Estimation of parameters of object motion based on stationary quasi-autonomous direction finder

A method for parametric identification of an object motion model represented in terms of generalized polynomials is proposed. The method is based on a stationary direction finder that, in addition to its own angular measurements, obtains data about the slant range to the observed object.     

On the oscillating motion of an Oldroyd-B fluid between two infinite circular cylinders

Exact solutions for some oscillating motions of Oldroyd-B fluids, between two infinite coaxial circular cylinders, are established by means of the Laplace transform. These solutions, presented as sum of the steady-state and transient solutions describe the motion of the fluid at small and large times and reduce to the similar solutions for Maxwell, second grade and Newtonian fluids as limiting cases. After some time, when the transients disappear, the starting solutions tend to the steady-state solutions which are periodic in time and independent of the initial conditions. The required time to obtain the steady-state for the cosine and the sine oscillations of the boundary is determined by graphical illustrations. This time decreases if the frequency of the velocity of the boundary increases.     

Object motion tracking using a moving direction estimate and color updates

This paper presents a direction detection and tracking object color update algorithm used to track moving objects that change colors. Different from traditional color-based tracking methods, which use an initial color distribution in order to track objects as long as the object carries the full or partial initial color, this method introduces a color update method used to quickly find the new object color in a new location if the object changes its color partially or completely; the updated color is then used to locate the object. In our algorithm, an initial color pattern is used to track an object using the color. During the tracking, an object’s new location is at first estimated and then used to detect any color change. If the color has changed, a new color pattern is updated based on the changes in the previous color distribution, and then the new color pattern is used to calculate the current location of the object. This algorithm utilizes the property that the movement of an object can be estimated either by using the object’s shadow or by background subtraction. The implementation of our algorithm results in an effective real-time object tracking. The validity of the approach is illustrated by the presentation of experiment results obtained using the methods described in this paper.     

Friction coefficients in a longitudinal direction between the finger pad and selected materials for different normal forces and curvatures

This study investigated the effect of object curvature, normal force and material on skin friction coefficient. Twelve subjects slid their middle fingertip pad against a test object with small (11 mm), medium (18, 21 mm) or large (flat object) radii of curvature, while maintaining a normal force of 1, 10 or 20 N. Tested materials were aluminium and four rubber hoses. The average friction coefficient was 0.6 for aluminium and 0.9 for the rubber hoses. As normal force increased from 1 to 20 N, the average friction coefficient decreased 46%. Friction coefficient did not vary significantly with object curvature. The citation of friction coefficient data requires careful attention to normal force levels with which they are measured, but not so much to object curvature between 11 mm and infinity. This study provides skin friction coefficient data that are needed for design of objects that are manipulated with the hands. The investigation of the effect of object curvature on skin friction coefficient has important implications to ergonomics practices as many objects handled in everyday activities have curved surfaces.     

Motion of a mechanism along a rough inclined plane using the motion of internal oscillating masses

A mobile mechanism capable of moving along a rough plane inclined surface using the motion of internal masses according to the harmonic law is considered. Oscillations of internal masses have equal frequencies and different phases. It is shown that using this principle of motion the mechanism can move upward along an inclined plane. Maximization conditions of the established motion velocity are given.     

Reconstructing and analyzing periodic human motion from stationary monocular views

We have shown previously that it is possible to accurately reconstruct periodic motions in 3D from a single camera view, using periodicity as a physical constraint from which to perform geometric inference. In this paper we explore the suitability of the reconstruction techniques for real human motion. We examine the degree of periodicity of human gait empirically, and develop algorithmic tools to address some of the challenges arising from this type of motion, including reconstructing motions that deviate from pure periodicity, properly handling the trajectories of multiple points on an articulated body, and proposing a distance function for measuring the difference between two reconstructions. Importantly, we illustrate the usefulness of these techniques by applying them to the tasks of view-invariant activity classification, clinical gait analysis and person identification.     

利用拉氏算子鉴别运动模糊方向

提出一种新的鉴别运动模糊图像的运动模糊方向的方法,它利用拉氏算子对运动模糊图像进行无方向性的二阶微分,并求微分图像的自相关,发现自相关图像中数值较大的点(鉴别点)能够有效标示出运动模糊方向。选取适当数目的候选鉴别点,并利用聚类方法剔除其中的奇异点,得到鉴别点;过零频尖峰(自相关图像的中心点)画一条直线,计算各个鉴别点到该直线的距离,求距离和;改变直线方向,当距离和最小时,直线的方向即为运动模糊方向。数据实验表明,这一新的运动模糊方向鉴别方法,具有抗噪声能力强、适用范围广、计算量小、鉴别精度高、稳定性好的优点．     

On detecting a human and its body direction from a video

This article describes a novel technique for detecting a human and his or her body direction using the histograms of oriented gradients (HOG) feature. The HOG feature is a well-known feature for judging a human, but normally it contains a background feature, which has a negative influence on the judgment. This article proposes the employment of the HOG feature based on a human model. The feature is also employed for detecting the direction of a human body. Experimental results show the effectiveness of the proposed technique compared with conventional ones.     

方向微分分块统计的运动模糊方向鉴别

运用方向微分鉴别运动模糊方向的基本思想是将原图像视为各向同性的一阶马尔可夫随机过程.但实际处理效果并不理想,其主要原因是很多图像并不严格满足各向同性的一阶马尔可夫随机过程.从整个图像来看,物体形状、平坦区域等因素都会弱化这一物理前提,造成微分图像计算不准确.为此提出一种优化方法,先提取多个局部方差较大的特征块,再分块进行运动模糊方向的鉴别,统计分块结果.实验结果表明,本文方法在传统的基于方向微分的加权平均法鉴别误差较大时,依然可以取得不错的鉴别精度.     

作平面运动的二维平面板的热耦合动力学问题

研究受到热冲击的作平面运动的二维平面板的温度场和动力学响应.考虑温度场和应变场的耦合,通过计算熵密度,建立了平面板的热传导变分方程,此外,在本构关系式中考虑热应变,基于平面应力假设建立了作平面运动的二维平面板的动力学变分方程.用有限元方法分别对温度场和变形场进行离散.最后,计算了作直线平动的平面板的温度场和变形场,揭示了温度和变形的相互耦合特征,体现了板运动对温度和变形的影响.     

Recovering facial shape using a statistical model of surface normal direction

In this paper, we show how a statistical model of facial shape can be embedded within a shape-from-shading algorithm. We describe how facial shape can be captured using a statistical model of variations in surface normal direction. To construct this model, we make use of the azimuthal equidistant projection to map the distribution of surface normals from the polar representation on a unit sphere to Cartesian points on a local tangent plane. The distribution of surface normal directions is captured using the covariance matrix for the projected point positions. The eigenvectors of the covariance matrix define the modes of shape-variation in the fields of transformed surface normals. We show how this model can be trained using surface normal data acquired from range images and how to fit the model to intensity images of faces using constraints on the surface normal direction provided by Lambert's law. We demonstrate that the combination of a global statistical constraint and local irradiance constraint yields an efficient and accurate approach to facial shape recovery and is capable of recovering fine local surface details. We assess the accuracy of the technique on a variety of images with ground truth and real-world images     

Entropy of a stationary process and entropy of a shift transformation in its sample space

We construct a class of non-Markov discrete-time stationary random processes with countably many states for which the entropy of the one-dimensional distribution is infinite, while the conditional entropy of the “present” given the “past” is finite and coincides with the metric entropy of a shift transformation in the sample space. Previously, such situation was observed in the case of Markov processes only.     

Cyclic motion design and analysis for a passive object manipulation using an active plate

We propose a novel scheme for manipulating a passive object using an active plate. In previous studies, cyclic manipulations that transport objects on a plate, position control of an object on a plate, and juggling have been realized. In most manipulations using plates, object motions in the direction of the gravitational force are not considered. The objective of this study is to control an object’s orientation with respect to the gravitational force direction using an active plate for realizing hitherto unrealized object motion. In this context, a tumble doll, which is a planar rigid sphere, is defined as the object. Motions of the object and active plate are designed to be cyclic. A state vector composed of the object’s angle and angular velocity is defined, and the cyclic motion is expressed as a nonlinear discrete system. Fixed points of the state vector are searched for in the designed cyclic motion. A stability analysis around the fixed points is conducted using a Poincaré map. As a result, the fixed points are shown to be asymptotically stable. Finally, experimental results are used to verify that the object’s angle can be manipulated with the designed cyclic motion using the plate.     

Spurious Granger causality between a broken-trend stationary process and a stochastic trend process

This paper examines spurious Granger causality between a trend stationary process with structural breaks and a stochastic trend process. Monte Carlo simulations show that whether or not there are deterministic variables in the testing models, the sample size and the parameter values of the data generation process can affect the empirical frequencies of spurious Granger causality relations in different degrees. The analysis also points out that an alternative rank-based causality test method can avoid the risk of spurious causality to some extent by adopting an intercept and deterministic trend term in the testing regressions.     

Visual search during dynamic displays: Effects of velocity and motion direction

The visual search performance during dynamic environment has been demonstrated that could be affected by the motion of target and distractors. In present study, two experiments were conducted to investigate the effect of motion direction and velocity on visual search on screen. In Experiment 1, participants were required to complete the search task at three velocities(2, 8, and 16 deg/s) and four directions of motion(up, down, left, right). In Experiment 2, participants finished the more difficult visual search tasks within two directions (right, left) at higher velocities (16, 24, and 32 deg/s). The experiments revealed that the increase of velocity on the screen has a negative effect on the visual search performance, and when the velocity is higher than 8 deg/s, search times for horizontally moving images were shorter than those for vertically moving images. Furthermore, the difference in search performance could also be found in left-moving and right-moving images with the increase of velocity. Right-moving images were proved to correspond to higher visual search performance. In addition, eye movement data indicated that saccade amplitude and saccade velocity might be responsible for this difference. The results of this study can be applied to industrial inspection, safety inspection, driving, and other fields.     

The robust and efficient adaptive normal direction support vector regression

The recently proposed reduced convex hull support vector regression (RH-SVR) treats support vector regression (SVR) as a classification problem in the dual feature space by introducing an epsilon-tube. In this paper, an efficient and robust adaptive normal direction support vector regression (AND-SVR) is developed by combining the geometric algorithm for support vector machine (SVM) classification. AND-SVR finds a better shift direction for training samples based on the normal direction of output function in the feature space compared with RH-SVR. Numerical examples on several artificial and UCI benchmark datasets with comparisons show that the proposed AND-SVR derives good generalization performance     

Bidirectional estimation between context and motion in motion sequence in which context changes

ABSTRACT

We describe a motion recognition method for reducing recognition errors. The method has a two-layer structure: a lower layer for motion recognition that is affected by the distribution of topics used as context information in the upper layer and an upper layer for the topic distribution that is affected by motion recognition in the bottom layer. We introduce an algorithm for the bottom layer to integrate the motion likelihood calculated using a hidden Markov model and motion appearance probabilities obtained by a topic model. We also use a set of particles to estimate and update contexts on the basis of the result of motion recognition in the bottom layer. The set of particles presents a probabilistic distribution of motion topics, and motion recognition and particle update procedures are performed on each particle. We experimented with two types of sequential motion: a sequence of 33 daily motions and complex motion sequences assuming actual observation. The results showed that the proposed method reduced recognition errors and tracked latent topics better than conventional methods did.     

船舶运动状态下风速风向测量补偿与数字仿真

为了研究船舶运动状态下的风速风向精确测量,设计了一种船舶风速风向动态测量及误差补偿的数字仿真系统。通过对船舶航行状态下的风速风向测量原理进行分析,建立了船舶平面运动的相对风速风向和真风风速风向的解算模型,并根据船舶空间运动的风速风向测量及其误差补偿算法,对船舶横摇、纵摇状态下的风速风向的动态测量和误差补偿进行了数字仿真。数字仿真结果表明,该方法能够消除船舶航行时的运动姿态对风速风向测量带来的影响,为船舶的操纵控制和航行安全提供了精确和可靠的风速风向数据信息。     

Instability of Marangoni toroidal convection in a microchannel and its relevance with the flowing direction

The instability of the Marangoni toroidal flows in microchannels is of interest in various areas such as microfluidics and heat transfer. Using pure liquid as working fluid in this study, the phenomena of Marangoni symmetry-to-asymmetry transition which does not arise from the buoyancy was observed. The experiments used a vertical cylindrical channel and the meniscus was formed at the bottom outlet to minimize the buoyant influences. Two microscopes were used to have top view and side view of the meniscus simultaneously. The Marangoni flow field on the meniscus was obtained by means of tracing particles. It was observed that the Marangoni flow on a concave meniscus was always nearly symmetrical, while that on a convex meniscus was out of symmetry with only one single vortex occupying the whole channel. The experimental results were highly consistent to the simulation results of authors’ previous 3D numerical model (Pan and Wang in Microfluid Nanofluid 9:657, 2010). Theoretical analysis together with newly developed numerical models is employed to dig into the mechanisms. The inward (from the meniscus edge to the center) Marangoni flow is found not as stable as the outward one. Based on the heat transfer analysis, a concave meniscus always has a colder edge thus the flow is outward and stable; while a convex enough meniscus could have an inward flow thus not stable and tends to lose the symmetry. The amplification mechanism of the inward Marangoni flow is comprehensively explained. Two conditions are required for the inward flow to lose the symmetry, i.e., the bulk liquid must be warmer than the meniscus, and the Marangoni number must be above a certain small value.     

相向运动径向模糊图像的复原算法研究

当摄像机在高速靠近或远离目标过程中成像时,所得目标图像会产生从中心到边缘的放射状径向模糊,从而影响对目标的识别与跟踪。首先建立了理想情况相向运动条件下图像模糊退化的数学模型,通过对模型的深入分析,确定了影响模糊程度的主要模型参数,然后模拟出与实际成像一致的仿真图像,并严格推导出图像复原的递推公式,最后通过对径向模糊仿真图像的复原验证了该公式的正确性。