Small Size Scale Research Articles

A new small-sized Calotes Cuvier (Squamata: Agamidae: Draconinae) from the Subansiri river basin, Arunachal Pradesh, India.

We describe a new species of small-sized Calotes from mid-elevation (~1270 m asl.), swidden or shifting cultivation areas in the Subansiri river basin, Upper Subansiri District, Arunachal Pradesh, India. Mitochondrial sequence data (ND2) recovers Calotes sinyik sp. nov. as the closely related sister taxon to an unnamed species from Medog, Tibet; the two falling in a broader clade including C. paulus + C. zolaiking and species of the C. emma and C. mystaceus groups. The new species is 7.8% divergent in ND2 sequence data from the unnamed lineage from Medog and deeply divergent (≥ 21.6-28.1%) from other congeners. The new species can easily be distinguished from regional congeners by its small adult body size (maximum snout to vent length of 65 mm) and heterogenous dorsal scales, and from its closest relatives C. paulus and C. zolaiking by having 54 or 55 midbody scale rows and 42 or 43 vertebral scales. It is likely that many more allied species remain to be discovered from Northeast India, which remains poorly surveyed across taxonomic groups.

Electrochemical additive manufacturing of interdigitated structures using a multi-anode system with independently-controlled anodes

Interdigitated parts are used across a multitude of engineering applications. The overlapping, intertwined structures pose a challenge for fabrication using conventional additive manufacturing techniques, especially at small size scales. Electrochemical additive manufacturing (ECAM) has been shown to successfully create overhanging parts at the small scale without reliance on support structures. This study extends the ECAM capabilities into demonstration of the fabrication of interdigitated parts by the use of a multi-anode electrochemical additive manufacturing system. The ECAM process is operated by a tool head consisting of multiple anodes independently controlled by individual channels on an in-house-built multipotentiostatic system. Each anode is independently switched into active (anodic) or inactive (open-circuit) mode using a predefined, coded pattern controlling the custom electronics. While each tool is in anodic mode, its current contribution into the overall deposition process is tracked independently as well. Each independent tool can deposit material extending from regions deposited by itself or neighboring tools. The entire multi-head tool is controllably moved by a 3-axis translation system. An interdigitated comb geometry relevant to practical engineering applications is fabricated using this system. This geometry is built using a parallelized voxel-by-voxel tool path with characteristic electrode activation patterns at each position of the tool head. It was found that a purely closed-loop control with no time limit yielded a qualitatively better geometry than a control system with a 10-minute time limit applied. This study overall demonstrates the working principle of a multi-anode system and its ability to fabricate parts interdigitated structures. This study therefore advances the capabilities of ECAM as a valuable additive manufacturing process that can fabricate a variety of challenging parts for relevant engineering applications.

Analysis of reflection of wave propagation in magneto-thermoelastic nonlocal micropolar orthotropic medium at impedance boundary

PurposeThis study aims to examine the plane wave reflection problem in micropolar orthotropic magneto-thermoelastic half space, considering the influence of impedance as a boundary in a nonlocal elasticity.Design/methodology/approachThis study presents the novel formulation of governing partial differential equations for micropolar orthotropic medium with impact of nonlocal thermo-elasticity under magnetic field.FindingsThis study provides the numerical results validation for a particular numerical data and expression for the amplitude ratios of reflected waves and identifies the existence of four different waves, namely, quasi longitudinal displacement qCLD-wave, quasi thermal wave qCT-wave, quasi transverse displacement qCTD-wave and quasi-transverse micro-rotational qCTM-wave. The study derives the velocity equation giving the speed and phase velocity of these waves. The study also shows that the small-scale size effect gives significant impact on phase velocity.Research limitations/implicationsThe graphical analysis examines the variation of speeds and coefficients of attenuation of these waves due to frequency, magnetic field and nonlocal parameters. Also, significant conclusions on the variation of reflection coefficient against nonlocal parameter, frequency, impedance parameter and angle of incidence are provided graphically.Practical implicationsThe creation of more effective micropolar orthotropic anisotropic materials which are very useful in the daily life and their applications in earth science are greatly impacted by the findings of this study.Originality/valueThe authors of the submitted document initiated and produced it collectively, with equal contributions from all members.

A Lightweight Pine Wilt Disease Detection Method Based on Vision Transformer-Enhanced YOLO

Pine wilt disease (PWD) is a forest disease characterized by rapid spread and extremely high lethality, posing a serious threat to the ecological security of China’s forests and causing significant economic losses in forestry. Given the extensive forestry area, limited personnel for inspection and monitoring, and high costs, utilizing UAV-based remote sensing monitoring for diseased trees represents an effective approach for controlling the spread of PWD. However, due to the small target size and uneven scale of pine wilt disease, as well as the limitations of real-time detection by drones, traditional disease tree detection algorithms based on RGB remote sensing images do not achieve an optimal balance among accuracy, detection speed, and model complexity due to real-time detection limitations. Consequently, this paper proposes Light-ViTeYOLO, a lightweight pine wilt disease detection method based on Vision Transformer-enhanced YOLO (You Only Look Once). A novel lightweight multi-scale attention module is introduced to construct an EfficientViT feature extraction network for global receptive field and multi-scale learning. A novel neck network, CACSNet(Content-Aware Cross-Scale bidirectional fusion neck network), is designed to enhance the detection of diseased trees at single granularity, and the loss function is optimized to improve localization accuracy. The algorithm effectively reduces the number of parameters and giga floating-point operations per second (GFLOPs) of the detection model while enhancing overall detection performance. Experimental results demonstrate that compared with other baseline algorithms, Light-ViTeYOLO proposed in this paper has the least parameter and computational complexity among related algorithms, with 3.89 MFLOPs and 7.4 GFLOPs, respectively. The FPS rate is 57.9 (frames/s), which is better than the original YOLOv5. Meanwhile, its mAP@0.5:0.95 is the best among the baseline algorithms, and the recall and mAP@0.5 slightly decrease. Our Light-ViTeYOLO is the first lightweight method specifically designed for detecting pine wilt disease. It not only meets the requirements for real-time detection of pine wilt disease outbreaks but also provides strong technical support for automated forestry work.

Design and offline tests of a resonant stripline cavity kicker for longitudinal feedback in the HEPS Booster

Resonant stripline cavity kicker was first proposed by Spring-8 as a highly efficient longitudinal feedback kicker, since the shunt impedance per length of this type of kicker is higher than that of the widely-used waveguide-loaded cavity kicker. This paper presents the design of a resonant stripline cavity kicker for the HEPS Booster with a smaller beampipe compared to Spring-8. Based on the time domain measurements and the particle-in-cell simulation results, the designed kicker with a length of 402 mm is expected to achieve a peak shunt impedance of 4140 Ω and a minimum shunt impedance of 2700 Ω within the bandwidth from 1.5 GHz to 1.75 GHz, demonstrating itself a higher efficiency over the waveguide-loaded cavity kicker. Besides, the analyzed coupling beam impedance of this kicker indicates it not a source of beam instability. All these results suggest the resonant stripline cavity kicker an ideal choice to simultaneously fulfill feedback requirements and save installation space even on a smaller size scale.

Elastostatics of nonuniform miniaturized beams: Explicit solutions through a nonlocal transfer matrix formulation

A mathematically well-posed nonlocal model is formulated based on the variational approach and the transfer matrix method to investigate the size-dependent elastostatics of nonuniform miniaturized beams. The beams are composed of an arbitrary number of sub-beams with diverse material and geometrical properties, as well as small-scale size dependency. The model adopts a stress-driven nonlocal approach, a well-established framework in the Engineering Science community. The curvature of a sub-beam is defined through an integral convolution, considering the bending moments across all cross-sections of the sub-beam and a kernel function. The governing equations are solved and the deflections are derived in terms of some constants. The formulation uses local and interfacial transfer matrices, incorporating continuity conditions at cross-sections where sub-beams are joined, to define relations between constants in the solution of a generic sub-beam and those of the first sub-beam at the left end. The boundary conditions are then imposed to derive an explicit, closed-form solution for the deflection. The solution significantly simplifies the study of nonuniform beams with multiple sub-beams. The predictions of the model for two limiting cases, namely local nonuniform and nonlocal uniform beams, are in excellent agreement with the available literature data. The flexural behavior of nonuniform miniaturized beams, composed of two to five different sub-beams and subjected to different boundary conditions, is studied. The results are presented and discussed, emphasizing the effects of the material properties, nonlocalities, and lengths of the sub-beams on the deflection. It is demonstrated that the flexural response of nonlocal nonuniform beams is more complex than local counterparts. Unlike the local beams, dividing a nonlocal uniform beam into multiple sub-beams and then reconnecting them changes the overall stiffness of the beam. The study highlights the potential to design nonuniform miniaturized beams with specific configurations to control their flexural response effectively.

Plane wave reflection in micro-structural piezomagnetic-flexomagnetic solid with impedance boundary conditions

The second-order gradient theory is reliable to predict the behavior of mechanical phenomena such as wave scattering, vibration, and buckling in nano/micro-structures. This theory incorporates size-dependent effects including strain-gradient elasticity and micro-inertia, crucial for constitutive modeling of piezomagnetic-flexomagnetic crystals. These small-scale size effects can have significant impact on the sensing mechanism of nanoscale transducers used in structural health monitoring (SHM) and nondestructive testing (NDT). In this article, we address the scattering of a plane wave (P-type longitudinal wave) in a piezomagnetic-flexomagnetic solid halfspace after it reflects from an open surface. The secular equation of quasi plane ( qP ) wave and multiple wave modes generated after reflection have been obtained analytically using non-classical governing equations. Impedance boundary conditions have been considered and conventional stress-free boundary conditions have been obtained as its case. Unlike a conventional piezomagnetic medium, five different wave modes have been traced after reflection (two different surface wave modes are present due to the gradient elasticity and micro-inertia effect). Closed expressions of amplitude ratios and energy flux ratios of reflected waves have been formulated from the system of linear equations. By taking a suitable numerical example, amplitude ratios and energy flux ratios for reflected waves have been plotted with respect to incidence angle. Detailed discussions have been made to understand the influence of impedance boundary and flexomagnetic effect on those ratios. The numerical results have been validated by energy conservation law. This investigation may provide necessary guidelines to understand the plane wave characteristics in micro-structural smart solid structures.

Design and Manufacture of 3 Phase Electric Engine Hydrophore Control System

On board there is a temporary water reservoir called a hydrophore? Hydrophore serves to distribute fresh water that will flow to all parts of the ship's hull or accommodation on the ship, the hydrophore pressure tank cannot work for a long time if the ship is in black out condition. This research method is a type of Experimental research. Data collection techniques carried out are observation, design, making, measurement and documentation. The analysis method uses a descriptive analysis method by describing the working principle of the 3 Phase Electric Machine Hydrophore Control System that has been designed and made by the Research Team. The results of the study produced a 3 Phase Electric Machine Hydrophore Control System trainer we made with the hope that it can be a material or learning tool for students studying at the Polytechnic of Shipping Sciences, especially cadets / cadets of Diploma IV Shipping students who have not carried out sea practice so that when they carry out sea practice there is already an idea they get about the Hydrophore control system Although the tool we made is only a miniature because the tank we use is on a small size scale.

Simultaneous equatorial plasma bubble observation using amplitude scintillations from GNSS and LEO satellites in low-latitude region

This study estimates the scale sizes of the plasma density irregularities and the longitudinal width associated with equatorial plasma bubbles (EPBs) in equatorial and low-latitude regions. By analyzing amplitude scintillation S4 indices and total electron content (TEC) measured from low earth orbit (LEO) satellite’s beacon signals with 400 MHz and Global Navigation Satellite System (GNSS) L1/E1 signals with 1575.42 MHz, recorded by receivers at the KMITL station in Bangkok, Thailand (geographic; 13.73° N, 100.77°E, magnetic: 7.26°N), we investigate the characteristics of these irregularities. We collected data of 154 LEO satellite pass events during nighttime on 21 disturbed days in four equinoctial months in 2021. Based on the presence or absence of the scintillation effects on GNSS and LEO beacon signals, the events are categorized into four classes to estimate the scale size of the plasma density irregularities. The analysis suggests that events with both GNSS and LEO scintillations, as well as events with GNSS scintillation alone, occur predominantly before midnight assuming the presence of the small-scale size of the irregularities within EPB. However, events with only LEO scintillation occur throughout the whole night and some events are observed before the events with both GNSS and LEO scintillations. Post-sunset LEO scintillation alone may be attributed to the onset of EPBs developing at low altitude, while post-midnight LEO scintillation events near the magnetic equator, observed during periods of low GNSS Rate of TEC Index (ROTI) values, are associated with bottom-side ionospheric irregularities but are not linked with EPB. The findings are consistent with previous researches on the generation and decay of electron density irregularities within plasma bubbles. However, this study provides new insights by using specific data sets and analysis techniques, offering a more comprehensive understanding of the association of LEO scintillations with bottom-side ionospheric irregularities near the magnetic equator, not observed in the ROTI map.Graphical

Small object detection leveraging density‐aware scale adaptation

AbstractAlbeit general object detection has made impressive progress in the last decade, as a significant subfield, small object detection still performs far from satisfactorily, which is impeded by several challenges, such as small size, severe occlusion and variant scales. To tackle these challenges, we propose a coarse‐to‐fine small object detection method leveraging density‐aware scale adaptation. Firstly, we employ global sketchy prediction via a coarse network in large scenes and generate adaptively scaled block regions with potential targets. Subsequently, we perform local accurate detection by a fine network for instances in densely packed areas with approximately unified scales. In particular, a density map with object distribution information is utilised to provide a scene classification auxiliary to instruct scale transformation. Extensive experiments on the popular remote sensing benchmark AI‐TOD and representative small object datasets VisDrone and UAVDT demonstrate the superiority of our method for small object detection, achieving an improvement of 2.9% mAP‐vt and 2.1% mAP on AI‐TOD, and outperforming the state‐of‐the‐art methods on VisDrone and UAVDT with an enhancement of 1.7% mAP and 2.0% mAP50, respectively.

The Increasingly Strange Polarimetric Behavior of the Barbarian Asteroids

Polarization phase-curve measurements provide a unique constraint on the surface properties of asteroids that are complementary to those from photometry and spectroscopy and have led to the identification of the “Barbarian” asteroids as a class of objects with highly unusual surfaces. We present new near-infrared polarimetric observations of six Barbarian asteroids obtained with the WIRC+Pol instrument on the Palomar Hale telescope. We find a dramatic change in polarimetric behavior from visible to near-infrared for these objects, including a change in the polarimetric inversion angle that is tied to the index of refraction of the surface material. Our observations support a two-phase surface composition consisting of high albedo and high index of refraction inclusions with a small optical size scale embedded in a dark matrix material more closely related to C-complex asteroids. These results are consistent with the interpretation that the Barbarians are remnants of a population of primitive bodies that formed shortly after calcium-aluminum-rich inclusion (CAIs). Near-infrared polarimetry provides a direct test of the constituent grains of asteroid surfaces.

On elastic gaps in strain gradient plasticity: 3D discrete dislocation dynamics investigation

Although presenting attractive features in dealing with small-scale size effects, strain gradient plasticity (SGP) theories can lead to uncommon phenomena for some boundary value problems. Almost all non-incremental (Gurtin-type) SGP theories including thermodynamically-consistent higher-order dissipation predict elastic gaps under certain non-proportional loading conditions. An elastic gap is defined as a finite change in the equivalent yield stress after an infinitesimal change in the strain conditions, at the occurrence of the non-proportional loading source. The existence of such gaps in reality is largely questioned and represents a major source of uncertainty preventing the development of robust SGP theories for real small-scale applications. Using 3D discrete dislocation dynamics (3D-DDD), the present paper aims at investigating size effects within micron-scale single crystal structures under various non-proportional loading conditions, including tension–compression–passivation, bending–passivation and tension–bending. An in-depth investigation of the occurrence of elastic gaps under these conditions, which are known to entail such gaps when using classical non-incremental SGP theories, is conducted. The obtained 3D-DDD results reproduce well known experimentally confirmed size effects like Hall–Petch effect, Asaro’s type III kinematic hardening and reversible plasticity. However, no evidence of the phenomenon of elastic gaps is found, which constitutes a first indication that this phenomenon may not exist in reality. The simulations are performed on face-centered cubic (FCC) Nickel single grains with cuboid shapes ranging from 2μm to 15μm and different orientations.

A Piezoelectric-Resonator-Based DC–DC Converter Demonstrating 1 kW/cm Resonator Power Density

Piezoelectric components hold promise for realizing power conversion with unprecedented levels of power handling density at small size scales. Dc-dc converter topologies and operating modes have recently been established for high-efficiency utilization of piezoelectrics, and strategies for piezoelectric material selection and component design have likewise been identified for high-performance power conversion. In this letter, we apply these developments to experimentally demonstrate the extraordinary power density capabilities of piezoelectrics. This 275–150 V, 12 W prototype achieves a piezoelectric resonator power handling density of 1.01 kW/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> at 493 kHz, greatly exceeding the densities of previous designs and validating the significant miniaturization potential of piezoelectrics for power conversion.

µ-CT Investigation of Hydrogen-Induced Cracks and Segregation Effects in Austenitic Stainless Steel

Hydrogen can drastically degrade the mechanical properties of a variety of metallic materials. The so-called hydrogen environment embrittlement of austenitic CrNi-type steels is usually accompanied by the formation of secondary surface cracks, which can be investigated in order to assess the embrittlement process. The occurrence of hydrogen-induced cracks is often related to element segregation effects that locally impact the austenite stability. Since there is as yet a lack of investigation methods that can visualize both structures three-dimensionally, the present study investigates the imageability of hydrogen-induced cracks and element segregation structures in austenitic CrNi-steel via micro-computed tomography (CT). In order to improve the X-ray visibility of segregation structures, modified versions of the reference steel, X2CrNi18-9, that contain W and Si are designed and investigated. The investigations demonstrated that small differences in the X-ray attenuation, caused by the W or Si modifications, can be detected via CT, although segregation structures could not be imaged due to their small size scale and image noise. Hydrogen-induced cracks were characterized successfully; however, the detection of the smaller cracks is limited by the resolution capability.

Spatial Pyramid Pooling and Adaptively Feature Fusion based Yolov3 for Traffic Sign Detection

Traffic sign detection is a key part of intelligent assisted driving, but also a challenging task due to the small size and different scales of objects in foreground and closed range. In this paper, we propose a new traffic sign detection scheme: Spatial Pyramid Pooling and Adaptively Spatial Feature Fusion based Yolov3 (SPP and ASFF-Yolov3). In order to integrate the target detail features and environment context features in the feature extraction stage of Yolov3 network, the Spatial Pyramid Pooling module is introduced into the pyramid network of Yolov3. Additionally, Adaptively Spatial Feature Fusion module is added to the target detection phase of the pyramid network of Yolov3 to avoid the interference of different scale features with the process of gradient calculation. Experimental results show the effectiveness of the proposed SPP and ASFF-Yolov3 network, which achieves better detection results than the original Yolov3 network. It can archive real-time inference speed despite inferior to the original Yolov3 network. The proposed scheme will add an option to the solutions of traffic sign detection with real-time inference speed and effective detection results.

A study on credit strategy for small and medium-sized enterprises based on hierarchical analysis

Micro, small and medium-sized enterprises (MSMEs) are enterprises with relatively small staff size and operation scale, which are important subjects for enhancing employment and scientific and technological innovation in China, as well as an important part of China's real economy, and play an irreplaceable role in promoting economic growth and social prosperity. This paper mainly provides research solutions to solve the credit decision problems of banks for MSMEs through quantitative analysis of credit risks of MSMEs, combined with the realistic basis for banks to pursue profit maximization and risk minimization. This paper selects some enterprise data as the research sample, pre-processes the original data, and then selects six indicators to quantify the risk: input invoice efficiency, output invoice efficiency, credit rating, total invoices, total price and tax, and average profit. Based on this, this paper uses AHP hierarchical analysis to calculate index weights of 0.0664, 0.115, 0.0755, 0.1067, 0.2899, and 0.3465, respectively, to weight the indicators of each enterprise to sum up the enterprise's reputation score. Then we derive the enterprise's compliance rate from the scores and build the optimal credit decision model accordingly. Finally, we use the greedy algorithm to solve for the final strategy.

Complex ink flow mechanisms in micro-direct-ink-writing and their implications on flow rate control

Despite its simplicity, low cost, and ability to process a wide range of materials, direct-ink-writing (DIW) is an additive manufacturing process with low resolution and accuracy, in the multiple hundred microns to millimeter range. One of the main sources for this issue is the difficulty with accurately controlling ink flow rate at smaller size scales. Towards addressing this limitation, this paper elucidates complex ink flow mechanisms that renders flow rate control difficult and explores printing implementations to increase flow rate accuracy in direct-ink-writing at the micro scale. To this end, a DIW system utilizing hybrid pressure and velocity-controlled extrusion is used to obtain pressure-flow rate relationships for a water-based sodium carboxymethyl cellulose (NaCMC) solution ink, as a function of printing nozzle diameter (510–100 µm). These studies showed that the transient response of piston velocity-controlled extrusion significantly slows down with decreasing nozzle diameter. For pressure-controlled extrusion, the wall slip increases with decreasing nozzle diameter and the constant slip velocity assumption no longer holds as nozzle size decreases below a certain diameter. To contextualize the influence of such behavior on flow rate accuracy, temperature-controlled parallel plate rheometry was performed on the inks and rheological ink models were accordingly determined. It was shown that the associated flow rate predictions under predicted flow rates due to lack of wall-slip consideration, particularly for smaller nozzle sizes. Lastly, an iterative pressure-controlled DIW implementation was explored to address the accuracy issues for micro-DIW. Our results indicated significant improvement in the transient response and flow rate accuracy for nozzle diameters as small as 100 µm using this approach compared to both of the conventional pressure and velocity control approaches.

A novel method to predict nanofilm morphology on arbitrary-topographical substrate

As physical properties of nanofilms are strongly influenced by their adhered substrates and presented morphologies, it is of vital importance to determine their attaching morphologies on substrates. However, the complex topography of substrate in the practical applications hinders the prediction of attached nanofilm morphology. Previous theoretical methods fail to analyze the complex topography, and molecular dynamics (MD) simulations are limited to small time and size scales. In order to predict the morphology of a nanofilm with an arbitrary size on a substrate with an arbitrary topography, a novel universal method is proposed by combining the mechanical analysis, discrete cosine transform, and multi-resolution analysis together, named multi-resolution discrete cosine transform (MRDCT) method. In this method, the attaching analysis for a complex-topographical substrate is transformed level by level into a sequence of simple mechanical analyses for a 2D-cosine-topographical substrate, of which a semi-analytical model is derived in advance based on the principle of minimum potential energy. Taking the advantages of the pre-derived mechanical model and the multi-level analysis, the MRDCT method has an extremely high efficiency, only about 10−4 of time cost of MD simulations, and moreover, it is not limited by the size scale of nanofilms. The results from both MD simulations and experiments highlight the competency of this method for various complex-topographical substrates. Furthermore, a general conformation criterion in terms of the substrate roughness is derived analytically based on the MRDCT method to assess whether the substrate can be fully conformed by the nanofilm. The proposed MRDCT method can not only be used in the mechanical analysis of film/substrate systems but also provide a new paradigm to solve other complex mechanical problems.

Free transverse vibrations of nanobeams with multiple cracks

A nonlocal model is formulated to study the size-dependent free transverse vibrations of nanobeams with arbitrary numbers of cracks. The effect of the crack is modeled by introducing discontinuities in the slope and transverse displacement at the cracked cross-section, proportional to the bending moment and the shear force transmitted through it. The local compliance of each crack is related to its stress intensity factors assuming that the crack tip stress field is undisturbed (non-interacting cracks).The kinematic field is defined based on the Bernoulli-Euler beam theory, and the small-scale size effect is taken into account by employing the constitutive equation of the stress-driven nonlocal theory of elasticity. In this manner, the curvature at each cross-section is defined as an integral convolution in terms of the bending moments at all the cross-sections and a kernel function which depends on a material characteristic length parameter. The integral form of the nonlocal constitutive equation is elaborated and converted into a differential equation subjected to a set of mathematically consistent boundary and continuity conditions at the nanobeam's ends and the cracked cross-sections. The equation of motion in each segment of the nanobeam between cracks is solved separately and the variationally consistent and constitutive boundary and continuity conditions are imposed to determine the natural frequencies. The model is applied to nanobeams with different boundary conditions and the natural frequencies and the mode shapes are presented at the presence of one to four cracks. The results of the model converge to the experimental results available in the literature for the local cracked beams and to the solutions of the intact nanobeams when the crack length goes to zero. The effects of the crack location, crack length, and nonlocality on the natural frequencies are investigated, also for the higher modes of vibrations. Novel findings including the amplification and shielding effects of the cracks on the natural frequencies are presented and discussed.

Compact high gain 28, 38 GHz antenna for 5G communication

ABSTRACT In this research paper, a miniaturized vertically polarized dual band antenna with its 2x2 MIMO configuration is proposed for 5G communication. The single antenna consists of an off-centered fed, concave-shaped patch surrounded by two mirror-image C-shaped strips. It works as a millimeter wave radiator for 28/38 GHz bands which provide the transmission at ultra-high speed with a gain of 7.46 dBi and 8.56 dBi and an efficiency of 77% and 91% at both frequency bands respectively. The antenna offers a small-scale size of 10 x 10 x 0.254 mm3 and the close compatibility of simulated and measured results shows the practical feasibility of the fabricated prototype for 5G handheld devices. It can be used for device to device communication at 28 GHz and 38 GHz can be used for 5G cellular communications with higher speed, connectivity and low latency. Apart from that an electrical equivalent circuit of the antenna based on its physical structure is designed using AWR software and its results are included and compared with the CST results. The low specific absorption value of 1.05/0.288W/kg at 28/38GHz and the appropriate results of various parameters for MIMO design confirm its relevance for the 5G MIMO applications.