AC Parameters Research Articles

Unveiling the influence of temperature and interface traps on the performance of source-all-around vertical TFET

This study investigates the electrical performance of a line-tunneling based source-all-around vertical Tunnel Field-Effect Transistor (SAA-VTFET) under diverse temperature and trap charge conditions. The proposed device achieves remarkable performance improvements across DC and AC parameters by employing strategically engineered III-V semiconductors and a wide source-channel tunneling heterojunction. Key metrics like on-state current (ION = 6.35 × 10−5 A/μm), off-state current (IOFF = 3.17 × 10−17 A/μm), threshold voltage (VT = ⁓0.18V), subthreshold swing (SSavg = ⁓7 mV/dec), transconductance (gm = 0.16 mS), cut-off frequency (fc = ⁓0.42 THz), gain bandwidth product (GBP), delay (τ), and various capacitances are thoroughly analyzed. Sentaurus TCAD 3D simulations employed in this study demonstrate the promising future of SAA-VTFETs in low-power and high-speed electronics.

Assessing Indoor Environmental Quality of Academic Building Using Subjective Measurement

Indoor Environment Quality (IEQ) is becoming increasingly popular as a means of assessing human comfort, especially in educational environments. Determining an appropriate degree of indoor environment quality (IEQ) involves considering many factors like thermal comfort, indoor air quality, acoustic comfort, and visual comfort. These days, there is an intense need for educational facilities to have high-quality interior environments by reason of the fear of a worldwide pandemic. This research looks into IEQ characteristics in several standard functional locations of a Navsari academic building. In order to assess the level of user satisfaction in the staff room, drawing hall, and classroom, a sequence of questionnaires measuring the subjective aspects of the IEQ parameters (TC, AC, IAQ, and LC) were utilized. According to the study’s findings, the summer months had the lowest proportion of TC parameter satisfaction overall and the highest percentage of AC parameter satisfaction. Additionally, the data demonstrates that the satisfaction rate is lower for the LC and IAQ parameters. The research has confirmed that the academic building has low IEQ and It is necessary to take the required steps to turn out a more pleasant, conducive, and productive education place.

Electrical investigation and enhancement of optical, structural, and dielectric properties of flexible PVDF/LiZnVO4 nanocomposites

Thin polymeric films of poly(vinylidene fluoride) (PVDF) containing variable mass fractions of nanoparticles (LiZnVO4) were successfully synthesized via the ordinary solution casting method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and ultraviolet–visible spectroscopy were used to explore the role of LiZnVO4 on the structural and optical characteristics of synthesized nanocomposites. In addition, dielectric permittivity (ε' and ε") and dielectric modulus (M' and M") were investigated. The XRD spectral data reveals the crystalline nature of pure LiZnVO4 with rhombohedral structure with an average size of 83 nm calculated using the Scherrer’s equation and W-L plot. The interaction between PVDF and LiZnVO4 was approved through the shift in characteristics in some IR bands. The decrease in band gap energies with increasing LiZnVO4 was attributed to the change of density in the localized states within the PVDF matrix. The effect of both frequency and temperature on the AC parameters was also investigated. Both ε' and ε" had their maximum values at low frequencies and decreased as the frequency and temperature increased. The results from XRD and FT-IR were correlated with changes in the dielectric characteristics at the maximum level value of LiZnVO4, suggesting the potential of these materials as basic components for lithium-ion batteries.

Diagnostic Performance of Quantitative Ultrasound Parameters in Non-alcoholic Fatty Liver Disease

Marked liver steatosis, steatohepatitis, and significant fibrosis are risk factors for unfavorable outcomes in non-alcoholic fatty liver disease (NAFLD). In this study, the diagnostic performance ofattenuation coefficient(AC), liver stiffness(LS), and dispersion slope (DS) was evaluated separately and combined in the diagnosis of liver steatosis and fibrosis in NAFLD suspects using biopsy or magnetic resonance imaging (MRI) as a reference standard. Seventy-four NAFLD suspects were prospectively imaged with an Aplio i800 ultrasound scanner (Canon Medical Systems, Tustin, CA). AC, LS, and DS measurements were obtained from the right liver lobe. Thirty-four patients underwent liver biopsy, and 40 had MRI. There were 32 patients (43%) with liver steatosis and fibrosis (S+F), 22(30%) with steatosis (S), 5 (7%) with fibrosis (F), and 15 (20%) with normal liver (N). Mean ACs were significantly higher in steatotic livers (n=54) than in non-steatotic livers (n=20) (P<0.0001). LS and DS were significantly higher in patients with liver fibrosis (n=37) compared tonon-fibrotic livers (n=37) (P=0.0004 and P=0.0002, respectively). In detecting (S+F), the area under the receiver operating characteristic curve (AUROCC) was 0.87 for combined ultrasound parameters of LS and AC (negative predictive value [NPV]: 75%, positive predictive value [PPV]: 77%, P<0.0001). In detecting patients with liver steatosis and fibrosis stage ≥2, LS had an AUROCC of 0.93 (NPV: 87%, PPV: 82%, P<0.0001). In the biopsy group, 32% (11/34) were diagnosed with non-alcoholic steatohepatitis (NASH). DS values showed a significant difference among patients with (n=23) or without (n=11) hepatocellular ballooning (P=0.02). AUROCC was 0.87 for combined ultrasound parameters of AC, LS, and DS with body mass index (BMI) in detecting NASH (NPV: 80%, PPV: 87%, P=0.0006). AC and LS showed high diagnostic value in detecting liver steatosis and fibrosis, respectively. The combined AC and LS values further improved the diagnostic accuracy in detecting NAFLD and high-risk NAFLD patients.

Selection of the Parameters of Reactive Power Compensation and Harmonic Filtering Devices for an HVDC Transmission System Based on Voltage Source Converters

This article describes a method for selecting the parameters of AC and DC filters for a multi-terminal HVDC transmission system based on voltage source converters (VSC-HVDC). The equivalent circuit model of a multi-terminal VSC-HVDC system with the parameters ±500 kV and 500 MW was developed in the Matlab Simulink software package and presented in d-q coordinate axes. The system voltage source converters in the model were controlled using a three-level pulse-width modulation (PWM) to reduce the level of current and voltage higher harmonic components and decrease the capacity of AC and DC filters. To select the most efficient filter for use as part of a multi-terminal VSC-HVDC system, high-pass filters (HPF) and low-pass filters (LPF) were considered.

TCAD Modeling of GaN HEMT Output Admittance Dispersion through Trap Rate Equation Green’s Functions

We present a novel and numerically efficient approach to analyse the sensitivity of AC parameters to variations of traps in GaN HEMTs. The approach exploits an in-house TCAD simulator implementing the drift-diffusion model self-consistently coupled with trap rate equations, solved in dynamic conditions with the Harmonic Balance algorithm. The capability of the model is demonstrated studying the low-frequency dispersion of a 150 nm gate-length AlGaN/GaN HEMT output admittance YDD as a function of the trap energy of Fe-induced buffer traps. The real part of YDD exhibits strong frequency dispersion and an important degradation of the output resistance at high frequency. The imaginary part is characterized by a peak at a frequency decreasing with trap energy deeper in the gap, in agreement with experimental data on similar structures. Distributed local sources show that YDD is most sensitive to trap energy variations localized in the buffer region under the gate, peaking under the unsaturated portion of channel towards the source. Trap variations affect the output admittance when localized in depth into the buffer up to a 100 nm distance from the channel.

Experimental Investigations on Heat Transfer Deterioration for Vertical Flow of Supercritical Carbon-Dioxide Under Natural Circulation

Abstract Many upcoming designs of nuclear reactors conceptualize use of supercritical fluids (SCFs) due to certain associated advantages. Supercritical helium (SC-He), supercritical carbon-dioxide (SC-CO2), and supercritical water (SCW) find proposed applications in primary/secondary heat removal cycles in nuclear reactors. The knowledge of heat transfer characteristics of the working fluid is essential prerequisite for its actual application. Similarly, for SCF, heat transfer deterioration (HTD) is an area having much ambiguity and thus has attracted many researchers in the recent past. Still, conclusive guidelines for design applications of SCF are lacking due to dramatic variation of thermos-physical properties of SCF in the pseudo-critical region. In this paper, extensive experimental investigations are undertaken to study HTD of SC-CO2 under natural circulation (NC) system. Experiments conducted at pressures between 7.9 and 12.31 MPa for vertical heater horizontal cooler (VHHC) and vertical heater vertical cooler (VHVC) are reported. Effect of heat flux, operating pressure, and cooler orientation are discussed based on the experimental data generated. Methodologies available in literature for identification of HTD are also examined with the present experimental data. The experimental data are compared with the HTD criteria available in literature and a new criterion for onset of HTD is proposed for vertical flows under natural circulation. Role of buoyancy (Bu) and acceleration (Ac) parameters are also investigated. Noticeable HTD is observed for Bu &amp;gt; 3 × 10−6 whereas Ac is not found to affect the HTD in this study.

Modeling and Design of a Novel 5-DOF AC–DC Hybrid Magnetic Bearing

This paper investigates a novel integrated AC–DC hybrid magnetic bearing (HMB) to reduce the volume, weight, manufacturing, and operation cost of magnetic suspension motors. Two radial MBs and an axial MB are integrated with the proposed HMB. The five-degree-of-freedom (5-DOF) suspension is realized in one unit. Two axially polarized permanent magnets provide the radial and axial bias fluxes. First, the HMB structure and the suspension mechanism are introduced. Second, based on the method of equivalent magnetic circuits, magnetic circuits are calculated. The mathematical models of suspension force are discussed. Third, the main parameters of the 5-DOF AC–DC HMB are given. The 3D finite element method (FEM) is adopted to analyze the proposed system’s electromagnetic characteristics, and the suspension mechanism of the 5-DOF is verified. The radial suspension forces versus the radial control current, the axial suspension forces versus the axial control current, the relationship between the axial suspension force and the axial control current with the X direction offset, and the relationship between the radial suspension force in the X direction and the axial control current with the Z direction offset are calculated. Based on the research results, it is shown that the HMB structure is compact and reasonable, and the mathematical models and suspension mechanism are correct.

Phenolic and colour characteristics of must and wine obtained from red grapes treated by pulsed electric fields. Efficacy of PEF to reduce maceration time in elaboration of red wines

Pulsed electric fields effect was studied on the physico-chemical and general phenolic composition as colour characteristics and stilbene content in must and wine. For this purpose, a continuous pulsed electric fields equipment was used to treat three red grape varieties of DOCa Rioja. Graciano, Tempranillo and Grenache wines from these grapes were elaborated with different maceration times, 2 days in the untreated sample (control) and the PEF-treated sample (PEF), and normal maceration time in another untreated sample (control-NM). Parameters as colour intensity, anthocyanin content, total polyphenol index and tannin content showed no differences between the PEF sample with 2 days of maceration and the control-NM sample, except in the case of Tempranillo wines. Total stilbenes, trans-resveratrol and trans-piceid of Graciano wines elaborated from PEF samples showed a higher concentration than the control wines. Alternatively, PEF wines and control-NM wines showed no differences between them. Tempranillo variety wines presented no differences between the three types of samples. In the Grenache variety, only trans-piceid levels showed differences between control and PEF wines. Moreover, relationship between must and wine characteristics was evaluated and compared between different samples. The trend lines obtained for the CI, TPI and AC parameters for samples of Graciano, Tempranillo and Garnacha indicate that the initial content of compounds extracted significantly affected the days of maceration necessary to obtain the appropriate wine. The results obtained increase the knowledge of pulsed electric fields as a technology available for use in the winery to elaborate red wines with reduced maceration time.

Effect of Particle Trap on Motion Characteristics of Metal Particles in AC GILs and Parameter Optimization

Metal particle contamination is an important reason for insulation failure of gas-insulated transmission lines (GILs). Particle trap is the common method for particle suppression. At present, research on the motion characteristics of metal particles near a particle trap and the optimization of trap parameters under AC voltage is insufficient. Based on that, firstly, a dynamic model of metal particles under AC voltage was established, and the motion characteristics of particles in front of the trap were studied, combined with experiments. Then, the influence of trap parameters on the capture effect was analyzed, and the optimization of the trap was realized by simulation. The results showed that, under AC voltage, the randomness of metal particle movement was strong, and the activity was low. The particles mainly moved away from the trap. Among the particles moving towards the trap, some stayed in front of the trap, and some fell into the trap from above. The thickness and height of the trap were the key parameters affecting the capture effect, and with the increase in height and thickness, the capture rate showed a trend of increasing first and then decreasing. The above conclusions can provide a reference for the optimization of a metal particle trap under AC voltage in engineering.

Diminish Short Channel Effects on Cylindrical GAA Hetero-gate Dielectric TFET using High-Density Delta

The examined work elucidates a novel concept on Gate All Around (GAA) hetero dielectric gate-cylindrical tunnel field-effect transistor (TFET) to reduce SCEs. In this paper, a hetero dielectric gate (HeG) integrated with Silicon-Germanium (Si-Ge) substrate material is proposed along with a novel placement of a high-density delta (HDD) layer across the source–channel junction to achieve high ION of 1.12 × 10−4 A/µm and robust IOFF of 9.7 × 10−17 A/µm at Vgs = 1.2 V with steepest subthreshold swing (SS) of 55 mV/decade. Designing and computation of the proffered structure have been done with the computer-aided design (TCAD) 3D device computation software. The systematic investigation in terms of AC and DC parameters, such as ON-current, OFF-current, Miller Capacitances (Gate-Drain Capacitance (Cgd)) and Gate-Source Capacitance (Cgs), are examined. Hetero-gate dielectric Cyl-TFET with high-density delta (HDD) is superior to other conventional structures. The result outcomes included a trap analysis while incorporating the hot charge carriers inside the oxide for improved device reliability. Furthermore, a low Cgd of 58fF and high Cgs of 6.6fF at Vds = 0.3 V have been achieved.

Influence of DC transmission distance on MMC-HVDC stability under weak AC system

The oscillation problem of MMC-HVDC under weak AC system poses a potential threat to the safe and stable operation of power grid, which is related to both of the AC and DC parameters. By comparing the stability of MMC-HVDC under different AC system strength with different DC transmission distance, it is found that when the AC system strength is too weak, there is a risk of instability under the condition of long DC transmission distance, and the correctness of this conclusion is verified by time-domain simulation. Later, the mechanism analysis of this phenomenon is carried out, the result shows that it is related to the interaction of MMC subsystems when the strength of AC system decreases.

Dynamic Identification of Equivalent Parameters of Mathematical Models of Power Electrical Equipment of Electromechanical Power Systems

The article describes a method for dynamic identification of AC and DC hybrid power network parameters. The inaccuracy of the parameters of the electromechanical transient simulation model of the power system has caused the obvious difference between the simulation results and the actual measurement, which has restricted its online application. Over the years, the dynamic parameter identification technology based on field test and test has made great progress, but it is far from satisfactory and accurate. There is still a long research journey for the requirements of performance. The online identification method based on the actual dynamic parameters of the power system is a way to solve the problem. The article includes the main microprocessor modules for system parametric identification of load (SIP L) and an overhead power transmission line (SIP TL). The article will analyze the active electrical network and passive electrical network

Evaluacija komandnog panela sistema klimatizacije u putničkim automobilima

The HVAC control panels of a sample of 10 passenger cars were investigated and evaluated in terms of the type and layout of the controls. The evaluation method of the layout for the same task execution is based on Keystroke Level Model (KLM). According to this method, the results in the manual adjustment of the AC parameters with rotary knobs were better than in the panel with the push buttons, for the same function. The automatic AC control significantly reduces the time and number of actions, thus reducing the driver's workload for the HVAC setting. However, the automatic operation could not provide preferable thermal conditions under some conditions or because of individual preferences, making a manual readjustment necessary

Simplify the resolve of AC parameters such as immittances, conductivity and dielectric by using the delay-time measurement

Our novelty for the presented work is to find a simple method to study electric and dielectric properties for samples such as magnetic materials. We focus on prepare and characterize of the ferrites. During the AC measurements, we struggled to use the Lissajous figure. In addition, we have a shortage of equipment for measurements. This prompted us to look for a method to be easy to use with simple devices. The Delay-Time measurement method for any two different sinusoidal waves was used to calculate the phase shift ( ) between them using an oscilloscope. The was exercised to resolve the series and the parallel of RC in AC circuit. The phasor diagram of the series and the parallel of RC in AC circuit were plotted. All the main and derived quantities of the AC circuit were calculated, such as the immittances, conductivity and dielectric parameters. The presented method is considered as a simple method comparing to other methods. Thus, it can be replaced the other methods as well as it can be used from the scientists and engineers. Our Master students already used this method and they got good results. This paper is considered to be a preliminary analysis for this simple method and we will develop it. Copyright © 2017 VBRI Press.

Inulin-Based Polymeric Micelles Functionalized with Ocular Permeation Enhancers: Improvement of Dexamethasone Permeation/Penetration through Bovine Corneas.

Ophthalmic drug delivery is still a challenge due to the protective barriers of the eye. A common strategy to promote drug absorption is the use of ocular permeation enhancers, while an innovative approach is the use of polymeric micelles. In the present work, the two mentioned approaches were coupled by conjugating ocular permeation enhancers (PEG2000, carnitine, creatine, taurine) to an inulin-based co-polymer (INU-EDA-RA) in order to obtain self-assembling biopolymers with permeation enhancer properties for the hydrophobic drug dexamethasone (DEX). Inulin derivatives were properly synthetized, were found to expose about 2% mol/mol of enhancer molecules in the side chain, and resulted able to self-assemble at various concentrations by varying the pH and the ionic strength of the medium. Moreover, the ability of polymeric micelles to load dexamethasone was demonstrated, and size, mucoadhesiveness, and cytocompatibility against HCE cells were evaluated. Furthermore, the efficacy of the permeation enhancer was evaluated by ex vivo permeation studies to determine the performance of the used enhancers, which resulted in PEG2000 > CAR > TAU > CRE, while entrapment ability studies resulted in CAR > TAU > PEG2000 > CRE, both for fluorescent-labelled and DEX-loaded micelles. Finally, an increase in terms of calculated Kp and Ac parameters was demonstrated, compared with the values calculated for DEX suspension.

Discussion on AC Corrosion Rate Assessment and Mechanism for Cathodically Protected Pipelines

Although a lot of AC corrosion failure cases and research work on cathodically protected pipelines have been reported, the mechanism of the AC corrosion process has not been completely understood, and there still exist many debates on AC corrosion assessment criteria under cathodic protection (CP), especially under a high CP level. AC corrosion simulation experiments in three kinds of environments were conducted to study the AC corrosion behavior under different conditions. Based on the AC corrosion rates and the corresponding AC current densities, DC IR-free potentials, and DC current densities, the AC corrosion rate assessment diagrams were presented and the threshold values for AC and DC parameters corresponding to certain corrosion rates were determined in three studied environments. Besides, the AC corrosion morphologies, products, local environment parameters, and electrochemical characteristics were measured and analyzed under the combined effects of AC and CP. The effect of hydrogen evolution reaction on the AC corrosion process under a high CP level was discussed based on the electrical equivalent circuit model at the steel/electrolyte interface, the dynamic electrochemical reaction process, and the change of local environment close to the specimen surface.

Virtual instrument for estimation of HVAC and HVDC test parameters according to IEC 60060-1:2010

High and ultra high voltage tests are commonly carried out to determine external and internal dielectric performances of electric power equipment. The standardization of these tests in different laboratories is obtained by following the standards with the requirements necessary to perform the tests. Among such requirements, the test voltage parameters must be measured within acceptable uncertainties. For a correct analysis of the test and presentation of the results it is necessary that the measuring system and the instrument used be able to estimate all parameters according to standard IEC 60060-1:2010, depending on each type of voltage and test, AC, DC or impulse. However, simpler conventional instruments, such as multimeters, are not capable of measuring and indicating all parameters required by current standards. Thus, dedicated instruments and software are needed, capable of performing the analysis of these parameters within the acceptable uncertainty limits. The use of software or measurement algorithms for voltage impulse testing is already described in IEC 61083-1 and -2 standards. Specifically, part 2 presents the reference waveforms used for the validation of the software used in the tests. Similarly, IEC 61083-4 is being developed for high voltage AC and DC tests, with standard waveforms for validation of the measurement software. The objective of this work is presenting the HVAT AC-DC virtual instrument developed in LabVIEW environment, capable of estimating the required AC and DC test parameters of the ABNT NBR IEC 60060-1:2013 standard and analyzing the robustness of such a virtual instrument through low and high voltage tests.

A 16-GB 640-GB/s HBM2E DRAM With a Data-Bus Window Extension Technique and a Synergetic On-Die ECC Scheme

Circuit and design techniques are presented for enhancing the performance and reliability of a 3-D-stacked high bandwidth memory-2 extension (HBM2E). A data-bus window extension technique is implemented to cope with reduced clock cycle time ranging from data-path architecture, through-silicon via (TSV) placement, and TSV-PHY alignment. A power TSV placement in the middle of array and at the chip edge along with a dedicated top metal for power mesh improves power IR drop by 62%. An on-die ECC (OD-ECC) scheme featuring a self-scrubbing function is designed to be orthogonal to system ECC. An uncorrectable bit error rate (UBER) is improved by 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> times with the proposed OD-ECC and scrubbing scheme. A memory built-in self-test (MBIST) block supports low-frequency cell and core test in a parallel manner and all channel at-speed operation with adjustable ac parameters. The proposed parallel-bit MBIST reduces test time by 66%. A 16-GB HBM2E fabricated in the second generation of 10-nm class DRAM process achieves a bandwidth up to 640 GB/s (5 Gb/s/pin) and provides a stable bit-cell operation at a high temperature (e.g., 105 ° C).

EFFECT OF CATARACT EXTRACTION ON IOP BY GOLDMANN APPLANATION TONOMETRY AND A/C DEPTH BY PENTACAM

Cataract and glaucoma are the first and second leading causes of blindness worldwide that affect the older population. Hence, the interaction between these two diseases is of interest to clinicians.Intraocular Pressure (IOP) is a function of aqueous humor secretion rate, episcleral venous pressure, and outflow facility at the anterior chamber angle.Phacoemulsification cataract surgery has been shown by numerous studies to significantly reduce intraocular pressure (IOP), in glaucomatous and non- glaucomatous eyes. Although the mechanism of action responsible for postoperative IOP reduction remains under debate, many studies lend support to the theory of improved aqueous access to the trabecular meshwork (TM) as one of the mechanisms of IOP reduction. The following changes in AC parameters after cataract removal have been demonstrated: increased AC depth, increased AC volume and increased AC angle width.The aim of the work is to assess the effect of phacoemulsification with intraocular lens (IOL) implantation on intraocular pressure (IOP) and anterior chamber parameters in patients with cataract.