Direct Current Source Research Articles

Mechanical and tribology performance of nanostructured ZrN-Cu coatings obtained by hybrid HiPIMS-DCMS technology

One of the biggest players in the world economy is the naval industry, which mainly controls the merchandise transportation sector. Any issue with ships could represent millions of USD of loss and increases in the cost of goods for the population worldwide. Two main problems which this industry has fought are corrosion and biofouling. Lastly, the pollution of the sea has gained importance, and more strict policies have been applied regarding the use of certain products by this industry. One of these is paintings, which represented this industry's definitive solution to avoid the mentioned problems for a long time. This situation allowed to explore other solutions like PVD coatings through multifunctional coatings. Zirconium nitride has been demonstrated to be useful in resisting corrosion with reliable mechanical properties. However, this material does not possess antimicrobial action. The present study presents a nanostructured coating combining ZrN with Cu, which works as a biocide, contributing to the desired multifunctionality. The developed coating was obtained using a hybrid magnetron co-sputtering employing High-power impulse (HiPIMS) and direct current (DCMS) power sources under a reactive atmosphere. SEM, EDX, XRD and Raman spectroscopy were used to assess the physico-chemical properties of the coatings. Besides, depth-sensing nano-indentation explored the mechanical properties. The tribological performance was tested by a reciprocating tribometer under dry and wet (with 3.5 % w/w NaCl solution) contact conditions and employing a soda lime glass ball as a counterbody. The results showed that adding Cu to ZrN through this technology resulted in a limited hardness reduction from 19 (pure ZrN) to 14 GPa. Also, the chemical activation with NaOCl solution softens the obtained coating and, together with the saline solution, influences the wear resistance. However, the nanostructured coating has been demonstrated to be suitable for use under real conditions, without loss of its protection over the used substrate. It opens a new possibility of a solution for the naval industry.

Detection of Veterinary Drugs in Food Using a Portable Mass Spectrometer Coupled with Solid-Phase Microextraction Arrow.

A portable mass spectrometer (PMS) was combined with a mesoporous silica material (SBA-15) coated solid-phase microextraction (SPME) Arrow to develop a rapid, easy-to-operate and sensitive method for detecting five veterinary drugs-amantadine, thiabendazole, sulfamethazine, clenbuterol, and ractopamine-in milk and chicken samples. Equipped with a pulsed direct current electrospray ionization source and a hyperboloid linear ion trap, the PMS can simultaneously detect all five analytes in approximately 30 s using a one-microliter sample. Unlike traditional large-scale instruments, this method shows great potential for on-site detection with no need for chromatographic pre-separation and minimal sample preparation. The SBA-15-SPME Arrow, fabricated via electrospinning, demonstrated superior extraction efficiency compared to commercially available SPME Arrows. Optimization of the coating preparation conditions and SPME procedures was conducted to enhance the extraction efficiency of the SBA-15-SPME Arrow. The extraction and desorption processes were optimized to require only 15 and 30 min, respectively. The SBA-15-SPME Arrow-PMS method showed high precision and sensitivity, with detection limits and quantitation limits of 2.8-9.3 µg kg-1 and 10-28 µg kg-1, respectively, in milk. The LOD and LOQ ranged from 3.5 to 11.7 µg kg-1 and 12 to 35 µg kg-1, respectively, in chicken. The method sensitivity meets the requirements of domestic and international regulations. This method was successfully applied to detect the five analytes in milk and chicken samples, with recoveries ranging from 85% to 116%. This approach represents a significant advancement in food safety by facilitating rapid, in-field monitoring of veterinary drug residues.

Optimized Energy Management for PV Hybrid Power Systems with DC Bus Voltage Control

The growing popularity of direct current (DC) power sources, energy storage systems, and DC loads has recently shifted the focus away from alternating current (AC) microgrids and towards DC-only systems. However, smart and energy-efficient building integration and effective microgrid administration are prerequisites. Direct current microgrids, which include solar modules as their principal power source, an energy storage device (battery), and an essential DC load, may have their energy consumption managed with the help of our study. Within the microgrid (MG) architecture, the DC-DC boost converter enables the PV module to operate in many modes, one of which is Maximum Power Point Tracking (MPPT). In order to link the battery and supercapacitor to the DC bus, the system also makes use of a DC-DC bidirectional converter. By restricting the charging/discharging currents and state of charge (SoC) of the batteries and supercapacitors, the proposed control approach seeks to manage power flow within the microgrid while considering their lifespan. This method simplifies and improves upon previous approaches to DC load supply by doing away with complicated energy management or maximum power point tracking methods. We conceived and simulated the DC microgrid under investigation thanks to Matlab/Simulink. We fulfil the load demand while maintaining system stability and performance. We provide a presentation and discussion of findings from controller design, analysis, and simulation validation for several operating modes.

Synthesis of TiO2-brookite nanorods and TiO2-Au composites for decomposition of organic dyes in water

This study employed a plasma-liquid interaction technique at room temperature to modify TiO2 nanocrystals in the brookite phase and coat their surface with gold nanoparticles (AuNPs). The technique was further utilized to reduce Au3+ ions to Au0, eliminating the need for chemical agents and reducing reaction time. The resulting TiO2-Au photocatalysts were then tested under visible light to evaluate their ability to degrade the dyes rhodamine 101 (RB101) in water. The findings indicated that the most effective degradation of RB101 molecules occurred at low dye concentrations (10 ppm) and low photocatalyst loadings with a ratio of 4. In comparing two different preparation methods, the TiO2-Au sample created using a micro-plasma process with a direct current (DC) source exhibited higher photocatalytic activity (87 % after 4 hours) compared to the sample created using a plasma jet process with an alternating current (AC) source. This research holds significance for the advancement of photocatalytic materials with potential environmental applications.

Design and Testing of an Electric Side-Mounted Cabbage Harvester

To address the limitations of current cabbage harvesters in China, which are often designed for a single variety and lack adaptability to different cabbage varieties, we developed an electric side-mounted cabbage harvester suitable for field operations in the Jiangsu region of China. This design is informed by the statistical analysis of the physical and agronomic parameters of major cabbage varieties. The harvester consists of key components, including an extraction device, a leaf-stripping device, a clamping and conveying device, and a root-cutting device. Powered by a 120 Ah direct current (DC) power source, it is capable of performing cabbage extraction, feeding, clamping, conveying, root cutting, and boxing in a single operation for three hours. Through theoretical analysis of the key components, specific parameters were determined, and field tests were conducted to verify the design. The results of the field experiments indicate that all components of the cabbage harvester operated effectively. Optimal performance was observed when the extraction roller speed was set between 100 and 110 RPM, the conveyor belt speed at 60 RPM, and the cutter speed between 160 and 220 RPM, resulting in a low cabbage harvest loss rate. The harvest loss rates from the three experiments were 11.3%, 13.3%, and 12%, respectively, which meets the mechanical harvesting requirements for cabbage.

Enhance Hydrogen Production from Water Using 532 Lasers

ABSTRACT: hydrogen production via water electrolysis under the influence of laser sounds fascinating with its unique properties, was particularly effective in promoting hydrogen production. The mechanism by which the laser promotes hydrogen production The electrolytic cell used in this work contains 270 ml of distilled water stimulated with different amounts of alcohol (2 ml - 4 ml - 6 ml - 8 ml - 10 ml). This chamber consists of two vertically oriented cylinders. Inside each cylinder there are graphite electrodes, each measuring 10 x 5 x 7 mm3, connected to the positive and negative terminals of a direct current power source, in addition to using a green laser source (532). An efficiency study was conducted using a green laser with a wavelength of 532 nanometers as an optical light source for water analysis through electrolysis. Results were obtained using both the standard electrolysis method and with the green laser source (532 nm). In the case of standard electrolysis, we obtained (When adding 5 ml of cohol, we get 6.63 hydrogen ), while (Adding 10 ml of ill we get 7.44 of hydrogen ) was obtained when using the laser source. The results indicate that using the laser source enhances hydrogen production significantly compared to standard electrolysis, demonstrating the laser's high effectiveness in electrolysis due to its non-absorptive property in water. This could have significant implications for renewable energy and hydrogen fuel production.

POWER SUPPLY UNIT OF THE STAND AND LABORATORY INSTALLATION FOR TREATING OLIVES WITH ELECTROSTATIC FIELD

Most technological machines (TM) use hydraulic drives and internal combustion engines, such as lifting and transporting, loading and unloading, construction, road, track, and mining. Increasing the durability of the specified TM units is an urgent task. One of the possible solutions to this urgent problem is the electrostatic treatment of hydraulic oils and diesel fuels. Over the past three decades, researchers have conducted many studies focused on finding optimal means of using external force fields to improve the quality of lubricating materials and intensify their production. Types of influence of force fields, such as mechanical, mechanochemical, acoustic, electromagnetic, and electric, are increasingly used to regulate the behaviour of dispersed particles in nonpolar and slightly polar environments. The theory of regulated interphase transitions proves that the emergence, growth, and size change of supramolecular structures, surrounded by an adsorption-solvate layer and creating complex structural units in oil dispersion systems, contribute to the emergence of new properties of these systems. One of the main provisions of this theory is the need for extreme and antibating changes in the size of complex structural units with the help of external influences, which include force fields. Lubricating materials differ in their degrees of dispersity, composition, and properties, so the effect of force fields on them is diverse. The ability to regulate intermolecular interactions and the size of complex structural units are significant in the operation of lubricants. Electric fields make it possible to control phase interactions in these dispersed systems: they increase the constant dipole moments of particles and the electrosurface forces, which contribute to the deformation of the electric double layer. Under the action of strong electric fields, structural changes occur in hydrocarbon dispersion systems, which significantly change the physicochemical properties of lubricating materials. Thus, the dynamic viscosity of the lubricant and its resistance to deformation may change depending on the chemical nature of the system. Previously conducted experimental studies allow us to formulate the requirements for the stand in detail, which enables investigation of the properties of petroleum-based liquids. Thus, it is possible to achieve increased anti-wear properties of petroleum-based liquids when the liquid passes through the gap between the electrodes in an electrostatic field. The voltage between the electrodes should be U = 1000–1500 V, and the speed of the liquid movement in the space between the electrodes should be V = 4.5–6.5 m/s. The power supply unit of the stand for electroprocessing petroleum-based liquids, proposed in this paper, meets these requirements. The article proposes a fundamentally new scheme for the power supply unit of the laboratory stand for direct current electrotreatment of petroleum-based liquids. The power supply unit is a bipolar source of adjustable direct current. It provides smooth regulation of the voltage from 0 to 3000 V and step regulation of the output current. The block has double protection against short circuits at the output and input. Keywords: anti-wear property, oil, influence of an electrostatic field on the anti-wear properties of oil, device for electrostatic treatment of oil.

Low-current gliding DC discharge in high-speed flows

Abstract A low-current gliding discharge (current range 1–5 A) in high-speed air flows of 100–250 m s−1 was experimentally studied. A high-voltage direct current source with a maximum voltage of 4.5 kV was used to create the discharge. The average electron concentration n e ∼ 1014 cm−3 and the plasma ionization degree were determined by measuring the Stark broadening of the hydrogen H β line (λ Hβ = 486.1 nm). The estimates of the electric field (E ∼ 100 V cm −1 ÷ 600 V cm−1) in the discharge positive column were found using time-synchronized high-speed video recordings and oscillograms. The gas rotational temperature T g = 7000–9500 K and the vibrational temperature T v = 7000–11 000 K were estimated using optical emission spectroscopy. Time-resolved spectroscopy is used to investigate the effective plasma channel spatial regions from which the N, NH, N2 +, O and OH molecules radiate. The difference of the obtained radii indicates the presence of a radial temperature gradient and inhomogeneous plasma composition in the discharge cross section. The possibility of using of gliding discharge to ignite hydrocarbon-air mixtures in the ramjet engines combustors has been experimentally demonstrated.

Analysis of a Resistive-Capacitive Shunted Josephson Junction with Topologically Nontrivial Barrier Coupledto a RLC Resonator

This paper presents the resistive-capacitive shunted Josephson junction (RCSJJ) with a topologically nontrivial barrier (TNB) coupled to a linear RLC resonator. The rate equations describing RCSJJ with TNB coupled to the linear RLC resonator are established via Kirchhoff’s current and voltage laws. The model exhibits four, two, or no equilibrium points depending on the external direct current (DC) source and the fractional parameter. The stability analysis of the equilibrium points with credit to the Routh-Hurwitz stability criterion reveals that the stability of equilibrium points depends on the DC source and the fractional parameter. Current-voltage characteristic reveals the presence of a birhythmicity zone which is sensitive to the fractional parameter m. As the fractional parameter increases, the coexistence of the resonant state is destroyed, which is followed simultaneously by the appearance of a new resonance state. Depending on initial conditions, birhythmic behaviour is characterized by the existence of a limit cycle. The projection of the phase space in the specific plane and the time evolution of charge is predicted in which the amplitude of attractors reported is sensitive to the parameter m. Lastly, with a defined fractional parameter, the amplitude of the branch locked to the resonator is greater than the unlocked branch.

CARBONIC ANHYDRASE FREQUENCY AND POPULATION STABILITY AMONG BREEDS OF NIGERIAN GOAT.

Using 900 goats of the three breeds in Nigeria from Borno, Sokoto and Ogun States with equal number across breed, blood was collected from each animal by means of jugular venipuncture and placed in heparinized tubes to prevent coagulation. It was then refrigerated at 8°C for two hours and thereafter carried into the laboratory. Carbonic anhydrase polymorphism from blood plasma and blood hemolysate were analysed by the method of starch gel electrophoresis using direct current electric source Multidrive XL. Gene, genotypic frequencies, allelic frequencies and genetic distance among the breeds were estimated for this locus. Carbonic anhydrase presented two alleles, Ca-S and Ca-F. The (Ca-F) was the predominant alleles in all the studied breeds. West African Dwarf breed recorded the highest frequency (0.9900) for (Ca-F) while the least value (0.9868) for (Ca-F) was observed in Red Sokoto goat. Considering the pattern of genotype within the sample population for carbonic anhydrase, it was observed that the average heterozygosity for all the breeds was 0.0000. This is a marker that the population has high level of homozygosity for carbonic anhydrase. UPMGA cluster showing relationship between populations at CA locus indicated similar distance value (0.0000) for the populations. It was recommended from observed result that the high level of homozygosity observed for this locus indicates that it is not a suitable candidate for selection and breeding purposes.

EXPERIMENTAL INVESTIGATION OF NEWLY DEVELOPED ELECTROLYTIC MAGNETIC ABRASIVE FINISHING SETUP WITH MULTIPLE POLE SYSTEM FOR FINISHING OF ALUMIUM WORKPIECE

The procedure of combining abrasion machining with chemical machining is the most demanding and crucial method of machining, because it guarantees higher levels of quality from the part. Combined procedure for machining are typically employed as the last step in the machining process, and their significance grows progressively crucial while a nano finished surface of the work piece material is necessary. The subject of nano surface finishing of materials via chemical machining and abrasion has advanced recently. Electrolytic magnetic abrasive finishing (EMAF) is a procedure that combines chemical and magnetic energy to achieve a desire finish. During the EMAF process, The work piece fits in the middle among two magnetic poles. A mixture of abrasives and ferromagnetic particles fills the gap between each pole and the workpiece. The electrode is positioned at a certain distance from the workpiece, and both are linked to a direct current (DC) power source. An electrolytic solution is circulated between the gap using a pump. The method offer a wide range of industrial applications because to its low specific energy consumption and enhanced surface finishing. This study presents the creation of a novel EMAF with multiple pole system. It further looks into the impact of different process attributes include machining time, rotational speed, size of the abrasive particles, electrolytic concentration and weight of the abrasive particles on the improved performance of material removal rate (MRR) and surface finishing (PISF).

An Efficient DC-AC Power Integration Model for Single-Phase Systems, Simulated in MATLAB

In the face of growing clean energy demands, this study presents a model for integrating Direct Current (DC) sources into the existing Alternating Current (AC) grid. The model is based on a single-phase system where a DC source is added. A converter, designed using the synchronous reference frame, is proposed to address integration issues. This converter allows for the control of both active and reactive power using a dq reference frame. A Proportional-Integrator (PI) controller is chosen for this purpose. To generate the necessary operational references, a Phase-Locked Loop (PLL) is used. An LCL filter is also incorporated based on its performance quality. The entire model is simulated in MATLAB, and the output obtained confirms the model’s ability to control both active and reactive power when integrating DC with AC and T. This work significantly contributes to the efforts of integrating clean energy into our existing grid systems.

Characteristics of inductively coupled plasma radio-frequency ion source of ion implanters for high number density dopant generation

In this study, we developed an inductively coupled plasma ion source that can be applied to implanters in semiconductor production. We employed an infrared camera and thermocouples to assess the temperature properties of the ion source operated at temperatures below 500 °C. This reduced temperature is expected to facilitate the adoption of various materials as the ion source. Ion densities of the direct current ion source measured using a double Langmuir probe were found to range from 1.66 × 1016 to 5.06 × 1016 m−3 within an input power range of 682–895 W. In contrast, the ion densities of a radio-frequency ion source ranged from 7.86 × 1016–9.58 × 1016 m−3 within an input power range of 700–900 W. This proposed ion source can serve as a next-generation solution because of its low operating temperature and high ion density.

Novel cascaded switched-diode five level inverter for renewable energy integration

This research presents the usage of a unique five-level cascaded switching diode for medium voltage integration of renewable energy sources. Its primary purpose is to decrease the quantity of gate drivers and switches. In addition to that, the cost and space for the installation of multilevel inverters are less. The inverter topology of novel cascaded multilevel inverters and switched diodes will combine both benefits. One-cycle control (OCC), which is used for clock phase-shifting (CPS) to regulate a two-stage container security device (CSD) multilevel inverter of renewable energy integration, was created to address issues with the multilevel inverter's direct current (DC) source variations. The topology also provides efficiency, harmonic distortion reduction, and voltage output quality. Waveforms are created, and a robust resistance to DC source variations is attained. The viability of the unique five-level inverter using cascaded switched diodes is confirmed by discussing the results of both simulation and experiment.

Fundamental frequency switching strategies of a seven level hybrid cascaded H-bridge multilevel inverter

This paper presents a novel hybrid cascaded H-bridge multilevel inverter (HCHB MLI) designed to address the growing importance of multilevel inverters in the context of renewable energy sources such as solar, wind, and fuel cells. The proposed topology features eight insulated-gate bipolar transistor (IGBT) switches and utilizes two distinct input direct current (DC) sources: a battery and a capacitor, making it a hybrid system. The control strategy employed in this topology is based on fundamental switching frequency techniques. Simulation results of the proposed topology are conducted using MATLAB/Simulink software, while hardware experimentation with a single-phase H-bridge inverter is also demonstrated in the paper. For pulse generation and IGBT switch control, an Arduino UNO microcontroller is utilized. The output voltage of the single-phase H-bridge inverter is verified through experimentation using a cathode-ray oscilloscope (CRO).

Improve the voltage profile of the grid-integrated induction motor with a fuzzy-based voltage source converter

This article suggests installing a series compensator on grid-connected induction motors that allows for the ride-through of unbalanced voltage sag. Fuzzy logic controls the motor voltages in a standard three-phase voltage source inverter or voltage source inverter (VSI). An open-ended three-phase machine and the grid form a series connection for the VSI. The proposed system is well suited for uses where frequency variation is unnecessary, such as with large pumps or fans. There is no requirement for a direct current (DC) source or injection transformer when conducting an electric mutual coupling The severity of the sag in the grid voltage that will prevent EMC from shutting down is proportional to the load on the motors. An increase in the voltage of the DC link may be necessary if the voltage is not balanced. A 1.5 hp four-pole induction motor was used alongside grid voltage disturbances to test the proposed compensator's ride-through capability. Grid's current analysis demonstrates that the proposed system does not require the addition of a passive filter to achieve low levels of total harmonic distortion (THD). Additionally, the control strategy, component ratings, and analysis of the converter's output voltage operating principle and pulse width modulation technique are covered. The system's viability is shown via simulation and experimental results.

Solar PV based seventeen level reduced switch symmetrical multilevel inverter topology fed induction motor

Multilevel inverters have received a lot of interest in recent years due to their ability to deliver more voltage levels than typical two-level inverters. Because of this property, multilevel inverters can produce output waveforms that closely resemble sinusoidal waveforms, lowering harmonic distortion dramatically. The emergence of reduced switch symmetrical multilevel inverter topologies has developed the curiosity of many different power conversion systems. These new topologies offer numerous advantages, including greater output voltage quality, fewer harmonic distortions, and increased power conversion efficiency. The inclusion of these inverters in the feeding of induction motors is one of their many prominent uses. A 17 levels of multi-level inverter (MLI) topology is presented with reduced switch count and harmonic reduction for power quality improvement. The inverter is fed by isolated equal photovoltaic panels which act as direct current or DC source. To reduce complexity, switching pulses are generated using hybrid pulse width modulation technique which is designed as controller. Through the use of MATLAB/Simulink, the performance assessment of a unique cascaded multilevel inverter-based reduced switch symmetrical inverter feeding an induction motor drive has been verified. The harmonic distortion with reduced switches obtained is 7.47% which is comparatively less than when compared with conventional cascaded H-bridge topology.

A modular IGBT power stack − based and open hardware framework for small wind turbines assessment

Wind energy technologies have emerged as the predominant renewable energy source within the framework of present-day electric power systems. Their design process, aligned with foundational theories, ought to be precision-engineered and systematized to fully maximize the potential of this energy source. This study presents a platform as solution designed and built to characterize and assess Small Wind Turbines (SWT), based on free software and open hardware. Additionally, the developed methodology step-by-step guide is disclosed. The characterization is based on the use of Permanent-Magnet Synchronous Generator (PMSG) as machine widely adopted in Wind Energy Conversion System (WECS) less than 100 kW. The core theoretical background is detailed to confirm the accuracy of the parameters procedures acquisitions. Poles number, machine design constant, armature reactance, synchronous reactance, and power-dynamic characteristic related to WECS are determined. This laboratory set-up is composed of variable industrial fan, rectifier, boost converter and a bidirectional Direct-Current (DC) source as a battery emulator. All components have been assembled within the laboratory environment using commercially available elements. Low implementation cost and versatile methods determine the real input in practice of this platform. To validate the effectiveness for any SWT, a real one is tested, and every parameter proposed is calculated.

Kinetic behavior of secondary electrons in a magnetized voltage-driven discharge using combined rf/dc sources

This study employed particle-in-cell/Monte Carlo simulations, along with test particle methods, to examine the characteristics of secondary electrons (SEs) in a voltage-driven discharge using combined rf/dc sources and operates in the presence of a magnetic field. The behavior of SEs is significantly influenced by the magnetic field, leading to the emergence of complex branches in temporal electron energy probability distributions and spatiotemporal electron density distributions within the sheath. The number of branches is directly correlated to the cyclotron period. Moreover, the application of a direct current (dc) source thickens the sheath at the dc biased electrode while attenuating the sheath on the opposite side. This leads to an asymmetrical modulation of the kinetic behavior of SEs in the two sheaths, ultimately resulting in a substantial increase in electron energy on the side of the dc biased electrode.

Effects of titanium and boron alloying with non-equimolar AlCrNbSiTi high entropy alloy nitride coatings

Among various fabrication technologies for high entropy alloy coatings, high power impulse magnetron sputtering (HiPIMS) technologies have been utilized to synthesize dense microstructure and high hardness coatings with enhanced mechanical and chemical properties. Mid-frequency (MF) pulses have been introduced in the off-time of HiPIMS pulses of the superimposed HiPIMS-MF system to improve the deposition rate. In this study, AlCrNbSiTiBN coatings were deposited using a superimposed HiPIMS-MF system connected to an Al4Cr2NbSiTi2 high entropy alloy target and a direct current (DC) power source for TiB2 target in a reactive Ar and N2 gas mixture. The DC power of the TiB2 target was varied to increase the titanium and boron contents. With increasing Ti and B contents, the microstructure transforms from loose granular and crystalline structure to denser and refined nanocrystalline phases. A residual stress-free coating with a B content of 4.2 at.%. and a hardness of 16.2 GPa was achieved without intentional heating and substrate bias. The poor corrosion resistance of the coatings with lower B contents can be enhanced with a further increase of B content up to 6.4 at.% and reaching a maximum of 10.3 times improvement than that of AISI 304 stainless steel.