On the basis of high precision requirement for input signals in the power system protection and control system,this paper,only for the influence of power system frequency deviation on extracting fundamental harmonic,s...On the basis of high precision requirement for input signals in the power system protection and control system,this paper,only for the influence of power system frequency deviation on extracting fundamental harmonic,studies the amplitude error of Fourier algorithm,presents a method of correcting frequency deviation,and further derives the formulas of improved Fourier algorithm.The simulation results verified the effectiveness of the algorithm,it not only can greatly weaken the influence of frequency deviation,but also increase the precision of the power system protection and control.As a result the study in this paper has practical application value.展开更多
In this paper, a weighted fractional Fourier transform(WFRFT) based cooperative overlay system, aiming to guarantee physical layer(PHY) security, is proposed. The paper elaborates how WFRFT and physical layer properti...In this paper, a weighted fractional Fourier transform(WFRFT) based cooperative overlay system, aiming to guarantee physical layer(PHY) security, is proposed. The paper elaborates how WFRFT and physical layer properties of the wireless medium are collaborated to guarantee the secrecy of wireless transmissions. In the proposed system, WFRFT is first preform on the secret data, such that the transmitted signal is distorted and can only be neutralized by inverse-WFRFT with the same parameter. And then two streams of the transformed sequences that bearing different messages are cooperatively and simultaneously transmitted to two legitimate receivers via a beamforming-liked method, respectively. In general, both the rapid spatial decorrelation property and the inherent security features of WFRFT are leveraged, such that only the eavesdropper's is degraded, and hence, the wireless communication secrecy is reliably guaranteed. Numerical simulations are conducted to evaluate the performance of the proposed system in terms of the average bit error rate and the secrecy capacity.展开更多
The aim of this study is to examine and present the results of the scientific examinations carried out on the ground layers with paint samples collected from the decorated surfaces of the wooden coffin dated back to t...The aim of this study is to examine and present the results of the scientific examinations carried out on the ground layers with paint samples collected from the decorated surfaces of the wooden coffin dated back to the late period from Saqqara excavation that belonged to the Ministry of Antiquities. Many analytical methods were performed as optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray analysis （ESEM-EDX）, X-ray diffraction analysis as well as fourier transform infrared spectroscopy have been used to both characterise the inorganic composition and the binding media used. The analytical results showed that the materials composition and technique used to plaster applied on the wooden surface are in good agreement with the information gathered through the historical survey. The coffin was in bad and poor condition. There was cracking on the surface and in the structure, serious flaking, cupping of some pigments and serious damage in both the wooden support and gesso layer. Conservation treatment processes carried out included consolidation of lifting areas of the paint film, disturbing restoration materials, repair of cracks in the wooden support and a dry surface cleaning of the pigments.展开更多
A series of symmetrical peptidomimetics （3-8） based on cysteine-modified cyclo（L-Lys-L-Lys）s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl （Fmoc）...A series of symmetrical peptidomimetics （3-8） based on cysteine-modified cyclo（L-Lys-L-Lys）s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl （Fmoc） and triphenylmethyl （Trt） protecting groups and the exchange of thiol-to-disulfide as well. The peptidomimetics holding Trt （3 and 4） showed no gel performance, while the Fmoc groups promoted 5 and 6 to give rise to thermo-reversible organogels in a number of organic solvents. The self-assembled fibrillar networks were distinctly evidenced in the organogels by transmission electron micros- copy （TEM） and scanning electron microscopy （SEM） observations. Fourier transform infrared spectroscopy （FT-IR） and fluorescence analyses revealed that the hydrogen bonding and ^-rt stacking play as major driving forces for the self-assembly of these organogelators. A 13-turn secondary structure was deduced for the organogel of 6 by virtue of X-ray diffraction, FT-IR and circular dichroism （CD） measurements, and an interdigitated bilayer structure was also presented.展开更多
文摘On the basis of high precision requirement for input signals in the power system protection and control system,this paper,only for the influence of power system frequency deviation on extracting fundamental harmonic,studies the amplitude error of Fourier algorithm,presents a method of correcting frequency deviation,and further derives the formulas of improved Fourier algorithm.The simulation results verified the effectiveness of the algorithm,it not only can greatly weaken the influence of frequency deviation,but also increase the precision of the power system protection and control.As a result the study in this paper has practical application value.
基金supported by the National Basic Research Program of China under Grant 2013CB329003the National Natural Science Founda-tion General Program of China under Grant 61171110
文摘In this paper, a weighted fractional Fourier transform(WFRFT) based cooperative overlay system, aiming to guarantee physical layer(PHY) security, is proposed. The paper elaborates how WFRFT and physical layer properties of the wireless medium are collaborated to guarantee the secrecy of wireless transmissions. In the proposed system, WFRFT is first preform on the secret data, such that the transmitted signal is distorted and can only be neutralized by inverse-WFRFT with the same parameter. And then two streams of the transformed sequences that bearing different messages are cooperatively and simultaneously transmitted to two legitimate receivers via a beamforming-liked method, respectively. In general, both the rapid spatial decorrelation property and the inherent security features of WFRFT are leveraged, such that only the eavesdropper's is degraded, and hence, the wireless communication secrecy is reliably guaranteed. Numerical simulations are conducted to evaluate the performance of the proposed system in terms of the average bit error rate and the secrecy capacity.
文摘The aim of this study is to examine and present the results of the scientific examinations carried out on the ground layers with paint samples collected from the decorated surfaces of the wooden coffin dated back to the late period from Saqqara excavation that belonged to the Ministry of Antiquities. Many analytical methods were performed as optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray analysis （ESEM-EDX）, X-ray diffraction analysis as well as fourier transform infrared spectroscopy have been used to both characterise the inorganic composition and the binding media used. The analytical results showed that the materials composition and technique used to plaster applied on the wooden surface are in good agreement with the information gathered through the historical survey. The coffin was in bad and poor condition. There was cracking on the surface and in the structure, serious flaking, cupping of some pigments and serious damage in both the wooden support and gesso layer. Conservation treatment processes carried out included consolidation of lifting areas of the paint film, disturbing restoration materials, repair of cracks in the wooden support and a dry surface cleaning of the pigments.
基金the National Natural Science Foundation of China (21174018)
文摘A series of symmetrical peptidomimetics （3-8） based on cysteine-modified cyclo（L-Lys-L-Lys）s were synthesized, and their gelation capability in organic solvents was dominated by fluorenylmethyloxycarbonyl （Fmoc） and triphenylmethyl （Trt） protecting groups and the exchange of thiol-to-disulfide as well. The peptidomimetics holding Trt （3 and 4） showed no gel performance, while the Fmoc groups promoted 5 and 6 to give rise to thermo-reversible organogels in a number of organic solvents. The self-assembled fibrillar networks were distinctly evidenced in the organogels by transmission electron micros- copy （TEM） and scanning electron microscopy （SEM） observations. Fourier transform infrared spectroscopy （FT-IR） and fluorescence analyses revealed that the hydrogen bonding and ^-rt stacking play as major driving forces for the self-assembly of these organogelators. A 13-turn secondary structure was deduced for the organogel of 6 by virtue of X-ray diffraction, FT-IR and circular dichroism （CD） measurements, and an interdigitated bilayer structure was also presented.
