Pulse Width Duration Research Articles

Evaluating the influence of filter membrane on dust particle deposition and detachment based on CFD-DEM method

The motion of dust particles significantly affects the service life and filtration efficiency of filter elements. By employing a coupled computational approach combining Computational Fluid Dynamics and Discrete Element Method (CFD-DEM), the Johnson-Kendall-Roberts (JKR) model was incorporated into the calculation of adhesive forces between particle-particle and particle-wall interactions. The influence of the membrane layer on dust particle deposition and detachment on the surface of filter elements was investigated through simulation analysis. The influence of membrane layers on the deposition and detachment of dust particles in filter elements was investigated. The results show that the addition of the membrane layer led to a 35.5% increase in the initial filtration pressure drop of the filter. However, it concurrently resulted in a diminution of the deposition depth of dust particles. By the eighth cycling period, the deposition depth of the filter element with membrane (FWM) was 2.5 mm, which was only half that of the filter element without membrane (FOM). Moreover, it was found that the cleaning efficiency of the FOM is more sensitive to reverse flow pressure, while the cleaning efficiency of the FWM is more sensitive to the duration of pulse width. These findings can help explain the mechanism of dust particle deposition and detachment and provide a basis for the design and manufacturing of filter elements.

Analysis of Degradation Mechanism in Poly-Si TFTs Under Dynamic Gate Voltage Stress With Short Pulse Width Duration

Analysis of Degradation Mechanism in Poly-Si TFTs Under Dynamic Gate Voltage Stress With Short Pulse Width Duration

A low-jitter and low-phase noise switched-loop filter PLL using fast phase-error correction and dual-edge phase comparison technique

This paper presents a low-jitter and low-phase noise type-II charge pump and switched-loop filter-based (SLF) phase-locked loop (PLL) with a fast phase error correction technique (FPEC) and a newly proposed dual-edge phase comparator (DEPC). To improve the phase noise, the bandwidth of the proposed PLL is extended to fREF/5 using the proposed DEPC. It consists of four D flip-flops in true single-phase clock (TSPC) logic, four current-mode logic-based inverters, and two logic OR gates. Unlike conventional DEPCs, the proposed DEPC has a small reset pulse width duration and negligible blind zone, and due to this, it can perform at higher frequencies along with an increased phase detection range. The proposed architecture is implemented for a 2.4 GHz output frequency that embodies DEPC and SLF using the FPEC technique in an 180-nm Semi-Conductor Laboratory (SCL) CMOS process. The proposed DEPC can work up to a maximum of 3.45 GHz frequency with 145 ps of reset delay. The proposed PLL accomplishes the 40 MHz bandwidth with a 200 MHz reference clock. The simulated rms jitter integrated from 10 kHz to 100 MHz and the phase noise of the output signal at an offset of 1 MHz are 860 fs and −122 dBc/Hz respectively. The proposed architecture occupies an area of 0.032 mm2 and consumes 8.2 mW from 1.8 V power supply.

SOA-MZI Differential Transformation Approach Applied on Simultaneous Electro-Optical Mixing

We experimentally incubate a ground-breaking design, for the first time, of concurrent electro-optical semiconductor optical amplifier Mach–Zehnder interferometer mixing (SOA-MZI) based on a differential transformation methodology. Projecting the simultaneous electro-optical mixing system and improving its efficiency and quality achievement in optical and electrical features is a crucial task due to the characteristics of an optical pulse source (OPS) operating with a repetition rate of f= 58.5 GHz and a pulse width duration of 1 picosecond (ps). The resultant of the contemporaneous electro-optical mixing exhibits exceptional passive power stability, reaching 0.8% RMS over a two-hour period. Furthermore, when the optical bandpass filter is controlled at the data wavelength of 1540 nm, we achieve up to 30 dBm of the overall mean output power with an optical conversion gain of 46 dB and an exceptionally high optical signal-to-noise ratio reaching 80 dB. Using orthogonal frequency division multiplexing (OFDM) signals, each data subcarrier is modulated using 128 quadratic amplitude modulation (128-QAM) at carrier frequencies fk and simultaneously up-mixed to high aim frequencies nf±fk at the SOA-MZI output. Additionally, the resulting OFDM_128-QAM up-mixed signal is examined using the specifications for the error vector magnitudes (EVMs) and the electrical conversion gains (ECGs). The SOA-MZI mixing experiment can handle high frequencies up to 120 GHz. Positive ECGs are followed by a sharp reduction over the entire band of the aim frequencies. The highest frequency range achieved during the realistic investigation is shown at 2f+f4= 120 GHz, where the EVM reaches 8% with a symbol rate of 15 GSymb/s. Furthermore, the concurrent OFDM_128-QAM up-mixed signal achieves an absolute maximum bit rate of 80.4 Gbit/s. The investigation into the simultaneous electro-optical mixing regime is finally supported by unmatched characterization improvements.

Clinical Practice Guidelines for the Use of Electroconvulsive Therapy.

Clinical Practice Guidelines for the Use of Electroconvulsive Therapy.

Evaluation of multi-bit domain wall motion by low current density to obtain ultrafast data rate in a compensated ferrimagnetic wire

Architectures based on multi-bit magnetic domain walls (DWs) take advantage of the fast speed, high density, nonvolatility, and flexible design of DWs to process and store data bits. However, controlling multi-bit DWs driven by electric current at an ideal position remains a significant challenge for developing integrated spintronic applications with high reliability and low power consumption. We exhibit the possibility of driving fast and stable multi-bit DWs at low current density without an in-plane external magnetic field in Fe-rich GdFeCo magnetic wires. When an in-plane magnetic field is applied in the wire direction, the front edge accelerates, although the rear edge decelerates, and the recorded data are destroyed. Hence, this method is not practical. Here, the DW speed of the multi-bit DWs is 1500 m/s under a low current density of 29 × 1010 (A/m2). A straight DW shape is required to accurately read the bits of information by the tunneling magnetoresistance head in real DW memory devices. Moreover, we demonstrate that the DW position is related to the DW shape after injecting a pulse current into the magnetic wire. A straight DW shape is exhibited for 3 ns pulse duration width, while the DW shape became rounded for 30 and 50 ns pulse duration widths. Our finding provides a practical concept for multiple-bit-per-cell memory and presents a viable platform for DW memory applications.

MCU-less biphasic electrical stimulation circuit for miniaturized neuromodulator.

A standalone neuro-stimulator circuit without a need of microcontroller (MCU) is presented. The neuro-stimulator circuit has a capability to produce a biphasic electrical stimulus with programmable pulse width and train duration. The proposed hardware system consists of commercial-off-the-shelf (COTS) components: a comparator to recognize triggering events and generate on/off signal for a variable train duration, a programmable timer to generate oscillatory signal with a fixed frequency and a variable pulse width, and a differentiator to convert monophasic pulses to biphasic pulses. The differentiator also works as a current driver having current drive capability of up to 40mA. The proposed MCU-less biphasic electrical neuro-stimulator successfully generated biphasic stimuli with variable pulse widths from 400µs to 5ms and train durations from 35 to 55% of cycle duration. It works with fixed parameters programmed at the beginning, and does not need continuous MCU input. Therefore, the proposed standalone neuro-stimulator circuit has a potential to decrease power and area consumption and minimize the size of the neuro-stimulator system.

Compact Q-switched Nd:YAG single-crystal fiber laser with 794 nm laser diode pumping

A promising Nd:YAG single-crystal fiber (SCF) was successfully fabricated by the laser-heated pedestal growth method. The compact passively Q-switched laser has been realized for the first time with a 794 nm laser diode pumping. Pulsed laser performances of this SCF were investigated in detail with a flat-flat resonator. Under the absorbed pump power of 2.50 W, the peak power of 274.24 W was obtained with 19.41 ns pulse duration width and 65.94 kHz repetition rate.

Design of an FPGA-Based Fuzzy Feedback Controller for Closed-Loop FES in Knee Joint Model.

Functional electrical stimulation (FES) device has been widely used by spinal cord injury (SCI) patients in their rehab exercises to restore motor function to their paralysed muscles. The major challenge of muscle contraction induced by FES is early muscle fatigue due to the open-loop stimulation strategy. To reduce the early muscle fatigue phenomenon, a closed-loop FES system is proposed to track the angle of the limb’s movement and provide an accurate amount of charge according to the desired reference angle. Among the existing feedback controllers, fuzzy logic controller (FLC) has been found to exhibit good control performance in handling complex non-linear systems without developing any complex mathematical model. Recently, there has been considerable interest in the implementation of FLC in hardware embedded systems. Therefore, in this paper, a digital fuzzy feedback controller (FFC) embedded in a field-programmable gate array (FPGA) board was proposed. The digital FFC mainly consists of an analog-to-digital converter (ADC) Data Acquisition and FLC sub-modules. The FFC was designed to monitor and control the progress of knee extension movement by regulating the stimulus pulse width duration to meet the target angle. The knee is expected to extend to a maximum reference angle setting (70°, 40° or 30°) from its normal position of 0° once the stimulus charge is applied to the muscle by the FES device. Initially, the FLC was modelled using MATLAB Simulink. Then, the FLC was hardcoded into digital logic using hardware description language (HDL) Verilog codes. Thereafter, the performance of the digital FLC was tested with a knee extension model using the HDL co-simulation technique in MATLAB Simulink. Finally, for real-time verification, the designed digital FFC was downloaded to the Intel FPGA (DE2-115) board. The digital FFC utilized only 4% of the total FPGA (Cyclone IV E) logic elements (LEs) and required 238 µs to regulate stimulus pulse width data, including 3 µs for the FLC computation. The high processing speed of the digital FFC enables the stimulus pulse width duration to be updated every stimulation cycle. Furthermore, the implemented digital FFC has demonstrated good control performance in accurately controlling the stimulus pulse width duration to reach the desired reference angle with very small overshoot (1.4°) and steady-state error (0.4°). These promising results are very useful for a real-world closed-loop FES application.

High-Throughput Drug Screening System Based on Human Induced Pluripotent Stem Cell-Derived Atrial Myocytes ∼ A Novel Platform to Detect Cardiac Toxicity for Atrial Arrhythmias.

Evaluation of proarrhythmic properties is critical for drug discovery. In particular, QT prolongation in electrocardiograms has been utilized as a surrogate marker in many evaluation systems to assess the risk of torsade de pointes and lethal ventricular arrhythmia. Recently, new evaluation systems based on human iPS cell-derived cardiomyocytes have been established. On the other hand, in clinical situations, it has been reported that the incidence of atrial arrhythmias such as atrial fibrillation has been increasing every year, with the prediction of a persistent increase in the near future. As to the increased incidence of atrial arrhythmias, in addition to the increased population of geriatric patients, a wide variety of drug treatments may be related, as an experimental method to detect drug-induced atrial arrhythmia has not been established so far. In the present study, we characterized the atrial-like cardiomyocytes derived from human induced pluripotent stem cells and examined their potential for the evaluation of drug-induced atrial arrhythmia. Atrial-like cardiomyocytes were induced by adding retinoic acid (RA) during the process of myocardial differentiation, and their characteristics were compared to those of RA-free cardiomyocytes. Using gene expression and membrane potential analysis, it was confirmed that the cells with or without RA treatment have atrial or ventricular like cardiomyocytes, respectively. Using the ultra-rapid activating delayed rectifier potassium current (IKur) channel inhibitor, which is specific to atrial cardiomyocytes, Pulse width duration (PWD) 30cF prolongation was confirmed only in atrial-like cardiomyocytes. In addition, ventricular like cardiomyocytes exhibited an early after depolarization by treatment with rapidly activating delayed rectifier potassium current (IKr) channel inhibitor, which induces ventricular arrhythmia in clinical situations. Here, we have established a high-throughput drug evaluation system using human iPS cell-derived atrial-like cardiomyocytes. Based on the obtained data, the system might be a valuable platform to detect potential risks for drug-induced atrial arrhythmias.

Nozzle-free droplet generation with focused acoustic beams for encapsulation of single circulating tumor cells

The recovery of single circulating tumor cells (CTCs) from the peripheral blood of cancer patients has great potential for the study of cell heterogeneity and cancer metastasis and the development of personalized cancer immunotherapy. Here we present nozzleless droplet generation with focused acoustic beams for cell encapsulation. The mechanism of droplet generation is sensitive to the pulse width and the droplet diameter ranges from 350 to 550 μm. The pulse width duration (520 μs) and cell concentration (5 × 103 cells ml−1) can be adjusted to obtain the maximum probability (11.61%) of single cell encapsulation. Three-color fluorescence is used to identify encapsulated cells in the droplet and target cells are extracted by microcapillarity for conducting single cell analysis. The reported method of using acoustic tweezers to eject the droplet has advantages of convenience, speed and biocompatibility while being non-invasive, and could become a powerful tool for encapsulating single CTCs.

Efficient Detection and Single-Cell Extraction of Circulating Tumor Cells in Peripheral Blood.

Circulating tumor cells (CTCs) play an important role in cancer biology studies. To further elucidate the role of single CTCs in tumor metastasis and prognosis, effective methods must be developed to isolate and encapsulate single CTCs. In this work, a single CTC capture and encapsulation platform based on ZnO nanofibers and surface acoustic waves was constructed. We also demonstrated that this platform can capture and encapsulate single CTCs efficiently. We first validated that the dense ZnO nanofibers provide additional binding sites, resulting in an increased capture efficiency of up to 93.3%. We then demonstrated that the release efficiency was increased to 100% by dissolving the substrate with ultralow concentration (25 mM) phosphoric acid, and the activity of the released cells was not affected. Furthermore, the released cells were suspended in alginate solution and encapsulated single CTCs via droplet-based surface acoustic wave devices. The encapsulating rate of a single cell is up to 13% under a pulse width duration of 520 μs. Few technology based on nanofibers and acoustic tweezers for single-cell encapsulation via acoustic droplet vaporization has been reported. It has a wide range of potential applications to acquire single target cells, which may facilitate further early clinical diagnosis and treatment of cancer patients.

Spatiotemporal analysis of streamer discharge in a wire-to-wire reactor with positive nanosecond pulse supply

The spatial and temporal distribution of the discharge streamers in positive pulsed wire-to-wire electrode configuration in atmospheric air is investigated by an electrical-optical diagnostic system. Time-resolved ICCD images show that the discharge streamers in wire-to-wire electrode develop in three phases: the primary streamer, the secondary positive streamer, and the secondary negative streamer. It is observed that the evolution of discharge streamers is strongly influenced by the amplitude of the applied voltage. The optical emission spectroscopy measurement of hydroxyl radical OH indicates that the OH is mainly generated in the secondary positive streamer near the anode region. But in the region near the cathode the emission of OH radicals can also be detected due to the secondary negative streamer. The influences of rise time, fall time and pulse duration on streamer dynamics and the subsequent radical production are observed. It is shown that the average propagation velocity of the primary streamer decreases with the increase of the rise time, while the variation of pulse width and pulse duration parameters have little effect on that of the primary streamer. The response surface methodology based on Box–Behnken design model is implemented to evaluate the contribution of the three critical pulse parameters on ozone production. The results of the response surface quadratic model show that the pulse rise time plays the most prominent role in the generation of ozone among the three pulse parameters of rise time, fall time and pulse duration.

Analytical study of flexible stimulation waveforms in muscle fatigue reduction

This paper presents the analytical study of flexible stimulation waveforms in muscle fatigue reduction for functional electrical stimulator (FES)-assisted hemiplegic muscle activities. The major challenge of muscle contraction induced by FES is early muscle fatigue which greatly limits activities such as FES-assisted standing and walking. The fixed stimulation pattern applied on a same motor unit has resulted the motor unit to be overworked and fatigue easily. Therefore, in this work, the stimulus parameters, which include the pulse width duration and the frequency were varied to create a few flexible stimulation waveforms using MATLAB/Simulink. The pulse width duration was modulated from 100µs – 500µs to generate five types of flexible stimulation waveforms such as Rectangular, Trapezoidal, Ramp Up, Ramp Down and Triangular. Concurrently, a few ranges of stimulus frequency were also used, which include 20Hz, 30Hz and 50Hz. The generated flexible stimulation waveforms were applied onto a humanoid muscle model to investigate and analyse the muscle output response and early muscle fatigue reduction. From the conducted simulation results and analyses, it was observed that flexible stimulation waveforms such as Triangular, Ramp Up and Ramp Down could reduce early muscle fatigue phenomenon by having lower average of negative slope, in the range of 0.012 to 0.013 for the muscle fitness. In contrast, the Rectangular and Trapezoidal shapes were found to have higher negative slope of muscle fitness in the range of 0.028 to 0.031. The Ramp Down shape was found to have the lowest average of negative slope (0.012) while Rectangular was found to have the highest average of negative slope (0.031). Therefore, it can be concluded that flexible stimulation waveforms such Ramp Down, Ramp Up and Triangular shapes could reduce early muscle fatigue phenomenon with Ramp Down shape having the highest muscle fatigue reduction.

Hybrid organic small molecules as a saturable absorber for passive Q-switching in erbium-doped fiber laser

This work demonstrates a Q-switched fiber laser by utilizing hybrid organic small molecules (HOSM) based on Tris-(8-hydroxyquinoline) aluminum (Alq3) and N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) as a saturable absorber. The HOSM was embedded into poly(vinyl alcohol) and inserted into a fiber laser cavity to achieve pulsing at 1560.1 nm. The pulse repetition rate was tuned from 66.3 kHz to 109 kHz whereas the pulse width duration decreased from 6.3 µs to 2.2 µs as the laser diode power gradually increased from 56 to 262 mW. Then a tunable bandpass filter (TBF) was used to produce tunable wavelength operation. As the TBF was tuned, the wavelength of the Q-switched laser shifted continuously from 1519.6 nm to 1562.8 nm. The results show that HOSM could be an efficient, easy to fabricate, and inexpensive saturable absorber for generating single and tunable wavelength Q-switched fiber laser.

Plasma Species and Coating Compositions in Aluminum Treated by PEO Using Shot Square Pulse

Abstract Up to now, plasma electrolytic oxidation (PEO) has been either produced direct current or ultra-low frequency ( 8 g.L-1 with presence of KOH). In order to contribute to these studies, the effect of current pulse width and time duration was investigated using diluted silicate electrolytic (Na2SiO3 2 g.L-1) and high pulse frequencies (> 1 kHz). The PEO process was performed on pure aluminum to try to explain how the phases composing the coatings are formed and distributed over the treatment time. For this, was made in situ monitoring using optical emission spectroscopy (OES) coupled with CCD camera. The crystalline phases evolution in the sample surface was investigated using grazing incidence X-ray diffraction (GIXRD). Regarding the evolution of ceramic phases, it is possible to verify that, internally, the predominant phase is rhombohedral α-Al2O3 but, superficially, the predominant phase is cubic γ-Al2O3. It was verified the presence of Si on the borders of the pores or in proximity to cracks, especially in the treatments with higher pulse width. SEM analysis shows a reduction of the superficial porosity and an increase in coating thickness with pulse width and treatment time.

Varying frequency and pulse width duration during electrical stimulation of cervical sympathetic chain in Zucker Fat rats dramatically alters hemodynamics

The influence of electrical stimulation of the cervical sympathetic chain (CSC) on hemodynamics has not been thoroughly investigated. Previous studies using healthy strains of rats focused on upper airway dynamics as well as ventilatory parameters. This current study examined the changes in mean blood pressure (MAP), diaphragmatic electromyogram (EMG), and upper airway pressure (UAP) elicited by electrical stimulation of the CSC in Zucker‐fat rats, a model of obesity‐hypertension,. Under urethane anesthesia, male Zucker‐Fat rats (16 weeks of age, n=4), were instrumented to continuously record MAP, diaphragmatic EMG), and UAP. Both CSC were dissected, isolated and stimulated at 0.5 mA, with varying frequency (2.5, 5, 7.5, 10 and 20 Hz) and pulse widths duration (0.1, 0.2, 0.5 and 2.0 ms). Both frequency and pulse‐width dependent depressor response was observed with bilateral CSC stimulation. Lower frequency stimulations produced a 5% decrease in MAP and 12% decrease in UAP whereas the highest frequency of 20 Hz (0.5 mA, 0.2 ms kept constant) produced a 20% decrease in MAP and 25% decrease in UAP relative to baseline (panel A). The smallest pulse width (0.1 ms) produced a 3% decrease in MAP and 5% decrease in UAP whereas 2 ms produced a 25% MAP drop and 10% drop in UAP relative to baseline measures (panel B). Diaphragmatic changes were negligible with CSC stimulation. We conclude that bilateral electrical stimulation of the CSC effectively lowers MAP and UAP in an obesity‐hypertension rat model. In addition, both frequency and pulse width parameters can vary the hemodynamic response dramatically. Future studies will investigate optimal stimulation parameters and whether stimulation can lower hypertension in conscious Zucker‐Fat rats.Support or Funding InformationSupported by NIH1OT2OD023860‐01, Galvani BioelectronicsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Using Laser - induced breakdown spectroscopy system to determine the fertility of middle Iraqi soil

In this work, different soil samples were brought to study and analyse the element concentrations from different middle regions of Iraq (such as, Habbaniah, Garmah, Fallujah, and Tarmiah cities). Using laser-induced breakdown spectroscopy (LIBS) has been documented as an atomic emission spectroscopy (AES) technique. Laser-induced plasma utilized to analyse elements in materials (gases, liquids, and solids) in order to analyse elements in materials (gases, liquids and solid). The Nd:YAG laser excitation source at 1064nm with pulse width and pulse duration of 9ns is used to generate power density of 5.5 x 10 12 MW/mm 2 , with optical spectrum in the range 320 -740 nm. The soils of Habbaniyah and Garmah cities features have small concentrations of P II (0.08 a.u), K II (0.01 a.u), SiII (0.004 a.u) and Ca II (0.04 a.u) elements. However, the Fallujah city features have a good concentration of Ca II (0.14a.u). It is concluded that the soil in Fallujah city is better than Habbaniah, Tarmiah and Garmah cities of concentration elements.

Sound characterization of the European lobster Homarus gammarus in tanks

Experiments in marine behavioural ecology rely heavily on observations made in tanks. However, when studying acoustic behaviours of marine animals in confined volumes, the effects of reverberation must be characterized, something that has been overlooked in parts of the marine ecology literature. In this study, we characterized reverberation in tanks using an artificial sound source and examined the implications for bioacoustic studies using sounds emitted by the European lobster Homarus gammarus during feeding and in response to stress. Broadband and transient sounds commonly produced by crustaceans were severely impacted by reverberation such that their spectral characteristics and pulse width durations could not be assessed. In contrast, low-frequency sounds could be characterized in tanks, but not their source level. Based on these observations, we describe a simple methodology to identify which sound characteristics can be measured in tanks. When feeding, the lobsters produced broadband and transient sounds called ‘rattles’, similar to sounds reported for tropical spiny lobsters Palinurus longipes and P. argus. When stressed, H. gammarus vibrated its carapace, producing a low-frequency sound analogous to the ‘buzzing’ sound of the American lobster H. americanus. The potential role of species-specific sound is discussed; however, although our observations represent the first bioacoustic characterization of H. gammarus, additional behavioural studies are necessary to understand their ecological meaning.

Effects of electrical stimulus composition on cardiac electrophysiology in a rodent model of electroconvulsive therapy.

Background:No electroconvulsive therapy (ECT) study on humans or in animal models has so far examined whether differently composed electrical stimuli exert different cardiac electrophysiological effects at constant electrical dose. The subject is important because cardiac electrophysiological changes may provide indirect information about ECT seizure quality as modulated by stimulus composition.Materials and Methods:Adult female Wistar rats (n = 20/group) received fixed, moderately suprathreshold (18 mC) electrical stimuli. This stimulus in each of eight groups was formed by varying pulse amplitude, pulse width, pulse frequency, and stimulus duration. The electrocardiogram was recorded, and time and frequency domain variables were examined in 30 s epochs in preictal (30 s before electroconvulsive shock [ECS]), early postictal (starting 15 s after stimulation), and late postictal (5 h after ECS) periods. Alpha for statistical significance was set at P < 0.01 to adjust for multiple hypothesis testing.Results:Cardiac electrophysiological indices in the eight groups did not differ significantly at baseline. At both early and late postictal time points, almost no analysis yielded statistically significant differences between groups for four time domain variables, including heart rate and standard deviation of R-R intervals, and for six frequency domain variables, including low-frequency power, high-frequency power, and total power.Conclusions:Cardiac electrophysiological measures may not be helpful to identify differences in seizure quality that are driven by differences in the composition of electrical stimuli at constant, moderately suprathreshold electrical dose. The generalization of this conclusion to threshold electrical doses and to human contexts requires a study.