Artículos de revistas: "2D arrays"

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Yue, Jian, Anqi Cui, Fei Wang, Lei Han, Jinguo Dai, Xiangyi Sun, Hang Lin, Chunxue Wang, Changming Chen y Daming Zhang. "Design of Monolithic 2D Optical Phased Arrays Heterogeneously Integrated with On-Chip Laser Arrays Based on SOI Photonic Platform". Micromachines 13, n.º 12 (30 de noviembre de 2022): 2117. http://dx.doi.org/10.3390/mi13122117.

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In this work, heterogeneous integration of both two-dimensional (2D) optical phased arrays (OPAs) and on-chip laser arrays based on a silicon photonic platform is proposed. The tunable multi-quantum-well (MQW) laser arrays, active switching/shifting arrays, and grating antenna arrays are used in the OPA module to realize 2D spatial beam scanning. The 2D OPA chip is composed of four main parts: (1) tunable MQW laser array emitting light signals in the range of 1480–1600 nm wavelengths; (2) electro-optic (EO) switch array for selecting the desired signal light from the on-chip laser array; (3) EO phase-shifter array for holding a fixed phase difference for the uniform amplitude of specific optical signal; and (4) Bragg waveguide grating antenna array for controlling beamforming. By optimizing the overall performances of the 2D OPA chip, a large steering range of 88.4° × 18° is realized by tuning both the phase and the wavelength for each antenna. In contrast to the traditional thermo-optic LIDAR chip with an external light source, the overall footprint of the 2D OPA chip can be limited to 8 mm × 3 mm, and the modulation rate can be 2.5 ps. The ultra-compact 2D OPA assembling with on-chip tunable laser arrays using hybrid integration could result in the application of a high-density, high-speed, and high-precision lidar system in the future.

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2

Yoon, Hansol y Tai-Kyong Song. "Sparse Rectangular and Spiral Array Designs for 3D Medical Ultrasound Imaging". Sensors 20, n.º 1 (27 de diciembre de 2019): 173. http://dx.doi.org/10.3390/s20010173.

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In three-dimensional (3D) medical ultrasound imaging with two-dimensional (2D) arrays, sparse 2D arrays have been studied to reduce the number of active channels. Among them, sparse 2D arrays with regular or uniform arrangements of elements have advantages of low side lobe energy and uniform field responses over the entire field of view. This paper presents two uniform sparse array models: sparse rectangular arrays (SRAs) on a rectangular grid and sparse spiral arrays (SSAs) on a sunflower grid. Both arrays can be easily implemented on the commercially available or the custom-made arrays. To suppress the overall grating lobe levels, the transmit (Tx) and receive (Rx) array pairs of both the array models are designed not to have grating lobes at the same locations in the Tx/Rx beam patterns, for which the theoretical design rules are also proposed. Computer simulation results indicate that the proposed array pairs for both the SRAs and the SSAs achieve peak grating lobe levels below –40 dB using about a quarter of the number of elements in the dense rectangular array while maintaining similar beam widths to that of the dense array pair.

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3

Doyoro, Yonatan Garkebo, Ping-Yu Chang y Jordi Mahardika Puntu. "Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities". Applied Sciences 11, n.º 7 (1 de abril de 2021): 3143. http://dx.doi.org/10.3390/app11073143.

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We examined the uncertainty of the two-dimensional (2D) resistivity method using conceptual cavity models. The experimental cavity study was conducted to validate numerical model results. Spatial resolution and sensitivity to resistivity perturbations were also assessed using checkerboard tests. Conceptual models were simulated to generate synthetic resistivity data for dipole-dipole (DD), pole-dipole (PD), Wenner–Schlumberger (WS), and pole-pole (PP) arrays. The synthetically measured resistivity data were inverted to obtain the geoelectric models. The highest anomaly effect (1.46) and variance (24,400 Ω·m) in resistivity data were recovered by the DD array, whereas the PP array obtained the lowest anomaly effect (0.60) and variance (2401 Ω·m) for the shallowest target cavity set at 2.2 m depth. The anomaly effect and variance showed direct dependency on the quality of the inverted models. The DD array provided the highest model resolution that shows relatively distinct anomaly geometries. In contrast, the PD and WS arrays recovered good resolutions, but it is challenging to determine the correct anomaly geometries with them. The PP array reproduced the lowest resolution with less precise anomaly geometries. Moreover, all the tested arrays showed high sensitivity to the resistivity contrasts at shallow depth. The DD and WS arrays displayed the higher sensitivity to the resistivity perturbations compared to the PD and PP arrays. The inverted models showed a reduction in sensitivity, model resolution, and accuracy at deeper depths, creating ambiguity in resistivity model interpretations. Despite these uncertainties, our modeling specified that two-dimensional resistivity imaging is a potential technique to study subsurface cavities. We inferred that the DD array is the most appropriate for cavity surveys. The PD and WS arrays are adequate, while the PP array is the least suitable for cavity studies.

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4

Wang, Dong, Ran Ji y Peter Schaaf. "Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates". Beilstein Journal of Nanotechnology 2 (22 de junio de 2011): 318–26. http://dx.doi.org/10.3762/bjnano.2.37.

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The fabrication of precise 2D Au nanoparticle arrays over a large area is presented. The technique was based on pre-patterning of the substrate before the deposition of a thin Au film, and the creation of periodic particle arrays by subsequent dewetting induced by annealing. Two types of pre-patterned substrates were used: The first comprised an array of pyramidal pits and the second an array of circular holes. For the dewetting of Au films on the pyramidal pit substrate, the structural curvature-driven diffusion cooperates with capillarity-driven diffusion, resulting in the formation of precise 2D particle arrays for films within a structure dependent thickness-window. For the dewetting of Au films on the circular hole substrate, the periodic discontinuities in the films, induced by the deposition, can limit the diffusion paths and lead to the formation of one particle per individual separated region (holes or mesas between holes), and thus, result in the evolution of precise 2D particle arrays. The influence of the pre-patterned structures and the film thickness is analyzed and discussed. For both types of pre-patterned substrate, the Au film thickness had to be adjusted in a certain thickness-window in order to achieve the precise 2D particle arrays.

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5

Wang, Haizhen, Lu Li, Jiaqi Ma, Junze Li y Dehui Li. "2D perovskite narrowband photodetector arrays". Journal of Materials Chemistry C 9, n.º 34 (2021): 11085–90. http://dx.doi.org/10.1039/d1tc03331j.

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6

Cassuto, Yuval y Amin Shokrollahi. "LDPC Codes for 2D Arrays". IEEE Transactions on Information Theory 60, n.º 6 (junio de 2014): 3279–91. http://dx.doi.org/10.1109/tit.2014.2313720.

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7

Gdor, Efrat, Shay Shemesh, Shlomo Magdassi y Daniel Mandler. "Multienzyme Inkjet Printed 2D Arrays". ACS Applied Materials & Interfaces 7, n.º 32 (7 de agosto de 2015): 17985–92. http://dx.doi.org/10.1021/acsami.5b04726.

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8

Rasskazov, Ilia L., Nishikant Sonwalkar y P. Scott Carney. "Light scattering by plasmonic disks and holes arrays: different or the same?" Journal of Physics D: Applied Physics 55, n.º 45 (19 de septiembre de 2022): 455104. http://dx.doi.org/10.1088/1361-6463/ac8ffc.

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Abstract We suggest a strategy for designing regular 2D arrays of nanoholes (NHs) in metal films with far-field scattering properties similar to that of regular 2D arrays of nanodisks (NDs) with the same periodicity. Full-wave simulations for perfectly conducting, Ag and Au NDs and respectively designed arrays of NHs demonstrate a minor difference between far-field properties either at wavelengths corresponding to Wood–Rayleigh anomalies of the arrays or in a broad wavelength range, depending on the array periodicity and sizes of NDs (NHs). Our results have broad implications in plasmon-enhanced-driven applications, including optoelectronic and photovoltaic devices, where the NH arrays are preferable to be fabricated for nano-structured optics.

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9

CHANG-HASNAIN, C. J., Y. A. WU, L. E. ENG y G. S. LI. "VERTICAL CAVITY SURFACE EMITTING LASER ARRAYS FOR WAVELENGTH DIVISION MULTIPLEXING APPLICATIONS". International Journal of High Speed Electronics and Systems 05, n.º 04 (diciembre de 1994): 569–92. http://dx.doi.org/10.1142/s0129156494000231.

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The capability to fabricate two-dimensional (2D) semiconductor diode laser array is one of the most important steps towards making wafer-scale low-cost lasers. The recent emergence of vertical cavity surface emitting laser (VCSEL) facilitates the fabrication of such large 2D arrays. In this paper, we review the recent progress on a novel largeaperture single-mode VCSEL and a 2D multiple-wavelength VCSEL array for ultra-high bandwidth applications. We demonstrate a passive antiguide region (PAR) VCSEL which emits a stable single mode with very low threshold, a large aperture, and a fixed polarization. We also demonstrate multi-wavelength VCSEL arrays with repeatable wavelength spans over 20 nm, grown by Molecular Beam Epitaxy. The wavelength shift is achieved by varying the GaAs growth rate across the wafer using a patterned backing wafer to induce a temperature profile. Such multiple wavelength laser arrays are promising for ultrahigh bandwidth optical transmission and switching systems using wavelength division multiplexing (WDM).

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10

Zhang, Lei, Shiwei Ren, Xiangnan Li, Guishan Ren y Xiaohua Wang. "Generalized L-Shaped Nested Array Concept Based on the Fourth-Order Difference Co-Array". Sensors 18, n.º 8 (1 de agosto de 2018): 2482. http://dx.doi.org/10.3390/s18082482.

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In this paper, a generalized L-shaped nested array based on the fourth-order difference co-array is proposed for two-dimensional (2D) directions’ estimation. The new structure framework makes full use of the physical sensor locations to form a virtual uniform rectangular array (URA) as large as possible. As it utilizes the fourth-order difference instead of the traditional second-order difference result, this structure framework can acquire a much higher degree-of-freedom (DOF) than the existing 2D sparse arrays. The proposed structures have two advantages. One is that the subarrays can be chosen as any nested-class arrays, which makes the sparse array design more flexible. We can choose arbitrary subarray structures for DOF enhancement purposes. Another advantage is that the relative position of two subarrays can be set as any integral multiple of half wavelength. This means that two subarrays can be located as far as possible so that the relative influence between two physical subarrays can be ignored. The DOFs of several typical generalized L-shaped nested arrays (GLNAs) are compared in this paper. By setting the subarrays as different types and the relative position as a special value, a special GLNA is presented. Simulations show that GLNAs have obvious superiority in 2D direction-of-arrival estimation.

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11

Wu, Tao, Yiwen Li, Zhengxin Li, Yijie Huang y Jiwei Xu. "A 2D Nested Array Based DOA Estimator for Incoherently Distributed Sources via Sparse Representation Utilizing L1-Norm". International Journal of Antennas and Propagation 2019 (3 de julio de 2019): 1–11. http://dx.doi.org/10.1155/2019/6941963.

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Nested arrays are sparse arrays composed of subarrays with nonuniform sensor spacing. Compared with traditional uniform arrays, nested arrays have more degree of freedoms (DOFs) and larger apertures. In this paper, a nested array has been proposed as well as a direction-of-arrival (DOA) estimation method for two-dimensional (2D) incoherently distributed (ID) sources. A virtual array is firstly obtained through vectorization of the cross-correlation matrix of subarrays. Sensor positions of the virtual array and the optimal configuration of the nested array are derived next. Then rotational invariance relationship for generalized steering matrix of the virtual array with respect to nominal azimuth is deduced. According to the rotational invariance relationship, sparse representation model under l1-norm constraint is established, which is resolved by transferring the objective function to second-order cone constraints and combining a estimation residual error constraint for receive vector of the virtual array. Simulations are conducted to investigate the effectiveness of the proposed method in underdetermined situation and examine different experiment factors including SNR, snapshots, and angular spreads as well as sensor number of subarrays. Results show that the proposed method has better performance than uniform parallel arrays with the same number of sensors.

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12

Darrh, Andréa, Christian Poppeliers y Leiph Preston. "Azimuthally Dependent Seismic‐Wave Coherence at the Source Physics Experiment Large‐N Array". Bulletin of the Seismological Society of America 109, n.º 5 (30 de julio de 2019): 1935–47. http://dx.doi.org/10.1785/0120180296.

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Abstract We document azimuthally dependent seismic scattering at the Source Physics Experiment (SPE) using the large‐N array. The large‐N array recorded the seismic wavefield produced by the SPE‐5 buried chemical explosion, which occurred in April 2016 at the Nevada National Security Site, U.S.A. By selecting a subset of vertical‐component geophones from the large‐N array, we formed 10 linear arrays, with different nominal source–receiver azimuths as well as six 2D arrays. For each linear array, we evaluate wavefield coherency as a function of frequency and interstation distance. For both the P arrival and post‐P arrivals, the coherency is higher in the northeast propagation direction, which is consistent with the strike of the steeply dipping Boundary fault adjacent to the northwest side of the large‐N array. Conventional array analysis using a suite of 2D arrays suggests that the presence of the fault may help explain the azimuthal dependence of the seismic‐wave coherency for all wave types. This fault, which separates granite from alluvium, may be acting as a vertically oriented refractor and/or waveguide.

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13

Albagory, Yasser y Fahad Alraddady. "Optimum Extrapolation Techniques for Two-Dimensional Antenna Array Tapered Beamforming". Electronics 11, n.º 13 (25 de junio de 2022): 1995. http://dx.doi.org/10.3390/electronics11131995.

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Optimizing antenna arrays is essential for achieving efficient beamforming with very low sidelobe level (SLL) where adopting tapered window functions is one of the straightforward efficient techniques for achieving this goal. Recently, two-dimensional (2D) beamforming has been extensively required for many applications; therefore, this paper proposes two extrapolation techniques applied to one-dimensional (1D) tapered functions to efficiently feed 2D antenna arrays using cross-linear and adaptive radial tapering techniques. The first proposed 2D cross-linear tapering technique determines the 2D tapering coefficients by Hadamard multiplication of two right-angled grids of repeated 1D functions, while the second proposed adaptive radial tapering technique locates the antenna element in the 2D array in terms of its radial distance with respect to the array center, then converts this distance to an element index in a virtual 1D tapering window to determine the element weighting value. The adaptive radial tapering technique is optimized for achieving the minimum SLLs. The two proposed techniques are analyzed and discussed, where it is found that the adaptive radial tapering provides deeper SLLs compared to the cross-linear tapering technique. The two extrapolation techniques are examined for four window functions including triangular (Bartlett), Hamming, cosine-square, and Blackman windows, and the simulation results show that for extrapolating the Blackman window using adaptive radial tapering, a −50 dB SLL can be achieved which is independent on the array size, while cross-linear tapering provides −35 dB and −41 dB SLLs for 16×16 and 32×32 antenna arrays, respectively.

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14

Julie, J. y J. Baskar Babujee. "Generalized Parikh Prime 2D Binary Arrays". Asian Journal of Research in Social Sciences and Humanities 6, n.º 9 (2016): 2065. http://dx.doi.org/10.5958/2249-7315.2016.00927.8.

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15

Hannour, A., L. Bardotti, B. Prével, E. Bernstein, P. Mélinon, A. Perez, J. Gierak, E. Bourhis y D. Mailly. "2D arrays of CoPt nanocluster assemblies". Surface Science 594, n.º 1-3 (diciembre de 2005): 1–11. http://dx.doi.org/10.1016/j.susc.2005.07.002.

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16

Sandro, Zampieri. "Exact Modelling of Finite 2D Arrays". IFAC Proceedings Volumes 25, n.º 21 (septiembre de 1992): 428–31. http://dx.doi.org/10.1016/s1474-6670(17)49809-0.

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17

Baraduc, C. y J. E. Mooij. "Coupled 2D-arrays of Josephson junctions". Czechoslovak Journal of Physics 46, S2 (febrero de 1996): 705–6. http://dx.doi.org/10.1007/bf02583660.

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18

Gunawidjaja, R., C. Jiang, H. Ko y V. V. Tsukruk. "Freestanding 2D Arrays of Silver Nanorods". Advanced Materials 18, n.º 21 (3 de noviembre de 2006): 2895–99. http://dx.doi.org/10.1002/adma.200600540.

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19

Kim, Jeong Nyeon, Tianning Liu, Thomas N. Jackson, Kyusun Choi, Susan Trolier-McKinstry, Richard L. Tutwiler y Judith A. Todd. "10 MHz Thin-Film PZT-Based Flexible PMUT Array: Finite Element Design and Characterization". Sensors 20, n.º 15 (4 de agosto de 2020): 4335. http://dx.doi.org/10.3390/s20154335.

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Piezoelectric micromachined ultrasound transducers (PMUT) incorporating lead zirconate titanate PbZr0.52Ti0.48O3 (PZT) thin films were investigated for miniaturized high-frequency ultrasound systems. A recently developed process to remove a PMUT from an underlying silicon (Si) substrate has enabled curved arrays to be readily formed. This research aimed to improve the design of flexible PMUT arrays using PZFlex, a finite element method software package. A 10 MHz PMUT 2D array working in 3-1 mode was designed. A circular unit-cell was structured from the top, with concentric layers of platinum (Pt)/PZT/Pt/titanium (Ti) on a polyimide (PI) substrate. Pulse-echo and spectral response analyses predicted a center frequency of 10 MHz and bandwidth of 87% under water load and air backing. A 2D array, consisting of the 256 (16 × 16) unit-cells, was created and characterized in terms of pulse-echo and spectral responses, surface displacement profiles, crosstalk, and beam profiles. The 2D array showed: decreased bandwidth due to protracted oscillation decay and guided wave effects; mechanical focal length at 2.9 mm; 3.7 mm depth of field for -6 dB; and -55.6 dB crosstalk. Finite element-based virtual prototyping identified figures of merit—center frequency, bandwidth, depth of field, and crosstalk—that could be optimized to design robust, flexible PMUT arrays.

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20

Awad, Samer I. y Jesse T. Yen. "3D Strain Imaging Using a Rectilinear 2D Array". Ultrasonic Imaging 29, n.º 4 (octubre de 2007): 220–30. http://dx.doi.org/10.1177/016173460702900403.

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Under mechanical compression, tissue movements are inherently three-dimensional. 2-D strain imaging can suffer from decorrelation noise caused by out-of-plane tissue movement in elevation. With 3-D strain imaging, all tissue movements can be estimated and compensated, hence minimizing out-of-plane decorrelation noise. Promising 3-D strain imaging results have been shown using 1 -D arrays with mechanical translation in elevation. However, the relatively large slice thickness and mechanical translation can degrade image quality. Using 2-D arrays, an improved elevational resolution can be achieved with electronic focusing. Furthermore, scanning with 2-D arrays is also done electronically, which eliminates the need for mechanical translation. In this paper, we demonstrate the feasibility of 3-D strain imaging using a 4 cm × 4 cm ultrasonic sparse rectilinear 2-D array operating at 5MHz. The signal processing combinations of 2-D or 3-D beamforming followed by 2-D or 3-D strain imaging are studied and compared to each other to evaluate the performance of our 3-D strain imaging system. 3-D beamforming followed by 3-D strain imaging showed best performance in all experiments.

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21

Xiao, Yu, Tao Wu, Yiwen Li, Xinping Ma y Yijie Huang. "Direction-of-Arrival Estimation for 2D Coherently Distributed Sources with Nested Array Based on Matrix Reconstruction". Mathematical Problems in Engineering 2020 (12 de mayo de 2020): 1–13. http://dx.doi.org/10.1155/2020/6494967.

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This paper has made proposition of a nested array and an estimation algorithm for direction-of-arrival (DOA) of two-dimensional (2D) coherently distributed (CD) sources. According to the difference coarray concept, double parallel hole-free virtual uniform linear arrays are generated by virtue of vectorization operation on cross-correlation matrices of subarrays. Sensor coordinates of virtual arrays are derived. Rational invariance relationships of virtual arrays are derived. According to the rotational invariance relationships, matrices satisfying rotation invariance are constructed by extracting and regrouping the receive vectors of the virtual arrays, and then an estimation of signal parameters via rotational invariance techniques- (ESPRIT-) like framework on matrix reconstruction is deduced. Optimal configuration of the nested array as well as computational complexity are analyzed. Without pair matching, the proposed method can resolve more sources than the sensor number. Simulation outcomes indicate that the proposed method tends to have a better performance as compared to the traditional uniform arrays that have similar number of sensors.

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22

Liu, Qiankun, Tom Smy, Ahmad Atieh, Pavel Cheben, Alejandro Sánchez-Postigo y Winnie N. Ye. "Integrated circular optical phased array". EPJ Web of Conferences 255 (2021): 01004. http://dx.doi.org/10.1051/epjconf/202125501004.

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Existing OPAs are typically based on 2D rectangular arrays or 1D linear arrays. Both approaches present a limited field-of-view (FOV) due to the presence of the grating lobes when the element spacing is larger than λ/2. To address the need for an increased steering range, we propose a new design strategy of an OPA system utilizing a 2D circular phased array, with a substantially increased FOV. We present a circular OPA using a demonstrated antenna element design, with an 820-element array. A steering range ΩSR calculated as a solid angle of 0.51π sr, and an angular beamwidth of 0.22°, was achieved. The array exhibits a sidelobe suppression larger than 10 dB, and a FOV of 2π sr. Although the performance is limited by the far field pattern of the individual antenna we chose, our circular OPA achieved, to the best of our knowledge, the largest steering range reported to date compared to the state-of-the-art integrated optical phased arrays reported in literature.

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23

Yu, Jing Jing y Fa Shan Yu. "Evolutionary Algorithm for Microphone Array Optimization". Applied Mechanics and Materials 143-144 (diciembre de 2011): 287–92. http://dx.doi.org/10.4028/www.scientific.net/amm.143-144.287.

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This paper presented a genetic algorithm (GA) to optimize element placements of microphone array with the purpose of maximizing beamforming SNR for given possible distribution of sound sources. A function based on relationship between statistical geometry descriptors and array performance matrices was applied as the objective function of GA. Optimization experiments of 1D linear array and 2D planar array were performed to demonstrate that this algorithm can effectively sort out superior arrays with significant SNR improvements over randomly generated arrays and regular arrays. High successful rate, rapid convergence speed, and fast processing time observed in all the experiments demonstrate the feasibility of this algorithm as a practical tool for microphone array design.

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Wu, Tao, Pengtao Zhang, Yiwen Li, Yangjun Gao, Chaoqi Fu y Bo Feng. "DOA Tracking of Two-Dimensional Coherent Distribution Source Based on Fast Approximated Power Iteration". Mathematical Problems in Engineering 2020 (16 de noviembre de 2020): 1–12. http://dx.doi.org/10.1155/2020/3219516.

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Aiming at two-dimensional (2D) coherent distributed (CD) sources, this paper has proposed a direction of arrival (DOA) tracking algorithm based on signal subspace updating under the uniform rectangular array (URA). First, based on the hypothesis of small angular spreads of distributed sources, the rotating invariant relations of the signal subspace of the receive vector of URA are derived. An ESPRIT-like method is constructed for DOA estimation using two adjacent parallel linear arrays of URA. Through the synthesis of estimation by multiple groups of parallel linear arrays within URA arrays, the DOA estimation method for 2D CD sources based on URA is obtained. Then, fast approximated power iteration (FAPI) subspace tracking algorithm is used to update the signal subspace. In this way, DOA tracking of 2D CD sources can be realized by DOA estimation through signal subspace updating. This algorithm has a low computational complexity and good real-time tracking performance. In addition, the algorithm can track multiple CD sources without knowing the angular signal distribution functions, which is robust to model errors.

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Fries, David y Geran Barton. "3D MICROSENSOR IMAGING ARRAYS NETWORKS". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, DPC (1 de enero de 2015): 000348–78. http://dx.doi.org/10.4071/2015dpc-ta33.

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2D microsensor arrays can permit spatial distribution measurements of the sensed parameter and enable high resolution sensing visualizations. Measuring constituents in a flowing media, such as air or liquid could benefit from such flow through or flow across imaging systems. These flow imagers can have applications in mobile robotics and non-visible imagery, and alternate mechanical systems of perception, process control and environmental observations. In order to create rigid-conformal, large area imaging systems we have in the past merged flexible PCB substrates with rigid constructions from 3D printing. This approach merges the 2D flexible electronics world of printed circuits with the 3D printed packaging world. Extending this 2D flow imaging concept into the third dimension permits 3D flow imaging networks, architectures and designs and can create a new class of sensing systems. Using 3D printing, 3D printed filaments, nets and microsensor cages, can be combined into integrated designs to generate distributed 3D imaging networks and camera systems for a variety of sensory applications.

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Denisov, A. A., C. M. Shakarji, B. B. Lawford, R. G. Maev y J. M. Paille. "Spot weld analysis with 2D ultrasonic Arrays". Journal of Research of the National Institute of Standards and Technology 109, n.º 2 (marzo de 2004): 233. http://dx.doi.org/10.6028/jres.109.015.

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27

Ma, Chun-Sheng, Xin Yan y Xian-Yin Wang. "Matrix analysis of 2D microring resonator arrays". Journal of Modern Optics 55, n.º 1 (10 de enero de 2008): 143–54. http://dx.doi.org/10.1080/09500340701322188.

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Wiesenfeld, Kurt, Adam S. Landsberg y Giovanni Filatrella. "Linewidth calculation for bare 2D Josephson arrays". Physics Letters A 233, n.º 4-6 (septiembre de 1997): 373–77. http://dx.doi.org/10.1016/s0375-9601(97)00470-2.

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29

Haghighi, Nasibeh, Philip Moser, Martin Zorn y James A. Lott. "19-Element 2D Top-Emitting VCSEL Arrays". Journal of Lightwave Technology 39, n.º 1 (1 de enero de 2021): 186–92. http://dx.doi.org/10.1109/jlt.2020.3023709.

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30

Rybczynski, J., U. Ebels y M. Giersig. "Large-scale, 2D arrays of magnetic nanoparticles". Colloids and Surfaces A: Physicochemical and Engineering Aspects 219, n.º 1-3 (junio de 2003): 1–6. http://dx.doi.org/10.1016/s0927-7757(03)00011-6.

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31

Gong, Chuanhui, Kai Hu, Xuepeng Wang, Peihua Wangyang, Chaoyi Yan, Junwei Chu, Min Liao et al. "2D Nanomaterial Arrays for Electronics and Optoelectronics". Advanced Functional Materials 28, n.º 16 (14 de febrero de 2018): 1706559. http://dx.doi.org/10.1002/adfm.201706559.

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32

Lin, C. H., L. Jiang, Y. H. Chai, H. Xiao, S. J. Chen y H. L. Tsai. "A method to fabricate 2D nanoparticle arrays". Applied Physics A 98, n.º 4 (27 de enero de 2010): 855–60. http://dx.doi.org/10.1007/s00339-010-5552-0.

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33

Henry, Claude R. "2D-Arrays of Nanoparticles as Model Catalysts". Catalysis Letters 145, n.º 3 (5 de noviembre de 2014): 731–49. http://dx.doi.org/10.1007/s10562-014-1402-6.

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Ripka, Pavel, Diana Hrakova, Mehran Mirzaei y Ondrej Kaman. "Apparent permeability of ordered magnetically soft nanowire arrays". AIP Advances 12, n.º 3 (1 de marzo de 2022): 035128. http://dx.doi.org/10.1063/9.0000316.

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Using the equivalent 2D model for finite element method (FEM) we calculated apparent permeability µa and demagnetization factor D for permalloy nanowire and microwire arrays. The simulation results were verified by 3D FEM for arrays up to 3000 wires and experimentally for very large arrays containing up to 40 million wires. We achieved µa = 3 to 33 and coercivities Hc = 1 to 9 kA/m, which are low values for wire arrays. The µa depends mainly on the array geometry; it can be increased by increasing the distance between wires (pitch) and the wire length-to-diameter ratio L/d.

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35

Xu, Lingyun y Fangqing Wen. "Two-Dimensional Direction Finding Estimation for Uniform Rectangular Array with Unknown Mutual Coupling via Real-Valued PARAFAC Decomposition". Journal of Circuits, Systems and Computers 28, n.º 03 (24 de febrero de 2019): 1950049. http://dx.doi.org/10.1142/s021812661950049x.

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Two-dimensional direction-of-arrival (2D-DOA) estimation for uniform rectangular array (URA) is a canonical problem with numerous applications, e.g., wireless communications, sonar and radar systems. The conventional 2D-DOA estimators usually are derived with the assumption of ideal arrays. However, in practice, the arrays may not be well calibrated and suffer from unknown mutual coupling. Using the conventional estimators may lead to low accuracy estimation and high computational complexity in the condition of large number of array elements. In this paper, a novel real-valued parallel factor (PARAFAC) decomposition algorithm is proposed to tackle this problem. The proposed algorithm has better angle estimation performance than the multiple signal classification (MUSIC) algorithm, estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm and conventional PARAFAC algorithm. But it has lower complexity than MUSIC algorithm. Moreover, the proposed algorithm can obtain automatically paired 2D-DOA estimation, and it is suitable to coherent or closely spaced signals and can eliminate the mutual coupling. Simulation results verify the effectiveness of the proposed algorithm.

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36

Pan, Ping, Yangyang Hu, Guiling Zhang, Zhao-Di Yang y Xiao Cheng Zeng. "Hybrid nanobud-array structures (C24)n/MoS2and (C24V)n/MoS2: two-dimensional half metallic and ferromagnetic materials". Journal of Materials Chemistry C 6, n.º 13 (2018): 3373–86. http://dx.doi.org/10.1039/c8tc00021b.

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Two-dimensional (2D) hybrid nanobud-array structures, (C₂₄)_n/MoS₂and (C₂₄V)_n/MoS₂, are designed by grafting (C₂₄)_nor (C₂₄V)_nfullerene arrays onto the surface of 2D monolayer MoS₂(ML-MoS₂).

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37

Martínez-Graullera, Óscar, Júlio Cesar Eduardo de Souza, Montserrat Parrilla Romero y Ricardo Tokio Higuti. "Design of 2D Planar Sparse Binned Arrays Based on the Coarray Analysis". Sensors 21, n.º 23 (30 de noviembre de 2021): 8018. http://dx.doi.org/10.3390/s21238018.

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The analysis of the beampattern is the base of sparse arrays design process. However, in the case of bidimensional arrays, this analysis has a high computational cost, turning the design process into a long and complex task. If the imaging system development is considered a holistic process, the aperture is a sampling grid that must be considered in the spatial domain through the coarray structure. Here, we propose to guide the aperture design process using statistical parameters of the distribution of the weights in the coarray. We have studied three designs of sparse matrix binned arrays with different sparseness degrees. Our results prove that there is a relationship between these parameters and the beampattern, which is valuable and improves the array design process. The proposed methodology reduces the computational cost up to 58 times with respect to the conventional fitness function based on the beampattern analysis.

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38

de Souza, Júlio Cesar Eduardo, Montserrat Parrilla Romero, Ricardo Tokio Higuti y Óscar Martínez-Graullera. "Design of Ultrasonic Synthetic Aperture Imaging Systems Based on a Non-Grid 2D Sparse Array". Sensors 21, n.º 23 (30 de noviembre de 2021): 8001. http://dx.doi.org/10.3390/s21238001.

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This work provides a guide to design ultrasonic synthetic aperture systems for non-grid two-dimensional sparse arrays such as spirals or annular segmented arrays. It presents an algorithm that identifies which elements have a more significant impact on the beampattern characteristics and uses this information to reduce the number of signals, the number of emitters and the number of parallel receiver channels involved in the beamforming process. Consequently, we can optimise the 3D synthetic aperture ultrasonic imaging system for a specific sparse array, reducing the computational cost, the hardware requirements and the system complexity. Simulations using a Fermat spiral array and experimental data based on an annular segmented array with 64 elements are used to assess this algorithm.

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39

Guo, Xiaolong, Tian Wang, Tian Xu Zheng, Chaohe Xu, Jintao Zhang, Yu Xin Zhang, Xiao Ying Liu y Fan Dong. "Quasi-parallel arrays with a 2D-on-2D structure for electrochemical supercapacitors". Journal of Materials Chemistry A 6, n.º 48 (2018): 24717–27. http://dx.doi.org/10.1039/c8ta07869f.

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40

Touati, Amine, Samir Chatbouri, Nabil Sghaier y Adel Kalboussi. "Theoretical Analysis and Characterization of Multi-Islands Single-Electron Devices with Applications". Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/241214.

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A two- (2D) and three-dimensional (3D) multiple-tunnel junctions array is investigated. Device structure and electrical characteristics are described. We present a comparison of carriers transport through devices based on polymetallic grains based on master equation and the orthodox theory. The Coulomb blockade effect of 2D and 3D arrays is observed at low and high temperatures. The conduction mechanism is handled by the tunnel effect, and we adopt in addition the thermionic and Fowler-Nordheim emissions. Numerical simulation results focused on flash-memory and photodetector applications. Memory characteristics such as program/erase select gate operation are demonstrated in 2D devices. Also 3D array scheme is discussed for the high-density NCs scalable for photodetector application.

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41

Loke, M. H., H. Kiflu, P. B. Wilkinson, D. Harro y S. Kruse. "Optimized arrays for 2D resistivity surveys with combined surface and buried arrays". Near Surface Geophysics 13, n.º 5 (julio de 2015): 505–18. http://dx.doi.org/10.3997/1873-0604.2015038.

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42

Petronijevic, Emilija, Alessandro Belardini, Grigore Leahu, Tiziana Cesca, Carlo Scian, Giovanni Mattei y Concita Sibilia. "Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver". Applied Sciences 10, n.º 4 (15 de febrero de 2020): 1316. http://dx.doi.org/10.3390/app10041316.

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Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then differently interacts with circular polarizations of opposite handedness at normal incidence, i.e., it becomes intrinsically chiral. The measure of this difference is called circular dichroism (CD). The nanosphere lithography combined with tilted silver evaporation was employed as a low-cost fabrication technique. In this paper, we demonstrate intrinsic chirality and CD by measuring the extinction in the near-infrared range. We further employ numerical analysis to visualize the circular polarization coupling with the nanostructure. We find a good agreement between simulations and the experiment, meaning that the optimization can be used to further increase CD.

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43

Liu, Qiankun, Daniel Benedikovic, Tom Smy, Ahmad Atieh, Pavel Cheben y Winnie N. Ye. "Circular Optical Phased Arrays with Radial Nano-Antennas". Nanomaterials 12, n.º 11 (6 de junio de 2022): 1938. http://dx.doi.org/10.3390/nano12111938.

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On-chip optical phased arrays (OPAs) are the enabling technology for diverse applications, ranging from optical interconnects to metrology and light detection and ranging (LIDAR). To meet the required performance demands, OPAs need to achieve a narrow beam width and wide-angle steering, along with efficient sidelobe suppression. A typical OPA configuration consists of either one-dimensional (1D) linear or two-dimensional (2D) rectangular arrays. However, the presence of grating sidelobes from these array configurations in the far-field pattern limits the aliasing-free beam steering, when the antenna element spacing is larger than half of a wavelength. In this work, we provide numerical analysis for 2D circular OPAs with radially arranged nano-antennas. The circular array geometry is shown to effectively suppress the grating lobes, expand the range for beam steering and obtain narrower beamwidths, while increasing element spacing to about 10 μm. To allow for high coupling efficiency, we propose the use of a central circular grating coupler to feed the designed circular OPA. Leveraging radially positioned nano-antennas and an efficient central grating coupler, our design can yield an aliasing-free azimuthal field of view (FOV) of 360°, while the elevation angle FOV is limited by the far-field beamwidth of the nano-antenna element and its array arrangement. With a main-to-sidelobe contrast ratio of 10 dB, a 110-element OPA offers an elevation FOV of 5° and an angular beamwidth of 1.14°, while an 870-element array provides an elevation FOV up to 20° with an angular beamwidth of 0.35°. Our analysis suggests that the performance of the circular OPAs can be further improved by integrating more elements, achieving larger aliasing-free FOV and narrower beamwidths. Our proposed design paves a new way for the development of on-chip OPAs with large 2D beam steering and high resolutions in communications and LIDAR systems.

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44

Mofakhami, Darius, Benjamin Seznec, Romaric Landfried, Philippe Teste, Philippe Dessante y Tiberiu Minea. "A fast-modeling algorithm to predict the thermo-field emission and thermal stability of field emitter arrays". Journal of Applied Physics 132, n.º 24 (28 de diciembre de 2022): 243302. http://dx.doi.org/10.1063/5.0116717.

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In the last decades, numerical simulation has become a precious tool to assist the design and study of electron sources based on regular arrays of field emitters. Simulations of field emitter arrays (FEAs) require 3D treatment to account for the interactions between neighbor emitters. Therefore, modeling the thermal evolution of FEAs involves high computational resources due to the multi-physics approach and time dependency. The present paper proposes an algorithm which gives a fast prediction of the self-heating of a large array of [Formula: see text] axisymmetric field emitters. It consists in finding for each emitter the equivalent 2D axisymmetric situation yielding the same electron current at 300 K as in the 3D array. The 3D modeling is thus efficiently split into [Formula: see text] simulations in 2D, with a significant computation time reduction by at least one order of magnitude. The proof of concept uses [Formula: see text] arrays of ideal emitters. Our results show a correct prediction, within a few percent, of the array thermo-field current and maximum temperature—two quantities of high interest for thermal failure and breakdown voltage considerations. The algorithm paves the way for including thermal effects in future optimization studies of realistic FEAs.

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45

Chen, Dong y Younghoon Joo. "Novel Approach to 2D DOA Estimation for Uniform Circular Arrays Using Convolutional Neural Networks". International Journal of Antennas and Propagation 2021 (8 de julio de 2021): 1–15. http://dx.doi.org/10.1155/2021/5516798.

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This paper presents a novel efficient high-resolution two-dimensional direction-of-arrival (2D DOA) estimation method for uniform circular arrays (UCA) using convolutional neural networks. The proposed 2D DOA neural network in the single source scenario consists of two levels. At the first level, a classification network is used to classify the observation region into two subregions (0°, 180°) and (180°, 360°) according to the azimuth angle degree. The second level consists of two parallel DOA networks, which correspond to the two subregions, respectively. The input of the 2D DOA neural network is the preprocessed UCA covariance matrix, and its outputs are the estimated elevation angle to be modified by postprocessing and the estimated azimuth angle. The purpose of the postprocessing is to enhance the proposed method’s robustness to the incident signal frequency. Moreover, in the inevitable array imperfections scenario, we also achieve 2D DOA estimation via transfer learning. Besides, although the proposed 2D DOA neural network can only process one source at a time, we adopt a simple strategy that enables the proposed method to estimate the 2D DOA of multiple sources in turn. Finally, comprehensive simulations demonstrate that the proposed method is effective in computation speed, accuracy, and robustness to the incident signal frequency and that transfer learning could significantly reduce the amount of required training data in the case of array imperfections.

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46

Canclini, Antonio, Fabio Antonacci, Augusto Sarti y Stefano Tubaro. "Distributed 3D Source Localization from 2D DOA Measurements Using Multiple Linear Arrays". Wireless Communications and Mobile Computing 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/1049141.

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This manuscript addresses the problem of 3D source localization from direction of arrivals (DOAs) in wireless acoustic sensor networks. In this context, multiple sensors measure the DOA of the source, and a central node combines the measurements to yield the source location estimate. Traditional approaches require 3D DOA measurements; that is, each sensor estimates the azimuth and elevation of the source by means of a microphone array, typically in a planar or spherical configuration. The proposed methodology aims at reducing the hardware and computational costs by combining measurements related to 2D DOAs estimated from linear arrays arbitrarily displaced in the 3D space. Each sensor measures the DOA in the plane containing the array and the source. Measurements are then translated into an equivalent planar geometry, in which a set of coplanar equivalent arrays observe the source preserving the original DOAs. This formulation is exploited to define a cost function, whose minimization leads to the source location estimation. An extensive simulation campaign validates the proposed approach and compares its accuracy with state-of-the-art methodologies.

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47

Battista, Michael T., Douglas H. Clements, Judy Arnoff, Kathryn Battista y Caroline Van Auken Borrow. "Students' Spatial Structuring of 2D Arrays of Squares". Journal for Research in Mathematics Education 29, n.º 5 (noviembre de 1998): 503–32. http://dx.doi.org/10.5951/jresematheduc.29.5.0503.

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We define spatial structuring as the mental operation of constructing an organization or form for an object or set of objects. It is an essential mental process underlying students' quantitative dealings with spatial situations. In this article, we examine in detail students' structuring and enumeration of 2-dimensional (2D) rectangular arrays of squares. Our research indicates that many students do not “see”the row-by-column structure we assume in such arrays. We describe the various levels of sophistication in students' structuring of these arrays and elaborate the nature of the mental process of structuring.

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48

BASOV, N. G., Yu M. POPOV, V. V. BEZOTOSNY y Kh Kh KUMYKOV. "2D high power laser diode arrays for solid-state laser driver inertial fusion energy project". Laser and Particle Beams 17, n.º 3 (julio de 1999): 427–35. http://dx.doi.org/10.1017/s0263034699173105.

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2D arrays of laser diodes were developed and investigated under QCW operating conditions. Output power and energy density up to 1 kW/cm2 and 0.45 J/cm2 (at pulse duration 0.5 ms) were measured at the wavelength 810 nm. The spectral composition of radiation, shape of the output pulses, and far-field and near-field radiation zones were examined under various pumping parameters. The kinetics of the temperature profiles in monolithic QCW AlGaAs/GaAs linear bars and 2D arrays, emitting at the wavelength 810 nm was modeled numerically. Quasi-CW and CW operation under various pump parameters were considered as a function of a heat sink design. A calculation model was used to interpret the experimental dependences of the output parameters of the arrays on the pump conditions for application in the solid-state laser driver project. The limit of total power conversion efficiency of diode lasers was analyzed in respect of the threshold current density, series resistance and external differential quantum efficiency. The estimated maximum value of 75% was obtained for the present technological level of the diode lasers production. The corresponding limit of the output optical power density of 2D laser array was defined around 10 kW/cm2.

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49

Yoo, Junhyuk, Wonjin Sung y In-Kyung Kim. "2D-OPC Subarray Structure for Efficient Hybrid Beamforming over Sparse mmWave Channels". International Journal of Antennas and Propagation 2021 (15 de junio de 2021): 1–9. http://dx.doi.org/10.1155/2021/6680566.

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Millimeter-wave (mmWave) communication is a key technology of 5G new radio (NR) mobile communication systems. Efficient beamforming using a large antenna array is important to cope with the significant path loss experienced in the mmWave spectrum. The existing fully digital beamforming scheme requires a separate radio frequency (RF) chain for each antenna, which results in an excessive hardware cost and consumption power. Under these circumstances, hybrid beamforming which approaches the performance of fully digital beamforming while reducing the complexity is a promising solution for the mmWave multiuser transmission. By extending the existing hybrid beamforming strategies, this paper proposes a novel architecture which effectively reduces the hardware cost and complexity for large antenna arrays. The proposed scheme includes multiple subarrays in the form of uniform planar array (UPA) which are allowed to be overlapped in the two-dimensional space. The corresponding antenna structure is referred to as the two-dimensional overlapped partially connected (2D-OPC) subarray structure. We evaluate the performance of the proposed scheme to suggest performance-complexity trade-offs in designing versatile antenna arrays for efficient beamforming over the mmWave channel.

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50

Chen, Jiajun, Enbo Zhu, Juan Liu, Shuai Zhang, Zhaoyang Lin, Xiangfeng Duan, Hendrik Heinz, Yu Huang y James J. De Yoreo. "Building two-dimensional materials one row at a time: Avoiding the nucleation barrier". Science 362, n.º 6419 (6 de diciembre de 2018): 1135–39. http://dx.doi.org/10.1126/science.aau4146.

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Assembly of two-dimensional (2D) molecular arrays on surfaces produces a wide range of architectural motifs exhibiting unique properties, but little attention has been given to the mechanism by which they nucleate. Using peptides selected for their binding affinity to molybdenum disulfide, we investigated nucleation of 2D arrays by molecularly resolved in situ atomic force microscopy and compared our results to molecular dynamics simulations. The arrays assembled one row at a time, and the nuclei were ordered from the earliest stages and formed without a free energy barrier or a critical size. The results verify long-standing but unproven predictions of classical nucleation theory in one dimension while revealing key interactions underlying 2D assembly.

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