基于求积分卡尔曼滤波的交互式多模型算法

针对非线性系统中的多模型估计问题,将求积分卡尔曼滤波算法应用到交互式多模型算法过程中,提出一种基于求积分卡尔曼滤波的交互式多模型算法.该算法不需要求取非线性方程的雅可比矩阵,且能够获得比基于不敏卡尔曼滤波的交互式多模型方法更高的滤波精度.仿真结果证明了该算法的有效性.     

交互式多模型算法的模型集设计

针对交互式多模型（IMM）算法中模型集的设计问题，提出一种模型集设计方法．在已知真实模式概率分布函数的情况下，根据要求的模型数目，等概率划分模式空间，在每个等概率模式空间上，利用方差的含义获得最大范围地覆盖模式空间的模型集，并给出一个例子说明模型集的设计方法．应用Monte-Carlo仿真．将所设计的模型集用于IMM算法进行目标跟踪．仿真结果显示跟踪精度高，表明了该模型集设计方法的有效性．     

Experimental investigation of natural convection heat exchange within a physical model of the manifold chamber of a thermosyphon heat-pipe evacuated tube solar water heater

The high capital costs associated with heat-pipe evacuated tube solar water heating systems can be reduced by replacing forced circulation with thermosyphon circulation. Currently research on thermosyphon heat-pipe evacuated tube solar water heaters is limited. An experimental investigation of the natural convective heat exchange regime that exists within the manifold chamber of a proprietary heat-pipe evacuated tube solar water was undertaken. This paper presents experimental data from a heat-pipe Evacuated Tube Solar Water Heater (ETSWH) subjected to the Northern Maritime Climate at the University of Ulster’s outdoor solar testing facility located at the Jordanstown campus. The thermal performance of this across solar noon (±30 min) was experimentally determined to be comparable to two physical laboratory 10 pin-fin model manifolds constructed to the same dimensions and geometry as the manifold chamber of the heat-pipe ETSWH when operated under steady laboratory conditions. When the surface temperatures of the pin-fins (simulated condensers) in the model manifold were normalised with respect to the lowest most pin-fin in the array the influence of buoyant flow was observed. Similarly to related studies in this field it was found that normalised surface temperatures on downstream pin-fins do not increase monotonically as would be expected if no interactions occur. It was found that at the pin-fin diameter to pitch used in the model manifold that normalised surface temperatures decrease at certain points in the array due to the action of buoyant flow generated from upstream pin-fins which increased heat transfer. Two-dimensional Particle Imaging Velocimetry (2D-PIV) was used to visualise the thermosyphon fluid flow regime. It was observed that the fluid flow regime varied across the model due to interactions between the fluid, chamber walls and pin-fins.     

两夹角不渗透断层对油井压力及压力导数的影响研究

利用镜像映射和叠加原理推导了理想油藏中油井位于两夹角(θ)不渗透断层间定产量生产时的井底压力及压力导数表达式,分析了夹角不渗透断层对油井压力及压力导数的影响,并得出结论:油井无论位于夹角断层间哪一位置,其压力半对数曲线上均出现斜率为径向流第一直线段斜率360°/θ倍的第二直线段,压力导数曲线上出现值为360°/θ×0.5的第二水平线。     

Discrete and continuous models of the dynamics of pelagic fish: Application to the capelin

In this paper, we study simulations of the schooling and swarming behavior of a mathematical model for the motion of pelagic fish. We use a derivative of a discrete model of interacting particles originated by Vicsek and Czirók et al. [A. Czirók, T. Vicsek, Collective behavior of interacting self-propelled particles, Physica A 281 (2000) 17–29; A. Czirók, H. Stanley, T. Vicsek, Spontaneously ordered motion of self-propelled particles, Journal of Physics A: Mathematical General 30 (1997) 1375–1385; T. Vicsek, A. Czirók, E. Ben-Jacob, I. Cohen, O. Shochet, Novel type of phase transition in a system of self-driven particles, Physical Review Letters 75 (6) (1995) 1226–1229; T. Vicsek, A. Czirók, I. Farkas, D. Helbing, Application of statistical mechanics to collective motion in biology, Physica A 274 (1999) 182–189]. Recently, a system of ODEs was derived from this model [B. Birnir, An ODE model of the motion of pelagic fish, Journal of Statistical Physics 128 (1/2) (2007) 535–568], and using these ODEs, we find transitory and long-term behavior of the discrete system. In particular, we numerically find stationary, migratory, and circling behavior in both the discrete and the ODE model and two types of swarming behavior in the discrete model. The migratory solutions are numerically stable and the circling solutions are metastable. We find a stable circulating ring solution of the discrete system where the fish travel in opposite directions within an annulus. We also find the origin of noise-driven swarming when repulsion and attraction are absent and the fish interact solely via orientation.     

Parallel and interacting Markov chain Monte Carlo algorithm

In many situations it is important to be able to propose N independent realizations of a given distribution law. We propose a strategy for making N parallel Monte Carlo Markov chains (MCMC) interact in order to get an approximation of an independent N-sample of a given target law. In this method each individual chain proposes candidates for all other chains. We prove that the set of interacting chains is itself a MCMC method for the product of N target measures. Compared to independent parallel chains this method is more time consuming, but we show through examples that it possesses many advantages. This approach is applied to a biomass evolution model.     

Reconstruction of 3D interacting solids of revolution from 2D orthographic views

3D CAD is replacing 2D CAD to improve efficiency of product design and manufacturing. Therefore, converting legacy 2D drawings into 3D solid models is required. CSG based approaches reconstruct solid models from orthographic views more efficiently than traditional B-rep based approaches. A major limitation of CSG based approaches has been the limited domain of objects that can be handled. This paper aims at extending the capabilities of CSG based approaches by proposing a hint-based recognition of interacting solids of revolution. This approach can handle interacting solids of revolution as well as isolated solids of revolution.     

IMM/MHT fusing feature information in visual tracking

In multi-target tracking, Multiple Hypothesis Tracking (MHT) can effectively solve the data association problem. However, traditional MHT can not make full use of motion information. In this work, we combine MHT with Interactive Multiple Model (IMM) estimator and feature fusion. New algorithm greatly improves the tracking performance due to the fact that IMM estimator provides better estimation and feature information enhances the accuracy of data association. The new algorithm is tested by tracking tropical fish in fish container. Experimental result shows that this algorithm can significantly reduce tracking lost rate and restrain the noises with higher computational effectiveness when compares with traditional MHT.     

Hand tracking in a natural conversational environment by the interacting multiple model and probabilistic data association (IMM-PDA) algorithm

Traditional image based hand tracking algorithms use a single model Kalman filter to estimate and predict the hand state (position, velocity, and acceleration) and do not consider multiple measurements with noise and false alarms. However, these approaches may fail in the case of large maneuvers and/or a clutter measurement environment. In this paper, we apply the interacting multiple model (IMM) to catch hand maneuvers and the probabilistic data association (PDA) method to process noisy measurements and false alarms. A theoretical framework of image based hand tracking by the IMM-PDA algorithm is set up. Experiment results from several long video segments show that the IMM-PDA algorithm gives a superior performance compared to single model based Kalman filters.