Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is...Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is not always sufficient in the reduction of phase noise. In this work, the local SNR-based Goldstein filter is further developed with the improvements in the definition of the local SNR and the adaption of the filtering patch size. What＇s more, for preventing the loss of the phase signal caused by the excessive filtering, an iteration filtering operation is also introduced in this new algorithm. To evaluate the performance of the proposed algorithm, both a simulated digital elevation model （DEM） interferogram and real SAR deformation interferogram spanning the L＇ Aquila earthquake are carried out. The quantitative results from the simulated and real data reveal that up to 79.5% noises can be reduced by the new filter, indicating 9%-32% improvements over the previous local SNR-based Goldstein filter. This demonstrates that the new filter is not only equipped with sufficient adaption, but also can suppress the phase noise without the sacrifice of the phase signal.展开更多
With the use ofa Geiger proportional counter with sensor tube of Russian and Chinese origin, a comparison was made in this work between measurements of environmental ionizing radiation with these detectors and a sodiu...With the use ofa Geiger proportional counter with sensor tube of Russian and Chinese origin, a comparison was made in this work between measurements of environmental ionizing radiation with these detectors and a sodium iodide scintillator activated with TI （Thallium NaI）. Through measurements carried out in a room located inside a tower 25 meters high on the ITA （Technological Institute of Aeronautics） campus, it was possible to study the efficiency of the three instruments for the environmental measurement of ionizing radiations at that location. Between March 7th and June 2nd of 2017, in that region, nine intense and weak rains were observed with 12 cold fronts coming from southern Brazil. Radiation measurements and the local meteorology involved are analyzed in this work to verify possible correlations.展开更多
This paper investigates the design of digital Sigma-Delta Modulator (SDM) for fractional-N frequency synthesizer. Characteristics of SDMs are compared through theory analysis and simulation. The curve of maximum-loop-...This paper investigates the design of digital Sigma-Delta Modulator (SDM) for fractional-N frequency synthesizer. Characteristics of SDMs are compared through theory analysis and simulation. The curve of maximum-loop-bandwidth vs. maximum-phase-noise is suggested to be a new criterion to the performance of SDM,which greatly helps designers to select an appropriate SDM structure to meet their real application requirements and to reduce the cost as low as possible. A low-spur 3-order Mul-tistage Noise Shaping (MASH)-1-1-1 SDM using three 2-bit first-order cascaded modulators is proposed,which balances the requirements of tone-free and maximum operation frequency.展开更多
The application of the 3dB directional coupler is very extensive,such as the phase shifter,the attenuator and the RF pulse compressor etc.The performance of the 3dB directional coupler is very important for these comp...The application of the 3dB directional coupler is very extensive,such as the phase shifter,the attenuator and the RF pulse compressor etc.The performance of the 3dB directional coupler is very important for these components. Optimization design has been done using the HFSS code.The new phase shifter prototype using the new optimization results has been tested.The tested results are in agreement with the measured ones.展开更多
Quantum private comparison(QPC) aims to accomplish the equality comparison of the secrets from different users without disclosing their genuine contents by using the principles of quantum mechanics. In this paper, we ...Quantum private comparison(QPC) aims to accomplish the equality comparison of the secrets from different users without disclosing their genuine contents by using the principles of quantum mechanics. In this paper, we summarize eight modes of quantum state preparation and transmission existing in current QPC protocols first. Then, by using the mode of scattered preparation and one-way convergent transmission, we construct a new multi-user quantum private comparison(MQPC) protocol with two-particle maximally entangled states, which can accomplish arbitrary pair's comparison of equality amongK users within one execution. Analysis turns out that its output correctness and its security against both the outside attack and the participant attack are guaranteed. The proposed MQPC protocol can be implemented with current technologies. It can be concluded that the mode of scattered preparation and one-way convergent transmission of quantum states is beneficial to designing the MQPC protocol which can accomplish arbitrary pair's comparison of equality among K users within one execution.展开更多
A terahertz(THz) polarizer and switch structure is proposed based on the phase transition of vanadium dioxide(VO_2). When VO_2 is in the insulation phase, the resonance frequencies of the proposed structure are 1.49 T...A terahertz(THz) polarizer and switch structure is proposed based on the phase transition of vanadium dioxide(VO_2). When VO_2 is in the insulation phase, the resonance frequencies of the proposed structure are 1.49 THz and 1.22 THz for the x- and y-polarization, respectively. It can perform as a THz polarizer with extinction ratios of 52.5 dB and 17 dB for the y- and x-polarization, respectively; When VO_2 transforms into metallic phase, the resonance frequency for x-polarization wave shifts from 1.49 THz to 1.22 THz, while that remains still for the y-polarization component. It means that the structure can work as a polarization-dependent THz switch with a high extinction ratio of 32 dB.展开更多
When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantu...When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantum data bus for nonlinear nanomechanical resonator, the nonlinearity destroys the dynamical quantum information-storage and maintains the revival of quantum coherence of charge qubit. With the calculation of decoherence factor, we demon- strate the influence of the nonlinearity of nanomechanical resonator on engineered decoherence of charge qubit.展开更多
基金Foundation item： Projects（40974006, 40774003） supported by the National Natural Science Foundation of China Project（NCET-08-0570） supported by the Program for New Century Excellent Talents in Universities of China+2 种基金 Proj ect（2011JQ001） supported by the Fundamental Research Funds for the Central Universities of China Project（PolyU 5155/07E） supported by the Research Grants Council （RGC） of the Hong Kong Special Administrative Region, China Project（CX2011B 102） supported by the Doctoral Research Innovation of Hunan Province, China
文摘Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is not always sufficient in the reduction of phase noise. In this work, the local SNR-based Goldstein filter is further developed with the improvements in the definition of the local SNR and the adaption of the filtering patch size. What＇s more, for preventing the loss of the phase signal caused by the excessive filtering, an iteration filtering operation is also introduced in this new algorithm. To evaluate the performance of the proposed algorithm, both a simulated digital elevation model （DEM） interferogram and real SAR deformation interferogram spanning the L＇ Aquila earthquake are carried out. The quantitative results from the simulated and real data reveal that up to 79.5% noises can be reduced by the new filter, indicating 9%-32% improvements over the previous local SNR-based Goldstein filter. This demonstrates that the new filter is not only equipped with sufficient adaption, but also can suppress the phase noise without the sacrifice of the phase signal.
文摘With the use ofa Geiger proportional counter with sensor tube of Russian and Chinese origin, a comparison was made in this work between measurements of environmental ionizing radiation with these detectors and a sodium iodide scintillator activated with TI （Thallium NaI）. Through measurements carried out in a room located inside a tower 25 meters high on the ITA （Technological Institute of Aeronautics） campus, it was possible to study the efficiency of the three instruments for the environmental measurement of ionizing radiations at that location. Between March 7th and June 2nd of 2017, in that region, nine intense and weak rains were observed with 12 cold fronts coming from southern Brazil. Radiation measurements and the local meteorology involved are analyzed in this work to verify possible correlations.
基金the National Natural Science Foundation of China (No. 60025101, No.90207001, and No. 90307016).
文摘This paper investigates the design of digital Sigma-Delta Modulator (SDM) for fractional-N frequency synthesizer. Characteristics of SDMs are compared through theory analysis and simulation. The curve of maximum-loop-bandwidth vs. maximum-phase-noise is suggested to be a new criterion to the performance of SDM,which greatly helps designers to select an appropriate SDM structure to meet their real application requirements and to reduce the cost as low as possible. A low-spur 3-order Mul-tistage Noise Shaping (MASH)-1-1-1 SDM using three 2-bit first-order cascaded modulators is proposed,which balances the requirements of tone-free and maximum operation frequency.
文摘The application of the 3dB directional coupler is very extensive,such as the phase shifter,the attenuator and the RF pulse compressor etc.The performance of the 3dB directional coupler is very important for these components. Optimization design has been done using the HFSS code.The new phase shifter prototype using the new optimization results has been tested.The tested results are in agreement with the measured ones.
基金supported by the National Natural Science Foundation of China(Grant Nos.61402407,and 11375152)
文摘Quantum private comparison(QPC) aims to accomplish the equality comparison of the secrets from different users without disclosing their genuine contents by using the principles of quantum mechanics. In this paper, we summarize eight modes of quantum state preparation and transmission existing in current QPC protocols first. Then, by using the mode of scattered preparation and one-way convergent transmission, we construct a new multi-user quantum private comparison(MQPC) protocol with two-particle maximally entangled states, which can accomplish arbitrary pair's comparison of equality amongK users within one execution. Analysis turns out that its output correctness and its security against both the outside attack and the participant attack are guaranteed. The proposed MQPC protocol can be implemented with current technologies. It can be concluded that the mode of scattered preparation and one-way convergent transmission of quantum states is beneficial to designing the MQPC protocol which can accomplish arbitrary pair's comparison of equality among K users within one execution.
基金supported by the National Basic Research Program of China(No.2014CB339800)the National Natural Science Foundation of China(Nos.61171027 and 61505088)+1 种基金the Natural Science Foundation of Tianjin of China(No.15JCQNJC02100)the Project of Science and Technology Program of Tianjin of China(No.13RCGFGX01127)
文摘A terahertz(THz) polarizer and switch structure is proposed based on the phase transition of vanadium dioxide(VO_2). When VO_2 is in the insulation phase, the resonance frequencies of the proposed structure are 1.49 THz and 1.22 THz for the x- and y-polarization, respectively. It can perform as a THz polarizer with extinction ratios of 52.5 dB and 17 dB for the y- and x-polarization, respectively; When VO_2 transforms into metallic phase, the resonance frequency for x-polarization wave shifts from 1.49 THz to 1.22 THz, while that remains still for the y-polarization component. It means that the structure can work as a polarization-dependent THz switch with a high extinction ratio of 32 dB.
文摘When the nonlinearity of nanomechanical resonator is not negligible, the quantum decoherenee of charge qubit is studied analytically. Using nonlinear Jaynes-Cummings model, one explores the possibility of being quantum data bus for nonlinear nanomechanical resonator, the nonlinearity destroys the dynamical quantum information-storage and maintains the revival of quantum coherence of charge qubit. With the calculation of decoherence factor, we demon- strate the influence of the nonlinearity of nanomechanical resonator on engineered decoherence of charge qubit.
