Alternative Voltage Research Articles

Measuring of Electric Potentials for the Diagnostics of Corrosion Protection of the Metal Structures

We analyze available methods for the determination of the polarization potentials of metal structures in electrically conducting media. The structure and principles of operation of the new equipment aimed at measuring the constant and alternative electric voltages and at finding the polarization potential with removing the Ohmic component are described. As advantages of this equipment, we can mention the improvement of monitoring of the cathodic protection of metal structures. We present an example of its application for the purposes of diagnostic inspections of the state of active and passive corrosion protection of underground pipelines and demonstrate wide possibilities of application of the proposed equipment under field conditions.

Switching of actin-myosin motors by voltage-induced pH bias in vitro

ATP-driven motor proteins, which function in cell motility and organelle transport, have potential applications as bio-inspired micro-devices; however, their control remains unsatisfactory. Here, we show rapid-velocity control of actin filaments interacting with myosin motors using voltage applied to Pt electrodes in an in vitro motility system, by which immediate increases and decreases in velocity were induced beside the cathode and anode, respectively. Indicator dye revealed pH changes after voltage application, and alternate voltage switching allowed actin filaments to cyclically alter their velocity in response to these changes. This principle provides a basis for on-demand control of not only motor proteins but also pH-sensitive events at a microscopic level.

Numerical Prediction of Stator Diameter Effect on the Output Torque of Ultrasonic Traveling-wave Motor, using Finite Elements Simulation

Nowadays, piezoelectric materials have wide applications in various industries. Therefore, investigation of these materials and their applications has a special importance. In this paper first, the natural frequencies of a traveling-wave piezoelectric motor are achieved, using finite elements simulations. Then, applying an alternative electrical voltage to the piezoelectric ring, a traveling wave is generated in the stator, and the stability, damping effects, and characteristics of the traveling wave are studied. Additionally, the output torque and rotational speed of the motor are obtained and validated by experimental values. Finally, the stator diameter is increased and its effects on the output torque and rotational speed are inspected. The results reveal that the output torque and maximum rotational speed of the enlarged motor respectively increases and decreases.

Technology of integrated self-aligned E/D-mode n++GaN/InAlN/AlN/GaN MOS HEMTs for mixed-signal electronics

We describe the technology and performance of integrated enhancement/depletion (E/D)-mode n++GaN/InAlN/AlN/GaN HEMTs with a self-aligned metal-oxide-semiconductor (MOS) gate structure. An identical starting epi-structure was used for both types of devices without the additional need for a contacts regrowth. The n++GaN cap layer was etched away in the gate trenches of the E-mode HEMT while it was left intact for the D-mode HEMT. The plasma etching process was shown to be highly selective between the cap and the InAlN barrier and also to polish the InAlN surface. However, different GaN etching initiation times inside and outside the mesa region were obtained. Gate contacts were isolated using a dielectric layer deposited at low temperature through an e-beam resist to retain the self-aligned approach. Feasibility of the approach for future fast GaN-based mixed-signal electronic circuits was shown by obtaining alternative HEMT threshold voltage values of +0.8 V and −2.6 V, invariant maximal output current of ∼0.35 A mm−1 despite large source-to-drain distances and by demonstrating a functional logic invertor.

Stabilization of alternative current voltage

Two ways to construct a pulse ac voltage stabilizer (PACVS) are discussed in the present paper. In the first one, the acting, average, and amplitude voltages are controlled. An observation interval equal to or a multiple of half of the period of measured voltage is required for it. In the second variant, the instant values of the ac voltages are controlled, which allows one to correct the voltage from and compensate for the short voltage jumps and drops. It is shown that PACVS construction using a booster circuit decreases the demands made on the voltage of transistors and filter capacitor, in addition to impairing the quality of the stabilization and correction of the voltage form. Since it uses the feedback principle of the output voltage form, it is appropriate to construct the PACVS by means of the control principle over disturbance. This enables one to increase the stabilizer speed, since it responds directly to the source of the change in the output voltage rather than the consequence. It is shown that the smoothing action depends on the capacitor capacity and throttle inductance product, while the output resistance and the filter oscillation decrease with increasing capacity and decreasing inductance. An example of a PACVS controlling the instant values of the output voltage and the results of its investigation in MATLAB and Simulink are given.

Evaluation of image sticking property on liquid crystal displays with polymer layers produced from phenanthrene-carrying monomers

ABSTRACTAs a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the liquid crystal (LC) cells having the polymer layers produced from monomers of phenanthrene (Phen)-carrying monomers, 2,7-, 3,8-, 1,8- and 3,6-dimethacryloyl-oxy-phenanthrene (DMAPhen), were prepared and investigated image sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (Δtilt). The VrDC values were small for the LC cells with the polymer layers produced from the Phen-carrying monomers used in this study. On the other hand, Δtilt depends on the molecular structure of the Phen-carrying monomer. The Δtilt values became small with increasing the linearity of the monomer structure for the Phen-carrying monomers. The findings would be useful for obtaining the small level of image sticking in the PSA-LCDs produced from the Phen-carrying monomers.

Implementation of a New Compact Inverter Structure Controlled by Numeric Sinusoidal Pulse Width Modulation for Photovoltaic Applications

In order to cover energy requirement, the photovoltaic is one of the proposed solutions. However, according to the aim of its utilization, the direct current output voltage of photovoltaic source should be adjusted. The boost inverter is a recent power processing stage that can increase, filter and alternate direct current input voltage. So as to control it, there are various modulation types. Among them, the sinusoidal pulse width modulation is presented in a new digital form. The operating principle of the aforementioned inverter and command have been analyzed and verified by simulation and realization. Furthermore, frequency analysis of output voltage signal proves efficient results.

Electrical impedance spectroscopy of a PET chip sandwiched between two disk electrodes: understanding the contribution of the polymer/electrode interface.

This work is devoted to the understanding of the dielectric impedance response of a semi-crystalline polyethylene terephthalate (PET) membrane sandwiched between two disk electrodes under alternate voltage excitation in the frequency range between 1 MHz and 25 mHz. Experimental results obtained for various PET thicknesses (36, 50 and 100 μm) highlighted the influence of the contact resistance at the electrode/polymer interface. For a better understanding of the PET/electrode interface behaviour, the experiments were compared with simulations performed for three different descriptions: the direct use of electrical equivalent circuits, an analytical model accounting for a power-law distribution of resistivity, and a numerical model (finite element simulations of the whole cell). The results highlight that the resistivity distribution obtained using the power-law model provided an appropriate description of the system in the frequency range investigated while the use of the CPE model is only consistent for low-frequencies (below 1 Hz).

Mechanisms of Destruction by Alternate Current

The mechanism of underground steel pipelines destruction by induced alternate currents in defects of waterproofing coat is considered in the article. Experimental assemblies have been developed to define the limit of qualitative change of character of degradation processes in steel under the action of alternate current. The change of processes’ character occurring on boundary “metal – electrolyte” with the increase of applied alternate voltage has been experimentally shown. For voltages more than 30 V the steel destruction becomes intensified by electroerosion phenomena.

An Alternative Voltage Ripple Control Strategy for the AGPS of the ITER Neutral Beam Injector

To construct a high power negative neutral beam injector, an ultra-high voltage power supply for acceleration grid is required. The acceleration grid power supply (AGPS) has been designed for ITER, based on neutral point clamped three phase three level inverter, step-up transformer and rectifier. The output voltage ripple is an important parameters for the AGPS, influencing the heating efficiency. This paper proposes an alternative voltage ripple control strategy. The new control strategy is illustrated and the design principles of the controller is discussed, based on the detail analyzing of operation processes and output characteristics of the AGPS circuit. Finally, simulations results are shown to verify the control system.

Static Variable Load for Grid-connected Photovoltaic System

This study addresses a static variable load for grid-connected photovoltaic system. In order to make the proposed system more improving powers disturbances, the interconnection of grid- photovoltaic assembled a reversible converter. The power circuit is composed of two 75 watts series photovoltaic panels associates to a static variable load with a dc-dc boost converter interconnect an alternative grid via reversible converter controlled by pulse width-modulation technique. In the dc–dc power conversion, the incremental conductance maximum power point tracking is introduced to improve the conversion efficiency of conventional boost converter. Moreover, a simple control system is designed for the current control of the reversible inverter to synchronize the output current to the alternative voltage in the grid and less variation under static load changes. Obtain results by using Matlab/simulink indicates that the present photovoltaic -grid system able to exchange the direction of active powers in the alternative grid for static variable load caused by reversible converter design.

Microelectromagnetic actuator based on a 3D printing process for fiber scanner application

A novel electromagnetic-actuated fiber scanner has been proposed for ultra-thin scanning fiber endoscope application. A free-fixed optical fiber cantilever with a cylindrical magnet can be driven and vibrated by a tilted coil on a tube surface under electromagnetic force. The tiny coil with a large tilt angle as the actuator is fabricated by a new three-dimensional (3D) printing technology and handmade hybrid process. It is an efficient and low-cost method for fabricating tiny 3D tilted coils compared with the complicated micromachining process. A 2.0 mm outer diameter tilted coil has been successfully developed. The line pitch, tilt angle, resistance and turns of this fabricated coil are 75 µm, 60°, 20 Ω and 100 turns, respectively. The scanning motion of the assembled scanner utilizing the fabricated 3D coil, fiber and a small magnet has been measured by a high-speed camera. The scanner consists of a 9 mm-length optical fiber, a 2 mm outer diameter cylindrical magnet, a jig and a fabricated tilted coil.The displacement of the fiber tip in the scanner is observed and measured when the alternative current-driven voltage was applied to the tilted coil, and 126.8 µm maximum displacement has been obtained. The present fiber scanner with 3D tilted coil has promise for use as an important inspecting device for biomedical endoscope application.

Unveiling characteristics of a bioelectrochemical system with polarity reversion for simultaneous azo dye treatment and bioelectricity generation.

A novel bioelectrochemical system (BES) operated with polarity reversion was explored for simultaneous anaerobic/aerobic treatment of azo dye and production of bioelectricity under extremely low buffer. The Congo red was first decolorized in anode, with completed color removal in 35 h. The resultant decolorization intermediates were then mineralized after the anode reversed to aerobic biocathode, evidenced by 55 % chemical oxygen demand (COD) removal in 200 h. The mineralization efficiency was further increased to 70 % when the period of the half-cycle was prolonged to 375 h. Meanwhile, the BES produced a continuous stable positive/negative alternate voltage output under 5 mM phosphate buffer because of the self-neutralization of the accumulated protons and hydroxyl ions in electrolyte. The electrode performance was significantly improved, which was indicated by alleviated electrode polarization, due to in situ use of accumulated protons and hydroxyl ions and enhanced electron transfer in the presence of Congo red and its degradation intermediates, which resulted in 1.05-fold increases in maximum power density (67.5 vs. 32.9 mW/m(2)). An analysis of the microbial diversity in the biofilm revealed that the biofilm was dominated by facultative bacteria with functional roles in contaminant degradation and electricity generation.

Effect of fluoride and water content on the growth of TiO2 nanotubes synthesized via ethylene glycol with voltage changes during anodizing process

In this work, titanium foils were anodized in ethylene glycol solutions containing different amounts of water and fluoride to determine their effects on the top morphology and crystalline structure of the formed titania nanostructures. Anodizing was performed for 2 h by using titanium foils as both anode and cathode applying a squared-pulse voltage profile composed of one step at 80 V for 3 min followed by another at 20 V for 5 min; constant voltage conditions were also used to study the nanostructure formation on the surface. We found the formation of nanostructured titania on the surface of the anodized foil when small amounts of water and fluoride are present in the anodizing solution. The top of these nanostructures is irregular when no water is added, but is expected to change with different amounts of water and fluoride in the ranges of 1 - 9% and 0.05 - 0.5%, respectively. Synthesis parameters also change nanotube morphology. The morphology and structure properties of the samples were studied by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). Formation of TiO2 nanotubes by anodization method are strongly correlated to conditions like fluoride concentration and applied voltages. Tube length varying between 2 and 7 μm, exhibiting different diameters and wall thicknesses were obtained. When an alternate voltage was applied, the wall of the nanotubes presented evenly spaced rings while nanotubes with smooth wall form were observed when constant voltage was applied. Reflection peaks corresponding to Brookite, Anatase, and Rutile of TiO2 phases were observed from XRD measurements. A correlation between the effects of synthesis parameters on nanotube formation and morphological properties is presented. TiO2 nanotubes prepared by electrochemical anodization have excellent performance in various applications such as photocatalysts, solar cells, gas sensors, and biomedical applications.

A new electrical configuration for improving the range of piezoelectric bimorph benders

This article describes a new electrical configuration for driving piezoelectric benders. The ‘Biased Bipolar’ configuration is compatible with parallel-polled, bimorph and multimorph benders. The new configuration is similar to the standard three-wire drive method where the top electrode is biased with a DC voltage and the bottom electrode is grounded. However, the new configuration uses an alternate DC bias voltage and adjusted range for the central electrode which allows the full range of positive and negative electric fields to be utilized. Using this technique, the predicted deflection and force can be increased by a factor of 2.2 compared to the standard two wire configuration and 1.3 times for the standard three wire configuration. These predictions were verified experimentally where the measured factor of improvement in displacement and force was of 2.4 and 1.3 compared to the standard two-wire and three-wire configurations.

静电纺丝制备K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub>纳米纤维及其压电发电性能研究

采用溶胶–凝胶静电纺丝技术制备无铅压电K0.5Na0.5NbO3 (KNN)纳米纤维，研究了退火温度和纺丝电压等对纳米纤维物相和形貌的影响。结果表明，退火处理后的纳米纤维是正交钙钛矿结构的KNN材料。随着退火温度的升高，纳米纤维的平均晶粒尺寸逐渐增大。当纺丝电压为6~12 kV时，KNN纳米纤维的直径随着电压的增大呈现先增加、后减小的趋势。将KNN纳米纤维在不同间距的叉指电极上进行组装，可获得能够输出交流脉冲电压的压电发电元件。输出电压的幅值可达190~430 mV，并随叉指电极间距的增加而增大。 The lead-free K0.5Na0.5NbO3 (KNN) nanofibers were fabricated through sol-gel electrospinning process. The effects of annealing temperature and electrospinning voltage on the phase and mor-phology of the products were investigated. The results show that the annealed nanofibers are or-thorhombic perovskite structured KNN materials. The increase of annealing temperature will lead to the increase of average grain size. When the electrospinning voltage is increased from 6 to 12 kV, the diameter of the nanofibers will be firstly increased and then decreased. By integrating the KNN nanofibers onto the interdigital electrodes, the piezoelectric generator can be obtained, which can generate impulsive alternative voltage. The amplitude of the output voltage is up to 190 - 430 mV, and will increase with the electrode spacing.

Investigation on static and dynamic performance of a hinge configuration with integrated dielectric elastomers

ABSTRACTA rigid hinge frame combined with pre‐stretched dielectric elastomer (DE) films can form an active biological agonist–antagonist configuration. In this structure, the DE films undergo a constant deformation under a static voltage as well as specific reciprocating rotation under an alternative voltage. To theoretically investigate the static and dynamic performance, we establish the kinetic equation of the active hinge configuration. The computational static rotary angle exhibits a good fit with the experimental data from literature. Based on this model, static performance of this configuration when DE undergoes uniaxial and pure shear deformation is investigated. Subject to a small perturbation, the configuration may oscillate around the equilibrium state and the natural frequency can be obtained. By varying the pre‐stretch ratios, applied voltage, layer number, and the rotational inertia of the hinge, we can tune the natural frequency at a wide range. When the voltage is sinusoidal and varies continuously, the configuration resonates at multiple frequencies of excitation, known as harmonic and superharmonic resonance. Our research may serve as a guide to optimal design and provide insights into the performance of the hinge configuration, which can effectively expand the structure's application fields. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41630.

Charging and absorption characteristics of small particulates under alternative and electrostatic voltages in an electrostatic precipitator

The charge quantity of small particulates such as PM2.5 plays a key role in the collection efficiency of an electrostatic precipitator (ESP). Under a single electrostatic voltage, it is difficult to charge and absorb small particulates. A new method of superimposing an alternative voltage on the electrostatic voltage is provided in this paper. Characteristics of small particulates are analyzed under alternative and electrostatic voltages. It is demonstrated that an alternative voltage can significantly improve the collection efficiency in three aspects: preventing anti-corona, increasing the charge quantity of small particulates, and increasing the median particulate size by electric agglomeration. In addition, practical usage with the superposition of alternative voltage is provided, and the results are in agreement with the theoretical analysis.

Laser annealing of plasma-damaged silicon surface

13.56MHz capacitance coupled Ar plasma irradiation at 50W for 120s caused serious damage at SiO2/Si interfaces for n-type 500-μm-thick silicon substrates. The 635-nm-light induced minority carrier effective lifetime (τeff) was decreased from 1.7×10−3 (initial) to 1.0×10−5s by Ar plasma irradiation. Moreover, the capacitance response at 1MHz alternative voltage as a function of the bias voltage (C–V) was changed to hysteresis characteristic associated with the density of charge injection type interface traps at the mid gap (Dit) at 9.1×1011cm−2eV−1. Subsequent 940-nm laser annealing at 3.7×104W/cm2 for 4.0×10−3s markedly increased τeff to 1.7×10−3s and decreased Dit to 2.1×1010cm−2eV−1. The hysteresis phenomenon was reduced in C–V characteristics. Laser annealing effectively decreased the density of plasma induced carrier recombination and trap states. However, laser annealing with a high power intensity of 4.0×104W/cm2 seriously caused a thermal damage associated with a low τeff and a high Dit with no hysteresis characteristic.

English

Now-a-days due to the shortage of electric power and rising cost of non-renewable energy resources generating electric power from the renewable energy resources such as PV modules are increasing day to day. This paper presents non-isolated, high step-up dc-dc converter with hybrid transformer with for low voltage renewable energy resources applications. The proposed converter utilizes hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving high step-up voltage with smaller sized magnetic component, the turn-off loss of switch is minimized, increasing the efficiency of the converter under all load conditions. By changing the input voltage the voltage stresses on the active switch and diodes are maintained at low level and are independent as a result of the resonant capacitor transferring energy to the output of the converter. Due to high system efficiency as well as ability to operate with a wide variable input voltage, the proposed dc-dc converter is an attractive design for alternative low dc voltage energy sources, such as solar PV modules and fuel cells.