DC Mode Research Articles

Fingertip pulse rate variability extraction based on extreme-point symmetric mode decomposition

To solve shortcomings of being sensitive to noise and waveform when using threshold method to extract pulse rate variability (PRV) at this stage, a method using extreme-point symmetric mode decomposition to extract PRV signals from pulse waves with noise is proposed. A Butterworth filter is used to remove the baseline drift, the DC mode and power frequency noise, which can effectively avoid noise interference when identifying peak points. The pre-processed data is decomposed by extreme-point symmetric mode decomposition to select the corresponding mode of the main wave, thereby reducing the difficulty of feature point extraction. Compared with the threshold method, the extraction method proposed in this paper is more intuitive and can self-adaptively select the best decomposition layer. This method is suitable for the extraction of fingertip PRV under complex noise and some disease statuses.

Physically Detachable and Operationally Stable Cs2SnI6 Photodetector Arrays Integrated with µ‐LEDs for Broadband Flexible Optical Systems

AbstractWith the surge in perovskite research, practical features for future applications are desired to be secured, but the reliability of the materials and the use of hazardous Pb are longstanding problems. Here, an air‐stable Cs2SnI6 (CSI) is prepared via diluted hydriodic acid solvent‐based precursor optimization during scalable hydrothermal growth. Materials characterization is performed using various elemental peak analyses and crystallographic identification. The resulting CSI exhibits long‐term operating stability over 6 months, i) at elevated temperatures, ii) in ambient air, and iii) under light illumination from UV to near‐infrared. More importantly, to demonstrate an intriguing class of applications up to system level, physically detachable CSI photodetector arrays (PD‐arrays), integrated with micro‐light‐emitting‐diodes (μ‐LEDs) arrays, are successfully fabricated. In addition, 3 × 3 flexible CSI PDs are fully operational, even in air, and their spatial uniformity in pixels is quantitatively evaluated. The charge‐transport mechanisms of the CSI PDs under light and elevated temperature are assessed via temperature‐dependent characterization from 148 to 373 K, implying the involvement of 3D variable‐range hopping. Multicycle evaluation of the CSI PD‐arrays confirms their operational stability in AC and DC modes, demonstrating this platform's potential benefit for wireless optical interconnection in advanced Si technology.

Combined Propulsion and Levitation Control for Maglev/Hyperloop Systems Utilizing Asymmetric Double-Sided Linear Induction Motors

This article presents a new method for combined levitation and propulsion control in maglev/Hyperloop systems by selectively applying AC and DC modes of operation to a group of asymmetric double-sided linear induction motors (ADSLIMs). Although adjusting the AC current magnitude of lower and upper primary windings in ADSLIMs allows simultaneous control of thrust and lift forces, the limitation of this current balancing technique prohibits them from producing a high lift force while operating with low thrust force. To overcome this limitation and to simultaneously control the thrust and lift forces of the ADSLIMs with high efficiency under different operating conditions, a combination of AC and DC modes of operation is proposed. AC mode of operation consists of feeding different AC current amplitudes to the upper and lower ADSLIM primary windings to produce and control the required thrust and lift forces. The DC mode of operation consists of controlling one or several ADSLIMs to operate with DC excitation to realize the desired lift force at lower thrusts which otherwise cannot be achieved by operating in AC mode alone. The concept of the new combined control strategy is studied using two-dimensional finite element (FE) electromagnetic simulations and compared with an Inductrack permanent magnet (PM) based passive magnetic levitation system.

Frequency-Reconfigurable SP4T Switch With Plaid Metal Transistors and Forward Body Biasing for Enhanced RON × COFF Characteristics

A frequency-reconfigurable SP4T switch is presented, in which <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON}} \times {C}_{\text {OFF}}$ </tex-math></inline-formula> characteristics of switch transistors are enhanced with plaid metal transistors and forward body biasing. Plaid metal transistors (PMT) with forward body bias (FBB) are used for all of the transistors to enhance the FoM. The plaid patterned metal accesses of a transistor for the source and drain decrease the extrinsic resistance and capacitance. FBB increases the overdrive voltage of a transistor and decreases the on-resistance. The SP4T switch includes main switch matrices that route an input signal to four-outputs, a switched inductor (SI) network, and a mode-selection switch. The SI network connected through the mode-selection switch resonates out the off-capacitances of the main switch matrices at RF in the RF mode. The SP4T switch operates without the SI network in DC mode. The SP4T switch is implemented in a 28-nm FDSOI CMOS process. The core area occupies 0.2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The switch shows less than 2 dB insertion loss from DC to 4.4 GHz in the DC mode and from 4.4 to 5.3 GHz in the RF mode, where isolations are more than 16.8 dB and 18 dB, respectively.

Enhanced Field Emission of Single-Wall Carbon Nanotube Cathode Prepared by Screen Printing with a Silver Paste Buffer Layer.

A high emission current with relatively low operating voltage is critical for field emission cathodes in vacuum electronic devices (VEDs). This paper studied the field emission performance of single-wall carbon nanotube (SWCNT) cold cathodes prepared by screen printing with a silver paste buffer layer. The buffer layer can both enforce the adhesion between the SWCNTs and substrate, and decrease their contact resistance, so as to increase emission current. Compared with paste mixing CNTs and screen printed cathodes, the buffer layer can avoid excessive wrapping of CNTs in the silver slurry and increase effective emission area to reduce the operating voltage. The experimental results show that the turn-on field of the screen-printed SWCNT cathodes is 0.9 V/μm, which is lower than that of electrophoretic SWCNT cathodes at 2.0 V/μm. Meanwhile, the maximum emission current of the screen-printed SWCNT cathodes reaches 5.55 mA at DC mode and reaches 10.4 mA at pulse mode, which is an order magnitude higher than that of electrophoretic SWCNTs emitters. This study also shows the application insight of small or medium-power VEDs.

Positive column dynamics of a low-current atmospheric pressure discharge in flowing argon

We present the results of studies of a cold-plasma atmospheric pressure discharge in argon flow, in both DC and pulse-periodic modes. The burning voltage and the discharge current were 200 V and 15 mA in continuous mode; in pulse-periodic mode the voltage was 220 V and the current 15 mA for a pulse repetition rate of 100 kHz. Special attention was given to the positive column dynamics during the discharge stages of initiation, burning, and extinction. The main method of investigation employed optical diagnostics of the plasma in the visible range with high time resolution. The positive discharge column is shown to be a constricted current channel in the form of an elongated loop. In continuous mode, the length of the positive column, from anode attachment to inflection point outside the discharge system, is several millimeters. In pulsed mode, the positive column is an unsteady plasma formation, the length of which increases at about 4 m s−1, and reaches the same dimension over a time of order 1 ms. We find that the positive column plasma includes hydroxyl molecules OH, nitrogen N2, and atomic oxygen O I, along with atoms of the working gas argon. Observation of the time evolution of the optical emission from the plasma-forming gas shows that the plasma glow of the positive column is mainly determined by argon Ar I radiation, with maximum intensity at the trailing edge of the current pulse.

Study and Analysis of Dual Mode Operation of Single DC Motor (Series and Separately Excitation Modes)

This paper presents a novel idea of a method to run DC series motor and then into DC separately excited mode and vice versa during operation. The purpose of this paper is to give an analysis of a real-time study performed experimentally for both series and separately excited operation of DC motor. The DC motor initially started in series mode giving high torque at a constant load in the form of an inertia wheel as starting load. The motor is then switched to separately excited DC mode with the help of switches after attaining the required number of rpm or speed. High speed with sufficient torque and good controllability is observed in separately excited DC motor mode. Eventually, this system has been proven with experimental results and proposed for numerous applications, especially where high starting torque and less speed are required and after that, high speed is required. Analyzing results with the help of MATLAB previously, a hardware-based real-time operating system has been provided. This setup can be proposed for various applications such as battery-operated DC machines especially Electric Vehicles and off-road Electric Vehicles and Solar powered applications as well.

A study on corrosion behaviour of various modes of ATIG welded plain carbon steel

The purpose of this study is to look at the corrosion behaviour of various current modes of Autogenous Tungsten Inert Gas (ATIG) welded powder metallurgy plain carbon steel (Fe-0.5% C). The impacts of different current modes (DC, AC, Mixed, and Pulsed) on ATIG corrosion welded joints are looked at. To get the highest density, the rectangular sintered plain carbon steel strips were subjected to a cold upset. The parent and welded specimens were subjected to aqueous immersion and electrochemical corrosion tests. The corrosion test findings were compared to the microhardness, corroded surface morphology, microstructure, and SEM of the corroded area. It is observed from the test results that as the parent metal contains pores could lead to a high corrosion rate and the ATIG welded specimens exhibit less corrosion rate due to pore free region at the weldment. The DC mode of the welded specimen is observed to exhibit a lesser corrosion rate compared to the other modes of welded specimens due to higher heat generation.

Transition from ballistic to thermalized transport of metal-sputtered species in a DC magnetron

Tunable diode-laser induced fluorescence technique has been optimized to accurately measure the titanium (Ti)-sputtered atom velocity distribution functions (AVDFs) in a magnetron discharge operating in DC mode. The high spatial and spectral resolution achieved reveals some features of the transport of the metal-sputtered atoms and their thermalization. The two groups of thermalized and energetic atoms have been very well separated compared to previous works. Hence, the fitting of the energetic atom group shows dumping from modified Thompson to Gauss distribution when the product pressure-distance from the target increases. In parallel, sputtered metal transport from the target has been simulated using the Monte Carlo collision (MCC) approach. Direct comparison between numerical and experimental results led to an improved cross-section for Ti–Ar momentum transfer, based on the ab initio formulas of the interaction potential derived from noble gas interaction. The accuracy of the experimental data enabled the numerical parametric study of the angular distribution and cut-off energy for the initial distribution of sputtered atoms to reveal the precise characterization of the initial conditions. A very good overall agreement is obtained for measured and calculated AVDFs. Comparison between the measured and modeling results emphasized the major role played by the argon (Ar) ions, not only in the sputtering process, but in the neutral metal transport by the gas rarefaction near the target. The microscopic description provided by the MCC model clearly reveals different transport regimes: ballistic, diffusive and back-scattering, which provide new insight into the thermalization of sputtered species in the intermediate pressure range.

Plasma electrolytic oxidation of zircaloy-4 in a mixed alkaline electrolyte

Characteristics of coating resulted from plasma electrolytic oxidation (PEO) of zircaloy-4 in an electrolyte containing phosphate, silicate, and hydroxide were investigated. The mixed electrolyte is proposed to reduce power consumption. PEO was conducted in a DC mode at a current density of 30, 50, and 70 mA/cm2. Plasma was generated at a relatively low breakdown voltage of 150 V, independent of the current density. The resulting coating was composed of amorphous SiO2 and crystalline monoclinic (m) and tetragonal (t) ZrO2 phases. XRD analysis revealed that the porous outer layer developed at 30 mA/cm2 was dominated by the m phase. The percentage of the m phase decreased while the t phase increased with increasing current density. Therefore, the coating formed at 70 mA/cm2 showed the highest abrasive wear resistance, three times higher than the substrate. Similarly, the polarization curve and electrochemical impedance spectroscopy showed that the highest corrosion resistance, more than two orders of magnitude higher than the substrate, was obtained in the coated-70 mA/cm2 specimen. The use of low power and a mixed electrolyte is beneficial in producing PEO coating with high wear resistance and excellent anti-corrosion characteristic.

Performance analysis and implementation of a scanning tunneling potentiometry setup: Toward low-noise and high-sensitivity measurements of the electrochemical potential.

Scanning tunneling potentiometry allows for studying charge transport on the nanoscale to relate the local electrochemical potential to morphological features of thin films or two-dimensional materials. To resolve the influence of atomic-scale defects on the charge transport, sub-µV sensitivity for the electrochemical potential is required. Here, we present a complete analysis of the noise in scanning tunneling potentiometry for different modes of operation. We discuss the role of various noise sources in the measurements and technical issues for both dc and ac detection schemes. The influence of the feedback controller in the determination of the local electrochemical potential is taken into account. Furthermore, we present a software-based implementation of the potentiometry technique in both dc and ac modes in a commercial scanning tunneling microscopy setup with only the addition of a voltage-controlled current source. We directly compare the ac and dc modes on a model resistor circuit and on epitaxial graphene and draw conclusions on the advantages and disadvantages of each mode. The effects of sample heating and the occurrence of thermal voltages are discussed.

Comparison of thrusts imparted by a magnetron sputtering source operated in DC and high power impulse modes

The thrusts induced by the 45-mm-diameter DC and high power impulse magnetron sputtering [DC magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS)] sources are assessed by using the pendulum thrust balance, where the instantaneous discharge power for the HiPIMS is two orders of magnitude larger than that for the DCMS. The temporally averaged power of the HiPIMS is chosen as 50–150 W, being similar to the DCMS, by adjusting the duty cycle. The thrust-to-power ratios of 9.1 and 3.7 mN/kW are obtained for the DCMS and HiPIMS, respectively, by ejecting the copper target material via sputtering. A comparison between the thrust and the deposition rate of the copper film on a substrate implies that the flux and the velocity of the ejected material for the DCMS are larger and lower than those for the HiPIMS, respectively.

Intra Prediction and Mode Coding in VVC

This paper presents the intra prediction and mode coding of the Versatile Video Coding (VVC) standard. This standard was collaboratively developed by the Joint Video Experts Team (JVET). It follows the traditional architecture of a hybrid block-based codec that was also the basis of previous standards. Almost all intra prediction features of VVC either contain substantial modifications in comparison with its predecessor H.265/HEVC or were newly added. The key aspects of these tools are the following: 65 angular intra prediction modes with block shape-adaptive directions and 4-tap interpolation filters are supported as well as the DC and Planar mode, Position Dependent Prediction Combination is applied for most of these modes, Multiple Reference Line Prediction can be used, an intra block can be further subdivided by the Intra Subpartition mode, Matrix-based Intra Prediction is supported, and the chroma prediction signal can be generated by the Cross Component Linear Model method. Finally, the intra prediction mode in VVC is coded separately for luma and chroma. Here, a Most Probable Mode list containing six modes is applied for luma. The individual compression performance of tools is reported in this paper. For the full VVC intra codec, a bitrate saving of 25% on average is reported over H.265/HEVC using an objective metric. Significant subjective benefits are illustrated with specific examples.

Electron cyclotron resonance discharge enhancement in a cusped field thruster

Electron cyclotron resonance (ECR) is induced to enhance the discharging performance of a cusped field thruster, by feeding microwave into the channel. Due to a critical combination of ECR discharge and DC discharge, propellant utilization is significantly improved, with varying degrees of impact on other parameters. The DC mode, the ECR mode and the combined mode are achieved and analyzed respectively. A Faraday probe and a retarding potential analyzer are employed to diagnose the plume plasma, and approximate calculated thrust is given. Moreover, high frequency electric field simulation is carried out to indicate the microwave feeding process in different mass flow rate conditions, making use of a particle-in-cell simulation result. The result shows that the ECR enhancement is particularly effectual in low mass flow conditions, and the special plasma distribution in the cusped magnetic field leads to the propellant utilization trend in the combined mode.

Bias-voltage effect on the TiN nanoparticle injection into magnetron sputtered CrN thin films towards nc-TiN/nc-CrN composites

The formation of a nanocomposite structure is thermodynamically driven by spinodal decomposition in at least two phases. With respect to the suppression of solid solution formation, artificial nc-TiN/nc-CrN composites were deposited using a novel hybrid-process, in which TiN nanoparticles and CrN thin film were separately synthesized and simultaneously deposited during composite growth. The bias-voltage is known as a crucial deposition parameter concerning the structural and mechanical properties in thin film technology. However, it is still unclear whether an externally injected nanoparticle jet is influenced by the bias-voltage applied to the substrate. In this work, composite thin films were DC sputtered applying bias-voltages of 0 V, -100 V and -200 V in DC mode, as well as -100 V in MF and HiPIMS mode. TEM-investigations reveal the successful embedment of the nanoparticles in the film. Growth defects in the interface between nanoparticle and thin film can be reduced using a pulsed bias-voltage. Based on 2D GI-XRD experiments using synchrotron radiation, a bias-voltage of -200 V DC and -100 V MF enables the reinforcement of a higher nanoparticle content in the thin films. Similar to an increased bias-voltage, the injection of nanoparticles results in a decrease of the crystallite size. In principle, the residual stresses are increased by the nanoparticle embedding, as is the case for an increasing bias-voltage. In the event of a pulsed-bias voltage, however, the residual stresses can be reduced by the embedding of the nanoparticles. The mechanical properties of the CrN thin films can be maintained when nanoparticles are injected.

Efficient mode decision scheme based on edge detection with Gaussian pulse for Intra-prediction in H.264/AVC

Advanced Video Coding (H.264/AVC) is one of the most important video coding standards which was developed by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG). Due to the complex procedures needed to find the optimal mode in intra prediction mode stage of H.264/AVC, an efficient mode decision is suggested in this paper. The main objectives of the proposed work are improving the compression efficiency of video coding and minimizing the degradation of video quality. The proposed algorithm is based on the gradient method for edge detection using the Prewitt filter to determine the texture direction of a block to be predicted in the luminance component of a video frame. To decide either implemented the DC mode or the edge-detection based gradient method to predict block under consideration, a predefined threshold value is used for the homogeneity test of each macro-block. To reduce the Bit Rate of the compressed video, Gaussian pulse modulation is also suggested to the Discrete Cosine Transformation (DCT) components of each macro-block during the coding process. The proposed algorithm is carried out on a luminance component of a set of different YUV video sequences with different resolutions and different quantization parameters using MATLAB. The suggested algorithm is evaluated using different metrics which are Peak Signal to Noise Ratio (PSNR) and bit rate measured by Bjontegaard Delta method. The simulation results show the ability of the proposed algorithm in enhancing the BDPSNR averagely by 1.14 dB and reducing the BDBR averagely by 11.34 %for QCIF sequences compared to the existing state-of-the-art fast intra-prediction mode decision algorithms.

Nonlinear Oscillations of Particle-Reinforced Electro-Magneto-Viscoelastomer Actuators

Abstract This work presents the dynamic modeling and analysis of a particle-reinforced and pre-stressed electro-magneto-viscoelastic plate actuator. The actuator belongs to a smart actuator category and is made of an electro-magneto-active polymer filled with a particular volume fraction of suitable fillers. An energy-based electro-magneto-viscoelastic model is developed to predict the actuator response and interrogate the impact of particle reinforcement on the dynamic oscillations of a pre-stressed condition of the actuator. An Euler–Lagrange equation of motion is implemented to deduce the governing dynamic equation of the actuator. The findings of the model solutions provide preliminary insights on the alteration of the nonlinear behavior of the actuator driven by DC and AC dynamic modes of actuation. It is observed that the enrichment in the particle reinforcement characterized by the amount of fillers strengthens the polymer and depleted the associated level of deformation. Also, the depletion in the intensity of oscillation and enhancement in the frequency of excitation is perceived with an increase in the particle reinforcement. In addition, the time-history response, Poincare plots, and phase diagrams are also plotted to assess the stability, periodicity, beating phenomenon, and resonant behavior of the actuator. In general, the current study provides initial steps toward the modern actuator designs for various futuristic applications in the engineering and medical field.

An Optimal Control Algorithm with Reduced DC-Bus Current Fluctuation for Multiple Charging Modes of Electric Vehicle Charging Station

This paper presents a systematic structure and a control strategy for the electric vehicle charging station. The system uses a three-phase three-level neutral point clamped (NPC) rectifier to drive multiple three-phase three-level NPC converters to provide electric energy for electric vehicles. This topology can realize the single-phase AC mode, three-phase AC mode, and DC mode by adding some switches to meet different charging requirements. In the case of multiple electric vehicles charging simultaneously, a system optimization control algorithm is adopted to minimize DC-bus current fluctuation by analyzing and reconstructing the DC-bus current in various charging modes. This algorithm uses the genetic algorithm (ga) as the core of computing and reduces the number of change parameter variables within a limited range. The DC-bus current fluctuation is still minimal. The charging station system structure and the proposed system-level optimization control algorithm can improve the DC-side current stability through model calculation and simulation verification.

High Frequency MOSFET Charging Circuit Using Series Parallel DC-DC Resonant Converter for Wireless Power Application

This paper proposes a new circuit topology of high frequency switching DC-DC Series Parallel Loaded Resonant Converter (SPLRC). The circuit is proposed to be used for a wireless power transmission application that required fast-charging operation. Most of the components used here are low-cost and commercially available in the market. Then, the purpose circuit is transformed into a different equivalent circuit that can efficiently analyze AC and DC modes. For each model, the operation for the converter is first described and explained. A full detailed circuit simulation is then carried out to find out the workability of the purpose converter. From the simulation, optimization is carried out. Here the components value is obtained. MATLAB R2018A is used for simulation purposes rather than being tested again using PSIM software to further prove the validity of the model. All the finding is explained and discussed, here, from the simulation result, it is confirmed that a high-frequency switching circuit is operated as expected.

Oxygen vacancy engineering of TaO x -based resistive memories by Zr doping for improved variability and synaptic behavior

Resistive switching (RS) devices are promising forms of non-volatile memory. However, one of the biggest challenges for RS memory applications is the device-to-device (D2D) variability, which is related to the intrinsic stochastic formation and configuration of oxygen vacancy (VO) conductive filaments (CFs). In order to reduce the D2D variability, control over the formation and configuration of oxygen vacancies is paramount. In this study, we report on the Zr doping of TaO x -based RS devices prepared by pulsed-laser deposition as an efficient means of reducing the VO formation energy and increasing the confinement of CFs, thus reducing D2D variability. Our findings were supported by XPS, spectroscopic ellipsometry and electronic transport analysis. Zr-doped films showed increased VO concentration and more localized VOs, due to the interaction with Zr. DC and pulse mode electrical characterization showed that the D2D variability was decreased by a factor of seven, the resistance window was doubled, and a more gradual and monotonic long-term potentiation/depression in pulse switching was achieved in forming-free Zr:TaO x devices, thus displaying promising performance for artificial synapse applications.