To investigate the potential of utilizing visible spectral imaging for controlling the plasma boundary shape during stable operation of plasma in future tokamak, a D_α band symmetric visible light diagnostic system w...To investigate the potential of utilizing visible spectral imaging for controlling the plasma boundary shape during stable operation of plasma in future tokamak, a D_α band symmetric visible light diagnostic system was designed and implemented on the Experimental Advanced Superconducting Tokamak(EAST). This system leverages two symmetric optics for joint plasma imaging. The optical system exhibits a spatial resolution less than 2 mm at the poloidal cross-section, distortion within the field of view below 10%, and relative illumination of 91%.The high-quality images obtained enable clear observation of both the plasma boundary position and the characteristics of components within the vacuum vessel. Following system calibration and coordinate transformation, the image coordinate boundary features are mapped to the tokamak coordinate system. Utilizing this system, the plasma boundary was reconstructed, and the resulting representation showed alignment with the EFIT(Equilibrium Fitting) results. This underscores the system's superior performance in boundary reconstruction applications and provides a diagnostic foundation for boundary shape control based on visible spectral imaging.展开更多
Real-time,contact-free temperature monitoring of low to medium range(30℃-150℃)has been extensively used in industry and agriculture,which is usually realized by costly infrared temperature detection methods.This pap...Real-time,contact-free temperature monitoring of low to medium range(30℃-150℃)has been extensively used in industry and agriculture,which is usually realized by costly infrared temperature detection methods.This paper proposes an alternative approach of extracting temperature information in real time from the visible light images of the monitoring target using a convolutional neural network(CNN).A mean-square error of<1.119℃was reached in the temperature measurements of low to medium range using the CNN and the visible light images.Imaging angle and imaging distance do not affect the temperature detection using visible optical images by the CNN.Moreover,the CNN has a certain illuminance generalization ability capable of detection temperature information from the images which were collected under different illuminance and were not used for training.Compared to the conventional machine learning algorithms mentioned in the recent literatures,this real-time,contact-free temperature measurement approach that does not require any further image processing operations facilitates temperature monitoring applications in the industrial and civil fields.展开更多
While considerable research has been conducted on the structural principles,fabrication techniques,and photoelectric properties of high-voltage light-emitting diodes(LEDs),their performance in light communication rema...While considerable research has been conducted on the structural principles,fabrication techniques,and photoelectric properties of high-voltage light-emitting diodes(LEDs),their performance in light communication remains underexplored.A high-voltage seriesconnected LED or photodetector(HVS-LED/PD)based on the gallium nitride(GaN)integrated photoelectronic chip is presented in this paper.Multi-quantum wells(MQW)diodes with identical structures are integrated onto a single chip through wafer-scale micro-fabrication techniques and connected in series to construct the HVS-LED/PD.The advantages of the HVS-LED/PD in communication are explored by testing its performance as both a light transmitter and a PD.The series connection enhances the device's 3 dB bandwidth,allowing it to increase from 1.56 MHz to a minimum of 2.16 MHz when functioning as an LED,and from 47.42 kHz to at least 85.83 kHz when operating as a PD.The results demonstrate that the light communication performance of HVS-LED/PD is better than that of a single GaN MQW diode with bandwidth and transmission quantity,which enriches the research of GaN-based high-voltage devices.展开更多
From 14 to 17 January,2025 already 2,900 exhibitors from 60 countries will present current trends,the latest collections,innovative materials and textile solutions at Heimtextil.High-calibre highlights await visitors:...From 14 to 17 January,2025 already 2,900 exhibitors from 60 countries will present current trends,the latest collections,innovative materials and textile solutions at Heimtextil.High-calibre highlights await visitors:For the first time,the Milanbased design platform Alcova will curate the Heimtextil Trends 25/26.In addition,the worldwide renowned designer and architect Patricia Urquiola brings textile design to life in the exclusive installation‘among-us’.展开更多
Visible light(VL)plays an important role in achieving high-precision positioning and low bit error radio(BER)data communication.However,most VL-based systems can not achieve positioning and communication,simultaneousl...Visible light(VL)plays an important role in achieving high-precision positioning and low bit error radio(BER)data communication.However,most VL-based systems can not achieve positioning and communication,simultaneously.There are two problems:1)the hybrid systems are difficult to extract distinguishable positioning beacon features without affecting communication performance,2)in the hybrid systems,the lost data bits in the inter-frame gap(IFG)are hard to recover,which affects positioning and communication performance.Therefore,in this article,we propose a novel VL-based hybrid positioning and communication system,named HY-PC system,to solve the above problems.First,we propose the robust T-W mapping for recognizing specific Light Emitting Diodes(LEDs),which can provide stable LED recognition accuracy without adding extra beacon data and does not decrease the communication rate.Furthermore,we also propose the novel linear block coding and bit interleaving mechanism,which can recover the lost data bits in the IFG and improve data communication performance.Finally,we use commercial off-the-shelf devices to implement our HY-PC system,extensive experimental results show that our HY-PC system can achieve consistent high-precision positioning and low-BER data communication,simultaneously.展开更多
Two-dimensional （2-D） BiVO4 nanosheets-graphene （GR） composites with different weight addition ratios of GR have been prepared via a facile wet chemistry process. X-ray diffraction （XRD）, Raman spectra, X-ray ph...Two-dimensional （2-D） BiVO4 nanosheets-graphene （GR） composites with different weight addition ratios of GR have been prepared via a facile wet chemistry process. X-ray diffraction （XRD）, Raman spectra, X-ray photoelectron spectra （XPS）, UV-vis diffuse reflectance spectra （DRS）, field-emission scanning electron microscopy （FE-SEM）, transmission electron microscopy （TEM）, nitrogen adsorption-desorption, transient photocurrent response and photoluminescence （PL） spectra were employed to determine the properties of the samples. It is found that BiVO4 nanosheets could pave well on the surface of graphene sheets. BiVO4 nanosheets-GR composites with a proper addition amount of GR exhibited higher photocatalytic activity than bare BiVO4 nanosheets toward liquid-phase degradation of rhodamine B （RhB） and methyl orange （MO） under visible light irradiation. The enhancement of photocatalytic activities of BiVO4 nanosheets-GR composites can be attributed to the effective separation of photoexcited electron-hole pairs. This work not only provides a simple strategy for fabricating specific 2-D semiconductor-2-D GR composites, but also opens a new window of such 2-D semiconductor-2-D GR composites as visible light photocatalysts toward an improved visible light photoactivity in purifying polluted water resources.展开更多
The key techniques in indoor positioning based on visible light communication and the state of the art of this research were surveyed. First, the significance of indoor positioning based on visible light communication...The key techniques in indoor positioning based on visible light communication and the state of the art of this research were surveyed. First, the significance of indoor positioning based on visible light communication from two aspects of the limitations of current indoor positioning technology and the advantages of visible light communication was discussed; And then, the main four technology of indoor positioning based on visible light communication were summarized and the triangulation of RSS method and the principle of image positioning were introduced in detail; Next, the performance characteristics of various typical algorithms were compared and analyzed; In the end, several suggestions on future research of indoor positioning based on visible light communication were given.展开更多
In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of un...In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of underlying physical propagation phenomenon should be carried out to realize VLC system in underground mines. To design VLC system and evaluate its performance, accurate and efficient channel models, including large-scale fading and scattering characteristics, are needed to be established. However,the characteristics of the underlying VLC channels about fading and scattering have not been sufficiently investigated yet. In this paper, a path loss channel model, based on the recursive model, is proposed precisely. Its path loss exponent is determined by three different trajectories, which is studied in the mining roadway and working face environment. Besides, the shadowing effect for VLC has been modelled by a Bimodal Gaussian distribution in underground mines. Considering the number of transmitters in line-of-sight(Lo S) as well as non-line-of-sight(NLo S) scenarios,our simulation illustrates the fact that, as the curve fitting technique is employed, the path loss displays a linear behavior in log-domain.The path loss expression is derived, it is related to the distance. Finally, root mean square(RMS) delay spread and Mie scattering in underground mines are analyzed.展开更多
NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, trans...NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, UV–visible（UV–vis） diffuse reflectance spectroscopy, and photoluminescence（PL） spectroscopy. The XRD patterns of the H-and S-samples showed peaks indexed to the pure phase of perovskite NaTaOand minor peaks assignable to TaNat various synthesis temperatures. Substitution of oxygen by nitrogen ions causes the light absorption of the H-and S-NaTaONsamples to be extended to the 600–650 nm region, thus making the samples visible-light active. The NaTaONsamples exhibited photocatalytic activity for Hand Oevolution from aqueous methanol and silver nitrate solutions under visible-light irradiation. The UV–vis and PL spectra of the Hand S-catalysts revealed the presence of cationic vacancies and reduced metallic species, which acted as recombination centers. These results demonstrated that the preparation method plays a critical role in the formation of defect states, thereby governing the photocatalytic activity of the NaTaONcatalysts.展开更多
Photocatalysis is considered as an ideal strategy for water pollution treatment.However,it remains challenging to design a highly efficient photo-catalytic system through regulating the charge flow via a precise appro...Photocatalysis is considered as an ideal strategy for water pollution treatment.However,it remains challenging to design a highly efficient photo-catalytic system through regulating the charge flow via a precise approach.In this work,a novel NH2-MIL-125(Ti)/Bi2WO6 composite was constructed via self-assembly growing Bi2WO6 nanosheets on NH2-MIL-125(Ti)material.The characterization results demonstrated that NH2-MIL-125(Ti)was successfully incorporated into Bi2WO6 and the photoexcited carriers could be efficiently separated and transferred between the two components.NH2-MIL-125(Ti)/Bi2WO6 composites displayed enhanced photocatalytic activity for the removal of rhodamine B(RhB)and tetracycline(TC)under visible light irradiation,and the optimal weight ratio of NH2-MIL-125(Ti)was determined to be 7 wt%.The introduction of NH2-MIL-125(Ti)into Bi2WO6 could raise the absorption of visible light,accelerate the separation and transfer of charge carriers,and boost photocatalytic activity.This research presents a wide range of possibilities for the further development of novel composites in the field of environment purification.展开更多
Photocatalytic reduction of CO2 with H2 O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry.Nevertheless,the precise control of CO/H2 ratio...Photocatalytic reduction of CO2 with H2 O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry.Nevertheless,the precise control of CO/H2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further application.Herein,we prepared a series of highly efficient heterostructure based on highly dispersed palladium supported on ultrathin Co Al-layered double hydroxide(LDH).In conjunction with a Ru-complex sensitizer,the molar ratios of CO/H2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation(λ>400 nm).More interestingly,the syngas can be obtained under light irradiation atλ>600 nm.Structure characterization and density functional theory calculations revealed that the remarkable catalytic activity can be due to the supported palladium,which improved the charge transfer efficiency.Meanwhile,more H atoms were used to generate H2 on the supported palladium for further tunable CO/H2 ratio.This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock.展开更多
Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically...Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.展开更多
Visible light communication(VLC)and non-orthogonal multiple access(NOMA)have been deemed two promising techniques in the next wireless communication networks.In this paper,secure communications in the presence of pote...Visible light communication(VLC)and non-orthogonal multiple access(NOMA)have been deemed two promising techniques in the next wireless communication networks.In this paper,secure communications in the presence of potential eavesdropper are investigated for a multiple-input single-output VLC system with NOMA.The artificial noise jamming and beamforming technologies are applied to improve secure performance.A robust resource allocation scheme is proposed to minimize the total transmit power taking into account the constraints on the quality of service requirement of the desired users and the maximum tolerable data rate of the eavesdropper,and the practical imperfect channel state information of both the desired users and the eavesdropper.The formulated non-convex optimization problem is tackled based onS-Procedure and semi-definite programming relaxation.Simulation results illustrate that our proposed resource allocation scheme can effectively guarantee communication security and achieve transmit power saving.Moreover,the height and number of LED can significantly affect system performance and the optimum LED height can be obtained for different LED numbers.展开更多
Ag–AgX(X = Cl, Br)@TiO_2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol–gel technique with post-photoreduction. The photocatalytic activ...Ag–AgX(X = Cl, Br)@TiO_2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol–gel technique with post-photoreduction. The photocatalytic activities of both Ag–Ag Cl@TiO_2 and Ag–Ag Br@TiO_2 under visible light are effectively improved by ~3 times relative to TiO_2 NPAS under the simulated sunlight for the decomposition of methyl orange(MO). Ag–AgBr@TiO_2 showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO_2. The role of Ag and Ag X nanoparticles on the surface of Ag–Ag X(X = Cl,Br)@TiO_2 was discussed. Ag on these samples not onlycan efficiently harvest visible light especially for Ag Cl, but also efficiently separate excited electrons and holes via the fast electron transfer from Ag X(X = Cl, Br) to metal Ag nanoparticles and then to TiO_2-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.展开更多
Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical s...Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical support for designing VLC-NOMA,we derive its analytic expressions for the symbol error rate(SER).Specifically,NOMA is first incorporated with appropriate VLC to establish a VLC-NOMA framework.Afterwards,mathematical expressions of the SER for the VLC-NOMA are developed.Moreover,numerical results are provided carefully to demonstrate that the proposed VLC-NOMA scheme outperforms than state-of-the-art orthogonal frequency division multiple access(OFDMA) one in terms of SER performance.Finally,relationships between the SER performance and the number of users,power allocation coefficient and semi-angle are well investigated,which can give us a scientific guide to devise the VLC-NOMA system for achieving better SER performance.展开更多
In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal proce...In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.展开更多
A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type sem...A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.展开更多
Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope ...Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope efficiencies of 34.7%,27.3%,and 12.3%were achieved with good beam qualities(M^(2)<1.6)at 670.4 nm,674.2 nm,and 678.9 nm,respectively.Record-high output power(2.6 W)and record-high slope efficiency(34.7%)were achieved for the Pr^(3+):YLF laser operation at 670.4 nm.This is also the first demonstration of longer-wavelength peaks beyond 670 nm in the^(3)P_(1)→^(3)F_(3)transition of Pr^(3+):YLF.In multi-wavelength laser operations,the dual-wavelength lasings,including 670.1/674.8 nm,670.1/679.1 nm,and 675.0/679.4 nm,were obtained by fine adjustment of one/two etalons within the cavity.Furthermore,the triple-wavelength lasings,e.g.672.2/674.2/678.6 nm and 670.4/674.8/679.4 nm,were successfully demonstrated.Moreover,both the first-order vortex lasers(LG_(0)^(+1)and LG_(0)^(-1)modes)at 670.4 nm were obtained by off-axis pumping.展开更多
Bismuth containing nanomaterials recently received increasing attention with respect to environmental applications because of their low cost, high stability and nontoxicity. In this work, Bi–Bi_2O_2CO_3 heterojunctio...Bismuth containing nanomaterials recently received increasing attention with respect to environmental applications because of their low cost, high stability and nontoxicity. In this work, Bi–Bi_2O_2CO_3 heterojunctions were fabricated by in-situ decoration of Bi nanoparticles on Bi_2O_2CO_3 nanosheets via a simple hydrothermal synthesis approach. X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and high-resolution TEM(HRTEM) were used to confirm the morphology of the nanosheet-like heterostructure of the Bi–Bi_2O_2CO_3 composite. Detailed ultrafast electronic spectroscopy reveals that the in-situ decoration of Bi nanoparticles on Bi_2O_2CO_3 nanosheets exhibit a dramatically enhanced electron-hole pair separation rate, which results in an extraordinarily high photocatalytic activity for the degradation of a model organic dye, methylene blue(MB) under visible light illumination. Cycling experiments revealed a good photochemical stability of the Bi–Bi_2O_2CO_3 heterojunction under repeated irradiation. Photocurrent measurements further indicated that the heterojunction incredibly enhanced the charge generation and suppressed the charge recombination of photogenerated electron-hole pairs.展开更多
Visible light communication(VLC) is expected to be a potential candidate of the key technologies in the sixth generation(6G) wireless communication system to support Internet of Things(IoT) applications. In this work,...Visible light communication(VLC) is expected to be a potential candidate of the key technologies in the sixth generation(6G) wireless communication system to support Internet of Things(IoT) applications. In this work, a separate least mean square(S-LMS) equalizer is proposed to compensate lowpass frequency response in VLC system. Joint optimization is employed to realize the proposed S-LMS equalizer with pre-part and post-part by introducing Lagrangian. For verification, the performance of VLC system based on multi-band carrier-less amplitude and phase(m-CAP) modulation with S-LMS equalizer is investigated and compared with that without equalizer,with LMS equalizer and with recursive least squares(RLS)-Volterra equalizer. Results indicate the proposed equalizer shows significant improved bit error ratio(BER) performance under the same conditions. Compared to the RLS-Volterra equalizer, SLMS equalizer achieves better performance under low data rate or high signal noise ratio(SNR) conditions with obviously lower computational complexity.展开更多
基金supported by the National MCF Energy R&D Program of China (Nos. 2018YFE0302103 and 2018YFE 0302100)National Natural Science Foundation of China (Nos. 12205195 and 11975277)。
文摘To investigate the potential of utilizing visible spectral imaging for controlling the plasma boundary shape during stable operation of plasma in future tokamak, a D_α band symmetric visible light diagnostic system was designed and implemented on the Experimental Advanced Superconducting Tokamak(EAST). This system leverages two symmetric optics for joint plasma imaging. The optical system exhibits a spatial resolution less than 2 mm at the poloidal cross-section, distortion within the field of view below 10%, and relative illumination of 91%.The high-quality images obtained enable clear observation of both the plasma boundary position and the characteristics of components within the vacuum vessel. Following system calibration and coordinate transformation, the image coordinate boundary features are mapped to the tokamak coordinate system. Utilizing this system, the plasma boundary was reconstructed, and the resulting representation showed alignment with the EFIT(Equilibrium Fitting) results. This underscores the system's superior performance in boundary reconstruction applications and provides a diagnostic foundation for boundary shape control based on visible spectral imaging.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61975072 and 12174173)the Natural Science Foundation of Fujian Province,China (Grant Nos.2022H0023,2022J02047,ZZ2023J20,and 2022G02006)。
文摘Real-time,contact-free temperature monitoring of low to medium range(30℃-150℃)has been extensively used in industry and agriculture,which is usually realized by costly infrared temperature detection methods.This paper proposes an alternative approach of extracting temperature information in real time from the visible light images of the monitoring target using a convolutional neural network(CNN).A mean-square error of<1.119℃was reached in the temperature measurements of low to medium range using the CNN and the visible light images.Imaging angle and imaging distance do not affect the temperature detection using visible optical images by the CNN.Moreover,the CNN has a certain illuminance generalization ability capable of detection temperature information from the images which were collected under different illuminance and were not used for training.Compared to the conventional machine learning algorithms mentioned in the recent literatures,this real-time,contact-free temperature measurement approach that does not require any further image processing operations facilitates temperature monitoring applications in the industrial and civil fields.
基金This work is jointly supported by the National Natural Science Foundation of China under Grant Nos.62004103,62105162,62005130,61827804,62274096,and 61904086the Natural Science Foundation of Jiangsu Province under Grant No.BK20200743+3 种基金the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province under Grant No.22KJA510003the Natural Science Foundation of Nanjing University of Posts and Telecommunications under Grant No.NY223084the“111”project under Grant No.D17018the Postgraduate Research&Practice Innovation Program of Jiangsu Province under Grant No.SJCX230257.
文摘While considerable research has been conducted on the structural principles,fabrication techniques,and photoelectric properties of high-voltage light-emitting diodes(LEDs),their performance in light communication remains underexplored.A high-voltage seriesconnected LED or photodetector(HVS-LED/PD)based on the gallium nitride(GaN)integrated photoelectronic chip is presented in this paper.Multi-quantum wells(MQW)diodes with identical structures are integrated onto a single chip through wafer-scale micro-fabrication techniques and connected in series to construct the HVS-LED/PD.The advantages of the HVS-LED/PD in communication are explored by testing its performance as both a light transmitter and a PD.The series connection enhances the device's 3 dB bandwidth,allowing it to increase from 1.56 MHz to a minimum of 2.16 MHz when functioning as an LED,and from 47.42 kHz to at least 85.83 kHz when operating as a PD.The results demonstrate that the light communication performance of HVS-LED/PD is better than that of a single GaN MQW diode with bandwidth and transmission quantity,which enriches the research of GaN-based high-voltage devices.
文摘From 14 to 17 January,2025 already 2,900 exhibitors from 60 countries will present current trends,the latest collections,innovative materials and textile solutions at Heimtextil.High-calibre highlights await visitors:For the first time,the Milanbased design platform Alcova will curate the Heimtextil Trends 25/26.In addition,the worldwide renowned designer and architect Patricia Urquiola brings textile design to life in the exclusive installation‘among-us’.
基金supported by the Guangdong Basic and Applied Basic Research Foundation No.2021A1515110958National Natural Science Foundation of China No.62202215+2 种基金SYLU introduced high-level talents scientific research support planChongqing University Innovation Research Group(CXQT21019)Chongqing Talents Project(CQYC201903048)。
文摘Visible light(VL)plays an important role in achieving high-precision positioning and low bit error radio(BER)data communication.However,most VL-based systems can not achieve positioning and communication,simultaneously.There are two problems:1)the hybrid systems are difficult to extract distinguishable positioning beacon features without affecting communication performance,2)in the hybrid systems,the lost data bits in the inter-frame gap(IFG)are hard to recover,which affects positioning and communication performance.Therefore,in this article,we propose a novel VL-based hybrid positioning and communication system,named HY-PC system,to solve the above problems.First,we propose the robust T-W mapping for recognizing specific Light Emitting Diodes(LEDs),which can provide stable LED recognition accuracy without adding extra beacon data and does not decrease the communication rate.Furthermore,we also propose the novel linear block coding and bit interleaving mechanism,which can recover the lost data bits in the IFG and improve data communication performance.Finally,we use commercial off-the-shelf devices to implement our HY-PC system,extensive experimental results show that our HY-PC system can achieve consistent high-precision positioning and low-BER data communication,simultaneously.
基金supported by the National Natural Science Foundation of China(NSFC)(20903022,20903023,21173045)the Award Program for Minjiang Scholar Professorship+1 种基金the Science and Technology Development of Foundation of Fuzhou University(2009-XQ-10)the Open Fund of Photocatalysis of Fuzhou University(0380038004)
文摘Two-dimensional （2-D） BiVO4 nanosheets-graphene （GR） composites with different weight addition ratios of GR have been prepared via a facile wet chemistry process. X-ray diffraction （XRD）, Raman spectra, X-ray photoelectron spectra （XPS）, UV-vis diffuse reflectance spectra （DRS）, field-emission scanning electron microscopy （FE-SEM）, transmission electron microscopy （TEM）, nitrogen adsorption-desorption, transient photocurrent response and photoluminescence （PL） spectra were employed to determine the properties of the samples. It is found that BiVO4 nanosheets could pave well on the surface of graphene sheets. BiVO4 nanosheets-GR composites with a proper addition amount of GR exhibited higher photocatalytic activity than bare BiVO4 nanosheets toward liquid-phase degradation of rhodamine B （RhB） and methyl orange （MO） under visible light irradiation. The enhancement of photocatalytic activities of BiVO4 nanosheets-GR composites can be attributed to the effective separation of photoexcited electron-hole pairs. This work not only provides a simple strategy for fabricating specific 2-D semiconductor-2-D GR composites, but also opens a new window of such 2-D semiconductor-2-D GR composites as visible light photocatalysts toward an improved visible light photoactivity in purifying polluted water resources.
基金supported by National Nature Science Foundation of China (No. 61373124)supported by China Scholarship Funds (2014CB3033)
文摘The key techniques in indoor positioning based on visible light communication and the state of the art of this research were surveyed. First, the significance of indoor positioning based on visible light communication from two aspects of the limitations of current indoor positioning technology and the advantages of visible light communication was discussed; And then, the main four technology of indoor positioning based on visible light communication were summarized and the triangulation of RSS method and the principle of image positioning were introduced in detail; Next, the performance characteristics of various typical algorithms were compared and analyzed; In the end, several suggestions on future research of indoor positioning based on visible light communication were given.
基金support from the National Natural Science Foundation of China (Grant No. 61371110)Key R&D Program of Shandong Province (Grant No. 2016GGX101014)+1 种基金EU H2020 RISE TESTBED project (Grant No. 734325)the Fundamental Research Funds of Shandong University (No. 2017JC029)
文摘In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of underlying physical propagation phenomenon should be carried out to realize VLC system in underground mines. To design VLC system and evaluate its performance, accurate and efficient channel models, including large-scale fading and scattering characteristics, are needed to be established. However,the characteristics of the underlying VLC channels about fading and scattering have not been sufficiently investigated yet. In this paper, a path loss channel model, based on the recursive model, is proposed precisely. Its path loss exponent is determined by three different trajectories, which is studied in the mining roadway and working face environment. Besides, the shadowing effect for VLC has been modelled by a Bimodal Gaussian distribution in underground mines. Considering the number of transmitters in line-of-sight(Lo S) as well as non-line-of-sight(NLo S) scenarios,our simulation illustrates the fact that, as the curve fitting technique is employed, the path loss displays a linear behavior in log-domain.The path loss expression is derived, it is related to the distance. Finally, root mean square(RMS) delay spread and Mie scattering in underground mines are analyzed.
基金the financial support from the Ministry of Science and Technology,Taiwan(MOST 104-2218-E-033-006-MY2)
文摘NaTaONcatalysts were synthesized by a hydrothermal（H） and a solid-state（S） methods in this study.The H-and S-NaTaONsamples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, UV–visible（UV–vis） diffuse reflectance spectroscopy, and photoluminescence（PL） spectroscopy. The XRD patterns of the H-and S-samples showed peaks indexed to the pure phase of perovskite NaTaOand minor peaks assignable to TaNat various synthesis temperatures. Substitution of oxygen by nitrogen ions causes the light absorption of the H-and S-NaTaONsamples to be extended to the 600–650 nm region, thus making the samples visible-light active. The NaTaONsamples exhibited photocatalytic activity for Hand Oevolution from aqueous methanol and silver nitrate solutions under visible-light irradiation. The UV–vis and PL spectra of the Hand S-catalysts revealed the presence of cationic vacancies and reduced metallic species, which acted as recombination centers. These results demonstrated that the preparation method plays a critical role in the formation of defect states, thereby governing the photocatalytic activity of the NaTaONcatalysts.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21476098,21471069 and 21576123)and Jiangsu University Scientific Research Funding(No.11JDG0146).
文摘Photocatalysis is considered as an ideal strategy for water pollution treatment.However,it remains challenging to design a highly efficient photo-catalytic system through regulating the charge flow via a precise approach.In this work,a novel NH2-MIL-125(Ti)/Bi2WO6 composite was constructed via self-assembly growing Bi2WO6 nanosheets on NH2-MIL-125(Ti)material.The characterization results demonstrated that NH2-MIL-125(Ti)was successfully incorporated into Bi2WO6 and the photoexcited carriers could be efficiently separated and transferred between the two components.NH2-MIL-125(Ti)/Bi2WO6 composites displayed enhanced photocatalytic activity for the removal of rhodamine B(RhB)and tetracycline(TC)under visible light irradiation,and the optimal weight ratio of NH2-MIL-125(Ti)was determined to be 7 wt%.The introduction of NH2-MIL-125(Ti)into Bi2WO6 could raise the absorption of visible light,accelerate the separation and transfer of charge carriers,and boost photocatalytic activity.This research presents a wide range of possibilities for the further development of novel composites in the field of environment purification.
基金supported by the Fundamental Research Funds for the Central Universities(XK1802-6,XK1902,XK1803-05,12060093063,2312018RC07)the National Natural Science Foundation of China(U1707603,21878008,21625101,20190816)。
文摘Photocatalytic reduction of CO2 with H2 O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry.Nevertheless,the precise control of CO/H2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further application.Herein,we prepared a series of highly efficient heterostructure based on highly dispersed palladium supported on ultrathin Co Al-layered double hydroxide(LDH).In conjunction with a Ru-complex sensitizer,the molar ratios of CO/H2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation(λ>400 nm).More interestingly,the syngas can be obtained under light irradiation atλ>600 nm.Structure characterization and density functional theory calculations revealed that the remarkable catalytic activity can be due to the supported palladium,which improved the charge transfer efficiency.Meanwhile,more H atoms were used to generate H2 on the supported palladium for further tunable CO/H2 ratio.This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock.
基金sponsored by Shanghai Pujiang Program(No.19PJ1405200)the Startup Fund for Youngman Research at SJTU(SFYR at SJTU,No.WF220516003)。
文摘Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.
基金supported in part by the National Natural Science Foundation of China(No.62061030,61661028,62031012,62071223,and 61701501)in part by the Young Elite Scientist Sponsorship Program by CAST and the National Key Research and Development Project of China(2018YFB1404303,2018YFB14043033,and 2018YFB1800801)+1 种基金in part by the Natural Science Foundation of Jiangsu Province(BK20170287)by Open Fund of IPOC(BUPT),and by Young Talents of Xuzhou Science and Technology Plan Project(KC19051).
文摘Visible light communication(VLC)and non-orthogonal multiple access(NOMA)have been deemed two promising techniques in the next wireless communication networks.In this paper,secure communications in the presence of potential eavesdropper are investigated for a multiple-input single-output VLC system with NOMA.The artificial noise jamming and beamforming technologies are applied to improve secure performance.A robust resource allocation scheme is proposed to minimize the total transmit power taking into account the constraints on the quality of service requirement of the desired users and the maximum tolerable data rate of the eavesdropper,and the practical imperfect channel state information of both the desired users and the eavesdropper.The formulated non-convex optimization problem is tackled based onS-Procedure and semi-definite programming relaxation.Simulation results illustrate that our proposed resource allocation scheme can effectively guarantee communication security and achieve transmit power saving.Moreover,the height and number of LED can significantly affect system performance and the optimum LED height can be obtained for different LED numbers.
基金supported by the China Postdoctoral Science Foundation (2016M602647)the Science and Technology Research Project of Chongqing Municipal Education Commission of China (KJ1400607)+3 种基金the Fundamental Research Funds for the Central Universities (CQDXWL-2014-001)NSFCQ (cstc2015jcyj A20020)NSFC (51572040, 51402112)National High Technology Research and Development Program of China (2015AA034801)
文摘Ag–AgX(X = Cl, Br)@TiO_2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol–gel technique with post-photoreduction. The photocatalytic activities of both Ag–Ag Cl@TiO_2 and Ag–Ag Br@TiO_2 under visible light are effectively improved by ~3 times relative to TiO_2 NPAS under the simulated sunlight for the decomposition of methyl orange(MO). Ag–AgBr@TiO_2 showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO_2. The role of Ag and Ag X nanoparticles on the surface of Ag–Ag X(X = Cl,Br)@TiO_2 was discussed. Ag on these samples not onlycan efficiently harvest visible light especially for Ag Cl, but also efficiently separate excited electrons and holes via the fast electron transfer from Ag X(X = Cl, Br) to metal Ag nanoparticles and then to TiO_2-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.
基金supported by National Natural Science Foundation of China grants(No.61401069,No.61271240,No.61501254)Jiangsu Specially Appointed Professor Grant(RK002STP16001)+2 种基金Innovation and Entrepreneurship of Jiangsu High-level Talent Grant(CZ0010617002)High-level talent startup grant of Nanjing University of Posts and Telecommunications(XK0010915026)“1311 Talent Plan” of Nanjing University of Posts and Telecommunications
文摘Non-orthogonal multiple access(NOMA) is considered as one of promising radio access techniques for visible light communications(VLC) in next-generation wireless communications systems.In order to provide theoretical support for designing VLC-NOMA,we derive its analytic expressions for the symbol error rate(SER).Specifically,NOMA is first incorporated with appropriate VLC to establish a VLC-NOMA framework.Afterwards,mathematical expressions of the SER for the VLC-NOMA are developed.Moreover,numerical results are provided carefully to demonstrate that the proposed VLC-NOMA scheme outperforms than state-of-the-art orthogonal frequency division multiple access(OFDMA) one in terms of SER performance.Finally,relationships between the SER performance and the number of users,power allocation coefficient and semi-angle are well investigated,which can give us a scientific guide to devise the VLC-NOMA system for achieving better SER performance.
基金supported by the NNSF of China(No.61177071, No.61250018)the Key Program of Shanghai Science and Technology Association (12dz1143000)
文摘In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.
基金financially supported by the National Natural Science Foundation of China(Grant No.21090341 and 21361140346)the National Basic Research Program(973 Program)of the Ministry of Science and Technology of China(Grant No.2014CB239401)
文摘A novel Sr2CulnO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations （DFT） and electrochem ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat alytic hydrogen production experiments under a visible light irradiation （A〉420 nm） were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.
基金supported by the National Natural Science Foundation of China(Nos.11674269,61975168).
文摘Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope efficiencies of 34.7%,27.3%,and 12.3%were achieved with good beam qualities(M^(2)<1.6)at 670.4 nm,674.2 nm,and 678.9 nm,respectively.Record-high output power(2.6 W)and record-high slope efficiency(34.7%)were achieved for the Pr^(3+):YLF laser operation at 670.4 nm.This is also the first demonstration of longer-wavelength peaks beyond 670 nm in the^(3)P_(1)→^(3)F_(3)transition of Pr^(3+):YLF.In multi-wavelength laser operations,the dual-wavelength lasings,including 670.1/674.8 nm,670.1/679.1 nm,and 675.0/679.4 nm,were obtained by fine adjustment of one/two etalons within the cavity.Furthermore,the triple-wavelength lasings,e.g.672.2/674.2/678.6 nm and 670.4/674.8/679.4 nm,were successfully demonstrated.Moreover,both the first-order vortex lasers(LG_(0)^(+1)and LG_(0)^(-1)modes)at 670.4 nm were obtained by off-axis pumping.
基金DST,India for financial grant(SB/S1/PC-011/2013)DAE(India)for financial grant 2013/37P/73/BRNS,NTH-School‘‘Contacts in Nanosystems:Interactions,Control and Quantum Dynamics’’+1 种基金the Braunschweig International Graduate School of Metrology(IGSM)DFG-RTG 1952/1,Metrology for Complex Nanosystems
文摘Bismuth containing nanomaterials recently received increasing attention with respect to environmental applications because of their low cost, high stability and nontoxicity. In this work, Bi–Bi_2O_2CO_3 heterojunctions were fabricated by in-situ decoration of Bi nanoparticles on Bi_2O_2CO_3 nanosheets via a simple hydrothermal synthesis approach. X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and high-resolution TEM(HRTEM) were used to confirm the morphology of the nanosheet-like heterostructure of the Bi–Bi_2O_2CO_3 composite. Detailed ultrafast electronic spectroscopy reveals that the in-situ decoration of Bi nanoparticles on Bi_2O_2CO_3 nanosheets exhibit a dramatically enhanced electron-hole pair separation rate, which results in an extraordinarily high photocatalytic activity for the degradation of a model organic dye, methylene blue(MB) under visible light illumination. Cycling experiments revealed a good photochemical stability of the Bi–Bi_2O_2CO_3 heterojunction under repeated irradiation. Photocurrent measurements further indicated that the heterojunction incredibly enhanced the charge generation and suppressed the charge recombination of photogenerated electron-hole pairs.
基金supported by National Natural Science Foundation of China (No.61671055)Scientific and Technological Innovation Foundation of Shunde Graduate School, USTB(BK19BF008)。
文摘Visible light communication(VLC) is expected to be a potential candidate of the key technologies in the sixth generation(6G) wireless communication system to support Internet of Things(IoT) applications. In this work, a separate least mean square(S-LMS) equalizer is proposed to compensate lowpass frequency response in VLC system. Joint optimization is employed to realize the proposed S-LMS equalizer with pre-part and post-part by introducing Lagrangian. For verification, the performance of VLC system based on multi-band carrier-less amplitude and phase(m-CAP) modulation with S-LMS equalizer is investigated and compared with that without equalizer,with LMS equalizer and with recursive least squares(RLS)-Volterra equalizer. Results indicate the proposed equalizer shows significant improved bit error ratio(BER) performance under the same conditions. Compared to the RLS-Volterra equalizer, SLMS equalizer achieves better performance under low data rate or high signal noise ratio(SNR) conditions with obviously lower computational complexity.
