Pattern Width Research Articles

Investigation of the dependences of the Vivaldi antenna with two curve radii in the electrodynamic modeling software package

Objective. The aim of the study is to build and optimize a computer model of the antenna using software packages for electrodynamic modeling.Method. The study is based on dynamic modeling methods.Result. In this paper, the dependences of the width of the radiation pattern on the curved Vivaldi antenna with a mirror arrangement of the petals are obtained. Graphs of the dependence of the radii of curved petals and aperture values on the width of the radiation pattern in two planes for frequencies of 3 and 24 GHz are plotted. Curve radius, antenna aperture and lower antenna height are plotted as functions of the maximum beamwidth for 24 GHz and the minimum beamwidth for 3 GHz. The obtained dependencies were approximated for two planes θ = 900 (antenna aperture plane) and φ = 00 (plane perpendicular to the antenna aperture plane). By means of regression analy sis, analytical descriptions and graphs of dependences of the maximum beamwidth for 24 GHz and the minimum beamwidth for 3 GHz, on the radii of the curves, aperture and the height of the lower curve of the antenna lobe were obtained.Conclusion. The resulting mathematical model makes it possible to obtain the values of the radius of the curve, the opening and the lower height of the antenna lobes for different frequencies, as a result, to build a Vivaldi antenna with the desired topology.

Losses in bifacial PERC solar cell due to rear grid design and scope of improvement

Photovoltaic (PV) industries are continuously trying to improve the module performance with the adoption of newer cell technologies. Recently, bifacial passivated emitter rear contact (PERC) solar cell technology has entered the market to further improve the module performance through the absorption of the extra photons reflected from the background. This work is mainly focused on optimizing the rear side grid pattern of the bifacial PERC solar cells for improvement of the total output power gain. We have developed an analytical model based on the front and rear grid pattern of commercially available bifacial PERC solar cells to calculate the optical shading and electrical losses for both sides of the solar cells. It is perceived that the rear shading loss due to rear grid design of industrial bifacial PERC solar cells is very high (∼30%) as compared to the front side (∼5%) of the cells. The model calculation shows that if with the improved laser scribing technology the finger width of the rear grid pattern be drastically reduced from ∼ 200 μm (measured value) to 25 μm the optical shading loss may be minimized to 11–14% from 30% without compromising the effective busbar resistance.

GaN-based mini-LED matrix applied to multi-functional forward lighting

In this paper, we propose and demonstrate to use of a single reflector with 68 segments to project vehicle low beam and high beam with the use of a GaN-based mini-LED matrix, which is a 5 × 6 LED die array. The design of the reflector is based on light field technology in considering etendue from the light source across the segments. The group of the segments with smaller etendue from the LED dies in the bottom 2 rows are used to project low beams. When the other LED dies are turned on, the reflector will project light upward and form the high beam. The selection of the turn-on LED dies in the mini-LED matrix can adjust the width of the illumination pattern so that an adaptive low/high beam can be performed. Besides, to extend the functionality of the headlamp module, we propose to dispense IR phosphor on LED dies in the high-beam zone of the GaN-based mini-LED matrix. Thus the vehicle can emit IR high beam, which can be imaged through a camera and can be incorporated with machine vision for an autonomous vehicle without using a complicated adaptive headlight to avoid glare. The proposed multi-function in spatial and spectral domains will be helpful to various applications with use of a mini-LED matrix.

Measuring the refractive index of scintillation crystal with a Mach-Zehnder interferometer

The refractive index of the scintillation crystal is a key parameter in the design of Positron Emission Tomography (PET) devices. However, existing methods to measure the refractive index always suffer from problems such as the complexity of optical path adjustment, long time cost, or high equipment consumption. To overcome these problems, we propose a method that can obtain the refractive index of the scintillation crystal with high accuracy in real time. In this method, we employ the Mach-Zehnder interferometer to generate the interference pattern when one beam of light passes through the scintillation crystal, which encodes the value of refractive index into the width of pattern. To obtain the width of interference pattern, we calculate the width pixels of dark/bright stripes in pattern with threshold, respectively, and finally get the average number of pixels of the pattern; this strategy can eliminate the coherent interference signal and random noise effectively. The optical path need not adjust during the whole measurement. Thus, the refractive index of scintillation crystals can be measured with reliability and efficiency. To validate the effectiveness of the proposed method, we measure different batches of BGO crystal and Ce:LYSO crystal samples. The results show that the proposed method can measure refractive indices with high accuracy and high efficiency, providing a reliable crystal refractive index measurement procedure for the PET detector module design. The proposed method is also suitable for refractive index measurements of transparent materials in visible light bands.

Morphological variability of stomatocyst 131 Pang & Wang (Chrysophyceae) from a freshwater shallow lake in South Urals, Russia

Stomatocyst 131 Pang & Wang was described from the sedge mires and puddles in the Aershan Geological Park, China and it has not been reported from other localities since its description. We recorded stomatocyst 131 from a shallow lake Zhurmankol in South Urals, Russia. Morphological variability of this morphotype was studied using scanning electron microscopy. We showed that the width of hexagonal pattern as well as the height of the mesh edges significantly varied depending on the maturation stage of the stomatocyst. An amended diagnosis of this stomatocyst is provided.

Assessment of cracking performance in edge restrained RC walls

AbstractExcessive cracking due to restraint of thermal and shrinkage strains is a widespread problem in the concrete construction industry. In design, restraint induced cracking is managed by the provision of reinforcement intended to distribute internal strains in such a way as to control the cracking pattern and limit crack widths. The area of secondary (horizontal) reinforcement required in members such as retaining walls and water tanks is often governed by the need to control early age thermal cracking. This paper presents results from four edge restrained walls tested at Imperial College London and the University of Leeds as part of an Engineering and Physical Sciences Research Council funded project into restraint induced cracking. The paper describes the development of volumetric strain and cracking in the tested walls. The cracking performance is assessed by comparing the restrained strain with the tensile strain capacity of concrete.

Laboratory Study of the Impact of the Surface Solitary Waves Created by the Internal Solitary Waves on Optical Imaging

AbstractThe effects of Surface Solitary Waves (SSWs), which are created by Internal Solitary Waves (ISWs), on optical imaging were investigated in this paper. We explored the connection between SSWs and optical images using simulations and experiments with calm water surface conditions. An experimental platform was built in a controlled laboratory environment where optical images and in‐situ wave data could be gathered simultaneously. SSWs created by different ISWs were successfully observed. The optical images revealed inverse bright and dark patterns for different ISW types (depression or elevation type). Based on theories and experimental results, simulation models of the ISWs and SSWs were built in Unigraphics NX. Using the illumination simulation function of Light Tools, the reason underlying the reversed patterns was explained by the irradiance distribution. Both the experiment and simulation indicated that the SSWs created by the ISWs affected the characteristics of optical images. To further explore how SSWs affect imaging, 16 experiments were designed to investigate the effects of ISW type, amplitude, and water density ratio. It is found that the relationship among the SSW amplitude, ISW amplitude, and density ratio was consistent with earlier studies. The relationships between imaging characteristics (grayscale differences and pattern widths) and the two types of SSWs were consistent.

Investigation into thermo-mechanical reliability of copper trace lines in stacked dies ball grid array packaging

The persistent trend toward device miniaturization in the semi-conductor field has led to an ever finer line width and spacing of the copper trace patterns in the organic substrate used to connect the chip and printed circuit board. Thus, copper trace fracture has emerged as a major concern during the manufacturing process or subsequent thermal cycle reliability testing stage. Accordingly, the present study develops a three-dimensional (3D) computational model to analyze the reliability of the copper trace lines in a stacked ball grid array (BGA) containing two dies under thermal cycling between −65 °C and 150 °C. The simulation model takes account of both the tensile mechanical strength of the copper trace and its creep behavior at elevated temperatures. The validity of the simulation model is confirmed by comparing the predicted distribution of the plastic work density (PWD) in the copper trace/substrate layer following thermal cycling with the experimental observation. In general, the results show that the maximum average PWD of the copper trace should not exceed 400 kJ/m3 in order to minimize the risk of trace fracture. Taguchi analysis experiments are performed to determine the optimal design of the stacked BGA package which minimizes the PWD and hence maximizes the fatigue life of the copper trace. The results indicate that the thermo-mechanical reliability of the stacked BGA package depends mainly on the choice of substrate core material and core trace thickness.

Flexural behaviour of geopolymer concrete beams reinforced with BFRP and GFRP polymer composites

The paper presents the experimental investigations on the flexural behaviour of geopolymer concrete beams reinforced with Basalt Fibre Reinforced Polymer (BFRP)/Glass Fibre Reinforced Polymer (GFRP) rebars and the effect of inclusion of the new adhesively bonded BFRP/GFRP stirrups. M30 grade geopolymer and conventional concrete beams with the dimension of 100 × 160 × 1700 mm were cast to investigae the flexural behaviour of BFRP/GFRP and steel bars. This study also examined the mode of failure, deflection behaviour, curvature moment capacity, crack width, pattern, propagation, strains and average crack width of the BFRP/GFRP bars with stirrups in the geopolymer concretes using a four-point static bending test. The results were compared to that of conventional steel-reinforced concrete, and it was found that the Basalt and Glass reinforced polymer beams demonstrated premature failure and sudden shear failure. Further, the FRP bars exhibited higher mid-span deflection, crack width and crack propagation than steel bars. Crack spacing of the FRP bars decreased with an increase in the number of cracks. The correlation between the load and the deflection behaviour of the beams was determined using statistical analysis of multi variables regression.

Icing Force on Line-Patterned Hydrophobic Surfaces

Observations of the frosting process on line-patterned hydrophobic surfaces have reported. The frost does not penetrate into the spaces, and it is believed that the frost adhesion can be reduced. Therefore, there is a possibility that this technology can be applied to prevent icing. However, the relationship between the line patterns and the ice adhesions of ice following freezing has not been studied. Therefore, in this study, the line patterns with the various space widths were fabricated on some silicon substrate surfaces, and the relationship between the change in hydrophobicity due to the line patterns and the icing force was investigated. As a result, it was found that the icing force decreases as the contact angle increases and does not change with the space widths of the line patterns.

Hierarchically Fabricated Amyloid Fibers via Evaporation-Induced Self-Assembly.

Multiscale hierarchical nano- and microstructures of amyloid fibrils are fabricated by evaporation-induced self-assembly combined with topographic surface patterning techniques. The continuous stick-and-slip motion induces uniaxial alignment of amyloid fibrils characterized by high orientational order during the drying process. The optical textures of the resultant amyloid aggregates are directly observed by polarized optical microscopy (POM) and atomic force microscopy (AFM). The resulting fiber structure can be tuned by varying the width of the topographic pattern, e.g., the microchannel width, inducing different separation between the deposited amyloid fibers on the glass substrate. Additionally, amyloid fibrils are decorated with gold nanoparticles to produce conductive microwires showing good conductivity (∼10-3 S/m). The finely controlled deposited amyloid fibers presented here can show a way to use naturally-abundant biomaterials for practical applications such as nanowires and sensors.

Relationship between blurring factors and interfacial effects in chemically amplified resist processes in photomask fabrication

Chemically amplified resists are an indispensable technology for photomask fabrication. The formation of latent images near interfaces in resist films is strongly affected by low-energy electron dynamics at the interfaces. On the other hand, the latent images are blurred by low-energy electron migration and acid diffusion in latent image formation. In this study, the relationship between blurring factors and interfacial effects was investigated by simulating the latent image formation on the basis of the sensitization and reaction mechanisms of chemically amplified electron beam resists. For low-energy electron dynamics, the interfacial effects on the protected unit distribution was reduced and the chemical gradient slightly increased with decreasing thermalization distance. For acid diffusion, the decrease in exposure pattern width significantly reduced the interfacial effects on the protected unit distribution in the depth direction because the acid diffusion length can be increased without sacrificing resolution.

Design of thin-structured-light projection system for small-height measurement.

A thin-structured light projection system with simple setup is proposed and applied to small-height measurement. In this system, the design of structured light pattern is carried out on the computer. The structure, color, geometric dimension, motion mode, projection brightness, contrast, and other attributes of the pattern can be edited easily. The optical system with zoom function is designed, which can output thin-structured-light fringe with a minimum width of 10μm. The camera and microscope are used to construct a vision system, which is used to capture the pattern of structured light. The three-dimensional (3D) shape reconstruction is realized by analyzing the pattern of structured light. The results show that this system can project a small width of thin-structured light pattern, which is very suitable for 3D shape reconstruction of microscopic objects with the small-height of tens of microns to hundreds of microns.

Odd Mathieu Functions Application to Synthesize a Multi-element Radiator Flat-topped Radiation Pattern

The paper studies synthesizing capabilities of a flat-topped radiation pattern when using the expansion of the target radiation pattern into a series in terms of odd Mathieu functions. As parameters for comparing the target and synthesized radiation patterns, we used a main-lobe width at a level of -1 dB and an irregularity of the top of the main-lobe of the radiation pattern. The sector-shaped radiation pattern has been synthesized for linear radiators of various lengths. The convergence of the coefficients of the Mathieu series in the synthesis of the sector-shaped radiation pattern has been estimated. It is shown that the use of piecewise-linear approximation of the target radiation pattern in the synthesis using a series expansion into odd Mathieu functions allows us to improve the quality of the radiation pattern formed.The task that involved finding the amplitude-phase distribution for a linear emitter with a length of 3λ, 4λ and 5λ (λ is operation wavelength) for a target radiation pattern was solved. The target amplitude distribution has the following electrical characteristics: the main-lobe width is 37.5° at a level of -1 dB and the side lobe level (SLL) is -20 dB. The synthesis procedure was performed for two cases. In the first case, the target radiation pattern is represented by a piecewise constant function with a given width. In the second case, the target pattern was specified using piecewise linear approximation of the top and slopes of the main lobe.Comparison of the radiation patterns obtained shows that in the first case, the main-lobe width of the radiation pattern at a level of -1 dB is 34°, the SLL varies from -15.6 to -17 dB, and the irregularity of the main-lobe top of the radiation pattern lies within 0.9 ... 1.2 dB. In the second case, the main-lobe width of the antenna radiation pattern at a level of -1 dB is 36.5°, the SLL is -17.5 dB, and the irregularity of the main-lobe top is 0.4 dB at most. When used, the considered under consideration enables us to obtain both the synthesized patterns for linear radiators of various lengths, and the corresponding amplitude-phase distributions and coefficients of the Mathieu series. An estimate of the convergence of the Mathieu series shows that the use of linear approximation of the target radiation pattern in some cases allows up to 2.7-fold increase in acceleration of the convergence of the Mathieu series. The accuracy of reproducing the sector-shaped pattern by the synthesis method using the expansion into odd Mathieu functions gives good results when synthesizing the amplitude-phase distribution for the linear radiators with an electric length of 5λ or more.

Laser Illumination Adjustments for Signal-to-Noise Ratio and Spatial Resolution Enhancement in Static 2D Chemical Images of NbOx/IGZO/ITO/Glass Light-Addressable Potentiometric Sensors

In a previous study, a thin In-Ga-Zn-oxide light addressable potentiometric sensor (IGZO LAPS) was indicated to have the advantages of low interference from ambient light, a high photocurrent and transfer efficiency, and a low cost. However, illumination optimization to obtain two-dimensional (2D) chemical images with better spatial resolutions has not been fully investigated. The trigger current and AC-modulated frequency of a 405-nm laser used to illuminate the fabricated IGZO LAPS were modified to check the photocurrent of the sensing area and SU8–2005 masking area, obtaining spatial resolution-related functions for the first time. The trigger current of illumination was adjusted from 0.020 to 0.030 A to compromise between an acceptable photocurrent and the integrity of the SU8–2005 masking layer. The photocurrent (PC) and differential photocurrent (DPC) versus scanning length (SL) controlled by an X-Y stage were used to check the resolved critical dimensions (CDs). The difference between resolved CD and optically measured CD (e.g., delta CD) measured at an AC frequency of 500 Hz revealed overall smaller values, supporting precise measurement in 2D imaging. The signal-to-noise ratio (SNR) has an optimized range of 2.0 to 2.15 for a better resolution for step spacings of both 10 and 2 μm in the scanning procedure to construct static 2D images. Under illumination conditions with a trigger current of 0.025 A and at an AC frequency of 500 Hz, the spatial resolution can be reduced to 10 μm from the pattern width of 6 μm. This developed methodology provides a quantitative evaluation with further optimization in spatial resolution without an extra cost for applications requiring a high spatial resolution, such as single-cell activity.

반구형 커버리지를 갖는 저궤도 위성 TC&R용 원편파 도파관 안테나

In this study, we suggested a waveguide antenna for low-orbit satellite TC&R with hemispherical coverage in the X-band of 7.0~8.5 GHz required for the telemetry command system (Telemetry, Command, Ranging, hereinafter TC&R) for communication between the satellite and the ground station. The proposed antenna is designed using a septum structure inside the waveguide to generate a circularly polarized wave and expand the axial bandwidth. In addition, to extend the beam width of the radiation pattern within the range of maintaining the circularly polarized wave, an outer wall of a corrugated structure was added and offset at the end of the opening of the spherical waveguide. Consequently, the hemispherical coverage characteristics were satisfied, and an axial ratio of around 10 dB was obtained at ±90°. In addition, the average gain of all angles within the beam width at the resonant frequency was −2.9 dBi. Accordingly, sufficient beam width, axial ratio, and gain were secured as antennas for low-orbit satellite TC&R.

Determination of the bottom scattering coefficient discontinuity lines in the multibeam ocean sounding

In this paper the problems of constructing sonar images of the seabed according to measurements of the multibeam side scan sonar are considered. The inverse problem for the non-stationary equation of radiation transfer with the diffuse reflection conditions at the boundary which consists in finding the discontinuity lines of the bottom scattering coefficient is investigated. A numerical algorithm for solving the inverse problem is developed, and an analysis of the quality of reconstructing the boundaries of inhomogeneities of the seabed is carried out, depending on the number of views and the width of a radiation pattern and the sounding range.

Characterisation of Finger Dermatoglyphics Traits and other Biometric Indices among Health Science Undergraduates of the Osun State University, Nigeria

Background: Finger dermatoglyphics has been useful in diagnosing genetically related diseases and detecting crimes. A cross-sectional study was carried out to establish the relationship between fingerprint traits and biometric indices Methods: Finger dermatoglyphics data were obtained using the ink method among the Health Sciences Students of Osun State University, Osogbo, Nigeria. Finger pattern intensity, finger pattern distribution, and finger ridge counts were measured and compared. These were done by counting and classifying ridge patterns and pattern configuration of arches, loops, and whorls and counting their ridge densities. The subject’s height, weight, and colour of the pupil were measured and recorded, respectively Results: The ulnar loops and arches were the most predominant finger patter ns in females, while males showed significantly spiral whorls. The sex differences between these patterns were not statistically significant (P>0.05). Subjects with brown pupils demonstrated higher ulnar loop and elliptical whorl, while those with black pupils possessed significantly well-distributed arches, and were insignificant in pattern width and intensity. Body Mass Index (BMI) polymorphism showed the lowest pattern size (Finger Ridge Counts) demonstrated by significantly reduced total finger ridge count among the subjects with BMI range of 24-26 and predominance of the concentric whorl, radial loop, and arches. However, higher pattern size was observed in subjects with a higher BMI value 27-29 BMI range with corresponding ulanr and spiral whorl respectively. Conclusion: This study demonstrated the prevalent biometrics measure of finger dermatoglyphics traits, in relations to the biometrics distribution of pupillary colour and body mass index among the Health Sciences Students of Osun State University, Osogbo Nigeria

Simulation of microstrip radio altimeter antenna for aircraft

The purpose of the article is to carry out mathematical modeling of the main characteristics and parameters of a microstrip antenna, the dielectric substrate of which is created from a domestic ceramic sample and to substantiate the use of a microstrip antenna as a transmitting and receiving antenna in a radio altimeter. It is shown that a microstrip antenna on a ceramic material substrate with a relative permittivity ε = 9.6 and a thickness of 0.2 mm has good electrical parameters in the frequency range of 31.5–33.5 GHz. Including the width of the antenna radiation pattern at the level of –3 dB is 12.5 degrees in the horizontal plane and 26.7 degrees in the vertical plane. In this case, the antenna gain is 17 dB and the level of the first side lobe is –20 dB relative to the main antenna lobe. Also the practical application of microstrip array antennas inphase as a transmitting and receiving antenna for a radio altimeter installed on aircraft is described in the article. The range of the altimeter reaches 300 m.

Optimization and Analysis of Multilayer Planar Spiral Coils for the Application of Magnetic Resonance Wireless Power Transfer to Wearable Devices

In this study, small multilayer planar spiral coils were analyzed and optimized to wirelessly charge an in-ear wearable bio-signal monitoring device in a wine-glass-shaped transmitter (Tx) based on magnetic resonance wireless power transfer (MR-WPT). For analysis of these coils, a volume filament model (VFM) was used, and an equivalent circuit formulation for the VFM was proposed. The proposed method was applied to design effective multilayer coils with a diameter and height of 6 and 3.8 mm, respectively, in the wearable device. For the coils, a printed circuit board having a 0.6 mm thick dielectric substrate and a 2 oz thick copper metal was used. Moreover, the coils on each layer were connected in series. The dimensions of the double-, four-, and eight-layer coils were optimized for the maximum quality factor (Q-factor) and coupling efficiency. The operating frequency was 6.78 MHz. The optimal dimensions for the maximum Q-factor varied depending on the number of coil layers, pattern width, and turn number. For verification, the designed coils were fabricated and measured. For the four-layer coil, the coupling efficiency and Q-factor using the measured resistance and mutual inductance were 58.1% and 32.19, respectively. Calculations showed that the maximum Q-factor for the four-layer coil was 40.8 and the maximum coupling efficiency was 60.1%. The calculations and measurement were in good agreement. Finally, the entire system of the in-ear wearable bio-signal monitoring device, comprising a wine-glass-shaped transmitter, the designed receiving coil, and a monitoring circuit, was fabricated. The measured dc-dc efficiency of the MR-WPT system was 16.08%.