Pulse Duty Cycle Research Articles

Enhanced performance of electrodeposited Ni-SiC plating as an alternative to electroplated chromium deposits: the effect of pulse duty cycle

Ni-SiC composite coating was prepared by the electrodeposition under the pulse current as an alternative for the environment polluted and human cancerogenic hard chromium plating. The microstructure and tribological performance of the composite coating under different duty cycles were studied. The results showed that the mechanical performance of the Ni-SiC can be optimized by adjusting the pulse duty cycle. With the increase of the duty cycle, the grain size of the Ni matrix are refined and the friction coefficient of the coating are decreasing. Composite coating obtained with 80% duty cycle possesses the lowest wear volume during the friction and wear test. The effect of the duty cycle on the microstructure and tribological performance of the composite coating were discussed. Moreover, the co-deposition mechanism of Ni atoms and the SiC particles under the pulse current were discussed.

Spectral Characteristics of Terahertz Quantum Cascade Lasers

Terahertz quantum cascade lasers (THz QCLs) are prospective radiation sources for high-resolution gas spectroscopy. A wide range of operating frequencies (from 1.2 to 5.4 THz), a narrow generation line (up to 10 kHz), the ability to operate on several radiative transitions (two-color lasers, generation of frequency combs) and other unique characteristics of THz QCLs make it possible to create a new generation of gas spectrometers for biomedical and environmental applications. The article discusses the possibilities of controlling the spectral characteristics of THz QCLs by changing the operating temperature and parameters of the injection current pulses: amplitude, duration, and repetition rate. For the first time, the study of energy transfer between longitudinal Fabry — Perot modes in THz QCLs with a change in the duty cycle of injection current pulses has been carried out.

Dual Response Optimization of Ultrasound-Assisted Oil Extraction from Red Fruit (Pandanus conoideus): Recovery and Total Phenolic Compounds

Red fruit oil (RFO) is a high-value oil that contains functional compounds, mainly phenolic compounds, providing antioxidant activity. Therefore, an optimal extraction method is essential to recover the RFO and phenolic compounds simultaneously. This research aimed to optimize the ultrasound-assisted extraction (UAE) for oil from red fruit using the Box-Behnken design combined with response surface methodology. The studied UAE factors, including sample-to-solvent ratio (1:3, 1:2, and 1:1 g mL−1), extraction temperature (60, 75, and 90 °C), and pulse duty-cycle (0.20, 0.50, and 0.80 s−1). Analysis of variance revealed that the three studied factors significantly influenced the recovered RFO, while the level of total phenolic compounds in the extracts was defined merely by extraction temperature (p < 0.05). These significant factors were then included in the optimization models (R2 > 0.99, lack-of-fit p > 0.05). The proposed UAE setting by the multiresponse optimization was an extraction temperature of 67 °C, a pulse duty-cycle of 0.50 s−1, and a sample-to-solvent ratio of 1:2.5 g mL−1. Subsequently, the extraction kinetic was evaluated, confirming full recovery at 60 min of extraction time. The developed method was then applied to extract six red fruit clones. Mbarugum clones provided high RFO recovery (9.60%), with an uppermost total phenolic compound of (42.63 mg GAE g−1) among the six red fruit clones. Additionally, the resulting RFO showed eminent antioxidant activities, indicated by excellent values of IC50 DPPH (37.69 mg L−1), IC50 FIC (30.43 mg L−1), FRAP reducing power (63.55 mg AAEA g−1), and IC50 ABTS (93.88 mg L−1). In contrast with a wet rendering method, UAE enhanced the RFO recovery by 53.02%, resulting in a higher level of total phenolic compounds. Henceforth, the proposed UAE method is a promising technique to substitute conventional oil production in the food and pharmaceutical industries.

Effects of low-intensity pulsed ultrasound on pain and functional disability in patients with early-stage lumbar spondylolysis: A randomized controlled trial

BackgroundLow Intensity Pulsed Ultrasound (LIPUS) is beneficial in accelerating fracture recovery, enhancing their capacity to execute tasks of daily life and, as a result, their autonomy. ObjectiveTo compare the outcomes of routine physical therapy and routine physical therapy along with LIPUS in patients with early-stage lumbar spondylolysis. MethodsThirty-four (29 males and 5 females) patients exhibiting symptomatic low back pain for at least four weeks were recruited and randomly divided into control group (CG) and intervention group (IG) group. Randomization was done by using goldfish bowl method and allocation was done by using sealed envelope method. Parallel assignment was done. Numeric Pain Rating Scale (NPRS) was utilized for the measurement of pain and Oswestry Disability Index (ODI) for functional disability. Patients were assessed at baseline, at the end of 12th and 20th week. Interventions were applied by two physical therapists (one male and one female) having more than eight years of clinical experience for 10 weeks on alternate days. ResultsIntervention group reported significant percentage change of 47% at 12th week and 65% at 20th week for pain and 42% at 12th week and 81% at 20th week for functional disability compared with 40% at 12th week and 37% at 20th week for pain and 3% at 12th week and 25% at 20th week follow-up for functional disability from baseline in control group. ConclusionLow-intensity pulsed ultrasound has significantly reduced pain and functional disability in patients with early-stage lumbar spondylolysis by using following parameters; 1.1-MHz oscillation frequency, 1-kHz pulsed frequency, 100-mW/cm2 spatial intensity, 2 ms pulse duration, 100Hz pulse repetition rate, 20% pulse duty cycle, and 20-min duration on alternate days.

An investigation of Grid-Integrated Photovoltaic system intended for hybrid Moth Flame Optimization using ANFIS techniques

As the move towards Grid Integrated-Photovoltaic (GI-PV) system is proposed to improve the power quality development. A novel Adaptive Neuro-Fuzzy Inference System (ANFIS) based on improved Moth Flame Optimization (MFO) algorithm is described for grid integrated approach. The solar integration of Maximum Power Point (MPP) fed into modified Switched Boost Inverter (SBI) is presented, this GI-PV connected circuit has become prominent research in a recent scenario for energy demand. Proposed MFOA-ANFIS controller has generated the duty cycle pulses to each converter circuit. The benefit of grid-tied SBI is direct control outer-loop employed to obtain MFO-ANFIS techniques. To maintain a constant voltage DC-link is employed for inner-loop, this presence of constant DC-power to grid loads with support of MFO-ANFIS assists Proportional Integral Differential (PID) method. The results acquired by the simulation expressed that the proposed controller is addressed to maintain active and reactive power exchange, regulate DC bus-link voltages, grid voltage, and grid current. The effectiveness of the practical implication research is achieved by the output as represented as minimum grid harmonics, load current, and compensator current as verified in MATLAB/Simulink platform.

An ultrasound-based technique for the analytical extraction of phenolic compounds in red algae

Phenolic compounds are bioactive compounds that are also naturally found in red algae. To determine the level of these compounds in the red algae, spectroscopic or chromatographic determination was applied over the liquid extracts. Therefore, a prior extraction method is needed. The presented study aimed to develop the analytical ultrasound-assisted extraction (UAE) method to extract phenolic compounds from red algae. A Box–Behnken design (BBD) based on five factors included solvent composition (50–90% ethanol in water), extraction temperature (10–60 °C), ultrasonic power (20–100%), pulse duty-cycle (0.2–1.0 s−1), and solvent-to-sample ratio (10:1 to 30:1) was used to evaluate the effects of the studied factors. Subsequently, response surface methodology (RSM) was performed to define the optimum extraction condition to recover phenolic compounds from the alga matrices. The UAE condition suggested by RSM was: ultrasonic power 100%, pulse duty-cycle 1 s−1, temperature 52.5 °C, extraction solvent 50% ethanol in water, and solvent-to-sample ratio 30:1. Kinetic studies confirmed 10 min to provide comparable recovery (p > 0.05) than any longer extraction time. The acceptable values validated the developed method for repeatability (CV, 4.8%) and intermediate precision (CV, 5.7%). In addition, the accuracy of the method suggested a complete recovery for two extraction cycles. Furthermore, the method has successfully been applied for a number of samples covering three different red algae species. Fingerprints of each sample based on phenolic composition and levels characterize the type and origin of different red algae species.

Development of a micro-electrochemical machining nanosecond pulse power supply.

Micro-electrochemical machining (micro-ECM) has been widely used for microscale and nanoscale processing of materials. The performance of the nanosecond pulse power supply is directly related to the precision of micro-ECM, which is one of the core technologies for micro-ECM. In this work, a nanosecond pulse power supply, with adjustable pulse frequency, duty cycle, and voltage, was designed with an STM32F103VET6 single-chip microcomputer as the control core and a metal-oxide-semiconductor field-effect transistor as the chopper switch component. The performance test has shown that the power supply can produce a continuous pulse with the highest frequency of 8MHz, the shortest pulse width of 50ns, the maximum peak current of 12A, and the maximum voltage of 10V. As compared with the power supply reported in the literature, the present power supply demonstrated the enhanced output current and improved waveform of the nanosecond pulse output, which could result in better machining accuracy and efficiency for micro-ECM.

Effect of pulse frequency and duty cycle on electrochemical dissolution behavior of multi-tip array tool electrode for reusability in the ECDM process

Effect of pulse frequency and duty cycle on electrochemical dissolution behavior of multi-tip array tool electrode for reusability in the ECDM process

The intensification of dehydration process of pectin-containing raw materials

The process of intensifying dehydration of pectin-containing raw materials by using centrifugation with simultaneous application of low-frequency oscillations to the working container creates an electroosmotic effect in unilateral diffusion to improve the filtration process. It is established that to reduce the technological resistance in the presented methods; it is necessary to create a fluidized bed of products due to the oscillating motion of the working capacity. An experimental vibration unit has been developed to determine the rational parameters of the vibrocentric moisture removal process using the electroosmotic effect. It is proved that the complex of the designed equipment provides consecutive carrying out of three-stage vibration filtration-convective drying of high-moisture production by an alternation of action of a stream of the heat carrier, an electromagnetic field, low-frequency fluctuations. According to the research results, the dependences of the kinetics of the moisture diffusion process on the electric field strength are obtained; frequency of electric current and duty cycle of pulses, which allowed to optimize the process parameters according to the criteria of minimizing energy consumption. It was found that the processing time to achieve the desired humidity with the application of vibration, filtration, and electroosmotic effect was twice less than for filtration drying in a fixed bed. In combination with the noted physical and mechanical factors, the proposed technology improves the technical and economic parameters of the studied process.

Research on “slice” layer height and width additive manufacturing by maskless localized electrodeposition method

Maskless localized electrodeposition additive manufacturing is a novel non-thermal metal additive manufacturing technology, the resolution and quality of the parts manufactured of the additive manufacturing process are determined by the layer height. In order to study the layer height data of maskless localized electrodeposition, the effect of main process parameters such as inter-electrode voltage, electrode scanning rate, electrode gap, and pulse duty cycle on experimental results were studied by the controlled variable method and orthogonal experiment method. The research results show that the electrode scanning rate and voltage have a greater influence on the layer height, and the duty cycle has a smaller influence on the layer height, a smaller electrode spacing will lead to deposition failure. The faster the electrode scanning speed, the smaller the layer height. In the voltage (4V), duty cycle (50%), interelectrode gap (IEG) (30μm), frequency (5KHz), scan rate (20μm/s), the layer height is 1.8μm and the deposition efficiency is higher and surface morphology is better.

Імпульсні перетворювачі зі зниженою пульсацією вихідного струму

When developing pulse converters, in order to ensure a low level of output current ripples, one should seek a compromise between the overall size of the elements and acceptable losses in them, while taking into account the dynamic characteristics of power sources as closed systems with feedback. Using multiphase pulse converters can help solve the said problem, but will not ensure a low level of output current ripples in a wide range of the duty cycle of the control pulses. This study aims to find a pulse converter topology capable of ensuring the reduction of the output current ripples, while maintaining the power and volume of the structure. The paper demonstrates the relevance of the study of pulse converters aimed at obtaining a low-ripple output current for powering sensitive loads and gives an overview of ways to reduce the ripples and the most common topologies of converters. The authors describe the results of the practical application of the developed experimental stand and analyze the obtained dependences of the output current ripples on the volumes of the power sections of the converters of different topologies under the same power and frequency. Recommendations are given for choosing the type of converter in each specific case in terms of reducing ripples.

Evaluation on the microhardness of Ni-TiO2 nanocomposite coatings on AISI 1022 substrate

The surface strength and performance of the material depends mainly on the appropriate coating techniques and also on the selection of the appropriate process parameters. From in this, electroplating is broadly used to protecting the material's surface and hence increases the life of industrial components. The present study pulse electrodeposition of Ni-TiO2 nanocomposite coating was developed on the surface of AISI 1022 Carbon Steel from watts bath. Such nanocoatings greatly enhanced the better hardness, wear and corrosion resistance in the automotive industry. The present work purpose to examine the influence of the coating process parameters on the microhardness (MH) of Ni-TiO2 nanocomposite coating on AISI 1022 Carbon Steel with the aid of response surface methodology (RSM). The Pulse frequency (Hz), Current density (A/cm2) and Duty cycle (%) parameters are considered and integrated into the RSM three factors and three level orthogonal arrays to determine the optimized condition for improved hardness of the coating. The contribution of the coating parameters was studied with the help of analysis of variance (ANOVA). The result revealed frequency: 20 Hz, current density: 0.2 A/cm2 and duty cycle: 30% coated specimen uniformly distributed cauliflower structure than compared to the frequency: 30 Hz, current density: 0.2 A/cm2 and duty cycle: 20%. To explore that uniformly coated specimen EDX, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) respectively.

Production of low-Sn Cu-Sn Alloy Coatings onto Steel Substrate Using Sodium Citrate Bath – Part 1: the Effect of Current Mode (DC or SPC) and Applied Current on the Chemical, Morphological, and Anticorrosive Properties of the Coatings

Abstratc This work reports the production of low-tin Cu-Sn alloy coatings on carbon steel substrates using a bath containing CuCl2, SnCl2, and sodium citrate. In the first part of this study, the coatings were electrodeposited by direct and simple pulse current processes (DC and SPC, respectively). Different current density values were used, while the pulse frequency and duty cycle remained constant. Independent of the current mode used, low-tin Cu-Sn coatings, showing globular surface morphology and Cu6Sn5 as the main compositional phase, were produced. Both the current mode and the applied current density affected the anticorrosive properties of the coatings. The most protective DC and SPC coatings, showing Sn content < 3 wt.% and compact morphology, were prepared using j = 80 A m-2 and jc = 167 A m-2, respectively. High charge transfer resistance values were verified even after immersion for 24 h in 0.5 mol L-1 NaCl solution.

Azimuth Interrupted FMCW SAR for High-Resolution Imaging

Azimuth interrupted frequency modulation continuous-wave synthetic aperture radar (AI-FMCW SAR) is a novel type of light and miniaturized sensor that works on satellites, which can transmit and receive signals with a single antenna. Different from conventional pulse SAR, the instantaneous duty cycle of pulse is close to 100%. Several pulses could not be transmitted and would be replaced by receiving echoes. There will be gaps in the received echoes. It is necessary to reconstruct the gapped data; otherwise, there will be ghosting with traditional imaging algorithms. The current algorithms for reconstructing the gapped data are computationally time-consuming and not suitable for high-resolution imaging. Therefore, a new imaging algorithm is proposed to focus on the AI-FMCW SAR raw data via subaperture processing, which is called subaperature sparse reconstructing technique (SSRT). It can significantly suppress ghost targets and has a high calculation speed. In this letter, the spaceborne AI-FMCW SAR signal model was proposed first. Then, SSRT was proposed to process the AI-FMCW SAR data, in which the generalized orthogonal matching pursuit (GOMP) algorithm was used to reconstruct the signals. Finally, the simulation experiments verified the effectiveness and rapidity of the proposed approach.

Feedback regulation system for spraying parameters based on online droplet mass deposit measurements

In order to effectively optimize and regulate spraying parameters based on actual spraying performance and improve pesticide utilization rate, in this research, a feedback regulation system for the regulation of spraying parameters was designed based on droplet mass deposit online measurement. The system consisted of an online droplet mass deposit measurement module, wireless transmission module, decision module, and spraying parameters regulation module. First, the droplet mass deposits on the sampling points were measured. Based on the deviation between the measured and expected droplet mass, the expected spraying parameters were determined by the decision module. The spraying parameter was regulated to the expected value by regulating the pulse duty cycle on the pump motor using a micro control unit and a relay. Evaluation tests were conducted indoors using an indoor spraying platform and outdoors using an unmanned aerial vehicle. The results showed that the relative errors between the expected and measured droplet mass deposit after regulation were 6.84% and 11.48% for the indoor and outdoor tests, respectively. Therefore, an optimal spraying performance was observed after regulation. This research provided an experimental platform to quickly optimize spraying parameters and also provided technical references for precision spraying. Keywords: spray, droplet mass deposit, online measurement, wireless transmission, duty cycle, feedback regulation DOI: 10.25165/j.ijabe.20221502.6118 Citation: Sun C D, Qiu W. Feedback regulation system for spraying parameters based on online droplet mass deposit measurements. Int J Agric & Biol Eng, 2022; 15(2): 25–29.

Особенности азотирования поверхности мелкомодульного зубчатого венца в импульсно-периодическом газовом пучково-плазменном образовании при низком давлении

The paper presents the results of a study of the homogeneity of the thickness of the modified layer on the surface of a tooth crown made of structural steel 38Cr2MoAl with a tooth modulus m = 0.5 and the number of teeth 14, obtained as a result of ion-plasma nitriding in a beam-plasma formation generated in a stationary and pulse-periodic non-self-sustained glow discharge with a hollow cathode at low, about 1 Pa, pressure. The thicknesses of the nitrided layer at the top and at the base of the tooth obtained at the discharge pulse duty cycle γ = 100, 85, and 50%. It is shown that the minimum difference in the thickness of the nitrided layer, which is about 6%, is characteristic of the regime with a discharge pulse filling coefficient γ = 85%. Gas beam-plasma formations formed at low pressure are promising in the processes of ion-plasma nitriding of parts of complex shape.

Wear Behaviors of Carbon-Chromium Carbide-Chromium Multilayer Coatings Prepared by Reactive High-Power Impulse Magnetron Sputtering.

Carbon–chromium carbide–chromium multilayer coatings were deposited by utilizing reactive high-power impulse magnetron sputtering with alternating various ratios of ethyne and argon mixtures under a constant total deposition pressure, target pulse frequency, pulse duty cycle, average chromium target power, and total deposition time. Two different alternating gas mixture periods were applied to obtain films with different numbers of layers and lamination thicknesses. The results show that the reduction in the modulation period effectively affects the elastic modulus and the subsequent ratio of hardness to elastic modulus (H/E) of the whole coating, which helps adapt the elastic strain in the coating. This improves the adhesion strength and wear resistance of coatings at room temperature. However, with the increase in wear test temperature, the difference between the wear behaviors of two types of coatings becomes inconspicuous. Both types of coatings lose the wear resistance due to the decomposition of hydrocarbon and the oxidation of the chromium content in the films.

Pulse Programming of Resistive States of a Benzothieno[3,2‐B][1]‐Benzothiophene‐Based Organic Memristive Device with High Endurance

Organic memristive devices are promising elements to be used in memory tasks, neuromorphic systems, and bioelectronics as hardware analogs of synapses. Among other materials, small molecules are considered in this field as candidates with more adjustable properties and fine chemical structures. Herein, the first organic memristive device based on benzothieno[3,2‐b][1]‐benzothiophene (BTBT) siloxane dimer is reported. The device resistance programming by voltage pulses with various control parameters is demonstrated: amplitude, frequency, and pulse duty cycle. It is proved that the device has at least four different resistive states in each case. In addition, the device shows 2.5 × 104 cycles of sustainable operation in the endurance test with ROFF/RON ratio exceeding 5.

Energy-efficient pulse electrochemical oxidation of Acid Blue 9 using a Ti/SnO2-Sb/α,β-Polytetrafluoroethylene-Fe-PbO2 electrode: Kinetics, mass transfer and mechanism

This study focused on the electrochemical oxidation of Acid Blue 9 (AB 9) under direct and pulse current modes using a Ti/SnO2-Sb/α,β-Polytetrafluoroethylene-Fe-PbO2 (PTFE-Fe-PbO2) anode. The results showed that 99.0% of AB 9 and 68.9% of COD could be eliminated at initial pH of 5, initial AB 9 concentration of 100 mg L-1, pulse frequency of 4000 Hz, current density of 20 mA cm−2 and pulse duty cycle of 50% after 120 min of electrolysis. The pulse electrochemical oxidation of AB 9 at the investigated conditions followed pseudo-first-order kinetics. Compared with the direct current mode, 76.0% of energy consumption could be saved at pulse current mode. The effect of mass transfer and electrode distance on the pulse electrochemical oxidation of AB 9 was also investigated in terms of mass transfer coefficient and effectiveness factor, the results showed that the reduced electrode distance was beneficial to improve the mass transfer and oxidation efficiency, as well as the energy efficiency. LC-MS analysis revealed that benzenesulfonate group, C-N and C-S bonds in AB 9 molecule were initially cleaved under the attack of ⋅OH, then some carboxylic acids were formed and eventually mineralized to CO2 and H2O. Therefore, pulse electrochemical oxidation with a PTFE-Fe-PbO2 electrode might be a promising alternative to enhance the practicability of electrochemical treatment for dye wastewater.

Modeling and experimental research on the evolution process of micro through-slit array generated with masked jet electrochemical machining

This paper proposed to prepare micro through-slit array on thin metallic plate with masked jet electrochemical machining. An ECM mathematic model was developed with ANSYS Parametric Design Language to analyze the evolution process of micro through-slit, including the broken through process of workpiece. In each step, machining status was monitored to judge whether the workpiece was broken through, then both model and boundary condition were reset accordingly, thus the broken through process was well solved. The simulation results indicated that with moving speed of workpiece decreasing (increasing machining time in ECM model), the sectional profile evolved from groove to a tapering micro through-slit, and a micro through-slit with low taper was formed at last. The changes of electric field distribution in both X and Z direction affected the material dissolution along the side wall of micro through-slit and contributed to the formation of micro through-slit. The experiments were performed with different moving speeds of workpiece, and the sectional profile evolution process agreed well with that in simulation. Moreover, with the same real machining time, low pulse duty cycle was useful to enhance the transport of electrolytic product in the small machining area and reduce the dimensional difference of micro through-slit. At last, ten micro through-slits with the length of 30 mm were well prepared at one time on a thin metallic plate of 50 μm. The width of upper surface and lower surface was 206.1 ± 2.28 μm and 193.7 ± 1.97 μm, respectively, and the taper was about 7.1°.