the function mixing of urban land use,and sorting out various classic measurement methods according to the lo... The study aims at exploring the applicability and limitations of domestic and foreign methods for measuring the function mixing of urban land use,and sorting out various classic measurement methods according to the logic of “conceptual reflection–characteristics comparison–limitation analysis.” The study shows that:① the connotation and types of mixed land use functions are still controversial at home and abroad;② there is a lack of research on measurement methods in China;③ for medium and micro-scale planning,current measurement methods cannot fully reflect the differences in the degree of mixing caused by the planar and three-dimensional layout of building functions within the grid;④ the measurement methods for refined planning governance should improve the measurement model in terms of the number of functional types and the mixed layout of various functions in the horizontal and vertical directions at the medium and micro-scales,and improve its accuracy of the measurement results of a single grid and the whole area. 展开更多
关键词 urban planning function mixing of land use measurement model LIMITATION improvement
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The building blocks of walkability: Pedestrian activity in Abu Dhabi city center 被引量:1
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作者 Mohamad Kashef 《Frontiers of Architectural Research》 CSCD 2022年第2期203-223,共21页
This study develops an empirical approach that underlines the effect of land use mix and development grain on pedestrian movement in the streets and public spaces of urban neighborhoods.The study begins with the end i... This study develops an empirical approach that underlines the effect of land use mix and development grain on pedestrian movement in the streets and public spaces of urban neighborhoods.The study begins with the end in mind;it compares two urban sectors in Abu Dhabi city with broadly recognized contrasting levels of pedestrian movement.The research works backward to identify the combination of built environment attributes that result in differing levels of pedestrian activity between the eastern and western sectors of Abu Dhabi city center.Using Geographic Information Systems maps/data files,direct observations,and field metrics,the study computes various indices related to land use mix,density,and street connectivity for Abu Dhabi central business district.The findings of this study highlight the land use,spatial and street network configurations that enhance pedestrian activity in urban centers.From a local perspective,the research outcome would inform future visions aimed at transforming the city of Abu Dhabi into a global metropolis that provides its citizens and visitors with unique and vibrant urban settings conducive to intra-and inter-neighborhood walkability. 展开更多
关键词 Land use mix Neighborhood design Pedestrian activity Street network Urban vitality
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Urban Land Use Classifcation Linked to Planning Management
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作者 QI Dongjin ZHOU Jianyun SHI Ke 《China City Planning Review》 2012年第4期8-15,共8页
By analyzing the applicability of the new Code for Classification of Urban Land Use and Planning Standards of Development Land from the angle of planning management,this paper points out the conflicts between the plan... By analyzing the applicability of the new Code for Classification of Urban Land Use and Planning Standards of Development Land from the angle of planning management,this paper points out the conflicts between the planning and land use management institutions.Referring to the experience of land use control in the US and the UK through zoning and case law respectively,this paper puts forward that the urban land use classification should take into consideration the characteristics of the actual urban planning system and the possibility of mixed land use due to the uncertainty of urban development,and be linked to the institutions of planning and land supply management. 展开更多
关键词 land use classification planning management mixed land use
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