A general formula for the dispersion limit of single-mode-fiber IM/DD (Intensity Modulation /Direct Detection) systems is derived for arbitrary given normalized pulse width P, eye opening penalty X and source linewidt...A general formula for the dispersion limit of single-mode-fiber IM/DD (Intensity Modulation /Direct Detection) systems is derived for arbitrary given normalized pulse width P, eye opening penalty X and source linewidth enchancement factor α. From the comparison with published theoretical results, computer simulation and experimental data, its validity and convenience in system design and evaluation are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems.展开更多
Direct methanol fuel cells(DMFCs)are considered favorable for portable devices due to their high energy density and the widespread availability of methanol fuel.However,the commercialization of DMFCs has been severely...Direct methanol fuel cells(DMFCs)are considered favorable for portable devices due to their high energy density and the widespread availability of methanol fuel.However,the commercialization of DMFCs has been severely limited by the sluggish reaction kinetics and poor stability of the anode.In this study,compressively strained PtRu alloy nanoparticles were deposited on a nanoporous thin film(NPTF)using a differential normal pulse voltammetry technique.The resulting compressive structure is confirmed through geometrical phase analysis,revealing high-level compressive strains of about−5%.Owing to the improved specific activity and high specific surface area,the compressively strained PtRu alloy nanoparticles exhibit outstanding Pt mass activities for methanol oxidation reaction.NPTF-Pt2Ru1 with a Pt/Ru molar ratio of 2/1 exhibits the highest Pt mass activity(1.64 A mg_(Pt)^(-1)),approximately 4 times higher than that of commercial PtRu/C.When applied in membrane electrode assembly,this film anode in DMFCs further exhibits mass activity enhancement owing to the structural advantages such as weakened methanol cross-over.With a loading of 0.21 mg_(Pt)cm^(-2),the maximum power density at 80℃reaches 117 mW cm^(-2),and the power efficiency of Pt is about 12 times higher than that of commercial PtRu/C(2 mg_(Pt)cm^(-2),92 mW cm^(-2)).Therefore,the methodology outlined in this study demonstrates a novel and effective means of synthesizing high-performance anode catalysts for DMFCs.展开更多
基金the High Technology Research and Development Programme of China
文摘A general formula for the dispersion limit of single-mode-fiber IM/DD (Intensity Modulation /Direct Detection) systems is derived for arbitrary given normalized pulse width P, eye opening penalty X and source linewidth enchancement factor α. From the comparison with published theoretical results, computer simulation and experimental data, its validity and convenience in system design and evaluation are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems.
基金financially supported by the National Natural Science Foundation of China(No.U2102214)。
文摘Direct methanol fuel cells(DMFCs)are considered favorable for portable devices due to their high energy density and the widespread availability of methanol fuel.However,the commercialization of DMFCs has been severely limited by the sluggish reaction kinetics and poor stability of the anode.In this study,compressively strained PtRu alloy nanoparticles were deposited on a nanoporous thin film(NPTF)using a differential normal pulse voltammetry technique.The resulting compressive structure is confirmed through geometrical phase analysis,revealing high-level compressive strains of about−5%.Owing to the improved specific activity and high specific surface area,the compressively strained PtRu alloy nanoparticles exhibit outstanding Pt mass activities for methanol oxidation reaction.NPTF-Pt2Ru1 with a Pt/Ru molar ratio of 2/1 exhibits the highest Pt mass activity(1.64 A mg_(Pt)^(-1)),approximately 4 times higher than that of commercial PtRu/C.When applied in membrane electrode assembly,this film anode in DMFCs further exhibits mass activity enhancement owing to the structural advantages such as weakened methanol cross-over.With a loading of 0.21 mg_(Pt)cm^(-2),the maximum power density at 80℃reaches 117 mW cm^(-2),and the power efficiency of Pt is about 12 times higher than that of commercial PtRu/C(2 mg_(Pt)cm^(-2),92 mW cm^(-2)).Therefore,the methodology outlined in this study demonstrates a novel and effective means of synthesizing high-performance anode catalysts for DMFCs.
