In this paper a novel coding method based on fuzzy vector quantization for noised image with Gaussian white-noise pollution is presented. By restraining the high frequency subbands of wavelet image the noise is signif...In this paper a novel coding method based on fuzzy vector quantization for noised image with Gaussian white-noise pollution is presented. By restraining the high frequency subbands of wavelet image the noise is significantly removed and coded with fuzzy vector quantization. The experimental result shows that the method can not only achieve high compression ratio but also remove noise dramatically.展开更多
We have investigated the photon-assisted shot noise properties in the magnetic field tunable heterostructures. Transport properties of the model structure are strongly dependent on the oscillatory field and the magnet...We have investigated the photon-assisted shot noise properties in the magnetic field tunable heterostructures. Transport properties of the model structure are strongly dependent on the oscillatory field and the magnetic field. In this structure,electrons can absorb or emit one or multi-photons to reach the quasi-bound state. As a result, the transmission properties are affected considerably by photon-assisted tunneling and these features cause the nontrivial variations in the shot noise and Fano factor. It is found that the shot noise becomes spin-dependent and can be modulated not only by the magnetic field, but also by the oscillatory field. Both the spin-up and spin-down components of the shot noise can be greatly suppressed by the magnetic field, and can also be drastically enhanced by the harmonically driven field. Furthermore,with increasing external magnetic field, it is important to note that the enhanced intensity is decreased, even suppressed.These results suggest another method to suppress the shot noise via modulating the oscillatory field at a diluted-magneticsemiconductors/semiconductor structure.展开更多
Spin noise spectroscopy （SNS） of electrons in n-doped bulk GaAs is studied as functions of temperature and the probe-laser energy. Experimental results show that the SNS signal comes from localized electrons in the ...Spin noise spectroscopy （SNS） of electrons in n-doped bulk GaAs is studied as functions of temperature and the probe-laser energy. Experimental results show that the SNS signal comes from localized electrons in the donor band. The spin relaxation time of electrons~ which is retrieved from the SNS measurement, depends on the probe light energy and temperature, and it can be ascribed to the variation of electron localization degree.展开更多
This paper studies the performance of the GOSGO and GOSSO CFAR detectors [1] in clutter edge situation. The authors derive the analytic expressions of the false alarm probabilities in that situation, analyze their per...This paper studies the performance of the GOSGO and GOSSO CFAR detectors [1] in clutter edge situation. The authors derive the analytic expressions of the false alarm probabilities in that situation, analyze their performances against clutter edge, and compare them with the OS, CA, GO and SO detectors. The results show that GOSGO possesses better performance than GO for countering clutter, but the performance of GOSSO is very unideal.展开更多
Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 1...Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 135 mW, this preamplifier can produce above 30-dB gain and keep the noise figure below 4.76 dB for all C-band signals, with the minimum noise figure as low as 3.38 dB for-30-dBm, 1550-nm signal.展开更多
Propagation properties of polarized anisotropic crystals were investigated four-petal Gaussian beams along the optical axis of uniaxially Based on the paraxially vectorial theory of beam propagation analytic expressio...Propagation properties of polarized anisotropic crystals were investigated four-petal Gaussian beams along the optical axis of uniaxially Based on the paraxially vectorial theory of beam propagation analytic expressions of the diffraction light field larization properties of the diffracted four-petal were obtained. The effects of the anisotropy on the po- Gaussian beams have also been explained by numerical method. The results elucidate that the linear polarization state and the symmetry of the incident beams cannot be kept during propagation in anisotropic crystals.展开更多
Micro stereo lithography is a kind of technology utilizing the solidified effect that photo curable polymer will appear under ultraviolet （UV） laser exposure. It is widely used in three-dimensional （3D） micro fabr...Micro stereo lithography is a kind of technology utilizing the solidified effect that photo curable polymer will appear under ultraviolet （UV） laser exposure. It is widely used in three-dimensional （3D） micro fabrication. We get the experimental values of a pair of UV laser curing coefficients, absorption coefficient and critical curing energy, of curable resin by fitting the calculation results of the Gaussian beam theory and experimental curing results. The theoretical relation between the curing unit＇s shape and the exposure features of time and intensity of convergent Gaussian beam is presented. The calculation and experimental results of curing unit under different conditions agree well with each other. This research offers a steady base for further research about the improvement of resolution.展开更多
文摘In this paper a novel coding method based on fuzzy vector quantization for noised image with Gaussian white-noise pollution is presented. By restraining the high frequency subbands of wavelet image the noise is significantly removed and coded with fuzzy vector quantization. The experimental result shows that the method can not only achieve high compression ratio but also remove noise dramatically.
基金Project supported by the National Natural Science Foundation of China(Grant No.11574173)the National Basic Research Program of China(Grant No.2011CB606405)the General Program of Science and Technology Development Project of Beijing Municipal Education Commission of China(Grant No.KM201410028021)
文摘We have investigated the photon-assisted shot noise properties in the magnetic field tunable heterostructures. Transport properties of the model structure are strongly dependent on the oscillatory field and the magnetic field. In this structure,electrons can absorb or emit one or multi-photons to reach the quasi-bound state. As a result, the transmission properties are affected considerably by photon-assisted tunneling and these features cause the nontrivial variations in the shot noise and Fano factor. It is found that the shot noise becomes spin-dependent and can be modulated not only by the magnetic field, but also by the oscillatory field. Both the spin-up and spin-down components of the shot noise can be greatly suppressed by the magnetic field, and can also be drastically enhanced by the harmonically driven field. Furthermore,with increasing external magnetic field, it is important to note that the enhanced intensity is decreased, even suppressed.These results suggest another method to suppress the shot noise via modulating the oscillatory field at a diluted-magneticsemiconductors/semiconductor structure.
基金Supported by the National Key Research and Development Program of China under Grant No 2016YFA0301202the National Basic Research Program of China under Grant No 2013CB922304+1 种基金the National Natural Science Foundation of China under Grant Nos 91321310 and 11674311the K.C.Wong Education Foundation
文摘Spin noise spectroscopy （SNS） of electrons in n-doped bulk GaAs is studied as functions of temperature and the probe-laser energy. Experimental results show that the SNS signal comes from localized electrons in the donor band. The spin relaxation time of electrons~ which is retrieved from the SNS measurement, depends on the probe light energy and temperature, and it can be ascribed to the variation of electron localization degree.
文摘This paper studies the performance of the GOSGO and GOSSO CFAR detectors [1] in clutter edge situation. The authors derive the analytic expressions of the false alarm probabilities in that situation, analyze their performances against clutter edge, and compare them with the OS, CA, GO and SO detectors. The results show that GOSGO possesses better performance than GO for countering clutter, but the performance of GOSSO is very unideal.
文摘Focused on the low noise figure requirements of erbium-doped preamplifiers, a two stage cascade preamplifier was presented based on the optimized design. With the total fiber length of 31.4 m and total pump power of 135 mW, this preamplifier can produce above 30-dB gain and keep the noise figure below 4.76 dB for all C-band signals, with the minimum noise figure as low as 3.38 dB for-30-dBm, 1550-nm signal.
基金the Open Subject of the Important Labortary of the Modern Optical Technology of Jiangsu Provience(No.KJS0730)
文摘Propagation properties of polarized anisotropic crystals were investigated four-petal Gaussian beams along the optical axis of uniaxially Based on the paraxially vectorial theory of beam propagation analytic expressions of the diffraction light field larization properties of the diffracted four-petal were obtained. The effects of the anisotropy on the po- Gaussian beams have also been explained by numerical method. The results elucidate that the linear polarization state and the symmetry of the incident beams cannot be kept during propagation in anisotropic crystals.
基金supported by the National "863" Program of China under Grant No. 2006AA04Z311
文摘Micro stereo lithography is a kind of technology utilizing the solidified effect that photo curable polymer will appear under ultraviolet （UV） laser exposure. It is widely used in three-dimensional （3D） micro fabrication. We get the experimental values of a pair of UV laser curing coefficients, absorption coefficient and critical curing energy, of curable resin by fitting the calculation results of the Gaussian beam theory and experimental curing results. The theoretical relation between the curing unit＇s shape and the exposure features of time and intensity of convergent Gaussian beam is presented. The calculation and experimental results of curing unit under different conditions agree well with each other. This research offers a steady base for further research about the improvement of resolution.
