Polarimetric whitening filter (PWF) can be used to polarimetric synthetic aperture radar (PolSAR) images improve the contrast between ships and sea clutter background. For this reason, output of detect ships. This paper deals with setting threshold over PolSAR filtered by PWF. Two parameter-constant false alarm rate (2P-CFAR) is a common detection method on whitened images. It assumes that probability density function (PDF) image intensity characterized log-normal distribution. However,...

For a multi-hydrophone synthetic aperture sonar (SAS), the instability of platform and underwater turbulence easily lead to two-dimensional (2-D) space-variant (SV) motion errors. Such errors can cause serious imaging problems are very difficult compensate for. In this study, we propose 2-D SV compensation algorithm for SAS based on sub-beam compensation. The proposed is implemented using following four-step process: (1) error each obtained by substituting sonar’s parameters measured in...

When a synthetic aperture sonar (SAS) system operates under low-frequency broadband conditions, the azimuth range coupling of point target reference spectrum (PTRS) is severe, and high-resolution imaging limited. To solve above issue, we first convert multi-receivers’ signal into equivalent monostatic then divide subblocks frequency subbands within each subblock in order. The terms are converted linear based on piece-wise approximation (PLA), phase error PTRS subband less than π/4. Then, use...

<abstract><p>In this paper, we study a class of $ p(x) $-biharmonic problems with negative nonlocal terms and weight function. Using the mountain pass theorem Ekeland's variational principle, at least three solutions are obtained. We also give some comments on existence infinite many for our problem when nonlinear term is general function.</p></abstract>

Uncompensated motion errors can seriously affect the imaging quality of synthetic aperture sonars (SASs). In existing line-by-line compensation (MOCO) algorithms for wide-beam multiple-receiver SAS systems, approximate form range history error usually introduces a significant approximation error, and residual two-dimensional (2D) cell migration (RCM) caused by aperture-dependent is not corrected, resulting in severe defocus image. this paper, presence translational rotational system, exact...

Laser interferometry is used in the Taiji program to detect gravitational waves ranging from 0.1 mHz 1 Hz, and picometer-level accuracy needs be achieved. Limited by interference of ground environment length test baseline, it difficult carry out experimental verification key technologies indicators on ground. Therefore, implementing a computer simulation based detection principles crucial. The method combining geometric wave optics adopted, corresponding models, including Gaussian beam its...

Aiming at the problem that existing imaging algorithms under wide beam conditions only consider relative range offset between different receivers, ignoring differential curvature, resulting in poor quality conditions, this paper proposes a Doppler algorithm for synthetic aperture sonar with multiple receivers considers curvature. Firstly, Signals from are corrected to central reference receiver domain, and spectrum aliasing is removed through coherent superposition. The signal equivalent...

In existing imaging algorithms for wide-beam multiple-receiver synthetic aperture sonar (SAS) systems, the double-square-root (DSR) range history of each receiver is generally converted into sum a single-square-root (SSR) and an error term using displaced phase center (DPCA) approximation. Therefore, before imaging, receiver’s needs to be individually compensated in azimuth frequency domain, which computationally expensive. As result, novel SAS system algorithm with low complexity high...

Background Visuospatial processing requires wide distribution or narrow focusing of attention to certain regions in space. This mechanism is described by the zoom lens model and predicts an inverse correlation between efficiency size attentional scope. Little known, however, about exact timing effects scaling on visual searching whether not additional phases are involved this process. Method Electroencephalographic recordings were made while participants performed a search task under...

To improve the imaging quality of conventional algorithms without motion compensation (MOCO) and efficiency point-by-point MOCO for multiple-receiver synthetic aperture sonar (SAS) with azimuth-invariant six-degree freedom (DOF) errors, an chirp scaling (CS) algorithm is presented in this paper. Taylor series approximation used to process range history double square root form, while considering fourth-order inner terms respect azimuth time. Using method reversion Fourier transform (FT)...

The medical CT image processing technology and an improved MC algorithm are used to reconstruct the defective skull model. A novel implementation of filling hole method is presented build surface that matches macro-shape region skull. final model scaffold obtained by a micro-structure constructing based on Boolean operation. proposed implemented programming, physical rapid prototyping process. Results show new can be construct both symmetrical unsymmetrical with proper micro-pore.

The constant false alarm rate (CFAR) detection method based on multi-look polarisation whitening filter (MPWF) has not been obtained in the polarimetric synthetic aperture radar imagery when texture variable obeys Inverse Beta distribution. To solve problem, a new CFAR with analytical expression for is proposed. First, probability density function (PDF) of output via MPWF derived hypothesis variables obeying distribution product model. Secondly, about threshold by integrating PDF output, and...

This paper is focused on α-generalized semantic resolution automated reasoning method in linguistic truth-valued lattice-valued propositional logic.Concretely, for latticevalued logic (L n × L 2 )P(X) equivalently transformed into that P(X)(i ∈ {1, 2, • , n}).A similar conclusion obtained between the V (n×2) P(X) and (n) n}).Secondly, generalized based a chain-type field investigated its soundness weak completeness are given.The Presented work provides some foundations resolution-based...

Simulating the detection process of a space-based gravitational wave (GW) measurement system is crucial for task demonstration, design, operation and data processing. Gaps glitches, which are common types abnormal events in process, an important part simulation. This paper explores two gap models three glitch models, provides comprehensive overview these models. The implementation Taiji Data, simulation program, designed. Dedicated software modules were developed to incorporate into process....