Peng-Bo Wei

GPU-Based Combination of GO and PO for Electromagnetic Scattering of Satellite

In the radar cross section (RCS) prediction of complex target, the intensive computational burden occurs while calculating the multiple scattering effect. In order to overcome the large computing, we present the program executing on graphics processing units (GPUs). In this paper, we analyze the scattering properties of the satellite, on which the antennas are described as cubes and columns, by employing the GPU-based combinational method of geometrical optics (GO) and physical optics (PO) together with the kd-tree technique. Furthermore, due to this distinctive treatment, the improved method yields a superior performance at high frequency. Some examples will be displayed in the following text. The agreement of the results yielded in this paper with the experimental and other exact results demonstrates the accuracy and efficiency of this useful technique.

Reliable Approach for Composite Scattering Calculation from Ship over a Sea Surface Based on FBAM and GO-PO Models

A reliable method based on facet-based asymptotical model, geometrical optics and physical optics (GO-PO) is developed to calculate composite scattering from 3-D complex ship targets over a rough sea surface. The backward ray-tracing is described to identify the visibilities of patches to the incident wave and the reflected wave of other patches on the target and facets on the sea surface. Both the scattering from target, including higher orders of scattering and the interactions between the target and rough sea surface, can be treated handily by the proposed GO-PO method. The accuracy of the target scattering and composite scattering is demonstrated by comparing with Multi-level fast multipole method (MLFMM), method of equivalent currents, and four-path model. Moreover, numerical examples of radar cross section estimation, electric current distribution, and synthetic aperture radar imagery simulation from a real ship target over a randomly rough sea surface are presented and discussed.

CUDA-Based SSA Method in Application to Calculating EM Scattering From Large Two-Dimensional Rough Surface

The small slop approximation (SSA) is an accurate method to calculate the electromagnetic (EM) scattering properties of rough surfaces. However, its computational complexity restricts its application to smaller domains and there is always the need for speedup in very large cases using pure central processing units (CPUs) hardware. With the development of graphics processing units (GPUs), more processors are dedicated to perform independent calculations. In addition, NVIDIA introduced a parallel computing platform, compute unified device architecture (CUDA), which provides researchers an easy way to use processors on GPU. To calculate EM scattering properties on GPU, we reformulate the SSA method with CUDA to take advantage of GPU threads. Because each thread executes synchronously and deals with a corresponding point data of rough surface, the CUDA-based SSA method calculates faster than the pure-CPU equivalent. To overcome memory limitations, the data of large rough surface are stored on hard disk. Moreover, a subsidiary thread is used to deal with the process of data transmission between the memory and the hard disk and reduce transmitting time further. The factors, block size, data transfers, and register, are also discussed in the optimization of the CUDA application. Test cases running on a NVIDIA GTX 460 GPU indicate that two orders of magnitude speedup, including file input and output, is obtained with our new formulation.

Spectral Decomposition Modeling Method and Its Application to EM Scattering Calculation of Large Rough Surface With SSA Method

The small slope approximation (SSA) method is a practical method to calculate the electromagnetic (EM) scattering from rough surfaces. However, the SSA method requires that the interval for sampling surfaces must be small enough, such as less than one-tenth of incident wavelength. This constraint condition will cause the problem of huge memory consumption and insufficient memory when the EM scattering of large rough surfaces is calculated. Although the hard disk has large space to keep data and can solve the insufficient memory problem, its read/write speed is still too slow. In addition, massive data transmission will reduce the computational efficiency for the compute unified device architecture (CUDA) parallel computation under some conditions. In this paper, the main idea of the spectral decomposition modeling method is that the whole spectrum of rough surface is divided into several parts and these parts can be used to generate different-scale rough surfaces. Then, by analyzing the different-scale rough surfaces, the large rough surface can be achieved and applied to the calculation of EM scattering with the SSA method. Due to the small memory consumption of different-scale rough surfaces, it takes less time to translate data for the different-scale rough surfaces than that for the standard large surface. Thus, the spectral decomposition modeling method could readily be applied to CUDA parallel computation.

An Improvement on SSA Method for EM Scattering From Electrically Large Rough Sea Surface

An improved facet model for the predication of the normalized radar cross section (NRCS) of electrically large rough sea surface was proposed based on the first-order small slope approximation (SSA-1) method, the Bragg scattering mechanism, and the specular scattering mechanism. The proposed method is able to evaluate both the complex reflective function and NRCS of electrically large sea surfaces from as low as ultrahigh frequency band to as high as Ka-band. The main idea is that a tilt sea facet can be regarded as the superposition of a planner facet and the microscopic profile; the latter is assumed to be a set of sinusoidal ripple patches. Thus, the integration kernel in SSA-1 over several small facets can be replaced by a large facet with a short wave modification. The efficiency increases because of the much larger mesh size than SSA. Then, both the backscattering and bistatic scattering NRCS results calculated by the proposed method were compared with those predicated by SSA-1, and all of the results show that the proposed method has the merits of high calculation efficiency as well as calculation accuracy.

Statistical realisation of CWMFSM for scattering simulation of space-time varying sea surface

ABSTRACT With the increasing demands of large maritime scene scattering prediction and also its high-resolution imaging simulation, the traditional two-scale scattering models, such as capillary wave modified facet scattering model (CWMFSM), appear to be inefficient and laborious when encountering scattering simulation of large maritime scene or long-time case. This paper proposes an effective and efficient approach, i.e. a statistical realisation of CWMFSM, for scattering simulation of space-time varying sea surface. Namely, this approach can give a fast and accurate simulation of large scene and long-time space–time varying sea surface scattering results using the memoryless non-linear transform method together with the statistic characteristics of results calculated by CWMFSM method. From the comparisons of texture feature, statistical characteristics and Doppler spectrum between the results derived from CWMFSM method and the statistical realisation, it is demonstrated that the proposed approach can give a pretty efficient simulation of space-time varying sea surface scattering with almost the same accuracy as the CWMFSM method itself. Similar with CWMFSM, the proposed approach can be applied to fields of sea surface scattering intensity distribution simulation, Doppler spectrum investigation of dynamic sea surface, composite scattering prediction of sea surface with multiple targets, SAR remote-sensing simulation of maritime scene, etc.

Space-Time Correlated Sea Scattering Map Simulation Based on Statistical Model

In numerous researching fields involving sea scattering problems, the electromagnetic (EM) scattering model becomes a better alternative rather than a direct experiment due to its low cost and easy realization. Nevertheless, the EM scattering model still appears to be slow and laborious when encountering the large scene or the long time case. This letter proposes an effective and efficient approach for 3-D space-time correlated sea scattering map simulation, an important step in real clutter simulation, which is based on the statistical characteristics from the EM scattering model. Namely, this approach can give a fast simulation of the large scene or long time space-time correlated sea scattering map through the statistic characteristics of that with a small scene or short time acquired by the EM scattering model. From the comparisons of the texture feature and the statistical characteristics between the results derived from the EM model and the proposed approach, it is demonstrated that the proposed approach can give a fast and effective simulation of the 3-D space-time correlated sea scattering map.

A New Model for Sand-Ripple Scattering Based on SSA Method and Practical Ripple Profiles

In the former model for sand surface electromagnetic (EM) scattering, the sand ripples are generally viewed as a standard sine-shaped wave surface, which artificially deprives many inherent properties of natural sand ripples. For example, the ripples have two pretty distinct sides: Y-junctions and variable texture directions. For these reasons, these corresponding scattering models deserve doubts to final calculated results. On the other hand, the former models usually are statistical models, which are not favorable in target coupling scattering problems and synthetic aperture radar (SAR) imaging simulations. In this paper, based on the physical mechanism governing the formation of aeolian landforms, sand ripples of actual shape are generated under the discrete models. Furthermore, as the slope of the ripple surface is fully small, facet-based small-slope approximation (SSA) method is unquestionably utilized in the EM scattering studies of sand ripples. Finally, significant differences are shown between the results based on sine-shaped wave surface and practical ripple surface, which proves the necessity of the new model for EM scattering of sand ripples.