A circular monopole antenna for bandwidth enhancement using cylinder slots with triple band notch characteristics

This article introduces a super wideband along with three notch bands circular patch monopole antenna. The design structure is applicable for microwave and high-speed wireless devices (2.19 to 25 GHz). In order to create a broad band, a ring dimension circular patch is used. To generate three notch bands, six symmetrical tiny cylinder stubs are introduced on the ground. These notch band frequencies can eliminate unwanted interference from various wireless frequencies, which mainly cover three notch bands: 5.5–7.3, 12.05–14.46, and 17.71–19.5 GHz. The steady radiation, super bandwidth, and stable gain properties expand when the ring patch and line feed are combined. It is excellent for many UWB applications because of its compact size (39 × 29 mm ²) and large bandwidth (166.97% fractional bandwidth). This model employs various size reduction and matching approaches to get a better response. The mechanisms of these structures are identified, and overall performance is compared with parametric analysis, tables, and figure.     

Computational fluid dynamics simulation of reactive absorption of CO2 in a structured packed column

In this study, multiphase Eulerian computational fluid dynamics (CFD) modelling is developed to predict the hydrodynamics, mass transfer, and chemical absorption of CO₂ using a monoethanolamine (MEA) solution in a structured packed column. First, the hydrodynamic simulation of liquid dispersion in a structured packed bed using a two-dimensional CFD is performed. The simulation results of the radial distribution of the liquid holdup are compared with the literature experimental data. The model prediction matches the experimental data at the top position of the column, whereas a slight deviation is found at the bottom position of the column. Using a validated CFD model, the reactive mass transfer is modelled to study CO₂ capture in a structured packed column with Mellapak 500.X. The model results are compared to the literature experimental results of CO₂ mole fractions along the height of the column. It is found that the model results match the experimental findings. Furthermore, CFD modelling is extended to investigate the influence of operating conditions such as gas and liquid velocities on CO₂ removal efficiency. The present CFD model demonstrates the porous media approach for reactive absorption of CO₂ in a structural packed bed.     

Performance and Analysis of Stack Junctionless Tunnel Field Effect Transistor

Silicon - To overcome the fabrication complexity and achieve a better switching ratio is a major grave concern for applications in semiconductor devices. In this regards, a novel stack gate-oxide...     

Effect of low thermal conductivity wick on the performance of compact loop heat pipe

The existing work deals with the evaluation of compact loop heat pipe by means of a low thermal conductivity sintered chrysotile wick to avoid large heat leaks as of the evaporator to the compensation chamber. Accordingly, a wick with low thermal conductivity (0.068–0.098 W/mK) chrysotile powder of a mean particle diameter of 3.4 μm is fabricated through sintering. Nine chrysotile wicks are sintered with different compositions of binders (bentonite and dextrin) and pore-forming agent NaCl at sintering temperatures of 500°C, 600°C, and 700°C with a sintering time of 30 min. The wick properties, for instance, porosity, permeability, wettability, and capillary rise are studied owing to sintering temperature. Consequently, it is observed that a pure chrysotile powdered wick at a sintering temperature of 600°C exhibits a high porosity of 61.8% with permeability 1.04 × 10⁻¹³ m² and a capillary rise of 4.5 cm in 30 s and is considered optimal. This optimal wick is used for performance evaluation in compact loop heat pipe and a decrease of 36.1% in thermal resistance is found when compared with copper mesh wick in a loop heat pipe. The lowermost thermal resistance originates to be 0.147 K/W at 120 W with wall temperature 57.7°C. This indicates that loop heat pipe with sintered chrysotile wick can operate at lower heat loads efficiently when compared with copper mesh wick and as heat load increases a chance of dry out condition occurs. The highest evaporative heat transfer coefficient obtained is 65.7 kW/m² K at a minimum heat load.