Applied Input Power Research Articles

A Miniaturized Tri-Band Implantable Antenna for ISM/WMTS/Lower UWB/Wi-Fi Frequencies.

This study aims to design a compact antenna structure suitable for implantable devices, with a broad frequency range covering various bands such as the Industrial Scientific and Medical band (868-868.6 MHz, 902-928 MHz, 5.725-5.875 GHz), the Wireless Medical Telemetry Service (WMTS) band, a subset of the unlicensed 3.5-4.5 GHz ultra-wideband (UWB) that is free of interference, and various Wi-Fi spectra (3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz, 6 GHz). The antenna supports both low and high frequencies for efficient data transfer and is compatible with various communication technologies. The antenna features an asynchronous-meandered radiator, a parasitic patch, and an open-ended square ring-shaped ground plane. The antenna is deployed deep inside the muscle layer of a rectangular phantom below the skin and fat layer at a depth of 7 mm for numerical simulation. Furthermore, the antenna is deployed in a cylindrical phantom and bent to check the suitability for different organs. A prototype of the antenna is created, and its reflection coefficient and radiation patterns are measured in fresh pork tissue. The proposed antenna is considered a suitable candidate for implantable technology compared to other designs reported in the literature. It can be observed that the proposed antenna in this study has the smallest volume (75 mm3) and widest bandwidth (181.8% for 0.86 GHz, 9.58% for 1.43 GHz, and 285.7% for the UWB subset and Wi-Fi). It also has the highest gain (-26 dBi for ISM, -14 dBi for WMTS, and -14.2 dBi for UWB subset and Wi-Fi) compared to other antennas in the literature. In addition, the SAR values for the proposed antenna are well below the safety limits prescribed by IEEE Std C95.1-1999, with SAR values of 0.409 W/Kg for 0.8 GHz, 0.534 W/Kg for 1.43 GHz, 0.529 W/Kg for 3.5 GHz, and 0.665 W/Kg for 5.5 GHz when the applied input power is 10 mW. Overall, the proposed antenna in this study demonstrates superior performance compared to existing tri-band implantable antennas in terms of size, bandwidth, gain, and SAR values.

Importance of higher‐level excited species in argon remote plasma sources: Numerical modeling with consideration of detailed chemical reaction pathways

AbstractStable plasma ignition of remote plasma sources (RPSs) for various plasma processes is essential to ensure the stability of the discharge, steady operating conditions, and high plasma density. In an RPS in which the gas pressure exceeds 1 Torr, the reaction paths leading to the high‐level excited state play an essential role in the power balance and energy cascade at high applied input power. In this study, 97 chemical reactions in a detailed reaction set involving argon discharge are investigated in the steady‐state to understand the extent to which the dominant reactions are affected by variations in the process parameters. We observed that the stepwise ionization process of the argon 4p excited state significantly contributes to sustaining high‐density plasmas in the near 1 Torr regime.

Experimental study on confinement effect of two-phase closed thermosyphon and heat transfer enhancement using cellulose nanofluid

This study experimentally investigated the confinement effect on the boiling regime of a two-phase closed thermosyphon and heat transfer enhancement using cellulose nanofiber fluid as the working fluid. The design lengths of the condenser, adiabatic, and evaporator sections of the experiment apparatus were 400, 150, 300 mm, respectively. The filling ratios were set to 0.25, 0.5, and 0.75. The applied input power was limited to 800 W owing to the heat resistance limit of the heating block, which supplies heat to the evaporator section. By applying Confinement number of 0.245 and using de-ionized water as the working fluid, the inner diameter of the channel was set to 11 mm. The boiling regime for each level of input power was determined using the surface temperature graph of the thermocouples attached to the evaporator section. It was observed that geyser boiling occurred at a low input power; in this regime, the surface temperature was observed to have a regular long-period oscillation with a large amplitude. Subsequently, the amount of heat increased, the amplitude remained the same, and the cycle length reduced. Churn boiling regime was observed at high input power, with the surface temperature having a very small and irregular amplitude. When the input power was further increased, dry out occurred and the surface temperature soared significantly. Using cellulose nanofiber fluid as a working fluid, the critical heat flux improved by a minimum of 14.3% and the boiling heat transfer coefficient improved by up to 71.74%, compared to water. In addition, aggregation and sedimentation phenomena, which are disadvantages of existing inorganic nanofluids, were not observed after repeated experiments.

Feasible production of hydrogen from methanol reforming through single stage DC microplasma reactor

Plasma-assisted methanol reforming is an effective technology to produce hydrogen for various clean energy applications. In this study, hydrogen was produced from methanol reforming in a unique single stage microplasma reactor. Microplasma was produced between the capillary stainless steel tube electrodes by using high voltage direct current (DC) power supply. Blend of methanol and water was supplied to the microplasma reactor in a controlled flow rate using nitrogen as carrier gas. The effects of applied input power to the discharge and methanol feed rate on the performance of the plasma methanol decomposition were investigated. The experimental results showed that increasing the applied input power expressively increased the methanol conversion and hydrogen energy yield. In contrast, the increased feed rate significantly decreased the methanol conversion efficiency though it enriched the hydrogen energy yield. Under selective conditions, hydrogen energy yield of 24.14 g kW[Formula: see text] h[Formula: see text] was achieved with the conversion efficiency of 71% and 50% selectivity for H2, which is comparatively better than many of plasma-assisted methanol reforming processes. This investigation reveals that methanol reforming through a single stage microplasma reactor has the ability to produce hydrogen efficiently without coke formation at room-temperature and atmospheric pressure.

The production of Titanium Powder via Hydrogen Reduction of Titanium Tetrachloride by Inductively Coupled RF plasma

In this study, the production of titanium powder via hydrogen reduction of titanium tetrachloride by inductively coupled radio frequency plasma was investigated. While titanium tetrachloride is hard to be reduced by hydrogen thermodynamically, dissociated hydrogen radical which formed from hydrogen gas passing through the plasma can react with titanium tetrachloride to form hydrochloric acid and subsequently produce titanium. The frequency of generator used in this experiment was 13.56 MHz and input power was varied. The characteristics of the powder such as powder size, size distribution, and phases were analyzed with x-ray diffractometer, field emission scanning electron microscope, energy dispersive x-ray spectrometer and transmission electron microscope. The deposited height of titanium powders, after 4 minutes reaction, were 4.004 μm and loosely attached that could be easily collected. The morphology of powders was found to be more spherical with the increase in applied input power. Most of the powders were composed of titanium and oxygen. The average diameter of powders was approximately 200 nm.

Thermal response for intermodulation distortion components of GaN HEMT for low and high frequency applications

Thermal effect on intermodulation distortion (IMD) behavior of GaN based high-electron mobility transistor (HEMT) have been researched over input power and frequency using a two-tone technique. A significant modification was observed in terms of magnitude on the linear component and the magnitude as well as the position and appearance of the nulls/notches of the nonlinear components was changed conspicuously. The parasitic resistances and as well as the output current were affected when applied input power increases. As a result, an increase in the output IMDs found and the device threshold voltage VT moves towards more negative of Vgs trace which in turn shifts the notch points of the nonlinear IMDs towards lower values of applied bias Vgs. The values of the output IMDs degrades with the increment of temperature and frequency. The output IMD products also reduced following the transconductances response to temperature. On the other hand, the notch/null's position of the nonlinear IMDs also moves following the thermal response of threshold voltage. This authentic and exhaustive study is crucial to figure out the minimum distortion, maximum gain bias option for active devices.

Prediction of variation of oxides of nitrogen in plasma-based diesel exhaust treatment using artificial neural network

Diesel exhaust treatment in plasma environment is a complex phenomenon mainly involving oxidation of several gaseous pollutants. With the help of artificial neural network, an attempt has been made in this paper to predict the variation of nitric oxide/nitrogen dioxide when the exhaust is subjected to discharge plasma. Electrical (power and frequency) and physical (engine load and flow rate) parameters have been considered as inputs of a three-layered artificial neural network model to track the performance of the treatment. Two different backpropagation algorithms named Bayesian regularization and Levenberg–Marquardt have been applied to compare the prediction performance. Bayesian regularization training algorithm shows better agreement with the experimental data than Levenberg–Marquardt in terms of root-mean-square error and correlation coefficient. Further, sensitivity analysis has been carried out to obtain an insight about the relative importance of input parameters on output parameters. This investigation shows that the applied input power is the most influential among the four input parameters from the point of variation of nitric oxide/nitrogen dioxide.

Novel Kerr-Vernier effects within the on-chip Si-ChG microring circuits

We propose a new concept of the nonlinear effect called the Kerr-Vernier effect by using cascaded Si-ChG microring circuits. The circuit is simulated for two materials of different refractive indices which results in phase difference in propagating light and hence observed in the output signal. By varying the input power into the system, the Vernier effects in terms of the Kerr-Vernier effects are seen. In application, the comparative results of the two-channel outputs are used to form the phase sensors, while the self-calibration between the two-channel outputs can be performed. The change in wavelength at the whispering gallery mode of 8 nm is achieved when the applied input power was fixed at 10 mW. A sensitivity of ∼120 µm W-1is obtained for this proposed sensor.

Ar + H2 Plasma Interacting with Lithium-Filled Capillary Porous Structure

Ar + H2 plasma interacting with liquid lithium was carried out on a one-cathode linear plasma device (SCU-PSI). The lithium sample was covered with capillary porous structure (CPS). It is found that the electron temperature of applied plasma ranged from ~0–1 eV and electron density ranged from 0.1 × 1020 to 1 × 1020 m−3. The experimental results indicate that a reduction in the electron temperature and the lithium evaporation is found as the percentage of H2 increases When the ratio of argon and hydrogen keeps constant, the electron temperature and lithium evaporation increase with applied input power, respectively. The retention of hydrogen atoms in lithium surface results in reducing the lithium evaporation. The XRD analysis result shows that during plasma radiation no LiH is formed.

Metal-Coated Silicon Nanowire Embedded Plasmonic Photonic Crystal Fiber: Kerr Nonlinearity and Two-Photon Absorption

In silicon, the presence of two photon absorption (TPA) and the generated free carriers can strongly perturb any Kerr-related nonlinear performance. Special consideration about the geometry and applied input power is needed to reduce undesirable free carrier effects (FCE). In our study, a plasmonic photonic crystal structure consisting of a central metal-coated silicon nanowire is proposed. The photonic crystal cladding and plasmonic nature of the guided modes provide the efficient wave propagation in the subwavelength core radius size of 150 nm, well beyond the diffraction limit at λ = 1.55 μm. Considerable increase of the threshold powers (approximate increment of 42d B W and 12d B W for the free carrier absorption and dispersion threshold powers at r S i = 500 nm) for the observation of FCE is a distinguished feature of the proposed structure which guarantee the safe launch of high input powers for full development of Kerr-based phenomena. An excellent agreement between the numerical solution of the nonlinear schrodinger equation and the calculated threshold powers confirms the obtained results. The proposed structure has potential applications in the areas regarding the Kerr-related nonlinear performance especially with relative high powers utility.

Investigation of micromixing by acoustically oscillated sharp-edges.

Recently, acoustically oscillated sharp-edges have been utilized to achieve rapid and homogeneous mixing in microchannels. Here, we present a numerical model to investigate acoustic mixing inside a sharp-edge-based micromixer in the presence of a background flow. We extend our previously reported numerical model to include the mixing phenomena by using perturbation analysis and the Generalized Lagrangian Mean (GLM) theory in conjunction with the convection-diffusion equation. We divide the flow variables into zeroth-order, first-order, and second-order variables. This results in three sets of equations representing the background flow, acoustic response, and the time-averaged streaming flow, respectively. These equations are then solved successively to obtain the mean Lagrangian velocity which is combined with the convection-diffusion equation to predict the concentration profile. We validate our numerical model via a comparison of the numerical results with the experimentally obtained values of the mixing index for different flow rates. Further, we employ our model to study the effect of the applied input power and the background flow on the mixing performance of the sharp-edge-based micromixer. We also suggest potential design changes to the previously reported sharp-edge-based micromixer to improve its performance. Finally, we investigate the generation of a tunable concentration gradient by a linear arrangement of the sharp-edge structures inside the microchannel.

Surface acoustic wave based pumping in a microchannel

Pumping and manipulation of liquids in microfluidic channels are important for many mechanical, chemical and biomedical applications. Surface acoustic wave based devices fabricated on high-efficiency piezoelectric substrates have been recently investigated for mixing and separation application within microfluidic channels. In this paper, we introduce a novel integrated surface acoustic wave based pump for liquid delivery and precise manipulation within a microchannel. The device employs a hydrophobic surface coating (Cytop) in the device design to decrease the friction force and increase the bonding. Contrary to previous surface acoustic wave based pumps which were mostly based on the filling and sucking process, we demonstrate long distance media delivery (up to 8 mm) and high pumping velocity increasing the device's application space and mass production potential. Additionally, the device design does not need precise layers of water and glass between substrate and channel, simplifying the design significantly. In this study, we conducted extensive parametric studies to quantify the effects of the liquid volume pumped, microchannel size, input applied power as well as the existence of hydrophobic surface coating on the pumping velocity and pump performance. Our results indicate that the pumping velocity for a constant liquid volume with the same applied input power can be increased by over 130 % (2.31 vs 0.99 mm/min) by employing a hydrophobic surface coating (Cytop) in a thinner microchannel (250 vs 500 µm) design. This device can be used in circulation, dosing, metering and drug delivery applications which necessitates small-scale precise liquid control and delivery.

SAR Analysis for handheld mobile phone using DICOM based voxel model

In this paper, Specific Absorption Rates (SAR) inside the human head and hand have been analyzed for a handheld mobile phone operated at GSM 900 band. Both the head and hand are modeled electrically using Digital Imaging and Communication in Medicine (DICOM) formatted CT Scan voxel data considering the electrical parameters of different internal anatomical structures. Three-dimensional Finite Difference in Time Domain (FDTD) method has been used to simulate SAR induced in the head and hand. Maximum peak 1-g and 10-g SARs of 1.33 W/kg and 0.388 W/kg are found at antenna resonance frequency of 930 MHz for 0.6 W applied input power which are below the limits set by ANSI/IEEE and FCC, respectively.

Electro-thermal analysis of an embedded boron diffused microheater for thruster applications

One of the important design criteria of micropropulsion systems in particular VLM is the type of microheater, its layout and placement with a view to achieve uniform heating of propellant, fast heat transfer efficiency with minimum input power. Thrust produced by microthruster not only depends on the structural geometry of the thruster and propellant flow rate, but also on the chamber temperature to produce super saturated dry stream at the exit nozzle. Detailed design of microheater in thermal and electrical domains using co-solvers available in MEMS software tools along with material’s thermal property, temperature dependence of electrical resistivity and thermal conductivity have been considered in the present work to achieve precise modeling and experimental accuracy of heater operation. The chamber temperature was analytically calculated and subsequently the required resistance and power were estimated. The boron diffused microheaters of meanderline configuration in silicon substrate has been designed and its finite element based electro-thermal modeling was employed to predict the heater characteristics. The variation of microheater temperature with time, applied voltage and along chamber length has been determined from the modeling. Subsequently the designed microheater was realized on silicon wafer by lithography and boron diffusion process and its detailed testing was evaluated. It was found that boron diffused resistor of 820 Ω can generate 405 K temperature with applied input power 2.4 W. Finally the simulated results were validated by experimental data.

초음파 (US)와 다양한 파장범위의 자외선 (UV) 조사에 따른 DEP 분해특성에 관한 연구

Diethyl phthalate (DEP) is widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including various applied power density (10-40 W/L), UV wavelengths (365 nm, 254 nm and 185 nm) and frequencies (283 kHz, 935 kHz) were applied to a DEP contaminated solution. The pseudo-first order degradation rate constants were in the order of <TEX>$10^{-1}$</TEX> to <TEX>$10^{-4}\;min^{-1}$</TEX> depending on the processes. Photolytic and sonophotolytic DEP degradation rate also were high at shortest UV wavelength (VUV) due to the higher energy of photons, higher molar absorption coefficient of DEP and increased hydroxyl radical generation from homolysis of water. Sonolytic DEP degradation rate increased with increase of applied input power and the dominant reaction mechanism of DEP in sonolysis was estimated as hydroxyl radical reaction by the addition of t-BuOH, which is a common hydroxyl radical scavenger. Moreover, synergistic effect of were also observed for sonophotolytic degradation with various UV irradiation.

Generation of ozone by pulsed corona discharge over water surface in hybrid gas–liquid electrical discharge reactor

Ozone formation by a pulse positive corona discharge generated in the gas phase between a planar high voltage electrode made from reticulated vitreous carbon and a water surface with an immersed ground stainless steel plate electrode was investigated under various operating conditions. The effects of gas flow rate (0.5–3 litre min−1), discharge gap spacing (2.5–10 mm), applied input power (2–45 W) and gas composition (oxygen containing argon or nitrogen) on ozone production were determined. Ozone concentration increased with increasing power input and with increasing discharge gap. The production of ozone was significantly affected by the presence of water vapour formed through vaporization of water at the gas–liquid interface by the action of the gas phase discharge. The highest energy efficiency for ozone production was obtained using high voltage pulses of approximately 150 ns duration in Ar/O2 mixtures with the maximum efficiency (energy yield) of 23 g kW h−1 for 40% argon content.