Single Square Research Articles

Nanolayer Laser Absorber for Femtoliter Chemistry in Polymer Reactors (Adv. Mater. 8/2022)

Polymer Laser Printing In article number 2108493, Junfang Zhang, Felix Loeffler, and co-workers describe how a facile iron oxide nanofilm synthesis revolutionizes polymer laser printing. Fast and precise laser transfer of polymer spots enables over 100 000 individual chemical reactions to be run in parallel in a single square centimeter. Rapid chemical reaction screenings, such as amide bond formation, click chemistry, or photochemistry, are now possible in the microarray format.

Automatic and continuous separation of mixed waste plastics via magneto-Archimedes levitation

High efficiency separation is a significant process of the mechanical recycling to manage the mixed waste plastics. However, most of the extant methods can only deal with binary mixtures. In this paper, a novel automatic and continuous separation method based on magneto-Archimedes levitation is proposed to handle multi-plastics. A theoretical model on how the object is levitated above a single square magnet with the aid of paramagnetic media is established. The model revealed that object with different densities would be levitated at different heights. Lighter object would be levitated rapidly to a certain height and then be pushed away slowly. Thereby, the separated plastics could be collected automatically and the continuous separation of the mixtures can be addressed. The separation of polyurethane (PU), polyamide (PA6), and polytetrafluoroethylene (PTFE) demonstrated that the method can deal with multiple plastics with purities over 96.2%. Combined with additional advantages of low cost and no energy consumed in separation process, the method has the potential to be industrialized into an economically-viable and environmentally-friendly mass production procedure.

A Beam-Split Metasurface Antenna for 5G Applications

This article presents a hybrid metasurface split beam antenna for fifth-generation (5G) mobile applications at 3.5 GHz. Multi-beam antennas with high directivity are required for a 5G mobile network. It can be achieved by having an array antenna. Using an antenna array at low frequency increases the complexity and size of the whole network. Therefore, a metasurface (MS) is proposed to direct surface current and to have high gain and multibeam properties. To achieve that, a square split ring resonator (SSRR) and U-shaped unit cell metasurface is implemented as a superstrate to a single square patch antenna. The manipulation of this hybrid metasurface configuration can create opposite current flow on the unit cell and thus split the beam. The hybrid metasurface superstrate and antenna are fabricated on FR-4 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon \text{r}\,\,=4.4$ </tex-math></inline-formula> , tan <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta =0.02$ </tex-math></inline-formula> ). Results show that the antenna resonates well at 3.5 GHz, with a less than −10 dB reflection coefficient. The arrangement of the unit cells on the superstrate metasurface is able to split the current, and thus the radiation pattern beam is split into two beams in the E-plane at ± 45°. This antenna is a good candidate for future 5G Pico cell base stations in urban or suburban areas with high capacity and interferences.

Impact of Amplitude and Phase Imbalance on Dual Differential Fed Patch Antenna With High Isolation

In this paper, the impact of amplitude and phase imbalance on a proposed dual differential fed patch antenna is analyzed in the context of system effective reflection coefficient and axial ratio (AR). A single square patch with four ports is used as a solo radiating element and provides absolute symmetry at radiating. An in-depth analysis will be presented to understand the impact of external RF chain components on the performance of the proposed antenna. When fully differential excitations and perfect symmetry can be achieved, all six polarization states exhibit identical system effective reflection coefficients with close to ideal AR for CP. When phase imbalance and amplitude imbalance only exist in between the two differential pairs, the antenna system matching performance is found to be unchanged. In the presence of the feed network, circular polarization (CP) achieves a measured maximum AR of 0.49dB along the antenna pointing angle, while linear polarization (LP) has a measured maximum cross polarization of −30dB. This work monitors the beamwidth over which the AR can be kept below 1dB (BW-AR−1dB). Based on the optimization of phase imbalance, a novel BW-AR−1dB enhancement technique is introduced. Compared to the case with better AR at the main beam location, an improvement of 14. beamwidth is measured without significant degradation of AR. Isolation better than 40dB across an operating frequency of 9.27 – 9.4 GHz has been experimentally demonstrated for the proposed dual differential fed technique. The resulting antenna is compact and low profile which is an appealing candidate for phased array applications.

Parallel-motion-type eddy current damper model of rectangular magnet and conductor

Eddy currents in a conductor moving in a non-uniform magnetic field in a static coordinate system are expressed as the superposition of the term by the partial derivative of the magnetic vector potential with respect to time and by the gradient of scalar potential in a stationary-conductor coordinate system. In this study, we proposed the general equation of “gradient of scalar potential is zero” condition (GSPZ condition) throughout the conductor. Additionally, under satisfying the GSPZ condition, we propose the method of obtaining the magnetic damping force from both the magnetic flux densities and the eddy currents calculated using the Biot-Savart law and Fleming's left-hand rule for the parallel-motion-type eddy current damper (GSPZ-A method). The precision of the GSPZ-A method is similar to that of the three-dimensional finite element method (3D-FEM); however, the effect of the secondary magnetic field was not considered. In this study, the GSPZ condition for the parallel-motion-type eddy current damper of a rectangular magnet and conductor of arbitrary dimensions was established. Furthermore, the GSPZ condition was applied to two types of eddy current dampers—one composed of the single square magnet and the other of the combined square magnet with oppositely aligned magnetic poles. The magnetic damping forces calculated using the GSPZ-A method were compared with those obtained from the 3D-FEM and experiments. As a result, the errors from the GSPZ-A method to 3D-FEM for the single and combined magnets were 10 and 0.4 %, respectively.

The Effect of the Gap Ratio on the Flow and Heat Transfer over a Bluff Body in Near-Wall Conditions

In order to study the effect of different gap ratios on the thermofluid-dynamic field around a bluff body located in proximity to a heated wall, a series of experiments and numerical simulations have been conducted. The former were carried out using an open circulating water tank experimental platform and a single cylinder and square column as geometrical models (their characteristic length being D). The latter were based on the well-known SIMPLE algorithm for incompressible flow. The results show that the gap ratio is an important factor affecting the wake characteristics of near-wall bluff bodies. When the gap ratio is small, the influence of the wall on the bluff body wake is large. With an increase in the gap extension, periodic vortex shedding is enabled and heat transfer is strengthened accordingly; in addition, the vortex shedding period is larger for the square column. The square column displays hysteresis compared with the cylinder at the same gap ratio (the critical gap ratio of cylinder is 0.2∼0.4, while that of square column is 0.4∼0.6).

Low-Profile Wideband Four-Corner-Fed Square Patch Antenna for 5G MIMO Mobile Antenna Application

A low-profile wideband four-corner-fed square patch antenna for fifth-generation (5G) multiple-input–multiple-output (MIMO) mobile antenna application is presented. The proposed antenna uses a single square patch to generate four uncorrelated waves over a wide band to cover 3.3–4.2 GHz (5G N77 band) with a low profile of 2.4 mm (0.03 λ at 3.75 GHz). Wideband operation is obtained by generating the half-patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode and the quarter-patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2,1/2</sub> mode for each port. The half-patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode is created by embedding two diagonal linear slots in the square patch. By further placing shorting pins along the patch's two centerlines, a square two-edge-shorted quarter-patch for each port to support the quarter-patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2,1/2</sub> mode is created, which combines with the half-patch TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode to form a wide operating band. Details of the proposed antenna including the experimental results are presented.

Mechanical properties of wire and arc additive manufactured component deposited by a CNC controlled GMAW

Wire and arc Additive Manufacturing (WAAM) is gaining a lot of popularity in industries due to its ability to produce metallic components with a high deposition rate compared to other Additive Manufacturing (AM) processes. Moreover, there is no material wastage in the form of scrap as in the conventional subtractive manufacturing process. In this study, deposition of layers is done using a Computer numerical controlled Gas Metal Arc Welding (CNC GMAW) based WAAM setup. ER70S-6 low carbon-alloy mild steel wire is chosen as filler wire. A single square bead and a square-shaped component of 9 layers are fabricated on a substrate A36 steel. Deposition on the preheated and normal substrate is considered for analyzing the control of dimensional stability of bead height and bead humping phenomenon. Coordinate Measuring Machine (CMM) results shown that bead deposited on a preheated substrate has more dimensional stability and reduced humping. The hardness and wear test of the fabricated components were also carried out. The result revealed that hardness increases to some extent from149 to 159 BHN in the built direction (vertical). The average hardness is somewhat greater than that produced by conventional methods. The wear test was carried out at two different loading conditions of 1 kg and 2 kg, the wear rate calculated shows that the wear is lower in the case of the WAAM fabricated component compared to other traditional manufacturing methods. Results also revealed that the rate of wear gets lowered when the load is increased.

A Numerical Investigation of Turbulent Flow Over Single and Tandem Square Cylinders

This paper presents the three-dimensional flow investigations over the square cylinders placed in the tandem arrangement. Two different flow configurations were investigated in detail; one comprising of a single square cylinder and the other comprising of three square cylinders placed in a tandem arrangement with the spacing of six times the width (w) of each square cylinder. The Reynolds number based on the width of the square cylinder (w) and free stream velocity (Uo) is 22,000. The problem was solved numerically using an Unsteady Reynolds-Averaged Navier-Stokes (URANS) based model and Large Eddy Simulation (LES) based model. Strouhal Number, lift, and drag coefficients were computed for each configuration. By comparing both the models using contour plots of pressure, velocity and vorticity it is found that the LES model is more accurate to capture the turbulence around single and tandem square cylinders. In the tandem arrangement, complex periodic vortex shedding was observed in the wake of each square cylinder. The production of turbulent kinetic energy was also investigated to understand the roles of stresses during flow over the cylinders. The analysis showed that the production of turbulence by normal stresses is higher than that of shear stresses. Furthermore, it was observed that the flow over the first cylinder arranged in tandem is quite identical to that of the single square cylinder. Moreover, the upstream cylinder experienced a higher lift in comparison to the downstream cylinders.

Fatigue life prediction of structural steel using acoustic birefringence and characteristics of persistent slip bands

AbstractNondestructive evaluation methods provide additional information about the material fatigue behavior and enhance the comprehension of damage evolution thanks to relationship between microstructure and physical properties. This paper deals with optical and ultrasonic investigations of structural steel specimens tested for low‐cycle fatigue. The development of persistent slip bands observed on the surface with an optical microscope was quantified using a previously trained neural network and fractal analysis. A surface damage parameter was defined as the ratio of total area of detected slip bands to the area of observed surface. Relationships between the rate of change and critical value of the damage parameter, the strain range, and the fatigue life were established. A single square relationship between relative number of cycles and ratio of the surface damage parameter to its critical value was obtained. Acoustic birefringence was measured by the echo method. The effect of the strain range on the rate of change in acoustic birefringence was investigated. A single linear relationship between relative number of cycles and change in acoustic birefringence was established. An algorithm for predicting the material remaining life, combining optical and ultrasonic data, was proposed.

A Dual-Band Polarization Insensitive Metamaterial Absorber with a Single Square Metallic Patch for Sensing Application

A Dual-Band Polarization Insensitive Metamaterial Absorber with a Single Square Metallic Patch for Sensing Application

Lattice Boltzmann analysis of fluid structure interaction mechanism around a row of five side-by-side square cylinders

In this paper numerical investigations are performed to examine the effect of Reynolds numbers (Re) and spacing ratios (g) on flow around a row of five side-by-side square cylinders using the lattice Boltzmann method. The Reynolds number is varied in the range 75 ≤ Re ≤ 175, while spacing ratio is varied between 0.5 and 5. The flow structure mechanism around a row of five side-by-side square cylinders is studied in terms of vorticity contours visualization, time trace analysis of drag and lifts coefficients, and power spectrum analysis of lift coefficient. The effect of Re on force statistics like mean drag coefficient and Strouhal number is also analyzed. The present data are compared with the data of single square cylinder and good agreement is observed for large spacing ratio (g = 5). The flow behind five side-by-side square cylinders is classified into three different flow regimes and these regimes are further subdivided into seven different regimes. The observed flow regimes are compared with those of the other researchers published studies and found good agreement.

Impact of region-of-interest size and location on quantitative contrast-enhanced ultrasound of canine splenic perfusion

BackgroundDuring contrast enhanced ultrasound (CEUS), the features of the regions of interest (ROI) can affect the value of the perfusion-related parameters obtained from a time intensity curve (TIC). In veterinary medicine, conflicting have been reported on the influence of ROI size and location on renal CEUS. There are some disagreeing evidences regarding the optimal method for selecting ROI in quantitative analysis of renal perfusion using CEUS.The aim of this study was to evaluate the effect of the size and location of ROIs in the spleen of conscious dogs on perfusion variables determined using sulphur hexafluoride contrast-enhanced ultrasounds.ResultsA prospective observational study on 15 client-owned mixed-breed adult dogs was performed using a system equipped with contrast-tuned imaging technology. Qualitative and quantitative assessments of the spleen enhancement pattern were carried out. Three square ROIs (0.05 cm2) were manually drawn in a row and spaced 1 mm apart, placing adjacent ROIs at three different depths. Three medium rectangular ROIs (0.3 cm2) include the 3 smallest ROIs in each row, indicated by the letters A, B and C, and a single large square ROI (1 cm2) was drawn containing all previous ROIs. Software analysis of time-intensity curves generated within each ROI allowed us to calculate the perfusion-related parameters: peak enhancement, time to peak, regional blood flow, mean transit time and regional blood volume.The coefficient of variation for all blood-related parameters was always lower in the larger ROI than in the other smaller ROIs. ROI A and B, positioned proximally and medially, levels respectively, showed similar coefficients of variation to the largest ROI. The analysis of variance model exhibited a significant effect of location and size of the ROIs in the quantitative analysis of canine spleen perfusion, with a reduction of perfusion-related parameters in the distal ROI.ConclusionsThe recommendation for a quantitative CEUS examination of a dog’s spleen is to analyze splenic perfusion by drawing a sufficiently large ROI proximal to the ultrasound beam on the splenic parenchyma. This may be of clinical relevance in the diagnosis of splenic diseases.

Lattice Boltzmann study of low-Reynolds-number flow past square cylinders with varying slip distributions

Slip distributions have been proved to have significant influence on the flow-past-cylinder problems. However, rare studies focus on the square cylinders. To obtain better understanding of the effect of slip distributions on the flow-past-square-cylinder problems that widely appear in the engineering fields, the flows past a single square cylinder, and two tandem square cylinders under different slip distributions and gap ratios are numerically investigated using the lattice Boltzmann method at low-Reynolds-numbers (25∼200, mainly at 100). The flow structures and drag properties (including the friction drag and the pressure drag) are analyzed. Various slip distributions are found to have minor impacts on the drag reduction of a single cylinder (3.5% in maximum) but larger impacts on that of the tandem cylinders, especially the downstream cylinder (100% in maximum). In addition, flank side slip is found to have important contributions to the drag reduction.

Dynamics and Traffic for Transfecting Exogenous MicroRNA as Studied by Live-Cell Microscopy.

MicroRNA (miRNA) has emerged as an important gene-regulator that shows great potential in gene therapy because of its unique roles in gene-regulation. However, the knowledge on their function and transportation in vivo is still lacking, and there are limited obvious evidences to define intracellular transportation of miRNA. In this study, the dynamics of exogenous miR-21 transfected into HeLa cells was traced by live-cell microscopy. Their transportation at key time points was recorded and dynamic properties were analyzed by single particle tracking (SPT) and mean square displacement (MSD) calculation. Results showed that the exogenous miRNAs bounded to cells quickly and went through lysosome into cytosol, where they were subsequently recruited into p-body. They finally were degraded, otherwise went back to cytosol in some way. Long time observation and analysis of motion mode showed that the miRNAs were confined in a small region and their motion modes were flexible in different intracellular microenvironment after entering the cells.

Modified Hexagonal Split Ring Resonator Based on an Epsilon-Negative Metamaterial for Triple-Band Satellite Communication.

A triple-band epsilon-negative (ENG) metamaterial based on a split ring resonator (SSR) with a modified hexagonal-shaped metal strip proposed in this study is a new combination of a single slit square resonator and a modified hexagonal-shaped metal strip. The desired unit cell FR-4 (lossy) that was selected as the substrate was 1.6 mm thick. Following the assessment of the unit cell, a high-frequency electromagnetic simulator like the computer simulation technology (CST) microwave studio was applied to assess the S-parameters. The proposed design exhibited resonance at 2.89, 9.42, and 15.16 GHz. The unit cell also demonstrated negative permittivity in the frequency ranges 2.912–3.728 GHz, 9.552–10.144 GHz, and 15.216–17.328 GHz, along with a negative refractive index. An effective medium ratio (EMR) of 11.53 is an indicator of the goodness of the metamaterial unit cell. It is deliberate at the lowermost resonance frequency of 2.89 GHz. Moreover, the simulated results that were validated using HFSS and equivalent circuit model indicated slight variations. The proposed design was finalised based on several parametric studies, including design optimisation, different unit cell sizes, various substrate materials, and different electromagnetic (EM) field propagations. The proposed triple band (S, X, and Ku bands) negative permittivity metamaterial unit cell can be utilised for various wireless applications, such as microwave communication, satellite communication, and long-distance radio communication.

The Curvature Effect on the Diffusion of Single Brownian Squares on a Cylindrical Surface in the Presence of Depletion Attractions.

The diffusion of single micron-sized Brownian square platelets on cylindrical surfaces with different radii of curvature in the presence of depletion attractions was studied experimentally by video microscopy. The translational motion of a square is found to be diffusive along the axial direction of the cylinder but sub-diffusive along the circumferential direction due to the confinement induced by gravity, while its rotational motion displays a sub-diffusive behavior due to the confinement induced by orientation-dependent depletion attractions. Such a confinement effect decreases as the radius of curvature increases and can be tuned both through surface curvatures and/or depletion attractions. Our work provides a new way to control the translational and rotational dynamics of anisotropic particles through curved surfaces in the presence of depletion attractions.

Geometric shaping optimization of 64-APSK constellation in discrete nonlinear frequency division multiplexing systems.

We experimentally demonstrated a geometric shaped (GS) 64-ary amplitude phase shift keying (64-APSK) eigenvalue transmission. The signal is modulated on the scatter coefficient of a single eigenvalue and linear minimum mean square error (LMMSE) estimator is used to reduce the noise. The channel response is estimated by transmitting a normally distributed 64-APSK constellation through a communication link. Based on the polar coordinates distribution of the received constellation, the diameter distributions for each circle can be obtained so that circles with larger noise can obtain larger judgment width. After optimization, the experimental results show that the Q-factor gain is 1.13 dB under 22 dB received optical signal to noise ratio (OSNR) configuration and 0.88 dB after 900 km transmission compared with normally distributed APSK configuration.

Numerical study of fixed ended Lean duplex stainless steel (LDSS) flat oval hollow stub column with square perforation under pure axial compression

This paper presents the parametric study of single square perforated fixed ended LDSS (Lean Duplex Stainless Steel) flat oval section stub columns, by varying the square perforation size, location of perforation along transversely as well as longitudinally, using the Finite element software Abaqus (2009). Based on the Finite element study, a near-linear reduction in ultimate load capacity with perforation size has been observed. The reduction is found to be higher for the stockier cross-sections as compared to slender sections. The percentage drop in ultimate load capacity remains relatively unaffected for larger perforation when the section is slender and located at the flat element. It is seen that, in comparison to the slender section, perforated stocky sections showed a mild drop in ultimate load as the perforation is located toward the corner junction of flat and curve portion from the mid-flat region. Further, in general, it is observed that the reduction in load capacity to be highest when the perforation is located near the mid-height. A design approach based on modified ASDM (Automotive Steel Design Manual) has been proposed to estimate the design capacity of single square perforated flat oval LDSS hollow columns

Numerical investigation of the effect of laser shock peening parameters on the residual stress and deformation response of 7075 aluminum alloy

Massive laser shot peening (LSP) is a promising surface modification technology to improve the properties of metallic materials. In this work, with the established FEM model, the dynamic propagation characteristics of stress waves by single round and square impact were investigated. The effect of three critical LSP parameters such as scanning patterns, overlapping rates and spot shape on the residual stress and the displacement deformation (U3) of 7075 aluminum alloy were further investigated under same spatial energy input. The simulation results were compared and validated with the reported research results. The spot shape has little effect on the residual stress field after a single impact while a better LSP treatment could be achieved by the massive square spot impact strategy. The snake scanning pattern was proved to be an optimized advancing pulse sequence compared with other two scanning patterns. The uniformity of compressive residual stress field and the displacement deformation (U3) curve were improved with the increase of overlapping rate.