Journal articles: 'Compacts arrays'

1

Shi, J. L. "Relations Between Coarsening and Densification and Mass Transport Path in Solid-state Sintering of Ceramics: Model Analysis." Journal of Materials Research 14, no. 4 (April 1999): 1378–88. http://dx.doi.org/10.1557/jmr.1999.0188.

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The correlations between coarsening (including grain and pore growth) and densification, and the effects of mass transport on particle coarsening and densification were discussed based on the simple particle array models and for the real particle compacts. Grain boundary motion could cause particle coarsening only under a certain particle size distribution but not densification; mass transport is reasoned to contribute to both grain growth (particle coarsening) and shrinkage for one-dimensional particle arrays. Under a certain limitation for the change of the particle size aspect ratio during sintering, very limited effects of grain grown by itself on the shrinkage of particle a rrays throughreinitiating the sintering could be found. For a real powder compact system, mass transport between the particles, which surround a pore, contributes to the particle coarsening and densification when the pore is thermodynamically unstable and only to particle coarsening when the pore is thermodynamically stable. The mass transport mechanism for both particle coarsening and densification would be the same, which cannot exclude, at least on thermodynamics, the contribution from surface diffusion in the intermediate stage of sintering.

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Li, Jing Feng, Song Zhe Jin, and Yong Li. "Fabrication of Si₃N₄ Micro-Components by a Combined Microfabrication Process." Key Engineering Materials 287 (June 2005): 28–32. http://dx.doi.org/10.4028/www.scientific.net/kem.287.28.

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Si-based high-temperature ceramics are attractive materials for power microelectromechanical systems (power MEMS), such as microscale gas turbines, micro-combustors and micro-reactors. This presentation introduces a novel process for the microfabrication of Si3N4 ceramics, which mainly consists of pre-sintering of Si powder compacts, micromachining of pre-sintered Si preforms and reaction sintering of the micromachined Si preforms. The present process has its high potential for Si3N4 3-dimensional microfabrication because it combines the machinablity of pre-sintered Si powder compacts and near-net shaping characteristic of S3N4 reaction sintering. Si3N4 micro-components such as micro nozzle arrays and micro-rotor were fabricated by using the present process.

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Llères, David, John James, Sam Swift, David G. Norman, and Angus I. Lamond. "Quantitative analysis of chromatin compaction in living cells using FLIM–FRET." Journal of Cell Biology 187, no. 4 (November 16, 2009): 481–96. http://dx.doi.org/10.1083/jcb.200907029.

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We present a quantitative Förster resonance energy transfer (FRET)–based assay using multiphoton fluorescence lifetime imaging microscopy (FLIM) to measure chromatin compaction at the scale of nucleosomal arrays in live cells. The assay uses a human cell line coexpressing histone H2B tagged to either enhanced green fluorescent protein (FP) or mCherry FPs (HeLaH2B-2FP). FRET occurs between FP-tagged histones on separate nucleosomes and is increased when chromatin compacts. Interphase cells consistently show three populations of chromatin with low, medium, or high FRET efficiency, reflecting spatially distinct regions with different levels of chromatin compaction. Treatment with inhibitors that either increase chromatin compaction (i.e., depletion of adenosine triphosphate) or decrease chromosome compaction (trichostatin A) results in a parallel increase or decrease in the FLIM–FRET signal. In mitosis, the assay showed variation in compaction level, as reflected by different FRET efficiency populations, throughout the length of all chromosomes, increasing to a maximum in late anaphase. These data are consistent with extensive higher order folding of chromatin fibers taking place during anaphase.

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Sun, Dajun, Jie Ding, Cuie Zheng, and Weimin Huang. "Array geometry calibration for underwater compact arrays." Applied Acoustics 145 (February 2019): 374–84. http://dx.doi.org/10.1016/j.apacoust.2018.10.004.

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Leicher, Rachel, Eva J. Ge, Xingcheng Lin, Matthew J. Reynolds, Wenjun Xie, Thomas Walz, Bin Zhang, Tom W. Muir, and Shixin Liu. "Single-molecule and in silico dissection of the interaction between Polycomb repressive complex 2 and chromatin." Proceedings of the National Academy of Sciences 117, no. 48 (November 18, 2020): 30465–75. http://dx.doi.org/10.1073/pnas.2003395117.

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Polycomb repressive complex 2 (PRC2) installs and spreads repressive histone methylation marks on eukaryotic chromosomes. Because of the key roles that PRC2 plays in development and disease, how this epigenetic machinery interacts with DNA and nucleosomes is of major interest. Nonetheless, the mechanism by which PRC2 engages with native-like chromatin remains incompletely understood. In this work, we employ single-molecule force spectroscopy and molecular dynamics simulations to dissect the behavior of PRC2 on polynucleosome arrays. Our results reveal an unexpectedly diverse repertoire of PRC2 binding configurations on chromatin. Besides reproducing known binding modes in which PRC2 interacts with bare DNA, mononucleosomes, and adjacent nucleosome pairs, our data also provide direct evidence that PRC2 can bridge pairs of distal nucleosomes. In particular, the “1–3” bridging mode, in which PRC2 engages two nucleosomes separated by one spacer nucleosome, is a preferred low-energy configuration. Moreover, we show that the distribution and stability of different PRC2–chromatin interaction modes are modulated by accessory subunits, oncogenic histone mutations, and the methylation state of chromatin. Overall, these findings have implications for the mechanism by which PRC2 spreads histone modifications and compacts chromatin. The experimental and computational platforms developed here provide a framework for understanding the molecular basis of epigenetic maintenance mediated by Polycomb-group proteins.

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Velarde Martinez, Apolinar. "Scheduling in Heterogeneous Distributed Computing Systems Based on Internal Structure of Parallel Tasks Graphs with Meta-Heuristics." Applied Sciences 10, no. 18 (September 22, 2020): 6611. http://dx.doi.org/10.3390/app10186611.

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The problem of scheduling parallel tasks graphs (PTGs) represented by directed acyclic graphs (DAGs) in heterogeneous distributed computing systems (HDCSs) is considered an nondeterministic polynomial time (NP) problem due to the diversity of characteristics and parameters, generally opposed, intended to be optimized. The PTGs are scheduled by a scheduler that determines the best location for the sub-tasks that constitute the PTGs and is responsible for allocating the resources of the HDCS to the sub-tasks of the PTGs. To optimize scheduling and allocations, the scheduler extracts characteristics from the internal structure of the PTGs. The prevailing characteristic in existing research is the critical path (CP), which is limited to providing execution paths of PTGs; considering this limitation, we extend the array method proposed in Velarde, which extracts two additional characteristics to the CP: the layering and the density of the graph for scheduling. These characteristics are represented as integer values of the PTGs to be scheduled; the values obtained from the characteristics are stored in arrays representing populations that are evaluated with the heuristic univariate marginal distribution algorithm (UMDA) and in terms of comparison with the genetic algorithm. With the best allocations produced by the algorithms, two performance parameters are evaluated: makespan and waiting time. The results indicate that when more PTGs characteristics are considered, resource allocations are optimized, and scheduling times are reduced. The results obtained with the heuristic algorithms show that UMDA provides shorter scheduling and allocation times compared with the genetic algorithm; UMDA widely distributes the sub-tasks in the clusters, whereas the genetic algorithm compacts the assignments of the PTGs in the clusters with a longer convergence time that translates into longer scheduling and allocation times. Extensive explanations of these conclusions are provided in this work, based on the conducted experiments.

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Fontana, P. M., and T. ‐A Haugland. "Compact sleeve‐gun source arrays." GEOPHYSICS 56, no. 3 (March 1991): 402–7. http://dx.doi.org/10.1190/1.1443058.

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Data derived from far‐field signature measurements have inspired several guidelines for using clustered sleeve guns effectively in tuned marine seismic source arrays. Primarily, these data show that for a given volume the signature produced by a cluster of sleeve guns has a comparable bubble period, increased primary amplitude, and reduced bubble‐pulse amplitude compared to the signature of a single gun. These results agree with those reported for clusters of conventional air guns. However, when the data are analyzed in terms of acoustic and operational efficiency, we find that for array elements with volumes greater than [Formula: see text] two‐gun clusters are more desirable than equivalent volume clusters of several small volume guns. For array elements with volumes up to [Formula: see text], the data show no significant advantages for using clusters instead of single guns. These guidelines have led to the design of sleeve‐gun arrays that produce signatures with temporal and spectral characteristics equal to or exceeding those produced by conventional air‐gun arrays incorporating almost twice the total gun volume. Moreover, these new arrays operate with a total number of individual guns comparable to conventional arrays, thus improving the performance of source arrays on small survey vessels without having to increase air compressor capacity or ancillary source equipment.

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Taylor, Jacob, Nolan Denman, Kevin Bandura, Philippe Berger, Kiyoshi Masui, Andre Renard, Ian Tretyakov, and Keith Vanderlinde. "Spectral Kurtosis-Based RFI Mitigation for CHIME." Journal of Astronomical Instrumentation 08, no. 01 (March 2019): 1940004. http://dx.doi.org/10.1142/s225117171940004x.

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We present the implementation of a spectral kurtosis-based Radio-Frequency Interference detection system on the CHIME instrument and its reduced-scale pathfinder. Our implementation extends single-receiver formulations to the case of a compact array, combining samples from multiple receivers to improve the confidence with which RFI is detected. Through comparison between on-sky data and simulations, we show that the statistical properties of the canonical spectral kurtosis estimator are functionally unchanged by cross-array integration. Moreover, by comparison of simultaneous data from CHIME and the Pathfinder, we evaluate our implementation’s capacity for interference discrimination for compact arrays of various sizes. We conclude that a spectral kurtosis-based implementation provides a scalable, high cadence RFI discriminator for compact multi-receiver arrays.

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KETO, ERIC. "HIERARCHICAL CONFIGURATIONS FOR CROSS-CORRELATION INTERFEROMETERS WITH MANY ELEMENTS." Journal of Astronomical Instrumentation 01, no. 01 (November 5, 2012): 1250007. http://dx.doi.org/10.1142/s2251171712500079.

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Array configurations built on a hierarchy of simple elements have excellent properties for cross-correlation imaging interferometers including a smooth distribution of measured Fourier components, high angular resolution, low side lobes, and compact array size. Compared to arrays with a Gaussian distribution of antenna separations, hierarchical arrays (H-arrays) produce beams with higher angular resolution and a tighter concentration of the total power (encircled energy) within a smaller area around the main beam. An attractive feature of H-arrays is their simplicity. The relationships between the Fourier coverage and the array configuration are easy enough to understand that they can be adjusted to achieve different design goals without the need for numerical optimization. H-arrays will be useful for future multi-element interferometers.

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Guohua Hu, Guohua Hu, Zhipeng Qi Zhipeng Qi, Binfeng Yun Binfeng Yun, Ruohu Zhang Ruohu Zhang, and and Yiping Cui and Yiping Cui. "Compact, integrated PLZT optical switch array." Chinese Optics Letters 13, no. 11 (2015): 111301–4. http://dx.doi.org/10.3788/col201513.111301.

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Haneef, Shaikh Rehan, Sathish Kumar Selvaperumal, and Vikneswary Jayapal. "Modified Compact 2x4 Slotted Array Antenna." Journal of Advanced Research in Dynamical and Control Systems 11, no. 11-SPECIAL ISSUE (February 20, 2019): 870–76. http://dx.doi.org/10.5373/jardcs/v11sp11/20193109.

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Lin, Shu-Dong, Shi Pu, Chen Wang, and Hai-Yang Ren. "Compact Design of Annular-Microstrip-Fed mmW Antenna Arrays." Sensors 21, no. 11 (May 26, 2021): 3695. http://dx.doi.org/10.3390/s21113695.

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In this paper, a series of four novel microstrip antenna array designs based on different annular-microstrip feeding lines at 60-GHz millimeter wave (mmW) band are proposed, aiming at the potential usage of the mmW coverage antenna with multi-directional property. As the feeding network, the annular contour microstrip lines are employed to connect the patch units so as to form a more compact array. Our first design is to use an outer contour annular microstrip line to connect four-direction linear arrays composed of 1 × 3 rectangular patches, thus the gain of 8.4 dBi and bandwidth of over 300 MHz are obtained. Our second design is to apply the two-direction pitchfork-shaped array each made up of two same linear arrays as the above, therefore the gain of 9.65 dBi and bandwidth of around 250 MHz are achieved. Our third design is to employ dual (inner and outer contour) annular-microstrip feeding lines to interconnect the above four-direction linear arrays, while our fourth design is to bring bridged annular-microstrip feeding lines, both of which can realize the goal of multi-directional radiation characteristic and higher gain of over 10 dBi.

13

Lui, Hoi-Shun, and Hon Tat Hui. "Direction-of-Arrival Estimation of Closely Spaced Emitters Using Compact Arrays." International Journal of Antennas and Propagation 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/104848.

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Performance evaluation of direction-of-arrival (DOA) estimation algorithms has continuously drawn significant attention in the past years. Most previous studies were conducted under the situation that antenna element separation is about half wavelength in order to avoid the appearance of grating lobes. On the other hand, recent developments in wireless communications have favoured the use of portable devices that utilize compact arrays with antenna element separations of less than half wavelength. Performance evaluation of DOA estimation algorithms employing compact arrays is an important and fundamental issue, but it has not been fully studied. In this paper, the performance of the matrix pencil method (MPM) that applies to DOA estimations is investigated through Monte Carlo simulations. The results show that closely spaced emitters can be accurately resolved using linear compact array with an array aperture as small as around half wavelength.

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Schwarz, Simon, Babette Götzendorfer, Stefan Rung, Cemal Esen, and Ralf Hellmann. "Compact Beam Homogenizer Module with Laser-Fabricated Lens-Arrays." Applied Sciences 11, no. 3 (January 23, 2021): 1018. http://dx.doi.org/10.3390/app11031018.

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We report on manufacturing of a compact beam homogenizer module including two lens arrays and an aperture. Lens arrays are fabricated by an all laser-based technology employing a precise femtosecond pulsed laser ablation and a CO2 laser polishing step. Each lens array is processed revealing a high contour accuracy and a roughness of 25 nm. The 8x8 lens arrays are designed to have a square footprint to generate a quadratic Top-Hat beam profile and focal length of 10 mm to realize compact packaging. Firstly, the lens arrays are tested in an experimental setup using commercial lens holders with their functionality being demonstrated by shaping a uniform 4.5 mm squared Top-Hat beam profile, as being calculated. Afterwards, a 3D printer is used to additively manufacture the housing for the beam homogenizer module having a length of only 16 mm. After assembling the laser-fabricated lens arrays and a laser-cutted aperture into the housing, the functionality of the miniaturized module is proven.

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Mao, Yanfei, Shiju E, and Chungeng Zhu. "A New and Simple Design Method for End-Fire Dipole Antenna Array and Three Two-Element 24 GHz Planar End-Fire Dipole Antenna Arrays." Applied Sciences 11, no. 16 (August 23, 2021): 7720. http://dx.doi.org/10.3390/app11167720.

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For an RF system, a high-gain antenna helps to improve the equivalent isotropic radiated power (EIRP) of the transmitter and an end-fire antenna array helps to improve the directivity (D) and half power beam width (HP) of the antenna. This work presents a new and simple design method for end-fire antenna array design. The method states that when antenna elements are λ/2 apart, a simple end-fire antenna array could be designed and constructed easily without matching networks between antenna elements. Utilizing Rogers 4350 PCB technology, three 24 GHz high-gain, compact planar two-element end-fire dipole antenna arrays are designed to verify this new design method. The achieved results are three two-element end-fire antennas with gains of 8.8, 9.9 and 9.1 dBi. These antenna arrays are characterized by high gain and simplicity in design. They are also very compact in size, with an area of about 1.9 × 1.7 cm2. The benefit of this work is that a new and simple design for end-fire antenna design is suggested, and three two-element end-fire dipole antenna arrays in planar technology which adopt the design method are presented. A utility model patent was granted for this end-fire dipole array antenna topology, ZL 202022106332.1.

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Pourmohammadi, Peyman, Vladimir Volski, and Guy A. E. Vandenbosch. "Medium-Sized Highly Coupled Planar Arrays with Maximum Aperture Efficiency." Sensors 21, no. 17 (September 3, 2021): 5925. http://dx.doi.org/10.3390/s21175925.

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This paper presents a technique to design strongly coupled planar arrays with very high aperture efficiency. The key innovation is that, based on an irregular 2 × 1 array, very compact medium-sized arrays of size 2 × 2, 2 × 4, and 2 × 6 are constructed with very strong and constructive mutual coupling between the elements. In this way, a maximum aperture efficiency is reached for a given footprint of the array. The occupied space of the antenna in comparison with conventional linear patch arrays is studied. A prototype 2 × 4 array operating around 5.8 GHz is designed, fabricated, built, and measured. The results show a large bandwidth of 20% and a very high aperture efficiency of 100%, which is the largest found in the literature for similarly sized arrays. These results are important in view of the future Internet of Things, where small and medium-sized arrays are planned to be mounted on numerous devices where a very limited physical area is available.

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Liu, Yuanyuan, Dongyue Jin, Xin Lei, Yuxin Zhou, Wanrong Zhang, Hongytm Xie, Weicong Na, Jlngfing Dai, and Zhiyong Wang. "Improvement of current crowding effect in VCSEL arrays with non-uniform oxidation aperture design." MATEC Web of Conferences 395 (2024): 01002. http://dx.doi.org/10.1051/matecconf/202439501002.

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A compact electro-opto-thermal model of 2-D vertical cavity surface emitting laser (VCSEL) arrays considering the current crowding effect in each array cell is established to study the impact of oxidation aperture on the device performance. Simulated results shows that increasing oxidation aperture of array cell is helpful to improve the uniformity of current density distribution. With careful design of non-uniform oxidation aperture layout, both the uniformity of the temperature distribution and the current distribution is improved by 36.52% and 42.08%, respectively. Furthermore, 3×3 VCSEL arrays with uniform oxidation aperture (array-1) and non-uniform oxidation aperture (array-2) are fabricated and the L-I-V curves of two types of VCSEL arrays at different biases are also measured. The peak output optical power of array-2 is enhanced to 1.83mW with an improvement of 8.91% when compared with that of array-1. Moreover, the total optical output power of array-2 is always superior to that of array-1 over a wide bias current range.

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Han, Guodong, and Weihang Liu. "A Circularly Polarized Non-Resonant Slotted Waveguide Antenna Array for Wide-Angle Scanning." Sensors 24, no. 10 (May 11, 2024): 3056. http://dx.doi.org/10.3390/s24103056.

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A compact circularly polarized non-resonant slotted waveguide antenna array is proposed with the aim of achieving wide-angle scanning, circular polarization, and low side-lobe levels. The designed antenna demonstrates a scanning range of +11° to +13° in the frequency domain and a beam scanning range of −45° to +45° in the phase domain. This design exhibits significant advantages for low-cost two-dimensional electronic scanning circularly polarized arrays. It employs a compact element that reduces the aperture area by 50% compared to traditional circular polarization cavities. Additionally, the staggered array method is employed to achieve an element spacing of 0.57λ within the azimuth plane. Isolation gaps were introduced into the array to enhance the circular polarization performance of non-resonant arrays. The Taylor synthesis method was employed to reduce the side-lobe levels. A prototype was designed, fabricated, and measured. The results indicate superior radiation efficiency, favorable VSWR levels, and an axis ratio maintenance below 3 dB across the scanning range. The proposed antenna and methodology effectively broaden the beam scanning angle of circularly polarized slotted waveguide array antennas.

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Roa, Carlos-Felipe, Emmanuel Chérin, Nidhi Singh, Jianhua Yin, Aaron Boyes, F. Stuart Foster, and Christine E. M. Demore. "Development of a Small-Footprint 50 MHz Linear Array: Fabrication and Micro-Ultrasound Imaging Demonstration." Sensors 24, no. 6 (March 13, 2024): 1847. http://dx.doi.org/10.3390/s24061847.

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Compact high-frequency arrays are of interest for clinical and preclinical applications in which a small-footprint or endoscopic device is needed to reach the target anatomy. However, the fabrication of compact arrays entails the connection of several dozens of small elements to the imaging system through a combination of flexible printed circuit boards at the array end and micro-coaxial cabling to the imaging system. The methods currently used, such as wire bonding, conductive adhesives, or a dry connection to a flexible circuit, considerably increase the array footprint. Here, we propose an interconnection method that uses vacuum-deposited metals, laser patterning, and electroplating to achieve a right-angle, compact, reliable connection between array elements and flexible-circuit traces. The array elements are thickened at the edges using patterned copper traces, which increases their cross-sectional area and facilitates the connection. We fabricated a 2.3 mm by 1.7 mm, 64-element linear array with elements at a 36 μm pitch connected to a 4 cm long flexible circuit, where the interconnect adds only 100 μm to each side of the array. Pulse-echo measurements yielded an average center frequency of 55 MHz and a −6 dB bandwidth of 41%. We measured an imaging resolution of 35 μm in the axial direction and 114 μm in the lateral direction and demonstrated the ex vivo imaging of porcine esophageal tissue and the in vivo imaging of avian embryonic vasculature.

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HU, TIEN-CHUNG, PING YAN CHEN, and N. C. WEBER. "A REMARK ON THE STRONG LAW FOR B-VALUED ARRAYS OF RANDOM ELEMENTS." Bulletin of the Australian Mathematical Society 82, no. 1 (June 2, 2010): 31–43. http://dx.doi.org/10.1017/s0004972710000158.

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AbstractThe conditions in the strong law of large numbers given by Li et al. [‘A strong law for B-valued arrays’, Proc. Amer. Math. Soc.123 (1995), 3205–3212] for B-valued arrays are relaxed. Further, the compact logarithm rate law and the bounded logarithm rate law are discussed for the moving average process based on an array of random elements.

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Yue, Jian, Anqi Cui, Fei Wang, Lei Han, Jinguo Dai, Xiangyi Sun, Hang Lin, Chunxue Wang, Changming Chen, and Daming Zhang. "Design of Monolithic 2D Optical Phased Arrays Heterogeneously Integrated with On-Chip Laser Arrays Based on SOI Photonic Platform." Micromachines 13, no. 12 (November 30, 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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Mohammadi-Asl, Saeed, Javad Nourinia, Changiz Ghobadi, and Maryam Majidzadeh. "Broadband circularly polarized slot antenna arrays using linked elliptical slots forC- andX-band applications." International Journal of Microwave and Wireless Technologies 10, no. 3 (April 2018): 328–35. http://dx.doi.org/10.1017/s1759078717000812.

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Compact broadband circularly polarized elliptical slot antenna arrays (CPESAAs) are devised based on 2 × 2 and 4 × 4 circularly polarized (CP) elliptical slot antennas and a sequential phase feed network. To realize the circular polarization, eight rectangular stubs are embedded in the feed structure to excite two orthogonal E vectors in 2 × 2 CPESAA configuration. Moreover, by taking four rectangular slots out from each array element, return loss and axial-ratio bandwidths are noticeably increased. The investigated simple array element has a compact size of 20 × 20 × 1 mm3. As well, 2 × 2 CPESAA occupies a compact size of 55 × 60 × 1 mm3, which operates within the frequency band 4.18–9.35 GHz. Thus, 76.4% of S11< −10 dB and 51.4% of CP bandwidth (4.43–7.5 GHz) are covered. Moreover, proposed 4 × 4 CPESAA is printed on 110 × 110 × 1 mm3FR4 substrate and covers the frequency band of 1.15–12.98 GHz with CP at 2.95–8.82 GHz. Throughout the study, the design process of the proposed antenna arrays are presented and discussed in detail.

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Saleh, Sahar, Tale Saeidi, and Nick Timmons. "Simple Compact UWB Vivaldi Antenna Arrays for Breast Cancer Detection." Telecom 5, no. 2 (April 8, 2024): 312–32. http://dx.doi.org/10.3390/telecom5020016.

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In this study, at ultra-wideband (UWB) frequency band (3.1–10.6 GHz), we propose the use of compact 2:1 and 3:1 nonuniform transmission line Wilkinson power dividers (NTL WPDs) as feeding networks for simple 2 × 1 linear UWB Vivaldi tapered and nonuniform slot antenna (VTSA and VNSA) arrays. The 2:1 and 3:1 tapered transmission line (TTL) WPDs are designed and tested in this work as benchmarks for NTL WPDs. The VTSA array provides measured S11 < −10.28 dB at 2.42–11.52 GHz, with a maximum gain of 8.61 dBi, which is 24.39% higher than the single element. Using the VNSA array, we achieve 52% compactness and 6.76% bandwidth enhancement, with good measured results of S11 < −10.2 dB at 3.24–13 GHz and 15.11% improved gain (8.14 dBi) compared to the VNSA single element. The findings show that the NTL and Vivaldi nonuniform slot profile antenna (VNSPA) theories are successful at reducing the size of the UWB WPD and VTSA without sacrificing performance. They also emphasize the Vivaldi antenna’s compatibility with other circuits. These compact arrays are ideal for high-resolution medical applications like breast cancer detection (BCD) because of their high gain, wide bandwidth, directive stable radiation patterns, and low specific absorption rate (SAR). A simple BCD simulation scenario is addressed in this work. Detailed parametric studies are performed on the two arrays for impedance-matching enhancement. The computer simulation technology (CST) software is used for the simulation. Hardware measurement results prove the validity of the proposed arrays.

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Abdalmalak, Kerlos Atia, Ayman Abdulhadi Althuwayb, Choon Sae Lee, Gabriel Santamaría Botello, Enderson Falcón-Gómez, Luis Emilio García-Castillo, and Luis Enrique García-Muñoz. "Standing-Wave Feeding for High-Gain Linear Dielectric Resonator Antenna (DRA) Array." Sensors 22, no. 8 (April 18, 2022): 3089. http://dx.doi.org/10.3390/s22083089.

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A novel feeding method for linear DRA arrays is presented, illuminating the use of the power divider, transitions, and launchers, and keeping uniform excitation to array elements. This results in a high-gain DRA array with low losses with a design that is simple, compact and inexpensive. The proposed feeding method is based on exciting standing waves using discrete metallic patches in a simple design procedure. Two arrays with two and four DRA elements are presented as a proof of concept, which provide high gains of 12 and 15dBi, respectively, which are close to the theoretical limit based on array theory. The radiation efficiency for both arrays is about 93%, which is equal to the array element efficiency, confirming that the feeding method does not add losses as in the case of standard methods. To facilitate the fabrication process, the entire array structure is 3D-printed, which significantly decreases the complexity of fabrication and alignment. Compared to state-of-the-art feeding techniques, the proposed method provides higher gain and higher efficiency with a smaller electrical size.

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Van Trinh, Thai, Jinsu Park, Chan Mi Song, Sungchan Song, and Keum Cheol Hwang. "A 3-D Metal-Printed Dual-Polarized Ridged Waveguide Slot Array Antenna for X-Band Applications." Applied Sciences 13, no. 8 (April 16, 2023): 4996. http://dx.doi.org/10.3390/app13084996.

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A compact three-dimensional (3-D) metal-printed ridged waveguide slot array antenna with wideband, dual linear polarization and low cross-polarization is presented for X-band applications. The proposed design achieves a compact structure due to the method of using a ridged waveguide (RWG). A vertically linear polarized (VP) array is realized through eight longitudinal shunt slots etched on the non-ridged broad wall of the RWG, while a horizontally linear polarized (HP) array is realized through eight V-shaped slots cut on the ridged broad wall of the RWG. To extend the operating bandwidth, each 1 × 8-element linear array is separated into two 1 × 4-element sub-arrays through a central feeding technique. The two sub-arrays of the VP array are excited with equal amplitude and are 180° out-of-phase through a T-junction power divider, which connects the coaxial feed and the radiated waveguide, while the two HP subarrays are directly excited by a coaxial feed with equal amplitude and remain in phase. The feed structure uses coaxial probes directly attached to the RWG to provide good mechanical stability and low voltage around the feed. An optimized 2 × 8-element dual-polarized array is fabricated using 3-D metal-printing technology for experimental verification. The measured −10 dB impedance bandwidth of the VP array is 1.2 GHz (12.2%) and, of the HP array, is 1.1 GHz (11.2%) with maximum gains of 14.6 and 15.5 dBi, respectively. There is good polarization purity over the entire operating bandwidth with a cross-polarization level better than −40 dB in the main beam direction. The isolation between two orthogonal polarized arrays is greater than 40 dB over the whole band.

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Lu, Xing, Qizhou Zhang, Jens Kauffmann, and Thushara Pillai. "SMA observations towards massive clouds in the central molecular zone." Proceedings of the International Astronomical Union 9, S303 (October 2013): 191–93. http://dx.doi.org/10.1017/s1743921314000532.

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AbstractRecently we conducted a mini-survey towards a sample of six massive clouds with surface density >1024 cm−2 in the central molecular zone (CMZ) of the Milky Way, with the SMA at 280 GHz in the compact array and at 230 GHz in the compact/subcompact arrays. The data reveal compact dust continuum peaks, some of which are also associated with organic molecular lines and thermal SiO emission. The subcompact array data helps recover more structures, e.g. the regularly spaced, well-aligned continuum fragments in the 20 km s−1 cloud. Shock tracers such as SiO are found in all the clouds. Our observations suggest potential protostellar origin for some of the dust continuum peaks in these regions.

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Lu, Junqi, and Yongxin Guo. "Compact Planar Sparse Array Antenna with Optimum Element Dimensions for SATCOM Ground Terminals." International Journal of Antennas and Propagation 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/806981.

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A novel antenna array architecture for low-cost and compact SATCOM mobile terminal is presented. Based on equal-amplitude aperiodic phased array with fewer active chain numbers, it possesses advantages including lower weight, less cost, and higher power efficiency compared to conventional periodic phased arrays. It is implemented with printed patch antenna so that it guarantees compactness. The elements position and dimensions are jointly designed, with an effective sparse array synthesis strategy that takes actual patch antenna design constraint into consideration, to obtain a maximum array aperture efficiency. Executable and practical approach for variable dimension patch antenna designing, including defect substrate element and small scale array, is introduced and utilized to implement proposed sparse array. Full-wave simulation results demonstrate the advantages of proposed array antenna as well as the effectiveness of corresponding design approach.

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Lv, Xianyang, Yongwei Zhang, Quan Shi, Yanwei Fu, Murat Temiz, Ahmed El-Makadema, and Hongliang Li. "Multibeam Cylindrical Conformal Array in the Presence of Enhanced Mutual Coupling." Electronics 13, no. 2 (January 16, 2024): 373. http://dx.doi.org/10.3390/electronics13020373.

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The limitations of conventional sensors have made array antennas increasingly crucial for gathering information and communication applications in intelligent transportation and communication systems. Compact cylindrical arrays are particularly favored for their ability to achieve azimuth angle scanning. However, the substantial mutual coupling effect between the elements on curved surfaces and its implication for these arrays remain unclear, which is a key factor to consider when such arrays are used for multibeam applications. This study investigates the effect of mutual coupling in a dual-slant-polarized cylindrical array. The results showed that mutual coupling is predominantly observed among the closely located elements, and it is essential for achieving an ultra-wide bandwidth. The study also analyzes the impact of mutual coupling on the scan impedance and radiation characteristics for multibeam applications and reveals that these arrays exhibit robust multibeam capability, hence having great potential for use in sensing and communication applications.

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Ogurtsov, Stanislav, Diego Caratelli, and Zhe Song. "A Review of Synthesis Techniques for Phased Antenna Arrays in Wireless Communications and Remote Sensing." International Journal of Antennas and Propagation 2021 (September 27, 2021): 1–19. http://dx.doi.org/10.1155/2021/5514972.

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Electronically controlled antenna arrays, such as reconfigurable and phased antenna arrays, are essential elements of high-frequency 5G communication hardware. These antenna arrays are aimed at delivering specified communication scenarios and channel characteristics in the mm-wave parts of the 5G spectrum. At the same time, several challenges are associated with the development of such antenna structures, and these challenges mainly originate from their intended mass production, contemporary manufacturing technologies, integration with active RF chains, compact size, dense circuitry, and limitations in postmanufacturing tuning. Consequently, 5G antenna array designers are presented with contradictory design requirements and constraints. Furthermore, these designers need to handle large numbers of designable parameters of the antenna array models, which can be computationally expensive, especially for repetitive and adaptive simulations that are required in design optimization and tuning. Antenna array synthesis, namely, the process of finding positions, orientation, and excitation of the array radiators, is a challenging yet crucial part of antenna array development. This process ensures that the performance requirements of the antenna array are met. Therefore, there is a need for reliable yet fast automated computer-aided design (CAD) and synthesis tools that can support the development of 5G antenna array solutions, from the initial prototyping stage to the final manufacturing tolerance analysis. This paper presents an overview of recent advances in antenna array synthesis from the viewpoint of their applicability to the design of electronically reconfigurable and phased antenna arrays for wireless communications and remote sensing.

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Huang, Tiancong, Yantao Yu, and Lijun Yi. "Design of Highly Isolated Compact Antenna Array for MIMO Applications." International Journal of Antennas and Propagation 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/473063.

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In order to achieve very high data rates in both the uplink and downlink channels, the multiple antenna systems are used within the mobile terminal as well as the base station of the future generation of mobile networks. When implemented in a size limited platform, the multiple antenna arrays suffer from strong mutual coupling between closely spaced array elements. In this paper, a rigorous procedure for the design of a 4-port compact planar antenna array with high port isolation is presented. The proposed design involves a decoupling network consisting of reactive elements, whose values can be obtained by the method of eigenmode analysis. Numerical results show the effectiveness of the proposed design approach in improving the port isolation of a compact four-element planar array.

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Dakhli, Saber, Jean Marie Floc’h, Mohammed Aseeri, Ameni Mersani, and Hatem Rmili. "Design of Compact and Superdirective Metamaterial-Inspired Two- and Three-Elements Antenna Arrays." Journal of Electromagnetic Engineering and Science 23, no. 4 (July 31, 2023): 362–68. http://dx.doi.org/10.26866/jees.2023.4.r.179.

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This paper presents the development of a miniature antenna array in a small space in order to achieve superdirectivity for long-range communication. The proposed structures consist of a superdirective metamaterial-inspired array based on a capacitively loaded loop (CLL) driven by an electrically small monopole antenna. This elementary antenna is then used in two- and three-array configurations separated by a fixed interelement distance of 0.1λ to achieve a higher directivity and compact size (with λ the wavelength calculated at the operation frequency 1.850 GHz). The design of the elementary antenna, its simulated radiation performances, as well as those of the parasitic array are also reported. The results of the optimization of two- and three-antenna arrays are discussed. For this study, three corresponding prototypes were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and shown to be in good agreement with their simulated values. The maximum measured directivity is equal to 5.9 dBi and 4.75 dBi in the case of the two- and three- elements, respectively. The proposed antenna arrays can serve for the realization of point-to-point wireless links and can have a significant impact on compact and high-directive radiofrequency front-ends of a wireless system and for wireless power transfer applications.

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J A, Akshay. "Design and VLSI implementation of SRAM memory array using Application-specific Integrated circuits design flow." International Journal for Research in Applied Science and Engineering Technology 11, no. 5 (May 31, 2023): 4047–58. http://dx.doi.org/10.22214/ijraset.2023.52570.

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Abstract Static Random-access memory (SRAM) are useful structure blocks in operations like data storage, embedded operations, cache recollections, microprocessors. The circuits should retain larger impunity to noise voltages. So, the Stationary Noise Margin (SNM) of the circuits should be veritably high. Large SRAM arrays that are extensively used as cache memory in microprocessors and operation-specific integrated circuits can absorb a big portion of the chip area. Highly compact circuits like SRAM arrays are estimated to cover relatively 90% of the System on chip area within the coming years. To optimize the performance of similar chips, large arrays of fast SRAM help to speed up the system performance. As a result, numerous minimal-size SRAM cells are tightly packed making SRAM arrays the compact circuitry on a chip. In this work an attempt is made to design a 8 X 8 SRAM memory array along with different components like Write driver circuit, Pre-charge circuit, Row and Column Decoder. Different SRAM architectures such as 6T, 7T and 8T are designed and different parameters such as Static Noise Margin and power dissipated are measured and the best performing memory design has been selected. 8T design has been resulted with least power dissipation. Hence this cell is selected for designing the memory array. A schematic of 8 x 8 array is designed and the layout of single SRAM 8T is created and to complete the ASIC design flow, DRC is done and the pre and post simulation are compared and verified. The integrated SRAM is operated with an input voltage of 0 to 1.8V.

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Hiraya, Atsunari, Katsuhide Yoshida, Sinya Yagi, Masaki Taniguchi, Shin-ichi Kimura, Hiroyuki Hama, Takeshi Takayama, and Daizo Amano. "Undulators at HiSOR – a compact racetrack-type ring." Journal of Synchrotron Radiation 5, no. 3 (May 1, 1998): 445–47. http://dx.doi.org/10.1107/s0909049597018220.

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A compact racetrack-type 700 MeV storage ring (HiSOR) has been constructed at Hiroshima Synchrotron Radiation Center (HSRC). As the ring was planned for synchrotron radiation research on science and technology using VUV to X-rays up to 5 keV with limited size and cost, the ring was designed (i) to realize a high magnetic field (2.7 T) using conventional dipole magnets for higher critical energy, and (ii) to include two straight sections for insertion devices. A linear undulator (25–300 eV) and a new-type helical/linear undulator were installed at the two straight sections. The latter undulator consists of upper and lower jaws, as in a planar undulator; each jaw consists of one fixed magnet array at the centre and two magnet arrays on both sides. By longitudinal displacement of the side magnet arrays, the phase between the vertical and horizontal magnetic fields, and therefore the polarization (right- or left-circular, elliptical, linear) can be selected. The helical/linear undulator gives almost perfect circular polarization at 4–40 eV in the helical configuration without changing the phase of the magnet arrays, as well as linearly polarized light at 3–300 eV in the linear configuration.

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Mahfoudi, Hichem, Hakim Takhedmit, Mohamed Tellache, and Sebastien Boisseau. "Wireless sensor node remote supply using a compact stacked rectenna array with voltage multipliers at 2.45 GHz." International Journal of Microwave and Wireless Technologies 12, no. 4 (October 14, 2019): 309–15. http://dx.doi.org/10.1017/s1759078719001314.

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AbstractThis paper presents compact rectenna arrays for ambient RF energy harvesting on the 2.45 GHz ISM band. The arrays are based on four and nine series-connected rectenna cells. Each cell is composed of a stacked fractal antenna and an RF-to-dc conversion circuit. The antenna is a compact third Koch fractal shape, fed by a coaxial probe for more compactness. The conversion circuit is a full-wave rectifier with a differential output, each DC polarity is provided by a two-stage Dickson voltage multiplier. Measurement results show a significant increase of the output DC voltage for the one, four, and nine cells rectenna arrays. They provide, for power density of 1.7 μW/cm2, an output DC voltage of 0.9, 2.2, and 4.1 Volts, respectively. The 9 cells rectenna array is used in a remote supply experiment of a temperature and acceleration wireless sensor, where the data are transmitted via a Bluetooth low energy link to a distant smartphone every 1 min.

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Criado, Á. R., J. Montero-dePaz, C. de Dios, L. E. García, D. Segovia, and P. Acedo. "Photonic Heterodyne Pixel for Imaging Arrays at Microwave and MM-Wave Frequencies." Advances in Optical Technologies 2012 (October 18, 2012): 1–7. http://dx.doi.org/10.1155/2012/792571.

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The use of photonic heterodyne receivers based on semiconductor optical amplifiers to be used in imaging arrays at several GHz frequencies is evaluated. With this objective, a imaging array based on such photonic pixels has been fabricated and characterized. Each of the receiving optoelectronic pixels is composed of an antipodal linear tapered slot antenna (LTSA) that sends the received RF signal directly to the electrical port of a semiconductor opticalamplifier (SOA) acting as the optoelectronic mixer. Both the local oscillator (LO) and the intermediate frequency (IF) signals are directly distributed to/from the array pixels using fiber optics, that allows for remote LO generation and IF processing to recover the image. The results shown in this work demonstrate that the performances of the optoelectronic imaging array are similar to a reference all-electronic array, revealing the possibility of using this photonic architecture in future high-density, scalable, compact imaging arrays in microwave and millimeter wave ranges.

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Simonovic, Alexander, and Tinus Stander. "A K-Band Series-Fed WR42 Waveguide Horn Array with Beam Squint Reduction through Shunt Delay Sections." International Journal of RF and Microwave Computer-Aided Engineering 2023 (May 23, 2023): 1–6. http://dx.doi.org/10.1155/2023/1319502.

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Series feeds are commonly used in antenna arrays because of their compact size and low loss compared to corporate feeds but typically feature beam squint over wide bandwidths. This work proposes a series-fed waveguide horn array with reduced beam squint by introducing synthesized time delay sections between the horns and the feed line. The array, implemented in a WR42 waveguide, achieves 1.53° beam squint over a 4 GHz operating band, compared to 10.52° for a reference design without time delay compensation.

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Zheng, Bin, Xiangyang Li, Xin Rao, and Na Li. "Multi-Beam Conformal Array Antenna Based on Highly Conductive Graphene Films for 5G Micro Base Station Applications." Sensors 22, no. 24 (December 10, 2022): 9681. http://dx.doi.org/10.3390/s22249681.

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Recently, micro base station antennas have begun to play a more important role in 5G wireless communication, with the rapid development of modern smart medical care, the Internet of things, and portable electronic devices. Meanwhile, in response to the global commitment to long-term carbon neutrality, graphene film has received significant attention in the field of antennas due to its low carbon environmental impact and high electrical conductivity properties. In this work, a conformal array antenna based on highly conductive graphene films (CGF) is proposed for 5G millimeter-wave (MMW) applications. The proposed antenna consists of three antenna arrays, with eight patch elements in each array, operating at 24 GHz, with linear polarization. Each antenna array’s current amplitude distribution coefficient is constructed by synthesizing a series-feeding linear array using the Chebyshev method. The measurement results demonstrated that the proposed CGF antenna exhibits a peak realized gain higher than 8 dBi in the bandwidth of 23.0–24.7 GHz. The proposed antenna achieves three independent beams from bore-sight to ±37° in conformal installations, with a cylinder radius of 30 mm, showing excellent beam-pointing performance. These characteristics indicate that the CGF can be used for the design of MMW micro base station antennas, fulfilling the requirements of the conformal carrier platform for a lightweight and compact antenna.

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Ramachandran, Rakesh C., Ganesh Raman, and Robert P. Dougherty. "Noise Source Localization Using a Compact Phased Array: Studies on a Full Scale Wind Turbine in a Wind Farm." Wind Engineering 36, no. 5 (October 2012): 589–604. http://dx.doi.org/10.1260/0309-524x.36.5.589.

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Locating the dominant noise sources on a wind turbine is an important problem in designing and developing low noise wind turbines. Previously very large microphone arrays were used to locate these sources. The primary focus of this paper is to show that using a compact and mobile microphone array with advanced beamforming algorithms, the noise sources can be successfully located and quantified. The results from the qualification experiments on the microphone array conducted in laboratory using synthetic noise sources show the differences between the various beamforming algorithms used in this study (both frequency and time domain algorithms). The initial experimental results on a full scale wind turbine reveal that it is indeed possible to locate the noise sources using a compact microphone array by successfully locating the two dominant noise sources on the wind turbine namely, aerodynamic noise near the blade tip and mechanical noise from nacelle.

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LIN, JIE, YUE JIANG, and DON ADJEROH. "THE VIRTUAL SUFFIX TREE." International Journal of Foundations of Computer Science 20, no. 06 (December 2009): 1109–33. http://dx.doi.org/10.1142/s0129054109007066.

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We introduce the VST (virtual suffix tree), an efficient data structure for suffix trees and suffix arrays. Starting from the suffix array, we construct the suffix tree, from which we derive the virtual suffix tree. Later, we remove the intermediate step of suffix tree construction, and build the VST directly from the suffix array. The VST provides the same functionality as the suffix tree, including suffix links, but at a much smaller space requirement. It has the same linear time construction even for large alphabets, Σ, requires O(n) space to store (n is the string length), and allows searching for a pattern of length m to be performed in O(m log |Σ|) time, the same time needed for a suffix tree. Given the VST, we show an algorithm that computes all the suffix links in linear time, independent of Σ. The VST requires less space than other recently proposed data structures for suffix trees and suffix arrays, such as the enhanced suffix array [1], and the linearized suffix tree [17]. On average, the space requirement (including that for suffix arrays and suffix links) is 13.8n bytes for the regular VST, and 12.05n bytes in its compact form.

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Mramor-Kosta, Neža, and Eva Trenklerová. "On basic embeddings of compacta into the plane." Bulletin of the Australian Mathematical Society 68, no. 3 (December 2003): 471–80. http://dx.doi.org/10.1017/s0004972700037874.

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A compactum K ⊂ ℝ2 is said to be basically embedded in ℝ2 if for each continuous function f: K → ℝ there exist continuous functions g, h: ℝ → ℝ such that f(x, y) = g(x) + h(y) for each point (x, y) ∈ K. Sternfeld gave a topological characterization of compacta K which are basically embedded in ℝ2 which can be formulated in terms of special sequences of points called arrays, using arguments from functional analysis. In this paper we give a simple topological proof of the implication: if there exists an array in K of length n for any n ∈ ℕ, then K is not basically embedded.

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Guan, Huan, Xingrui Huang, Donghe Tu, Hang Yu, Yuxiang Yin, Zhiguo Yu, and Zhiyong Li. "Two-Dimensional Elliptical Microresonator Arrays for Wide Flat Bandwidth and Boxlike Filter Response." Photonics 9, no. 11 (October 28, 2022): 814. http://dx.doi.org/10.3390/photonics9110814.

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Based on two-dimensional elliptical microresonator arrays, we designed and fabricated a compact filter on the silicon-on-insulator platform with potential applications for on-chip optical interconnects. The fabricated optical filter exhibits a wide flat bandwidth of 951 GHz with the shape factor of 0.57 at the through port for the 3×20 arrays. The out-of-band rejection is as high as 50 dB. The crosstalk is also very low (−46 dB). The spectral shows a boxlike response. Although there are sixty rings used in the array, the insertion loss is still very small (≤1.36 dB).

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Gong, Jianwen, Ji Zhou, Haifeng Sun, Song Hu, Jian Wang, and Junbo Liu. "Mask-Shifting-Based Projection Lithography for Microlens Array Fabrication." Photonics 10, no. 10 (October 11, 2023): 1135. http://dx.doi.org/10.3390/photonics10101135.

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Microlens arrays play a critical role in enhancing imaging systems due to their outstanding optical performance, compact size, and lightweight nature. However, traditional fabrication methods for microlens arrays suffer from low precision, inefficiency, high costs, and a lack of adequate surface figure control. In this paper, we present a novel approach for microlens array fabrication, using a projection lithography process with mask-shifting. The method employs a 0.2× projection objective lens to enhance linewidth resolution. By employing a projection-based mask-shift filtering technique, we achieve superior surface figure accuracy while reducing the complexity of mask preparation. The experimental results for four microlenses with different aperture sizes demonstrate surface figure accuracy in the submicron range and surface roughness at the nanometer level. In addition, 3D profilometer scanning equipment was employed to measure the surface roughness of these microlens arrays, and the measurement results of these microlens arrays processed using the proposed method for their surface roughness are 18.4 nm, 29.6 nm, 34.4 nm, and 56.1 nm. Our findings indicate that this method holds great potential in microlens array fabrication, offering the ability to achieve lower linewidths and higher surface figure accuracy compared to conventional methods.

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Agudo, Òscar Calderón, Philippe Caprioli, and Dirk-Jan van Manen. "A spatially compact source designature filter." GEOPHYSICS 81, no. 2 (March 1, 2016): V125—V139. http://dx.doi.org/10.1190/geo2015-0259.1.

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Source arrays are usually tuned for optimum primary-to-bubble ratio of the output. In addition, they may also be designed to mitigate source ghost effects, but such configurations introduce directivity effects as the generated downgoing wavefield varies with the source angles. We have investigated a practical source signature deconvolution operator, valid for any marine source array, which is able to remove source ghosts, residual bubble, and directivity effects from seismic data. The designature operator was designed to be a small wavenumber approximation of the inverse of the far-field signature of a source array, which involved the array geometry, the notional source signatures, and the firing synchronization of the sources. We have found that such an approximation leads to the design of spatially compact source designature (CSD) filters able to correct for shot-to-shot perturbations of the sources’ output and reduced their smearing due to the limited spatial aperture of the filters. They also had the potential to account for some source directivity and source ghost effects when applied to common receiver gathers. Our method was then further studied for a particular synchronized multilevel source array and azimuthal variations were neglected. First, tests on synthetic data were performed and the benefits and limitations of the approach were analyzed. Second, the method was tested on a field data set under further approximations that simplified the processing flow (1D earth and average notionals) and which enabled the direct application to common shot gathers. Our results have determined that the expected small — but nevertheless observable — improvements of source designature even at the target level improved event continuity, dephasing, and sharpening of the wavelet. Additionally, the CSD filter was used in conjunction and compared with the current best-practice data processing techniques.

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Gülink, Jan, Steffen Bornemann, Hendrik Spende, Matthias Auf der Maur, Aldo Di Carlo, Joan Daniel Prades, Hutomo Suryo Wasisto, and Andreas Waag. "InGaN/GaN nanoLED Arrays as a Novel Illumination Source for Biomedical Imaging and Sensing Applications." Proceedings 2, no. 13 (December 6, 2018): 892. http://dx.doi.org/10.3390/proceedings2130892.

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Guidelines for the fabrication of nanoscale light-emitting diode arrays (i.e., nanoLED arrays) based on patterned gallium nitride (GaN) with very small dimensions and pitches have been derived in this work. Several challenges during top-down LED array processing have been tackled involving hybrid etching and polymer-based planarization to yield completely insulated highaspect-ratio LED fin structures and support the creation of p-GaN crossing line contacts, respectively. Furthermore, simulations of the light emission patterns were also performed providing hints for enhancing the device designs. As a result, regardless of the required device processing optimization, the developed nanoLED arrays are expected to offer high potential as novel illumination sources in biomedical imaging and sensing applications (e.g., mini compact microscopes and wearable biological/chemical nanoparticle counters)

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Feng Zhihua, 封治华, 袁硕 Yuan Shuo, 陈益姝 Chen Yishu, 刘海鹏 Liu Haipeng, 毕群玉 Bi Qunyu, 张福领 Zhang Fuling, and 冯吉军 Feng Jijun. "结构紧凑的高均匀性硅波导阵列波导光栅." Chinese Journal of Lasers 50, no. 22 (2023): 2219001. http://dx.doi.org/10.3788/cjl230484.

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Fan, Yuanlong, K. Alan Shore, and Xiaopeng Shao. "Dynamics of Electrically Pumped Semiconductor Nano-Laser Arrays." Photonics 10, no. 11 (November 10, 2023): 1249. http://dx.doi.org/10.3390/photonics10111249.

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Semiconductor nano-lasers have been actively investigated both theoretically and experimentally with to the aim of providing a highly compact laser amenable to photonic integration. Such devices are naturally suited for assembly in close-packed one- and two-dimensional arrays. In such arrangements, optical coupling between elements of the array opens opportunities to generate a range of dynamical behaviours. In this paper, we present the first theoretical treatment of the dynamics of electrically pumped nano-laser arrays. Two specific forms of such arrays are analysed in detail: a three-element linear array, and triangular arrays. The former is the basis for extensive one-dimensional arrays, whilst the latter is a building block of many possible geometric configurations of two-dimensional nanolaser arrays. Using these prototypical configurations enables the identification of novel dynamical behaviours, which may be accessed using nano-laser arrays. A distinguishing physical feature of nano-lasers is the enhancement of the spontaneous emission rate via the so-called Purcell effect. Allowing for a range of Purcell enhancement factors, the analysis focusses on the effects of experimentally controllable parameters such as the laser drive current. It is shown that the Purcell enhancement factor is critical to the availability of a range of dynamical behaviours which arise simply due to inter-element optical coupling. Two-dimensional portraits of the regimes of differing dynamics offer a convenient means for determining the dynamics which may be accessed by varying the laser drive current.

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Semouchkina, Elena, Arash Hosseinzadeh, and George Semouchkin. "Realization of High-Q Fano Resonances in Ceramic Dielectric Metamaterials for Sensing Applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, CICMT (September 1, 2013): 000087–93. http://dx.doi.org/10.4071/cicmt-2013-wa14.

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Ceramic all-dielectric metamaterials are found to support very high Q resonances of the Fano-type, which until recently were largely attributed to the atomic physics phenomena. It is shown that proper arrangement of ceramic resonators in the metamaterial array allowsd for obtaining Q factors up to 15000. Thus high Q factors could be employed for new applications, in particular, for advanced sensing. An opportunity to design compact arrays that could be incorporated in a microwave sensor fed by a microstrip line is demonstrated. Numerical experiments have confirmed that Fano resonances in such arrays conserve high sensitivity to the dielectric permittivity of the controlled media.

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Cha, Young-Gil, Jiwoong Na, Hyun-Kyung Kim, Jae-Myeong Kwon, Seok-Haeng Huh, Seung-Un Jo, Chang-Hwan Kim, Min H. Kim, and Ki-Hun Jeong. "Microlens array camera with variable apertures for single-shot high dynamic range (HDR) imaging." Optics Express 31, no. 18 (August 21, 2023): 29589. http://dx.doi.org/10.1364/oe.498763.

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We report a microlens array camera with variable apertures (MACVA) for high dynamic range (HDR) imaging by using microlens arrays with various sizes of apertures. The MACVA comprises variable apertures, microlens arrays, gap spacers, and a CMOS image sensor. The microlenses with variable apertures capture low dynamic range (LDR) images with different f-stops under single-shot exposure. The reconstructed HDR images clearly exhibit expanded dynamic ranges surpassing LDR images as well as high resolution without motion artifacts, comparable to the maximum MTF50 value observed among the LDR images. This compact camera provides, what we believe to be, a new perspective for various machine vision or mobile devices applications.

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Zheng, Jianfeng, Yue Li, and Zhenghe Feng. "Impact of Mutual Coupling and Polarization of Antennas on BER Performances of Spatial Multiplexing MIMO Systems." International Journal of Antennas and Propagation 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/795205.

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This paper is aimed at studying the impacts of mutual coupling, matching networks, and polarization of antennas on performances of Multiple-Input Multiple-Output (MIMO) systems employing Spatial Multiplexing (SM). In particular, the uncoded average Bit Error Rate (BER) of MIMO systems is investigated. An accurate signal analysis framework based on circuit network parameters is presented to describe the transmit/receive characteristics of the matched/unmatched antenna array. The studied arrays consist of matched/unmatched compact copolarization and polarization diversity antenna array. Monte-Carlo numerical simulations are used to study the BER performances of the SM MIMO systems using maximum-likelihood and/or zero-forcing detection schemes. The simulation results demonstrate that the use of matching networks can improve the BER performance of SM MIMO systems significantly, and the BER performance deterioration due to antenna orientation randomness can be compensated by use of polarization diversity antenna arrays.

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Takhedmit, Hakim, Laurent Cirio, Boubekeur Merabet, Bruno Allard, François Costa, Christian Vollaire, and Odile Picon. "A 2.45-GHz dual-diode rectenna and rectenna arrays for wireless remote supply applications." International Journal of Microwave and Wireless Technologies 3, no. 3 (June 2011): 251–58. http://dx.doi.org/10.1017/s1759078711000523.

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Abstract:

This paper describes a compact and efficient rectenna based on a dual-diode microstrip rectifier at 2.45 GHz. This circuit has been designed and optimized using a global analysis technique which associates electromagnetic and circuit approaches. Due to the differential topology of the rectifier, neither input low-pass filter nor via-hole connections are needed. This makes the structure more compact reducing losses. Measurements of a single rectenna element show 83% efficiency over an optimal load of 1050 Ω at a power density of 0.31 mW/cm2. To increase the received RF power and then increase dc power over the load, identical rectennas have been interconnected to form arrays. Two and four elements rectenna arrays, connected either in parallel or in series, have been developed. It was shown that by properly choosing the interconnection topology and the optimal output load, higher dc voltage or dc power have been obtained. The four-element series-connected array can provide experimentally up to 3.85 times output dc voltage compared to the single rectenna. The parallel-connected rectenna arrays generate approximately 2.15 and 3.75 times output dc power for two and four elements, respectively.

Journal articles on the topic 'Compacts arrays'

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