Wave AC Research Articles

Real time detection of fatigue cracks on steel structures by applying square wave induction

For years the Eddy currents principle together with inductive thermography have been applied to detect cracks or defects in metallic machine components. In case a component has a crack, by inducing Eddy currents within a coil, it is possible to cause a temperature increase in the edges of the crack. This temperature variation can be observed by using an infrared camera. Thus, the crack is registered and observed in the infrared images, which are later analyzed. However, currently used systems require an enormous amount of power and a long time for image processing. For this reason, applying this method to large steel structures such as bridges, cranes, wind power towers, pipe lines or offshore oil stations has been much more complex. To overcome these limitations, a light portable system that optimally recreates the Eddy currents principle has been developed and used in this research. This system generates a square wave AC voltage, it uses considerably less power and it is capable of detecting cracks in real time. This paper presents the simulations and experiments carried out on two different structural steel specimens to demonstrate the efficiency of the system and its potential in the field of nondestructive testing.

3-Level Flying Capacitor Inverter with Trapezoidal Wave AC Heating Capability for Automotive Batteries

3-Level Flying Capacitor Inverter with Trapezoidal Wave AC Heating Capability for Automotive Batteries

Mathematical Modeling and Analysis of Capacitor Voltage Balancing for Power Converters with Fewer Switches

The multilevel inverter (MLI) has been developed as a powerful power conversion scheme for several processes, including renewable energy, transmission systems, and electric drives. It has become popular across medium- to high-power operations due to its many advantages, including minimum harmonic content, low switching losses, and reduced electromagnetic interference (EMI). In this paper, the capacitor voltage balancing technique-based pulse width modulation (PWM) has been proposed. The proposed PWM strategy offers several advantages, such as high-quality output waveforms with reduced harmonic distortion, improved efficiency, and better control over the output voltage. The Xilinx ISE 10.1 software was used for synthesizing, and the VHDL code was written for the proposed method. MATLAB software was used to simulate and hardware was used to verify the proposed system. The SPARTAN 3E FPGA was used for the generation of the PWM. This paper developed a 2 kW single-phase 15-level inverter that created an AC wave from the DC input voltage, with a total harmonic distortion (THD) of 8.02%, which was less than the THD achieved from other conventional MLI. The results indicate that MLI topologies with low total harmonic currents, fewer switches, and higher output voltage levels are better stabilized during load disturbance circumstances.

Ethernet Over Coaxial (EoC) Cable Telemetry Over High Voltage Dc And High Power Ac For Airborne Sonar Applications


 
 
 We have proposed a new passive component-based coupling scheme to simultaneously transmit high power AC, high voltage DC and high speed data through a long, single core coaxial cable, particularly for Airborne Sonar applications. This method is intended to replace the bulky multicore cables with single core coaxial cables that are compact and effective for transmitting data over long distances. This coupling scheme consists of three couplers to superimpose high power AC, high voltage DC and high speed data at the onboard end of the cable, and three decouplers to separate them at the remote end. The long cable, couplers, decouplers and the acoustic transducer are represented by their corresponding equivalent circuits that are cascaded together to construct the complete network. Power loss in the circuit is minimised by providing impedance matching networks in the form of a T-network transmission line and a tuning coil. The Ethernet over Coaxial (EoC) module can transmit high speed Ethernet data at the rate of 10/100 Mbps for telemetry from onboard to remote units and vice versa. DC voltages up to 300 V are coupled to the single core coaxial cable from the onboard unit and superimposed with high power AC signals and high-speed data. Passive filter-based coupling and decoupling schemes are demonstrated. Network simulation studies and experimental studies are carried out to verify and validate the equivalent circuit model. The transfer functions of each set of couplers and decouplers are determined independently as well as collectively and their effects on the underwater acoustic performance of the system are studied. The model resuls are found to agree with experiments. The proposed system is capable of generating an acoustic Source Level of about 195 dB with the supply of 125 V continuous wave (CW) AC signals, with simultaneous transmission of data at 10 Mbps and DC supply of 260 V from the on-board unit to the remote unit at the end of a coaxial cable of 200 m length. Introduction of impedance matching network is found to increase the source level by about 12 dB.
 
 

Pelatihan Perancangan dan Pengaplikasian Alat INTENSOR

Technological developments have a role in the competition for metal processing in the home industry, namely the development of metal heating devices. However, the home industry needs to consider environmentally friendly metal heaters. One of the environmentally friendly metal heaters is an induction heater. Induction heater has a metal heating technique by utilizing electromagnetic induction which is more efficient than using a conventional metal heating furnace. Induction heaters have advantages in terms of easier use, efficient in terms of energy, time and temperature regulation. Induction heating is a metal heating technique by utilizing electromagnetic induction from high frequency AC waves, which is more efficient than using conventional metal heating furnaces. This problem is the basis for holding training on the design and application of the INTENSOR tool. This community service activity has had quite a good impact in: 1) increasing the knowledge and skills of metal processing business actors in designing INTENSOR tools; 2) increase the knowledge of metal processing business actors in making and applying INTENSOR tools. Community service activities are carried out for 6 months and are intended for metal processing business actors.

Quantifying Deformation and Migration Properties of U87 Glioma Cells Using Dielectrophoretic Forces.

Glioblastoma multiforme is one of the most aggressive malignant primary brain tumors. To design effective treatment strategies, we need to better understand the behavior of glioma cells while maintaining their genetic and phenotypic stability. Here, we investigated the deformation and migration profile of U87 Glioma cells under the influence of dielectrophoretic forces. We fabricated a gold microelectrode array within a microfluidic channel and applied sinusoidal wave AC potential at 3 Vpp, ranging from 30 kHz to 10 MHz frequencies, to generate DEP forces. We followed the dielectrophoretic movement and deformation changes of 100 glioma cells at each frequency. We observed that the mean dielectrophoretic displacements of glioma cells were significantly different at varying frequencies with the maximum and minimum traveling distances of 13.22 µm and 1.37 µm, respectively. The dielectrophoretic deformation indexes of U87 glioma cells altered between 0.027-0.040. It was 0.036 in the absence of dielectrophoretic forces. This approach presents a rapid, robust, and sensitive characterization method for quantifying membrane deformation of glioma cells to determine the state of the cells or efficacy of administrated drugs.

Using a web-based and stand-alone oscilloscope for physics experiment during Covid-19 pandemic

Teaching alternating currents, ac or sound waves, is incomplete without an introduction to the oscilloscope. An oscilloscope is a tool that graphically displays electrical signals and shows their time dependence. However, due to the pandemic, triggered by the SARS-CoV-2 virus, many students do not have the opportunity to master the use of an oscilloscope. Face-to-face teaching activity has been interrupted in both schools and higher institutions. The sudden change to online teaching created problems among educators, especially for laboratory activities. The central issue is creating laboratory activities without going into the labs for the students to acquire the required skills, especially the basics of how to operate an oscilloscope. In order to create an opportunity and engaging environment, we suggested the use of the ‘web-based and stand-alone oscilloscope’. The software consists of a low-frequency (signal) generator (LFG), a direct current power supply, and an oscilloscope. The LFG is capable of producing several types of signal and the software is designed to aid the undergraduate engineering and physics students in learning the operation and functions of a digital storage oscilloscope. It can be used as an alternative to face-to-face laboratory activity for physics experiments. It is free and easy to use. The experiments enable students to develop the experimental and measurement skills related to signal generators and oscilloscopes. Hence it opens the opportunity of ‘doing’ virtual physics investigations individually at home.

(Digital Presentation) Develop Cell Internal Resistance Measurement Tool As a Lib Cell Characterization Technology

As LiB cell is not a pure ohmic device but a complex electrochemical device with capacitive and inductive behaviors, its characteristic and performance will vary depending on the input signals, frequencies, and usage conditions. And as LiB cell is a non-linear system, its internal resistance (IR) depends significantly on variables, like aging (state of Health: SOH), state of charge (SOC), temperature, applying current rate and period. The IR is an intrinsic property of a cell representing its characteristic, performance, and health status at the measuring point. Therefore, its precise measurement is essential for its usage for cell characterization, quality control (QC), and grading-selection criteria for designing cell, module, pack, host system, and thermal management, health monitoring-prediction criteria. However, IR measurement is inherently complex and requires sophisticated procedures (1,2). Direct wave DC pulse and AC electrochemical impedance spectroscopy (EIS) are the prevalent techniques used for cell IR characterization (1,2). Most cell QC processes use the AC-impedance tool at 1.0 kHz with voltage, and IEC-62660 adopt a DC pulse, Hybrid Pulse Power Characterization (HPPC) method, and new proposals, like a multisine signals method and a pulse-multisine, have been proposed (1,2). However, the AC-impedance tool (1.0 kHz) cannot represent the dynamic behaviors of the cell and system compared to the DC pulse (3). In addition, some DC pulse test requires pre-testing conditions and a long test period; furthermore, there is no harmonized test technologies among the battery standards and some best practices of the LiB cell testing and characterization. To adopt a test method and condition as a QC tool for cell characterization that should be simple and not be time-consuming on pre-measurement condition and testing procedure to perform (3).This research aims to propose simple IR measurement tools in which test results are comparable with each other’s and do not require a long period of pre-test conditioning time and a time-consuming test period. We evaluated four test methods of the cell IR measurement at four temperature conditions (0 ~ 5 ℃, RT (20 ~ 25 ℃), 35 ℃, and 45 ℃). In addition, we selected five types of cell groups (two 18650 cells, two pouch-type cells, and one prismatic cell) to evaluate the IR. The four IR measurement test methods are classified with DC pulse tools (simplified DC pulse method and HPPC) and AC pulse signal tools (Full range EIS and AC-pulse Impedance at 1.0 kHz). Test results studied the relationship between cells’ IR response behaviors by each type of pulse and the electrochemical mechanism of the cells. After comparing those test results, the best IR characterization tool and procedure will be proposed as a standard LiB cell characterization technology.We found the simplified DC pulse method is simple and not time-consuming on both pre-test condition and testing procedure to perform and provide reasonable dynamic behaviors of the cell system compared to other methods. Figure 1 shows the trends of cell IR changes according to the experimental variables, applied current rate and frequency from the simplified DC pulse method. The blue color dot zone shown the optimum applied current rate and frequency and the red color dot zone shown the optimum frequency (3).Reference:1) Thomas R. B. Grandjean, Jakobus Groenewald, Andrew McGordon, Widanalage D. Widanage and James Marco, Batteries 2018, 4, 49; doi:10.3390/batteries4040049.2) Mohammad A. Hoque, Petteri Nurmi, Arjun Kumar, Samu Varjonen, Junehwa Song, Michael G. Pecht, Sasu Tarkoma Journal of Power Sources 513 (2021) 2305193)3) Jaesik Chung, Kwang Jung, and Giovanni Flores, 2020 NASA Aerospace Battery Workshop November 17 ~ 19 2020 Figure 1

Particle-Induced Electrostatic Repulsion within an Electric Curtain Operating below the Paschen Limit.

The electric curtain is a platform developed to lift and transport charged particles in air. Its premise is the manipulation of charged particles; however, fewer investigations isolate dielectric forces that are observed at lower voltages (i.e., less than the Paschen limit). This work focuses on observations of simultaneous dielectrophoretic and electrostatic forces. The electric curtain was a printed circuit board with interdigitated electrodes (0.020 inch width and spacing) coated with a layer of polypropylene, where a standing wave or travelling wave AC signal was applied (50 Hz) to produce an electric field below the Paschen limit. Soda lime glass beads (180–212 µm) demonstrated oscillatory rolling via dielectrophoretic forces. In addition, several particles simultaneously experienced rapid projectile repulsion, a behavior consistent with electrostatic phenomena. This second result is discussed as a particle-induced local increase in the electric field, with simulations demonstrating that a particle in close proximity to the curtain’s surface produces a local field enhancement of over 2.5 times. The significance of this is that individual particles themselves can trigger electrostatic repulsion in an otherwise dielectric system. These results could be used for advanced applications where particles themselves provided triggered responses, perhaps for selective sorting of micrometer particles in air.

Demystifying frame aggregation in 802.11 networks: Understanding and approximating optimality

MAC-layer frame aggregation has significantly improved the efficiency of IEEE 802.11n and 802.11ac networks by placing multiple MAC-layer data units in a large PHY-layer frame. In this paper, we focus on finding the optimal length of an Aggregated MAC Protocol Data Unit (A-MPDU) in order to maximize throughput. In theory, larger A-MPDUs amortize overheads over more bits and therefore increase throughput. However in practice, throughput can be negatively impacted if too many frames are aggregated, due to higher error rates at the end of A-MPDUs. Determining the optimal number of subframes is challenging because error rates can be higher in the later part of the A-MPDU which change with factors such as mobility, speed and transmission rate. Additionally, there are dependencies between consecutive A-MPDUs due to software retransmissions.We develop a model of A-MPDU frame aggregation and use it to design a statistically optimal algorithm. Using our understanding of that algorithm we develop a standard compliant, Practical, Near-Optimal Frame Aggregation algorithm (PNOFA). Our trace-based evaluation shows that across a variety of devices and scenarios PNOFA outperforms existing state-of-the-art algorithms and obtains throughputs that are within 97% of those obtained using the statistically optimal algorithm. Furthermore, we implement PNOFA as a user-space process on an 802.11ac Wave 2, Google Wifi access point. We find that when compared with the frame aggregation algorithm provided in the device’s Qualcomm IPQ 4019 chipset’s firmware, PNOFA increases average throughput by 17% and 13% for UDP and TCP traffic on the scenarios tested.

Simulation model of Ximeng-Taizhou 800 kV UHVDC transmission system based on PSCAD

In order to study the changing characteristics of electrical variables during the operation process of UHVDC system with hierarchical connection to AC system, using the main circuit parameters of Ximeng-Taizhou 800 kV UHVDC transmission system which has been put into operation and referring to the control system of CIGRE HVDC standard test system, the simulation models of the AC system, converter, converter transformer, flat wave reactor, AC and DC filter and DC line of the transmission system of the Ximeng-Taizhou project are established by PSCAD. The model is used to simulate the positive, negative and bipolar full voltage operation mode, and the simulation results are compared with the system design parameters. It can be seen that the simulation model can more accurately simulate the Ximeng-Taizhou project, and can be used as an effective simulation tool for further research on the UHVDC transmission projects such as the Ximeng-Taizhou project with hierarchical connection to AC system.

Comparison of Inverter Types for Home Appliance Using Push-Pull Amplifier

This paper deals with a comparison of inverter types and develops a system to provide pure sine wave ac voltage. The ac voltage is utilized to drive the compressor ac split. The assembled inverter problem is a square waveform, power losses, torque, efficiency, and a lag behind in terms of performance reliability. The push-pull amplifiers technic is proposed to produce sine wave output from dc input. The output result shows that an experimental pure sin wave obtains a frequency of 50.05 Hz, V max 13.49 Volt, V min -14.49 volt, and duty cycle 50.1%. the assembled inverter has a frequency is 37.87 Hz, V max 11.88 Volt, V min 13.09 volt, and a duty cycle is 50 %. A modified 3-phase inverter attains frequency 50.05 Hz, V max 15.71 Volt, V min -16.11 Volt, and the duty cycle is 50.5 %. The frequency, v max, v min, and duty cycle are bigger than an assembled inverter, then the modified 3-phase inverter has small harmonic distortion. The comparison of inverter types gives information for home appliances.

Research on Ultrasonic Power Supply Based on Cascade Buck Technology

In view of the large voltage harmonics and low power density of the low-power ultrasonic power supply, a low-power ultrasonic power supply based on the cascade buck technology is proposed. The converter of the power supply is composed of two buck units in cascade, and the output of the unit is forward Sinusoidal half-wave DC voltage waveform, and then commutated by the full-bridge inverter every half cycle to output sine wave AC voltage waveform, can significantly reduce the voltage harmonics of the ultrasonic power supply, reduce the inductance of the matching network, and improve the ultrasonic wave Power density. Through the combination of voltage and current phase detection and PI regulator, the tracking resonance frequency is controlled. By analyzing the system structure, working principle and control strategy of the ultrasonic power supply, modeling and simulation are carried out on Matlab / Simulink, and the feasibility and effectiveness of the scheme are verified.

Investigation of Ionic EAP Actuators with Metal and Polymer Electrodes in Aqueous Medium

Electroactive polymers (EAP) are promising materials for creating electromechanical transducers. Among ionic EAP, ionic polymer-metal composites (IPMC), which are an ion-exchange membrane with metal electrodes on both sides, have been widely spread and well studied. The evolutionary development of IPMC results in ionic polymer-polymer composites (IP2C), in which polymer electrodes are used. To obtain IPMC actuators with platinum electrodes, the method of chemical reduction from the salt solution was chosen, and to obtain IP2C actuators with PEDOT electrodes, the method of in situ polymerization of the monomer on the membrane surface was chosen. Samples of 2x0.5 cm in size based on the MF-4SK membrane with a thickness of 290 μm were preliminarily kept in deionized water (H+ form) and in 0.1 M CuSO4 aqueous solution (Cu2+ form), after which their performance was studied in air, in deionized water, as well as in aqueous solutions of CuSO4 and NaCl. When applying a DC voltage and a sine wave AC voltage, a decrease in the maximum displacement and peak-to-peak displacement of the IPMC actuators and IP2C actuators with an increase in the ionic strength of the liquid was observed, except for the case of the IPMC actuator operation in CuSO4 aqueous solutions. In all considered media, the IPMC actuators and IP2C actuators in Cu2+ form displaced more strongly than the corresponding samples in H+ form, except for the IP2C actuators in deionized water. The largest peak-to-peak displacement was demonstrated by the IPMC actuators in Cu2+form when operating in air (5 mm) and the IP2С actuators in H+ form when operating in deionized water (8.4 mm).

Experimental Evaluation of Defects in Ferromagnetic Steel Tube by Electromagnetic Sensor Using Square Wave AC Magnetic Field with DC Bias

Experimental Evaluation of Defects in Ferromagnetic Steel Tube by Electromagnetic Sensor Using Square Wave AC Magnetic Field with DC Bias

Wide Range Variable Voltage Transformerless DC Power Supply Using TRIAC

<p class="Abstract">Variable voltage DC power supply that has wide range of power, lightweight and inexpensive is quite difficult to obtain. This research designs and tests a DC power supply without a transformer using switching technology that utilizes TRIAC. The 220 Volt AC power source is converted to DC electricity by the method of cutting off some AC waves signal, using TRIAC, and then rectifying it with diodes and filters. DIAC functions as a trigger TRIAC at the specified time, by turning the variable resistor. The test results show that the output DC power voltage can be adjusted from 5 Volts to 75 Volts by adjusting the DIAC resistance and the load resistance. The results of the series image characteristics are given 2-dimensional and 3-dimensional graphics.<em></em></p>

A Numerical Investigation of Enhancing Microfluidic Heterogeneous Immunoassay on Bipolar Electrodes Driven by Induced-Charge Electroosmosis in Rotating Electric Fields

A unique approach is proposed to boost on-chip immuno-sensors, for instance, immunoassays, wherein an antibody immobilized on the walls of a microfluidic channel binds specifically to an antigen suspended freely within a working fluid. The performance of these sensors can be limited in both susceptibility and response speed by the slow diffusive mass transfer of the analyte to the binding surface. Under appropriate conditions, the binding reaction of these heterogeneous immuno-assays may be enhanced by electroconvective stirring driven by external AC electric fields to accelerate the translating motion of antigens towards immobilized antibodies. To be specific, the phenomenon of induced-charge electroosmosis in a rotating electric field (ROT-ICEO) is fully utilized to stir analyte in the vicinity of the functionalized surface of an ideally polarizable floating electrode in all directions inside a tri-dimensional space. ROT-ICEO appears as a consequence of the action of a circularly-polarized traveling wave signal on its own induced rotary Debye screening charge within a bipolar induced double layer formed on the central floating electrode, and thereby the pertinent electrokinetic streamlines exhibit a radially converging pattern that greatly facilitates the convective transport of receptor towards the ligand. Numerical simulations indicate that ROT-ICEO can enhance the antigen–antibody binding reaction more effectively than convectional nonlinear electroosmosis driven by standing wave AC signals. The effectiveness of ROT-ICEO micro-stirring is strongly dependent on the Damkohler number as well as the Peclet number if the antigens are carried by a continuous base flow. Our results provide a promising way for achieving a highly efficient heterogeneous immunoassay in modern micro-total-analytical systems.

Drive-induced many-body localization and coherent destruction of Stark many-body localization

We study the phenomenon of many-body localization (MBL) in an interacting system subjected to a combined DC as well as a square wave AC electric field. First, the condition for the dynamical localization, coherent destruction of Wannier-Stark localization and super Bloch oscillations in the non-interacting limit, are obtained semi-classically. In the presence of interactions (and a confining/disordered potential), a static field alone leads to "Stark many-body localization", for sufficiently large field strengths. We find that in the presence of an additional high-frequency AC field, there are two ways of maintaining the MBL intact: either by resonant drive where the ratio of amplitude to the frequency of the drive ($A/\omega$) is tuned at the dynamical localization point of the non-interacting limit or by off-resonant drive. Remarkably, resonant drive with $A/\omega$ tuned away from the dynamical localization point leads to a \emph{coherent destruction of Stark-MBL}. Moreover, a pure (high-frequency) AC field can also give rise to the MBL phase if $A/\omega$ is tuned at the dynamical localization point of the zero dc field problem.

High-frequency pulse-modulated square wave AC TIG welding of AA6061-T6 aluminum alloy

Bead-on-plate welding of 6-mm thick AA6061-T6 aluminum alloy is used to characterize the high-frequency (HF) pulse-modulated square wave AC TIG (HFPM AC TIG) welding. The modulation HF pulse reduces the reignition voltage of negative half-wave arc. However, its effectiveness on increasing weld penetration is not evident until the penetration rate (penetration-to-workpiece thickness ratio) exceeds 45%. Above this value, the weld penetration increases significantly with increasing peak current of the HF pulse, and first increased and then decreased with increasing pulse frequency from 10 to 40 kHz. Maximum penetration achieved at optimal welding condition increases by 120% compared with that of conventional AC TIG welding. The grain size and width of partially melted zone are visibly reduced. The average equiaxed grain size, pore number density, and average pore size in HFPM AC TIG weld metal decrease with increasing pulse frequency.

HF pulse effect on microstructure and properties of AC TIG butt-welded joint of 6061Al alloy

Abstract Butt joint welding of 6 mm thickness of 6061 aluminum alloy was used to characterize the high frequency (HF) pulse modulated square wave AC TIG (HFPM AC TIG) welding with filler wire addition. The heat input required for achieving fully penetrated weld is remarkably reduced by the modulation HF pulse. The weld penetration is increased and weld width is decreased at the same equivalent current. The width of partially melted zone, dissolution zone and overaged zone are all decreased. The formation of columnar grain around the fusion line is suppressed and the formation of the equiaxed grain is promoted. The number density and average size of micro-pores in weld metal are greatly reduced. The softening effect of welding thermal cycle is significantly relieved. The strength and elongation of the welded joint are increased by 8.5 % and 19.8 % respectively, and the strength and elongation of the weld metal are increased by 6.1 % and 46.1 % respectively.