A novel pancake Rogowski coil without magnetic core is introduced in this paper. Owing to its special pancake winding structure, the coil is of low self-resistance and high self-inductance, and thus has excellent low ...A novel pancake Rogowski coil without magnetic core is introduced in this paper. Owing to its special pancake winding structure, the coil is of low self-resistance and high self-inductance, and thus has excellent low frequency characteristic in the self-integral mode. Moreover, because of its unique installation method, the coil has a flexible sensitivity and can be applied under situations where toroidal air-core Rogowski coils or printed aircuit board （PCB） coils are not available. The parameters and performance of the pancake Rogowski coil are presented, and the principle of shielding is given. Measurements of step pulse current and oscillating pulse current by the coil are studied experimentally to illustrate its good linearity, reliable and flexible sensitivity and excellent frequency characteristic, especially its advantage in low frequency characteristic. The pancake Rogowski coil can be designed to assume round, square or rectangle shape, and has thus broad prospects in its application to the current measurement in such areas as plasma physics and pulsed power technology.展开更多
Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,...Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.展开更多
It＇s all about determination and persistence against the odds, befieves Zhang Ke. ＂You can realize your dreams as long as you persist,＂ says the 11-year-old. ＂You see, if the youngest brother had run away like his...It＇s all about determination and persistence against the odds, befieves Zhang Ke. ＂You can realize your dreams as long as you persist,＂ says the 11-year-old. ＂You see, if the youngest brother had run away like his elder brothers on that night, he would never have married the beautiful princess,＂ says the fifth-grader from Run＇an Public School in China＇s eastern Anhui Province.展开更多
In order to reveal the flavor characteristics of Chinese pancakes,the aroma and taste compounds of seven traditional Chinese pancakes were identified.The results showed that electronic nose(E-nose)analysis with PCA co...In order to reveal the flavor characteristics of Chinese pancakes,the aroma and taste compounds of seven traditional Chinese pancakes were identified.The results showed that electronic nose(E-nose)analysis with PCA could successfully distinguish the aroma profiles of seven Chinese pancakes;the principal components PC1 and PC2 represented 75.74%and 23.2%of the total variance(98.94%)respectively.Meanwhile,the discrimination index of taste profiles of seven Chinese pancakes based on electronic tongue(E-tongue)analysis with LDA was 99.32%;the discriminant factors DF1 and DF2 represented 94.99%and 4.33%of the total variance respectively.Furthermore,GC-MS results demonstrated that thirty-threeflavor compounds were identified in seven Chinese pancakes,including aldehydes,alcohols,alkanes,acids,and aromatics.Among the flavor components,aldehydes with ROAVs higher than 1 contributed most significantly to the overall aroma,such as(E,E)-2,4-nonadienal present the largest contribution in Qingzhou pancake,Jinan and Yishui pancake;hexanal present the largest contribution in Shenxian and Gaomi pancake;nonanal and benzeneacetaldehyde present the largest contribution in Linqu and Tai’an pancake,respectively.The umami and sweet taste amino acids were the most abundant in all the Chinese pancake samples,and Qingzhou pancake had relatively high amino acid content.The content of glucose was higher than maltose in Gaomi,Shenxian,and Tai’an pancakes,whereas the content of maltose was higher than glucose in Linqu,Qingzhou,Jinan,and Yishui pancakes.These results indicated that the aroma and taste profiles of Chinese pancakes differed significantly in terms of their flavor compound composition.The presented results could be beneficial for providing a comprehensive method for flavor profile identification of traditional whole-grain-based staples such as Chinese pancakes.展开更多
A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads t...A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.展开更多
In the strict sense, it is not very clear why with magnetic field increasing, the normal-superconductive (NS) transition becomes broad for Bi2Sr2CaCu208+δ(Bi2212) while the NS transitions are almost parallel for La19...In the strict sense, it is not very clear why with magnetic field increasing, the normal-superconductive (NS) transition becomes broad for Bi2Sr2CaCu208+δ(Bi2212) while the NS transitions are almost parallel for La193Sroo7Cu04+δ(La214). In this paper, R-T relations are measured by the six-probe method. We propose a moving mechanism of the pancake vortex and vortex line for Bi2212. The theoretical curves fit the experiment data well.展开更多
基金supported by Chinese National High Technology Research and Development Program(863 Program)(No.2008AA04Z408)
文摘A novel pancake Rogowski coil without magnetic core is introduced in this paper. Owing to its special pancake winding structure, the coil is of low self-resistance and high self-inductance, and thus has excellent low frequency characteristic in the self-integral mode. Moreover, because of its unique installation method, the coil has a flexible sensitivity and can be applied under situations where toroidal air-core Rogowski coils or printed aircuit board （PCB） coils are not available. The parameters and performance of the pancake Rogowski coil are presented, and the principle of shielding is given. Measurements of step pulse current and oscillating pulse current by the coil are studied experimentally to illustrate its good linearity, reliable and flexible sensitivity and excellent frequency characteristic, especially its advantage in low frequency characteristic. The pancake Rogowski coil can be designed to assume round, square or rectangle shape, and has thus broad prospects in its application to the current measurement in such areas as plasma physics and pulsed power technology.
基金the National Natural Science Foundation of China(Nos.11872195,11472120,and 11802036)the 111 Project(No.B14044)。
文摘Quench and mechanical behaviors are critical issues in high temperature superconducting(HTS)coils.In this paper,the quench characteristics in the rare earth barium copper oxide(REBCO)pancake coil at 4.2K are analyzed,and a two-dimensional(2D)axisymmetric electro-magneto-thermal model is presented.The effects of the constituent materials,background field,and coil size are analyzed.An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation.The variations of the temperature and strain in superconducting layers are compared.The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation.The possible damages are discussed with the consideration of the effects of the background field and coil size.It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused.
文摘It＇s all about determination and persistence against the odds, befieves Zhang Ke. ＂You can realize your dreams as long as you persist,＂ says the 11-year-old. ＂You see, if the youngest brother had run away like his elder brothers on that night, he would never have married the beautiful princess,＂ says the fifth-grader from Run＇an Public School in China＇s eastern Anhui Province.
基金supported by the Special Fund of the National Key Research and Development Program of China(Grant No.2017YFD0400103).
文摘In order to reveal the flavor characteristics of Chinese pancakes,the aroma and taste compounds of seven traditional Chinese pancakes were identified.The results showed that electronic nose(E-nose)analysis with PCA could successfully distinguish the aroma profiles of seven Chinese pancakes;the principal components PC1 and PC2 represented 75.74%and 23.2%of the total variance(98.94%)respectively.Meanwhile,the discrimination index of taste profiles of seven Chinese pancakes based on electronic tongue(E-tongue)analysis with LDA was 99.32%;the discriminant factors DF1 and DF2 represented 94.99%and 4.33%of the total variance respectively.Furthermore,GC-MS results demonstrated that thirty-threeflavor compounds were identified in seven Chinese pancakes,including aldehydes,alcohols,alkanes,acids,and aromatics.Among the flavor components,aldehydes with ROAVs higher than 1 contributed most significantly to the overall aroma,such as(E,E)-2,4-nonadienal present the largest contribution in Qingzhou pancake,Jinan and Yishui pancake;hexanal present the largest contribution in Shenxian and Gaomi pancake;nonanal and benzeneacetaldehyde present the largest contribution in Linqu and Tai’an pancake,respectively.The umami and sweet taste amino acids were the most abundant in all the Chinese pancake samples,and Qingzhou pancake had relatively high amino acid content.The content of glucose was higher than maltose in Gaomi,Shenxian,and Tai’an pancakes,whereas the content of maltose was higher than glucose in Linqu,Qingzhou,Jinan,and Yishui pancakes.These results indicated that the aroma and taste profiles of Chinese pancakes differed significantly in terms of their flavor compound composition.The presented results could be beneficial for providing a comprehensive method for flavor profile identification of traditional whole-grain-based staples such as Chinese pancakes.
文摘A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.
基金the National Natural Science Foundation of China(Grant No.10334090)the Ministry of Science and Technology of China(GrantNo.NKBRSF-G19990646)
文摘In the strict sense, it is not very clear why with magnetic field increasing, the normal-superconductive (NS) transition becomes broad for Bi2Sr2CaCu208+δ(Bi2212) while the NS transitions are almost parallel for La193Sroo7Cu04+δ(La214). In this paper, R-T relations are measured by the six-probe method. We propose a moving mechanism of the pancake vortex and vortex line for Bi2212. The theoretical curves fit the experiment data well.
