基于仿生眼异向运动原理的超小型无人旋翼机定点着陆新方法

基于仿生双眼的异向运动原理,提出了超小型无人旋翼机野外定点着陆的一种新型定位方法,并且根据眼球运动的神经回路,建立了眼球异向运动控制模型.对该控制模型进行了仿真实验,并将仿真结果与双目异向运动的生理学特点作了对比,对比结果表明该模型符合双眼异向运动的生理学特点,能自适应地实现双目异向运动.最后,在仿真的基础上,分析了影响超小型无人旋翼机野外定点着陆的因素.这种新型的方法与传统的视觉方法相比,可以消除盲区,从而克服了野外定点着陆的不准确性.     

Dynamic deflection of perimeter-attached thin-sheet structural components under blast loading

The results of experimental investigations of the relation the pressure pulse of blast products and the deflection of thin-sheet structural components with a circular and rectangular attachment perimeter under a loading are presented. The relationship between the relative deflection and specific (per unit mass of the loaded portion of the plate) kinetic energy imparted to the plate being deformed is determined.Translated from Problemy Prochnosti, No. 4, pp. 94–96, April, 1993.     

Spatial frequency masking in human vision: binocular interactions.

Binocular contrast interactions in human vision were studied psychophysically. Thresholds were obtained for sinewave grating stimulation of the right eye in the presence of simultaneous masking gratings presented to the right eye (monocular masking) or left eye (dichoptic masking). In the first experiment, thresholds were measured at 0.25, 1.0, 4.0, and 16.0 cycle per degree (cpd) as a function of the contrast of masking gratings of identical frequency and phase. Thresholds rose nonmonotonically with masking contrast. At medium and high contrast levels, dichoptic masking was more effective in elevating contrast thresholds than monocular masking, and approached Weber's Law behavior. In the second experiment, spatial frequency tuning functions were obtained for test gratings at five spatial frequencies, by measuring threshold elevation as a function of the spatial frequency of constant-contrast masking gratings. At 1.0, 4.0, and 16.0 cpd, the tuning functions peaked at the test frequencies. The dichoptic tuning functions had a bandwidth of about 1 octave between half-maximum points, narrower than +/- 1 octave bandwidths of the monocular tuning functions. At 0.125 and 0.25 cpd, the tuning functions were broader and exhibited a shift in peak masking to frequencies above the test frequencies.     

Cyclopean geometry of binocular vision

The geometry of binocular projection is analyzed in relation to the primate visual system. An oculomotor parameterization that includes the classical vergence and version angles is defined. It is shown that the epipolar geometry of the system is constrained by binocular coordination of the eyes. A local model of the scene is adopted in which depth is measured relative to a plane containing the fixation point. These constructions lead to an explicit parameterization of the binocular disparity field involving the gaze angles as well as the scene structure. The representation of visual direction and depth is discussed with reference to the relevant psychophysical and neurophysiological literature.     

基于叠加模型的橡胶元件动态特性分析

基于模型叠加理论,针对橡胶元件的动态特性开展研究。采用时间—步长法,在MATLAB中建立了一维多参数橡胶叠加本构模型。模型由弹性单元、黏弹单元和弹塑单元并联构成。黏弹单元采用Able黏壶,用于表征橡胶元件的频率依赖性;弹塑单元采用多线性理想弹塑模型,用于表征橡胶元件的振幅依赖性。对比测试结果表明:在计算谐波激励下橡胶弹簧的受力时,力—位移迟滞曲线的计算结果与测试数据能很好地吻合,刚度频率振幅依赖性和阻尼频率依赖性能被较好的表征。在计算随机激励下橡胶隔振器的受力时,高频激励下的计算结果与测试数据能较好地吻合,低频激励下有一定程度的偏差,但计算精度在工程可接受范围之内。提出的叠加模型能较好的表征橡胶元件的动态特性,能够提高动力学模型的准确性。     

Dynamic inferential estimation using principal components regression (PCR)

Principal components regression (PCR) is applied to the dynamic inferential estimation of plant outputs from highly correlated data. A genetic algorithm (GA) approach is developed for the optimal selection of subsets from the available measurement variables, thereby providing a method of identifying nonessential elements. The theoretical link between principal components analysis (PCA) and state–space modelling is employed to identify a measurement equation involving the GA-selected subset, which is then used for inferential estimation of the omitted variables. These techniques are successfully demonstrated for the inferential estimation of outputs from a validated industrial benchmark simulation of an overheads condensor and reflux drum model (OCRD).     

Chromatographic profiling and multivariate analysis for screening and quantifying the contributions from individual components to the bioactive signature in natural products

A new approach for assigning bioactivity to individual components in extracts from natural products is presented and validated. 60 mixtures were created according to a uniform design from 12 chemical components of which 7 possessed antioxidant activity. The synthetic mixtures were characterized by chromatographic profiling and their antioxidant power was assessed by use of the Ferric Reducing Antioxidant Power (FRAP) assay. 40 of the prepared mixtures were used as a training set to create a cross validated partial least squares (PLS) regression model with the FRAP measurement as response. The remaining 20 mixtures were used as an independent external validation set. The bioactive signature was singled out from the multi-component PLS model using target projection (TP). In addition to excellent prediction performance of antioxidant strength from the bioactive signature, our approach, called Quantitative Pattern-Activity Relationship (QPAR), was able to rank 6 of the 7 bioactive components according to individual bioactive strength. The ratios of bioactive capacity of the two most active components to the two least active components were close to 100 to 1. This explains why one of the two least bioactive components was not detected.     

Dynamic behavior of shell components in engine blocks during their kinematic excitation

The study was reported at the All-Union Scientific Conference on Problems of Engine Strength, which was convened in Moscow in October, 1986.     

Automatic vergence control based on hierarchical segmentation of stereo pairs

This article presents a video system to focus an object of interest in the field of view by means of a stereo robotic head. The system relies on a new hierarchical segmentation technique that split the stereo pair into regions in a combined way. After segmentation is achieved, resulting regions in both images are implicitly related by a set of links and, consequently, their disparity can be estimated. Then, the cameras vergence is changed according to the estimated disparity until the object of interest is focused. The system has proven to be robust against mild noise and illumination changes. Its main advantage is that calibration is not a critical issue for the system to work. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 224–233, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10058     

双目系统中图像随机噪声的分析

图像立体匹配的精度是保证双目系统测量准确性的重要因素，也是系统研制过程中需要解决的难点问题。对影响双目系统中图像立体匹配精度的随机噪声建立了一种局部统计量符合高斯分布的简化统计模型，基于这个噪声模型设计了滤波方案。实验表明，滤波后图像立体体匹配的精度优于1／4像素。     

fMRI analysis of excessive binocular disparity on the human brain

The aim of this study is to evaluate brain regions related with excessive binocular disparity that may be linked to stereoscopic visual fatigue. In stereoscopic displays, excessive binocular disparity may generate blurring or double vision in the stereovision and induce unnatural oscillations in accommodation and vergence. These phenomena may lead to visual fatigue and activation (or deactivation) of human brain related with sensory and eye movement functions. A functional magnetic resonance imaging (fMRI) method is used to investigate the effect of excessive binocular disparity on human brain. Subjective assessments of visual fatigue are also conducted with the same stimuli as the fMRI experiment. Based on the subjective assessment results, participants are classified into low‐ and high‐fatigue groups. From the fMRI experiments, the high‐fatigue group showed more activation at the intraparietal sulcus (IPS) than the low‐fatigue group, when viewing an excessive disparity stimulus. The results showed that the excessive binocular disparity stimulus may induce overload to the IPS region, which is related with stereo processing and saccadic eye movement. In addition, it could be possible to use fMRI as an objective measurement method for understanding the stereoscopic visual fatigue when stimuli with excessive binocular disparity are applied.     

存在镜面反射时的双目立体匹配

传统的立体匹配方法建立在Lambertian的漫反射模型之上,漫反射模型的立体匹配在一个图像的大多部分是有效的,但是在处理图像中包含镜面反射的部分时结果会产生严重的匹配错误。笔者利用漫反射和镜面反射在灰度和最大色度上的不同,分离出镜面反射的像素,然后采用一种针对镜面反射的匹配测度,在图像中漫反射部分和镜面反射部分都能匹配得到正确的视差。结果证明了方法的有效性。