mA Range Research Articles

Exploring GVS as a display modality: signal amplitude and polarity, in various environments, impacts on posture, and with dual-tasking.

Galvanic Vestibular Stimulation (GVS) has been proposed as an alternative display modality to relay information without increasing demands on the visual or auditory sensory modalities of the wearer or in environments where those modalities cannot be used (e.g., covert night operations). We further investigated this concept with four experiments designed to test: (1) thresholds at which subjects could distinguish between different GVS current amplitudes and polarities, (2) thresholds at which different bipolar (i.e., sinusoidal waveform with current oscillating between left and right directions) current frequencies were distinguishable among room temperature, hot, cold, and windy environments, (3) effects of unipolar (i.e., sinusoidal waveform with current occurring in only the left or right direction) currents on balance performance, and (4) dual-task performance among frequency and polarity modulated GVS conditions during a concordant visual search task. Subjects reliably distinguished between current amplitudes that varied from a pedestal of ± 0.6mA by a median of 0.03mA (range of 0.02-0.32mA) and between unipolar currents at a median amplitude of 0.55mA (range of 0.32-0.83mA). GVS frequency thresholds were robust to the environment conditions tested, with no statistical differences found. Sway and balance errors were increased with unipolar currents. GVS thresholds were not impacted by the dual-task paradigm, but the visual search scores were slightly elevated when congruently performing a polarity thresholding task. Overall findings continue to support GVS use as a display modality, but some limitations are noted, such as the use of unipolar currents under scenarios where postural control is important.

Experimental determination of stray currents in parallel operated cells exemplified on alkaline water electrolysis

Avoiding undesired electric field-driven cell-to-cell ion conduction is a common issue in electrochemical bipolar stacks affecting many processes such as alkaline water electrolysis, chlor-alkali electrolysis, and redox flow batteries. In bipolar stack systems, they are known as ionic shunt or stray currents and flow alongside a cell stack through the electrolyte manifolds bypassing the bipolar plates. A similar phenomenon occurs if multiple single cells are operated in parallel with a common electrolyte supply, even though each individual cell is galvanically isolated. If the parallel cells are operated at different voltages, an electrochemical potential gradient is formed across the electrolyte tube manifold, causing stray currents to flow from one cell to the other. It is important to determine and reduce stray currents and its implications to ensure high system efficiency and maximum system lifetime. This work presents a new approach with which stray currents between parallel operated, galvanically isolated electrochemical cells has been determined for the first time. For this purpose, an ionic 4-point measurement was implemented into an experimental setup with two electrolyzer flow cells with a common electrolyte supply using reference electrodes. This approach was used to measure the potential differences ΔE between both electrolyzers exemplarily for alkaline water electrolysis. Combined with the measured ionic resistances of the electrolyte within the polymeric tube manifold, stray currents were accurately determined. The presented results show that the ionic 4-point measurement could be successfully implemented and validated to experimentally determine stray currents between parallelly operated cells. The method presented enabled stray current measurements with high precision in the mA range. Due to the high cell currents and high ionic tube resistance, the stray current is less than 1 % in the introduced electrochemical setup. The demonstrated systematic measurement approach can be easily transferred to other electrochemical systems or processes.

Investigation of the effect of dimensional and non-dimensional parameters on the performance of pitch-varied staggered arranged dimple solar air heaters

In this study, the efficacy of a single pass, single glazed, five different types of absorber plate incorporated solar air heater (SAH) was experimentally examined in outdoor test conditions on alternative days. The experiment was carried out for flat plate solar air heater (FPSAH) and staggered arranged dimple imprinted absorber plate solar air heater (SDPSAH) maintained at four different pitch ratios (Pt/Pl: 1.0, 1.11, 1.25, and 1.67) by varying the air mass flow rate (ma) from 0.01-0.05 kg/s (corresponding Re range: 1971.66–10466.45). The results show that the performance of both FPSAH and SDPSAH improves when the ma increases. For the tested range of ma, SDPSAH outperforms FPSAH regardless of pitch ratio. SDPSAH, with a pitch ratio of 1.25, on the other hand, has a greater air temperature difference, efficiencies, heat removal factor, collector efficiencies, and averaged Nusselt number (Nuavg) while having a lower global heat loss coefficient and top loss. The Nuavg of SDPSAH at a pitch ratio of 1.25 is 1.01–1.17, 1.16–1.24, 1.26–1.57, and 1.44–1.88 times higher than SDPSAH at pitch ratios 1.0, 1.11, 1.67, and FPSAH, respectively. The higher averaged friction factor (favg) of 0.0443 is attained for SDPSAH at a pitch ratio of 1.25 due to the presence of the largest number of dimples. The ηth and ηd of SDPSAH at a pitch ratio of 1.25 are 34.5 and 35.5 % higher than those of FPSAH. The global heat loss coefficient of SDPSAH at pitch ratios 1.11, 1.0, and 1.67 is 1.05–1.84, 1.09–2.15, and 1.11–2.92 times higher, respectively, than that of SDPSAH at a pitch ratio of 1.25.

Two episodes of Early Palaeozoic high-pressure metamorphism in North Balkhash ophiolite zone (Central Kazakhstan, western Central Asian Orogenic Belt): Evidence for tectonic evolution of Junggar–Balkhash Ocean

The structure of serpentinite mélange of the North Balkhash ophiolite zone (Central Kazakhstan; west Central Asian Orogenic Belt) is ascertained to be high-grade formations assigned to epidote-glaucophane eclogites and garnet blueschists, and their varieties. The rocks follow a clockwise ‘subduction-type’ evolution with the estimated near–peak metamorphic conditions of 1.6–1.9 GPa and 500–560 °C. 40Ar39Ar phengite ages of ∼491 Ma and ∼ 465 Ma obtained for the eclogites and garnet blueschists, respectively, are interpreted to reflect the near-peak to shortly retrograde stages of rock evolution and to record the late Cambrian and Middle Ordovician episodes of high-pressure re-equilibration in the North Balkhash zone. Protoliths of the eclogites were N-MORB-like mafic rocks, which comprised structurally different (from the lower gabbroic to the upper dolerite/basalt) parts of pre-late Cambrian oceanic crust and were formed in the spreading centre setting at the expense of depleted mantle source. Protoliths of the garnet blueschists and associated rocks were represented by volcanogenic–sedimentary, predominantly mafic, complexes (tuffaceous sandstones, greywackes), an accumulation of which and subsequent involvement into subduction occurred at ∼478–465 Ma in the intra-oceanic (fore-arc) setting. Zircon core ages indicate formation of the source of the protoliths of the garnet blueschists occurred in the 509–478 Ma range. A comprehensive correlation of the metamorphic and igneous formations of the North Balkhash zone with those assigned to the adjacent complexes of the southern part of the West Junggar area (NW China) suggested their mutual Early Palaeozoic tectonic evolution within the Junggar–Balkhash Ocean.

High contrast at short separation with VLTI/GRAVITY: Bringing Gaia companions to light

Context. Since 2019, GRAVITY has provided direct observations of giant planets and brown dwarfs at separations of down to 95 mas from the host star. Some of these observations have provided the first direct confirmation of companions previously detected by indirect techniques (astrometry and radial velocities). Aims. We want to improve the observing strategy and data reduction in order to lower the inner working angle of GRAVITY in dual-field on-axis mode. We also want to determine the current limitations of the instrument when observing faint companions with separations in the 30–150 mas range. Methods. To improve the inner working angle, we propose a fiber off-pointing strategy during the observations to maximize the ratio of companion-light-to-star-light coupling in the science fiber. We also tested a lower-order model for speckles to decouple the companion light from the star light. We then evaluated the detection limits of GRAVITY using planet injection and retrieval in representative archival data. We compare our results to theoretical expectations. Results. We validate our observing and data-reduction strategy with on-sky observations; first in the context of brown dwarf follow-up on the auxiliary telescopes with HD 984 B, and second with the first confirmation of a substellar candidate around the star Gaia DR3 2728129004119806464. With synthetic companion injection, we demonstrate that the instrument can detect companions down to a contrast of 8 × 10−4 (ΔΚ = 7.7 mag) at a separation of 35 mas, and a contrast of 3 × 10−5 (ΔΚ = 11 mag) at 100 mas from a bright primary (K < 6.5), for 30 min exposure time. Conclusions. With its inner working angle and astrometric precision, GRAVITY has a unique reach in direct observation parameter space. This study demonstrates the promising synergies between GRAVITY and Gaia for the confirmation and characterization of substellar companions.

Detrital zircons and the magmatic history of Viti Levu, Fiji

We integrate the existing detrital zircon data from multiple modern river sediment samples on Viti Levu, Fiji, with the most current available geological and topographic mapping of the respective river drainage basins to compare detrital populations with potential bedrock sources. The temporal and spatial variations in zircon geochemistry supplement what is known from igneous rocks and confirm the petrological differences between plutonic and volcanic rocks from the Eocene to early Oligocene (Yavuna age, >30 Ma), middle Oligocene to middle Miocene (Wainimala age, 30–12.5 Ma), late Miocene (Colo age, 12.5–6.5 Ma) and latest Miocene (Namosi age, 6.5–5 Ma). The >30 Ma Yavuna-age zircons are restricted to areas that drain the previously mapped Yavuna Group. The 30–12.5 Ma zircons are found across central Viti Levu from west to east, and the 30–15 Ma zircons have distinctively low U/Yb and high Dy/Yb ratios. They are the best radiometric evidence of widespread early to middle Miocene arc magmatism in Fiji that was relatively U-poor. Peak deconvolution of the Colo age zircons from individual basins suggests the following ages for undated or poorly dated plutons from central Viti Levu. The large Mavuvu pluton is probably composed of multiple intrusions in the 12–10 Ma range, the Waiqa pluton is probably ca 10 Ma, and the Noikoro pluton is probably ca 9 Ma. There are zircons from unknown plutonic or volcanic sources between 8 and 7 Ma in western Viti Levu that have distinct Eu/Eu* ratios. We attribute the highest U/Yb ratios in some Colo age zircons to crustal anatexis. Namosi-age zircons are abundant in the Medrausucu Group and can be found scattered across Viti Levu.

Rectangular-to-elliptical shape transition intakes with various leading-edge for performance enhancement

This study explores the efficiency of streamline-tracing intake in scramjets within the hypersonic domain, where the Mach number (Ma) exceeds five. Focusing on a rectangular-to-elliptical shape transition intake following Busemann streamlines with a contraction ratio of 4.67, tailored for Ma 7.1, this study innovates beyond traditional design method, employing numerical simulations to interpolate iso-Ma points and shape the leading edge of the intake to enhance the performance. Three distinct leading-edge designs—using a sinusoidal function to closely track all iso-Ma points, a convex second-order polynomial to bolster compression and mass flow, and a concave polynomial to widen the starting envelope—were conceptualized. The research included experiments with 0.06 scaled models for validation and performance assessments of full-scale intakes using three-dimensional viscous simulations. Key performance metrics, such as the pressure ratio, total pressure recovery, mass flow rate, and exit Ma, were evaluated to reveal the capability of all three intake designs to operate effectively over a broad Ma range (3–7). A key finding of this study is the ability to selectively enhance either the compression capability or the total pressure recovery by strategically designing the leading edge of the intake through interpolation methods. This study underscores the importance of using numerical simulation results in the notching process as an effective design strategy to handle a wide range of off-design conditions with fixed geometry and achieve performance improvements in scramjet intakes.

Mantle xenoliths from Komsomolskaya kimberlite pipe, Yakutia: Multistage metasomatism

Minerals from > 200 mantle xenoliths from Komsomolskaya kimberlite pipe were studied by electron microprobe and LA-ICP-MS. They are metasomatised garnet and spinel peridotites containing phlogopite, amphibole and ilmenite with garnets (up to 12.5 wt% Cr2O3) and clinopyroxenes (up to 5 wt% Na2O) or rarer Fe-pyroxenites and A, B, C eclogites.Thermobarometry indicates that the lithospheric mantle beneath the Komsomolskaya pipe is layered. Heated porphyroclastic, deformed peridotites at the lithosphere base (7–6 GPa) are enriched in Fe. The cold group at 6.0–5.5 GPa (34 mW/m2) are depleted peridotites with sub-Ca garnets. Cpx-fertilized varieties belong to the middle part of the mantle section. Amphiboles range from Cr-hornblendes to edenites (2–6 GPa), showing K-Ti enrichment. Picroilmenites yield two pressure intervals from 6.5 to 5.0 GPa and from 5.0 to 4.0 GPa, forming two differentiation branches. Eclogites mainly occur in the lower part of the section with a peak at pressures of 4–6 GPa.Trace elements of melts that formed harzburgitic garnets-pyroxenes refer to oceanic MORB like melt interaction with peridotites. The sub-calcic S-type garnets are similar to subduction-related melts (S-type REE) with troughs in HFSE. Adakite-like hybrid metasomatism formed Na, Al-rich pyroxenes with peaks in Sr and HFSE. K-bearing pyroxenes and amphiboles refer to shoshonitic metasomatism. Trace elements for Cpx of re-fertilized mantle peridotites reveal high LREE, Nb-Ta troughs and peaks in Zr, Th, Sr, U. They are reacted to carbonatite –alkaline melts. Protokimberlite (essentially carbonatitic) interaction produced HFSE-enrichment. Type B eclogites show more subduction-related features with HFSE troughs while type A eclogites are closer to hybrid and peridotitic signatures. We suggest six types of major metasomatic agents. The 40Ar/39Ar ages of phlogopites vary in the 440–690 Ma range, with some at 1.6 Ga, suggesting multistage metasomatism.

Direct numerical simulation of supersonic nanoparticles flow in free-molecule regime using the angular coefficient method

We employ molecular flow methods to numerically simulate the supersonic nanoparticles flow in free-molecule regime. To streamline the computational complexity, interaction forces between the gas and solid particles are disregarded. We first develop a discrete phase model (DPM) method that integrates the non-rigid body collision model, enabling an accurate simulation of nanoparticle diffusion under the influence of the drag force and Brownian motion force. The nanoparticles considered in this study have sizes below 10 nm, and the accuracy of the DPM method is verified by comparing its results with experimental data. Subsequently, we theoretically and numerically investigate the transmission probability and number density of N2 molecules flowing through two-dimensional (2D) channels and three-dimensional (3D) tubes by using the angular coefficient (AC) method and the direct simulation Monte Carlo (DSMC) method. The findings indicate that as the diameter of the nanoparticle (dp) decreases to 1 nm, the diffusion coefficient (D) and the root mean square displacement (x) of nanoparticles approach the N2 molecules. The microscopic velocity of most N2 molecules falls within the range of 62–1400 m/s, and the macroscopic velocity of N2 flow falls within the range of Ma = 1.28–1.35. In contrast to the DSMC method, the AC method exhibits enhanced accuracy even with a reduced number of grids and obviates the process for large-scale sampling. Additionally, the solution time required by the AC method is approximately 1/10 and 1/13–1/32 of the DSMC method in 3D cylindrical tubes and 2D channels, respectively. Moreover, the AC method demonstrates superior adaptability when dealing with complex geometries.

Skin dose estimation in adults undergoing diagnostic chest X-ray examinations at Al-Zahra Teaching Hospital in Wasit Governorate, Iraq

This research intended to calculate skin dose (mgy) was determined in 30 adult patients. The average value of the Tube’s potential kVp range from 72 kVp To 100 (kVp) is 9.646±1.76 kVp. The average value of the SSD (cm) range from 100 cm to 180 cm is 22.558±4.118 cm, and the average value of the Tube load (mAs) range from 3 MAs to 16 MAs is 3.727±0.680. Additionally, the SKIN DOSE was from 0.06 mGY to 0.57 mGY, with an average of 0.120 mGY. It was found that the dose results were within the prescribed range of 0.4 mGy; this is recommended by international organizations that protect against radiation. Except for a few instances, the frequency of quality assurance (QA) and quality control (QC) was higher. As a result, the skin dose to patients who have chest exams at Al-Zahra Teaching Hospital in Wasit Province was equivalent to the Global standard.

Mineralogical constraints on pegmatite genesis and rare metal mineralization in the Mufushan batholith, South China

Pegmatites are commonly associated with or strongly influenced by the crystallization of magmatic volatile phases (MVP) as ascending magmas undergo differentiation. The mechanism of fractional crystallization, liquid immiscibility, and water–rock interactions that influence the rare metals concentration in pegmatites are still unclear. We analyzed the mineralogy (incl. monazite, garnet, zircon, and muscovite) from pegmatites to unravel the timing and magmatic-hydrothermal processes for the giant Renli-Chuanziyuan pegmatite Li-Nb-Ta mineralization in the Mufushan region (South China). Five types of pegmatites have been identified at Mufushan, i.e., those containing mainly orthoclase (O-pegmatite), microcline (M-pegmatite), albite-orthoclase (AO-pegmatite), microcline-albite (MA-pegmatite), and spodumene-albite (S-pegmatite).Monazites from the Renli high-Th Li-mica pegmatite exhibit magmatic affinity. The ∼140 Ma age of monazite U-Pb suggests a temporal relationship between the Li-rich pegmatite and its muscovite granite host. Garnet from these pegmatites is magmatic and belongs to the almandine-spessartite series, and contains feldspar and apatite inclusions. Continuous fractional crystallization likely controlled the pegmatite development, as the garnet spessartite content increases with distance from the Mufushan batholith. Garnet in the spodumene-albite pegmatites has very low REE content, and it represents a late stage of crystallization related to magmatic-hydrothermal fluids. Compositional variation in muscovite from all of the pegmatites is negligible. The K/Rb ratio (a proxy for the degree of fractionation) increases gradually from the O- to S-pegmatite, whilst the muscovite F content correlates positively with the degree of magma fractionation. The transformation of muscovite to lepidolite in pegmatites can occur through magmatic-hydrothermal crystallization or metasomatism. Zircon in pegmatites generally occurs as metasomatic remnants, with uneven zoning shown in cathodoluminescence (CL) images. Hydrothermal zircon U-Pb ages are concentrated in the 140–134 Ma range, consistent with the garnet leucogranite ages. This suggests that pegamtites and the garnet leucogranite were formed in the same magmatic-hydrothermal activity. The accumulated MVP and incompatible elements may have migrated from deeper, more crystal-rich zones under medium degree of fractionation. The MVP may contain abundant dissolved melt components as single-phase hydrous silicate liquids, forming typical quartz-/feldspar-dominated pegmatite and the diversity of rare-metal deposits.

Spectrum Modelling as a Method for Temperature Correction of Organic Light Emitting Diodes Based on Three-Component Structures

OLED technology is widely used in various displays, which operate in a wide range of temperatures. For such devices, it is necessary to maintain the luminance and chromaticity coordinates at the given level when the external temperature changes. In this work, a program was developed that, based on the electro-physical characteristics and electroluminescence spectra of a white OLED sample at different temperatures and currents, as well as the spectral characteristics of the coloured filters, allows for selection of currents in the range of (1–25) mA, applied to each subpixel in such a way as to converge the chromaticity coordinates to the specified values. Various chromaticity coordinates were tested in the process of program execution, including CIE sources of type A, type B, type C, and type D65. In each of these cases, the program significantly reduced the difference in chromaticity coordinate changes with temperature. The obtained results will be used for gamma correction of micro-displays produced at the Cyclone Research Institute during their operation at a wide range of temperatures.

Experimental study on the characteristics of a novel aerodynamic wake width flameholder

In this study, a novel flameholder named aerodynamic wake width flameholder (AWF) was proposed. The AWF optimized the sidewall profile of conventional bluff body flameholders and widened the downstream recirculation zone through aerodynamic force, while maintaining the same trailing edge width as conventional flameholders. Consequently, the combustion properties were impacted. To investigate the flow field structure, flame stability limits, and flame evolution of the novel flameholder, an aerodynamic wake width evaporating flame holder (AWEF) was designed and compared with a normal evaporating flameholder (EF). Comparative analysis of the downstream flow field structure revealed that the AWEF exhibited a wider zero-velocity contour and a higher reflux rate. Furthermore, the AWEF demonstrated a larger velocity gradient near the trailing edge, indicating the presence of a thicker shear layer. Within the inlet Ma range of 0.1 to 0.17, the AWEF exhibited wider flame stability limits compared to the EF. The ignition fuel-air ratio (FAR) of the AWEF remained relatively constant within this range, suggesting that the novel flameholder could withstand the deterioration of ignition performance caused by an increase in the inlet Ma. Moreover, the AWEF achieved a larger flame projection area and flame width downstream compared to the EF. Finally, by combining the flow field characteristics and flame stability properties of the AWEF, the mechanisms underlying the changes in flame stability characteristics were analyzed. The results of this study can serve as valuable references for enhancing flame stability in current and future advanced augmentor systems.

Ultra-low-dose CT for attenuation correction: dose savings and effect on PET quantification for protocols with and without tin filter

BackgroundUltra-low-dose (ULD) computed tomography (CT) scans should be used when CT is performed only for attenuation correction (AC) of positron emission tomography (PET) data. A tin filter can be used in addition to the standard aluminium bowtie filter to reduce CT radiation dose to patients. The aim was to determine how low CT doses can be, when utilised for PET AC, with and without the tin filter, whilst providing adequate PET quantification.MethodsA water-filled NEMA image quality phantom was imaged in three configurations with 18F-FDG: (1) water only (0HU); (2) with cylindrical insert containing homogenous mix of sand, flour and water (SFW, approximately 475HU); (3) with cylindrical insert containing sand (approximately 1100HU). Each underwent one-bed-position (26.3 cm) PET-CT comprising 1 PET and 13 CT acquisitions. CT acquisitions with tube current modulation were performed at 120 kV/50 mAs-ref (reference standard), 100 kV/7 mAs-ref (standard ULDCT for PET AC protocol), Sn140kV (mAs range 7–50-ref) and Sn100kV (mAs range 12–400-ref). PET data were reconstructed with μ-maps provided by each CT dataset, and PET activity concentration measured in each reconstruction. Differences in CT dose length product (DLP) and PET quantification were determined relative to the reference standard.ResultsAt each tube voltage, changes in PET quantification were greater with increasing density and reducing mAs. Compared with the reference standard, differences in PET quantification for the standard ULDCT protocol for the three phantoms were ≤ 1.7%, with the water phantom providing a DLP of 7mGy.cm. With tin filter at Sn100kV, differences in PET quantification were negligible (≤ 1.2%) for all phantoms down to 50mAs-ref, proving a DLP of 2.8mGy.cm, at 60% dose reduction compared with standard ULDCT protocol. Below 50mAs-ref, differences in PET quantification were > 2% for at least one phantom (2.3% at 25mAs-ref in SFW; 6.4% at 12mAs-ref in sand). At Sn140kV/7mAs-ref, quantification differences were ≤ 0.6% in water, giving 3.8mGy.cm DLP, but increased to > 2% at bone-equivalent densities.ConclusionsCT protocols for PET AC can provide ultra-low doses with adequate PET quantification. The tin filter can allow 60–87% lower dose than the standard ULDCT protocol for PET AC, depending on tissue density and accepted change in PET quantification.

Intraoperative nerve stimulation during vagal nerve stimulator placement.

Vagal nerve stimulation (VNS) is a palliative treatment for refractory epilepsy and intraoperative nerve stimulation is applied to the vagal and other nerves to prevent electrode misplacement. We evaluated these thresholds to establish intraoperative monitoring procedures for VNS surgery. Forty-six patients who underwent intraoperative nerve stimulation during VNS placement were enrolled. The vagal nerve and other exposed nerves were electrically stimulated during surgery, and muscle contraction was confirmed by electromyography of the vocal cords and visual recognition of cervical muscle contraction. The nerve thresholds and the most sensitive parts of the vagal nerve were analyzed retrospectively. The stimulation of vagal nerves induced vocal cord responses in all 46 patients; the median thresholds of the most sensitive parts and all parts were 0.2 mA (range: 0.05-0.75 mA) and 0.25 mA (range: 0.15-1.5 mA), respectively. The medial middle region was identified as the most sensitive part of the vagal nerve in the majority of participants (82.5%). In 11 patients, other cervical nerves were stimulated and sternohyoid muscle contraction was induced with a median threshold of 0.35 mA (range: 0.1-0.7 mA) in eight patients, while sternocleidomastoid muscle contraction was induced with a median threshold of 0.2 mA (range: 0.1-0.2 mA) in three. Intraoperative stimulation of vagal nerves induces vocal cord responses with locational variations, and the middle part stimulation could minimize the stimulus intensities. The nerves innervating the sternohyoid and sternocleidomastoid muscles may be exposed during the procedure. Knowledge of these characteristics will enhance the effectiveness of this technique in future applications.

Flow pattern diagram of compressible non-equilibrium gas flow around a circular cylinder

An investigation into the non-equilibrium gas flow around a circular cylinder within the Knudsen number (Kn) range of 0.001–1 and the free-stream Mach number (Ma) range of 0.01–6 is presented using the unstructured grid unified gas kinetic scheme. The primary objective is to examine the impact of Kn and Ma on flow patterns. The flow pattern diagram illustrating seven flow patterns in the Ma-Kn space is provided, including the transition boundary between bow shock-wave with laminar flow (BS+L) and bow shock-wave with vortex flow (BS+V). The relationships between Re-Kn and Ma-Re both follow the power function: y=eβxα, where α and β are constants. The study also provides a more precise critical curve of vortex shedding in subsonic inflow, the boundary of tailing shock-wave, and the boundary of vortex shedding in a transonic inflow. The flow pattern diagram indicates that the variation of flow separation with Kn is non-monotonic across the entire Ma range but is monotonic at Ma>1. In the subsonic inflow, the critical Re of flow separation (Rec) increases with Ma, while Rec initially increases and then decreases with Kn. The critical Ma at the turning point is about 0.72. In supersonic inflow, the critical Re associated with the onset of flow separation either increases or decreases with the increase in Ma or Kn. The critical Re of vortex shedding is non-monotonic with Kn. The critical Re of the trailing shock-wave decreases with both Kn and Ma. In the transonic inflow, the critical Re and critical Ma of vortex shedding decrease with Kn. As rarefaction increases, the type of flow patterns decreases. The flow pattern diagram provides a visual representation of the impact of rarefaction and compressibility effects on flow pattern transitions and assists in determining the applicable range of the drag coefficient model.

A Low Power Low Inrush Current LDO with Different Techniques for PSR and Stability Improvement

One of the most popular power management regulators is the low drop-out voltage regulator (LDO). LDOs have different specifications such as the power supply rejection (PSR) over different frequencies, stability over different load ranges, inrush current spike flows through the input supply, and power consumption. In this work, we present a low power low inrush current LDO design with different techniques for PSR and stability improvement across different frequencies. The LDO presented in this work is a low-power and small area LDO but achieves a high PSR over a wide range of frequencies. The LDO is designed in 65 nm CMOS technology and achieves a PSR better than 80 dB up to 30 MHz for an output load current of 25 mA using an output load capacitor of 4 µF. The design can be used in capless/capped LDOs with wide load current ranges as high as 200 mA and load capacitor range from 1 nF to 12 µF with inrush current improvement by more than 2×. The presented LDO consumes a zero-load quiescent current of 10 µA and its area of 180 µm × 180 µm.

Optimization of Doping Concentration to Obtain High Internal Quantum Efficiency and Wavelength Stability in An InGaN/GaN Blue Light-Emitting Diode

We conduct a comprehensive study to investigate the feasibility of achieving high internal quantum efficiency (IQE) and wavelength stability in an InGaN/GaN blue light-emitting diode (LED) through numerical simulations with different doping concentrations. To ensure accurate calculations, we emulated the structure of an LED, fabricated on freestanding GaN with low defect density, abrupt interfaces, and high-performing characteristics, which resemble ideal conditions. Our objective is to determine the optimal doping concentration of the claddings using the Quantum Drift-Diffusion (QDD) model. We tested three concentrations ( ), and found that produced the highest IQE of 82.5%, the most stable wavelength in the range of (0.08–63.25) mA, an optical power of mWs−1, and a forward voltage of V at 20 mA. We suggest that using this concentration leads to the parameters closest to those of the reference device.

Interface engineered nanostructured phase formation at Se/In sites by Ag ion irradiation and its structural, optical and morphological behavior

Thermally evaporated Se/In bilayer films were irradiated by 120 MeV Ag ion at different fluences. Energy-dispersive X-ray fluorescence (EDXRF) spectra of the films showed the 1:2 ratio concentration of In and Se. After six months of preserving the films under ambient condition, four phases: In2Se3, In4Se3, In and Se developed in the films as revealed by Grazing incidence X-ray diffraction (GIXRD) study. The In4Se3 and In were completely insensitive to the irradiation while the other two phases (In2Se3 and Se) were completely amorphized at high ion fluences. The Poission fitting of the fluence dependence area under X-ray diffraction (XRD) peaks showed the radius of amorphized latent tracks along the path of 120 MeV Ag ions in In2Se3 and Se as 8.4 nm and 9.5 nm respectively. The lattice fringe images of High-resolution transmission electron microscopy (HRTEM) showed the presence of the four phases as observed by GIXRD study. The UV-visible study revealed the band gap reduction at the low fluence region from pristine to 3 × 1011ions cm−2 and increased at high fluence from 1 × 1012 ions cm-2 to 1 × 1013 ions cm-2. This variation of band gap may be due to the formation of localized states and annealing effect due to ion irradiation. Field emission scanning electron microscopy (FESEM) images showed the nano needle shaped structure formation at 1 × 1012 ions cm−2 which increased with ion fluences. The appearance of needle shaped structures may be due to the In2Se3 phase. The I-V study showed the excellent current response in mA range which enables the films for various electrical applications. The surface wettability study showed the hydrophobicity nature of the films which enables it for application in different coating materials.

Closed-loop parameter optimization for patient-specific phrenic nerve stimulation.

Ventilator-induced diaphragm dysfunction occurs rapidly following the onset of mechanical ventilation and has significant clinical consequences. Phrenic nerve stimulation has shown promise in maintaining diaphragm function by inducing diaphragm contractions. Non-invasive stimulation is an attractive option as it minimizes the procedural risks associated with invasive approaches. However, this method is limited by sensitivity to electrode position and inter-individual variability in stimulation thresholds. This makes clinical application challenging due to potentially time-consuming calibration processes to achieve reliable stimulation. We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. A closed-loop system recorded the respiratory flow produced by stimulation and automatically adjusted the electrode position and stimulation amplitude based on the respiratory response. By iterating over electrodes, the optimal electrode was selected. A binary search method over stimulation amplitudes was then employed to determine an individualized stimulation threshold. Pulse trains above this threshold were delivered to produce diaphragm contraction. Nine healthy volunteers were recruited. Mean threshold stimulation amplitude was 36.17 ± 14.34 mA (range 19.38-59.06 mA). The threshold amplitude for reliable nerve capture was moderately correlated with BMI (Pearson's r = 0.66, p = 0.049). Repeating threshold measurements within subjects demonstrated low intra-subject variability of 2.15 ± 1.61 mA between maximum and minimum thresholds on repeated trials. Bilateral stimulation with individually optimized parameters generated reliable diaphragm contraction, resulting in significant inhaled volumes following stimulation. We demonstrate the feasibility of a system for automatic optimization of electrode position and stimulation parameters using a closed-loop system. This opens the possibility of easily deployable individualized stimulation in the intensive care setting to reduce ventilator-induced diaphragm dysfunction.