Downburst event is identified as a major cause to failure of transmission lines in non-coastal regions.In this paper,a novel nonlinear analytical frame for quasi-static buffeting responses of hinged and multi-span ins...Downburst event is identified as a major cause to failure of transmission lines in non-coastal regions.In this paper,a novel nonlinear analytical frame for quasi-static buffeting responses of hinged and multi-span insulator-line systems are derived based on the theory of cable structure.The closed-form solutions are presented and applied to predict nonlinear response including displacements and other reactions of the system subjected to a moving downburst wind in a case study.Accuracy and efficiency of the derived analytical frame are validated via comparisons with results from finite element method.展开更多
Optical wireless communication(OWC)using the ultra-broad spectrum of the visible-to-ultraviolet(UV)wavelength region remains a vital field of research for mitigating the saturated bandwidth of radio-frequency(RF)commu...Optical wireless communication(OWC)using the ultra-broad spectrum of the visible-to-ultraviolet(UV)wavelength region remains a vital field of research for mitigating the saturated bandwidth of radio-frequency(RF)communication.However,the lack of an efficient UV photodetection methodology hinders the development of UV-based communication.The key technological impediment is related to the low UV-photon absorption in existing silicon photodetectors,which offer low-cost and mature platforms.To address this technology gap,we report a hybrid Sibased photodetection scheme by incorporating CsPbBr_(3) perovskite nanocrystals(NCs)with a high photoluminescence quantum yield(PLQY)and a fast photoluminescence(PL)decay time as a UV-to-visible colourconverting layer for high-speed solar-blind UV communication.The facile formation of drop-cast CsPbBr_(3) perovskite NCs leads to a high PLQY of up to ~73% and strong absorption in the UV region.With the addition of the NC layer,a nearly threefold improvement in the responsivity and an increase of ~25% in the external quantum efficiency(EQE)of the solar-blind region compared to a commercial silicon-based photodetector were observed.Moreover,timeresolved photoluminescence measurements demonstrated a decay time of 4.5 ns under a 372-nm UV excitation source,thus elucidating the potential of this layer as a fast colour-converting layer.A high data rate of up to 34 Mbps in solar-blind communication was achieved using the hybrid CsPbBr_(3)-silicon photodetection scheme in conjunction with a 278-nm UVC light-emitting diode(LED).These findings demonstrate the feasibility of an integrated high-speed photoreceiver design of a composition-tuneable perovskite-based phosphor and a low-cost silicon-based photodetector for UV communication.展开更多
Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significant...Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV microlight-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately 1369 μm^(2)(equivalent to circular device pixels of diameter;0 μm). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.展开更多
Conventional line-of-sight underwater wireless optical communication(UWOC)links suffer from huge signal fading in the presence of oceanic turbulence due to misalignment,which is caused by variations in the refractive ...Conventional line-of-sight underwater wireless optical communication(UWOC)links suffer from huge signal fading in the presence of oceanic turbulence due to misalignment,which is caused by variations in the refractive index in the water.Non-line-of-sight(NLOS)communication,a novel underwater communication configuration,which has eased the requirements on the alignment,is supposed to enhance the robustness of the UWOC links in the presence of such turbulence.This Letter experimentally and statistically studies the impact of turbulence that arises from temperature gradient variations and the presence of different air bubble populations on NLOS optical channels.The results suggest that temperature gradient-induced turbulence causes negligible signal fading to the NLOS link.Furthermore,the presence of air bubbles with different populations and sizes can enhance the received signal power by seizing the scattering phenomena from an ultraviolet 377 nm laser diode.展开更多
The sub-cellular events that occur during the ethylene-modulated cell elongation were characterized by examining the ultra-structure of etiolated Arabidopsis seedling hypocotyl cells. Preventing the basal level ethyle...The sub-cellular events that occur during the ethylene-modulated cell elongation were characterized by examining the ultra-structure of etiolated Arabidopsis seedling hypocotyl cells. Preventing the basal level ethylene response facilitated cell elongation, and the cells exhibited wall loosening and separation phenotype. Nearby the wall separation sites were frequently associated with an increase in the cortical rough endoplasmic reticulum （rER） membranes, the presence of paramural bodies, and the circular Golgi formation. The cortical rER proliferation and circular Golgi phenotype were reverted by the protein biosynthesis inhibitor cycloheximide. The cortical rER membranes were longer when the ethylene response was prevented and shortened with elevated ethylene responses. Proteomic changes between wild type and the ethylene-insensitive mutant ethylene insensitive2 （ein2） seedling hypocotyls indicated that distinct subsets of proteins involving endomembrane trafficking, remodeling, and wall modifications were differentially expressed. FM4-64 staining supported the proteomic changes, which indicated reduced endocytosis activity with alleviation of the ethylene response. The basal level ethylene response has an important role in endomembrane trafficking, biological materials transport and maintenance of the endomembrane organization. It is possible that endomembrane alterations may partly associate with the wall modifications, though the biological significance of the alterations should be addressed in future studies.展开更多
This tutorial focuses on devices and technologies that are part of laser-based visible light communication(VLC)systems. Laser-based VLC systems have advantages over their light-emitting-diode-based counterparts, inclu...This tutorial focuses on devices and technologies that are part of laser-based visible light communication(VLC)systems. Laser-based VLC systems have advantages over their light-emitting-diode-based counterparts, including having high transmission speed and long transmission distance. We summarize terminologies related to laser-based solid-state lighting and VLC, and further review the advances in device design and performance.The high-speed modulation characteristics of laser diodes and superluminescent diodes and the on-chip integration of optoelectronic components in the visible color regime, such as the high-speed integrated photodetector,are introduced. The modulation technology for laser-based white light communication systems and the challenges for future development are then discussed.展开更多
基金supported in part by Science and Technology Foundation of State Grid Shandong Electric Power Company(Grant No.52062518000U)National Natural Science Foundation of China(Grant Nos.51720105005 and 51478373)+1 种基金by Science and Technology Foundation of State Grid Shandong Electric Power Company(Grant No.52062518000U)National Natural Science Foundation of China(Grant Nos.51720105005 and 51478373)are greatly acknowledged.
文摘Downburst event is identified as a major cause to failure of transmission lines in non-coastal regions.In this paper,a novel nonlinear analytical frame for quasi-static buffeting responses of hinged and multi-span insulator-line systems are derived based on the theory of cable structure.The closed-form solutions are presented and applied to predict nonlinear response including displacements and other reactions of the system subjected to a moving downburst wind in a case study.Accuracy and efficiency of the derived analytical frame are validated via comparisons with results from finite element method.
基金supported by funding from King Abdullah University of Science and Technology(KAUST),BAS/1/1614-01-01,KCR/1/2081-01-01 and GEN/1/6607-01-01,and the KAUST-KFUPM Special Initiative,REP/1/2878-01-01the financial support from the King Abdulaziz City for Science and Technology(KACST),Grant no.KACST TIC R2-FP-008.
文摘Optical wireless communication(OWC)using the ultra-broad spectrum of the visible-to-ultraviolet(UV)wavelength region remains a vital field of research for mitigating the saturated bandwidth of radio-frequency(RF)communication.However,the lack of an efficient UV photodetection methodology hinders the development of UV-based communication.The key technological impediment is related to the low UV-photon absorption in existing silicon photodetectors,which offer low-cost and mature platforms.To address this technology gap,we report a hybrid Sibased photodetection scheme by incorporating CsPbBr_(3) perovskite nanocrystals(NCs)with a high photoluminescence quantum yield(PLQY)and a fast photoluminescence(PL)decay time as a UV-to-visible colourconverting layer for high-speed solar-blind UV communication.The facile formation of drop-cast CsPbBr_(3) perovskite NCs leads to a high PLQY of up to ~73% and strong absorption in the UV region.With the addition of the NC layer,a nearly threefold improvement in the responsivity and an increase of ~25% in the external quantum efficiency(EQE)of the solar-blind region compared to a commercial silicon-based photodetector were observed.Moreover,timeresolved photoluminescence measurements demonstrated a decay time of 4.5 ns under a 372-nm UV excitation source,thus elucidating the potential of this layer as a fast colour-converting layer.A high data rate of up to 34 Mbps in solar-blind communication was achieved using the hybrid CsPbBr_(3)-silicon photodetection scheme in conjunction with a 278-nm UVC light-emitting diode(LED).These findings demonstrate the feasibility of an integrated high-speed photoreceiver design of a composition-tuneable perovskite-based phosphor and a low-cost silicon-based photodetector for UV communication.
基金Engineering and Physical Sciences Research Council (EP/M01326X/1, EP/S001751/1, EP/T00097X/1)。
文摘Deep ultraviolet(DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV microlight-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately 1369 μm^(2)(equivalent to circular device pixels of diameter;0 μm). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.
基金supported by the King Abdullah University of Science and Technology(KAUST)(baseline funding,BAS/1/1614-01-01,KAUST funding KCR/1/2081-01-01,and GEN/1/6607-01-01)T.K.N.and B.S.O.gratefully acknowledge funding from King Abdulaziz City for Science and Technology(KACST)Grant KACST TIC R2-FP-008
文摘Conventional line-of-sight underwater wireless optical communication(UWOC)links suffer from huge signal fading in the presence of oceanic turbulence due to misalignment,which is caused by variations in the refractive index in the water.Non-line-of-sight(NLOS)communication,a novel underwater communication configuration,which has eased the requirements on the alignment,is supposed to enhance the robustness of the UWOC links in the presence of such turbulence.This Letter experimentally and statistically studies the impact of turbulence that arises from temperature gradient variations and the presence of different air bubble populations on NLOS optical channels.The results suggest that temperature gradient-induced turbulence causes negligible signal fading to the NLOS link.Furthermore,the presence of air bubbles with different populations and sizes can enhance the received signal power by seizing the scattering phenomena from an ultraviolet 377 nm laser diode.
基金supported by the National Natural Sciences Foundation of China (31070249, 31100212, and 31123006)the Chinese Ministry of Science and Technology (2011CB100700 and 2012AA10A302-2)the Chinese Academy of Sciences (KSCX2-EW-J-12)
文摘The sub-cellular events that occur during the ethylene-modulated cell elongation were characterized by examining the ultra-structure of etiolated Arabidopsis seedling hypocotyl cells. Preventing the basal level ethylene response facilitated cell elongation, and the cells exhibited wall loosening and separation phenotype. Nearby the wall separation sites were frequently associated with an increase in the cortical rough endoplasmic reticulum （rER） membranes, the presence of paramural bodies, and the circular Golgi formation. The cortical rER proliferation and circular Golgi phenotype were reverted by the protein biosynthesis inhibitor cycloheximide. The cortical rER membranes were longer when the ethylene response was prevented and shortened with elevated ethylene responses. Proteomic changes between wild type and the ethylene-insensitive mutant ethylene insensitive2 （ein2） seedling hypocotyls indicated that distinct subsets of proteins involving endomembrane trafficking, remodeling, and wall modifications were differentially expressed. FM4-64 staining supported the proteomic changes, which indicated reduced endocytosis activity with alleviation of the ethylene response. The basal level ethylene response has an important role in endomembrane trafficking, biological materials transport and maintenance of the endomembrane organization. It is possible that endomembrane alterations may partly associate with the wall modifications, though the biological significance of the alterations should be addressed in future studies.
文摘This tutorial focuses on devices and technologies that are part of laser-based visible light communication(VLC)systems. Laser-based VLC systems have advantages over their light-emitting-diode-based counterparts, including having high transmission speed and long transmission distance. We summarize terminologies related to laser-based solid-state lighting and VLC, and further review the advances in device design and performance.The high-speed modulation characteristics of laser diodes and superluminescent diodes and the on-chip integration of optoelectronic components in the visible color regime, such as the high-speed integrated photodetector,are introduced. The modulation technology for laser-based white light communication systems and the challenges for future development are then discussed.
