Number Of Pulses Research Articles

Low-noise soliton molecule generation with an in-phase controllable pulse number by third- and second-order dispersion compensation in an all-fiber erbium-doped oscillator

We report on the experimental results of high-order soliton molecule (SM) generation in an erbium-doped oscillator. The generation of 14 solitons with an average power of 48 mW, a pulse duration of 508 fs, a separation of 2.59 ps between pulses, and a repetition rate of 19 MHz at 1560 nm central wavelength was demonstrated. The stability of this generation was also evidenced by its low relative intensity noise (0.08% in the frequency range [10 kHz–1 MHz]), and a low Allan deviation of frequency repetition rate of 1.98⋅10−9 at an interval of 1 s (during 10 h of free-running measurements). Moreover, the accurate manipulation of SM order by changing the pump power was investigated; we showed the ability to generate with four, six, seven, nine, 10, 11, 13, and 14 pulses with high stable states between solitons. The change in the number of pulses occurred repeatably by increasing and decreasing the pump power, offering a stable source of a controllable number of pulses for potential applications in quantum computing.

Ultrafast thermal modulation dynamics during ripple formation induced by a femtosecond laser multi-pulse vortex beam

Abstract This work theoretically investigated the ultrafast thermal modulation dynamics during early formation of ripples on an Au film induced by femtosecond laser multi-pulse vortex beam irradiation. An extended two-temperature dynamics model that comprehensively considers optical interference modulation for the formation of seed ripples, transient reflectivity and non-equilibrium thermal transfer was self-consistently built to predict high-contrast ripple formation. The two-dimensional evolution of electron and phonon temperature modulations during ripple formation in a high non-equilibrium state of Au film were obtained via femtosecond laser multi-pulse vortex beam irradiation. It was revealed that ripple contrast can be significantly amplified by shortening the laser wavelength, increasing the pulse number, or enlarging the laser fluence of the vortex beam. Moreover, the electron–phonon coupling time during ripple formation is fully explored in detail. This study provides valuable insights into optimizing laser parameters for controlled high-contrast ripple formation on Au films.

Influence of electron radiation of spring barley seeds on phytopathogenic microflora

Under the conditions of a model pot experiment, the effect of electron irradiation on the phytopathogenic microflora of plant roots and leaves was studied. The studies were carried out on spring barley seeds of the Vladimir variety (reproduction 1), affected by helminthosporiosis (pathogen Bipolaris sorokiniana Shoem.), (natural infectious background). This pathogen causes root rot and leaf spot. The grain was irradiated using a wide-aperture electron accelerator “Duet” with a mesh plasma cathode and the output of the generated beam of a large cross-section into the atmosphere in doses of 1, 2, 3, 4 and 5 kGy. The total administered dose was increased by changing the number of pulses. The radiation dose rate was 100 Gy/pulse, the electron energy was 130 keV (mode 1) and 160 keV (mode 2). The depth of dose absorption did not exceed 300 μm. Based on the conducted studies on the effect of electron irradiation on root rot (pathogen Bipolaris sorokiniana) of spring barley, it was noted that in the tillering and heading phases, when irradiating seed material with a dose of 2 kGy in mode 1 (130 keV), the disease incidence and prevalence decreased by more than 1.5 times compared to the non-irradiated control. In the phase of full grain maturity, the highest value of root infestation (45–50%) and prevalence (95–100%) of Bipolaris sorokiniana were recorded, but statistically significant differences between the irradiated variants and the control were absent. The records of the damage of vegetative plants showed that in the tillering phase, for all irradiation variants in mode 1, the degree of damage to leaves 1–3 increased by 23% compared to the control, and in the heading phase, the degree of damage to the upper leaves (1–3) exceeded the control when irradiated at doses of 2–5 kGy (mode 1) and 1–5 kGy (mode 2) – 2.1–2.8 times for 1 leaf, 1.9–2.0 times for 2 leaves and 1.2 times for 3 leaves.

Optical pulse generation with programmable positions in an actively mode-locked optical cavity

A novel, to our knowledge, approach for generating optical pulses with programmable positions in an actively mode-locked (AML) optical cavity is proposed and experimentally demonstrated. In the AML, active mode locking occurs when the cavity gain exceeds one, and the cavity round trip time equals integer multiples of the repetition period of the electrical driving signal. The generated optical pulses are present at the positions where the optical cavity operates at its maximum transmission points. By periodically controlling the cavity gain with the driving signal, the maximum transmission points can be manipulated using a periodic arbitrary waveform, allowing the positions of the generated optical pulses within one round trip time to be programmed. Thanks to the superposition of the circulating optical field within the optical cavity, the pulse width of the generated pulses can be greatly compressed. In a proof-of-concept experiment, optical pulses with programmable pulse numbers, pulse intervals, and pulse position distributions in one period are generated by programming the driving signals. Optical pulse compression is also successfully verified. Optical pulses with an approximate 34-ps pulse width, ultra-low pulse interval (about 200 ps), and linear positional distribution are achieved.

Arrhythmogenicity of monophasic and biphasic PFA waveforms in a porcine model.

The potential risk of inducing ventricular arrhythmias was explored by employing pulsed field ablation (PFA) through the administration of both monophasic and biphasic waveform deliveries. PFA was applied to specific locations in the right ventricle (RV, n = 5 sites) in swine (n = 2), utilizing identical settings with consistent amplitude, pulse width, and a number of pulses for both monophasic and biphasic waveforms. PFA deliveries were precisely timed in 10-ms intervals across the entire T wave. Using monophasic waveforms, ventricular fibrillation (VF) was induced 7/7 times when PFA pulses were delivered during the T wave. Biphasic waveforms resulted in no ventricular arrhythmias when PFA was delivered across the entire duration of T wave. Our findings indicate that VF can be consistently induced with monophasic pulse waveforms, but not with biphasic pulse waveforms in a porcine model.

Artificial photoelectric synaptic devices with ferroelectric diode effect for high-performance neuromorphic computing

With the rapid advancement of artificial intelligence and machine learning, the demand for neuromorphic computing systems has intensified. High-performance artificial synaptic devices are crucial to achieving this objective. Ferroelectric diode artificial synaptic devices were prepared using aluminum-doped BaTiO3 (BTAO) thin films by a low-cost sol-gel method. These devices mimic the basic properties of biological synapses, such as long-term plasticity (LTP) and short-term plasticity (STP), under electrical stimulation. Additionally, the devices exhibit an excellent UV light response, enabling the transition from STP to LTP by adjusting the light pulse intensity, width, and number of pulses. Aluminum doping significantly enhances the ferroelectricity of BaTiO3 films, increasing the Pr from 2.31 µC/cm² to 9.08 µC/cm². By modulating the Schottky barrier through polarization, the BTAO films exhibit a switchable diode effect, which facilitates fine-tuning of the synaptic connection strength while maintaining synaptic stability. Recognition accuracies of 97.32% for the MNIST dataset and 87.48% for the Fashion-MNIST dataset were achieved by convolutional neural network simulations. These results suggest new possibilities for brain-like processing with ferroelectric diodes.

Nanoripples evolution on tungsten surface induced by two-pulse configuration

Tuneable shapes and uniformity of the laser-induced periodic surface structures (LIPSS) attract interest because of their diverse applications in both scientific research and technological advancements. In this work, we investigate the progression of regular one-dimensional (1D) LIPSS on a tungsten surface, examining its evolution based on the time delay between two laser pulses that initiate the formation of nanoripples. 1D-LIPSS were formed in the case of single-beam laser ablation with approximately 84 laser pulses. Two-dimensional (2D) LIPSS, including triangle, hexagonal, and square shapes, were generated by employing two cross-polarized laser beams (with wavelengths of 1030 nm and pulse durations of 40 fs) with no delay between the pulses. However, introducing a time delay of 2 picoseconds (ps) between the two cross-polarized laser pulses resulted in the division of the initially cross-oriented 2D-LIPSS into square-shaped structures, particularly along the spatially overlapped region of the laser beams. The emergence of triangle- and hexagonal-shaped two-dimensional laser-induced periodic surface structures (2D-LIPSS) is analyzed within the framework of a self-organization model, particularly in the context of solidifying the molten layer under cold temperature conditions on the tungsten surface. We examine the formation mechanism of LIPSS, attributing it to a combination of the self-organization/hydrodynamic mechanism initially, which transitions to the electromagnetic mechanism as the effective number of pulses increases.

Enfoque multitareas implementado en una minicomputadora para el control y monitoreo de un motor a pasos industrial

This paper presents the implementation of the multitasking approach on a Raspberry Pi single board minicomputer, with experimental results, of the control and monitoring of an industrial type Nema 34 stepper motor through a user interface that allows the configuration of the control operation and data visualization to interact with the physical devices. One of the tasks consists of generating a pulse width modulation that is sent to the DQ860HA driver to rotate the stepper motor considering 400 pulses per revolution, while the second task simultaneously counts the number of pulses produced by an encoder with a resolution of 100 pulses per revolution, which is coupled to the motor shaft. The use of low-cost computer equipment and open-source software makes the presented development can be considered as a frugal technology application for the control and monitoring of an industrial system, with experimental results that validate the correct operation of two tasks that must be executed simultaneously.

Design of a low-power Digital-to-Pulse Converter (DPC) for in-memory-computing applications

Data converters such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), digital-to-time converters (DTCs), time-to-digital converters (TDCs), among others, are considered some of the most essential blocks in the field of integrated circuit design. In this work, we introduce a novel type of data converter known as the Digital-to-Pulse converter (DPC) and present its novel analog flow circuit implementation. The DPC system is a critical component in emerging artificial neural network accelerators and in-memory computing systems. The DPC system presented in this study offers two distinct operating modes. The first mode is the generation of a single pulse with a width that is modulated by the digital input. The second mode is an n-bit digital to discrete pulse converter, where the number of generated pulses is directly related to the value of the digital input. The proposed DPC system offers designers a high level of flexibility in shaping the characteristics of the output pulses, including the number of pulses, pulse width, and pulse amplitude. This empowers designers to accommodate different application requirements and scenarios effectively. The proposed circuit has been verified and tested using Virtuoso Cadence circuit tools in 180 nm CMOS technology with post-layout simulation and analysis. The results indicate a significant enhancement in average power consumption (∼12×), layout area (∼5×), and Latency (∼1.4×) with the proposed system compared to the digital Register Transfer Level (RTL) implementation under a power supply of 1.8V and a clock frequency of 1 GHz in the Application Specific Integrated Circuits (ASIC) flow. This demonstrates the suitability of the proposed system for low-power and high-speed applications.

Colloidal Quantum Dots‐Based Photoelectrochemical‐Type Optoelectronic Synapse

AbstractCurrent artificial neuromorphic systems are mainly constructed using solid‐state optoelectronic synaptic devices, limiting their potential artificial intelligence applications in liquid medium. Here, colloidal CuInGaSe/ZnSe quantum dots (QDs) with environment‐benign feature and broad visible light absorption are prepared to fabricate a photoelectrochemical (PEC)‐type optoelectronic synaptic device operating in aqueous electrolyte, enabling unique biological synaptic behaviors including paired‐pulse facilitation (PPF), short‐term plasticity (STP), long‐term plasticity (LTP) and learning‐forgetting‐relearning process when simulated by optical pulses with various wavelength, pulse number, frequency, power density, and applied voltage. These results demonstrate the feasibility of building PEC‐type optoelectronic synapses using colloidal QDs, paving the way to realize available optoelectronic synaptic devices for prospective underwater artificial intelligence technology.

Comparison of microwave and pulsed electric field methods on extracting antioxidant compounds from Arvaneh plant (Hymenocrater platystegius Rech. F)

Improving the quality of extracts derived from medicinal plants is a critical concern due to their extensive use across various industries. The Arvaneh plant (Hymenocrater platystegius Rech. F), a species native to the Khorasan province in Iran and belonging to the mint family, was the focus of this study. We optimized the extraction of Arvaneh plant using both microwave (MW) and pulsed electric field (PEF) techniques. The MW method was tested at different processing times (90, 180, and 270 s) and power levels (180, 540, and 900 W), while the PEF method was evaluated with varying electric field intensities (0.25, 3.25, and 6.25 kV/cm) and pulse numbers (10, 45, and 80) using a central composite design (CCD). The results revealed that extraction efficiency, total phenolic content, and total flavonoid content were significantly higher with the PEF method compared to the MW method (p < 0.05). Moreover, the PEF technique showed superior performance in preserving the antioxidant properties of the extract, as assessed by DPPH and FRAP methods. GC/MS analysis confirmed the presence of 27 bioactive compounds in the Arvaneh extract obtained through PEF-assisted extraction. In conclusion, the PEF method proved to be highly efficient for extracting bioactive compounds from the Arvaneh plant.

Universal quantum processors in spin systems via robust local pulse sequences

We propose a protocol to realize quantum simulation and computation in spin systems with long-range interactions. Our approach relies on the local addressing of single spins with external fields parametrized by Walsh functions. This enables a mapping from a class of target Hamiltonians, defined by the graph structure of their interactions, to pulse sequences. We then obtain a recipe to implement arbitrary two-body Hamiltonians and universal quantum circuits. Performance guarantees are provided in terms of bounds on Trotter errors and total number of pulses. Additionally, Walsh pulse sequences are shown to be robust against various types of pulse errors, in contrast to previous hybrid digital-analog schemes of quantum computation. We demonstrate and numerically benchmark our protocol with examples from the dynamics of spin models, quantum error correction and quantum optimization algorithms.

Experimental study on the effect of discharge parameters of high-frequency nSDBD on the multi-point ignition characteristics of NH3/air mixture

Multi-point ignition by high-frequency nanosecond surface dielectric barrier discharge (nSDBD) offers the potential to enhance the combustion speed of NH3/air mixtures. This paper investigates the ignition process of high-frequency nSDBD in NH3/air mixture. Firstly, the morphology of the discharge channels is studied, and it is found that before the formation of a clear flame kernel, with the increase of the pulse number, the discharge filament length increases first and then stabilized, while the discharge filament number decreases from about 20 to around 12. Secondly, the influence of the mixed gas state on discharge characteristics is studied, and it is observed that as the gas pressure increases, the single pulse energy decreases and the discharge filament length decreases, but the deposition energy per unit length did not change significantly. The increase in NH3 concentration leads to a slight decrease in discharge energy and length. Finally, the effect of the flame kernel on discharge morphology is studied, and it is found that when the flame kernel is small, the discharge filament trees change from dispersed to coincident, and the discharge energy is concentrated. When the flame kernel is large, the discharge filament trees mostly transform into overlapping types, and the number decreases.

Electron-positron pair creation under Gaussian and super-Gaussian pulse trains

The electron-positron pair (EPP) creation under Gaussian and super-Gaussian pulse trains are studied by the computational quantum field theory (CQFT) in the single-photon regime. The details of the EPP creation are studied from the time evolution of the EPP number, energy spectra and spatial distribution of the electrons. The results indicate that the final created EPPs is the non-linear accumulation of the multi-pulses, which depends on the time interval, pulse shape and pulse number. The optimal time interval can be chosen based on the pulse resonance condition, which is derived by the perturbation method. Besides, steeper super-Gaussian pulses and adding more pulses facilitate the EPP creation as well. The results indicate that, under optimal multi-pulse parameters, the number of the EPPs obtained is much larger than the sum of the EPPs created under the same number of single pulses. This finding not only can enhance the EPP creation, but also can improve the multi-pulse utilization and guide future experimental research on the EPP creation.

The effect of the age at the time of targeting a lead implantation on the difficulty with the transvenous lead extraction technique

Abstract Background In transvenous lead removal procedures, the number of years since the lead implantation is an indicator of procedural difficulty and complications. However, even with the same number of years since the lead implantation, we considered the possibility that a younger age at the time of the implantation (AoI) would increase the difficulty of the procedure. Objective To elucidate the procedural difficulty in the transvenous lead extraction procedure according to the age at the time of targeting the lead implantation. Method A total of 471 consecutive transvenous lead extraction cases were analyzed. The patient AoI of the oldest lead in extraction procedure cases was divided into two groups: those younger than 60 years (implant age &amp;lt;60 yrs old: AoI&amp;lt;60) and those older than 60 years (implant age ≧60 yrs old: AoI≧60). The analysis was conducted by the number of years since the lead implantation (&amp;lt;10 years: group A, 10 to 20 years: group B, and &amp;gt;20 years: group C). Results The number of AoI&amp;lt;60 and AoI≧60 patients were 60 and 254 (Group A), 51 and 56 (Group B), and 41 and 9 (Group C). The patient age significantly differed among the groups between an AoI&amp;lt;60 and AoI≧60 (group A: 51.7 vs. 77.1; P&amp;lt;0.001, group B: 61.6 vs. 83.1; P&amp;lt;0.001, group C: 71.2 vs. 88; P&amp;lt;0.001). But the oldest dwell time (years) was similar for all groups (group A: 4.6 vs. 4.2; P=0.324, group B: 14.2 vs. 13.5; P=0.148, and group C: 25.7 vs. 22.6; P=0.097). The complete removal rate (group A: 97.7% vs. 98.4%; P=0.722, group B: 90.4% vs. 93.3%; P=0.567, and group C: 78.05 vs. 90.95; P=0.337) and major complication-free rate (group A: 98.8% vs. 100%; P=0.391, group B: 96.2% vs. 100%; P=0.125, and group C: 90.2% vs. 100%; P=0.281) were not statistically significant in all groups but were higher for an AoI≧60. An AoI&amp;lt;60 resulted in a longer procedure time (group A: 78.4 min. vs. 65.3 min.; P=0.006, group B: 96.0 min. vs. 72.3 min.; P=0.002, and group C: 100.9 min. vs. 94.8 min.; P=0.709), longer fluoroscopy time (group A: 12.0 min. vs. 10.2 min.; P=0.247, group B: 19.2 min. vs. 11.6 min.; P=0.017, and group C: 22.2 min. vs. 16.0 min.; P=0.008), and higher number of laser pulses (group A: 779.6 vs. 433.7; P=0.002, group B: 2089.6 vs. 1032.9; P=0.017, and group C: 1509.3 vs. 831.5; P=0.201) in all groups. Conclusion This study suggested that the difficulty of transvenous lead extraction procedures may increase with a younger AoI, even if the lead dwelling time is the same.

Quantification of hemolysis rates from pulsed field ablation

Abstract Introduction Pulsed electric fields induce hemolysis of red blood cells as a dose-dependent effect of the electric field. Voltage pulsations induce a transmembrane potential across the cell membrane and either open up or create pores in the red cells. In isotonic conditions, the pores allow passage of potassium and sodium ions but not sucrose or hemoglobin, and leakage of ions leads to an osmotic imbalance which in turn causes a colloidal hemolysis of the red cells. Objective To quantify hemolysis rates during pulsed field ablation (PFA). Methods We created a computational model of PFA to determine the total volume of blood hemolyzed from each pulse during catheter ablation using pulsed field energy. The percentage hemolysis was calculated as a function of electric field intensity utilizing existing published experimental data. A single electrode delivering a single pulse of 100 microseconds duration was modeled at voltages of 1 kV, 1.5 kV, and 2 kV. Results The total volume of hemolyzed blood per pulse increased with increasing applied voltage (Figure). For 2 electrodes in direct tissue contact, the electrode surface exposed to the blood pool generated 19 microliters of hemolyzed red blood cells with a single pulse of a 2 kV field strength. In the case of a single pulse train consisting of 50 pulses, using a catheter configuration with 20 electrodes, an estimate of total volume per pulse train is approximately 9.5 mL of hemolyzed blood. In the case of electrodes not in direct contact with endocardial tissue, and exposed to the blood pool, up to double this volume could be anticipated per pulse train. Hemolyzed volume can be reduced with better tissue contact (reducing exposure to blood), or potentially with the use of irrigation to dilute the local red blood cell concentration. Increased tonicity of the irrigant fluid may also reduce the osmotic pressure increases that result in hemolysis. Conclusions Typical voltages utilized in pulsed field ablation can cause significant hemolysis, which is exacerbated by inadequate tissue contact. A greater number of electrodes and number of pulses delivered increases the risk, whereas better tissue contact, and the use of irrigation, may reduce it.

Achieving high piezoelectric performance in Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric single crystals through pulse poling technique

To maximize the piezoelectric performance of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, a pulse poling (PP) method is proposed in this study. This study investigates the effects of pulse poling on the piezoelectric and dielectric properties of these PMN–PT single crystals and explores the polarization rotation mechanisms. Our findings indicate a significant improvement in the piezoelectric properties postpulse poling. The optimal PP conditions are identified as 30 pulse numbers at a pulsed electric field of 5 kV/cm. The dielectric constant ɛT33/ɛ0 and piezoelectric coefficient d33 of PMN–0.28PT post PP are 7000–7700 and 2200–2530 pC/N, respectively, representing increases of 49% and 66% compared with those of postdirect current poling (DCP). Additionally, the domain structures of the PMN–0.28PT single crystals after various DCP and PP treatments are examined and compared using piezoelectric force microscopy. The enhanced piezoelectric properties are attributed to the finer domain structures, as well as increased domain wall density achieved through PP. This research introduces a novel domain engineering approach to improve the electromechanical properties of relaxor ferroelectric single crystals.

Randomised controlled trial comparing different intersession intervals of intermittent theta burst delivered to the dorsal medial prefrontal cortex

BackgroundIntermittent theta burst stimulation (iTBS) is a form of repetitive transcranial magnetic stimulation (rTMS) that can be administered in a fraction of the time of standard rTMS. Applying multiple daily...

Q-switched Nd: YAG Fundamental and Second Harmonic Wavelengths Impact on Preparing Nb2O5 Thin Films by a PLD Technique: A Comparative study

We aim to study and investigate the structural, optical, topographical, and morphological properties of Nb2O5 thin films deposited under vacuum Q-switched Nd: YAG pulsed laser for the first time to the best of our knowledge. The obtained results of this study can contribute in different fields of applications including the optoelectronic and biomedical fields. The fundamental (1064 nm) and the visible second harmonic (532 nm) wavelengths were utilized for this purpose. The laser energy was fixed at 657 mJ. The number of pulses and the substrate temperatures were 200 laser shots and 450 ºC, respectively. The observed X-ray diffraction patterns were assigned for T-Nb2O5 that refers to the orthorhombic and H-Nb2O5 which is related to the monoclinic phases supported by Raman spectra analyses. Nb2O5 thin film deposited by Nd: YAG fundamental wavelength (1064 nm) showed a thicker film, a higher surface roughness and, on average, a larger particles size It also provided better matching of the lattice d-spacing with the standard d-spacing obtained by JPCDs cards 00-030-0873 and 00-009-0372. The optical properties including the band gap values for both direct and indirect transitions were estimated with the lower gap was reported for the thin film prepared at the fundamental wavelength. The photoluminescence analyses supported that the transitions of both prepared films were indirect. FE-SEM clarified the surface morphology of each prepared film. The EDX analyses provided the elemental compositions and the purity of the Nb2O5 prepared films.

Temperature Effects on the Optical Properties of Bismuth Nanoparticles Prepared by PLAL for Antibacterial Activity

Bismuth nanoparticles (Bi NPs) constitute a promising technology for combating infectious illnesses and bacterial resistance to antibacterial treatments. Bi NPs were synthesized by Pulsed Laser Ablation in Liquid (PLAL) using a 532 nm second-harmonic generation Nd:YAG laser. Bi NPs samples were prepared in 10, 35, 50, 75, and 90 ˚C water for various laser energies and number of laser pulses. Ultraviolet-visible (UV-Vis) spectra measurements revealed a characteristic plasmonic absorption band indicative of metallic bismuth nanosized particles. Field emission scanning electron microscopy (FESEM) analysis showed that the water temperature during the ablation process affected the size and morphology of Bi NPs. The average Bi NP size at 60 ˚C was 28 nm, considerably smaller than the 55 nm average observed at 10 ˚C. The antimicrobial properties of Bi NPs against two opportunistic pathogens, E. coli and S. aureus, were assessed. For S. aureus, the inhibition zone of Bi NPs prepared at 60 ˚C was greater than that of samples prepared at 10 ˚C. Further, Bi NPs exhibited lower potency against E. coli than S. aureus in both samples.