A water level measurement using an interdigital capacitive sensor with low-cost, low-energy, good repeatability, high linearity, and ease of installation is proposed with a support of experimental results. This sensor comprises a printed circuit board (PCB) with configuration of two interpenetrating comb electrodes. The comb electrode is 70–80 mm width, 300 mm height with 1–2 mm spacing between each comb. This configuration of electrode causes the capacitance between comb electrodes to vary by the water level. Microcontroller is used to calculate the capacitance between comb electrodes in terms of a discharge time correlated to the water level. A practical water level measurement technique using two comb electrodes designated as level and reference sensors is presented. This technique can directly be applied to water with different conditions without recalibration. This sensor is able to measure absolute levels of water with 0.2 cm resolution over 30 cm range. In addition, it is also sensitive enough to trace the variability of water level. A flood monitoring simulation is carried out in wave flume where this sensor is used to detect the rising wave.

A self-calibration water level measurement using an interdigital capacitive sensor

A Review of Smart Parking System and its Technology

Water level sensing: State of the art review and performance evaluation of a low-cost measurement system

Fibre Bragg grating (FBG) pressure sensors show a great potential in replacing conventional electrical pressure sensors due to their numerous advantages. However, increasing their pressure sensitivity performance for low hydrostatic pressure measurement is still a challenge. This paper reviewed recent pressure sensitivity enhancement methods that could be divided into two groups, namely intrinsic and extrinsic. For the intrinsic enhancement method, this paper reviewed polymer FBGs, special fibre sensors, interferometric sensors, and special grating sensors. For the extrinsic enhancement method, polymer-based pressure transducers, diaphragm-based pressure transducers, and other structure-based pressure transducers were reviewed in detail.

Review of high sensitivity fibre-optic pressure sensors for low pressure sensing

This paper presents the design and fabrication of a liquid-level measurement system based on a grounded cylindrical capacitive sensor for conductive liquids. Fabrication of the cylindrical capacitive sensor is performed with a novel approach of shielded cable. The inner conductor of shielded cable is connected to ground and the outer conductor is used to measure the liquid level. The relationship between the capacitance value of the cylindrical capacitive sensor and the liquid level is deduced by the analysis and calculation of physical parameters. Moreover, a backward difference calculation is adopted in order to offset the effects of the parasitic capacitance. The performance of the system has been experimentally tested in both grounded metallic and plastic containers. The experimental results show that the nonlinear error is smaller than 5 mm over a range of 90 cm. Over a wide measuring range of 200 cm, the liquid-level measurement system has a nonlinear error smaller than 1.35 cm.

Structure design and performance analysis of a coaxial cylindrical capacitive sensor for liquid-level measurement

Gros Michel banana soluble solids content evaluation and maturity classification using a developed portable 6 channel NIR device measurement

Interdigital capacitance sensing of moisture content in rubber wood

In this paper, an experimental study of human movement effects in indoor wireless networks on the performance of the received signal strength indicator (RSSI)-based trilateration method is presented. The contribution of this work is that how the RSSI fluctuation caused by human movements nearby a target node influences the estimation accuracy of the trilateration method is studied. Additionally, efficient adaptive filters which can observe RSSI variation levels and select appropriate inputs (i.e., distance values converted from RSSI values) are proposed for handling the RSSI variation problem and compensating the position estimation error. Experiments using low-cost 2.4-GHz wireless nodes have been set and tested in a laboratory room. Results demonstrate that, during the human blocking the communication link between the transmitter and the receiver, RSSI data are fluctuated and the trilateration method shows a large estimation error. Here, the localization accuracy significantly depends on the RSSI variation level. The experimental results also indicate that, by applying our proposed solutions, they can automatically provide appropriate inputs for the trilateration method. The estimation error decreases by 43.76% and 46.28% for our test scenarios.

Human movement effects on the performance of the RSSI-based trilateration method: adaptive filters for distance compensation

The objective of this research is to propose procedures for measuring service life and evaluating the quality of locally made and used solid tires in Thailand. The solid tires were stressed and rotated until blowout on a drum-like test apparatus which is designed, constructed by the authors and equipped with laboratory instrumentation. Solid tires from five different manufacturers were selected for testing. We measured service life, length of time to tire failure, at three different loading amplitudes and three different speeds on the testing drum. The service life of all specimens was studied and compared to determine the possibility of using service life to evaluate the quality of a solid tire.

https://rdo.psu.ac.th/sjstweb/journal/32-4/0125-3395-32-4-387-390.pdf

Kanadit Chetpattananondh

Papers

A self-calibration water level measurement using an interdigital capacitive sensor

Gros Michel banana soluble solids content evaluation and maturity classification using a developed portable 6 channel NIR device measurement

Interdigital capacitance sensing of moisture content in rubber wood

Human movement effects on the performance of the RSSI-based trilateration method: adaptive filters for distance compensation

Measuring service life and evaluating the quality of solid tires