Pulse Modulation Research Articles

Synaptic transistor based on PVK mixed with oxadiazole and its logic gate application

Because of the simplicity of device integration, high energy efficiency, and the ability to achieve robust neuromorphic calculation, the explore of artificial synaptic devices has attracted extensive attention. In this work, an electronic synaptic organic transistor based on a mixture of p-type polymer and n-type small molecule semiconductor colloids by spin coating was designed to achieve synaptic plasticity. Typical synaptic behavior, including excitatory postsynaptic current and paired-pulse facilitation, is simulated using electrical impulse stimulation. In addition, the transition from short-term plasticity to long-term plasticity were realized by adjusting input pulse operation. More importantly, the logic function of “AND” and “NAND” gate is designed and realized based on the operability of organic transistor pulse modulation. Our work offers a new approach for the exploitation of organic multifunctional neuromorphic electronic devices.

Development of a 40-kV Pulse Modulator and Experiment With Industrial Odor Removal Using Nonthermal Plasma

Development of a 40-kV Pulse Modulator and Experiment With Industrial Odor Removal Using Nonthermal Plasma

A Hybrid Weight Quantization Strategy for Memristive Neural Networks

Due to the ability to store data and process information, the memristor-based neuromorphic system has attracted extensive attention. Its efficient parallel computing approach allows it to implement neural networks in hardware. However, due to the limitation of the range of memristor conductance, it is difficult to represent high-precision weights in memristive neural network. During the off-chip learning, it is crucial to find an efficient weight quantization scheme and map it to the memristor array. Therefore, a hybrid weight quantization strategy that combines uniform and non-uniform quantization is proposed to overcome these problems. Specifically, the curve fitting of pulse modulation for tantalum oxide-based memristor is carried out, and the mapping rules of weights are proposed to simplify the process of reading verification. Furthermore, the hybrid quantization strategy is proposed and applied to a multilayer perceptron and a convolutional neural network, respectively. The effectiveness and robustness of the hybrid quantization scheme are verified in the MNIST dataset. Experiments show that the proposed hybrid quantization scheme can achieve 99.26% accuracy at 4 bits and tolerate 20% noise interference. The simulation results in this paper also provide an effective solution for the hardware implementation of memristive neural networks.

The hybrid pulse amplitude width modulation scheme: high efficiency technique for dimmable VLC systems

Abstract Visible-light communications (VLC) is an environmentally friendly optical wireless communication (OWC) technology that operates in the 400–800 THz frequency band. It is currently a critical technology for 5G and 6G wireless indoor applications due to its high data rates, low latency, and superior reliability. Intensity modulated direct detection (IM/DD) is widely used in VLC systems. A channel modulation scheme is designed using L-level pulse modulation techniques such as on–off keying (OOK), amplitude modulation (PAM), position modulation (PPM), and the width modulation (PWM). We introduce a novel hybrid modulation scheme n-M-PAWM based on both PAM and PWM schemes to improve throughput and significantly increase power and spectrum efficiency in VLC communication systems. The performance of our proposed hybrid n-M-PAWM scheme is studied in several aspects, including the number of transmitted bits per symbol, average BER, information rate ratio (IRR), PAPR, bandwidth, and power requirement. In an extremely noisy VLC system, the proposed 2-M-PAWM modulation outperforms both PPWM and PAPM modulation schemes due to its better BER performances. Additionally, we examine the performance of the VLC system in terms of spectral efficiency (SE) using our proposed PAWM-based dimming control system by varying the number of pulses transmitted during one symbol period. We demonstrate through simulation results that our PAWM-based dimming control system performs significantly better compared to the other pulse modulation schemes. All results of this research show that our proposed hybrid PAWM modulation scheme has high potential for VLC technology in indoor and noisy environments.

Error performance analysis for chaotic pulse width position modulation in free space optical communication system

Abstract In this paper, a pulse time modulation method called chaotic pulse width position modulation (CPWPM) is studied for free space optical communication system. This is a digital modulation technique that combines pulse position modulation and pulse width modulation with chaos. In this scheme, the binary information is carried by both the position and width of the pulses, which are modulated by a chaotic signal. Hence, on a single pulse, two bits of information are encoded, which results in higher bit rates, better privacy, and larger effective bandwidth as compared to chaotic pulse position modulation (CPPM) and chaotic pulse width modulation (CPWM) techniques. Probability of error is investigated for different FSO scenarios, i.e., varying turbulence conditions and link lengths for CPWPM scheme. Finally, the performance of CPWPM-FSO system is compared with a commonly used differential chaos shift keying (DCSK) scheme. CPWPM-FSO system shows comparable results as DCSK-FSO system (for probability of error, P e = 10−4 average signal-to-noise ratio (SNR) required for DCSK and CPWPM scheme is 40 dB and 41 dB, respectively, for same length and system conditions), while data rate is doubled in latter, and this verifies the validity of using CPWPM in FSO communication system.

Сравнительный анализ математических описаний и методов широтно-импульсной модуляции

The article considers the mathematical description and comparison of the most common methods of pulse-width modulation (PWM) for a three-phase voltage inverter, namely vector PWM, PWM with third harmonic premodulation and classical PWM. In contrast to the classical mathematical description of PWM, a description is presented that is close to the implementation of modulation using modern microcontroller technology. The classic representation of PWM is based on comparing two signals. In this representation, the modulation pulse occurs at the moment when the modulating function is greater in value than the reference signal. When implementing PWM by a microcontroller, the pulse is placed within the period symmetrically with respect to the middle of the interval, while the pulse width is determined by the average value of the voltage modulating function. With a different mathematical description of PWM, the pulse is located differently within the modulation interval. There are presented the results of modeling and compares the mathematical descriptions of PWM methods according to the criterion of minimum dispersion of the current flowing in the load. As a result of the comparison, it was revealed that the same, differently described PWM algorithm gives different results. A comparison of vector PWM with a modified vector PWM was made. The modification consists in applying a dynamic pulse shift algorithm in such a way as to obtain a minimum of current dispersion in the load. Comparison of PWM methods was carried out at different frequencies of the reference signal; a static RL circuit was used as a load when simulating a three-phase voltage inverter. The results obtained allow us to recommend a pulse shift algorithm for implementing PWM in voltage inverters operating at relatively low PWM frequencies. Minimization of the current dispersion makes it possible to obtain improved energy and vibration-noise characteristics of the electric drive.

MODERNIZATION OF THE HELIUM ION ACCELERATOR MICROWAVE POWER SUPPLY SYSTEM

The high-voltage rectifier modernization, which is part of helium accelerator (PSS-4) high-frequency system, is described. The rectifier supplies the pulse modulator with direct current energy. The valves of the modulator used are mercury thyratrons. Modernization involves replacing thyratrons with semiconductor diodes. In the article, a comparative analysis of the parameters of thyratrons and diodes, which are supposed to be replaced by thyratrons, is carried out, and the expediency of such a replacement is substantiated.

Effects of two weak femtosecond pulse seeds on promoting rogue wave generation

We numerically simulate the enhancement of rogue wave generation by adding two weak femtosecond pulse seeds at two fixed modulation frequencies. The results show that two weak pulse seeds have better promotion effect on rogue wave generation than one weak pulse seed. In addition, the modulation depth and pulse width of the weak pulse seeds also affect the generation of rogue wave. With the increase of the modulation depth and pulse width of the two weak pulse seeds, the control effect of rogue wave gradually becomes better.

Non-Isolated Current-Fed Series Resonant Converter with Hybrid Control Algorithms for DC Microgrid

Module-level power electronics can optimize the power generation of photovoltaic panels, which requires a simple topology structure, high power conversion efficiency, and wide voltage gain, corresponding to irradiance variations. This paper proposes a non-isolated current-fed L-C series resonant converter and its control algorithms. The proposed converter can obtain a buck–boost voltage gain with the hybrid control algorithm utilizing the switching frequency modulation and asymmetric pulse width modulation. The proper power stage design can guarantee the soft-switching capability for the entire operating range. Also, the control strategy is designed to obtain a small rms current. The operational principle of proposed converter is analyzed in order to design the resonant tank and control strategy. The performance of designed converter can be verified with the experimental results with a 500 W prototype converter.

High-Sensitive Fiber Optical Accelerometer With Pulse Modulation of Optical Flow Intensity

This research addresses to the design and development of a precision fiber optical sensor of acceleration using pulse modulation of optical flow intensity. The accelerometer proposed in this article can theoretically reach a threshold sensitivity better than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> g (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) for acceleration near g and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> g (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) for ultralow acceleration. In addition to the high resolution, it is possible to adjust the frequency of acceleration measurement by changing the parameters of the sensor, which allows the device to be applied to specific tasks. In our experiment, we assessed the changes in acceleration constrained by seismic noise. As a result, the noise levels were measured on the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> g for the vertical component and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> g for the lateral components. Furthermore, the minimum detectable acceleration changes were observed at levels of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> g for the vertical component and 5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> g for the lateral components. The proposed acceleration sensor has several advantages compared to current developments, such as immunity to external electromagnetic fields and measurement of time instead of measuring optical force to determine acceleration. Moreover, theoretically, the relative error level is comparable to the advanced developments in the field of acceleration measurement, while the mass and size characteristics of the proposed sensor are superior to conventional measuring instruments.

Effect of Ho:YAG laser on kidney tissue with Virtual Basket™ and Bubble Blast™ pulse modulation: an experimental ex vivo study.

There is a lack of studies in the literature on effects of Virtual Basket™ (VB) and Bubble Blast™ (BB) laser pulse modulations of the Ho:YAG laser on tissue. We aimed to compare the effects of standard modulation (SM), VB, and BB pulse modulations of Ho:YAG laser on kidney tissue. An ex vivo experiment was conducted using veal kidneys. The Quanta System Cyber Ho 100W laser generator with a broad setting spectrum at 15-80W, 10-40Hz, 1.5-2J, and medium pulse duration were tested. Incision depth (ID), vaporization area (VA), coagulation area (CA), and total laser area (TLA = VA + CA) were evaluated. Histopathological measurement outcomes were grouped as a low-power group (15, 20, and 30 W) and a high-power group (40, 60, and 80W) according to the power outputs used. A total of 108 experiments were performed. In saline and high-power output (40, 60, 80 W), mean VA, TLA, and ID, histopathological measurements were higher in BB pulse modulation than VB and SM pulse modulations (p: 0.03, p: 0.001, and p: 0.003, respectively). In contrast, mean CA and LE measurements were higher in SM than in VB and BB pulse modulations (p < 0.001 and p < 0.001, respectively). There was no statistically significant difference in mean histopathological measurements of VA, CA, TLA, and ID, among SM, VB, and BB pulse modulations in the low-power output group in saline (p > 0.05). VB can allow controlled dissection, as it does not create a large VA during surgical procedures. BB should be used in a controlled manner in soft tissue surgery due to its strong effect on tissues.

A Distributed High-Voltage Arbitrary Waveform Generator Based on Versatile Pulsed Power Module

A Distributed High-Voltage Arbitrary Waveform Generator Based on Versatile Pulsed Power Module

Tailing phenomenon in high voltage solid-state pulse modulators: Analyzing and modeling

In many applications of high-voltage solid-state pulse modulators (SSPMs), the expected square pulsed shape is difficult to be generated and also there exists a long falling edge (also known as the “tailing”). In some fields that strictly need squared pulses, tailing will restrict the application of SSPMs. Although topological solutions have been proposed to eliminate the tail, its formation and regulatory factors are still not clear. Based on the classic switch–capacitor circuit, the tailing model is discussed and established for stacked and non-stacked SSPMs in this paper, which can help predict the pulsed tailing of SSPMs under various loads. The circuital factors (stage number, parasitic inductance, etc.) of the pulsed tail are studied. Meanwhile, the suggested tailing criteria for different load scenarios are proposed. The experiment verifies the accuracy of the tailing model. Finally, the applicable conditions of the tailing model are discussed. This model can not only help explain the mechanism of tailing but make predictions of tailing in SSPMs.

Modulation Technique Design of An Improved Zero Common Mode Voltage (CMV)

Voltage imbalance of neutral-point and CMV are hot issues in the research of three-level inverters. This paper first introduces the three-level topology of the neutral-point clamped (NPC) inverter. Aiming to eliminate CMV of three-level NPC and balance the voltage of the neutral point simultaneously, a virtual space vector pulse modulation (VSVPWM) strategy is proposed. Virtual voltage vectors of this strategy are composed of 3 medium vectors. The voltage of the neutral point is balanced since the average current of the neutral point is 0. Therefore, the balance index is introduced to redefine virtual voltage vectors, so the voltage of the neutral point can recover quickly when the capacitors’ voltage of the dc-link is imbalanced.

High-damage-threshold mid-infrared saturable absorber enabled by tantalum carbide nanoparticles.

A stable mid-infrared saturable absorber with a high damage threshold is urgently required for high-performance optical modulation in the mid-infrared regime. Here, we demonstrate stable mid-infrared erbium-doped fiber laser generation modulated by tantalum carbide nanoparticles (TaC NPs) experimentally. The TaC NPs show high physicochemical stability, obvious nonlinear optical absorption, and a high damage threshold. By introducing the TaC-based saturable absorber into an erbium-doped fiber laser, stable nanosecond pulses can be successfully delivered with a minimum pulse duration of 575 ns and signal-to-noise ratio of over 40 dB. The experimental results show that TaC NPs can act as a stable mid-infrared pulse modulator, and may make inroads for developing highly stable broadband optoelectronic devices.

Modulation of Exchange Bias in La0.35Sr0.65MnO3/La0.7Sr0.3MnO3 through Volatile Polarization of P(VDF‐TrFE) Gate Dielectric

AbstractElectric‐field regulation of magnetic properties in perovskite manganites has attracted much attention for its potential in spintronics. For antiferromagnetic perovskite manganites, fewer studies are reported due to technological difficulties in probing their magnetic properties. Here, negative exchange bias (EB) is realized in epitaxial antiferromagnetic/ferromagnetic manganite bilayers with atomically flat interfaces. The low‐voltage pulse modulation of EB is demonstrated using the field‐effect device geometry with the ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene as a dielectric gating layer, antiferromagnetic La0.35Sr0.65MnO3 (AF‐LSMO) as pinning layer, and ferromagnetic La0.7Sr0.3MnO3 (FM‐LSMO) as conduction channel. Instead of using non‐volatile polarizations to control the EB, volatile polarizations in ferroelectric field effect transistors are suggested to be capable of modulating the EB. With high‐resolution electron microscopy and spectroscopy, the non‐volatile regulation of EB is attributed to the creation/annihilation of oxygen vacancies in the AF‐LSMO layer via low‐voltage pulses. This study reveals the effect of volatile electric polarizations in ferroelectric field effect devices and highlights the potential for low‐voltage pulse control of the physical properties in antiferromagnetic perovskite oxide insulators.

Effects of Pulsed Light on Mycelium Growth and Conidiation in Aspergillus oryzae

Understanding how Aspergillus oryzae responds to light is critical for developing efficient light regulation strategies in the brewing and waste treatment industries. Although continuous light is known to restrict A. oryzae, little is known about A. oryzae’s sensitivity to light with photoperiod. In this study, we used pulse wave modulation (PWM) to generate nine pulsed blue light (PBL) treatments with varying peak light intensities and frequencies. The effect of PBL on A. oryzae was then compared to that of continuous blue light (CBL). Our findings showed that A. oryzae GDMCC 3.31 mycelium developed faster and produced more conidia under PBL with specific peak intensities and frequencies than under CBL treatment when the light dose and average light intensity were held constant. The colony diameter and conidia count under the two PBL treatments (PL-20_40%_1 Hz and PL-400_20%_10 kHz) were 1.13 and 1.22 times greater than under the CBL treatments, respectively. This different response may be mainly attributed to A. oryzae’s adaptation to the light–dark cycles in nature. Furthermore, an interactive effect was found between peak light intensity and frequency. This work includes pulsed wave modulation as a new factor that influences the A. oryzae photoresponse and recommends it in the development of light regulation methods for fermentation.

Radiofrequency pulse modulation of the penile dorsal nerve for the treatment of premature ejaculation: evaluation of effectiveness

Introduction. Premature ejaculation (PE) is the second most common male sexual dysfunction with a significant negative impact on quality of life. A significant number of conservative and surgical methods for the treatment of PE are proposed, but their effectiveness and, in some cases, safety, remain the subject of discussion.Objective. To study the effectiveness of pulsed radiofrequency impulse neuromodulation (RPN) with different modes on the penile dorsal nerve in treatment of patients with premature ejaculation.Materials &amp; methods. Two groups of PE-patients participated in a prospective multicenter study: Group 1 — 11 patients aged 22 – 34 years; Group 2 — 12 patients aged 23 – 34 years. Group 1 received pulsed RPN at a temperature of 42°C, a stimulation frequency of 2 Hz, 45 V, and a duration of 180 seconds; in Group 2 — pulsed RPN at a temperature of 50 °C and the same frequency and duration of stimulation as Group 1. All patients before and after treatment measured intravaginal ejaculation latency time (IELT) and completed a premature ejaculation profile (PEP). The results were evaluated after 30 days.Results. In both groups, there was a statistically significant increase in IEDT and PEP. Thus, in Group 1, IELT increased from 58 to 101.9 seconds, PEP from 3.8 to 12.6 points. In Group 2, IELT increased from 66.5 to 210.9 seconds, PEP from 3.2 to 12.6 points. At the same time, in Group 2, IELT increased by 107% more than in Group 1. No significant side effects were observed in both groups.Conclusion. RPN appears to be a very promising treatment for premature ejaculation, as it is a minimally invasive, safe, and reversible procedure. The technique of influencing the penile dorsal nerve at an electrode temperature of 50 °C compared to 42 °C seems to be more effective, however, additional studies are needed.

Engineering activatable promoters for scalable and multi-input CRISPRa/i circuits

Dynamic, multi-input gene regulatory networks (GRNs) are ubiquitous in nature. Multilayer CRISPR-based genetic circuits hold great promise for building GRNs akin to those found in naturally occurring biological systems. We develop an approach for creating high-performing activatable promoters that can be assembled into deep, wide, and multi-input CRISPR-activation and -interference (CRISPRa/i) GRNs. By integrating sequence-based design and in vivo screening, we engineer activatable promoters that achieve up to 1,000-fold dynamic range in an Escherichia coli-based cell-free system. These components enable CRISPRa GRNs that are six layers deep and four branches wide. We show the generalizability of the promoter engineering workflow by improving the dynamic range of the light-dependent EL222 optogenetic system from 6-fold to 34-fold. Additionally, high dynamic range promoters enable CRISPRa systems mediated by small molecules and protein-protein interactions. We apply these tools to build input-responsive CRISPRa/i GRNs, including feedback loops, logic gates, multilayer cascades, and dynamic pulse modulators. Our work provides a generalizable approach for the design of high dynamic range activatable promoters and enables classes of gene regulatory functions in cell-free systems.

A microplasma device and its switching behavior triggered by modulated pulse signal

Since the physical and electrical properties of plasmas are similar to those of semiconductor devices, plasma devices have been proposed to be good candidates for switching controlled devices when applied in harsh environments. In the proposed paper, a microplasma device with a dielectric barrier structure constructed with three electrodes (two driven electrodes and one trigger electrode) is fabricated, and the electrical characteristics of the proposed device are investigated in 2 kPa of argon. From the experimental results, a stable conducting current is obtained through the two driven electrodes in the device due to gas discharge, since the hysteresis characteristic of discharge plasmas (discharge is still maintained when the driven voltage is below the breakdown voltage of the gas because of the existence of residual charge particles), the device can be switched from the OFF to ON state through pre-discharge by a pulse applied to the trigger electrode. While in the device ON state, this trigger voltage attracts channel charged particles to the surface of the dielectric layer, quenching the discharge plasma current and the device can be switched from ON to OFF state. The trigger pulse that makes the device switch successfully goes from single to continuous up to 80 kHz. The influence of pulse parameters on the switching process is also investigated, pulse amplitude and pulse width are found to be important to determine whether the device can switch ON or OFF, peak current after switching, and the response speed of switching ON current; however, these switching parameters are barely affected by the rise and fall time of the pulse. The results are significant for the application of microplasma switching devices.