一个面向异构多UUV协作任务的分层式控制系统

针对异构多UUV协作任务,提出了基于多智能体系统的分层式体系结构(MAHA).在个体层面,将UUV智能体的思维状态分为社会心智和个体心智两个层次分别实现,更加符合人类社会协作模式;在群体层面,提出了复杂海洋环境下UUV群体结构的评价准则,并据此将MAHA与现有结构进行了对比分析.此外,利用面向对象的Petri网理论建立了系统的协作模型,有效降低了系统建模的复杂性.最后,水下多目标搜索使命的实例研究表明,MAHA能够保证异构UUV之间进行有效的协作.

Surface modelling of soil pH

In addition to classical methods, namely kriging, Inverse Distance Weighting (IDW) and splines, which have been frequently used for interpolating the spatial patterns of soil properties, a relatively more accurate surface modelling technique is being developed in recent years, namely high accuracy surface modelling (HASM). It has been used in the numerical tests, DEM construction and the interpolation of climate and ecosystem changes. In this paper, HASM was applied to interpolate soil pH for assessing its feasibility of soil property interpolation in a red soil region of Jiangxi Province, China. Soil pH was measured on 150 samples of topsoil (0-20 cm) for the interpolation and comparing the performance of HASM, kriging. IDW and splines. The mean errors (MEs) of interpolations indicate little bias of interpolation for soil pH by the four techniques. HASM has less mean absolute error (MAE) and root mean square error (RMSE) than kriging, IDW and splines. HASM is still the most accurate one when we use the mean rank and the standard deviation of the ranks to avoid the outlier effects in assessing the prediction performance of the four methods. Therefore, HASM can be considered as an alternative and accurate method for interpolating soil properties. Further researches of HASM are needed to combine HASM with ancillary variables to improve the interpolation performance and develop a user-friendly algorithm that can be implemented in a GIS package. (C) 2009 Elsevier B.V. All rights reserved.