In the global climate system, the polar regions are sensitive indicators of climate change, in which sea ice plays an important role. Satellite remote sensing is a significant tool for monitoring sea ice. The use of s...In the global climate system, the polar regions are sensitive indicators of climate change, in which sea ice plays an important role. Satellite remote sensing is a significant tool for monitoring sea ice. The use of synthetic aperture radar(SAR) images to distinguish sea ice from sea water is one of the current research hotspots in this topic. To distinguish sea ice from the open sea, the polarization ratio characteristics of sea ice and sea water are studied for L-band and C-band radars, based on an electromagnetic scattering model of sea ice derived from the integral equation method(IEM) and the radiative transfer(RT) model. Numerical experiments are carried out based on the model and the results are given as follows. For L-band, the polarization ratio for sea water depends only on the incident angle, while the polarization ratio for sea ice is related to the incident angle and the ice thickness. For C-band, the sea water polarization ratio is influenced by the incident angle and the root mean square(RMS) height of the sea surface. For C-band, for small to medium incident angles,the polarization ratio for bare sea ice is mainly determined by the incident angle and ice thickness. When the incident angle increases, the RMS height will also affect the polarization ratio for bare sea ice. If snow covers the sea ice, then the polarization ratio for sea ice decreases and is affected by the RMS height of snow surface, snow thickness, volume fraction and the radius of scatterers. The results show that the sea ice and the open sea can be distinguished by using either L-band or C-band radar according to their polarization ratio difference. However, the ability of L-band to make this differentiation is higher than that of C-band.展开更多
The intrinsic product polarization and intramolecular isotope effect of the S（~1D,~3P） ＋ HD reaction have been investigated on both the lowest singlet state（1A） and the triplet state（3A and 3A） potential energy...The intrinsic product polarization and intramolecular isotope effect of the S（~1D,~3P） ＋ HD reaction have been investigated on both the lowest singlet state（1A） and the triplet state（3A and 3A） potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P（θr） distributions,P（φ r） distributions,and polarization-dependent differential cross sections（PDDCSs）（00） are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.展开更多
A breaking wave can exert a great influence on the electromagnetic（EM） scattering result from sea surfaces. In this paper, the process of small-scale wave breaking is simulated by the commercial computational fluid ...A breaking wave can exert a great influence on the electromagnetic（EM） scattering result from sea surfaces. In this paper, the process of small-scale wave breaking is simulated by the commercial computational fluid dynamics（CFD）software FLUENT, and the backscattering radar cross section（RCS） of the turbulence structure after breaking is calculated with the method of moments. The scattering results can reflect the turbulent intensities of the wave profiles and can indicate high polarization ratios at moderate incident angles, which should be attributed to the incoherent backscatter from surface disturbance of turbulence structure. Compared with the wave profile before breaking, the turbulence structure has no obvious geometrical characteristic of a plunging breaker, and no sea spikes are present at large incident angles either.In summary, the study of EM scattering from turbulence structure can provide a basis to explain the anomalies of EM scattering from sea surfaces and help us understand the scattering mechanism about the breaking wave more completely.展开更多
The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique base...The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique based on Faraday modulation combined with the optical differential method to measure an extremely small polari- zation rotation angle with high sensitivity. The theoretical and experimental results show that common mode noise is reduced appreciably and signal to noise ratio is enhanced. The effectiveness of this technique has been demonstrated by measuring the Verdet constant of terbium gallium garnet glass and measuring the small polari- zation rotation angle. A sensitivity of enhancement of one order of magnitude has been achieved using differ- ential detection based on Faraday modulation.展开更多
An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge character...An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge characteristics in these areas were compared with the charging state in Ansan,South Korea,located in the midlatitude,where artificial factors,such as human activity,urbanization,and traffic,might result in a higher total concentration.Furthermore,in Ansan,South Korea,the charged-particle polarity ratio was very stable and was close to 1.However,notably different particle charge characteristics were obtained in the Antarctic and Arctic regions.The imbalance between the numbers of positively and negatively charged particles was evident,resulting in more positive charges on the atmospheric particles.On average,the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher,respectively,compared with the negatively charged particles.The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.展开更多
We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller.The overall size of the dynamic polarization controller on chip is 2.830 mm × 0.210 mm × 1 mm.The mo...We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller.The overall size of the dynamic polarization controller on chip is 2.830 mm × 0.210 mm × 1 mm.The modulation bandwidth is 30 kHz.By using a variable step simulated annealing approach,we achieve a dynamic polarization extinction ratio greater than 25 dB.A numerical simulation method was used to optimize the relevant parameters of the dynamic polarization controller.It is expected that the dynamic polarization controller can be utilized in fiber communication systems or silicon photonics integrated quantum communication systems to minimize the size and decrease the cost further.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFC1401007)the Global Change Research Program of China(Grant No.2015CB953901)+1 种基金the National Natural Science Foundation of China(Grant No.41776181)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX18 1012)
文摘In the global climate system, the polar regions are sensitive indicators of climate change, in which sea ice plays an important role. Satellite remote sensing is a significant tool for monitoring sea ice. The use of synthetic aperture radar(SAR) images to distinguish sea ice from sea water is one of the current research hotspots in this topic. To distinguish sea ice from the open sea, the polarization ratio characteristics of sea ice and sea water are studied for L-band and C-band radars, based on an electromagnetic scattering model of sea ice derived from the integral equation method(IEM) and the radiative transfer(RT) model. Numerical experiments are carried out based on the model and the results are given as follows. For L-band, the polarization ratio for sea water depends only on the incident angle, while the polarization ratio for sea ice is related to the incident angle and the ice thickness. For C-band, the sea water polarization ratio is influenced by the incident angle and the root mean square(RMS) height of the sea surface. For C-band, for small to medium incident angles,the polarization ratio for bare sea ice is mainly determined by the incident angle and ice thickness. When the incident angle increases, the RMS height will also affect the polarization ratio for bare sea ice. If snow covers the sea ice, then the polarization ratio for sea ice decreases and is affected by the RMS height of snow surface, snow thickness, volume fraction and the radius of scatterers. The results show that the sea ice and the open sea can be distinguished by using either L-band or C-band radar according to their polarization ratio difference. However, the ability of L-band to make this differentiation is higher than that of C-band.
文摘The intrinsic product polarization and intramolecular isotope effect of the S（~1D,~3P） ＋ HD reaction have been investigated on both the lowest singlet state（1A） and the triplet state（3A and 3A） potential energy surfaces by using quasi-classical trajectory and quantum mechanical methods.The calculations indicate that intramolecular isotope effects are different on the three electronic states.The stereodynamics study shows that the P（θr） distributions,P（φ r） distributions,and polarization-dependent differential cross sections（PDDCSs）（00） are sensitive to mass factor and the product angular momentum vectors are not only aligned but also oriented.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61372004 and 41306188)the Fundamental Research Funds for the Central Universities,China(Grant No.K 5051207015)the Foundation of the Science and Technology on Electromagnetic Scattering Laboratory,China(Grant No.HX0113071414)
文摘A breaking wave can exert a great influence on the electromagnetic（EM） scattering result from sea surfaces. In this paper, the process of small-scale wave breaking is simulated by the commercial computational fluid dynamics（CFD）software FLUENT, and the backscattering radar cross section（RCS） of the turbulence structure after breaking is calculated with the method of moments. The scattering results can reflect the turbulent intensities of the wave profiles and can indicate high polarization ratios at moderate incident angles, which should be attributed to the incoherent backscatter from surface disturbance of turbulence structure. Compared with the wave profile before breaking, the turbulence structure has no obvious geometrical characteristic of a plunging breaker, and no sea spikes are present at large incident angles either.In summary, the study of EM scattering from turbulence structure can provide a basis to explain the anomalies of EM scattering from sea surfaces and help us understand the scattering mechanism about the breaking wave more completely.
基金supported by the National Key R&D Program of China(No.2017YFB0503100)the National Science Foundation of China(NSFC)(No.61227902)
文摘The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique based on Faraday modulation combined with the optical differential method to measure an extremely small polari- zation rotation angle with high sensitivity. The theoretical and experimental results show that common mode noise is reduced appreciably and signal to noise ratio is enhanced. The effectiveness of this technique has been demonstrated by measuring the Verdet constant of terbium gallium garnet glass and measuring the small polari- zation rotation angle. A sensitivity of enhancement of one order of magnitude has been achieved using differ- ential detection based on Faraday modulation.
基金supported by the research fund of Hanyang University(HY-2019-P).
文摘An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge characteristics in these areas were compared with the charging state in Ansan,South Korea,located in the midlatitude,where artificial factors,such as human activity,urbanization,and traffic,might result in a higher total concentration.Furthermore,in Ansan,South Korea,the charged-particle polarity ratio was very stable and was close to 1.However,notably different particle charge characteristics were obtained in the Antarctic and Arctic regions.The imbalance between the numbers of positively and negatively charged particles was evident,resulting in more positive charges on the atmospheric particles.On average,the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher,respectively,compared with the negatively charged particles.The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.
基金This work was supported by the Aeronautical Science Foundation of China(No.20200020115001)National Natural Science Foundation of China(No.62175138)+1 种基金Key Research and Development Program of Guangdong Province(No.2020B0303040002),Shanxi 1331KSCOpen Project of the State Key Laboratory of Quantum Optics and Quantum Optics Devices of Shanxi University(No.KF202006).
文摘We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller.The overall size of the dynamic polarization controller on chip is 2.830 mm × 0.210 mm × 1 mm.The modulation bandwidth is 30 kHz.By using a variable step simulated annealing approach,we achieve a dynamic polarization extinction ratio greater than 25 dB.A numerical simulation method was used to optimize the relevant parameters of the dynamic polarization controller.It is expected that the dynamic polarization controller can be utilized in fiber communication systems or silicon photonics integrated quantum communication systems to minimize the size and decrease the cost further.
