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A vertically stacked, three layer hybrid Hilbert fractal geometry and serpentine radiator-based patch antenna is proposed and characterized for medical implant applications at the Industrial, Scientific and Medical band (2.4-2.48 GHz). Antenna parameters are optimised to achieve miniaturized, biocompatible and stable transmission characteristics. The paper aims to discuss these issues.

Human tissue effects on the antenna electrical characteristics were simulated with a three-layer (skin, fat and muscle) human tissue model with the dimensions of 180×70×60 mm3 (width×height×thickness mm3). Different stacked substrates are utilized for the satisfactory characteristics. Two identical radiating patches are printed on Roger 3,010 (ε _r=10.2) and Alumina (ε _r=9.4) substrate materials, respectively. In addition, various superstrate materials are considered and simulated to prevent short circuit the antenna while having a direct contact with the metallization, and achieve biocompatibility. Finally, superstrate material of Zirconia (ε _r=29) is used to achieve biocompatibility and long-life. A finite element method is used to simulate the proposed hybrid model with commercially available Ansoft HFSS software.

The antenna is miniaturized, having dimensions of 10×8.4×2 mm3 (width×height×thickness mm3). The resonance frequency of the antenna is 2.4 GHz with a bandwidth of 100 MHz at return loss (S11) of better than −10 dB characteristics. Overall, the proposed antenna have 50 Ω impedance matching, −21 dB far field antenna gain, single-plane omni-directional radiation pattern properties and incident power of 5.3 mW to adhere Specific Absorption Rate regulation limit.

Vertically stacked three layer hybrid design have miniaturized characteristics, wide bandwidth, biocompatible, and stable characteristics in three layer human tissue model make this antenna suitable for implant biomedical monitor systems. The advanced simulation analysis of the proposed design constitutes the main contribution of the paper.

This paper aims to investigate the three-dimensional (3D) numerical simulations, based on the Navier–Stokes equations and the energy equation. Forced convection of a mixture of (60:40) percent ethylene glycol and water, was used as the base fluid and CuO nanoparticles, through a serpentine minichannel.

In this simulation, a serpentine mini-channel heat exchanger was simulated. The fluid studied in this simulation was composed of a mixture of (60:40) per cent ethylene glycol and water, was used as the base fluid and CuO nanoparticles. Four slabs and three serpentines were used in this study. The serpentine section is connected to the slab. Three equidistant circular channels (1 mm in diameter) were implemented inside the slab.

Results show that nanoparticles increase the fluid pressure drop and by changing volume fraction of nanoparticles from 0 to 1 per cent, the pressure drop of nanofluids increases between 42and 47 per cent, for Reynolds numbers from 100 to 500. The existence of serpentine bend in the minichannel heat exchanger causes the heat transfer rate to increase. Increase the volume fraction of nanoparticles reduces the fluid temperature at the outlet of the heat exchanger. The numerical results show that in Re = 500, at the beginning of the last slab in middle channel by changing volume fraction of nanoparticles from 0 to 2 per cent, local Nusselt number 57.40 per cent increase. The existence of the serpentine bend causes the heat transfer rate to increase.

Forced convection of a mixture of (60:40) per cent ethylene glycol and water by using of 3D numerical simulations, based on the Navier–Stokes equations.

The residential buildings sector has a high priority in the climate change adaptation process due to significant CO₂ emissions, high energy consumption and negative environmental impacts. The article investigates how, conversely speaking, the residential buildings will be affected by climate change, and how to improve existing structures and support long-term decisions.

The climate dataset was created using the scenarios determined by the Intergovernmental Panel on Climate Change (IPCC), and this was used in the study. Different building envelope and Heating, Ventilating and Air Conditioning (HVAC) systems scenarios have been developed and simulated. Then, the best scenario was determined with comparative results, and recommendations were developed.

The findings reveal that future temperature-increase will significantly impact buildings' cooling and heating energy use. As the outdoor air temperatures increase due to climate change, the heating loads of the buildings decrease, and the cooling loads increase significantly. While the heating energy consumption of the house was calculated at 170.85 kWh/m² in 2020, this value shall decrease significantly to 115.01 kWh/m² in 2080. On the other hand, the cooling energy doubled between 2020 and 2080 and reached 106.95 kWh/m² from 53.14 kWh/m² measured in 2020.

Single-family houses constitute a significant proportion of the building stock. An in-depth analysis of such a building type is necessary to cope with the devastating consequences of climate change. The study developed and scrutinised energy performance improvement scenarios to define the climate change adaptation process' impact and proper procedure. The study is trying to create a strategy to increase the climate resistance capabilities of buildings and fill the gaps in this regard.

This paper aims to present the design of a compact vertically polarized four-element UWB antenna suitable for MIMO communications.

The unit cell antenna is constructed using a square ring radiator excited through a stepped impedance feed. The proposed antenna covers the Ultra-wideband (UWB) spectrum ranging from 2.2 to 12.3 GHz. The isolation between the unit cell antennas in the array is enhanced using a simple microstrip line resonator. The decoupling element is connected to the ground through a via.

The proposed scheme offers at least 16 dB improvement in the port-to-port coupling. Furthermore, the four-element antenna array is constructed using a specific interlocking scheme. The proposed antenna array’s Multiple Input Multiple Output (MIMO) performance metrics are analyzed.

By suitably selecting the excitation port, directional radiation patterns can be realized. The combined radiation pattern covers 360 degrees. A prototype antenna array is fabricated, and the simulation results are verified using real-time experiments. The proposed antenna is a suitable candidate for shark fin housing in automotive communications.

The main purpose of this paper is the generation of the heat transfer and pressure drop correlations by considering three working fluids, namely air, water, and ethylene glycol, for the wavy plate-fin heat exchangers (PFHEs).

In order to present the general correlations, various models with different geometrical parameters should be tested. Because of the problems, such as difficult, long time, and costly fabrication of the wavy fins in experimental tests, computational fluid dynamics (CFD) calculations can be a useful method for the generation of the heat transfer and pressure drop correlations with eliminating the experimental problems. Hence, the effective design parameters of the wavy plate-fin, including fin pitch, fin height, wave length, fin thickness, wave amplitude, and fin length, and also their levels were recognized from the literature. The Taguchi method was applied to formulate the CFD simulation work.

The simulation results were compared and validated with an available experimental data. The mean deviations of the Colburn factor, j, and Fanning friction factor, f, values between the simulation results and the experimental data were 3.74 and 9.07 percent, respectively. The presented air correlations and experimental data were in a good agreement, so that approximately 95 percent of the experimental data were correlated within ±12 percent. The j factor values varied for the different working fluids, while the f factor values did not sensibly change.

The presented correlations can be used to estimate the thermal-hydraulic characteristics and to design of the compact PFHE with the wavy channels.

This manuscript presents the new correlations for the compact PFHEs with the way channels by considering all the geometrical parameters and the working fluids with the different Prandtl numbers, 0.7, 7, and 150.

The purpose of this paper is to investigate how to make tele‐operated tasks easier using an expert system to interpret joystick and sensor data.

Current tele‐operated systems tend to rely heavily on visual feedback and experienced operators. Simple expert systems improve the interaction between an operator and a tele‐operated mobile‐robot using ultrasonic sensors. Systems identify potentially hazardous situations and recommend safe courses of action. Because pairs of tests and results took place, it was possible to use a paired‐samples statistical test.

Results are presented from a series of timed tasks completed by tele‐operators using a joystick to control a mobile‐robot via an umbilical cable. Tele‐operators completed tests both with and without sensors and with and without the new expert system and using a recently published system to compare results. The t‐test was used to compare the means of the samples in the results.

Time taken to complete a tele‐operated task with a mobile‐robot partly depends on how a human operator interacts with the mobile‐robot. Information about the environment was restricted and more effective control of the mobile‐robot could have been achieved if more information about the environment had been available, especially in tight spaces. With more information available for analysis, the central processor could have had tighter control of robot movements. Simple joysticks were used for the test and they could be replaced by more complicated haptic devices. Finally, each individual set of tests was not necessarily statistically significant so that caution was required before generalising the results.

The new systems described here consistently performed tasks more quickly than simple tele‐operated systems with or without sensors to assist. The paper also suggests that the amount of sensor support should be varied depending on circumstances. The paired samples test was used because people (tele‐operators) were inherently variable. Pairing removed much of that random variability. When results were analysed using a paired‐samples statistical test then results were statistically significant. The new systems described in this paper were significantly better at p<0.05 (95 per cent probability that this result would not occur by chance alone).

The paper shows that the new system performed every test faster on average than a recently published system used to compare the results.

This paper aims to investigate the effects of different volume fractions of Al₂O₃-water nanofluid on flow and heat transfer under chaotic convection conditions in an L-shaped channel, comparing the difference of numerical simulation results between single-phase and Eulerian–Lagrangian models.

The correctness and accuracy of the two calculation models were verified by comparing with the experimental values in literature. An experimental model of the L-shaped channel was processed, and the laser Doppler velocimeter was used to measure the velocities of special positions in the channel. The simulated values were compared with the experimental results, and the correctness and accuracy of the simulation method were verified.

The calculated results using the two models are basically consistent. Under the condition of Reynolds number is 500, when the volume fractions of nanofluid range from 1% to 4%, the heat transfer coefficients simulated by single-phase model are 1.49%–25.80% higher than that of pure water, and simulated by Eulerian–Lagrangian model are 3.19%–27.48% higher than that of pure water. Meanwhile, the friction coefficients are barely affected. Besides, there are obvious secondary flow caused by lateral oscillations on the cross sections, and the appearance of secondary flow makes the temperature distributions uniform on the cross section and takes more heat away, thus the heat transfer performance is enhanced.

The originality of this work is to reveal the differences between single-phase and two-phase numerical simulations under different flow states. The combination of chaotic convection and nanofluid indicates the direction for further improving the heat transfer threshold.