We design and construct a resonant photodetector(RPD)with a Q factor of 320.83 at the resonant frequency of38.5 MHz on the basis of a theoretical analysis.Compared with the existing RPD under the same conditions,the s...We design and construct a resonant photodetector(RPD)with a Q factor of 320.83 at the resonant frequency of38.5 MHz on the basis of a theoretical analysis.Compared with the existing RPD under the same conditions,the signalto-noise-ratio of the error signal is increased by 15 dB and the minimum operation power is reduced from-55 dBm to-70 dBm.By comparing the standard deviations of the stability curves,we confirm that the RPD has a dramatic improvement on ultralow power extraction.In virtue of the RPD,we have completed the demonstration of channel multiplexing quantum communication.展开更多
Wireless Sensor Networks (WSNs) typically use in-network processing to reduce the communication overhead. Due to the fusion of data items sourced at different nodes into a single one during in-network processing, the ...Wireless Sensor Networks (WSNs) typically use in-network processing to reduce the communication overhead. Due to the fusion of data items sourced at different nodes into a single one during in-network processing, the sanctity of the aggregated data needs to be ensured. Especially, the data integrity of the aggregated result is critical as any malicious update to it can jeopardize not one, but many sensor readings. In this paper, we analyse three different approaches to providing integrity support for SDA in WSNs. The first one is traditional MAC, in which each leaf node and intermediate node share a key with parent (symmetric key). The second is aggregate MAC (AMAC), in which a base station shares a unique key with all the other sensor nodes. The third is homomorphic MAC (Homo MAC) that is purely symmetric key-based approach. These approaches exhibit diverse trade-off in resource consumption and security assumptions. Adding together to that, we also propose a probabilistic and improved variant of homomorphic MAC that improves the security strength for secure data aggregation in WSNs. We carry out simulations in TinyOS environment to experimentally evaluate the impact of each of these on the resource consumption in WSNs.展开更多
Herein, we report visible light active mesoporous cadmium bismuth niobate（CBN） nanospheres as a photocatalyst for hydrogen（H） generation from copious hydrogen sulfide（HS）. CBN has been synthesized by solid state...Herein, we report visible light active mesoporous cadmium bismuth niobate（CBN） nanospheres as a photocatalyst for hydrogen（H） generation from copious hydrogen sulfide（HS）. CBN has been synthesized by solid state reaction（SSR） and also using combustion method（CM） at relatively lower temperatures.The as-synthesized materials were characterized using different techniques. X-ray diffraction analysis shows the formation of single phase orthorhombic CBN. Field emission scanning electron microscopy and high resolution-transmission electron microscopy showed the particle size in the range of.5–1 μm for CBN obtained by SSR and 50–70 nm size nanospheres using CM, respectively. Interestingly, nanospheres of size 50–70 nm self assembled with 5–7 nm nanoparticles were observed in case of CBN prepared by CM.The optical properties were studied using UV–visible diffuse reflectance spectroscopy and showed band gap around.0 eV for SSR and 3.1 eV for CM. The slight shift in band gap of CM is due to nanocrystalline nature of material. Considering the band gap in visible region, the photocatalytic activity of CBN for hydrogen production from HS has been performed under visible light. CBN prepared by CM has shown utmost hydrogen evolution i.e. 6912 μmol/h/0.5 g which is much higher than CBN prepared using SSR.The enhanced photocatalytic property can be attributed to the smaller particle size, crystalline nature,high surface area and mesoporous structure of CBN prepared by combustion method. The catalyst was found to be stable, active and can be utilized for water splitting.展开更多
Population reduction effect generated in two-photon resonant excitation process of potassium atoms in a potassium molecule-atom system is theoretically investigated The obtained result is compared with the relevant ex...Population reduction effect generated in two-photon resonant excitation process of potassium atoms in a potassium molecule-atom system is theoretically investigated The obtained result is compared with the relevant experimental ones in the process of two-photon resonant excitation of potassium molecules and in the process of two-photon mixed excitation of potassium molecule-atoms.展开更多
In this letter, exact chirped multi-soliton solutions of the nonlinear Schrodinger (NLS) equation with varying coefficients are found. The explicit chirped one- and two-soliton solutions are generated. As an example, ...In this letter, exact chirped multi-soliton solutions of the nonlinear Schrodinger (NLS) equation with varying coefficients are found. The explicit chirped one- and two-soliton solutions are generated. As an example, an exponential distributed control system is considered, and some main features of solutions are shown. The results reveal that chirped soliton can all be nonlinearly compressed cleanly and efficiently in an optical fiber with no loss or gain, with the loss, or with the gain. Furthermore, under the same initial condition, compression of optical soliton in the optical fiber with the loss is the most dramatic. Also, under nonintegrable condition and finite initial perturbations, the evolution of chirped soliton has been demonstrated by simulating numerically.展开更多
It is well known that the undistorted transmission of pulses is impossible in bulk dispersive linear media with the transverse effects not being considered. The compressing or broadening of optical pulses during trans...It is well known that the undistorted transmission of pulses is impossible in bulk dispersive linear media with the transverse effects not being considered. The compressing or broadening of optical pulses during transmission depends on the incident pulse states. In order to achieve ultrahigh data rates of transmission in optical communication systems, several possible ways of overcoming dispersion effects have been employed. Among them the most significant and practial one was suggested by Hasegawa et al. , in which the nonlinear dependence of the refractive index on pulse intensity was utilized. This展开更多
We derived the theoretical results of soliton interactions in optical fiber with super-Gaussian sliding-frequency filters. The results demonstrate that the interactions between optical fiber solitons can be effectivel...We derived the theoretical results of soliton interactions in optical fiber with super-Gaussian sliding-frequency filters. The results demonstrate that the interactions between optical fiber solitons can be effectively suppressed by super-Gaussian sliding-frequency filters. And the results also show that the super-Gaussian filter with sliding is more effective in suppressing soliton interactions than that without sliding.展开更多
We present an expression of maximum fiber-link length, at which the output pulses can return to its original rms time width, in an optical fiber link with up to fourth-order dispersion. The fourth order dispersion is ...We present an expression of maximum fiber-link length, at which the output pulses can return to its original rms time width, in an optical fiber link with up to fourth-order dispersion. The fourth order dispersion is compensated by combination of the effects of proper source chirping and negative residual second-order dispersion. The interesting fact is that the optical pulses can restore itself at a longest distance even in case of chirp parameter being positive, as well as being negative traditionally. The validity of the analytical formulas is also confirmed by split-step Fourier numerical stimulation.展开更多
The short Hermite-Gaussian optical pulse transmission over 1440 km in a dense dispersion compensated system is investigated based on numerical simulation. In the simulation, compensation is made not only for the group...The short Hermite-Gaussian optical pulse transmission over 1440 km in a dense dispersion compensated system is investigated based on numerical simulation. In the simulation, compensation is made not only for the group-velocity dispersion but also for the third order dispersion. It is demonstrated that the pulse with reasonably lower power can propagate steadily in net zero, positive and negative dispersion system.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62027821,11654002,11874250,and 11804207)the National Key R&D Program of China(Grant No.2016YFA0301401)+3 种基金the Key R&D Program of Shanxi,China(Grant No.201903D111001)the Program for Sanjin Scholar of Shanxi Provincethe Program for Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,Chinathe Fund for Shanxi“1331 Project”Key Subjects Construction,China。
文摘We design and construct a resonant photodetector(RPD)with a Q factor of 320.83 at the resonant frequency of38.5 MHz on the basis of a theoretical analysis.Compared with the existing RPD under the same conditions,the signalto-noise-ratio of the error signal is increased by 15 dB and the minimum operation power is reduced from-55 dBm to-70 dBm.By comparing the standard deviations of the stability curves,we confirm that the RPD has a dramatic improvement on ultralow power extraction.In virtue of the RPD,we have completed the demonstration of channel multiplexing quantum communication.
文摘Wireless Sensor Networks (WSNs) typically use in-network processing to reduce the communication overhead. Due to the fusion of data items sourced at different nodes into a single one during in-network processing, the sanctity of the aggregated data needs to be ensured. Especially, the data integrity of the aggregated result is critical as any malicious update to it can jeopardize not one, but many sensor readings. In this paper, we analyse three different approaches to providing integrity support for SDA in WSNs. The first one is traditional MAC, in which each leaf node and intermediate node share a key with parent (symmetric key). The second is aggregate MAC (AMAC), in which a base station shares a unique key with all the other sensor nodes. The third is homomorphic MAC (Homo MAC) that is purely symmetric key-based approach. These approaches exhibit diverse trade-off in resource consumption and security assumptions. Adding together to that, we also propose a probabilistic and improved variant of homomorphic MAC that improves the security strength for secure data aggregation in WSNs. We carry out simulations in TinyOS environment to experimentally evaluate the impact of each of these on the resource consumption in WSNs.
基金Department of Electronics and Information Technology(Deit Y),Government of India for financial supportB.P.H.E Society's Ahmednagar College Ahmednagar for financial supportNanocrystalline Materials Group C-MET for the kind support
文摘Herein, we report visible light active mesoporous cadmium bismuth niobate（CBN） nanospheres as a photocatalyst for hydrogen（H） generation from copious hydrogen sulfide（HS）. CBN has been synthesized by solid state reaction（SSR） and also using combustion method（CM） at relatively lower temperatures.The as-synthesized materials were characterized using different techniques. X-ray diffraction analysis shows the formation of single phase orthorhombic CBN. Field emission scanning electron microscopy and high resolution-transmission electron microscopy showed the particle size in the range of.5–1 μm for CBN obtained by SSR and 50–70 nm size nanospheres using CM, respectively. Interestingly, nanospheres of size 50–70 nm self assembled with 5–7 nm nanoparticles were observed in case of CBN prepared by CM.The optical properties were studied using UV–visible diffuse reflectance spectroscopy and showed band gap around.0 eV for SSR and 3.1 eV for CM. The slight shift in band gap of CM is due to nanocrystalline nature of material. Considering the band gap in visible region, the photocatalytic activity of CBN for hydrogen production from HS has been performed under visible light. CBN prepared by CM has shown utmost hydrogen evolution i.e. 6912 μmol/h/0.5 g which is much higher than CBN prepared using SSR.The enhanced photocatalytic property can be attributed to the smaller particle size, crystalline nature,high surface area and mesoporous structure of CBN prepared by combustion method. The catalyst was found to be stable, active and can be utilized for water splitting.
基金Project supported by the National Natural Science Foundation of China and the Natural Science Foundation of Shanxi Province of China.
文摘Population reduction effect generated in two-photon resonant excitation process of potassium atoms in a potassium molecule-atom system is theoretically investigated The obtained result is compared with the relevant experimental ones in the process of two-photon resonant excitation of potassium molecules and in the process of two-photon mixed excitation of potassium molecule-atoms.
基金This work was supported by the National Natural Science Foundation of China (No. 60477026), the Provincial Youth Science Foundation of Shanxi (No. 20011015).
文摘In this letter, exact chirped multi-soliton solutions of the nonlinear Schrodinger (NLS) equation with varying coefficients are found. The explicit chirped one- and two-soliton solutions are generated. As an example, an exponential distributed control system is considered, and some main features of solutions are shown. The results reveal that chirped soliton can all be nonlinearly compressed cleanly and efficiently in an optical fiber with no loss or gain, with the loss, or with the gain. Furthermore, under the same initial condition, compression of optical soliton in the optical fiber with the loss is the most dramatic. Also, under nonintegrable condition and finite initial perturbations, the evolution of chirped soliton has been demonstrated by simulating numerically.
基金Project supported by the National Natural Science Foundation of Chinathe Provincial Natural Science Foundation of Shanxi
文摘It is well known that the undistorted transmission of pulses is impossible in bulk dispersive linear media with the transverse effects not being considered. The compressing or broadening of optical pulses during transmission depends on the incident pulse states. In order to achieve ultrahigh data rates of transmission in optical communication systems, several possible ways of overcoming dispersion effects have been employed. Among them the most significant and practial one was suggested by Hasegawa et al. , in which the nonlinear dependence of the refractive index on pulse intensity was utilized. This
基金the National Natural Science Foundation of China (No.10674183)the National"973"Project of China (No.2004CB719804)Ph.D.Degrees Foundation of Ministry of Education of China (No.20060558068).
文摘We derived the theoretical results of soliton interactions in optical fiber with super-Gaussian sliding-frequency filters. The results demonstrate that the interactions between optical fiber solitons can be effectively suppressed by super-Gaussian sliding-frequency filters. And the results also show that the super-Gaussian filter with sliding is more effective in suppressing soliton interactions than that without sliding.
基金This work was supported by the National Natural Science Foundation of China(No.10074041)and Shanxi Province Youth Science Foundation(No.20011015).
文摘We present an expression of maximum fiber-link length, at which the output pulses can return to its original rms time width, in an optical fiber link with up to fourth-order dispersion. The fourth order dispersion is compensated by combination of the effects of proper source chirping and negative residual second-order dispersion. The interesting fact is that the optical pulses can restore itself at a longest distance even in case of chirp parameter being positive, as well as being negative traditionally. The validity of the analytical formulas is also confirmed by split-step Fourier numerical stimulation.
基金This research is supported by the National Natural Science Foundation of China (No. 10074041) and the Shanxi Province Youth Science Foundation (No. 20011015). Y. Xiao's e-mail address is xiaoyan @ mail. sxu. edu. cn.
文摘The short Hermite-Gaussian optical pulse transmission over 1440 km in a dense dispersion compensated system is investigated based on numerical simulation. In the simulation, compensation is made not only for the group-velocity dispersion but also for the third order dispersion. It is demonstrated that the pulse with reasonably lower power can propagate steadily in net zero, positive and negative dispersion system.
