Planar Pattern Research Articles

Persistent Placoid Maculopathy: Lichen-like Lesions Growing between Retinal Pigment Epithelium and Bruch’s Membrane

To report the novel imaging findings in persistent placoid maculopathy (PPM) from the first case series of Asian subjects. Retrospective observational case series. Patients with PPM included from 2013-2023. Medical records and multimodal imagings at each visit were analyzed. Imaging and follow-up findings. Twenty-one eyes of 16 patients were included. Mean age was 61 (range, 48-84) years old. Five patients were involved bilaterally. PPM lesions were unremarkable on color fundus photography, autofluorescence and fluorescein angiography. Hypofluorescence with lichen-like appearance presented in all phases of indocyanine green angiography, which were most prominent in the late-phase and presented in fused (71%) or clustered (29%) pattern. The hypofluorescence correlated to the lesions between retinal pigment epithelium (RPE) and Bruch's membrane (BM) with moderate reflectivity on OCT, the thickness of which ranged from thickening of the RPE-BM complex, slit-like to mound-like. The intensity of hypofluorescence may vary in the same eye, and correlated to the thickness of sub-RPE lesions on OCT. No abnormal blood flow signals were detected on either sub-RPE space or choriocapillaris slab of OCT angiography across the PPM lesions. Peripapillary (5 eyes, 24%) and extra posterior-pole (2 eyes, 10%) involvements were seen, with the former of which sparing the β zones of optic discs. Ten eyes of 7 patients were followed up (median, 26 months; range, 2-121 months). During follow-up, the lichen-like lesions spread and migrated slowly without changing the plane patterns of the first visit, and were limited to sub-RPE growth. The fused lichen-like pattern sprawled around the enlarged base. The clustered lichen-like pattern gradually loosened. Ten eyes (48%, 9 eyes in fused pattern, 1 eye in clustered pattern) had secondary choroidal neovascularization (CNV) at the first visit, with type I (6 eyes, 5 of which were polypoidal choroidal vasculopathy) and type II (4 eyes). No new CNV developed during follow-up. PPM lesions locate in the sub-RPE space, determined by multimodal imaging. Spreading and migration between RPE and BM may account for their unique lichen-like appearance and progression pattern.

Multilayer printed antenna with circular directional pattern and increased directional coefficient

Formulation of the problem. The article explores the possibility of using an array of square open frames to increase the directivity of a multilayer printed antenna with a circular radiation pattern in the azimuthal plane and horizontal polarization. Target. Develop a multi-layer dual-band antenna with increased directivity, emitting/receiving a radio signal in all directions in the azimuthal plane with horizontal polarization. First frequency range: GSM-1800, LTE-1800, UMTS-2100; second frequency band: n79 5G. Results. A new design of a multilayer antenna is proposed, consisting of three printed circuit boards located one above the other. A circular antenna array of F-shaped radiators is placed on the lower dielectric substrate. It is excited by a high-frequency connector. The second board contains arc-curved dipoles located along two circles of different diameters. On the third dielectric substrate there is an array of 45 square open frames. The electrodynamic characteristics of the antenna are calculated and the influence of the array of frames on the directivity coefficient is studied. The antenna operates in two frequency ranges 1.62…2.32 GHz and 4.23…4.95 GHz, the maximum directivity in the first frequency range is 1.9 dB, and in the second 4.6 dB. Practical significance. The antenna can be used as an element of an omnidirectional antenna array of cellular communications of 2-5G generations, to implement the Internet of Things technology, to communicate with moving objects.

Studi Etnomatematika Pada Motif Batik Troso Jepara Dalam Bentuk Geometri Dua Dimensi

This study aims to explore the concept of a flat shape in the troso batik motif, so that this concept can be developed as a teaching material for elementary school students. Data collection techniques through observation, semi-structured interviews, and document archiving. From the results of the study it is shown that many Jepara troso batik motifs can be applied as a medium to introduce mathematical concepts, especially the concept of flat geometric shapes. The geometry concept shown is in the form of flat shapes, such as square, rectangle, triangle, parallelogram, rhombus, kite, and combined plane patterns. The geometric concept found can be used as teaching material in the form of printed, visual, or other teaching materials, adapted to the learning needs of students

Position‐only planar hexagonal array antenna pattern nulling with simultaneous side lobe reduction at multiple azimuth planes

SummaryThis article presents a study on the placement of multiple nulls as well as minimization of side lobe level in the radiation pattern using a planar hexagonal antenna array structure in two different vertical planes. The desired null depth is achieved to suppress the interference signal by the position‐only control of the uniformly excited isotropic antennas in the array structure. The immediate solution to the mentioned computational problem is reached by various meta‐heuristic optimization algorithms such as teaching learning‐based optimization (TLBO), symbiotic organism search (SOS), and moth fly optimization (MFO) within a considerably reduced processing time with a control over the design constrains. Various examples for diversified scenarios are demonstrated to place multiple deep nulls in the radiation pattern without compromising the pattern constraints and all other radiation pattern characteristics. This experiment sought to illustrate and quantify the unique benefits and limitations of proposed technique using three considered meta‐heuristic optimization algorithm.

A planar switched‐beam antenna with compact size

AbstractA planar pattern reconfigurable patch antenna is proposed. The proposed antenna is a circular array composed of three radiating elements, and each element can generate a horizontally polarized main beam with a half‐power beamwidth of about 135°. To switch the beam direction, a single‐pole three‐through circuit is designed on the same printed circuit board as the radiating elements, and the total area of the integrated planar antenna is a circular shape of diameter 0.37λ0. A prototype operated at 2.45 GHz is constructed, and the measured results demonstrate that the pattern reconfigurable antenna can give three steerable beams in the E plane, and the gain and the front‐to‐back ratio of each beam are 3.2 dBi and 15 dB, respectively; moreover, an operation bandwidth of more than 10% is also achieved. Simulated analyses are also performed to explain the antenna performances mentioned above, and they have good agreements with the experimental data.

Wafer-scale heteroepitaxy GaN film free of high-density dislocation region with hexagonal 3D serpentine mask

GaN-based III-Nitride compound semiconductors are fundamental materials for high-performance optoelectronic and electronic devices. Low-defect-density substrate has been a major bottleneck in achieving high internal quantum efficiency and high breakdown voltage in those devices. However, a large-scale and uniform low dislocation density GaN film is still hard to obtain on foreign substrates, which is the mainstream economical method in scientific research and industrial production. Here, we present a 3D serpentine mask method of growing high-quality GaN film on foreign substrates without high dislocation density (HDD) areas by designing both sectional and planar shapes of stacked masks. The serpentine channel in the cross-section mechanically blocks the extended dislocations and the hexagonal planar pattern reduces the dimension of coalescence geometry. A wafer-scale GaN epilayer, free of HDD zone, with the overall threading dislocation density of 1.7 × 107 cm−2 estimated by plan-view cathode luminescence, is achieved in the metal-organic chemical vapor deposition system. Then, an array of light-emitting diodes based on this substrate with low forward voltages and high light output powers are fabricated, which introduces a practical method to provide high-quality GaN films for high-performance optoelectronic devices.

Compact SCSRR‐based quad‐band antenna for Bluetooth, WiMAX, WLAN, and fixed‐satellite services

SummaryThis research describes the detailed analysis and design of the compact complex‐free structural metamaterial quad band radiating element applicable for Bluetooth, WiMAX, WLAN, and fixed‐satellite service. The radiating element designed is composed of an inner angle‐rotated circular Split Ring Resonator (SRR) placed within the outer square‐shaped SRR interlinked by a strip to design the multiband operational characteristics and is fed by a coplanar waveguide. Suggested radiating element is imprinted over the FR4 substrate material with the electrical dimension of 28 × 31.26 × 0.8 mm3. The initial outer‐closed square ring offers dual‐band operation by resonating at 2.8 and 8.5 GHz frequencies, and the incorporation of a circular SRR offers quad‐band operation. The unique negative permeability feature of the proposed Square and Circular Split Ring Resonator (SCSRR) structure is extracted, and its band characteristics are analyzed. Results obtained from the simulated radiating element are validated with the fabricated antenna. The measured E plane pattern resembles a numeric eight shape, and the H plane pattern is omnidirectional. Suggested SCSRR antenna offers a gain of above 3.2 dBi in all the operating bands.

A Gain-Enhanced Differential-Fed Stacked Circular Patch Antenna With Simultaneously Controllable E-Plane and H-Plane Radiation Nulls

In this work, a differential-fed three-layer stacked circular patch antenna with enhanced gain performance is theoretically investigated for the simultaneous control of radiation nulls over both <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -plane and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane patterns. First, the bottom layer patch is meticulously designed based on a modified TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode to meet the matching conditions. Then, the structures of the parasitic layer patches are contrived to form similar peripheral radiative current distributions compared with the bottom one, aiming to simplify the analysis process. After that, the three-layer patches are stacked in a capacitively coupled fashion, which guarantees the out-of-phase scheme between the middle layer patch and the other two-layer patches. By means of the cavity-model theorem, further investigations on the multilayer distributions of the equivalent magnetic currents for the three radiators have successfully demonstrated that the destructive interference among the currents will result in the emergence of radiation nulls for both <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -plane and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane patterns. As a result, the beamwidth of the antenna in the two principal planes can be narrowed, which contributes to a significant improvement in the overall gain performance. Furthermore, a thorough array factor analysis on the flexible control of the radiation nulls is highlighted with both theoretical predictions and full-wave quantitative verifications. Finally, an experimental prototype is fabricated and measured to prove its validity. Compared with other stacked antennas with approximately the same longitudinal profiles, this design features the highest measured peak gain of 13.9 dBi, with an attractive increment of 8.0 dB pronounced.

Symmetric Perfect and Symmetric Semiperfect Colorings of Groups

Let G be a group. A k-coloring of G is a surjection λ:G→{1,2,…,k}. Equivalently, a k-coloring λ of G is a partition P={P1,P2,…,Pk} of G into k subsets. If gP=P for all g in G, we say that λ is perfect. If hP=P only for all h∈H≤G such that [G:H]=2, then λ is semiperfect. If there is an element g∈G such that λ(x)=λ(gx−1g) for all x∈G, then λ is said to be symmetric. In this research, we relate the notion of symmetric colorings with perfect and semiperfect colorings. Specifically, we identify which perfect and semiperfect colorings are symmetric in relation to the subgroups of G that contain the squares of elements in G, in H, and in G∖H. We also show examples of colored planar patterns that represent symmetric perfect and symmetric semiperfect colorings of some groups.

Experimental and numerical simulation of a dual-band omnidirectional printed antenna

Currently, there are many radio engineering and telecommunication systems, the exchange of information in which is carried out using radio signals. For each system, it is necessary to develop new antennas operating in a certain frequency range. Therefore, an urgent problem is development of radiating devices capable of operating simultaneously in two or more wide frequency ranges. This will allow the antenna to be used for multiple applications. The aim of the article is to develop and implement a small-sized printed antenna with a circular pattern in the azimuthal plane and horizontal polarization of the vector E, emitting and receiving a radio signal in the bands corresponding to the GSM-1800, LTE-1800, UMTS-2100 and n79 5G standards. An original design of a multilayer printed antenna with a circular radiation pattern in the azimuthal plane and horizontal polarization has been developed. The antenna consists of two printed circuit boards located one above the other. The bottom board contains a ring array of F-shaped radiators, which is excited using a high-frequency connector. The top board contains an array of passive dipoles that are excited by an electromagnetic field created by a ring array of F-shaped dipoles. According to the calculation results, the antenna emits and receives a radio signal in two frequency ranges: 1,65–2,38 GHz and 4,21–5 GHz (in terms of VSWR = 2). An antenna model has been made, its electrodynamic characteristics have been measured, and the experiment and simulation results have been compared. The developed antenna can be used as an independent radiator or an element of an omnidirectional antenna array of cellular communication standards GSM-1800, LTE-1800, UMTS-2100 and n79 5G.

Planar Spin Glass with TopologicallyProtected Mazes in the Liquid Crystal Targeting for Reconfigurable Micro Security Media.

The planar spin glass pattern is widely known for its inherent randomness, resulting from the geometrical frustration. As such, developing physical unclonable functions (PUFs)-which operate with device randomness-with planar spin glass patterns is a promising candidate for an advanced security systems in the upcoming digitalized society. Despite their inherent randomness, traditional magnetic spin glass patterns pose considerable obstacles in detection, making it challenging to achieve authentication in security systems. This necessitates the development of facilely observable mimetic patterns with similar randomness to overcome these challenges. Here, a straightforward approach is introduced using a topologicallyprotected maze pattern in the chiral liquid crystals (LCs). This maze exhibits a comparable level of randomness to magnetic spin glass and can be reliably identified through the combination of optical microscopy with machine learning-based object detection techniques. The "information" embedded in the maze can be reconstructed through thermal phase transitions of the LCs in tens of seconds. Furthermore, incorporating various elements can enhance the optical PUF, resulting in a multi-factor security medium. It is expected that this security medium, based on microscopically controlled and macroscopically uncontrolled topologicallyprotected structures, may be utilized as a next-generation security system.

The effect of different particle sized rations and live yeast supplementation on energy profile in dairy cows in heat stress

The aim of the present study was to determine the effect of adding different sized feed particles and live yeast culture (LY) to the rations of dairy cattle on their metabolic energy balance and some blood parameters under heat stress conditions. In this study, four Holstein-Fresiean dairy cattle (600 ± 25 kg of BW) in the middle of the lactation, which gave multiple births, were used. The cattle were fed with diets containing 2 different doses of LY additives (0 and 1 g/day/dairy cattle) in 2 different particle sizes (High particle size (HPS) and Short particle size (SPS)). The experiment was carried out in 2x2 factorial plane and 4x4 latin square pattern. During the study, it was determined that the averages of the temperature humidity index (THI) were above 76.&#x0D; In the present study, the effect of LY supplementation on the live weight (BW) change and on feed consumption was not determined. However, it was observed that the non esterified fatty acids (NEFA), beta hydroxybutyric acid (BHBA) and glucose levels of dairy cattle decreased significantly, while the urea level increased with the supplementation of LY to the ration (P

Peacock patterns and resurgence in complex Chern–Simons theory

The partition function of complex Chern–Simons theory on a 3-manifold with torus boundary reduces to a finite-dimensional state-integral which is a holomorphic function of a complexified Planck’s constant tau in the complex cut plane and an entire function of a complex parameter u. This gives rise to a vector of factorially divergent perturbative formal power series whose Stokes rays form a peacock-like pattern in the complex plane. We conjecture that these perturbative series are resurgent, their trans-series involve two non-perturbative variables, their Stokes automorphism satisfies a unique factorization property and that it is given explicitly in terms of a fundamental matrix solution to a (dual) linear q-difference equation. We further conjecture that a distinguished entry of the Stokes automorphism matrix is the 3D-index of Dimofte–Gaiotto–Gukov. We provide proofs of our statements regarding the q-difference equations and their properties of their fundamental solutions and illustrate our conjectures regarding the Stokes matrices with numerical calculations for the two simplest hyperbolic textbf{4}_1 and textbf{5}_{2} knots.

ОСОБЕННОСТИ ПОСТРОЕНИЯ МОДЕЛИ ЗЕРКАЛЬНОЙ АНТЕННЫ С УЧЕТОМ ВЛИЯНИЯ МЕТЕОРОЛОГИЧЕСКИХ ФАКТОРОВ

An electrodynamic model of a millimeter-range single-mirror antenna with a puddle in the reflector is given. As a justification for the need for a model, the influence of rainfall on the design of millimeter-range mirror antennas was assessed. The aim of the study was to create a model of the parabolic reflector of a mirror antenna with an aqueous precipitation layer, with parameters chosen for the climatic region in which the antenna is located. An analysis of known models of single mirror antennas with a layer of precipitation has been carried out. It has been shown that the known models do not describe the operation of a millimeter-range mirror antenna with a reflector in which a puddle of water has formed. It is suggested that the influence of this layer on the directional characteristics of the antenna be assessed with the aperture method used for mirror antennas with reflector profile defects. The results of the modelling of the directivity pattern of a mirror antenna with a puddle of water in the reflector are presented. It is shown that the appearance of a puddle leads to an asymmetric change in the height of the first side lobes of the directivity pattern in the vertical plane. In the horizontal plane, changes are observed in the growth level of each side lobe, except for the first one. The lobes' symmetry is not affected. Research focus: The process of emitting a millimeter electromagnetic wave using a single mirror antenna with a layer of water in the reflector. Subject of the study: "Mirror antenna reflector with water precipitation layer - millimeter wavelength electromagnetic wave" system. Methods: Electromagnetic meteorological method, modified aperture method, modified Ruze method, statistical meteorological method. Main result: A wireless communication system using the magnetic component of the electromagnetic field has been developed. Practical relevance: The results of this research may be useful in the design of millimeter-range mirror antennas to assess the influence of meteorological precipitation on the directivity characteristics. The work was presented at the VIII All-Russian Microwave Conference "Microwave week 2022" in Moscow.

Evaluation of the effectiveness of using antennas with an asymmetric radiation pattern to reduce the influence of interference from the ground on detection with an average repetition rate in onboard pulse radars

Problem statement. To solve the problem of warning about possible collisions of small aircraft or unmanned aerial vehicles intended for the development of hard-to-reach territories or for search and rescue operations, it is possible to use the prediction of the trajectory of aircraft using radar information about their coordinates. It is possible to increase the time of early detection of another aircraft on intersecting trajectories by reducing the level of interference from the earth's surface in a certain range of angles, which corresponds to the selected range of detection ranges. So for small aircraft, in order to avoid collisions on intersecting and catch–up courses, this is the near range area. The study is aimed at evaluating the effectiveness of radar detection using antennas with an asymmetric radiation pattern in the vertical plane. Research methods. The mathematical apparatus of the antenna array theory was actively used in the work, as well as the methodology for calculating the parameters of radar detection for airborne radars with an average pulse repetition rate. Purpose. By modeling, to evaluate the effectiveness of the effect of reducing the side lobes in a given range of angles in the plane at the angle of the place c on reducing the effect of interference from the Earth's surface on the near detection of small aircraft when the radar carrier is flying at low altitude. Results. The simulation results are presented, showing an improvement in conditions for near-range radar detection in onboard pulse-Doppler radars with an average pulse repetition rate when using antennas with an asymmetric directional function, characterized by a reduced level of lateral radiation in the lower hemisphere. Practical significance. The results of the work can be used in small-sized on-board pulse radars of low-altitude and low-speed carriers in order to increase the time of a temporary warning about the presence of other aircraft on the flight path. This task seems to be especially relevant when flying radar carriers in developed territories with difficult terrain.

A Multicompressed-High-Order Modes Dipole Antenna With Wide-Beam and High-Gain Radiations in Two Different Bands

In this letter, a multi-compressed-high-order mode dipole antenna with wide-beam coverage and high-gain radiations in two respective sub-6 GHz bands is proposed. The capacitors and inductors are loaded at the current distribution nulls of the fifth-order mode of the dipole arms. The loading brings the resonant frequencies of the third- and the seventh-order modes closer to the fifth-order mode, and thus achieves wide bandwidth. In addition, the loadings change the current distribution of the third- and the seventh-order modes, and achieve radiation patterns with wide coverage in the lower band and high gain in the higher band. To facilitate fabrication, the capacitors and inductors are replaced by narrow slits and bending lines separately. A prototype of this design is fabricated and measured. The measurement and simulation results are in good agreement. The proposed antenna achieves a wideband of 3.30 to 5.35 GHz (VSWR < 2) with an omnidirectional radiation pattern in the horizontal plane. In addition, it achieves a ±57° coverage angle over 0 dBi in the lower band and 6.41 dBi peak gain in the higher band in the vertical plane, which can be applied for 5G wireless communication.

Shaped Omnidirectional Reflector Fed by a Dielectric Lens Associated with a Coaxial Feed Horn

The paper explores an omnidirectional antenna configuration composed of a reflector fed by a shaped dielectric lens associated with a coaxial TEM horn. A simple formula describes the lens shape obtained by applying Fermat’s principle to control the rays’ caustic emerging from the dielectric interface. Based on geometrical optics (GO) principles, a synthesis technique defines the reflector shape to control the antenna radiation pattern in the vertical plane. Concatenated conic describes the reflector generatrix. The study employs a full-wave analysis to validate the designs and explores the proposed configuration to attend two distinct far-field specifications.

Pressure Sensitivity Kernel and Travel-Time Gradient for Geoacoustic Parameters Perturbations of Sediment in Shallow Water

In shallow sea, the effect of geoacoustic characteristics of seabed sediments on acoustic propagation cannot be neglected, which is closely related to acoustic detection and seabed inversion. Aiming at the problem of low-frequency acoustic propagation, the sound pressure sensitivity kernel (PSK) and travel-time gradient (TTG) of the shallow low-frequency acoustic field for the geoacoustic parameters of sediment were presented by using normal mode model and perturbation approximation. Combined with the benchmark shallow sea model, the numerical simulation was carried out. The simulation results show that the PSK for the sound velocity of sediment are showing some interference pattern in velocity-range plane and velocity-frequency plane, and its strength is attenuated with the increase of range. TTGs have different sensitivity to the sound velocity of sediment at different range, which is more sensitive at mid-range. The PSK and TTG show some frequency selectivity.

Highly effective recovery of palladium from a spent catalyst by an acid- and oxidation-resistant electrospun fibers as a sorbent

Palladium is not only a precious metal but also is widely used in catalyst production, therefore it is of significance to recover palladium from spent catalysts. In this paper, Nanofiber modified by 2-Thionicotinic acid (TN-Nanofiber) featuring acid- and oxidation-resistant was fabricated through electrospinning and chemical grafting, which can trap efficiently Pd(II) ions from the extremely acidic and oxidizing systems derived from the leaching of spent catalyst. The adsorption kinetic data of Pd(II) ions was well described by the pseudo-second-order model, and the times required to reach equilibrium was 60 min. The Langmuir isotherm model provided better fitting for the Pd(II) ions adsorption, and the maximum uptake capacity of TN-Nanofiber was evaluated as 348.4 mg/g for Pd(II) ions. Furthermore, the column adsorption experiments proved the feasibility of TN-Nanofiber separation of Pd(II) ions from the spent catalyst. Investigation of the adsorption mechanism demonstrated a planar quadrilateral coordination pattern between the Pd(II) ions and the adsorption sites of TN-Nanofiber, which includes one N and one S atom sourced from the adsorption sites and two Cl atoms derived from the original PdCl42−. In summary, TN-Nanofiber may serve as the next generation of emerging adsorbents to recover palladium from the strongly acidic and oxidizing systems due to its excellent performance.

Optimization Design for Sparse Planar Array in Satellite Communications

The antenna is one of the key components of satellite communication load. To address the evolving requirements of future satellite communication systems, the sparse planar array has become an important device for transmitting and receiving electromagnetic waves in emerging antenna systems. The advantages of this technology include low cost, low system complexity, and robust anti-interference ability, which have attracted widespread attention within the industry. In this paper, we investigate an optimization design of sparse planar arrays in satellite communication scenarios. Firstly, we introduce the mathematical foundation of the array antennas and establish the optimization design model of the sparse planar array. Secondly, we analyze and compare the impact of different array layout methods on the sparse planar array antenna pattern, and then introduce the latest design trend of array material design. Thirdly, we review some classical optimization methods for optimizing sparse planar arrays and the recent research advancements in promising and novel methods. Lastly, on the basis of the present research status, we propose three future research directions and two critical challenges for optimal design of sparse planar arrays in satellite communication scenarios, which can facilitate the development and realization of array technology under future B5G and 6G wireless networks.