GPU-based high-precision real-time radiometric rendering for IR scene generation

Aiming at the problem that traditional infrared scene real-time radiometric rendering method leads to greater calculation error for securing real-time purpose, this article studies the IR rendering comprehensive optimization method, which secures real-time performance as well as calculation accuracy. Firstly, based on the effective average value principle, the spectrum coupling thermal emission and reflected radiations in the spectral radiometric equation are decomposed into physical quantities, and the spectral radiometric equation is improved to become a simpler calculation between “primer” radiance terms and effective average factors. Secondly, the parameter processing method is proposed to cope with the situation when index parameters of effective average factors exceed the maximum dimensionalities of graphics processing unit (GPU) look-up-table (LUT); and pre-calculation method is applied to promote the real-time evaluation efficiency of the physical quantities in the radiometric equation. Finally, concurrent computation of radiometric equation is achieved with GPU IR scene generation software and the precise and real-time rendering of three-dimensional IR scene is realized.     

动态波前误差的自适应光学实时校正

本文报道了在实验室里用由21元面阵变形反射镜、横向剪切干涉仪和平行控制系统构成的自适应光学系统实时校正动态波前误差的原理和实验结果.     

大气信道简化单次散射模型

采用椭球坐标系研究非直视日盲紫外光通信的单次散射模型,求解过程中要对有效散射体的体积进行复杂的数值积分并确定三组积分限。为便于分析,使用近似表达式极大简化了复杂单次散射信道模型,得出路径损耗是收发机几何结构与大气散射吸收系数的函数。对传输距离和路径损耗的仿真证明,该近似表达式与原始模型的所得结果吻合很好。利用该近似表达式,分别仿真分析了大气能见度对紫外光通信系统路径损耗和误码率的影响,仿真结果表明,大气能见度并不是越高越好,而是在能见度为10 km时紫外光通信系统有最佳性能。     

大气信道简化单次散射模型

采用椭球坐标系研究非直视日盲紫外光通信的单次散射模型,求解过程中要对有效散射体的体积进行复杂的数值积分并确定三组积分限。为便于分析,使用近似表达式极大简化了复杂单次散射信道模型,得出路径损耗是收发机几何结构与大气散射吸收系数的函数。对传输距离和路径损耗的仿真证明,该近似表达式与原始模型的所得结果吻合很好。利用该近似表达式,分别仿真分析了大气能见度对紫外光通信系统路径损耗和误码率的影响,仿真结果表明,大气能见度并不是越高越好,而是在能见度为10 km时紫外光通信系统有最佳性能。     

Adaptive time-domain filtering for real-time spectral discrimination in a Michelson interferometer

We present a method of spectral discrimination that employs time-domain processing instead of the typical frequency-domain analysis and implement the method in a Michelson interferometer with a nonlinear mirror scan. The technique yields one analog output value per scan instead of a complete interferogram by directly filtering a measured scan with a reference function in the time domain. Such a procedure drastically reduces data-processing requirements downstream. Additionally, using prerecorded interferograms as references eliminates the need to compensate for scan nonlinearities, which broadens the field of usable components for implementation in miniaturized sensing systems. With our efficient use of known spectral signatures, we demonstrate real-time discrimination of 633- and 663-nm laser sources with a mirror scan length of 1 microm , compared with the Rayleigh criterion of 7 microm.     

换流变压器噪声预测模型及其简化研究

换流变压器作为高压直流换流站主要噪声源,其噪声预测精度和控制方法的选择将直接影响换流站整体噪声预测水平及治理效果。通过对换流变压器噪声的产生机理、噪声频谱及常见治理方案等方面进行系统研究,重点推出了换流变压器噪声控制方法BOX-IN技术,并就BOX-IN装置的噪声预测模型进行了简化和对比验证。通过对降噪量进行现场测试,结果表明,BOX-IN装置降噪量达到20dB(A)左右,与理论计算值近似,为进一步提高高压直流换流站噪声预测精度提供了理论依据。     

Dynamics of individual single-walled carbon nanotubes in water by real-time visualization

Individual single-walled carbon nanotubes (SWNTs) in aqueous suspension are visualized directly by fluorescence video microscopy. The fluorescent tagging is simple, biocompatible, and does not modify the SWNTs. The dynamics of individual SWNTs in water are observed and quantified for the first time. We measure the confined rotational diffusion coefficient and find it in reasonable agreement with predictions based on confined diffusion of dilute Brownian rods. We determine the critical concentration at which SWNTs in suspensions start interacting. By analyzing the fluctuating shape of SWNTs in the 3 to 5 microm range, we determine that their persistence length ranges between 32 and 174 microm, in agreement with theoretical estimates; thus, commonly available SWNTs in liquids can be considered as rigid Brownian rods in the absence of imposed external fields or self-attractive forces.     

射线实时成像检测系统透视变换模型

以射线实时成像检测系统为研究对像 ,从透视成像的角度对射线实时成像检测系统的各个组成部分进行了较为详细的分析。将系统划分为射线透射环节、增强器成像环节、摄像系统变换环节和采集量化环节。从摄像机出发组建统一的坐标系 ,以此为基础 ,较为完整地建立了各成像环节的透视变换模型 ,为进一步进行缺陷的精确定位及定量分析打下了良好的基础。同时对其它相关应用场合也有实际意义     

Application of magneto-optical method for real-time visualization of eddy currents with high spatial resolution for nondestructive testing

In this paper we describe a new, laser supported, eddy current microscope for the real-time visualization of eddy current distributions. In the experimental set-up, the induction of eddy currents is conventionally performed by an alternating current excitation coil above the object surface. The magnetic field induced by the eddy currents is detected by the use of the Faraday effect. For that purpose, a laser beam is passed through a suitable thin crystal integrated in the excitation coil. The polarization direction of the laser beam is rotated in this thin crystal depending on the local magnetic field. The area distribution of the rotation angle is transformed into a grey value picture using an optical set-up, which comprises a conventional microscope, a lighting technique, an analyzator, and a CCD sensor. By choosing a suitable optic, a real-time measurement of the magnetic field with a high spatial resolution can be carried out. In this paper, the basic physics and the design of the new microscope are described. The initial results of experimental investigations concerning the resolution power of magneto-optic eddy current sensors are presented and compared with conventional eddy current sensors.     

Adaptive semi-empirical model for non-contact atomic force microscopy

Non-contact atomic force microscope is a powerful tool to investigate the surface topography with atomic resolution. Here we propose a new approach to estimate the interaction between its tips and samples, which combines a semi-empirical model with density functional theory (DFT) calculations. The generated frequency shift images are consistent with the experiment for mapping organic molecules using CuCO, Cu, CuCl, and CuO_x tips. This approach achieves accuracy close to DFT calculation with much lower computational cost.     

语音LPC参数的自适应LMS实时估计算法

本文提出了一种应用LMS自适应算法对语音LPC参数进行实时提取的方法,分析了这种算法在语音环境下的收敛性及实现实时处理的条件。本文还对残差序列的实时提取进行了讨论。文中对于有关的理论进行了计算机模拟验证,并对比传统的经典方法得出了比较理想的实验结果。     

Perceptual simplification for model-based binaural room auralisation

Design of computationally efficient yet perceptually realistic room auralisation algorithms require a careful selection of the early reflections to be auralised. A perception-based simplification algorithm is presented for the selection of the early reflections using a criterion which depends both on the arrival time and on the angle of incidence of the early reflection with respect to the listener. Results of two subjective tests for the evaluation of the proposed algorithm are presented. The proposed algorithm is shown to provide a significant reduction in the number of early reflections without significantly affecting the tested localisational or spatial qualities of auralisation.     

基于电化学模型的锂离子电池多尺度建模及其简化方法

锂离子电池的精确建模和状态估计对于电动汽车电池管理系统非常重要,准二维(P2D)电化学模型由于计算复杂,难以直接应用于电池管理的参数在线估计和实时控制中.本文基于多孔电极理论和浓度理论,提出一种考虑锂离子液相动力学的简化准二维(SP2D)模型.忽略锂离子孔壁流量沿电极厚度方向的变化求解SP2D模型所描述的锂离子电池锂浓度分布,基于锂离子电池电化学平均动力学行为求解固相和液相电势变化,推导出电池电压计算的简化表达式;采用恒流、脉冲以及城市循环工况放电电流对比分析了严格P2D模型与SP2D模型的终端电压和浓度分布.结果表明:SP2D模型在保持较高计算精度的同时,可显著提高计算效率.     

基于小波-ARMA模型的光纤陀螺自适应滤波

针对光纤陀螺输出是非平稳信号的特点,提出了小波-ARMA模型建模方法 ,并与ARIMA模型进行了对比分析;针对滤波方程中的量测噪声不能确定的问题,提出了基于量测噪声自适应的滤波方法,并与卡尔曼滤波进行了对比分析。研究结果表明:滤波方法相同时,小波-ARMA模型的滤波效果优于ARIMA模型;模型相同时,自适应滤波效果优于卡尔曼滤波;且建模精度大于滤波方法对滤波效果的影响。Allan方差分析表明:基于小波-ARMA模型的自适应滤波能很好地滤除光纤陀螺中的量化噪声,提高陀螺的输出精度。     

Flow visualization and aerodynamic-force measurement of a dragonfly-type model

An unsteady flow visualization and force measurement were carried out in order to investigate the effects of the reduced frequency of a dragonfly-type model. The flow visualization of the wing wake region was conducted by using a smoke-wire technique. An electronic device was mounted below the test section in order to find the exact position angle of the wing for the visualization. A load-cell was employed in measuring aerodynamic forces generated by a plunging motion of the experimental model. To find the period of the flapping motion in real time, trigger signals were also collected by passing laser beam signals through the gear hole. Experimental conditions were as follows: the incidence angles of the foreand hind-wing were 0° and 10°, respectively, and the reduced frequencies were 0.150 and 0.225. The freestream velocities of the flow visualization and force measurement were 1.0 and 1.6m/sec, respectively, which correspond to Reynolds numbers of 3.4 × 10³ and 2.9 × 10³. The variations of the flow patterns and phase-averaged lift and the thrust coefficients during one cycle of the wing motion were presented. Results showed that the reduced frequency was closely related to the flow pattern that determined flight efficiency, and the maximum lift coefficient and lift coefficient per unit of time increased with reduced frequency.     

Adaptive control of vowel formant frequency: evidence from real-time formant manipulation

Auditory feedback during speech production is known to play a role in speech sound acquisition and is also important for the maintenance of accurate articulation. In two studies the first formant (F1) of monosyllabic consonant-vowel-consonant words (CVCs) was shifted electronically and fed back to the participant very quickly so that participants perceived the modified speech as their own productions. When feedback was shifted up (experiment 1 and 2) or down (experiment 1) participants compensated by producing F1 in the opposite frequency direction from baseline. The threshold size of manipulation that initiated a compensation in F1 was usually greater than 60 Hz. When normal feedback was returned, F1 did not return immediately to baseline but showed an exponential deadaptation pattern. Experiment 1 showed that this effect was not influenced by the direction of the F1 shift, with both raising and lowering of F1 exhibiting the same effects. Experiment 2 showed that manipulating the number of trials that F1 was held at the maximum shift in frequency (0, 15, 45 trials) did not influence the recovery from adaptation. There was a correlation between the lag-one autocorrelation of trial-to-trial changes in F1 in the baseline recordings and the magnitude of compensation. Some participants therefore appeared to more actively stabilize their productions from trial-to-trial. The results provide insight into the perceptual control of speech and the representations that govern sensorimotor coordination.     

Excitons in the one-dimensional Hubbard model: a real-time study

We study the real-time dynamics of a hole and doubly occupied site pair, namely, a holon and a doublon, in a 1D Hubbard insulator with on-site and nearest-neighbor Coulomb repulsion. Our analysis shows that the pair is long-lived and the expected decay mechanism to underlying spin excitations is actually inefficient. For a nonzero intersite Coulomb repulsion, we observe that part of the wave function remains in a bound state. Our study also provides insight on the holon-doublon propagation in real space. Because of the one-dimensional nature of the problem, these particles move in opposite directions even in the absence of an applied electric field. The potential relevance of our results to solar cell applications is discussed.