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Geometrical optics approximation of light scattering by large air bubbles

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Particuology 2008年第5期6卷 340-346页

作者： Haitao Yu jianqi shen Yuehuan Wei University of Shanghai for Science and Technology Shanghai 200093 China

For large spherical bubbles in water, geometrical optics approximation is considered a better method for calculating light scattering patterns. In this paper, the basic theory of geometrical optics approximation is clarified. The change of phase for bubbles is calculated when total reflection occurs, which is different from particles with relative refractive indices larger than 1. Verification of the method was achieved by assuming a spherical particle and comparing present results to Mie scattering and Debye calculation. Agreement with the Mie theory was excellent in all directions when the dimensionless size parameter is larger than 50. Limitations of the geometrical optics approximation are also discussed.

关键词： Geometrical optics approximation Light scattering Total reflection

Inclusion of the tunneling phase shift for interferometric particle imaging for bubble sizing

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Particuology 2021年第1期19卷 50-57页

作者： Xiang Liu jianqi shen Peng Gong Haitao Yu College of Science University of Shanghai for Science and TechnologyShanghai 200093China

The interferometric particle imaging technique makes use of the angular oscillations of the scattered light in the forward direction for droplet or bubble *** out-of-focus image consists of fringes,the spacing of which reflects the interference between the surface-reflected light and the twofold-refracted *** internal reflection occurs when the incident light hits the bubble at a large incident *** tunneling phase shift is not included in the geometric optics approximation,which leads to a deviation from Mie *** this work,we modified the formula for describing the fringe spacing by including the tunneling phase shift of total internal *** analysis and experiments showed that the modification is effective for the measurement of bubbles smaller than 60μm.

关键词： Interferometric particle imaging Bubbles Total internal reflection Tunneling phase shift

Improved algorithm of light scattering by a coated sphere

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China Particuology 2007年第3期5卷 230-236页

作者： Lei Liu Huarui Wang Bin Yu Yamin Xu jianqi shen Institute of Science University of Shanghai for Science and Technology Shanghai 200093 China School of Mathematics and Physics Anhui University of Technology Ma'anshan 243002 China College of Physics and Electronic Engineering Xuzhou Normal University Xuzhou 221116 China

An efficient numerical algorithm for computing the light scattering by a coated sphere is proposed. The calculation of relevant functions by different recurrence algorithms is discussed. The new algorithm avoids the numerical difficulties, which give rise to significant errors encountered in practice by prior methods. Exemplifying results such as extinction efficiency, scattering efficiency, light scattering intensity as well as calculation speed are provided. The results show that this algorithm is efficient, fast, numerically stable and accurate. 2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.

关键词： Coated sphere Scattering Algorithm Calculation

透过率起伏相关频谱法测量两相流场中颗粒速度、粒径分布和体积分数

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中国激光 2022年第23期49卷 98-108页

作者：龚鹏沈建琪上海理工大学理学院上海200093

两相流中颗粒的运动速度、粒径分布和体积分数是非常重要的参数。本文介绍了一种基于透过率起伏相关频谱测试技术的光学测量装置,并采用该装置实现了颗粒运动速度、粒径分布和体积分数的同时测量。该测试装置具有结构简单、易实现和便... 详细信息

两相流中颗粒的运动速度、粒径分布和体积分数是非常重要的参数。本文介绍了一种基于透过率起伏相关频谱测试技术的光学测量装置,并采用该装置实现了颗粒运动速度、粒径分布和体积分数的同时测量。该测试装置具有结构简单、易实现和便于安装维护等特点,有望应用于两相流的在线实时测量。实验结果与标称直径、其他测量方法所得结果相符并具有较好的重复性,证明了测试装置的可行性。

关键词：测量两相流透过率起伏相关频谱颗粒粒径分布

Optimization of regularization parameter of inversion in particle sizing using light extinction method

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China Particuology 2007年第4期5卷 295-299页

作者： Mingxu Su Feng Xu Xiaoshu Cai Kuanfang Ren jianqi shen Institute of Particle and Two Phase Flow Measurement Technology University of Shanghai .for Science and Technology Shanghai 200093 China LESP UMR6614/CORIA CNRS-Universite France INSA de Rouen 76801 France

In particle sizing by light extinction method, the regularization parameter plays an important role in applying regularization to find the solution to ill-posed inverse problems. We combine the generalized cross-validation （GCV） and L-curve criteria with the Twomey-NNLS algorithm in parameter optimization. Numerical simulation and experimental validation show that the resistance of the newly developed algorithms to measurement errors can be improved leading to stable inversion results for unimodal particle size distribution.

关键词： Particle size analysis Light extinction Inversion algorithm Regularization parameter

A NEW ALGORITHM OF RELAXATION METHOD FOR PARTICLE ANALYSIS FROM FORWARD SCATTERED LIGHT

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China Particuology 2006年第1期4卷 13-19页

作者： jianqi shen Mingxu Su Junfeng Li University of Shanghai for Science and Technology Shanghai 200093 P. R. China

A new algorithm of the relaxation method is developed for the inversion of forward scattered light to obtain the size distribution of spherical particles. Numerical tests are performed for a laser particle analyzer using the Mie theory and the diffraction approximation. The algorithm efficiency, in the presence of experimental noises, is studied. The results show that the technique is fast in convergence, stable against random noise and insensitive to the distribution of particles and the initial trial distribution.

关键词： particle size analysis forward scattering inversion algorithm relaxation method

Controllable Tunneling of Light through a Quantum-Dot-Molecule Dielectric Film via Electromagnetically Induced Transparency

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Optics and Photonics Journal 2017年第8期7卷 49-67页

作者： Ruixi Zeng Jing Gu jianqi shen Centre for Optical and Electromagnetic Research State Key Laboratory for Modern Optical Instrumentation Zijingang Campus Zhejiang University Hangzhou China

Since discrete multilevel transitions of quantum-dot molecules driven by external electromagnetic fields can exhibit quantum coherence effects, such an optical characteristic can be utilized to control propagation of electromagnetic wave through a quantum-dot molecule dielectric film. Since inner-dot tunneling in quantum-dot molecules can be controlled by a gate voltage, destructive quantum coherence among multilevel transitions in quantum-dot molecule would give rise to EIT (electromagnetically induced transparency). In this report, we shall investigate controllable on- and off-resonance tunneling effects of an incident electromagnetic wave through such a quan-tum-dot-molecule dielectric film, of which the optical response is tuned by the switchable gate voltage. We have found from the theoretical mechanism that a high gate voltage can cause the EIT phenomenon of quan-tum-dot-molecule systems, and under the condition of on-resonance light tunneling through the thin film, the probe field will propagation without loss if the probe frequency detuning is zero. By taking advantage of these effects sensitive to the tunable gate voltage, such quantum coherence would be inte-grated in certain photonic structures, and some devices such as photonic switching and transistors can be designed. Transient evolution of optical characteristics in the quantum-dot-molecule dielectric film (once the tunable gate voltage is turned on or off) is also considered in this report.

关键词： Resonant Tunneling Quantum-Dot Molecules Quantum Coherence Controllable Transmission

Light propagation and reflection-refraction event in absorbing media

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Chinese Optics Letters 2010年第1期8卷 111-114页

作者：沈建琪于海涛卢进灯 College of Science University of Shanghai for Science and Technology

The light propagation within an absorbing medium and the reflection and refraction at the interface of two absorbing media are studied. By using the unit vectors denoting the planes of constant field amplitude and constant phase respectively, the light propagation and attenuation are described by the effective refractive indices which depend on both the complex refractive index of the medium and the angle between the unit vectors. With the expression for the light propagation, the corresponding Snell＇s law and the expression of Fresnel coefficients are obtained, which can be applied to describe the reflection-refraction event at the interface between an arbitrary combination of transparent and absorbing media.

关键词： Electromagnetic wave absorption Light propagation Light refraction Organic polymers Phase interfaces Reflection Refraction Refractive index Refractometers

Transient Characteristics and Accommodative Current Limiting Strategy for Bidirectional Interlinking Converters in Hybrid AC/DC Microgrids

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1575-1588页

作者： Xia shen Zhikang Shuai Wen Huang Chao shen Yang shen Z.John shen College of Electrical and Information Engineering Hunan UniversityChangsha 410082China Department of Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616 USA

Bidirectional interlinking converter(BIC)is the core equipment in a hybrid AC/DC microgrid connected between AC and DC ***,the variety of control modes and flexible bidirectional power flow complicate the influence of AC faults on BIC itself and on DC sub-grid,which potentially threaten both converter safety and system *** study first investigates AC fault influence on the BIC and DC bus voltage under different BIC control modes and different pre-fault operation states,by developing a mathematical model and equivalent sequence ***,based on the analysis results,a general accommodative current limiting strategy is proposed for BIC without limitations to specific mode or operation *** amplitude is predicted and constrained according to the critical requirements to protect the BIC and relieving the AC fault influence on the DC bus *** with conventional methods,potential current limit failure and distortions under asymmetric faults can also be ***,experiments verify feasibility of the proposed method.

关键词： Bidirectional interlinking converter current limiting fault characteristic hybrid AC/DC microgrid variation/oscillation of DC bus voltage