With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar backgro...With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar background noise, non-line-of-sight(NLOS) and good secrecy. The strong scattering characteristics in atmospheric render ultraviolet waveband the ideal choice for achieving NLOS optical communication. This paper reviews the research history and status of ultraviolet communication both in China and abroad, and especially introduces three main issues of ultraviolet communication: channel model, system analysis and design, light sources and detectors. For each aspect, current open issues and prospective research directions are analyzed.展开更多
Linear transceiver designs are investigated for distributed two-way relaying networks,which aim at minimising the WeightedMean Square Error(WMSE) of data detections.The forwarding matrices at relays andequalization ma...Linear transceiver designs are investigated for distributed two-way relaying networks,which aim at minimising the WeightedMean Square Error(WMSE) of data detections.The forwarding matrices at relays andequalization matrices at destinations are jointly optimised.To overcome the challenginglimitations introduced by individual powerconstraints,a Semi-Definite Relaxation(SDR)called element-wise relaxation is proposed,which can transform the original optimizationproblem into a standard convex optimizationproblem.In this research,two-way relaying isunderstood from a pure signal processing perspective which can potentially simplify thetheoretical analysis.Finally,simulation resultsare used for assessing the performance advantage of the proposed algorithm.展开更多
The issue of carbon emissions has been on the corporate sustainability agenda for some years. For those working in agricultural supply chains, the challenges remain significant, given the diverse direct and indirect e...The issue of carbon emissions has been on the corporate sustainability agenda for some years. For those working in agricultural supply chains, the challenges remain significant, given the diverse direct and indirect emissions occurring throughout the value chain. This study determines the carbon footprint of the supply chain of Costa Rican coffee exported to Europe, using best practice methodology to calculate greenhouse gas emissions. Overall, it was found that the total carbon footprint across the entire supply chain is 4.82 kg CO2e kgx green coffee. The carbon footprint of the processes in Costa Rica to produce l km of green coffee is 1.77 kg CO2e. The processes within Europe generate 3.05 kg CO2e kg-1 green coffee. This carbon footprint is considered as ＂very high intensity＂. This paper also identifies the sources of the most intense emission and discusses mitigation possibilities on which efforts must be focused.展开更多
The elements that mid-wife news and editorial contents remain： what, who, where, when, why, and how, typical of Lasswell＇s （1948） conceptual model of communication. The operational actualization of this in theory ...The elements that mid-wife news and editorial contents remain： what, who, where, when, why, and how, typical of Lasswell＇s （1948） conceptual model of communication. The operational actualization of this in theory and practice exemplifies a paradigm of news and other editorial contents reporting slant that pays more attention to dramatizing events and incidents, at best exacerbating, psychologically, panic, apprehension, and tension, but hardly focusing on solution to critical situation in society. However, journalism may not always be about the curses; it could be about cures, particularly in regard to climate change/global warming issues in developing economies like Africa＇s. Hence, the thrust of this paper is a strong advocacy for curative journalism that should issue from a well fed body of science-based information on how to adapt to the menace of global warming palaver in developing nations of the world, especially Nigeria. It advances that new media scientific journalism that could benefit society should do more of probing solution rather than concentrate on the throes： the former acting as an anti-depressant journalism instead of a hopeless journalism.展开更多
基金supported by the National High-tech R&D Program of China grant 2015AA043302the Basic research project of Shenzhen grant JCYJ20140417115840236
文摘With rapid advances of solar blind ultraviolet LED and ultraviolet detecting technology in recent years, ultraviolet communication gradually becomes a research hotspot due to its inherent advantages: low solar background noise, non-line-of-sight(NLOS) and good secrecy. The strong scattering characteristics in atmospheric render ultraviolet waveband the ideal choice for achieving NLOS optical communication. This paper reviews the research history and status of ultraviolet communication both in China and abroad, and especially introduces three main issues of ultraviolet communication: channel model, system analysis and design, light sources and detectors. For each aspect, current open issues and prospective research directions are analyzed.
基金supported in part by EricssonNational Science and Technology Major Project under Grant No.2010ZX03003-003-03+2 种基金Sino-Swedish IMT-Advanced and Beyond Cooperative Program under Grant No.2008DFA11780National Natural Science Foundation of China under Grant No.61101130the Excellent Young Scholar Research Funding of Beijing Institute of Technology under Grant No.2013CX04038
文摘Linear transceiver designs are investigated for distributed two-way relaying networks,which aim at minimising the WeightedMean Square Error(WMSE) of data detections.The forwarding matrices at relays andequalization matrices at destinations are jointly optimised.To overcome the challenginglimitations introduced by individual powerconstraints,a Semi-Definite Relaxation(SDR)called element-wise relaxation is proposed,which can transform the original optimizationproblem into a standard convex optimizationproblem.In this research,two-way relaying isunderstood from a pure signal processing perspective which can potentially simplify thetheoretical analysis.Finally,simulation resultsare used for assessing the performance advantage of the proposed algorithm.
文摘The issue of carbon emissions has been on the corporate sustainability agenda for some years. For those working in agricultural supply chains, the challenges remain significant, given the diverse direct and indirect emissions occurring throughout the value chain. This study determines the carbon footprint of the supply chain of Costa Rican coffee exported to Europe, using best practice methodology to calculate greenhouse gas emissions. Overall, it was found that the total carbon footprint across the entire supply chain is 4.82 kg CO2e kgx green coffee. The carbon footprint of the processes in Costa Rica to produce l km of green coffee is 1.77 kg CO2e. The processes within Europe generate 3.05 kg CO2e kg-1 green coffee. This carbon footprint is considered as ＂very high intensity＂. This paper also identifies the sources of the most intense emission and discusses mitigation possibilities on which efforts must be focused.
文摘The elements that mid-wife news and editorial contents remain： what, who, where, when, why, and how, typical of Lasswell＇s （1948） conceptual model of communication. The operational actualization of this in theory and practice exemplifies a paradigm of news and other editorial contents reporting slant that pays more attention to dramatizing events and incidents, at best exacerbating, psychologically, panic, apprehension, and tension, but hardly focusing on solution to critical situation in society. However, journalism may not always be about the curses; it could be about cures, particularly in regard to climate change/global warming issues in developing economies like Africa＇s. Hence, the thrust of this paper is a strong advocacy for curative journalism that should issue from a well fed body of science-based information on how to adapt to the menace of global warming palaver in developing nations of the world, especially Nigeria. It advances that new media scientific journalism that could benefit society should do more of probing solution rather than concentrate on the throes： the former acting as an anti-depressant journalism instead of a hopeless journalism.
