Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eig...Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eigenfrequency, trajectory, velocity and the time for a magnetic vortex to obtain the steady gyration are analyzed. Simulation results reveal that the magnetic vortices in larger and thinner nanodisks can achieve a lower-frequency gyration at a lower current density in a shorter time. However, the magnetic vortices in thicker nanodisks need a higher current density and longer time to attain steady gyration but with a higher eigenfrequency. We also find that the point-contact position exerts different influences on these parameters in different nanodisks, which contributes to the control of the magnetic vortex gyration. The conclusions of this paper can serve as a theoretical basis for designing nano-oscillators and microwave frequency modulators.展开更多
Pulsed breakdown of dry air at ambient pressure has been investigated in the point-plane geometry, using repetitive nanosecond pulses with 10 ns risetime, 20-30 ns duration, and up to 100 kV amplitude. A major concern...Pulsed breakdown of dry air at ambient pressure has been investigated in the point-plane geometry, using repetitive nanosecond pulses with 10 ns risetime, 20-30 ns duration, and up to 100 kV amplitude. A major concern in this paper is to study the dependence of breakdown strength on the point-electrode polarity. Applied voltage, breakdown current and repetitive stressing time are measured under the experimental conditions of some variables including pulse voltage peak, gap spacing and repetition rate. The results show that increasing the E-field strength can decrease breakdown time lag, repetitive stressing time and the number of applied pulses as expected. However, compared with the traditional polarity dependence it is weakened and not significant in the repetitive nanosecond-pulse breakdown. The ambiguous polarity dependence in the experimental study is involved with an accumulation effect of residual charges and metastable states. Moreover, it is suggested that the reactions associated with the detachment of negative ions and impact deactivation of metastable species could provide a source of primary initiating electrons for breakdown.展开更多
Some algorithms of feature extraction in existing literature studied for image processing was the gray image with one-dimensional parameter. However, some feature points’ extraction for three-dimensional color of pol...Some algorithms of feature extraction in existing literature studied for image processing was the gray image with one-dimensional parameter. However, some feature points’ extraction for three-dimensional color of polar image, such as the color edge extraction, inflection points, and so on, was urgently to be solved a polar color problem. For achieving quickly and accurately the color feature extraction to polar image, this paper proposed a similar region of color algorithm. The algorithm was compared to polar image, and the effect to color extraction was also described by the combination of the proposed and existing algorithms. Moreover, this paper gave the comparison of the proposed algorithm and an existing classical algorithm to extraction of color feature. These researches in this paper provided a powerful tool for polar image classification, color feature segmentation, precise recognition, and so on.展开更多
Suppose A,B and C are the bounded linear operators on a Hilbert space H, when A has a generalized inverse A - such that (AA -) *=AA - and B has a generalized inverse B - such that (B -B) *=B -B,the general cha...Suppose A,B and C are the bounded linear operators on a Hilbert space H, when A has a generalized inverse A - such that (AA -) *=AA - and B has a generalized inverse B - such that (B -B) *=B -B,the general characteristic forms for the critical points of the map F p:X→‖ A X B-C ‖ p p (1<p<∞), have been obtained, it is a generalization for P J Maher's result about p=2. Similarly, the same question has been discussed for several operators.展开更多
Let W^-（t）（t∈R＋^N） be the d-dimensional N-parameter generalized Brownian sheet. We study the polar sets for W^-（t）. It is proved that for any α∈ R^d, P{W^-（t） = α, for some t∈ R〉^N} = {1, if βd 〈 2N ...Let W^-（t）（t∈R＋^N） be the d-dimensional N-parameter generalized Brownian sheet. We study the polar sets for W^-（t）. It is proved that for any α∈ R^d, P{W^-（t） = α, for some t∈ R〉^N} = {1, if βd 〈 2N ,0 if αd〉 2N and the probability that W^-（t） has k-multiple points is 1 or 0 according as whether 2kN〉d（k-1）β or 2kN 〈 d（k - 1）α. These results contain and extend the results of the Brownian sheet, where R〉^N = （0,＋∞）U,R＋^N = [0,＋∞）^N,0〈 α ≤1and β〉1.展开更多
为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自...为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自卷积窗的快速傅里叶计算方法对不同类型的电缆阻抗失配点进行定位。其次,提出电缆阻抗失配点时频脉冲转换算法,利用高斯窄带包络信号良好的频段调节能力和时频特性,详细阐述了时频脉冲的参数设计和极性判断方法。之后,运用仿真,对不同类型的阻抗失配点进行时频脉冲转换,验证了该算法的有效性。最后,采用该算法对实验室含接头长1500m的10k V XLPE电缆进行实验验证。仿真和实验结果表明:时频脉冲转换算法可以有效地定位长电缆阻抗失配点并且实现不同类型阻抗失配点的极性识别;同时,不同长度电缆阻抗失配点的时频脉冲转换结果不受低频段数据缺失占比的影响,有效提高了长电缆阻抗失配点的极性识别率。展开更多
The author summarized the physiological activity of carrageenan,——antioxidant,antiviral and anti coagulation.The article compared and analysed three methods of decomposing carrageenan to carrageenan oligosaccharides...The author summarized the physiological activity of carrageenan,——antioxidant,antiviral and anti coagulation.The article compared and analysed three methods of decomposing carrageenan to carrageenan oligosaccharides.And it emphatically pointed out that biological enzyme method is better than chemical method and physical method on degradation of carrageenan and its good application prospect.?In addition,the article clarified the possibility of obtaining new carrageenase from Polar microorganisms from the special biological environment,the microorganisms’special physical and chemical characteristics and so on.In order to provide reference for the search of the industrial production of carrageenan oligosaccharides by enzymatic degradation.展开更多
Long period fiber gratings are emerging as a potential candidate in the list of surrounding refractive index optical fiber sensors. Their sensitivity can be enhanced greatly if the grating period, fiber dimensions and...Long period fiber gratings are emerging as a potential candidate in the list of surrounding refractive index optical fiber sensors. Their sensitivity can be enhanced greatly if the grating period, fiber dimensions and surrounding refractive index are optimized in a way to operate at a point called turn around point on phase matching curves of these gratings. Turn around point LPFGs are well known for their ultrahigh sensitivity to external parameters. Potential of operating LPFG at or near turn around point has been investigated by many researchers in various applications including physical parameter sensing, adulteration detection, radiation dose, etc. Since TAP LPFGs are in investigation phase therefore a lot of rigorous & efficient work in finding techniques for optimizing their potential as sensor in chemical, biochemical, structural health monitoring is still to be carried out. A brief review of work carried out in this domain till now is presented here and key findings from literature review are highlighted.展开更多
基金Project supported by the Thirteenth Five-Year Program for Science and Technology of Education Department of Jilin Province,China(Grant No.JJKH20191007KJ)the Program for Development of Science and Technology of Siping City,China(Grant No.2016063)
文摘Micromagnetic simulation is employed to study the gyration motion of magnetic vortices in distinct permalloy nanodisks driven by a spin-polarized current. The critical current density for magnetic vortex gyration, eigenfrequency, trajectory, velocity and the time for a magnetic vortex to obtain the steady gyration are analyzed. Simulation results reveal that the magnetic vortices in larger and thinner nanodisks can achieve a lower-frequency gyration at a lower current density in a shorter time. However, the magnetic vortices in thicker nanodisks need a higher current density and longer time to attain steady gyration but with a higher eigenfrequency. We also find that the point-contact position exerts different influences on these parameters in different nanodisks, which contributes to the control of the magnetic vortex gyration. The conclusions of this paper can serve as a theoretical basis for designing nano-oscillators and microwave frequency modulators.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 50207011 and 50437020）.
文摘Pulsed breakdown of dry air at ambient pressure has been investigated in the point-plane geometry, using repetitive nanosecond pulses with 10 ns risetime, 20-30 ns duration, and up to 100 kV amplitude. A major concern in this paper is to study the dependence of breakdown strength on the point-electrode polarity. Applied voltage, breakdown current and repetitive stressing time are measured under the experimental conditions of some variables including pulse voltage peak, gap spacing and repetition rate. The results show that increasing the E-field strength can decrease breakdown time lag, repetitive stressing time and the number of applied pulses as expected. However, compared with the traditional polarity dependence it is weakened and not significant in the repetitive nanosecond-pulse breakdown. The ambiguous polarity dependence in the experimental study is involved with an accumulation effect of residual charges and metastable states. Moreover, it is suggested that the reactions associated with the detachment of negative ions and impact deactivation of metastable species could provide a source of primary initiating electrons for breakdown.
文摘Some algorithms of feature extraction in existing literature studied for image processing was the gray image with one-dimensional parameter. However, some feature points’ extraction for three-dimensional color of polar image, such as the color edge extraction, inflection points, and so on, was urgently to be solved a polar color problem. For achieving quickly and accurately the color feature extraction to polar image, this paper proposed a similar region of color algorithm. The algorithm was compared to polar image, and the effect to color extraction was also described by the combination of the proposed and existing algorithms. Moreover, this paper gave the comparison of the proposed algorithm and an existing classical algorithm to extraction of color feature. These researches in this paper provided a powerful tool for polar image classification, color feature segmentation, precise recognition, and so on.
文摘Suppose A,B and C are the bounded linear operators on a Hilbert space H, when A has a generalized inverse A - such that (AA -) *=AA - and B has a generalized inverse B - such that (B -B) *=B -B,the general characteristic forms for the critical points of the map F p:X→‖ A X B-C ‖ p p (1<p<∞), have been obtained, it is a generalization for P J Maher's result about p=2. Similarly, the same question has been discussed for several operators.
基金the National Natural Science Foundation of China (10471148)the Natural Science Foundation of Shaanxi Province (2005A08, 2006A14)
文摘Let W^-（t）（t∈R＋^N） be the d-dimensional N-parameter generalized Brownian sheet. We study the polar sets for W^-（t）. It is proved that for any α∈ R^d, P{W^-（t） = α, for some t∈ R〉^N} = {1, if βd 〈 2N ,0 if αd〉 2N and the probability that W^-（t） has k-multiple points is 1 or 0 according as whether 2kN〉d（k-1）β or 2kN 〈 d（k - 1）α. These results contain and extend the results of the Brownian sheet, where R〉^N = （0,＋∞）U,R＋^N = [0,＋∞）^N,0〈 α ≤1and β〉1.
文摘为解决采用频域反射技术进行长电缆缺陷检测时,其结果易受低频段数据缺失占比的影响,而难以判断电缆缺陷极性的问题,该文提出一种基于频域反射技术的电缆阻抗失配点时频脉冲转换算法以实现缺陷的定位和极性判别。首先,采用2阶Nuttall自卷积窗的快速傅里叶计算方法对不同类型的电缆阻抗失配点进行定位。其次,提出电缆阻抗失配点时频脉冲转换算法,利用高斯窄带包络信号良好的频段调节能力和时频特性,详细阐述了时频脉冲的参数设计和极性判断方法。之后,运用仿真,对不同类型的阻抗失配点进行时频脉冲转换,验证了该算法的有效性。最后,采用该算法对实验室含接头长1500m的10k V XLPE电缆进行实验验证。仿真和实验结果表明:时频脉冲转换算法可以有效地定位长电缆阻抗失配点并且实现不同类型阻抗失配点的极性识别;同时,不同长度电缆阻抗失配点的时频脉冲转换结果不受低频段数据缺失占比的影响,有效提高了长电缆阻抗失配点的极性识别率。
基金funded by the State Oceanic Administration of Marine Bioactive Substances and Modern Analytical Technology Key Laboratory(MBSMAT-2015-01)
文摘The author summarized the physiological activity of carrageenan,——antioxidant,antiviral and anti coagulation.The article compared and analysed three methods of decomposing carrageenan to carrageenan oligosaccharides.And it emphatically pointed out that biological enzyme method is better than chemical method and physical method on degradation of carrageenan and its good application prospect.?In addition,the article clarified the possibility of obtaining new carrageenase from Polar microorganisms from the special biological environment,the microorganisms’special physical and chemical characteristics and so on.In order to provide reference for the search of the industrial production of carrageenan oligosaccharides by enzymatic degradation.
文摘Long period fiber gratings are emerging as a potential candidate in the list of surrounding refractive index optical fiber sensors. Their sensitivity can be enhanced greatly if the grating period, fiber dimensions and surrounding refractive index are optimized in a way to operate at a point called turn around point on phase matching curves of these gratings. Turn around point LPFGs are well known for their ultrahigh sensitivity to external parameters. Potential of operating LPFG at or near turn around point has been investigated by many researchers in various applications including physical parameter sensing, adulteration detection, radiation dose, etc. Since TAP LPFGs are in investigation phase therefore a lot of rigorous & efficient work in finding techniques for optimizing their potential as sensor in chemical, biochemical, structural health monitoring is still to be carried out. A brief review of work carried out in this domain till now is presented here and key findings from literature review are highlighted.
