Block-matching-based motion field generation utilizing directional edge displacement

A motion field generation algorithm using block matching of edge flag histograms has been developed aiming at its application to motion recognition systems. Use of edge flags instead of pixel intensities has made the algorithm robust against illumination changes. In order to detect local motions of interest effectively, a new adaptive frame interval adjustment scheme has been introduced in which only the edge flags due to local motions present in the frame are accumulated and utilized in block matching. These edge flags are projected onto x and y axes to generate histograms and the motion in x and y directions are determined by histogram matching. As a result, the computational cost for best match search has been substantially reduced. A vector representation of the motion field, which is called projected principal-motion distribution (PPMD), has also been proposed. It was applied to preliminary motion recognition experiments using Hidden Markov Models (HMMs) and its effectiveness has been confirmed. Moreover the advantage of the proposed motion field generation method over the simple optical flow as well as the conventional block matching method using pixel intensities has been demonstrated.     

Status and verification of edge plasma turbulence code BOUT

The BOUT code is a detailed numerical model of tokamak edge turbulence based on collisional plasma fluid equations. BOUT solves for time evolution of plasma fluid variables: plasma density Ni, parallel ion velocity V‖i, electron temperature Te, ion temperature Ti, electric potential ?, parallel current j_‖, and parallel vector potential A_‖, in realistic 3D divertor tokamak geometry. The current status of the code, physics model, algorithms, and implementation is described. Results of verification testing are presented along with illustrative applications to tokamak edge turbulence.     

Simulation of ship wakes image by an along-track interferometric SAR

A mathematical model that allows simulations of the image of waves in ship wakes by either regular or interferometric airborne Synthetic Aperture Radar (SAR or INSAR) is described. The three-component velocity field induced at the ocean surface by a moving ship serves as the input to the model. The simulations take into account the effect of temporal variations of the wave field in the wake on the INSAR imaging by the velocity bunching mechanism. The model also accounts for the scanning distortion of the image. The developed algorithm allows study of the visibility of the ship wave wake by a regular SAR or by INSAR for arbitrary imaging parameters, as well as for different ship sizes and ship velocity vectors relative to the platform flight track. Various patterns of ship wake images obtained by numerical simulations are presented.     

Numerical analysis of turbulence decay in momentumless wakes behind a sphere and a prolate body of revolution

The numerical analysis of the characteristics of a turbulent flow in momentumless wakes behind a sphere and a prolate body of revolution in a homogeneous and linearly stratified media is performed. The results of the numerical simulation based on modern second- and third-order models of turbulence agree with the known theoretical and experimental data. The proximity between these flows in a number of inherent properties, including the self-similar turbulence decay in the far wake in a homogeneous medium and the interrelation between the second and third invariants of the Reynolds stress tensor are shown. The problem of the interaction between two regions of turbulent perturbations forming on the motion of a sphere and a prolate body of revolution in a homogeneous medium is considered.     

Dance motion generation by recombination of body parts from motion source

In this paper, we propose an approach to synthesize new dance routines by combining body part motions from a human motion database. The proposed approach aims to provide a movement source to allow robots or animation characters to perform improvised dances to music, and also to inspire choreographers with the provided movements. Based on the observation that some body parts perform more appropriately than other body parts during dance performances, a correlation analysis of music and motion is conducted to identify the expressive body parts. We then combine the body part movement sources to create a new motion, which differs from all sources in the database. The generated performances are evaluated by a user questionnaire assessment, and the results are discussed to understand what is important in generating more appealing dance routines.     

yoyo运动的实时轨迹生成

基于NTG（Nonlinear Trajectory Generation）软件包提出了一种机器人yoyo运动实时最优轨迹生成的通用方法,即数值解法,该方法也可以应用于其他类似周期性动态系统的轨迹规划问题。对于这类系统的实时最优控制来说,一个最为关键的问题就是如何实现快速求解最优轨迹,以满足实时性要求。而传统的数值求解方法都很费时。通过把最优问题映射一个较低维的空间进行求解,并且利用多线程编程技术,大大减少了计算所用的时间。仿真结果显示所求得的数值解与解析解完全相同,这也验证了该方法的正确性。单循环yoyo仿真的计算时间为10 ms左右,这表明该方法完全可以应用于实时控制。     

Human motion generation with multifactor models

To generate human motions with various specific attributes is a difficult task because of high dimensionality and complexity of human motions. This paper presents a novel human motion model for generating and editing motions with multiple factors. A set of motions performed by several actors with various styles was captured for constructing a well‐structured motion database. Subsequently, MICA (multilinear independent component analysis) model that combines ICA and conventional multilinear framework was adopted for the construction of a multifactor model. With this model, new motions can be synthesized by interpolation and through solving optimization problems for the specific factors. Our method offers a practical solution to edit stylistic human motions in a parametric space learnt with MICA model. We demonstrated the power of our method by generating and editing sideways stepping, reaching, and striding over obstructions using different actors with various styles. The experimental results show that our method can be used for interactive stylistic motion synthesis and editing. Copyright © 2011 John Wiley & Sons, Ltd.     

Semi-automatic cartoon generation by motion planning

To reduce tedious work in cartoon animation, some computer-assisted systems including automatic Inbetweening and cartoon reusing systems have been proposed. In existing automatic Inbetweening systems, accurate correspondence construction, which is a prerequisite for Inbetweening, cannot be achieved. For cartoon reusing systems, the lack of efficient similarity estimation method and reusing mechanism makes it impractical for the users. The semi-supervised graph-based cartoon reusing approach proposed in this paper aims at generating smooth cartoons from the existing data. In this approach, the similarity between cartoon frames can be accurately evaluated by calculating the distance based on local shape context, which is expected to be rotation and scaling invariant. By the semi-supervised algorithm, given an initial frame, the most similar cartoon frames in the cartoon library are selected as candidates of the next frame. The smooth cartoons can be generated by carrying out the algorithm repeatedly to select new cartoon frames after the cartoonists specifying the motion path in a background image. Experimental results of the candidate frame selection in our cartoon dataset suggest the effectiveness of the proposed local shape context for similarity evaluation. The other experiments show the excellent performance on cartoon generation of our approach.     

Simulation of isotropic turbulence degeneration based on the large-eddy method

In this paper, the simulation of isotropic turbulence degeneration is studied. The turbulent process is modeled based on filtered three-dimensional unsteady Navier-Stokes equations. For the closure of the main equations, a viscous model of turbulence is used. The problem is solved numerically, i.e., in solving the equation of motion the modified method of fractional steps using compact schemes is employed and the equation for pressure is solved by the Fourier method in combination with matrix factorization. Temporal variations in the kinetic energy of turbulence and changes in the micro scale of turbulence and longitudinal-transverse correlation functions have been obtained. Longitudinal and transverse one-dimensional spectra have been found.     

Improved finite volume discretisations of entropy generation and turbulence production

The finite volume discretisation of the rates of turbulence production and entropy generation commonly use cell centred differencing schemes. Whilst these are easy to derive they can result in discrepancies in solutions that are otherwise based on gradients approximated at cell faces. For example, a turbulent log law layer calculated using the k–? model can exhibit a spurious peak in the turbulence kinetic energy near the wall, or the volumetric rate of work calculated from entropy generation may not equal energy fluxes through domain boundaries. In this article new discretisations of turbulence production and entropy generation are derived that are based on derivatives centred at cell faces. These do not display the erroneous behaviours of the cell centre discretisations.     

边缘跟踪算法的图像线条画生成

给出一种基于边缘跟踪算法的图像线条画生成算法。该算法由边缘跟踪和线条画绘制两部分组成。在边缘跟踪中,提出基于相异性度量的边缘跟踪算法,以使利用边缘检测算子得到的边缘能够归类、连接;在线条画绘制过程中,引入非均匀B样条对不连续边缘进行插值并使用高斯平滑以获得连续光滑的边缘线条,然后以线条的曲率为依据,生成画笔,实现线条画的绘制。实验给出了本文方法生成的图像线条画的结果,实验结果表明,本文方法能够迅速快捷的生成较高质量的线条画。     

一种基于边折叠的LOD自动生成算法

多细节层次（LOD）是实时图形生成的一项重要技术。介绍了几种典型的多细节层次模型的自动生成算法，在此基础上提出了一种基于边折叠的多边形网格模型简化算法。实验表明，这种网格模型简化算法能在损失很少的屏幕像素误差的前提下提高图形绘制速度，是一种简单且有效的LOD自动生成算法。     

Ship wakes in radar imagery

In 1989 an experiment in Loch Linnhe, Scotland, was conducted to improve the understanding of radar images of internal-wave wakes generated by ships. During the experiment a multi-frequency synthetic-aperture radar (SAR) image containing several bright narrow V-shaped wakes was obtained during a period of low wind speed. One of the wakes imaged is caused by internal waves generated by a ship that was participating in the experiment. Three other wakes were also imaged which were generated by fishing vessels. The wakes of the fishing vessels are different in appearance to the internal-wave wake generated by the experiment ship. Given that the displacement of the fishing vessels is about four orders of magnitude less than the experiment ship it is unlikely that they could produce internal waves that could be detected by the radar. The fishing vessel wakes observed at two different radar frequencies can, however, be explained by the mechanism proposed by Munk et al. in 1987.     

High frequency lateral tape motion and the dynamics of tape edge contact

Lateral motion of magnetic tape is investigated on roller and porous air-bearing type tape drives. The lateral tape motion signal is high-pass filtered and the spectral components are analyzed. Time-frequency analysis is also performed. The effect of dynamic tension changes during high frequency lateral motion events is examined, and the tension difference across the tape head is found to be correlated to the lateral motion of tape near the head. The effect of lateral motion of tape on tape pack winding is investigated and the frequencies observed during edge contact are analyzed.     

Streamline generation code for particle dynamics description in numerical models of turbulence

Streamline Version 4 is a versatile Fortran 77 & C++ program for calculating charged test particle trajectories or field-lines for user-specified fields using the test-particle method. The user has the freedom to specify any type of field (analytical, tabulated in files, time dependent, etc.) and maintains complete control over initial conditions of trajectories/field-lines and boundary conditions of specified fields. The structure of Streamline was redesigned from previous versions in order to know not only particle or field-lines positions and velocities at each step of the simulations, but also the instantaneous field values as seen by particles. This was made to compute the instantaneous value of the particle’s magnetic moment, but other applications are possible too. Accuracy tests of the code are shown for different cases, i.e., particles moving in constant magnetic field, magnetic plus constant electric field and wave field. In addition in the last part of the paper we concentrate our discussion on the study of velocity space diffusion of charged particles in turbulent slab fields, paying attention to the discretization of the fields and the temporal discretization of the dynamical equations. The diffusion of charged particles is a very common topic in plasma physics and astrophysics since it plays an important role in many different phenomena such as stochastic particle acceleration, diffusive shock acceleration, solar energetic particle propagation, and the scattering required for the solar modulation of galactic cosmic rays.     

Tape edge wear and its relationship to lateral tape motion

The relationship between tape edge wear and lateral tape displacement is investigated for a typical 12.7 mm (1/2 inch) tape drive. Tape edge wear is measured using atomic force microscopy, while lateral tape displacement is measured using an optical edge sensor. The lateral displacement signal is high-pass and band-pass filtered to examine the effect of tape edge wear on the dynamics of lateral tape displacement. In addition, time frequency analysis of the lateral displacement signal is performed.     

Guided latent space regression for human motion generation

In the present work, we describe a mathematical model to generate human-like motion trajectories in space. We use linear regression in a latent space to find the model parameters from a set of demonstration examples.The learning procedure requires a relevant set of similar examples. The apprehended models encode both the typical shapes of motion and their variability towards specific boundary conditions (BC). We will show the added value of encoding both properties in a unique model and we apply this ability to common problems of error compensation and target tracking.The models allow us to describe human motion using expansion-function series (EFS), thus avoiding typical stability issues that arise in the use of differential equation models. To cope with variable scenarios, we show two specific algorithms that morph and adapt the evolution trajectory. In analogy to splines, the EFS preserve an analytical structure on which we develop the optimisation steps. In such a way, we managed to combine multiple single segments into complex motions that preserve continuity and may simultaneously optimise other criteria.In the present work, after having analysed similar tools, we present the basic model and its features. Then we develop a robust tool to gather the model from examples, and to achieve real-time trajectory adaptation. The achieved results will be analysed through an experimental analysis on data collected in a ball catching experiment.