Study of the Intrinsic Recombination Velocity at the Junction of Silicon Solar under Frequency Modulation and Irradiation

In this study, a method for determining the intrinsic recombination velocity at the junction of a silicon solar cell is presented. The expression of intrinsic recombination velocity at the junction was established under irradiation in frequency modulation. Based on this expression, an electrical model of the intrinsic recombination velocity at the junction is presented.

Design of electron wave filters in monolayer graphene with velocity modulations

We compare the transport properties of electrons in monolayer graphene by modulating the Fermi velocity inside the barrier. A critical transmission angle is found only when the Fermi velocity in the barriers is larger than the one outside the barriers. It is shown that the transmission exhibits periodicity with the incident angle below the critical transmission angle, and attenuates exponentially in the opposite situation. For both situations, peak splitting occurs in the transmission as the number of the velocity barriers increases, and the characteristics of the transmission suggest an interesting application of an excellent band-pass filter. The dependence of the conductance on the Fermi energy through an identical velocity- modulation structure differs wildly with different Fermi velocities of the barrier. The counterpart of the peak splitting is the sharp oscillations in the conductance profile. Furthermore, some oscillations for the multiple barriers are so sharp that the structure may be used as an excellent sensor.

Velocity modulation of electron transport through a ferromagnetic silicene junction

We address velocity-modulation control of electron wave propagation in a normal/ferromagnetic/normal silicene junc- tion with local variation of Fermi velocity, where the properties of charge, valley, and spin transport through the junction are investigated. By matching the wavefunctions at the normal-ferromagnetic interfaces, it is demonstrated that the variation of Fermi velocity in a small range can largely enhance the total conductance while keeping the current nearly fully valley- and spin-polarized. Further, the variation of Fermi velocity in ferromagnetic silicene has significant influence on the valley and spin polarization, especially in the low-energy regime. It may drastically reduce the high polarizations, which can be realized by adjusting the local application of a gate voltage and exchange field on the junction.

Optimal transport of cold atoms by modulating the velocity of traps

This work experimentally demonstrates a new method of optimizing the transport of cold atoms via modulating the velocity profile imposed on a magnetic quadrupole trap.The trap velocity and corresponding modulation are controlled by varying the currents of two pairs of anti-Helmholtz coils.Cold 87Rb atoms are transported in a non-adiabatic regime over 22 mm in 200 ms.For the transported atoms their final-vibration amplitude dependences of modulation period number,depth,and initial phase are investigated.With modulation period n = 5,modulation depth K = 0.55,and initial phase φ = 0,cold atom clouds with more atom numbers,smaller final-vibration amplitude,and lower temperature are efficiently transported.Theoretical analysis and numerical simulation are also provided,which are in good agreement with experimental results.

Particle modulations to turbulence in two-phase round jets

The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer （PDA）. Laden with very large particles, no significant attenuations of turbulence intensities were measured in the farfields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop- erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.

Analysis Scheme for Density Modulation Experiments to Study Particle Confinements

Density modulation experiments are powerful experimental schemes for the study of particle transport. The diffusion coefficients （D） and convection velocity （V）, which cannot be evaluated from the particle balance in the equilibrium state, can be obtained separately. Further, the estimated values of D and V are determined independent of the absolute value of the particle source rate, which is difficult to obtain experimentally. However, the sensitivities and interpretation of D and V from the modulation experiments need to be considered. This paper describes numerical techniques for solving the particle balance equation of the modulation components. Examples of the analysis are shown regarding the data of LHD experiments, and the results of the modulation experiments are discussed.

A.C. Recombination Velocity as Applied to Determine n⁺/p/p⁺Silicon Solar Cell Base Optimum Thickness

This work deals with determining the optimum thickness of the base of an n+/p/p+ silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (λ), with boundary conditions that impose recombination velocities (Sf) and (Sb) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (Sb). By the graphic technique of comparing the two expressions obtained, depending on the thickness (H) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.

A novel differential velocity modulation laser spectroscopy

Experimental investigation of a novel differential velocity modulation laser spectroscopy is reported and demonstrated with the spectra of N2+A2IIm-X2∑g+ Meinel system. The S/N ratio excesses 500 : 1, about 60 times higher than that with the traditional non-differential technique.With this technique, we obtained the high-resolution electronic absorption spectra of A2II-X2∑+(1,0) vibration-al band of CS+ for the first time. It is confirmed that this technique will be a powerful method and receive wide application in studies of new molecular ions.

Analysis of Buoyancy Module Auxiliary Installation Technology Based on Numerical Simulation

To reduce the requirement for lifting capacity and decrease the hoist cable force during the descending and laying process of a subsea production system(SPS), a buoyancy module auxiliary installation technology was proposed by loading buoyancy modules on the SPS to reduce the lifting weight. Two models are established, namely, the SPS lowering-down model and the buoyancy module floating-up model. The main study results are the following: 1) When the buoyancy module enters the water under wave condition, the amplitude of tension fluctuation is twice that when SPS enters water; 2) Under current condition, the displacement of SPS becomes three times larger because of the existence of the buoyancy module; 3) After being released, the velocity of the buoyancy module increases to a large speed rapidly and then reaches a balancing speed gradually. The buoyancy module floats up at a balancing speed and rushes out from the water at a pop-up distance; 4) In deep water, the floating-up velocity of the buoyancy module is related to its mass density and shape, and it is not related to water depth; 5) A drag parachute can reduce floating-up velocity and pop-up distance effectively. Good agreement was found between the simulation and experiment results.

Optical heterodyne detected velocity modulation molecular ionic spectroscopy

Optical heterodyne detected velocity modula- tion molecular ionic spectroscopy is presented and employed to observe the rovibrantional spectra of O+2 and O-2. That the lineshape of OH-VMS is of the second derivative of Gaussian profile and its sensitivity is 3.5×10?8 are theoreti- cally analyzed, and they are both in good agreement with our experimental results.

柔性光伏系统颤振性能的节段模型试验研究

柔性光伏支架的频率低、质量轻,极易在风荷载作用下发生大幅振动。以某实际柔性光伏项目为工程背景,借鉴桥梁抗风的研究经验,对该柔性光伏支架的颤振性能进行研究。首先,考虑严格的相似比关系,设计并制作了弹性悬挂节段模型系统,并对其动力特性进行了测试;然后,进行不同光伏组件倾角(-39°~+39°)下的弹性悬挂节段模型测振风洞试验,研究光伏组件风致响应随风速的变化规律,得到各倾角下柔性光伏节段模型的颤振临界风速值,探讨2种气动措施对提高柔性光伏支架颤振稳定性的效果。结果表明:在0°~39°的正倾角工况下,柔性光伏支架的颤振临界风速随光伏组件倾角的增大,呈现先减小后增大的趋势,最小颤振临界风速出现在12°~21°光伏组件倾角范围内,折算成实际风速为9.6m/s;在-39°~0°的负倾角工况下,颤振临界风速随光伏组件倾角的增大,也呈现先减小后增大的趋势,最小颤振临界风速出现在-21°~-12°光伏组件倾角范围内,折算成实际风速为10.1m/s;设置中央稳定板的气动措施难以有效提高柔性光伏支架的颤振临界风速。

基于线性调频连续波的合作式通信辐射源测距

针对加速运动目标参数估计中,离散多项式变换方法无法进行非整数估计的问题,本文提出基于瑞夫算法的离散多项式变换法和基于Chirp-Z变换的离散多项式变换法2种新型离散多项式变换算法,对加速运动目标速度和加速度进行估计,并对2种算法的估计误差和计算量进行了分析比较。结果表明:2种算法在信噪比-20 dB时均方误差开始接近克拉美罗界。基于瑞夫算法的离散多项式变换法与3次迭代基于Chirp-Z变换的离散多项式变换法均可在较低信噪比下可实现任意频率的有效估计且性能接近,二者均可实现低信噪比下速度、加速度的有效估计,但基于瑞夫算法的离散多项式变换法计算量远小于3次迭代基于Chirp-Z变换的离散多项式变换法。

复杂光照条件下基于光流的水运航道流速检测算法

实时准确的河流表面流速数据是现代化水运调度和防洪的重要依据,但传统的仪器测速法大多需要人工实地参与,危险系数高且无法满足大规模系统部署的要求。相比之下,图像测速法不需要直接接触河流,可以依据摄相机获取的连续帧得到近乎实时的速度信息。然而,光流估计作为当前主流的图像测速法,是针对刚体运动提出的,没有考虑流体本身的性质,在河流表面等相似度高的场景中泛化能力较弱。为提高基于光流估计循环全对场变换(RAFT)模型的水流流速算法估算精度,提出一种改进的光流估计测速方法。在特征提取部分增加卷积块注意力模块(CBAM),增强其对河流表面波纹和示踪粒子运动的识别能力。通过优化光流迭代更新部分的损失函数,引入能体现流体运动特征的角误差损失和旋度散度平滑损失,并且为损失函数匹配随迭代次数呈指数增长的权重因子,突出高次迭代结果对于整体结果的显著影响。为验证改进方法的有效性,使用不同场景河流数据集对其进行性能评估,结果表明,该方法在复杂光学噪声场景下的平均相对误差为11.37%,具有较好的鲁棒性,能够生成更精准的表面速度空间分布图。

锂电池模组液冷并联蛇形流道结构设计及优化

锂离子电池被广泛应用于化学储能系统,然而由于该电池固有的产热特性,热失控成为了化学储能电站的一大安全隐患。因此优化设计电池热管理系统,有效避免热失控现象,对化学储能系统安全运行至关重要。文中设计了一种兼具串联折返与并联分支结构的新型并联蛇形流道液冷板,通过仿真实验,研究液冷板流道结构、液冷系统布置、冷却液入口流速对最高温度、温度分布均匀性、进出口压降的影响,以达到优化液冷系统的目的。结果表明,相同冷却液入口流速下,与传统并联流道相比,新型流道的最高温度降低0.2849 K、模组组内温差降低0.4663 K,与传统蛇形流道相比,其进出口压降减小40.18%;基于并联蛇形流道液冷板,液冷系统的最佳布置方案为冷却液二分口注入+液冷板交错布置;不同液冷板流速差异化设置,即两侧液冷板入口流速设定为0.1 m/s,居中液冷板入口流速设定为0.2 m/s,较四板保持相同流速为0.2 m/s的方案,电池模组组内温差降低13.62%,列间温差降低82.59%,能耗降低44.87%,达到“降本增效”的优化效果。合理的流道结构、交错的液冷板布置以及差异化的入口流速设计可以优化电池模组的液冷系统,增加电池模组运行的安全性。

速度调制分子离子激光光谱技术的理论研究

介绍了速度调制光谱对分子离子测量过程中的一些基本问题,运用朗之万运动方程导出了离子在交流电场中的漂移速度表达式;在小调制度近似下,给出了速度调制谱线的解析表达式,表明谱线的基本线型为高斯线型的一次微分线型、强度与调制度成正比;还讨论了调制电场对谱线的影响。

CO^+彗尾带系(A^2Π-X^2∑^+)(2,3)带速度调制激光光谱研究

利用差分速度调制分子离子激光光谱技术，首次测量了 ＣＯ~＋彗尾带系（Ａ~２Π－Ｘ~２∑~＋）（２，３）弱带转动吸收光谱，通过对测量谱线的标识，获得了两态的分子常数，其中下态ｖ~＂＝３的常数未见有文献报导。在锁相放大器１ｓ积分时间下，实验系统的吸收测量灵敏度实测为 １．５６ ｘ １０^(－６)。

一种大面积抗干扰高射频激光光幕靶设计

提出了一种能同时测量高射频火炮射击速度和密集度的大面积激光光幕靶设计方案。采用半导体激光脉冲调制、光电传感器列阵接收和单片机数字处理技术,不仅实现了光靶与计时系统一体化,而且有效地去除诸如炮口闪光、外界自然光及蚊虫等干扰,提高了测量的灵敏度、精度和可靠性。

海底沉积物声速与物理性质的理论关系

为建立海底沉积物声速与物理性质的关系,引入密度变化比和弹性模量变化比为参数描述海底沉积物声速。密度变化比是描述声速的一个复合参数,由孔隙率、固相密度和海水密度三个物理参数表示;弹性模量变化比是描述声速的另一个复合参数,由孔隙率、固相体积模量和海水体积模量三个物理参数表示;声速公式可展开为这两个复合参数的泰勒多项式。两个复合参数的变化构成声速曲面,声速曲面包含了声速特性与沉积物性质的完整信息;而单参数声速公式是声速曲面上的一条曲线。数值计算与测试结果对比表明:把孔隙率-声速经验公式变换为参考声速乘以一个调制函数的标准形式,各个海区的孔隙率-声速经验公式的调制函数是相当接近的。论文导出的声速公式与Wood声速公式的区别在于弹性模量的模型不同。

膜生物反应器中影响膜透水率的几个因素

本文研究了影响膜 -好氧生物反应器中中空纤维膜透水率的几个因素 ,如组件长度、操作压力、膜面流速、活性污泥浓度和温度。中空纤维膜内 ,压力沿料液流动方向呈抛物线型分布 ,所以在膜内径和膜面流速一定的情况下 ,存在一个最佳的膜组件长度 Llin使得膜利用率最高 ,且最省能 ;操作压力对膜透水率的影响分为三个区域 ,各个区域膜的主要过滤阻力不同 ,不同污泥浓度时 ,为了使中空纤维膜内腔不堵塞 ,膜面流速必须高于某一范围 ,膜透水率随温度呈正比例关系变化。

基于AMESim节流调速回路仿真及实验研究

推导出考虑液压缸泄漏的节流调速回路活塞运动速度表达式,基于AMESim建立了进油路的节流调速回路仿真模型,分析液压缸泄漏对节流调速回路速度-负载特性的影响,得到速度-负载曲线;利用QCS003C教学实验台进行实验验证,得出所建立的模型是准确的结论,为节流调速回路的进一步研究提供了理论依据。