Apinai Rerkratn

Bio: Apinai Rerkratn is an academic researcher from King Mongkut's Institute of Technology Ladkrabang. The author has contributed to research in topics: Amplifier & Voltage. The author has an hindex of 7, co-authored 48 publications receiving 161 citations.

Pulse Induction Metal Detector Using Sample and Hold Method

Abstract: This paper presents the Pulse Induction Metal Detector Using Sample and Hold Method. The proposed method is to measure output voltage from search coil. The system consists of the pulse generator circuit, amplifier circuit, integrator circuit, three mono-stable circuits, sample and hold circuit, comparator circuit and display circuit. The voltage output signal of the proposed technique is proportional to size, shape and type of metal target. The metal target with differential size was used in our experiment as an illustrative case study. Experimental results show that the proposed method can detect metal with satisfied sensitivity and good linearity.

Integration of WirelessHART and ISA100.11a field devices into condition monitoring system for starting IIoT implementation

Abstract: This paper presents a technique to integrate wireless field devices using WirelessHART and ISA100.11a technologies into a condition monitoring system based on Wonderware InTouch software. The proposed integration brings the data from a field site with digital multi-device networking for automatic data collection to support the condition monitoring of instruments or smart connected equipment in preparation of the Industrial Internet of Things (IIoT) implementation. Data including process variables and diagnostics from WirelessHART and ISA100.11a devices are buffered and mapped into Modbus/TCP registers for real-time monitoring at the operator workstation. Experimental results confirm that the proposed integration functions correctly.

Four-quadrant analogue multiplier using operational amplifier

Abstract: A method to realise a four-quadrant analogue multiplier using general-purpose operational amplifiers (opamps) as only the active elements is described in this article. The realisation method is based on the quarter-square technique, which utilises the inherent square-law characteristic of class AB output stage of the opamp. The multiplier can be achieved from the proposed structure with using either bipolar or complementary metal-oxide-semiconductor (CMOS) opamps. The operation principle of the proposed multiplier has been confirmed by PSPICE analogue simulation program. Simulation results reveal that the principle of proposed scheme provides an adequate performance for a four-quadrant analogue multiplier. Experimental implementations of the proposed multiplier using bipolar and CMOS opamps are performed to verify the circuit performances. Measured results of the experimental proposed schemes based on the use of bipolar and CMOS opamps with supply voltage ±2.4 V show the worst-case relative errors of 0.32...

ZigBee based wireless temperature monitoring system for shrimp farm

Abstract: This paper proposes a design and implementation of wireless temperature monitoring system for shrimp farm based on ZigBee technology. The proposed system consists of three wire resistance temperature device (RTD) type PT-100, Current source circuit, XBee Pro module, 2.4 GHz antenna with gain 5dBi, Arduino Uno R3 microcontroller board and LabVIEW program for monitoring and control system. Experimental results with standard temperature bath show that the proposed system can monitor temperature with satisfied data. The maximum error of temperature is about 0.25 percents. The maximum range of system is about 500 meters.

8-Electrode Data Collection System For Electrical Capacitance Tomography

Abstract: An 8-electrode data collection system for electrical capacitance tomography is presented. The system mainly consists of a signal generator, 8times2 multiplexer, detector, amplifier, band-pass filter, rms-to-dc converter, A/D converter circuit and control computer. Experimental results with a circular sensor show that the proposed system is able to collect data with satisfactory sensitivities, linearity, resolution and also being insensitive to noise. Reconstructed images from collected data are shown

1D/2D Carbon Nanomaterial‐Polymer Dielectric Composites with High Permittivity for Power Energy Storage Applications

Abstract: With the development of flexible electronic devices and large-scale energy storage technologies, functional polymer-matrix nanocomposites with high permittivity (high-k) are attracting more attention due to their ease of processing, flexibility, and low cost. The percolation effect is often used to explain the high-k characteristic of polymer composites when the conducting functional fillers are dispersed into polymers, which gives the polymer composite excellent flexibility due to the very low loading of fillers. Carbon nanotubes (CNTs) and graphene nanosheets (GNs), as one-dimensional (1D) and two-dimensional (2D) carbon nanomaterials respectively, have great potential for realizing flexible high-k dielectric nanocomposites. They are becoming more attractive for many fields, owing to their unique and excellent advantages. The progress in dielectric fields by using 1D/2D carbon nanomaterials as functional fillers in polymer composites is introduced, and the methods and mechanisms for improving dielectric properties, breakdown strength and energy storage density of their dielectric nanocomposites are examined. Achieving a uniform dispersion state of carbon nanomaterials and preventing the development of conductive networks in their polymer composites are the two main issues that still need to be solved in dielectric fields for power energy storage. Recent findings, current problems, and future perspectives are summarized.

The effects of salinity and temperature on the growth and survival rates of juvenile white shrimp, Penaeus vannamei, Boone, 1931

Abstract: The growth and survival of Penaeus vannamei postlarvae was measured at temperatures of 20, 25, 30 and 35 °C and salinities of 20, 30, 35, 40 and 50%.. Groups of 30 animals were used in each combination of conditions, in triplicate. The results clearly show that juveniles of this species have their best survival between temperatures of 20 and 30 °C and salinities above 20%.. Best growth was obtained between temperatures of 25 and 35 °C, with little difference being noted among salinities. Survival and growth coincide best at around 28 to 30 °C and 33 to 40%.. Calculated overall production was shown to be best in these conditions. The results demonstrate a high coincidence between the experimentally determined optimum conditions for production and the prevailing conditions in the coastal environment from which the animals originated.

Pulsed eddy current imaging and frequency spectrum analysis for hidden defect nondestructive testing and evaluation

Abstract: Hidden defect characterisation in some complex structures is difficult. Pulsed Eddy Current (PEC) imaging based on rectangular excitation coil is investigated in this paper and hidden defect nondestructive testing and evaluation (detection, classification, and quantification) is carried out based on the various C-scan images. Experimental results have illustrated that hidden defects can be identified effectively by particular character in C-scan imaging results and sub-surface defects can be discriminated to correct class by selecting the rising time from response in time domain. The quantification information of hidden defects is preliminarily obtained based on the contour and 3D images. In addition, PEC imaging and frequency spectrum analysis are effective to detect, classify, and evaluate the sub-surface defects under the influence of edge effect of specimen. To sum up, PEC imaging is an effective approach to characterise hidden defects and sub-surface defects.