Electromagnetic optimization utilizing finite element or similar numerical techniques always carries a heavy burden of computation;therefore, an efficient optimizer reducing the number of objective function calls to f...
详细信息
Electromagnetic optimization utilizing finite element or similar numerical techniques always carries a heavy burden of computation;therefore, an efficient optimizer reducing the number of objective function calls to find the optimum accurately is essential. Kriging as a regression model is able to locate the optimum;meanwhile, it also can produce the response surface of objective function only based on the spatial correlation of limited information. However, the storage of correlation matrices generated by a kriging optimizer, along with the iterative optimization process, is an issue in the context of the electromagnetic optimization problems with many design variables and multiple optimal objectives. The proposed hybrid kriging methodology incorporating a direct algorithm is able to maintain memory occupation of the optimizer as a nearly constant level. It performs efficiently and reliably while coping with the large-scale multivariable optimization tasks. The feasibility and efficiency of the proposed hybrid kriging are verified via a classic analytic function and the multivariable benchmark TEAM Workshop problem 22.
This paper presents a practical projector-camera based 3D object modelling system developed in our laboratories. The hardware consists of a computer, a video projector and at least two digital cameras. The 3D modellin...
详细信息
This paper presents a practical projector-camera based 3D object modelling system developed in our laboratories. The hardware consists of a computer, a video projector and at least two digital cameras. The 3D modelling of a real object is realized automatically by applying an adaptive spot projection technique. For each spot in the first image, an algorithm is applied to find its correspondence in the second one, thus a cloud of 3D points is finally generated by triangulation, which is necessary for the calculation of the geometry of the object. In the case that the surface of the object is irregular, an iterative optimization process is lanced to improve the 3D reconstruction speed and the precision of the reconstructed model.
A recently proposed antenna measurement technique based on impedance or reflection coefficient measurements with varying reflective objects in front of an antenna is reviewed. The method allows radiation pattern deter...
详细信息
ISBN:
(纸本)9781479936786
A recently proposed antenna measurement technique based on impedance or reflection coefficient measurements with varying reflective objects in front of an antenna is reviewed. The method allows radiation pattern determination without moving cables which are subject to changes in their electrical length and attenuation during conventional antenna measurements. In addition, a modification to the method is introduced in order to speed up the involved iterative optimization process.
The accuracy of training samples used for data classification methods, such as support vector machines (SVMs), has had a considerable positive impact on the results of urban area extractions. To improve the accuracy o...
详细信息
The accuracy of training samples used for data classification methods, such as support vector machines (SVMs), has had a considerable positive impact on the results of urban area extractions. To improve the accuracy of urban built-up area extractions, this paper presents a sample-optimized approach for classifying urban area data using a combination of the Defense Meteorological Satellite Program-Operational Linescan System (DMSP-OLS) for nighttime light data, Landsat images, and GlobeLand30, which is a 30-m global land cover data product. The proposed approach consists of three main components: (1) initial sample generation and data classification into built-up and non-urban built-up areas based on the maximum and minimum intervals of digital numbers from the DMSP-OLS data, respectively;(2) refined sample selection and optimization by the probability threshold of each pixel based on vegetation-cover, using the Landsat-derived normalized differential vegetation index (NDVI) and artificial surfaces extracted from the GlobeLand30 product as the constraints;(3) iterative classification and urban built-up area data extraction using the relationship between these three aspects of data collection together with the training sets. Experiments were conducted for several cities in western China using this proposed approach for the extraction of built-up areas, which were classified using urban construction statistical yearbooks and Landsat images and were compared with data obtained from traditional data collection methods, such as the threshold dichotomy method and the improved neighborhood focal statistics method. An analysis of the empirical results indicated that (1) the sample training process was improved using the proposed method, and the overall accuracy (OA) increased from 89% to 96% for both the optimized and non-optimized sample selection;(2) the proposed method had a relative error of less than 10%, as calculated by an accuracy assessment;(3) the overall and indiv
暂无评论