Rectangular Array Research Articles

Application of adaptive finite focus beamforming method for localization of low-frequency transformer sound

In this paper, the developed adaptive linearly constrained minimum variance finite focus beamforming method is used to increase the accuracy and resolution of low-frequency transformer sound source localization. In the first step, simulations on virtual arrays are conducted to define the array size and compare the influence of three different beamforming algorithms on sound localization accuracy and resolution. In the second step, measurements of the regulating transformer as a noise source are conducted in the semi-anechoic chamber. A large rectangular microphone array, with 90 microphone positions spaced 0.44 meters apart, is used for that purpose. The developed algorithm is compared with infinite and finite focus beamforming for the localization of total noise and noise at specific noise harmonics.

Synthesis of Antenna Array Radiation Pattern at Large Scanning Angles Using Genetic Algorithm

At present, in most modern communication systems, for example, in modern satellite terminals, the use of scanning beam antennas, i. e. antenna arrays is assumed. At the same time, at large scanning angles, the side lobe level (SLL) increases strongly and decrease in the gain is observed. In this regard, the problem of finding a procedure for synthesizing an amplitude-phase distribution (APD) with low SLL and high gain (G) at large scanning angles comes up. One of the ways to reduce SLL and compensate for the decrease in G is to synthesize the optimal APD (in terms of the maximum G and minimum SLL) using optimization algorithms. At the same time, taking into account the characteristics of the radiation pattern of the array emitters requires numerical electrodynamic calculation. The goal of this paper is to develop a procedure for the synthesis of APD with low SLL for linear and rectangular antenna arrays at various, including large, scanning angles and compensation for G reduction using a genetic algorithm and numerical electrodynamic calculation. The methods for studying the characteristics of antenna radiators are numerical electrodynamic modeling by the finite element method (FEM) in Ansys HFSS computer-aided design system and optimization of the APD for a given radiation pattern(RP) by a random search method using partial diagrams of antenna elements. The novelty is the combination of accurate numerical electrodynamic calculation of the RP of antenna elements and optimization search for APD for the synthesis of the required RP using partial diagrams. As a result, a procedure for APD synthesis of linear and uniform rectangular equidistant (for example, 8- and 64-element) antenna arrays has been developed, taking into account the exact electrodynamic characteristics of antenna elements and their mutual resistance. Radiation patterns were obtained taking into account the effect of neighboring elements, with the help of which, using a genetic algorithm, APDs on emitters were found at different scanning angles. The change in SLL and G of the antenna array is analyzed at different scanning angles using different APDs. The proposed algorithm allows to synthesize APD for a RP with low SLL and high G at scanning angles up to 40° for linear antenna array and up to 80° in the case of a uniform rectangular antenna array. The results of this work are relevant in the problems of radiation pattern synthesis, since the proposed solution provides a significant gain in the radiation pattern synthesis rate of APD of linear and rectangular antenna arrays, especially for systems with a large number of antenna elements. At the same time, it is possible to maintain a high G at large scanning angles, and achieve a significant reduction of SLL.

Optimization and analysis of air-to-ground wireless link parameters for UAV mounted adaptable Radar Antenna Array

Unmanned Aerial Vehicles (UAVs) are rapidly used in a variety of applications such as surveillance, search and rescue operation, delivery, etc. These operations strongly depend on the performance of the air-to-ground (A2G) communication link. This link communicates vital information between the UAV and the ground station (GS). However, due to the UAV’s unpredictable mobility, the A2G link becomes unreliable, which limits the quality of data transfer. An Adaptable Radar Antenna Array (ARAA) can be used to solve this problem by effectively handling transmitted data through altering the antenna pattern using the beamforming process. This work proposes a new algorithm for selecting antenna patterns with proper beamforming by considering the effect of wobbling and mutual coupling (MC). In addition, the proposed algorithm is used to reduce the maximum sidelobe level (SLL) and optimize the distance between the interelement of ARAA, which directly controls the MC effect in a time-varying channel. Also, an analysis is done for various antenna configurations, such as Uniform Linear Array (ULA), Uniform Rectangular Array (URA), and Uniform Circular Array (UCA), while varying different UAV parameters like altitude, speed, location error, and beamforming capacity.

Walk on a grid

There are various combinatorial questions on rectangular arrays consisting of points, numbers, fields or, in general, of symbols such as chessboards, lattices, and graphs. Many such problems in enumerative combinatorics come from other branches of science and technology like physics, chemistry, computer sciences and engineering; for example the following two very challenging problems from chemistry: Problem 1: Dimer problem (Domino tiling) In chemistry, a large molecule composed repeatedly from monomers as a long chain is called a polymer and a dimer is composed of two monomers (where: mono = 1, di = 2, poly = many and mer = part).

Sidelobe level reduction in pattern synthesis of a non-uniform series-fed microstrip antenna array using the TLBO algorithm

In this paper, a series-fed microstrip patch antenna array with high gain and extremely low sidelobe levels, operating at 24 to 24.25 GHz, is presented. This antenna is fabricated on a single-layer PCB substrate. Due to its features such as compactness, lightweight, low cost, high gain, and narrow beamwidth, it can be used in many applications such as perimeter surveillance and collision-avoiding radar systems. The proposed antenna is a rectangular antenna array that consists of a non-uniform linear array with 50 in-line series-fed elements in one dimension and a uniform linear array with 16 elements in the other dimension. The non-uniform array provides 78% more physical space between the central elements, which is used to place the feed network of the uniform array. The radiation pattern of this non-uniform array has been synthesized using the TLBO algorithm. The prototype antenna with dimensions of 335 mm × 120 mm has been fabricated and tested. The measured gain of this antenna at central frequency is 28 dBi, with a 3-dB beamwidth of 2.6°and 7°and sidelobe level of 23.3 and 22.5 dB in the E-plane and H-plane respectively.

Improving estimation performance of compressive sensing‐based multiple‐input multiple‐output radar using electronic beamsteering

AbstractTwo‐dimensional direction‐of‐arrival (DoA) estimation in azimuth and elevation via radar systems equipped with uniform rectangular arrays (URAs) will play an important role in various application areas—most distinctively in future urban air mobility settings with unmanned aerial vehicles. A key factor is the fast and reliable provision of target detections in terms of range and DoA for safe autonomous operation of the vehicle using on‐board antenna arrays with compact installation size. The authors present a technique for improving the performance of DoA estimation using compressive sensing in conjunction with multiple‐input multiple‐output arrays with electronically steered beams in the transmit direction. The simulation study investigates the impact of different design considerations on radar signal processing performance. An optimisation of a radar system using electronic beamsteering in the transmit domain is presented numerically. Based on the architecture of the URAs used, performance and detection accuracy can be improved.

Decoupling and Cloaking of Rectangular and Circular Patch Antennas and Interleaved Antenna Arrays with Planar Coated Metasurfaces at C-Band Frequencies-Design and Simulation Study.

An electromagnetic cloaking approach is employed with the intention to curb the destructive effects of mutual interference for rectangular and circularly shaped patch antennas situated in a tight spacing. Primarily, we show that by coating the top surface of each patch with an appropriately designed metasurface, the mutual coupling is considerably reduced between the antennas. Furthermore, the cloak construct is extended to a tightly spaced, interleaved linear patch antenna array configuration and it is shown that the coated metasurfaces successfully enhance the performance of each array in terms of their matching characteristics, total efficiencies and far-field realized gain patterns for a broad range of beam-scan angles. For rectangular patches, the cloaked Array I and II achieve corresponding peak total efficiencies of 93% and 90%, in contrast to the total efficiencies of 57% and 21% for uncloaked Array I and II, respectively, at their operating frequencies. Moreover, cloaked rectangular Array I and II exhibit main lobe gains of 13.2 dB and 13.8 dB, whereas uncloaked Array I and II only accomplish main lobe gains of 10 dB and 5.5 dB, respectively. Likewise, for the cloaked circular patches, corresponding total efficiencies of 91% and 89% are recorded for Array I and II, at their operating frequencies (uncloaked Array I and II show peak efficiencies of 71% and 55%, respectively). The main lobe gain for each cloaked circular patch array is approximately 14.2 dB, whereas the uncloaked Array I and II only achieve maximum gains of 10.5 dB and 7.5 dB, respectively.

Laser Powder Bed Fusion of Stainless Steel 316L for Rectangular Micropillar Array with High Geometrical Accuracy and Hardness

Laser Powder Bed Fusion of Stainless Steel 316L for Rectangular Micropillar Array with High Geometrical Accuracy and Hardness

Toeplitz Matrix Reconstruction Algorithm for Rectangular Hollow Array

Among the directional angle calculation models of Bluetooth 5.1, the rectangular hollow array offers the advantage of shorter sampling time due to its fewer elements compared to traditional planar arrays. However, the antimultipath algorithms suitable for traditional planar arrays cannot be applied to rectangular hollow arrays. Therefore, this study proposes a virtual array filling algorithm, wherein four virtual matrices are inserted into the hollow matrix to transform the array into a uniform rectangular array. This algorithm ensures translation invariance of the rectangular array, enabling the application of the antimultipath coherent source algorithm to a rectangular hollow array. An algorithm for reconstructing Toeplitz matrices in two‐dimensional uniform planar arrays is also proposed. Through the analysis of the spatial spectrum and angle estimation results of various algorithms, the effectiveness of the signal angle of arrival estimation theory is verified.

2D Spatial Homogenizer Design Based on Rectangular Optical Fiber Array

2D Spatial Homogenizer Design Based on Rectangular Optical Fiber Array

Application of factor analytic and spatial mixed models for the analysis of multi-environment trials in common bean (Phaseolus vulgaris L.) in Ethiopia.

Common bean (Phaseolus vulgaris L.) is one of the most important grain legumes consumed globally, especially in Ethiopia, for its edible seeds, cash crops, and supply of protein for farmers. Efficient statistical methods must be employed for the evaluation of common bean varieties to accurately select superior varieties that contribute to agricultural productivity. The objective of this study was to identify promising large mottled bean varieties through analysis of multi-environment trials (MET) data using multiplicative spatial mixed models. In this study, 16-18 large mottled common bean varieties, including one check, were sown across nine growing environments in Ethiopia using lattice and alpha lattice designs, with three replications laid out in a square or rectangular (row by column) array of plots, respectively during the main cropping season from 2015 to 2018. We present a linear mixed model analysis that integrates spatial and factor analytic (FA) models, and the heritability measure was used to evaluate the efficiency of these models with the conventional analysis. The analysis of the spatial model, and more significantly, the spatial+FA model, revealed a notable enhancement in heritability. With the exception of a trial conducted at Kobo, a genotype DAP 292, found to be good performing for days to flowering and maturity, but for yield only across four clusters of trials, C2, C3, C5 and C7, formed with trials of relatively high genetic variance. Across these clusters, the yield advantage of this variety over the check ranged from 10-32%. This genotype also has a yield that is somewhat comparable to the check across the remaining clusters. Overall, both the spatial and factor analytic models proved to be effective approaches for analyzing the data in this study. The analysis of multi-environment trial data through the use of more efficient statistical models can provide a more robust platform for evaluating common bean varieties with greater confidence in selecting superior varieties across a range of environments. Hence, scaling up the use of this efficient analysis method is indispensable for enhancing the selection of superior varieties.

Design of a 2*2 Microstrip Phased Array Antenna for Radar Applications

Micro-strips patch antennae used in array configurations are more beneficial than single antenna element by augmenting the directivity (dB) radiation pattern, and lowering the substrate's permittivity to overcome its drawbacks, which include poor gain, low efficiency, narrow bandwidth limited directivity. It also facilitates beam-steering capability which is obtained by enabling phase difference(β) between the antennas. Beam scanning capability is used in radar and GNSS technologies. This paper proposes a 2*2 microstrip phased array antenna by using rectangular microstrip patch antenna on an FR-4 dielectric substrate for beam scanning. The resonant frequency of the antenna is at 2.52GHz frequency with a good Voltage Standing Wave Ratio (VSWR) value of 1.1325. The design has been simulated in Ansys HFSS software. The simulation results exhibit antenna better performance of the proposed antenna compared to state-of-art designs present in the literature. The compactly designed Rectangular Micro-strip Patch Antenna array shows a low S-parameter (–24.127858 dB), high gain (13.689104 dB), directivity (14.055125 dB), and efficiency of 91.917%.

The slow viscous flow around a general rectangular doubly-periodic arrays of infinite slender cylinders

Abstract The slow viscous flow through a doubly-periodic array of cylinders does not have an analytical solution. However, as a reduced model for the flow within fibrous porous media and microfluidic arrays, this solution is important for many real-world systems. We asymptotically determine the flow around a general rectangular doubly-periodic array of infinite slender cylinders, extending the existing asymptotic solution for square arrays. The flow in the cell is represented by a collection of doubly-periodic, rapidly-convergent two-dimensional singularity solutions, and the boundary condition on the surface of the cylinder is solved asymptotically in powers of the cylinder radius. The asymptotic solution provides an easily computed closed-form estimate for the flow and forces as a function of the radius and the dimensions of the cell. The force is compared to results from lattice-Boltzmann simulations of low-Reynolds-number flows in the same geometry, and the accuracy of the no-slip condition on the surface of the cylinder, predicted by the asymptotic theory, is assessed. Finally, the behaviour of the flow, flux, force and effective permeability of the cell is investigated as a function of the geometric parameters. The structure of the asymptotic permeability is consistent with previous single-geometry predictions but provides a closed-form estimate for how the aspect ratio of the cell changes the leading-order behaviour. These models could be used to help understand the flows within porous systems composed of fibres and systems involving periodic arrays such as systems based on deterministic lateral displacement .

Experimental, numerical, and 4E assessment of photovoltaic module using macro-encapsulation of pure and nano phase change material: A comparative analysis

Phase Change Material (PCM) for the thermal management of PV modules has been widely used while overlooking long-term viability and cost-effective power generation. To bridge this gap the current study adopted an innovative approach wherein macro-encapsulated pure and nano PCM are seamlessly integrated into the PV module within a rectangular array of tubes. The rectangular tubes with PCM prevent natural convection blockage, creating a fin-like effect on the rear side of the PV module, and minimizing PCM bulk for cost-effective power generation. This study is focused on the comparative assessments based on experimental and 4E analysis of PV modules having PCM (PVPCM) and uses numerical simulations to study the parametric analysis and assess heat transfer mechanisms of PVPCM module. The experimental results show that PV modules with pure PCM (PVPCM-1) and Nano PCM (PVPCM-2) reduce temperatures by 6.96 % and 13.78 % respectively. Performance improves by 7.69 % (PVPCM-1) and 16.32 % (PVPCM-2). PVPCM-2 also recovers 14 % exergy destruction showing the superiority of nano PCM over pure PCM. Numerical results show, that increasing the tilt angle for wind speeds more than 1 m/s raises the average PV temperature by 5.04 K. Economically, PVPCM-2 has a 2.5-year payback versus 2.84 years for unmodified PV.

Analysis of 5G Rotman beamforming lens antenna for higher beam angle and minimum phase error

Abstract Rotman lens beamforming networks are widely used for high gain, wide bandwidth applications in 5G communication. The uniform amplitude and phase distribution along with wide angle scanning at the array ports are mostly demanded for reducing the losses. Furthermore, minimum phase error is essential requirement for lens designs. Conventionally, for wide angle scanning, the lenses are designed by using most common expression between beam angle α and focal ratio (parameter ‘g’) i.e. g = 1 + 0.5α 2. The lenses obtained by such relation are inefficient for higher beam angle such as α = 45° due to the restricted shapes of beam and array contours. Hence suffer with large path length error limitation. In this paper, the mathematical relation between beam angle and focal ratio (parameter ‘g’) has been developed. The proposed relation offers phase error reduction more than 3× than the conventional expression based lens error. The simulation of the designed lens has performed using Software MATLAB which showed close agreement with the analytical values. Furthermore, three rectangular MPA arrays at center frequency 2.35 GHz have been proposed and simulated with lens design for 5G frequency range i.e. 2.3–2.4 GHz and offer high gain, directivity and wide coverage.

A high-precision method for manufacturing tunable solid microneedles using dicing saw and xenon difluoride-induced dry etching

Numerous fabrication techniques have been employed to produce solid microneedles (MNs); yet precise manufacturing of MNs with adjustable features (height, aspect ratio, and array number) remains the main limitation. Developing tunable MNs holds immense promise for personalized and efficient drug delivery systems. In this study, we utilized a combination of dicing saw and XeF2 isotropic dry etching processes to fabricate solid MNs with tunable characteristics. We herein created rectangular arrays using a dicing saw with desired geometry followed by dry etching to form MN arrays without further processing. Employing optimized parameters, the average heights of the MNs were 522 ± 15 µm, 614 ± 42 µm, and 698 ± 22 µm for initial pattern depths of 500 µm, 600 µm, and 700 µm, respectively. Moreover, we achieved an aspect ratio as high as 3.7, a radius of curvature less than 10 µm, and a tip angle as low as 6.4o. The mechanical and surface properties of the MNs were enhanced through magnetron sputtering with titanium. An ex vivo penetration test conducted on porcine skin demonstrated the significant potential of these MNs for transdermal drug delivery in future investigations. Overall, a cost-effective production of a single solid MN patch, featuring 400 MN arrays per cm2, can be achieved within a remarkably short timeframe (approximately 2 h). Investigating fundamental principles, this study addresses the persistent challenge in manufacturing solid MNs with adjustable features, such as height, aspect ratio, and array number. This presents a substantial advantage over alternative fabrication techniques.

Spatially extended sound source reconstruction based on the non-synchronous measurements of microphone arrays and Bayesian compressive sensing

The Non-synchronous Measurements (NSM) was proposed to enhance the accuracy of reconstruction and reduce the measurement cost. However, the investigated object of conventional NSM are only sparsely distributed sound sources, and little emphasis placed on the reconstructed accuracy of the spatially extended sound source. In this article, the traditional NSM is further investigated in the spatially extended sound source, and the sound pressure information is reconstructed by Bayesian compressive sensing algorithm (BCS). Firstly, the spatially extended sound source is scanned by moving the rectangular microphone array, and the measurement effects of the array with large aperture and high density are approximately obtained by using NSM technique. Then, BCS is applied to reconstruct sound field by the NSM of sound pressure. The results of numerical simulations provide evidence for the feasibility of applying the proposed investigation to the spatially extended sound source. NSM has advantages in reconstruction accuracy compared with the single measurement. At the same time, the reconstructed sound pressure under NSM can replace the simultaneous measurement (SM) results of multi-array, which avoids the limitation of using reference microphone in increasing the number of channels and spatial layout. The experimental results of the driven steel plate provide additional evidence to support the effectiveness and feasibility of the investigation.

Does a row of objects comprise a boundary? How children miss the forest for the trees in spatial navigation.

Unlike children's early ability to navigate by continuous boundaries, their ability to extract geometric information from an array of objects emerges gradually over childhood. To investigate children's developing representation of object arrays for navigation and its relation to their mental representation of the global spatial layout, reorientation behavior was tested in 146 children (4-9 years, 78 male children and 68 female children, Italian) with rectangular arrays made up of 20 objects. Posttest questions on children's spatial language and their mental and pictorial representation of the environment were administered. Although children of all ages navigated by the geometry of continuous boundary-like arrays, they only succeeded with separated object arrays at around 7 years of age. This developmental change was predicted by children's individual ability to extract the abstract geometry of the spatial layout in a two-dimensional picture of the room. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Multichannel coherence migration grid search (MCMgs) in locating microseismic events recorded by a surface array

SUMMARY Microseismic monitoring has been used in geo-energy related activities, such as shale-gas exploitation, mining, deep geothermal exploitation, geotechnical and structural engineering, for detecting and locating fractures, rock failures and micro-earthquakes. The success of microseismic monitoring depends on reliable detection and location of the recorded microseismicity. Multichannel coherence migration (MCM) is a detection and location waveform migration-based approach which does not require phase picking, identification and association and performs well on noisy data. Its caveat is a high computational cost, which impedes its application of MCM on large data sets or for real-time monitoring. To address this issue, we propose an improved approach, the multichannel coherence migration grid search (MCMgs), by introducing an adaptive grid optimization technique. Based on results from synthetic and real data, we show that MCMgs reduces the computation time up to 64 times. In addition, MCMgs generates multiple maximum coherence values with various grid sizes instead of a single (maximum) coherence value that links to a single gridpoint and size, thus resulting in more accurate locations. Our simulation results on different deployment geometries demonstrate that MCMgs is effective even with a small number of recordings available—a minimum of seven. We conduct a sensitivity analysis to assess how the detectability of events is affected by the spatial arrangement of the deployed monitoring array. If a limited number of seismometers are available for deployment, our analysis favours a patch array deployment geometry. We show that 12 seismometers deployed at a patch array geometry can have similar detection and localization capability as a large rectangular array of more than 100 seismometers but at a much lower computational and deployment cost.

Reflection-type surface lattice resonances in all-metal metasurfaces for refractive index sensing

Surface lattice resonance (SLR) is a pretty effective mechanism to realize ultranarrow linewidths in the spectrum. Herein, we propose and demonstrate reflection-type SLRs in all-metal metasurfaces experimentally, compared with the traditional transmission-type SLR, which can avoid the refractive index (RI) mismatch problem and are more suitable for high-efficiency RI sensing due to direct contact and strong light–matter interaction. The measured SLR linewidth is 13.5 nm influenced by the meta-atom size, which needs a compromise design to keep a balance between the narrow linewidth and noise immunity. Notably, the SLR sensitivity is determined by the lattice period along the polarization direction with regularity, which establishes an intuitive link between structures and optical responses and provides a theoretical guide for metasurface designs. Additionally, incident angle multiplexing will make the resonance wavelength red shift or blue shift in the case of orthogonal polarization. The rectangular array metasurface can realize dual SLRs with different sensing performances. Flexibly, the SLR can also be formed by the different meta-atoms and arrays. This research supports SLR multifarious applications involving not only RI sensing but also nonlinear optics, nano-lasers, etc.