Direct Strain and Stress Measurement for Prestressed Steel.

Bridge assessment requires knowledge of the design prestress and of any losses that may occur since stressing. The knowledge on state of stress in prestressing wires of prestressed beams is a very important criteria when assessment is conducted on an existing prestressed concrete structures. The high initial stress could slowly decrease due to creep, shrinkage and relaxation, effects. The reduction in stress could also occur abruptly due to slippage and loss of concrete area. The development of electronic instruments that test, measure, and control industrial processes has gone through a rather impressive growth pattern in recent years. In most industrial applications, the requirement of effective measurement method is very essential. In general, the strain gauge only measures the change of strain and stress due to loading unless it has been fixed in the steel structure before the steel is stressed. Until now, there are no practical non-destructive methods for measuring residual stress. The hole drilling strain gauge method can be used but destructive in nature. To date, the non-destructive stress measurement of prestressed steel has not yet been established after the steel has been stressed. Therefore, the purpose of this project is to develop the non-destructive residual stress measurement technique for prestressed steel by using resistance measurement as a tool for determining the stress value. Experimental tests were carried out to find a relationship between stress and resistance for three types of steel such as prestressing steel wire, prestressing steel strand and high tensile steel plate. The stress and resistance relationships obtained from the experiment have been analyzed by using statistical analysis. It was found that resistance in the prestressed steel is proportional to the applied stress. Based on the stress and resistance relationships obtained from the three types of steel specimens, a software was develop by using Visual Basic to compute the stress value for the measured resistance in the prestressed steel. For the time being, the resistance value is keyed in but should later be able to be improved, so that it will read directly from the interfacing circuit

Low Power CMOS Electrocardiogram Amplifier Design for Wearable Cardiac Screening

The trend of health care screening devices in the world is increasingly towards the favor of portability and wearability. This is because these wearable screening devices are not restricting the patient’s freedom and daily activities. While the demand of low power and low cost biomedical system on chip is increasing in exponential way, the front-end electrocardiogram (ECG) amplifiers are still suffering from flicker noise for low frequency cardiac signal acquisition, 50Hz power line electromagnetic interference, and the large unstable input offsets due to the electrode-skin interface is not attached properly. In this paper, a CMOS based ECG amplifier that suitable for low power wearable cardiac screening is proposed. The amplifier adopts the highly stable folded cascode topology and later being implemented into RC feedback circuit for low frequency DC offset cancellation. By using  0.13µm CMOS technology from Silterra, the simulation results show that this front-end circuit can achieve a very low input referred noise of  1pV/Hz1/2 and high common mode rejection ratio of 174.05dB. It also gives voltage gain of 75.45dB with good power supply rejection ratio of 92.12dB. The total power consumption is only 3µW and thus suitable to be implemented with further signal processing and classification back end for low power wearable biomedical device

Machine vision based smart parking system using Internet of Things

It is expected that in the next decade, majority of world population will be living in cities. Better public services and infrastructures in the city are needed to cope with the booming population. City vehicles that cruising for parking have indirectly causing traffic, making one harder to travel around the city. Thus, a smart parking system can certainly lays the foundation to build a smart city. This paper proposed a cost-effective IoT smart parking system to monitor city parking space and provide real-time parking information to drivers. Moreover, instead of the conventional approach that uses embedded sensors to detect vehicles in the parking area, camera image and machine vision technology are used to obtain the parking status. In the prototype, twenty outdoor parking lots are covered using a 5 megapixel camera connected to Raspberry Pi 3 installed at the 5th floor of the nearby building. Machine vision in this project that involved motion tracking and Canny edge detection are programmed in Python 2 using OpenCV technology. Corresponding data is uploaded to an IoT platform called Ubidots for possible monitoring activity. An Android mobile application is designed for user to download real-time data of parking information. This paper introduces a low cost smart parking system with the overall detection accuracy of 96.40%. Also, the mobile application allows users to alert other car owners for any emergency incidents and double parking blockage. The developed system can provide a platform for users to search for empty car parking with ease and reduce the traffic issues such as illegal double parking especially in the urban area

LED based soil spectroscopy

Soil is a medium for plant roots to grow, absorb water and necessary solutes for growth. Soil macronutrient testing is helpful for determining the nutrient content in soil before applying fertilizer for quality and process controls of agricultural productivity and soil fertility. Spectroscopy is an emerging technology which is rapid and simple has been widely used in agricultural and food analysis processes. The capability of spectroscopy to characterize material from the transmission or absorbance has been used in this paper to measure nitrogen ( N ), phosphorus ( P ) and potassium ( K ) content in organic soil. The paper details preliminary characterization of soil spectroscopy with a Deuterium - Halogen lamp and spectrometer to measure the absorbance level of the macronutrients. The extracted nutrients were mixed with the colour reagent and specific colour ed solution was developed. The result shows high absorbance level for N and P are at 970 nm in wavelength. In addition, N gi ve absorbance at wavelength 450 nm and P yield absorbance at 800 nm wavelength . K was measured high at 620 nm. Further experiments were conducted to measure the absorbance characteristic of N , P and K for 20 minute period. The result shows that P and K has constant value of absorbance for 20 minutes duration while N , have stable absorbance value after 10 minutes being illuminated by 470 nm blue light - emitting diode ( LED ) . For future works, the optical measurements will be implemented using visible and near infrared LED and the photodetector in order to replace the spectrometer usage for soil spectroscopy. This would lead to achieve the primary objective of this research in developing a simple and low cost spectroscopy uses LED

Implementation of optimized low pass filter for ECG filtering using verilog

Electrocardiogram is a standard method used for the diagnosis of heart related disease. QRS complex plays an important role in Electrocardiogram signal processing since it is the prominent feature of Electrocardiogram signal. One of the important modules in the QRS detection algorithm is filtering. Electrocardiogram signal is processed to filter out unwanted signal through digital filtering. The main objective of this paper is to compare the resource utilization of hardware realization consumed between Direct Form I structure and Direct Form II structure. In this work, Infinite Impulse Response low pass filter to remove high frequency noise is designed with a passband frequency and stopband frequency of 5 and 25 Hz respectively. The designed filter is verified using Matlab Filter Design Analysis tool and realized in hardware using Verilog. Both the results show that the unwanted signals in the raw ECG signal are attenuated through the designed filter. The resource utilization result shows improvement with optimized Direct Form II implementation. The amount of look up tables, flip flop and digital signal processing used with Direct Form II structure shows a reduction to 0.26%, 0.12% and 2.50% respectively compared to 1.17%, 0.20%, 2.92% of utilization with Direct Form I structure

A low cost spectroscopy with Raspberry Pi for soil macronutrient monitoring

Soil spectroscopy measurement is widely used to determine the macronutrients content in the soil. Spectrometer is costly equipment and commonly used to determine the transmittance, absorbance or reflectance level of various liquids and opaque solids by measuring the intensity of light as a light source passes through a sample chemical substance. This paper is reported on a low cost experimental assessment of soil macronutrient for soil spectroscopy utilizing Raspberry Pi (RPI) module in visible and near-infrared (NIR) wavelength. The sensitivity measurements are mainly due to the concentration level and the intensity of light emitting diode (LED) light source. The work is focusing on the absorbance spectroscopy particularly on linear relationship to determine the Nitrogen (N), Phosphorus (P) and Potassium (K) content level in soil using colour-developing reagent. The development of low cost and portable RPI based spectrophotometer has created new possibilities to measure the concentration level of the existed soil macronutrient within visible and infrared light wavelength of light sources. The absorbance of light was computed based on Beer-Lambert Law. The low cost RPI based spectrometer costs 80% less than the spectrometer available in the market and is capable of recording the absorbance measurements up to 5 samples. The performance of this prototype shows that it is possible to build the spectrometer using open-source software and hardware by considering the limiting factors such as light transfer to the sample, spectral filtering and the sensitivity due to the signal-to-noise ratio

Uric acid detection in visible spectrum

The measurement of uric acid based on the optical absorption at visible light spectrum is investigated and tested. Sensing in the visible region was conducted for determination of suitable wavelength that produces high sensitivity and accuracy performance based on the Beer-Lambert law calculation. In this work, the uric acid is detected by detecting sodium urate as a product of chemical reaction between uric acid with sodium hydroxide buffer. The setup has been tested for uric acid concentration ranging from 15 mg/dL to 85 mg/dL. Three wavelengths have been analyzed which are 460 nm, 525 nm and 630 nm. Measured data at 460nm wavelength exhibits the highest sensitivity, which is 0.0012 (mg/dL)-with 86.51% accuracy. Detection of uric acid at visible light spectrum offers a low-cost sensor based on visible LEDs and photodiode is possible to be realized

Large signal model of heterojunction bipolar transistor InP/InGaAs as an optoelectronic mixer

A large-signal model of InP/InGaAs single Heterojunction Bipolar Transistor (HBT) has been developed considering spectral performance and mixing. This model is based on Gummel Poon BJT model. HBT InP/InGaAs has been modeled and analyzed in this paper as an optoelectronic mixer (OEM). The HBT proposed was simulated by considering the wavelength of 1310 nm for an up-conversion frequency of 30 GHz. Its characteristics was further investigated to develop the appropriate structure device for OEM application. This proposed HBT InP/InGaAs can be potentially implemented in the broadband Radio over Fiber (RoF) system to perform photodetection and frequency up-conversio

Raspberry pi bassed spectroscopy

Raspberry Pi (RPI) is a tiny single-board computer which can be fitted into a box along with photo-detecting circuits to build an affordable spectrometer. The Tkinter (TK) graphic user interface (GUI) written in Python (PY) displays the output voltage, power and absorbance of light. A Raspberry Pi based (RPI) spectrometer was developed to measure the ability of chemical substance to absorb light by measuring the power of light as a light source passed through a sample chemical substance. This method can be used to measure the concentration of the soil nutrients in a soil extract. The higher the concentration of the soil nutrients of a soil extract, the higher the light absorbance of a sample. The absorbance of light was computed based on Beer- Lambert Law. The low cost RPI based spectrometer costs 80% less than the spectrometer available in the market and is capable of recording the absorbance measurements up to 5 samples. The performance of this prototype shows that it is possible to build the spectrometer using open-source software and hardware

A linear array passively quenched single photon avalanche diode

The integrated circuit design of Single Photon Avalanche Diode (SPAD) with quenching circuit in CMOS is highly desirable photon detection at high rates, but low counting rates constrain image acquisition rates and dynamic range. The characterization should primarily define the dead time of quenching SPAD circuit in order to estimate the SPAD performance prior fabrication. This paper reports the development and characterization of the mathematical model SPAD on passively quenched SPAD circuit with ballast resistor. An improved model in defining the dead time (tD) response for SPAD is used to characterize the performance of 8×1 passively quenched SPAD array. The time response for both quenching and recharging time are developed for 180 nm depletion layer which means low voltage technology. Hence that, the 8×1 passively SPAD array circuit is designed by using Silterra 180nm CMOS technology for uncorrelated time measurements with on-chip 4-bit counter to improve the counting rate. The passive quenching circuit design on-chip would enable the capability to perform at higher speed, which is more than 100 kHz. In addition, are presented in this paper