Spread-Doppler clutter caused by multi-mode propagation seriously affects the over-the-horizon radar detection performance for slow ships. To solve this problem, the authors propose to suppress multi-mode clutter usin...
详细信息
Spread-Doppler clutter caused by multi-mode propagation seriously affects the over-the-horizon radar detection performance for slow ships. To solve this problem, the authors propose to suppress multi-mode clutter using spatial information in the multiple-input-multiple-output over-the-horizon radar system. Traditional processing algorithms need prior information of the target direction. However, it is often not readily available. In this study, they propose a novel multi-mode clutter suppression algorithm based on the second-order blind identification (SOBI) technique. The proposed algorithm does not need prior information of the target direction and can effectively suppress the multi-mode clutter. Considering that the SOBI algorithm affected by the similarity in sources spectra, they improve the proposed algorithm using the spatial smoothing technique. Simulation results show that, in the single target scene, the improved algorithm can effectively eliminate the spectrum burrs caused by incomplete separation, making separated signals smoother. Signal-to-clutter-noise ratio is greatly improved. The good multi-mode clutter suppression performance is obtained. In the multi-mode scenario that double targets with the same radial velocity, that is, sources spectra have similarities, the algorithm based on SOBI cannot separate all targets. Although the improved algorithm can make all targets visible and effectively suppresses the multi-mode clutter.
We provide an algorithm for computing the centered Hausdorff measures of self-similar sets satisfying the strong separation condition. We prove the convergence of the algorithm and test its utility on some examples. (...
详细信息
We provide an algorithm for computing the centered Hausdorff measures of self-similar sets satisfying the strong separation condition. We prove the convergence of the algorithm and test its utility on some examples. (C) 2011 Elsevier Ltd. All rights reserved.
Covalent modifications on therapeutic proteins are traditionally monitored by chromatographic techniques, which quantify limited number of protein modifications at a time. In this report, computer algorithms for autom...
详细信息
Covalent modifications on therapeutic proteins are traditionally monitored by chromatographic techniques, which quantify limited number of protein modifications at a time. In this report, computer algorithms for automated analyses of liquid chromatography/tandem mass spectrometry (LC/MS/MS) data for large-scale identification and quantification of known and unknown modifications are described. Peptide identification is achieved by comparing the experimental fragmentation spectrum to the predicted spectrum of each native or modified peptide. Peak areas of related peptide ions under their selected-ion chromatograms (SIC) are used for relative quantification of modified peptides. A matched window function is used to generate SIC for more reliable quantification. In an LC/MS/MS analysis of a tryptic digestion of an IgG2 monoclonal antibody, 1712 peptide ions were identified with a false-discovery rate of similar to 0.4%, and 227 modifications were identified and quantified. The accuracy of the mass spectrometry-based quantification is evaluated by comparing the abundance of different glycoforms determined by mass spectrometry to that determined by a fluorescence-based chromatography method. This large-scale method may potentially replace many chromatographic methods for assessing the quality attributes of therapeutic proteins.
This paper gives algorithms for determining real-valued univariate unimodal regressions, that is, for determining the optimal regression which is increasing and then decreasing. Such regressions arise in a wide variet...
详细信息
This paper gives algorithms for determining real-valued univariate unimodal regressions, that is, for determining the optimal regression which is increasing and then decreasing. Such regressions arise in a wide variety of applications. They are shape-constrained nonparametric regressions, closely related to isotonic regression. For unimodal regression on n weighted points our algorithm for the L-2 metric requires only Theta(n) time, while for the L-1 metric it requires Theta(n log n) time. For unweighted points our algorithm for the L. metric requires only Theta(n) time. All of these times are optimal. Previous algorithms were for the L-2 metric and required Omega(n(2)) time. All previous algorithms used multiple calls to isotonic regression, and our major contribution is to organize these into a prefix isotonic regression, determining the regression on all initial segments. The prefix approach reduces the total time required by utilizing the solution for one initial segment to solve the next. (C) 2008 Elsevier B.V. All rights reserved.
Using the dynamic properties of fractional-order Duffing system, a sequential parameter identification method based on differential evolution optimization algorithm is proposed for the fractional-order Duffing system....
详细信息
Using the dynamic properties of fractional-order Duffing system, a sequential parameter identification method based on differential evolution optimization algorithm is proposed for the fractional-order Duffing system. Due to the step by step parameter identification method, the dimension of parameter identification of each step is greatly reduced and the search capability of the differential evolution algorithm has been greatly improved. The simulation results show that the proposed method has higher convergence reliability and accuracy of identification and also has high robustness in the presence of measurement noise.
Inspired by the advanced capabilities of fish-like swimmers, we seek a greater understanding of the hydrodynamic mechanisms they employ. Borrowing tools from geometric mechanics, we develop a large-amplitude gait desi...
详细信息
Inspired by the advanced capabilities of fish-like swimmers, we seek a greater understanding of the hydrodynamic mechanisms they employ. Borrowing tools from geometric mechanics, we develop a large-amplitude gait design technique for self-propelling deformable swimmers in potential flow and Stokes flow. Additionally, a heuristically-developed control algorithm is implemented to nearly optimize thrust-generation for a swimmer moving through its own nearly-periodic vortex wake.
This paper describes the experimental comparison among four model-based control algorithms on a direct-drive robotic arm. We present experimental results of the following controllers: Computed-Torque control, PD + con...
详细信息
This paper describes the experimental comparison among four model-based control algorithms on a direct-drive robotic arm. We present experimental results of the following controllers: Computed-Torque control, PD + control, PD control with computed feedforward and PD control. All controllers include Coulomb and viscous friction compensation as well as cancellation of gravitational torques. They are tested under common trajectory specification and performance index. (C) 2000 Elsevier Science Ltd. All rights reserved.
We are proposing a multiresolution representation which uses a subdivision surface as a smooth base surface with respect to which a high resolution mesh is defined by normal displacement. While this basic representati...
详细信息
We are proposing a multiresolution representation which uses a subdivision surface as a smooth base surface with respect to which a high resolution mesh is defined by normal displacement. While this basic representation is quite straightforward, our actual contribution ties in the automatic generation of such a representation. Given a high resolution mesh, our algorithm is designed to derive a subdivision control mesh whose structure is properly adjusted and aligned to the major geometric features. This implies that the control vertices of the subdivision surface not only control globally smooth deformations but in addition that these deformations are meaningful in the sense that their support and shape correspond to the characteristic structure of the input mesh. This is achieved by using a new decimation scheme for general polygonal meshes (not just triangles) that is based on face merging instead of edge collapsing. A face-based integral metric makes the decimation scheme very robust such that we can obtain extremely coarse control meshes which in turn allow for deformations with large support.
By exploiting the direction of arrival (DoA) information of azimuth ambiguity, an innovative algorithm for the adaptive suppression of azimuth ambiguity for multichannel synthetic aperture radar (SAR) wide-swath imagi...
详细信息
By exploiting the direction of arrival (DoA) information of azimuth ambiguity, an innovative algorithm for the adaptive suppression of azimuth ambiguity for multichannel synthetic aperture radar (SAR) wide-swath imaging is presented. It firstly estimates the DoA value of each azimuth component within a Doppler cell using the efficient noise subspace-based iterative estimation technique. Then the spatial filter for sequentially extracting the desired azimuth component is derived, which is designed to be used with the newly estimated DoA information within each Doppler bin. Finally, the azimuth ambiguities can be suppressed via the implementation of spatial filtering. The proposed approach is robust to aircraft velocity errors, and its effectiveness is validated via simulation results.
In this paper, mobile robot navigation on a 3D terrain with a single obstacle is addressed. The terrain is modelled as a smooth, complete manifold with well-defined tangent planes and the hazardous region is modelled ...
详细信息
In this paper, mobile robot navigation on a 3D terrain with a single obstacle is addressed. The terrain is modelled as a smooth, complete manifold with well-defined tangent planes and the hazardous region is modelled as an enclosing circle with a hazard grade tuned radius representing the obstacle projected onto the terrain to allow efficient path-obstacle intersection checking. To resolve the intersections along the initial geodesic, by resorting to the geodesic ideas from differential geometry on surfaces and manifolds, we present a geodesic-based planning and replanning algorithm as a new method for obstacle avoidance on a 3D terrain without using boundary following on the obstacle surface. The replanning algorithm generates two new paths, each a composition of two geodesics, connected via critical points whose locations are found to be heavily relying on the exploration of the terrain via directional scanning on the tangent plane at the first intersection point of the initial geodesic with the circle. An advantage of this geodesic path replanning procedure is that traversability of terrain on which the detour path traverses could be explored based on the local Gauss-Bonnet Theorem of the geodesic triangle at the planning stage. A simulation demonstrates the practicality of the analytical geodesic replanning procedure for navigating a constant speed point robot on a 3D hill-like terrain.
暂无评论