Circular Cap Research Articles

SUB-6 5G NETWORKS: DESIGN OF BUTTON MUSHROOM MIMO ANTENNA AND IT’S INVESTIGATION

The unlicensed National Information Infrastructure radio band (n77, n78, and n46) is taken into consideration for this research work's "Multiple-input-multiple-output (MIMO)" antenna with dual band features. Gradually, the form design of simple single-patch MIMO antennas gives way to four-element MIMO antennas. Four microstrip antennas are integrated using button-like circular caps on the main patches. Reduced ground is also used in the construction of many band characteristics. Excellent isolation can be achieved by using Rectangular Metallic Strip (RMS). The suggested MIMO antenna has the advantage of covering two significant frequency bands. At 3.07 GHz and 6.31 GHz, the antenna system resonates with a total bandwidth of 2.43 GHz. The antenna design uses a FR4 substrate measuring 35 mm by 49 mm by 1.6 mm in thickness. For simulation purposes, Teflon and a specially made SMA connector with a perfect electrical conductor (PEC) are used to enhance impedance matching. An 8.2 mm feed line with an inset feed is also utilized. Research and investigation are conducted on radiation properties, including mean effective gain, envelope correction coefficient, reflection coefficient, and more. Both the reflection and isolation coefficients have values of less than -10 dB, with the former being less than -15 dB. It is a 16.30 dB increase overall. 5G applications will greatly benefit from having this smaller, four-element MIMO antenna.

SUB-6 5G NETWORKS: DESIGN OF BUTTON MUSHROOM MIMO ANTENNA AND IT’S INVESTIGATION

The unlicensed National Information Infrastructure radio band (n77, n78, and n46) is taken into consideration for this research work's "Multiple-input-multiple-output (MIMO)" antenna with dual band features. Gradually, the form design of simple single-patch MIMO antennas gives way to four-element MIMO antennas. Four microstrip antennas are integrated using button-like circular caps on the main patches. Reduced ground is also used in the construction of many band characteristics. Excellent isolation can be achieved by using Rectangular Metallic Strip (RMS). The suggested MIMO antenna has the advantage of covering two significant frequency bands. At 3.07 GHz and 6.31 GHz, the antenna system resonates with a total bandwidth of 2.43 GHz. The antenna design uses a FR4 substrate measuring 35 mm by 49 mm by 1.6 mm in thickness. For simulation purposes, Teflon and a specially made SMA connector with a perfect electrical conductor (PEC) are used to enhance impedance matching. An 8.2 mm feed line with an inset feed is also utilized. Research and investigation are conducted on radiation properties, including mean effective gain, envelope correction coefficient, reflection coefficient, and more. Both the reflection and isolation coefficients have values of less than -10 dB, with the former being less than -15 dB. It is a 16.30 dB increase overall. 5G applications will greatly benefit from having this smaller, four-element MIMO antenna.

Investigating binary granular mixing in a rotating drum using ultrafast X-ray computed tomography

The transient mixing dynamics of an initially segregated binary granular system in a half-filled rotating drum are experimentally investigated. The granular system consists of spherical beads having identical size. The density ratio between the two granular phases is 2.8. With its ability to scan three-dimensional opaque systems with a high frequency, the ultrafast X-ray computed tomography is used to capture the transient and steady-state segregation dynamics in the bulk. The segregation dynamics are also compared to those at the circular end-wall caps, which have been captured with a camera. The results show an axial migration of the denser particles towards the bulk and, more importantly, second-order overshooting dynamics in the radial mixing index, which tend to increase with the Froude number. The results will find application in industrial systems, where rapid mixing occurs. We also believe the presented data can serve as validation for future three-dimensional simulations focusing on the transient formation of segregation patterns in the bulk.

Calculation of circular cap plate connection

In Viet Nam, there are quite a lot of standard, documents and textbooks on Steel Structures [1, 3, 4, 5, 6, 7, 8]..., however, calculating construction site joints uses circular cap plate and bolts to Connecting steel tube members is only mentioned in the textbook Steel Structures for Civil and Industrial Construction [2]. In particular, calculating circular cap plate thickness is determined based on looking up the chart, this method is quite manual and inconvenient. Therefore, it is necessary for the author to establish a concise formula to determine circular cap plate thickness. Therefore, this paper has presented circular cap plate connections, proposed a formula, established look-up tables to determine circular flange thickness according to that formula and compared with the results in the chart; then present conclusions and recommendations.

Discharge performance of a submerged seawater intake in unsteady flows: Combination of physical models and decision tree algorithms

Developing impressive and cost-effective desalination technologies is crucial for addressing the increasing global demand for freshwater. In this regard, along with the process type and technology of desalination, the system's efficiency relies on the availability of a sufficient, constant, uniform, and high-quality discharge flow from the seawater intake structure. This investigation concerns the discharge flow performance of velocity caps, which serve as submerged seawater intake structures, in unsteady flows using physical models and decision tree algorithms. The observations indicate that the square caps are more prone to instability compared to the circular caps when exposed to waves. Additionally, circular caps can increase efficiency by about 12 % compared to square caps. Therefore, the circular velocity cap is more optimal than the square one. Results show that increasing wave height and period decreases the discharge through the intake due to increased interaction between wave and intake structure. Also, wave steepness leaves a significant reverse effect on seawater intake of about 40 %. The study also found that the optimal relative bottom height (w/h) is 1 for high flow depths and 0.5 for low flow depths, respectively. Finally, practical equations of discharge coefficients have been proposed based on decision tree algorithms with high accuracy. These high-accuracy equations show great potential for designing new desalination systems and optimizing existing ones.

Hydraulic performance of bottom intake velocity caps using PIV and OpenFOAM methods

The objective of this investigation is to obtain a more profound understanding of the effective parameters of the velocity caps for bottom intake systems, utilizing particle image velocimetry (PIV) and OpenFOAM. Observations indicate a higher probability of surface vortex formation in square types compared to circular ones, with the vortex being formed downstream of the caps. Additionally, the flow pattern reveals that the flow whirls in a more favorable path into the circular caps as opposed to the square ones. Through both experimental and numerical comparisons of three shapes (rhombus, square, and circle), it becomes evident that the circular type outperforms the other types in terms of discharges through the intake, showing an improvement of about 8%. The results indicate that flow depth and height of the velocity caps are positively effective parameters for the flow rate, with respective influences of 90% and 30%. In contrast, the interaction between the flow and caps intensifies with an increase in the distance of the intake opening from the bed, which plays a negative influence on the flow rate. Enhancing the number of blades in caps proves to be the optimal approach for generating a smoother flow with minimal impact on the flow rate. Numerical simulations show a 50% reduction in cap height leads to a significant 33% decrease in flow rate. Additionally, rotating the square cap by 45° into a rhombus aligned with the flow direction results in a 7% discharge flow rate increase.

Simplified calculation methods for earthquake-induced hydrodynamic added mass of immersed pile caps with different cross-sections

Assessment of the earthquake-induced hydrodynamic added mass of pile caps is important in predicting the seismic resilience of deep-water bridges with an elevated pile group foundation. Simplified formulas for the hydrodynamic added mass of immersed pile caps with different cross-sections were derived in this paper. The added mass values of circular pile caps with various dimensions and submerged depths were estimated based on the numerical fluid-structure coupled model, and the corresponding added mass calculation formula was obtained through the curve fitting method. The formulas to determine the added mass for rectangular pile caps and rectangular pile caps with fillet or chamfer corners were further developed by incorporating the corresponding shape coefficients for the pile cap in the formula. A total of 200 pile caps with different cross-sections and physical parameters were selected using Latin hypercube sampling to assess the performance of the proposed formulas. Next, the consistency between these formulas and the numerical model for added mass results was observed. The proposed formulas are concise and enable efficient calculation of the hydrodynamic added mass of pile caps submerged in water.

Electrical Modeling and Impedance Spectra of Lithium-Ion Batteries and Supercapacitors

In this study, electrical models for cylindrical/pouch-type lithium Li-ion batteries and supercapacitors were investigated, and the impedance spectra characteristics were studied. Cylindrical Li-ion batteries use Ni, Co, and Al as the main materials, while pouch-type Li-ion batteries use Ni, Co, and Mn as the main materials. Herein, 2600–3600 mAh 18650-type cylindrical Li-ion batteries, 5000 mAh 21700-type cylindrical Li-ion batteries, 37–50.5 Ah pouch-type Li-ion batteries, and a 2.7 V, 600 F supercapacitor are compared and analyzed. For a cylindrical Li-ion battery, the RS value of a battery with a protection device (circular thermal disc cap) is in the range of 14–38 mΩ. For the 18650-type cylindrical Li-ion battery with a protection device, the RS value of the battery is between 48 and 105 mΩ, and the protection device increases the RS value by at least 33 mΩ. A good Li-ion battery exhibits RS. Moreover, it has small overall RP and CP values. For the 21700-type cylindrical Li-ion battery with a protection device, the RS value of the battery is 25 mΩ. For the pouch-type Li-ion battery, the RS value of the battery is between 0.86 and 1.04 mΩ. For the supercapacitor, the RS value of the battery is between 0.4779 and 0.5737 mΩ. A cylindrical Li-ion battery exhibits a semicircular shape in the impedance spectrum, due to the oxidation and reduction reactions of Li ions, and the impedance increases with a slope of 45° in the complex plane, due to the ZW generated by Li ion diffusion. However, for a pouch-type Li-ion battery, the impedance spectrum exhibits a part of the semicircular shape, due to the oxidation and reduction reactions of Li ions, and the ZW generated by Li ion diffusion does not appear. In a supercapacitor, the oxidation and reduction reactions of ions do not appear at all, and the ZW generated by Li ion diffusion does not occur.

Load Transfer in Geosynthetic-Reinforced Piled Embankments with a Triangular Arrangement of Piles

A geosynthetic-reinforced piled embankment situated along a newly constructed high-speed rail line was fully instrumented and monitored to explore soil arching in an equilateral-triangular arrangement of piles with circular cap configuration. During construction, the settlement and vertical stress on the pile caps and subsurface at ground level and the tensile strain in the geogrid were recorded. A modified analytical arching model is derived from the established concentric arches (CA) model to elucidate the load transfer mechanism, specifically for a triangular array of piles. The general framework assumes that the embankment load, not resting on the subsurface beneath the arches, is transferred outward along the arches and distributed uniformly over the improved ground. Compared to the conventional CA model, the proposed model gives a lower proportion of load carried by piles, more in line with field measurements. Given the friction and adhesion between soil and geosynthetics, a novel quartic equation is applied to characterize the tensioned membrane effect of geosynthetic reinforcement based on Pham’s circular and parabolic models. The stiffness variation of the biaxial geogrid was critically assessed for the triangular pile arrangement, and its implications for the design were revealed. Finally, the pile efficacy and critical arch height were determined from different analytical methods and checked against field observations, demonstrating the potential of the proposed model.

Exploring the Absorption Spectra of an Ultra-Wideband Metamaterial Absorber in the Visible and Near-Infrared Regions.

This paper investigates the absorption spectra of a plasmonic metamaterial absorber in the visible and near-infrared regimes by utilizing a metal-dielectric-metal (MDM) functional stack. A periodic metal-dielectric cap is introduced on top of a metallic substrate to excite surface plasmon modes. The shape of this cap and the glass coating modifies the absorbance bandwidth. Although the circular cap exhibits less broadening in the absorbance than the square one, the circular cap’s glass coating boosts the bandwidth’s expansion in the near-infrared region to about 1.65 µm. In the visible and near-infrared regimes, absorption bandwidth and spectral ratio can be tailored by modifying four distinct structural parameters. The finding shows that one can achieve an ultra-broad bandwidth that extends from 0.3 µm to 1.65 µm at 90% absorbance. The thickness of the top titanium layer, the silicon dioxide spacer thickness, the Ti-SiO2 cap diameter, and the sliver substrate pitch are selected to be 20 nm, 60 nm, 215 nm, and 235 nm, respectively. Furthermore, the influence of using various metals on absorption spectra has been explored in the visible and near-infrared regimes. The d metals considered for the top layer are titanium, nickel, chromium, silver, copper, gold, aluminum, and gold.

Monitoring of an instrumented geosynthetic-reinforced piled embankment with a triangular pile configuration

ABSTRACT A comprehensive monitoring programme was undertaken at a geosynthetic-reinforced piled embankment over soft ground to better understand its time-dependent performance. The programme involved continuous monitoring of earth pressure, axial force in piles, settlement of structural elements, lateral movement of subsoil, and geogrid tensile strain of the instrumented system. Earth pressure measurements evidenced the mobilization of soil arching; pile efficacies were derived from established analytical methods and assessed against observed data for piles with circular cap configuration arranged in a triangular pattern, with the Concentric Arches model giving the best predictions. The development of axial load in piles can be properly captured by a regression equation with analytical approach. Penetration and compression behaviours of structural elements were evaluated by settlement measurement on piles and soils at ground level relative to pile toe or substratum. The proposed approach in obtaining tensile force of geogrid was verified with the measured differential-settlement data.

Kavitationsdynamik in geschmierten Kontakten - Weiterentwicklung eines Modells mit Blasendynamik

Cavitation is a widespread phenomenon in journal bearings and other lubricated contacts. In lubricated contacts, tensile stresses can occur in the lubricant as a result of cavitation dynamics. These tensile stresses, hardly known with respect to duration and magnitude, are investigated with a simulation model consisting of Reynolds equation and Rayleigh-Plesset equation for the negative squeeze motion of circular plate and spherical cap. The tensile stresses are practically relevant in calculating the opening times of valves (oil stiction). It may assumed that the short-time tensile stresses occurring in the simulation model also occur in other cases and have an influence on material fatigue and wear of the components involved and are thus practically relevant.

Constraints on the behavior of a descending ice probe due to force balance

Water is a key ingredient to the potential for life, and several icy moons, such as Europa and Enceladus, are thought to harbor a dynamic subsurface ocean of liquid water. An ice probe or “cryobot” is a proposed technology to penetrate the surrounding ice shell and deliver a life-detection payload to these oceans. As the ice probe descends, it is surrounded by a thin melt film of liquid water. This paper focuses on the fluidics of the melt film for the case of a general ice probe shape, leading to a new approximate equation for the force balance constraints (validated to <0.4% error by numerical model). In addition to the introduction of water by melting, the analysis allows for consideration of additional volumetric flow via a pumped jet of recirculated water. The general force balance equation is explored in more detail for the example of a cylindrical probe geometry with flat circular end caps. The thickness of the melt film below and to the side of the cylindrical probe is constrained by the force balance such that the probe typically operates in one of two asymptotic regimes, moving or stalled.

Modelling topographic waves in a polar basin

This study is concerned with properties of freely propagating barotropic Rossby waves in a circular polar cap, a prototype model for the Arctic Ocean. The linearised shallow-water equations are used to derive an amplitude equation for the waves in which full spherical geometry is retained. Almost by definition, polar basin dynamics are confined to regions of limited latitudinal extent and this provides a natural small scale which can underpin a rational asymptotic analysis of the amplitude equation. The coefficients of this equation depend on the topography of the basin and, as a simple model of the Arctic basin, we assume that the basin interior is characterised by a constant depth, surrounded by a continental shelf-slope the depth of which has algebraic dependence on co-latitude. Isobaths are therefore a family of concentric circles with centre at the pole. On the shelf and slope regions the leading order amplitude equation is of straightforward Euler type. Asymptotic values of the wave frequencies are derived and these are compared to values computed directly from the full amplitude equation. It is shown that the analytic results are in very good accord with the numerical predictions. Further simulations show that the properties of the waves are not particularly sensitive to the precise details of the underlying topography; this is reassuring as it is difficult to faithfully represent the shelf topography using simple mathematical functions.

A theoretical solution of the axial stiffness of a cylindrical shell with a circular plate

A structure of a cylindrical shell with a circular plate end cap is usually used in connect different shaft system and it is necessary to estimate the axial stiffness in order to analyze the vibration of the rotor system. This paper builds the model of this structure. The theoretical solution of the bending deflection of the circular plate and the cylindrical shell are deduced by using the classic theory of plates and shells, and the continuity boundary conditions at the junction of the circular plate and the cylindrical shell. Furthermore, the axial stiffness of the structure is solved through considering the relationship between the external force-bending deformation. Two different boundary conditions for the left side of the cylindrical shell is considered and their axial stiffness varying with the length of the cylindrical shell is calculated. For verification, a finite element model of the structure is built and analyzed. The theoretical results fairly coincide with the finite element ones.

Notch sensitivity of Sanicro 25 in small punch creep test

Small punch creep tests of unnotched and notched 8 mm discs of new austenitic steel Sanicro 25 were performed at 700 °C. Side notches through the disc thickness proposed by Lacalle of different lengths ranging from 3.0 to 4.5 mm were applied for this study. It was found that the notch length influences the time to rupture and the minimum displacement rate, however no apparent signs of crack initiation were observed on the recorded time-displacement and time-displacement rate curves at 400 N force. The shortest time to rupture and fastest displacement rate were obtained for notch length of 3.5 mm, while the longest time to rupture and slowest displacement rate were obtained for notch length of 4.25 mm. The fracture of Sanicro 25 discs had signs of a “star” shape, with multiple cracks, which indicates lower ductility. A larger circular cap which is obvious for materials with high ductility was not present in all the small punch tests performed.

Effect of eccentric loading on energy absorbing circular cap and open end frusta tube structures

The response of cap end (C) and open end (O) frusta tube made of aluminium alloy AA-1080 were explored against eccentric loading by carrying out numerical simulation. The thickness of both type of frusta tube was varied as 1.15, 1.2 and 1.3 mm whereas height of open end and cap end frusta tube were considered as 91.6 and 103 mm respectively. The semi-apical angle was varied as 5.71°and 7.59° which resulted base diameter 60.8 and 67.2 mm for both type of tubes respectively. The variation in eccentricity of loading from the axis of the tubes was kept as 5, 8 and 12 mm. The numerical simulations were carried out by using commercial finite element code LS-DYNA. The performance of structures was decided based on crashworthiness parameters like Peak force, Mean crushing force, Crash load efficiency and Energy absorption capability.For validating the numerical results, experiments were performed on compression testing machine wherein both cap end and open end specimens with the thickness of 1.15 mm were compressed with eccentricity 5 mm. The actual results were found close enough with predicted results. Cap end structure showed higher Crash load efficiency and energy absorption compared to the open end frusta tube.

Collision of Expanding Actin Caps with Actomyosin Borders for Cortical Bending and Mitotic Rounding in a Syncytium

The early Drosophila embryo is a large syncytial cell that compartmentalizes mitotic spindles with furrows. Before furrow ingression, an Arp2/3 actin cap forms above each nucleus and is encircled by actomyosin. We investigated how these networks transform a flat cortex into a honeycomb-like compartmental array. The growing caps circularize and ingress upon meeting their actomyosin borders, which become the furrow base. Genetic perturbations indicate that the caps physically displace their borders and, reciprocally, that the borders resist and circularize their caps. These interactions create an actomyosin cortex arrayed with circular caps. The Rac-GEF Sponge, Rac-GTP, Arp3, and actin coat the caps as a growing material that can drive cortical bending for initial furrow ingression. Additionally, laser ablations indicate that actomyosin contraction squeezes the cytoplasm, producing counterforces that swell the caps. Thus, Arp2/3 caps form clearances of the actomyosin cortex and control buckling and swelling of these clearances for metaphase compartmentalization.

Peltate trichomes on biogenic silvery leaves of Elaeagnus umbellata.

External and internal features of Elaeagnus umbellata leaves were investigated by optical and electron microscopy. The adaxial (upper) and abaxial (lower) leaf surfaces appeared green and silver in color, respectively. There were peltate trichomes on both the adaxial and abaxial leaf surfaces. The peltate trichomes were 200-300 μm in diameter and shield or umbrella-shaped. They had a central dome and 20-30 radiating rays that were fused to form a circular cap in the center and tapered at the end. The density of peltate trichomes was apparently higher on the abaxial leaf surface than on the adaxial leaf surface. At least two layers of peltate trichomes were commonly observed on the abaxial leaf surface. The epidermal cells on the abaxial leaf surface had convex lens-like shape in cross sections. No distinct chloroplasts were found in the cytoplasm of peltate trichomes. These results suggest that the silver coloration on the abaxial leaf surface is mostly due to structural coloration associated with the profuse overlapping peltate trichomes having a circular cap of radially fused rays. The shrub did not show any pigmentary cellular features associated with the silver coloration. With the silvery leaves as a reflective surface for shaded leaves in canopy, E. umbellata is likely to adapt to the harsh non-native light-demanding environments.

A model for pressurized hydrogen induced thin film blisters

We introduce a model for hydrogen induced blister formation in nanometer thick thin films. The model assumes that molecular hydrogen gets trapped under a circular blister cap causing it to deflect elastically outward until a stable blister is formed. In the first part, the energy balance required for a stable blister is calculated. From this model, the adhesion energy of the blister cap, the internal pressure, and the critical H-dose for blister formation can be calculated. In the second part, the flux balance required for a blister to grow to a stable size is calculated. The model is applied to blisters formed in a Mo/Si multilayer after being exposed to hydrogen ions. From the model, the adhesion energy of the Mo/Si blister cap was calculated to be around 1.05 J/m2 with internal pressures in the range of 175–280 MPa. Based on the model, a minimum ion dose for the onset of blister formation was calculated to be d = 4.2 × 1018 ions/cm2. From the flux balance equations, the diffusion constant for the Mo/Si blister cap was estimated to be DH2=(10±1)×10−18 cm2/s.