Autonomous monitoring strategies are becoming an increasingly popular application modality due to their adaptable deployment and reconfigurability. Motivated by low-cost robotic swarms conveying ultrasonic transducers...
详细信息
Autonomous monitoring strategies are becoming an increasingly popular application modality due to their adaptable deployment and reconfigurability. Motivated by low-cost robotic swarms conveying ultrasonic transducers that are maneuverable into arrays for pipe inspections, this paper aims to develop an initial framework for predicting such an array's performance and understanding the effects of target defect scattering properties and array topology parameters on that performance. Assuming uniformly omnidirectional transducers, we first develop a predictive spatial probability of detection (POD) model that depends on target defect scattering and distance and verify it against experiment. We then synthesize these single-transducer models into arrays and derive global POD performance metrics that are parameterized by defect scattering properties (via the single transducer model) and array topology (geometric arrangement and transducer pitch). We perform a performance evaluation in the case of a highly directional scatterer (e.g., a crack) over the global parameter space to make suggestions about arraydesign.
This paper proposes a novel sparse array design and an efficient algorithm for two-dimensional direction-of-arrival (2D-DOA) estimation. By analyzing the hole distribution in coprime arrays and introducing supplementa...
详细信息
This paper proposes a novel sparse array design and an efficient algorithm for two-dimensional direction-of-arrival (2D-DOA) estimation. By analyzing the hole distribution in coprime arrays and introducing supplementary elements, we design a Complementary Coprime Planar array (CCPA) that strategically fills key holes in the virtual array. This design enhances the array's continuous Degrees Of Freedom (DOFs) and virtual aperture, achieving improved performance in 2D-DOA estimation with fewer physical elements. The virtualization of the array further increases the available DOFs, while the hole-filling strategy ensures better spatial coverage and continuity. On the algorithmic side, we introduce a dimensionality-reduction root MUSIC algorithm tailored for uniform planar arrays after virtualization. By decomposing the two-dimensional spectral peak search into two one-dimensional polynomial root-finding problems, the proposed method significantly reduces computational complexity while maintaining high estimation accuracy. This approach effectively mitigates the challenges of 2D peak search, making it computationally efficient without sacrificing precision. Extensive simulations demonstrate the advantages of the proposed array and algorithm, including higher DOFs, reduced complexity, and superior estimation performance compared to existing methods. These results validate the effectiveness of the proposed framework in advancing sparse array design and signal processing for 2D-DOA estimation.
In this paper, we explore the use of large-scale sparsearrays for pilot placement in pilot-based sensing within integrated sensing and communication (ISAC) systems. Unlike conventional regular pilot placement method,...
详细信息
ISBN:
(纸本)9798350344820;9798350344813
In this paper, we explore the use of large-scale sparsearrays for pilot placement in pilot-based sensing within integrated sensing and communication (ISAC) systems. Unlike conventional regular pilot placement method, sparse placement offers a significant reduction in overhead while maintaining high sensing performance. We present a novel large-scale sparsearray construction method by introducing a multi-tier array structure. Using the proposed method, the design of large-scale sparsearrays can be simplified into several smaller-sized arraydesign problems, significantly reducing computational complexity and storage requirements. Numerical examples demonstrate the effectiveness of the proposed method for low-overhead sensing pilot placement design, which is applicable in future 6G applications.
Large wideband two-dimensional (2-D) arrays are essential for high-resolution three-dimensional (3-D) ultrasound imaging. Since the tremendous element number of a full sampled large 2-D array is not affordable in any ...
详细信息
Large wideband two-dimensional (2-D) arrays are essential for high-resolution three-dimensional (3-D) ultrasound imaging. Since the tremendous element number of a full sampled large 2-D array is not affordable in any practical 3-D ultrasound imaging system, it is necessary to reduce the element number through sparse 2-D arraydesign. sparse array design requires that both the positions and weights of the array elements should be arbitrarily alterable. Hence a proper evaluation tool that can deal with arbitrary array is integral to optimizing the array structure and apodization function. It is known that pulse-echo point spread function (PSF) has been a common tool used to evaluate the performance of wideband arrays in ultrasound imaging all along, which also plays an important role in wideband ultrasound simulations. However, so far the conventional ultrasound simulation tools can only calculate pulse-echo PSF of arbitrary wideband arrays in the time domain because of the existence of nonuniform nodes in the spatial impulse response expressions, which obstructs their application of FFT to do fast computation of the time-domain convolutions. As a result, ultra-high time consumption of pulse-echo PSF computation of a large arbitrary wideband array hampers it to be taken as the evaluation tool by any stochastic optimization methods which need massive iterations in designing large sparse 2-D arrays. This paper aims to make available the pulse-echo PSF tool in designing large sparse 2-D arrays by proposing a fast computation method of far-field pulse-echo PSFs of arbitrary wideband arrays. In the paper, fast computation of wideband spatial impulse responses of a 2-D array is first realized in frequency domain by employing the nonuniform fast Fourier transform (NUFFT), under the point source assumption in far-field. On the basis of that, fast computation of time-domain convolutions is made possible by using FFT. In addition, a short inverse FFT (IFFT) is applied in recove
In phase-contrast magnetic resonance imaging (PC-MRI), spin velocity contributes to the phase measured at each voxel. Therefore, estimating velocity from potentially wrapped phase measurements is the task of solving a...
详细信息
In phase-contrast magnetic resonance imaging (PC-MRI), spin velocity contributes to the phase measured at each voxel. Therefore, estimating velocity from potentially wrapped phase measurements is the task of solving a system of noisy congruence equations. We propose Phase Recovery from Multiple Wrapped Measurements (PRoM) as a fast, approximate maximum likelihood estimator of velocity frommulti-coildatawith possible amplitude attenuation due to dephasing. The estimator can recover the fullest possible extent of unambiguous velocities, which can greatly exceed twice the highest venc. The estimator uses all pairwise phase differences and the inherent correlations among them to minimize the estimation error. Correlations are directly estimated frommulti-coil data without requiring knowledge of coil sensitivity maps, dephasing factors, or the actual per-voxel signal-to-noise ratio. Derivation of the estimator yields explicit probabilities of unwrapping errors and the probability distribution for the velocity estimate;this, in turn, allows for optimized design of the phase-encoded acquisition. These probabilities are also incorporated into spatial post-processing to further mitigate wrapping errors. Simulation, phantom, and in vivo results for three-point PC-MRI acquisitions validate the benefits of reduced estimation error, increased recovered velocity range, optimized acquisition, and fast computation. A phantom study at 1.5T demonstrates 48.5% decrease in root mean squared error using PRoM with post- processing versus a conventional "dual-venc" technique. Simulation and 3T in vivo results likewise demonstrate the proposed benefits. Index Terms-
We present extended Cantor arrays based on fourth-order difference co-arrays (E-FO-Cantor). These arrays result from extending the recently proposed fractal arrays to fourth-order difference co-arrays, and lead to fou...
详细信息
ISBN:
(纸本)9781728192017
We present extended Cantor arrays based on fourth-order difference co-arrays (E-FO-Cantor). These arrays result from extending the recently proposed fractal arrays to fourth-order difference co-arrays, and lead to fourth-order difference co-arrays that are hole-free. The set of sensor positions of the E-FO-Cantor is expressed in a simple and recursive form. The proposed Cantor arrays lead to O(N-2 log2 3) approximate to O(N-3.17) degrees of freedom compared to O(N-2) that can be achieved by existing sparsearrays with the hole-free property. Compared with other sparsearrays with the hole-free property in their fourth-order co-arrays, the proposed Cantor arrays provide a longer uniform linear array with more virtual sensors, leading to better DOA estimation performance.
sparsearrays on a moving platform can efficiently expand the numbers of achievable degrees of freedom (DOFs) and consecutive lags, improving direction-of-arrival (DOA) estimation. This property has been recently used...
详细信息
ISBN:
(纸本)9781728189420
sparsearrays on a moving platform can efficiently expand the numbers of achievable degrees of freedom (DOFs) and consecutive lags, improving direction-of-arrival (DOA) estimation. This property has been recently used for the case of environment-independent structured sparsearray configurations, such as those defined by nested and co-prime arrays. In this paper, we consider environment-dependent sparsearrays (EDSAs) design for mismatched DOA using Cramer-Rao bound (CRB) as the metric of optimality. The CRB is derived for multiple sources with angle biases. Two optimization metrics are considered, and solved by enumerations, to provide the optimum arrays. Simulation results are presented to validate the effectiveness of the proposed EDSA design.
The problem of optimum distribution of the available spatial degrees of freedom among two sparse antenna subarray beamfomers in shared aperture receiver is investigated. The two subarrays, forming a full array, co-exi...
详细信息
ISBN:
(纸本)9781538646588
The problem of optimum distribution of the available spatial degrees of freedom among two sparse antenna subarray beamfomers in shared aperture receiver is investigated. The two subarrays, forming a full array, co-exist on the same platform and could perform separate RF sensing and communications tasks. The sparsity and cardinality of the subarray configurations are joint optimization variables which considerably affect the output signal-to-interference plus noise ratios (SINR) of the two beamformer outputs. A minimum output SINR figure value is imposed to guarantee minimum performance. We solve this problem by utilizing Taylor series approximation to reformulate the initial non-convex problem to a convex one. Simulation results validate the effectiveness of the proposed method.
The problem of optimum distribution of the available spatial degrees of freedom among two sparse antenna subarray beamfomers in shared aperture receiver is investigated. The two subarrays, forming a full array, co-exi...
详细信息
ISBN:
(纸本)9781538646595
The problem of optimum distribution of the available spatial degrees of freedom among two sparse antenna subarray beamfomers in shared aperture receiver is investigated. The two subarrays, forming a full array, co-exist on the same platform and could perform separate RF sensing and communications tasks. The sparsity and cardinality of the subarray configurations are joint optimization variables which considerably affect the output signal-to-interference plus noise ratios (SINR) of the two beamformer outputs. A minimum output SINR figure value is imposed to guarantee minimum performance. We solve this problem by utilizing Taylor series approximation to reformulate the initial non-convex problem to a convex one. Simulation results validate the effectiveness of the proposed method.
Two of the most important criteria for a sensor array beam-pattern are beamwidth and side-lobe level. A narrower beamwidth means a better angular resolution and well separation of close sources. The beamwidth of a sen...
详细信息
暂无评论