A 16 bit stereo audio novel stability fifth-order ∑△ A/D converter that consists of switched capacitor ∑△ modulators, a decimation filter, and a bandgap circuit is proposed. A method for the stabilization of a hig...A 16 bit stereo audio novel stability fifth-order ∑△ A/D converter that consists of switched capacitor ∑△ modulators, a decimation filter, and a bandgap circuit is proposed. A method for the stabilization of a high order single stage ∑△ modulator is also proposed. A new multistage comb filter is used for the front end decimation filter. The ∑△ A/D converter achieves a peak SNR of 96dB and a dynamic range of 96dB. The ADC was implemented in 0. 5μm 5V CMOS technology. The chip die area occupies only 4. 1mm × 2.4mm and dissipates 90mW.展开更多
The thermal stability, phase transformation, surface morphology, pore size distribution and permeation of the defect-free silica-zirconia membrane were investigated by using X-ray diffraction （XRD）, atomic force mic...The thermal stability, phase transformation, surface morphology, pore size distribution and permeation of the defect-free silica-zirconia membrane were investigated by using X-ray diffraction （XRD）, atomic force microscopy （AFM）, gas adsorption analyzer （BET）, and gas permeation apparatus, respectively. Using silica as the stabilizing agent, the defect-free membrane was much more stable than pure zirconia. The crystal transformation of zirconia in the silica-stabilized membrane could be prohibited by the interaction between silica and zireonia. ZrO2 crystals were kept tetragonal below 900℃, the size of which did not change with temperature between 700℃ and 900℃. It was further verified by the AFM observation, pore size analysis and permeation study. This thermal stability makes the silica-zirconia membrane a good choice as the intermediate layer for zeolite and Pd-based membranes.展开更多
In this paper we consider general nonlinear switching systems. Under an additional assumption, we prove that there exists a state space depending switching rule which stabilizes the system in a very general sense.
A method based on the wavelet transform is proposed for processing white light Interferograms from optical fiber interferometers.With this method,the envelope and the zero optical path difference(ZOPD) of white light ...A method based on the wavelet transform is proposed for processing white light Interferograms from optical fiber interferometers.With this method,the envelope and the zero optical path difference(ZOPD) of white light interferograms are obtained with high accuracy.The results agree well with those obtained by the method of center of gravity.Reasons for the insensitivity to noises of this method are discussed.The method is expected to be useful when processing white light interferograms from optical fiber interferometers,especially with low signal-to-noise ratio.展开更多
The atomistic mechanism for direct conversion of graphite to diamond is a long-standing problem in condensed matter physics. The newly identified cold-compressed graphite phases of M, W and 0 carbon provide a crucial ...The atomistic mechanism for direct conversion of graphite to diamond is a long-standing problem in condensed matter physics. The newly identified cold-compressed graphite phases of M, W and 0 carbon provide a crucial link to understand the graphite-to- diamond phase transformation. We demonstrate by ab initio calculations that pressure has a dual role in lowering the conversion barrier and enhancing the production stability during the first-stage cold-compressed phase conversion of graphite toward the intermediate metastable M, W and 0 carbon phases. However, it has little effect on the relative enthalpy and high conversion barrier during the second-stage conversion process toward the diamond polytypes, showing a temperature dominated conversion process. These results may give explanation regarding the necessity of high pressure and high temperature during the graphite-to- diamond reaction.展开更多
The purpose of this work is to investigate the asymptotic properties of a stochastic Gilpin--Ayala population system under regime switching on patches. We establish the global stability and the extinction of the trivi...The purpose of this work is to investigate the asymptotic properties of a stochastic Gilpin--Ayala population system under regime switching on patches. We establish the global stability and the extinction of the trivial equilibrium state of the model. Further- more, we show the existence of the stationary distribution for our system model. The analytical results are illustrated by computer simulations.展开更多
The stability of perovskite solar cells is an important issue to be addressed for future applications.Perovskite solar cells are vulnerable to exposure to UV light due to promoted chemical reactions.However, preventin...The stability of perovskite solar cells is an important issue to be addressed for future applications.Perovskite solar cells are vulnerable to exposure to UV light due to promoted chemical reactions.However, preventing UV light from entering solar cells lowers the power conversion efficiency by reducing the photocurrent. The challenge is to improve UV stability without sacrificing efficiency. Here, we demonstrate the reduction of UV light-related negative effects from the perspective of spectral modification. By simultaneously introducing UV–visible downshifting and light trapping, perovskite solar cells can achieve a comparable efficiency of over 21% to that of an unmodified device. The optimized device obtains increased UV stability due to UV–visible downshifting. Different from other strategies, spectral modification externally alters the composition of incident light and improves UV stability without changing the internal device architecture, which is broadly applicable to perovskite solar cells with different structures. The present work may also find applications in other types of solar cells to boost the stability of devices exposed to UV light.展开更多
文摘A 16 bit stereo audio novel stability fifth-order ∑△ A/D converter that consists of switched capacitor ∑△ modulators, a decimation filter, and a bandgap circuit is proposed. A method for the stabilization of a high order single stage ∑△ modulator is also proposed. A new multistage comb filter is used for the front end decimation filter. The ∑△ A/D converter achieves a peak SNR of 96dB and a dynamic range of 96dB. The ADC was implemented in 0. 5μm 5V CMOS technology. The chip die area occupies only 4. 1mm × 2.4mm and dissipates 90mW.
基金Supported by the National Natural Science Foundation of China (No.20476076).
文摘The thermal stability, phase transformation, surface morphology, pore size distribution and permeation of the defect-free silica-zirconia membrane were investigated by using X-ray diffraction （XRD）, atomic force microscopy （AFM）, gas adsorption analyzer （BET）, and gas permeation apparatus, respectively. Using silica as the stabilizing agent, the defect-free membrane was much more stable than pure zirconia. The crystal transformation of zirconia in the silica-stabilized membrane could be prohibited by the interaction between silica and zireonia. ZrO2 crystals were kept tetragonal below 900℃, the size of which did not change with temperature between 700℃ and 900℃. It was further verified by the AFM observation, pore size analysis and permeation study. This thermal stability makes the silica-zirconia membrane a good choice as the intermediate layer for zeolite and Pd-based membranes.
基金Supported by the NSF of Commission of Education of Henan Province(200510459002)
文摘In this paper we consider general nonlinear switching systems. Under an additional assumption, we prove that there exists a state space depending switching rule which stabilizes the system in a very general sense.
文摘A method based on the wavelet transform is proposed for processing white light Interferograms from optical fiber interferometers.With this method,the envelope and the zero optical path difference(ZOPD) of white light interferograms are obtained with high accuracy.The results agree well with those obtained by the method of center of gravity.Reasons for the insensitivity to noises of this method are discussed.The method is expected to be useful when processing white light interferograms from optical fiber interferometers,especially with low signal-to-noise ratio.
基金supported by the National Natural Science Foundation of China(Grant No.11274356)the Ministry of Environmental Protection of China(Grant Nos.200909086 and 201109037)
文摘The atomistic mechanism for direct conversion of graphite to diamond is a long-standing problem in condensed matter physics. The newly identified cold-compressed graphite phases of M, W and 0 carbon provide a crucial link to understand the graphite-to- diamond phase transformation. We demonstrate by ab initio calculations that pressure has a dual role in lowering the conversion barrier and enhancing the production stability during the first-stage cold-compressed phase conversion of graphite toward the intermediate metastable M, W and 0 carbon phases. However, it has little effect on the relative enthalpy and high conversion barrier during the second-stage conversion process toward the diamond polytypes, showing a temperature dominated conversion process. These results may give explanation regarding the necessity of high pressure and high temperature during the graphite-to- diamond reaction.
文摘The purpose of this work is to investigate the asymptotic properties of a stochastic Gilpin--Ayala population system under regime switching on patches. We establish the global stability and the extinction of the trivial equilibrium state of the model. Further- more, we show the existence of the stationary distribution for our system model. The analytical results are illustrated by computer simulations.
基金supported by the National Natural Science Foundation of China (52025028, 51972218)the 1000 Youth Talents Plan+2 种基金the 333 High-level Talents Cultivation Project of Jiangsu Provincethe Six Talents Peak Project of Jiangsu Provincethe Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions。
文摘The stability of perovskite solar cells is an important issue to be addressed for future applications.Perovskite solar cells are vulnerable to exposure to UV light due to promoted chemical reactions.However, preventing UV light from entering solar cells lowers the power conversion efficiency by reducing the photocurrent. The challenge is to improve UV stability without sacrificing efficiency. Here, we demonstrate the reduction of UV light-related negative effects from the perspective of spectral modification. By simultaneously introducing UV–visible downshifting and light trapping, perovskite solar cells can achieve a comparable efficiency of over 21% to that of an unmodified device. The optimized device obtains increased UV stability due to UV–visible downshifting. Different from other strategies, spectral modification externally alters the composition of incident light and improves UV stability without changing the internal device architecture, which is broadly applicable to perovskite solar cells with different structures. The present work may also find applications in other types of solar cells to boost the stability of devices exposed to UV light.
