一种改进的自适应网格交互多模型跟踪算法

自适应网格交互多模算法能够根据目标的运动模式,自适应调整系统各模型参数,从而实现对目标的跟踪。但当目标机动性较大时,在其模式变换时刻,网格中心剧烈摆动,导致跟踪精度下降。提出对该算法的改进,通过对网格中心运动步长进行适当的平滑处理,以增加网格的平稳性。仿真给出了平滑因子的经验值,并表明改进的自适应网格交互多模算法能解决传统算法在目标运动模式变换时跟踪不稳定的问题,提高精度跟踪。

任意横截面形状非均匀介质波导传输特性的分析

用阶梯近似与边缘元和模匹配相结合的方法分析了一大类任意横截面形状非均匀介质波导的传输特性 .将非均匀部分用一系列级联的台阶近似 ,各台阶用微波多模网络等效 .用边缘元方法求得各本地波导的本征值问题后 ,用模匹配法算出各微波网络的散射参数 ,最后通过级联的微波网络求得整个非均匀结构的传输特性 .由于边缘元方法的通用性 。

Multiresolution analysis over triangle meshes: method and data structure

A robust and efficient algorithm is presented to build multiresolution models (MRMs) of arbitrary meshes without requirement of subdivision connectivity. To overcome the sampling difficulty of arbitrary meshes, edge contraction and vertex expansion are used as downsampling and upsampling methods. Our MRMs of a mesh are composed of a base mesh and a series of edge split operations, which are organized as a directed graph. Each split operation encodes two parts of information. One is the modification to the mesh, and the other is the dependency relation among splits. Such organization ensures the efficiency and robustness of our MRM algorithm. Examples demonstrate the functionality of our method.

An Algorithm of the Adaptive Grid and Fuzzy Interacting Multiple Model

This paper studies the algorithm of the adaptive grid and fuzzy interacting multiple model （AGFIMM） for maneuvering target tracking, while focusing on the problems of the fixed structure multiple model （FSMM） algorithm＇s cost-efficiency ratio being not high and the Markov transition probability of the interacting multiple model （IMM） algorithm being difficult to determine exactly. This algorithm realizes the adaptive model set by adaptive grid adjustment, and obtains each model matching degree in the model set by fuzzy logic inference. The simulation results show that the AGFIMM algorithm can effectively improve the accuracy and cost-efficiency ratio of the multiple model algorithm, and as a result is suitable for enineering apolications.

Equality Testing for Soil Grid Unit Resolutions to Polygon Unit Scales with DNDC Modeling of Regional SOC Pools

Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of China.Both soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map scales.Four indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid units.Subjecting to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC pools.Optimal soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map scales.With these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV < 1% was assumed to be a criterion for all four indices.A quadratic curve regression model,namely,y = – 0.80 × 10^(–6)x^2 + 0.0228 x + 0.0211(R^2 = 0.9994,P < 0.05),and a power function model R? = 10.394?^(0.2153)(R^2 = 0.9759,P < 0.05) were revealed,which describe the relationship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km^2) and the ?,with the highest R^2 among different mathematical regressions,respectively.This knowledge may facilitate the grid partitioning of regions during the investigation and simulation of SOC pool dynamics at a certain map scale,and be referenced to other landscape polygon patches' mesh partition.

3D Engineering Model Retrieval Based on Enhanced Shape Distributions

To reuse and share the valuable knowledge embedded in repositories of engineering models for accelerating the design process, improving product quality, and reducing costs, it is crucial to devise search engines capable of matching 3D models efficiently and effectively. In this paper, an enhanced shape distributions-based technique of using geometrical and topological information to search 3D engineering models represented by polygonal meshes was presented. A simplification method of polygonal meshes was used to simplify engineering model as the pretreatment for generation of sample points. The method of sampling points was improved and a pair of functions that was more sensitive to shape was employed to construct a 2D shape distribution. Experiments were conducted to evaluate the proposed algorithm utilizing the Engineering Shape Benchmark (ESB) database. The experiential results suggest that the search effectiveness is significantly improved by enforcing the simplification and enhanced shape distributions to engineering model retrieval.

Research on a Multi-grid Model for Passenger Evacuation in Ships

In order to enhance the authenticity and accuracy of passenger evacuation simulation in ships, a new multi-grid model was proposed on the basis of a traditional cellular automata model. In the new model finer lattices were used, interaction of force among pedestrians or between pedestrians and constructions was considered, and static floor fields in a multi-level exit environment were simplified into cabin and exit static floor fields. Compared with the traditional cellular automata model, the multi-grid model enhanced the continuity of the passengers'track and the precision of the boundary qualifications. The functions of the dislocation distribution of passengers as well as partial overlap of tracks due to congestion were realized. Furthermore, taking the typical cabin environment as an example, the two models were used to analyze passenger evacuation under the same conditions. It was found that the laws of passenger evacuation simulated by the two models are similar, while the simulation's authenticity and accuracy are enhanced by the multi-grid model.

Numerical simulation on conjugate heat transfer of turbine cascade

Numerical simulation on conjugate heat transfer of an internal cooled turbine vane was carried out. Numerical techniques employed included the third-order accuracy TVD scheme, multi-block structured grids and the technique of arbitrary curved mesh. Comparison between results of commercial CFD codes with several turbulence models and those of this code shows that it is incorrect of commercial CFD codes to predict the thermal boundary layer with traditional turbulence models, and that turbulence models considering transition lead to more accurate heat transfer in thermal boundary layer with some reliability and deficiency yet. The results of this code are close to those of CFX with transition model.

SDOG-based multi-scale 3D modeling and visualization on global lithosphere

The structure of global lithosphere is very important to the scientific researches of tectonic movement, geodynamic process, mantle convection, resource exploration, and disaster prevention and reduction. Three-dimensional (3D) spatial modelling and visualization is an effective tool for lithosphere researches. However, both the isoline/profile methods and the Euclidean-based 3D modelling methods cannot meet the requirement of real 3D modeling of global lithosphere, whereas the recently developed global 3D grid methods have some defects on grid design, such as grid shrinkage, overlapping, non-orthogonality, and nonlatitude-longitude consistency. In this paper, Spheroid Degenerated-Octree Grid (SDOG), a non-overlapping, non-shrinking, orthogonal, latitude-longitude consistent grid in the spheroidal manifold space, was chosen as the basic grid for global lithosphere 3D modeling and visualization. The SDOG-based methods of spatial representation and modelling of lithosphere were proposed. A multi-scale model of lithosphere was designed, and the multi-scale modeling and multi-mode visualization were realized at the full advantages of SDOG in multi-hierarchical and multi-resolution and the properties of lithosphere in multi-semantic. It shows that (1) the SDOG-based method has not only overcome the defects of the current global 3D grid, but also reflected the spherical features of lithosphere more realistically and naturally than the traditional methods, providing a novel solution for global modeling, numeric simulating, and data sharing of lithosphere; and (2) more detailed plates division, more precise geo-layer structure, plates boarder and surface concave-convex, and more rich lithosphere properties are revealed as the scale-model moves on.